JP2001272274A - Pyroelectric infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive infrared sensor by enhancing collecting efficiency for infrared rays and improving a sensitivity. SOLUTION: This pyroelectric infrared sensor includes at least a sensor element, a sensor element supporter for supporting the sensor element and a circuit board. In the pyroelectric infrared sensor, an optical filter and a compound lens are arranged above the sensor element, and the optical sensor has a lens effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pyroelectric infrared sensor having a small infrared sensor element for detecting infrared rays radiated from an object such as a human body.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view showing a conventional pyroelectric infrared sensor. FIG. 2 is a top view of the pyroelectric infrared sensor of FIG. The pyroelectric infrared sensor shown in FIG.
Are supported on the circuit board 3 by the sensor element support 2. A front surface electrode and a back surface electrode (both not shown) are formed on the front and back surfaces of the sensor element 1 by vapor deposition or sputtering. The sensor element support 2 is made conductive by a conductive material or conductive plating, and the sensor element 1, the sensor element support 2 and the circuit board 3 are electrically connected by a conductive adhesive or the like.

Reference numeral 4 denotes a compound eye lens which is formed in a dome shape. 5 is an optical filter. The compound eye lens 4 and the optical filter 5 are arranged above the sensor element 1 so that their centers are aligned. The infrared light having a certain wavelength that has passed through the compound eye lens 4 and the optical filter 5
Is generated, a charge proportional to the amount of infrared light received is generated by the pyroelectric effect of the sensor element 1, and a voltage generated by this charge is taken out from the lead 7 attached to the base 6 through the circuit board 3. Has become. The base 6 and the lead 7 are insulated by a hermetic seal or the like. In addition, 8 is a cap.

The pyroelectric infrared sensor filters using an optical filter 5 in accordance with the wavelength of the infrared light emitted from the object to be measured. Normally, an infrared transmitting material such as Si or Ge is used as an optical filter, and a thin film of ZnS, SiO or the like is formed on the surface thereof in a total of about 100 layers. Thus, a predetermined optical characteristic (wavelength band) is obtained. For the purpose of detecting a human body, selective detection of infrared rays near 10 μm is required, and a 5 μm or 6.5 μm cut-on long wavelength transmission filter is usually used.

In addition, the pyroelectric infrared sensor uses a lens according to the application in order to obtain a viewing angle and a detection distance. The lens is mainly made of polyethylene. The pyroelectric infrared sensor shown in the conventional example has a dome-shaped compound eye lens 4 for the purpose of reliably detecting a human body in a wide area.

FIGS. 3A and 3B are views showing a compound eye lens, wherein FIG. 3A is a top view, and FIG. 3B is a sectional view taken along line AA of FIG. The compound eye lens 4 is formed in a dome shape, and each of the plurality of lenses 4a formed in the dome collects infrared rays in the detection area. The focus of the lens is designed to be as close as possible to the center of the sensor element 1.

[0007]

Normally, the infrared light condensed by the compound eye lens does not converge at one point in the center of the element, but becomes a spotted pattern (a defocused image) at the center of the element. Inefficient. For this reason, the sensitivity of the pyroelectric infrared sensor has been reduced.

The optical filter and the compound eye lens are important parts constituting the pyroelectric infrared sensor, but each is made of a different material, so that the cost is high. For optical filters, special coating and other processes have been added, increasing the number of production steps. SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive infrared sensor that increases the efficiency of condensing infrared light, improves sensitivity, and reduces the cost.

[0009]

A pyroelectric infrared sensor comprising at least a sensor element, a sensor element support for supporting the sensor element, and a circuit board, wherein an optical filter and a compound eye lens are disposed above the sensor element. Is a pyroelectric infrared sensor having a lens function.

The optical filter is a pyroelectric infrared sensor formed of barium fluoride.

In a pyroelectric infrared sensor having at least a sensor element, a sensor element support for supporting the sensor element, and a circuit board, wherein an optical filter and a compound eye lens are disposed above the sensor element, the optical filter and the compound eye lens are fluorinated. A pyroelectric infrared sensor integrally formed of barium.

[0012]

FIG. 4 is a sectional view of a pyroelectric infrared sensor according to an embodiment of the present invention. The same parts as those in the conventional example are denoted by the same reference numerals.

The sensor element 1 is supported on a circuit board 3 by a sensor element support 2. A front surface electrode and a back surface electrode (both not shown) are formed on the front and back surfaces of the sensor element 1 by vapor deposition or sputtering. The sensor element support 2 is made conductive by a conductive material or conductive plating, and the sensor element 1, the sensor element support 2, and the circuit board 3 are provided.
Are electrically connected by a conductive adhesive or the like.

Reference numeral 4 denotes a compound eye lens which is formed in a dome shape. The material is polyethylene. 9 is an optical filter. The compound eye lens 4 and the optical filter 9 are arranged above the sensor element 1 so that their centers are aligned. When infrared rays of a certain wavelength that have passed through the compound eye lens 4 and the optical filter 9 are projected onto the sensor element 1, charges proportional to the amount of received infrared light are generated due to the pyroelectric effect of the sensor element 1, and the charges are generated by the charges. The structure is such that voltage is taken out from the leads 7 attached to the base 6 through the circuit board 3. The base 6 and the lead 7 are insulated by a hermetic seal or the like. 8 is a cap.

The optical filter 9 is formed in a lens shape.
It has a lens function. The infrared rays are condensed to some extent by the compound eye lens 4 at the center of the sensor element, but are defocused and not completely condensed. Therefore, the optical filter 9 is formed in a lens shape, and infrared rays are further condensed by another lens so as to be surely condensed on the surface center of the sensor element 1.

The optical filter 9 having the lens function is preferably made of barium fluoride. Barium fluoride has a property of transmitting infrared rays having a wavelength of 5 μm or more and not transmitting other wavelengths. Therefore, it is suitable for applications such as human body detection. The infrared radiation emitted by the human body has a wavelength of about 10 μm. Further, since barium fluoride has a property of refracting light, it can be used as a material of a lens, so that the pyroelectric infrared sensor described in one embodiment of the present invention can be configured.

FIG. 5 is a sectional view of a pyroelectric infrared sensor according to another embodiment of the present invention. The same reference numerals are used for the same parts as in the conventional example and the embodiment.

The sensor element 1 is supported on a circuit board 3 by a sensor element support 2. A front surface electrode and a back surface electrode are formed on the front and back surfaces of the sensor element 1, and a voltage generated by the pyroelectric effect is extracted to the outside via the sensor element support 2. Reference numeral 10 denotes a dome-shaped compound eye lens formed of barium fluoride. Compound eye lens 10
Is formed by powder molding. By shaping and forming powdered barium fluoride in a mold, the shape becomes free, and a convex shape or a dome shape such as a lens can be easily formed. By forming the compound eye lens 10 as described above, both the lens function and the filter function can be provided, and the conventional lens and the optical filter can be integrated. Therefore, the number of parts can be reduced.

[0019]

According to the present invention, since the optical filter is formed in a lens shape, infrared rays which cannot be condensed by the compound eye lens can be further condensed, and the sensitivity of the pyroelectric infrared sensor can be improved.

According to the second aspect of the present invention, since the lens and the optical filter can be integrated, the number of components can be reduced, and an inexpensive pyroelectric infrared sensor can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a conventional pyroelectric infrared sensor.

FIG. 2 is a top view of the pyroelectric infrared sensor of FIG. 1;

FIG. 3 is a view showing a compound eye lens, (a) is a top view,
(B) is an AA cross-sectional view of (a).

FIG. 4 is a cross-sectional view of a pyroelectric infrared sensor showing one embodiment of the present invention.

FIG. 5 is a sectional view of a pyroelectric infrared sensor showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor element 2 Sensor element support 3 Circuit board 4 Compound eye lens 5 Optical filter 6 Base 7 Lead 8 Cap 9 Optical filter 10 Compound eye lens

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Claims (3)

[Claims] 1. A pyroelectric infrared sensor comprising at least a sensor element, a sensor element support for supporting the sensor element, and a circuit board, wherein an optical filter and a compound eye lens are disposed above the sensor element, wherein the optical filter has a lens function. A pyroelectric infrared sensor, comprising: 2. The pyroelectric infrared sensor according to claim 1, wherein said optical filter is made of barium fluoride. 3. A pyroelectric infrared sensor comprising at least a sensor element, a sensor element support for supporting the sensor element, and a circuit board, wherein an optical filter and a compound eye lens are disposed above the sensor element. A pyroelectric infrared sensor which is integrally formed of barium fluoride.