JPH081397B2 - Pyroelectric device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric film, a plurality of electrodes of a first group provided on one surface of the pyroelectric film, and the other surface of the pyroelectric film. A plurality of electrodes of a second group is provided, and each of the electrodes of the first and second groups makes a lead connection with an electrode body for providing an effective light receiving electrode area and another electric circuit. Therefore, each of the plurality of electrodes of the first group, each of the plurality of electrodes of the first group, and each of the first and second electrodes have a lead portion that is integrally drawn from the electrode body and extends. A pyroelectric element device in which a plurality of unit pyroelectric elements are constituted by the pyroelectric film interposed between a plurality of electrodes in each of two groups, and particularly to the electrode structure thereof, Is suitable for use in pyroelectric infrared sensors A.

[0002]

2. Description of the Related Art A pyroelectric infrared sensor for detecting an intruder used in the fields of security and automatic doors is required to have high reliability. Various researches and developments have been made on sensors. For example, U.S. Pat. No. 3,839,640 discloses that a pair of unit pyroelectric elements are connected in series or in parallel so that their polarities are opposite to each other to form a pyroelectric element. There is disclosed a pyroelectric element device in which a defect that is erroneously detected due to a change in room temperature or the incidence of disturbance light is improved. Also, JP-A-61-1755
No. 83, No. 58-32337, and European Patent No. 131996 are shown in FIGS. 1 (A), 2 (A) and 3 (A) in the accompanying drawings of the present application, respectively. Discloses an electrode structure of a pyroelectric element device including the above-described anti-pyroelectric element.

Next, the electrode structure of the pyroelectric element device comprising the pyroelectric element shown in FIGS. 1A, 2A and 3A will be described. In these drawings, parts corresponding to each other are denoted by the same reference numerals.

In these figures, reference numeral 1 denotes a pyroelectric film,
Reference numerals 2 and 3 are surface electrodes formed on the surface of the pyroelectric film 1. These electrodes 2 and 3 are provided with electrode main bodies 2a and 3a for providing an effective light receiving electrode area, lead portions 2b and 3b drawn out from these electrode main bodies 2a and 3a and extending, and these lead portions. 2b, 3b, and terminal portions 2c, 3c. Reference numerals 4 and 5 denote back electrodes formed on the back surface of the pyroelectric film 1. The electrodes 4, 5 are electrode bodies 4a, 5a for giving an effective light receiving electrode area, lead portions 4b, 5b extended from the electrode bodies 4a, 5a, and lead portions thereof. It is composed of terminal portions 4c and 5c constituted by the tip portions of 4b and 5b. The electrodes 2 and 3 are arranged point-symmetrically on the surface of the pyroelectric film 1, and the electrodes 4 and 5 are
Are arranged point-symmetrically on the back surface of the. And electrode 2
And 3 and the electrodes 4 and 5 are arranged so as to have the same shape on both sides of the pyroelectric film 1.

Therefore, the first unit pyroelectric element is constituted by the electrode 2, the electrode 4, and the portion of the pyroelectric film 1 interposed between the electrodes 2 and 4.
The electrode 3, the electrode 5, and the portion of the pyroelectric film 1 interposed between these electrodes 3 and 5 form the second
Are constituted. And these first
By connecting the second pyroelectric element and the second unit pyroelectric element in series or in parallel such that their polarities are opposite to each other, a pyroelectric element is configured. For example, these first
And the second unit pyroelectric element are connected in parallel such that their polarities are opposite to each other,
b, a terminal portion 2c composed of the tip of
The terminal portion 5c constituted by the tip portion of b is electrically connected to a common lead wire (not shown). Then, a terminal portion 3c constituted by a tip portion of the drawer portion 3b
And a terminal portion 4c constituted by a tip portion of the drawer portion 4b
Is electrically connected to another common lead wire (not shown) as in the case of the terminal portions 2c and 5c described above.

[0006]

[Problems to be Solved by the Invention] As described above,
Despite many researches and developments relating to a pyroelectric device including a pyroelectric device composed of a pair of first and second unit pyroelectric devices, such a pyroelectric device is used. When the pyroelectric infrared sensor is actually manufactured by using the technology of the pyroelectric element device, it is not always possible to obtain a sensor having excellent electrical characteristics against ambient light as expected,
Further, there are variations in the electrical characteristics with respect to ambient light between the manufacturing lots.

The above points will be described in more detail.
In order to prevent erroneous detection of ambient light from occurring in a pyroelectric element configured by connecting the second unit pyroelectric element in series or in parallel so that their polarities are opposite to each other, The electrical characteristics of the first and second unit pyroelectric elements with respect to ambient light must be the same. More specifically, these first
When the second unit pyroelectric element and the second unit pyroelectric element are connected in anti-parallel, when the infrared light, which is disturbance light, is simultaneously incident on the two unit pyroelectric elements, the amounts of charges generated by these two unit pyroelectric elements are mutually different. When connected in anti-series, it is necessary that when infrared light is simultaneously incident on the two unit pyroelectric elements, the generated potentials of these two unit pyroelectric elements are equal to each other. is there.

However, the actually manufactured pyroelectric element is
Even if the variations in the thickness, the dielectric constant and the pyroelectric coefficient of these two unit pyroelectric elements were reduced, the electrical characteristics against disturbance light alone were not improved.

As a result of diligent investigations and examinations of the cause, the present inventor has found that with normal mechanical precision, the pattern of the front surface electrode and the pattern of the back surface electrode formed on the front and back surfaces of the pyroelectric film are the same. It has been found that there is a positional shift between the unit pyroelectric elements, which results in a difference in the effective light receiving electrode area between the unit pyroelectric elements.

Next, this development will be further described with reference to FIGS. 1A to 3B for a pyroelectric device having a conventional electrode structure.

FIGS. 1A, 2A and 3A
In the pyroelectric element device shown in FIG. 1, the pattern of the front surface electrodes 2 and 3 of the pyroelectric film 1 and the pattern of the back electrodes 4 and 5 on the back side are slightly displaced from each other in the vertical and horizontal directions. (B), FIG. 2 (B) and FIG. 3 (B). Note that these FIG. 1 (B) and FIG.
In FIG. 3B and FIG. 3B, illustration of the pyroelectric film 1 is omitted. The hatched portions 7a and 7b are
The overlapping portions of the electrodes 2 and 4 and the overlapping portions of the electrodes 3 and 5 are shown. And the arrow
The lead portions 2b, 3b, 4b, and 5b are the respective electrode main bodies 2a,
3A, 3A, 4A, and 5A show directions in which each of them is drawn out and starts to extend.

In the case of FIG. 1B, a pair of hatched portions 7
The right shaded portion 7a of a and 7b is larger than the left shaded portion 7b by the portions 8a and 8b indicated by the double shaded lines at the upper and lower ends of the shaded portion 7a. Figure 2
In the case of (B), the left-side hatched portion 7b is lower at the upper and lower ends of the right-side hatched portion 7b than the right-side hatched portion 7a.
Only the portions 8a and 8b indicated by the heavy diagonal lines are enlarged. In the case of FIG. 3 (B), the shaded portion 7b on the left is larger than the shaded portion 7a on the right by the portion 8 indicated by double oblique lines at the base end of the lead portion 3b of the electrode 3. . The double-hatched portions 8a, 8b, 8 are portions where any of the lead portions 2b to 5b overlaps with any of the electrodes 2 to 5 on the opposite side via the pyroelectric film 1. The double hatched portions 8a, 8b, 8 correspond to the first and second portions.
It can be seen that the effective light receiving electrode areas of the unit pyroelectric elements are different from each other.

As described above, the double-hatched portions 8a, 8b,
The reason why 8 occurs is that FIGS. 1 (B), 2 (B) and 3
In (B), the lead portions 2b to 5b are connected to the electrode body 2a.
~ 5a direction to start extending from (5)
When the patterns of the electrodes 2 to 5 are displaced in the vertical and / or horizontal directions on the front and back surfaces of the pyroelectric film 1 because the drawing start directions are different from each other, the displacement between the electrodes 2 and 4 is This is because the state and the state of displacement between the electrode 3 and the electrode 5 are different from each other.

In order to solve such a problem, the surface electrodes 2 and 3 of the pyroelectric film 1 are designed to be smaller than the back electrodes 4 and 5 so that the electrode patterns may be slightly shifted between the front and back sides. As shown in FIG. 3 (A), a method for performing this is already known. However, even in the case of such a design, as shown in FIG.
The effective light receiving electrode area differs between the first and second unit pyroelectric elements.

Therefore, it is an object of the present invention to provide a pyroelectric element device in which a plurality of unit pyroelectric elements are connected in parallel, and which has excellent electrical characteristics with respect to ambient light.

[0016]

The present invention for attaining this object provides a pyroelectric element device as described at the beginning, comprising a first electrode of the first group and a first electrode of the second group. A first unit pyroelectric element is constituted by the pyroelectric film interposed between these two first electrodes,
A second unit pyroelectric element is constituted by the second electrode of the first group, the second electrode of the second group, and the pyroelectric film interposed between these two second electrodes, The first unit pyroelectric element has the first unit pyroelectric element connected in parallel to the second unit pyroelectric element with their polarization directions reversed from each other. And a lead portion of the lead portion of the first electrode of the first group, the lead portion of the lead electrode of the second electrode is connected to the lead electrode of the second electrode of the second group. The tip portion of the first electrode of the second electrode of the first group, the tip portion of the lead electrode of the second electrode of the first group is opposed to the tip portion of the first electrode of the second group. Hold the tip of the drawer and the pyroelectric film to However, even if the patterns of the plurality of electrodes of the first group are formed to be slightly displaced from the patterns of the plurality of electrodes of the second group, the first and the second groups of the first group are formed. The effective light-receiving electrode area formed by the overlapping portions of the second electrode and the first and second electrodes of the second group does not substantially differ between the unit pyroelectric elements. Each lead part of the plurality of electrodes of one group is
The directions in which the electrodes are pulled out of the electrode body and start to extend are substantially the same as each other, and the widths of the portions at which the extensions start are also substantially the same as each other, and
The lead-out portions of the plurality of electrodes of the second group have substantially the same direction in which they are pulled out from the electrode body and start extending, and the width of the extending start portion is also the same. Substantially the same size as each other.

[0017]

FIG. 4 (A) and FIG. 4 (B) show a pyroelectric device according to an embodiment of the present invention. Note that in FIGS. 4A and 4B, FIGS.
Parts common to those in FIG. 1B are denoted by the same reference numerals.

In FIG. 4A, reference numeral 1 is a pyroelectric film, front electrodes 2 and 3 are formed on the surface of the pyroelectric film 1, and back electrodes 4 and 4 are formed on the back surface. 5 is formed.

The electrodes 2 to 5 are substantially rectangular parallelepiped electrode bodies 2a to 5a for providing an effective light receiving electrode area, and these electrodes are used for lead connection with other electric circuits (not shown). Drawer portions 2b to 5b that are integrally drawn out from the main bodies 2a to 5a and extend, and these drawer portions 2b to 5
b of terminal portions 2c to 5c. The width of each of the lead portions 2b to 5b is narrower than that of the electrode bodies 2a to 5a. The electrode bodies 2a and 3a of the electrodes 2 and 3 have substantially the same shape, and the electrode bodies 4a and 5a of the electrodes 4 and 5 have substantially the same shape. However, the electrode bodies 4a and 5a are
In the case shown in FIG. 4 (A) in which there is no displacement between a and 3a, the electrode body 2a, 3a is provided with a protruding portion 11 over substantially the entire circumference thereof.

The lead portions 2b to 5b are connected to the electrode main body 2a to
The directions in which the base portions 9 are drawn out from 5a and start to extend are almost the same as each other, and the widths of the proximal end portions 9 which start to extend are almost the same as each other. In the text, the “same direction” means a parallel direction or a completely same direction and the same direction.

The lead-out portions 2b to 5b are a base end portion 9 extending in the same direction by a short length, and a portion 10 extending from the base end portion 9 in a substantially right angle direction and extending in a substantially L-shape. And consists of. The terminal portions 2c to 5c are formed at the tip of the portion 10. Also,
The drawers 2b to 5b are formed such that their base end portions 9 do not overlap each other. And electrode 2
The terminal portions 2c and 5c are opposed to each other on both sides of the pyroelectric film 1 at the edge of the pyroelectric film 1.
Similarly, the terminals 3c and 4c of the electrodes 3 and 4 are opposed to each other on the front and back sides of the pyroelectric film 1 at the edge of the pyroelectric film 1. The patterns of the front electrodes 2 and 3 and the patterns of the back electrodes 4 and 5 are almost symmetrical on the front and back of the pyroelectric film 1 except for the protruding portion 11.

Therefore, the electrode 2, the electrode 4, and the portion of the pyroelectric film 1 interposed between these electrodes 2 and 4 constitute a first unit pyroelectric element.
The electrode 3, the electrode 5, and the portion of the pyroelectric film 1 interposed between these electrodes 3 and 5 form the second
Are constituted. And these first
By connecting the second unit pyroelectric element and the second unit pyroelectric element in parallel so that their polarities are opposite to each other, a pyroelectric element device composed of an anti-pyroelectric element is configured. In this connection, in order to connect in parallel so that the polarities are opposite to each other, the terminal portion 2c of the front surface electrode 2 and the terminal portion 5c of the back surface electrode 5 are disclosed in JP-A-61-175583 and Europe. As disclosed in Japanese Patent Publication No. 131,996, they are each electrically connected to a common lead wire (not shown). In addition, the terminal portion 3 c of the front surface electrode 3 and the terminal portion 4 c of the back surface electrode 4 are the terminal portions 2 of the electrodes 2 and 5.
As in the case of c and 5c, each is electrically connected to another common lead wire (not shown).

FIG. 4B shows that in the pyroelectric device shown in FIG. 4A, the patterns of the front surface electrodes 2 and 3 and the patterns of the back surface electrodes 4 and 5 are in the vertical and horizontal directions by the width of the protruding portion 11. The state where they are displaced from each other is shown. Such misalignment is caused by the electrodes 2-5 on the pyroelectric film 1.
Often caused by manufacturing errors in forming the.

In FIG. 4B, since the base end portions 9 of the lead-out portions 2b to 5b of the electrodes 2 to 5 are pulled out in the same direction, the positional deviation between the electrodes 2 and 4 and the electrode 3 are caused.
The positional deviation states of 5 and 5 are point-symmetrically similar to each other, including the lead portions 2b to 5b. For this,
The effective light receiving electrode areas of the first unit pyroelectric element and the second unit pyroelectric element are substantially the same as shown by the shaded portions 7a and 7b in FIG. 4B.

The present invention is not limited to the electrode pattern shown in FIG. 4, and the lead-out portions 2b of the two surface electrodes 2 and 3 provided on the front side of the pyroelectric film 1 are provided.
3b have substantially the same directions in which they are pulled out and start to extend, and their widths are also substantially the same, and two back surface electrodes 4 provided on the back side of the pyroelectric film 1, Other electrode patterns may be used as long as the directions in which the lead-out portions 4b, 5b of FIG. 5 start to be pulled out and extend are substantially the same and their widths are also substantially the same size.
Further, the pyroelectric device according to the present invention does not necessarily have to be made up of only a pair of unit pyroelectric devices, and a pyroelectric device made up of more than one pair of unit pyroelectric devices may be enclosed in a common package. The present invention can also be applied to the above pyroelectric infrared sensor.

[0026]

According to the present invention, a pyroelectric element device in which a plurality of unit pyroelectric elements are connected in parallel is formed even if the electrode patterns are slightly displaced from each other on both sides of the pyroelectric film. Since the effective light-receiving electrode areas of the plurality of unit pyroelectric elements are substantially the same among the unit pyroelectric elements, when a pyroelectric infrared sensor is manufactured using this pyroelectric element device, It is possible to obtain a sensor having excellent electrical characteristics.

[Brief description of drawings]

FIG. 1A is a perspective view of a conventional pyroelectric device, and FIG. 1B is a state in which a front electrode and a back electrode of the pyroelectric device shown in FIG. FIG.

FIG. 2A is a plan view of another conventional pyroelectric device, and FIG. 2B is a plan view of the pyroelectric device shown in FIG. FIG.

FIG. 3A is a plan view of still another conventional pyroelectric device, and FIG. 3B is a diagram illustrating the pyroelectric device shown in FIG. FIG.

FIG. 4A is a plan view of a pyroelectric device according to an embodiment of the present invention, and FIG. 4B is a plan view of a pyroelectric device shown in FIG. It is a top view showing the state where it has shifted.

[Explanation of symbols]

 1 Pyroelectric Film 2 Surface Electrode 2a Electrode Main Body 2b Lead-out Part 3 Surface Electrode 3a Electrode Main Body 3b Lead-out Part 4 Back Electrode 4a Electrode Main Body 4b Lead-out Part 5 Back Electrode 5a Electrode Main Body 5b Lead-out Part 9 Base Part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 31/0264

Claims (5)

[Claims] 1. A pyroelectric film, a plurality of electrodes of a first group provided on one surface of the pyroelectric film, and a second group provided on the other surface of the pyroelectric film. Each of the first and second groups has an electrode body for providing an effective light receiving electrode area, and the electrode body for making a lead connection with another electric circuit. A plurality of electrodes of the first group, a plurality of electrodes of the second group, and a plurality of electrodes of each of the first and second groups. In a pyroelectric element device in which a plurality of unit pyroelectric elements are configured by the pyroelectric film interposed between individual electrodes, a first electrode of the first group and a first electrode of the second group are provided. Between one electrode and these two first electrodes A first unit pyroelectric element is constituted by the pyroelectric film which is used, and between the second electrode of the first group, the second electrode of the second group, and these two second electrodes. A second unit pyroelectric element is constituted by the pyroelectric film interposed between the first unit pyroelectric element and the second unit pyroelectric element, the polarization directions of which are opposite to each other, and the units are connected in parallel. In order to lead-connect the first and second electrodes of each of the first and second unit pyroelectric elements to the other electrical circuit as described above, the first electrodes of the first group of The leading end portion of the lead-out portion substantially opposes the leading end portion of the lead-out portion of the second electrode of the second group with the pyroelectric film sandwiched therebetween, and the second electrode of the first group. The leading end portion of the drawer portion of the The tip portion of the lead-out portion of the first electrode and the pyroelectric film are sandwiched so as to face each other, and the pattern of the plurality of electrodes of the first group becomes the pattern of the plurality of electrodes of the second group. Even if they are formed to be slightly displaced with respect to each other, they are formed by respective overlapping portions of the first and second electrodes of the first group and the first and second electrodes of the second group. In order that the effective light receiving electrode area is not substantially different between the unit pyroelectric elements, the lead-out portions of the plurality of electrodes of the first group are substantially oriented in the direction in which they are pulled out from the electrode body and start extending. Of the plurality of electrodes in the second group, and the lead portions of the plurality of electrodes of the second group are formed in the same direction. Body The pyroelectric element device is characterized in that the directions in which it is pulled out and starts to extend are substantially the same as each other, and the widths of the portions at which the extensions are started are also substantially the same in size. . 2. The width of each lead portion of each of the first and second electrodes of each of the first and second groups is smaller than the width of each electrode body of each of the first and second electrodes. The pyroelectric element device according to claim 1, wherein: 3. The lead portions of the first and second electrodes of the first and second groups, respectively,
Short proximal end portions extending from the respective electrode bodies of the first and second electrodes in substantially the same direction and extending from each other, and a short proximal end portion extending from these proximal end portions. The pyroelectric element device according to claim 1 or 2, wherein the pyroelectric element device comprises an L-shaped extending portion. 4. The edge portion of the lead portion of the first electrode of the first group is the edge portion of the lead portion of the lead portion of the second electrode of the second group and the edge of the pyroelectric film. Part of the first electrode of the second electrode of the first group, the tip of the second electrode of the first group of the second electrode of the first electrode of the second group The pyroelectric element device according to claim 1, wherein the tip portion and the edge portion of the pyroelectric film are substantially opposed to each other with the pyroelectric film sandwiched therebetween. 5. The electrode body of each of the first and second electrodes of the second group is formed in a portion overlapping with the electrode body of each of the first and second electrodes of the first group. The pyroelectric element device according to any one of claims 1 to 4, wherein the pyroelectric element device has a protruding portion in the periphery.