JPH029168A - Perfect contact type photo sensor - Google Patents

Abstract

PURPOSE:To increase signal output and read concentration gradient by mounting photodetecting parts on photoelectric conversion parts at both sides in the secondary and main scanning directions of a lightning window and using a light-tight film between blocks as an upper electrode. CONSTITUTION:A vaporized film is formed on a transparent substrate 1 and a light-tight film to be used commonly as a lower electrode 2 is formed by providing a lightning window 3. A photoelectric conversion layer 5 is formed on the lower electrode and then, an upper transparent electrode 6 is formed on the above layer 5. A transparent insulating film 4 is formed on the above electrode 6 and finally, a vaporized film is formed as the upper electrode to be used commonly as the light-tight film 6 between blocks. Photodetecting parts on sensor parts A are in existence at both sides inn the secondary and main scanning directions of the lightning window 3. This configuration increases signal output and makes it possible to read concentration gradient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fully contact type 1-magnification optical sensor used for reading documents in facsimiles and the like.

[Prior art] Figures 1 (a) and (b) are examples of a fully contact type 1-magnification optical sensor that does not use a lens system ((a) is a cross-sectional view, (b)
) is a plan view, 1 is a transparent substrate, 2 is a light-shielding film/lower electrode with a lighting window 3, 4 is a 5in2 transparent insulating film, 5 is a photoelectric conversion layer, 6 is an upper electrode, 7 is an original, and 8 is between blocks. The upper transparent electrode is omitted because it is a light-shielding film. ] are known. In this type of fully contact type optical sensor, light that enters from the transparent substrate 1 side through the lighting window 3 is reflected by the surface of the document 7, reaches the photoelectric conversion section, that is, the light receiving section on the sensor part A, and is reflected there. The light is converted into an electric signal according to its illuminance, and this signal charge is then temporarily stored in the capacitor B.
As is clear from Figure (b), the light receiving part (size is usually 100 μm2) consists of one lighting window (size is usually 90 μm2).
) Since there is only one spot on one side in the sub-scanning direction, a large signal output cannot be obtained, and therefore the S/N is 18 to 25 d.
It was difficult to read the density gradation. In addition, since the inter-block light-shielding film is formed separately from the upper electrode, such as by forming it further below the lower electrode with an insulating film interposed therebetween, or after forming the upper electrode, it is formed separately from the upper electrode. This not only complicates the process, lowers yield, but also increases costs.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks in the prior art, increase the signal output, make it possible to read density gradation, and simplify the manufacturing process. An object of the present invention is to provide a completely contact type optical sensor that improves yield and reduces costs.

[Structure/Operation of the Invention] The optical sensor of the present invention has sensor blocks each having a light-shielding film having a daylight window on a transparent substrate, a lower electrode, a photoelectric conversion layer, a transparent insulating film, and an upper electrode connected by a light-shielding film between the blocks. The complete contact type optical sensor having this structure is characterized in that the light receiving sections on the photoelectric conversion section are provided on both sides of the lighting window in the sub-main scanning direction, and the interblock light shielding film also serves as the upper electrode.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 4.

FIGS. 2(a) and 2(b) are a schematic sectional view and a plan view, respectively, of an example of the optical sensor of the present invention in which the number of capacitive portions B is one. Further, FIG. 3 is a schematic cross-sectional view of another example of the optical sensor of the present invention in which there are two capacitive parts B. For both optical sensors, the light receiving part on sensor part A is in the sub-main scanning direction of the lighting window 3 (see Fig. 4).

C exists on both sides of the light receiving section). Therefore, the amount of signal due to the incident light from the lighting window 3 is approximately twice that of the conventional one. For example 8
In the case of a bit/m optical sensor, the signal amount is 0.6 to 088V in the case of a conventional one with one light receiving part, but
If there are two light receiving sections like the present invention, it is 1.2 to 1.
Increases to 5v.

Moreover, the S/N is improved to approximately 30 to 35 dB, which is a large +l]. Here, when the size of the light-receiving part is 8 dots/I-oum reading density, d and e are each 0-11 in Fig. 4.
0μm, c is 3~IOμm, a is 90-150
A value of 173 to 2/3 in μm and b/a gives good results. Outside these ranges, the S/N tends to decrease. Also, the reading density is 16 dots/m or 24 dots/Il! When the value is as high as 11, the dimensions and manufacturing method can be determined in almost inverse proportion to the above value, excluding the b/a ratio. In this case, the b/a ratio is the same as above.

To make the optical sensor of the present invention, for example, in the case of the optical sensor shown in FIG. 2, Ti and Cr are deposited on the transparent substrate 1.

By forming a vapor deposited film such as AQ, and then providing a lighting window 3 by photolithography, the light shielding film/lower electrode 2 is formed.
form. Next, a photoelectric conversion layer 5 of a-3i (amorphous SL), CdS, Ss, etc. is formed on top of it by plasma CVD method or the like, and on top of that, ITO1In20. , SnO, etc., a transparent insulating film 4 of Sin is formed thereon, and finally, a transparent insulating film 4 of Ti, Cr, AQ, etc. is formed as the upper electrode (individual electrode) and inter-block light-shielding films 6 and 8. A vapor deposited film may be formed.

Note that the lower electrode may have a multilayer structure together with the SiO□ layer separately from the light shielding film, and the upper electrode may also have a similar multilayer structure.

In the above embodiment, in the sandwich type optical sensor,
The lower electrode is a common electrode for each photoelectric conversion element,
When several elements are collectively driven as a sensor block, the upper electrode (individual electrode) and inter-block light-shielding film of the present invention can prevent light leakage between these sensor blocks. Further, this upper electrode can be applied even when the lower electrode is separated into individual elements, and therefore there is light leakage between all the elements. Note that even when the upper electrode of the present invention is directly irradiated with light from above, it is possible to block light between the blocks and to partially block light at the same time as the sensor.

[Operations and effects of the invention] The effects of the present invention are as follows.

1) Upper individual', 1! Since the poles also serve as inter-block light-shielding films, there is no need for a special process to form this light-shielding film, and the manufacturing process of the optical sensor is simplified.

2) There are two light-receiving parts, and the signal amount is 2 compared to the conventional type.
Since the increase has doubled, the S/N is also 30 to 35 dB, which is a large +lJ.
Therefore, it can be used as an optical sensor that can read density gradations.

4゜3) Even if the sensor bits are 16 to 32 bits/book, the signal amount is large, so implementation and circuit design are easy.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are a schematic cross-sectional view and a plan view, respectively, of an example of a conventional fully contact type optical sensor, and FIGS. 2(a) and (b) are an example of a fully contact type optical sensor of the present invention, respectively. FIG. 3 is a schematic cross-sectional view of another example of the sensor of the present invention, and FIG. 4 is an explanatory diagram for determining the size of the lighting window and the light receiving portion of the sensor of the present invention. 1...Transparent substrate 2...Light shielding film/lower electrode 3...
Lighting window 4...Transparent insulating film 5...Photoelectric conversion layer 6...Upper electrode 7...Original 8.
...Inter-block light-shielding film A...part of the sensor B...
・Capacity section C・Light receiving section

Claims (1)

[Claims] 1. In a complete contact type optical sensor having a structure in which each sensor block has a light-shielding film having a lighting window on a transparent substrate, a lower electrode, a photoelectric conversion layer, a transparent insulating film, and an upper electrode, and is connected by a light-shielding film between the blocks, A completely contact type optical sensor characterized in that a light receiving section on a photoelectric conversion section is provided on both sides of a lighting window in the sub-main direction, and an interblock light-shielding film also serves as an upper electrode.