JPH0454420A - Infrared measuring instrument - Google Patents

Abstract

PURPOSE:To eliminate the need to correct and calculate the lowest level of each amplifier output, channel by channel, and to shorten the arithmetic time by correcting the lowest level of each amplifier output to the same potential. CONSTITUTION:A heat image signal generated by an infrared camera is supplied to a multiplexer 20 through amplifiers for 10 channels, and selected, channel by channel, and supplied to an adder 21. A bias voltage is applied to adders 21 and 23 and an amplifier 22 and an A/D converter 24 are so set as to operate with the best level. The output signal of the A/D converter 24 is supplied to an adder 30 and in an offset adjustment period, the signal is stored in an offset register 29, channel by channel. Then their movement mean value is found by a CPU 33 and supplied to an adder 30 through a level setter 31. Consequently, the lowest levels of the respective channels are set to the same value and the channel-by-channel arithmetic for the lowest levels is not necessary, so that the arithmetic time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared measuring device that measures the level of infrared rays emitted from an object.

[Prior Art] It is known that any object with a temperature above absolute zero emits infrared rays from its surface, and there is a relationship between the amount of radiated infrared rays (amount of energy) and the surface temperature of the object. There is a certain relationship called Blank's radiation formula. Therefore, the surface temperature of an object can be determined by measuring the amount of infrared radiation. This amount of infrared rays is detected by an infrared detector, but a single infrared detector can only detect infrared rays coming from a certain direction. A mechanism can be provided to detect infrared radiation coming from various directions.

FIG. 2 is a diagram showing an example of this method, in which 1 is a rotating mirror configured in an annular manner with 10 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 focusing motor, 6 is 10 infrared detection elements arranged vertically, and 7 is an amplifier provided for each infrared detection element. ) is designed to output independent output signals.

In the device configured in this manner, the 0-rotation mirror that transmits infrared rays through the silicon window l and reaches the rotating mirror l is a plane mirror that is disposed vertically by 0.05 degrees as described above. Each plane mirror horizontally scans a portion of the subject that is shifted by 0.1 degrees in the vertical direction. One rotation of this rotating mirror 1 causes 10 in the vertical direction.
It is designed to scan a range of degrees. On the other hand, ten infrared detectors 6 are arranged in the vertical direction, and the interval between them corresponds to an angle of 1.0 degrees in the vertical direction.

Therefore, one plane mirror has 10 elements of infrared detector 6.
．． The thermal image signals at 0 degree intervals are simultaneously received, and the next plane mirror simultaneously receives the thermal image signals at a position shifted by 0.1 degree from the previous position. In this way, one rotation of the rotating mirror 1 scans 10 degrees in the vertical direction of the subject. Also,
In the horizontal direction, the horizontal viewing angle (approximately 18 degrees) of each plane mirror of the rotating mirror is scanned.

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.

If, for example, a temperature range from 14 degrees to 23 degrees is required among the temperature ranges in Table 1, select the temperature range indicated by symbol A with switch 9, and the data in that range will be converted to the conversion table 1.
Written to 0.

Table 1 In this writing process, 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. Table 1 is written using analog signals, but since writing is performed using 8-bit digital signals, the values range from 0 to 255. For this reason, the missing portions from the values in Table 1 are interpolated to create data.

In this case, the lowest value is set to zero and the highest value is set to 255.

However, the linearity of an infrared detector is guaranteed only within a certain range, so if the linearity falls outside of that range, the input signal is attenuated using a filter or the like to bring it within the linearity range.

[Problems to be Solved by the Invention] 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. For this reason, writing to the conversion table must be performed for each amplifier. However, since each amplifier has a different offset amount and a different saturation level, it takes a considerable amount of time to write while performing calculations each time. For this reason, there was a problem that it was not possible to follow the rapid temperature changes of the subject.

Also, writing data to the conversion table is equivalent to changing the measurement center temperature, changing the temperature resolution, or changing the temperature measurement setting range), changing the temperature table, or changing the room temperature. , it is necessary to rewrite the conversion table each time the saturation level written to the conversion table changes, and this also requires high-speed arithmetic processing.

[Means for Solving the Problems] In order to solve such problems, the present invention always keeps the lowest level of the observation range the same by means of measuring the offset level of each amplifier output and a subtractor that subtracts it from the amplifier output. A minimum level correction means for correcting the electric potential is provided.

[Operation] Since the lowest level potentials are the same for each amplifier, there is no need to change the lowest value once it is written, and it is sufficient to find and write only the maximum value. This reduces calculation time.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.
Thermal image signals generated by the infrared camera are supplied to the multiplexer 20 via an amplifier (10 elements/10 channels (not shown)). This multiplexer 20 is a CPU
33 selects one channel at a time and sequentially supplies it to the adder 21. Adders 21 and 23 are CPU 33
A bias voltage is supplied by bias setters 25, 27 controlled by the amplifier 22 and the A/D converter 24 to set them to operate at optimal levels. Amplifier 22 is a gain setter 26 controlled by CPO 33
The gain is controlled by the A/D converter 24, and a signal at a conversion permissible level is supplied to the A/D converter 24 regardless of whether the level of the input signal is high or low. That is, when the input signal is large, the gain of the amplifier 22 is made small, when the input signal is small, the gain of the amplifier 22 is made large, and the A/D converter 24 is made to have the same level as possible in all cases. The signal is now supplied. The operating level of the A/D converter 24 is determined by a level setter 28 which is controlled by the CPU 33.

The output signal of the A/D converter 24 is supplied to the adder 30, and is stored in the offset register 29 for each channel during the offset IIN adjustment period.

The data in this offset register 29 is read by the CPU 33, a moving average is taken, and the value is determined by the level setter 3.
1 and is supplied to an 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 it will be explained in more detail here. 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, all you need to do is configure the conversion table so that when a thermal image signal in that range is input, the corresponding temperature information will be output.However, if the conversion table is set to the entire measurement range, the measurement accuracy will decrease. I'll wear them. 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 is one of these divisions. In order to measure even more accurately, 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 there vary in the range from 0 to 255. For this reason, it is necessary to make zero correspond to the lowest value and 255 to the maximum value. For example, if one of the divided ranges is from -40°C to +127.5°C, zero corresponds to -40°C. Correspond, 255
It is necessary to write it into the conversion table so that it corresponds to +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, the lowest level and highest level for each channel should be set to 0 to 25 in the conversion table.
5 and write the calculation result in the conversion table.Furthermore, if the temperature measurement range is wide, the dynamic range of the input signal is wide, so the straight line of the amplifier 22 or A/D converter 24 must be In this case, data must be written in the conversion table in the same way. 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, it will take a considerable amount of calculation time.
Processing will not be done in time. In order to solve this problem, the lowest level of the amplifiers is made the same.

For this purpose, the offset level of each channel is stored in the offset register 29 as shown in FIG.
The moving average value is obtained by the CPU 33, and the level setter 31
This moving average value is supplied to the adder 30 via. 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.

[Effects of the Invention] 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, so there is no need to perform minimum level correction calculation for each channel. This has the effect of shortening the calculation time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of an infrared detection section, and FIG. 3 is a graph showing the characteristics of a conversion table. 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 setter.

Claims (1)

[Scope of Claim] In an infrared measurement device that obtains a thermal image by individually amplifying the output signals of a plurality of infrared detectors using the same number of amplifiers, there is provided a means for measuring an offset level of each amplifier output, and a means for measuring an offset level of each amplifier output; An infrared measuring device characterized by being provided with a minimum level correction means for always correcting the lowest level in the observation range to the same potential using a subtracter.