Image forming apparatus

Patent metadata

Field	Value
Publication number	US-9454113-B2
Application number	US-201414525343-A
Country	US
Kind code	B2
Filing date	Oct 28, 2014
Priority date	Oct 30, 2009
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

An image forming apparatus includes a sheet feed unit which feeds a sheet to an image forming unit forming an image on the sheet, a re-transport roller which reverses the sheet with a toner image fixed on the sheet and re-transports the sheet to the image forming unit, and a control unit which controls a sheet feed operation of the sheet feed unit for feeding the sheet. As the temperature of the re-transport roller sensed by the temperature sensing unit is decreased, the control unit retards the timing at which the sheet feed unit starts the sheet feed operation when a duplex image formation in which the image is formed on both sides of the sheet is performed after a one-side image formation is completed.

First claim

What is claimed is:

1. An image forming apparatus, comprising:
a sheet feed unit which feeds a sheet to an image forming unit forming a toner image on the sheet;
a fixing unit which fixes the toner image formed by the image forming unit to the sheet;
a re-transport roller which re-transports the sheet with the toner image fixed on one side of the sheet to the image forming unit for forming an image on another side of the sheet; and
a control unit which controls a sheet feed operation of the sheet feed unit, wherein, when a subsequent duplex image formation in which an image is formed on both sides of a sheet is started after a one-side image formation in which an image is formed on one side of a sheet is completed, the control unit reduces a wait time, from the end of a sheet feed operation for feeding a last sheet in the one side image formation to the start of a sheet feed operation for feeding a first sheet in the subsequent duplex image formation, as the number of sheets subjected a preceding duplex image formation, in which an image is formed on both sides of a sheet before the one-side image formation, increases.

2. The image forming apparatus according to claim 1 , wherein, when the subsequent duplex image formation is started after the one-side image formation is completed, the control unit reduces the wait time, as the number of sheets subjected the preceding duplex image formation before the one-side image formation increases, and a time from the end of the preceding duplex image formation to the start of the one-side image formation decreases.

3. An image forming apparatus, comprising:
a sheet feed unit which feeds a sheet to an image forming unit forming a toner image on the sheet;
a fixing unit which fixes the toner image formed by the image forming unit to the sheet;
a re-transport roller which re-transports the sheet with the toner image fixed on one side of the sheet to the image forming unit for forming an image on another side of the sheet; and
a control unit which controls a sheet feed operation of the sheet feed unit, wherein, when a subsequent duplex image formation in which an image is formed on both sides of a sheet is started after a one-side image formation in which an image is formed on one side of a sheet is completed, the control unit reduces a wait time, from the end of a sheet feed operation for feeding a last sheet in the one side image formation to the start of a sheet feed operation for feeding a first sheet in the subsequent duplex image formation, as a time from the end of a preceding duplex image formation, in which an image is formed on both sides of a sheet before the one-side image formation, to the start of the one-side image formation decreases.

4. An image forming apparatus, comprising:
a sheet feed unit which feeds a sheet to an image forming unit forming a toner image on the sheet;
a fixing unit which fixes the toner image formed by the image forming unit to the sheet;
a re-transport roller which re-transports the sheet with the toner image fixed on one side of the sheet to the image forming unit for forming an image on another side of the sheet; and
a control unit which controls a sheet feed operation of the sheet feed unit, wherein, in a case that a subsequent duplex image formation, in which an image is formed on both sides of a sheet, is performed after completion of a one-side image formation, in which an image is formed on one side of a sheet, the control unit sets a shorter wait time, from the end of a sheet feed operation for feeding a last sheet in the one side image formation to the start of a sheet feed operation for feeding a first sheet in the subsequent duplex image formation, when a preceding duplex image formation, in which an image is formed on both sides of a sheet before the one-side image formation, has been executed on a first number of sheets, than a wait time when the preceding duplex image formation has been executed on a second number of sheets fewer than the first number of sheets.

5. The image forming apparatus according to claim 4 , wherein, at a time when starting the subsequent duplex image formation after the completion of the one-side image formation, the control unit sets a shorter wait time, from the end of a sheet feed operation for feeding the last sheet in the one-side image formation to the start of a sheet feed operation for feeding the first sheet in the subsequent duplex image formation, as a number of sheets is increased in the preceding duplex image formation performed before the one-side image formation and/or as a time period from the completion of the preceding duplex image formation to start of the one-side image formation is shortened.

6. An image forming apparatus, comprising:
a sheet feed unit which feeds a sheet to an image forming unit forming a toner image on the sheet;
a fixing unit which fixes the toner image formed by the image forming unit to the sheet;
a re-transport roller which re-transports the sheet with the toner image fixed on one side of the sheet to the image forming unit for forming an image on another side of the sheet; and
a control unit which controls a sheet feed operation of the sheet feed unit, wherein, in a case that a subsequent duplex image formation, in which an image is formed on both sides of a sheet, is performed after completion of a one-side image formation, in which an image is formed on one side of a sheet, the control unit sets a shorter wait time, from the end of a sheet feed operation for feeding a last sheet in the one side image formation to the start of a sheet feed operation for feeding a first sheet in the subsequent duplex image formation, when the one-side image formation is executed after a first time period is elapsed from the completion of a preceding duplex image formation, than a wait time when the one-side image formation is executed after a second time period longer than the first time period is elapsed from the completion of the preceding duplex-side image formation.

Assignees

• Canon Kk

Inventors

• Kuwata Takashi
• Abe Kenji
• Ohta Hideki
• Matsuo Takamichi
• Suzuki Youhei
• Mita Takuro

Classifications

• G03G2215/00599

  Timing, synchronisation · CPC title

• G03G15/2028

  with means for handling the copy material in the fixing nip, e.g. introduction guides, stripping means · CPC title

• G03G2215/00772

  of temperature influencing copy sheet handling · CPC title

• G03G15/6579

  Refeeding path for composite copying · CPC title

• G03G15/234 Primary

  by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters · CPC title