JPH07198497A - Room-temperature clamp-level correction circuit of infrared image apparatus - Google Patents

Abstract

PURPOSE:To provide the room temperature clamp level correction circuit, of an infrared image apparatus, in which room temperature can be corrected precisely. CONSTITUTION:A DC reproducing device 2 superposes a reference-voltage signal on a sensor signal which has been amplified by an amplifier 1. An offset circuit 3 adds or subtracts an offset-value input front a D/A converter 7 to or from a referencevoltage-signal level which has been superposed in the output of the DC reproducing device 2. An A/D converter 4 digitizes the output signal of the offset circuit 3. A room-temperature-data detector 8 detects level data which has been offset-operated from the output signal of the A/D converter 4. A CPU 6a compares room-temperature data which is output by a room- temperature sensor 5 with level data which is output by the room-temperature- data detector 8 regarding their magnitude relationship, and it outputs, to the D/A converter 7, an offset value which is required to make both coincide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room temperature clamp level correction circuit for an infrared imager.

[0002]

2. Description of the Related Art In temperature measurement using infrared rays radiated by an object, the internal temperature of an infrared imager is normally used as a reference temperature. For example, as shown in FIG. Although the difference between the level and the minimum temperature level is constant, the temperature inside the apparatus, which is the room temperature level, varies depending on the environment in which it is used. Therefore, conventionally, for example, a room temperature clamp level correction circuit as shown in FIG. 3 is provided.

In FIG. 3, an amplifier 1 amplifies a sensor signal, which is a detection signal of an infrared sensor, with a constant amplification degree up to an input rated amplitude of an A / D converter 4. The DC regenerator 2 is set to 1 when the infrared sensor scans the inner wall surface of the camera.
A constant value reference voltage of 2 volts or 2 volts is generated, superposed on the sensor signal amplified and output by the amplifier 1, and output to the offset circuit 3.

On the other hand, the room temperature sensor 5 detects the temperature of the inner wall surface of the camera. The CPU 6b applies a predetermined predicted value to the detected room temperature of the room temperature sensor 5 to obtain an offset value corresponding to the room temperature. This offset value is the D / A converter 7
Is converted into an analog signal and applied to the offset circuit 3.

Therefore, the offset circuit 3 adds or subtracts the offset value input from the D / A converter 7 to the reference voltage level in the output of the DC regenerator 2 and clamps the reference voltage level to a predetermined value. .

As a result, the output of the offset circuit 3 is A
The / D converter 4 converts the signal into, for example, a 12-bit digital signal and outputs it as a digitized sensor signal to the outside of the figure, but the temperature of the measurement object is measured with reference to the reference voltage level clamped to a predetermined value. You can do it.

[0007]

However, in the conventional method for obtaining the offset value with the predicted value, it is difficult to perform accurate room temperature correction, and it is difficult to improve the measurement accuracy.

An object of the present invention is to provide a room temperature clamp level correction circuit for an infrared imaging device which enables accurate room temperature correction.

[0009]

In order to achieve the above object, the room temperature clamp level correction circuit of the infrared imaging device of the present invention has the following configuration. That is, the room temperature clamp level correction circuit of the infrared imaging device of the present invention includes a DC regenerator that superimposes a reference voltage signal on a sensor signal; and an offset value that is input, the superposed reference voltage signal that is being output from the DC regenerator. An offset circuit for adjusting the level, and an A / D for digitizing the output signal of the offset circuit
A converter; a detector for detecting the level data subjected to the offset operation from the output signal of the A / D converter;
A room temperature sensor; and a control circuit that compares the room temperature data output from the room temperature sensor with the level data and forms and outputs the offset value necessary for matching the two. It is a thing.

[0010]

Next, the operation of the room temperature clamp level correction circuit of the infrared imaging apparatus of the present invention constructed as described above will be described. In the room temperature clamp level correction circuit of the infrared imaging device of the present invention, the offset level data that is subjected to the offset operation is detected from the output digitized sensor signal, and the offset value necessary for matching both is formed from the level data. A feedback circuit is provided.

Therefore, since the fluctuation of the reference voltage level can be suppressed by using the correct offset value according to the actual room temperature, the measurement accuracy can be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a room temperature clamp level correction circuit of an infrared imaging device according to an embodiment of the present invention. In FIG. 1, FIG.
The same components and parts are designated by the same reference numerals and names. Hereinafter, the description will focus on the part relating to the present invention.

The room temperature data detector 8 detects, from the digitized sensor signal output from the A / D converter 4, level data indicating the reference voltage level offset by the offset circuit 3 as described above.

The CPU 6a compares the magnitude relation between the room temperature data output by the room temperature sensor 5 and the level data output by the room temperature data detector 8 and forms and outputs an offset value required to match the two.

This offset value is D / A as in the conventional case.
It is converted into an analog signal by the converter 7 and given to the offset circuit 3.

As a result of repeating the above-described operation of the feedback circuit, the level data contained in the digitized sensor signal output from the A / D converter 4 is stabilized without being affected by room temperature fluctuations. Therefore, the measurement accuracy can be improved.

[0017]

As described above, in the room temperature clamp level correction circuit of the infrared imaging apparatus of the present invention, the offset-processed level data is detected from the output digitized sensor signal, and both are detected from the room temperature data. Since the feedback circuit that forms the offset value necessary for matching is provided, it is possible to suppress the fluctuation of the reference voltage level by using the correct offset value according to the actual room temperature, and it is possible to improve the measurement accuracy. .

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a room temperature clamp level correction circuit of an infrared imaging device according to an embodiment of the present invention.

FIG. 2 is a relationship diagram between an output signal of an infrared sensor and a room temperature level.

FIG. 3 is a configuration block diagram of a conventional room temperature clamp level correction circuit.

[Explanation of symbols]

 1 Amplifier 2 DC Regenerator 3 Offset Circuit 4 A / D Converter 5 Room Temperature Sensor 6a CPU 7 D / A Converter 8 Room Temperature Data Detector

Claims (1)

[Claims] 1. A D for superimposing a reference voltage signal on a sensor signal.
A C regenerator; an offset circuit that adjusts an input offset value to the superimposed reference voltage signal level in the output of the DC regenerator; and an A / D converter that digitizes the output signal of the offset circuit. A detector for detecting the level data obtained by performing the offset operation from the output signal of the A / D converter; a room temperature sensor; and a room temperature data output from the room temperature sensor and a level relationship of the level data to compare the two. A room temperature clamp level correction circuit for an infrared imaging device, comprising: a control circuit that forms and outputs the offset value necessary for matching.