JPS61241629A - Infrared radiation thermometer - Google Patents

Abstract

PURPOSE:To measure a temperature of a material body under noncontact state by using a diffraction grating and a peak detecting circuit and not knowing an absolute value of emissivity and infrared radiation electric power of the material body. CONSTITUTION:The titled thermometer is provided with the diffraction grating 7, a servomotor 8, an angle detector 9, a sample and hold circuit 10, the peak detection circuit 11 and an optical cut-off filter 12 of higher order, etc. Then, incident infrared rays are divided spectrally with the grating 7 and made basic wave components alone with the filter 12 and condensed by an infrared lens 1 and detected by an infrared detector 2. The grating 7 is turned by the motor 8 and the spectral wavelength is changed to measure a wavelength characteristic of the infrared radiation electric power. When a maximum point of the wavelength characteristic is detected with the circuit 11, an output signal of the detector 9 is held with the circuit 10. Then, the output of the circuit 10 as it is displayed on a display part 4. Further, in order to eliminate the influence which is given to the wavelength characteristic of the infrared radiation electric power by respective wavelength characteristics of the sensitivity of the detector 2, the diffraction efficiency of the grating 7 and the transmissivity of the lens 1, a gain of a detector amplifier 3 is changed and compensated every wavelength with an amplifier gain variable device 5 responding to wavelength information from the detector 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an infrared radiation thermometer that can measure temperature in a non-contact manner using infrared rays emitted by an object.

[Conventional technology]

Figure 3 is a configuration diagram showing a conventional infrared radiation temperature needle. An infrared detector that outputs a signal, (3) a detector amplifier that amplifies the output of the infrared detector (2), +6) Emissivity data of the object to be measured, and (5) detected by the emissivity data (6) instrument amplifier (
3) An amplifier gain variable device that adjusts the gain.

(This is a 41U temperature display section.

A conventional infrared radiation thermometer is constructed as described above.For example, the emissivity data (6) of the object to be measured is set in advance in the amplifier gain variable device (5), and the infrared radiation emitted by the object is measured. is detected by an infrared detector (2), and the emissivity-corrected object temperature is displayed on a temperature display section (41) through a gain-adjusted detector amplifier (3).

[Problem that the invention seeks to solve]

With conventional infrared radiation thermometers such as those mentioned above, the emissivity of the target object must be known before temperature measurement.
The emissivity also varies greatly depending on the material and surface condition of the object, making it difficult to grasp accurately and making it difficult to accurately measure temperature.

The present invention was made to solve these problems, and aims to realize an infrared radiation thermometer that can measure temperature without being affected by emissivity.

[Means for solving problems]

The infrared radiation thermometer according to the present invention includes a circuit that detects the spectral diameter of infrared rays emitted from an object using a diffraction grating, and detects the infrared wavelength at which the radiated power is maximum.

[Effect]

In this invention, incident infrared rays are spectrally dispersed using single diffracted photons, and the wavelength at which the radiated infrared power is maximum is detected, and the temperature is converted into an object temperature based on radiation theory and then displayed.

〔Example〕

FIG. 1 is a block diagram of an infrared radiation thermometer showing an embodiment of the present invention. (11, +21. +31. (41
, (51 is the same as the above conventional device. (7) is a diffraction grating.

(8) is the servo motor for driving it, (9) is the angle detector for detecting the rotation angle of the servo motor (8), +II is the sample hold circuit that holds the output of the angle detector (9), and aυ is the light receiving circuit. A peak detection circuit that detects the maximum radiated power.

Q2 is a high-dimensional cut filter that removes components of high-order light generated by the diffraction grating.

In an infrared radiation thermometer configured as described above, 1
The temperature is determined based on the following radiation theory.

The radiant emittance W(λ, T) of a black body can be expressed by the following equation.

...(1) Where, T: Blackbody temperature ('K) λ: Wavelength (μm) aI=3.74X10 (Watfyfdi -μ?
FF' ) 0, = 1.44 Xi G'(μm-'
K) When the above equation (1) is partially differentiated with respect to the wavelength λ...(2
) From the above equation (2), when the inorganic body is at a certain temperature TO, the wavelength λmax having the maximum radiation power satisfies the following equation.

According to the above equation (3), Q is the wavelength λma having the maximum radiation power.
Once x is obtained, the blackbody temperature TO at that time can be found.

□ For general objects, not black bodies, the emissivity ε is not constant at 1 but is a function of wavelength, but in a certain wavelength band it can be approximated as a constant of 6 < 1 (gray body). Therefore, the above equation (3) also holds true for radiation from a general object. In other words, by knowing the wavelength at which each wavelength-minute of infrared radiation power is maximum, it is possible to measure the temperature of an object regardless of the emissivity value.

In Fig. 1, the incident infrared rays are separated by a diffraction grating (7).

High-order optical cut filter H eliminates only the fundamental wave component.

The light is focused by an infrared lens (1) and sent to an infrared detector (2)
Detected in The above diffraction grating (7) is moved by a servo motor (8
) to change the wavelength for one minute, and measure the wavelength % characteristic of the infrared radiation power. When the peak detection circuit 1 detects the maximum point of the wavelength characteristic, the output signal of the angle detector (9), that is, the wavelength information, is held in the sample and hold circuit member. The temperature of the object to be measured and the wavelength at the maximum point have a 1:1 correspondence according to equation (3) above, so the output of the sample and hold circuit QI can be directly displayed on the temperature display section (4). indicate. In this example, the wavelength characteristics of the diffraction efficiency/rate of the two-sensitivity diffraction grating (7) of the infrared detector (2) and the transmittance of the infrared lens (1) are determined by the wavelength of the infrared radiation power. In order to eliminate the influence on the characteristic measurement, the above angle detector (
9) Amplifier gain variable device (5) that receives wavelength information from
The gain of the detection 67 amplifier (3) is changed for each wavelength to compensate. "An embodiment of the peak detection circuit according to the present invention is shown in FIG. 2. In the figure, (II is a comparator, (14) t-
t buffer, OUT, gate, ae is the detector amplifier output, αη is the sample and hold signal. A comparator compares the detector amplifier output 00 and the output of buffer a4.

If the detector amplifier output tteO is larger, is the sample hold signal 0? ) is output, and the game H1 is opened and the contents of the back γα line are updated to the current detector amplifier output H. Therefore, in the end, the content of back γα mold becomes the maximum value of detected infrared rays.

The sample and hold circuit Q1m also holds the wavelength signal at the maximum point.

〔Effect of the invention〕

As explained above, this invention has the effect of being able to measure the temperature of an object without contact, without knowing the emissivity of the object or the absolute value of the infrared radiation power, by using the diffraction grating and the peak detection circuit. .

[Brief explanation of drawings]

Fig. 1 is a block diagram of an infrared radiation thermometer showing an embodiment of the present invention, Fig. 2 is a block diagram of the peak detection circuit shown in Fig. 1, and Fig. 3 is a block diagram of a conventional infrared radiation thermometer. It is. In the figure, (2) is an infrared door detector, (3) is a detector amplifier, (4) is a temperature display section, (5) is an amplifier gain variable device, mn diffraction grating, (8) is a servo amplifier, ( 9) is an angle detector, (11 is a sample hold circuit, and 0υ is a peak detection circuit. The same reference numerals in Figure 1 indicate the same or equivalent parts.

Claims (1)

[Claims] A diffraction grating that separates infrared rays emitted from an object, a servo motor that rotates this diffraction grating and changes its angle with respect to the incident infrared rays, an angle detector that detects the rotation angle of this servo motor, and an angle detector that detects the rotation angle of this servo motor. A sample hold circuit that holds the output, an infrared detector that detects the infrared rays separated by the above-mentioned diffraction grating, a detector amplifier that amplifies the output signal of this infrared detector, and a maximum value of the output of this detector amplifier. a peak detector for detecting and sending a sample signal to the sample hold circuit; and amplifier gain variable means for inputting the output of the angle detector and adjusting the gain of the detector amplifier according to the rotation angle of the diffraction grating. ,
An infrared radiation thermometer comprising: a temperature display section that displays the output of the sample and hold circuit.