JPS60139063A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To improve the photoelectric transfer characteristics with a miniature scale of an original reading system of a facsimile, by forming the 1st transparent protecting layer covering a photoelectric conversion element on a transparent substrate and the 2nd protecting layer covering an area between adjacent photoelectric conversion element on the 1st layer. CONSTITUTION:The photodetectors 404 sandwiched by a metallic electrode 402 and a transparent electrode 403 are arrayed in a row on a glass substrate 401 with a fixed pitch. These electrodes and elements are covered with a transparent protecting layer 405, and a transparent protecting layer 503 as well as a light shielding layer 501 are formed on the layer 405. Furthermore the layer 501 and a transparent protecting layer 502 are provided at an area between adjacent photodetectors 404. Therefore the beams (a) and (c) to be applied to the adjacent photodetectors 404 are reflected by a vertical wall surface of the layer 502 among the reflected beams given from a point A set on an original 103. While the beams (a) and (c) transmitted through said vertical wall are cut by the layer 501. Thus it is possible to secure the excellent image resolution characteristics with no use of a fiber lens array.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a photoelectric conversion device that has the same dimension as the width of a document and reads the document in close contact with the document, for example in a facsimile document reading system.

[Prior art]

One of the conventional devices of this type is shown in FIG. In the figure, 101 is an IC image sensor, 102
103 is a lens, 103 is a document, and 104 is a fluorescent lamp for illuminating the document 103.

In such a photoelectric conversion device, an image of an original 103 illuminated by a fluorescent lamp 104 is transferred to an IC by a lens 102.
A reduced image is formed on the image sensor 101. Above I
The C image sensor 101 has a light receiving element of 10 to 20 μm.
They are arranged in a line at intervals, and can be electrically scanned by a CCD or the like.

However, ICs using such monolithic IC technology
For the image sensor 101, the length of the light receiving element is 3011I.
Since the width is limited to about 11, normally when reading a document 103 having a width exceeding 200I, a reduction optical system as shown in FIG. F is essential. For this reason, manuscript 1
The distance between 03 and IC image sensor 101 is 300
This is a major factor preventing miniaturization of this type of photoelectric conversion device.

Therefore, recently, the original 103 has the same dimensions as the original width.
A close-contact image sensor is being considered that reads the image by coming in close contact with the image sensor. An example of the structure of this contact type image sensor is shown in FIG. 2 or 3. In FIGS. 2 and 3, 201 is a sensor board, 202 is an LED array for illuminating the original 103, 2o3 is a fiber lens array, and 204 is a guide plate for the original 103.

First, the photoelectric conversion device shown in FIG. 2 will be explained.

The original 103 is illuminated by two LED arrays 202, and its image is formed as a real image of the same size on the sensor substrate 201 by the fiber lens array 203.

On the sensor board 201, eight light receiving elements are arranged in a row.
The light receiving elements are arranged at an element density of 8 pixels/mya, and photoelectric conversion is performed at a resolution of 8 pixels/am. By using such a large sensor substrate 201, the distance between the sensor substrate 201 and the document 103 is approximately 20+a+w, and the photoelectric conversion equipment can be significantly downsized.

Next, the photoelectric conversion device shown in FIG. 3 will be explained.

In this device, the fiber lens array 203 in the device shown in FIG. 2 is not provided, and the sensor substrate 201
is in contact with the original 103, and illumination is provided by the LED array 20.
2 from the back surface of the sensor substrate 201. FIG. 4 shows a cross section of the sensor substrate 201 used in this device. In the figure, light incident from the glass substrate 401 (indicated by an arrow in the figure) passes through a transparent electrode 403 and a transparent protective layer 405. , illuminates the original 103. The light reflected on the surface of the original 103 passes through the transparent protective layer 405 and the transparent electrode 403 again, and enters the light receiving element (photoelectric conversion element) 404. Also in the figure, 40
2 is a metal electrode.

In the device having the structure shown in FIG. 3, the sensor board 2
01 is read by contacting with the original 103, there is no need to use the fiber lens array 203 compared to the conventional example shown in FIG. 2, which has the advantage of further downsizing and cost reduction.

However, in conventional devices with such a configuration, it is necessary to make the protective layer thick to some extent in order to ensure the amount of light at the light receiving element 404, but since no lens system is used, the protective layer is thick (the resolution increases as the thickness increases). There is also a drawback that the surface of the protective layer 405 is easily contaminated due to contact with the original.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by providing a second protective layer on the transparent protective layer to cover the area between adjacent photoelectric conversion elements, the resolution characteristics can be improved. The purpose of this invention is to provide a photoelectric conversion device that is extremely inexpensive.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows a photoelectric conversion device according to an embodiment of the present invention.

In the figure, 401 is a glass substrate (transparent substrate), 404
are a plurality of light receiving elements (photoelectric conversion elements) arranged in a line on a glass substrate 401 at predetermined intervals;
A metal electrode 402 and a transparent electrode 403 are formed above and below 04.

405 is a first transparent protective layer formed on the glass substrate 401 to cover the light receiving element 404, and 501 is a first transparent protective layer [formed on the glass substrate 401 to cover the portion between the adjacent light receiving elements 4. The light-shielding layer 502 is a second transparent protective layer formed on the light-shielding layer 502, and 503 is a second protective layer composed of the light-shielding layer 501 and the second transparent protective layer 502. A sensor substrate 201 is configured.

Next, the effects will be explained. Figure 5 shows the sensor board 2
01 is a cross-sectional view taken along a plane along the arrangement direction of the light receiving elements. A metal electrode 402 is placed on the glass substrate 401.
and a light receiving element 404 sandwiched between transparent electrodes 403.
They are arranged in a line at a pitch of 25 μm, and are covered with a first transparent protective layer 405. Also, on the first transparent protective layer 405, a light shielding layer 501 and a second transparent protective layer 5 are arranged.
03 is formed.

Also, the cross-sectional view in a plane perpendicular to the arrangement direction of the light-receiving elements is the same as that in FIG. The light enters the substrate 401 and hits the surface of the original 103,
The reflected light from the surface of the original 103 passes through the transparent protective layer 405 and reaches the light receiving element 404 .

In this device, as shown in FIG. 5, a light shielding layer 501 and a second
Since the transparent protection N502 is provided, the original 103
Among the reflected light from point A on the surface, adjacent light receiving elements 404
The lights a and C are reflected by the vertical wall surface of the second transparent protective layer 502, and the lights a and C that have passed through the second transparent protective layer 502 are cut off by the light shielding layer 501. Therefore, in this device,
Excellent resolution characteristics can be obtained without using a lens optical system such as the fiber lens array 203 shown in FIG.

Further, since a second transparent protective layer 502 is further formed on the light shielding layer 501, contact with the document surface occurs only on the surface of this transparent protective layer 502, and the surface of the first transparent protective layer M405 In other words, there is no risk that the surface of the protective layer on the light receiving element 404 will come into contact with the surface of the document and become dirty, so that very stable photoelectric conversion can be performed.

Here, the two transparent protective layers 40-5, 502 are made of silicon oxide, silicon nitride, tantalum oxide, etc., with a thickness of about 50 μm, and the light shielding layer 501 is made of chromium, nichrome, tantalum oxide, etc.
It is appropriate to form a metal such as aluminum to a thickness of 50 to several hundred nm.

Further, FIG. 6 shows a second embodiment of the present invention, and in this embodiment, a transparent protective layer 502 on the light-shielding layer 501 shown in FIG.
is not formed, and the film thickness of the light shielding layer 501 is formed thick, that is, the second protective layer 503 is entirely covered with the light shielding layer 50.
1.

With this configuration, most of the reflected light from point A on the surface of the original 103 is incident on one light receiving element 404, as shown by arrows a, b, and c in the figure. It is possible to obtain excellent resolution characteristics as in the embodiment.

Here, the film thickness of the light-shielding layer 501 in this device is several to several hundred μ.
m is appropriate. In addition, thick film formation methods such as metal vacuum evaporation or sputtering can be used to form the light shielding layer [501]; however, in this device, there is no deterioration in resolution due to an increase in the thickness of the light shielding layer. , screen printing method.

Alternatively, a method of adhering a metal foil, metal plate, etc. to the surface and then buttering it by photolithography is also an effective method for forming a light-shielding layer.

In the above two embodiments, the second protective layer includes a light-shielding layer, but the second protective layer may be entirely a transparent protective layer. Further, in the first embodiment, the light-shielding layer is formed on the entire bottom surface of the second transparent protective layer, but this light-shielding layer may be formed on a part of the bottom surface of the second transparent protective layer.

〔Effect of the invention〕

As described above, according to the present invention, the second protective layer is provided on the transparent protective layer so as to cover the portion between adjacent photoelectric conversion elements, which impairs the advantages of being small and inexpensive. There is an effect that resolution characteristics and photoelectric conversion characteristics can be significantly improved without any problems.

[Brief explanation of the drawing]

1 is a perspective view of an example of a conventional photoelectric conversion device having a reduction optical system, FIG. 2 is a perspective view of an example of a conventional contact type photoelectric conversion device, and FIG. 3 is a perspective view of an example of a conventional contact type photoelectric conversion device. A perspective view of another example, FIG. 4 is a cross-sectional side view showing the structure of the sensor substrate in the device of FIG. 3, and FIG. 5 is a cross-sectional view showing the structure of the sensor substrate in the photoelectric conversion device according to an embodiment of the present invention. , FIG. 6 is a sectional view of another embodiment of the present invention. 201... Sensor substrate, 405... First transparent protective layer, 404... Light receiving element (photoelectric conversion element), 401...
... Glass substrate (transparent substrate), 501 ... Light shielding layer, 5
02...Second transparent protective layer, 503...Second protective layer. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 3 Figure 4 Procedural amendment (voluntary) 21 Name of the invention Photoelectric conversion device 3 Person making the amendment Representative Hitoshi Katayama Department 4 Agent 5 Details of the invention in the specification to be amended Explanation column 6, content of amendment (formed by r03 on page 7, line 13 of 11 specification) is changed to “02
is corrected to "formation". (2) Correct "membrane thickness" in line 7 of page 9 to "rlit thickness". (3) Correct "thick film" in line 17 to "thin film."that's all

Claims (4)

[Claims] (1) A photoelectric conversion device that reads the document by photoelectrically converting light reflected from the document from behind the sensor substrate by a sensor substrate that is in contact with the document, wherein the sensor substrate is made of a transparent substrate. a plurality of photoelectric conversion elements arranged in a line at predetermined intervals on the transparent substrate; a first transparent protective layer formed on the transparent substrate to cover the photoelectric conversion elements; A photoelectric conversion device comprising: a first transparent protective layer; and a second protective layer formed to cover a portion between the adjacent photoelectric conversion elements. (2) The photoelectric conversion device according to claim 1, wherein the second protective layer is a second transparent protective layer formed integrally with the first transparent protective layer. (3) The second protective layer includes a second transparent protective layer formed on the first transparent protective layer, and a light shielding layer formed on a part or all of the bottom surface of the second transparent protective layer. The photoelectric conversion device according to claim 1, characterized in that the photoelectric conversion device comprises a layer. (4) The photoelectric conversion device according to claim 1, wherein the second protective layer is a light shielding layer formed on the first transparent protective layer.