JPS6021329B2 - thermography equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention eliminates errors caused by the fact that the emissivity of the subject is not 1, and errors caused by reflected infrared rays emitted from the surrounding environment of the subject and reflected on the subject, which enter the infrared detector. The present invention relates to a thermography device that can automatically perform correction.

Generally, the intensity W of infrared rays emitted from a subject having a temperature T is expressed by the following equation.

However, 〇 is a proportionality constant, and z is the emissivity of the subject. VV=
[11] When detecting infrared rays from the subject with an infrared detector,
The infrared rays incident on the detector include infrared rays emitted from the subject as well as infrared rays from the infrared ray emitting surface around the temperature Ta (usually room temperature) reflected on the subject surface (the second in the following equation
) is incident on the infrared detector, and the intensity W of the infrared rays incident on the infrared detector is given by the following equation.

W = Go. r+(1-go). Ta4. ．． ．． ．． ．．・【
2} Therefore, the above intensity W obtained by the infrared detector
Since the signal corresponding to W does not correspond to the intensity component OT4 that is related only to the true temperature T of the subject, the signal corresponding to W is corrected and given by the following equation {3'. Obtain the corresponding signal, spread this signal on the cathode ray tube surface,
An image representing the true temperature of the subject is obtained. .

r=W-OTa40. T34. ．．・…
t3} That is, as is clear from this equation, in order to obtain a signal corresponding to the true temperature of the subject, it is necessary to correct the error based on the fact that the emissivity is not 1, and the error due to the inclusion of reflected infrared rays. . Conventional equipment has an emissivity correction mechanism and a room temperature reflection correction mechanism that perform corrections by adjusting variable resistors etc. with knobs, and after measuring the emissivity by measuring the side temperature of the subject surface using a contact thermometer in advance , these knobs are adjusted manually. Therefore, each time an observation is made, it is necessary to operate the two correction knobs mentioned above, which is difficult to handle, and the emissivity of the subject must be measured in advance, which is time-consuming.
In order to solve these problems, the present invention provides a thermography system that can automatically perform corrections related to emissivity and reflected infrared rays, and the principle thereof will be explained in detail below.

First, the emissivity of the object is determined by the following equation by modifying the equation (2) above.

W-.

T. ．． ．． ...[4'go=. rIO
TゞThe point A of the object detected by the infrared detector
The infrared intensity is based on the infrared intensity W at , and the temperature T at the point A of the subject.

The above [[ Equation 4' is calculated to obtain a signal corresponding to each emissivity at point A of the object. By the way, the emissivity at a certain point A obtained at this time is usually not much different from the emissivity at other parts of the subject. Therefore, the output signal corresponding to the emissivity f determined by the emissivity measurement circuit and the reflected infrared intensity OTa4 based on the environmental temperature Ta
By introducing the output signal from the side-type thermometer corresponding to Errors associated with temperature are automatically corrected, resulting in a signal that corresponds to the true temperature of the subject. The drawing shows an embodiment according to the above principle, in which 1 is an optical scanning means for scanning and condensing infrared rays emitted from a subject 2 and guiding them to an infrared detector 3, which receives a scanning signal from a scanning circuit 4. is scanned two-dimensionally based on After the infrared signal detected by the infrared detector 3 is amplified by the amplifier 5,
The signal is sent to a correction circuit 6 where the emissivity and reflected infrared intensity are corrected. The output signal from the correction circuit is converted by the linearity correction circuit 7 into a temperature signal having an IJ-near relationship with the temperature of the object, and then integrated into the grid of the cathode ray tube 8 synchronized with the optical scanning means 1. Ru. 9a
and 9b are contact type thermometers such as thermocouples or thermistors, the thermometer 9a measures the temperature at any location on the subject 2, and the thermometer 9b measures the environmental temperature around the subject, such as the temperature of a room wall, etc. It is for measuring.

The output signals from these thermometers are matched with each other.
It is introduced into the emissivity measuring circuit 11 via 0a and 10b. Further, a part of the output signal from the infrared detector 3 is taken out and introduced into the emissivity measurement circuit by an output extraction circuit 12, and the output signal from the emissivity measurement circuit is sent to the correction circuit 6. be introduced. The output signal from the matching circuit 10a is also introduced into the nuclear correction circuit.
The output extraction circuit 12 is configured to display, for example, a horizontal marker and a vertical marker on the screen of the cathode ray tube, and to extract an output signal from the infrared detector 3 corresponding to the position where both markers intersect. In the above-described configuration, first, the thermometer 9a is brought into contact with an arbitrary point A on the subject 2,
When the thermometers gb are brought into contact with the chamber wall 13 that emits reflected infrared radiation, each thermometer sends an output signal corresponding to the measured temperature to matching circuits 10a and 10b, respectively.

By appropriately adjusting the gain and the bell of the output signal of each thermometer in both matching circuits, from 10a onward, the equation {41 above is obtained. A signal corresponding to the value of r and a signal corresponding to the value of OTa4 in the same equation are obtained from 10b, respectively, and both of the obtained signals are introduced into the emissivity measuring circuit 11. The signal from 10b is also introduced into correction circuit 6. On the other hand, by scanning the optical scanning means 1, an apparent temperature distribution image is displayed on the cathode ray tube 8 without correction of the emissivity of the subject and the intensity of reflected infrared rays, and at the same time an external image of the thermometer 9a is displayed. is displayed, the output extraction circuit 12 aligns the intersection of the horizontal and vertical markers with the point A where the thermometer 9a of the subject is in contact, thereby obtaining the infrared intensity signal from the infrared detector 3 at the point A of the subject, i.e. A signal corresponding to the value of W in the above formula (4) is extracted. Since the extracted signal is introduced into the emissivity measuring circuit 11, the above-mentioned equation (2) is calculated in the emissivity measuring circuit 11, and the emissivity at point A of the subject 2 is measured. When the emissivity measurement is completed, the emissivity measurement circuit 11 sends an output signal corresponding to the emissivity to the correction circuit 6.
In order to introduce the true temperature at each point of the object, the correction circuit calculates the equation '3} to obtain a signal corresponding to the true temperature at each point of the object. The obtained signal is converted into a temperature signal by the linearity correction circuit 7 and supplied to the cathode ray tube 8, so that an accurate temperature distribution image of the subject 2 is displayed. By configuring as described above, the present invention can provide a thermography apparatus that can automatically correct errors due to the inclusion of emissivity and reflected infrared rays, and has great practical effects.

[Brief explanation of drawings]

The drawing is a basic diagram showing an embodiment of the present invention.

Claims (1)

[Claims] 1. Infrared rays obtained by two-dimensionally scanning an object with an optical scanning means are detected by an infrared detector, and the detection signal is introduced into a display means synchronized with the optical scanning means to display the object. The device for obtaining a temperature distribution image includes: a first contact thermometer that is in contact with a point on the surface of the subject; a second contact thermometer that is in contact with a point on an infrared radiation surface around the subject; means for extracting a detection signal of the infrared detector corresponding to a point in contact with the first contact thermometer on a surface, and the extracted detection signal and the first and second contact thermometers; means for obtaining a signal corresponding to the emissivity of the subject based on a signal from the means, and a signal corresponding to the emissivity from the means and a signal from a contact thermometer in contact with an infrared radiation surface around the subject. Therefore, a thermography apparatus characterized in that it is provided with means for converting a signal from the infrared detector into a signal corresponding to the true temperature of the subject.