A transport roller, adapted to be used in a transport apparatus that transports a medium, includes a shaft, and a wheel group. The wheel group includes a plurality of toothed wheels arrayed in a direction in which the shaft extends, the plurality of toothed wheels being held by a holder which is held by the shaft. A plurality of teeth portions are provided on a peripheral surface of the wheel group, the plurality of teeth portions being disposed to be shifted in position from each other in a circumferential direction of the wheel group when the wheel group is viewed from the direction in which the shaft extends.

A conveying apparatus includes: a rotation shaft; a conveying roller secured to the rotation shaft; a driven roller that cooperates with the conveying roller to convey a sheet at a nip position; a supporter supporting the rotation shaft rotatably; and a first guide and a second guide opposed to each other and defining a conveyance path guiding the sheet toward the nip position. The first guide and the second guide respectively have first and second guide surfaces defining the conveyance path. The first guide and the second guide respectively have first and second engaging portions engaged with the rotation shaft at positions different from a position of the supporter in the axial direction of the rotation shaft.

A transporting device includes a first driving roller which transports the base material; a second driving roller which is disposed to be closer to a downstream side of the transporting direction than the first driving roller, and transports the base material; a driven roller which nips the base material between the second driving roller and the driven roller, and rotates together with the second driving roller; and an inter-roller transporting path which is provided between the first driving roller and the second driving roller, and through which the base material is transported in a state where the base material is suspended in a direction of gravity and bent. The second driving roller starts winding the base material at a position which is closer to an upstream side of the transporting direction than a position where the driven roller is in contact with the base material.

A sheet transport device includes pre-transfer sheet-transport rollers that transport a sheet to a transfer position at which an unfixed image is transferred, the pre-transfer sheet-transport rollers including a first roller in which three or more separate rollers attached to a first shaft rotate, and a second roller in which three or more separate rollers attached to a second shaft are in contact with the separate rollers of the first roller and rotate. The hardness of an inner separate roller of the first roller is lower than the hardness of end separate rollers of the first roller. The outside diameter of an inner separate roller of the second roller is greater than the outside diameter of end separate rollers of the second roller.

An image forming apparatus includes a print medium tray in which a print medium is loaded and a pickup roller which is configured to pick up the loaded print medium from the print medium tray. The pickup roller includes at least one first pickup block and at least one second pickup block configured to alternately come into contact with an upper portion of the loaded print medium. Using such a configuration, the pickup performance of the image forming apparatus may be improved.

A paper thickness detecting device that detects a paper thickness in accordance with a detection signal of a displacement sensor, includes: a pair of paper thickness detecting rollers including a first roller and a second roller that pinch a paper conveyed via a pair of conveyance rollers; and the displacement sensor that detects a displacement amount of the pair of paper thickness detecting rollers at the time when the paper passes through the pair of paper thickness detecting rollers, wherein the paper thickness is detected on the basis of the displacement amount of the pair of paper thickness detecting rollers that follows to rotate with respect to the paper conveyed via the pair of conveyance rollers.

A printing apparatus includes a printing unit that prints an image on a sheet by using ink, a feed path along which the sheet is transported toward the printing unit, a switchback mechanism that, when two sides of the sheet are to be printed, switches back the sheet of which one of the two sides has been printed and sends the sheet to the feed path, and a correction roller pair capable of correcting skew of the sheet by having firm contact with the sheet transported along the feed path.

A liquid ejection apparatus, including: a conveyor; and an ejector to eject a liquid; wherein each of an upstream roller pair, a first downstream roller pair, and a second downstream roller pair of the conveyor includes upper and lower rollers to respectively contact front and back surfaces of a recording medium, at least one of the upper and lower rollers being configured to give a conveyance force to the recording medium, wherein a rotation speed of the second downstream roller pair is higher than that of the first downstream roller pair, and the conveyance force of the first downstream roller pair is larger than that of the second downstream roller pair, and wherein the conveyance force of the second downstream roller pair is largest at a position thereof in the first direction which is nearest to the central position of the second downstream roller pair.

A medium feeding device includes an imaging unit which images a medium tip end portion from a position of facing a face of the medium on a downstream side of a nipping position of the medium using a feeding unit and a separating unit; and a determining unit which determines whether or not there is transport disorder by evaluating a state of a boundary between a path member which forms a medium transport path and a medium tip end from image data obtained by the imaging unit, in which the determining unit sets a rectangular determining region including at least a part of the boundary with respect to the image data, and determines whether or not there is transport disorder based on a length of a boundary in the determining region.

A document conveying apparatus includes a first conveying roller for conveying a document stacked on the document tray, a second conveying roller, provided at a downstream side with respect to the first conveying roller, for conveying a document stacked on the document tray, a separation roller, provided at a downstream side with respect to the second conveying roller, for performing separation operation of the document, a driving force transmission mechanism for transmitting the driving force to a driving shaft of the first conveying roller, a driving shaft of the second conveying roller, and a driving shaft of the separation roller, and a first blocking mechanism, provided between the first conveying roller and the driving shaft of the first conveying roller, for blocking a driving force transmitted to the driving shaft of the first conveying roller, for a first certain period of time.