Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
1998-12-11
2001-04-17
Grainger, Quana M. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S113000
Reexamination Certificate
active
06219507
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an image information processing apparatus such as a copier, printer, facsimile machine, scanner and the like as well as relating to a sheet feeder usable in an image information processing apparatus and having a function of feeding sheets, one by one, from a stack of sheets.
(2) Description of the Related Art
Concerning image information processing apparatuses including: a copier which scans the image of an original and produces a printed output of the scanned image information; a printer which produces a printed output of transferred image information; a facsimile machine which transmits the image information obtained by scanning the image of an original; and a scanner which scans the image of an original to obtain its image information and the like, wasted interior space is attempted to be reduced as much as possible to make the image information processor compact. However, when miniaturizing, simply reducing the space is not effective enough, it is necessary to develop the miniaturization whilst securing necessary space, without any deterioration of the functions and operativities as much as possible.
For example, in order to enable maintenance, checks, adjustment, repair etc. of an image processing apparatus, Japanese Utility Model Laid-Open Application Sho 58 No. 126,460 discloses an image processing apparatus in which its functional units can be detachably attached from two adjoining sides thereof. In this prior art, when the detachable photosensitive member unit is attached or detached from the top of the image processing apparatus, the functional unit, located below the photosensitive member inside the image processing apparatus and having functional parts, are shifted to the side of the image processing apparatus while the developing unit is pulled out of the top, so as to create an open space around the photosensitive member for its attachment and detachment. Thus, the photosensitive member is attached or detached.
Concerning this technology, in order to improve the easiness of the attachment and detachment by reducing the number of working steps upon attachment and detachment, it is possible to configure an arrangement in which the photosensitive member can be attached and detached from the top of the image processing apparatus without shifting the functional unit, including the functional part located below the photosensitive member, to the side of the image processing apparatus. Illustratively, the functional parts, including the photosensitive member, located above the photosensitive member are integrated into a single functional unit so that the unit can be attached or detached from the top of the image processing apparatus. In such an image processing apparatus, it is necessary to develop miniaturization without compromising the attachment and detachment performance.
However, in the case where the image processing apparatus having detachable functional blocks, disclosed in Japanese Utility Model Laid-Open Application Sho 58 No. 126,460 is miniaturized, in order to effect the function in the functional unit, the parts inevitably residing at their predetermined positions are kept as they are while parts other than the above-mentioned parts are configured to be moved. Further, in order to avoid interference of one functional unit with an adjacent one during attachment and detachment thereof, each functional unit is configured so as not to have any projection which would be an obstacle to the attaching or detaching movement of an adjacent functional unit and hence the functional unit is preferably configured so that the width of the space required for attachment and detachment may be substantially uniform. Therefore, the overall shape of functional units tends to be a rectangular prism. However, if the functional units are limited to this shape, they produce wasted space. In this way, it was not possible to reduce the volume of the space occupied by the functional units, and hence it was not promoted to miniaturize of the image processing apparatus. This problem becomes marked for the functional units having functions relating to the sheets, such as an exposure scanner unit, sheet feeding unit, image forming unit, fixing unit and the like.
For miniaturization of the image information processing apparatus, the following two points are of importance:
(1) To miniaturize individual parts; and
(2) To eliminate the wasted space within the image information processing apparatus as much as possible. However, the first point ‘miniaturization of individual parts’ can be attained only to a limited extent, limited by the fact that each part should present the specified functionality expected by the design requirements.
For the purpose of explanation, a feed roller in a sheet feeding device having the function of separating and feeding sheets, one by one, from a stack of sheets will be a typical example. The sheet feeding performance of a feed roller varies widely depending upon the size of the sheets (length, width and thickness), the characteristics of sheets (friction coefficient with respect to the feed roller and the stiffness) or the environment under which sheets are handled by the feeder. Therefore, in order to expect a stable sheet feeding performance for handling a variety of sheet types under various environment conditions, the feed roller needs certain minimum dimensions. For example, to prevent skew during feeding, the feed roller needs to abut the sheet with a predetermined nipping length or greater, which means that the feed roller needs to be longer than a predetermined length. To separate sheets, one by one, the feed roller needs to abut the sheet with a predetermined nipping width or greater, which means that the diameter and the rubber thickness of the feed roller need to be greater than predetermined values.
Concerning the sheet stopper means of a sheet feeder for preventing the stack of sheets from reaching the feed roller, this device needs to move and retract from the sheet blocking position when a sheet needs to be delivered. Therefore, the movable distance of the stopper is determined by the height of the stack of sheets to be allowed. As for some examples of the functional parts disposed in the image forming units, such as the photosensitive member, the developing roller in the developing unit, the cleaning blade, the charger, the transfer device, etc., the sizes of these elements are determined by the maximum size of sheets to be handled since image forming needs to be done for the sheets of the acceptable maximum size.
In this way, not only the functional parts directly acting on the sheets, such as the feed roller, photosensitive member, charger, transfer device etc., but also the functional parts indirectly acting on the sheets, such as the developing roller, cleaning blade etc., will be determined as to their dimensions by the size of the sheets to be handled. Further, similar to the sheet stopper means, there are functional parts having a predetermined movable range. But the movable range is also determined depending on the sheets. Accordingly, these functional parts relating to the sheets, because they relate to sheets, may be modified as to their dimensions and their positional relationship relative to the sheets, to some permissible extent depending upon their relationship with the sheets, but still cannot be said to have a large flexibility in their design.
On the other hand, parts other than the functional parts relating to the sheets, such as, the drive transmitting parts for transmitting driving force to the functional parts relating to the sheets, support parts and casings for accommodating functional parts relating to the sheets, drive sources, parts for electrical connections and the like, are rather flexible in design with regard to miniaturization and their layout, compared to the functional parts relating to the sheets.
Next, the second point, ‘elimination of the wasted space within the image information processing apparatus as much as possible’
Inoue Tatsuya
Nagao Hiroyuki
Sugita Shinji
Yamamoto Hiranaga
Yoneda Yoshiharu
Grainger Quana M.
Renner , Otto, Boisselle & Sklar, LLP
Sharp Kabushiki Kaisha
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