Image reading device with protective layers

DETAILED DESCRIPTION An object of the present invention is to resolve such drawbacks and to provide an image reading device with improved durability, capable of relaxing the stress resulting from temperature change or adhesion for preventing the cracks in the protective layer or substrate, and still capable of maintaining a high resolving power.
Another object of the present invention is to provide an image reading device without deterioration in the reading characteristics or image quality.
Still another object of the present invention is to provide an image reading device capable of ensuring stability of the light-receiving unit in the ambient conditions.
Still another object of the present invention is to provide an image reading device provided with: a substrate; an entrance window provided in said substrate and receiving the light illuminating an information bearing member, bearing information to be read; a photosensor provided on said substrate for receiving the light that has entered through said entrance window and has been reflected by said information bearing member; and a protective layer formed on said photosensor opposite to said substrate, in order to maintain a constant distance between said information bearing member and said photosensor; wherein said protective layer has a multi-layer structure of separate functions, comprising a first layer of a first function at the side of photosensor, and a second layer of another function different from said first function.