| 摘要 |
PURPOSE:To execute an adjustment to an exposure quantity optimum for a picture read operation by exposing a reference plate, feeding back an output signal of a sensor which receives a reflected light from this reference plate, to a liquid crystal shutter, and executing a correction corresponding to a change in the lapse of time of a light source, an environmental variation of a temperature, etc., and a variation of an impressed voltage. CONSTITUTION:A liquid crystal shutter 56 is provided on a light irradiating part of a light source 21, and also a reflected light from a reference plate 19 of a color determined in advance, such as white, etc. formed at a position preceding a scanning exposure of an original 18 is led to a CCD sensor 51 through a reflecting mirror 25' and a lens 26, and an output signal of the CCD sensor 51 is impressed to each segment 57 of the liquid crystal shutter 56 through a control circuit 52 and a driving circuit 53. Also, the output signal of the CCD sensor 51 is impressed to a binary-coding circuit 54, too, and a binary-coded signal is impressed to a memory, etc. 55. The liquid crystal shutter 56 is controlled to a light shutting area and a light transmitting area, having a shape corresponding to the output signal of each part of the CCD sensor 51, and an illuminance distribution on a photosensitive body can be equalized. |
