JPS62209849A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To realize a perfectly contact type and thin image sensor and eliminate requirements for working accuracy and complexity by a method wherein a light waveguide is formed on the surface of a sensor substrate where a photodetector is provided and guides a light from the horizontal direction on the same plane as the photodetector. CONSTITUTION:A photodetector 12 is provided on the surface of a sensor substrate 21 and further a light waveguide 28 is formed on the same surface of the substrate 21. The light waveguide 28 is composed of a dielectric thin film whose refractive index is larger than the refractive index of the sensor substrate 21 and is so formed on the surface of the sensor substrate 21 as to guide the light from a predetermined position onto the photodetector 24 and the surface of its portion above the photodetector 24 is formed into an uneven surface 29. Because of the uneven surface 29, the condition of total reflection is not conformed at this part and the light is discharged outside and reflected by a manuscript 31 surface and enters the light waveguide 28 again and is absorbed by the photodetector 24 below and converted into an electric signal. With this constitution, an image sensor, while it is a perfect contact type image sensor which does not need an optical system, which has a light introduction means requiring no working accuracy of manufacture and causing no complexity can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a contact type image sensor for reading images of facsimiles and the like.

(Prior art) In facsimile machines, etc., a contact image sensor that can read originals in a ratio of t-1 to l differs from conventional CCD sensors in that it does not require an optical reduction system and can make the sensor section thinner. It becomes possible to downsize the. Furthermore, when hydrogenated amorphous silicon is used as the light-receiving element array, a highly sensitive element can be realized at low temperatures (200 to 300°C).

By the way, in order to read a document, it is necessary to irradiate the surface of the document with light. Figure 2 (a), (b).

(e) shows the main conventional light irradiation methods. FIG. 2(a) shows, for example, as described in Japanese Utility Model Application Publication No. 60-1077, light from an LED 12 is reflected on a document 11 and one reflected light is passed through a Selfoc lens play 15 to a glass substrate 14. This structure leads to the light receiving element 13 above. Figure 2 (
b) is a method of guiding the reflected light from the original 11 to the light receiving element 13 through the Oguti fiber array 16, as described in, for example, Japanese Utility Model Application No. 59-156213; Figure (- as well as LED, 14
is a glass substrate. FIG. 2(c) shows, for example, JP-A-6
As described in Publication No. 0-91360, LED
12 is introduced from the back side of the glass substrate 14, and the reflected light from the original 11 that is in close contact with the insulating protective film 17 is guided directly to the light receiving element 13.

(Problems to be Solved by the Invention) However, in the first method shown in FIG.
The drawback is that it is difficult to make it thin. Also, Figure 2(b)
In the second method, the distance between the document 11 and the sensor substrate is smaller than in the first method, but it has the disadvantage of being expensive. Furthermore, the third method shown in FIG. 2(c) has the feature that it can be made thinner because it does not require an optical system. Since it is necessary to drill holes 18, manufacturing is troublesome, and processing accuracy is required.

This invention was made in view of the above points, and its purpose is to provide a complete contact type that does not require an optical system like the conventional example shown in FIG. It is an object of the present invention to provide a contact type image sensor having a method of introducing light that does not cause problems or complications.

(Means for solving the problem) In the present invention, a light receiving element is provided on the surface of the sensor substrate,
Further, an optical waveguide is formed on the same surface of the sensor substrate. The optical waveguide is made of a dielectric thin film having a refractive index greater than the refractive index of the sensor substrate, and is formed on the surface of the sensor substrate from a predetermined position to above the light receiving element, and is formed in an upper portion of the light receiving element. The surface is formed into an uneven surface.

(Function) In such an optical waveguide, from the end opposite to the light receiving element,
Light from an external light source is introduced. Then, the light undergoes repeated total reflection on the upper and lower surfaces of the guide waveguide, travels through the optical waveguide, and is guided to the upper part of the light receiving element.

However, since the surface of the optical waveguide above the light-receiving element is formed into an uneven surface, the conditions for total reflection are no longer satisfied at this portion, and the light is emitted to the outside. The emitted light is reflected by the surface of the document provided in close contact with the optical waveguide, and the reflected light enters the optical waveguide again 9, is absorbed by the light receiving element below, and is converted into an electrical signal.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing one embodiment of the present invention. In this figure, 21 is a glass substrate as a sensor substrate;
A light receiving structure 22 is provided at a predetermined portion on the surface thereof. The light receiving structure 22 includes a common electrode 23 formed on the surface of the glass substrate 21, a common electrode 23 connected to the common electrode 23, and formed on the substrate 21.
A large number of light receiving elements 24 in a horizontal row made of a semiconductor such as H,
A transparent conductive film 2 such as ITO on the top surface of each light receiving element 24
5. Individual electrodes 26 drawn out from the transparent conductive film 25 (from the top surface of the light receiving element 24) through the side surfaces of the light receiving element 24 onto the surface of the substrate 21; the individual electrodes 26 and the light receiving element 26;
It is composed of a stow insulating film 27 that insulates.

Such a light receiving part structure 22t-formed glass substrate 2
1 (on the surface on which the light-receiving part structure 22 is provided), Tr Ot t-mixed Sing t 3 to several l
By forming the 810 ! An optical waveguide 28 made of a thin film is formed. In this optical waveguide 28, the surface of the upper portion of the light receiving element 24 is formed into an uneven surface 29 by plasma etching or wet etching. Furthermore, the end of the optical fiber 30 from the external light source is bonded to the end of the optical waveguide 28 corresponding to the end of the substrate 21 with an adhesive. In this example, the optical waveguide 28 is formed using TtOtt-mixed Si, but the optical waveguide 28 is not limited to this, and may be formed using a sensor substrate such as a glass substrate 2.
Any dielectric material having a refractive index greater than 1 may be used.

The operation of one embodiment configured in this way will be explained. Light from an external light source is transmitted to the glass substrate 2 via an optical fiber 30.
1 (corresponding to the end of the optical waveguide 28) into the optical waveguide 28. Then, the light travels through the optical waveguide 28 while repeating total reflection on the upper and lower surfaces of the guide waveguide 28, and is guided to the upper part of the light receiving element 24. However, since the surface of the optical waveguide 28 above the light-receiving element 24 is formed with an uneven surface 29, the condition for total reflection is no longer satisfied at this portion, and the light is emitted to the outside through the uneven surface 29. As shown in FIG. 1, the original 31 is moving in close contact with the uneven surface 29 of the optical waveguide 28. Therefore, the emitted light is reflected by the surface of the original 31, and the reflected light enters the optical waveguide 28 again from the uneven surface 29, is absorbed by the light receiving element 24 below, and is converted into an electrical signal.

In this case, the problem is that from the optical waveguide 28 to the light receiving element 2.
4, as shown in FIG. 1, the individual electrodes 26 of the light receiving element 24 are pulled out so as to be interposed between the light receiving element 24 and the optical waveguide 28, and the individual electrodes 26 are used as a light shielding film. This can be easily solved by using

(Effects of the Invention) As detailed above, according to the contact image sensor of the present invention, an optical waveguide is formed on the surface of the sensor substrate on which the light receiving element is provided, and the light receiving element and the light receiving element are connected to each other through the optical waveguide. Since we guided the light from the lateral direction on the same surface, Figure 2 (c
), it is completely contact type and can be made thinner like the conventional example, so there is no need to provide a lighting hole for each light receiving element as in the conventional example, and the requirements for processing accuracy and complexity in manufacturing can be reduced. It can be eliminated. In addition, the uneven surface on the top of the light-receiving element of the leading waveguide does not need to be provided separately for each element, and can be easily formed in a one-dimensional shape extending in the direction of the element array with the width of the entire width of the light-receiving element arranged in a horizontal row. can be realized. Further, the dielectric thin film serving as the optical waveguide also serves as a tsusipation film, and therefore, according to the sensor of the present invention, it is possible to omit the formation of a /4 sipation film.Furthermore,
The sensor of this invention is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the contact type image sensor of the present invention, and FIG. 21... Glass substrate, 24... Light receiving element, 28...
- Optical waveguide, 29... uneven surface, 30... optical fiber.

Claims (1)

[Scope of Claims] Consisting of (a) a sensor substrate; (b) a light-receiving element provided on the surface of the sensor substrate; and (c) a dielectric thin film having a refractive index greater than the refractive index of the sensor substrate. , an optical waveguide formed on the surface of the sensor substrate on the same side as the light-receiving element, extending from a predetermined position onto the light-receiving element, the surface of the upper part of the light-receiving element having an uneven surface; (d) A contact image sensor comprising means for introducing light from a light source into this optical waveguide from the end opposite to the light receiving element.