| 摘要 |
PURPOSE:To achieve shading correction at AD conversion of a video signal, by obtaining a reference voltage through the use of a light outside the scanning region of original plane of a scanner. CONSTITUTION:An original 2 is located on a contact glass 1 and a reflection plate 8 is located outside the scanning region of this original. When a light source 3 scans the reflection plate 8, the reflected light from the reflection plate 8 is inputted to a line image sensor 7. In this case, an analog switch SW1 is opened with a control signal CS1 and a prescribed reference voltage Vref is given to an AD converter A/D. The output of the line image sensor 7 is transmitted to the AD converter A/D through an AMP and stored to a RAM as shading correction information in 4-bit. The video information with good fidelity can be obtained through the correction of shading of the original scanning output with this information. |
