Sheet feeding device, sheet treating device and image reading apparatus using the same

An image reading apparatus comprising:

• a separating portion for separating and conveying sheet-shaped originals one by one by a forwardly rotating conveying rotary member and a reversely rotating separating rotary member;
• center distance changing means for relatively changing a center distance between the conveying rotary member and the separating rotary member;
• control means for controlling the center distance changing means;
• adjusting means for adjusting a brightness of a read image;
• display means for displaying an adjusted value of the brightness of the read image;
• a first switch for arbitrarily selecting between a first sheet feeding mode for effecting sheet feeding while automatically adjusting the center distance for each original, and a second sheet feeding mode for effecting sheet feeding with the center distance fixed;
• and
• a second switch for switching a propriety of a center distance setting input for effecting a setting of the center distance when the second sheet feeding mode is selected;
• wherein when the center distance setting input is made possible by said second switch, the setting of the center distance is effected by said adjusting means for adjusting the brightness of the read image, and a set value of the center distance is displayed by said display means for displaying an adjusted value of the brightness of the read image.

A sheet feeding device comprising:

• a sheet separating portion which forwardly rotates a first roller member and reversely rotates a second roller member to separate sheets one by one;
• a center distance adjusting portion which automatically adjusting a center distance between said first roller member and said second roller member in accordance with a thickness of a sheet to be fed;
• a selecting portion which selects between a first sheet feeding mode and a second sheet feeding mode;
• and
• a controlling portion which, in said first sheet feeding mode, feeds sheets while automatically adjusting the center distance by said center distance adjusting portion with respect to each of a plurality of sheets to be fed, and which, in said second sheet feeding mode, feeds sheets while automatically adjusting the center distance by said center distance adjusting portion with respect to one of a plurality of sheets to be fed, and while assuming an automatically adjusted center distance to be a fixed value with respect to the other sheets.