JPH03263378A - Photoconductive element and manufacture thereof - Google Patents

Abstract

PURPOSE:To detect light with high accuracy and to realize a small size by a method wherein a resistance element is mounted integrally on a substrate and is connected in series with a photoconductive element. CONSTITUTION:In addition to a first hole and a second hole h1, h2 for lead extraction use, a third hole h3 for lead extraction use is made; a third lead 7c is fixed and bonded to the third hole h3 for lead extraction use. In addition, a chip resistance 10 is fixed and bonded to the rear of a substrate 4; electrodes 11a, 11b at both ends of the chip resistance 10 are connected respectively to the third lead 7c and a second lead 7b via a conductive paste; a photoconductive element and the chip resistance are connected in series. That is to say, since a resistance element for compensation use is mounted collectively on the substrate 4 of the photoconductive element, the element can be mounted on a circuit board extremely easily, it can be made small-sized and it can detect the quantity of light with high accuracy. When a variable resistance is used for the resistance element, a resistance value can be adjusted extremely easily.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a photoconductive element and a method for manufacturing the same.

(Prior art) Photoconductive elements include cadmium sulfide (CdS) cells, cadmium selenide (CdSe) cells, which have sensitivity in the visible light region, lead sulfide (PbS) cells, and selenide cells, which have sensitivity in the infrared region, depending on their photosensitive wavelength. There are lead (PbSe) cells, etc., and their use in various fields is increasing by taking advantage of the property that the resistance value changes depending on the illuminance received by the light receiving surface in each photosensitive wavelength region.

Even in the interior, the CdS cell can be used as a bulk type photoconductive element.
Because it exhibits excellent linearity, low electrical distortion, and high sensitivity, it is widely used in volume control by detecting the pedal depression angle of electronic organs, photometering devices in cameras, and document edge detection devices in facsimile machines. There is.

However, individual resistances of photoconductive elements such as such CdS cells vary by about ±50%.

For this reason, a resistance element having a constant ratio with the resistance value of the photoconductive element is connected in series outside the photoconductive element, and constant voltage measurement is performed to compensate for variations in the resistance value. For example, by making the resistance element a variable resistor and adjusting the resistance value of the variable resistor, variations in the individual resistances of the photoconductive elements are compensated for and a predetermined resistance ratio is obtained.

That is, in this method, as shown in the equivalent circuit diagram in FIG. 12, V1++ is applied to the series connection of the photoconductive element 1 and the variable resistor 2, the variable resistor side is grounded, and the voltage across the variable resistor is By measuring the change with the voltmeter 3, the change in the resistance value of the photoconductive element is calculated, and the amount of light received is determined.

Conventionally, for example, in a plastic coat type CdS cell, as shown in FIG. 13, a CdS layer as a photoconductor layer 5 is formed on the surface of a ceramic substrate 4 made of alumina or the like with holes hl and h2 for leading out leads. After coating and sintering, a pair of electrodes 6a and 6b are provided on the upper layer of the photoconductor layer 5, facing each other, and holes h for leads are formed from these two electrodes 6a and 6b.
l h2 via leads 7a, 7. b is derived.

Then, as shown in FIG.
A method has been adopted in which the dS cell 1 and the variable resistor 2 are mounted and used. The resistance value of this variable resistor 2 can be changed by turning a screw D.

(Problems to be Solved by the Invention) In such a method, the resistor and wiring board occupy a large area of the entire optical sensor circuit, which has been a major problem that hinders miniaturization.

Furthermore, during mounting, both the resistor and the photoconductive element had to be mounted, resulting in poor workability.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a photoconductive element that can perform highly accurate light detection and can be miniaturized.

[Structure of the invention]

(Means for Solving the Problems) Therefore, the present invention includes a photoconductive layer formed on the surface of an insulating substrate and a pair of surface electrodes formed on the photoconductive layer, and leads are led from the back surface. In the photoconductive element,
A resistive element is integrally mounted on this substrate and connected in series with the photoconductive element.

Preferably, this resistance element is a variable resistance.

Further, this resistance element is a chip resistance.

Further, this resistive element is a thick film resistor formed directly on the substrate.

Furthermore, the method of the present invention includes a photoconductive layer formed on the surface of an insulating substrate and a pair of surface electrodes formed on the photoconductive layer, and leads are led out from the back surface to form a photoconductive element. After that, the resistance value is measured, and a resistor element corresponding to this resistance value is integrally mounted on the board and connected in series with the photoconductive element, and the resistor is adjusted so that the resistance value becomes the desired value. The resistance layer of the element is cut to finely adjust the resistance value.

(Function) According to the above configuration, since the compensating resistance element is integrally mounted on the substrate of the photoconductive element, mounting on the circuit board is extremely simple, and the light amount detection is small and highly accurate. It becomes possible to do this.

Moreover, by making this resistance element a variable resistance, it becomes extremely easy to adjust the resistance value.

Further, by using a chip resistor as the resistive element, it is possible to obtain a sensor that can detect the amount of light with high accuracy at extremely low cost.

Furthermore, by using a thick film resistor as the resistor element, it can be formed directly on the substrate and can be carried out in parallel with the manufacturing process of the photoconductive element itself, greatly simplifying the process. becomes possible.

Furthermore, the method of the present invention includes a photoconductive layer formed on the surface of an insulating substrate and a pair of surface electrodes formed on the photoconductive layer, and leads are led out from the back surface to form a photoconductive element. After that, the resistance value is measured, and according to this resistance value, a resistance element is integrally mounted on the board and connected in series with the photoconductive element, and further, the resistance value is adjusted to the desired value. Since the resistance value is finely adjusted, the resistance ratio between the photoconductive element and the resistive element is always adjusted with higher precision, making it possible to easily obtain a highly accurate sensor.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Example 1 This photoconductive element, as shown in FIGS. 1(a> to 1(C)), is basically constructed in the same way as the conventional element shown in FIG. In addition to the first and second lead-out holes hl and h2, the third lead-out hole h3
A third lead 7c is fixed to the hole h3 for leading out the third lead, and a chip resistor 1 is attached to the back surface of the substrate 4.
0, and electrodes 11a at both ends of this chip resistor 10.
, llb are respectively connected to the third glue door 7c and the second glue door b via conductive paste, so that the photoconductive element and the chip resistor are connected in series. Here, Fig. 1(a) is a perspective view, and Fig. 1(a) is a perspective view.
b) is a back view, and FIG. 1(C) is an equivalent circuit diagram.

The other parts are the same as the conventional element shown in FIG.

That is, a CdS layer as a photoconductor layer 5 is coated and sintered on the surface of a ceramic substrate 4 made of alumina or the like, and a pair of electrodes 6a and 6b are further disposed on the upper layer of this photoconductor layer 5 so as to face each other. , these two electrodes 6a.

Lead 7a from 6b through lead hole hl h2
7b is derived.

Note that solder may be used instead of the conductive paste to connect the chip resistor and the leads.

Further, around the third lead hole h8, the photoconductor layer 5 is removed by laser trimming or the like to cut off electrical connection with the substrate surface.

Further, as shown in an enlarged view in FIG. 2, this chip resistor 10 further includes a thick film resistor layer 13 formed on the surface of a ceramic substrate 12 by a screen printing method, and a U-shaped first and second electrodes 11a. , 11b.

The resistance value of this chip resistor 10 can be partially removed by a laser trimming method in which laser light is irradiated to evaporate, as shown in examples in FIGS. 3(a) to 3(e). This makes it extremely easy to adjust. K indicates the removed portion.

Next, a method for manufacturing this photoconductive element will be explained.

First, as shown in FIG. 4(a), three holes h1h2
A CdS layer is applied to the gold body on the surface of the alumina ceramic substrate 4 on which h3 has been formed, and sintered at 600°C for 1 hour to form a photoconductor layer 5. A metal mask is further applied to the upper layer of this photoconductor layer 5. A pair of electrodes 6a and 6b consisting of a solder thin film pattern are formed by vacuum evaporation with the electrodes placed on the substrate.

Then, as shown in FIG. 4(b), these two electrodes 6
Holes for leads from a, 6b hl h2 Niori leads 7a, 7
b, and use silver paste to connect electrodes 6a, 6b and 7a.
, 7b.

Furthermore, the photoconductor layer 5 around the lead hole h3 is removed by trimming, and the lead 7c is inserted into the lead hole h3 and fixed using an insulating paste.

Then, measure the resistance value at both ends of the leads 7a and 7b, select a chip resistor as a compensation resistor according to the value, fix it to the back of the board using insulating paste, and then connect the electrodes at both ends. ], a, and llb are respectively connected to the third glue 7C and the first glue 7a via conductive paste, and the photoconductive element and the chip resistor are connected in series.

In this way, the photoconductive elements shown in FIGS. 1(a) to 1(C) are completed.

Furthermore, after completion, trimming the chip resistor and finely adjusting the resistance value while monitoring the resistance value between the third lead 7C and the second lead 7b will allow for more accurate adjustment. becomes possible.

According to this photoconductive element, since the resistor is integrally formed, it is easy to incorporate into a circuit and can be miniaturized.Fine adjustment of the resistance value is also extremely easy, making it possible to achieve high performance. Accurate light amount detection becomes possible.

Embodiment 2 Note that the third lead is not inserted into the through hole as in the previous embodiment, but is inserted in a way that does not reach the substrate surface as shown in FIG. 5 as a second embodiment of the present invention. hole h
If O is used, there is no need to remove the photoconductor layer 5 around the lead hole h3 as in the previous embodiment.

Embodiment 3 In addition, as a third embodiment of the present invention, as shown in FIGS. 6(a) and 6(b), the electrodes 11 at both ends of the chip resistor are
A resistor lead 17 is fixed to one of the resistor leads 11a of the photoconductive element 11a and is used as a chip resistor, and this is fixed so that the electrode 11b is close to the second lead 7b on the back surface of the substrate 4 of the photoconductive element. It's okay.

In this embodiment, in addition to the effects of the first embodiment, the photoconductive element itself is formed in the same manner as before without making any design changes, and then a chip resistor having a desired resistance value is added. It is extremely easy to manufacture.

2 Embodiment 4 Furthermore, in the third embodiment, the resistor leads were attached perpendicularly to the resistor surface, but as a fourth embodiment, as shown in FIGS. 7(a) and 7(b). One of the electrodes 11a and 11b at both ends of the chip resistor 1.1
A resistor lead 17 is fixed to the resistor surface parallel to the resistor surface, and this is used as a chip resistor.This is fixed to the side surface of the substrate 4 of the photoconductive element, and the electrode of the chip resistor is attached to the second electrode 6b on the surface of the substrate. 1.1b may be fixed so that they are close to each other.

In this embodiment, the second electrode 6b and the electrode of the chip resistor]
, 1b may be made using a conductive paste such as silver paste, solder, or the like.

In this example, as in the third embodiment, the photoconductive element itself can be formed in the same manner as before without making any design changes, and then a chip resistor having a desired resistance value can be added. Therefore, manufacturing is extremely easy.

Example 5 3 Next, a fifth embodiment of the present invention will be described.

In this example, as shown in FIGS. 8(a) and 8(b), a groove V1 for inserting a resistor lead is formed on the back surface of the substrate of the photoconductive element.
An L-shaped glue 21 is fixed along the back and side surfaces of the chip resistor, and is fixed in this groove using an insulating adhesive, and at the same time using solder or conductive paste. A predetermined electrical connection is made using the

With this configuration, it is possible to easily and stably bond the resistor to the lead wire and to fix the photoconductive element main body and the resistor, and it is also extremely easy to position the resistor to which it is attached.

Example 6 Next, a sixth embodiment of the present invention will be described.

In this example, as shown in FIGS. 9(a) and 9(b), a groove v2 for inserting a resistor lead is formed on the side surface of the substrate 4 of the photoconductive element.
An L-shaped glue 31 is fixed along the back surface of the chip resistor, and is fixed in this groove using an insulating adhesive, and at the same time using solder or conductive paste. A predetermined electrical connection is made using the

With this configuration, as in Example 5, it is possible to easily and stably bond the resistor and the lead wire and to fix the resistor to the photoconductive element body, and also to position the resistor's fixing position. It becomes extremely easy.

Example 7 Next, a seventh embodiment of the present invention will be described.

This is a modification of Example 5. In this example, as shown in FIG. 10, a recess T for installing a chip resistor is provided on the back surface of the substrate of the photoconductive element. A chip resistor with an L-shaped glue 21 fixed along the side surface is fixed in the recess T using an insulating adhesive.

The recess T is a groove that matches the shape of the chip resistor and the lead, and the chip resistor and the lead can be easily positioned by fitting the chip resistor and the lead into this groove.

5 With such a configuration, it is possible to more easily and stably bond the resistor and the lead wires and the photoconductive element body and the resistor, and the appearance is extremely good, as well as the resistance of the resistor. Positioning 6- of the fixed position is also extremely easy.

Furthermore, the structure for forming grooves into which the chip resistor and leads are fitted is not limited to this example, and can be applied to all of the structures of Examples 1 to 4, such as forming grooves on the side surfaces. It is.

Embodiment 8 In the above embodiment, an example was explained in which a chip resistor was used as a resistor mounted on a substrate, but as shown in FIG.
A thick film resistor 40 consisting of b may be formed on the back surface of the substrate. This example is formed in exactly the same manner as in Example 2 except that the chip resistor is replaced with a thick film resistor.

In this case, if the electrode 42b of the thick film resistor is arranged so as to surround the second lead insertion hole h26 of the photoconductive element, and the silver paste is applied around the second lead, the second connection with the electrode 6b is easily possible.

If trimming is performed while monitoring the resistance value, it becomes possible to form a compact and highly accurate optical sensor extremely easily.

In the above embodiments, a photoconductive element using CdS as a photoconductive layer has been described, but the present invention is not limited to this and may include PbS, Pb5e.

Needless to say, it is also applicable to those using photoconductive layers such as CdSe.

Further, the structure and shape of the electrode can also be changed as appropriate.

In addition to the laser trimming method, methods for trimming the resistor include the sandblasting method, in which a mixture of pressurized air and sand is sprayed toward the thick film resistor through a small hole, and the thick film resistor is blown away. A short peening method in which a mixture of pressurized air and iron powder is injected through a small hole towards the thick film resistor, wiping it away. Various other methods can be applied, such as the wire brush method, which scrapes away the resistance layer, and the water jet method, which sprays pressurized water from small holes toward the thick film resistor to blow it away. is also possible.

In addition, as the resistance element, a variable resistor other than the chip resistor, thick film resistor, etc. used in the above embodiments may be used.

〔Effect of the invention〕

As explained above, according to the present invention, since the resistive element is integrally mounted on the substrate of the photoconductive element, mounting on the circuit board is extremely simple, and it is also compact and highly accurate. It becomes possible to detect the amount of light.

Furthermore, in the method of the present invention, the resistance value of the photoconductive element is measured, a resistance element corresponding to this value is integrally mounted on the substrate, and then the resistance value is adjusted so that this resistance value becomes a desired value. Since fine adjustments are made, it is possible to easily obtain a highly accurate sensor.

[Brief explanation of drawings]

1(a) to 1(c) are diagrams showing a photoconductive device according to a first embodiment of the present invention, FIG. 2 is a diagram showing a chip resistor used in the photoconductive device, and FIG. 3(a) to 3(e) are diagrams showing examples of trimming of the same chip resistor, and FIG. 4(a) and FIG. 4(b) are diagrams showing trimming examples of the photoconductive element of the first embodiment of the present invention. FIG. 5 is a diagram showing a part of the manufacturing process, FIG. 5 is a diagram showing a photoconductive element according to a second embodiment of the present invention, and FIGS. 6(a) and 6(b) are diagrams showing a third embodiment of the present invention. 7(a) and 7(b) are diagrams showing a photoconductive element according to a fourth embodiment of the present invention, and FIG. 8(a) and FIG. 8( b) is a diagram showing a photoconductive element according to a fifth embodiment of the present invention, FIGS. 9(a) and 9(b) are diagrams depicting a photoconductive element according to a sixth embodiment of the present invention, The figure shows the seventh aspect of the present invention.
FIG. 11 is a diagram showing a photoconductive device according to an eighth embodiment of the present invention, FIG. 12 is a diagram showing an equivalent circuit of a conventional photoconductive device, and FIG. 13 is a diagram showing an equivalent circuit of a conventional photoconductive device. This figure shows a conventional photoconductive element, and FIG. 914 shows an example of mounting the conventional photoconductive element on a circuit board. 1. Photoconductive element, 2. Variable resistance, 3. Voltage 51.
4... Ceramic substrate, hl,, h2. h3... Hole for leading out leads, 5... Photoconductor layer, 6a, 6b... Electrode, 7a. 7b...Lead, 17.21.31...Resistance lead,
40...Thick film resistor, 41...Thick film resistor layer, 42a, 4
2b...electrode pattern. 0 Ward Figure 6 ((7) (b) Funeral map <a> Figure 1a (a) Figure 10 Figure 4-1 Hiroshi JP 3 263378 (9) Koban Tetsu Kiln)

Claims (5)

[Claims] (1) A photoconductive layer comprising a photoconductive layer formed on the surface of an insulating substrate, a pair of surface electrodes disposed on the photoconductive layer, and a lead led out from the back surface of the substrate. 1. A photoconductive element comprising: a resistive element integrally mounted on the substrate so as to be in series with the photoconductive element. (2) The photoconductive element according to claim (1), wherein the resistance element is a variable resistance. (3) The photoconductive element according to claim (1), wherein the resistive element is a chip resistor. (4) The photoconductive element according to claim 1, wherein the resistive element is a thick film resistor formed directly on the substrate. (5) a photoconductive element forming step comprising a photoconductive layer formed on the surface of an insulating substrate and a pair of surface electrodes formed on the photoconductive layer, and leads being led out from the back surface; and resistance of the element. a measurement step of measuring the resistance value; a resistive element mounting step of integrally mounting a resistive element on the substrate and connecting it in series with the photoconductive element; A method for manufacturing a photoconductive element, comprising: a fine adjustment step of finely adjusting a resistance value by cutting a resistance layer;