JPS63180829A - Linearizer for infrared temperature detector - Google Patents

Abstract

PURPOSE:To realize a linearizer capable of obtaining an ideal linear output characteristic, by arranging an infrared detector, a logarithmic conversion circuit, an A/D converter, a read-only-memory and the like. CONSTITUTION:Radiation infrared rays of a reference blackbody furnace and an object to be observed are introduced alternately into an infrared detector 1. A detection signal of the detector 1 is amplified with a preamplifier 2 while an infrared ray detection signal of the object to be measured is clamped with a clamp circuit 3 to a detection level of a reference infrared ray which is released from the reference blackbody furnace to obtain a signal corresponding to an absolute temperature T of the object being measured. This signal is sent to an A/D converter 5 through a logarithmic amplifier 4 to be converted into a digital signal. At a read-only-memory 6, a temperature value previously stored is read out with this digital signal as address signal. This temperature value is sent to a display device 7 to be displayed in numeral display. This makes adjustment simple along with a simplified construction of the circuit. The use of the logarithmic circuit can reduce the number of bits of the A/D converter 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a calibration circuit for a measured temperature value of an infrared temperature detection device.

[Prior Art] Generally, an infrared temperature detection device detects infrared rays emitted by an observation object, converts the infrared rays into an electrical signal, and outputs the electrical signal. It is known that the correlation between the detection signal of the infrared detector and the temperature of the observed object has nonlinear characteristics as shown in FIG. 2(a). A linearizer is used to convert the detection signal of the infrared detector into one with characteristics linear with temperature. Conventionally, a polygonal line approximation circuit has been used as the linearizer.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, since the linearizer is configured by a polygonal line approximation circuit, the complicated circuit structure and the difficulty of adjustment in the circuit are considered to be major problems.

The present invention solves the above problems, and aims to provide a linearizer that can obtain ideal linear output characteristics by adding a simple configuration to an infrared temperature detection device. .

[Means for Solving the Problems] To this end, the present invention provides an infrared detector that detects infrared radiation emitted by an object as an electrical signal, a logarithmization circuit to which a detection signal of the infrared detector is supplied, and a logarithmization circuit that detects the infrared radiation of an object as an electrical signal. said A/D converter for converting the output signal of the circuit into a digital value; and storage means for storing the correlation between the temperature of the infrared ray emitting object and the output signal of the logarithmization circuit as digital data;
The present invention is characterized in that the temperature data in the storage means is read out using the output signal of the /D converter.

[Operation] In the present invention, the detection signal of the infrared detector is logarithmized by a logarithmization circuit, and the logarithmized signal is converted into a digital value by an A/D converter. Using the digital signal, digital data representing the correlation between the temperature and the output of the logarithmization circuit is read out from a storage means in which digital data is stored in advance.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figure is a block diagram showing one embodiment of a linearizer of an infrared temperature detection device according to the present invention.

In FIG. 1, radiated infrared rays from a reference blackbody furnace and from an observation object are alternately introduced into an infrared detector 1.

The detection signal of the infrared detector is amplified by a preamplifier 2, and a clamp circuit 3 clamps the infrared detection signal of the measurement object to the detection level of the reference infrared rays emitted by the reference blackbody furnace, and sets it to the absolute temperature T of the measurement object. I am getting a corresponding signal. The signal is sent to an A/D converter 5 via a logarithmic amplifier 4 and converted into a digital signal. In the read-only memory 6, a pre-stored temperature value is read out using this digital signal as an address signal. The read temperature value is sent to the display 7 and displayed as a numerical value.

In the above configuration, the logarithmic amplifier 4 is, for example, a logarithmic amplifier using a chip-type integrated circuit, and the introduced signal has a signal strength-temperature characteristic that is approximately proportional to the fourth power of the absolute temperature, as described above. signal (see FIG. 2(a)).

By logarithmizing the = 3- detection signal of the infrared detector using the logarithmic amplifier 4, the characteristic curve shown in Fig. 2 (a) has a linear correlation with the absolute temperature as shown in Fig. 2 (b). The characteristic curves are close to each other.

As shown by the broken line in FIG. 3, the read-only memory 6 includes:
A table representing this characteristic curve is stored. Third
In the figure, the vertical axis (left) indicates the output of the logarithmic amplifier 4, the right vertical axis indicates the output converted into a digital value (rooOJ to rFFFJ) by the 12-bit A/D converter 5, and the horizontal The axis is read-only memory 6 r
It shows the temperature values stored in addresses from ooOJ to "FFF".

Now, for example, when observing an object with a known temperature (T+°K), the output of the infrared detector is Vl, and the output of the logarithmic amplifier 4 which logarithms this is 10111V+, which is further digitally converted into A/ The output of D converter 5 is r6B6
If it is J, then this "6B6J is sent as it is to the read-only memory 6 as an address signal, so the temperature value r666J stored in advance at address r6B6J of the read-only memory is read out. The display 7 displays this "6B6J".
666'', the temperature T1 of the object is displayed numerically.

Similarly, when observing an object whose temperature is unknown, the output of the infrared detector is 2, and the output of the logarithmic amplifier 4 is too V.
2. If the output of the A/D converter 5 is r8A4J, the temperature value r99AJ is read from the address r8A4J of the read-only memory 6, and the display value on the display 7 based on this temperature value is T2, indicating that the unknown object It immediately turns out that the temperature of is T2.

Note that the above-mentioned embodiments are merely examples, and the present invention can be modified in many ways. For example, the read-only memory 6 has an A/D
storing data in the form of a correction amount from the output value of the converter 5;
The correction value read from the read-only memory 6 and the A/D
The correct conversion output may be obtained by adding the outputs of the converters 5.

In this way, the number of bits of data stored in the read-only memory 6 can be reduced, and memory capacity can be saved.

Furthermore, it goes without saying that two-dimensional temperature information can be obtained by installing an optical scanning means in front of the detector 1 and scanning the measurement points.

[Effects of the Invention] As is clear from the above description, according to the present invention, the linearizer of the infrared temperature detection device is equipped with a logarithmization circuit that logarithms the detection output of the infrared detector, and a logarithmization circuit that logarithms the detection output of the infrared detector, and digitalization of the logarithmized signals. By constructing an A/D converter that converts into a value and a read-only memory that is addressed by the digital signal, the circuit structure is simplified compared to conventional polygonal line approximation circuits, and in particular, the logarithmization circuit can be integrated on a single chip. If a circuit is used, the number of adjustment points in the circuit can be significantly reduced and the adjustment can be simplified.

Furthermore, since the dynamic range of the infrared detection signal is suppressed by using the logarithmization circuit, the A/D converter 5
The number of bits required is also small.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the linearizer of the infrared temperature detection device according to the present invention, FIG. 2 is a diagram showing the relationship between the output of the infrared detector and temperature, and FIG. 3 is for explaining the operation. This is a diagram. 1...Infrared detector, 2...Preamplifier, 3...
Clamp circuit, 4... Logarithmization circuit, 5... A/D converter, 6... Read only memory, 7... Display device. Patent applicant: JEOL Ltd. Ai Foundation

Claims (1)

[Claims] An infrared detector that detects the infrared radiation of an object as an electrical signal, a logarithmization circuit to which the detection signal of the infrared detector is supplied, and an A/D converter that converts the output signal of the logarithmization circuit into a digital value. , storage means storing the correlation between the temperature of the infrared ray emitting object and the output signal of the logarithmization circuit as digital data, and reading out the temperature data of the storage means according to the output signal of the A/D converter. A linearizer for an infrared concentration detection device characterized by: