JPS6236962A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To decrease the light response time without losing an optical current by lowering the transmissivity of a protection layer, forming the protection layer as a multi-layer film having different refractive index and making simultaneously a bias light and a reflected light from an original incident on a photoelectric transducer face. CONSTITUTION:A light shield layer 2 having a lighting window 3 is formed on a transparent insulation substrate 1 by a material such as Si and a transparent insulation layer 4 made of a material such as SiO2 is formed as a multi-layer film to keep insulation with a photoelectric transducer. The photoelectric transducers 5 arranged as the shape of islands in the main scanning direction on the light shield layer 2 are formed by photoconductive thin film made of such as CdS, CdSe or their solid solution. A protection layer 8 is provided on the transducer 5 in order to introduce the reflected light 10 from an original 9 into the photoelectric transducer 5 and to protect the transducer 5. The thickness of the protection layer 8 is thinner than the pitch of the transducer 5 to prevent the deterioration in the resolution. The transmissivity of the protection layer 8, let the maximum value of the reflected light 10 from the original 9 be 100, is selected so that the intensity of scattered light 11 in the protection layer 8 as the bias light to the transducer 5 is 10-100 on the transducer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention has a size that corresponds 1:1 to the width of a document used on the reading side of a facsimile machine, a non-print scanner, etc. The present invention relates to type image sensors.

2. Description of the Related Art Conventional contact type image sensors include, for example, Japanese Patent Application Laid-Open No. 58
As shown in Japanese Patent No. 40856, the structure was as shown in FIG.

That is, in FIG. 4, on the transparent insulating substrate 1.

5i02, Si3N4 to form a light shielding layer 2 having an illumination window 3 and to maintain insulation between the photoelectric conversion element 6 and the light shielding layer 2.
Form an insulating layer such as 3B/m and on it, e.g. aaS.

Photoelectric conversion elements 6 made of 0dSe -4 or a solid solution thereof are formed in an island shape, and consist of a common electrode 6 in which the photoelectric conversion elements 6 are grouped into a certain number of units, and individual electrode elements corresponding to each photoelectric conversion element 5. After providing the counter electrode, a transparent protective layer 1 having high transmittance, such as micro sheet glass, is placed on top of the counter electrode.
2, the light incident through the illumination window 3 is reflected by the document 9, and the reflected light 1Q is converted into an electrical signal by a photoelectric conversion element 6 as information about the document 9. .

Problems to be Solved by the Invention However, in a contact type image sensor having such a structure, if the photoelectric conversion element 6 is a non-storage type using a photoconductor of an l-VI group compound, a large amount of photocurrent can be obtained. However, the photoresponse time is as slow as 10-odd m5ec.

For extremely high-speed reading, a structure that sacrifices photocurrent, such as an accumulation type, must be used. Such an office structure has problems such as a complicated signal processing circuit because the output signal is very small.

In consideration of this point, it is an object of the present invention to provide a contact type image sensor that has a simple structure, has a large photocurrent, and can read document information at high speed.

Means for Solving the Problems In order to solve the above problems, the present invention lowers the transmittance of the protective layer, and with this configuration, part of the light incident from the illumination window is irradiated onto the document and reflected. A portion of the light is scattered inside the protective layer and is simultaneously used as bias light to be incident on the photoelectric conversion element.

Effect of the present invention With the above structure, the effective trap concentration of carriers can be reduced by the bias light added at the same time as the reflected light from the original, and the photoelectric conversion using a photoconductor thin film of a -VI group compound can be achieved. In the device, the optical response time can be easily and drastically shortened.

Example Hereinafter, one embodiment of the present invention will be described based on the attached drawings. I will explain.

In the cross-sectional view in the sub-scanning direction of FIG. 1, a light-shielding layer 2 having an illumination window 3 is formed on a light-transmitting insulating substrate 1, such as 7059 glass manufactured by Corning Corporation, using Si.

The transparent insulating layer 4 is made of Or, Ta, W, Ti, etc., and is made of 5i02, 5i5N4, etc. in order to maintain insulation from the photoelectric conversion element 6 as a single layer or a multilayer film. Photoelectric conversion elements 6 arranged in an island shape in the main scanning direction above the light-shielding layer 2 are formed of a photoconductor thin film such as OdS, GdSe or a solid solution thereof, and photoelectric conversion elements 6 are arranged in a fixed number of units.
A common electrode 6 that brings together the photoelectric conversion elements 5 and a counter electrode consisting of individual electrode elements corresponding to each photoelectric conversion element 5 are provided. Furthermore, a protective layer 8 is provided on top of the photoelectric conversion element 6 in order to introduce the reflected light 1o from the original 9 into the photoelectric conversion element 6 and to protect the photoelectric conversion element 6. At this time, the thickness of the protective layer 8 is made thinner than the pitch of the photoelectric conversion elements 6 in order to prevent a decrease in resolution.

Then, the transmittance of the protective layer 8 is calculated as 1 for the reflected light from the original 9.
When the maximum value of o is set to 100, the intensity of the scattered light 116 peno in the protective layer 8 which becomes the bias light of the photoelectric conversion element 6 is 5 to 100 on the surface of the photoelectric conversion element 6, preferably as shown in FIG. As can be seen from the relationship between the relative bias light amount and the photoresponse time, it is set to 10 to 1o○. By arbitrarily changing the transmittance of the protective layer 8 in this manner, the amount of bias light on the surface of the photoelectric conversion element 5 can be adjusted. Here, the increase in scattering [11] in the protective layer 8 is due to the increase in the original 9
Although the illuminance of the surface will be lowered, the effect of the light amount on the photoresponse time is much less of a problem than the bias light amount effect.

As a result, reflected light 1 from the original 9 appears on the surface of the photoelectric conversion element 6.
By simultaneously injecting 0 and the scattered light 11 which becomes the bias light, the optical response time can be easily reduced to less than μ~K with a simple structure, as shown in Fig. 3, and high-speed reading is possible. . Furthermore, since the photocurrent does not decrease, the configuration of the signal processing circuit is also easy.

Next, other embodiments of the present invention will be described.

FIG. 2 shows a cross-sectional view in the sub-scanning direction of another embodiment, and the structure of the seven pages other than the protective layers 12 and 13 in FIG. 2 is the same as that in FIG. 1. In this embodiment, as shown in FIG. 2, a first protective layer 12 and a second protective layer 13 are
In addition, the first protective layer 12 and the second protective layer 13 have different refractive indexes, and the first protective layer 12, for example, 5i0
A transparent material having a higher refractive index of the second protective layer 13 than the second protective layer 13, for example, HOS.

By using SiC, TiO2, diamond, etc., the same effect as the first embodiment can be obtained by using the scattered light 11 at the interface between the first protective layer 12 and the second protective layer 13 as bias light. In addition, by using a material with high hardness, such as Hos+SiC, for the second protective layer 13, the surface of the protective layer 13 is less likely to be scratched due to contact with the original 9, thereby improving durability.

Note that the protective layer is not limited to two layers as in this embodiment, but it goes without saying that three or more layers can be formed.

Effects of the Invention According to the present invention, bias light and reflected light containing document information can be simultaneously transmitted onto the photoelectric conversion element surface using an extremely simple structure that reduces the transmittance of the protective layer and uses a multilayer film with different refractive indexes. The photoresponse time can be reduced to less than that of conventional IA without damaging the photocurrent, the signal processing circuit can be simplified, and the durability of the protective layer can also be improved. It is extremely excellent in practical use.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view in the sub-scanning direction of a contact type image sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view in the sub-scanning direction of a sub-scanning sensor of a contact type image sensor according to another embodiment of the present invention. It is. 2... Light shielding layer, 3... Lighting window, 6...
... Photoelectric conversion element, 8 ... Protective layer with low transmittance, 9 ... Original document, 10 ... Reflected light,
11...Scattered light, 12.Old...Transparent protective layer, 1
3... Protective layer with different refractive index. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4: Bias light intensity (7=9)

Claims (3)

[Claims] (1) A light-shielding layer having an illumination window on an insulating substrate, a light-transmitting insulating layer, a plurality of photoelectric conversion elements arranged in an island shape in the main scanning direction on the light-shielding layer, and a constant number of the photoelectric conversion elements. A common electrode that is commonly connected for each unit, a counter electrode that is connected to each of the photoelectric conversion elements, and a protective layer having a certain transmittance, and the incident light from the illumination window is directed to the top of the protective layer. A contact type image sensor characterized in that the reflected light is used as signal light and the light scattered by the protective layer is used as bias light to enter the photoelectric conversion element. (2) Regarding the transmittance of the protective layer, when the maximum value of the reflected light from the original is 100, the light intensity of the scattered light on the surface of the photoelectric conversion element is 5 to 100. A contact image sensor according to scope 1. (3) The protective layer is made of a multilayer film with a sequentially increasing refractive index, the scattered light from the film interface with different refractive index is used as bias light, and the light intensity of the scattered light is set when the maximum value of the reflected light from the original is 100. 2. The contact image sensor according to claim 1, wherein: 5 to 100 on the surface of the photoelectric conversion element.