JPH0886692A - Pyroelectric sensor element and production thereof - Google Patents

Abstract

PURPOSE: To produce a micro sensor element having a simple structure efficiently. CONSTITUTION: A thin metal film 7 is formed on the surface of a rectangular sensor board 6 exhibiting pyroelectric effect while leaving the marginal parts at the opposite ends on the short side of the rectangle. On the rear side of the sensor board 6, electrodes of thin metal film 8 are formed at the opposite end parts on the short side of the rectangle so that the electrodes face the thin metal film 7 formed on the surface at least partially through the sensor board 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric sensor element for converting infrared rays into electric signals by utilizing the pyroelectric effect and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, for example, a so-called dual type of a pyroelectric infrared sensor element is shown in FIG.
The concave electrodes 2 are vapor-deposited in a matrix on the surface of the ceramic substrate 1 having a pyroelectric effect, and the electrodes 3 are vapor-deposited on the back surface so as to correspond to both ends of the concave electrodes 2 on the surface. After forming these electrodes, the sensor element 5 was formed by dividing each electrode 2 by the dividing line 4. This sensor element 5 is about 5 m
It was formed in a case having a square shape of m square and having a light receiving window, and was housed together with an FET or the like for impedance conversion of an output signal from this sensor element.

[0003]

However, in the case of the above conventional technique, it cannot be said that the sensor element 5 is efficiently formed from the ceramic substrate 1 forming the sensor element 5, and the sensor element itself is useless. There was space. Therefore, the use efficiency of the ceramic substrate 1 is poor, which hinders downsizing and cost reduction of the sensor element.

The present invention has been made in view of the above problems of the prior art, and provides a pyroelectric sensor element capable of efficiently forming a small sensor element with a simple structure and a manufacturing method thereof. The purpose is to

[0005]

According to the present invention, a thin metal film is formed on the surface of a rectangular sensor substrate such as PZT having a pyroelectric effect, leaving both ends on the short side of the rectangle slightly left. On the back side of, the metal thin film on the front side is separated from the metal thin film on the front side by a metal thin film, and the electrodes are separated at the center of the substrate so that they face each other across the sensor substrate. The formed pyroelectric sensor element.

Further, according to the present invention, metal thin films are formed in stripes on the front surface of the substrate having a pyroelectric effect at predetermined intervals, and similarly, metal thin films are formed on the back surface in stripes at predetermined intervals.
A metal thin film on the front surface and a metal thin film on the back surface are formed at positions facing each other in the gaps between the stripes, and this substrate is divided in parallel with the metal thin film at the portion between the metal thin films on the front surface side and the back surface. The metal thin film on the side is divided into two parts, and the substrate is also divided in the direction perpendicular to the longitudinal direction of the metal thin film, and the side in the longitudinal direction of the metal thin film becomes the short side in the state after the division. It is a method of manufacturing a pyroelectric sensor element for forming a rectangular sensor element.

[0007]

The pyroelectric sensor element and the manufacturing method thereof according to the present invention are
A large number of pyroelectric sensor elements can be efficiently obtained from a single substrate, and the sensor element itself can be miniaturized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the pyroelectric sensor element 5 of this embodiment, as shown in FIGS. 1 and 2, a metal thin film 7 of Ni, Cr or Ag is formed on the surface of a sensor substrate 6 made of a ferroelectric ceramic such as PZT or PT. ing. This metal thin film 7 is shown in FIG.
As shown in (A), the rectangular sensor substrate 6 is formed with both ends on the short side left. In addition, as shown in FIG. 1B, on the back surface of the sensor substrate 6, metal thin films 8 serving as electrodes independent from each other are formed at both ends of the short side of the rectangle, leaving the substrate center. There is. This sensor board 6
Has a long side to short piece ratio of about 2: 1.

In the method for manufacturing the pyroelectric sensor element 5, first, the ceramic substrate 1 for dividing the sensor element 5 to obtain a large number is formed, and after polarization processing is performed, the surface side of the ceramic substrate 1 is The mask 30 shown in FIG. 3 is placed and the metal thin film 7 is vapor-deposited. Similarly, the metal thin film 8 as an electrode material is vapor-deposited on the back surface using the mask 32 shown in FIG. Openings 34 and 36 for forming the metal thin films 7 and 8 are formed in the masks 30 and 32, respectively, and a through hole 38 for alignment is also formed in each of them. As a result, the metal thin films 7 and 8 are formed in stripes at predetermined intervals. The metal thin films 7 and 8 are formed at positions where the metal thin film 7 on the front surface and the metal thin film 8 on the back surface face each other in the gap between the stripes.

After that, the substrate 1 is divided into individual sensor elements 5. The dividing method is that the metal thin film 7 on the front surface side is divided in parallel with the metal thin film 7, and the metal thin film 8 on the back surface side is divided.
Is divided into two parts. At the same time, the substrate 1 is divided in the direction perpendicular to the longitudinal direction of the metal thin film 7,
As shown in FIG. 1, the divided sensor element 5 is formed in a rectangular shape in which the sides in the longitudinal direction of the metal thin films 7 and 8 are short sides.

The pyroelectric sensor element 5 of this embodiment is shown in FIG.
As shown in FIG. 6, the housing is housed in a hermetic base 10 that is a disk-shaped metal bottom plate that constitutes a case body, and a cylindrical hermetic metal cap 12 that covers the hermetic base 10. A light receiving window 16 is formed in the center of the upper surface of the cap 12, and an infrared incident filter 17 is formed in the light receiving window 16.
Is attached.

The ceramic substrate 20 shown in FIGS. 5 and 6 is placed on the hermetic base 10, and the resistor 21 and the FET 22 are soldered to the circuit pattern 18 formed on the surface of the ceramic substrate 20. It is installed. Further, on the ceramic substrate 20, the base end portions of the pair of metal columns 24 supporting the sensor element 5 are fixed by solder and connected to the circuit pattern 18.
The support column 24 is, for example, a copper round bar solder-plated, the sensor element 5 is supported by the two support columns 24, and electrical connection between the sensor element 5 and the ceramic substrate 20 is also achieved. . The sensor element 5 is placed on the tip of the support column 24, and is fixed by, for example, a conductive adhesive 26 in which silver or the like is mixed with epoxy resin.

Three lead terminals 28 pass through the peripheral portions of the hermetic base 10 and the ceramic substrate 20. The lead terminal 28 is the support column 2 supporting the sensor element 5.
It is separate from 4, and penetrates through the hermetic base 10 and the ceramic substrate 20, and its tip end is connected to the circuit pattern 18 on the ceramic substrate 20 by the solder 30 and fixed to the ceramic substrate 20. And
It is connected to the FET 22 and the like on the ceramic substrate 20 via the circuit pattern 18 on the ceramic substrate 20.

The peripheral edge of the cap 12 is resistance-welded to the peripheral edge of the hermetic base 10 to completely seal the inside. The inside of the case body is filled with nitrogen gas, and the influence of characteristic changes due to changes in the external environment is suppressed.

The operation of the pyroelectric sensor element of this embodiment is as follows. First, when there is no infrared radiator in the field of view of the sensor element 5,
The output signal from the sensor element 5 is only noise, and no detection signal is output. On the other hand, when an infrared radiator such as a person passes through the field of view of the sensor element 5, the output signal from the sensor element 5 fluctuates positively and negatively when a person enters and exits. Then, the detection signal whose impedance is converted to a predetermined level by the FET 22 is output from the lead terminal 28.

According to the pyroelectric sensor element of this embodiment, the sensor element 5 can be efficiently divided from the ceramic substrate 1 and a large number can be taken, and the pyroelectric sensor element 5 can be taken from one ceramic substrate 1. This greatly increases the number of devices, which contributes to cost reduction and also contributes to downsizing of the sensor device. The size of the sensor element 5 can be appropriately selected, and the number, shape, or width of the metal thin film that is the electrode can be appropriately set.

Next, another embodiment of the pyroelectric sensor element of the present invention will be described with reference to FIG. Here, the same members as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.
In this embodiment, a rectangular sensor substrate 6 having a pyroelectric effect is used.
A metal thin film 7 is formed on a part of the surface of the sensor substrate 6, and an electrode formed by the metal thin film 8 is also formed on the back surface of the sensor substrate 6 so as to face the metal thin film 7 with the sensor substrate 6 interposed therebetween. At least a part of the metal thin films 7 and 8 may be overlapped on the front and back sides with the sensor substrate 6 interposed therebetween, and the size and the number thereof can be set appropriately.

In the method for manufacturing the pyroelectric sensor element of this embodiment, the metal thin films 7 are formed in stripes on the front surface of the substrate 1 having a pyroelectric effect at predetermined intervals, and similarly, on the back surface are also formed in stripes at predetermined intervals. The metal thin film 8 is formed. At this time, the metal thin film 7 on the front surface and the metal thin film 8 on the back surface are formed so that a part thereof faces each other with the sensor substrate 6 interposed therebetween. Then, the metal thin films 7 and 8 are each divided in a direction parallel to the longitudinal direction of the stripes of the metal thin films 7 and 8. Further, the substrate 1 is divided also in the direction perpendicular to the longitudinal direction of the metal thin films 7 and 8, and the rectangular sensor element 5 in which the side in the longitudinal direction of the metal thin films 7 and 8 is the short side is formed after the division. .

The pyroelectric sensor element of this embodiment has the same effect as that of the above-mentioned embodiment, and can be applied to pyroelectric sensor elements other than the dual type.

[0020]

The pyroelectric sensor element of the present invention has a simple structure and can be divided into a large number of sensor elements from a multi-piece substrate, contributing to cost reduction and downsizing of the sensor device. Can be planned.

[Brief description of drawings]

FIG. 1 is a diagram showing a front surface (A) and a back surface (B) of a pyroelectric sensor element according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of a ceramic substrate from which a pyroelectric sensor element of this example is obtained.

FIG. 3 is a plan view of a mask for vapor deposition on the front surface side for obtaining the pyroelectric sensor element of this embodiment.

FIG. 4 is a plan view of a mask for vapor deposition on the back surface side for obtaining the pyroelectric sensor element of this embodiment.

FIG. 5 is a perspective view of a sensor device to which the pyroelectric sensor element of this embodiment is attached.

FIG. 6 is a vertical cross-sectional view of the pyroelectric sensor device of this embodiment.

FIG. 7 is a plan view of a pyroelectric sensor element according to another embodiment of the present invention.

FIG. 8 is a plan view of a conventional pyroelectric sensor element.

[Explanation of symbols]

 1 substrate 5 sensor element 6 sensor substrate 7, 8 metal thin film

Claims (4)

[Claims] 1. A metal thin film is formed on the surface of a rectangular sensor substrate having a pyroelectric effect.
A pyroelectric sensor element in which an electrode made of a metal thin film is formed at a position where at least a portion of the sensor substrate faces the metal thin film on the front surface side of the sensor substrate. 2. A rectangular sensor substrate surface having a pyroelectric effect, a metal thin film is formed on the surface of the rectangular sensor substrate, leaving both ends on the short side of the rectangle.
A pyroelectric sensor element in which electrodes, which are independent of each other, are formed of metal thin films at both ends on the short side of a rectangle. 3. A metal thin film is formed in stripes on a front surface of a substrate having a pyroelectric effect at predetermined intervals, and similarly, metal thin films are formed on the back surface in stripes at predetermined intervals. The metal thin film and the metal thin film partially face each other with the sensor substrate interposed therebetween, and the substrate is divided in parallel with the metal thin film on the front surface side, and the substrate is also divided in the direction perpendicular to the longitudinal direction of the metal thin film. A method for manufacturing a pyroelectric sensor element, comprising forming a rectangular sensor element in which a side in a longitudinal direction of the metal thin film is a short side in a state after being divided. 4. A metal thin film is formed in stripes on a front surface of a substrate having a pyroelectric effect at predetermined intervals, and a metal thin film is also formed on the back surface in stripes at predetermined intervals. A metal thin film is formed at a position facing each other in the gap between the stripes, the substrate is divided parallel to the metal thin film in the portion between the metal thin films on the front surface side, and the metal thin film on the back surface side is divided into two parts. And the substrate is also divided in the direction perpendicular to the longitudinal direction of the metal thin film, and a rectangular sensor element whose longitudinal side is the short side is formed in the state after the division. Method for manufacturing an electric sensor element.