JPH01119061A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To enable gap to be easily and strictly controlled, to enable improved resolution with less scattering to be realized, and to prevent electrical short- circuiting due to contact between a conductive layer and a sensor part by sandwiching an insulation spacer between a photosensor and a protective layer which is in direct contact with a manuscript. CONSTITUTION:Four-layer construction protective layers 229, 230, 232, and 235 are formed on a photosensor part 208. An insulation spacer 234 is dispersed within the second protective layer 229. When forming a conductive layer such as ITO on a thin plate glass such as borosilicate glass, a conductive protrusion 236 may be produced if dust and foreign objects may be present, thus resulting is electrical short-circuiting. However, by dispersing the insulation spacer 234 within the second protective layer 229, not only the reading resolution is secured but also short-circuiting due to the conductive protrusion 236 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photoelectric conversion device, and relates to a photoelectric conversion device, for example, in which a -dimensional line sensor is used, and a document for image reading is placed in close contact with the -dimensional line sensor. The present invention relates to a photoelectric conversion device suitable for application to a facsimile device, an image reader, etc. that reads image information while moving the device.

[Conventional technology]

Conventionally, as an image reading device using a -dimensional line sensor, one is known that reads image information by forming a document image on a one-dimensional line sensor several centimeters in length using a reduction optical system. However, this type of image reading device requires a long optical path length to perform reduction or imaging.
Furthermore, since the volume occupied by the optical system is large compared to the volume of the entire device, it has been difficult to construct the reading device in a compact size.

On the other hand, when using a same-magnification optical system using a long-dimensional line sensor with the same length as the document width, the volume of the optical system can be significantly reduced, and the reading device can be made smaller. Known methods for realizing such a same-magnification optical system include a method using a focusing fiber and a method using a contact lens array.

However, since convergent optical fibers are generally expensive, there is a contact-type original reading method (specially used) in which the original is read while moving the original in close contact with the -dimensional line sensor without using such fibers or lens arrays. Publication No. 55-74262, Japanese Patent Publication No. 55-7527
'1, JP-A-56-45084, JP-A-56-12
No. 2172) has already been developed as related to the applicant's earlier application.

FIG. 4 is a partially cutaway side sectional view showing a main part of the contact type photoelectric conversion device. To briefly describe the device, reference numeral 8 denotes sensor sections arranged on a transparent substrate 11 such as glass in a direction perpendicular to the drawing to constitute a one-dimensional line sensor.

In this sensor 8, a light-shielding layer 12 and an insulating layer 13 made of metal or the like are formed on a transparent substrate 11 made of glass or the like, and hydrogenated amorphous silicon (hydrogenated amorphous silicon) as a photoconductive layer is formed thereon.
A semiconductor layer 14 such as A-3t:H (hereinafter referred to as A-3t:H) or Cd5-8e is formed. Further, a pair of main electrodes 16 and 17 are formed via a doped semiconductor layer 15 for ohmic contact, and a light receiving window 18 is formed between them.

In such a configuration, the document P is illuminated with light L incident through the entrance window 19 of the transparent substrate 11 (the sensor unit 8 is shielded from light by the light shielding layer 12 from this incident light);
The reflected light is received by the sensor section 8 and a read signal is taken out via electrode wiring (not shown). That is, for example, when a high-potential driving voltage is applied to the main electrode 17 with reference to the potential of the main electrode 16, when reflected light enters the surface of the semiconductor layer 14 via the light-receiving window 8, carriers increase. Therefore, the resistance decreases, and this change can be read as image information.

In this configuration, the light from the light source 30 enters the substrate 11 from the back surface side. At this time, when direct light from the light source 30 enters the sensor unit 8 in addition to the light reflected from the document surface, the photocurrent due to the direct light flows as a steady current, so even if the photocurrent due to the reflected light from the document surface flows. The S/N ratio is greatly reduced. Therefore, in order to prevent direct light from the light source 30 from entering the sensor section 8, it is essential to provide the light shielding layer 12 on the light source side of the sensor section 8. And this light shielding layer 1
2 is usually made of metal in order to ensure sufficient light-shielding properties with a thin film.

On the other hand, the distance between the original P and the sensor section 8 is usually 0.1
A reading resolution of 4 to 8 lines/mm can be obtained with a spacing of about 4 mm, but in order to ensure such resolution, the above-mentioned spacing must be strictly controlled.

Conventionally, a protective layer 20 has been provided to protect the photoelectric conversion section (sensor section) 8. This protective layer 20 has generally been provided on a substrate 11 made of a light-transmitting member having a photoelectric conversion portion, such as glass, with an adhesive layer 21 as an intermediate layer interposed therebetween.

This adhesive layer 21 was used for the function of simply bonding the protective layer 20 and the substrate 11 having the photoelectric conversion section 8.

[Problem that the invention seeks to solve]

However, there have been cases where the thickness of the adhesive layer 21 is uneven in the distance between the document P and the photoelectric conversion unit 8, that is, in the direction perpendicular to the drawing, or the adhesive layer 21 is thicker than necessary.

Variations in this distance and thickness greater than desired have been a contributing factor to a decrease in stability of quality in terms of resolution, a decrease in yield, and deterioration in performance.

Furthermore, it is clear that as the resolution becomes higher and higher, the variation in the distance and the thickness of the layer become even more of an obstacle.

[Problems to be Solved by the Invention] Furthermore, if a conductive layer for static electricity countermeasures is formed between the transparent protective layer 20 and the adhesive layer 21, the conductive layer will come into contact with the sensor section, causing an electrical short circuit. There was a problem.

[Means for solving problems]

To this end, the present invention provides a photoelectric conversion device in which a protective layer is provided on a substrate having a photoelectric conversion portion via an intermediate layer, and by having spacer particles in the intermediate layer, the photoelectric conversion device which has been a problem in the past has been solved. This makes it easier to manage the distance between the converter and the original.

Further, according to the present invention, a high-resolution photoelectric conversion device with little variation in performance between photoelectric conversion sections is provided.

Furthermore, by interposing an insulating spacer between the electrostatic conductive layer and the optical sensor, it is possible to prevent electrical short circuits due to contact between the conductive layer and the sensor section.

Hereinafter, the present invention will be described in detail with reference to the drawings.

[Example 1] Figures 1, 2 (A) and 2 (B) respectively show photoelectric conversion devices according to embodiments of the present invention. FIG. 1 is a sectional view taken along line BB' of the plan view shown in FIG. 2(A), and FIG.
It is a sectional view taken along c' line.

In these figures, 210 is a matrix wiring section, 208
212 is a light sensor section; 212 is a charge storage section; 213 is a switch section including a transfer switch 213a and a discharge switch 213b for resetting the charge in the charge storage section 212;
4 is a wiring that connects the signal output of the transfer switch to a signal processing section to be described later; 223 is a load capacitor for accumulating and reading out the charge transferred by the transfer switch 213a; and 234 is a connection between the optical sensor section 208 and the original P. It is a spacer to maintain and manage the distance.

In this embodiment, the optical sensor section 208 is connected to the transfer switch 21.
An A-3i:H film is used as the photoconductive semiconductor layer 204 constituting the discharge switch 213a and the discharge switch 213b, and a silicon nitride film (Si
NH) was used.

In addition, in FIG. 2 (A), in order to avoid complexity,
Photoconductive semiconductor layer 204, insulating layer 203, protective layer 229
, 230 and 232 and spacer 234 are not shown. In addition, the photoconductive semiconductor layer 204 and the insulating layer 203 are formed in the optical sensor section 208, the charge storage section 212), the transfer switch 213a, and the discharge switch 213b, and are also formed between the upper layer electrode wiring and the substrate. . Further, an n+ doped A-33:H layer 205 was formed at the interface between the upper electrode wiring and the photoconductive semiconductor layer to form an ohmic contact.

In addition, in the wiring pattern of the line sensor of this example, all signal paths output from each sensor section are wired so as not to intersect with other wiring, thereby preventing crosstalk between each signal component and gate electrode wiring. This prevented the generation of induced noise.

In the optical sensor section 208, 216 and 217 are upper layer electrode wirings. The light incident through the entrance window 219 and reflected from the document surface passes through the A-8i:H photoconductive semiconductor layer 20.
The conductivity of 4 was changed, and the current flowing between the upper layer electrode wirings 216 and 217 facing each other in a rhombus shape was changed.
02 is a metal light-shielding layer connected to an appropriate drive unit,
Direct light from the light source was prevented from entering the sensor unit 208.

The charge storage section 212 is formed on the lower electrode wiring 214, the dielectric material of the insulating layer 203 and the photoconductive semiconductor 204 formed on the lower electrode wiring 214, and the photoconductive semiconductor layer 204, and serves as an optical sensor. The wiring is continuous with the upper layer electrode wiring 217 of the section. The structure of this charge storage section 212 is a so-called MIS (Metal-Insulator).
-3emiconductor) It has the same structure as a capacitor. Although either positive or negative bias conditions can be used, stable capacitance and frequency characteristics could be obtained by always using the lower electrode wiring 214 in a negative bias state.

In the figure, (C) shows a switch section 213 with a TPT structure including a transfer switch 213a and a discharge switch 213b. ,
It was composed of a photoconductive semiconductor layer 204, an upper layer electrode wiring 225 serving as a source electrode, an upper layer electrode wiring 217 serving as a drain electrode, and the like. The gate insulating layer and photoconductive semiconductor layer of the discharge switch 213b are the same layer as the insulating layer 203 and the photoconductive semiconductor layer 204, the source electrode is the upper layer electrode wiring 217, the gate electrode is the lower layer electrode wiring 227, and the drain electrode is the This is the upper layer electrode wiring 226. Moreover, 233 is a lower layer wiring connected to the gate electrode of the transfer switch 213a.

Furthermore, as shown in FIG. 1B and FIG. 1, three-layer protective layers 229, 230, and 232 were formed on the optical sensor section 208. First storage It layer 23 which is an intermediate layer
Since the liquid is directly applied to the optical sensor part 208, etc., the liquid can be easily used as a high purity material such as an inorganic thin film such as a Stow film or a 5iNH film, which can stabilize the surface of the optical sensor part 208, etc. Organic films such as polyimide resin were used because they can be formed into films. As the second protective layer 229, which is an intermediate layer, an epoxy resin or the like with good adhesion was used to improve moisture resistance. For the third protective layer 232, thin glass such as borosilicate glass is used as a material with high wear resistance and light transmittance. in this case,
The second protective layer 229 also functioned as an adhesive.

In this way, the protective layer has a laminated structure in which each layer performs multiple functions that cannot be satisfied with a single material, so to speak, with functional separation, thereby ensuring the environmental resistance of the photoelectric conversion device.

In the second protective layer 229, an insulating spacer 234 is provided.
The distance between the document P and the sensor unit 208 was set to be about 0.1 mm, and a reading resolution of 8 to 16 lines/mm was ensured.

Glass fiber is used as a spacer material.

A photoelectric conversion device was manufactured using alumina particles and plastic beads, respectively, and it was confirmed that the effect of using one spacer member was sufficiently exhibited no matter which one was used.

In this way, by interposing the insulating spacer between the optical sensor and the protective layer that is in direct contact with the original, it has become easier to precisely control the distance between the optical sensor and the original.

[Embodiment 2] FIG. 3 is a side sectional view of a line sensor showing another embodiment according to the present invention. All of the constituent parts of the optical sensor section, charge storage section, transfer switch, discharge switch, and matrix wiring section are the same as in the first embodiment. Four-layer protective layers 229, 230, 232 and 235 are provided on the optical sensor section 208.
are formed, the first protective layer 230, the second protective layer 229
, and the third protective layer 232 are formed in the same manner as in the first embodiment and have the same functions. The fourth protective layer 235
This antistatic layer is made of ITO or the like and has a function of protecting the sensor element from static electricity generated by contact with the original P on the protective layer 232 of the original P, and is maintained at a constant potential.

In the second protective layer 229, an insulating spacer 234 is provided.
was dispersed.

When forming a conductive layer such as ITO on thin glass such as borosilicate glass, if dust or foreign matter is present, conductive protrusions 236
may occur. This protrusion 236
9, 230, the optical sensor section 208, the charge storage section 2
12) Although contact with the switch section 213, matrix wiring section 210, etc. may cause an electrical short circuit, reading resolution is ensured by dispersing insulating spacers 234 in the second protective layer 229. In addition, short circuits caused by the conductive protrusions 236 can be prevented.

Incidentally, as the spacer member, glass fibers, alumina particles, plastic beads, etc. as described above could be suitably used. Further, among these materials, it is particularly desirable to use a translucent material as the spacer member.

When a spacer member is translucent, it is highly desirable to make the refractive index substantially equal to that of the intermediate layer it contains, since this can minimize loss of incident light and adverse effects on incident light for reading. Ta.

The size (thickness) of the spacer member is determined by setting the average diameter (or average particle size) of the layer to 1.0 to 0.75 times the design thickness of the contained intermediate layer. Very favorable results were obtained in terms of thickness controllability, ease of manufacturing a photoelectric conversion device, and uniformity of layer thickness.

It goes without saying that the present invention is not limited to the embodiments described above, but can be applied to many modifications within the scope of the invention.

〔Effect of the invention〕

As explained above, the present invention includes a light-shielding layer disposed on the surface of a light-transmitting substrate, an insulating layer disposed on the light-shielding layer,
It includes an optical sensor placed on an insulating layer and a plurality of protective layers placed on the optical sensor, and image information is generated by receiving reflected light from the light irradiated onto the document surface from the back side of the substrate. In an image reading device that reads documents, an insulating spacer is sandwiched between an optical sensor and a protective layer that comes into direct contact with the document.

This facilitates strict control of the distance between the optical sensor and the document, making it possible to provide a high-resolution image reading device with little variation.

Furthermore, by interposing an insulating spacer between the electrostatic conductive layer and the optical sensor, it is possible to prevent electrical short circuits due to contact between the conductive layer and the sensor section.

[Brief explanation of the drawing]

1, 2(A) and 2(B) respectively show an embodiment of a photoelectric conversion device according to the present invention, and FIGS.
B) are B-B of the plan view shown in FIG. 2 (Δ), respectively.
FIG. 3 is a side sectional view showing another embodiment of a photoelectric conversion device according to the present invention, and FIG. 4 is a side sectional view showing an example of a conventional image reading device. 8.208... Optical sensor section 11.201... Transparent substrate 12.202... Light shielding layer 13.203... Insulating layer 14.204... Semiconductor layer 15.205. ...Doped semiconductor layer 16.17,
216,217.233...Electrode (wiring) 18......Light receiving window 19.219...Incidence window 30.237...Light source 20.229,230 , 232...Protective layer 210...Matrix wiring section 212...
......Charge storage section 213...
...Switch section 213a...Transfer switch section 213b...Discharge switch section 214
......Signal output wiring 223...
...Readout load capacitor 224.227...
Gate electrode 225... Source electrode 226...
...Drain electrode 229, 230, 232 ...Protective layer 234 ...Spacer 235 ...
...... Transparent conductive layer 236 ......
Transparent conductive layer protrusion L・・・・・・・・・・・・・・・ Original illumination light P・・・・・・・・・・・・・・・ Original

Claims (6)

[Claims] (1) A photoelectric conversion device in which a protective layer is provided on a substrate having a photoelectric conversion portion via an intermediate layer, the photoelectric conversion device comprising a spacer member in the intermediate layer. (2) The photoelectric conversion device according to claim 1, wherein the photoelectric conversion section has a photoconductive layer. (3) A photoelectric conversion device according to claim 2, wherein the photoconductive layer is amorphous silicon. (4) The photoelectric conversion device according to claim 1, wherein the spacer member is made of a material selected from glass, alumina, and plastic. (5) The photoelectric conversion device according to claim 1, wherein the intermediate layer is an adhesive layer. (6) The photoelectric conversion device according to claim 1, further comprising a conductive layer maintained at a constant potential between the intermediate layer and the photoelectric conversion section.