Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2001-11-30
2003-07-29
Grainger, Quana M. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S113000
Reexamination Certificate
active
06600885
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus adapted to enable a sheet or the like stuck in a carrier path to be removed by opening the carrier path between a feeding unit for feeding such a sheet to an image forming unit and a discharge unit for discharging the sheet carried from the image forming unit to the outside.
Digital technology has recently found its fields of application in copying machines, and attempts are being made to improve image quality through the use of laser recording. The digital copying machines are now capable of producing an image output from data transmitted from devices other than a scanner unit in a copying machine, such as a personal computer and a facsimile machine, connected through an interface.
A need arises here to produce image outputs in the same order as the associated image data inputs are received from another device or apparatus. “Face-down” types are currently popular; those types discharge sheet sequentially from the discharge unit so that the side of the sheet on which an image is formed looks down.
The face-down type is equipped with a carrier path through which, sheet is fed sheet by sheet from a feeding unit, such as a sheet feeding unit, situated below an image forming unit and also sheet, after an image is formed thereon, is discharged face-down from a discharge unit situated above the image forming unit. Along the carrier path extending upright between the feeding unit and the discharge unit are there provided a pair of carrier rollers, transfer device, peeler device, fixing device, and other devices, which overall complicates the structure of the apparatus. Miniaturization of the image forming apparatus is another trend recently being pursued; if moving sheet gets stuck in the carrier path as a result of a problem in the image forming apparatus, removing the stuck sheet is a troublesome task.
Japanese Patent Publication No. 8-18724 discloses an image forming apparatus having a main body which is separable into two parts with respect to the carrier path extending upright between the feeding unit and the discharge unit, one of the parts being a static body including an image forming unit, the other part being a movable body which, near the bottom thereof, is engaged rotatably to the static body via a supporting axis and which can thereby swing with respect to the static body, wherein if moving sheet gets stuck in the carrier path, the carrier path can be opened by swinging the movable body around the supporting axis, allowing the sheet to be removed from the carrier path.
In the conventional image forming apparatus, the movable body in the main body is engaged rotatably with the static body, and the movable body is swung around the supporting axis. The structure allows the carrier path to be wide open on the side opposite to the swing center, but not on the side of the swing center. Therefore, it is difficult to remove sheet stuck near the entrance of the carrier path (near the feeding unit).
Further, the entire movable body swings around the supporting axis, tracing an arc; therefore the transfer device, the carrier rollers, and other components which forms the carrier path in the movable body move tracing a curve, rather than a straight line. This makes it difficult to accurately position the aforementioned components of the carrier path mounted to the movable body and the image forming unit and the components of the carrier path, such as the carrier rollers and the fixing device, mounted to the static body. The movable body swings especially violently on the side far from the swing center, in other words, the exit of the carrier path, tracing a large arc, and requires high accuracy in relative positioning with respect to the static body. If accurate positioning of the components of the carrier path fails, problems are likely to develop with moving sheet in the carrier path.
Besides, when the movable body is swung around the supporting axis, the movable body experiences a relatively large impact. Possible impact could be taken care of, by providing strength compensation to the supporting axis and associated parts and impact alleviation by means of a hydraulic dumper or another mechanism. However, this will add to the total weight of the image forming apparatus and result in increased load in swinging the movable body, which undesirably degrades operability of the movable body.
To make the entrance of the carrier path (a part near the feeding unit) wide open, the supporting axis and the static body need be separated by a relatively great distance. This however adds to the size of the image forming apparatus and requires increased room for installation including free space to swing the movable body. It therefore becomes difficult to install the apparatus in limited space. If the movable body is provided with a switchback carrier path and a cover body which can swing so as to open the switchback carrier path, the movable body is swung first, and the cover body needs be also swung with respect to the already swung movable body, which adds to difficulty to the removing of sheet.
BRIEF SUMMARY OF THE INVENTION
An object of the invention is to provide an image forming apparatus having a carrier path which can be wide open along the entire length thereof without adding to the size owing to such a configuration that enables a movable body in a main body to slide and optionally a sub-carrier path, being connected to the carrier path at the midpoint thereof, which can be wide open together with the carrier path.
Another object of the invention is to provide an image forming apparatus that can maintain good positional relationship among components forming a carrier path between a static body and a movable body in a main body and also that can position, relative to the image forming unit, an auxiliary device, such as a transfer device, mounted to the movable body with increased accuracy when the movable body is slid closed, owing to a configuration in which the static body or the movable body has a guide member for guiding the slide movement of the movable body.
A further object of the invention is to provide an image forming apparatus which satisfactorily prevents a sheet stuck in the carrier path from falling when the carrier path is opened, owing to a configuration in which either the static body or the movable body has a pair of carrier rollers carrying the sheet.
Yet another object of the invention is to provide an image forming apparatus that can position the auxiliary device, such as the transfer device, relatively to the image forming unit with increased accuracy when the movable body is slid closed, owing to a configuration in which the auxiliary device is provided swingingly to the movable body.
An image forming apparatus in accordance with a first aspect includes: an image forming unit for forming an image on a sheet; a feeding unit for feeding the sheet toward the image forming unit; a discharge unit for discharging the sheet carried from the image forming unit to the outside thereof, and a main body separable into a static body and a movable body along a carrier path extending from the feeding unit to the discharge unit, the static body being provided with the image forming unit, and is adapted so that the movable body is slidable with respect to the static body.
According to the first aspect, the carrier path extending from the feeding unit to the discharge unit can be wide open along the entire length thereof by sliding open the movable body; therefore, sheet stuck in the carrier path, especially, in winding and other parts where sheet is likely to get stuck, can be readily spotted and easily removed. The image forming apparatus thus delivers good operability in sheet removal. The movable body slides and experiences a relatively small impact when slid open; therefore, the movable body no longer needs a complicated supporting mechanism. The image forming apparatus weighs less and requires less installation space.
An image forming apparatus in accordance with a second aspect is such t
Grainger Quana M.
Renner Otto Boisselle & Sklar
Sharp Kabushiki Kaisha
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