Electrophotography – Document handling – Copy
Reexamination Certificate
1998-07-09
2001-08-14
Grimley, Arthur T. (Department: 2852)
Electrophotography
Document handling
Copy
C271S065000, C271S186000, C271S301000, C399S402000
Reexamination Certificate
active
06275676
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer or the like, and more particularly it relates to an image forming apparatus in which productivity is improved when images are recorded on recording sheets by several times.
2. Related Background Art
Productivity (index for indicating the number of recordable copies per unit time) which is one of performances of an image forming apparatus such as a copying machine is generally determined by a process speed and a conveying distance (interval) between recording sheets.
The process speed is a conveying speed for the recording sheet in an image forming part. The conveying interval of the recording sheet is a distance between a trailing end of a preceding recording sheet and a leading end of a succeeding sheet when images are formed continuously. That is to say, the productivity of the copying machine can be improved by increasing the process speed or by decreasing the conveying interval.
However, the process speed greatly depends upon a processing ability of the image forming part. Accordingly, in order to increase the process speed, an image forming apparatus having a high speed processing ability must be adopted or developed, which leads in increase in the manufacturing cost and which is difficult to realize quickly.
In order to decrease the conveying interval of the recording sheet, there is a danger of arising the following problems.
In case of an image forming apparatus of electrophotographic type, an image is fixed to a recording sheet by heating toner transferred to the recording sheet by means of a fixing device. If the conveying interval is decreased, since the number of recording sheets fixed per unit time is increased, a greater amount of heat is absorbed from the fixing device. As a result, the recording sheet cannot be heated sufficiently, thereby causing poor toner fixing.
On the other hand, in case of an image forming apparatus having a first page processing function, a rear surface discharge mode in which recording sheets on which the images were formed are turned up or reversed and then are stacked on a discharge tray is used. In this case, when a switch-back system in which the recording sheet is temporarily into a reverse path is used as a recording sheet reversing system, since the succeeding recording sheet cannot be conveyed until the preceding recording sheet is discharged from the reverse path, a predetermined conveying interval is required.
Further, in a case where a retard system in which sheets are supplied one by one by means of a supply roller and friction of a separation roller is used, in an area where the sheet is conveyed only by the supply roller and the separation roller, a conveying speed of the recording sheet becomes unstable. Thus, the conveying interval must be increased accordingly.
SUMMARY OF THE INVENTION
Due to the above limitations, the conveying interval cannot merely be decreased, and, thus, it is difficult to improve the productivity by decreasing the conveying interval. In consideration of this, an object of the present invention is to provide an image forming apparatus in which a conveying interval can be decreased regardless of the above limitations thereby to improve productivity.
To achieve the above object, the present invention provides an image forming apparatus having an electrophotographic image forming means for fixing a toner image formed on a sheet to the sheet by heating the toner image, wherein an interval between the sheets when the sheets are continuously sent to the image forming means to form images on both surfaces of plural sheets is selected to become smaller than an interval between the sheets when the sheets are continuously sent to the image forming means to form images on one surfaces of the plural sheets.
Further, the image forming apparatus may comprise a sheet supply means for feeding out the sheet from a sheet containing part, and a re-convey means for returning the sheet on which the image was formed by the image forming means to the image forming means to form the image on the sheet again, and, in the image forming apparatus, when the image is formed on one surface of the sheet, the sheet is fed out from the sheet supply means, and, when the images are formed on both surfaces of the sheet, the sheet is sent to the image forming means again through the re-convey means.
REFERENCES:
patent: 4935786 (1990-06-01), Veeder
patent: 5225881 (1993-07-01), Goto et al.
patent: 5337135 (1994-08-01), Malachowski et al.
patent: 5347351 (1994-09-01), Morita et al.
patent: 5557391 (1996-09-01), Kato et al.
patent: 5893020 (1999-04-01), Atsumi
patent: 0 602 661 (1994-06-01), None
patent: 60-063561 (1985-04-01), None
patent: 60-181757 (1985-09-01), None
patent: 63-300247 (1988-12-01), None
patent: 9-297433 (1997-11-01), None
patent: 10-039559 (1998-02-01), None
European Search Report.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grimley Arthur T.
Noe William A.
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