Transport device, transport method, image forming apparatus, and image forming method for sheet transport control using sheet length

1. A transport device comprising:

a transport unit configured to transport a paper sheet;

a cutter unit configured to cut the paper sheet; and

a controller configured to, when transport of the paper sheet in the vicinity of the cutter unit is to be halted, control the transport unit so that the transport unit transports the paper sheet by a longer travel when a specified length of the paper sheet is shorter than a threshold length than when the specified length of the paper sheet is longer than the threshold length,

wherein the cutter unit is configured to cut the paper sheet, transported by the transport unit, at the ideal cut line where a resulting cut sheet has the specified length,

wherein the transport unit comprises:

a first transport section configured to transport the paper sheet and then halt the transport of the paper sheet so that the ideal cut line is placed at the cutter unit; and

a second transport section configured to transport the paper sheet downstream of the cutter unit in a direction of transport, and halt the transport of the leading end of the paper sheet at a standby position if the leading end of the paper is to remain on standby, and

wherein the controller is configured to switch between a first transport control operation and a second transport control operation,

wherein the controller is configured to, in the first transport control operation, if a timing of the second transport section causing the leading end of the paper sheet to halt comes before a timing of the first transport section causing the paper sheet to halt to place the ideal cut line at the cutter unit, control the second transport section to cause the leading end to halt in accordance with the length of the paper sheet while controlling the first transports to cause the paper sheet to halt before the ideal cut line reaches the cutter unit, and

wherein the controller is configured to, in the second transport control operation, control the second transport section to cause the leading end to halt while controlling the first transport section to transport the paper sheet until the cut line reaches the cutter unit and then control the transport of the paper sheet to halt.

2. The transport device according to claim 1 , wherein the controller is configured to shift to the second transport operation at a timing of starting deceleration of a transport speed of the paper sheet in the course of adjusting the speed of the paper sheet after the first transport section causes the paper sheet to halt once before the ideal cut line reaches the cutter unit in the first transport operation.

3. The transport device according to claim 1 , further comprising an accommodating unit that accommodates curving of the paper sheet occurring in a paper transport path between the cutter unit and the standby position.

4. The transport device according to claim 3 , wherein the controller is configured to control the transport unit to transport the paper sheet in the first transport control operation if the transport of the paper sheet in the second transport operation would cause the paper sheet to curve to a maximum of curving accommodated by the accommodating unit or more before the ideal cut line reaches the cutter unit.

5. The transport device according to claim 1 , wherein the transport unit comprises a stepping motor as a driving source; and

wherein the controller is configured to shift to the second transport operation at a timing of the first transport section starting deceleration of a transport speed of the paper sheet to cause the ideal cut line to reach the cutter unit while the stepping motor accelerates after the first transport section causes the paper sheet to halt once while the second transport section halts the leading end in the first transport control operation.

6. The transport device according to claim 1 , wherein the controller is configured to switch between a third transport control operation and a fourth transport control operation,

wherein the controller is configured to, in the third transport control operation, if a timing of the second transport section causing the leading end of the paper sheet to halt comes after a timing of the first transport section causing the paper sheet to halt to place the ideal cut line at the cutter unit, control the second transport section to cause a leading paper sheet cut by the cutter unit and transported by the first transport section to halt in accordance with the length of the paper sheet, and control the first transport section to transport the leading paper sheet and a subsequent paper sheet in succession to the cut leading paper sheet with a first paper sheet spacing therebetween, and

wherein the controller is configured to, in the fourth transport control operation, control the second transport section to halt the transport of the leading paper sheet and control the first transport section to transport the subsequent paper sheet together with the leading paper sheet with a second paper sheet spacing therebetween different from the first paper sheet spacing.

7. An image forming apparatus comprising:

the transport device of claim 1 ; and

an image forming unit configured to form an image on the paper sheet transported by the transport unit.

8. A transport device comprising:

a transport unit configured to transport a paper sheet;

a cutter unit configured to cut the paper sheet; and

a controller configured to, when transport of the paper sheet in the vicinity of the cutter unit is to be halted, control the transport unit so that the transport unit transports the paper sheet by a longer travel when a specified length of the paper sheet is shorter than a threshold length than when the specified length of the paper sheet is longer than the threshold length,

wherein the controller is configured to switch between a first mode performed when a length of the paper sheet is longer than the threshold length and a second mode performed when the length of the paper sheet is shorter than the threshold length,

wherein the controller is configured to cause, in the first mode, an ideal cut line corresponding to the length of the paper sheet to be halted when a leading end of the paper sheet is halted, and

wherein the controller is configured to, in the second mode, transport the ideal cut line to the cutter unit while the leading end of the paper sheet remains halted.

9. A transport method comprising:

transporting a paper sheet;

cutting the paper sheet by a cutter unit; and

when transport of the paper sheet in the vicinity of the cutter unit is to be halted, controlling the transport of the paper sheet so that the paper sheet is transported by a longer travel when a specified length of the paper sheet is shorter than a threshold length than when the specified length of the paper sheet is longer than the threshold length,

wherein the cutting comprises cutting the paper sheet, transported by the transport unit, at the ideal cut line where a resulting cut sheet has the specified length,

wherein the transporting comprises:

transporting, by a first transport section, the paper sheet and then halting the transport of the paper sheet so that the ideal cut line is placed at the cutter unit; and

transporting, by a second transport section, the paper sheet downstream of the cutter unit in a direction of transport, and halting the transport of the leading end of the paper sheet at a standby position if the leading end of the paper is to remain on standby, and

wherein the controlling the transport of the paper sheet comprises switching between a first transport control operation and a second transport control operation,

wherein the first transport control operation comprises, if a timing of the second transport section causing the leading end of the paper sheet to halt comes before a timing of the first transport section causing the paper sheet to halt to place the ideal cut line at the cutter unit, then controlling the second transport section to cause the leading end to halt in accordance with the length of the paper sheet while controlling the first transport section to cause the paper sheet to halt before the ideal cut line reaches the cutter unit, and

wherein the second transport control operation comprises controlling the second transport section to cause the leading end to halt while controlling the first transport section to transport the paper sheet until the cut line reaches the cutter unit and then controlling the transport of the paper sheet to halt.

10. An image forming method comprising:

the transport method of claim 9 ; and

forming an image on the transported paper sheet.

11. A transport method comprising:

transporting a paper sheet;

cutting the paper sheet by a cutter unit; and

when transport of the paper sheet in the vicinity of the cutter unit is to be halted, controlling the transport of the paper sheet so that the paper sheet is transported by a longer travel when a specified length of the paper sheet is shorter than a threshold length than when the specified length of the paper sheet is longer than the threshold length,

wherein the controlling the transport of the paper sheet comprises switching between a first mode performed when a length of the paper sheet is longer than the threshold length and a second mode performed when the length of the paper sheet is shorter than the threshold length,

wherein the controlling the transport of the paper sheet comprises causing, in the first mode, an ideal cut line corresponding to the length of the paper sheet to be halted when a leading end of the paper sheet is halted, and

wherein the controlling the transport of the paper sheet comprises, in the second mode, transporting the ideal cut line to the cutter unit while the leading end of the paper sheet remains halted.