Sheet-supply device and image forming device including same

An image forming device comprising:

• a sheet-supply device for supplying sheets from a stack of sheets one at a time in a guide direction, the sheet-supply device including:
• a sheet supporting member with a sheet-supporting surface that supports the stack of sheets;
• a sheet feed unit applying a force to a sheet in the stack to move the sheet in a sheet feed direction;
• a guide member disposed at a downstream side of the sheet supporting member with respect to the sheet feed direction, the guide member having a guide surface that guides the sheet in the guide direction as the sheet slides across the guide surface, the guide surface generating a resistance to sliding movement of sheets;
• a stopper member disposed in the guide member and having a stack-slippage prevention surface capable of imparting a larger resistance to sliding movement of sheets than the guide surface, the stopper member being movable between:
• a protruding position wherein the stack-slippage prevention surface of the stopper member protrudes away from the guide surface in a direction substantially opposite from the sheet feed direction to a position into abutment with the stack of sheets to impart the larger resistance on the stack of sheets;
• and
• a retracted position wherein the stack-slippage prevention surface of the stopper member is retracted away from the guide surface in substantially the sheet feed direction to a position out of contact with the stack of sheets so that the stack-slippage prevention surface does not impart the larger resistance on the stack of sheets;
• and
• a stopper moving mechanism that selectively moves the stopper member between the protruding position and the retracted position;
• and
• an image forming portion disposed downstream from the sheet-supply device in the guide direction, the image forming portion forming images on sheets supplied by the sheet-supply device.