Shading correcting circuit

Abstract

Abstract PURPOSE:To obtain a shading correcting circuit which contains no correction mechanism in its optical path system and is never affected by the change with the lapse of time of the light quantity of a light source like a fluorescent lamp, etc., by proportionating the reference voltage of an A/D converting part corresponding to a picture signal to a shading wave form. CONSTITUTION:When a power supply is applied, a control part 8 starts a photoelectric transducing part 3 and an address counter 6. At the same time, an analog switch 9 selects the reference voltage Vs corresponding to the maximum dynamic range of the output of the part 3 out of a reference voltage generating part 10 in the form of the 1st reference voltage of an A/D converting part 4. When a transmission original is read and scanned, the shading data is read out a line memory 5 for each line as soon as the scan of the original is started and then converted into analog signals by a D/A converting part 7. In response to this operation, the 2nd reference voltage VD is produced from a reference voltage generating part 11. Then the part 4 performs the A/D conversion of the read-out picture signals of the transmission original based on the reference VD.

Inventors

• 👤 Kazuyuki Sumita
• 👤 住田　和之

Bibliographic Details