Document feeding apparatus, image reading apparatus, and image forming apparatus

A sheet feeding apparatus comprising:

• a sheet tray provided with a sheet placement surface on which a sheet is to be placed;
• a feed roller configured to feed the sheet placed on the sheet tray in a feeding direction;
• a driving unit including a motor for driving the feed roller and switchable between (a) a first state in which the feed roller is driven by the motor and (b) a second state in which the feed roller is not driven by the motor;
• an arm portion configured to liftably and lowerably support the feed roller, the arm portion lowering the feed roller by the driving unit being changed from the second state to the first state;
• a separation conveying unit disposed downstream of the feed roller with respect to the feeding direction, the separation conveying unit being configured to separate and convey sheets fed by the feed roller, one by one;
• a conveyance roller pair disposed downstream of the separation conveying unit with respect to the feeding direction, the conveyance roller being configured to convey a sheet separated by the separation conveying unit;
• and
• a detecting unit provided with a flag member disposed to protrude upward from the sheet placement surface, the detecting unit being configured to detect presence or absence of the sheet placed on the sheet tray based on a position of the flag member,
• wherein the driving unit changes from the first state to the second state after a first sheet has been fed by the feed roller and reached the conveyance roller pair, and
• wherein the detecting unit detects the presence or absence of a second sheet which is to be fed next after the first sheet has been fed and the driving unit has changed from the second state to the first state.

An image reading apparatus comprising:

• a sheet tray provided with a sheet placement surface on which a sheet is to be placed;
• a feed roller configured to feed the sheet placed on the sheet tray in a feeding direction;
• a driving unit including a motor for driving the feed roller and switchable between (a) a first state in which the feed roller is driven by the motor and (b) a second state in which the feed roller is not driven by the motor;
• an arm portion configured to liftably and lowerably support the feed roller, the arm portion lowering the feed roller by the driving unit being changed from the second state to the first state;
• a separation conveying unit disposed downstream of the feed roller with respect to the feeding direction, the separation conveying unit being configured to separate and convey sheets fed by the feed roller, one by one;
• a conveyance roller pair disposed downstream of the separation conveying unit with respect to the feeding direction, the conveyance roller being configured to convey a sheet separated by the separation conveying unit;
• a detecting unit provided with a flag member disposed to protrude upward from the sheet placement surface, the detecting unit being configured to detect the presence or absence of the sheet placed on the sheet tray based on a position of the flag member;
• and
• a reading sensor configured to read an image of the sheet fed by the feed roller,
• wherein the driving unit changes from the first state to the second state after a first sheet has been fed by the feed roller and reached the conveyance roller pair, and
• wherein the detecting unit detects presence or absence of a second sheet which is to be fed next after the first sheet has been fed and the driving unit has changed from the second state to the first state.