JPH08122156A - Pyroelectric infrared ray element and infrared ray sensor - Google Patents

Abstract

PURPOSE: To suppress a thermal crosstalk generated between a plurality of light reception electrodes, eliminate the fading of an infrared ray image and constantly and accurately sense a measurement space by outputting electrically and mutually opposite signals from an element adjacent to a piezoelectric element for the output from the piezoelectric element when infrared rays enter one piezoelectric element. CONSTITUTION: When infrared rays 25 enter a light reception electrode 21, sensor output is obtained. The sensor output is amplified by an amplification circuit 24, where an output is generated at a light reception electrode part where no infrared rays are applied by the propagation of heat from the adjacent light reception electrode and thermal crosstalk. Then, sensor output which is obtained after infrared rays are applied generates sensor output opposite and inverse phases corresponding to the sensor output via an inverted amplification circuit 27. As a result, the sensor output from a light reception electrode which does not emit infrared rays yet becomes the sum of the output by thermal crosstalk and that in inverse phase which is opposite to sensor output from the adjacent light reception electrode, namely almost 0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared element and an infrared sensor capable of obtaining a sensor output in consideration of thermal influence between pyroelectric elements.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for security and air-conditioning control by detecting the presence or absence of people in a room and the amount of activity. That is, infrared rays are generated using an infrared sensor for the purpose of detecting the human body by detecting the infrared rays emitted from the human body and using the signal for controlling environmental control devices such as air conditioners and lighting equipment and crime prevention systems. Devices for detecting sources have come into use.

Two types of infrared sensors are known: a quantum type sensor that captures infrared rays as photons, and a thermal type sensor that utilizes the change in the physical properties of the element caused by the temperature rise of the element due to the absorption of infrared light. However, since the former usually requires cooling with liquid nitrogen or the like, a thermal sensor is generally used. Of the thermal sensors, the pyroelectric infrared sensor has a higher sensitivity than other sensors, so it is suitable for infrared source detection, but the pyroelectric infrared sensor basically detects infrared changes. Therefore, when trying to detect a stationary infrared ray generation source, it is necessary to devise that infrared rays intermittently enter the sensor light receiving part by some method, and usually a chopper such as a disc with a slit or a flat plate is used. By rotating or vibrating, infrared rays are intermittently incident (chopping).

FIG. 6 is a schematic view showing an electrode pattern of a pyroelectric element in a conventional pyroelectric infrared sensor.
6A shows the front side of the pyroelectric substrate, and FIG. 6B shows the back side of the pyroelectric substrate. In the above pyroelectric infrared sensor,
A light receiving electrode 72 for receiving infrared rays and a compensating electrode 74 corresponding to each of the light receiving electrodes 72 are formed on the surface 71 of the pyroelectric substrate. A counter electrode 77 is formed on the back surface 76 of the electric substrate corresponding to the light receiving electrode 72 and the compensation electrode 74. By irradiating infrared rays only to the light receiving electrodes 72 on the surface 71 of the pyroelectric substrate, a potential difference occurs, and the infrared source can be detected by detecting the voltage.

[0005]

The pyroelectric infrared sensor for detecting infrared rays in this manner is capable of detecting the heat source by examining the temperature distribution in the measurement space. In the above conventional one, for example, four infrared ray receiving electrodes 72a
In the state where four independent detection areas are formed by ~ 72d, if the infrared ray from the human body, which is the infrared ray generation source, enters only the light receiving electrode 72b, the output signal from the light receiving electrode 72b should not be output. I won't. However, in reality, the incident heat when infrared rays are received by the infrared ray receiving electrode 72b is conducted through the pyroelectric substrate 71 and is also conducted to the other infrared ray receiving electrodes 72a, 72c, 72d, and the temperature rises, There is a problem that these light-receiving electrodes cause polarization similar to that when infrared light is received, a potential difference is generated and output as an output signal, that is, thermal crosstalk occurs. FIG. 5 is a diagram showing the state of output at this time. Although infrared rays should be incident only on the light receiving electrode of 72b,
It can be seen that about 30% of the output signals are output to 2a and 72c, and about 10% of the output signals are output to the light receiving electrodes of 72d.

As described above, in the conventional sensor, the thermal crosstalk and the infrared rays are not incident, but the output is generated due to the heat propagation,
There are problems that the apparent output increases, the infrared image is blurred, and the position of the heat source cannot be detected accurately by making a large determination of the size of the heat source.

That is, when infrared rays are incident on a certain one light receiving electrode due to thermal crosstalk due to heat propagation between the light receiving electrodes of the pyroelectric element, an output is also generated from the light receiving electrode in the vicinity thereof, and the output of the space sensing. However, there is a problem in that it is not possible to accurately detect a heat generation object due to variations and errors.

The present invention has been made in consideration of the above problems, and in a pyroelectric infrared sensor, suppresses thermal crosstalk between a plurality of light receiving electrodes to eliminate blurring of an infrared image. The present invention provides a pyroelectric infrared sensor that always enables accurate sensing of a measurement space with little error.

[0009]

In the pyroelectric infrared device of the present invention, in a pyroelectric device in which polarization is generated by receiving infrared light, when infrared light is incident on a certain pyroelectric device, an output from the pyroelectric device is obtained. On the other hand, the output from the adjacent element can be corrected by causing the elements adjacent to the pyroelectric element to output electrically contradictory signals.

Further, the pyroelectric element is composed of one substrate.

Furthermore, it is preferable that the pyroelectric element is divided or a groove is formed between the elements.

Further, the pyroelectric infrared sensor of the present invention includes a light receiving electrode portion capable of receiving infrared rays on the surface of the pyroelectric element, a compensation electrode portion corresponding to the light receiving electrode portion, and the pyroelectric element. In a pyroelectric infrared sensor having a counter electrode at a position facing the light receiving / compensating electrode section on the back surface of
When an infrared ray is incident on a certain light receiving electrode portion, by causing an electrode adjacent to the light receiving electrode to output a signal that is electrically contradictory to the output from the light receiving electrode,
The output from the adjacent electrodes can be corrected.

Further, the pyroelectric infrared sensor of the present invention is
A light receiving electrode portion capable of receiving infrared rays on the surface of the pyroelectric element, a compensation electrode portion corresponding to the light receiving electrode portion, and a position on the back surface of the pyroelectric element facing the light receiving / compensating electrode portion. In a pyroelectric infrared sensor having a counter electrode, when infrared light is incident on a certain light-receiving electrode section, a sensor output from the light-receiving electrode is amplified by an operational amplifier and a resistor, and a reverse phase proportional to the sensor output is obtained. By outputting the signal of (1) from the electrode adjacent to the light receiving electrode, the influence of heat between adjacent elements can be suppressed and the sensor output can be corrected, which is a pyroelectric infrared sensor.

Furthermore, it is desirable that the signal output from the electrode adjacent to the light receiving electrode be a signal whose phase is shifted with respect to the sensor output from the light receiving electrode.

In other words, in a pyroelectric infrared element which is polarized by receiving infrared rays, when infrared rays are incident on a certain pyroelectric element, the elements adjacent to this pyroelectric element have electrically opposite phases. By outputting the electric signal in an amount commensurate with the output increase due to thermal crosstalk, the thermal crosstalk can be suppressed and the output increase of the element to which infrared rays are not incident can be suppressed. As a result, accurate heat source detection without crosstalk can be performed. Further, in a pyroelectric infrared sensor having a light receiving electrode, a compensating electrode, and a counter electrode, the sensor output generated when infrared light is incident on one certain light receiving electrode section is electrically connected from an electrode near the light receiving electrode. By outputting an electric signal of opposite phase, it is possible to suppress the sensor output rise from other electrodes due to heat conduction, to obtain an accurate and high-resolution infrared image, and to obtain an accurate temperature distribution. Is something that can be done. Furthermore, by using these pyroelectric infrared sensors, it is possible to obtain a two-dimensional temperature distribution with less variation and error, and to perform accurate heat source detection and human body detection.

As described above, by canceling the thermal crosstalk between the adjacent elements by the electrically opposite signals having opposite phases, it is possible to obtain an accurate temperature distribution with little variation and to accurately detect the heat source. It can be carried out.

[0017]

In the present invention, by using the above-mentioned pyroelectric infrared element, it is possible to suppress an increase in the output of the infrared non-irradiated area due to heat conduction between the adjacent elements,
Thermal crosstalk can be suppressed and an accurate output signal can be obtained.

Further, by using this pyroelectric infrared sensor, it is possible to prevent the sensor signal output from being generated from the light receiving electrodes in the vicinity due to the heat propagation from the electrodes receiving the infrared rays, thereby blurring the infrared image. Therefore, the measurement space sensing can be performed easily, accurately and highly reliably.

Further, it is possible to obtain an accurate sensor output which does not depend on the incidence of infrared rays on the near-field light receiving electrodes and which has few variations and errors. In particular, by suppressing thermal crosstalk, infrared intensity can be accurately output, high resolution can be achieved, and adjacent heat generating objects can be separated to perform accurate heat source detection and human body detection. You can

Thus, this pyroelectric infrared sensor is
Thermal crosstalk can be suppressed very easily, and by using this sensor, accurate and highly reliable heat source detection and human body detection can be easily performed at low cost. Therefore, by using the present invention, the pyroelectric infrared device and the infrared sensor, which are easily and highly accurately and highly reliable, effectively act.

[0021]

【Example】

(Embodiment 1) A pyroelectric infrared device according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the signal intensity and output on each of the light-receiving surfaces a to d of the pyroelectric infrared device of the present invention. FIG. 1A shows that only the pyroelectric-material light-receiving surface b emits infrared rays. It is an output when it is incident, and FIG. 1B is a sensor output after processing of the sensor signal. That is, in the pyroelectric elements a to d that are polarized by receiving infrared rays, when infrared rays are incident only on one pyroelectric element b, the output from the pyroelectric element b is shown in FIG. As described above, the elements a, c, and d adjacent to the pyroelectric element b output signals of electrically opposite phases. At this time, if a and c, which are closest to each other, output a signal having a reverse phase of about 30% with respect to b, d outputs a signal having a reverse phase of about 10%. On the other hand, the sensor output from the actual pyroelectric element is, as shown in FIG. 5, when infrared rays are incident only on the pyroelectric element b, due to thermal crosstalk due to heat conduction from the substrate, the pyroelectric element b The sensor output is about 30% from a and c, and about 10% from d. But here in Figure 1
As shown in (a), since output signals of opposite phases are output from a, c, and d, the output due to this thermal crosstalk is canceled. In this way, the sensor output after the correction processing is finally the infrared ray as shown in FIG. 1B due to the increase in the sensor output due to the thermal crosstalk and the output from the anti-phase signal from the infrared non-irradiation area. The sensor output is only on the incident light receiving surface b, and the sensor output is almost zero on the light receiving surfaces a, c, and d on which infrared rays are not incident. In the conventional pyroelectric element, due to the influence of thermal crosstalk, the thermal effect on the proximity element is large, and an inaccurate sensor output with large variations and errors is obtained, and accurate heat source detection cannot be performed. However, by using the present invention, a signal that is inconsistent with the original sensor signal is output from the light receiving surface that is the infrared non-incident surface, so that there is no variation or error as shown in FIG. An independent, accurate sensor output signal can be obtained.

In this way, the signal output contradictory to the sensor output is generated from the region close to the light receiving surface on which the infrared rays are incident, so that the thermal crosstalk generated between the plurality of pyroelectric elements is suppressed. Therefore, it is possible to obtain an accurate sensor measurement output without variations and errors, and it is possible to perform accurate heat source detection and human body detection. Furthermore, because thermal crosstalk is canceled, an accurate sensor signal output can be obtained for the amount of infrared incident light, so blurring of the infrared image can be suppressed, reliability is high, and the human body is highly accurate. It is possible to perform detection and position detection.

As described above, according to the present embodiment, by generating an anti-phase output with respect to the sensor output from the infrared non-irradiation area, it is possible to easily, accurately and accurately perform thermal crosstalk. It is possible to obtain a pyroelectric infrared device capable of producing a sensor output that does not depend on the above and has no variations or errors.

The pyroelectric infrared device of this embodiment is 1
It may be composed of one substrate, or may be a pyroelectric infrared element in which the pyroelectric element is divided or a groove is formed between the elements.

(Embodiment 2) A pyroelectric infrared sensor according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram for explaining an electric circuit of the pyroelectric infrared sensor of the present invention. A light receiving electrode portion 21 capable of receiving infrared rays on the surface of the pyroelectric element 20.
And a compensation electrode portion 22 corresponding to the light receiving electrode portion 21,
In a pyroelectric infrared sensor having a counter electrode 23 at a position facing the light receiving / compensating electrode portion on the back surface of the pyroelectric element 20, when infrared rays 25 enter the light receiving electrode 21, a sensor output is obtained. This sensor output is amplified by the amplifier circuit 24. Here, in the light receiving electrode portion where infrared rays are not incident, an output is generated due to heat propagation and thermal crosstalk from the adjacent light receiving electrodes. Therefore, next, the sensor output obtained by the incidence of the infrared ray generates a sensor output of an opposite phase corresponding to the sensor output via the inverting amplifier circuit 27 with respect to the adjacent output. By doing so, the sensor output from the light receiving electrode that has not been irradiated with infrared rays becomes the sum of the output due to thermal crosstalk and the output of the opposite phase that is opposite to the sensor output from the adjacent light receiving electrode, and becomes almost zero.

As described above, by feeding back the sensor signal from the light receiving electrode on which the infrared rays are incident, as the output of the sensor signal to the adjacent sensor, the sensor output from the adjacent light receiving electrode is obtained. In addition, it is possible to obtain an accurate sensor output that suppresses thermal crosstalk and has no variation or error, and it is possible to perform accurate heat source detection and human body detection. Furthermore, because thermal crosstalk is canceled, an accurate sensor signal output can be obtained for the amount of infrared incident light, so blurring of the infrared image can be suppressed, reliability is high, and the human body is highly accurate. Detection,
It is possible to detect the position.

As described above, according to the present embodiment, the sensor output from the light receiving electrode on which infrared rays are incident is fed back, inverted and amplified, and a signal of an opposite phase is generated from the adjacent output, whereby infrared rays are generated. The sensor output from the non-irradiated light receiving electrode can be accurately output, and it is possible to easily and accurately output a sensor output that is highly accurate, highly reliable, and does not depend on thermal crosstalk, and that has no variation or error. A pyroelectric infrared sensor can be obtained.

(Embodiment 3) A pyroelectric infrared sensor according to a third embodiment of the present invention will be described below with reference to FIG.

A light-receiving electrode portion capable of receiving infrared rays on the surface of the pyroelectric element, a compensation electrode portion corresponding to the light-receiving electrode portion, and a light-receiving / compensation electrode portion on the back surface of the pyroelectric element facing the light-receiving / compensating electrode portion. In a pyroelectric infrared sensor having a counter electrode at a position, when infrared light enters the light receiving electrode, a sensor output is obtained. Next, the sensor output obtained by the incidence of the infrared ray is made to generate a contradictory sensor output corresponding to the sensor output through the inverting amplifier circuit with respect to the adjacent output. The output at this time is not a completely opposite phase, but an output with a phase shift. The situation is shown in FIG. FIG. 3 shows signal intensities and outputs at the respective light receiving electrodes of the pyroelectric infrared sensor of the present embodiment, which are outputs when infrared rays are incident on the light receiving electrode b. By generating a phase-shifted output from the light-receiving electrodes that have not been irradiated with infrared rays, the sensor output increase due to thermal crosstalk and the output of the anti-phase signal from the infrared-unirradiated area will finally give the sensor output after correction processing. As shown in FIG. 1 (b), the light receiving surface b on which infrared rays are incident
The sensor output becomes only 0, and the sensor output becomes almost 0 on the light receiving surfaces a, c, and d where infrared rays are not incident. In the conventional pyroelectric element, due to the influence of thermal crosstalk, the thermal effect on the proximity element is large, and an inaccurate sensor output with large variations and errors is obtained, and accurate heat source detection cannot be performed. However, by using the present invention, by outputting a signal that is out of phase with the original sensor signal from the light receiving surface that is the infrared non-incident surface, there is no variation or error as shown in FIG. An accurate sensor output signal that does not depend on talk can be obtained.

As described above, by feeding back the sensor signal from the light receiving electrode on which the infrared rays are incident as the output of the sensor signal to the adjacent sensor, the sensor output from the adjacent light receiving electrode is obtained. In addition, it is possible to obtain an accurate sensor output that suppresses thermal crosstalk and has no variation or error, and it is possible to perform accurate heat source detection and human body detection. Furthermore, because thermal crosstalk is canceled, an accurate sensor signal output can be obtained for the amount of infrared incident light, so blurring of the infrared image can be suppressed, reliability is high, and the human body is highly accurate. Detection,
It is possible to detect the position.

As described above, according to this embodiment, the sensor output from the light receiving electrode on which infrared rays are incident is fed back, and a signal with a phase shifted from the adjacent output is generated. The sensor output from the electrodes can be output accurately, and it is easy, accurate, highly reliable and accurate, and does not depend on thermal crosstalk.
It is possible to obtain a pyroelectric infrared sensor that can output a sensor output without variations and errors.

(Embodiment 4) A pyroelectric infrared sensor according to a fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a diagram showing a state in which an approaching human body is detected by using the pyroelectric infrared sensor used in the second embodiment. FIG. 4 shows the state of detection of an approaching human body using sensor output, FIG. 4 (a) shows the case of using a conventional pyroelectric infrared sensor, and FIG. 4 (b) shows the present embodiment. It is a sensor output when the pyroelectric infrared sensor of an example is used. In the conventional pyroelectric infrared sensor, there is a thermal crosstalk to the adjacent light receiving electrodes, so that the sensor output is generated in a wide area, and the infrared image becomes blurred. It could not be detected separately. However, when the pyroelectric infrared sensor of the present embodiment is used, thermal crosstalk can be suppressed, so that only a sensor output corresponding to the amount of infrared incident light is generated from the adjacent light receiving electrodes. Higher resolution can be achieved, and as shown in FIG. 4B, it is possible to detect even two human bodies in close proximity by sufficiently dividing them.

In this way, the signal output contradictory to the sensor output is generated from the region near the light receiving surface on which the infrared rays are incident, so that the thermal crosstalk generated between the plurality of pyroelectric elements is suppressed. Therefore, it is possible to obtain an accurate sensor measurement output without variations and errors, and it is possible to perform accurate heat source detection and human body detection. Furthermore, since thermal crosstalk is canceled, it is possible to obtain an accurate sensor signal output with respect to the amount of infrared incident light, so that it is possible to suppress blurring of the infrared image, high resolution, and high reliability. It is possible to detect multiple human bodies and positions with high accuracy.

[0037]

As is apparent from the above description, the present invention can eliminate the thermal crosstalk generated between a plurality of infrared ray receiving surfaces, and the increase in the sensor output from the infrared non-irradiated electrode due to the crosstalk can be seen. Therefore, the heat source and the human body can be detected accurately and easily.

In particular, since thermal crosstalk between adjacent light receiving electrodes can be electrically suppressed, an accurate sensor output corresponding to the incident amount of infrared rays can be generated, and the sensor output from the adjacent light receiving electrodes does not depend on the sensor output accurately. It is possible to obtain a sensor output with no variation or error, and by doing so, it is possible to detect the separation of an approaching human body, which was previously impossible due to thermal crosstalk. It has become possible to detect the human body and the heat source at the resolution.

As described above, the pyroelectric infrared element and the infrared sensor are structurally very simple, and by using this sensor, it is possible to easily and inexpensively produce accurate and highly reliable variations and errors. A small amount of heat source can be detected, a two-dimensional temperature distribution can be obtained, and an accurate human body can be detected.

Therefore, by using the present invention, it is possible to greatly contribute to the manufacture of a pyroelectric infrared element and an infrared sensor capable of easily and highly accurately detecting a human body with high reliability.

[Brief description of drawings]

FIG. 1 is a signal intensity and output at each light receiving electrode of the pyroelectric infrared sensor according to the first embodiment of the present invention,
(A) Output when infrared rays are incident on the light receiving electrode b, (b)
It is the sensor output after processing.

FIG. 2 is a circuit diagram for explaining an electric circuit of a pyroelectric infrared sensor according to a second embodiment of the present invention.

FIG. 3 is a signal intensity and output at each light receiving electrode of the pyroelectric infrared sensor according to the third embodiment of the present invention, and is an output when infrared light is incident on the light receiving electrode b.

FIG. 4 is a diagram showing a state of detection of an approaching human body by using a sensor output, where (a) a conventional pyroelectric infrared sensor is used, and (b) a fourth embodiment of the present invention. It is a sensor output when a pyroelectric infrared sensor is used.

FIG. 5 is a diagram showing signal intensity and sensor output at each light receiving electrode when a conventionally used pyroelectric infrared sensor is used.

FIG. 6 is a schematic view showing an electrode pattern of a conventional pyroelectric infrared sensor, showing (a) a front surface of a pyroelectric substrate and (b) a back surface of the pyroelectric substrate.

[Explanation of symbols]

 20 Pyroelectric body 21 Light receiving electrode 22 Compensating electrode 23 Counter electrode 24 Amplifying circuit 25 Infrared 26 Infrared light shielding plate 27 Inversion amplifying circuit

Claims (4)

[Claims] 1. When an infrared ray is incident on one pyroelectric element of a plurality of pyroelectric elements which are polarized by receiving infrared rays, the output from the pyroelectric element is adjacent to the pyroelectric element. A pyroelectric infrared device, wherein the outputs from the adjacent pyroelectric devices can be corrected by causing the pyroelectric devices to output signals that are electrically contradictory to each other. 2. A light receiving electrode portion capable of receiving infrared rays on the surface of the pyroelectric element, a compensation electrode portion corresponding to the light receiving electrode portion, and a light receiving / compensating electrode portion opposed to the back surface of the pyroelectric element. In a pyroelectric infrared sensor provided with a counter electrode at a position, when infrared light is incident on a certain light receiving electrode section,
With respect to the output from the light receiving electrode, the output from the adjacent electrode can be corrected by causing the electrodes adjacent to the light receiving electrode to output electrically contradictory signals. Infrared sensor. 3. A light receiving electrode portion capable of receiving infrared light on the surface of the pyroelectric element, a compensation electrode portion corresponding to the light receiving electrode portion, and a light receiving / compensating electrode portion facing the back surface of the pyroelectric element. In a pyroelectric infrared sensor having a counter electrode at a predetermined position, when an infrared ray is incident on a certain light-receiving electrode portion, the sensor output from the light-receiving electrode is amplified by an operational amplifier and a resistor, and is proportional to the sensor output. By outputting the opposite phase signal from the electrode adjacent to the light receiving electrode, the influence of heat between the adjacent elements is suppressed,
A pyroelectric infrared sensor characterized in that the sensor output can be corrected. 4. The pyroelectric type according to claim 3, wherein the signal output from the electrode adjacent to the light receiving electrode is a signal whose phase is shifted with respect to the sensor output from the light receiving electrode. Infrared sensor.