JPH04353729A - Infrared-ray measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain an infrared-ray measuring apparatus which can follow the high-speed temperature change of an object. CONSTITUTION:A lowest-level correcting means 26 which corrects the lowest level of the output of each amplifier 22 to the same potential is provided. A memory means circuit 35, wherein the data of the means 26 and measuring condition data are stored, is provided. Therefore the potential of the lowest level is equal for every amplifier. When the lowest value is written once, changing is not required. Only the maximum value is obtained and written, and that is all. Thus, the operating time is shortened. The data in the apparatus immediately before the change in measuring conditions are stored. The data are read out, and the state before the change can be immediately reproduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an infrared measuring device for measuring the level of infrared rays emitted from an object.

0002

[Prior Art] It is known that any object with a temperature above absolute zero emits infrared rays from its surface, and there is a difference between the amount of radiated infrared rays (amount of energy) and the surface temperature of the object. There is a certain relationship called Planck's radiation formula. Therefore, the surface temperature of an object can be determined by measuring the amount of infrared radiation.

[0003] This amount of infrared rays is detected by an infrared detector, but one infrared detector can only detect infrared rays coming from a certain fixed direction. However, if a mechanism for bending the path of light, that is, a scanning mechanism is provided in front of the infrared detector, infrared radiation coming from various directions can be detected.

FIG. 2 is a diagram showing an example of this method.
1 is a rotating mirror configured in an annular manner with ten plane mirrors having slightly different vertical angles, 2 is a silicon window, 3 is a folding mirror, 4 is a condenser lens, 5 is a focus positioning motor, 6 10 is an infrared detecting element arranged in the vertical direction, and 7 is an amplifier provided for each infrared detecting element, so as to send out independent output signals for 10 channels.

In the device configured as described above, only infrared rays pass through the silicon window 2 and reach the rotating mirror 1. As described above, in the rotating mirror, the plane mirrors are provided at slightly different angles in the vertical direction, so each plane mirror laterally scans a portion of the subject that is slightly shifted in the vertical direction. One rotation of the rotating mirror 1 scans a range of 10 degrees in the vertical direction.

On the other hand, ten infrared detector elements 6 are arranged vertically, and the gap between the elements corresponds to an angle of 1.0 degrees in the vertical direction. Therefore, with one plane mirror, 1
The zero-element infrared detector 6 simultaneously receives thermal image signals at intervals of 1.0 degrees, and the next plane mirror simultaneously receives thermal image signals at a position shifted by 0.1 degrees from the previous position.

[0007] In this way, one rotation of the rotary mirror 1 scans 10 degrees in the vertical direction of the subject. In addition, regarding the horizontal direction, the horizontal viewing angle of each plane mirror of the rotating mirror (
(approximately 18 degrees). The thermal image signals thus obtained are each amplified by ten amplifiers and output. Reference numeral 8 denotes a temperature table, in which data such as the one shown in Table 1, which has been temperature-corrected in a blackbody furnace, is stored. For example, from 14 degrees to 2 degrees within the temperature range in Table 1.
If a temperature range of 3 degrees is required, the temperature range indicated by symbol A is selected using the switch 9, and the data for that range is written into the conversion table 10.

[0008]

[Table 1]

In this writing, as shown in FIG. 3, the voltage corresponding to the energy of infrared rays, that is, the input voltage value in Table 1 is written on the horizontal axis, and the temperature at that time is written on the vertical axis. 1st
Although the table is written using an analog signal, since writing is performed using an 8-bit digital signal, the values range from 0 to 255. For this reason, the missing portions from the values in Table 1 are interpolated to create data.

[0010] In this case, the lowest value is zero and the highest value is 255.
Set to . However, the linearity of infrared detectors is guaranteed only within a certain range. For this reason, if the input signal falls outside the linearity range, the input signal is attenuated by a filter or the like so that it falls within the linearity range. The results measured in this way are displayed in colors that correspond to the temperature of the object to be measured.

[0011]

However, there are a plurality of amplifiers, and their characteristics are not the same, and even if a filter is provided, the infrared detector may become saturated depending on the set width of the measurement range. Therefore, writing to the conversion table must be performed for each amplifier. However, each amplifier has a different offset amount and a different saturation level, so it takes a considerable amount of time to write while performing calculations each time, and this poses the problem of being unable to follow the rapid temperature changes of the subject.

[0012] Also, if the setting range or other measurement conditions are changed, it is necessary to rewrite the data in the conversion table.
When you try to compare and display the measurement conditions and the previous measurement conditions alternately, you have to make detailed settings again to return to the previous measurement conditions, which not only makes it impossible to compare quickly, but also Since data must be written, extra time is required to collect data for writing, making real-time comparison impossible.

[0013]

[Means for Solving the Problems] In order to solve such problems, the present invention provides a minimum level correction means for correcting the lowest level of each amplifier output to the same potential, and a memory for storing the data and measurement condition data. It is equipped with the means.

[0014]

[Operation] Since the lowest level potential is the same for each amplifier, there is no need to change the lowest value once it is written.
All you have to do is find and write only the maximum value. This shortens the calculation time, and since the data inside the device immediately before the measurement condition change is stored, the data can be read out and the state before the change can be immediately reproduced.

[0015]

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention, in which a thermal image signal generated by an infrared camera is sent to a multiplexer 20 via an amplifier for 10 channels (not shown).
supplied to This multiplexer 20 is selected one channel at a time under the control of the CPU 33, and the adder 2
1. Adders 21 and 23 are supplied with bias voltage by bias setters 25 and 27 controlled by CPU 33, and are set so that amplifier 22 and A/D converter 24 operate at optimal levels.

The gain of the amplifier 22 is controlled by a gain setter 26 controlled by the CPU 33, and the A/D converter 24 is controlled regardless of whether the level of the input signal is high or low.
It is designed to supply a signal at an acceptable level for conversion. In other words, when the input signal is large, the gain of the amplifier 22 is made small, and when the input signal is small, the gain of the amplifier 22 is made small.
The gain of the A/D converter 24 is set to be large so that a signal of the same level as possible is supplied to the A/D converter 24 in any case. The operating level of the A/D converter 24 is determined by a level setter 28 controlled by the CPU 33.

The output signal of the A/D converter 24 is sent to an adder 30.
and stored in the offset register 29 for each channel. This data is read by the CPU 33 and a moving average is taken, and the resulting value is supplied to the level setter 31, which is then supplied to the adder 30 to perform zero level correction for each channel. In this way, the signal whose zero level potential is aligned for each channel is supplied to the signal conversion table 32, so that an output signal corresponding to the input signal can be obtained.

The setting of data in the conversion table has been described above, but will now be explained in more detail. This device is capable of measuring temperatures ranging from -40°C to +950°C. This measurement is performed by converting the infrared thermal image signal energy detected by the camera into temperature using a conversion table. Basically, it is sufficient to configure the conversion table so that when a thermal image signal in that range is input, the corresponding temperature information is output. However, if the conversion table covers the entire measurement range, measurement accuracy will deteriorate. For this reason, the measurement range is divided into several areas, and the conversion table handles only the data in the divided areas. Table 1 above is one of these divisions. In order to measure even more precisely,
Interpolation is performed as described above.

The data handled by the conversion table is 8-bit digital data, and the values of the data handled therein vary within the range of 0 to 255. Therefore, it is necessary to make zero correspond to the minimum value and 255 to the maximum value. For example, one of the divided ranges is from -40℃ to +1
Assuming that the temperature is 27.5°C, it is necessary to write in the conversion table so that zero corresponds to minus 40°C and 255 corresponds to plus 127.5°C.

However, in this example, there are input signals for 10 channels, and each channel is amplified by a different amplifier, so the lowest level and highest level are different for each channel. For this reason, originally, it would be necessary to calculate and allocate the lowest level and highest level for each channel so as to correspond to 0 to 255 in the conversion table, and write the calculation results in the conversion table. Furthermore, since the dynamic range of the input signal is wide when the temperature measurement range is wide, the amplifier 22 or the A/D converter 24
linearity cannot be ensured, and saturation occurs at high levels.

In this case, it is necessary to write data to the conversion table in the same manner. That is, originally, data would be written as shown by the solid line in FIG. 3, but since it saturates at an intermediate level, it is necessary to write data as shown by the dotted line. If all such calculations are performed at the time of writing, a corresponding amount of calculation time will be required, and the processing will not be completed in time. In order to solve this problem, the lowest level of the amplifiers is made the same.

For this purpose, as shown in FIG. 1, the offset level of each channel,
That is, the lowest level is stored and the moving average value is stored in the CPU 3.
3, and this moving average value is supplied to the adder 30 via the level setter 31. By doing this, the lowest level of each channel is unified and becomes the same value. Therefore, for the lowest level, calculation for each channel is no longer necessary, and the calculation time is shortened.

The above is a means for performing high-speed calculation, but
In addition to the above-mentioned operations, the present application has a function of immediately returning to the previous measurement state. A means for realizing this is the memory circuit 35 shown in FIG. This storage circuit stores all the operating conditions of each circuit immediately before the measurement conditions are changed. Therefore, when the switch 36 is turned on, the data of each circuit is replaced with the data immediately before the setting condition change, and the measurement state immediately before the measurement condition change is displayed on the display.

It should be noted that, as a matter of course, data after changing the measurement conditions is also stored in the memory circuit 35. Therefore, by turning on and off the switch 36, the measurement conditions before and after the change in the measurement conditions are alternately displayed. be done.

[0025]

As explained above, the present invention provides a minimum level correction means for correcting the minimum level of each amplifier output to the same potential, and a storage circuit for storing data representing the operating state of each circuit immediately before a change in measurement conditions. Since the measurement condition is provided, the measurement condition after the measurement condition is changed and the measurement condition immediately before the change can be displayed alternately, and comparative measurements can be easily performed.

[Brief explanation of drawings]

[Fig. 1] Block diagram showing one embodiment of this invention

[Figure 2]
Diagram showing the configuration of the infrared detection section

[Figure 3] Graph showing characteristics of conversion table

[Explanation of symbols]

1 Rotating mirror 2 Silicon window 6 Infrared detection element 7 Amplifier 8 Temperature table 10, 32 Conversion table 20 Multi-table 24 A/D converter 29 Offset register 30 Adder 31 Level setting device

Claims (1)

[Claims] Claim 1: By optically scanning a field of view, infrared rays from various parts within the field of view are detected by a plurality of infrared detectors, and the output signals of these infrared detectors are individually amplified by a plurality of amplifiers to obtain a thermal image. An infrared measuring device comprising: a minimum level correction means for correcting the lowest level of each amplifier output to the same potential; and a storage means for storing setting conditions and measurement condition data of each circuit at this time. measuring device.