JPH01228166A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To prevent the MTF from degradation by a method wherein a material equal in linear expansion coefficient to the substrate material is employed to constitute a supporting board. CONSTITUTION:In a contact type image sensor wherein a plurality of substrates 3, each mounted with a lighting window 1 and a photoelectric conversion element 2, are arranged and bonded into one piece on a supporting board 4, it is so prepared that the material for the substrates 3 is equal in linear expansion coefficient to the material for the supporting board 4. By adopting this design, a bonding layer 5 or a substrate 3 is protected from break possibly to occur when exposed to heat from a light source. This design also prevent the MTF (resolution characteristic) from degradation at a junction between substrates 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contact type image sensor used in facsimiles, electronic blackboards, and the like.

BACKGROUND OF THE INVENTION In recent years, contact type image sensors that do not use lenses have been developed as image reading devices for fax machines, electronic blackboards, and the like. This type of image sensor basically has a plurality of substrates 3 provided with illumination windows 1 and photoelectric conversion elements 2 arranged on a support plate 4, as shown in FIG. It is glued and integrated. To read an image in such an image sensor, light from a light source (not shown) placed on the side of the support plate 4 is transmitted through the support plate 4, the adhesive layer 5, and the substrate 3 (if the support plate and the substrate are opaque metal plates). is provided with a slit) and the original 6 passes through the irradiation window 1.
The reflected light further reaches the photoelectric conversion element 2 and is sensed. Since the adhesive used here was a room-temperature ultraviolet curing type, as shown in Figure 1, the connecting parts (linear) between the boards 3 were completely normal at room temperature, but due to heat from the light source, etc. When heated, if there is a difference between the coefficient of linear expansion of the substrate and the coefficient of linear expansion of the support plate, damage to the adhesive layer or sometimes damage to the substrate may occur as shown in Figure 1(b). be. In such a state, during reading, the scattering of light at the bonding portions of the substrates becomes significant, resulting in fatal deterioration of MTF (characteristics representing resolution).

An object of the present invention is to provide a close-contact image sensor that can prevent deterioration of MTF at the connection portion between substrates.

The contact type image sensor of the present invention is a contact type image sensor in which a plurality of substrates each having an illumination window and a photoelectric conversion element are arranged on a support plate and bonded to form a single unit. It is characterized in that a material having a linear expansion coefficient equivalent to that of the substrate material is used.

Glass plates such as Pyrex glass, quartz glass, blue plate glass, and metal plates such as AQ and SO5 are generally used as substrates and support plates for contact type image sensors. The linear expansion coefficients of these materials are as follows.

Coefficient of linear expansion Quartz glass approx. 0.4 x 10-' blue plate glass approx. 8-10 x 10-' AQ
Approximately 23~29 x 10-'SUS
Approximately 10 to 16 x 10-' In the present invention, materials having the same coefficient of linear expansion are selected from among the above materials as the substrate and the support plate, but generally the same materials are used. For example, if Pyrex glass is used as the substrate, Pyrex glass is used as the support plate.

On the other hand, as the adhesive for bonding the substrate and the support, room temperature UV curable adhesives (e.g. room temperature UV curable acrylic adhesives), epoxy adhesives, etc. are used as in the past. Or, when a transparent glass plate is used as the support, an adhesive having a refractive index equivalent to that of the glass, such as a room temperature ultraviolet curable acrylic adhesive, is preferred. Further, in this case, an acrylic adhesive may be used only on the side surface of the substrate connection portion (a portion serving as an optical path), and another adhesive, such as an epoxy adhesive, may be used on the bonding portion between the substrate and the support plate.

In the present invention, in order to prevent the adhesive from extruding at the board connection part and to improve the accuracy of connecting the photoelectric conversion elements, the side surface of the board connection part is shaped like an arc (however, the contact point between both boards is shaped like an arc, as shown in Fig. 2). It is preferable to process it into an arc having its center on the substrate surface so that it lies on the surface on the photoelectric conversion element side.

In addition, in the present invention, in order to maximize the amount of light from the light source by bringing the light source as close as possible to the substrate, the substrate 3 (in this case, a transparent glass plate) is provided with a lighting window, as shown in FIG. 3 (cross-sectional view). It is preferable that the support plate 4 is bonded to the support plate 4 except for the portion immediately below the support plate 1 and one side thereof (the left side in FIG. 4). Note that 7 is a light shielding layer and 8 is a light source.

The method for manufacturing the image sensor of the present invention may be the same as the conventional method except for using the substrate and support as described above. For example, if the same type of glass plate is used for the substrate and the support plate, first, a metal (such as Cr,
After providing a light shielding layer made of Ni, Mo, Ti, etc., a transparent inorganic insulating material (e.g. 5xOz*5x3N4tSxO
xNy, etc.), a lower electrode made of the same material as the light-shielding layer is provided on top of that, an a-3i-based photoelectric conversion layer is provided on top of that, and a transparent inorganic conductive material (such as ITO) is provided on top of that. , SiO, etc.) to form a photoelectric conversion element, and if necessary, a transparent protective layer made of the above-mentioned transparent inorganic insulating material is provided on the entire surface, or a thin plate glass (e.g. quartz glass, Pyrex glass, etc.) is provided on the entire surface. etc)
Just glue it on.

Effects Since the contact image sensor of the present invention uses a material for the support plate that has the same coefficient of linear expansion as the substrate material,
Even if heated by a light source or the like, the adhesive layer or the substrate will not be damaged, and therefore deterioration of the MTF can be prevented. Further, when the side surface of the substrate connection part is formed into an arc shape as shown in FIG. 3, it is possible to prevent the adhesive from extruding and to improve the accuracy of connecting the photoelectric conversion elements. Furthermore, if the substrate and support are bonded together as shown in FIG. 4, the amount of light from the light source can be utilized to the maximum.

[Brief explanation of the drawing]

FIGS. 1(a) and 3(b) are side sectional views of a conventional contact-type image sensor at normal temperature and when heated, respectively, and FIGS.
The figures are a side sectional view and a cross sectional view, respectively, of a contact type image sensor according to an example of the present invention. 1...Lighting window 2...Photoelectric conversion element 3...
・Substrate 4... Support plate 5... Adhesive or adhesive layer 6... Original 7... Light shielding layer 8... Light source Patent applicant Rico Co., Ltd. - Agent Patent attorney Sa 1) Mamoru 1 male, 3 tails (¥)

Claims (1)

[Claims] 1. In a close-contact image sensor formed by arranging a plurality of substrates equipped with illumination windows and photoelectric conversion elements on a support plate and bonding them together, the material of the support plate has a coefficient of linear expansion that is substantially the same as that of the substrate material. A close-contact image sensor characterized by using a sensor having: