JPH09113365A - Pyroelectric infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pyroelectric infrared sensor in which the output can be made uniform through simple adjustment by providing a drive section for moving a lens to the left and right in the direction normal to the optical axis and an aperture disposed in front of the lens. SOLUTION: Infrared rays emitted from an object within the view pass through an aperture 7 and focused on a pyroelectric body 4 located at an image point by means of a lens 5 through an infrared ray incident window 3. Since the lens 5 moves to the left and right in the direction normal to the optical axis and the detecting direction is varied, opening and shielding part of the aperture 7 are detected alternately and the quantity of light incident to the pyroelectric body 4 is varied thus bringing about chopping effect. According to the structure, only the positional relationship between the lens 5 and pyroelectric body 4 requires adjustment and since no obstacle shield the luminous flux passed through the lens 5, the luminous flux is invariant regardless of the moving amount of lens 5 thus ensuring an uniform output.

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 have been capable of non-contact detection of objects and temperature, and are used in microwave oven temperature measurement, air conditioner room temperature control, automatic doors, and alarm devices. It is used for human body detection of
Its range of use is expected to expand in the future.

The pyroelectric infrared sensor utilizes the pyroelectric effect of LiTaO ₃ single crystal or the like. The pyroelectric body has spontaneous polarization and always 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 on this, the temperature of the pyroelectric body changes, and along with this, the charge state on the surface also changes, breaking the neutral state. At this time, the charge generated on the surface is detected,
A pyroelectric infrared sensor measures the amount of incident infrared rays. Generally, an object emits infrared rays according to its temperature, and the presence or temperature of the object can be detected by using this pyroelectric infrared sensor.

A conventional pyroelectric infrared sensor will be described below. FIG. 15 shows an outline of a conventional pyroelectric infrared sensor. A sealing can 2 having an opening 1, an infrared incident window 3 attached to the opening 1, and a pyroelectric body 4 which is a thin film, for example, which is located in the sealing can 2 are provided. A lens 5 located in the front and having an image point distance near the pyroelectric body 4, and a wing 17 for connecting and disconnecting infrared rays between the infrared incident window 3 and the lens 5 are used as a driving force. It is composed of a chopper 18.

[0005]

However, in the above configuration, since the chopper 18 is positioned in the middle of the infrared ray converging light flux imaged on the pyroelectric body 4 by the lens 5, the positioning is performed so that the light flux does not reach the light flux when the chopper interruption is opened. Since it is necessary to adjust the adjustment, the adjustment becomes complicated, and when the chopper 18 is driven, the wing 17 is applied to the light flux when the chopper 18 is opened due to the nonuniformity of the displacement amount, which causes the output nonuniformity. Was there.

The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a pyroelectric infrared sensor which is easy to adjust and has a uniform output.

[0007]

In order to achieve this object, the present invention provides a sealing can having an opening, an infrared entrance window attached to the opening, and a focus located in the sealing can. An electric body, a lens located in front of the infrared entrance window and having an image point distance near the pyroelectric body, a drive unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and in front of the lens It is composed of an aperture located at the position of 1., and it is only necessary to adjust the optical positional relationship between the lens and the pyroelectric body. Does not change and the output becomes uniform.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is a sealing can having an opening, an infrared entrance window attached to the opening, and a pyroelectric lamp located in the sealing can. A body, a lens located in front of the infrared entrance window and having an image point distance near the pyroelectric body, a drive unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and in front of the lens. It is composed of apertures positioned, and has an effect that it is assembled only by adjusting the positional relationship between the lens and the pyroelectric body and uniform output can be obtained.

According to the second aspect of the present invention, the number of lenses is two or more, and the detection frequency is increased.

According to the third aspect of the invention, the pyroelectric body is composed of two or more pieces, and has the effect of being able to simultaneously detect the outputs of a plurality of detection regions.

The invention according to claim 4 has two apertures.
With the configuration having more than one opening, it has an effect of being able to simultaneously detect the outputs of a plurality of detection regions.

The invention described in claim 5 has an effect of rotating the lens in the structure of claims 1 to 4 to obtain a uniform output.

The invention described in claim 6 has an effect that the diffractive optical lens is used as the lens in the structure of claims 1 to 4 to shorten the focal length and reduce the movable amount.

According to the seventh aspect of the present invention, the lens is configured to be movable up and down with respect to the optical axis direction, and has the effect of reducing the size of the drive section.

The invention described in claim 8 has a function of being able to detect a uniform output even if the amount of movement of the lens is uneven, because the lens is curved.

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a pyroelectric infrared sensor according to the first embodiment of the present invention. Sealing can 2 having opening 1
An infrared incident window 3 attached to the opening 1, a pyroelectric body 4 which is, for example, a thin film located in the sealing can 2, a front of the infrared incident window 3 and the vicinity of the pyroelectric body 4. A lens 5 having an image point distance, a drive unit 6 for moving the lens 5 left and right in a direction perpendicular to the optical axis direction, and an aperture 7 located in front of the lens 5.

The operation of the pyroelectric infrared sensor constructed as described above will be described with reference to FIG.

First, the infrared rays 8 radiated from the object to be detected in the field of view pass through the aperture 7, and are imaged by the lens 5 after passing through the infrared incident window 3 on the pyroelectric body 4 located on the image point. At this time, since the detection direction changes as the lens 5 moves to the left and right in the direction perpendicular to the optical axis direction, the opening portion and the blocking portion of the aperture 7 are alternately detected,
Since the amount of light incident on the pyroelectric body 4 changes, a chopping effect is obtained as a result.

With this configuration, it is only necessary to adjust the optical positional relationship between the lens 5 and the pyroelectric body 4, and since there is no obstacle that blocks the light flux after passing through the lens 5, the movable amount of the lens 5 is uneven. However, it was possible to obtain a uniform output without changing the luminous flux.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 schematically shows a pyroelectric infrared sensor according to the second embodiment of the present invention. The difference from the first embodiment is that
That is, at least two lenses 9 are configured.

The operation of the pyroelectric infrared sensor constructed as described above will be described with reference to FIG.

First, the infrared rays 8 radiated from the object to be detected within the field of view pass through the aperture 7 and are imaged by the lens 9 after passing through the infrared incident window 3 on the pyroelectric body 4 located on the image point. At this time, since the detection direction is changed by moving the lens 9 left and right in the direction perpendicular to the optical axis direction, the opening portion and the blocking portion of the aperture 7 are alternately detected,
Since the amount of light incident on the pyroelectric body 4 changes, a chopping effect is obtained as a result. At this time, when there are at least two lenses 9, the amount of incident light changes by the number of lenses 9 being moved by moving the lenses 9 in one cycle, and as a result, the detection frequency increases.

With this configuration, it is only necessary to adjust the optical positional relationship between the lens 9 and the pyroelectric body 4, and since there is no obstacle that blocks the light flux after passing through the lens 9, the movable amount of the lens 9 is uneven. However, it is possible to obtain a uniform output without changing the luminous flux, and the frequency is increased, so that the number of samplings is increased and the output accuracy is improved. Further, when the pyroelectric body 4 is a thin film, the noise component of the output decreases as the detection frequency becomes higher, so that the S / N ratio can be improved.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows the outline of a pyroelectric infrared sensor according to the third embodiment of the present invention. The difference from the first embodiment is that
That is, at least two pyroelectric bodies 10 are configured.

The operation of the pyroelectric infrared sensor constructed as described above will be described with reference to FIG.

First, the infrared rays 8 radiated from the object to be detected in the field of view pass through the aperture 7 and are imaged by the lens 5 after passing through the infrared entrance window 3 on the pyroelectric body 10 located on the image point. At this time, since the detection direction is changed by moving the lens 5 left and right in the direction perpendicular to the optical axis direction, the opening and the blocking portion of the aperture 7 are alternately detected, and the incident on the pyroelectric body 10. As a result, the amount of light emitted changes, resulting in a chopping effect. At this time, when there are at least two pyroelectric bodies 10, the center of the opening of the aperture 7, the principal point of the lens 5, the optical axis direction passing through the center of the pyroelectric body 10, the image point distance of the lens 5, and the pyroelectric body. At least two or more detection areas are created by the viewing angle determined by the shape of 10.

With this configuration, the lens 5 and the pyroelectric body 10
It suffices to adjust only the optical positional relationship of the light beams, and since there is no obstruction that blocks the light flux after passing through the lens 5, the light flux does not change even if the movable amount of the lens 5 is uneven, and a uniform output is obtained. It has become possible to detect the outputs of multiple detection areas simultaneously.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 7 schematically shows a pyroelectric infrared sensor according to the fourth embodiment of the present invention. The difference from the first embodiment is that
That is, the aperture 11 has at least two openings.

The operation of the pyroelectric infrared sensor constructed as described above will be described with reference to FIG.

First, the infrared rays 8 emitted from the object to be detected in the field of view pass through the aperture 11 and are imaged by the lens 5 after passing through the infrared incident window 3 on the pyroelectric body 4 located on the image point. At this time, the detection direction changes as the lens 5 moves left and right in the direction perpendicular to the optical axis direction, so that the opening portion and the blocking portion of the aperture 11 are detected alternately, and the incident light enters the pyroelectric body 4. As a result, the amount of light emitted changes, resulting in a chopping effect. At this time, when there are at least two apertures in the aperture 11, the optical axis direction passing through the center of the aperture of the aperture 11, the principal point of the lens 5 and the center of the pyroelectric body 4, the image point distance of the lens 5, and the focal point. Electric body 4
At least two or more detection areas are created by the viewing angle determined by the shape of.

With this configuration, it is only necessary to adjust the optical positional relationship between the lens 5 and the pyroelectric body 4, and since there is no obstacle that blocks the light flux after passing through the lens 5, the movable amount of the lens 5 is uneven. However, it is possible to obtain a uniform output without changing the luminous flux, and it is possible to detect the outputs of a plurality of detection areas at the same time.

Needless to say, similar results can be obtained by rotating the lens 5 as shown in FIGS. 9A to 9C in the first, second, third, and fourth embodiments.

Further, in the first, second, third, and fourth embodiments, as shown in FIG. 10, the lens has irregularities corresponding to the amount of phase modulation, and the groove depth of the irregularities is uniform over the entire area. By using the diffractive optical lens 13 having the uneven shape depending on the wavelength of the incident infrared ray, the lens can be downsized, so that the focal length can be shortened (for example, the focal length is 6 mm). The amount of movement in the system has also been reduced, making it possible to downsize the entire system.

Further, in the third and fourth embodiments, by forming at least two lenses, the amount of incident light changes by the number of lenses times when the lens moves for one cycle, and as a result, the detection frequency is increased. growing. as a result,
The number of samplings is increased, and the output accuracy is improved. Further, when the pyroelectric body is a thin film, the noise component of the output decreases as the detection frequency becomes higher, so that the S / N ratio can be improved.

(Fifth Embodiment) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. FIG.
Shows an outline of a pyroelectric infrared sensor according to a fifth embodiment of the present invention. Sealing can 2 having opening 1
An infrared entrance window 3 attached to the opening 1, a pyroelectric body 4 which is, for example, a thin film located in the sealing can 2, a front of the infrared entrance window 3, and the vicinity of the pyroelectric body 4. It is composed of a lens 5 having an image point distance and a drive unit 14 for moving the lens 5 vertically in the optical axis direction.

The operation of the pyroelectric infrared sensor constructed as described above will be described with reference to FIG.

First, the infrared rays 8 radiated from the object to be detected in the visual field are focused by the lens 5 on the pyroelectric body 4 located on the image point.
An image is formed after passing through the infrared incident window 3. At this time, lens 5
Is moved up and down in the optical axis direction, the imaging position moves up and down the pyroelectric body 4, and the amount of light changes depending on whether or not an image is formed on the pyroelectric body 4. It will have a chopping effect.

With this configuration, it is only necessary to adjust the optical positional relationship between the lens 5 and the pyroelectric body 4, and since there is no obstacle that blocks the light flux after passing through the lens 5, the movable amount of the lens 5 is uneven. However, the light flux does not change, and it is possible to obtain a uniform output. Further, the movable amount of the lens 5 may be about the depth of focus of the lens 5 (several hundreds of micrometers), and the driving unit 14 can be downsized. , It became possible to downsize the entire system.

It should be noted that the lens has irregularities corresponding to the amount of phase modulation, the groove of the irregularities has a uniform depth over the entire area, and the irregular shape also serves as a diffractive optical lens depending on the wavelength of incident infrared rays. It goes without saying that similar results can be obtained.

(Embodiment 6) A sixth embodiment of the present invention will be described below with reference to the drawings. FIG.
Shows a schematic of a pyroelectric infrared sensor according to a sixth embodiment of the present invention. The difference from the first embodiment is that the driving unit 16 has a function of bending the lens 15.

The operation of the pyroelectric infrared sensor constructed as above will be described with reference to FIGS. 14 (a) and 14 (b).

First, the infrared rays 8 radiated from the object to be detected in the visual field are moved by the lens 15 to the pyroelectric body 4 positioned on the image point.
An image is formed after passing through the infrared incident window 3. At this time, lens 1
Because the focal length of the lens 15 changes due to the bending of the lens 5, the image forming position moves up and down on the pyroelectric body 4, and the amount of light changes depending on whether or not an image is formed on the pyroelectric body 4. As a result, it will have a chopping effect.

With this configuration, the lens 15 and the pyroelectric body 4 are
It suffices to adjust only the optical positional relationship between the lens 1 and the lens 1 because there is no obstacle that blocks the light flux after passing through the lens 15.
Even if the movable amount of 5 is not uniform, the light flux does not change, and it is possible to obtain a uniform output.

By using an organic material such as polyethylene, which transmits infrared rays having a wavelength of about 10 micrometers, as the lens material, it is possible to bend the material more easily than the spring constant of the material, and as a result, the driving force becomes small. The drive unit 16 can be downsized and power consumption can be reduced.

[0045]

As described above, according to the present invention, by directly moving the lens, it suffices to adjust only the optical positional relationship between the lens and the pyroelectric body, and there is no blocker that blocks the light flux after passing through the lens. Therefore, it is possible to provide a pyroelectric infrared sensor in which the light flux does not change even when the amount of lens movement is uneven, and the output is uniform.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing the same operation.

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

FIG. 4 is an explanatory diagram showing the same operation.

FIG. 5 is a schematic diagram of a pyroelectric infrared sensor according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the same operation.

FIG. 7 is a schematic diagram of a pyroelectric infrared sensor according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing the same operation.

FIG. 9 is a schematic view of a pyroelectric infrared sensor according to the first, second, third, or fourth embodiment of the present invention.

FIG. 10 is a schematic view of a pyroelectric infrared sensor according to the first, second, third, or fourth embodiment of the present invention.

FIG. 11 is a schematic diagram of a pyroelectric infrared sensor according to a fifth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing the same operation.

FIG. 13 is a schematic diagram of a pyroelectric infrared sensor according to a sixth embodiment of the present invention.

14A and 14B are explanatory views showing the same operation.

FIG. 15 is a schematic sectional view of a conventional pyroelectric infrared sensor.

[Explanation of symbols]

 1 Opening 2 Sealing Can 3 Infrared Incident Window 4 Pyroelectric Body 5 Lens 6 Driving Section 7 Aperture 8 Infrared 9 Lens 10 Pyroelectric Body 11 Aperture 12 Driving Section 13 Diffractive Optical Lens 14 Driving Section 15 Lens 16 Driving Section 17 Wing 18 Chopper

Claims (8)

[Claims] 1. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. A pyroelectric infrared sensor comprising a lens having an image point distance in the vicinity of an electric body, a driving unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and an aperture positioned in front of the lens. 2. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. A lens having an image point distance in the vicinity of the electric body, a drive unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and an aperture positioned in front of the lens,
A pyroelectric infrared sensor comprising at least two lenses. 3. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. It comprises a lens having an image point distance near the body, a drive unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and an aperture positioned in front of the lens, and the pyroelectric body has at least 2 Pyroelectric infrared sensor consisting of more than one. 4. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. A lens having an image point distance near the body, a drive unit for moving the lens left and right in a direction perpendicular to the optical axis direction, and an aperture positioned in front of the lens, and at least two apertures or more. Infrared sensor with an opening. 5. The pyroelectric infrared sensor according to claim 1, wherein the lens is rotated as a driving unit. 6. A lens is a diffractive optical lens having concavities and convexities corresponding to the phase modulation amount thereof, the groove depth of the concavities and convexities is uniform over the entire area, and the concavo-convex shape depends on the wavelength of incident infrared rays. The pyroelectric infrared sensor according to claim 1, 2, 3, or 4. 7. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. A pyroelectric infrared sensor including a lens having an image point distance near the body and a driving unit for moving the lens up and down with respect to the optical axis direction. 8. A sealing can having an opening, an infrared incident window attached to the opening, a pyroelectric body located in the sealing can, and a pyroelectric element located in front of the infrared incident window. A pyroelectric infrared sensor including a lens having an image point distance near the body and a driving unit for bending the lens.