JPH10300585A - Radiation temperature measuring equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the observed value of the output amplitude from a pyroelectric infrared detection element from fluctuating depending on the falling of a synchronization signal and the falling timing just like a case employing a synchronism detection circuit. SOLUTION: A frequency component calculating means 15 calculates the Fourier coefficients of two signal components having a frequency equal to the switching frequency of infrared rays and a phase difference of π/2 from a data sequence obtained by sampling the output signal from a pyroelectric infrared detection element and determines the square sum thereof thus removing the effect of rising/falling timing of a synchronization signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the temperature of an object in a non-contact manner using infrared rays.
In particular, the present invention relates to a device that detects infrared rays using a pyroelectric infrared detection element.

[0002]

2. Description of the Related Art As one of so-called radiation thermometers for detecting infrared rays emitted from an object and measuring the temperature of the object without contact, there is a radiation thermometer using a pyroelectric infrared detecting element.

The pyroelectric infrared detecting element is made of an insulator having ferroelectricity, and when the amount of infrared light incident on the insulator changes, the temperature of the insulator changes, and the spontaneous polarization is accordingly caused. Change. The pyroelectric infrared detecting element outputs a change in the amount of incident infrared light as a voltage value of the surface charge generated by the spontaneous polarization.

Using such a pyroelectric infrared detecting element,
In order to measure the temperature of an object whose temperature is stable and constantly emits a certain amount of infrared light, the infrared light emitted by the object whose temperature is to be measured is constantly incident on the pyroelectric infrared detector. Instead, it is necessary to forcibly change the incident infrared light. For this reason, infrared rays emitted from an object as a temperature measurement target and infrared rays emitted from an object as a reference temperature are alternately switched to be incident on a pyroelectric infrared detection element. A method involving mechanical operation, such as rotating an impeller with a stepping motor, is usually used for switching infrared rays.
The temperature of the object as the reference temperature is used as a temperature compensation signal when calculating the temperature of the object to be subjected to temperature measurement from the output signal of the pyroelectric infrared detection element.

The general operation of a conventional radiation thermometer using such a pyroelectric infrared detecting element will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 20 is a block diagram showing a configuration example of a conventional radiation thermometer. In the figure, reference numeral 1 denotes an object to be subjected to temperature measurement, 2 denotes an object having a reference temperature, 3 denotes infrared switching means for alternately switching infrared light emitted by the object 1 and infrared light emitted by the object 2, and 4 denotes pyroelectric infrared light. Infrared detecting means comprising a detecting element, 5 is an amplifying circuit, 6 is a synchronous detecting circuit, 7 is a low-pass filter, and 8 is a reference temperature measuring means for measuring the temperature of an object as a reference temperature. The reference temperature measuring means 8
It consists of a temperature-sensitive element such as a thermistor. Reference numeral 9 denotes temperature calculating means for calculating the temperature of the object 1 based on the output of the low-pass filter 7 and the temperature measured by the reference temperature measuring means 8, and 10 denotes temperature displaying means for displaying the calculated temperature.

FIG. 21 is a characteristic diagram showing timings at which the infrared switching means 3 switches infrared rays and signal waveforms of the amplifier circuit 5 and the synchronous detection circuit 6.

In FIG. 20, the infrared switching means 3 alternately switches between the infrared light emitted by the object 1 and the infrared light emitted by the object 2 and causes the infrared light to be incident on the infrared detecting means 4. The frequency at which the infrared light is switched is usually set to several hertz to several tens of hertz. The timing at which the infrared ray incident on the infrared ray detecting means 4 is actually switched is delayed by a mechanical response time from a drive signal for starting a mechanical operation by a stepping motor or the like for switching the infrared ray as shown in FIG.

Returning to FIG. 20, the infrared detecting means 4 outputs an AC signal corresponding to a change in the amount of incident infrared light to the amplifier circuit 5. This AC signal is a repetitive signal having a cycle equal to the cycle at which the infrared switching means 3 switches infrared rays.

The amplifying circuit 5 amplifies the voltage of the AC signal and outputs it to the synchronous detection circuit 6. When the temperature of the object 1 is higher than the temperature of the object 2, the AC signal output from the amplifier circuit 5 rises when infrared light from the object 1 enters the infrared detection means 4 as shown in FIG. When the infrared rays of the fall, fall. On the other hand, when the temperature of the object 1 is lower than the temperature of the object 2, when the infrared ray from the object 1
Rises when infrared light from the camera enters. Note that FIG.
Although the illustration is omitted, the rising and falling timings of this signal are strictly slightly delayed from the timing at which the infrared light is switched by the response speed of the infrared detection means 4. Further, depending on the configuration of the amplifier circuit 5, a delay based on electrical characteristics such as the phase characteristic of the amplifier circuit 5 may be further added.

Returning to FIG. 20, the synchronous detection circuit 6 creates a signal called a synchronous signal. As the synchronization signal, a square wave having the same frequency as the fundamental frequency of the output signal of the infrared detecting means 4, that is, the same frequency as that at which the infrared switching means 3 switches the infrared light is used. In principle, the rising and falling timings of the synchronizing signal are determined by increasing the signal value of the synchronizing signal by +1 when the signal value of the AC signal obtained as the output of the amplifier circuit 5 becomes larger than 0 volt as shown in FIG. Bolts,
When the signal value becomes smaller than 0 volt, the signal value of the synchronization signal may be determined to be -1 volt. Actually, since the output signal of the amplifier circuit 5 includes element noise of the infrared detector 4 and circuit noise of the amplifier circuit 5, the influence of such noise is eliminated and the rise and fall of the synchronization signal are eliminated. Several methods are used to determine the timing, such as using a driving signal of the infrared switching means 3, which will be described later in detail. The synchronous detection circuit 6 creates a signal represented by the product of the voltage value of the synchronous signal and the voltage value of the output signal of the amplifier circuit 5 and outputs the signal to the low-pass filter 7.

The low-pass filter 7 removes an AC component from the output signal of the synchronous detection circuit 6 and outputs a DC component.
The magnitude of the DC component output from the low-pass filter 7 is proportional to the temperature difference between the object 1 and the object 2.

The reference temperature measuring means 8 measures the temperature of the object 2 and outputs the measurement result to the temperature calculating means 9.

The temperature calculating means 9 calculates the temperature of the object 1 using the output of the low-pass filter 7 and the temperature of the object 2 measured by the reference temperature measuring means 8, and outputs the calculation result to the temperature display means 10. .

The temperature display means 10 displays the calculated temperature. The conventional radiation thermometer operates as described above. Among them, the synchronous detection circuit 6 is required to detect the output signal of the infrared detection means 4 amplified by the amplifier circuit 5 very precisely. You. For this purpose, it is necessary to correctly determine the rising and falling timings of the synchronizing signal, and if the timings are shifted, the detection result will be greatly disordered.

Typical methods for determining this timing include a method using a predetermined timing delayed by a predetermined amount with respect to a drive signal of the infrared switching means 3,
There is a method of automatically determining based on the output signal of the amplifier circuit 5 using the technique of the case locked loop (for example, see Japanese Patent Application Laid-Open No. 60-6835). Further, Japanese Patent Application Laid-Open No. 60-6835 proposes a method in which the timing once determined automatically is stored in a memory, and thereafter, the timing is determined based on information read from the memory.

In addition, a method of directly converting the functions of the synchronous detection circuit 6 and the low-pass filter 7 into software using a microcomputer or the like can be considered. this is,
This can be achieved as follows. That is, the output signal of the amplifier circuit 5 is sampled and converted from analog to digital for an integer period and stored in the memory. In this case, a constant offset voltage is added to the output voltage of the amplifier circuit 5 for the sake of analog / digital conversion so that the signal value is always 0 volt or more. After all samplings are completed, the average value of the data group stored in the memory is calculated, and the sum of the absolute values of the differences between the individual values and the average value of the data group stored in the memory is calculated. The value obtained by dividing the sum by the total number of times of sampling may be regarded as the value of the DC voltage output from the low-pass filter 7.

[0018]

However, the timing of rising and falling of the synchronization signal is determined,
These techniques for converting the functions of the synchronous detection circuit 6 and the low-pass filter 7 into software as they are have respective problems.

The method using predetermined timings as the rising and falling timings of the synchronizing signal is based on the response speed of a mechanically operating component used by the infrared switching means 3 for switching infrared rays, the infrared detecting means 4
If the response speed of the pyroelectric infrared detecting element used in the above or the phase characteristics of the amplifier circuit 5 varies, there is a problem that the predetermined timing deviates from the original timing.

On the other hand, the rising and falling timings of the synchronizing signal are determined by the Phase Locked Loop.
When the method of automatically determining using the technique of the above is adopted, the timing can be accurately determined, but since it takes some time after the start of the temperature measurement to determine the timing, the time required for the temperature measurement is required. Another problem is that the length of the data becomes longer.

The technique proposed in Japanese Patent Application Laid-Open No. Sho 60-6835 for storing the automatically determined timing in a memory has the possibility of solving both of these two problems. In the case where the response speed of the component that performs the detection, the response speed of the pyroelectric infrared detection element, or the phase characteristic of the amplifier circuit 5 has an aging change or a temperature dependency on the ambient temperature, it is determined based on the information read from the memory. It cannot be guaranteed that the timing always coincides with the expected timing.

Further, when the functions of the synchronous detection circuit 6 and the low-pass filter 7 are converted into software as they are, there remains a problem of how to make the timing to start sampling constant. This will be described with reference to FIG. FIG. 22 is a characteristic diagram showing sampling timing when the output signal of the amplifier circuit 5 is sampled at a timing obtained by dividing one cycle of the output signal into four equal parts. Even when the same output waveform is sampled by dividing one cycle into four equal parts, as shown in FIG. 22A, the output signal of the amplifier circuit 5 is sampled so as to include the moment when the difference from the average value is the largest. Sampling is performed when the timing for starting the sampling is taken and when the timing for starting the sampling is set so as to include the moment when the output signal of the amplifier circuit 5 coincides with the average value as shown in FIG. A difference occurs in the value corresponding to the detection result calculated from the data sequence, and the value in the former case is obviously larger. Thus, the synchronous detection circuit 6 and the low-pass filter 7
If you want to realize this function as software,
The problem of how to determine the rising and falling timings of the synchronizing signal remains as the problem of how to determine the timing to start sampling.

When the functions of the synchronous detection circuit 6 and the low-pass filter 7 are converted into software as they are, all the sampling values converted into digital signals are temporarily stored in the memory, so that the storage capacity is large in proportion to the number of samplings. There is also a problem that the memory is required.

[0024]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and the output of the infrared detecting means 4 can be determined without determining the rising and falling timings of the synchronizing signal and the timing of starting the sampling. It is intended to realize a radiation thermometer that can accurately measure the magnitude of a signal.The infrared detection means outputs a signal corresponding to the change in the amount of incident infrared light, and the radiation emitted from an object to be measured. An infrared switching means for alternately switching the infrared light emitted from the object having the reference temperature and the infrared light emitted from the object having the reference temperature to enter the infrared detection means, a sampling means for sampling an output signal of the infrared detection means, and a signal output by the infrared detection means Of the signal components of various frequencies included in the The size of the stomach signal components, based on the data string sampling means sampled, in which the sampling means has a frequency component calculating means for calculating with the algorithm that can remove the influence of the timing for starting the sampling.

According to the above invention, the sampling means starts sampling at an arbitrary timing, and the frequency component calculating means determines the frequency of the signal components of various frequencies included in the output signal of the infrared detecting means by the infrared switching means. The magnitude of the signal component equal to the infrared switching frequency is
Based on the data sequence sampled by the sampling means, the calculation is performed using an algorithm capable of removing the influence of the sampling start timing, so that there is no need to create a synchronization signal as in the conventional technology using the synchronous detection technology. . Therefore, it is not necessary to worry about the difference between the rising and falling timings of the synchronization signal, and it is not necessary to take extra time to accurately determine the timing. Further, there is no problem of how to determine the timing to start sampling as in the case where the synchronous detection circuit and the low-pass filter are directly converted into software.

[0026]

DETAILED DESCRIPTION OF THE INVENTION The present invention converts an infrared ray obtained by alternately switching infrared rays emitted from an object to be subjected to temperature measurement and infrared rays emitted from an object to be a reference temperature into an electric signal, Of the signal components of various frequencies included in the signal, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared is removed based on a data sequence obtained by sampling the electric signal, and the influence of the sampling start timing is removed. This is a radiation temperature measurement device that calculates the temperature of an object as a temperature measurement target based on the calculation result using the obtained algorithm and the temperature of the object as a reference temperature.

Then, among the signal components of various frequencies included in the electric signal, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray is calculated by using an algorithm capable of eliminating the influence of the sampling start timing. Therefore, there is no need to create a synchronization signal as in the conventional technique using the synchronous detection technique. Therefore, it is not necessary to worry about the difference between the rising and falling timings of the synchronizing signal, and it is not necessary to take extra time to accurately determine these timings. Further, there is no problem of how to determine the timing to start sampling as in the case where the synchronous detection circuit and the low-pass filter are directly converted into software.

Also, an infrared detecting means for outputting a signal corresponding to a change in the amount of incident infrared light, and an infrared light emitted from an object as a temperature measuring object and an infrared light emitted from an object as a reference temperature are alternately switched. An infrared switching means for inputting the infrared light to the infrared detecting means, a sampling means for sampling an output signal of the infrared detecting means, and a frequency of the signal components of various frequencies included in the signal output by the infrared detecting means, Frequency component calculating means for calculating the magnitude of a signal component equal to the switching frequency of the infrared ray based on a data sequence sampled by the sampling means using an algorithm capable of removing the influence of the timing at which the sampling means starts sampling; Reference temperature measuring means for measuring the temperature of an object to be a temperature, and a frequency component Detection means in which is a temperature calculating means for calculating the temperature of the object to the temperature measured from the calculated value and the reference temperature at which the temperature measuring means has measured.

Then, the sampling means starts sampling at an arbitrary timing, and the frequency component calculating means
Starting the sampling of the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means among the signal components of various frequencies included in the output signal of the infrared ray detection means, based on the data sequence sampled by the sampling means. Since the calculation is performed using an algorithm that can remove the influence of timing, there is no need to create a synchronization signal as in the conventional technique using the technique of synchronous detection. Therefore, it is not necessary to worry about the difference between the rising and falling timings of the synchronization signal, and it is not necessary to take extra time to accurately determine the timing. Further, there is no problem of how to determine the timing to start sampling as in the case where the synchronous detection circuit and the low-pass filter are directly converted into software.

Further, the frequency component calculating means removes harmonic components of the infrared switching frequency by the infrared switching means and calculates the magnitude of a signal component having a frequency equal to the infrared switching frequency by the infrared switching means. It was done.

The drive signal that causes the infrared detecting means to start a mechanical operation by a stepping motor or the like for switching the infrared rays is usually a second harmonic of the infrared switching frequency by the infrared switching means and a higher harmonic. Since it is composed of even harmonics, by removing the influence of electrical noise accompanying the harmonics, it is possible to more accurately calculate the magnitude of the signal component having the same frequency as the infrared switching frequency by the infrared switching means. It becomes possible.

Further, the frequency component calculating means determines that two of the signal components of various frequencies included in the signal output from the infrared detecting means have the same frequency as the infrared switching frequency by the infrared switching means and a phase different by π / 2. It is provided with a Fourier coefficient calculating means for calculating a Fourier coefficient of the signal component.

The values of the two calculated Fourier coefficients are two of the magnitude of the signal component having a frequency equal to the switching frequency of the infrared ray by the infrared ray switching means and the phase of the signal component determined at the timing of starting the sampling. Can be represented by a mathematical formula with two unknowns, so using the calculated values of the two Fourier coefficients, in the manner of solving a system of binary equations, the signal component of the frequency equal to the infrared switching frequency by the infrared switching means The size can be calculated.

Further, the frequency component calculating means removes the influence of the sampling start timing by using the sum of the squares of the two Fourier coefficients.

Then, by calculating the sum of the squares of the two Fourier coefficients, the magnitude of the signal component having the frequency equal to the switching frequency of the infrared ray by the infrared switching means and the phase of the signal component determined at the timing of starting the sampling are calculated. Of the two unknowns, the influence of the phase can be removed, and the size of the remaining one unknown can be accurately calculated.

Further, the frequency component calculating means removes the influence of the sampling start timing by using the ratio of the two Fourier coefficients.

Then, by calculating the ratio of the two Fourier coefficients, the magnitude of the signal component having the frequency equal to the switching frequency of the infrared ray by the infrared switching means and the phase of the signal component determined at the sampling start timing are obtained. Of unknowns, the influence of the magnitude can be removed, and the phase can be calculated accurately. Thereafter, by using the phase thus calculated and at least one of the two Fourier coefficients, it is possible to calculate the size of the remaining unknown.

Further, the frequency component calculating means calculates an amplitude of a signal component having a frequency equal to the switching frequency of the infrared ray by the infrared switching means among the signal components of various frequencies included in the signal output from the infrared detecting means. It is configured to include a calculating means.

Since the magnitude of the amplitude calculated by the amplitude calculating means is a value proportional to the square root of the sum of the squares of the two Fourier coefficients, the amplitude calculating means calculates the amplitude by using the infrared switching means. It is possible to calculate the magnitude of the signal component having a frequency equal to the switching frequency of the infrared ray by removing the influence of the phase determined by the sampling start timing.

The frequency component calculating means calculates the energy of the signal component having a frequency equal to the infrared switching frequency of the infrared switching means among the signal components of various frequencies included in the signal output from the infrared detecting means. It is configured to include energy calculating means.

Since the magnitude of the energy calculated by the energy calculating means is a value proportional to the sum of the squares of the two Fourier coefficients, the energy calculating means calculates the energy by the infrared switching means. It is possible to calculate the magnitude of the signal component having a frequency equal to the switching frequency of the above by removing the influence of the phase determined by the timing of starting the sampling.

The frequency component calculating means calculates the number of data sampled by the sampling means, and calculates a product of a constant determined according to the count value of the counting means and the data sampled by the sampling means. The configuration includes a multiplying unit and a cumulative value storing unit that stores a cumulative value of the value calculated by the multiplying unit.

Since the accumulated value stored in the accumulated value storage means is a value proportional to the Fourier coefficient, the Fourier coefficient can be calculated by dividing the accumulated value by a predetermined constant.

Further, the frequency component calculating means has a sampling value storing means for storing each data sampled by the sampling means, and after storing all the sampling data, using the data stored in the sampling value storing means. In addition, of the signal components of various frequencies included in the signal output by the infrared detecting means, the magnitude of the signal component whose frequency is equal to the infrared switching frequency by the infrared switching means is calculated.

During the period when the sampling value storage means stores the sampling data, only the processing of storing the sampling value, which can be executed in a relatively short time, is performed.
The processing involving more time-consuming multiplication and division is performed using the data stored in the sampling value storage means after the storage of all the sampling data is completed. Therefore, values such as Fourier coefficients, amplitude, and energy are calculated. Even if the sampling period is so short that the multiplication and division operations required for
Among the signal components of various frequencies included in the signal output by the infrared detection means, the magnitude of the signal component whose frequency is equal to the infrared switching frequency by the infrared switching means can be calculated.

Further, the frequency component calculating means may be provided with a sampling value accumulating means for storing a plurality of values obtained by accumulatively adding the data sequence sampled by the sampling means in synchronism with a cycle at which the infrared switching means switches the infrared rays. I have.

Then, instead of the sampling value storage means storing the individual sampling data individually, the sampling value accumulation storage means stores the accumulation value of the sampling value and uses the accumulation value to reduce the storage capacity. Even if the sampling period is so short that the multiplication and division operations required to calculate the values of Fourier coefficients, amplitude, energy, etc. cannot be completed within one sampling period, the infrared detection means outputs Among the signal components of various frequencies included in the obtained signal, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means can be calculated.

Further, the frequency component calculating means accumulates the data sequence sampled by the sampling means by inverting positive and negative alternately in each half cycle in synchronism with the half cycle of the cycle in which the infrared switching means switches the infrared rays. Is provided with a sampling value accumulation storage means for storing a plurality of sampled values.

Then, the sampling value accumulation storage means
By accumulating the sampled data sequence by inverting the sign alternately, only half the storage capacity is required compared to the case of simply accumulating without inverting the sign,
Even if the sampling period is so short that the multiplication and division operations required to calculate the values of Fourier coefficients, amplitude, energy, etc. cannot be completed within one sampling period, they are included in the signal output by the infrared detecting means. Among the signal components of various frequencies, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means can be calculated.

The sampling means is configured to perform sampling at a frequency which is an integral multiple of the frequency at which the infrared switching means switches infrared rays.

Since the sampling frequency of the sampling means can be assured to be exactly an integral multiple of the frequency at which the infrared switching means switches infrared rays, the frequency component calculating means allows the frequency component calculating means to output various signals included in the signal output by the infrared detecting means. It is possible to accurately calculate the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means among the signal components of the various frequencies.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing a configuration of an embodiment of a radiation temperature measuring apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes an object whose temperature is to be measured, 2 denotes an object having a reference temperature, 3 denotes an infrared switching means for alternately switching between the infrared light emitted by the object 1 and the infrared light emitted by the object 2, Infrared detecting means comprising a pyroelectric infrared detecting element, 5 is an amplifier circuit, 8 is an object 2 having a reference temperature.
Is a reference temperature measuring means for measuring the temperature by a thermistor, 11 is a first timing instructing means, and 12 is a second timing instructing means. Second timing instruction means 1
2 has a frequency dividing means 12a inside. Also, 13
Is a filter circuit configured using an operational amplifier that attenuates a signal having a predetermined frequency or more to a negligible level, 14 is a sampling unit that samples an analog signal, and 15 is included in a signal output from the filter circuit 13. Frequency component calculating means for calculating the magnitude of a cosine wave component whose frequency is equal to the infrared switching frequency of the infrared switching means 3 among signal components of various frequencies, 16 is a temperature calculating means for calculating the temperature of the object 1, 10 Is a temperature display means for displaying the calculated temperature. The radiation temperature measuring device shown in FIG. 1 is based on the premise that the temperature of the object 1 to be measured is higher than the temperature of the object 2 as the reference temperature.
Measure the temperature of.

FIG. 2 is a block diagram showing a configuration example of the infrared ray switching means 3. In FIG. 2, 3a is a drive circuit, 3b is a stepping motor, and 3c is an impeller.
The impeller 3c has four blades. Each time the impeller 3c rotates by 45 degrees, the infrared light emitted by the object 1 to be subjected to temperature measurement is transmitted as it is and made incident on the infrared detecting means 4, or the object 1 It is possible to alternately switch between blocking the emitted infrared rays and, instead, totally reflecting the infrared rays emitted by the object 2 and making the infrared rays incident on the infrared detection means 4.

Hereinafter, the operation of the radiation temperature measuring device will be described in detail. The first timing instructing means 11 generates a signal for instructing the sampling means 14 to perform sampling at a constant frequency pulse. This pulse may be generated by dividing the output of a crystal oscillator or a ceramic oscillator, or by using an oscillator using an operational amplifier.
Hereinafter, a case where the frequency of this pulse is 160 Hz will be described as an example.

The frequency dividing means 12a in the second timing instruction means 12 generates a pulse having a frequency obtained by dividing the pulse generated by the first timing instruction means 11 at a constant frequency dividing ratio. Hereinafter, a case where the frequency division ratio is 8 will be described as an example. Therefore, the frequency of the pulse generated by the frequency dividing means 12a is 20 Hz, and the period is 50 milliseconds.

The second timing instructing means 12 supplies the pulse generated by the frequency dividing means 12a to the infrared ray switching means 3 as it is as a signal for instructing the timing of switching the infrared rays.

When a pulse is supplied from the second timing instructing means 12, the driving circuit 3a in the infrared switching means 3 drives the stepping motor 3b to rotate it by a rotation angle of 45 degrees. Therefore, the stepping motor 3b
Rotate 45 degrees every 0 ms. If the width of the pulse supplied from the second timing instruction means 12 is too wide to accurately determine the timing for driving the stepping motor 3b, the moment the pulse rises from a low level to a high level, or The stepping motor 3b may be driven at the moment when the pulse falls from the high level to the low level.

The impeller 3c rotates together with the stepping motor 3b, and every time the stepping motor 3b rotates 45 degrees, the infrared rays emitted from the object 1 to be subjected to the temperature measurement are transmitted as they are and incident on the infrared detecting means 4. ,
Whether the infrared rays emitted by the object 1 are blocked and the infrared rays emitted by the object 2 are totally reflected and made incident on the infrared detecting means 4 is alternately switched. Therefore, the infrared light incident on the infrared detecting means 4 via the infrared switching means 3 is such that the infrared light emitted from the object 1 and the infrared light emitted from the object 2 are alternately switched every 50 milliseconds, and It changes periodically every time. That is, the infrared switching means 3 switches infrared rays at a frequency of 10 Hz.

The infrared detecting means 4 outputs a signal corresponding to a change in the amount of incident infrared light. Since the infrared light incident on the infrared detecting means 4 changes periodically every 100 milliseconds, the signal output from the infrared detecting means 4 is also a periodic signal having a period of 100 milliseconds.

The amplifying circuit 5 amplifies the output signal of the infrared detecting means 4 by AC, and further adds a constant DC signal to the amplified AC signal, so that the voltage value always changes in a range of 0 volt or more. Output as an AC signal.

The filter circuit 13 does not attenuate the signal components having a frequency of 10 Hertz or less in the AC signal, and attenuates the signal components having a frequency higher than 80 Hertz to a negligible magnitude.

When a pulse is supplied from the first timing instruction means 11, the sampling means 14 samples the output voltage of the filter circuit 13 and supplies the obtained sampling value to the frequency component calculation means 15. The sampling frequency of the sampling means 14 is 160 Hz, while the output signal of the filter circuit 13 is a periodic signal having a period of 100 milliseconds.
Means that sampling is performed at equal time intervals at a rate of 16 times in one cycle of the output signal of the filter circuit 13.
If the width of the pulse supplied from the first timing instruction means 11 is too wide to accurately determine the timing of sampling, the moment the pulse rises from a low level to a high level, or the pulse changes from a high level to a low level. Sampling may be performed at the moment when the level falls to the level.

In the above description, the case where the frequency of the pulse generated by the first timing instructing means 11 is 160 Hz and the frequency dividing ratio of the frequency dividing means 12a is 8 has been described as a specific example. Generally, when the frequency of the pulse generated by the first timing instruction means 11 is F Hertz and a value twice the frequency division ratio of the frequency dividing means 12a is represented by a natural number N, the frequency at which the infrared switching means 3 switches infrared rays is F
/ N hertz. At this time, the filter circuit 13 is designed so as not to attenuate signal components having a frequency of F / N hertz or less, and to attenuate signal components having a frequency higher than F / 2 hertz to a negligible magnitude. The filter circuit 13
Is a periodic signal having a period of N / F seconds. Further, the sampling means 14 performs sampling at an equal time interval at a rate of N times in one cycle of the output signal of the filter circuit 13. In the following, the description of the operating frequency of each unit and the frequency of the signal component will be made using this frequency F and natural number N unless otherwise required. The frequency component calculating means 15 uses M × N sampling values supplied from the sampling means 14 for a predetermined natural number M in a period M times the cycle of switching the infrared light by the infrared light switching means 3, The amplitude Vs of the cosine wave component of the frequency F / N hertz included in the signal indicated by the sampling value sequence is calculated. How the frequency component calculating means 15 calculates the amplitude Vs will be described later in detail. The value of the natural number M is the frequency at which the infrared switching means 3 switches infrared light,
Determined from the time used for temperature measurement. For example, if the frequency at which the infrared switching means 3 switches infrared light is 10 Hz and the time used for temperature measurement is 1 second, then M =
It may be set to 10. The larger the value of M × N, the more
The ratio of the magnitude of Gaussian noise such as thermal noise to the signal component in the output signal of the filter circuit 13 can be relatively reduced, but this is not directly related to the object of the present invention, so that Detailed description is omitted.

On the other hand, the reference temperature measuring means 8 measures the absolute temperature of the object 2 as a reference temperature by a thermistor, and supplies the measurement result to the temperature calculating means 16 as a digital value T0.

The temperature calculating means 16 calculates the absolute temperature T of the object 1 using the amplitude Vs calculated by the frequency component calculating means 15 and the absolute temperature T0 of the object 2 supplied from the reference temperature measuring means 8, The calculation result is supplied to the temperature display means 10. The calculation of the absolute temperature T of the object 1 is performed between Vs, T, and T0.

[0067]

(Equation 1)

Using the fact that there is a relationship,

[0069]

(Equation 2)

Is calculated. Note that the proportionality constant K is determined from the absolute temperature T1 of the object 1 at that time, the absolute temperature T2 of the object 2, and the amplitude Vsk calculated by the frequency component calculating unit 15, assuming that the object whose temperature is known is the object 1.

[0071]

(Equation 3)

May be determined in advance and stored in a non-volatile memory or the like. The temperature display means 10 displays the absolute temperature T calculated by the temperature calculation means 16.

Next, the operation of the frequency component calculating means 15 will be described.
This will be described in detail with reference to FIGS.

FIG. 3 is a block diagram showing an example of the configuration of the frequency component calculating means 15. In the figure, 15a is a counting means for counting the number of sampling values supplied from the sampling means 14, 15b is A / D conversion means for converting an analog signal into a digital signal, and 15c is a constant value sequence determined as a value of a cosine function. Cosine value generating means for generating, 15d is a sine value generating means for generating a constant value sequence determined as a value of a sine function, 15e and 15f are multiplying means for performing a multiplication operation,
15g and 15h are cumulative value storage means, 15j is Fourier coefficient calculation means, and 15k is amplitude calculation means.

FIG. 4 is a flowchart showing the operation of the frequency component calculating means 15. In FIG. 4, the reference numerals of the components that perform each operation are shown in parentheses.

Hereinafter, the operation of the frequency component calculating means 15 will be described with reference to FIG. First, the counting means 15a initializes a count value n for counting the number of sampling values supplied from the sampling means 14 to zero. Further, the accumulated value storage unit 15g initializes the accumulated value ΔVcos to 0.
Similarly, the cumulative value storage unit 15h initializes the cumulative value ΣVsin to 0.

After that, the frequency component calculation means 15 waits for the sampling value to be supplied from the sampling means 14.

When an analog signal is supplied from the sampling means 14, the A / D conversion means 15b converts the sampled value into a digital signal, and supplies the conversion result to the multiplication means 15e and the multiplication means 15f. . Hereinafter, for convenience of description, the sampling value converted into the digital signal is described as V (n) as a value corresponding to the count value n of the counting means 15a.

When the sampling value is supplied from the sampling means 14, the cosine value generating means 15c generates a value cos_value determined as cos (n × 2π / N) with respect to the count value n of the counting means 15a, and multiplies it. Means 1
5e.

When the sampling value is supplied from the sampling means 14, the sine value generating means 15d generates a value sin_value determined as sin (n × 2π / N) with respect to the count value n of the counting means 15a, and multiplies it. Means 1
5f.

The cosine value generating means 15c and the sine value generating means 15d may calculate the value to be generated by a numerical operation when the value is needed, or may calculate the value calculated in advance in a non-volatile manner. Alternatively, the information may be recorded in a non-volatile memory and read from the nonvolatile memory. However, when it is necessary to increase the operating speed of the cosine value generating means 15c and the sine value generating means 15d, it is preferable to use a method of reading from the non-volatile memory.

The multiplication means 15e is provided with an A / D conversion means 15b.
And the value cos_value supplied from the cosine value generating means 15c is calculated, and the calculation result Vcos is supplied to the accumulated value storing means 15g.

The multiplying means 15f includes an A / D converting means 15b
Is calculated by multiplying the value V (n) supplied from the control unit 15 and the value sin_value supplied from the sine value generation unit 15d, and supplies the calculation result Vsin to the accumulated value storage unit 15h.

The accumulation value storage means 15g is provided with a multiplication means 15e.
Is added to the accumulated value ΣVcos and stored as a new accumulated value ΣVcos.

The accumulation value storage means 15h is provided with a multiplication means 15f
Is added to the cumulative value ΣVsin and stored as a new cumulative value ΣVsin.

Next, the counting means 15a increases the count value n by one. Thereafter, the frequency component calculation means 15 compares the count value n with M × N. As a result of the comparison, the count value n is M
If it is not equal to × N, after waiting for a new sampling value to be supplied from the sampling means 14, A / A
A series of processes from the process of converting the sampling value into a digital signal by the D conversion means 15b to the comparison of the count value n with M × N is repeated. When the count value n is equal to M × N, the repetition ends, and the processing by the Fourier coefficient calculation unit 15j starts. When the count value n becomes equal to M × N, the cumulative value ΣVcos and the cumulative value ΣVsi
The value of n will be described later in detail.

The Fourier coefficient calculating means 15j calculates the count value n
Is equal to M × N, the cumulative value ΣVcos stored in the cumulative value storage means 15g is doubled and the counting means 15
The value obtained by dividing the count value n of a by the Fourier coefficient f of the cosine wave component
and the accumulated value storage means 1
The value obtained by doubling the accumulated value ΣVsin stored in 5h and dividing by the count value n of the counting means 15a is calculated as a Fourier coefficient fourier_sin of a sine wave component, and supplied to the amplitude calculating means 15k.

The amplitude calculating means 15k calculates the amplitude Vs as

[0089]

(Equation 4)

The temperature calculation means 1 calculates
6 The frequency component calculation means 15 operates as described above.

Next, when the count value n becomes equal to M × N, the accumulated value ΔV stored in the accumulated value storage means 15g is obtained.
The values of the value of the cos and the cumulative value ΣVsin stored in the cumulative value storing means 15h and the amplitude Vs calculated by the amplitude calculating means 15k will be described.

First, the properties of the trigonometric functions used for calculating these values will be described.

[0093]

(Equation 5)

Next, by using these properties, the values of the accumulated value ΣVcos and the accumulated value ΣVsin when the count value n becomes equal to M × N are obtained.

The output signal of the filter circuit 13 has a period N /
Since it is a periodic signal of F seconds and does not include a signal component having a frequency higher than F / 2 hertz, a fundamental component having a frequency of F / N hertz and harmonic components from the second order to the N / 2 order thereof , And the sum of the DC components. The sampling frequency of the sampling means 14 is F hertz, which is N times the frequency F / N hertz of the fundamental wave.
(N)

[0096]

(Equation 6)

Can be expressed as follows. Where ζ1 and ζ
k is the initial phase of the fundamental wave component and the harmonic component determined by the timing at which sampling is started. In the prior art, when these initial phases ζ1 and 変 化 k change, there is a problem that the influence of the change cannot be removed.

Now, the value of the cumulative value ΣVcos is as follows.

[0099]

(Equation 7)

Similarly, the value of the cumulative value ΣVsin is as follows.

[0101]

(Equation 8)

Accordingly, the value of the Fourier coefficient calculated by the Fourier coefficient calculating means 15j is fourier_cos = a1 × cosζ1 fourier_sin = −a1 × sinζ1 and the value Vs calculated by the amplitude calculating means 15k
Is Vs = 2 × a1. That is, the value Vs calculated by the frequency component calculating means 15 is equal to the peak-to-peak amplitude of the fundamental wave component without being affected by the initial phases ζ1 and ζk or the harmonics at all. I understand.

Here, the output signal of the filter circuit 13 is expressed as a signal obtained by superimposing a DC component with a fundamental component having a frequency of F / N Hertz and its harmonic component represented by a cosine function. Although it has been shown that the value calculated as the amplitude Vs is equal to the amplitude of the cosine wave component of the frequency F / N Hertz, the output signal of the filter circuit 13 is represented by the sine function of the fundamental wave component and its harmonic components. When the component and the DC component are expressed as a superposition, the values of the initial phases ζ1 and ζk only change by π / 2, and the value calculated as the amplitude Vs is the frequency F /
It goes without saying that the amplitude becomes equal to the amplitude of the sine wave component of N hertz.

Further, instead of setting the value cos_value generated by the cosine value generating means 15c to cos (n × 2π / N), cos (n × 2π / N +
ε), and at the same time, the value sin_value generated by the sine value generating means 15d is set to sin (n × 2π /
Even if sin (n × 2π / N + ε) is used instead of N), the value calculated as a Fourier coefficient is fourier_cos = a1 × cos (ζ1−ε) Fourier_sin = −a1 × sin (ζ1−ε) And does not affect the amplitude Vs.

In order to accurately calculate the Fourier coefficient, it is desirable that the natural number N is determined so that N ≧ 8.

According to the present embodiment, the influence of the initial phases ζ1 and ζk determined by the sampling start timing is removed from the amplitude Vs calculated by the amplitude calculating means 15k, so that the mechanical response speed of the stepping motor 3b is reduced. An excellent effect that the temperature of the object 1 to be temperature-measured can be correctly measured without having to adjust the timing at which the sampling means 14 starts sampling in accordance with variations in the response speed of the infrared detecting means 4 or the like. can get.

Further, Phase Locked Lo
Since it is not necessary to determine the timing of the rise and fall of the synchronizing signal as in the case of the op technique, the problem that the time required for temperature measurement becomes long does not occur.

Further, since the sampling values V (n) converted into digital values by the A / D conversion means 15b do not need to be stored individually one by one, the total sampling number M
Even when × N is increased, the amplitude Vs can be calculated without requiring a memory having a large storage capacity.

A signal for instructing the infrared switching means 3 to switch the infrared light is sent to the sampling means 1.
4 is generated by dividing the signal indicating the sampling timing by the frequency dividing means 12a, so that the sampling frequency of the sampling means 14 is exactly an integer multiple of the frequency at which the infrared switching means 3 switches infrared light. Thus, the amplitude Vs can be accurately calculated by the frequency component calculating means 15.

The output signal of the filter circuit 13 sampled by the sampling means 14 is supplied to the driving circuit 3a.
However, there is a possibility that electric noise associated with driving the stepping motor 3b may be mixed in. However, since this electric noise is a repetitive signal having a cycle of N / (F × 2) seconds,
It consists of a cosine wave component of frequency F × 2 / N Hertz and a cosine wave component of its harmonic. Therefore, the electric noise is a collection of the second harmonic of the frequency F / N hertz and the higher harmonics of the higher order even when the infrared switching means 3 switches the infrared light. It can be removed by arithmetic processing.

The present invention is not limited to the above embodiment, but can be implemented with appropriate modifications.

For example, the amplitude calculator 15k may calculate a value proportional to the peak-to-peak amplitude, such as a half value, instead of the peak-to-peak amplitude of the fundamental wave component. This is because the temperature calculation means 16
Is the fourth power of the absolute temperature T of the object 1 and the absolute temperature T0 of the object 2
Since the absolute temperature T of the object 1 is calculated using the fact that the difference of the fourth power is proportional to the amplitude Vs calculated by the frequency component calculating means 15, it is inconvenient even if the amplitude Vs is always calculated as a value multiplied by a constant. Does not occur.

For exactly the same reason, the filter circuit 13 may be designed so that the signal component of the frequency F / N hertz is attenuated at a constant attenuation rate.

Similarly, the Fourier coefficient calculating means 15j calculates
An operation of doubling the accumulated value ΣVcos and the accumulated value ΣVsin and dividing by the count value n of the counting means 15a, that is, doubling the natural number M
The operation of dividing by × N is omitted, and the values of the cumulative value ΣVcos and the cumulative value ΣVsin are directly used as the Fourier coefficients fourier.
_Cos and the value of fourier_sin are supplied to the amplitude calculating means 15k.
Is a proportional constant K used to calculate the absolute temperature T of the object 1.
In addition, the effect of doubling and dividing by a natural number M × N may be incorporated. Alternatively, instead of incorporating the effect of doubling and dividing by a natural number M × N into the proportionality constant K, a value cos_value generated by the cosine value generating means 15c and a value sin_value generated by the sine value generating means 15d are used.
And cos_value = 2 × cos (n × 2π / N) /
(M × N) sin_value = 2 × sin (n × 2π / N) /
(M × N).

In addition, when the highest frequency component included in the output signal of the amplifier circuit 5 is equal to or less than half of the sampling frequency of the sampling means 14 and the so-called Nyquist condition is satisfied, the filter circuit 13 is omitted. It does not matter.

When the output signal of the infrared detecting means 4 is sufficiently large, the amplifier circuit 5 may be omitted.

Further, the temperature display means 10 may convert the absolute temperature T supplied from the temperature calculation means 16 into a temperature in degrees Celsius or a temperature in degrees Fahrenheit and display it.

When the temperature of the impeller 3c itself in the infrared switching means 3 or a temperature at which the temperature difference from the impeller 3c can be ignored is measured by the reference temperature measuring means 8, the impeller 3c is The impeller 3 c itself may be used instead of the object 2 by using a material having a high emissivity. Alternatively, the infrared switching means 3 may be configured by using a piezoelectric diaphragm in place of the stepping motor 3b and the impeller 3c.

In addition, the radiation temperature measuring apparatus shown in FIG. 1 measures the temperature of the object 1 on the assumption that the temperature of the object 1 to be measured is higher than the temperature of the object 2 as the reference temperature. If it is desired to measure the temperature of the object 1 even when the temperature of the object 1 is lower than the temperature of the object 2, for example,
When the temperature of the filter circuit 13 is higher than the temperature of the object 2,
Initial phase of the fundamental component of the cosine wave included in the output signal of
The first sampling is performed by the sampling means 14 at a timing such that 1 becomes equal to or more than -π / 4 and equal to or less than + π / 4, and the amplitude calculating means 15k outputs the Fourier coefficient fo calculated by the Fourier coefficient calculating means 15j.
If the value of urier_cos is 0 or more, the amplitude Vs

[0120]

(Equation 9)

And the Fourier coefficient fouri
If the value of er_cos is less than 0, the amplitude Vs

[0122]

(Equation 10)

It is sufficient to calculate as In this case, the amplitude Vs calculated by the amplitude calculating unit 15k is
When the temperature of the object 1 is higher than the temperature of the object 2, it takes a positive value, and when the temperature of the object 1 is lower than the temperature of the object 2, it takes a negative value. Irrespective of the magnitude relation between the temperature and the temperature of the object 2, the temperature calculating means 16 can correctly calculate the temperature of the object 1. Even if the timing at which the sampling means 14 starts sampling deviates from the assumed timing, the magnitude of the deviation is converted into the phase of the fundamental wave by π / 4.
And the Fourier coefficient fou as long as the initial phase ζ1 is within the range of −π / 2 or more and π / 2 or less.
Since it does not affect the sign of rier_cos at all, it is possible to determine without a mistake which of the object 1 and the object 2 is higher in temperature, and to measure the temperature of the object 1 correctly.

(Embodiment 2) FIG. 5 is a flowchart showing another operation of the amplitude calculating means 15k in Embodiment 2 of the present invention.

Hereinafter, according to FIG. 5, the amplitude calculating means 15k
Will be described. First, the amplitude calculating unit 15k first calculates the two Fourier coefficients fourier_cos and fourier_sin supplied from the Fourier coefficient calculating unit 15j.
Among them, it is determined whether or not the value of fourier_cos is 0.

If the result of the determination indicates that the value of Fourier_cos is 0, a value obtained by doubling the absolute value of Fourier_sin is calculated as the amplitude Vs, and the process is terminated.

If the value of Fourier_cos is not 0, the value of the inverse tangent function to the value obtained by dividing the value obtained by inverting the sign of Fourier_sin by Fourier_cos, that is, the value of the inverse function of the tangent function is calculated as the numerical value α. I do. When this numerical value α is represented by a mathematical formula,

[0128]

[Equation 11]

Is as follows. Next, after calculating the value of the cosine function for this numerical value α as β, fourier_co
The value obtained by doubling the absolute value of the value obtained by dividing s by β is calculated as the amplitude Vs, and the processing is terminated.

Next, it will be described that the amplitude Vs calculated in this way becomes equal to the amplitude Vs calculated by the operation of the amplitude calculating means 15k according to the flowchart of FIG.

As already indicated, the sampling means 1
When the fundamental wave component included in the sampling value supplied from 4 is expressed as a1 × cos (n × 2π / N + ζ1), fourier_cos, fourier_
The values of sin are respectively fourier_cos = a1 × cosζ1 fourier_sin = −a1 × sinζ1.

Therefore, the value of fourier_cos is 0
In this case, the absolute value of fourier_sin is a1, and the value calculated as the amplitude Vs is Vs = 2 × a1.

On the other hand, if the value of fourier_cos is not 0, the value calculated as the numerical value α is

[0134]

(Equation 12)

The value calculated as the amplitude Vs is

[0136]

(Equation 13)

Is obtained. That is, fourier_co
Regardless of whether the value of s is 0 or not, the value of the amplitude Vs calculated according to the flowchart of FIG. 5 is equal to the value of the amplitude Vs calculated according to the flowchart of FIG. 4, and Vs = 2 × a1. .

According to this embodiment, the value of the amplitude Vs can be calculated as a value equal to the peak-to-peak amplitude of the fundamental wave component without being affected by the initial phases ζ1 and ζk at all. .

(Embodiment 3) FIG. 6 is a block diagram showing another configuration of the frequency component calculating means in the embodiment of the present invention. In FIG. 6, reference numeral 18 denotes frequency component calculating means, and 18a denotes
This is an energy calculating unit that calculates the energy of the cosine wave component of frequency F / N hertz included in the signal indicated by the sampling value sequence supplied from the sampling unit 14. In addition, the same components as in FIG. 3 are denoted by the same reference numerals as in FIG. This frequency component calculating means 18
Is different from the frequency component calculating unit 15 of FIG. 3 only in that an energy calculating unit 18a is provided instead of the amplitude calculating unit 15k.

FIG. 7 is a flowchart showing the operation of the frequency component calculating means 18. In FIG. 7, the reference numerals of the components performing each operation are shown in parentheses.

Hereinafter, the operation of the frequency component calculating means 18 will be described with reference to FIG. However, the frequency component calculation means 1
8, the counting means 15a, the A / D conversion means 15b, the cosine value generation means 15c, and the sine value generation means 15
The operations of d, multiplication means 15e, multiplication means 15f, cumulative value storage means 15g, cumulative value storage means 15h, and Fourier coefficient calculation means 15j are exactly the same as those of the frequency component calculation means 15 in FIG. I do.

The energy calculating means 18a calculates the Fourier coefficient four supplied from the Fourier coefficient calculating means 15j.
Using ier_cos and fourier_sin,

[0143]

[Equation 14]

The value E obtained is calculated and supplied to the temperature calculating means 16. As already shown, fourier_cos = a1 × cosζ1 fourier_sin = −a1 × sinζ1, so the value of E calculated by the energy calculating unit 18a is:

[0145]

(Equation 15)

This shows the energy of a cosine wave having a frequency of F / N Hertz. When the frequency component calculating means 18 is used, the temperature calculating means 16 in FIG.
The energy E calculated by the frequency component calculating means 18 and the absolute temperature T0 of the object 2 supplied from the reference temperature measuring means 8
And the absolute temperature T of the object 1 to be measured.
To

[0147]

(Equation 16)

Is calculated. Note that the proportional constant K2 is
An object whose temperature is known is regarded as an object 1, and the object 1 at that time
From the absolute temperature T1, the absolute temperature T2 of the object 2, and the energy Ek calculated by the frequency component calculating means 18.

[0149]

[Equation 17]

May be determined in advance and stored in a nonvolatile memory or the like. In the calculation of the absolute temperature T, the calculation of the fourth root can be realized by repeating the operation for obtaining the square root twice using the same function as that for obtaining the square root of the energy E.

According to the present embodiment, the operation for calculating the square root does not exist in the frequency component calculating means 18 but is integrated in the temperature calculating means 16 as an operation that can be used in common with the operation for calculating the fourth root. Have been. Therefore, when the frequency component calculating means 18 and the temperature calculating means 16 are realized by independent dedicated hardware or independent microcomputer chips, a hardware or software routine for calculating the square root is provided by a temperature or temperature routine. Since only the calculation means 16 needs to be provided, the required hardware scale or software scale can be reduced as compared with the case where the frequency component calculation means 15 of FIG. 3 is used.

The energy calculating means 18a is removed from the frequency component calculating means 18 and the frequency component calculating means 1 is removed.
8 is a Fourier coefficient fourier_cos and fourier_sin calculated by the Fourier coefficient calculating means 15j,
Alternatively, a value proportional to them is supplied to the temperature calculating means 16, and the energy E or the amplitude Vs, or a value or amplitude V proportional to the energy E in the temperature calculating means 16.
It goes without saying that the same effect can be obtained even if a value proportional to s is obtained.

(Embodiment 4) FIG. 8 is a block diagram showing another configuration of the frequency component calculating means in the embodiment of the present invention. 8, reference numeral 19 denotes frequency component calculating means, 19a denotes counting means, 19b denotes sampling value storing means for storing a sampling value, 19c denotes a cosine value generating means for generating a constant value sequence determined as a value of a cosine function, and 19d denotes a sine value. Sine value generating means for generating a constant value sequence determined as a function value, 19
e and 19f are multiplication means for performing multiplication operations, and 19g and 19h are accumulation value storage means. In addition, the same components as in FIG. 3 are denoted by the same reference numerals as in FIG.

FIGS. 9, 10 and 11 are flowcharts showing the operation of the frequency component calculating means 19. In FIGS. 10 and 11, the reference numerals of the components performing each operation are shown in parentheses.

Hereinafter, the operation of the frequency component calculating means 19 will be described. As shown in FIG. 9, the operation of the frequency component calculating means 19 includes a data input process for storing the sampling value supplied from the sampling means 14 and a frequency included in a signal indicated by the sampling value sequence based on the stored sampling value. It consists of two arithmetic processes for calculating the amplitude Vs of the cosine wave component of F / N hertz.

First, the data input process will be described with reference to FIG. In the data input process, first, the counting means 19a initializes the count value n to zero.

Thereafter, the frequency component calculating means 19 waits for the sampling value to be supplied from the sampling means 14.

When an analog signal is supplied from the sampling means 14, the A / D converter 15b converts the sampled value into a digital signal, and converts the value V (n) obtained as a result of the conversion into a digital signal. This is supplied to the sampling value storage means 19b.

The sampling value storage means 19b is a memory for storing M × N sampling values. The location of the sampling value in the memory is determined by the counting means 19.
It is determined by the count value n of a. Hereinafter, the value stored in this storage location is referred to as a value M (n) using the count value n of the counting means 19a. The sampling value storage means 19b stores
When the value V (n) is supplied from the / D conversion means 15b,
The supplied value V (n) is stored as the value M (n).

Next, the counting means 19a increases the count value n by one. Thereafter, the frequency component calculation means 19 compares the count value n with M × N. As a result of the comparison, the count value n is M
If it is not equal to × N, after waiting for a new sampling value to be supplied from the sampling means 14, A / A
A series of processes from the process of converting the sampling value into a digital signal by the D conversion unit 15b to the counting unit 19a updating the count value n is repeated. When the count value n is equal to M × N, the data input processing is ended and the arithmetic processing is started.

Next, the arithmetic processing will be described with reference to FIG. In the arithmetic processing, first, the counting means 19a
Initializes the count value n to 0. Further, the accumulated value storage unit 19g initializes the accumulated value ΔVcos to 0. Similarly, the cumulative value storage unit 19h initializes the cumulative value ΣVsin to 0.

Next, the cosine value generating means 19c adds cos (n × 2π / N) to the count value n of the counting means 19a.
Then, a value cos_value determined as

The sine value generating means 19d is provided with a counting means 19a.
, A value sin_value determined as sin (n × 2π / N) is generated for the count value n and supplied to the multiplying means 19f.

The cosine value generating means 19c and the sine value generating means 19d may calculate the value to be generated by a numerical operation when the value is required, or may use a previously calculated value in a non-volatile manner. Alternatively, the information may be recorded in a non-volatile memory and read from the nonvolatile memory.

The multiplying means 19e is provided with a cosine value generating means 19c.
, The value M (n) stored in the sampling value storage means 19b is read, the product of M (n) and cos_value is calculated, and the calculation result Vcos is stored in the cumulative value storage means 19g. To supply.

The multiplying means 19f is provided with a sine value generating means 19d.
, The value M (n) stored in the sampling value storage means 19b is read, the product of M (n) and sin_value is calculated, and the calculation result Vsin is stored in the cumulative value storage means 19h. To supply.

The cumulative value storage means 19g is provided with a multiplication means 19e.
Is added to the accumulated value ΣVcos and stored as a new accumulated value ΣVcos.

The cumulative value storage means 19h is provided with a multiplication means 19f.
Is added to the cumulative value ΣVsin and stored as a new cumulative value ΣVsin.

Next, the counting means 19a increases the count value n by one. Thereafter, the frequency component calculation means 19 compares the count value n with M × N. As a result of the comparison, the count value n is M
If it is not equal to × N, the cosine value generating means 19c and the sine value generating means 19d set cos_value and sin
A series of processes from the process of generating _value to the updating of the count value n by the counting unit 19a is repeated. When the count value n is equal to M × N, the repetition ends, and the processing by the Fourier coefficient calculation unit 15j starts.

The Fourier coefficient calculating means 15j calculates the count value n
Is equal to M × N, the cumulative value ΣVcos stored in the cumulative value storage means 19g is doubled, and the counting means 19
The value obtained by dividing the count value n of a by the Fourier coefficient f of the cosine wave component
and the accumulated value storage means 1
A value obtained by doubling the accumulated value ΣVsin stored in 9h and dividing by the count value n of the counting means 19a is calculated as a Fourier coefficient fourier_sin of a sine wave component, respectively.
It is supplied to the amplitude calculating means 15k.

The amplitude calculating means 15k calculates the amplitude Vs,

[0172]

(Equation 18)

The calculation result is calculated as follows:
6 According to the frequency component calculating means 19 of the present embodiment, the amplitude V is exactly the same as that of the frequency component calculating means 15 of FIG.
s is calculated, but in the data input processing, only processing that can be performed in a relatively short time, such as storage of sampling values, is performed. In processing involving multiplication and division that requires more time, arithmetic processing is performed after the data input processing is completed. , So that the cumulative value for one sampling value Σ
Even if the oscillation frequency F of the first timing instructing means 11 is so high that the updating of Vcos and the accumulated value ΣVsin cannot be completed within one cycle of sampling by the sampling means 14, the amplitude Vs can be calculated without any problem. Becomes possible.

(Embodiment 5) FIG. 12 is a block diagram showing another configuration of the frequency component calculating means in the embodiment of the present invention. In FIG. 12, reference numeral 20 denotes frequency component calculation means, and 20a
Is a counting means, 20b is a sampling value accumulation storage means, 2
0c is a cosine value generation means for generating a constant value sequence determined as the value of the cosine function, 20d is a sine value generation means for generating a constant value sequence determined as the value of the sine function, 20e and 20f are multiplication means for performing a multiplication operation, 20g And 20h are cumulative value storage means, and 20j is a Fourier coefficient calculation means. In addition, the same components as in FIG. 3 are denoted by the same reference numerals as in FIG.

FIG. 13, FIG. 14, FIG. 15, FIG.
5 is a flowchart showing the operation of the frequency component calculation means 20. In FIGS. 14 to 16, the reference numerals of the components performing each operation are shown in parentheses.

The frequency component calculating means 20 processes the sampled values supplied from the sampling means 14 by classifying them into N groups. However, as already mentioned,
N is a natural number indicating a value twice the frequency division ratio of the frequency dividing means 12a.

The counting means 20a has two count values. Hereinafter, these two count values will be referred to as a count value n and a count value r. The count value n is determined by the sampling means 1
It is used to count the number of sampling values supplied from 4. On the other hand, the count value r is used to determine to which of the N groups the sampling value supplied from the sampling unit 14 belongs.

Also, the sampling value accumulation storage means 20b
Can store a total of N values, one for each group, obtained by cumulatively adding the sampling values supplied from the sampling means 14 for each group. Hereinafter, the stored value is referred to as a cumulative value S (r) using the count value r of the counting means 20a.

Hereinafter, the operation of the frequency component calculating means 20 will be described. As shown in FIG.
The operation of (1) is an initialization process for initializing the internal state, a data input process of classifying the sampled values supplied from the sampling means 14 into N groups, and accumulating and storing the data for each group. And an initialization process for calculating the amplitude Vs of the cosine wave component of the frequency F / N hertz included in the signal indicated by the sampling value sequence supplied from the sampling means 14 based on the values stored and stored. , Data input processing, and arithmetic processing.

First, the initialization processing will be described with reference to FIG. In the initialization processing, first, the counting means 2
0a initializes the count value r to 0.

Next, the sampling value accumulation storage means 20
b initializes the accumulated value S (r) to 0.

The counting means 20a increases the count value r by one. Thereafter, the frequency component calculation means 20 compares the count value r with N. As a result of the comparison, if the count value r is not equal to N, the sampling value accumulation storage means 20b repeats the process of initializing the accumulated value S (r) to 0 and the process of updating the count value r. When the count value r is equal to N, the initialization processing ends.

At the end of the initialization processing, the N cumulative values S (0) stored in the sampling value cumulative storage means 20b
ＳS (N−1) are all initialized to 0.

Next, the data input process will be described with reference to FIG. In the data input process, first, the counting means 20a initializes both the count value n and the count value r to zero.

Thereafter, the frequency component calculating means 20 waits for the sampling value to be supplied from the sampling means 14.

When the analog signal is supplied from the sampling means 14, the A / D conversion means 15b converts the sampling value into a digital signal, and converts the value V (n) obtained as a conversion result into a digital signal. This is supplied to the sampling value accumulation storage means 20b.

The sampling value accumulation storage means 15b stores
The value V (n) supplied from the / D conversion means 15b is added to the accumulated value S (r) and stored as a new accumulated value S (r).

Next, the counting means 20a increases the count value n by 1 and sets the value of the count value r to a value obtained by dividing the incremented count value n by a natural number N. That is, when the value of the quotient obtained by dividing the count value n by the natural number N is represented by an integer m of 0 or more, n = N × m + r (where 0 ≦ r ≦ N-1).

Thereafter, the frequency component calculating means 20 compares the count value n with M × N. As a result of the comparison, the count value n is M × N
If it is not equal to, after waiting for a new sampling value to be supplied from the sampling means 14, the A / D conversion means 15b converts the sampling value into a digital signal. Count value r
A series of processing is repeated until is updated. When the count value n is equal to M × N, the data input processing ends and the arithmetic processing starts.

Therefore, the accumulated value S at the end of the data input processing
The value of (r) is

[0191]

[Equation 19]

Is obtained. Next, the arithmetic processing will be described with reference to FIG.

In the arithmetic processing, first, the counting means 20
a initializes the count value r to 0. Further, the cumulative value storage unit 20g initializes the cumulative value ΣVcos2 to 0. Similarly, the cumulative value storage unit 20h initializes the cumulative value ΣVsin2 to 0.

Next, the cosine value generating means 20c adds cos (r × 2π / N) to the count value r of the counting means 20a.
Then, a value cos_value is determined and supplied to the multiplication means 20e.

The sine value generating means 20d is provided with a counting means 20a.
, A value sin_value determined as sin (r × 2π / N) is generated for the count value r, and supplied to the multiplying means 20f.

The cosine value generating means 20c and the sine value generating means 20d may calculate the value to be generated by a numerical operation when the value is required, or may use a previously calculated value in a non-volatile manner. Alternatively, the information may be recorded in a non-volatile memory and read from the nonvolatile memory.

The multiplying means 20e is provided with a cosine value generating means 20c.
, The value S (r) stored in the sampling value accumulation storage means 20b is read out, the product of S (r) and cos_value is calculated, and the calculation result Vcos2 is stored in the accumulation value storage means. 20g
To supply.

The multiplying means 20f is provided with a sine value generating means 20d.
, The value S (r) stored in the sampling value accumulation storage means 20b is read out, the product of S (r) and sin_value is calculated, and this calculation result Vsin2 is stored in the accumulation value storage means. 20h
To supply.

The cumulative value storage means 20g is provided with a multiplication means 20e.
Is added to the accumulated value ΣVcos2 and stored as a new accumulated value ΣVcos2.

The cumulative value storage means 20h is provided with a multiplication means 20f.
Is added to the accumulated value ΣVsin2 and stored as a new accumulated value ΣVsin2.

Next, the counting means 20a increases the count value r by one. Thereafter, the frequency component calculation means 20 compares the count value r with N. As a result of the comparison, when the count value r is not equal to N, the cosine value generation means 20c and the sine value generation means 20d set the cos_value and the sin_val
A series of processes from the process of generating ue to the process of updating the count value r by the counting unit 20a is repeated. Count value r is N
If is equal to, the repetition ends, and the processing by the Fourier coefficient calculation means 20j is started.

The accumulated values ΣVcos2 and 累積 Vsin2 when the count value r becomes equal to N are:

[0203]

(Equation 20)

Can be expressed as follows. The values of these will be described in detail later. When the count value r becomes equal to N, the Fourier coefficient calculating means 20j doubles the cumulative value ΣVcos2 stored in the cumulative value storing means 20g and divides the value by a natural number (M × N) to obtain a cosine wave component. A value obtained by doubling the cumulative value ΣVsin2 stored in the cumulative value storage means 20h and dividing by a natural number (M × N) as a Fourier coefficient fourier_cos is calculated as a Fourier coefficient fourier_sin of a sine wave component, and the amplitude is calculated. To the means 15k.

The amplitude calculating means 15k calculates the amplitude Vs

[0206]

(Equation 21)

[0207] The temperature calculation means 1 calculates
6 Next, when the count value r becomes equal to N, the accumulated value ΣV stored in the accumulated value storage means 20g is obtained.
A description will be given of what value the cos2 and the accumulated value ΣVsin2 stored in the accumulated value storage means 20h have.

From the conclusion, first, the accumulated value Σ
Vcos2 and the accumulated value ΣVsin2 are respectively shown in FIG.
In the flowchart of FIG. 7, the accumulated value ΣVcos and the accumulated value ΣVsin when the count value n is equal to M × N are equal to the values. Hereinafter, this will be described.

The count value n in the flowchart of FIG.
Is equal to M × N, the value of the accumulated value ΣVcos can be expressed as follows.

[0210]

(Equation 22)

This value is nothing but the value of the cumulative value ΔVcos2 when the count value r becomes equal to N.

Similarly, in the flowchart of FIG.
Cumulative value ΔVsi when count value n becomes equal to M × N
The value of n can be expressed as:

[0213]

(Equation 23)

This value is nothing but the value of the cumulative value ΔVsin2 when the count value r becomes equal to N.

Therefore, the frequency component calculating means 20 calculates
The same value as the frequency component calculation means 15 is calculated as the amplitude Vs.

According to the frequency component calculating means 20 of the present embodiment, similarly to the frequency component calculating means 19 of FIG. 8, the processing involving multiplication and division requiring a long time for the calculation is performed after the data input processing is completed. Therefore, the amplitude Vs can be calculated without any problem even if the period of one cycle in which the sampling means 14 performs sampling is not short enough to perform the multiplication operation.

Further, as compared with the frequency component calculating means 19, the sampling value storing means 19b had to store a total of M × N sampling values, whereas the sampling value accumulating means 20b of the present embodiment was required. Needs to store only N accumulated values. Therefore, a radiation thermometer having the same function can be realized with a smaller storage capacity. Increasing the natural number M and increasing the number of times that the sampling means 14 performs sampling is equivalent to the magnitude of the Gaussian noise included in the output signal of the filter circuit 13 such as the thermal noise of the infrared detecting element constituting the infrared detecting means 4. Is one of the effective means for relatively reducing the signal value with respect to the magnitude of the signal value.
According to 0b, only the same storage capacity as when no noise countermeasures are taken is required.

Further, the multiplication means 19e and the multiplication means 1 shown in FIG.
The number of times the multiplication operation is performed by 9f is M × N, whereas the number of times the multiplication unit 20e and the multiplication unit 20f of this embodiment perform the multiplication operation is only N times. Therefore, according to the frequency component calculating means 20 of the present embodiment, the amplitude Vs
Can be calculated.

(Embodiment 6) FIGS. 17, 18 and 19 show
6 is a flowchart illustrating another operation example of the frequency component calculating unit 20 according to the embodiment of the present invention. 17 to 19, the reference numerals of the components performing each operation are shown in parentheses.

[0220] The frequency component calculating means 20 of this embodiment converts the sampling value supplied from the sampling means 14 into
Processing is performed by classifying into N / 2 groups. Further, the accumulated value stored in the sampling value accumulation storage means 20b is shown in FIG.
4, T (r) is used to distinguish it from the flowcharts of FIGS. 15 and 16, and the accumulated value T (r) is also T (r).
N / 2 of (0) to T (N / 2-1). However,
As described above, N is a natural number indicating twice the value of the frequency division ratio of the frequency dividing means 12a, so N / 2 is also a natural number.

The counting means 20a determines whether the sampling value supplied from the sampling means 14 belongs to the N / 2 groups or the count value n for counting the number of sampling values supplied from the sampling means 14. Has two count values, a count value r used to determine.

The operation of the frequency component calculating means 20 according to the present embodiment includes an initialization process for initializing the internal state, and classifying the sampling values supplied from the sampling means 14 into N / 2 groups. And a data input process for accumulatively adding to and storing the data, and an amplitude Vs of a cosine wave component of frequency F / N Hertz included in a signal indicated by the sampling value sequence supplied from the sampling means 14 based on the value accumulated and stored. Is calculated, and the initialization processing, the data input processing, and the arithmetic processing are executed in this order.

First, the initialization process will be described with reference to FIG. In the initialization processing, first, the counting means 2
0a initializes the count value r to 0.

The sampling value accumulation storage means 20b initializes the accumulation value T (r) to zero. Next, the counting means 20
a increases the count value r by one.

Thereafter, the frequency component calculation means 20 compares the count value r with N / 2. As a result of the comparison, the count value r is N /
If it is not equal to 2, the sampling value accumulation storage means 20b repeats the process of initializing the accumulation value T (r) to 0 and the process of updating the count value r. When the count value r is equal to N / 2, the initialization processing ends.

At the end of the initialization processing, the N / 2 accumulated values T stored in the sampled value accumulating means 20b are stored.
The values of (0) to T (N / 2-1) are all initialized to 0.

Next, the data input processing will be described with reference to FIG. In the data input process, first, the counting means 20a initializes both the count value n and the count value r to zero.

Thereafter, the frequency component calculating means 20 waits for the sampling value to be supplied from the sampling means 14.

When the sampling value as an analog signal is supplied from the sampling means 14, the A / D conversion means 15b converts the sampling value into a digital signal, and converts the value V (n) obtained as a result of the conversion into a digital signal. This is supplied to the sampling value accumulation storage means 20b.

When the count value r is smaller than N / 2, the sampling value accumulation storage means 15b reads the A / D conversion means 1
The value V (n) supplied from 5b is added to the accumulated value T (r) and stored as a new accumulated value T (r). If the count value r is equal to or greater than N / 2, the value V (n) supplied from the A / D converter 15b is subtracted from the cumulative value T (r-N / 2). And a new accumulated value T
(R−N / 2).

Next, the counting means 20a increases the count value n by 1 and sets the value of the count value r to a value obtained by dividing the incremented count value n by a natural number N.

Thereafter, the frequency component calculating means 20 compares the count value n with M × N. As a result of the comparison, the count value n is M ×
If not equal to N, the frequency component calculating means 20
After waiting for a new sampling value to be supplied from the sampling means 14, the processing from the A / D conversion means 15b converting the sampling value to a digital signal to the counting means 20a updating the count value n and the count value r. Is repeated. When the count value n is equal to M × N, the data input processing ends and the arithmetic processing starts.

Therefore, the accumulated value T at the end of the data input process
The value of (r) is

[0234]

(Equation 24)

Is obtained. Next, the arithmetic processing will be described with reference to FIG.

In the arithmetic processing, first, the counting means 20
a initializes the count value r to 0. Further, the cumulative value storage unit 20g initializes the cumulative value ΣVcos3 to 0. Similarly, the cumulative value storage unit 20h initializes the cumulative value ΣVsin3 to 0.

Next, the cosine value generating means 20c adds cs (r × 2π / N) to the count value r of the counting means 20a.
Then, a value cos_value is determined and supplied to the multiplication means 20e.

The sine value generating means 20d is provided with a counting means 20a.
, A value sin_value determined as sin (r × 2π / N) is generated for the count value r, and supplied to the multiplying means 20f.

The cosine value generating means 20c and the sine value generating means 20d may calculate the value to be generated by a numerical operation when the value is required, or may calculate the value calculated in advance in a non-volatile manner. Alternatively, the information may be recorded in a non-volatile memory and read from the nonvolatile memory.

The multiplying means 20e includes a cosine value generating means 20c
, The value T (r) stored in the sampling value accumulation storage means 20b is read out, the product of T (r) and cos_value is calculated, and this calculation result Vcos3 is stored in the accumulation value storage means. 20g
To supply.

The multiplying means 20f includes a sine value generating means 20d
, The value T (r) stored in the sampling value accumulation storage means 20b is read out, the product of T (r) and sin_value is calculated, and this calculation result Vsin3 is stored in the accumulation value storage means. 20h
To supply.

The cumulative value storage means 20g is provided with a multiplication means 20e.
Is added to the accumulated value ΣVcos3 and stored as a new accumulated value ΣVcos3.

The cumulative value storage means 20h is provided with a multiplication means 20f.
Is added to the accumulated value ΣVsin3 and stored as a new accumulated value ΣVsin3.

Next, the counting means 20a increases the count value r by one. Thereafter, the frequency component calculation means 20 compares the count value r with N / 2. As a result of the comparison, the count value r is N
/ 2 is not equal to the cosine value generation means 20c and the sine value generation means 20d.
A series of processes from the process of generating _value until the counting unit 20a updates the count value r are repeated. When the count value r is equal to N / 2, the repetition ends, and the processing by the Fourier coefficient calculation means 20j starts.

When the count value r becomes equal to N / 2, the accumulated values ΔVcos3 and ΔVsin3 are

[0246]

(Equation 25)

It can be expressed as The values of these will be described in detail later. When the count value r becomes equal to N, the Fourier coefficient calculating means 20j doubles the cumulative value ΣVcos3 stored in the cumulative value storing means 20g and divides the value by a natural number (M × N) to obtain a cosine wave component. A value obtained by doubling the cumulative value ΣVsin3 stored in the cumulative value storage means 20h and dividing by a natural number (M × N) as a Fourier coefficient fourier_cos is calculated as a Fourier coefficient fourier_sin of a sine wave component, and the amplitude is calculated. To the means 15k.

The operation of the amplitude calculating means 15k is the same as that shown in the flowchart of FIG.

Next, when the count value r becomes equal to N / 2, the accumulated value Σ stored in the accumulated value storage means 20g is obtained.
The value of Vcos3 and the cumulative value ΣVsin3 stored in the cumulative value storage means 20h will be described.

From the conclusion, as stated earlier, the accumulated value at this time Σ
Vcos3 and the accumulated value ΣVsin3 are respectively shown in FIG.
Cumulative value ΣVco obtained according to the flowchart of FIG.
s2 and the accumulated value ２Vsin2. less than,
This will be described.

In the flowchart of FIG. 16, the value of the accumulated value ΣVcos2 when the count value r becomes equal to N can be expressed as follows.

[0252]

(Equation 26)

This value is nothing but the value of the cumulative value ΣVcos3 calculated in the flowchart of FIG.

Similarly, when the count value r becomes equal to N in the flowchart of FIG.
The value of n2 can be represented as follows.

[0255]

[Equation 27]

This value is nothing but the value of the cumulative value ΔVsin3 calculated in the flowchart of FIG.

Therefore, the amplitude Vs calculated using the flowchart in FIG. 19 has the same value as the amplitude Vs calculated in the flowchart in FIG.

According to the present embodiment, the number of cumulative values to be stored in the sampling value cumulative storage means 20 is as shown in FIGS.
7 is only half the case where the algorithm shown in the flowchart of FIG. 7 is used.
Can be realized with a smaller storage capacity.

The multiplication means 20e and the multiplication means 20f
Also has half the number of times that the algorithm shown in the flowcharts of FIGS. 15 to 17 is used, so that the amplitude Vs can be calculated in a shorter calculation time.

[0260]

As described above, as shown using various examples,
According to the present invention, the frequency component calculating means determines, among signal components of various frequencies included in the signal output by the infrared detecting means, the magnitude of the signal component whose frequency is equal to the infrared switching frequency by the infrared switching means. Based on the data sequence sampled by the sampling means, the calculation is performed using an algorithm that can remove the influence of the timing at which the sampling means starts sampling.
There is no need to create a synchronization signal as in the conventional technique using the synchronous detection technique. Therefore, it is not necessary to worry about the difference between the rising and falling timings of the synchronizing signal, and it is not necessary to take extra time to accurately determine these timings. Further, there is an excellent effect that there is no problem of how to determine the timing to start sampling as in the case where the synchronous detection circuit and the low-pass filter are directly converted into software.

Further, since the frequency component calculating means removes the harmonic component of the infrared switching frequency by the infrared switching means and calculates the magnitude of the signal component having the same frequency as the infrared switching frequency by the infrared switching means, There is an excellent effect that a noise component generated from the infrared switching means as an even harmonic component and mixed into an input signal of the sampling means can be satisfactorily removed.

The values of the two Fourier coefficients calculated by the Fourier coefficient calculating means are both the magnitude of the signal component having the frequency equal to the infrared switching frequency by the infrared switching means and the signal determined by the timing of starting the sampling. Since the phase of the component and the two can be represented by an equation with unknowns, using the calculated values of the two Fourier coefficients, in the manner of solving a binary simultaneous equation, the switching frequency of the infrared by the infrared switching means and The magnitudes of the signal components having the same frequency can be calculated.

Further, by calculating the sum of the squares of the two Fourier coefficients, the influence of the phase of the two unknowns can be removed, and the size of the remaining one unknown can be calculated accurately. Becomes

By determining the ratio of the two Fourier coefficients, the influence of the magnitude of the two unknowns can be removed, and the phase can be calculated accurately. Thereafter, by using the phase thus calculated and at least one of the two Fourier coefficients, it is possible to calculate the size of the remaining unknown.

Further, the magnitude of the amplitude calculated by the amplitude calculating means is a value proportional to the square root of the sum of the squares of the two Fourier coefficients. It is possible to calculate the magnitude of the signal component having a frequency equal to the switching frequency of the infrared ray by removing the influence of the phase determined by the sampling start timing.

Since the magnitude of the energy calculated by the energy calculating means is a value proportional to the sum of the squares of the two Fourier coefficients, the energy calculating means calculates the energy by the infrared switching means. The magnitude of the signal component of the frequency equal to the switching frequency of
The calculation can be performed by removing the influence of the phase determined by the timing of starting the sampling.

Since the cumulative value stored in the cumulative value storage means is a value proportional to the Fourier coefficient, the Fourier coefficient can be calculated by dividing the cumulative value by a predetermined constant.

In the period during which the sampling value storage means stores the sampling data, only the processing of storing the sampling value, which can be executed in a relatively short time, is performed, and the processing involving multiplication and division which requires more time is all performed. After the storage of the sampling data is completed, the data stored in the sampling value storage means is used to perform the multiplication and division operations required to calculate the values of the Fourier coefficients, amplitude, energy, etc. Even if the sampling period is too short to be completed within the time, the magnitude of the signal component whose frequency is equal to the infrared switching frequency by the infrared switching unit among the signal components of various frequencies included in the signal output by the infrared detecting unit Can be calculated.

Further, instead of the sampling value storage means storing the individual sampling data individually, the sampling value accumulation storage means stores the accumulation value of the sampling value and uses the accumulation value to reduce the storage capacity. Even if the sampling period is so short that the multiplication and division operations required to calculate the values of Fourier coefficients, amplitude, energy, etc. cannot be completed within one sampling period, the infrared detection means outputs Among the signal components of various frequencies included in the obtained signal, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means can be calculated.

Also, the sampled value accumulating and storing means alternately inverts positive and negative of the sampled data sequence and accumulatively adds, thereby storing half as compared with a case where the accumulative value is simply inverted without inverting the sign. Even if only a capacity is required and the sampling period is short enough that the multiplication and division operations required to calculate the values of Fourier coefficients, amplitude, energy, etc. cannot be completed within one sampling period, the infrared detection means Among the signal components of various frequencies included in the output signal, it is possible to calculate the magnitude of the signal component whose frequency is equal to the infrared switching frequency by the infrared switching unit.

Also, since it is possible to guarantee that the sampling frequency of the sampling means is exactly an integral multiple of the frequency at which the infrared switching means switches the infrared light, the frequency component calculating means is included in the signal output by the infrared detecting means. Among the signal components of various frequencies, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray by the infrared ray switching means can be accurately calculated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a radiation temperature measuring device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of infrared switching means in the radiation temperature measuring device.

FIG. 3 is a block diagram of a frequency component calculating means in the radiation temperature measuring device.

FIG. 4 is a flowchart showing an operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 5 is a flowchart illustrating an operation of an amplitude calculating unit in the radiation temperature measuring device according to the second embodiment of the present invention.

FIG. 6 is a block diagram of a frequency component calculating unit in the radiation temperature measuring device according to the third embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 8 is a block diagram of a frequency component calculating unit in the radiation temperature measuring device according to the fourth embodiment of the present invention.

FIG. 9 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 10 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 11 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 12 is a block diagram of a frequency component calculating unit in the radiation temperature measuring device according to the fifth embodiment of the present invention.

FIG. 13 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 14 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 15 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 16 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 17 is a flowchart illustrating an operation of a frequency component calculating unit in the radiation temperature measuring device according to the sixth embodiment of the present invention.

FIG. 18 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 19 is a flowchart showing the operation of a frequency component calculating means in the radiation temperature measuring device.

FIG. 20 is a block diagram of a conventional radiation thermometer.

FIG. 21 is a characteristic diagram of an amplifier circuit and a synchronous detection circuit in the radiation temperature measuring device.

FIG. 22 (a) is a characteristic diagram of the timing of sampling the output of the amplifier circuit in the radiation temperature measuring apparatus; and (b) is a characteristic diagram of the timing of sampling the output of the amplifier circuit.

[Explanation of symbols]

3 infrared switching means 4 infrared detecting means 8 reference temperature measuring means 9, 16 temperature calculating means 14 sampling means 15, 18, 19, 20 frequency component calculating means 15a, 19a 20a counting means 15e, 15f, 19e, 19f, 20e, 20f multiplication Means 15g, 15h, 19g, 19h, 20g, 20h Cumulative value storage means 15j, 20j Fourier coefficient calculation means 15k Amplitude calculation means 18a Energy calculation means 19b Sampling value storage means 20b Sampling value accumulation storage means

Claims (13)

[Claims] 1. An infrared ray radiated from an object as a temperature measurement target and an infrared ray radiated from an object as a reference temperature are alternately switched to be converted into an electric signal,
Among the signal components of various frequencies included in the electric signal, the magnitude of the signal component whose frequency is equal to the switching frequency of the infrared ray is determined based on a data sequence obtained by sampling the electric signal, and the influence of the sampling start timing. A radiation temperature measuring device that calculates the temperature of an object to be a temperature measurement target based on the calculation result and the temperature of the object as a reference temperature by using an algorithm that can remove the temperature. 2. An infrared detecting means for outputting a signal corresponding to a change in the amount of incident infrared light, and alternately switching between infrared light emitted from an object as a temperature measuring object and infrared light emitted from an object as a reference temperature. An infrared switching means for causing the infrared detection means to input the light, a sampling means for sampling an output signal of the infrared detection means, and a signal component of various frequencies included in the signal output by the infrared detection means, wherein the frequency is A frequency for calculating the magnitude of a signal component equal to the switching frequency of infrared rays by the infrared switching means, based on a data sequence sampled by the sampling means, using an algorithm capable of removing the influence of the timing at which the sampling means starts sampling. Component calculation means and reference temperature measurement for measuring the temperature of an object as a reference temperature Stage and the radiation temperature measuring device and a temperature calculating means for the frequency component calculation means and the value calculated is the reference temperature measuring means calculates the temperature of the object to the temperature measured from the temperature measurement. 3. The frequency component calculating means removes a harmonic component of an infrared switching frequency by the infrared switching means,
3. The radiation temperature measuring device according to claim 2, wherein a magnitude of a signal component having a frequency equal to the switching frequency of the infrared ray is calculated. 4. The frequency component calculating means, of the signal components of various frequencies included in the signal output from the infrared detecting means, has two frequencies equal to the switching frequency of the infrared ray by the infrared switching means and having a phase different by π / 2. 4. The radiation temperature measuring device according to claim 2, further comprising a Fourier coefficient calculating means for calculating a Fourier coefficient of the signal component. 5. The radiation temperature measuring apparatus according to claim 4, wherein the frequency component calculating means removes the influence of the sampling start timing by using a sum of squares of two Fourier coefficients. 6. The radiation temperature measuring device according to claim 4, wherein the frequency component calculating means removes the influence of the sampling start timing by using a ratio of two Fourier coefficients. 7. A frequency component calculating means for calculating an amplitude of a signal component having a frequency equal to an infrared switching frequency of the infrared switching means among various frequency signal components included in a signal output by the infrared detecting means. The radiation temperature measuring device according to claim 2, further comprising a calculating unit. 8. The frequency component calculating means calculates energy of a signal component having a frequency equal to an infrared switching frequency of the infrared switching means among various frequency signal components included in the signal output by the infrared detecting means. The radiation temperature measuring device according to any one of claims 2 to 6, further comprising energy calculating means. 9. The frequency component calculating means includes: a counting means for counting the number of data sampled by the sampling means; and a product of a constant determined according to a count value of the counting means and data sampled by the sampling means. 7. A multiplying means for calculating, and a cumulative value storing means for storing a cumulative value of the value calculated by the multiplying means.
The radiation temperature measuring device according to any one of claims 1 to 4. 10. The frequency component calculating means has a sampling value storing means for storing each data sampled by the sampling means, and after storing all the sampling data, the data stored in the sampling value storing means is stored. 7. A method for calculating the magnitude of a signal component having a frequency equal to the switching frequency of infrared rays by the infrared ray switching means among signal components of various frequencies included in a signal output by the infrared ray detecting means. The radiation temperature measuring device according to any one of claims 1 to 4. 11. The frequency component calculating means includes sampling value accumulating means for storing a plurality of values obtained by accumulating and adding data strings sampled by the sampling means in synchronization with a cycle at which the infrared switching means switches infrared rays. 2
7. The radiation temperature measuring device according to any one of claims 1 to 6. 12. A frequency component calculating means for accumulating a data string sampled by the sampling means by inverting positive and negative alternately in each half cycle in synchronism with a half cycle of a cycle in which the infrared switching means switches infrared rays. 7. The radiation temperature measuring apparatus according to claim 2, further comprising a sampling value accumulating means for storing a plurality of sampling values. 13. The radiation temperature measuring device according to claim 2, wherein the sampling means performs sampling at a frequency which is an integral multiple of the frequency at which the infrared switching means switches infrared rays.