JPH0650264B2 - Temperature measuring method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a technique for externally measuring the temperature of a measurement target that is inaccessible from the outside by using ultrasonic waves.

[Conventional technology]

2. Description of the Related Art Conventionally, as a method for measuring the temperature inside a living body such as a human body, there is a technique in which a sensor unit such as a thermocouple of a temperature measuring device is brought into contact with a measurement target such as a stomach or liver inside the human body to measure the temperature. This is shown in FIG. In FIG. 12, 1 is a section of a human body, 2 is a heater for heating, 3 is an object to be measured, and 4 is a thermocouple for temperature measurement. As can be seen from the figure, conventionally, the temperature of the measurement target 3 was measured by inserting the thermocouple 4 inside the human body.

[Problems to be Solved by the Invention]

However, in the above-mentioned conventional techniques, since the thermocouple 4 is inserted inside the human body, there are drawbacks that the human body is painful and that anesthesia is required to stop the pain.

Further, as shown in FIG. 13, when measuring the temperature of the measuring object 7 inside the structure 6, it is necessary to make a hole for inserting a sensor unit such as a thermocouple 8 for temperature measurement. Since the shape around the measurement target 7 is different from the actual structure,
There was a drawback that the temperature distribution of the measurement part was also different from the actual one. In addition, there is also a drawback that it requires a processing cost for making a hole.

The present invention has been made in view of the above points, and an object of the present invention is to provide a temperature measuring method and apparatus for measuring the temperature of a measurement target that is inaccessible from the outside.

[Means for Solving the Problems]

In order to achieve such an object, the temperature measuring method according to the present invention transmits an ultrasonic wave to a measuring object that is not accessible from the outside, receives a reflected wave from the measuring object, and frequency-tunes the received reflected wave in a short time unit. The temperature of the measurement target is calculated using the peak frequency and the half-width, which are characteristic of the frequency distribution of the received wave subjected to the analysis and frequency analysis.

The temperature measuring device according to the present invention includes a temperature measuring ultrasonic sensor for transmitting and receiving ultrasonic waves, an ultrasonic transmitting / receiving circuit for transmitting / receiving ultrasonic waves, and a received wave A / D for A / D converting the received wave. The signal processing unit includes a conversion unit and a signal processing unit.
The A / D-converted received wave is cut out in a short time and frequency-analyzed. The peak frequency and half-width are calculated from the frequency distribution of the frequency-analyzed received wave, and the temperature-peak frequency and temperature-half-width obtained in advance are calculated. The temperature is calculated from the relationship of.

[Action]

In the present invention, it is possible to measure the temperature of the measurement target that is inaccessible from the outside.

〔Example〕

FIG. 1 is an explanatory view for explaining a measuring method when the temperature inside the human body is measured by using an embodiment of the temperature measuring device according to the present invention. In the figure, 11 is an ultrasonic sensor for temperature measurement, 12 is an ultrasonic device body for temperature measurement, and 1
Reference numeral 3 is a propagation path of ultrasonic waves propagating inside the human body, 14 is a cross section of the body of the human body, 15 is a heater for heating, 16 is a measuring object, and the ultrasonic sensor 11 for temperature measurement and the temperature measuring long ultrasonic device main body 12 are provided. And constitute a temperature measuring device. When the human body is heated from the outside of the body using the heating heater 15 in the cross section 14 of the body of FIG.
Becomes high temperature. An ultrasonic wave is transmitted from the temperature measuring ultrasonic sensor 11 to the measurement target 16, the received wave is received by the temperature measuring ultrasonic sensor 11, and the temperature measuring ultrasonic device main body 12 calculates the temperature. Although the ultrasonic sensor 11 in FIG. 1 has both a transmitting function and a receiving function, the same effect can be obtained by using two separate sensors.

FIG. 2 is a system diagram showing the temperature measuring ultrasonic device main body 12 of FIG. In FIG. 2, reference numeral 21 is an ultrasonic transmission / reception circuit, 22 is a received wave A / D conversion unit, 23 is a signal processing unit,
Reference numeral 24 is a display, and 25 is a printer. The ultrasonic transmission / reception circuit 21 is a circuit for transmitting and receiving ultrasonic waves from the ultrasonic sensor 11 for temperature measurement shown in FIG. The reception wave A / D conversion unit 22 is a unit that converts a received analog signal into a digital signal for subsequent signal processing. The signal processing unit 23 is the most important part of this embodiment, and a flowchart for explaining its operation is shown in FIG. The display 24 is for displaying the temperature measurement result, and the printer 25 is also for printing out the measurement result.

Next, the operation of the signal processing unit 12, which is the most important part of this embodiment, will be described with reference to FIG. The received wave A / D converted by the received wave A / D converter 22 (see FIG. 5) is 1
It is cut out in a short time of about the wavelength (steps 31, 3
2). There are several cutting methods as shown in FIGS. 6 (a) and 6 (b). Thereafter, the cut out wave is subjected to frequency analysis (step 33), and the peak frequency PF and the half width WF (see FIG. 4) are calculated from the frequency distribution (step 34). Further, the temperature is calculated from the relationship between the temperature and the peak frequency and the temperature and the half value width which are obtained in advance (step 34).

FIGS. 6 (a) and 6 (b) show an example of a method of cutting out a received wave in a short time of about one wavelength. In Fig. 6 (a), NO.1, NO.2,
.. are cut out at intervals of about 1 wavelength without overlapping each other, but when accuracy is required, the positions are cut out by slightly shifting (.DELTA.t) as shown in FIG. 6 (b). Better

In FIGS. 5 and 6, reference numeral 36 denotes a reflected waveform from the measurement target.

FIG. 7 is a graph showing the relationship between the temperature and the peak frequency in the case of a human body. The ultrasonic signal frequency in this case is 5 MH
z, ambient temperature is 17 ° C. As can be seen from FIG. 7, the peak frequency rises as the temperature rises.
This is because the impedance for ultrasonic waves increases at the boundary between the measurement target 16 and other portions as the temperature rises, so that the reflection of ultrasonic waves at the boundary between the measurement target and
It is considered that the attenuation of ultrasonic waves due to absorption is reduced.

FIG. 8 is a graph showing the relationship between the temperature and the half width in the case of a human body. As can be seen from the figure, the full width at half maximum tends to become narrower as the temperature rises. It is considered that this is because the impedance of the ultrasonic wave increases at the boundary surface as the temperature rises and the attenuation of the ultrasonic wave decreases as in the above case. The ultrasonic signal frequency and the ambient temperature are the same as in the case of FIG.

There are various factors of attenuation related to the reflection and absorption of these ultrasonic waves, and when applied to temperature measurement, there are large variations in temperature measurement. Therefore, improvement in measurement accuracy is ensured by using both the peak frequency and half width of ultrasonic waves as measurement parameters.

FIG. 9 is an explanatory diagram for explaining one embodiment of the temperature measuring method according to the present invention. In the figure, 41 is an ultrasonic sensor for temperature measurement, 42 is an ultrasonic device main body for temperature measurement, 43 is a propagation path of ultrasonic waves propagating inside the structure, 4
4 is a structure and 45 is an object to be measured. In FIG.
An ultrasonic wave is transmitted from the temperature measuring ultrasonic sensor 41 to the target measuring object 45 from the outside of the structure 44, and the received wave is received by the temperature measuring ultrasonic sensor 41. The temperature is calculated by the main body 42. Although the ultrasonic sensor 41 has both a transmitting function and a receiving function in this embodiment, the same effect can be obtained by using two separate sensors.

FIG. 10 is a graph showing the relationship between temperature and peak frequency in the case of a structure. The ultrasonic signal frequency in this case is 5
MHz, ambient temperature is 500 ° C. In FIG. 10, the peak frequency rises as the temperature of the measurement target 45 rises.

FIG. 11 is a graph showing the relationship between the temperature and the half-value width in the case of a structure. In the figure, the half-width narrows as the temperature of the measurement target 45 rises. Also in this case, the measurement accuracy can be improved by using both the peak frequency and the half width. The ultrasonic signal frequency and the ambient temperature are the same as in the case of FIG.

〔The invention's effect〕

As described above, the present invention transmits an ultrasonic wave to a measurement target that is not accessible from the outside, receives a reflected wave from the measurement target, frequency-analyzes the received reflected wave in short time units, and receives the frequency-analyzed received wave. Calculate the peak frequency and half width from the frequency distribution of
By determining the temperature from the relationship between the temperature and the half-value width, there is an effect that the temperature of the measurement target that cannot be accessed from the outside can be measured.

[Brief description of drawings]

FIG. 1 is an explanatory view for explaining a method of measuring the temperature inside a human body using an embodiment of the temperature measuring device according to the present invention, and FIG. 2 is an ultrasonic device for temperature measurement shown in FIG. A system diagram showing the main body, FIG. 3 is a flow chart for explaining the operation of the temperature measuring ultrasonic wave device main body of FIG. 2, FIG. 4 is a graph showing peak frequency and half width, and FIG. 5 is A / D. FIG. 6 is a waveform diagram showing the converted reception waveform in an analog manner, FIG. 6 is a waveform diagram for explaining the method of cutting out the reception wave, and FIG. 7 is a graph showing the relationship between the temperature and the peak frequency in the case of the human body,
FIG. 8 is a graph showing the relationship between the temperature and the half width in the case of a human body, FIG. 9 is an explanatory view for explaining an embodiment of the temperature measuring method according to the present invention, and FIG. 10 is a case of a structure. FIG. 11 is a graph showing the relationship between temperature and peak frequency, FIG. 11 is a graph showing the relationship between temperature and half width in the case of a structure, and FIG. 12 is an explanatory view for explaining a temperature measuring method inside a human body according to the prior art, FIG. 13 is an explanatory diagram for explaining a conventional method for measuring the temperature inside a structure. 11 ... Ultrasonic sensor for temperature measurement, 12 ... Ultrasonic device body for temperature measurement, 13 ... Propagation path, 14 ... Cross section of human body, 15 ... Heating heater, 16 ... Measurement object, 2
1 ... Ultrasonic wave transmitting / receiving circuit, 22 ... Received wave A / D conversion section, 23 ... Signal processing section, 24 ... Display, 25
...... Printer.

Claims (2)

[Claims] 1. An ultrasonic wave is transmitted to a measurement target that is inaccessible from the outside, a reflected wave from the measurement target is received, the received reflected wave is frequency-analyzed in a short time unit, and the frequency distribution of the frequency-analyzed received wave is analyzed. The temperature measuring method for calculating the temperature of the measurement target using the peak frequency and the half-width representing the characteristics of the above. 2. An ultrasonic sensor for temperature measurement, which transmits and receives ultrasonic waves, and an ultrasonic wave transmission / reception circuit which transmits / receives ultrasonic waves.
A reception wave A / D conversion unit that performs A / D conversion on the reception wave and a signal processing unit are provided, and the signal processing unit cuts out the reception wave that has been A / D converted in a short time and analyzes the frequency, A temperature measuring device that calculates a peak frequency and a half width from the analyzed frequency distribution of a received wave and obtains a temperature from a previously determined relationship between the temperature and the peak frequency and the half width.