Electrophotography – Document handling – Copy
Reexamination Certificate
2000-03-14
2002-08-06
Beatty, Robert (Department: 2852)
Electrophotography
Document handling
Copy
C399S407000
Reexamination Certificate
active
06430388
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an image forming machine such as laser printer, facsimile, or electrostatic copier. More specifically, the invention relates to an image forming machine which can form images on both surfaces of a sheet, and by which the sheet having an image or images formed on one or both of its surfaces can be discharged after posttreatment of the sheet, such as punching, stapling, or sorting.
DESCRIPTION OF THE PRIOR ART
In an image forming machine, such as an electrostatic copier (hereinafter referred to as a copier), there may be need to not only discharge a sheet having an image formed thereon (a copied sheet) onto a copy receiving tray, but also perform sheet posttreatment, such as punching, stapling, or sorting. In this case, a finisher (a sheet post-treating device) is produced independently of the copier, and is provided detachably on a lateral side part of the copier.
In a copier, the height of a sheet discharge port differs generally depending on the entire size of the copier. When the copier is equipped with a finisher, it has been common practice to produce a specific finisher, which has a sheet send-in port with a height corresponding to the sheet discharge port of a copier of a specific size (type), and provide the copier of the specific size with the specific finisher.
There has been known a finisher, which is to be provided on a copier, and which has a punching means installed at an upstream position of a sheet send-in path, the punching means designed for punching as sheet posttreatment. With this type of finisher, a sheet having an image formed thereon is once stopped when it passes through the punching means. At the time of its stoppage, punching is performed for an end portion of the sheet. More concretely, the punching means has a sheet stopper. The sheet stopper is disposed so as to be selectively brought by a drive means, such as cam, to a retreat position at which the sheet stopper retreats from a sheet send-in path, and permits transport of the sheet sent in, and a stop position at which the sheet stopper protrudes into the sheet send-in path to block the sheet send-in path, and contacts one end of the sheet sent in, i.e., its downstream end in a transport direction of the sheet, to stop the movement of the sheet temporarily, thereby putting the sheet to a predetermined punched position. When the sheet stopper is located at the stop position with a predetermined timing with respect to the sending-in of the sheet, the sheet sent in is stopped at the punched position. Then, a punch of the punching means is reciprocated in a face-and-back direction of the sheet to carry out punching at a predetermined position of an end portion of the sheet, the downstream end portion of the sheet. The sheet punched at its one end portion is sent in, in a state turned upside down, onto a sheet receiving stand provided at the finisher. A pile of the punched sheets thus stored on the sheet receiving stand is discharged onto a discharge tray for sorting.
The above-described finisher having the punching means may be provided in a copier capable of forming images on both surfaces of a sheet. An example of this type of copier has an image forming transport path in which an image is formed on one surface of the sheet being transported, a reversing transport path in which a transport direction of the sheet selectively introduced from a downstream portion of the image forming transport path is reversed, a returning path in which the sheet reversely transported from the reversing transport path is returned below the image forming transport path with the directions of the face and back of the sheet being unchanged, and an inverting transport path in which the sheet returned through the returning path is turned upside down and readmitted into an upstream portion of the image forming transport path. The downstream end of the image forming transport path is connected to the sheet send-in path of the finisher provided on the copier. When the sheet having images formed on both surfaces thereof in the copier is to be punched, the sheet is sent in from the downstream end of the image forming transport path to the sheet send-in path of the finisher, and has its end portion is punched in the aforementioned manner.
As described above, the finisher provided on the copier is produced to be adapted for a specific copier. When it is installed actually, adjustment of its height is an essential task. Particularly in an unfavorable environment for installation, such as a place of installation with a slope or irregularities, this height adjusting work involves considerable labor and burden, thus taking a long time for installation. If, after installation of the finisher, a deviation in height occurs between the finisher and the copier, or a deviation arises in the gap between them, because of unexpected factors, transport of the sheet from the copier to the finisher may fail to be performed stably. In case the sheet is not stably transported, a jam may take place, or a defective product may occur. Since the finisher is installed at a side portion of the copier, moreover, a lateral surplus space for installation is needed. Furthermore, in dealing with the jam, it is necessary to separate the finisher from the copier laterally. Thus, the above lateral space will have to be expanded further.
In a copier capable of image formation on both surfaces of a sheet and provided with a finisher having punching means, when punching is to be performed in an end portion of a sheet having an image formed only on one surface thereof during its transport through an image forming transport path of the copier, the sheet is fed into the finisher from a downstream end of the image forming transport path. The end portion of the sheet sent into the finisher is brought into contact with the sheet stopper of the punching means located at the stop position, and stopped at the punched position. Then, punching is carried out at a predetermined position of the end portion of the sheet. When punching is to be performed in an end, portion of a sheet having images formed on both surfaces thereof, the sheet having an image formed on one surface thereof during its transport through the image forming transport path of the copier passes through the reversing transport path and the returning path. Then, the sheet is turned upside down in the inverting transport path, and readmitted into an upstream portion of the image forming transport path. During its re-transport through the image forming transport path, an image is formed on the other surface of the sheet. The sheet having images formed on both surfaces thereof is sent into the finisher from a downstream end of the image forming transport path, and punching is performed at a predetermined position of an end portion of the sheet by the punching means in the manner stated earlier.
As clear from the foregoing description, the distance of transport during which the sheet has images formed on both surfaces thereof in the copier, then enters the finisher, and contacts the sheet stopper of the punching means is about twice or more as long as the distance of transport during which the sheet has an image formed on only one surface thereof, then enters the finisher, and contacts the sheet stopper of the punching means. Furthermore, transport of the sheet in double-sided image formation involves the inverting action of the sheet. As the sheet transport distance increases, there is a high possibility that displacement of the sheet in a horizontal direction perpendicular to the direction of transport (hereinafter referred to as “transport width direction”) will increase during transport of the sheet. If the inverting action is involved during transport of the sheet, this possibility will be increased further. Consequently, the sheet having images formed on both surfaces thereof is transported over such a long distance of transport with its inverting motion being involved, and is brought into contact with the sheet stopper of the punching means in the finisher,
Hashimoto Yukio
Hirai Yasuyuki
Kusumoto Hiroshi
Yamamoto Kiyonori
Beatty Robert
Kyocera Mita Corporation
Smith , Gambrell & Russell, LLP
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