Process cartridge

A process cartridge detachably mountable to an image forming apparatus for forming an image on a recording material includes a first unit including at least an image-bearing member, a second unit including at least a developing device for developing an electrostatic image formed on the image-bearing member, and a connector for separably connecting the first unit and the second unit with each other, which permits integral mounting and demounting of the first and second units relative to the image forming apparatus. The second unit has a life which substantially equals to the life of the image forming apparatus, and the first unit is replaceable by separation thereof from the second unit outside the image forming apparatus.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to a process cartridge which is detachably mountable to an image forming apparatus, such as a copying machine, a printer, a facsimile apparatus, etc., for forming an image by utilizing an electrophotographic process or an electrostatic recording process.

FIG. 6is a schematic sectional view (front view) of an embodiment of a conventional image forming apparatus and illustrates an entire structure of an image forming apparatus500which is a so-called digital copying machine.

Referring toFIG. 6, the image forming apparatus500of this embodiment includes an original read portion510provided with an automatic document feeder disposed at an upper portion of the apparatus500, an image forming portion520disposed substantially at a central portion of the apparatus500, and a (paper) feeding portion530disposed at a lower and a right-side portion of the image forming portion520.

The image forming portion520includes, for example, an integral-type process cartridge526including integrally a photosensitive drum521which is an electrophotographic photosensitive member, a charging roller522for charge-treating the surface of the photosensitive drum521, a developing device523for visualizing an electrostatic image on the photosensitive drum521, a toner containing means524which contains a toner to be supplied to the developing device523, and a cleaning device525for removing and recovering residual toner image remaining on the photosensitive drum521; an exposure apparatus (laser scanner unit)527disposed above the process cartridge526; a transfer roller528, disposed opposite to the photosensitive drum521, for transferring a toner image formed on the photosensitive drum521onto a sheet S; a fixing device541for effecting heat fixation treatment to the sheet S onto which the toner image has been transferred; and a pair of discharge rollers542, which is integrally constituted with the fixing device541for discharging the fixation-treated sheet S outside the image forming apparatus500.

In the feeding portion530; a (paper) feeding cassette531capable of accommodating sheets S having A4 size or a size smaller than A4 size; a feeding roller532for feeding the sheets S toward the image forming portion520; and an intermediary plate533for lifting up the sheets S so that a leading end of the sheet S abuts the feeding roller532; are disposed. The sheet S fed by the feeding roller532is once stopped by a pair of register rollers535through a conveyance roller534and is fed after it is timed to the toner image formed on the photosensitive drum521. In some cases, the sheet S it fed from a manual feed portion536disposed on a right-side to the register roller pair535.

In the original read portion510an original supporting platen glass512, a contact image sensor513, a supporting shaft514for supporting the contact image sensor513, and a reader motor515for driving the contact image sensor513are disposed. An original is placed on the original supporting platen glass512and is subjected to scanning with the contact image sensor513, whereby image reflected light is converted into an electric signal.

When the photosensitive drum521surface which has been uniformly charged by a charge roller522is subjected to exposure to an image light L, issued from a laser (beam) scanner unit527, converted from the electric signal which has been converted from the original image reflected light at the original read portion510, an electrostatic image is formed on the photosensitive drum521. After the electrostatic image is developed as a toner image (visualized image) by the developing device523together with the rotation of the photosensitive drum521, the toner image is transferred onto a sheet S, which is timed to the toner image by the register roller pair535, fed from the feeding portion530by a transfer roller528. Incidentally, the surface of the photosensitive drum521after completion of the transfer is cleaned by the cleaning device525to prepare a subsequent image formation process. The sheet S after the transfer is completed is subjected to heat fixation at the time when the toner image on the sheet S passes through the fixing device541, and after being fixed, is discharged outside the image forming apparatus510by the discharge roller pair542.

FIG. 7illustrates a method of mounting and demounting the integral-type process cartridge526from the image forming apparatus500.

In the image forming apparatus500, it is necessary for a user of the image forming apparatus to perform demounting and mounting of the integral-type process cartridge526at the time of replacement of the process cartridge526or post-treatment for paper jamming at the image forming portion520. The demounting and mounting of the process cartridge526is performed in such a manner that the original read portion510is moved horizontally in a left-hand direction as shown inFIG. 7, and from an opening portion503which has appeared substantially above the image forming portion520, the integral-type process cartridge526may be detached from and attached to a main assembly511of the image forming apparatus500in a direction of an indicated arrow. More specifically, the user of the image forming apparatus demounts and mounts the integral-type process cartridge526along a cartridge guide portion504while holding a gripping portion526a. Incidentally, an explanation on a mechanism and structure for performing the horizontal movement of the original read portion510will be omitted.

As described above, the image forming process by the conventional image forming apparatus500is performed.

However, in the conventional image forming apparatus500, the life of the integral-type process cartridge526is determined by the volume of the toner contained in the toner containing portion524. When the toner is used up, as shown inFIG. 7, it is necessary to replace the integral-type process cartridge526with a new one by taking the process cartridge526out of the image forming apparatus500.

In this case, the entire integral-type process cartridge526which includes parts the lives of which do not expire is subjected to replacement. Accordingly, still usable parts for the process cartridge526are to be replaced since the process cartridge526is replaced as the process cartridge unit.

Further, the integral-type process cartridge is ordinarily recovered and its recycling mechanism is also created. However, from the viewpoint of environmental protection which has recently received attention, the number of parts as consumable replacement parts may preferably be as small as possible in the first place.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a process cartridge capable of improving usability features, such as handleability and (paper) jam treating performance, by disposing it detachably mountable to an image forming apparatus in such a state that a first unit and a second unit are connected with each other.

Another object of the present invention is to provide a process cartridge capable of cutting removing costs by reducing the number of consumable replacement parts while taking environmental protection into consideration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the process cartridge according to the present invention will be described based onFIGS. 1-4.

FIG. 1shows the entire structure of an image forming apparatus (copying machine) according to this embodiment;FIG. 2shows a state of a process cartridge as an image forming unit for the image forming apparatus at the time of mounting and demounting;FIGS. 3(a)-3(d) are enlarged views of the process cartridge for illustrating a separating method of the process cartridge; andFIG. 4is a supplementary explanation view showing a toner container.

An image forming apparatus100according to this embodiment has the same structure as the above-mentioned conventional image forming apparatus500except for a process cartridge127. Parts or members of the image forming apparatus100identical to those of the conventional image forming apparatus500are indicated by the same reference numerals and explanation thereon is omitted.

<Entire Structure of the Apparatus>

The entire structure of the image forming apparatus100will be explained with reference toFIG. 1with particular emphasis on its modifications.

As shown inFIG. 1, the image forming apparatus100of this embodiment is constituted by an original read portion510disposed at an upper portion of the apparatus100, an image forming portion120disposed at almost central portion, and a (paper) feeding portion530disposed below and on the right side of the image forming portion120. As described above, the original read portion510and the feeding portion530are identical to those in the conventional image forming apparatus500, so that the structure of the image forming portion120will be described below.

To the image forming portion120, a process cartridge127is mounted. As shown inFIG. 1, the process cartridge is mounted to the image forming portion120in such a state that a drum cartridge128and a developing cartridge129, which are mutually separable cartridges for a photosensitive member, are connected to each other.

The drum cartridge128as a first unit includes a photosensitive drum121being an electrophotographic photosensitive member as an image bearing member, a charge roller122for charging the surface of the photosensitive drum121, a cleaning device125for removing and recovering residual toner image remaining on the photosensitive drum121surface, etc. These members are integrally formed in a unit which is detachably mountable to the image forming apparatus100.

The developing cartridge129as a second unit includes a developing roller123for visualizing an electrostatic latent image on the photosensitive drum121, a toner containing portion124for accommodating a toner container151containing a toner supplied to the developing roller123, a plurality of stirring members126for stirring the toner send from the toner container151, etc. These members are integrally formed in a unit which is detachably mountable to the image forming apparatus100.

A method of separating and connecting the drum cartridge128and the developing cartridge129will be described hereinafter.

Incidentally, within the toner container151of the process cartridge127shown inFIG. 1, a feeding lade152is provided for feeding the toner toward the developing roller123.

FIG. 2shows a state at the time when the process cartridge127is detached from and attached to the image forming apparatus100. Also in the image forming apparatus100, a user of the image forming apparatus100is required to perform demounting and mounting of the process cartridge127at the time of replacement of consumable parts within the process cartridge127or jam treatment of sheet(s) as a recording material at the image forming portion120. The demounting and mounting of the process cartridge127is performed in such a manner that the original read portion110is moved horizontally in a left-hand direction as shown inFIG. 2, and from an opening portion103which has appeared substantially above the image forming portion120, the integral-type process cartridge127may be detached from and attached to a main assembly of the image forming apparatus100in a direction of an indicated arrow. More specifically, the user of the image forming apparatus demounts and mounts the integral-type process cartridge127along a cartridge guide portion504while holding a fold-down gripping portion127a.

As described above, the process cartridge127is detached and attached in a substantially vertical direction (a direction perpendicular to a rotational axis direction of the photosensitive drum121), so that it is not necessary to ensure a large space for mounting the process cartridge127.

Incidentally, the gripping portion127ais formed of a wire member and is in a fold-down state when the process cartridge127is mounted in the image forming portion120.

In the process cartridge127for the image forming apparatus100according to the present invention, the photosensitive drum121deteriorates by wearing of its photosensitive layer with the use thereof for a predetermined time. For this reason, the drum cartridge128is designed as a consumable replacement part so that the user of the image forming apparatus100replaces the drum cartridge128, a predetermined number of times in total, every time when the life of the drum cartridge128expires in successive use of the image forming apparatus100. Incidentally, with respect to the timing of replacement, the image forming apparatus100is designed so that it displays a message of, e.g., “please replace the cartridge” at a liquid crystal display portion thereof to encourage the user to replace the drum cartridge when a thickness of the photosensitive layer is not more than a certain threshold value by detecting a current passing through the photosensitive drum121at the time of applying a predetermined voltage to the charge roller122disposed in contact with the photosensitive drum121to simulate detection of the photosensitive layer thickness every predetermined time.

Herein, the “life” means a maximum sheet number or a maximum period of image formation capable of satisfying and retaining a predetermined criterion as to qualities of an image formed on the sheet as the recording material by the image forming apparatus100.

In this embodiment, the lives of the main assembly of the image forming apparatus100and the developing cartridge129are respectively about 10×104 sheets (A4-size, printing ratio of about 6%) as the number of image formation sheets or 5 years as the period of use, and the life of the drum cartridge128is about 1.9×104 sheets (A4-size, printing ratio of about 6%) as the number of image formation sheets.

As described above, the developing cartridge129has the life which is substantially the same as that of the image forming apparatus100. In other words, it is not necessary for the process cartridge127of this embodiment to be replaced until the life of the image forming apparatus100expires, except for the toner container151containing the toner which is consumed with the image formation. The toner container151is designed to be replaceable with a new toner container by pulling out it from the developing cartridge129when the toner runs out.

The above-mentioned predetermined criterion is a criterion which is established by a manufacturer of the image forming apparatus so that qualities of an image formed on the sheet give user satisfaction.

More specifically, the substantially agreement between the lives of the main assembly of the image forming apparatus and the developing cartridge means that the replacement of the developing cartridge is not performed once until the image forming apparatus reaches its end of life. Thus, it is possible to reduce the running costs by obviating the need for replacement of the developing device. In addition, it is possible to increase usability for an operator by the reduction of replacement parts.

<Separation and Connection Between Drum Cartridge and Developing Cartridge>

FIGS. 3(a) to3(d) show a sequence of separation procedure of the process cartridge127in the case of replacing the drum cartridge128.

The drum cartridge128and the developing cartridge129are connected to each other so that they are engaged with each other by engaging an engaging protrusion163(connection means) of the developing cartridge129with an engaging portion164(connection means) of the drum cartridge128and also that the developing roller123and the photosensitive drum121(shown inFIG. 1) are disposed opposite to each other with a predetermined spacing through, e.g., a spacer. Further, the connection state is ensured by locking a release lever161disposed on the drum cartridge side of the process cartridge.

The replacement procedure of the drum cartridge128of the process cartridge127at the time when it reaches end of its life will be describe step by step.

FIG. 3(a) shows a state in which the process cartridge127is taken out of the image forming apparatus100, and the drum cartridge128and the developing cartridge129are still connected to each other.

In this state, it is possible to perform the above-mentioned (paper) jam treatment. More specifically, a space corresponding to a volume of the process cartridge is obtained within the image forming apparatus, so that it is possible to expose a conveyance path of a recording material at a transfer portion for transferring a toner image from the photosensitive member (drum) to the recording material. As a result, the operator can readily remove the jammed recording material.

In the state ofFIG. 3(a), the release lever161is in the engagement position. The release lever161engages with the engaging protrusion163(FIG. 3(d)) of the developing cartridge129while resisting a compression spring162disposed on the developing cartridge side of the process cartridge.

Incidentally, the release lever161is disposed on the rear side and the far side in a direction perpendicular to the drawing sheet. In the state ofFIG. 3(a), the process cartridge127can be handled similarly as in the case of the above-mentioned integral-type process cartridge516.

FIG. 3(b) shows a first step for separating the drum cartridge128and the developing cartridge129from each other. When the release lever161is rotationally moved in a direction of an arrow indicated in the figure, an engaging hook161aprovided to the release lever161is moved apart from the engaging protrusion163.

FIG. 3(c) shows a state wherein the release lever161is moved up to its maximum released position. In this state, the drum cartridge128and the developing cartridge129are separably joined to each other.

FIG. 3(d) shows a state wherein the drum cartridge128is being separated from the developing cartridge129. Referring toFIG. 3(d), the drum cartridge lighter than the developing cartridge129is moved in a direction of an indicated arrow relative to the developing cartridge129which is in a mounted state, whereby the engaging portion164of the drum cartridge128is disengaged from the engaging protrusion163of the developing cartridge129.

As described above, the separation procedure of the drum and developing cartridges128and129is performed.

In order to connect again between the drum cartridge128and the developing cartridge129, the above-described separation procedure is performed in reverse order after the engaging protrusion163is engaged into the engaging portion164to connect the developing cartridge129to the drum cartridge128. By doing so, it is possible to replace only the drum cartridge128which has reached end of its life.

FIG. 4shows the toner container151containing the toner. A predetermined amount (about 200 g in this embodiment) of the toner is accommodated in the toner container151, which is incorporated in a toner container accommodating portion124disposed on the developing cartridge side of the process cartridge by insertion.

Next, a method of first mounting the toner container151to the process cartridge127will be described.

The mounting of the toner container151may be performed in accordance with the following five steps (1)-(5).

(1) The process cartridge127is taken out of the image forming apparatus100.

(2) The toner container151is inserted toward the toner container accommodating portion124in a direction of an arrow m shown inFIG. 4.

(3) A sealing member153, which seals a toner supply port151a(indicated by dashed lines in the figure), is pulled in a direction, of an arrow indicated in the sealing member153, which is opposite from the arrow m direction, thus being removed from the toner container151.

(4) A fold-down grip which is disposed to be foldable toward the side surface of the toner container151by rotating about its shaft, is raised and rotated in a direction of an arrow n shown inFIG. 4by a predetermined angle (about 110 degrees in this embodiment) while being held by the operator.FIG. 4shows a state in which the fold-down grip154is folded (after the toner container151is mounted into the toner container accommodating portion124).

As a result of the rotation of the grip154, the toner is placed in a state wherein it can be supplied from the toner supply port151ato a toner receiving port of the developing cartridge129. Further, at the time of image formation, the electrostatic image on the photosensitive drum can be developed with the supplied toner by the developing cartridge129.

(5) The process cartridge127to which the toner container151is mounted is mounted into the image forming apparatus100.

The removal (demounting) of the toner container151may be performed in accordance with the following two steps (1) and (2).

(1) After the process cartridge127is taken out of the image forming apparatus100, the fold-down grip154is raised and held, followed by rotation in a direction opposite from the arrow n direction shown inFIG. 4.

(2) While holding the fold-down grip154, the toner container151is pulled out in a direction opposite from the arrow m direction. Thereafter, a new toner container is inserted into the process cartridge in the above-described manner.

<Handling of Process Cartridge>

The handling method of the process cartridge127of this embodiment will be described.

The process cartridge127is generally detached from and attached to the image forming apparatus100by the user (operation) of the image forming apparatus100at the times of post-treatment of paper jam at the image forming portion120, of replacement in the case where the drum cartridge128reaches end of life, and of replacement of the toner container151in the case where the toner is consumed and runs out. At such times, as described above, the handling performance of the process cartridge127when it is demounted and mounted can be well retained similarly as in the case of the integral-type process cartridge, so that handling of the process cartridge127of this embodiment can be performed with no feeling of incongruity even by the user who is practiced in handling of the integral-type process cartridge.

On the other hand, in the case where the drum cartridge128that has reached end of its life is replaced, the process cartridge127is first taken out of the image forming apparatus100and then the drum cartridge128and the developing cartridge129are separated from each other as described above. Thereafter, a new drum cartridge128is connected to the developing cartridge129to construct the process cartridge127, which is then mounted in the image forming apparatus100.

Further, in the case where the toner contained in the toner container151runs out, the process cartridge127is taken out of the image forming apparatus100and the toner container151is removed from the toner container accommodating portion124. Then, a new toner container151is mounted in the toner container accommodating portion124, and the resultant process cartridge127is mounted in the image forming apparatus100.

As described above, according to this embodiment, it is possible to appropriately perform the replacement of consumable parts, such as the drum cartridge128and the toner container151only at the time when their lives expire, thus eliminating the need for replacement of the developing cartridge129which has the substantially same life as the image forming apparatus100.

In the process cartridge127and the image forming apparatus100according to this embodiment, the handling of the process cartridge regarding its demounting from and mounting in the image forming apparatus is substantially equivalent to that of the integral-type process cartridge and the consumable replacement parts occurring with the use of the image forming apparatus can be minimized. As a result, it becomes possible to not only reduce the running costs but also to provide an advantageous structure in terms of environmental protection which is the subject of attention recently.

As described above, it becomes possible to provide a process cartridge and an image forming apparatus which allow good workability at the time of demounting and mounting of the process cartridge and accomplish the reduction of the consumable replacement parts.

Another Embodiment

Then, another embodiment of the present invention will be described based onFIG. 5. Incidentally, the basic structure of an image forming apparatus200is similar to that described in the above-mentioned embodiment. Accordingly, parts or members indicated by the same reference numerals are omitted from the following explanation.

FIG. 5is a perspective explanatory view showing the entire outward appearance of the image forming apparatus200.

In the image forming apparatus200, an original read portion210is fixed to an image forming portion120, so that demounting and mounting of the process cartridge127cannot be performed by horizontally moving the original read portion510as shown inFIG. 2.

For this reason, in the image forming apparatus200of this embodiment, the operation of demounting and mounting the process cartridge127is performed in such a manner that a front cover261is opened by rotationally moving it in a direction of an arrow a indicated inFIG. 5to expose the image forming portion120. InFIG. 5, the case of mounting the process cartridge127is shown. The process cartridge127is mounted in the image forming apparatus200by inserting it toward the image forming portion120in a direction of an arrow b (parallel to a rotational axis direction of the photosensitive drum121).

As described above, the image forming apparatus200(of this embodiment) and the image forming apparatus100(of the above-mentioned Embodiment 1) are only different in the direction of demounting and mounting of the process cartridge127, thus achieving the same effects in terms of handling of the process cartridge127at the time of demounting and mounting, and in terms of a reduction of running costs and environmental protection.

Further, according to this embodiment, the demounting and mounting of the process cartridge127can be performed from the front side of the image forming apparatus200, so that it is possible to readily demount and mount the process cartridge127even when space is tight above the image forming apparatus200.

As described hereinabove, according to the respective embodiments of the present invention, it is possible to realize a reduction in running costs and to realize environmental protection by designing the image forming apparatus so as to achieve a good handleability at the time, when the process cartridge is demounted and mounted, and to allow replacement of minimum consumable parts.

More specifically, the jam treatment performance is improved by integrally taking the developing device (which is not the replacement part) together with the photosensitive member out of the image forming apparatus. In addition thereto, the photosensitive member is also designed to be replaceable, so that it is possible to compatibly realize the improvement in usability and the reduction in running costs.