JPH06249712A - Pyroelectric infrared sensor and device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pyroelectric infrared sensor and device having advantages such as low cost, small size, and high sensitivity. In the amplified signal processing circuit 13 for amplifying the output of the pyroelectric infrared detector 25, a circuit having a temperature dependency opposite to the temperature dependency of the pyroelectric effect of the pyroelectric body is the amplified signal processing circuit 13. Is a pyroelectric infrared sensor that can output a detection signal that does not depend on the temperature environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared sensor and device using a pyroelectric infrared sensor.

[0002]

2. Description of the Related Art Conventionally, there are two types of devices for measuring the temperature distribution in space using infrared rays. One of them is a method of obtaining a temperature distribution using a two-dimensional quantum solid-state imaging infrared sensor. The other is a method of obtaining a spatial temperature distribution using a pyroelectric sensor, which is disclosed in, for example, Japanese Patent Laid-Open No. 64-8839.
1, JP-A-57-185695, JP-A-2-18375
2. As described in JP-A-2-196932 and the like, a single pyroelectric sensor is used to mechanically scan in the vertical and horizontal directions to detect the input energy in each direction and obtain the temperature distribution. Is the way.

[0003]

By the way, in the former quantum type solid-state imaging infrared sensor, the measurement temperature accuracy and resolution are high, but since the sensor part needs to be cooled, it becomes expensive, and it becomes difficult to use it for household appliances. There is a problem that it is not suitable for use.

On the other hand, the latter one using the pyroelectric sensor is
Due to the problem of low sensor sensitivity, the complexity of the mechanism, and the complexity of signal processing, there is a problem of low spatial resolution and temperature resolution.

On the other hand, the pyroelectric sensor has a drawback that its temperature dependency is considerably large. In particular, there is an adverse effect due to heat generated by the amplifier circuit that amplifies the output of the sensor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional sensor, and an object thereof is to provide a pyroelectric infrared sensor and device having advantages such as low cost, small size, and high sensitivity. .

[0007]

According to the present invention, in an amplified signal processing circuit for amplifying the output of a pyroelectric infrared detector, the pyroelectric effect has a temperature dependence opposite to that of the pyroelectric effect. This is a pyroelectric infrared sensor that can output a detection signal that does not depend on the temperature environment by using the circuit included in the amplified signal processing circuit.

Further, the present invention comprises a pyroelectric infrared detecting section provided in a plurality of arrays, the above-mentioned amplified signal processing circuit, and chopping means for intermittently blocking infrared rays incident on the detecting section. It is a pyroelectric infrared sensor device.

[0009]

In the present invention, the amplified signal processing circuit has a circuit having a temperature dependence opposite to the temperature dependence of the pyroelectric effect of the pyroelectric body, and cancels the temperature dependence of the pyroelectric body. As a result, a signal having no temperature dependence is output.

Further, according to the present invention, a chopping section for intermittently blocking infrared rays incident on the infrared detecting section,
Since the infrared detecting unit is provided with a rotating unit that continuously rotates, temperature measurement can be realized with higher sensitivity.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of a temperature distribution measuring apparatus used in an embodiment of the present invention. A pyroelectric infrared array sensor 1 having a plurality of light receiving portions arranged in a line.
1 and an infrared lens 12 for condensing infrared rays on the pyroelectric sensor array 11 on the front surface of the array sensor 11, a photocoupler 14 for detecting a chopping state is provided on a sensor rotating unit 10. There is. The photocoupler 14 is composed of a photodiode, a light emitting element such as a phototransistor, and a light receiving element.

On the other hand, the sensor rotating unit 10 is mechanically connected to the rotation starting unit 30 via the transmission 31. Further, a cylindrical chopper 40 having a chopper window portion 41 for intermittently blocking the infrared rays incident on the infrared lens 12 is provided. The chopper 40 is also the rotation starter 3
Mechanically connected to 0. The chopper 40 is provided with a reflecting plate 42 for reflecting the light emitted from the light emitting element of the photocoupler 14 to the light receiving element. Each of the mechanical units 30, 3
1, 40, 10 and the like are sensor supports 2 having a window portion 21.
Supported by 0. Further, the sensor support 20 is provided with a light receiving element 22 for detecting the rotation direction of the sensor rotating portion 10.

FIG. 2 is an external view of the chopper 40 and a view in which the cylindrical portion is opened. The chopper shown in the figure opens and closes three times in one rotation, but if the opening is set to N,
It enables the chopper N times. Chopper 40
In addition to the chopper window portion 41, a reflection plate 42 is provided at the same interval as the chopper window portion so that the light emitted from the light emitting element of the photocoupler 14 is reflected when the chopper window portion crosses the front surface of the sensor rotating portion. The light is reflected by the plate 42 and received by the light receiving element which is a constituent element of the photocoupler 14, thereby enabling detection.

FIG. 3 is a partially cutaway perspective view of a measuring device having a structure similar to that of the temperature distribution measuring device shown in FIG. 1 and shows a schematic structure thereof.

Now, when the rotation starter 30 is driven in a state where the infrared sensor 11 is in the form of an array and the major axis direction thereof is installed in the vertical direction, the chopper 40 continuously rotates,
Since the infrared rays incident on the infrared lens 12 are intermittently blocked, the distribution of radiant heat in the column in the direction facing the lens 12, that is, the temperature distribution can be measured. The measurable spatial range depends on the angle of view of the lens 12 and the sensor size.

At the same time, the transmission 31 causes the sensor rotating part 1 to rotate.
0 is also continuously rotated at a constant rotation angular velocity. That is, the sensor rotation unit is rotated forward to scan the direction in which the sensor and the lens are facing, while driving the chopper to measure the temperature distribution on the next surface. After the measurement, by connecting the vertical temperature distributions in each direction by electrical signal processing, a two-dimensional inversion temperature distribution of space is obtained.

After the measurement of the final body surface direction is completed, the motor is rotated in the reverse direction to return to the initial body surface direction, and a standby state for the next measurement is created.

The device shown in the above example was mounted on the upper wall surface of a room of about 6 × 6 m, and the temperature distribution in the whole room was measured.
Note that the number of sensor light-receiving units was 10, and the number of left and right rotation steps was 30. The spatial temperature distribution at this time is 10
X30 matrix S00, 01, S00, 02, ---, S00, 10 S01, 01, S01, 02, ---, S01, 10 ----- --- --- --- --- It can be expressed by S30, 01, S30, 02, --- S30, 10. That is, if the number of sensor light receiving portions is n and the angle at which the sensor portion rotates in one open / close chopper is θ degrees, the data addresses are, for example, S01, S02,
---, S0n, data is stored for each step, the measurement is performed by rotating the direction forwards m times, and the data addresses at that time are Sm1, Sm2, ---, Smn. Therefore, it was possible to detect the presence or absence of persons in the room and the number of persons in the room by determining the distribution state of each measured temperature of 30 ° C. or higher. Here, it is difficult to discriminate between the case where there is one person near the measuring device and the case where there are a plurality of persons at one place in the distance, but it is difficult to distinguish with one measurement temperature distribution. Therefore, it was possible to determine empirically. Furthermore, the amount of activity of the occupants was able to be qualitatively determined.

By introducing the fuzzy reasoning using the membership function for the above judgment, more accurate judgment was possible.

FIG. 4 shows a block diagram of electric signals of the measuring device. The I / O port 17 has a motor 5 and
CP with built-in clock generator, calculator and memory
U16 is electrically connected. The signal from the infrared array sensor 1 is amplified by the filter 12 and the amplifier 13, and then selected by the multiplexer 14. The signal of the selected element is processed by the A / D converter 15 and the CPU
16 is input. The sensor output is obtained by the rotation of the sensor rotation unit 3 and the continuous rotation of the chopper 4 by the rotation of the motor 5. In addition, the signals from the position sensor 18 such as the photocoupler 13, the reflector 42, and the light receiving element 22 are also C
It is input to the PU 16.

By the way, FIG. 5 shows a circuit of the light receiving portion 25 and the amplifier 13 of the infrared array sensor 1 of FIG. The amplifier 13 has an operational amplifier 26 and a feedback resistor R 27. The voltage generated from the light receiving unit 25 is input to the operational amplifier 26.

FIG. 6 is a graph showing the temperature dependence of the pyroelectric body of the light receiving section 25. The horizontal axis represents the environmental temperature of the pyroelectric body, and the vertical axis represents the sensitivity (output voltage) of the pyroelectric body.

On the other hand, FIG. 7 shows the resistance R of the amplifier 13.
27 is a temperature-dependent characteristic of No. 27. The horizontal axis is the environmental temperature of the resistance,
That is, it is the environmental temperature of the pyroelectric body, and the vertical axis represents the resistance R 27.
Is the resistance value of. Therefore, as is apparent from the circuit of FIG. 4, the output Vout has a flat temperature characteristic as a whole as shown in FIG. That is, there is no temperature dependence. The amplification factor of the FET of the operational amplifier 26 hardly changes depending on the pyroelectric environment temperature.

The element for canceling the temperature-dependent characteristic of the pyroelectric body is not limited to the above resistance and may be another element as long as it has such an action.

Further, the infrared detecting portion of the present invention is not limited to the one that rotates, but may be another type such as a fixed type.

[0027]

As is apparent from the above description,
The present invention relates to an amplified signal processing circuit for amplifying the output of a pyroelectric infrared detector, wherein a circuit having a temperature dependence opposite to the temperature dependence of the pyroelectric effect of a pyroelectric body is the amplified signal processing circuit. When used, it has the advantage that it can output a detection signal that does not depend on the temperature environment.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a pyroelectric infrared sensor device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a chopper of a pyroelectric infrared sensor device according to an embodiment of the present invention.

FIG. 3 is a schematic perspective view of a pyroelectric infrared sensor device according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of an electric circuit portion according to an embodiment of the present invention.

FIG. 5 is an electric circuit diagram centering on an amplifier according to an embodiment of the present invention.

FIG. 6 is a graph showing the temperature dependence of the pyroelectric body.

FIG. 7 is a graph showing temperature dependence characteristics of resistance of an amplifier according to an exemplary embodiment of the present invention.

FIG. 8 is a graph showing the temperature dependence of the detection output of the pyroelectric infrared sensor according to the example of the present invention.

[Explanation of symbols]

 1 Infrared Array Sensor 3 Sensor Rotating Part 4 Chopper 5 Motor 10 Sensor Rotating Part 11 Infrared Sensor 12 Infrared Lens 13 Amplifier 14 Photocoupler 16 CPU 18 Position Sensor 20 Support 21 Support Window 22 Light-receiving Element 25 Light-receiving 26 Operational Amplifier 27 Resistor 30 Rotation Starting Section 31 Transmission 40 Chopper 41 Chopper Window 42 Reflector

Claims (2)

[Claims] 1. An amplified signal processing circuit for amplifying an output of a pyroelectric infrared detection unit, wherein the circuit having a temperature dependence opposite to that of a pyroelectric effect of a pyroelectric body is the amplified signal processing circuit. A pyroelectric infrared sensor characterized by being capable of outputting a detection signal independent of the temperature environment by being used for. 2. A pyroelectric infrared detector provided in a plurality of arrays, an amplified signal processing circuit according to claim 1, and chopping means for intermittently interrupting infrared light incident on the detector. A pyroelectric infrared sensor device characterized by being provided.