JP3622753B2 - Radiation thermometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation thermometer that measures the temperature of a human body with infrared rays emitted from the eardrum or the like.
[0002]
[Prior art]
In recent years, a radiation thermometer has been developed that can measure a body temperature in a short time compared to an electronic thermometer using a thermistor that measures the body temperature in the mouth or armpit. This type of radiation thermometer can measure body temperature by detecting infrared rays emitted from the ear drum.
[0003]
FIG. 10 is a block diagram for explaining the configuration of a radiation thermometer described in Japanese Utility Model Laid-Open No. 55-145329. Infrared rays are radiated from the eardrum through the probe 1 used by inserting into the ear canal. This infrared ray is proportional to the temperature of the human body and is detected by the pyroelectric infrared detection element 3. A chopper 2 is arranged in front of the pyroelectric infrared detection element 3, and the incident infrared ray is interrupted, and an electric signal corresponding to the amount of infrared detected by the pyroelectric infrared detection element 3 is continuously provided. Trying to get. This electrical signal is transmitted to the body temperature measuring means 4, the body temperature measuring means 4 calculates the temperature, and the display means 5 displays the temperature. A power source 6 supplies power to the chopper 2 and each part.
[0004]
[Problems to be solved by the invention]
The conventional radiation thermometer has a configuration in which the chopper is continuously driven from the time when the power is supplied until the measurement is finished, and there is a problem that unnecessary power consumption is large.
[0005]
[Means for Solving the Problems]
In the present invention, the chopper driving means for driving the chopper is driven by using the chopper power source means at the time of measurement, thereby providing an economical radiation thermometer.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 is a radiation thermometer capable of measuring body temperature with high accuracy with reduced influence of room temperature by switching the reference voltage of the AD conversion means according to room temperature.
[0007]
The invention described in claim 2 is a radiation thermometer capable of notifying the user of an abnormality so that the body temperature measuring means displays the abnormality of the disconnection of the sensor temperature detecting means on the display means.
[0008]
The invention described in claim 3 is a radiation thermometer in which the body temperature measuring means determines the abnormality of the chopper from the temperature signal of the infrared sensor and notifies the display means of the abnormality.
[0009]
The invention described in claim 4 is a radiation thermometer capable of measuring the body temperature with high accuracy by driving the shielding part to grasp the influence of noise before starting measurement of the body temperature and removing the noise. Yes.
[0010]
The invention described in claim 5 is a radiation thermometer in which the chopper driving means soft-starts the chopper and can stably measure the body temperature.
[0011]
According to the sixth aspect of the present invention, the chopper driving means drives the chopper with a sine waveform or a cosine waveform to provide a radiation thermometer with low chopper operating sound.
[0012]
【Example】
(Reference Example 1)
The first reference example of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of this reference example. Reference numeral 10 denotes a thin-film pyroelectric infrared sensor (hereinafter simply referred to as an infrared sensor 10) that receives infrared rays emitted from the eardrum through the probe 1. One of the detection signals of the infrared sensor 10 is transmitted directly to the body temperature measuring means 12, and the other one is transmitted to the body temperature measuring means 12 via the sensor temperature detecting means 11. The sensor temperature detecting means 11 is constituted by a thermistor.
[0013]
The body temperature measuring means 12 is constituted by a microcomputer, and the body temperature is calculated from the signal from the sensor temperature detecting means 11 and the signal from the infrared sensor 10 and displayed on the display means 13. A chopper 14 is disposed in front of the infrared sensor 10. The chopper 14 is made of a piezoelectric material such as ceramic, and vibrates using the resonance by the power source supplied by the chopper driving means 15 to open and close the light entrance window of the infrared sensor 10. Reference numeral 16 denotes chopper power supply means for supplying power to the chopper driving means. In this reference example, the voltage of the battery is boosted by a booster circuit. The chopper power supply means 16 operates according to instructions from the body temperature measuring means 12.
[0014]
Although the infrared sensor 10 of this reference example uses a thin film pyroelectric type, it may be replaced with a pyroelectric infrared sensor made of a dielectric material such as ceramic.
[0015]
The operation of this reference example will be described below. When a power supply (not shown) is turned on and a measurement start button is pressed, each unit starts operating. That is, the infrared sensor 11 starts detecting infrared rays emitted from the eardrum via the probe 1. The infrared sensor 11 generates an amount of electric charge according to the difference between its own temperature and the temperature obtained from the light entrance window. The sensor temperature detecting means 11 detects the self temperature of the infrared sensor 10. The signals of the infrared sensor 10 and sensor temperature detecting means 11 are transmitted to the body temperature measuring means 12.
[0016]
In this reference example, the chopper 14 is driven during the body temperature measurement. That is, the chopper power supply means 16 supplies power to the chopper driving means 15 according to an instruction from the body temperature measuring means 12, and the chopper driving means supplies a drive signal for the chopper 14. As a result, the infrared sensor 10 generates a signal as shown in FIG. FIG. 2B is a waveform showing the driving state of the chopper 14, and shows how the light incident window of the infrared sensor 10 is opened and closed as a result of vibration caused by the driving signal of the chopper driving means 15. The signal generated in the infrared sensor 10 repeats a cycle of detecting the infrared ray of the body temperature while the light entrance window is open and detecting the infrared ray of the chopper while the light entrance window is closed. Can be detected.
[0017]
As described above, the peak voltage of this signal is proportional to the difference between the body temperature of the measurer and the self-temperature of the infrared sensor 10. The body temperature measurement means 12 measures the body temperature of the measurer by calculating the signal of the infrared sensor 10 and the signal of the sensor temperature detection means 11 and displays it on the display means 13.
[0018]
In particular, in this reference example, the chopper power supply means 16 is driven only at the time of measurement, and is stopped when the body temperature display is viewed. Thus, power consumption is reduced without consuming unnecessary power. This is the realization of a radiation thermometer.
[0019]
(Reference Example 2)
Next, a second reference example of the present invention will be described with reference to FIG. This reference example includes amplification means 17 for amplifying the signal of the infrared sensor 10 and amplification factor variable means 18 for changing the amplification factor of the amplification means 17 according to the signal of the sensor temperature detection means 11.
[0020]
The operation of this reference example will be described below. As described in Reference Example 1, the output signal of the infrared sensor 10 is proportional to the difference between the human body temperature and room temperature. Therefore, when this difference is small, that is, when the room temperature is high, the output signal of the infrared sensor 10 is small, and the body temperature calculated and displayed by the body temperature measuring means 12 is also low in accuracy.
[0021]
Therefore, in this reference example, the signal from the infrared sensor 10 is amplified by the amplifying means 17 and sent to the body temperature measuring means 12. At this time, the amplification factor of the amplification unit 17 is determined by the signal of the amplification factor variable unit 18 that operates according to the signal of the sensor temperature detection unit 11. That is, when the room temperature is high and the output voltage of the infrared sensor 10 is small, the amplification factor varying means 18 determines the amplification factor to be high. When the room temperature is low and the output voltage of the infrared sensor 10 is large, the gain variable means 18 determines the gain to be relatively low.
[0022]
As described above, according to the present reference example, since the amplification factor varying means 18 determines the amplification factor according to the room temperature, the influence of the room temperature can be reduced, and a radiation thermometer with high measurement accuracy can be realized. is there.
[0023]
(Example 1)
Next, a first embodiment of the present invention will be described with reference to FIG. In the present embodiment, AD conversion means 19 for AD converting the signal of the infrared sensor 10 and voltage switching means 20 for switching the voltage level of the AD conversion means 19 are provided. The voltage switching unit 20 adjusts the switching level according to the signal from the sensor temperature detection unit 11.
[0024]
The operation of this embodiment will be described below. The AD conversion means 19 converts an analog signal detected by the infrared sensor 10 into a digital signal. The voltage switching unit 15 switches the reference voltage of the AD conversion unit 19 based on a signal from the temperature detection unit 11. This reference voltage determines the resolution per bit of the AD conversion means 19. That is, when the difference between room temperature and body temperature is small, the output voltage of the infrared sensor 10 is small, so the reference voltage is reduced to increase the resolution per bit and improve the measurement accuracy.
[0025]
When the difference between the room temperature and the body temperature is large, the output voltage of the infrared sensor 6 is large. Therefore, the measurement range is widened by increasing the reference voltage to lower the resolution per bit. That is, the voltage of the AD conversion means 19 is changed to reduce the influence of room temperature, and a radiation thermometer with high measurement accuracy is realized.
[0026]
(Example 2)
Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the present embodiment. In the present embodiment, the temperature measuring unit 12 includes a sensor temperature abnormality detection unit 22 that detects an abnormality such as a disconnection of the sensor temperature detection unit 11.
[0027]
The operation of this embodiment will be described below. The sensor temperature detection means 11 includes a thermistor and a reference resistance, and transmits a power supply voltage divided by the reference resistance and the resistance of the thermistor to the body temperature measurement means 12 as a signal indicating temperature. The resistance value of the thermistor changes according to the temperature of the infrared sensor 10 by changing the resistance value of the thermistor depending on the sensor temperature. Therefore, the resistance of the sensor temperature detecting means 11 as a whole is also the resistance of the infrared sensor 10. It changes according to temperature.
[0028]
At this time, for example, if the thermistor constituting the sensor temperature detecting means 11 is broken or the lead wire to be connected is disconnected, the resistance value detected by the sensor temperature detecting means 11 becomes very large and the signal voltage is high. Is output. This signal is checked by the sensor temperature abnormality detecting unit 22 of the body temperature measuring means 12, and in the case of the abnormal state described above, the body temperature measuring means 12 is displayed on the display means 13, the sensor temperature detecting means 11 is disconnected, etc. Execute the abnormal display.
[0029]
As described above, according to the present embodiment, the sensor temperature abnormality detection unit 22 can detect an abnormality such as disconnection of the sensor temperature detection means 7 and notify the user of the abnormality.
[0030]
(Example 3)
Next, a third embodiment of the present invention will be described. FIG. 6 is a block diagram showing the configuration of this embodiment. In this embodiment, the body temperature measuring unit 12 detects the phase of the temperature signal of the infrared sensor 10 and the chopper abnormality that detects the amplitude displacement abnormality of the chopper 10 from the phase information detected by the phase detection unit 23. A detection unit 24 is provided.
[0031]
The operation of this embodiment will be described below. The phase detector 23 detects the phase of the temperature signal of the infrared sensor 6. The signal detected by the infrared sensor 10 has the same charging time and discharging time shown in FIG. 2A when the chopper 14 is normal. That is, the light entrance window of the infrared sensor 10 is opened and closed by the chopper 14 at a duty ratio of about 50%. When the chopper 14 is deformed for some reason, the duty ratio is greatly deviated from 50%. The phase detector 23 detects the phase of the infrared sensor 11, and the chopper abnormality detector 24 detects an abnormality of the chopper 14 from this phase state. When the abnormality of the chopper 14 is detected, the body temperature measuring means 12 displays on the display means 13 that the chopper 14 is abnormal.
[0032]
(Example 4)
Next, a fourth embodiment of the present invention will be described. FIG. 7 is a block diagram showing the configuration of this embodiment. In this embodiment, the infrared sensor 10 has a shielding part 25 that shields light from entering the light entrance window, and the body temperature measuring means 12 has a noise removing part 26. For example, the shielding portion 25 is made of a black body surface by applying a black paint or the like on the surface of a resin or metal plate. For example, even if a mirror surface or a white surface is used, there is no problem. That is, any device that can prevent light from entering the light entrance window of the infrared sensor 10 may be used.
[0033]
The operation of this embodiment will be described below. Before the body temperature measurement, the shielding unit 25 is disposed in front of the infrared sensor 10, and a test operation is executed. At this time, the output of the infrared sensor 10 should be zero. That is, the shielding unit 25 shields the light entrance window of the infrared sensor 10, and all light should not enter the infrared sensor 10. However, in reality, the infrared sensor 10 outputs a certain amount of signal (hereinafter referred to as noise) due to noise caused by the power supply supplied to the chopper 14 by the chopper driving means 15. The noise removing unit 26 detects and stores a signal due to the noise. Thus, the test operation is finished and the body temperature is measured. At this time, of course, the infrared rays from the eardrum are detected without using the shielding portion 25. The body temperature measuring means 12 performs a body temperature calculation by subtracting the noise amount stored by the noise removing unit 26. The test operation does not need to be performed every time the body temperature is measured, and it is sufficient to perform the test operation periodically at a frequency such as once a month.
[0034]
(Example 5)
Next, a fifth embodiment of the present invention will be described. FIG. 8 is a block diagram showing the configuration of this embodiment. In this embodiment, the chopper power supply means 16 is provided with a chopper activation unit 27 that soft-starts the chopper 14.
[0035]
With the above configuration, the operation of the chopper 9 is stabilized and acts so that stable body temperature measurement can be performed. That is, since the chopper power supply means 16 is provided with the chopper starter 27 for soft-starting the chopper 14, the voltage of the power supplied by the chopper power supply means 16 rises gently.
[0036]
When the voltage of the power source supplied to the chopper 9 suddenly rises, since the material constituting the chopper 9 is a piezoelectric material such as ceramic, the amplitude of vibration at the time of rise becomes very large and the generated high frequency is generated. Due to the influence of the components, the resonance point shifts and the operation does not occur at the set frequency. Therefore, in this embodiment, in order to avoid such a situation, the chopper power source means 16 is provided with a chopper activation unit 27 so that the chopper 9 can operate stably from the start.
[0037]
(Example 6)
Next, a sixth embodiment of the present invention will be described. FIG. 9 is a block diagram showing the configuration of this embodiment. In this embodiment, the chopper driving means 15 is provided with a drive signal generator 27.
[0038]
With the above configuration, the chopper driving means 15 drives the chopper 14 to vibrate in accordance with a signal generated by the drive signal generator 27. The drive signal generator 27 uses a sine wave waveform or a cosine wave waveform as the drive signal for the chopper 14. For this reason, the fault at the time of setting it as the drive by the conventional rectangular wave can be removed. That is, in the case of driving by a rectangular wave, the chopper 14 resonates due to a high-frequency component generated at the rise or fall of the harmonic. For this reason, while the chopper is operating, a resonance sound at this harmonic is generated. In this respect, according to the present embodiment, since the drive signal generator 27 uses the sine wave waveform or the cosine wave waveform as the drive signal of the chopper 14, there is no generation of harmonics, and therefore the operation sound of the chopper can be reduced.
[0039]
In this embodiment, the drive signal of the chopper 14 is a sine wave waveform or a cosine wave waveform. However, the present invention is not particularly limited to this, and the same effect can be obtained even when the rectangular wave corner is blunted. is there.
[0040]
【The invention's effect】
As described above, according to the first aspect of the present invention, a radiation thermometer capable of highly accurate body temperature measurement with reduced influence of room temperature is realized.
[0041]
According to the second aspect of the present invention, a radiation thermometer capable of notifying the user of an abnormality is realized.
[0042]
According to the invention described in claim 3, a radiation thermometer that recognizes an abnormality of the chopper and notifies the abnormality to the display means is realized.
[0043]
According to the invention described in claim 4, a radiation thermometer capable of measuring an accurate body temperature by grasping the influence of noise and removing the noise is realized.
[0044]
According to the invention described in claim 5, a radiation thermometer capable of performing stable body temperature measurement is realized.
[0045]
According to the sixth aspect of the present invention, a radiation thermometer having a low chopper operating sound is realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a radiation thermometer as a first reference example of the present invention. FIG. 2A is a waveform diagram showing an output signal of an infrared sensor. FIG. FIG. 3 is a block diagram showing a configuration of a radiation thermometer as a second reference example of the present invention. FIG. 4 is a block diagram of the radiation thermometer according to the first embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a radiation thermometer according to a second embodiment of the present invention. FIG. 6 is a block diagram showing a configuration of a radiation thermometer according to a third embodiment of the present invention. FIG. 7 is a block diagram showing a configuration of a radiation thermometer according to a fourth embodiment of the present invention. FIG. 8 is a block diagram showing a configuration of a radiation thermometer according to the fifth embodiment of the present invention. FIG. 10 is a block diagram showing the configuration of a radiation thermometer according to the sixth embodiment. Example block diagram showing a radiation clinical thermometer configurations are EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 10 Infrared sensor 11 Sensor temperature detection means 12 Body temperature measurement means 13 Display means 14 Chopper 15 Chopper drive means 16 Chopper power supply means 17 Amplification means 18 Amplification rate variable means 19 AD conversion means 20 Voltage switching means 22 Sensor temperature abnormality detection part 23 Phase detection Unit 24 chopper abnormality detecting unit 25 shielding unit 26 noise removing unit 27 chopper starting unit 28 drive signal generating unit

Claims (6)

Infrared sensor for detecting infrared rays radiated from the human body, sensor temperature detection means for detecting the self-temperature of the infrared sensor, AD conversion means for AD converting the signal of the infrared sensor, and a signal from the sensor temperature detection means Voltage switching means for switching the reference voltage of the AD conversion means, body temperature measuring means for measuring the body temperature based on an output signal of the AD conversion means and a signal from the sensor temperature detection means, and a chopper for opening and closing the light incident window of the infrared sensor And a chopper driving means for driving the chopper, and a chopper power supply means for driving the chopper driving means only during body temperature measurement. 2. The radiation thermometer according to claim 1, wherein the body temperature measuring unit includes an abnormality detection unit that detects an abnormality of disconnection of the sensor temperature detection unit. The radiation thermometer according to claim 1 or 2, wherein the body temperature measuring means includes a chopper abnormality detecting means for detecting an abnormality in the amplitude displacement of the chopper. The radiation thermometer according to any one of claims 1 to 3, wherein the infrared sensor has a shielding part that shields light from entering the light entrance window, and the body temperature measuring means has a noise removing part. The radiation thermometer according to any one of claims 1 to 4, wherein the chopper power supply means includes a chopper activation unit that soft-starts the chopper. The radiation thermometer according to any one of claims 1 to 5, wherein the chopper driving means has a chopper driving signal having a sine wave waveform or a cosine wave waveform.

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