JPH0747874Y2 - Contact image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an image sensor, and more particularly to a contact image sensor for reading an information carrier, for example, a document at a normal size (1: 1). is there.

(Prior Art) Conventionally, contact-type image sensors of various structures have been proposed which are used by being incorporated in a device such as a facsimile or an image scanner and which can read a document at the same size. Since such a contact image sensor does not need a reduction optical system, it has a feature that the device can be downsized. Since such a contact image sensor receives light reflected from a document, it has a large number of light receiving elements arranged in an array so as to have the same size as the width of the document. Then, a low temperature process (200 to 300
Research and development is being carried out using hydrogenated amorphous silicon that can be produced in a large area at a temperature of ° C.

In such a contact type image sensor, since the document is read with high resolution, it is necessary to bring the document and the light receiving section into close contact with each other, but on the other hand, the document is irradiated with light and the reflected light from the document is received. The original must be read by receiving light at the section, and therefore, a method of irradiating (incident) the light from the light source onto the original becomes important.

Hereinafter, such a method will be described with reference to the drawings.

Figure 3 is a conventional example disclosed in the literature ("Completely Adhesive Amorphous Silicon Image Sensor" Symposium of the Electrophotography Society (where amorphous silicon devices have come), May 24, 1985, pp.53-56). It is explanatory drawing which shows an example of the contact image sensor of FIG. The light receiving element 13 provided on the glass substrate 11 is a photosensitive layer 15 a
It has a sandwich type structure in which a —Si: H film 15 is sandwiched between a common electrode 17 and an individual electrode 19. Except for a desired region (light transmitting window 21 portion) of the photosensitive layer 15, the common electrode 17 in contact with the photosensitive layer 15 completely shields light. Also, glass substrate
A manuscript 23 is placed on the side opposite to the light receiving element 13 of 11, and a height of, for example, 7 is provided between the glass substrate 11 and the manuscript 23.
A rod lens array 25 of about 8 mm is provided.
Further, a space for converging light is provided between the rod lens array 25, the glass substrate 11 and the original document 23. Further, in order to irradiate the original document with light in the vicinity of the rod lens array 25. The light source 27 is provided. Therefore, according to this image sensor, it is possible to guide the information of the document 23 to the light receiving element 13 in a one-to-one manner.

FIG. 4 is an explanatory view of another example of the conventional contact type image sensor disclosed in the same document, showing an example in which a rod lens array is unnecessary. The basic structure of the light receiving element 13 of this image sensor is a sandwich type similar to that shown in FIG. 3, but a window for light transmission which penetrates the photosensitive layer 15, the common electrode 17 and the individual electrode 19 is used. 21 is provided, the light of a light source 27 provided on the opposite side of the glass substrate 11 from the side where the light receiving element 13 is provided is passed through this window 21
It is configured to guide the document to 23 and illuminate the document. further,
On the light receiving element 13, a translucent insulating film having a film thickness of about several μm, which also serves as a protective layer, is provided as indicated by 29 in FIG. Incidentally, 29a in FIG. 4 is a recess formed in the protective layer 29, which is formed because the light transmitting window 21 is formed.

In the contact type image sensor shown in FIG. 4, the light receiving element is protected by the above-mentioned translucent insulating film 29, and the distance between the original 23 and the light receiving element 13 is maintained so that the light receiving element receives light. The amount of light reflected from the original is increased.

(Problems to be Solved by the Invention) However, in the conventional contact type image sensor described with reference to FIG. 4, electric charges are accumulated on the surface of the protective layer due to friction generated by contact between the original and the contact image sensor. There was a problem that it would end up.

When the charge is accumulated in the protective layer, the charge becomes a leak current, the dark current of the diode forming the light receiving element increases, and the characteristic of the image sensor, for example, the light-dark ratio characteristic is impaired. Not desirable.

The present invention has been made in view of such a point, and therefore an object of the present invention is to solve the above-mentioned problems and provide a contact image sensor having excellent characteristics such as a light-dark ratio.

(Means for Solving the Problems) In order to achieve this object, according to the present invention, a light receiving element array for receiving reflected light from an original document, and the original document provided above the light receiving element array are provided. A contact layer type image sensor that protects the light receiving element when the contact is made, and reads the document by bringing the document into close contact with the protective layer. It is characterized in that a conductive layer made of a wear resistant material and grounded is provided on a region excluding a region corresponding to the formation region of the light receiving element array.

(Operation) With such a configuration, the conductive layer can be grounded, for example, by being connected to the common electrode of the light receiving element array. Therefore, when a document is brought into close contact with the contact type image sensor of the present invention and the document is fed to read the document, the contact between the document and the conductive layer, or the contact between the document and the protective layer including the conductive layer. Even if an electric charge is generated by friction,
Since this charge flows to the ground side through the conductive layer, the charge will not be accumulated in the protective layer. Further, since the conductive layer provided on the protective layer is made of a wear resistant material, it has excellent durability against friction with the original.

(Embodiment) An embodiment of the contact type image sensor of the present invention will be described below with reference to FIGS. 1 and 2. It should be noted that these drawings are only schematically shown to the extent that the present invention can be understood, and the dimensions, shapes, and positional relationships of the respective constituent components are not limited to the illustrated examples. In addition, in each drawing, the same reference numerals are given to the same components, and
Constituent components similar to those in the conventional art are indicated by the same reference numerals as those shown in the conventional drawings.

The contact-type image sensor of the present invention comprises a light-receiving element array for receiving reflected light from a document and a protective layer provided on the upper side of the light-receiving element array and protecting the light-receiving element array at the time of contact with the document. The contact image sensor comprises a protective layer. Therefore, the structure of the contact image sensor other than the protective layer is not particularly limited, and it is obvious that the present invention can be applied to contact image sensors having various structures. Therefore, the following embodiments will be described with an example in which the present invention is applied to the contact image sensor described with reference to FIG.

FIG. 1 is a plan view schematically showing the structure of the contact image sensor according to the embodiment of the present invention, and is a plan view showing a part of the contact image sensor. 2 is a sectional view schematically showing the contact type image sensor shown in FIG. 1 taken along the line I-I in FIG. In FIG. 2, hatching showing a cross section is partially omitted in order to avoid complication of the drawing.

In FIGS. 1 and 2, reference numeral 11 denotes a transparent insulating substrate. The insulating substrate 11 can be made of any suitable material such as glass. The insulating substrate 11 is represented by 17 and is a light-shielding layer made of an opaque metal film which also serves as a common electrode and a light-shielding film, and 15 is a light-receiving layer made of a thin film having a photoelectric conversion property such as amorphous silicon. And a transparent conductive layer denoted by 19 and made of a transparent conductive film of indium oxide / tin (ITO) or the like to be an individual electrode in this order from the substrate 11 side. Here, the laminated body in the portion where the common electrode 17 and the individual electrode 19 intersect is referred to as an individual light receiving element.
This light receiving element is shown with reference numeral 13 in FIGS. 1 and 2. A light receiving element array can be constructed by forming a predetermined number of the light receiving elements 13 at a predetermined pitch.

Further, in the case of this contact image sensor, a light introduction window indicated by 21 is provided in the central portion of the light receiving element 13. The window 21 for introducing light includes a light shielding layer 17, a light receiving layer 15, and a transparent conductive film layer 19
Is formed by removing predetermined portions of the respective layers. Further, a transparent protective layer 29 is provided on the substrate 11 including the light receiving element 13, and the transparent protective layer 29 has a high resistance such as SiN _x formed by a suitable method such as a sputtering method. It can be composed of an insulating film.

In the case of the contact type image sensor of the embodiment of the present invention,
On the protective layer 29, a conductive layer designated by 31 is provided. The conductive layer 31 is for releasing the electric charge from the protective layer 29 to the outside when the electric charge is accumulated in the protective layer 29. In the case of this embodiment, the conductive layer 31 is formed on a region excluding the region corresponding to the region where the light receiving element 13 is formed on the protective layer 29, and its planar shape is just like a window frame. (See FIG. 1). This conductive layer 31 is
Since the protective layer 29 has the purpose of releasing the charge when the charge is accumulated, it is necessary to ground the conductive layer by some method. Although various grounding methods are conceivable, in the case of this embodiment, this grounding is performed by connecting the conductive layer 29 to the common electrode 17 of the light receiving element. By doing so, it is possible to effectively ground without changing the manufacturing process of the contact image sensor, and it is possible to prevent various problems caused by the accumulation of electric charges, which is preferable.

The conductive layer 31 is required to have conductivity as a constituent material. However, when the conductive layer is formed at a position which is in direct contact with the original as in the above-described embodiment, the conductive layer has abrasion resistance. It is preferable that it has excellent flatness and a flat surface. Examples of such a material include thin films of Cr (chromium), Ta (tantalum) and the like. Further, such a metal thin film conductive tank can be formed by using a conventionally known film forming technique and photoetching technique.

Further, in the above-mentioned embodiments, the case where the conductive layer has a window frame-like planar shape has been described. However, this shape is arbitrary according to the design as long as charges can be efficiently removed. It can be changed to a suitable shape.

(Effect of the Invention) As is apparent from the above description, according to the contact type image sensor of the present invention, the conductive layer is provided on the protective layer having an insulating property and easily accumulating charges, and the conductive layer is formed. Since the layers are grounded, electric charges generated by friction between the original and the protective layer do not accumulate on the protective layer.

Further, since the conductive layer made of a wear-resistant material is provided on a region on the protective layer, which is removed from a region corresponding to the formation region of the light receiving element array when viewed from the document side, This conductive layer can be made highly durable against friction with the original, and can exhibit the function of removing accumulated charges for a long period of time.

For this reason, it is possible to provide a complete contact type image sensor having excellent electrical characteristics and durability, as well as solving problems caused by accumulated charges.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing the structure of an embodiment of the contact image sensor of the present invention, and FIG. 2 shows the contact image sensor shown in FIG.
FIG. 3 and FIG. 4 are sectional views schematically showing the contact image sensor of the related art taken along the line I-I shown in the figure. 11 ... Insulating substrate, 13 ... Light receiving element 15 ... Light receiving layer, 17 ... Shading layer (common electrode) 19 ... Transparent conductive layer (individual electrode) 21 ... Light introduction window, 29 ... Protective layer 29a: concave portion, 31: conductive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Mohri 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) Reference JP 62-36961 (JP, A) JP Sho 60-37161 (JP, A) JP-A-59-122274 (JP, A) JP-A-64-71173 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A protective layer comprising a light-receiving element array for receiving reflected light from a document, and a protective layer which is provided above the light-receiving element array and holds the light-receiving element when contacting the document. In the contact image sensor for reading the original by bringing the original into close contact with the original, an area on the protective layer excluding an area corresponding to the area where the light receiving element array is formed when viewed from the original side. A contact-type image sensor having a conductive layer made of a wear-resistant material and grounded thereon.