JPH0332948B

PURPOSE:To keep the level of the light emitting quantity constant which is used for each photoelectric conversion of each light source lamp, by using a controlling photosensor which receives directly the light of the lamp and turning off the lamp when the photodetecting quantity of the photosensor reaches a prescribed level. CONSTITUTION:An original table 11 is shifted in the direction rectangular to the lengthwise direction of a photosensor 2 by means of a feed screw 13 which is driven by a subscan motor 12. Light source lamps 6R, 6G and 6B are provided on the rear side of the table 11 and emit the separated beams of three colors R, G and B. The light of the light source transmits through an original 1 and forms an image on the photodetecting surface of a line type CCD photosensor 2 via an optical device 30 like a lens, etc. A control photosensor 6 is set in front of lamps 6R, 6G and 6B respectively to receive directly the beams sent from those three lamps. The output of the sensor 7 is supplied to a light quantity monitor circuit 31. The circuit 31 always checks each effective photodetecting quantity of the sensor 7 and keeps it at a fixed level. The result of this check informed to a timing control circuit 15.