Image forming apparatus having sheet retaining function

• US 20050207811A1
• Filed: 03/17/2005
• Published: 09/22/2005
• Est. Priority Date: 03/22/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Fujii, Takayuki, Fukatsu, Yasuo, Kimura, Kuniyasu, Miyake, Toshiyuki
• Granted Patent: US 7,142,806 B2
• Time in Patent Office: Days
• US Class Current: 399/401
• CPC Class Codes: G03G 15/6529 Transporting G03G15/6555 takes precedence
• CPC Class Codes: G03G 2215/00426 Post-treatment device adding qualities to the copy medium product G03G2215/00421 takes precedence
• CPC Class Codes: G03G 2215/00438 Inverter of refeeding path
• CPC Class Codes: G03G 2215/00945 Copy material feeding speed varied over the feed path

Abstract

An image forming apparatus capable of connecting to a sheet post-processing equipment, includes an image forming unit which forms an image on a sheet; a reversing unit which reverses the sheet between front and back sides for forming an image on the back side after an image has been formed on the front side by the image forming unit; a two-sided conveying unit which conveys the sheet having been reversed by the reversing unit to the image forming unit for forming the image on the back side; a retaining unit which temporarily retains the sheet on a conveying path of the two-sided conveying unit by using the reversing unit and the two-sided conveying unit and then discharges the sheet to the sheet post-processing equipment when a post-processing procedure is selected; and a conveyance control unit which controls a conveying speed at a time of discharging the sheet from the two-sided conveying unit to the sheet post-processing equipment to be faster than a conveying speed at a time of conveying the sheet from the reversing unit to the two-sided conveying unit when the post-processing procedure is selected.

Claims

1. An image forming apparatus operable to form images on sheets and connectable a sheet post-processing equipment, comprising:

an image forming unit configured to selectively form an image on front and back sides of a sheet;

a reversing unit configured to reverse the sheet between the front and the back sides so as to facilitate forming an image on another surface after an image has been formed on one surface of the sheet by the image forming unit;

a two-sided conveying unit configured to convey the sheet having been reversed by the reversing unit to the image forming unit to form an image on the other surface side;

a retaining unit temporarily retaining the sheet on a conveying path of the two-sided conveying unit with the reversing unit and the two-sided conveying unit, and then discharging the retained sheet to the sheet post-processing equipment when a post-processing procedure is selected; and

a conveyance control unit controlling a conveying speed, at a time of discharging the sheet from the two-sided conveying unit to the sheet post-processing equipment, to be faster than a conveying speed at a time of conveying the sheet from the reversing unit to the two-sided conveying unit when the post-processing procedure is selected.

2. An image forming apparatus according to claim 1, wherein the conveyance control unit controls the conveying speed at the time of conveying the sheet from the reversing unit to the two-sided conveying unit to be faster than a conveying speed at the time of forming the image by the image forming unit.

3. An image forming apparatus according to claim 1, wherein the reversing unit reverses a conveying direction of the sheet conveyed to said conveying path in said reversing unit in order to convey the sheet to the two-sided conveying unit.

4. An image forming apparatus according to claim 1, wherein the image forming unit includes a fixing unit fixing the images on the sheet, and wherein the conveyance control unit controls the conveying speed of the sheet to be faster after a trailing edge of the sheet has passed through the fixing unit.

5. An image processing apparatus installable to a sheet post-processing equipment, comprising:

an image forming unit configured to form an image on a sheet;

a first conveying portion conveying the sheet having the image formed thereon on a first conveying path;

a retaining unit retaining the sheet conveyed by the first conveying portion in a second conveying path upstream with respect to the sheet post-processing equipment, wherein a conveying direction of the retained sheet discharged from the second conveying path is reverse to a conveying direction of the sheet conveyed to the second conveying path;

a second conveying portion conveying the sheet from the retaining unit to the sheet post-processing equipment; and

a conveyance control unit controlling a conveying speed of the sheet out of the second conveying path to be faster than a conveying speed of the sheet into the second conveying path.

6. An image processing apparatus according to claim 5, further comprising a two-sided conveying mechanism unit operable to re-convey the sheet in order to form an image on another surface of the sheet by the image forming unit after an image has been formed on one surface of the sheet by the image forming unit, wherein the retaining unit provide a conveying path of the sheet for the two-sided conveying mechanism unit.

7. An image processing apparatus according to claim 6, wherein the two-sided conveying mechanism unit includes a reversing unit configured to reverse the sheet between a front and back of the sheet by reversing the conveying direction of the sheet, having the image formed on one side, and a re-conveying portion conveying the sheet reversed by the reversing unit to the image forming unit.

8. An image processing apparatus according to claim 5, wherein the conveyance control unit controls the conveying speed of the sheet into the second conveying path to be faster than a conveying speed of the sheet in the first conveying path.

9. An image processing apparatus according to claim 5, further comprising a sheet discharging unit discharging the sheet when a post-processing procedure is not selected, wherein the retaining unit provides a conveying path of the sheet for the sheet discharging unit.

10. An image forming apparatus capable of connecting to a sheet post-processing equipment, comprising:

an image data inputting unit configured to input a plurality of pages of image data to be formed as images on sheets;

an image forming unit configured to form the image on the sheet based on the image data inputted with the inputting unit;

a retaining unit including a first conveying path branching from a second conveying path of the sheet post-processing equipment, the retaining unit temporarily retaining the sheet having the image formed thereon by the image forming unit, and then while the sheet post-processing equipment is performing post-processing of a sheet bundle, conveying the sheet to the sheet post-processing equipment; and

a control unit differentiating an order of pages on which the image is formed from an order of pages at a time of normally forming the image in the sheet bundle, as to which the sheet post-processing equipment performs the post-processing.

11. An image forming apparatus according to claim 10, wherein the control unit changes an order of a part of pages of sheets which should be retained in the retaining unit and sheets which are not necessary to be retained in the retaining unit.