An image forming device includes an image forming unit, a reading unit, a registration-less unit, and an engine control unit. The reading unit reads a sheet to be conveyed. The engine control unit moves the other end side of the registration-less unit to correct skew. The engine control unit obtains a deviation amount (first deviation amount) of the position of the sheet based on the correction, and changes a sheet conveyance speed from a first speed to a second speed when the sheet enters the registration-less unit. The engine control unit adjusts the timing to change from the first speed to the second speed based on the first deviation amount.

In an image-forming apparatus, when a sheet length of a first sheet is shorter than or equal to a predetermined length, a controller supplies power to an electromagnetic clutch to convey the first sheet and a second sheet so that a sheet gap of the second sheet is equivalent to a first gap. When the sheet length of the first sheet is longer than the predetermined length, the controller supplies power to the electromagnetic clutch to successively convey a first number of sheets so that the sheet gap of each of the first number of sheets is equivalent to the first gap. After the first number of sheets has been conveyed, the controller supplies power to the electromagnetic clutch to convey at least one sheet so that the sheet gap of each of the at least one sheet is equivalent to a second gap greater than the first gap.

A document conveying device includes a document tray, a first rotary member, a first motor, a second rotary member, a second motor, a document feed sensor, and a controller. The controller counts a counted time from the time point that the first motor starts to rotate until the leading end of a document reaches the document feed sensor. When the time resulting from subtracting the counted time from a required sheet-to-sheet time interval is longer than the required speed change time, the controller performs deceleration and post-deceleration acceleration for the first motor. The required speed change time is the time required for speed change from the first rotation speed to the second rotation speed.

A document conveying device includes a document tray, a first rotary member, a first motor, a second rotary member, a second motor, a document feed sensor, and a controller. The controller counts a counted time from the time point that the first motor starts to rotate until the leading end of a document reaches the document feed sensor. When the time resulting from subtracting the counted time from a required sheet-to-sheet time interval is longer than the required speed change time, the controller performs deceleration and post-deceleration acceleration for the first motor. The required speed change time is the time required for speed change from the first rotation speed to the second rotation speed.

A detection device includes a first detection unit that detects a leading edge portion and a trailing edge portion of a medium while the medium is being transported, and a second detection unit that detects both edge portions of the medium in an orthogonal direction that is orthogonal to a transporting direction of the medium while the medium is being transported.

A detection device includes a first detection unit that detects a leading edge portion and a trailing edge portion of a medium while the medium is being transported, and a second detection unit that detects both edge portions of the medium in an orthogonal direction that is orthogonal to a transporting direction of the medium while the medium is being transported.

A conveyance device includes a conveyance roller, a registration roller, a sensor, a mode setting part, a storage, a conveyance state determination part and a drive control part. The mode setting part sets the mode to either a plain paper mode or a tab paper mode. The storage stores threshold information corresponding to the mode. The conveyance state determination part determines, when the plain paper mode is set, whether the conveyance state of the recording medium is a skew conveyance state or a tab paper conveyance state, based on the detection result of the sensor and the plain paper mode threshold information. The conveyance state determination part determines, when the tab paper mode is set, whether the conveyance state of the recording medium is the skew conveyance state or the tab paper conveyance state, based on the detection result of the sensor and the tab paper mode threshold information.

A conveyance device includes a conveyance roller, a registration roller, a sensor, a mode setting part, a storage, a conveyance state determination part and a drive control part. The mode setting part sets the mode to either a plain paper mode or a tab paper mode. The storage stores threshold information corresponding to the mode. The conveyance state determination part determines, when the plain paper mode is set, whether the conveyance state of the recording medium is a skew conveyance state or a tab paper conveyance state, based on the detection result of the sensor and the plain paper mode threshold information. The conveyance state determination part determines, when the tab paper mode is set, whether the conveyance state of the recording medium is the skew conveyance state or the tab paper conveyance state, based on the detection result of the sensor and the tab paper mode threshold information.

A conveyor includes a conveyance roller to convey a conveyed object, a pair of roller supports opposing to each other and supporting both ends of the conveyance roller in an axial direction thereof, a position sensor to detect a position of the conveyed object, and a sensor support supporting the position sensor. Each of the pair of roller supports has an insertion hole into which the sensor support is inserted. The insertion hole determines a position of the sensor support in a direction intersecting an insertion direction of the sensor support. The sensor support includes a positioning portion determining the position of the sensor support with respect to at least one of the pair of roller supports. The positioning portion determines the position of the sensor support in the insertion direction, a direction opposite to the insertion direction, and a rotational direction about an axis along the insertion direction.

A sheet feeder apparatus includes a width detector for a sheet placed on a sheet placement portion, a conveyor for conveying sheets while separating the sheets one by one, a first detector for detecting a sheet having a first width at a plurality of first positions, a second detector for detecting a sheet having a second width that is not detected by the first sheet detector at a plurality of second positions, and a controller for determining skewing of a sheet based on a result of the detection of the sheet performed by the first detector if the width of the sheet is the first width, and determining skewing of a sheet based on a result of the detection performed by the second detector if the width of the sheet is the second width.