JPH09292214A - Ultrasonic sebum thickness measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and precisely measure sebum thickness. SOLUTION: An ultrasonic pulse is emitted toward the tissue under the skin of a subject plural times, and a group of echoes containing the sebum echo from the critical surface between pannicular tissue and flesh is received. A waveform shaper 7 converts the received signal into a signal corresponding to the presence or absence of echo followed by outputting, and a serial I/O 8 takes the output signals of the waveform shaper 7 at a prescribed taking period, and transmits the taken value of 1 pit to a CPU 11. The CPU 11 detects the change from '1' to '0' of the taken value and counts the frequency of presence of echo every taking period. The value obtained by multiplying the sum of the respective receiving frequencies for a plurality of periods further before by a coefficient 2 is subtracted from the sum of the respective receipt frequencies for four period before an optional taking period to calculate the integrated receiving frequency, the taking period and receiving frequency which give the maximum value of the integrated receiving frequency are determined, and sebum thickness is calculated on the basis of these taking period and receiving frequency.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention radiates an ultrasonic pulse toward a living tissue under a predetermined skin of a living body, and examines an echo returning from an interface between a subcutaneous fat tissue and a muscle tissue. The present invention relates to an ultrasonic skin fat thickness measuring device for measuring skin fat thickness.

[0002]

2. Description of the Related Art In recent years, a high correlation between obesity and various diseases has been pointed out, and interest in beauty has increased, and a simple method for testing the degree of obesity has been demanded. Conventionally, in order to easily know the degree of obesity, for example, skin fat thickness is measured. As a device for measuring the skin oil thickness, an ultrasonic pulse is emitted toward the body of a living body, and the ultrasonic pulse is reflected by the boundary surface between the subcutaneous fat tissue and the muscle tissue to detect echoes and return to the skin oil. An ultrasonic skin oil thickness measuring device for measuring thickness is known. For example, special table Sho 57-50090
The ultrasonic skin fat thickness measuring device described in Japanese Patent No. 0 supplies an electric pulse signal generated by a pulse generator to an ultrasonic transducer to emit an ultrasonic pulse toward the inside of a living body, and to echo the returned echo. Based on the time required from the transmission of ultrasonic pulse to the detection of the echo, assuming that the desired echo is detected when this electric signal exceeds the specified threshold value It is configured to measure.

[0003]

However, in the ultrasonic skin fat thickness measuring device described in the above publication, the skin fat thickness is calculated based on the intensity of the echo that is returned by transmitting the ultrasonic pulse. Therefore, there is a problem that the hardware becomes complicated and the cost increases. Further, a method of obtaining the average value of these measurement values as skin fat thickness by performing a plurality of measurements is also considered, but in this method, a plurality of sites or boundaries other than the boundary surface between subcutaneous fat tissue and muscle tissue are considered. Since echoes from the surface are also detected at the same time, and a desired echo cannot be separated from these echoes to calculate the skin fat thickness, there is a drawback that the measurement accuracy is low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ultrasonic skin fat thickness measuring apparatus having a simple circuit structure, which is inexpensive and has high measurement accuracy.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 has a vibrator for performing mutual conversion between an electric signal and an ultrasonic wave and a delay member for transmitting the ultrasonic wave. Ultrasonic transducers for transmitting and receiving ultrasonic waves, transmission control means for controlling the transmission of ultrasonic waves by the ultrasonic transducers, and signals based on the signals received by the ultrasonic transducers to be input, with or without echo The transmission control means includes: an echo presence / absence signal generating means for generating and outputting a signal; and a skin fat thickness calculating means for calculating a predetermined skin fat thickness of the living body based on the output of the echo presence / absence signal generating means. When measuring once, ultrasonic wave K (K
Is a natural number greater than or equal to 2) and is configured to perform transmission.
Every time the ultrasonic transducer transmits an ultrasonic wave, the skin-fat thickness calculating means fetches the output signal from the echo presence / absence signal generating means at a predetermined time interval, and transmits the number of times with echo at each capturing time. The reverberation and the end face echo reflected by the end face of the delay member are excluded, and converted to a value indicating the distribution with echo with respect to the acquisition time by using a predetermined recurrence formula, and the distribution with echo is further shown. An ultrasonic skin fat thickness measuring device configured to calculate a maximum value of the values and calculate the skin fat thickness based on the maximum value, wherein the recurrence formula is the Nth (N is 0 or a natural number) of interest. ) For each of the acquisition timing and any of the plurality of acquisition timings prior to the acquisition timing, the sum of the values obtained by multiplying the number of echo occurrences by a predetermined coefficient is the Nth acquisition timing. As a value showing the distribution with echo at the time It is characterized by an equation that gives.

The invention according to claim 2 is the ultrasonic skin fat thickness measuring device according to claim 1, wherein the recurrence formula is based on the N-th intake time of interest and the intake time. Also, from the sum of the number of times with echo for each of the previous arbitrary multiple acquisition times, there is an echo for each of the continuous multiple acquisition times before the multiple acquisition times. It is an expression that gives a result obtained by subtracting a value obtained by multiplying the sum of times by a predetermined coefficient of 2 or more as a value indicating the distribution with the echo at the N-th acquisition time, and the skin fat thickness calculating means is Obtaining the uptake time that gives the maximum value of the distribution indicating the presence of the echo obtained using the predetermined recurrence formula, based on the uptake time and the number of echoes at the uptake time, the sebum Characterized by being configured to calculate the thickness That.

Furthermore, the invention according to claim 3 is the ultrasonic skin fat thickness measuring device according to claim 1 or 2, wherein the echo presence / absence signal generating means receives the signal received by the ultrasonic transducer. And a predetermined threshold value, which is a decay function of time, are compared to output a signal corresponding to the presence or absence of the echo.

[0008]

According to the structure of the present invention, the presence / absence of an echo is detected to detect the sebum echo reflected and returned at the boundary between the subcutaneous fat tissue and the muscle tissue. One bit is sufficient for a signal corresponding to the presence or absence of an echo, and therefore, the hardware can be greatly simplified and the cost can be kept low as compared with the method of measuring the intensity of the echo. Also, the operation time can be shortened significantly. Further, when counting the number of echoes at each acquisition time by the skin fat thickness calculating means, for example, the effects of transmission reverberation and end face echo can be eliminated, and echoes can be obtained using a predetermined recurrence formula. In the process of obtaining the maximum value of the distribution of the presence, for example, because it is possible to remove the effect of the echo that is reflected back at the interface between the muscle tissue and the organ that comes after the sebum echo,
Information regarding the sebum echo can be accurately extracted. Therefore, the skin fat thickness can be accurately calculated. Furthermore, if the ultrasonic wave is emitted a number of times for measurement and the sebum thickness is calculated based on the maximum value showing the distribution with echo obtained by a predetermined recurrence formula from the temporal distribution of the number of times with echo It is possible to measure with higher accuracy.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using an embodiment. FIG. 1 is a block diagram showing an electrical configuration of an ultrasonic skin fat thickness measuring apparatus according to an embodiment of the present invention, FIG. 2 is an external view of the apparatus, and FIG. 3 is a schematic diagram showing a usage state of the apparatus. 4, FIG. 4 is a diagram used for explaining the operation of the apparatus, and FIG. 5 is a flowchart showing an operation processing procedure of the apparatus. As shown in FIGS. 1 to 3, the ultrasonic skin fat thickness measuring apparatus of this example responds to each input of an electric pulse signal at a predetermined cycle, and, An echo (hereinafter referred to as sebum echo) Ae that emits ultrasonic pulses Ai a predetermined number of times toward the living tissue under the skin Ma of the abdomen and returns from the boundary surface Y between the subcutaneous fat tissue Mb and the muscle tissue Mc. An ultrasonic transducer (hereinafter, simply referred to as a transducer) 1 that receives an echo group including a signal and converts it into a received signal (electrical signal), and an electric pulse signal is supplied to the transducer 1 and is output from the transducer 1. After the received signal is processed and converted into a signal S corresponding to the presence or absence of echo, a predetermined arithmetic process is performed to calculate the skin fat thickness, and a device It has schematically a cable 3 for connecting the p o 1 and the apparatus main body 2.

The transducer 1 is mainly composed of an ultrasonic transducer 1a having electrode layers on both sides of a disc-shaped thickness vibration type piezoelectric element such as lead titanium zirconate (PZT). An ultrasonic wave delay spacer 1b such as polyethylene bulk is fixed to one electrode surface of 1a (transmission / reception surface of ultrasonic wave pulse Ai) in order to remove the effect of transmission reverberation. The ultrasonic delay spacer 1b can be omitted when the transmission reverberation does not affect the reception of the sebum echo Ae. Here, in order to perform a highly accurate measurement, the ultrasonic pulse Ai, which can be regarded as a plane wave from the transmitting / receiving surface of the transducer 1, can be radiated toward the living tissue under the skin Ma and can be regarded as a plane wave. Since it is desirable for the echo Ae to return to the transmitting / receiving surface, the transducer 1 preferably has a transmitting / receiving surface as wide as possible (in this example,
The diameter D of the transmitting / receiving surface is set to 15 [mm]).

The apparatus main body 2 includes a pulse generator 4, a matching circuit 5, an amplifier 6, a waveform shaper 7, and a serial I.
/ O8, ROM 9, RAM 10, CPU (Central Processing Unit) 11, and display 12. The pulse generator 4 is connected to the transducer 1 via the cable 3, repeatedly generates an electric pulse signal having a center frequency of about 1 MHz at a predetermined cycle (for example, 100 msec), and transmits the electric pulse signal to the transducer 1. The cycle of this ultrasonic pulse is set sufficiently longer than the echo arrival time Ta described later. The matching circuit 5 performs impedance matching between the transducer 1 connected via the cable 3 and the apparatus body 2 so that signals can be transmitted and received with maximum energy efficiency. Therefore, the received signal is output from the transducer 1 every time the ultrasonic transducer 1a of the transducer 1 receives the echo group including the sebum echo Ae, passes through the matching circuit 5, and without energy loss,
It is input to the amplifier 6. The amplifier 6 amplifies the received signal input via the matching circuit 5 with a predetermined amplification degree, and then
Input to the waveform shaper 7. The waveform shaper 7 is an L (not shown).
A bandpass filter having a C configuration, a comparator, a threshold voltage generating circuit, and the like are provided, and the received signal amplified by the amplifier 6 is subjected to filter processing to perform linear waveform shaping to remove noise components, and then waveform shaping. The analog received signal received is compared with a predetermined reference detection voltage Vt output from the threshold voltage generating circuit by a comparator, and when the received signal does not exceed the reference detection voltage Vt, "1", reference detection When it exceeds the voltage Vt, it is sequentially converted into a signal S corresponding to the presence or absence of a 1-bit echo that becomes "0", and the signal S is sent to the serial I / O 8. Here, the reference detection voltage Vt
Is set so that it decays with a predetermined time constant as time passes, as shown in FIG. Serial I / O8 is
After the signal S corresponding to the presence or absence of this echo is acquired at a predetermined acquisition period Ts (for example, 1.33 μsec),
The fetched fetched value is sent to the CPU 11. The capture cycle Ts is set so as to approximately satisfy the relationship [c × Ts = 2 mm] with the propagation velocity c of the ultrasonic pulse in the subcutaneous fat tissue Mb.

ROM 9 is an operating system
In addition to (OS), the CPU 11 calculates the skin fat thickness.
Stores the processing program to be executed. This processing program
Each time it emits one pulse and receives a group of echoes
In other words, from the serial I / O8 for each measurement K
Corresponding to the presence / absence of 1-bit echo transmitted
Whether the captured value of signal S has changed from "1" to "0"
For each acquisition period Ts, that is, the ultrasonic pulse Ai
From the transducer 1 to the living tissue under the skin Ma
Detected for each capture time N calculated from the time when it is launched
Procedure, respond by emitting ultrasonic pulse Ai a predetermined number of times
When the echo group is received, the acquisition value at each acquisition time N
Number of changes from "1" to "0", that is, with echo
The number of times of accumulation, and
Number of echoes received in the Nth cycle M _NThe hand to ask
In order, prior to this, transmission reverberation and ultrasonic delay spacer 1b
From the end surface on the side of the skin Ma (hereinafter referred to as end surface echo)
The procedure for excluding the above), the number of received waves obtained for each acquisition time N
Number M_NBased on the
The cumulative number of received waves Y, which will be described later, given by the recurrence polynomial
_NFor calculating the total number of received waves Y_NGive the maximum value
To obtain the acquisition time N that can be obtained, this acquisition time N and this
Number of waves received M_NProcedure for obtaining the skin fat thickness D based on
Is described. In addition, in this processing program,
The arrival time Ta of the fat echo is calculated as follows.
You. First, the cumulative number of received waves Y_NAt the import time N
Number of waves M_NEquation (1) is a recurrence polynomial for
Confuse.

[0013]

[Equation 1]

M_N-1, M_N-2,…: Retrieval time N
Number of waves received at -1, N-2, ... However, acquisition time N
Can take from 0 to the upper limit acquisition time N0. In this example
Is [N0 = 35]. Also, in equation (1),
If the value of N-1 is not defined, then [M_N-1= M_N-2
= ... = 0]. For example, when [N = 0], [Y
₀= M₀] Becomes. For each capture time N according to equation (1)
Accumulated number of received waves Y_NThe largest of the largest
Total number of received waves Y_XAnd the maximum cumulative number of received waves Y_XGive maximum
Frequency hour import time N_XUsing and, the arrival time of sebum echo
Ta can be obtained by the equation (2).

[0015]

[Equation 2]

N _{X + 1} , N _{X + 2} , ...: Retrieval timing N, respectively
_{X + 1, N X + 2} , ... M X + 1, M X + 2, ...: each, taking time N _X + 1, N _X +
The number of waves received at 2, ... By the way, the skin fat thickness D is given by the equation (3).

[0017]

(Equation 3)

Here, the predetermined time interval Ts [μsec]
Is the propagation velocity c of the ultrasonic pulse in the subcutaneous fat tissue Mb.
Since it is set so that the relationship of [c × Ts = 2 mm] with [mm / μsec] is approximately satisfied, if the arrival time Ta of the sebum echo is [Ta = Ts], the sebum thickness D Is calculated as [D = 1 mm]. Therefore, the skin fat thickness D [mm] is calculated by the equation (4).

[0019]

(Equation 4)

That is, although the uptake time N is a dimensionless quantity, the calculation result of the equation (4) becomes the skin fat thickness D expressed in millimeters as it is.

The RAM 10 has a working area in which a work area of the CPU 11 is set and a data area for temporarily storing various data, and the data area is loaded at each loading time N at each measuring time K. An echo data memory area or the like for storing a value, the number of received waves M _N for each acquisition time N after the measurement of a predetermined number of times of measurement, and the like are set. The CPU 11 executes the above-described various processing programs stored in the ROM 9 using the RAM 10 to control each part of the device including the pulse generator 4 and the waveform shaper 7, and emits one pulse to generate one group. Each time the echo of the above is received, the captured value of the signal S corresponding to the presence or absence of the echo is received from the serial I / O8, and the change of the captured value from "1" to "0" is detected. Then, the number of echo receptions M _N for each acquisition time N is obtained, and the skin fat thickness D is further obtained. Further, the display 12 is composed of a liquid crystal display or the like, and displays the calculated skin fat thickness D in millimeters under the control of the CPU 11.

Next, the operation of this example (mainly the processing flow of the CPU 11 in calculating the skin fat thickness) will be described with reference to FIGS. When the device is powered on, the CPU 11 waits for the measurement start switch to be pressed after presetting each part of the device, initializing counters, various registers, and various flags (step SP10 (FIG. 5)). (Step SP11). Here, the operator
As shown in FIG. 3, the ultrasonic gel 13 is applied to the surface W of the skin Ma of the abdomen that is the measurement site of the subject, and the ultrasonic gel 1
The transducer 1 is applied to the surface W of the skin Ma via 3 and the transmitting / receiving surface is directed to the living tissue under the cortex Ma.
Turn on the measurement start switch. When the measurement start switch is turned on (step SP11), the CPU 11 starts the measurement operation according to the processing procedure shown in FIG.

The CPU 11 rewrites the value of the measurement time K from the initial setting value "0" to "1" (step SP12),
Start the first measurement. The CPU 11 first issues a 1-pulse generation command to the pulse generator 4 (step SP
13). When the pulse generator 4 receives the 1-pulse generation command from the CPU 11, the pulse generator 4 transmits an electric pulse signal to the transducer 1. The transducer 1 is a pulse generator 4
When the electric pulse signal is supplied from the
The ultrasonic pulse Ai is emitted toward the biological tissue under a (it can be regarded as a plane wave during a short distance to be handled). As shown in FIG. 3, the ultrasonic pulse Ai emitted from the transducer 1 is transmitted to the ultrasonic delay spacer 1b.
Is partially reflected by the end surface on the side of the skin Ma, and the rest is the skin Ma
Is injected from the surface W into the skin Ma. Furthermore, the skin M
The ultrasonic pulse injected into a is partially reflected by the boundary surface X between the skin Ma and the subcutaneous fat tissue Mb, and the rest is injected into the subcutaneous fat tissue Mb. The ultrasonic pulse injected into the subcutaneous fat tissue Mb is partially reflected by, for example, a blood vessel in the subcutaneous fat tissue Mb, and the rest is subcutaneous fat tissue Mb.
To the boundary surface Y between the muscle tissue Mc and the muscle tissue Mc. Then, a part thereof is reflected by the boundary surface Y to become a sebum echo Ae, and the rest is injected into the muscle tissue Mc to form the muscle tissue Mc and the organ M.
It reaches the boundary surface Z with d, and a part thereof is reflected by the boundary surface Z. A group of echoes such as the sebum echo Ae follows a path opposite to that of the incident ultrasonic wave Ai, and is received again by the ultrasonic transducer 1a of the transducer 1. Therefore, in the transducer 1, after the ultrasonic pulse Ai is emitted, first the transmission reverberation is followed by the end face echo with a slight delay,
The echo reflected by blood vessels in the subcutaneous fat tissue Mb (hereinafter referred to as the subcutaneous fat tissue echo) is further delayed,
The sebum echo Ae and, thereafter, echoes from the boundary surface Z between the muscle tissue Mc and the organ Md (hereinafter referred to as muscle tissue echo) are respectively received by the ultrasonic transducer 1a, and an electrical received signal is received. Respectively converted to. The generated received signal is input to the apparatus main body 2 (matching circuit 5) via the cable 3, amplified by the amplifier 6 with a predetermined amplification degree, and input to the waveform shaper 7. Here, in the waveform shaper 7, as shown in FIG. 4, the signal p1 corresponding to the end face echo, the signal p2 corresponding to the subcutaneous fat tissue echo, and the sebum echo Ae, as shown in FIG.
Signal p3 corresponding to, the signal p corresponding to muscle tissue echo
Input in the order of 4.

The waveform shaper 7 compares the received signals corresponding to a group of echoes including the above-mentioned signals p1, p2, p3 and p4, which are input, with the reference detection voltage Vt by the comparator, and compares them with the reference detection voltage. "1" when Vt is not exceeded,
When it exceeds, it is converted to a signal S corresponding to the presence or absence of echo that becomes "0" (step SP14), and serial I / O
8 is sent. The serial I / O 8 acquires the signal S corresponding to the presence or absence of this echo at the acquisition cycle Ts,
The captured value captured is transferred to the CPU 11. CPU11
Is a capture value S ₁₀ , which indicates the presence or absence of reception of a total of 36 1-bit echoes from the serial I / O 8 from the capture timing N of 0 to 35, that is, up to the 35th cycle.
S _11, S _12, ..., by sequentially incorporating S _135, as data measurement count K representing the presence or absence of echo in the case of 1, RAM 1
0 is stored in the echo data memory area (step S
P15). Next, among the 36 acquisition values stored in the RAM 10, the value “1” at the previous acquisition time (N−1) has changed to the value “0” at the current acquisition time N. Find the capture value, and associate the capture time N with the value "1" of the detected value m _{1N indicating} the presence or absence of a change from "1" to "0",
When there is no change from "1" to "0", the detected value m
The value of _1N is set to "0" (step SP16). here,
The values of m ₁₀ , m ₁₁ , m ₁₂ , and m ₁₃ are set to "0", and the signal p that is taken before the signal p3 corresponding to the sebum echo Ae is taken.
Exclude unnecessary signals such as 1, p2 (step SP1
7). Then, the values of these detected values m _1N (N = 0 to 35) are also stored in the echo data memory area of the RAM 10.

Next, the CPU 11 receives the number of waves M _N (N = 0) at the acquisition time N to be integrated.
~ 35), if the detected value m _1N is "1",
"1" is added to the previous value, and if the detected value _m1N is "0", it is left as it is (step SP18). Since this time is the first measurement (K = 1), the detected value m is set to the initial value “0”.
Add the value of _1N . As a result, the number of received waves M
_{In N} (N = 0 to 35), it is checked whether or not there is one whose value is the upper limit cumulative frequency M0 (M0 = 15 in this example) (step SP19). If none of them reaches 15, it is determined whether or not the current measurement count K is the upper limit measurement count K0 (K0 = 127 in this example) (step SP20). As a result, when the current measurement number K does not reach the upper limit measurement number K0, the value of the measurement number K is "1".
Is added (step SP21), the process proceeds to the next measurement, and the processes after step SP13 are repeated. If the current measurement number K reaches the upper limit measurement number K0, the calculation of the integrated wave number Y _N is started (step SP22). In step SP19, even if one of the number of receptions M _N (N = 0 to 35) has a value of 15,
Start the calculation of the cumulative number of waves Y _N. Here, for each acquisition time N (N = 0 to 35), the value of the cumulative number of times of wave reception Y _N is calculated according to the equation (1), and the calculation result is stored in the echo data memory area of the RAM 10. To do.
The results of the number of wave receptions M _N and the total number of wave receptions Y _{N at} N = 0 to 35 are shown in Table 1, for example.

[0026]

[Table 1]

The CPU 11 then proceeds to step SP22.
Total number of received waves Y calculated in _N(N = 0 to 35)
The maximum cumulative number of received waves Y that has the maximum value from_XChoose
This is the maximum cumulative number of received waves Y_XMaximum frequency corresponding to
Acquisition time N_XEcho data memory of RAM10
It is stored in the area (step SP23). Where the expression
Maximum cumulative number of received waves Y according to (1)_XWhen seeking
Taken after the signal p3 corresponding to the sebum echo Ae
For the signal p4 corresponding to the muscle tissue echo,
For example, in equation (1), the number of received waves M_NTakes the signal p4
If it is equivalent to the number of waves received,
For several cycles including the number of waves received when the signal p3 of
Sum of the number of received waves [M_N-5+ ... + M_N-11] To the coefficient "2"
Multiply the value by the number of received waves M_NWill be deducted from
Then, the total number of received waves at this time Y_NIs the maximum cumulative number of received waves Y_X
Will not be. Therefore, for the calculation of the skin fat thickness D after that,
By the way, the influence of the muscle tissue echo is eliminated. CPU1
1 then calculates the skin fat thickness D according to equation (4)
(Step SP24), the calculation result is displayed in mm on the display unit 12.
Display in units (step SP25). In this example,
From the measurement results shown in Table 1, [N_X= 9],
It is calculated as [D = 9 mm].

According to the above construction, since the presence or absence of an echo is detected and the sebum echo Ae reflected and returned at the boundary surface Y between the subcutaneous fat tissue Mb and the muscle tissue Mc is detected, it is output from the waveform shaper 7. The signal S corresponding to the presence or absence of the echo to be used is sufficient for one bit, and therefore, the hardware can be greatly simplified and the cost can be suppressed to a low level as compared with the method of measuring the intensity of the echo. Also, the operation time can be shortened significantly. Also, sebum echo A
After detecting a change in the captured value of the signal S from "1" to "0" corresponding to the presence or absence of the echo of e, for example, the detected values m ₁₀ , m ₁₁ , m ₁₂ , m ₁₃ are set to " By setting it to "0", the influence of transmission reverberation, end face echo, etc. can be eliminated, and the total number of received waves Y _N is calculated using the formula (1) to find the maximum number of received waves Y _X. Thus, for example, the accumulated number of times of reception Y _N corresponding to the muscle tissue echo reflected and returned at the boundary surface Z between the muscle tissue Mc and the organ Md can be eliminated, so that the subcutaneous fat tissue and the muscle tissue can be separated from each other. Since the accumulated wave number Y _N corresponding to the sebum echo Ae reflected and returned at the boundary surface can be selected as the maximum accumulated wave number Y _X , the sebum thickness D can be accurately calculated. Further, since the ultrasonic wave is emitted a number of times for measurement, the skin fat thickness D is calculated based on the maximum cumulative number of receptions Y _X obtained from the equation (1) from the temporal distribution of the number of receptions M _N of the echo. It is possible to measure with higher accuracy. The acquisition cycle TS is
The product [cTS] of the sound velocity c in subcutaneous adipose tissue is approximately 2 mm
(That is, the sebum thickness D is equivalent to about 1 mm), so if the number of cycles is known, the sebum thickness D
You can know immediately. Furthermore, the waveform shaper 7
In the comparator, a predetermined reference detection voltage VT is compared with the signals p1, p2, p3, p4, etc., and a signal S corresponding to the presence or absence of a 1-bit echo of "1" or "0"
, Which weak signals such as the signal p2 are excluded here, which helps to efficiently extract the desired signal.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like that do not depart from the gist of the present invention. Is also included in the present invention. For example, in the above-mentioned embodiment, the upper limit cumulative frequency is set to 15, but it may be higher. Similarly, the upper limit number of measurements is not limited to 127. Further, the upper limit acquisition timing is not limited to 35. Further, the ultrasonic transducer constituting the transducer is not limited to the thickness vibration type, but may be a flexural vibration type. Similarly, the center frequency used is not limited to 1 MHz. Further, an algorithm for judging the degree of obesity of the subject based on the calculated skin fat thickness of the subject may be stored in the ROM, and the result calculated by the CPU by this algorithm may be output to the display. In addition, in the above-described embodiment, the skin fat thickness of the abdomen was measured, but the measurement site is not limited to the abdomen. Further, in the equation (1), the coefficient of each term on the right side is M
_{For N} , M _N-1 , M _N-2 , and M _N-3 , “1”, M _N-5 ,
, -M _N-11 is set to "-2", but the values are not limited to these values and may be changed as appropriate. Further, similarly, each term of the numerator on the right side of the equation (4), N _X M _X , N _{X + 1} M _{X + 1} , N
_{X + 2} M _{X + 2} , N _{X + 3} M _{X + 3} coefficients, denominator terms, M _X ,
The coefficients of M _{X +1} , M _{X + 2} , and M _{X + 3} do not necessarily have to be “1”, and can take different values. Further, in the equation (4), the calculation is performed within the range of four cycles, but the number may be increased or decreased as appropriate. further,
The uptake period is set so that the product of the uptake period and the speed of sound in the subcutaneous fat tissue is approximately 2 mm, but it is not limited to 2 mm.

[0030]

According to the structure of the present invention, since the presence or absence of an echo is detected and the sebum echo reflected back at the boundary between the subcutaneous fat tissue and the muscle tissue is detected, the echo presence / absence signal generating means is used. The signal corresponding to the presence or absence of the output echo is sufficient to be 1 bit, and therefore, the hardware can be greatly simplified and the cost can be kept low as compared with the method of measuring the intensity of the echo. Also, the operation time can be shortened significantly. Further, when counting the number of echoes at each acquisition time by the skin fat thickness calculating means, for example, the effects of transmission reverberation and end face echo can be eliminated, and echoes can be obtained using a predetermined recurrence formula. In the process of obtaining the maximum value of the distribution of presence, for example, it is possible to remove the influence of echoes reflected and returned at the boundary surface between the muscle tissue and the organ that comes after the sebum echoes. Information can be extracted accurately. Therefore, the skin fat thickness can be accurately calculated.
Furthermore, if the ultrasonic wave is emitted a number of times for measurement and the sebum thickness is calculated based on the maximum value showing the distribution with echo obtained by a predetermined recurrence formula from the temporal distribution of the number of times with echo It is possible to measure with higher accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an ultrasonic skin fat thickness measuring apparatus according to an embodiment of the present invention.

FIG. 2 is an external view of the device.

FIG. 3 is a schematic view showing a usage state of the apparatus.

FIG. 4 is an explanatory diagram used for explaining an operation of the device.

FIG. 5 is a flowchart showing an operation processing procedure of the apparatus.

[Explanation of symbols]

1 Transducer (Ultrasonic Transducer) 1a Ultrasonic Transducer (Transducer) 1b Ultrasonic Delay Spacer (Delay Member) 7 Waveform Shaper (Echo Presence / Absence Signal Generation Means) 8 Serial I / O (Part of Skin Oil Thickness Calculation Means) 11 CPU (transmission control means, part of skin fat thickness calculation means) Ai ultrasonic pulse (ultrasound) Ae sebum echo (part of echo)

Claims (3)

[Claims] 1. An ultrasonic transducer for transmitting and receiving ultrasonic waves, comprising an oscillator for performing mutual conversion between electric signals and ultrasonic waves, and a delay member for transmitting ultrasonic waves, and transmission of ultrasonic waves by the ultrasonic transducer. A transmission control means for controlling the signal, an echo presence / absence signal generation means for generating and outputting a signal corresponding to the presence or absence of an echo based on a signal received by the input ultrasonic transducer, and the echo presence / absence signal generation means. And a skin fat thickness calculating means for calculating a predetermined skin fat thickness of the living body based on the output of
(K is a natural number of 2 or more) is transmitted, and the skin-fat-thickness calculating means determines an output signal from the echo presence / absence signal generating means every time the ultrasonic transducer transmits an ultrasonic wave. , The number of echoes for each acquisition time is determined by excluding the transmission reverberation and the end face echo reflected by the end surface of the delay member, and the echo with respect to the acquisition time is calculated using a predetermined recurrence formula. It is an ultrasonic skin fat thickness measuring device configured to convert a value showing a distribution and further obtain a maximum value of a value showing the distribution with the echo, and calculate a skin fat thickness based on the maximum value. Then, the recurrence formula is the number of times with echo for each of the N-th (N is 0 or a natural number) acquisition time of interest and an arbitrary plurality of acquisition times before the acquisition time. The sum of the values obtained by multiplying by a predetermined coefficient Is an equation that gives as a value indicating the distribution with echo at the Nth capture time. 2. The recurrence formula is based on a sum of the number of times with echo for each of the N-th acquisition time of interest and an arbitrary plurality of acquisition times before the acquisition time, The result of subtracting the value obtained by subtracting the value obtained by multiplying the sum of the number of times with echoes for each of a plurality of consecutive acquisition times before the plurality of acquisition times by a predetermined coefficient of 2 or more is N-th. Along with the expression given as a value indicating the distribution with the echo at the acquisition time, the skin fat thickness calculating means, the maximum value of the value showing the distribution with the echo obtained using the predetermined recurrence formula. The ultrasonic skin fat thickness according to claim 1, wherein the skin fat thickness is calculated on the basis of the intake time to be given, and based on the intake time and the number of echoes at the intake time. measuring device. 3. The echo presence / absence signal generation means responds to the presence or absence of the echo by comparing the input signal received by the ultrasonic transducer with a predetermined threshold value which is a decay function of time. The ultrasonic skin fat thickness measuring device according to claim 1 or 2, wherein the device is configured to output a signal.