JPH102791A - Pyroelectric infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and inexpensive pyroelectric infrared sensor having a long service life and a wide view, which is employed in a home appliance, e.g. a lighting fixture or an air-conditioner. SOLUTION: The pyroelectric infrared sensor comprises an optical system, having more than one diffraction optical element 6 and more than one pyroelectric 1, located at the focal point of the diffraction optical element 6. This arrangement requires no drive motor for turning the sensor section for scanning a detection area, in order to locate an object, thus realizing a small and inexpensive pyroelectric infrared sensor with a long service life.

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 for detecting infrared rays with a pyroelectric body.

[0002]

2. Description of the Related Art In recent years, pyroelectric infrared sensors take advantage of the fact that they can detect objects and detect temperatures in a non-contact manner. It is used for human body detection and the like, and the range of use is expected to expand in the future.

A pyroelectric infrared sensor uses a pyroelectric effect of LiTaO ₃ crystal or the like. The pyroelectric body has spontaneous polarization and constantly generates a surface charge. However, in a steady state in the atmosphere, the pyroelectric body is electrically neutral with the charge in the atmosphere. When infrared rays are incident thereon, the temperature of the pyroelectric body changes, and the charge state on the surface also changes due to the neutral state being broken. At this time, the charge generated on the surface is detected,
An infrared sensor measures the amount of incident infrared light. Generally, an object emits infrared rays according to its temperature, and the use of this pyroelectric infrared sensor can detect the presence and temperature of the object.

FIG. 9 schematically shows a conventional pyroelectric infrared sensor. Conventionally, a pyroelectric infrared sensor is disclosed in
What is described in JP-A-2-222128 is known. A pyroelectric body 14 made of, for example, ceramic, which detects infrared rays, a sealing can 15 for protecting the pyroelectric body 14 from disturbance light and electromagnetic noise, and an infrared filter attached to an opening 16 of the sealing can 15 17 and an external lens 18 which forms an image on the pyroelectric body 14 of infrared rays 19 radiated from a detection target which is located outside the sealing can 15 and penetrates or moves in the detection area. I have.

The external lens 18 covers a wide range of infrared rays 19.
The optical axis of each lens is distributed so that each lens has a field of view at regular intervals in the detection area as shown in the figure, for example. The outer lens 18 is made of polyethylene and uses a refraction type Fresnel lens array utilizing the refraction of light. In one Fresnel lens, the inclination angle of the groove is increased by increasing the depth of the groove toward the outer periphery, and the interval between the grooves and the depth of the groove are on the order of several hundred to several thousand times the wavelength, and the shape is also large. It is big. Further, since each lens of the external lens 18 is formed so that the optical axis is perpendicular to the lens surface,
Becomes dome-shaped, and becomes three-dimensional and large. As a detection, it reacts when the detection target enters the detection area, but cannot specify the position.

As an example of specifying the position of a detection target, a conventional pyroelectric infrared sensor is disclosed in Japanese Patent Laid-Open No. 1-147241.
Japanese Unexamined Patent Publication (Kokai) No. H10-264, pp. 157-334 is known. FIG. 10 shows the structure of a conventional pyroelectric infrared sensor. An infrared ray 25 having a wavelength of about 6 to 15 μm mainly emitted from a human body and a wall is input to an infrared sensor 21 through a lens 20 and an electrical signal is output. Convert to The drive unit is the sensor unit 22
Has a drive motor 23 for rotating scanning of
The scanning angle of the sensor unit 22 is sequentially detected by the rotation detector 24 to detect the position of the human body.

[0007]

Since this pyroelectric infrared sensor is used for household products such as lighting and air conditioning equipment, miniaturization, cost reduction and long life are strongly demanded, but it can be sufficiently satisfied. It was not something.

An object of the present invention is to provide a pyroelectric infrared sensor having a small size, a low cost, and a long service life so as to be used for such household goods.

[0009]

According to the present invention, there is provided an optical system having at least two diffractive optical elements, and an optical system which is built in a sealing body and located at an image forming point of the diffractive optical elements. And at least two or more pyroelectric bodies.

According to this configuration, it is possible to provide a pyroelectric infrared sensor having a small size, a low cost, and a long life as used for household products.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a sealing body having an opening, an infrared incident window sealed at the opening of the sealing body, and an infrared incident window. An optical system having at least two or more diffractive optical elements positioned at the front, and at least two or more pyroelectric elements built in the sealing body and positioned at an image forming point of the diffractive optical element, and a sensor unit There is no need for a drive motor for rotating and scanning, and there is an effect that the size, cost, and life are increased.

[0012] According to a second aspect of the present invention, there is provided a sealing body having an opening, an infrared incident window sealed at the opening of the sealing body, and an infrared incident window located in front of the infrared incident window. An optical system having at least two or more diffractive optical elements, at least two or more pyroelectric elements built in the sealing body and located at the image forming point of the diffractive optical element, and a screen between the pyroelectric elements. The effect of cross-talk caused by other diffractive optical elements can be cut off by the screen, S / N can be improved, and detection without malfunction can be performed.

According to a third aspect of the present invention, there is provided a sealed body having an opening, an infrared ray incident window sealed at the opening of the sealed body, and a front side of the infrared ray incident window. An optical system having at least two or more diffractive optical elements, the principal points of which coincide with each other; and at least two or more pyroelectric elements built in the sealing body and located at the image forming point of the diffractive optical element It is a configuration with a body, by matching the main points,
Since the outputs are superimposed, there is an effect that the cost can be reduced, the size can be reduced, and the field of view can be widened.

According to a fourth aspect of the present invention, an optical system having at least two or more diffractive optical elements is provided directly on the infrared incident window in the structure of the first to third aspects. And an infrared incident window are shared, so that the cost and the output can be reduced, and the space can be reduced in size.

According to a fifth aspect of the present invention, in the constitution of the first to fourth aspects, a diffractive optical lens is used as a diffractive optical element, and the diffractive optical lens has irregularities corresponding to a phase modulation amount. This has the effect that the light can be collected with high efficiency and the size and output can be increased.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the shape of the unevenness is stepped, and the processing can be performed easily and with high precision by etching. It has the effect of enabling cost reduction.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the first embodiment of the present invention.
1 schematically shows a pyroelectric infrared sensor according to the first embodiment. A sealing body 4 having an opening 3 for protecting the built-in pyroelectric body 1 and the circuit 2 from disturbance light and electromagnetic noise, and, for example, Si sealed in the opening 3 of the sealing body 4
And an infrared ray 8 radiated from an object to be detected which is located in front of the infrared ray incident window 5 and intrudes into the detection area or moves in the detection area. An optical system having at least two or more diffractive optical elements 6, and the diffractive optical element 6 built in the sealing body 4
And at least two or more pyroelectric elements 1 formed of, for example, a thin film, which are located at the image forming point, and a high-resistance, FET built in the sealing body 4 and generated by the pyroelectric element 1, for example. It is composed of at least two or more circuits 2 for extracting electric charges as signals to the outside, and a fixed base 7 on which the pyroelectric body 1 and the circuit 2 are mounted.

At this time, the diffractive optical element 6 and the pyroelectric body 1
There are at least as many detection fields as the number of diffractive optical elements 6 (for example, when the pyroelectric element is divided into N, the number of diffractive optical elements × N exists), and FIG.
As shown in (a) and (b), the pyroelectric elements 1 are positioned at intervals such that their fields of view do not interfere with each other, and the arrangement of the diffractive optical element 6 is set so that the fields of view do not interfere with each other. It has been done. Further, since each of the pyroelectric bodies 1 has the circuit 2, it is possible to specify which detection visual field the detection target object has entered or moved by the configuration of the control system.

The operation of the pyroelectric infrared sensor configured as described above will be described. First, when a detection target enters or moves into a detection field formed by the diffractive optical element 6 and the pyroelectric element 1, the infrared rays 8 emitted from the detection target are collected by the diffractive optical element 6 and collected by the pyroelectric element. 1 is imaged. At this time, the temperature of the pyroelectric body 1 changes, and accordingly, the charge state of the surface also changes because the neutral state is broken. At this time, the electric charge generated on the surface is detected as a signal by the circuit 2, and the presence of the detection target is detected. At this time, the position of the detection target in the detection area can be confirmed based on the information from which pyroelectric body 1.

With this configuration, a pyroelectric infrared sensor that is small in size, low in cost, and has a long life without the need for a drive motor for rotating and scanning the sensor unit to confirm the position of the detection target in the detection area is provided. It becomes possible to configure.

The number of divisions N of the pyroelectric body 1 (for example, N =
By increasing 4), it is possible to detect an output signal due to slight movement of the detection target, and it is possible to confirm at which position in the detection area the detection target continues.

By providing a chopping mechanism for interrupting incident infrared rays in front of the diffractive optical element 6 or between the diffractive optical element 6 and the infrared incident window 5, incident infrared rays can be detected as a quantity. The temperature distribution in the detection area can be measured.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 schematically shows a pyroelectric infrared sensor according to the second embodiment of the present invention. A sealing body 4 having an opening 3 for protecting the built-in pyroelectric body 1 and the circuit 2 from disturbance light and electromagnetic noise, and a material such as Si sealed in the opening 3 of the sealing body 4 is used. An infrared incident window 5, and at least two or more infrared rays 8 radiated from a detection target that is located in front of the infrared incident window 5 and that penetrates or moves in the detection area, and forms an image on the pyroelectric body 1. An optical system having a diffractive optical element 6, at least two or more pyroelectric bodies 1 formed of, for example, a thin film, which are built in the sealing body 4 and located at the image forming point of the diffractive optical element 6, At least two or more screens 9, which are provided between the electric elements 1 and which are built in the sealing body 4 and are made of, for example, a high-resistance, FET, and take out charges generated in the pyroelectric element 1 as signals. The circuit 2, the pyroelectric body 1 and the circuit 2 are mounted. It is formed of a fixed base 7.

At this time, the diffractive optical element 6 and the pyroelectric body 1
Are present by at least the number of the diffractive optical elements 6 (for example, when the pyroelectric body 1 is divided into N pieces, the number of the diffractive optical elements 6 × N exists).
Further, since each of the pyroelectric bodies 1 has the circuit 2, it is possible to specify which detection visual field the detection target object has entered or moved by the configuration of the control system.

The operation of the pyroelectric infrared sensor configured as described above will be described. First, when a detection target enters or moves into a detection field formed by the diffractive optical element 6 and the pyroelectric element 1, the infrared rays 8 emitted from the detection target are collected by the diffractive optical element 6 and collected by the pyroelectric element. 1 is imaged. Here, crosstalk from another diffractive optical element 6 is cut off by the partition 9. At this time, the temperature of the pyroelectric body 1 changes, and accordingly, the charge state of the surface also changes because the neutral state is broken. At this time, the electric charge generated on the surface is detected as a signal by the circuit 2, and the presence of the detection target is detected. At this time, the position of the detection target in the detection area can be confirmed based on the information from which pyroelectric body 1.

With this configuration, the influence of crosstalk caused by the other diffractive optical element 6 can be cut off by the partition 9 to improve the S / N ratio. As a result, detection without malfunction can be performed, and the pyroelectric body 1 can be detected. Since the distance can be reduced, a pyroelectric infrared sensor that can be reduced in size can be configured.

The number of divisions N of the pyroelectric body 1 (for example, N =
By increasing 4), it is possible to detect an output signal due to slight movement of the detection target, and it is possible to confirm at which position in the detection area the detection target continues.

By providing a chopping mechanism for interrupting incident infrared light in front of the diffractive optical element 6 or between the diffractive optical element 6 and the infrared incident window 5, incident infrared light can be detected as a quantity. The temperature distribution in the detection area can be measured.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. FIG.
7A and 7B schematically show a pyroelectric infrared sensor according to a third embodiment of the present invention. A sealing body 4 having an opening 3 for protecting the built-in pyroelectric body 1 and the circuit 2 from disturbance light and electromagnetic noise, and a material such as Si sealed in the opening 3 of the sealing body 4 is used. An infrared incident window 5, and at least two or more infrared rays 8 radiated from a detection target that is located in front of the infrared incident window 5 and that penetrates or moves in the detection area, and forms an image on the pyroelectric body 1. And an optical system whose principal points coincide with each other, and at least two or more thin films formed of, for example, thin films which are built in the sealing body 4 and located at the image forming point of the diffractive optical element 6 A pyroelectric body 1 and at least two or more circuits 2 which are built in the sealing body 4 and are made of, for example, a high-resistance FET, and take out charges generated in the pyroelectric body 1 as signals, Fixed base 7 on which pyroelectric body 1 and circuit 2 are mounted It is configured Ri. Since the detection field is formed by the diffractive optical element 6 and the pyroelectric element 1 and each of the pyroelectric elements 1 has the circuit 2, which detection field the detection target object has entered or moved by the configuration of the control system. Can be specified.

The operation of the pyroelectric infrared sensor configured as described above will be described. First, when a detection target enters or moves into a detection field formed by the diffractive optical element 6 and the pyroelectric element 1, the infrared rays 8 emitted from the detection target are collected by the diffractive optical element 6 and collected by the pyroelectric element. 1 is imaged. At this time, the temperature of the pyroelectric body 1 changes, and accordingly, the charge state of the surface also changes because the neutral state is broken. Here, if the principal points of the diffractive optical element 6 coincide, FIG.
As shown in (b), for example, 60 deg and -60 deg are mutually amplified by superimposing outputs. At this time, the electric charge generated on the surface is detected as a signal by the circuit 2, and the presence of the detection target is detected. At this time, the position of the detection target in the detection area can be confirmed based on the information from which pyroelectric body 1.

With this configuration, it is possible to superimpose the outputs, increase the output, and reduce the size of the diffractive optical element 6. In particular, the output of the diffractive optical element 6 having a large incident angle has been a problem in the past, but this configuration can increase the output and widen the viewing field. As a result, it is possible to configure a low-cost, small-sized pyroelectric infrared sensor having a wide-angle viewing area.

The number of divisions N of the pyroelectric body 1 (for example, N =
By increasing 4), it is possible to detect an output signal due to slight movement of the detection target, and it is possible to measure at which position in the detection area the detection target continues.

By providing a chopping mechanism for interrupting incident infrared rays in front of the diffractive optical element 6 or between the diffractive optical element 6 and the infrared incident window 5, incident infrared rays can be detected as a quantity. The temperature distribution in the detection area can be confirmed.

Further, it goes without saying that the diffractive optical element 6 may have a configuration in which elements whose principal points coincide with each other and elements which do not coincide with each other are mixed.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 schematically shows a pyroelectric infrared sensor according to a fourth embodiment of the present invention. The difference from Embodiment 1 is that
That is, an optical system having at least two or more diffractive optical elements 10 is provided directly on the infrared incident window 5.

With this configuration, the diffractive optical element 10 and the infrared incident window 5 are used in common, so that the cost can be reduced, and the total transmittance of infrared rays is improved by integrating the diffractive optical element 10 and the infrared incident window 5. . In addition, the integration enables spatial miniaturization. As a result, a pyroelectric infrared sensor that can be manufactured at low cost, with high output, and with a small size can be configured.

It is needless to say that the same effect can be obtained by providing an optical system having at least two or more diffractive optical elements 6 directly in the infrared incident window 5 with respect to the second and third embodiments.

Embodiment 5 Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 7 schematically shows a pyroelectric infrared sensor according to a fifth embodiment of the present invention. The difference from Embodiment 1 is that
A diffractive optical lens 11 is used as a diffractive optical element, and the diffractive optical lens 11 has irregularities corresponding to the amount of phase modulation.

With this configuration, since the diffraction efficiency is 100%, light can be condensed with high efficiency, and as a result, a pyroelectric infrared sensor that can be reduced in size and output can be configured.

It should be noted that the same effects can be obtained by using a diffractive optical lens as the diffractive optical element in the second, third, and fourth embodiments, and using the diffractive optical lens having irregularities corresponding to the amount of phase modulation. Needless to say.

(Embodiment 6) Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 8 shows a cross section of a diffractive optical lens according to the sixth embodiment of the present invention. The difference from the fifth embodiment is that the cross-sectional shape of the diffractive optical lens is changed by the unevenness 1 according to the phase modulation amount.
2 is approximated to m steps (for example, m = 8) of steps 13 so as to be inscribed in 2.

With this configuration, the diffraction efficiency can be converged with a high efficiency of 95%, for example, in the case of approximating in eight steps, and the processing can be easily and accurately performed by etching. Production becomes possible. As a result, it is possible to configure a pyroelectric infrared sensor capable of increasing the output and reducing the cost.

[0043]

As described above, according to the present invention, an optical system having at least two or more diffractive optical elements and at least two or more pyroelectric elements located at the imaging point of the diffractive optical elements are provided. Accordingly, there is provided a pyroelectric infrared sensor that is compact, low-cost, and has a long life without the need for a drive motor for rotating and scanning the sensor unit in order to confirm the position of the detection target in the detection area. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a pyroelectric infrared sensor according to a first embodiment of the present invention.

FIGS. 2A and 2B are a layout diagram of a pyroelectric body and a layout diagram of a diffractive optical element according to the first embodiment of the present invention.

FIG. 3 is a schematic sectional view of a pyroelectric infrared sensor according to a second embodiment of the present invention.

FIGS. 4A and 4B are a top view and a schematic cross-sectional view of a pyroelectric infrared sensor according to a third embodiment of the present invention.

FIGS. 5A and 5B are conceptual diagrams of output superposition according to a third embodiment of the present invention.

FIG. 6 is a schematic sectional view of a pyroelectric infrared sensor according to a fourth embodiment of the present invention.

FIG. 7 is a schematic sectional view of a pyroelectric infrared sensor according to a fifth embodiment of the present invention.

FIG. 8 is a schematic sectional view of a diffractive optical lens used for a pyroelectric infrared sensor according to a sixth embodiment of the present invention.

FIG. 9 is a schematic sectional view of a conventional pyroelectric infrared sensor.

FIG. 10 is a schematic sectional view of a conventional pyroelectric infrared sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pyroelectric body 2 Circuit 3 Opening 4 Sealing body 5 Infrared entrance window 6 Diffractive optical element 7 Fixing stand 8 Infrared 9 Screen 10 Diffractive optical element 11 Diffractive optical lens 12 Irregularity according to phase modulation amount 13 Step

Claims (6)

[Claims] 1. A sealing body having an opening, an infrared incident window sealed in the opening of the sealing body, and at least two or more diffractive optical elements located in front of the infrared incident window. A pyroelectric infrared sensor, comprising: an optical system; and at least two pyroelectric elements built in the sealing body and located at the image forming point of the diffractive optical element. 2. A sealing body having an opening, an infrared incident window sealed at the opening of the sealing body, and at least two or more diffractive optical elements located in front of the infrared incident window. An optical system, at least two or more pyroelectric elements built in the sealing body and located at the image forming point of the diffractive optical element, and a screen between the pyroelectric elements, and a pyroelectric infrared ray. Sensor. 3. A sealing body having an opening, an infrared incident window sealed in the opening of the sealing body, and at least two or more diffractive optical elements located in front of the infrared incident window. And an optical system having respective principal points coincident with each other, and at least two or more pyroelectric bodies built in the sealing body and located at the image forming point of the diffractive optical element. Type infrared sensor. 4. The pyroelectric infrared sensor according to claim 1, wherein an optical system having at least two or more diffractive optical elements is provided directly on the infrared incident window. 5. The pyroelectric infrared ray according to claim 1, wherein a diffractive optical lens is used as the diffractive optical element, and the diffractive optical lens has irregularities according to a phase modulation amount. Sensor. 6. The pyroelectric infrared sensor according to claim 5, wherein the unevenness has a stepped shape.