JPS5729002A - Light condensing device - Google Patents

Abstract

PURPOSE:To make the distance between a light source and a read surface long by providing plural laminated light transmittable plates between the light source and a light condensing part, and providing them at the angles at which the rays in said plates are refracted in such a way that their directions are made approximately perpendicular to the thickness direction with respect to a light condensing device such as an OCR or copying device. CONSTITUTION:Light of a light source lamp 3 passes through plural plates 11-13 of light transmittable materials such as glass and irradiates an irradiating part 5. The end faces on the light source side of the plates of the light transmittable materials are provided at angles theta1-theta3 at which the light out from the lamp 3 refracts in the direction of advancing straightforward inside the respective plates 11, 13. The end faces on the light condensing side are provided at the angles theta1'-theta3' at which the beams of said light refract in such a way as to condense at the part 5 at the time of emitting from the trailing ends of the plates 11-13. Further the plates 11-13 are made thickner on both sides than in the center and therefore the angular errors produced with respect to the rays passing through near the circumferential edges of the end faces are roughly uniform with all the plates. With such constitution, the distance (l) from the light source lamp up to the read surface is made long in spite of a small capacity of the light source.