A phase detector is provided. The phase detector includes a signal selector, a bias level generator, and a phase information detector. The signal selector selects, as a selected sensor signal, one of a plurality of sensor signals each having a signal level corresponding to a phase of a rotor. The bias level generator divides a signal level difference between a pair of sensor signals, including the selected sensor signal and other sensor signal of the plurality of sensor signals other than the selected sensor signal, at a first ratio, to generate a first bias level. The phase information detector generates a threshold level corresponding to the phase of the rotor based on the first bias level, and detects the signal level of the selected sensor signal reaching the threshold level.

A conveyor includes: a slide gear and a clutch gear including a first gear and a second gear. The clutch gear includes: a first surface and a second surface provided on one of the first and second gears and facing each other; and a contact member provided on the other of the first and second gears and located between the first surface and the second surface. A controller is configured to: control a motor in a state in which the slide gear and the first gear are in mesh with each other, to rotate the clutch gear to establish a state in which the contact member is not in contact with the first surface or the second surface; and control a sliding mechanism to slide the slide gear in the state in which the contact member is not in contact with the first surface or the second surface.

An image forming system has a transmission assembly, standard and auxiliary sheet feeders, standard and auxiliary trays, an image forming device and a controller. The transmission assembly is for switching transmission of a drive force of a motor selectively to the one of the standard and auxiliary sheet feeders. The controller determines whether sheet is absent in the standard tray. The controller, based on determining the sheet is absent in the standard tray and receipt of preceding data, control the transmission assembly to initiate to switch the transmission of the drive force to the auxiliary sheet feeder. Also the controller, based on receipt of control data received after preceding data, control the image forming device to form an image based on the control data.

A braking content determiner determines a content of braking control on a rotating operation such that rotation of a paper feeding motor stops within a time required for stopping from a time point of detection of a sheet by a sheet sensor to a time point of passing of a trailing edge of the sheet through a paper feeding roller, the time required for stopping being determined based on a length of the sheet in a sheet conveying direction, a predetermined speed of the paper feeding roller, and a distance between the paper feeding roller and the sheet sensor in a sheet conveying route. A controller performs the braking control on the rotating operation of the paper feeding motor, according to the content determined by the braking content determiner, upon or prior to the detection by the sheet sensor of the sheet sent out by the paper feeding roller.

A method and a device for combining an auxiliary stack and a main stack include a rake carrying the auxiliary stack and being abruptly movable out of a stack area to prevent sheets that contact the rake from being entrained and to preserve the structure of the stack. A sheet-fed printing press or sheet punching machine having the device is also provided.

A sheet processing device in an embodiment includes a processing section, a tray, a lifting and lowering device, a flexible member, a first member, and a second member. The processing section processes a sheet. The sheet can be placed on a first surface on a first side of the tray. The lifting and lowering device moves the sheet to the processing section. The flexible member is provided on the first side of the tray and has flexibility. The first member is connected to a first end portion of the flexible member. The second member is connected to a second end portion opposite to the first end portion of the flexible member. The second member is separated from the first member in a first direction. A separation distance between the second member and the first member is shorter than length of the flexible member between the second member and the first member.

The unfolding device includes a frame that provides a space for placing an empty box, a plurality of stress concentrating members that unfolds a plurality of corners of the empty box, a plurality of movable portions, and a power transmission portion that transmits power for moving the stress concentrating member via the movable portion. The stress concentrating member is brought into contact with the inside of the empty box from the opening side of the empty box, thereby placing the empty box. The power transmission portion transmits, to the stress concentrating member, power for moving the stress concentrating member so as to bring the stress concentrating member into contact with the corner. The power transmission portion transmits the power to the stress concentrating member so that the stress concentrating member unfolds the corner by tearing and opening the corner.