JPH05133803A - Infrared-detecting element - Google Patents

Abstract

PURPOSE:To improve the infrared detection response of an infrared detecting element by making the entire body of the detecting element simpler and smaller in size by eliminating such inconvenience that a desired lens must be fitted to the outside of the detecting element when the detecting element is used for detecting a human body, etc., and, at the same time, eliminating the light loss caused by the lens. CONSTITUTION:This infrared detecting element has an infrared ray transmissive filter 3 provided on the upper surface of a hermetic-sealed case 1 and an infrared ray photodetector 4 for detecting infrared rays transmitted through the filter 3 provided in the case 1. In addition, the filter 3 is integrally formed with a lens R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detecting element suitable for use in an infrared detecting device for detecting a human body by detecting infrared rays emitted from a human body existing in a predetermined detection area.

[0002]

2. Description of the Related Art Conventionally, as an infrared detecting element used in an infrared detecting device for detecting a human body, there is one shown in FIG. 4, for example. In this conventional device, an infrared light receiving element 4e for infrared detection such as a pyroelectric element or a thermopile is provided in a hermetically shielded case 1e, and an infrared ray having a constant wavelength (for example, 8 Infrared transmission filter 3e for blocking electromagnetic waves other than (.about.13 μm) is provided. By using the infrared transmission filter 3e, it is possible to block ambient light from other than the human body, for example, sunlight, headlights, indoor lighting, etc., and prevent malfunction of the infrared detection device. By the way, in the prior art, when the infrared detecting element is used for human body detection, the infrared detecting element and the condenser lens Re are separately manufactured and assembled so that their optical axes coincide with each other.

[0003]

However, in the conventional means using other lens Re, the process for assembling the lens Re to the infrared detecting element is complicated and the manufacturing cost is high, and the space for mounting the lens is also large. However, there is a problem that the infrared detection device becomes extra bulky and large in size because it is necessary to secure the above. Further, as an important problem, in the above-mentioned conventional technique, when light passes through the lens Re,
Light loss occurs due to the lens Re. That is, polyethylene or the like is generally applied as the material of the lens Re of this kind, and in such polyethylene, the light transmittance is 40% at a thickness of 1 mm, and the light transmittance is poor, and a considerable amount is present at the position of the lens Re. Infrared rays are blocked. Therefore, the amount of infrared light received on the infrared detection element side is reduced, and the infrared detection response of the infrared light receiving element 4e becomes dull by the reduced amount of light.

Therefore, the present invention eliminates the inconvenience of externally attaching a desired lens to an infrared detection element when applied to an infrared detection apparatus for detecting a human body and the like, and thus the entire apparatus is provided. The object is to make it simple and small, and to improve the response of infrared detection by eliminating the light loss due to the lens.

[0005]

An infrared detecting element according to the present invention, which is proposed to achieve the above object, is provided with an infrared transmitting filter on the upper surface of a hermetically shielded case, and In an infrared detecting element in which an infrared receiving element for detecting infrared rays transmitted through the infrared transmitting filter is provided in the case, a lens is integrally formed in the infrared transmitting filter.

In the infrared detecting element according to the present invention as defined in claim 2, in the structure according to claim 1, a plurality of the lenses are formed on the back surface side of the infrared transmitting filter, and the light of each lens is formed. The axis is configured to focus on the center of the light receiving surface of the infrared light receiving element.

[0007]

In the infrared detecting element according to the present invention having the above-mentioned structure, the infrared rays passing through the infrared transmitting filter are collected or dispersed by the lens integrally formed with the infrared transmitting filter. In this state, it is absorbed by the infrared light receiving element and infrared rays are detected. Therefore, it is not necessary to separately attach a condensing or light-dispersing lens separately from the infrared detecting element according to the present invention. If the lens is formed as a converging convex lens,
An infrared image obtained by narrowing the viewing angle can be obtained, and conversely, if it is formed as a concave lens, the viewing angle can be enlarged and a reduced image can be obtained. In addition, it is not necessary to use the lenses individually, and because the lenses are formed integrally with the infrared transmission filter, an increase in the number of parts for transmitting light is avoided, so that the infrared reception light Loss can be reduced. Therefore, the amount of infrared light received at the position of the infrared light receiving element can be increased, and the responsiveness of infrared detection can be improved.

In the infrared detecting element according to the present invention as defined in claim 2, since the infrared rays transmitted through the plurality of lenses formed in the infrared transmitting filter are focused on the center of the light receiving surface of the infrared receiving element, the infrared transmitting filter. The light receiving efficiency of infrared rays passing through is increased. Further, by forming the lens on the back surface of the infrared transmission filter, the surface of the infrared transmission filter can be formed flat, so that the dust adhesion to the infrared transmission filter surface can be suppressed or the adhered dust can be easily removed. ..

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of an infrared detecting element according to the present invention, and FIG. 2 is a bottom view of an infrared transmitting filter.

The infrared detecting element A is hermetically shielded, that is, a case 1 made of metal or the like which is hermetically sealed, an infrared transmitting filter 3 mounted at a position of an opening 1a in an upper portion of the case 1, The infrared transmission filter 3
The lens R is integrally formed on the lower surface (back surface) side of the above, and the infrared light receiving element 4 provided inside the case 1. Here, the infrared transmission filter 3 blocks electromagnetic waves of wavelengths other than infrared and transmits only infrared rays. For example, a silicon substrate 3a having a good infrared transmittance.
Is formed by vapor-depositing a multilayer film 3b of magnesium oxide having a high refractive index and magnesium fluoride having a low refractive index for blocking electromagnetic waves of wavelengths other than infrared rays.

The lens R is formed by processing the back surface side of the infrared transmission filter 3 on which the multilayer film 3b is not formed. In this embodiment, the diameter of the infrared transmission filter 3 is set as shown in FIG. A total of 12 condensing lenses R each having a convex curved surface and having a diameter considerably smaller than that of the above are formed. These lenses R are arranged on a concentric circle centered on the center point O2 of the infrared transmission filter 3 on the center line of the visual field of the infrared light receiving element 4, and the space efficiency is good over substantially the entire area of the infrared transmission filter 3. It is provided in a simple state. this house,
The four inner lenses R1 ... Are tilted by an angle of θ1 with respect to the center line of the field of view of the infrared light receiving element 4, and the eight outer lenses R2 ... Are tilted by an angle of θ2. Are provided so as to be focused on the center of the light receiving surface of the infrared light receiving element 4, that is, the visual field center point O1. In addition, in the present invention, each of the lenses R can be configured as a Fresnel lens. In this case, as a Fresnel lens forming means, a silicon substrate 3a of the infrared transmitting filter 3 is coated with an electron beam resist, a desired lens pattern is formed by electron beam lithography, and ion beam etching is performed to form an electron beam resist. The shape may be transferred to the back surface side of the silicon substrate 1a. Usually, in a Fresnel lens, a so-called edge phenomenon is generated for obliquely incident light, and the phenomenon causes light loss. However, in the present embodiment, since the silicon used in the substrate 3a of the infrared transmission filter 3 having the lens R has a large refractive index of 3.4 with respect to infrared rays,
The light loss can be considerably reduced as compared with a polyethylene lens or the like. Therefore, there is almost no adverse effect of light loss due to the kicking phenomenon by the edge portion, and in the present invention, it is practical to use a Fresnel lens that can be easily processed and formed.

As the infrared light receiving element 4, similar to the conventional infrared detecting element, a pyroelectric type in which a voltage changes with a temperature rise due to infrared absorption, a thermistor type in which a resistance value changes with a temperature rise, or the like. However, any type may be used in the present invention. The infrared light receiving element 4 is supported by an appropriate supporting means 5 and fixed in the case 1, and the electrodes 4a and 4a led out of the case 1 are connected to the infrared light receiving element 4 which causes infrared light reception. It is possible to externally detect changes in voltage, resistance value, and the like.

In the infrared detecting element A having the above structure,
When infrared rays are transmitted from the outside into the infrared transmission filter 3, the infrared rays are condensed by a plurality of lenses R ... Formed on the back surface side of the infrared transmission filter 3 and reach the infrared light receiving element 4. Then, the temperature of the infrared light receiving element 4 changes, and the change of the voltage value or the resistance value of the infrared light receiving element 4 due to the temperature change is changed by the electrodes 4a, 4a.
Can be detected through. Since the infrared light received by the infrared light receiving element 4 is collected by the lens R ..., Even if the infrared light received by the infrared detecting element A is small, it is collected. It is possible to increase the detection sensitivity. That is, by condensing infrared rays with the lens R provided in the infrared transmission filter 3, the same action as that of enlarging the infrared image can be obtained by narrowing the viewing angle received by the infrared light receiving element 4. Therefore, the infrared detecting element A can be directly used for human body detection and the like without attaching a condenser lens to the outside. In particular, in this embodiment, since the respective optical axes of the plurality of lenses R ... Are focused on the center O1 of the visual field of the light receiving surface of the infrared light receiving element 4, all infrared rays transmitted through these lenses R. The light is condensed at the center point O1 of the element 4, and its light collection efficiency becomes very good. Also, since it is not necessary to attach a condenser lens externally,
The loss of light generated by the external lens can be eliminated, and since the lens R is formed integrally with the infrared transmission filter 3, the number of parts that transmit infrared rays does not increase at all. Therefore, the light loss of infrared rays before reaching the infrared light receiving element 4 can be reduced,
The infrared detection sensitivity of the infrared light receiving element 4 can be further increased.

In the above embodiment, a plurality of lenses R ...
Although each optical axis is focused on the visual field center point O1 on the surface of the infrared light receiving element 4, the present invention according to claim 1 is not limited to such a configuration. For example, as shown in FIG. 3, the entire rear surface of the infrared transmission filter 3 may be formed as one condenser lens R. Even in such a case, it goes without saying that the lens R can be formed as a Fresnel lens. However, in order to increase the efficiency of collecting infrared rays that enter the infrared transmission filter 3 at various angles, it is preferable to use the configuration shown in FIGS. 1 and 2 above that shown in FIG.
In the present invention according to claim 1, the lens is not limited to being formed as a convex lens, but may be formed as a concave lens. When the concave lens is formed, the infrared rays to be received can be dispersed, so that the viewing angle received by the infrared light receiving element 4 can be expanded and the infrared image can be reduced.

[0015]

As described above, according to the infrared detecting element of the present invention as defined in claims 1 and 2, when applied to an infrared detecting device for detecting a human body, a desired lens can be detected by infrared rays. Since it is not necessary to attach it externally to the element, the entire infrared detection device can be manufactured easily and compactly, and the loss of light due to the external lens as in the past can be eliminated, and the infrared detection response There is a special effect that it can improve the sex. In particular, according to the infrared detecting element of the present invention as defined in claim 2, the infrared rays transmitted through the plurality of lenses formed in the infrared transmitting filter can be focused on the center of the light receiving surface of the infrared receiving element. There is an advantage that it is possible to improve the light receiving efficiency of the light and further improve the response of infrared detection. Further, since the front surface side of the infrared transmission filter can be formed flat by forming a lens on the back surface of the infrared transmission filter,
There is also an advantage that dust can be prevented from adhering to the surface of the infrared transmission filter, or the attached dust can be easily removed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an infrared detection element according to the present invention.

FIG. 2 is a bottom view showing an example of a lens formed on an infrared transmission filter.

FIG. 3 is a cross-sectional view showing another example of the lens formed on the infrared transmission filter.

FIG. 4 is a sectional view showing an example of a conventional infrared detection element.

[Explanation of symbols]

 1 Case 3 Infrared transmission filter 4 Infrared light receiving element R Lens O1 Center of light receiving surface (viewpoint center point)

Claims (2)

[Claims] 1. An infrared detecting device comprising an hermetically shielded case having an infrared transmitting filter provided on an upper surface thereof, and an infrared receiving element for detecting infrared rays transmitted through the infrared transmitting filter provided in the case. An infrared detecting element, wherein a lens is formed integrally with the infrared transmitting filter. 2. The infrared lens according to claim 1, wherein a plurality of the lenses are formed on the back surface side of the infrared transmitting filter, and the optical axis of each lens is focused on the center of the light receiving surface of the infrared light receiving element. An infrared detection element characterized by the above.