Image reading apparatus

• US 5,350,914 A
• Filed: 08/05/1992
• Issued: 09/27/1994
• Est. Priority Date: 08/09/1991
• Status: Expired due to Term

• Current Assignee: Agfa-Gevaert N.V., Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Hotta, Hiroyuki
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US07/924,905
• Time in Patent Office: 783 Days
• Field of Search: 250/214.1, 250/208.1, 250/208.2, 257/443, 358/482, 358/483
• US Class Current: 250/208.1
• CPC Class Codes: H01L 31/02161 for devices characterised by at least one potential jump barrier or surface barrier

Abstract

An image reading apparatus includes a protective plate for securing photoelectric elements from wear and secondary incidence of rays of light. The amount of light of secondary incidence upon the photoelectric elements is governed by the total thickness of the protective plate and an adhesive layer, so that the amount of light of secondary incidence can be reduced to a desired level or less by setting the total thickness of the two layers to at least a certain value, derived from a function of the desired ratio of the amount of secondarily incident light upon the photoelectric elements to the total amount of light totally reflected at the boundary of the protective layer with the outside air.

Claims

1. An image reading apparatus comprising:

a substrate;

a plurality of photoelectric elements arranged in substantially the same plane on said substrate;

an adhesive layer of a transparent adhesive material formed on said photoelectric elements and a remaining portion of said substrate not underlying said photoelectric elements; and

a protective plate disposed on said adhesive layer, there being thus a lower boundary separating said protective plate and said adhesive layer and an upper boundary separating said protective plate and outside air, said protective plate made of a transparent material having a refractive index substantially equal to that of said adhesive layer;

wherein the following expression is satisfied,

space="preserve" listing-type="equation">d≧

L((n.sup.2 -1).sup.1/2 /(4 sin 0.9A))

where n is a refractive index common to said adhesive layer and said protective plate, d is the sum of the thicknesses of said adhesive layer and said protective plate, A represents as a percentage the ratio of the amount of light of secondary incidence on said photoelectric elements to the amount of light that originates from scattering at and around said photoelectric elements and then is totally reflected at said upper boundary, and L is the length of each of said photoelectric elements in the slow scan direction, wherein A is not more than 10%.

5. An image reading apparatus according to claim 1, wherein A is not more than 3%.

6. An image reading apparatus according to claim 1, wherein A is not more than 2%.

2. An image reading apparatus comprising:

a substrate;

a plurality of photoelectric elements arranged in substantially the same plane on said substrate;

an intermediate layer overlying said photoelectric elements and a remaining portion of said substrate not containing said photoelectric elements; and

a protective plate disposed over said photoelectric elements and separated from said photoelectric elements by said intermediate layer, said intermediate layer having a lower refractive index than that of said protective plate whereby rays of light incident from said intermediate layer into said protective plate are subject to repeated total reflections at an upper boundary and a lower boundary of said protective plate.

3. An image reading apparatus according to claim 2, wherein said intermediate layer is a gas.

4. An image reading apparatus according to claim 2, wherein said intermediate layer is a solid.