WO2006101375A1 - Visual stethoscope - Google Patents

Visual stethoscope Download PDF

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Publication number
WO2006101375A1
WO2006101375A1 PCT/KR2006/001101 KR2006001101W WO2006101375A1 WO 2006101375 A1 WO2006101375 A1 WO 2006101375A1 KR 2006001101 W KR2006001101 W KR 2006001101W WO 2006101375 A1 WO2006101375 A1 WO 2006101375A1
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WO
WIPO (PCT)
Prior art keywords
signals
unit
sound
output
set forth
Prior art date
Application number
PCT/KR2006/001101
Other languages
French (fr)
Inventor
Kee Young Park
Original Assignee
Sunmeditec Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020050024678A external-priority patent/KR100669532B1/en
Priority claimed from KR20-2005-0008908U external-priority patent/KR200388387Y1/en
Application filed by Sunmeditec Co., Ltd. filed Critical Sunmeditec Co., Ltd.
Publication of WO2006101375A1 publication Critical patent/WO2006101375A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00—Instruments for auscultation
    • A61B7/02—Stethoscopes
    • A61B7/04—Electric stethoscopes

Definitions

  • the present invention relates generally to a visual stethoscope and, more particularly, to a visual stethoscope which amplifies and filters received thoracic and heart sounds, and then stores or audibly outputs the waveform of the thoracic and heart sounds through a Universal Serial Bus (USB) transmission path terminal using a biomedical signal analysis algorithm.
  • USB Universal Serial Bus
  • the traditional analog stethoscope invented by Laennec in 1819, is a stethoscope including a chestpiece part, an earpiece part, and a tube connecting the chestpiece part and the earpiece part .
  • the traditional analog stethoscopes and the recent electronic stethoscopes allow only physicians to listen to thoracic and heart sounds, so that the frequency of misdiagnosis is relatively high due to the physicians' subjective assessment, and patients and their guardians cannot listen to the sounds through the stethoscopes, thereby- resulting in one-sided diagnosis.
  • an object of the present invention is to provide a visual stethoscope which is capable of storing and playing received biomedical signals through a USB transmission path.
  • Another object of the present invention is to provide a visual stethoscope which can convert diagnosis data into digital signals and put them into a database, thereby transmitting the diagnosis data to a remote location.
  • Still another object of the present invention is to provide a visual stethoscope which is capable of making objective and reliable diagnosis based on a thoracic and heart sound database and diagnostic software at the time of diagnosis .
  • Still another object of the present invention is to provide a visual stethoscope which prevents physicians' acoustic disturbance and ear pain attributable to the use of the stethoscope.
  • Still another object of the present invention is to provide a visual stethoscope in which a microphone is mounted within a cavity above a sound collection hole which is the inside of a head, and the periphery of the microphone is wrapped with a soundproof rubber member, so that the loss of sounds collected through the sound collection hole and the flow of noise are prevented, thereby clearly and precisely collecting thoracic and heart sounds.
  • the present invention provides a visual stethoscope including a sound collector for collecting biomedical signals generated from a human body and converting them into electric sound signals; a controller for receiving and amplifying thoracic and heart sounds output from the sound collector, performing filtering with respect to a predetermined frequency, or performing data conversion and processing, and outputting them,- and an output unit for receiving signals output from the controller, and outputting the signals as sound, or diagnosing, analyzing and displaying the signals using a predetermined algorithm.
  • the controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a second amplification unit for amplifying the biomedical signals output through the super low-pass filter; and an audio unit for passing only certain frequency band signals of the amplified biomedical signals through a predetermined filter.
  • the output unit is sound output unit for receiving signals output through the audio unit and converting them into sound signals.
  • the audio unit includes a signal detection circuit for detecting thoracic and heart sounds from the second amplification unit; and a low-pass filter for eliminating noise by passing certain frequency band signals of the signals from the signal detection circuit therethrough.
  • the controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an Analog-to-Digital (A/D) conversion unit for converting the sampled and held analog signals into digital signals; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; and a Universal Serial Bus (USB) transmission path terminal for delivering signals from the digital signal processing unit to external output unit .
  • A/D Analog-to-Digital
  • the output unit is a computer that is connected to the USB transmission path terminal of the controller, receives signals output through the USB transmission path terminal and diagnoses and analyzes them using the predetermined algorithm.
  • the controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an A/D conversion unit for converting the sampled and held analog signals into digital signals; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; a Digital-to-Analog (D/A) conversion unit for converting outputs from the digital signal processing unit into analog signals and outputting them; and signal volume control unit for controlling amplitudes of signals from the D/A conversion unit and outputting the signals to external output unit.
  • D/A Digital-to-A
  • objective diagnosis is possible because a patient and his or her guardian can listen to thoracic and heart sounds, also can see the waveform of the data at the time of diagnosis, and reliable diagnosis is possible because clinical data and a medical prescription based on a thoracic and heart sound database and diagnostic software are generated.
  • FIG. 1 is a block diagram illustrating a visual stethoscope according to the present invention
  • FIG. 2a is a block diagram illustrating a first embodiment of the visual stethoscope of FIG. 1;
  • FIG. 2b is a block diagram illustrating a second embodiment of the visual stethoscope of FIG. 1;
  • FIG. 2c is a block diagram illustrating a third embodiment of the visual stethoscope of FIG. 1;
  • FIG. 3 is a circuit diagram illustrating the ⁇ r-type filter and inverted L-type filter of the visual stethoscope according to the present invention;
  • FIG. 4 is a sectional view illustrating the sound collector of the assembled stethoscope according to the present invention.
  • FIG. 5 is a block diagram illustrating the execution of a biomedical signal analysis program according to the present invention.
  • FIG. 6 is a waveform diagram illustrating the sampling and holding method of the visual stethoscope according to the present invention.
  • FIG. 7 is a diagram illustrating a screen capture of a biomedical signal analysis and diagnosis program.
  • FIGS . 8a to 8d are waveform diagrams illustrating clinical diagnosis graphs taken using the biomedical diagnosis program of FIG. 7.
  • FIG. 1 is a block diagram illustrating a visual stethoscope according to an embodiment of the present invention, which includes a sound collector 100, a controller
  • the controller 200 includes a first amplification unit 211, a super Low Pass Filter (LPF) 213, a second amplification unit 215, an audio unit 217, a signal input interface 231, an automatic gain control unit 233, a sampling and holding unit 235, an analog-to-digital conversion unit 237, a digital signal processing unit 239, a digital-to- analog conversion unit 241, a signal volume control unit 243, and a USB transmission path terminal 251.
  • LPF super Low Pass Filter
  • the controller 200 can have various types of external devices 300, 400 and 500 connected thereto, and may connect the sound output unit 300, such as earphones or a speaker which allows a physician to directly listen to the diagnostic sounds of a patient, to the output terminal of the audio unit 217, the speaker output unit 400, such as a speaker capable of allowing a general person to listen to a voice signal for diagnosis to the signal volume control unit 243, and a computer, such as a personal computer or a notebook, to the USB transmission path terminal 251.
  • the sound output unit 300 such as earphones or a speaker which allows a physician to directly listen to the diagnostic sounds of a patient
  • the speaker output unit 400 such as a speaker capable of allowing a general person to listen to a voice signal for diagnosis to the signal volume control unit 243
  • a computer such as a personal computer or a notebook
  • the controller 200 it is possible to divide the controller 200 into 3 functional blocks, first, an sound processing unit 210 including the first amplification unit 211, the super LPF 213, the second amplification unit 215, and the audio unit 217, as illustrated in FIG. 2a, second, a voice processing unit 230 including the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, the digital- to-analog conversion unit 241, and the signal volume control unit 243, as illustrated in FIG.
  • a digital communication unit 250 including the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, and the USB transmission path terminal 251 as illustrated in FIG. 2c.
  • the sound collector 100 collects biomedical (thoracic and heart) signals generated from a human body, and converts them into electric signals, that is, in detail, collects sounds or biomedical signals generated from the thoracic and heart of the human body and transmits them to the controller 210.
  • the controller 210 includes the first amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the second amplification unit 215 for amplifying the biomedical signals output from the super LPF 213, and the audio unit 217 for eliminating noises by passing only certain frequency band signals of the biomedical signals which are amplified and then are output as described above, using a predetermined filter.
  • the super LPF 213 is set to 1.0 kHz, and therefore, cuts off frequencies above 1.0 kHz.
  • the audio unit 217 includes a signal detection circuit 218 and a low-pass filter 219, functions to eliminate some unfiltered high frequency signals from signals resulting from the output of biomedical signals passed through the super LPF 213, and prevents the high frequencies from modifying original signals that are biomedical signals .
  • the sound output unit 300 connected to the audio unit 217 enables a physician to monitor and listen to the diagnosis sounds of a patient, and includes earphones or a speaker which can output signals from the audio unit 217 as sound signals.
  • the low-pass filter 219 is formed of a 7r-type filter and an inverted L-type filter, as illustrated in FIG. 3.
  • the ⁇ - type filter eliminate some unfiltered high frequency signals from signals resulting from the output of thoracic and heart sound signals passed through the super LPF 213 and prevents the high frequencies from modifying the original signals of thoracic and heart sounds.
  • the inverted L-type filter is formed of an inductor L and a capacitor C which eliminates high frequency components again, and reproduces the original signals .
  • FIG. 2b is a block diagram illustrating the second embodiment of the controller according to the present invention, which includes the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, the digital-to-analog conversion unit 241, the signal volume control unit 243 and the speaker output unit 400 as illustrated.
  • the sound collector 100 is a sound collection head which functions to collect biomedical signals generated from a human body and converts them to electric signals, that is, which collects sounds or biomedical signals (thoracic and heart) generated from the chest of the human body and transmits them to the controller 200.
  • the controller 200 includes the first amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the signal input interface 231 for transmitting the biomedical signals output through the super LPF 213 to the automatic gain control unit 233, the automatic gain control unit 233 for maintaining or controlling the biomedical signals transmitted through the signal input interface in a state close to that of original signals, the sampling and holding unit 235 for sampling and holding signals from the automatic gain control unit 233, the A/D conversion unit 237 for converting the sampled and held analog signals into digital signals, the digital signal processing unit for performing encoding/decoding, voice detection, noise control, and signal compression and decompression functions, the D/A conversion unit 241 for converting the outputs of the digital signal processing unit into analog signals and outputting them, and the signal volume control unit for controlling the amplitude of the output signals from the D/A conversion unit 241.
  • the automatic gain control unit 233 upwardly amplifies signals the amplitude of which is small, and attenuates signals the amplitude of which is large, thereby always causing signals having constant amplitude to be output.
  • the sampling and holding unit 235 performs a sampling operation through a sampling circuit having a frequency above 2.0 kHz in order to generate non-continuous data and a holding operation of latching the digital signals and maintaining the values thereof, as illustrated in FIG. 6.
  • the A/D conversion unit 237 and the D/A conversion unit 241 have performance higher than that corresponding to a Total Harmonic Distortion (THD) of 0.01% and a Signal-to-Noise Ratio (SNR) of 96dB.
  • THD Total Harmonic Distortion
  • SNR Signal-to-Noise Ratio
  • the THD corresponds to a reproduction precision value equal to or smaller than 0.01%, which is the reproduction value of thoracic and heart sounds with respect to their original signals
  • the SNR of 96 dB is a value exhibiting an optimal separation rate, which is a ratio of thoracic and heart sound signals to noise of approximately 100,000 to 1.
  • the signal volume control unit 234 is a module for setting a bias in the pre-stage with respect to the analog signals from the D/A conversion unit 241 in order to listen to un-distorted thoracic and heart sounds through a speaker or earphones, and functions to adjust only the amplitude of amplified thoracic and heart sounds using variable resistors and maintain the frequency thereof, thereby controlling an amplification level .
  • the speaker output unit 400 is preferably a speaker capable of outputting signals from the signal volume control unit 243 as sound signals .
  • FIG. 2c is a block diagram illustrating the third embodiment of the digital stethoscope according to the present invention.
  • the digital stethoscope includes the sound collector 100, the amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the A/D conversion unit 237, the digital signal processing unit 239, and a computer 500.
  • the sound collector 100 is a sound collection head which collects biomedical signals generated from a human body, and converts them into electric signals, and, in detail, collects sounds or biomedical (thoracic and heart) signals generated from the chest of the human body and transmits them to the controller 200.
  • the controller 200 includes the amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the signal input interface 231 for transmitting the biomedical sounds output through the super LPF 213 to the automatic gain control unit 233, the automatic gain control unit 233 for maintaining or controlling the biomedical signals transmitted through the signal input interface in a state close to that of the original signals, the sampling and holding unit 235 for sampling and holding signals from the automatic gain control unit 233, the A/D conversion unit 237 for converting the sampled and held analog signals into digital signals, the digital signal processing unit 239 for performing encoding/decoding, and signal compression and decompression functions, and the USB transmission path terminal 251 connected to the external computer 500 through a predetermined cable.
  • the amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100
  • the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough
  • the computer 500 includes a USB transmission path terminal 511 which is connected to the USB transmission path terminal 251 of the controller 200 and receives signals output through the digital signal processing unit 239, and a circuit unit which diagnoses and analyzes signals received through the USB transmission path terminal 511 using a predetermined algorithm.
  • the signals transmitted to the digital signal processing unit 239 are buffered in Read Only Memory (ROM) and Random Access Memory (RAM) , which are separate auxiliary memory units embedded in the computer 500, through the USB transmission path terminal 511, or are displayed on a liquid crystal display screen by inputting the signals to a biomedical signal diagnosis and analysis program stored in the computer 500.
  • ROM Read Only Memory
  • RAM Random Access Memory
  • the digital signals of thoracic and heart sounds through the USB transmission path terminal 511 are preferably received or transmitted in the form of a DOWN & UP STREAM, 16Bit MONO STElEAM or 24Bit STREAM, and the sampling bit rate thereof may be changed in the range of 6.4 to 48kHz.
  • a battery be used as the power supply of the controller 200, and that the battery be automatically charged through the USB transmission path terminal 511 when the controller 200 is connected to the USB transmission path terminal 511 of the computer 500.
  • the controller 200 does not require a separate power supply because it uses the power supplied from the computer 500 through the USB transmission path terminal.
  • an embedded battery (3.6V Ni-cd) is charged, but it is possible to use the visual stethoscope in the form of a conventional analog stethoscope comprising a separate embedded battery (3.6V Ni-cd) when the visual stethoscope is used as an analog stethoscope.
  • the sound collector for the stethoscope of these embodiments includes a body 110, a diaphragm 130, a microphone 140, a cap 150 and a cable 170 as illustrated in FIG. 4.
  • the body 110 is formed in an approximately inverted funnel shape.
  • a first sound collection plate 111 having a lampshade shape is placed in the lower portion of the body 110 so as to have a wide opening.
  • a sound collection hole 115 having a narrow passage shape is formed above the center of the opening.
  • a wide cavity is formed above the upper end of the sound collection hole 115.
  • reference numeral 113 designates a second sound collection plate projecting toward the diaphragm 130 from the inner surface of the first sound collection plate 111, which is shaped in a ring from.
  • the second sound plate 113 When, during diagnosis, a physician move after bringing the first sound collection plate 111 into contact with the chest of a human body, sounds (frictional sounds) caused by such contact are directly delivered to the second sound collection plate 113 through a sound collection hole 115, so that loud echo and noise occur.
  • the second sound plate 113 is mounted, which functions to isolate external noises and frictional sounds caused by such contact, and directly delivers the thoracic and heart sounds of the chest.
  • the second sound collection plate 113 adheres to the skin of the human body due to the contact with the skin and pressure on the human body, so that a vibration phenomenon disappears . The disappearance of the vibration due to the contact and pressure of the skin is prevented by mounting the second sound collection plate 113.
  • the body is made of plastic material, rather than metal material.
  • plastic material rather than metal material. The reason for this is that it is possible to prevent a patient from feeling unpleasant and discomfort or fear due to the coolness of the body 110 when it contacts the skin of the patient because the heat retention of plastic material is better than that of metal material.
  • the diaphragm 130 is connected to the lower end of the opening and is constructed to generate predetermined vibration depending on sounds generated from the object of diagnosis.
  • the microphone 140 is inserted into a cavity formed on the upper end of the sound collection hole 115 and is constructed to amplify sounds input through the sound collection hole 115.
  • the cap 150 is screwed to the outer surface of the cavity and supports the body 110, into the center of an end of which a soundproof molding member 160 is inserted.
  • the cable 170 is inserted into the center of the molding member 160 , is constructed to connect with an output terminal formed on the upper end of the microphone 140, and deliver amplified sound signals from the microphone 140.
  • a buffer rubber member 141 which prevents the flow and generation of noise is inserted between the cavity of the body 110 and the outer surface of the microphone 140, and a ring soundproof rubber member 145 is inserted between the edge of the upper end of the microphone 140 and the molding member 160, thereby protecting sounds flowing through the sound collection hole 115 and the microphone 140.
  • the body 110 and diaphragm 130 are connected to each other through a predetermined engagement member 120.
  • the engagement member 120 is a rubber ring having a cross- section approximately shaped in a "] " form, and is secured into a groove formed along the edge of the body 110 and the lower surface of the diaphragm 130, thereby engaging the body 110 with the diaphragm 130.
  • a bolt is formed on the outer surface of the cavity of the body 110 and a nut matching the bolt is formed on the inner surface of the cap 150. That is, the diaphragm 130 converts sounds from the chest into vibration.
  • the sound collection hole 115 collects variations in the vibrations received from the diaphragm 130 into the hole, thereby collecting thoracic and heart sounds.
  • the engagement member 120 holds the diaphragm 130 closed to the lower surface of the edge of the first sound collection plate 111.
  • the body 110 collects sounds through the diaphragm 130 and the opening, and has an optimal sound collection structure when the inner angle with respect to the diaphragm 130 is approximately 10° to 12°.
  • the size of the sound collection hole 115 is approximately 3.0 ⁇ to 3.5 ⁇ . The sounds due to resonance
  • the sound collection hole 115 which is defined as Q (representing the relationship between the repetition (frequency) of vibrations and the degree of amplification with respect to a predetermined time at a point) .
  • Q representing the relationship between the repetition (frequency) of vibrations and the degree of amplification with respect to a predetermined time at a point
  • Q value is optimal, thoracic and heart sounds can be best heard without echoes.
  • the size of the sound collection hole 115 must be appropriately adjusted depending on whether a patient is a child or an adult.
  • the cap 150 is a fastener for securing the body 110 so that it does not move, and is gripped by a physician upon auscultation.
  • the microphone 140 is provided to convert sounds from a sound collector into electric signals.
  • the buffer rubber member 141 is a stand for protecting the microphone 140 in order to prevent the microphone 140 and the hole from being modified.
  • the molding member 160 receives and supports the cable 170 in the inner hollow thereof, and is a piece of rubber which prevents noise from flowing from the outside and directly delivers signals from the sound collection hole 115 and the microphone 140.
  • the ring rubber member 145 protects sounds which flow through the sound collection hole 115 and the microphone 140.
  • the cable is a connection line for delivering sounds (thoracic and heart) received from the microphone as electric signals . As described above, the cavity is formed above the upper end of the body 110 of the head, and then the microphone is mounted thereon, so that it is possible to sufficiently amplify even weak vibration sounds of the diaphragm 130 using the microphone 140.
  • the microphone 140 is mounted on the upper end of the sound collection hole 115, so that it is possible to amplify the thoracic and heart signals with fidelity. Furthermore, it is possible to sufficiently detect not only high frequencies but also low frequencies using a single diaphragm 130.
  • the buffer rubber member 141 is inserted between the microphone 140 and the cavity of the body 110, so that it is possible to protect the microphone 140 and cut off sound waves leaking through the sound collection hole 115.
  • the ring rubber member 145 is located between the upper end of the microphone 140 and the molding member 160, so that the leakage of sounds from the sound collection hole 115, and the flowing of noise can be prevented and the microphone 140 is protected, thereby increasing the ability to collect and detect the sounds of a human body through the sound collection hole 115.
  • the above-described sound collector directly connects to the controller 200 for analyzing thoracic and heart sounds by connecting a stereo jack, rather than earpieces, to one end of the cable 170, so that self-diagnosis by a general person is possible without the diagnosis of a physician, and, furthermore, a patient as well as a physician can directly listen to his or her own thoracic and heart sounds also to see the data or monitor the results after analysis by an analysis program using a graph through a thoracic and heart sound analysis controller.
  • FIG. 5 is a block diagram illustrating the execution of a thoracic and heart sound diagnosis and analysis program within a computer according to the present invention.
  • biomedical signals such as, auscultatory sounds received from the sound collector 100, blood pressure, body temperature, respiratory rate, and oxygen saturation, are delivered to the computer 500 through the USB transmission path terminal 511.
  • a biomedical diagnosis algorithm is installed in the computer 500, so that processing of thoracic and heart sound data collected by the sound collector 100 and the display thereof are possible, and, with respect to the biomedical signals received through the USB transmission path terminal 511, the logarithmic energy level crossing rate of each of the biomedical signals is analyzed using a predetermined biomedical signal analysis algorithm included in a fast Fourier transformation (FFT) unit and a Logarithmic energy level Crossing Rate (LCR) calculation unit 515, and is displayed on a monitor 519.
  • FFT fast Fourier transformation
  • LCR Logarithmic energy level Crossing Rate
  • the monitor 519 is implemented using a touch screen, so that the operation of the monitor is easy, and, thus, there is an advantage of shortening diagnosis time.
  • the thoracic and heart sound signals are information about analog thoracic and heart sounds input continuously as time elapses .
  • the digitization of the analog thoracic and heart sounds is required, and in order to overcome the limitation of hardware resource, the lossless compression of the thoracic and heart sound information is required.
  • the compression of thoracic and heart sound information serves to delete redundant information from signals and to store the signals.
  • a predetermined width of analysis interval (where hanning window 512 is optimal) is, defined with respect to input voice, the characteristics of the sounds in the interval are analyzed, and results based on the analysis are used or utilized.
  • the logarithmic energy level crossing rate is calculated by the logarithmic energy level crossing rate calculation unit 515 embedded in the computer using Equation 1 as follows :
  • TH is a threshold value, and is determined by the characteristic of the input signal and various examination results. Since the determination of the threshold value and a large amount of calculation are problems, it is assumed that the value of TH is not always constant, and the value of TH is determined by observing variation in the characteristics of the input signal and using the average characteristic of the input signal. That is, the threshold value is determined by input variables .
  • the threshold value which is experimentally used for the detection of signals is fixed, so that a threshold value that varies depending on the situation is determined, a biomedical signal interval is detected by performing FFT on voice data and using the sum of energies of 20Hz ⁇ 4kHz, the LCR and whether energy level continues to increase.
  • biomedical signals such as auscultatory sounds, blood pressure, body temperature, respiratory rate, and oxygen saturation, received from the sound collector 100, are delivered to the computer 500 through the USB transmission path terminal 511.
  • a biomedical diagnosis algorithm is installed in the computer 500, so that the processing of thoracic and heart sound data collected by the sound collector 100 and the display thereof are possible, and the thoracic and heart sounds transmitted through the USB transmission path terminal 511 are passed through the harming window 513, thereby generating predetermined data required for diagnosis and analysis.
  • the logarithmic energy level crossing rate of each of the biomedical signals which are transmitted to the computer 500 is analyzed using a predetermined biomedical signal analysis algorithm included in the fast Fourier transformation (FFT) unit and the logarithmic energy level crossing rate calculation unit 515, and is displayed on a monitor 519.
  • FFT fast Fourier transformation
  • the monitor 519 is implemented using a touch screen, so that the manipulation of the monitor is easy, and, thus, there is the advantage of shortening diagnosis time.
  • the computer 500 receives biomedical signals, such as auscultatory sounds, blood pressure, body temperature, respiratory rate and oxygen saturation, which are transmitted through the USB transmission path terminal 511, analyzes the biomedical signals using a numerical display algorithm 517 related to blood pressure, body temperature, respiratory rate or the like, and displays a corresponding numerical value on the monitor 519 in which the touch screen function is implemented.
  • biomedical signals such as auscultatory sounds, blood pressure, body temperature, respiratory rate and oxygen saturation
  • FIG. 7 is a diagram illustrating a screen capture of a biomedical signal analysis and diagnosis program. The functions of respective parts are described with reference to FIG. 7 below.
  • Reference character (D designates a button used to record thoracic and heart sounds
  • reference character (b designates a button used to play thoracic and heart sounds
  • reference character ⁇ designates a button used to play only the waveform ® of the enlarged time interval of selected thoracic and heart sounds
  • reference character (d) designates a button used to stop the recording or playing of thoracic and heart sounds
  • reference character ⁇ designates an open button used to load the database of thoracic and heart sounds
  • reference character (D designates a storage button used to store the content of thoracic and heart sounds.
  • reference character (D designates a window used to write the name of a patient
  • reference character (K) designates a window used to write the unique number or social identification number of a patient
  • reference character ⁇ designates a window used to write the file (including year, month, day, time, and file name) of a recorded database when the database of thoracic and heart sounds is recorded as another name or when thoracic and heart sounds are stored
  • reference character ⁇ designates a window used to display the temperature of a patient
  • reference character ® designates a window used to display the maximum and minimum values of the blood pressure of a patient
  • reference character CD designates a window used to display the pulse rate of a patient
  • reference character ⁇ designates a window used to display oxygen saturation Sp ⁇ 2
  • ® designates a window used to display the LCR values (bronchial trouble, pneumonia and asthma, determined based on the LCR values) of a diagnosis algorithm
  • reference character ® designates a window used to display a record level when thora
  • reference character (D designates a window represented by dragging a part to be viewed in detail among the overall thoracic and heart sounds ⁇ using a mouse
  • reference character ⁇ designates the overall thoracic and heart sounds displayed (recorded) when thoracic and heart sounds are load from a database or diagnosed
  • reference character ⁇ designates the enlarged waveform of original sounds, in which the designated interval ® of the overall thoracic and heart sounds displayed in ⁇ is enlarged
  • reference character ⁇ designates a spectrogram (the frequency of which is 1.0kHz and 1.0-2.OkHz) displayed with respect to the designated interval (P) of the overall thoracic and heart sounds displayed in ⁇ .
  • ⁇ and ⁇ are screens of FIGS . 8a to 8d in which waveforms and spectrograms corresponding to biomedical signals are captured as clinical diagnosis graphs detected using a biomedical program (algorithm) .
  • FIG. 8a is a diagram illustrating waveform of the normal respiratory rate of a healthy person
  • FIG.8b is a diagram illustrating waveform of the abnormal respiratory rate of an unwell person, such as an asthma patient
  • FIG. 8c is a diagram illustrating a mild asthma state
  • FIG. 8d is a diagram illustrating a moderate asthma state .
  • Reference character ⁇ designates waveform representing some portion of the overall waveform.
  • the present invention can transmit thoracic and heart sounds directly from the USB transmission path terminal 511 to a speaker or earphones, that is, the speaker output unit 400, through the D/A conversion unit 241 and the signal volume control unit 243 capable of controlling the amplitude of signals, when a physician, and a patient or an intern want to simultaneously listen to the thoracic and heart sounds and visualize the thoracic and heart sounds at the time of diagnosis, unlike the above-described embodiments.
  • the visual stethoscope collects biomedical signals (thoracic and heart sounds) , and enables visualization of and listening to thoracic and heart sounds, which are output from a sound collector using a biomedical signal diagnosis program through a USB transmission path, using a liquid crystal display and earphones or a speaker. Furthermore, the visual stethoscope can store thoracic and heart sounds as digital data using a biomedical signal diagnosis algorithm, and can store the personal information of a patient and the clinical records of a physician.
  • the digital data is associated with a database, the biomedical signal diagnosis algorithm and a separate diagnostic database, so that the most probable name of a disease can be provided. It is possible to make objective diagnosis based on statistics using the database, and to implement a visual stethoscope system using a USB transmission path, which is high value-added.
  • objective diagnosis is possible because a patient and his or her guardian can listen to thoracic and heart sounds, also can see the waveform of the data at the time of diagnosis, and reliable diagnosis is possible because clinical data and a medical prescription based on a thoracic and heart sound database and diagnostic software are generated.
  • the thoracic and heart sound database is shared between physicians, there are advantages in that quality of medicine is improved and the thoracic and heart sound database is provided in various information formats for the future management and treatment of a patient.

Abstract

Disclosed herein is a visual stethoscope in which objective diagnosis is possible because a patient and his or her guardian can listen to thoracic and heart sounds also can see the waveform of the data at the time of diagnosis, and reliable diagnosis is possible because clinical data and a medical prescription based on a thoracic and heart sound database and diagnostic software are generated. The visual stethoscope includes a sound collector, a controller and an output unit. The sound collector collects biomedical signals generated from a human body and converts them into electric sound signals. The controller receives and amplifies thoracic and heart sounds output from the sound collector, performs filtering with respect to a predetermined frequency, or performs data conversion and processing, and outputs them. The output unit receives signals output from the controller, and outputs the signals as sound, or diagnoses, analyzes and displays the signals using a predetermined algorithm.

Description

[invention Title]
VISUAL STETHOSCOPE
[Technical Field]
The present invention relates generally to a visual stethoscope and, more particularly, to a visual stethoscope which amplifies and filters received thoracic and heart sounds, and then stores or audibly outputs the waveform of the thoracic and heart sounds through a Universal Serial Bus (USB) transmission path terminal using a biomedical signal analysis algorithm.
[Background Art]
The traditional analog stethoscope, invented by Laennec in 1819, is a stethoscope including a chestpiece part, an earpiece part, and a tube connecting the chestpiece part and the earpiece part .
Until now, mechanical stethoscopes have been widely used in medicine, but, recently, conversion to electronic stethoscopes (using analog amplification) has been taking place. When making a diagnosis using the above-described stethoscope for a long time, diagnostic physicians suffer considerable acoustic disturbance and pain. Therefore, problems due to the ears' pain of the physicians occur at the time of diagnosis, thus resulting in misdiagnosis. In addition, the traditional analog stethoscopes and the recent electronic stethoscopes allow only physicians to listen to thoracic and heart sounds, so that the frequency of misdiagnosis is relatively high due to the physicians' subjective assessment, and patients and their guardians cannot listen to the sounds through the stethoscopes, thereby- resulting in one-sided diagnosis.
Furthermore, the traditional analog stethoscopes cannot store diagnostic data in a database due to their analog nature, so that there is a problem in that remote transmission is impossible .
[Disclosure] [Technical Problem]
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a visual stethoscope which is capable of storing and playing received biomedical signals through a USB transmission path.
Another object of the present invention is to provide a visual stethoscope which can convert diagnosis data into digital signals and put them into a database, thereby transmitting the diagnosis data to a remote location.
Still another object of the present invention is to provide a visual stethoscope which is capable of making objective and reliable diagnosis based on a thoracic and heart sound database and diagnostic software at the time of diagnosis .
Still another object of the present invention is to provide a visual stethoscope which prevents physicians' acoustic disturbance and ear pain attributable to the use of the stethoscope.
Still another object of the present invention is to provide a visual stethoscope in which a microphone is mounted within a cavity above a sound collection hole which is the inside of a head, and the periphery of the microphone is wrapped with a soundproof rubber member, so that the loss of sounds collected through the sound collection hole and the flow of noise are prevented, thereby clearly and precisely collecting thoracic and heart sounds.
[Technical Solution]
In order to accomplish the above object, the present invention provides a visual stethoscope including a sound collector for collecting biomedical signals generated from a human body and converting them into electric sound signals; a controller for receiving and amplifying thoracic and heart sounds output from the sound collector, performing filtering with respect to a predetermined frequency, or performing data conversion and processing, and outputting them,- and an output unit for receiving signals output from the controller, and outputting the signals as sound, or diagnosing, analyzing and displaying the signals using a predetermined algorithm.
The controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a second amplification unit for amplifying the biomedical signals output through the super low-pass filter; and an audio unit for passing only certain frequency band signals of the amplified biomedical signals through a predetermined filter.
The output unit is sound output unit for receiving signals output through the audio unit and converting them into sound signals.
The audio unit includes a signal detection circuit for detecting thoracic and heart sounds from the second amplification unit; and a low-pass filter for eliminating noise by passing certain frequency band signals of the signals from the signal detection circuit therethrough.
Alternatively, the controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an Analog-to-Digital (A/D) conversion unit for converting the sampled and held analog signals into digital signals; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; and a Universal Serial Bus (USB) transmission path terminal for delivering signals from the digital signal processing unit to external output unit .
The output unit is a computer that is connected to the USB transmission path terminal of the controller, receives signals output through the USB transmission path terminal and diagnoses and analyzes them using the predetermined algorithm.
Finally, the controller includes a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an A/D conversion unit for converting the sampled and held analog signals into digital signals; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; a Digital-to-Analog (D/A) conversion unit for converting outputs from the digital signal processing unit into analog signals and outputting them; and signal volume control unit for controlling amplitudes of signals from the D/A conversion unit and outputting the signals to external output unit.
[Advantageous Effects]
According to the present invention, objective diagnosis is possible because a patient and his or her guardian can listen to thoracic and heart sounds, also can see the waveform of the data at the time of diagnosis, and reliable diagnosis is possible because clinical data and a medical prescription based on a thoracic and heart sound database and diagnostic software are generated.
[Description of Drawings]
FIG. 1 is a block diagram illustrating a visual stethoscope according to the present invention;
FIG. 2a is a block diagram illustrating a first embodiment of the visual stethoscope of FIG. 1; FIG. 2b is a block diagram illustrating a second embodiment of the visual stethoscope of FIG. 1;
FIG. 2c is a block diagram illustrating a third embodiment of the visual stethoscope of FIG. 1; FIG. 3 is a circuit diagram illustrating the τr-type filter and inverted L-type filter of the visual stethoscope according to the present invention;
FIG. 4 is a sectional view illustrating the sound collector of the assembled stethoscope according to the present invention;
FIG. 5 is a block diagram illustrating the execution of a biomedical signal analysis program according to the present invention;
FIG. 6 is a waveform diagram illustrating the sampling and holding method of the visual stethoscope according to the present invention;
FIG. 7 is a diagram illustrating a screen capture of a biomedical signal analysis and diagnosis program; and
FIGS . 8a to 8d are waveform diagrams illustrating clinical diagnosis graphs taken using the biomedical diagnosis program of FIG. 7.
[Best Mode]
FIG. 1 is a block diagram illustrating a visual stethoscope according to an embodiment of the present invention, which includes a sound collector 100, a controller
200, a sound output unit 300, speaker output unit 400 and a computer 500.
As illustrated, the controller 200 includes a first amplification unit 211, a super Low Pass Filter (LPF) 213, a second amplification unit 215, an audio unit 217, a signal input interface 231, an automatic gain control unit 233, a sampling and holding unit 235, an analog-to-digital conversion unit 237, a digital signal processing unit 239, a digital-to- analog conversion unit 241, a signal volume control unit 243, and a USB transmission path terminal 251.
The controller 200 can have various types of external devices 300, 400 and 500 connected thereto, and may connect the sound output unit 300, such as earphones or a speaker which allows a physician to directly listen to the diagnostic sounds of a patient, to the output terminal of the audio unit 217, the speaker output unit 400, such as a speaker capable of allowing a general person to listen to a voice signal for diagnosis to the signal volume control unit 243, and a computer, such as a personal computer or a notebook, to the USB transmission path terminal 251.
That is, in the view of the external devices, it is possible to divide the controller 200 into 3 functional blocks, first, an sound processing unit 210 including the first amplification unit 211, the super LPF 213, the second amplification unit 215, and the audio unit 217, as illustrated in FIG. 2a, second, a voice processing unit 230 including the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, the digital- to-analog conversion unit 241, and the signal volume control unit 243, as illustrated in FIG. 2b, and finally, a digital communication unit 250 including the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, and the USB transmission path terminal 251 as illustrated in FIG. 2c.
The respective embodiments of the above-described visual stethoscope are described below. First, in FIG. 2a, the sound collector 100 collects biomedical (thoracic and heart) signals generated from a human body, and converts them into electric signals, that is, in detail, collects sounds or biomedical signals generated from the thoracic and heart of the human body and transmits them to the controller 210.
The controller 210 includes the first amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the second amplification unit 215 for amplifying the biomedical signals output from the super LPF 213, and the audio unit 217 for eliminating noises by passing only certain frequency band signals of the biomedical signals which are amplified and then are output as described above, using a predetermined filter. The super LPF 213 is set to 1.0 kHz, and therefore, cuts off frequencies above 1.0 kHz.
The audio unit 217 includes a signal detection circuit 218 and a low-pass filter 219, functions to eliminate some unfiltered high frequency signals from signals resulting from the output of biomedical signals passed through the super LPF 213, and prevents the high frequencies from modifying original signals that are biomedical signals .
Furthermore, the sound output unit 300 connected to the audio unit 217 enables a physician to monitor and listen to the diagnosis sounds of a patient, and includes earphones or a speaker which can output signals from the audio unit 217 as sound signals.
The low-pass filter 219 is formed of a 7r-type filter and an inverted L-type filter, as illustrated in FIG. 3. The π- type filter eliminate some unfiltered high frequency signals from signals resulting from the output of thoracic and heart sound signals passed through the super LPF 213 and prevents the high frequencies from modifying the original signals of thoracic and heart sounds. The inverted L-type filter is formed of an inductor L and a capacitor C which eliminates high frequency components again, and reproduces the original signals .
FIG. 2b is a block diagram illustrating the second embodiment of the controller according to the present invention, which includes the first amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the analog-to-digital conversion unit 237, the digital signal processing unit 239, the digital-to-analog conversion unit 241, the signal volume control unit 243 and the speaker output unit 400 as illustrated.
The sound collector 100 is a sound collection head which functions to collect biomedical signals generated from a human body and converts them to electric signals, that is, which collects sounds or biomedical signals (thoracic and heart) generated from the chest of the human body and transmits them to the controller 200.
The controller 200 includes the first amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the signal input interface 231 for transmitting the biomedical signals output through the super LPF 213 to the automatic gain control unit 233, the automatic gain control unit 233 for maintaining or controlling the biomedical signals transmitted through the signal input interface in a state close to that of original signals, the sampling and holding unit 235 for sampling and holding signals from the automatic gain control unit 233, the A/D conversion unit 237 for converting the sampled and held analog signals into digital signals, the digital signal processing unit for performing encoding/decoding, voice detection, noise control, and signal compression and decompression functions, the D/A conversion unit 241 for converting the outputs of the digital signal processing unit into analog signals and outputting them, and the signal volume control unit for controlling the amplitude of the output signals from the D/A conversion unit 241.
The automatic gain control unit 233 upwardly amplifies signals the amplitude of which is small, and attenuates signals the amplitude of which is large, thereby always causing signals having constant amplitude to be output.
Furthermore, when converting the analog signals of thoracic and heart sounds into bits for conversion into digital signals, the sampling and holding unit 235 performs a sampling operation through a sampling circuit having a frequency above 2.0 kHz in order to generate non-continuous data and a holding operation of latching the digital signals and maintaining the values thereof, as illustrated in FIG. 6.
In addition, it is preferred that the A/D conversion unit 237 and the D/A conversion unit 241 have performance higher than that corresponding to a Total Harmonic Distortion (THD) of 0.01% and a Signal-to-Noise Ratio (SNR) of 96dB. The THD corresponds to a reproduction precision value equal to or smaller than 0.01%, which is the reproduction value of thoracic and heart sounds with respect to their original signals, and the SNR of 96 dB is a value exhibiting an optimal separation rate, which is a ratio of thoracic and heart sound signals to noise of approximately 100,000 to 1.
The signal volume control unit 234 is a module for setting a bias in the pre-stage with respect to the analog signals from the D/A conversion unit 241 in order to listen to un-distorted thoracic and heart sounds through a speaker or earphones, and functions to adjust only the amplitude of amplified thoracic and heart sounds using variable resistors and maintain the frequency thereof, thereby controlling an amplification level . Furthermore, the speaker output unit 400 is preferably a speaker capable of outputting signals from the signal volume control unit 243 as sound signals .
FIG. 2c is a block diagram illustrating the third embodiment of the digital stethoscope according to the present invention. As illustrated, the digital stethoscope includes the sound collector 100, the amplification unit 211, the super LPF 213, the signal input interface 231, the automatic gain control unit 233, the sampling and holding unit 235, the A/D conversion unit 237, the digital signal processing unit 239, and a computer 500.
The sound collector 100 is a sound collection head which collects biomedical signals generated from a human body, and converts them into electric signals, and, in detail, collects sounds or biomedical (thoracic and heart) signals generated from the chest of the human body and transmits them to the controller 200. The controller 200 includes the amplification unit 211 for amplifying electric sound signals transmitted from the sound collector 100, the super LPF 213 for passing predetermined frequency band signals of the amplified electric sound signals therethrough, the signal input interface 231 for transmitting the biomedical sounds output through the super LPF 213 to the automatic gain control unit 233, the automatic gain control unit 233 for maintaining or controlling the biomedical signals transmitted through the signal input interface in a state close to that of the original signals, the sampling and holding unit 235 for sampling and holding signals from the automatic gain control unit 233, the A/D conversion unit 237 for converting the sampled and held analog signals into digital signals, the digital signal processing unit 239 for performing encoding/decoding, and signal compression and decompression functions, and the USB transmission path terminal 251 connected to the external computer 500 through a predetermined cable.
The computer 500 includes a USB transmission path terminal 511 which is connected to the USB transmission path terminal 251 of the controller 200 and receives signals output through the digital signal processing unit 239, and a circuit unit which diagnoses and analyzes signals received through the USB transmission path terminal 511 using a predetermined algorithm. In addition, the signals transmitted to the digital signal processing unit 239 are buffered in Read Only Memory (ROM) and Random Access Memory (RAM) , which are separate auxiliary memory units embedded in the computer 500, through the USB transmission path terminal 511, or are displayed on a liquid crystal display screen by inputting the signals to a biomedical signal diagnosis and analysis program stored in the computer 500.
Furthermore, the digital signals of thoracic and heart sounds through the USB transmission path terminal 511 are preferably received or transmitted in the form of a DOWN & UP STREAM, 16Bit MONO STElEAM or 24Bit STREAM, and the sampling bit rate thereof may be changed in the range of 6.4 to 48kHz.
Although not shown, it is preferred that a battery be used as the power supply of the controller 200, and that the battery be automatically charged through the USB transmission path terminal 511 when the controller 200 is connected to the USB transmission path terminal 511 of the computer 500.
As a result, the controller 200 does not require a separate power supply because it uses the power supplied from the computer 500 through the USB transmission path terminal. At ordinary times, an embedded battery (3.6V Ni-cd) is charged, but it is possible to use the visual stethoscope in the form of a conventional analog stethoscope comprising a separate embedded battery (3.6V Ni-cd) when the visual stethoscope is used as an analog stethoscope. The sound collector for the stethoscope of these embodiments includes a body 110, a diaphragm 130, a microphone 140, a cap 150 and a cable 170 as illustrated in FIG. 4.
The body 110 is formed in an approximately inverted funnel shape. A first sound collection plate 111 having a lampshade shape is placed in the lower portion of the body 110 so as to have a wide opening. A sound collection hole 115 having a narrow passage shape is formed above the center of the opening. A wide cavity is formed above the upper end of the sound collection hole 115. In addition, reference numeral 113 designates a second sound collection plate projecting toward the diaphragm 130 from the inner surface of the first sound collection plate 111, which is shaped in a ring from. When, during diagnosis, a physician move after bringing the first sound collection plate 111 into contact with the chest of a human body, sounds (frictional sounds) caused by such contact are directly delivered to the second sound collection plate 113 through a sound collection hole 115, so that loud echo and noise occur. In order to prevent this, the second sound plate 113 is mounted, which functions to isolate external noises and frictional sounds caused by such contact, and directly delivers the thoracic and heart sounds of the chest. Furthermore, when the physician places the head on the patient's chest, the second sound collection plate 113 adheres to the skin of the human body due to the contact with the skin and pressure on the human body, so that a vibration phenomenon disappears . The disappearance of the vibration due to the contact and pressure of the skin is prevented by mounting the second sound collection plate 113.
In addition, in the present invention, the body is made of plastic material, rather than metal material. The reason for this is that it is possible to prevent a patient from feeling unpleasant and discomfort or fear due to the coolness of the body 110 when it contacts the skin of the patient because the heat retention of plastic material is better than that of metal material.
Furthermore, the diaphragm 130 is connected to the lower end of the opening and is constructed to generate predetermined vibration depending on sounds generated from the object of diagnosis. The microphone 140 is inserted into a cavity formed on the upper end of the sound collection hole 115 and is constructed to amplify sounds input through the sound collection hole 115. The cap 150 is screwed to the outer surface of the cavity and supports the body 110, into the center of an end of which a soundproof molding member 160 is inserted. The cable 170 is inserted into the center of the molding member 160 , is constructed to connect with an output terminal formed on the upper end of the microphone 140, and deliver amplified sound signals from the microphone 140.
Furthermore, a buffer rubber member 141 which prevents the flow and generation of noise is inserted between the cavity of the body 110 and the outer surface of the microphone 140, and a ring soundproof rubber member 145 is inserted between the edge of the upper end of the microphone 140 and the molding member 160, thereby protecting sounds flowing through the sound collection hole 115 and the microphone 140. Furthermore, the body 110 and diaphragm 130 are connected to each other through a predetermined engagement member 120. The engagement member 120 is a rubber ring having a cross- section approximately shaped in a "] " form, and is secured into a groove formed along the edge of the body 110 and the lower surface of the diaphragm 130, thereby engaging the body 110 with the diaphragm 130.
A bolt is formed on the outer surface of the cavity of the body 110 and a nut matching the bolt is formed on the inner surface of the cap 150. That is, the diaphragm 130 converts sounds from the chest into vibration. The sound collection hole 115 collects variations in the vibrations received from the diaphragm 130 into the hole, thereby collecting thoracic and heart sounds. The engagement member 120 holds the diaphragm 130 closed to the lower surface of the edge of the first sound collection plate 111. The body 110 collects sounds through the diaphragm 130 and the opening, and has an optimal sound collection structure when the inner angle with respect to the diaphragm 130 is approximately 10° to 12°.
The size of the sound collection hole 115 is approximately 3.0 φ to 3.5 φ. The sounds due to resonance
(sounds generated by the cavities of a human body) of a human body become small or large depending on the size of the sound collection hole 115, which is defined as Q (representing the relationship between the repetition (frequency) of vibrations and the degree of amplification with respect to a predetermined time at a point) . When Q value is optimal, thoracic and heart sounds can be best heard without echoes. As a result, the size of the sound collection hole 115 must be appropriately adjusted depending on whether a patient is a child or an adult. Furthermore, the cap 150 is a fastener for securing the body 110 so that it does not move, and is gripped by a physician upon auscultation. The microphone 140 is provided to convert sounds from a sound collector into electric signals. The buffer rubber member 141 is a stand for protecting the microphone 140 in order to prevent the microphone 140 and the hole from being modified. The molding member 160 receives and supports the cable 170 in the inner hollow thereof, and is a piece of rubber which prevents noise from flowing from the outside and directly delivers signals from the sound collection hole 115 and the microphone 140. The ring rubber member 145 protects sounds which flow through the sound collection hole 115 and the microphone 140. The cable is a connection line for delivering sounds (thoracic and heart) received from the microphone as electric signals . As described above, the cavity is formed above the upper end of the body 110 of the head, and then the microphone is mounted thereon, so that it is possible to sufficiently amplify even weak vibration sounds of the diaphragm 130 using the microphone 140. Furthermore, the microphone 140 is mounted on the upper end of the sound collection hole 115, so that it is possible to amplify the thoracic and heart signals with fidelity. Furthermore, it is possible to sufficiently detect not only high frequencies but also low frequencies using a single diaphragm 130.
Furthermore, the buffer rubber member 141 is inserted between the microphone 140 and the cavity of the body 110, so that it is possible to protect the microphone 140 and cut off sound waves leaking through the sound collection hole 115. The ring rubber member 145 is located between the upper end of the microphone 140 and the molding member 160, so that the leakage of sounds from the sound collection hole 115, and the flowing of noise can be prevented and the microphone 140 is protected, thereby increasing the ability to collect and detect the sounds of a human body through the sound collection hole 115.
The above-described sound collector directly connects to the controller 200 for analyzing thoracic and heart sounds by connecting a stereo jack, rather than earpieces, to one end of the cable 170, so that self-diagnosis by a general person is possible without the diagnosis of a physician, and, furthermore, a patient as well as a physician can directly listen to his or her own thoracic and heart sounds also to see the data or monitor the results after analysis by an analysis program using a graph through a thoracic and heart sound analysis controller.
FIG. 5 is a block diagram illustrating the execution of a thoracic and heart sound diagnosis and analysis program within a computer according to the present invention. First, biomedical signals such as, auscultatory sounds received from the sound collector 100, blood pressure, body temperature, respiratory rate, and oxygen saturation, are delivered to the computer 500 through the USB transmission path terminal 511. A biomedical diagnosis algorithm is installed in the computer 500, so that processing of thoracic and heart sound data collected by the sound collector 100 and the display thereof are possible, and, with respect to the biomedical signals received through the USB transmission path terminal 511, the logarithmic energy level crossing rate of each of the biomedical signals is analyzed using a predetermined biomedical signal analysis algorithm included in a fast Fourier transformation (FFT) unit and a Logarithmic energy level Crossing Rate (LCR) calculation unit 515, and is displayed on a monitor 519.
All of the numerical values and operational states of the program are displayed on the monitor 519. The monitor 519 is implemented using a touch screen, so that the operation of the monitor is easy, and, thus, there is an advantage of shortening diagnosis time.
In order to extract the characteristics of thoracic and heart sound signals, acoustic parameters are required for the analysis of signals. The thoracic and heart sound signals are information about analog thoracic and heart sounds input continuously as time elapses . The digitization of the analog thoracic and heart sounds is required, and in order to overcome the limitation of hardware resource, the lossless compression of the thoracic and heart sound information is required. The compression of thoracic and heart sound information serves to delete redundant information from signals and to store the signals. When thoracic and heart sound signals are input to a recognizer without any control in order to recognize thoracic and heart sound information, the resources of the recognizer, which are required to process highly redundant data, are wasted. As a result, in order to reduce the waste of the recognizer's resources, (a predetermined width of analysis interval (where hanning window 512 is optimal) is, defined with respect to input voice, the characteristics of the sounds in the interval are analyzed, and results based on the analysis are used or utilized.
The logarithmic energy level crossing rate is calculated by the logarithmic energy level crossing rate calculation unit 515 embedded in the computer using Equation 1 as follows :
Figure imgf000020_0001
sga[x(n)-TH] =I, x(n)≥0
sgn[x(n)-TH] =-1, x(n) <0 where TH is a threshold value, and is determined by the characteristic of the input signal and various examination results. Since the determination of the threshold value and a large amount of calculation are problems, it is assumed that the value of TH is not always constant, and the value of TH is determined by observing variation in the characteristics of the input signal and using the average characteristic of the input signal. That is, the threshold value is determined by input variables . Accordingly, the threshold value which is experimentally used for the detection of signals is fixed, so that a threshold value that varies depending on the situation is determined, a biomedical signal interval is detected by performing FFT on voice data and using the sum of energies of 20Hz~4kHz, the LCR and whether energy level continues to increase.
Meanwhile, in the diagnosis of biomedical signals, biomedical signals, such as auscultatory sounds, blood pressure, body temperature, respiratory rate, and oxygen saturation, received from the sound collector 100, are delivered to the computer 500 through the USB transmission path terminal 511.
A biomedical diagnosis algorithm is installed in the computer 500, so that the processing of thoracic and heart sound data collected by the sound collector 100 and the display thereof are possible, and the thoracic and heart sounds transmitted through the USB transmission path terminal 511 are passed through the harming window 513, thereby generating predetermined data required for diagnosis and analysis.
The logarithmic energy level crossing rate of each of the biomedical signals which are transmitted to the computer 500 is analyzed using a predetermined biomedical signal analysis algorithm included in the fast Fourier transformation (FFT) unit and the logarithmic energy level crossing rate calculation unit 515, and is displayed on a monitor 519.
All of the numerical values and operational states of the program are displayed on the monitor 519. The monitor 519 is implemented using a touch screen, so that the manipulation of the monitor is easy, and, thus, there is the advantage of shortening diagnosis time.
Furthermore, the computer 500 receives biomedical signals, such as auscultatory sounds, blood pressure, body temperature, respiratory rate and oxygen saturation, which are transmitted through the USB transmission path terminal 511, analyzes the biomedical signals using a numerical display algorithm 517 related to blood pressure, body temperature, respiratory rate or the like, and displays a corresponding numerical value on the monitor 519 in which the touch screen function is implemented. As described above, it is preferable to transmit a diagnosis or analyzed digital data to the computer 500 or to a separate computer, to store the data as clinical data along with the comments of the physician who observes the thoracic and heart signals, and to use them. As a result, there is an advantage in that data loss and the diagnosis of a patient ' s disease and condition according to subjective comments based on the hearing ability of a physician, which are the big disadvantages of conventional analog stethoscopes, are overcome, and, therefore, it is possible to perform an objective medical diagnosis thanks to visual confirmation and determination.
FIG. 7 is a diagram illustrating a screen capture of a biomedical signal analysis and diagnosis program. The functions of respective parts are described with reference to FIG. 7 below. Reference character (D designates a button used to record thoracic and heart sounds, reference character (b designates a button used to play thoracic and heart sounds, reference character © designates a button used to play only the waveform ® of the enlarged time interval of selected thoracic and heart sounds, reference character (d) designates a button used to stop the recording or playing of thoracic and heart sounds, reference character © designates an open button used to load the database of thoracic and heart sounds, and reference character (D designates a storage button used to store the content of thoracic and heart sounds.
Furthermore, reference character (D designates a window used to write the name of a patient, reference character (K) designates a window used to write the unique number or social identification number of a patient, reference character © designates a window used to write the file (including year, month, day, time, and file name) of a recorded database when the database of thoracic and heart sounds is recorded as another name or when thoracic and heart sounds are stored, reference character © designates a window used to display the temperature of a patient, reference character ® designates a window used to display the maximum and minimum values of the blood pressure of a patient, reference character CD designates a window used to display the pulse rate of a patient, reference character © designates a window used to display oxygen saturation Spθ2, ® designates a window used to display the LCR values (bronchial trouble, pneumonia and asthma, determined based on the LCR values) of a diagnosis algorithm, and reference character ® designates a window used to display a record level when thoracic and heart sounds are recorded.
Furthermore, reference character (D designates a window represented by dragging a part to be viewed in detail among the overall thoracic and heart sounds © using a mouse, reference character © designates the overall thoracic and heart sounds displayed (recorded) when thoracic and heart sounds are load from a database or diagnosed, reference character © designates the enlarged waveform of original sounds, in which the designated interval ® of the overall thoracic and heart sounds displayed in © is enlarged, and reference character © designates a spectrogram (the frequency of which is 1.0kHz and 1.0-2.OkHz) displayed with respect to the designated interval (P) of the overall thoracic and heart sounds displayed in ©.
The examples of © and © are screens of FIGS . 8a to 8d in which waveforms and spectrograms corresponding to biomedical signals are captured as clinical diagnosis graphs detected using a biomedical program (algorithm) .
FIG. 8a is a diagram illustrating waveform of the normal respiratory rate of a healthy person, FIG.8b is a diagram illustrating waveform of the abnormal respiratory rate of an unwell person, such as an asthma patient, FIG. 8c is a diagram illustrating a mild asthma state, and FIG. 8d is a diagram illustrating a moderate asthma state . Reference character © designates waveform representing some portion of the overall waveform. When a physician views the waveform existing in a database and makes a diagnosis stating that a specific part (£) has a problem, it is possible to record and determine the precise diagnosis of a patient by analyzing the part in detail .
The present invention can transmit thoracic and heart sounds directly from the USB transmission path terminal 511 to a speaker or earphones, that is, the speaker output unit 400, through the D/A conversion unit 241 and the signal volume control unit 243 capable of controlling the amplitude of signals, when a physician, and a patient or an intern want to simultaneously listen to the thoracic and heart sounds and visualize the thoracic and heart sounds at the time of diagnosis, unlike the above-described embodiments.
[industrial Applicability]
Accordingly, the visual stethoscope according to the present invention collects biomedical signals (thoracic and heart sounds) , and enables visualization of and listening to thoracic and heart sounds, which are output from a sound collector using a biomedical signal diagnosis program through a USB transmission path, using a liquid crystal display and earphones or a speaker. Furthermore, the visual stethoscope can store thoracic and heart sounds as digital data using a biomedical signal diagnosis algorithm, and can store the personal information of a patient and the clinical records of a physician.
Furthermore, the digital data is associated with a database, the biomedical signal diagnosis algorithm and a separate diagnostic database, so that the most probable name of a disease can be provided. It is possible to make objective diagnosis based on statistics using the database, and to implement a visual stethoscope system using a USB transmission path, which is high value-added.
Accordingly, in the present invention, objective diagnosis is possible because a patient and his or her guardian can listen to thoracic and heart sounds, also can see the waveform of the data at the time of diagnosis, and reliable diagnosis is possible because clinical data and a medical prescription based on a thoracic and heart sound database and diagnostic software are generated.
Furthermore, since the thoracic and heart sound database is shared between physicians, there are advantages in that quality of medicine is improved and the thoracic and heart sound database is provided in various information formats for the future management and treatment of a patient.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[Claims]
[Claim l]
A visual stethoscope, comprising: a sound collector for collecting biomedical signals generated from a human body and converting them into electric sound signals; a controller for receiving and amplifying thoracic and heart sounds output from the sound collector, performing filtering with respect to a predetermined frequency, or performing data conversion and processing, and outputting them; and output unit for receiving signals output from the controller, and outputting the signals as sound, or diagnosing, analyzing and displaying the signals using a predetermined algorithm.
[Claim 2]
The visual stethoscope as set forth in claim 1, wherein the controller comprises : a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a second amplification unit for amplifying the biomedical signals output through the super low-pass filter; and an audio unit for passing only certain frequency band signals of the amplified biomedical signals through a predetermined filter. [Claim 3]
The visual stethoscope as set forth in claim 2, wherein the output unit is sound output unit for receiving signals output through the audio unit and converting them into sound signals .
[Claim 4]
The visual stethoscope as set forth in claim 2, wherein the audio unit comprises : a signal detection circuit for detecting thoracic and heart sounds from the second amplification unit; and a low-pass filter for eliminating noise by passing certain frequency band signals of the signals from the signal detection circuit therethrough.
[Claim 5]
The visual stethoscope as set forth in claim 1, wherein the controller comprises: a first amplification unit for amplifying the electric sound signals output from the sound collector,- a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an Analog-to-Digital (A/D) conversion unit for converting the sampled and held analog signals into digital signals ; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; and a Universal Serial Bus (USB) transmission path terminal for delivering signals from the digital signal processing unit to external output unit .
[Claim 6]
The visual stethoscope as set forth in claim 5, wherein the output unit is a computer that is connected to the USB transmission path terminal of the controller, and receives signals output through the USB transmission path terminal and diagnoses and analyzes them using the predetermined algorithm.
[Claim 7]
The visual stethoscope as set forth in claim 1, wherein the controller comprises: a first amplification unit for amplifying the electric sound signals output from the sound collector; a super low-pass filter for passing predetermined frequency band signals of the amplified electric sound signals therethrough; a signal input interface for transmitting the biomedical signals output through the super low-pass filter; an automatic gain control unit for maintaining or controlling the biomedical signals output through the signal input interface in a state close to that of original signals; a sampling and holding unit for sampling and holding signals output from the automatic gain control unit; an A/0 conversion unit for converting the sampled and held analog signals into digital signals; a digital signal processing unit for receiving signals output through the A/D conversion unit and performing an encoding or decoding function and a compression or decompression function; a Digital-to-Analog (D/A) conversion unit for converting outputs from the digital signal processing unit into analog signals and outputting them,- and signal volume control unit for controlling amplitudes of signals from the D/A conversion unit and outputting the signals to external output unit .
[Claim 8]
The visual stethoscope as set forth in claim 7, wherein the controller further comprises : a second amplification unit for amplifying the biomedical signals output through the super low-pass filter; and an audio unit for eliminating noise by passing only certain frequency band signals of the amplified biomedical signals through a predetermined filter and outputting them to external output unit.
[Claim 9]
The visual stethoscope as set forth in claim 7 or 8, wherein the controller further comprises a USB transmission path terminal for delivering signals from the digital signal processing unit to external output unit. [Claim 10]
The visual stethoscope as set forth in claim 7, wherein the output unit is speaker output unit for converting signals output through the signal volume control unit into voice signals and outputting them.
[Claim ll]
The visual stethoscope as set forth in any one of claims 2 to 8, wherein the super low-pass filter is set for a frequency of 1.0 kHz .
[Claim 12]
The visual stethoscope as set forth in any one of claims 1 to 8, wherein the sound collector comprises: a body formed in an approximately inverted funnel shape, and having a wide opening on a lower end thereof and a sound collection hole formed in a narrow passage shape above a center of the opening; a microphone mounted in a wide cavity formed above the sound collection hole to communicate with the sound collection hole and configured to amplify sounds flowing through the sound collection hole; a diaphragm coupled to the lower end of the body and configured to generate vibrations depending on an amount of sound generated from an object of diagnosis; a cap screwed to an outer surface of the hole to support the body, and engaged with a soundproof molding member on a center of an end thereof; and a cable inserted into a center of the molding member, connected to an output terminal formed on an upper end of the microphone, and configured to deliver amplified sound signals from the microphone to an outside .
[Claim 13]
The visual stethoscope as set forth in claim 12, wherein a buffer rubber member is inserted between a periphery of the cavity of the body and an outer surface of the microphone.
[Claim 14]
The visual stethoscope as set forth in claim 12 or 13, wherein a soundproof ring rubber member is inserted between an upper end of the microphone and the molding member.
[Claim 15]
The visual stethoscope as set forth in claim 12 , wherein the body is made of plastic material .
[Claim 16]
The visual stethoscope as set forth in claim 1, wherein the output unit comprises a computer which receives one or more of blood pressure, body temperature, respiratory rate, and oxygen saturation SpO2, which are biomedical signals, through the sound collector, collects the thoracic and heart sound signals, and manages them.
[Claim 17]
The visual stethoscope as set forth in claim 16, wherein the computer comprises : a harming window unit for generating required data using the thoracic and heart sound signals; and a fast Fourier transformation unit and a logarithmic energy level crossing rate calculation unit for diagnosis or analysis of the biomedical signals .
[Claim 18]
The visual stethoscope as set forth in claim 17, wherein the computer includes a biomedical signal diagnosis algorithm (LCR algorithm) in the fast Fourier transformation unit and the logarithmic energy level crossing rate calculation unit, analyzes logarithmic energy level crossing rates of respective thoracic and heart sounds, and displays them on a monitor thereof.
[Claim 19]
The visual stethoscope as set forth in claim 18, wherein the monitor of the computer is a touch screen.
PCT/KR2006/001101 2005-03-24 2006-03-24 Visual stethoscope WO2006101375A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR1020050024678A KR100669532B1 (en) 2005-03-24 2005-03-24 Usb digital stethoscope
KR10-2005-0024678 2005-03-24
KR20-2005-0008908 2005-03-31
KR20-2005-0008908U KR200388387Y1 (en) 2005-03-31 2005-03-31 Head of a stethoscope

Publications (1)

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WO2006101375A1 true WO2006101375A1 (en) 2006-09-28

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US8870791B2 (en) 2006-03-23 2014-10-28 Michael E. Sabatino Apparatus for acquiring, processing and transmitting physiological sounds
JP7377560B2 (en) 2021-10-27 2023-11-10 東郷メディキット株式会社 Stethoscope

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US6544198B2 (en) * 2001-06-11 2003-04-08 Hoseo University Stethoscope system for self-examination using internet
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US8870791B2 (en) 2006-03-23 2014-10-28 Michael E. Sabatino Apparatus for acquiring, processing and transmitting physiological sounds
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