WO2005116594A1

WO2005116594A1 - Pyroelectric element and pyroelectric infrared sensor

Info

Publication number: WO2005116594A1
Application number: PCT/JP2005/009325
Authority: WO
Inventors: Shinya Nozu
Original assignee: Murata Manufacturing Co., Ltd.
Priority date: 2004-05-28
Filing date: 2005-05-23
Publication date: 2005-12-08
Also published as: WO2005116594A8; JP2007292461A

Abstract

On a pyroelectric board (1), single elements (35A, 24A, 24B, 35B) are successively arranged in a horizontal direction. The single elements (24A, 24B) form a first dual element (24), and the single elements (35A, 35B) form a second dual element (35). To the single elements (35A, 24A, 24B, 35B), infrared rays generated in substantially continuous different areas (C, D, E, F) are focused and irradiated. A signal detected by the second dual element (35) by infrared ray irradiation is outputted from an FET (2), and a signal detected by the first dual element (24) is outputted from an FET (1). Thus, a human body (100) in center areas (D, E) corresponding to the first dual element (24) and in peripheral areas (C, F) corresponding to the second dual element (35) sandwiching the areas (D, E) is detected.

Description

Specification

Pyroelectric element and pyroelectric infrared sensor

Technical field

The present invention relates to a pyroelectric element formed by forming an electrode on a substrate surface having a pyroelectric effect, and a pyroelectric infrared ray sensor for detecting a person and an object in a predetermined detection area using the pyroelectric element. Related to sensors. Background art

Conventionally, a pyroelectric infrared sensor includes a pyroelectric element that outputs a detection signal by receiving infrared light, and an optical system that causes the pyroelectric element to receive infrared light, and moves within a predetermined detection area. By detecting infrared rays generated by a moving object (for example, a person), the movement of this object is detected.

[0003] A pyroelectric element used in such a pyroelectric infrared sensor includes a pyroelectric substrate made of a ferroelectric material or the like, and electrodes provided on both sides of the pyroelectric substrate.

[0004] The pyroelectric substrate does not generate electric charge between both surfaces in a steady state (when the substrate temperature is constant), but when the substrate temperature changes, electric charge is generated between both surfaces according to the change. This is because the pyroelectric substrate, which is a ferroelectric material, is spontaneously polarized in a steady state, but is in a neutral state by attracting a floating charge in the outside air, whereas the spontaneous polarization state is changed when the substrate temperature changes. This is a phenomenon that occurs because the neutral state changes due to change. Pyroelectric elements use this phenomenon to extract charge fluctuations that change in accordance with the magnitude of temperature change due to infrared radiation applied to the electrode-formed portion of the pyroelectric substrate, using the electrodes formed on these surfaces. This outputs a detection signal.

[0005] Such a pyroelectric element is provided with one single element composed of a single electrode and a pyroelectric substrate formed on both sides of the pyroelectric substrate so as to be opposed to each other as described above. On the other hand, a device having a dual element formed by arranging two single elements has been devised (see Patent Document 1). In a pyroelectric element having such a dual element, two single elements are arranged in parallel, and the light-receiving surface electrode or the opposing surface electrode of each single element has the opposite polarity of the charge generated by the temperature change of the pyroelectric substrate. Are connected in series so that This is to correct the external temperature dependency that occurs when only the element is used. This configuration can also be used simply as two single elements arranged at a predetermined interval. In other words, the pyroelectric element that detects infrared radiation from different positions is configured by making the light receiving area different for each single element constituting the pyroelectric element including the dual element. By arranging the single elements in the horizontal direction, a pyroelectric infrared sensor for detecting the moving direction of an object such as a person is formed.

[0006] Furthermore, since the detection area is limited even in the case of a pyroelectric element having a dual element, a pyroelectric element in which the detection area is enlarged using a pyroelectric element in which a plurality of dual elements are formed is used. An infrared sensor has been devised (see Patent Document 2).

Patent Document 1: JP-A-5-187918

Patent Document 2: Registered Utility Model No. 3042061

Disclosure of the invention

Problems to be solved by the invention

[0007] In an infrared sensor used in a security system, it is desirable to mainly detect a specific narrow area and also to detect a wide area around the specific area. As an example of this, there is a case where a guard area (priority monitoring area) and a guard preparation area (light monitoring area) are simultaneously monitored (detection of a person or an object). In this case, the surrounding area (light monitoring area) is usually located on both sides of the central area (high priority monitoring area) where priority detection is performed.

[0008] When detecting the important monitoring area and the light monitoring areas on both sides in this way, a dual element corresponding to the priority monitoring area and two dual elements respectively corresponding to the light monitoring areas on both sides are provided. Must be formed on the pyroelectric element. In other words, in a conventional pyroelectric element having a plurality of dual elements, dual elements must be formed in the pyroelectric element by the number of areas to be detected. The sensor cannot be made small-sized and low-cost. Also, a pyroelectric infrared sensor in which pyroelectric elements are arranged according to the number of detection areas can detect the above-mentioned area, but the increase in the number of pyroelectric elements increases the size and cost. Would.

[0009] An object of the present invention is to configure a pyroelectric infrared sensor having a simple structure that detects a specific region and detects regions on both sides of the specific region as described above. Means for solving the problem

[0010] The present invention provides a pyroelectric substrate, a light receiving surface electrode formed on one surface of the pyroelectric substrate, and an opposing surface electrode formed on the other surface of the pyroelectric substrate so as to face the light receiving surface electrode. In the pyroelectric element formed by arranging a plurality of single elements formed in approximately one row, four or more even single elements are formed, and two single elements adjacent to each other at the center in the arrangement direction The first dual element formed by conducting between the light receiving surface electrodes or the opposite surface electrodes, and the single element on both sides sandwiching the first dual element in the arrangement direction are combined one by one from the inside, and combined. And one or more second dual elements formed by electrically connecting the light receiving surface electrodes of the respective single elements or between the opposing surface electrodes.

[0011] In this configuration, a plurality of single elements are arrayed and formed in the pyroelectric element, and the single element adjacent to the first dual element is combined with the first dual element interposed therebetween to form another second dual element. A single element adjacent to both sides of the outer second dual element with the first and second dual elements interposed therebetween is combined to form another second dual element. Such repetition of the dual element configuration is performed for at least four single elements formed in the pyroelectric element. As a result, two single elements constituting the sandwiched dual element are arranged on both sides of the sandwiched dual element.

[0012] Further, the pyroelectric element of the present invention is formed by electrically connecting the light receiving surface electrodes or the opposing surface electrodes of the first dual element and the single elements on both sides of the first dual element in the arrangement direction. And a second dual element.

[0013] In this configuration, the two single elements of the second dual element are arranged on both sides of the first dual element.

Further, the pyroelectric infrared sensor according to the present invention irradiates infrared rays generated in a specific region to the formation position of the above-mentioned pyroelectric element and the first dual element of the pyroelectric element, and the first dual element Optical means for irradiating other dual elements with infrared rays generated in a region sandwiching the specific region.

[0015] With this configuration, infrared light generated in the detection area is transmitted to the red light of the pyroelectric element through the optical means. The portion corresponding to the region where the outside line is generated is irradiated. As described above, the pyroelectric element generates an electric charge due to a change in temperature, so that the temperature of a portion irradiated with infrared rays rises, and a local electric charge is generated. Then, the pyroelectric element outputs a detection signal by detecting this charge with a single element. Here, the pyroelectric element of the present invention has a structure in which the first dual element is sandwiched by the second dual element as described above, so that the area detected by the first dual element is the single area of the second dual element. It is sandwiched between each area detected by the element. If a second dual element is formed further outside, each area detected by each single element of the sandwiched second dual element is detected by the second dual element sandwiched. Located on both sides of the area. That is, the second dual element, which is a single element on both sides sandwiching the first dual element for detecting the predetermined area, detects the area on both sides sandwiching the predetermined area, and the two dual elements, the inner two areas and this area, Four regions consisting of the two outer regions sandwiching are detected.

Further, the pyroelectric infrared sensor of the present invention is characterized in that the optical means is constituted by an infrared condensing lens provided on the detection area side of the pyroelectric element.

[0017] In this configuration, the infrared light generated in the detection area is collected by the single infrared light condensing lens, and is applied to each part of the pyroelectric element corresponding to each area of the detection area.

The invention's effect

According to the present invention, by including the first dual element and the second dual element composed of a single element sandwiching the first dual element, infrared rays from a specific area can be detected and this specific element can be detected. The pyroelectric element for detecting the infrared rays generated by the area force on both sides of the area can be configured with a simple structure.

Further, according to the present invention, infrared rays having a specific area are detected by the first dual element, and infrared rays on both sides of the specific area are separated by a single element having the first dual element interposed therebetween. Is detected by the second dual element. Thus, a pyroelectric infrared sensor that detects four regions, that is, two regions in a specific region and two regions on both sides of the specific region, can be configured by these two dual elements. That is, the pyroelectric infrared sensor for detecting the specific region and the regions on both sides thereof can be configured with a simple structure. Further, according to the present invention, a pyroelectric infrared sensor having a simpler structure can be configured by irradiating infrared light in the detection area to the pyroelectric element using a single infrared light condensing lens. it can.

Brief Description of Drawings

FIG. 1 is a plan view, a sectional view, and a bottom view of a pyroelectric element of the present invention.

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

FIG. 3 is an equivalent circuit diagram of the pyroelectric infrared sensor of the present invention.

FIG. 4 is a conceptual diagram showing a relationship between a range of a detection area and an infrared irradiation position of a pyroelectric element.

FIG. 5 is a conceptual diagram showing a state of detecting movement of a person by the pyroelectric infrared sensor of the present invention.

[0022] 1 Pyroelectric substrate

2A, 2B—Light receiving surface electrode

2C—Connection electrode

4A, 4B—facing electrode

24A, 24B Single element

24 1st dual element

3A, 3B—Light receiving surface electrode

3C—Connection electrode

5A, 5B—facing electrode

35A, 35B—Single element

35 2nd dual element

6A, 6B, 7A, 7B—External connection electrode

10—pyroelectric element

20—Base substrate

30—Stem

31A to 31D External connection pins

40 Filter support (can case) 50 Infrared pass filter

60 Lens dome with Fresnel lens

100 people

BEST MODE FOR CARRYING OUT THE INVENTION

A pyroelectric element according to an embodiment of the present invention and a pyroelectric infrared sensor using the pyroelectric element will be described with reference to FIGS.

FIG. 1 (A) is a plan view of a pyroelectric element according to an embodiment of the present invention, and FIG. 1 (B) is a cross-sectional view taken along the line AA ′ of the pyroelectric element shown in (A) and (C). FIG. 1C is a bottom view of the pyroelectric element of the present embodiment.

The pyroelectric element 10 is formed on a flat pyroelectric substrate 1 having a pyroelectric effect, for example, a ferroelectric force, and a surface of the pyroelectric substrate 1 (a surface shown in FIG. 1A). The first light-receiving surface electrodes 2A, 2B, the second light-receiving surface electrodes 3A, 3B, the connection electrodes 2C, 3C, and the first opposing surface formed on the back surface of the pyroelectric substrate 1 (the surface shown in FIG. 1 (C)). The surface electrodes 4A, 4B, the second opposed surface electrodes 5A, 5B, and the external connection electrodes 6A, 6B, 7A, 7B formed on the back surface of the pyroelectric substrate 1 act as forces.

[0024] At substantially the center of the surface of the pyroelectric substrate 1, light receiving surface electrodes 2A and 2B having a rectangular shape in plan view are arranged and formed so as to be separated by a predetermined distance so that long sides are adjacent to each other. A connection electrode 2C is formed substantially at the center of the two light receiving surface electrodes 2A and 2B in the long side direction, and the light receiving surface electrodes 2A and 2B are electrically connected. Light receiving surface electrodes 2A and 2B are formed on the surface of the pyroelectric substrate 1 and light receiving surface electrodes 3A and 3B having substantially the same shape as the light receiving surface electrodes 2A and 2B are formed at positions separated by a predetermined distance. I have. The light receiving surface electrode 3A is arranged on the side facing the light receiving surface electrode 2B with the light receiving surface electrode 2A as the center, and the light receiving surface electrode 3B is arranged on the side facing the light receiving surface electrode 2A with the light receiving surface electrode 2B as the center. I have. Further, the light receiving surface electrodes 3A, 3B are electrically connected by the connection electrodes 3C formed at positions not overlapping with the first light receiving surface electrodes 2A, 2B and the connection electrode 2C of the pyroelectric substrate 1. Here, the first light-receiving surface electrodes 2A and 2B and the second light-receiving surface electrodes 3A and 3B are materials that absorb infrared rays from the outside and partially raise the temperature of the pyroelectric substrate 1.

[0025] On the back surface of the pyroelectric substrate 1, the light receiving surface electrodes 2A, 2B are provided at positions facing the light receiving surface electrodes 2A, 2B, 3A, 3B provided on the front surface side of the pyroelectric substrate 1, respectively. , Same as 3A, 3B Opposite surface electrodes 4A, 4B, 5A, 5B are formed. Thus, a single element 24A is composed of the light receiving surface electrode 2A, the facing surface electrode 4A, and the pyroelectric substrate 1 sandwiched therebetween, and the light receiving surface electrode 2B, the facing surface electrode 4B, and the pyroelectric body sandwiched therebetween. The substrate 1 forms a single element 24B, the light receiving surface electrode 3A, the opposing surface electrode 5A, and the pyroelectric substrate 1 sandwiched therebetween constitute a single element 35A, and the light receiving surface electrode 3B and the opposing surface electrode 5B. The pyroelectric substrate 1 sandwiched therebetween forms a single element 35B. The single element 24A and the single element 24B are electrically connected so that charges detected by the connection electrodes 2C have opposite polarities, and constitute the first dual element 24. The single element 35A and the single element 35B are electrically connected so that charges detected by the connection electrodes 3C have opposite polarities, and constitute the second dual element 35.

In the present embodiment, the connection electrodes of the single elements are provided on the light receiving surface (the surface of the pyroelectric substrate 1), but the connection electrodes may be provided on the opposing surface (the back of the pyroelectric substrate 1). Yeah.

[0026] Also, on the back surface of the pyroelectric substrate 1, external connection electrodes 6A and 6B conducting to the opposing surface electrodes 4A and 4B, and external connection electrodes 7A and 6A conducting to the opposing surface electrodes 5A and 5B, respectively. 7B are formed. These external connection electrodes 6A, 6B, 7A, 7B are formed on the back surface of the pyroelectric substrate 1 at positions not facing any of the electrodes 2A to 2C, 3A to 3C formed on the front surface. Have been.

[0027] Since the pyroelectric substrate 1 has a pyroelectric effect, as described above, the infrared rays are radiated or irradiated, and the infrared rays are cut off. Imbalance occurs. At this time, there is an imbalance of charges of opposite polarity between the case where the temperature is changed by irradiation of the infrared ray and the case where the temperature is changed by blocking the infrared ray. For example, when infrared light is irradiated, positive charges are biased toward the light receiving surface of the pyroelectric substrate 1 and negative charges are biased toward the opposing surface. On the other hand, when infrared rays are blocked, negative charges are biased toward the light receiving surface of the pyroelectric substrate 1 and positive charges are biased toward the opposing surface. By utilizing this phenomenon, for example, when infrared rays are irradiated only on the light-receiving surface electrode 2A of the pyroelectric substrate 1, the single element 24A detects the charge imbalance in this part. On the other hand, when infrared light is irradiated only on the light receiving surface electrode 2B of the pyroelectric substrate 1, the single element 24B detects the charge imbalance in this part. Thus, the irradiation of the infrared rays to the light receiving surface electrodes 2A and 2B is detected by the first dual element 24. It is. At this time, since the polarity of the detected charge is reversed between the single element 24A and the single element 24B as described above, by observing the detection signal from the first dual element 24, the infrared rays It is possible to detect whether infrared light has been irradiated to the single element 24B when the light was irradiated.

[0028] Since the same effect as the first dual element 24 occurs in the second dual element 35, the irradiation of infrared rays to the light receiving surface electrodes 3A and 5A is detected by the second dual element 35. Since the polarities of the charges detected by the single element 35A and the single element 35B are reversed, by observing the detection signal from the second dual element 35, the power of the irradiation of the single element 35A with the infrared light is obtained. It is possible to detect whether infrared rays have been irradiated to the single element 35B.

That is, the pyroelectric element 10 detects infrared rays with the two dual elements of the pyroelectric substrate 1 according to the portion of the pyroelectric substrate 1 irradiated with the infrared rays, and detects infrared rays from the two output systems. An output signal can be output.

Also, since the polarities of the charges detected by the single element 24A and the single element 24B are opposite, in the case of infrared rays irradiating a wide range such as sunlight, the voltages output from the single elements 24A and 24B are opposite to each other. Are canceled and are not output to the outside. Since this effect is also applied to the single element 35A and the single element 35B, the effect of external light can be eliminated by these functions.

Next, a pyroelectric infrared sensor using the above-described pyroelectric element 10 will be described with reference to FIGS.

FIG. 2 is a perspective view of the pyroelectric infrared sensor according to the present embodiment in a state where a part of the filter support 40 and the lens dome 60 is cut out. It is formed in a shape that covers the element 10.

FIG. 3 is an equivalent circuit diagram of the pyroelectric infrared sensor of the present embodiment.

The pyroelectric element 10 is disposed on a base substrate 20 on which a predetermined electrode pattern is formed, with the side on which the first and second light receiving surface electrodes 2A, 2B, 3A, 3B are formed as an upper surface. It is electrically and mechanically connected. In the electrode pattern formed on the base substrate 20, FET1, FET2 and resistors Rl, R2 (not shown in FIG. 2) are mounted. A circuit according to the equivalent circuit diagram shown is formed. Specifically, the external connection electrode 6A of the pyroelectric element 10 is connected to the gate of the FET1, the external connection electrode 6B is connected to the ground electrode GND, and a resistor R1 is connected between the ground electrode GND and the gate of the FET1. It is connected. That is, the first dual element 24 of the pyroelectric element 10 and the resistor R1 are connected in parallel between the gate of the FET 1 and the ground. The external connection electrode 7A of the pyroelectric element 10 is connected to the gate of the FET2, the external connection electrode 7B is connected to the ground electrode GND, and a resistor R2 is connected between the ground electrode GND and the gate of the FET2. I have. That is, the second dual element 35 of the pyroelectric element 10 and the resistor R2 are connected in parallel between the gate of the FET 2 and the ground electrode GND. Further, the drain of FET1 and the drain of FET2 are connected to the drain terminal D, the source of FET1 is connected to the first source terminal S1, and the source of FET2 is connected to the second source terminal S2. A drive voltage is applied to the drain terminal D, and a predetermined resistor (not shown) is connected between the first source terminal S1 and the second source terminal S2 and the ground electrode GND, so that the first source terminal A source follower-type infrared detection circuit that outputs a voltage-type detection signal from Sl and the second source terminal S2 is configured. The FET used in the output section of this circuit is generally high impedance on the pyroelectric element 10 side. This is for performing matching and transmitting the detection signal with low loss.

[0032] The base substrate 20 is mounted on a metal stem 30 having external connection pins 31A to 31D. The external connection pins 31A to 31D are connected to the drain terminal D, the first source terminal Sl, and the second source terminal. Connected to either terminal S2 or ground electrode GND. Here, the ground electrode GND of the base substrate 20 is formed in a shape that conducts to the stem 30 (for example, a shape formed on both the front and back surfaces of the base substrate 20 and conducted through through holes). The ground electrode is mounted on the substrate on which the pyroelectric infrared sensor is mounted and grounded, so that the ground electrode GND of the base substrate 20 is grounded together with the external connection pins.

As described above, the cylindrical filter support (can case) 40 that covers the pyroelectric element 10 is provided on the upper surface side of the stem 30 on which the base substrate 20 on which the pyroelectric element 10 is mounted is mounted. In addition, an infrared light passing filter 50 that allows only infrared light of a desired wavelength to pass therethrough is disposed at a position facing the pyroelectric element 10 at an opening formed in the filter support 40. The Further, a lens dome 60 in which a spherical Fresnel lens is formed in a shape covering the filter support 40 is arranged. As shown in FIG. 4, the dome on the top surface of the lens dome 60 condenses infrared light generated in a predetermined range of each detection area by a Fresnel lens and irradiates the infrared light to a predetermined position of the pyroelectric element 10. It is formed in a shape.

FIG. 4 is a conceptual diagram showing the relationship between the range of the detection area and the infrared irradiation position of the pyroelectric element 10. FIG. 4A is a conceptual diagram showing the relationship in the horizontal direction (H direction). (B) is a conceptual diagram showing the relationship in the vertical direction (V direction). It should be noted that the relationship shown in this figure is when the arrangement direction of the single elements 24A, 24B, 35A, 35B of the pyroelectric element 10 is the horizontal direction (H direction).

When the arrangement direction of the light receiving surface electrodes 2A, 2B, 3A, 3B, that is, the arrangement direction of the single elements 24A, 24B, 35A, 35B is horizontal, as shown in FIG. 24A and 24B are arranged near a straight line passing through the zenith of the lens dome 60 and perpendicular to the pyroelectric substrate 1, so that the portion composed of the single elements 24A and 24B, that is, the first dual element 24, It is possible to detect infrared rays within a range of a predetermined angle α in the horizontal direction around a point orthogonal to the horizontal axis and the straight line. On the other hand, since the single elements 35Α and 35Β are arranged at positions sandwiching the single elements 24Α and 24Β, the portion composed of the single elements 35Α and 35Β, that is, the second dual element 35 is located between the horizontal axis of the detection area and the straight line. In the horizontal direction around the orthogonal point, infrared rays in a range of a predetermined angle β wider than the predetermined angle α can be detected excluding the range of the predetermined angle α. The single element 35Α, 24Α, 24Β, and 35Β are arranged in this order, so that the area detected by the single element 35Α and the area detected by the single element 35Β correspond to the area detected by the first dual element 24. Located on both sides. That is, the area where the first dual element 24 detects infrared rays is sandwiched between the area where the second dual element 35 detects infrared rays.

In the vertical direction, since the single elements 24Α, 24Β, 35Α, and 35 配置 are arranged at the same position in the vertical direction, the portion composed of the first and second dual elements 24, 35 And a line perpendicular to the pyroelectric substrate 1 and passing through the zenith of the lens dome 60 as a center.

Here, by changing the vertical size of the first and second dual elements, the vertical predetermined angle γ of each dual element may be made different. The operation of detecting the movement of a person using the pyroelectric infrared sensor having such a configuration will be described with reference to FIG.

This will be described with reference to FIG.

FIG. 5 is a conceptual diagram showing how the movement of a person is detected by the pyroelectric infrared sensor of the present embodiment. In this description, the light receiving surface electrodes 2A and 3A, that is, the single element 24

A case will be described in which a circuit is configured to generate a positive voltage detection signal when the portions A and 35A are irradiated with infrared rays.

As shown in FIG. 5, when the person 100 moves in the detection area horizontally from the point A to the point B, the person 100 sequentially passes through the divided areas C, D, E, and F.

(1) First, when the person 100 enters the divided area C, infrared rays radiated from the person 100 are condensed and radiated to the single element 35 A via the lens dome 60. When this portion is irradiated with infrared rays, the voltage V detected by the single element 35A becomes a positive voltage. And

F2

When the person 100 is passing through the divided area C, almost the same amount of infrared light is continuously irradiated to the single element 35A, so that the voltage V attenuates at a predetermined time constant (approaches a value of 0).

F2

. Next, when the person 100 goes out of the divided area C, the irradiation of the infrared rays to the single element 35A stops, and the voltage V detected by the single element 35A becomes a negative voltage. And this

F2

The voltage V decays with a predetermined time constant (approaches 0 value). And this signal is FET2

F2

Is amplified and output.

(2) Next, when a person enters the divided area D, infrared rays radiated from the person 100 are condensed and radiated to the portion of the single element 24A via the lens dome 60. When this part is irradiated with infrared rays, the voltage V detected by the single element 24A becomes a positive voltage. And

F1

While the person 100 is passing through the divided area D, substantially the same amount of infrared light is continuously irradiated to the single element 24A, and the voltage V attenuates with a predetermined time constant (approaches a value of 0).

F1

Next, when the person 100 goes out of the divided area D, the irradiation of the infrared rays to the single element 24A stops, and the voltage V detected by the single element 24A becomes a negative voltage. And this

F1

The voltage V decays with a predetermined time constant (approaches 0 value). And this signal is FET1

F1

Is amplified and output.

(3) Next, when a person enters the divided area E, infrared rays radiated from the person 100 are condensed and radiated to the single element 24 B via the lens dome 60. This area is illuminated by infrared light. As a result, the voltage V detected by the single element 24B becomes a negative voltage. And people

F1

While 100 passes through the divided area E, almost the same amount of infrared light is continuously irradiated to the single element 24B, and the voltage V attenuates with a predetermined time constant (approaches 0 value). Next

F1

On the other hand, when the person 100 goes out of the divided area E, the irradiation of the infrared rays to the single element 24B is stopped, and the voltage V detected by the single element 24B becomes a positive voltage. And this voltage

F1

V decays with a predetermined time constant (approaching 0). And this signal is higher than FET1.

F1

The width is output.

(4) Next, when a person enters the divided area F, infrared rays radiated from the person 100 are condensed and radiated to the single element 35 B via the lens dome 60. When this part is irradiated with infrared rays, the voltage V detected by the single element 35B becomes a negative voltage. And people

F2

While 100 passes through the divided area F, almost the same amount of infrared light is continuously irradiated on the single element 35B, so that the voltage V attenuates with a predetermined time constant (approaches 0 value). Next

F2

On the other hand, when the person 100 goes out of the divided area F, the irradiation of the infrared rays to the single element 35B is stopped, and the voltage V detected by the single element 35B becomes a positive voltage. And this voltage

F2

V decays with a predetermined time constant (approaching 0). And this signal is higher than FET2.

F2

The width is output.

As described above, by observing the output signals from the FET1 and the FET2, it is possible to detect the movement of a person. Further, by arranging a plurality of single elements, it is possible to divide the detection area and detect the movement of a person in each of the divided areas.

Further, by arranging the single elements 35A, 35B, that is, the second dual element 35 in a shape sandwiching the single elements 24A, 24B, ie, the first dual element 24, as described above, for example, the first dual element 24 The area to be detected is set as the alert area, the area to be detected by the second dual element 35 is set as the alert preparation area, and four areas consisting of two areas within the alert area and the alert preparation areas on both sides sandwiching it Can be detected by two sets of dual elements. This eliminates the need for using a dual element for each area to be detected as in the related art, and a simple structure of a pyroelectric infrared sensor for detecting one central area divided into a plurality of areas and its peripheral area. Can be realized. As a result, detection can be performed with a small pyroelectric infrared sensor that has a small number of parts and reduced cost for the same detection area as before. Can do.

In the above-described embodiment, the first dual element is sandwiched by one second dual element, and the force described in the pyroelectric infrared sensor having the structure of two dual elements is compared to the first dual element. A pyroelectric infrared sensor having a structure in which a plurality of second dual elements are sequentially sandwiched in order by the inner force can also be configured, and the same effects as described above can be obtained. Here, the number of the second dual elements to be formed may be appropriately set according to the required specifications.

Claims

The scope of the claims

[1] A pyroelectric substrate, a light receiving surface electrode formed on one surface of the pyroelectric substrate, and an opposing surface electrode formed on the other surface of the pyroelectric substrate facing the light receiving surface electrode In a pyroelectric element in which a plurality of single elements formed by

The single element is formed of an even number of four or more,

A first dual element formed by conducting light-receiving surface electrodes of two of the single elements adjacent to each other at the center in the arrangement direction or opposing surface electrodes;

The single elements on both sides sandwiching the first dual element in the arrangement direction are combined one by one from the inner side, and the light receiving surface electrodes or the opposing surface electrodes of each combined single element are formed by conduction. A pyroelectric element comprising at least one second dual element.

[2] The first dual element, and a second dual element formed by conducting light-receiving surface electrodes or opposing surface electrodes of the single element on both sides sandwiching the first dual element in the arrangement direction, The pyroelectric element according to claim 1, comprising:

[3] The pyroelectric element according to claim 1 or claim 2,

Optical means for irradiating the first dual element of the pyroelectric element with infrared rays generated in a specific area, and irradiating dual elements other than the first dual element with infrared rays generated in an area sandwiching the specific area, A pyroelectric infrared sensor comprising:

4. The pyroelectric infrared sensor according to claim 3, wherein the optical means is an infrared focusing lens provided on a light receiving surface side of the pyroelectric element.