SHADING CORRECTION MECHANISM FOR CLOSE CONTACT SENSOR SYSTEM

摘要

PURPOSE:To secure the unified light quantity and to remove noises produced in a photoelectric transducing mode by printing a pattern which is inversely proportional to the light intensity on a glass plate and then providing this glass plate between an original and a light source and a focusing light transmitter array. CONSTITUTION:A glass plate 7 containing a printed specific pattern is set between a LED array 4 and a focusing light transmitter array 5 and an original 2. An example of the specific pattern on the plate 7 is shown in the figure. The light quantity given from the array 4 irradiates the original 2 with light intensity in a fixed cycle and in proportion to the pattern on the plate 7 when the light of the array 4 is transmitted through the plate 7. Then the light reflected from the original is condensed by the array 5 to irradiate the light receiving part of a close contact sensor 6. Then the white level fluctuation of the output of the sensor 6 is corrected accurately by selecting correctly the light intensity depending on the pattern on the plate 7 and the positional relations of shading characteristics of the sensor 6 and the array 5.