Sheet-material associating – Associating or disassociating – Sheet associating
Reexamination Certificate
1999-02-17
2002-03-05
Skaggs, H. Grant (Department: 3651)
Sheet-material associating
Associating or disassociating
Sheet associating
C270S058270, C270S059000, C271S188000, C271S198000, C271S314000
Reexamination Certificate
active
06352253
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a discharged sheet stacking apparatus in which imaged sheets are book-bound by a book-binding means such as a stapler and are discharged and stacked, and an image forming apparatus having such a stacking apparatus.
More particularly, the present invention relates to a discharged sheet stacking apparatus in which, sheets are temporarily stopped for both-face imaging treatment and stapling treatment, the sheets are discharged, and an image forming apparatus such as a printer, a copying machine and the like, having such a stacking apparatus.
2. Related Background Art
As discharged sheet stacking apparatus for a laser beam printer (image forming apparatus) having a book-binding apparatus such as a stapler, a stacking apparatus which is connected to a side of the printer body including a discharge opening and in which imaged sheets are stapled for each job and are discharged and stacked is well known. However, since such a discharged sheet stacking apparatus has a discharged sheet switch-back mechanism for permitting the imaged sheets to be stapled and stacked in a page sequence, an installation area is increased and, since a sheet-to-sheet distance is increased to ensure the switch-back of the sheet, through-put of print is worsened.
To avoid such inconveniences, there has been proposed a discharged sheet stacking apparatus in which sheets are conveyed in a reverse manner and are stacked on an upper surface of a printer to omit a reversing mechanism. However, in order to stack a large number of sheets in such a discharged sheet stacking apparatus, strength of the printer body for supporting the sheets must be increased, thereby increasing the cost of the printer body.
To avoid such inconvenience, there has been proposed a discharged sheet stacking apparatus of so-called “lower-installed” type in which a discharged sheet stacking portion is disposed below a printer body, and a flapper (branching means) for feeding sheets to a sheet discharge apparatus arranged below the printer body is provided in a sheet discharge path of the printer body and a convey portion for conveying the sheet downwardly from the flapper to the sheet discharge apparatus is provided out of the printer body, and an actuator for actuating the flapper of the printer body is provided in the convey portion, thereby avoiding such inconvenience.
However, in order to effect the book-binding by using the book-binding means such as the stapler, a plurality of sheets must be aligned with each other for each job. Generally, in a conventional aligning means, a sheet aligning portion is inclined with respect to a horizontal plane by about 10° to 30° so that the sheets are aligned with each other by abutting the sheets against a vertical wall portion provided at an inclined end by utilizing the inclination of the sheet aligning portion.
When the aligning means having the inclined surface is used at the sheet stacking portion in this way, a height of the discharged sheet stacking apparatus becomes great, so that, when the discharged sheet stacking apparatus is installed below the printer as mentioned above, the entire height of the printer is increased. As a result, it will be difficult for the user to handle the uppermost printer.
Further, a sheet bundle stapling mechanism used with the conventional discharged sheet stacking apparatus is designed so that a stapling mechanism portion is shifted along a sheet bundle comprised of sheets aligned with each other on a sheet stacking tray (sheet stacking portion) to staple any position(s) of the sheet bundle. That is to say, in the sheet bundle stapling mechanism provided in the image forming apparatus, after a predetermined number of sheets on which toner images were recorded in an image forming portion are conveyed onto the sheet stacking tray and are aligned there, the stapling mechanism portion is shifted to the predetermined position at the end portion of the aligned sheet bundle on the sheet stacking tray to effect the stapling operation.
However, in the above-mentioned conventional sheet bundle stapling mechanism, the stapling mechanism portion must be shifted by distances corresponding to various sizes of various sheets in order to staple any position on the end portion of the sheet bundle.
Thus, the sheet bundle stapling mechanism becomes complicated, and, since the stapling mechanism portion is shifted, the possibility of occurrence of malfunction will be increased. Further, since a space through which the stapling mechanism portion is shifted must be reserved, it is difficult to make the apparatus compact.
Accordingly, it is difficult to manufacture the conventional sheet bundle stapling mechanism with cheap cost, and a greater installation area for the image forming apparatus having the discharged sheet stacking apparatus is required.
Further, in some sheet bundle stapling mechanisms of the conventional discharged sheet stacking apparatus, the stapling treatment is effected by temporarily stopping or waiting the sheet in the sheet convey path.
The sheet conveyed through a vertical convey portion is received in the discharged sheet stacking apparatus by a pair of align and convey-in rollers and is guided onto an align table (sheet stacking portion). The sheets abut against a tip end stopper portion of a sheet stopper to be stacked on the align table.
When a predetermined number of sheets are stacked on the align table as a sheet bundle, the sheets are aligned with each other in a feeding direction and in a direction perpendicular to the feeding direction and then are pinched by a pair of bundle convey rollers (sheet convey rollers). When the convey path is released by rotating the tip end stopper portion in a retard direction, the sheets are conveyed and discharged from the discharged sheet stacking apparatus in the form of the sheet bundle.
In the above-mentioned discharged sheet stacking apparatus, in order to make the apparatus itself simpler and to achieve reduction of cost, a lower bundle convey roller among the pair of bundle convey rollers does not include a drive connection/disconnection means such as a clutch.
Thus, the lower bundle convey roller continues to rotate while supporting (from the below) the sheets urged against the tip end stopper portion. Further, the lower bundle convey roller is positioned substantially flush with an upper surface of the align table to bundle-convey the sheets.
In this way, since the lower bundle convey roller continues to rotate at the position substantially flush with the upper surface of the align table, the roller continues to rub a lowermost sheet in the sheet bundle urged against the tip end stopper portion.
Therefore, the conventional discharged sheet stacking apparatuses have the disadvantages that the surface of the sheet is damaged and the image formed on each sheet is distorted to damage the image.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a discharged sheet stacking apparatus and an image forming apparatus, in which the above-mentioned conventional drawbacks can be eliminated and which have a small height.
To achieve the above object, according to the present invention, there is provided a discharged sheet stacking apparatus characterized in that a sheet feed-in means for pinching and feeding-in a sheet onto a sheet stacking portion on which a plurality of sheets are stacked and for causing a tip end of the sheet to abut against a sheet stopper retractable with respect to the sheet stacking portion is disposed at a position spaced apart from the sheet stopper by a distance smaller than a length of the sheet, and the sheet feed-in means continues the feed-in operation while pinching a tail end of the sheet even after the tip end of the sheet abuts against the sheet stopper so that after a loop is formed in the tail end the sheet is stacked onto the sheet stacking portion.
The discharged sheet stacking apparatus may include a sheet auxiliary convey means for conveying the sheet on the sheet feed-in me
Hayakawa Yasuyoshi
Komatsu Teruo
Ogata Atsushi
Waragai Tsuyoshi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Skaggs H. Grant
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