A sheet feeding device includes a tray to store a stack of sheets, and a sheet elevation mechanism provided at the bottom of the tray to lift the stack of sheets until a top sheet of the stack of sheets reaches a predetermined height position. A paper feed roller is disposed above the tray to come in contact with the top sheet having reached the predetermined height position and rotated by a motor to deliver the top sheet from the tray. Additionally, the sheet feed device includes a controller to control the sheet elevation mechanism based on a drive torque of the motor to adjust the height position of the stack of sheets, after delivery of the first sheet from the tray by the paper feed roller and upon delivery of a second sheet by the paper feed roller. The frictional force to be produced between the second sheet and the paper feed roller is substantially equal to the frictional force produced between the first sheet and the paper feed roller during delivery of the first sheet.

A supply apparatus that supplies corrugated cardboard sheets to a supply position in a box-making section that opens folded corrugated cardboard sheets and makes boxes. The supply apparatus comprises a conveying unit, a drive unit, and a control unit. The conveying unit conveys a plurality of the corrugated cardboard sheets to the supply position with the corrugated cardboard sheets stacked. The drive unit drives the conveying unit. A controller, serving as the control unit, estimates the total quantity of the plurality of stacked corrugated cardboard sheets on a conveying surface of the conveying unit. The controller acquires a value pertaining to the drive force of the drive unit when the drive unit drives the conveying unit, and estimates the total quantity of the plurality of stacked corrugated cardboard sheets on the basis of the acquired value.

A sheet transport device includes: a curved sheet transport path; multiple transport roller pairs disposed in the sheet transport path; multiple driving sources that drive the multiple transport roller pairs; multiple load detectors that detect the loads of the multiple driving sources; and a control unit that controls the driving speed of at least one of the driving sources such that detection results obtained by the load detectors are within a predetermined range in accordance with the position of the leading end of a sheet.

According to one embodiment, a sheet feed device includes a first roller, a second roller, a torque limiter, a holder, and a driving unit. The first roller conveys a sheet in a first direction while being in contact with a first surface of the sheet. The second roller faces the first roller and is in contact with a second surface which is a back side of the first surface of the sheet in a state of sandwiching the sheet between the second roller and the first roller. The torque limiter imparts an anti-torque to the second roller in order to generate a force on the second surface in a direction opposite to the first direction. The holder rotatably supports the second roller. The driving unit moves the holder and biases the holder toward the first roller.

A method for feeding a material strip to the processing zone of a punch press, wherein the material strip is clamped between a pair of feed rollers and is fed intermittently by rotating the feed rollers at intervals, and wherein the following steps are carried out after each feed of the material strip and before the next feed of the material strip in a feed pause with the material strip stationary and clamped between the feed rollers: holding the material strip by fixing the feed rollers with a certain holding torque; temporarily reducing or eliminating the holding torque of the feed rolls; positioning the strip of material with the holding torque of the feed rollers reduced or removed by inserting one or more pilot pins into associated pilot holes in the strip of material, the strip of material being displaced by the pilot pin or pins and the feed rollers being rotated by the strip of material clamped between them as it is displaced, optionally overcoming the reduced holding torque; and re-extending the pilot pin(s) from the pilot holes of the material belt. This method makes it possible to achieve a highly precise strip feed even without complex intermediate lifting mechanisms.

In a printer, an accommodating portion accommodates roll paper. A supply roller pair is disposed upstream of a recording unit in a transport direction, and nips the roll paper. The intermediate roller pair is rotatably disposed between the supply roller pair and the accommodating portion, and nips the roll paper. A second motor and a third motor apply tension to the roll paper between the intermediate roller pair and the accommodating portion. A control unit can switch between a first mode and a second mode. In the first mode, first tension is applied to the roll paper between the intermediate roller pair and the accommodating portion. In the second mode, second tension smaller than the first tension is applied.

In a printer, an accommodating portion accommodates roll paper. A supply roller pair is disposed upstream of a recording unit in a transport direction, and nips the roll paper. The intermediate roller pair is rotatably disposed between the supply roller pair and the accommodating portion, and nips the roll paper. A second motor and a third motor apply tension to the roll paper between the intermediate roller pair and the accommodating portion. A control unit can switch between a first mode and a second mode. In the first mode, first tension is applied to the roll paper between the intermediate roller pair and the accommodating portion. In the second mode, second tension smaller than the first tension is applied.

An image forming apparatus is provided. The image forming apparatus includes an engine unit to be used for performing an image forming job, a motor to start the engine unit, a driver circuit to sense a current flowing in the motor and supply the motor with a power source, and a processor to determine a load size of the motor based on the sensed current and control a driving speed of the motor based on the determined load size.

An image forming apparatus is provided. The image forming apparatus includes an engine unit to be used for performing an image forming job, a motor to start the engine unit, a driver circuit to sense a current flowing in the motor and supply the motor with a power source, and a processor to determine a load size of the motor based on the sensed current and control a driving speed of the motor based on the determined load size.

In a printer, an accommodating portion accommodates roll paper. A supply roller pair is disposed upstream of a recording unit in a transport direction, and nips the roll paper. The intermediate roller pair is rotatably disposed between the supply roller pair and the accommodating portion, and nips the roll paper. A second motor and a third motor apply tension to the roll paper between the intermediate roller pair and the accommodating portion. A control unit can switch between a first mode and a second mode. In the first mode, first tension is applied to the roll paper between the intermediate roller pair and the accommodating portion. In the second mode, second tension smaller than the first tension is applied.