Electrophotography – Document handling – Copy
Reexamination Certificate
2001-01-22
2002-10-22
Brase, Sandra (Department: 2852)
Electrophotography
Document handling
Copy
C399S401000, C399S402000
Reexamination Certificate
active
06470169
ABSTRACT:
CROSS-REFERENCE TO RELATED DOCUMENTS
This document claims benefit of priority under 35 U.S.C. §119 to Japanese Patent Application Nos. 2000-012297, 2000-230153, 2000-398225, and 2000-396638, respectively filed in the Japanese Patent Office, on Jan. 20, Jul. 31, Dec. 27, and Dec. 27, 2000, the entire contents of each of which are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus, such as a printer, copying machine, facsimile device, etc., provided with a paper turning-over section in the paper conveying path extended from the paper feeding section to the image forming section, and in particular, an image forming apparatus provided with an image forming section of the electrophotographic type or digital electrophotographic type capable of conveying recording paper with high speed, or an image forming apparatus having a function of paper binding.
The present invention further relates to an image forming apparatus having a function of accommodating the recording paper from the front tip end thereof in a temporary paper accommodating section, switching back the recording paper such that the rear tip end of the recording paper becomes the front tip end thereof, and conveying the recording paper thus switched back to the printer engine.
The present invention further relates to an image forming apparatus capable of sufficiently shortening the distance between the preceding recording paper and the recording paper just subsequent thereto, in particular, at the time of the both-surfaces printing, or otherwise capable of at least partially superposing the preceding recording paper and the just subsequent recording paper on each other in the temporary paper accommodating section.
The present invention further relates to a printer, copying machine, facsimile device set, and complex machine, all provided with the above-mentioned image forming apparatus.
2. Discussion of the Background
Regarding such the sorts of technology, the inventions described in the published specifications of Japanese Laid-open Patent Publication Nos. 5-289453 and 8-259045 are well known.
Among those Japanese Laid-open Patents, the former Laid-open Patent (5-289453) discloses the sheet feeding section of an image forming apparatus capable of shortening the positional distance between the recording papers having the image formed thereon by the image forming section by conveying the recording paper with an increased conveying speed during a constant time period. If the paper distance is intended to be shortened with the increased conveying speed, when the paper conveying path from the paper feeding section to the position where the conveying speed starts to be increased is long, all of the recording papers existing in the conveying path have to be conveyed with the same increased conveying speed. For this reason, the control of changing the paper conveying speed inevitably becomes large-scaled, and that results in the occurrence of troublesome matters to be solved, such as the increase of cost, the increase of noise, etc., on some occasions. In such a situation, the background-art technology has enabled to successively convey the recording paper fed with a constant conveying speed/paper distance in the past, with the necessary paper conveying speed and with the very shortened paper distance, without transiently accelerating the recording paper to be conveyed by use of the method of shortening the paper distance utilizing the switch-back path.
Furthermore, the published specification of Japanese Laid-open Patent Publication No. 8-259045 discloses a paper re-feeding apparatus in an image forming apparatus, that is, a both-surfaces copying apparatus capable of turning over the recording paper having the image formed on the one-side surface thereof and re-feeding the recording paper thus turned over, in which two sheets of paper can be conveyed at the same time on the switch-back path in the paper turning-over device. The same specification further discloses the registration operation at the time of sending out the recording paper.
However, according to the above background art, since the advancing and sending-out operations are performed with three rollers successively brought into contact with each other so as to equalize the conveying speeds before and behind the recording paper turning-over apparatus, the paper distance cannot be largely shortened. Furthermore, the position where the registration operation is performed is largely shifted from the image forming device. Therefore, the image position is probably shifted therefrom due to the conveyance error occurring during the time period of conveying the recording paper on the path. For this reason, the functional effect is limited only to skewing function compensating.
Otherwise, as the related technology, the sheet-state material (e.g. paper) turning-over apparatus and the image as disclosed in the published specification of Japanese Laid-open Patent Publication No. 8-20106 and the sheet turning-over apparatus as disclosed in the published specification of Japanese Laid-open Patent Publication No. 5-97305 are well known. However, in both of them, the driving roller provided on the switch-back path can be parted therefrom and the advancing and sending-out operations for the recording paper can be performed at the same time in the both-surfaces copying machine same as that of the background art as disclosed in the aforementioned Japanese Laid-open Patent Publication No. 8-259045.
Here, the image forming apparatus provided with a paper turning-over device on the paper conveying path extending from the paper feeding stage to the image forming apparatus as proposed by the present inventor, et al. is described hereinafter.
FIG. 12
illustrates an example of an electrophotographic-type image forming device and an image forming apparatus provided with a paper turning-over device. In
FIG. 12
, the recording papers piled and accommodated in a paper feeding device
1
are separated and fed sheet by sheet from the uppermost position thereof. The recording paper thus separated and fed advances to the switch-back path by the action of the first conveying device
11
and the third conveying device
13
constructing the switch-back path. After stopping temporarily, the third conveying device
13
and the second conveying device
12
practice the registration operation. Thereafter, the recording paper is fed to the image forming device
2
. After forming and fixing the image on the recording paper, the recording paper having the image formed thereon is discharged to the paper discharging device
6
.
FIGS. 13 through 15
illustrate the registration operation at the time of forming the image on the recording paper in the image forming apparatus as shown in FIG.
12
. As is apparent from the illustration of
FIGS. 13-15
, the leading tip end of the recording paper sent out from the switch-back path is detected by a registration sensor
15
, and the sending-out operation of the third conveying device
13
is continued until a predetermined time period elapses. Thereafter, the operation of the third conveying device
13
is stopped. In such a state, the leading tip end of the recording paper impinges on the second conveying device
12
in a state of a little bending as shown in FIG.
14
. By creating such a state, the leading tip end of the recording paper is caused to go forward along the nip portion of the second conveying device
12
, and in such a state, the improvement of the accuracy in the skew compensation and the paper sending-out timing can be realized. The above operation is called “a registration operation”.
Here, among the advancing path for the recording paper and the other path of sending out the recording paper, the commonly-used paper conveying path is called “a switch-back path
13
a
”, and the position where the recording paper is stopped by the switch-back device is called “a turning-over stop position” (B position described later). During the time period of practic
Brase Sandra
Ricoh & Company, Ltd.
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