JP2006292488A - Apparatus for measuring temperature distribution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for measuring temperature distribution, capable of efficiently removing noise due to high amplification of an infrared sensor array, having a plurality of elements and performing accurate detection. <P>SOLUTION: The temperature distribution measuring apparatus is provided with a plurality of thermopile elements 121 for detecting the distribution of infrared rays; a lens 11 for condensing light from a detection range; and an amplifying part 14 for amplifying detected signals. The amplifying part 14 performs amplification, while removing noise by acquiring filter passage signals, by passing the detection signals through a high-pass filter 142a and subtracting the filter passage signals from the detected signals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature distribution measuring apparatus that detects infrared rays with a plurality of elements and measures temperature in a distribution.

In the conventional technique, the output voltage of the light receiving element is amplified by the first amplification unit, the output voltage of the reference temperature element is amplified by the second amplification unit, and two amplified signals are input to the differential amplification unit. Differential amplification is performed (for example, refer to Patent Document 1).
JP 2003-92177 A

  However, conventionally, since the gain is high and the impedance of the sensor itself is high, there is a problem that noise and the like are amplified.

  The present invention has been made paying attention to the above-mentioned problems, and its object is to efficiently remove noise due to high amplification of an infrared sensor array having a plurality of elements and to detect temperature distribution accurately. Is to provide.

  In order to achieve the above-described object, in the present invention, in a temperature distribution measuring apparatus including a plurality of elements that detect infrared rays in a distributed manner, a lens that collects light from a detection range, and an amplification unit that amplifies a detection signal. The amplifying unit uses a detection signal that has passed through a high-pass filter as a filter passing signal, and subtracts the filter passing signal from the detection signal to amplify while removing noise.

  Therefore, in the present invention, noise due to high amplification of an infrared sensor array having a plurality of elements can be efficiently removed and detected with high accuracy.

  Embodiments for realizing the temperature distribution measuring apparatus of the present invention will be described below based on examples.

  First, the structure will be described.

  FIG. 1 is a block diagram of the temperature distribution measuring apparatus according to the first embodiment. FIG. 2 is a circuit configuration diagram of the thermopile unit of the temperature measuring apparatus according to the first embodiment.

Example 1 is an example used for measuring the temperature distribution in a vehicle.
The temperature distribution measuring apparatus according to the first embodiment mainly includes a thermopile module 1 and a microcomputer 2.
The thermopile module 1 mainly includes a lens 11, a thermopile unit 12, a scanning unit 13, an amplifying unit 14, and a reference temperature element 15.
The lens 11 is disposed in front of the thermopile unit 12 and condenses infrared rays emitted from the detection area 3 on the thermopile unit 12.
The thermopile unit 12 has thermopile elements (corresponding to elements) 121 for detecting infrared rays arranged in a matrix.
The scanning unit 13 selects an output signal from the thermopile element 121 by an address signal.

As shown in FIG. 2, the amplifying unit 14 includes an operational amplifier OP1, a minus input unit 141, a plus input unit 142, an adjustment unit 143, and a negative feedback unit 144.
The minus input unit 141 inputs the input signal from the thermopile unit 12 to the minus terminal of the operational amplifier OP1 via the resistor R1.
The plus input unit 142 inputs the input signal from the thermopile unit 12 to the plus terminal of the operational amplifier OP1 through the high pass filter 142a including the capacitor C1 and the resistor R3.
The adjustment unit 143 connects the reference voltage obtained from the reference temperature element 15 between the high-pass filter 142a and the operational amplifier OP1 via the resistor R4.
The negative feedback unit 144 connects the output of the operational amplifier OP1 via the resistor R2 between the resistor R1 and the negative terminal of the operational amplifier OP1.

The reference temperature element 15 outputs a reference voltage that is an output indicating the reference temperature.
The reference temperature element 15 may measure an object at a constant temperature by the thermopile element 121 or may output a constant voltage.
The microcomputer 2 controls the thermopile unit 12, processes output signals, and performs calculations, and outputs data and control outputs to automobile equipment and communication lines.
The microcomputer 2 includes a signal output unit 21 and a multiplexer 22.

The signal output unit 21 outputs an address signal in a matrix arrangement of the thermopile elements 121 to the scanning unit 13 at a predetermined timing.
The multiplexer 22 receives the output signal from the amplifying unit 14 and performs selection / switching of the thermopile elements 121 in a matrix.

Next, the operation will be described.
[Noise removal]
In the temperature distribution measuring apparatus according to the first embodiment, the output signal of the thermopile element 121 selected by the scanning unit 13 based on the address signal from the signal output unit 21 of the microcomputer 2 becomes the input signal in the amplifying unit 14 of FIG. (See FIG. 3 (a)).

One of the input signals is a negative input of the operational amplifier OP1 through the resistor R1. The other is adjusted in potential by the reference voltage via the high-pass filter 142a and becomes a positive input of the operational amplifier OP1 (see FIG. 3B).
The operational amplifier OP1 is provided with a negative feedback unit 144 to perform differential inversion amplification. That is, the high frequency noise component of FIG. 3B is subtracted from the waveform of FIG. Therefore, the noise component is not amplified unlike the conventional case.
Thereby, the accuracy of temperature measurement improves compared with the past.

Further, this action will be described in other words.
The output voltage of the operational amplifier is Vo, the reference voltage is Vref, the values of the resistors R1 to R4 are R1 to R4, the value of the capacitor C1 is C1, the operator is S, i is a variable, and the symbol sequence means multiplication Then, {R1Vo + R2Vi} / {R1 + R2} is input to the negative input of the operational amplifier OP1. The output of the high-pass filter 142a is input to the positive input of the operational amplifier OP1. This is {SC1R4Vi + (1 + SC1R3) Vref} / {1 + SC1 (R3 + R4)}.
Therefore, the output of the operational amplifier OP1 is as follows.

Here, assuming that R1 = R3 and R2 = R4, in Equation A, Vo = −R2Vi / R1 + (R1 + R2) Vref / R1 at 0 Hz, and Vo = Vref at high frequencies.
In FIG. 3, since the level changes abruptly when the element is switched, the differential waveform by the high-pass filter 142a is input to the plus input of the operational amplifier OP1, and the output changes greatly. When the differential component disappears, the noise component is eliminated.

Next, the effect will be described.
In the temperature distribution measuring apparatus according to the present embodiment, the following effects can be obtained.
(1) In a temperature distribution measuring apparatus including a plurality of thermopile elements 121 that detect infrared rays in a distributed manner, a lens 11 that collects light from a detection range, and an amplification unit 14 that amplifies a detection signal, the amplification unit 14 includes: The detection signal that has passed through the high-pass filter 142a is used as a filter-passing signal, and the filter-passing signal is subtracted from the detection signal to amplify the noise while removing the noise. It can be removed and detected accurately.

  (2) The amplifying unit 14 includes an operational amplifier OP1 provided with a negative feedback unit 144, a negative input unit 141 that uses a detection signal as a negative input of the operational amplifier OP1, and a positive input of the operational amplifier OP1 that passes the detection signal through the high-pass filter 142a. And the adjustment unit 143 that sets the potential of the positive input of the operational amplifier OP1 to a predetermined potential, so that noise due to high amplification of the infrared sensor array having a plurality of elements can be efficiently removed and detected accurately. it can.

The operational effects of the first embodiment will be further described.
The temperature distribution measuring apparatus according to the first embodiment is a scan type, and performs detection by switching elements. In this case, if a conventional low-pass filter for removing noise is used for the output or input that amplifies the noise, the time constant becomes longer and the signal becomes dull because the noise is taken. The switching speed must be slowed down. In the temperature distribution measuring apparatus according to the first embodiment, noise can be removed and amplified without slowing down the element switching speed.

(Other embodiments)
As described above, the embodiment of the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the embodiment, and design changes and the like within the scope of the invention are not limited. Even if it exists, it is included in this invention.

  The circuit configuration of the amplifying unit may be different, or what is shown by the mathematical expression in the first embodiment may be performed on software.

It is a block diagram of the temperature distribution measuring apparatus of Example 1. FIG. 3 is a circuit configuration diagram of a thermopile unit of the temperature measuring device according to the first embodiment. It is explanatory drawing which shows the waveform processing example of the temperature measuring apparatus of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermopile module 11 Lens 12 Thermopile unit 121 Thermopile element 13 Scan part 14 Amplification part 141 Negative input part 142a High pass filter 142 Plus input part 143 Adjustment part 144 Negative feedback part 15 Reference temperature element 2 Microcomputer 21 Signal output part 22 Multiplexer 3 Detection area

Claims (2)

A plurality of elements that detect infrared rays in a distributed manner;
A lens that collects light from the detection range;
An amplifying unit for amplifying the detection signal;
In a temperature distribution measuring device comprising:
The amplification unit is
The detection signal that has passed through the high-pass filter is used as the filter passing signal,
Subtracting the filtered signal from the detection signal and amplifying it while removing noise,
A temperature distribution measuring device characterized by that. In the temperature distribution measuring apparatus according to claim 1,
The amplification unit is
An operational amplifier with a negative feedback section;
A negative input section that uses the detection signal as a negative input of the operational amplifier;
A positive input unit that passes the detection signal through a high-pass filter and serves as a positive input of the operational amplifier;
An adjustment unit for setting a positive input potential of the operational amplifier to a predetermined potential;
With
A temperature distribution measuring device characterized by that.

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