| 摘要 |
PURPOSE:To reduce the influence of temperature variation upon an image forming element by charging liquid which has large specific gravity among respective elements which constitute an optical image formation system. CONSTITUTION:The optical image formation system consisting of three groups of lens arrays 1-3 made of plastic include the arrays 1-3 at specific intervals, and optical axes of lenses constituting the arrays are made coincident with optical axes of lenses constituting other arrays. An information reader forms an original image of an original surface 0 on a photodetection surface 4 through the optical image formation system and reads it. The arrays 1-3 are fixed at specific mutual intervals so that the optical axes of the lenses are made coincident by a sealing plate 6 parallel to the optical axes. Further, the liquid 7 which has large specific heat is charged among the arrays 1-3 sealed by the sealing plate 6. This constitution increases the heat capacity of the whole optical image formation system, so the generation of the temperature distribution of the optical image formation system due to the heat generation of a light source is suppressed to hold the whole optical image formation system at nearly constant temperature, thereby obtaining performance as designed.
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