JPS5846186B2 - Photoelectric conversion device and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion device used in a transmission system such as a facsimile IJ, and it is possible to simplify the structure by using a photoelectric conversion element whose size corresponds one-to-one with the original. purpose.

In the conventional photoelectric conversion device, as shown in FIG.
is uniformly illuminated by an illumination light source 2 such as a fluorescent lamp, and the reflected light is imaged on a photoelectric conversion element 4 by a lens 3 to obtain a time-series electric signal.

In this case, the photoelectric conversion element 4 is a MOS or CCD made using IC technology, and has a chip size of about 20 rran.
When a lens with a diameter of 290 mm) is used, the reduction ratio of the lens is approximately 1/10, and the distance from the transmission document 1 to the photoelectric conversion element 4 is considerably large, which has the disadvantage of increasing the size of the apparatus.

Furthermore, in reality, as shown in Figure 1, one set of lenses can only be used for originals up to B6 size.
For A4 size, two sets of lenses are used.

This is because as the chip size of a CCD or the like increases, that is, as the total number of bits increases, the cost increases rapidly and becomes unprofitable.

However, when two sets of lenses are used, adjustment work is required to optically combine the exchanges.

In fact, this adjustment work is currently a major bottleneck in manufacturing.

On the other hand, instead of using a lens as an optical system, as shown in FIG. 5 to a large sensor array 6 is also known.

In this case, the distance between the document and the sensor is significantly shortened compared to a system using a lens, which has the advantage of being smaller overall, but it is difficult to align the light guide system 5 and the sensor, and the light guide system 5 has disadvantages such as being expensive.

As a method for solving the above-mentioned drawbacks, a method has been proposed in which the sensor and the document are brought into close contact with each other and the document is directly read without using a light guiding system.

As this method, there is a method as shown in FIGS. 3a and 3b.

For example, referring to FIG. 3a, a row of light receiving elements 8 is formed on a transparent substrate 7, and a transparent protective layer 9 is provided on top of the array.

Note that electrodes and wiring relationships are omitted in this figure.

Luminous flux 1 from the illumination light source 2 placed below the transparent substrate 7
0 illuminates the transmission document 1 through the light-transmitting substrate 7, the gap between the light-receiving elements 8, and the transparent protective layer 9, and the reflected light is captured by the light-receiving element 8 and subjected to photoelectric conversion.

In this case, the photoelectric conversion output obtained from the light receiving element is the luminous flux (which becomes interference light) that directly illuminates the light receiving element from the illumination light source.
0' and the reflected light beam from the document surface (which becomes the signal light), and has the disadvantage that the signal-to-noise ratio decreases due to the interference light.

On the other hand, in FIG. 3, a non-transparent metal layer 11 and a transparent insulating layer 12 are inserted between the light receiving element 8 and the transparent substrate γ.

In this way, direct interference light 10' from the illumination light source as shown in FIG. 3a can be prevented, and the S/N ratio in this sense is improved.

However, the thickness of the transparent protective film 9 (transmission original 1 and light receiving element 8
corresponds to the distance of

) requires a certain degree of thickness in order to efficiently make light incident on the transmission document 1 and introduce the reflected light into the light receiving element 8 .

In an extreme case, if the original to be transmitted 1 and the light receiving element 8 are brought into close contact with each other, the light beam 10 from the illumination light source 2 below the transparent substrate 7 will be transmitted to the light receiving element 8 itself or the non-transparent metal layer 11. It is blocked and does not effectively reach the transmission document 1 corresponding to the light receiving element 8.

The light beam 10 reaches the transmission document 1 corresponding to the portion without the light-receiving element 8 or the non-transparent metal layer 11, but if the transmission document 1 and the light-receiving element 8 were in complete contact with each other, the reflected light would not be received. It cannot reach element 8.

Therefore, as described above, the transparent protective layer 9 requires a certain degree of thickness.

However, from an actual production standpoint, it is difficult to produce the transparent protective layer 9.

In other words, after all the manufacturing processes for the light-receiving element, wiring, etc. are completed, a film that is transparent and also serves as wear resistance is applied to a certain thickness, that is, 50 to 100 μm, by vapor deposition, This is an extremely difficult technique regardless of which method is used, such as sputtering or coating.

Therefore, in practice, instead of the transparent protective layer 9, for example, a layer with a thickness of 5
A fourth glass plate 9' having a diameter of about 0 to 100 μm is attached to the surface of the substrate 7 on which the light shielding layer, photoconductive element, wiring, etc. have been completed.
The structure shown in the figure can be considered.

With this structure, the light beam 10 from the illumination light source 2 placed below the transparent substrate 7 passes through the transparent substrate 7, passes through the transparent window 15 without the non-transparent metal 11, and Furthermore, although the incident light 10 passes through the transparent substrate 9', even if the incident light 10 is narrowed down by the transparent window 15, it will be scattered when passing through the transparent substrate 9', and will be spread out when it enters the document.

Therefore, in order to prevent this, it is necessary to attach a second non-transparent film to the surface of the transparent substrate 9' that comes into contact with the original, and to provide a second transparent window that narrows the light.

However, since this second non-light-transparent film comes into contact with the original to some extent, it must also have wear-resistant properties.

Therefore, it is a question of what kind of material to choose, but the transparent substrate 9' is a thin glass plate with a thickness of about 50 to 100 μm, and if it is A4 size, the length in the main scanning direction is 23 mm.
It will be about 0rrrm.

Therefore, it is necessary to form a light-opaque film with thin slit-shaped transparent windows on a thin and large glass plate, but both methods are difficult to handle, whether it is formed using a vapor deposition mask or photolithography. It is extremely difficult to form a thin slit-shaped transparent window with precision.

In order to eliminate the above-mentioned drawbacks, the present invention provides a thick
By providing phase-shifted light insertion regions on the first and second bidirectional surfaces of the translucent insulating substrate and allowing the incident light to pass through these two light insertion regions, it is possible to prevent the incident light from spreading on the original due to scattering. The purpose of the present invention is to provide a photoelectric conversion device that prevents this problem and improves image quality.

The present invention will be described in detail below based on the drawings.

FIG. 5 is a partially enlarged sectional view in the sub-scanning direction showing an embodiment of the present invention.

1 is a document, 2 is an illumination light source such as a fluorescent lamp, and 7 is a thickness of 1.2
a light-transmissive insulating substrate of about 100 psi, 8 is a plurality of light-receiving element rows formed in a row in the main scanning direction on the first main surface of the light-transmitting insulating substrate 7, 9' is a light-receiving element and a document This is a light-transmitting wear-resistant plate for keeping the interval constant and preventing abrasion due to contact with the original 1. For example, it is a thin glass plate with a thickness of about 50 to 100 μm. It is glued onto the insulating substrate T.

11°11' is a non-transparent film made of metal such as Cr,
Reference numeral 11 denotes light insertion regions 15 and 1 extending in the main scanning direction in the first main part and 11' in the second main part of the transparent insulating substrate T, respectively.
It is attached except for the 5' part.

However, the phases of 15 and 15' are shifted in the sub-scanning direction.

Reference numeral 12 denotes a light-transmitting insulating film covering the substrate γ, which is made of glass of the same quality as the substrate γ, such as Konisig 7059, and is applied over the entire surface by sputtering or the like.

13 and 14 are electrodes formed on the light receiving element 8.

In order to pass light from a position shifted toward the sub-scanning direction of the light-receiving element, the electrode 14 may be provided with a hole in the electrode, or as shown in FIG. The light insertion region 15 can be formed by forming an electrode by bypassing the electrode in a portion corresponding to the middle of the element.

Alternatively, it goes without saying that the electrode 14 may be a transparent electrode.

Reference numeral 10 denotes a luminous flux that illuminates the document with illumination light emitted from the light source 2, and reflected light reaches the light receiving element.

In this case, the light emitted from the light source 2 is first condensed by the non-transparent film 11', and only the light that has passed through the light insertion region 15 travels through the substrate γ, and then further passes through the non-transparent film at the exit of the substrate 7. Only the light that has been narrowed down by the light insertion area 11 and passed through the light insertion area 15 is directed toward the original 11.

At this time, the light spreads even in the transparent wear-resistant plate 9', but between 7 and 9
Since the thickness ratio of ' is greater than 10:1, the spread of the light beam 10 shown by the dotted line in FIG. 5 is extremely small and can be ignored.

Even if the thickness ratio of 7 and 9' is such a value, the non-transparent film 11
', and if the incident light is not focused in the light insertion area 15', the light will enter the light insertion area 15 from various angles, and the light will spread widely in the light-transmitting wear-resistant plate 9'. Of course it is.

Furthermore, if the non-transparent film 11 can be formed of an insulating material, it is natural that the transparent insulating film 12 is not necessary, and the transparent insulating film 12 may not be attached to the transparent window 15. , it goes without saying that 12 does not need to be transparent if it is to be removed.

Next, the operating principle will be described using FIG.

As shown in FIG. 5, the light beam 10 emitted from the light source 2 passes through the light insertion areas 15' and 15 and illuminates the original 1, and the reflected light from the original is captured by the light receiving element 8 and photoelectrically converted. .

At this time, the reflected light from the original 1 is scattered in all directions, but if the thickness of the transparent wear-resistant plate 9' is selected to be approximately 100 μm or less, the reflected light leaking to the adjacent light-receiving element will be small, allowing the original light to be received. Most of the light is captured by the element, providing sufficient resolution.

However, if the thickness of the light-transmitting wear-resistant plate 9' is made extremely thin, it will be difficult for light to reach the original 1 and the lighting rate will be poor, so there is a limit. Appropriate.

Next, the manufacturing process will be described with reference to FIG.

First, a glass substrate 70 made by Dow Corning, for example, with a size of 140 mm x 50 rran and a thickness of 1.2 fran.
After washing 59, heat at 500℃ to 600℃ for 10 to 20 minutes.
Heat treat for minutes.

This heat treatment is performed after forming a photoconductive film, such as a CdS film, and when performing activation treatment, annealing, etc., thermal distortion (thermal expansion causes the substrate to stretch and the pattern pitch to increase).

) This is to prevent pattern pitch deviation due to the activation temperature, and heat treatment is performed in advance near the activation temperature to eliminate the effect of activation.

Next, a metal such as Cr is formed as a light-opaque film on both the first and second main cylinders by a method such as vapor deposition.

Next, as shown in Figure 7a, using the so-called photolithography technique,
The slit-shaped light insertion regions 15, 15' are removed.

In this case, as shown in FIGS. 5 and 7, the light insertion area 15,
15' is shifted in the sub-scanning direction, and if mask alignment, etching, etc. are performed at the same time using a double-sided mask alignment device, etc.
Not only can mutual dimensional accuracy be obtained, but the process can also be simplified.

Next, as shown in FIG. 7, Corning 7059, which has the same quality as the substrate 7, is coated on the entire first principal surface of the substrate 7, that is, the non-transparent film 11, by a method such as sputtering to form the transparent insulating film 12. Put it on.

Of course, it is not a bad idea to apply it also on the second main surface, that is, on the non-light-transparent film 11'.

Furthermore, as shown in FIG. 7C, CdS, Cd
Se, CdTe, Te, etc. are deposited singly or in plurals on the entire surface of the transparent insulating film 12 by vapor deposition or chemical precipitation, and then patterned as shown in FIG. 7d by photolithography.

After that, it is activated and made photoconductive by heat-treating it with a halogen compound (formation of light-receiving element 8).
.

Next, as an ohmic electrode, for example, NiCr or Au is applied to the gold wire by vacuum evaporation, and electrodes 13 and 14 are formed by photolithography, leaving only the necessary portions, as shown in FIG.

In some cases, a blocking electrode Te may be attached to one of the electrodes to provide diode characteristics.

Note that FIG. 7 shows a cross section in the sub-scanning direction, and as shown in FIG. 6, in FIG. Island-shaped light insertion regions 15 arranged in a row are provided.

- The electrode pattern is detoured only in this part between the light receiving elements.

Next, Dow Corning's glass microsheet +0211 with a thickness of 100 cm is cut to an appropriate size and is pasted onto the substrate T using transparent adhesive 16, as shown in Figure 7f. do.

As is clear from the above embodiments, the present invention provides the following excellent effects.

1) Non-transparent film 11°11 on the translucent insulating substrate 7
', and only the light that has passed through the light insertion areas 15' and 15 hits the original 1.

That is, since the light is condensed by the bibulous parts of the transparent insulating substrate 7, which is at least 10 times thicker than the transparent wear-resistant plate 9', the light spreads due to scattering within the transparent wear-resistant plate 9'. This allows a sufficiently narrowed light beam to be incident on the document, thereby improving image quality.

11) Forming a transparent window pattern by vapor depositing a light-opaque film on a light-transmitting wear-resistant plate 9, that is, a thin glass plate with a thickness of about 50 to 100 μm, by photolithography, etc. means that the glass plate is thin. Therefore, the process is extremely difficult.

However, as in the example, the thickness is large and the first
In the case where the light insertion region 15' is formed in the second main cylinder of the light-transmitting insulating substrate 7 whose main surface is patterned by a photolithography process, the relative position between the light insertion region 15 and 15', the light receiving element 8 and the light It is easy to define the relative positions between the insertion areas 15', and in terms of process, the number of man-hours can be shortened and productivity can be improved.

As described above, according to the present invention, it is possible to improve the reading performance and obtain high-quality images, and the manufacturing process is also simplified, thereby providing an industrially excellent photoelectric conversion device and its manufacturing method. It is something to do.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional optical reading system, Figure 2 is a perspective view of an optical reading system using a large sensor and light guide system, and Figure 3 a.
, b are partial cross-sectional views in the main scanning direction of conventional contact reading systems, FIG. 4 is a partial cross-sectional view of a thin glass plate bonded to the surface as a wear-resistant layer, and FIG. 5 is a partial cross-sectional view of a conventional contact reading system in the main scanning direction. FIG. 6 is a top view showing a state in which the electrodes are detoured, and FIG. 7 a=f is a partially cutaway view for explaining the manufacturing process. 1... Original, 2... Light source, 7...
...Transparent insulating substrate, 8... Light receiving element, 9'.
...Translucent wear-resistant plate, 11.11'...
Non-transparent film, 12... Transparent insulating layer, 13, 14... Electrode, 15.15'... Light insertion region.

Claims (1)

[Scope of Claims] 1. A light-transmitting insulating substrate and a first light insertion region of the light-transmitting insulating substrate for irradiating a document in the main scanning direction.
a first light-impermeable layer formed on the main surface; and a second light-insertion region parallel to the first light-insertion region of the first light-impermeable layer and shifted in the sub-scanning direction. a second non-transparent layer formed on the second main body of the transparent substrate; a transparent insulating layer covering at least the first non-transparent layer; a plurality of light-receiving element groups arranged in a sub-scanning direction opposite to the second light insertion region with respect to the insertion region and in the main scanning direction formed on the first light-opaque layer; A light-transmitting wear-resistant plate is formed in the main scanning direction so as to cover the light-receiving element group; The light that passes through the second light insertion area and the first light insertion area and further passes through the transparent wear-resistant plate irradiates the document, and the reflected light is incident on the light receiving element. 2. In the photoelectric conversion device according to claim 1, of the two electrodes taken out from the light receiving element in the sub-scanning direction, the first light insertion One of the electrodes passing through the first light insertion region is arranged in a part shifted in the sub-scanning direction between the light receiving elements in the first light insertion region, or in a detoured shape, or in the first light insertion region. , a photoelectric conversion device characterized in that it has a perforated shape. 3. In the photoelectric conversion device according to claim 2, the electrode passing through the first light insertion region is connected to a light receiving element. A photoelectric conversion device characterized in that an island-like light insertion region is formed in a corresponding portion shifted in the sub-scanning direction. 4. On the first main surface and the second main surface of the transparent insulating substrate. The first and second light-impermeable layers formed in A method for manufacturing a photoelectric conversion device, comprising forming a light-transmitting insulating film, a light-receiving element, etc. on the first main surface with the insertion region as a reference, and further adhering a light-transmitting wear-resistant plate thereon. .