In one example in accordance with the present disclosure, a sheet transport device is described. The sheet transport device includes a pickup roller to insert a sheet into a sheet path. A pair of separation rollers of the sheet transportation device form a nip that advances the sheet along the sheet path. A first separation shaft on which a first separation roller is disposed rotates in a first direction as the sheet is advanced and a second separation shaft on which a second separation roller is disposed also rotates in the first direction as the sheet is advanced. The second separation roller is driven in a second direction via a torque limiter. A motor rotates the shafts. A one-way clutch is disposed on the second separation shaft to disengage the second separation shaft from the motor when the motor is operating in a reverse mode.

The feeding apparatus includes a pick-up roller, a feed roller, a separation roller which forms a separation nip portion with the feed roller, an encoder, and an engine control unit. The engine control unit obtains variation in rotation speed of the separation roller based on a detection result of the encoder, and determines a life condition of the separation roller based on the obtained variation in rotation speed of the separation roller.

A document sheet transportation device includes a feeding portion which feeds a document sheet from a document sheet placement portion toward a document sheet transportation path. The feeding portion includes a holder, a feeding member, a supporting body supported by the holder, a rotatable stopper member having a contact end portion allowed to contact a front end of a document sheet, and a biasing member which applies a biasing force to the stopper member. The stopper member is allowed to change a position among a first position in which the contact end portion contacts the front end of the document sheet, a second position which allows feeding of the document sheet by the feeding member, and a third position which is rotated in the first rotating direction from the second position. The biasing member applies the biasing force to the stopper member in a reverse second rotating direction.

A medium transportation device includes a transportation driving roller that transports a medium; a roller unit including a separation roller as a driven roller that is rotated by rotation of the transportation driving roller and a shaft which penetrates a rotation center of the separation roller; a holder that detachably holds the roller unit; and a lock mechanism that switches between an unlocked state in which the roller unit is unlocked from the holder and a locked state in which the roller unit is locked to the holder.

In one example in accordance with the present disclosure, a sheet transport device is described. The sheet transport device includes a pickup roller to insert a sheet into a sheet path. A pair of separation rollers of the sheet transportation device form a nip that advances the sheet along the sheet path. A first separation shaft on which a first separation roller is disposed rotates in a first direction as the sheet is advanced and a second separation shaft on which a second separation roller is disposed also rotates in the first direction as the sheet is advanced. The second separation roller is driven in a second direction via a torque limiter. A motor rotates the shafts. A one-way clutch is disposed on the second separation shaft to disengage the second separation shaft from the motor when the motor is operating in a reverse mode.

In one example in accordance with the present disclosure, a sheet transport device is described. The sheet transport device includes a pickup roller to insert a sheet into a sheet path. A pair of separation rollers of the sheet transportation device form a nip that advances the sheet along the sheet path. A first separation shaft on which a first separation roller is disposed rotates in a first direction as the sheet is advanced and a second separation shaft on which a second separation roller is disposed also rotates in the first direction as the sheet is advanced. The second separation roller is driven in a second direction via a torque limiter. A motor rotates the shafts. A one-way clutch is disposed on the second separation shaft to disengage the second separation shaft from the motor when the motor is operating in a reverse mode.

A document sheet transportation device includes a feeding portion which feeds a document sheet from a document sheet placement portion toward a document sheet transportation path. The feeding portion includes a holder, a feeding member, a supporting body supported by the holder, a rotatable stopper member having a contact end portion allowed to contact a front end of a document sheet, and a biasing member which applies a biasing force to the stopper member. The stopper member is allowed to change a position among a first position in which the contact end portion contacts the front end of the document sheet, a second position which allows feeding of the document sheet by the feeding member, and a third position which is rotated in the first rotating direction from the second position. The biasing member applies the biasing force to the stopper member in a reverse second rotating direction.

The feeding apparatus includes a pick-up roller, a feed roller, a separation roller which forms a separation nip portion with the feed roller, an encoder, and an engine control unit. The engine control unit obtains variation in rotation speed of the separation roller based on a detection result of the encoder, and determines a life condition of the separation roller based on the obtained variation in rotation speed of the separation roller.

In one example in accordance with the present disclosure, a sheet transport device is described. The sheet transport device includes a pickup roller to insert a sheet into a sheet path. A pair of separation rollers of the sheet transportation device form a nip that advances the sheet along the sheet path. A first separation shaft on which a first separation roller is disposed rotates in a first direction as the sheet is advanced and a second separation shaft on which a second separation roller is disposed also rotates in the first direction as the sheet is advanced. The second separation roller is driven in a second direction via a torque limiter. A motor rotates the shafts. A one-way clutch is disposed on the second separation shaft to disengage the second separation shaft from the motor when the motor is operating in a reverse mode.

A medium transportation device includes a transportation driving roller that transports a medium; a roller unit including a separation roller as a driven roller that is rotated by rotation of the transportation driving roller and a shaft which penetrates a rotation center of the separation roller; a holder that detachably holds the roller unit; and a lock mechanism that switches between an unlocked state in which the roller unit is unlocked from the holder and a locked state in which the roller unit is locked to the holder.