Photocopying – Projection printing and copying cameras – Photographing on both sides of photo-sensitive paper
Reexamination Certificate
1999-11-23
2001-05-01
Mathews, Alan A. (Department: 2851)
Photocopying
Projection printing and copying cameras
Photographing on both sides of photo-sensitive paper
C355S077000, C399S364000
Reexamination Certificate
active
06226069
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a stackless continuous dual-sided copying method for photocopying machines.
2. Description of Related Art
Among photocopying machines, some are equipped with a continuous dual-sided copying function wherein dual-sided copying is carried out in a circulating conveyance path without stacking the copy sheets following one-sided copying (hereinafter referred to as a stack-less continuous dual-sided copying function). When carrying out continuous dual-sided copying in such photocopiers, copy sheets are fed successively, and reverse-side copying is performed successively on the fed copy sheets. A predetermined position on the circulating conveyance path (hereinafter called the circulatable sheet-count discriminating position) is for discriminating that the number of copy sheets being conveyed has reached a maximum value. The count of copy sheets that can stay in the circulating conveyance path defines this maximum value (hereinafter called the circulatable sheet count). When the sheet on which reverse-side copying was performed first reaches the circulatable sheet-count discriminating position, the copier discriminates that the count of copy sheets in conveyance is the circulatable sheet count, and halts fresh copy-sheet supply.
Thereafter, front-side copying is carried out successively on the copy sheets on which reverse-side copies were made. Then, once the front-side copying operation is performed for the last copy sheet currently being conveyed on the circulating conveyance path, sheet feeding is restarted and the same operations are repeated.
The circulatable sheet count differs according to, for example, copy size, copy mode and sheet-feed level, and therefore the circulatable sheet-count discriminating position also varies according to the copy size, copy mode and sheet-feed level. Therefore, copy-sheet detection sensors are disposed in a plurality of circulatable sheet-count discriminating positions determined beforehand in the circulatable conveyance path. The copy-sheet detection sensors are disposed at circulatable sheet-count discriminating positions determined based upon, in the present instance for example, copy size, copy mode and sheet-feed level. Based on the output from the copy-sheet detection sensors, whether or not the copy sheet on which reverse-side copying was first performed has reached the circulatable sheet-count discriminating position is discriminated.
A problem conventionally has been that discriminating whether the sheet count of copy paper being conveyed on the circulating conveyance path has reached the circulatable sheet count has necessitated utilizing a plurality of copy sheet detection sensors.
Conventionally too, when sheet feeding is resumed, shifting to the next continuous dual-sided copying cycle, copy sheets are fed from a sheet-feeding cassette and conveyed into the circulating conveyance path. The sheet-feeding cassettes are at multiple levels from the copy-sheet conveyance entry position. When sheet-feeding from a cassette that is in a location remote from the conveyance entry position, proceeding from resumption of the sheet-feeding operation to the point at which a copy sheet is conveyed to the registration roller pair takes time. This is a problem in that it lengthens the time it takes for continuous dual-sided copying operations.
SUMMARY OF THE INVENTION
An object of the present invention is to make copy sheet detection sensors used to determine whether or not the number of copy sheets being conveyed along the circulating conveyance path has reached a circulatable sheet count unnecessary by a stackless continuous dual-sided copying method in photocopying machines.
Another object of the present invention is to make possible avoiding what would be overlapping at the copy-sheet conveyance entry point in the circulating conveyance path of the copy sheet that was fed first and on which reverse-side copying was carried out, and a copy sheet fed later. This might occur when in the midst of sequentially feeding a circulatable sheet count quantity of copy paper a non-feed jam arises, in a continuous dual-sided copying cycle for a circulatable sheet count quantity of copy paper.
Yet another object of the present invention by a stackless continuous dual-sided copying method in photocopying machines, aims for curtailed processing time for continuous dual-sided copying.
By one aspect of the present invention, a stackless continuous dual-sided copying method in photocopying machines is characterized in including: a first step that finds as a circulatable sheet count the number of copy sheets that can stay in a circulating conveyance path when carrying out stackless continuous dual-sided copying; a second step that successively feeds only the circulatable sheet count quantity of copy sheets if the copy sheet count remaining amount is greater than the circulatable sheet count, the circulatable sheet count quantity of copy sheets being successively convey-introduced into the circulating conveyance path from a copy-sheet conveyance entry point for the circulating conveyance path; and a third step that resumes sheet-feeding operations for starting the next continuous dual-sided copying cycle upon completion of copying to first sides of the copy sheets successively convey-introduced into the circulating conveyance path in step
2
, at a predetermined timing after the last sheet of the copy sheets has completed passing the aforementioned conveyance entry point in the circulating conveyance path.
This invention enables a stackless continuous dual-sided copying method in photocopying machines that does not require the use of a plurality of copy sheet detection sensors to discriminate whether the number of copy sheets conveyed onto the circulating conveyance path has reached the circulatable sheet count.
In accordance with the present invention the stackless continuous dual-sided copying method in photocopying machines may also include a fourth step of halting sheet-feeding operations so that sheet-feeding retry operations will not be carried out when a non-feed jam has arisen in the second step, and a fifth step of resuming sheet-feeding operations at a predetermined timing after the last sheet of the copy sheets has finished passing said conveyance entry point in the circulating conveyance path, for starting a next continuous dual-sided copying cycle after image transfer to first sides of the copy sheets convey-introduced into said circulating conveyance path is completed, until in said fourth step the sheet-feeding operations are halted. There may be times when a non-feed jam has arisen in the midst of successively carrying out sheet feeding of a circulatable sheet count quantity in a continuous dual-sided copying cycle for the circulatable sheet count quantity of copy paper. This invention, however, makes possible avoiding what would be overlapping at the copy-sheet conveyance entry point in the circulating conveyance path of the copy sheet that was fed first and on which reverse-side copying was carried out, and a copy sheet fed later.
The first step can also include, for example, computing copy speed based on copy size, copy mode, and position of a sheet-feeding section from which copy sheets are fed; and a step for determining the circulatable sheet count based on the computed copy speed. “Copy speed” herein means the copy sheet count per unit time, but copy-processing time per single copy sheet may be used for copy speed.
By another aspect of the present invention, in photocopying machines wherein during stackless continuous dual-sided copying, copy sheets are successively fed and conveyed into a copying circulation conveyance path and conveyance of fresh copy sheets into the copying circulation conveyance path is prohibited from a timing point when a forward end of a leading copy sheet conveyed into the copying circulation conveyance path reaches a first pre-established position, to when a trailing end of a final copy sheet conveyed at the timing point into the circulat
Furushige Katsuji
Kida Yasuhiko
Tabuchi Hidehiro
Mathews Alan A.
Mita Industrial Co. Ltd.
Nguyen Hung Henry
Shinjyu Intellectual Property Firm
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