| 摘要 |
PURPOSE:To obtain an accurate image signal which is not affected by temperature variation with a simple constitution by holding the output of a light shield part for the output of a solid-state image sensor where a part of photodetectors are shielded from light, and performing A/D conversion and outputting the lowest reference voltage. CONSTITUTION:Reflected light from printed matter 3 is image-formed on a CCD 1 through an image forming lens 2. A driving circuit 9 outputs a shift pulse SH and transfer pulses phi1 and phi2 under the command of a control circuit 10, the CCD 1 outputs an image signal V1, and an amplifying circuit 4 inverts and amplifies it to input an image signal V2 to a display device 8 through an A/D converter 6 and an arithmetic circuit 7. A part of the photodetectors of the CCD 1, on the other hand, are shielded from light, so a sample hold circuit 5 holds a signal in a period wherein the amplifying circuit 4 outputs only the image signal from the shielded part, and sends its dark output VD to an arithmetic circuit 7 through the A/D converter 6, so that the dark output component is removed from the image signal V2.
|
