| 摘要 |
PURPOSE:To read optical information accurately by arranging plural photocells on a read sensor and providing a correcting circuit which varies the light intensity of a light source body according to the illuminance of photodetection of those photocells. CONSTITUTION:When reflected light from a label 21 forms an image on a read sensor 30, the light strikes on photocells 34. The cells 34 sense illuminance at their parts and send it to the correcting circuit 35. The circuit 35 amplifies signals from the cells 34 by an amplifier 36 and a current control circuit 37 varies the light intensity of a diode 25 so that the respective signals have the same value. Consequently, an error in the illuminace of the light forming the image on the sensor 30 is due to a difference in optical path length among the respective parts is corrected and the reflected light from the label 21 strikes on any part of the sensor 30 with uniform illuminance. Said correction is made and then a bar code 22 is read by a photoelectric elements 32, so that the information of the bar code is accurately read.
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