1. Field of the Invention
The present invention relates to a process cartridge and an image forming apparatus, particularly to a process cartridge for a copier, a facsimile machine, a printer and the like that use one of electronic photography and electrostatic recording methods and an image forming apparatus that uses the process cartridge.
2. Description of Related Art
Conventionally, when a drum cartridge is supplied to users as a process cartridge for a copier, a facsimile machine, a printer and the like that use one of electronic photography and electrostatic recording methods, a plastic cover member that covers the drum cartridge is attached to protect a drum portion of a new cartridge from possible damage during replacement process.
An example of the process cartridge having the cover member of the above-described type is disclosed in Related Art 1. When the process cartridge is inserted into an apparatus, an interference portion provided on a protective cover touches the apparatus and thereby stops only the protective cover so as to prevent the protective cover from being pushed inside. Cartridge insertion is complete while the protective cover protrudes from the process cartridge.
[Related Art 1] Japanese Patent Laid-open Publication Hei 9-127851
The process cartridge of Related Art 1, however, has the protective cover, made of plastic or another material, that covers an entire exposed portion of a photoconductive drum and that has a guiding portion or the like formed in one piece, which slides and fits into a cartridge frame. The process cartridge thereby occupies a space and requires manufacturing costs for the protective cover, which increases costs of the expendable process cartridge.
Further, the cartridge frame is provided with a protective cover guide that slides and fits into the guiding portion of the protective cover, thus leading to a further cost increase of the process cartridge. Furthermore, the protective cover becomes unnecessary after being inserted into the apparatus, causing an environmental protection issue.
An object of the present invention is to provide a process cartridge and an image forming apparatus, wherein the process cartridge has a low-cost and easily disposable cover member having a minimum size that protects a photoconductive drum portion and that prevents damage in replacement, while requiring no plastic cover member that covers the entire process cartridge, and wherein the image forming apparatus uses the process cartridge.
In the present invention, the process cartridge, having a photoconductive drum therein and attachable to/detachable from the image forming apparatus, is provided with a sheet-type cover member. The cover member, which protects the photoconductive drum, is attached to the cartridge until the cartridge is inserted halfway into the image forming apparatus. The cover member is then removed from the cartridge when the cartridge touches an exterior wall of the image forming apparatus as the cartridge is being inserted into the image forming apparatus.
The sheet-type cover member according to the present invention no longer requires the image forming apparatus to have a cover guide or the like that slides and fits into the cover member, thereby allowing manufacturing of the cover member at a lower cost than that of a plastic product. Further, while the process cartridge is inserted into the apparatus, the insertion operation stops, allowing a user to know a timing to remove the cover member. Furthermore, the user is able to easily remove and dispose of the cover member.
The present invention is further described in the detailed description which follows, with reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
The embodiments of the present invention are explained in the following, in reference to the above-described drawings.
Image forming unit 110Y includes photoconductive drum 111Y, charged roller 112Y, developer unit 113Y, primary transfer roller 114Y and photoconductive drum cleaner 115Y. Image forming unit 110Y forms a toner image in yellow (Y) on photoconductive drum 111Y. Developer unit 113Y is filled with a two-component developer including a toner and a carrier and is provided with developer roller 116 and mixing screw 117.
Other image forming units 110M 110C and 110K have the same structure as image forming unit 110Y; that is, charged rollers 112M, 112C and 112K are provided and developer units 113M, 113C and 113K are filled with toners in magenta (M), cyan (C) and black (K) respectively.
Laser scanning unit 120 irradiates photoconductive drums 111Y, 111M, 111C and 111K of image forming units 110Y, 110M, 110C and 110K with respective laser beams. The laser beams are separated into four colors through a polygon mirror, an f-θ lens, a reflective mirror, an imaging lens and the like, which are not shown in the figure.
Intermediate transfer unit 130 includes intermediate transfer belt 131, driving roller 132 and driven roller 133. Intermediate transfer belt 131 is rotatably mounted on driving roller 132 and driven roller 133. Driving roller 132 rotates intermediate transfer belt 131 in the direction of an arrow.
Fuser unit 140 includes fuser roller 141 and pressure roller 142, as well as an exciting coil unit and the like, which are not shown in the figure. Fuser roller 141 and pressure roller 142 revolve while pressuring each other to form a nip.
Paper feeder 150, provided at a lower part of apparatus main unit 101, includes paper cassette 151 that holds sheets of papers P. A pickup roller and a separator roller, which are not shown in the figure, separate and feed a sheet of paper one by one from a stack of papers P in paper cassette 151.
As shown in
The charged surfaces of photoconductive drums 111Y, 111M, 111C and 111K are then sequentially exposed by the laser beams from laser scanning unit 120. Thereby, electrostatic latent images in respective colors are developed on the surfaces of photoconductive drums 111Y, 111M, 111C and 111K.
The electrostatic latent images in each color formed on the surfaces of respective photoconductive drums 111Y, 111M, 111C and 111K are sequentially developed with thinly layered toners in four colors, that is, yellow, magenta, cyan and black, and formed into toner images in four colors. The toners are mixed by mixing screw 117 of respective developer unit 113Y (113M, 113C and 113K) and supplied by developer roller 116.
The toner images in four colors formed on the surfaces of respective photoconductive drums 111Y, 111M, 111C and 111K are then primarily transferred, that is, sequentially layered onto an image transfer surface (exterior circumference surface) of rotating intermediate transfer belt 131 by primary transfer roller 114Y (114M, 114C and 114K). Thereby, a full color image is formed on the image transfer surface of intermediate transfer belt 131.
The full color image primarily transferred onto intermediate transfer belt 131 is transferred at one time (secondary transfer) onto a sheet of paper P by secondary transfer roller 102. The sheet of paper P is supplied from paper feeder 150 and positioned by registration roller 152 for recording.
The full color image secondarily transferred onto the sheet of paper P is fused by a nip of fuser unit 140. Then, the sheet of paper P is ejected by paper ejecting roller 103 onto a paper ejection tray provided on an upper part of apparatus main unit 101.
Image forming units 110Y, 110M, 110C and 110K are drum cartridges (process cartridges) attachable to and detachable from apparatus main unit 101. A single unit structure of the image forming unit before attached to apparatus main unit 101 is described below in reference to
As shown in
Image forming unit 110Y is inserted from another end portion in the longitudinal direction into an opening (not shown in the figure) for image forming unit 110Y attachment provided on apparatus main unit 101. Procedures for attaching image forming unit 110Y to apparatus main unit 101 will be described later in detail in reference to
For protective cover (cover member) 200, exterior cover sheet 201 is made of a cardboard sheet; buffer sheet 202, as buffer material, is made of a foamed polyethylene sheet; and blackout sheet 203 is made of a light-shielding polyethylene sheet (e.g., colored in black) that substantially completely shuts out light. The sheets have shapes as shown in a plain view of
As
Functions of sheets 201 to 203 of protective cover 200 assembled as above are described below in reference to
As shown in
Holding portions 201b and 201c of exterior cover sheet 201 are cut at the right end portions into insertion end portion 201a. The shape is formed to prevent interference of exterior cover sheet 201 with a protrusion (not shown in the figure) on apparatus main unit 101, when the insertion end portion of image forming unit 110Y is inserted into apparatus main unit 101. When no protrusion is provided on apparatus main unit 101, holding portions 201b and 201c need not to be cut out and may be formed as a same surface of insertion end portion 201a.
When image forming unit 110Y is inserted into the opening on apparatus main unit 101 for image forming unit 110Y attachment, insertion end portion 201a of exterior cover sheet 201 having the shape described above touches the exterior wall near the opening for image forming unit 110Y attachment, thereby stopping the insertion operation of image forming unit 110Y and letting the user know the timing to remove entire protective cover 200 along with buffer sheet 202 and blackout sheet 203.
The shape of exterior cover sheet 201 allows the user to easily hold image forming unit 110Y along with holding portions 201b, 201c and 201d, when inserting image forming unit 110Y into the opening on apparatus main unit 101 for image forming unit 110Y attachment. Further, the shape allows the user to easily know the timing to remove entire protective cover 200, while inserting the insertion end portion of image forming unit 110Y into the opening on apparatus main unit 101 for image forming unit 110Y attachment.
Exterior cover sheet 201 therefore provides a holding function for replacement and a stop function during insertion, when image forming unit 110Y is attached to apparatus main unit 101.
Buffer sheet 202 is made of one sheet of foamed polyethylene that absorbs shock and easily cuts in one direction. Thus, buffer sheet 202 protects the surface of photoconductive drum 111Y from being damaged as strongly pressed by the rear side of blackout sheet 203 when the user holds both sides of image forming unit 110Y along with holding portions 201b, 201c and 201d of exterior cover sheet 201.
As shown in
Buffer sheet 202 therefore provides a protection function that guards the surface of photoconductive drum 111Y; a light-shielding function that blocks out outside light that may fall on the surface of photoconductive drum 111Y; and a function that allows easy removal of entire protective cover 200, when image forming unit 110Y is attached to apparatus main unit 101.
As shown in
Therefore, blackout sheet 203, made of one sheet of light-shielding polyethylene colored black that substantially completely shuts out light, provides a light-shielding function that substantially completely shields the exposed portion of photoconductive drum 111Y from outside light, when image forming unit 110Y is attached to apparatus main unit 101. Thereby, blackout sheet 203 is able to prevent exposure even when image forming unit 110Y is placed under outside light for a long period of time.
Described below are operation procedures for attaching image forming unit 110Y covered with protective cover 200 shown in
Prior to the operation shown in
A holding method shown in
As shown in
Since the insertion operation of image forming unit 110Y stops, the user knows the timing to remove protective cover 200. Then, as shown in an enlarged part of
Thereby, buffer sheet 202 that covers the substantially entire circumference of image forming unit 110Y can be removed from the circumference of image forming unit 110Y. Blackout sheet 203 that covers the exposed portion of photoconductive drum 111Y can also be removed. Lifting exterior cover sheet 201 in the direction of an arrow shown in the figure can easily remove entire protective cover 200 from image forming unit 110Y.
As shown in
Then, the user can dispose of protective cover 200 removed from image forming unit 110Y.
The operation procedures shown in
As described above, the protective cover that covers the image forming unit according to the embodiment is attached to the image forming unit until the insertion end portion of the image forming unit is halfway inserted into the apparatus main unit, and then the entire protective cover is removed when the exterior cover sheet touches the exterior wall of the apparatus main unit.
Therefore, when inserting the image forming unit into the apparatus main unit, the user is able to know the timing to remove the protective cover, since the insertion operation stops, and is able to remove the protective cover easily. Further, when the insertion end portions of the buffer sheet and the blackout sheet, which constitute the protective cover, are inserted into the apparatus main unit along with the image forming unit, the exterior cover sheet touches the exterior wall of the apparatus main unit, thereby preventing the user from inserting the protective cover inadvertently deeply into the apparatus main unit.
Furthermore, the sheet-type protective cover does not require the image forming unit to have a cover guide or the like that slides and fits into the protective cover, thereby reducing manufacturing costs of the protective cover, compared to a plastic product, thus reducing manufacturing costs of the image forming unit.
The protective cover according to the embodiment includes: the exterior cover sheet that provides the holding function for replacement and the stop function during insertion, when the image forming unit is attached to the apparatus main unit; the buffer sheet that provides the protection function to guard the surface of the photoconductive drum, the light-shielding function to shield the photoconductive drum surface from light, and the function to allow easy removal of the entire protective cover; and the blackout sheet that provides the light-shielding function to substantially completely shield the exposed portion of the photoconductive drum from outside light.
Thus, when the image forming unit is replaced, the photoconductive drum surface is prevented from being damaged and the exposed portion of the photoconductive drum is shielded from outside light. Therefore, the user is able to easily replace the image forming unit and remove the protective cover. Further, the protective cover is made of the cardboard sheet, the foamed polyethylene sheet and the light-shielding polyethylene sheet. Therefore, the user is able to dispose of an unwanted protective cover, which is also suitable for environmental protection.
Although the embodiment above shows the protective cover having the three layer structure, it is also possible to form a two layer structure having the exterior cover sheet and the buffer sheet. The two layer structure allows manufacturing of the protective cover at lower cost, which is also preferable to environmental protection.
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular structures, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
The present invention is not limited to the above described embodiments, and various variations and modifications may be possible without departing from the scope of the present invention.
This application is based on the Japanese Patent Application No. 2005-088056 filed on Mar. 25, 2005, entire content of which is expressly incorporated by reference herein.
Number | Date | Country | Kind |
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2005/088056 | Mar 2005 | JP | national |
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Number | Date | Country |
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9-127851 | May 1997 | JP |
Number | Date | Country | |
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20060216064 A1 | Sep 2006 | US |