DE69218423T2 - Process cartridge and imaging system with built-in process cartridge - Google Patents

Description

The present invention relates to process cartridges, image forming devices containing such cartridges, and methods for recycling such cartridges. The image forming device may, for example, be in the form of an electrophotographic copying machine, a laser printer, a facsimile machine, a word processing device or the like.

In image forming systems such as copying machines, a latent image is formed by selectively exposing a uniformly charged image-bearing member, then visualizing the latent image with toner, and then transferring the toner image to a recording sheet, thereby forming an image on the recording sheet. In such image forming systems, new toner must be refilled whenever the toner is used up. The process of refilling the toner is not only inconvenient, but also often causes the environment to become dirty. Furthermore, since the maintenance of various elements or components cannot be carried out by just a specialist, many users find this inconvenient.

In order to avoid such a disadvantage and inconvenience, an image forming system has been proposed in which parts such as a developing device whose toner has been used up or an image bearing member whose life has expired can be easily replaced, thereby facilitating maintenance by replacing the image bearing member, a charger, the developing means and a cleaning means are integrally assembled as a process cartridge which can be removably mounted in the image forming system, and such a system has been disclosed, for example, in U.S. Patent Nos. 3,985,436, 4,500,195, 4,540,268 and 4,627,701.

In such a process cartridge, the charger is constructed as a single charger unit comprising a charger wire for generating a corona discharge and a shield plate. Furthermore, the developing unit is constructed as a single developing unit comprising a developing sleeve, a developing blade, a toner supply mechanism, a toner receiving section and a developer container. Furthermore, the cleaning device is constructed as a single cleaning unit comprising a cleaning blade, a toner squeezing roller blade and a cleaning agent container.

However, the following problems occur with conventional methods:

In order to protect the environment, there has been a strong demand to collect used cartridges and reuse them (recycle them) in order to use resources effectively. If the process units are designed independently of each other, a number of different steps are required to dismantle and clean the process units in order to reuse them, which makes the recycling process more difficult.

In order to effectively recycle the process cartridges, it is also necessary to effectively disassemble and clean the process cartridges collected from the market.

For this purpose, the inventors have created the effective invention which could solve the problems described above and filed as previous applications (Japanese Patent Application No. 2-3Q1779, US Application No. 785401, EP application 91402953.3 = EP-A 0 485 271, Chinese patent application No. 91111554.4 and Korean patent No. 91- 19663).

A first aspect of the present invention relates in particular to a process cartridge to be removably mounted in a main body of an electrophotographic image forming apparatus, the cartridge comprising: a lower frame, an upper frame connected to the lower frame so as to be above the lower frame when the cartridge is mounted in the apparatus, the frames being separable from each other when the cartridge is removed from the apparatus; a rotatable electrophotographic photosensitive drum mounted on the lower frame; charging means for charging the drum; developing means mounted on the lower frame for developing a latent image on the drum; a toner container provided in the upper frame for containing toner used by the developing means; and cleaning means provided in the lower frame for cleaning the drum of the toner.

An example of such a cartridge is described in the patent documents EP-A 0 453 963 and EP-A 0 437 097. In these cartridges, the charging means is formed by a corona charger which is attached to the lower frame.

The cartridge according to the first aspect of the present invention is characterized in that the loading means comprises: a rotatable loading roller; means for mounting the loading roller on the upper frame to move it toward the drum; and means for biasing the loading roller toward the drum to move therewith.

Such a cartridge facilitates recycling, although toner adheres to the drum, the developer and the cleaning agent during operation of the cartridge, relatively little toner adheres to the charger roller. Therefore, since the charger roller is attached to the upper frame, the elements of the cartridge that require considerable cleaning are attached to one frame (the lower frame) and the elements that require less cleaning are attached to the other frame (the lower frame). Furthermore, although the charger roller and the photosensitive drum are attached to different frames, the use of a roller that is spring-loaded toward the drum can ensure that the charger roller and the drum work together properly.

Other aspects and preferred features of the present invention are set out in the claims.

A particular embodiment of the present invention will now be described by way of example with reference to the drawings in which:

Fig. 1 is a side section of a copying machine, within which a process cartridge according to a preferred embodiment of the present invention is mounted;

Fig. 2 is an axonometric view of the copying machine in a state in which a drawer is opened ;

Fig. 3 is an axonometric view of the copying machine in a state in which a drawer is closed;

Fig. 4 is a side section of the process cartridge;

Fig. 5 is an axonometric view of the process cartridge;

Fig. 6 is an axonometric view of the process cartridge in an inverted state;

Fig. 7 is an exploded sectional view of the process cartridge in a state where an upper frame and a lower frame are separated from each other;

Fig. 8 is an axonometric view of the lower frame showing its internal structure;

Fig. 9 is an axonometric view of the upper frame showing its internal structure;

Fig. 10 is a longitudinal section of a photosensitive drum of the process cartridge;

Fig. 11 is a schematic diagram for explaining the measurement of charging noise;

Fig. 12 is a diagram showing the result of measuring the loading noise concerning a position of a filler;

Fig. 13 is an axonometric view of a ground contact for the photosensitive drum;

Fig. 14 is an axonometric view of a ground contact of the photosensitive drum according to another embodiment;.

Fig. 15 is an axonometric view showing an embodiment using a non-forked ground contact in the photosensitive drum;

Fig. 16 is a section of the non-forked ground contact used in the photosensitive drum;

Fig. 17 is an elevational view showing a mounting structure for a loading roller;

Fig. 18A is an axonometric view of an exposure shutter, and Fig. 18B is a partial section of an exposure shutter;

Fig. 19 is a section showing a non-magnetic toner supply mechanism having an actuating vane;

Fig. 20 is a longitudinal sectional view showing a positional relationship between the photosensitive drum (9) and a developing sleeve (12d) and a structure for pressing the developing sleeve;

Fig. 21A is a section taken along the line A - A of Fig. 20 and

Fig. 21B is a section taken along the line B - B of Fig. 20;

Fig. 22 is a section to explain the compressive force acting on the developing sleeve;

Fig. 23 is an axonometric view of a nip roll blade in a state such that an upper edge of the blade is curved;

Fig. 24A is an axonometric view showing a state in which a double-sided adhesive tape protrudes from a lower end of the squeegee sheet, and Figs. 24B and 24C are views showing a state in which an adhesive tool is adhered to the protruding double-sided adhesive tape.

Fig. 25 is an axonometric view showing a state in which a squeegee sheet is adhered to a curved mounting surface with a lower end portion of the sheet being curved, and Fig. 25B is an axonometric view showing a state that a lower end portion of the squeegee sheet is tensioned by releasing the curvature of the mounting surface;

Fig. 26 is an axonometric view of a nip roller blade according to another embodiment, wherein a width of the blade is straight and gradually expanded from both ends to its middle portion;

Fig. 27 is an axonometric view for explaining the formation of the curvature of the nip roller blade attachment surface by the pressing of the surface;

Fig. 28 is a view showing states in which a recording medium is passed through a lower surface of the lower frame;

Fig. 29 is a section showing a state in which the photosensitive drum is finally assembled;

Fig. 30 is a section showing a state in which a developing sheet and a cleaning sheet are glued together;

Fig. 31 is an exploded view to explain the assembly of the process cartridge;

Fig. 32 is a view for explaining a position of guide members when the photosensitive drum of the process cartridge is assembled;

Fig. 33 is a section of a structure wherein the drum guides are arranged at the ends of the blade support members;

Fig. 34 is an axonometric view for explaining the support members for the photosensitive drum and the developing sleeve;

Fig. 35 is a section of the photosensitive drum and the developing sleeve with the support members attached;

Fig. 36 is an axonometric view for explaining a cover film and a tension band;

Fig. 37 is an axonometric view showing a state in which the trigger band projects from a handle;

Fig. 38 is a schematic view showing a state in which a process cartridge is gripped by a hand of an operator;

Fig. 39A is a flow chart showing the assembling and delivery line for the process cartridge and Fig. 39B is a flow chart showing the disassembling and cleaning line for the process cartridge;

Fig. 40 is an axonometric view showing a state in which the process cartridge is fixed within the image forming system;

Fig. 41 is an axonometric view showing a state in which the process cartridge of Fig. 24 is mounted within the image forming system;

Fig. 42 is an axonometric view showing the arrangement of three contacts provided on the image forming system;

Fig. 43 is a section showing the structure of the three contacts;

Fig. 44 is a section for explaining the positioning of the relative position between the lower frame and a lens unit;

Fig. 45 is a section for explaining the positioning of the relative position between the lower frame and an original glass support;

Fig. 46 is an axonometric view showing the fixing positions of the positioning pins;

Fig. 47 is a schematic elevational view showing the relationship between the rotary shafts of the drum and the sleeves and shaft support members for them, and a transmission direction of a driving force from a driving gear to a flange gear of the photosensitive drum;

Fig. 48 is an axonometric exploded view of a development sleeve, according to a variant of the design, in which it can slide easily,

Fig. 49 is a schematic elevation of the developing sleeve of Fig. 48;

Fig. 50 is a sectional elevation showing a state in which the upper frame and the lower frame are released;

Fig. 51 is a view showing gears and contacts attached to the photosensitive drum;

Fig. 52A is an elevational view of a developing sleeve receiving member according to another embodiment, and Fig. 52B is an end view of a receiving member of Fig. 52A;

Fig. 53 is an elevational view showing an arrangement in which the developing sheet and the cleaning sheet inside are attached to the interior of the image forming system by means of pins;

Fig. 54 is an elevational view showing a state in which the photosensitive drum is finally assembled, according to a further embodiment;

Fig. 55 is a side section of bearing members for supporting the photosensitive drum and the developing sleeve, according to a further embodiment;

Fig. 56 is a schematic view of a transmission mechanism for transmitting a driving force from a drive motor of the image forming system to various elements;

Figs. 57 and 58 are axonometric views showing a state in which the flange wheel of the photosensitive drum and a wheel integral with the flange wheel project from the lower frame;

Fig. 59 is a view showing a transmission chain for transmitting a driving force from the drive gear of the image forming system to the photosensitive drum and the transfer roller; and

Figs. 60A and 60B are views showing different force transmission mechanisms for the developing sleeves where magnetic toner is used and where non-magnetic toner is used.

First, a process cartridge according to a first embodiment of the present invention and an image forming system using such a process cartridge will be explained with reference to the accompanying drawings.

The entire structure of a process cartridge and an image forming system to mount the process cartridge in it:

First, the entire construction of the image forming system will be briefly described. Fig. 1 is a side section of a copying machine as an example of the image forming system, within which the process cartridge is mounted, Fig. 2 is an axonometric view of the copying machine with an opened tray, Fig. 3 is an axonometric view of the copying machine with the closed tray, Fig. 4 is a side section of the process cartridge, Fig. 5 is an axonometric view of the process cartridge and Fig. 6 is an axonometric view of the process cartridge in an inverted state.

As shown in Fig. 1, the image forming system A operates to optically read image information on an original or document 2 by an original reading means 1. A recording medium placed on a sheet feed tray 3 or manually fed from the sheet feed tray 3 by a conveying means 5 to an image forming station of the process cartridge B where a developer (hereinafter referred to as "toner") image is formed in response to the image information is transported to the recording medium 4 by a transferring means 6. Thereafter, the recording medium 4 is sent to a fixing means 7 where the transferred toner image is permanently fixed to the recording medium 4. Then, the recording medium is ejected to an ejecting basket 8.

The process cartridge B defining the image forming station operates to uniformly charge a surface of a rotating photosensitive drum (image bearing member) 9 by a charging means 10 and then to form a latent image on the photosensitive drum 9 by projecting a light image read by the reading means 1 onto the photosensitive drum by an exposure means 11 and then to visualize the latent image as a toner image by a developing means 12. After the toner image is transferred to the recording medium 4 by the transfer means 6, the remaining toner remaining on the photosensitive drum 9 is removed by a cleaning means 13.

The process cartridge B is designed as a cartridge unit in that it accommodates the photosensitive drum 9 and the like within frames which comprise a first or upper frame 14 and a second or lower frame 15. Furthermore, in the embodiment shown, the frames 14, 15 are made of a high impact styrene resin (HIPS) and a thickness of the upper frame 14 is about 2 mm and a thickness of the lower frame 15 is about 2.5 mm. However, the material and thickness of the frames are not limited to the above values, but they can be appropriately selected.

Next, various parts of the image forming system A and the process cartridge B mountable in the image forming system will be fully described.

Image Education System

First, different parts of the image formation system will be explained.

(Original Reading Resources)

The original reading means 1 serves to optically read the information written on the original, and, as shown in Fig. 1, comprises an original glass carrier 1a which is arranged at an upper portion of a body 16 of the image forming system and on which the original 2 is to be placed. An original holding plate 1b having a sponge layer 1b1 on its inner surface is attached to the original glass carrier 1a for opening and closing movement. The original glass carrier 1a and the original holding plate 1b are mounted on the system body 16 for reciprocating sliding movement in the left and right direction in Fig. 1. On the other hand, a lens unit 1c is arranged below the original glass carrier 1a at the upper portion of the system body 16, and it includes a light source 1c1 and a short focal length focusing lens assembly 1c2 inside.

In this arrangement, when the original 2 is placed on the original glass carrier la with its image surface facing downwards, and when the light source 1c1 is activated and the original glass carrier la slides in the left-right direction in Fig. 1, the photosensitive Drum 9 of the process cartridge B is exposed by the reflected light from the original 2 via the lens arrangement 1c2.

(Recording medium funding)

The conveying means 5 serves to convey the recording medium 4 placed on the sheet feed basket 3 to the image forming station and to convey the recording medium to the fixing means 7. Specifically, after a plurality of recording mediums 4 are stacked on the sheet feed tray 3, or after a single recording medium 4 is manually inserted into the sheet feed tray 3, and the leading end(s) of the recording medium or media abuts against a gap between a sheet feed roller 5a and a friction pad 5b pressed against the roller, then, when a copy start button A3 is depressed, the sheet feed roller 5a is rotated to separate the recording medium 4 and feed it to a pair of register rollers 5c1, 5c2, which in turn feed the recording medium in accordance with the image forming process. After the image forming process, the recording medium 4 is conveyed to the fixing means 7 by a conveying belt 5d and a guide member 5e, and then it is ejected onto the ejection basket 8 by a pair of ejection rollers 5f1, 5f2.

(Transmission medium):

The transfer means 6 serves to transfer the toner image formed on the photosensitive drum 9 to the recording medium 4 and comprises, in the embodiment shown in Fig. 1, a transfer roller 6. In particular, by pressing the recording medium 4 against the photosensitive drum 9 in the process cartridge B mounted in the image forming system by means of the transfer roller 6 provided in the image forming system and by applying to the transfer roller 6 a voltage having the polarity opposite to that of the toner image, the is formed on the photosensitive drum 9, the toner image on the photosensitive drum 9 is transferred to the recording medium 4.

(Fixing agent)

The fixing means 7 is for the toner image transferred to the recording medium 4 by applying the tension to the transfer roller 6, and, as shown in Fig. 1, it comprises a heat-resistant fixing film 7e wound around and extending between a drive roller 7a, a heating body 7c held by a holder 7b, and a tension plate 7d. The tension plate 7b is biased by a torsion spring 7f to apply a tensile force to the film 7e. A pressing roller 79 is pressed against the heating body 7c with the film 7e therebetween so that the fixing film 7e is pressed against the heating body 7c with a predetermined force necessary for the fixing process.

The heating body 7c is made of a heat-resistant material such as alumina, and has a heat-generating surface composed of wire-shaped or plate-shaped members having a width of about 160 µm and a length (from the extension perpendicular to the plane of Fig. 1) of about 216 mm, made of, for example, Ta₂N, and arranged on a lower surface of the holder 7b made of insulating material or composite material comprising insulation and a protective layer made of, for example, Ta₂O, covering the heat-generating surface. The lower surface of the heating body 7c is flat, and the front and rear ends of the heating body are rounded to allow sliding movement of the fixing film 7e. The fixing film 7e is made of heat-treated polyester, and has a thickness of about 9 µm. The film can be rotated in the clockwise direction by rotating the drive roller 7a. When the Recording medium 4 onto which the toner image has been transferred passes between the fixing film 7e and the pressure roller 79, then the toner image is fixed onto the recording medium 4 by heat and pressure.

In order to thereby exhaust or dissipate the heat generated by the fixing agent 7 from the image forming system, a cooling fan 17 is provided within the body 16 of the image forming system. The cooling fan 17 is rotated, for example, when the copy start button A3 (Fig. 2) is depressed to generate air currents a (Fig. 1) flowing into the image forming system from the recording medium supply inlet and flowing out from the recording medium ejection outlet. The various parts, including the process cartridge B, are cooled by the air current so that the heat does not remain in the image forming system.

(Recording media feed and ejection baskets)

As shown in Figs. 1 to 3, the sheet supply basket 3 and the discharge basket 8 are mounted on axes 3a, 8a, respectively within the system body 16 for pivotal movement in the directions b in Fig. 2, and for pivotal movement about the axes 3b, 8b in the directions c in Fig. 2. Locking projections 3c, 8c are formed on the free ends of the baskets 3, 8 at both sides thereof, respectively. These projections can be inserted into locking recesses 1b2 formed in an upper surface of the original hold-down plate 1b. Therefore, as shown in Fig. 3, when the baskets 3, 8 are folded inward to insert the locking projections 3c, 8c into the corresponding recesses 1b2, the original glass carrier 1a and the original hold-down plate 1b are prevented from sliding in the left and right directions. As a result, an operator can easily lift and transport the image forming system A via handles 16a.

(Adjustment buttons for density etc.)

Similarly, adjustment buttons for adjusting density and the like are provided on the image forming system A. Briefly, a main switch A1 is provided in Fig. 2 to turn the image forming system on and off. A density adjustment selector A2 is used to adjust the basic density (of the copied image) of the image forming system. The copy start button A3, when depressed, starts the copying operation of the image forming system. A copy cancel button A4, when depressed, interrupts the copying operation and cancels the various setting states (for example, the set density state). A copy number counter button A5 is used to adjust the number of copies when depressed. An automatic density adjustment button A6, when pressed, automatically adjusts the density during copying. A density adjustment dial A7 is provided so that the operator can adjust the copy density by rotating this dial as needed.

Process cartridge

Next, various parts of the process cartridge B, which can be mounted within the image forming system A, can be explained.

The process cartridge B comprises an image bearing member and at least one processing means. The processing means may, for example, comprise a charging means for charging a surface of the image bearing member, a developing means for forming a toner image on the image bearing member, and/or a cleaning means for removing the residual toner remaining on the image bearing member. As shown in Figs. 1 and 4 in the illustrated embodiment, the process cartridge B is designed as a cartridge unit which can be removably mounted within the body 16 of the image forming system by comprising the charging means 10, the developing means 12 which deposits the toner (developer) and the cleaning means 13 which are arranged around the photosensitive drum 9 as the image bearing member by a casing including the upper and lower frames 14, 15. The charging means 10, the developing means 11 (opening 11a) and the toner container 12a of the developing means 12 are arranged within the upper frame 14, and the photosensitive drum 9, the developing sleeve 12d of the developing means 12 and the cleaning means 13 are arranged within the lower frame 15.

Now, the various parts of the process cartridge B will be fully explained, namely, the charging means 10, the exposing means 11, the developing means 12 and the cleaning means 13, in that order. In this case, Fig. 7 is a sectional view of the process cartridge with the upper and lower frames separated from each other, Fig. 8 is an axonometric view showing the internal structure of the lower frame, and Fig. 9 is an axonometric view showing the internal structure of the upper frame.

(Photosensitive drum)

In the illustrated embodiment, the photosensitive drum 9 comprises a cylindrical drum core 9a having a thickness of about 1 mm and made of aluminum, and an organic photosensitive layer 9b disposed on an outer peripheral surface of the drum core so that an outer diameter of the photosensitive drum 9 becomes 24 mm. The photosensitive drum 9 is rotated in a direction indicated by the arrow in response to the image forming operation by transmitting a driving force of a driving motor 54 (Fig. 56) of the image forming system to a flange gear 9c (Fig. 8) fixed to one end of the photosensitive drum 9.

During the image forming process, when the photosensitive drum 9 is rotated, the surface the photosensitive drum 9 is uniformly charged by applying to the charging roller 10 (in contact with the drum 9) a fluctuating voltage obtained by superimposing a direct current voltage on an alternating current voltage. In this case, in order to uniformly charge the surface of the photosensitive drum 9, the frequency of the alternating current voltage applied to the charging roller 10 must be increased. However, if the frequency exceeds about 2000 Hz, the photosensitive drum 9 and the charging roller 10 are caused to vibrate, thereby generating the so-called "charging noise".

It is to be noted that when the AC voltage is applied to the charger roller 10, an electrostatic attractive force is generated between the photosensitive drum 9 and the charger roller 10, so that the attractive force becomes maximum at the maximum and minimum values of the AC voltage, whereby the charger roller 10 is attracted to the photosensitive drum 9 while the charger roller 10 is elastically deformed. On the other hand, at an intermediate value of the AC voltage, the attractive force becomes minimum, with the result that the elastic deformation of the charger roller 10 is canceled in an attempt to separate the charger roller 10 from the photosensitive drum 9. As a result, the photosensitive drum 9 and the charger roller 10 are vibrated at a frequency twice that of the applied AC voltage. Furthermore, when the charger roller 10 is attracted to the photosensitive drum 9, the rotations of the drum and the roller are braked, causing the vibration due to the slippage, which also leads to the charger noise.

In order to reduce the vibration of the photosensitive drum 9 in the embodiment shown, as shown in Fig. 10 (section of the drum), a rigid or elastic filler 9d is arranged inside the photosensitive drum 9. The filler 9d can be made of a metal such as aluminum, brass or the like, cement, ceramics such as gypsum or a rubber material such as natural rubber, taking into consideration productivity, manufacturability, effect of weight and cost. The filler 9d has a solid cylindrical shape or a hollow cylindrical shape, and has an outer diameter smaller than an inner diameter of the photosensitive drum 9 by about 100 µm, and is inserted into the drum core 9a. That is, a gap between the drum core 9a and the filler 9d is set to be 100 µm at most, and an adhesive (e.g., cyanoacrylate resin, epoxy resin, or the like) 9e is applied to the outer surface of the filler 9d or the inner surface of the drum core 9a, and the filler 9d is inserted into the drum core 9a, thereby bonding the two together.

Explained will now be the results of experiments conducted by the inventors in which the relationship between the position of the packing 9d and the sound pressure (noise level) was checked by changing the position of the packing 9d in the photosensitive drum 9. As shown in Fig. 11, the sound pressure was measured by a microphone M arranged at a distance of 30 cm from the front surface of the process cartridge B arranged in a room having a background noise of 43 dB. As a result, as shown in Fig. 12, when the packing having a weight of 80 grams was arranged at a central portion in the longitudinal direction of the photosensitive drum 9, the sound pressure was 54.5 - 54.8 dB. On the other hand, when the packing having a weight of 40 grams was arranged at a position offset from the middle position toward the flange wheel 9c by 30 mm, the sound pressure was minimal. From this result, it was found that it was more effective to arrange the packing 9d in the photosensitive drum 9 offset from the middle position toward the flange wheel 9c. The reason for this seems to be that one end of the photosensitive drum 9 is supported by the flange wheel 9c, while the other end of the drum 9 is supported by a bearing member 26 having no flange, so that the structure of the photosensitive drum 9 is not symmetrical with respect to the central position in the longitudinal direction of the drum.

Therefore, in the illustrated embodiment, as shown in Fig. 10, the filler 9d in the photosensitive drum 9 is arranged offset from the middle position c (in the longitudinal direction of the drum) to the flange wheel 9c, i.e. to the drive transmission mechanism on the photosensitive drum 9. In the illustrated embodiment, a filler 9d, which comprises a hollow aluminum member having a length L3 of 40 mm and a weight of about 20 - 60 grams, preferably 35 - 45 grams (particularly preferably about 40 grams), is arranged inside the photosensitive drum 9, which has a length L1 in the longitudinal direction of 257 mm, at a location offset from the middle position c to the flange wheel 9c by a distance L2 of 9 mm. By arranging the filler 9d inside the photosensitive drum 9, the latter can be rotated in a stable manner, thereby suppressing the vibration due to the rotation of the photosensitive drum 9 in the image forming process. Therefore, it is possible to reduce the charging noise even if the frequency of the AC voltage applied to the charging roller 10 is increased.

Furthermore, in the illustrated embodiment, as shown in Fig. 10, a ground contact 18a is in contact with the inner surface of the photosensitive drum 9, and the other end of the ground contact is in contact with a drum ground contact pin 35a, whereby the photosensitive drum 9 is electrically grounded. The ground contact 18a is arranged at the end of the photosensitive drum opposite the end in the area of the flange wheel 9c.

The ground contact 18a is made of a stainless spring steel, spring bronze phosphate or the like, and is attached to the bearing member 26. Specifically, as shown in Fig. 13, the ground contact comprises a base portion 18a1 having a locking hole 18a2 into which a projection formed on the bearing member 26 can be fitted, and two arm portions 18a3 projecting from the base portion 18a1, each arm portion being provided at its free end with a semicircular projection 18a4 projecting downward. When the bearing member 26 is attached to the photosensitive drum 9, the projections 18a4 of the ground contact 18a are pressed against the inner surface of the photosensitive drum 9 by the elastic force of the arm portions 18a3. In this case, since the ground contact 18a is in contact with the photosensitive drum 9 at multiple points (two points), the reliability of the contact is improved, and since the ground contact 18a is in contact with the photosensitive drum 9 via the semicircular projections 18a4, the contact between the ground contact and the photosensitive drum 9 is stabilized.

In this case, as shown in Fig. 14, the lengths of the arm portions 18a3 of the ground contact 18a may be differentiated from each other. In this embodiment, since the positions at which the semicircular projections 18a4 are in contact with the photosensitive drum 9 are offset from each other in the circumferential direction of the drum, even if a breakage extends in the axial direction of the inner surface of the photosensitive drum 9, both projections 18a4 do not contact this breakage at the same time, thereby maintaining the ground contact (between the contact and the drum) without failure. In this case, if the lengths of the arm portions 18a3 are differentiated, the contact pressure between one of the arm portions 18a3 and the photosensitive drum 9 is different from the contact pressure between the other arm portion and the drum. However, such a difference can be compensated for, for example, by changing the bending angles of the arm sections 18a3.

While in the illustrated embodiment, the ground contact 18a had two arm portions 18a3 as mentioned above, three or more arm portions may be provided, or if the ground contact is in contact with the inner surface of the photosensitive drum 9 without fail, then a single arm portion 18a3 (not fork-shaped) having no projection may be used as shown in Figs. 15 and 16.

Now, if the contact pressure between the ground contact 18a and the inner surface of the photosensitive drum 9 is too weak, the semicircular projections 18a4 cannot follow the unevenness of the inner surface of the photosensitive drum 9, thereby causing poor contact between the ground contact and the photosensitive drum 9 and generating noise due to vibration of the arm portions 18a3. In order to avoid such poor contact and noise, the contact pressure must be increased. However, if the contact pressure is too strong, when the image forming system is used for a long period of time, the inner surface of the photosensitive drum 9 will be damaged by the high pressure of the semicircular projections 18a4. Therefore, when the semicircular projections 18a4 pass through such a damaged portion, the vibration occurs, thereby causing poor contact and the vibration noise. In consideration of the above, it is preferable that the contact pressure between the ground contact 18a and the inner surface of the photosensitive drum be set in a range between about 10 grams and about 200 grams. It should be noted that according to the results of the experiments conducted by the inventors, when the contact pressure was less than about 10 grams, the poor contact was feared to occur with a probability, and due to the rotation of the photosensitive drum, thereby causing radio wave interference affecting other electronic devices. On the other hand, when the contact pressure was larger than about 200 grams, it was feared that the inner surface of the photosensitive drum 9 was damaged due to the sliding contact between the inner surface of the drum and the ground contact 18a over a long period of time, thereby causing the abnormal noise and/or poor contact.

At this time, although the generation of the above noise and the like cannot be completely avoided sometimes due to the condition of the inner surface of the photosensitive drum 9, it is possible to reduce the vibration of the photosensitive drum 9 by arranging the filler body 9d inside the drum 9, and it is also possible to prevent the damage of the drum and the poor contact more effectively by arranging the conductive lubricant on the contact surface between the ground contact 18a and the inner surface of the photosensitive drum 9. Furthermore, since the ground contact 18a is arranged on the bearing member 26 located away from the filler body 9d which is shifted toward the flange wheel 9c, the ground contact can be easily attached to the bearing member.

(Charging medium)

The charging means serves to charge the surface of the photosensitive drum 9. In the illustrated embodiment, the bearing member is of the so-called contact charging member type as disclosed in Japanese Patent Laid-Open Application No. 63-149669. As shown particularly in Fig. 4, the charging roller 10 is rotatably supported on the inner surface of the upper frame 14 via a sliding bearing 10c. The charging roller 10 comprises a roller shaft 10b made of metal (for example, a conductive metal core made of iron, SUS or the like), an elastic rubber layer made of EPDM, NBR or the like. made and arranged around the roller axis, and a layer of urethane rubber in which carbon is dispersed and arranged around the elastic rubber layer, or it comprises a roller axis made of metal and a foamed urethane rubber layer in which carbon is dispersed. The roller axis 10b of the charger roller 10 is held by bearing sliding guide claws 10d of the upper frame 14 via the sliding bearing 10c so that it cannot be removed from the upper frame and can be easily moved toward the photosensitive drum 9. The roller axis 10b is biased by a spring 10a so that the charger roller 10 is biased toward the surface of the photosensitive drum 9. Therefore, the charger member is constructed by the charger roller 10 received in the upper frame 14 via the bearing 10c. In the image forming process, when the charger roller 10 is driven by the rotation of the photosensitive drum 9, the surface of the photosensitive drum 9 is uniformly charged by applying the superimposed DC and AC voltage to the charger roller 10 as mentioned above.

Now, the voltage applied to the charger roller 10 will be described. Although the voltage applied to the charger roller 10 may be a DC voltage alone, in order to achieve the uniform charge, the threshold voltage obtained by superimposing the DC voltage and the AC voltage as mentioned above should be applied to the charger roller. Preferably, the threshold voltage obtained by superimposing the DC voltage has a peak-to-peak voltage value which is larger, namely, two times larger or more than the charger start voltage when the DC voltage alone is used, and the AC voltage is applied to the charger roller 10 to improve the uniform charge (see Japanese Patent Laid-Open Publication, Application No. 63-149669). The "threshold voltage" described therein means a voltage whose value periodically changes as a function of time. and having a peak-to-peak voltage which is preferably larger, namely two times or more, than the charger start voltage when the surface of the photosensitive drum is charged by only the DC voltage. Further, the waveform of the threshold voltage is not limited to the sine wave, but may be a rectangular wave, a triangular wave or a pulse wave. However, the sine wave does not include the higher harmonic components and is preferable in view of reducing the charging noise. The DC voltage may include a voltage having a rectangular waveform obtained by, for example, turning a DC power source ON/OFF.

As shown in Fig. 17, the application of the tension to the charger roller 10 is achieved by pressing one end 18c1 of a charger bias contact 10c against a charger bias contact pin of the image forming system as will be described later, and the other end 18c2 of the charger bias contact 18c is pushed against the metal roller shaft 10b, thereby applying the tension to the charger roller 10. At this time, since the charger roller 10 is biased to the right in Fig. 17 by the elastic contact 18c, the charger roller bearing 10c, which is remote from the contact 18c, has a hook-shaped stopper portion 10c1. Further, a stopper portion 10e suspended from the upper frame 14 is disposed near the contact 18c to prevent excessive axial movement of the loader roller 10 when the process cartridge B is dropped or vibrated.

In the embodiment shown, with the arrangement as described above, the voltage of 1.6 - 2.4 KVVpp, - 600 VVDC (sine wave) is applied to the charger roller 10.

When the loader roller 10 is accommodated in the upper frame 14, first the bearing 10c is held by the guide claws 10d of the upper frame 14, and then the roller shaft 10b of the loader roller 10 is inserted into the bearing 10c. Further, when the upper frame 14 is assembled with the lower frame 15, the loader roller 10 is pressed against the photosensitive roller 9 as shown in Fig. 4.

Here, the bearing 10c for the charger roller 10 is made of the conductive bearing material having a large amount of carbon filler, and the tension is applied to the charger roller 10 from the charging bias contact 18c via the metal spring 10a, so that a stable charging bias can be applied.

(Exposure medium)

The exposure means 11 serves to expose the surface of the photosensitive drum 9, which is uniformly charged by the charger roller 10, with a light image from the reading means 1. As shown in Figs. 1 and 4, the upper frame 14 is provided with an opening 11a through which the light from the lens assembly 1c2 of the image forming system can be projected onto the photosensitive drum 9. At this time, when the process cartridge B is removed from the image forming system A, if the photosensitive drum 9 is exposed to the ambient light through the opening 11a, there is a fear that the photosensitive drum will be damaged. To prevent this, a shutter member 11b is attached to the opening 11a so that when the process cartridge B is removed from the image forming system A, the opening 11a is closed by the shutter member 11b and when the process cartridge is installed in the image forming system, the shutter member opens the opening 11a.

As shown in Figs. 18A and 18B, the shutter member 11b has an L-shaped cross section having a convex portion directed toward the outside of the cartridge, and is pivotally mounted on the upper frame 14 via pins 11b1. A torsion coil spring 11c is mounted around one of the pins 11b1 so that the Shutter member 11b is biased toward the coil spring 11c to close the opening 11a in a state where the process cartridge B is dismounted from the image forming system A.

As shown in Fig. 18A, stopper portions 11b2 are formed on the outer surface of the shutter member 11b, so that when the process cartridge B is mounted within the image forming system A and an upper opening/closing cover 19 (Fig. 1) to be opened with respect to the body 16 of the image forming system is closed, a projection 19a formed on the cover 19 abuts against the stopper portions 11b2, thereby rotating the shutter member 11b in a direction shown by the arrow e (Fig. 18B) to open the opening 11a.

In the operation of opening and closing the shutter member 11b, since the shutter member 11b has the L-shaped cross section, and since the stopper portions 11b2 are arranged outside the periphery of the cartridge B and in the vicinity of the pivot pins 11b1 as shown in Figs. 4 and 18B, the shutter member 18b abuts against the projection 19a of the cover 19 outside the periphery of the process cartridge B. As a result, even when the opening and closing angle of the shutter member 11b is small, a leading end of the rotary shutter member 11b is surely opened, whereby the light from the lens array 1c2 arranged above the shutter member on the photosensitive drum is surely exposed to form the latent image on the surface of the photosensitive drum 9. By constructing the shutter member 11b as described above, when the process cartridge B is installed in the image forming system, it is not necessary to delay the cartridge B relative to the shutter opening projection 19a of the cover 19 of the image forming system, with the result that it is possible to reduce the stroke of the projection, thereby making the process cartridge B and the image forming system A small.

(Development funds)

Next, the developing agent 12 will be explained. The developing agent 12 serves to visualize the electrostatic latent image formed on the photosensitive drum 9 as a toner image by the developing agent with toner. Although magnetic toner or non-magnetic toner may be used in this image forming system A, the developing agent in the process cartridge B comprises the magnetic toner as a one-component magnetic developer.

The binder resin of the one-component magnetic toner used in the developing process may be the following or a mixture of the following polymer of styrene and its substituents such as polystyrene and polyvinyltoluene, styrene copolymer such as styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid-ethyl copolymer or styrene-acrylic acid-butyl copolymer; Polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyacrylic acid, resin, modified resin, turpentine resin, phenol resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petrol resin, paraffin wax, carnauba wax or the like.

As for the coloring material added to the magnetic toner, carbon black, copper, phthalocyanine, iron black or the like is known. The fine magnetic particles contained in the magnetic toner may be made of a material which is magnetizable when placed in a magnetic field, such as ferromagnetic powder of a metal such as iron, cobalt and nickel, powder of a metal alloy or powder of a compound such as magnetite or ferrite.

As shown in Fig. 4, the developing agent 12 for forming the toner image with the magnetic toner, a toner container 12a for containing the toner and a toner supply mechanism 12b disposed inside the toner container 12a and adapted to convey the toner. Further, the developing means is arranged such that the developing sleeve 12d having a magnet 12c inside thereof is rotated to form a thin toner layer on a surface of the developing sleeve. When the toner layer is formed on the developing sleeve 12b, the developable frictional charging charges are applied to the electrostatic latent image on the photosensitive drum 9 by the friction between the toner and the developing sleeve 12d. Further, to regulate a thickness of the toner layer, a developing blade 12e is pressed against the surface of the developing sleeve 12d. The developing sleeve 12b is arranged opposite to the surface of the photosensitive drum 9, with a gap of about 100 - 400 µm therebetween.

As shown in Fig. 4, the magnetic toner conveying mechanism 12b has conveying members 12b1 made of polypropylene (PP), acrylbutadiene styrene (ABS), high impact styrene (HIPS) or the like, which are reciprocally movable in a direction indicated by arrows f along a lower surface of the toner container 12a. Each conveying member 12b1 has a substantially triangular cross section, and is provided with a plurality of long rod members extending along the rotation axis of the photosensitive drum (direction perpendicular to the plane of Fig. 4) to scrape the entire lower surface of the toner container 12a. The rod members are connected to each other at both ends thereof to form an integral structure. Further, there are three conveying members 12b1 and the displacement range of the conveying members is selected to be larger than the lower width of the triangular cross section so that all of the toner on the lower surface of the toner container can be scraped off. In addition, an arm member 12b2 is provided at its free end with a projection 12b6, which prevents the feed links from slipping and becoming disorganized.

The feed member 12b1 has a locking projection 12b4 at one of its longitudinal ends, which projection is rotatably fitted in a slot 12b5 formed in an arm member 12b2. The arm member 12b2 is rotatably mounted on the upper frame 14 via a shaft 12b3, and is connected to an arm (not shown) disposed outside the toner container 12a. Further, a drive transmission means is connected to the feed members 12b1 so that when the process cartridge B is mounted within the image forming system A, the driving force from the image forming system is transmitted to the feed members to pivot the arm member 12b2 about the shaft 12b3 by a predetermined angle. In this case, as shown in Fig. 7 and the like, the feed members 12b1 and the arm member 12b2 may be integrally formed of resin such as polypropylene, polyamide or the like so that they can be folded at a connecting portion between them.

Accordingly, in the image forming operation, when the arm member 12b1 is pivoted by a predetermined angle, the feed members 12b1 are reciprocated along the lower surface of the toner container 12a in the direction f between a state shown by the solid lines and a state shown by the broken lines. Accordingly, the toner located near the lower surface of the toner container 12a is fed to the developing sleeve 12d through the feed members 12b1. In this case, since each feed member 12b1 has a triangular cross section, the toner is caught by the feed members and is smoothly fed along the inclined surfaces of the feed members 12b1. Therefore, the toner near the developing sleeve 12d is not easily stirred, and therefore the toner layer deposited on the surface of the developing sleeve 12b is not easily destroyed.

Further, as shown in Fig. 4, a lid member 12f of the toner container 12a is provided with a depending member 12f1. A distance between a lower end of the developing member 12f1 and the lower surface of the toner container is selected to be slightly larger than a height of the triangular cross section of each toner supply member 12b1. Accordingly, the toner supply member 12b1 is reciprocated between the lower surface of the toner container and the depending member 12f1, with the result that when the supply member 12b1 attempts to slip on the lower surface of the toner container, such slipping is limited or regulated, thereby preventing the slipping of the supply members 12b1.

Here, the image forming system A according to the embodiment shown may accommodate a process cartridge containing the non-magnetic toner. In this case, the toner supply mechanism is driven to stir the non-magnetic toner near the developing sleeve 12d.

Incidentally, when the non-magnetic toner is used, as shown in Fig. 19, an elastic roller 12g rotated in the same direction as the developing sleeve 12d feeds the non-magnetic toner from the toner container 12a to the developing sleeve 12d through the toner supply mechanism 12h. In this case, at a gap between the developing sleeve 12d and the elastic roller 129, the toner is charged on the elastic roller 129 by friction between the sliding contact between the toner and the developing sleeve 12d to electrostatically adhere to the developing sleeve 12d. During the rotation of the developing sleeve 12d, the non-magnetic toner adhering to the developing sleeve 12d enters a contact area between the developing blade 12e and the developing sleeve 12d to form the thin toner layer on the developing sleeve, and the toner is charged by friction through the sliding contact between the toner and the developing sleeve, the polarity being sufficient to develop the electrostatic latent image. However, if the toner remains on the developing sleeve 12d, the remaining toner is mixed with the new toner which is supplied to the developing sleeve 12d and which is fed into the contact area between the developing sleeve and the developing blade 12e. The remaining toner and the new toner are charged by friction through the sliding contact between the toner and the developing sleeve 12d. However, in this case, although the new toner is charged with the appropriate charge, the old toner, since it is already charged from the state in which it is already charged with the appropriate charge, is overcharged. The overcharged or excessively charged toner has an attractive force (to the developing sleeve 12d) greater than that of the properly charged toner, thereby making its use in the developing process more difficult.

To avoid this, in the illustrated embodiment concerning the process cartridge containing the non-magnetic toner, as shown in Fig. 12, the non-magnetic toner supply mechanism 12h comprises a rotary member 12h1 disposed in the toner container 12a, which rotary member 12h1 has an elastic agitating blade 12h2. When the non-magnetic toner cartridge is mounted in the image forming system A, the drive transmission member is connected to the rotary member 12h1 so that it is rotated by the image forming system in the image forming process. In this way, when the image is formed by using the cartridge containing the non-magnetic toner and incorporating it in the image forming system, the toner in the toner container 12a is strongly stirred by the stirring blade 12h2. As a result, the toner in the vicinity of the developing sleeve 12d is also stirred to be mixed with the toner in the toner container 12a, thereby dispersing the charges removed from the developing sleeve 12d in the toner within the toner container to prevent the deterioration of the toner.

The developing sleeve 12d on which the toner image is formed is arranged opposite to the photosensitive drum 9 with a small gap therebetween (about 300 µm for the process cartridge containing the magnetic toner or about 200 µm for the process cartridge containing the non-magnetic toner). Accordingly, in the illustrated embodiment, stop rings each having an outer diameter larger than that of the developing sleeve by an amount corresponding to the small gap are arranged near both axial ends of the developing sleeve 12d and outside the toner layer formation region so that these rings abut against the photosensitive drum 9 in regions outside the latent image formation region.

Now, the positional relationship between the photosensitive drum 9 and the developing sleeve 12d will be explained. Fig. 20 is a longitudinal sectional view showing a positional relationship between the photosensitive drum 9 and the developing sleeve 12d and a structure for pressurizing the developing sleeve, Fig. 21A is a sectional view taken along the line A - A in Fig. 20, and Fig. 21B is a sectional view taken along the line B - B of Fig. 20.

As shown in Fig. 20, the developing sleeve 12d on which the toner image is formed is arranged in an opposed relationship to the photosensitive drum 9 with a small gap therebetween (about 200 - 300 µm). In this case, the photosensitive drum 9 is rotatably supported on the lower frame 15 by a rotation axis 9f of the flange gear 9c is rotatably supported at one end of the drum via a support member 33. The other end of the photosensitive drum 9 is also rotatably secured to the lower frame 12 via a bearing portion 26a of the bearing member 26 secured to the lower frame. The developing sleeve 12d has the above-described stopper rings 12d1 each having an outer diameter larger than that of the developing sleeve by the amount corresponding to the narrow gap and are arranged near both axial ends of the developing sleeve and outside the toner image forming area so that these rings abut against the photosensitive drum 9 in areas outside the latent image forming area.

Further, the developing sleeve 12d is rotatably supported by the sleeve bearings 12i between the stopper rings 12d1 near both axial ends of the developing sleeve and outside the toner image forming area, which sleeve bearings 12i are fixed to the lower frame in such a manner that they can be easily displaced in directions shown by the arrow g in Fig. 20. Each sleeve bearing 12i has a rearwardly projecting projection around which is mounted a compression spring 12j having one end abutting against the lower frame 15. Accordingly, the developing sleeve 12d is always biased toward the photosensitive drum 9 by these compression springs. With this arrangement, the stopper rings 12da always abut against the photosensitive drum 9, with the result that the predetermined gap between the developing sleeve 12d and the photosensitive drum 9 is always maintained, thereby transmitting the driving force to the flange gear 12c of the photosensitive drum and a sleeve gear 12k of the developing sleeve 12d which meshes with the flange gear 12c.

The sleeve wheel 12k also forms a flange section of the development sleeve 12d. It should be noted that that according to the embodiment shown, the sleeve wheel 12k and the flange portion are integrally formed from resin material (e.g., polyacetylene resin). Furthermore, a metal pin 12d2 having a smaller diameter (e.g., made of stainless steel) and having one end rotatably supported in the lower frame 15 is press-fitted and inserted into the sleeve wheel 12k (flange portion) at its center. The metal pin 12d2 serves as a rotation axis at one end of the developing sleeve 12d. Since according to the embodiment shown, the sleeve wheel and the flange portion can be integrally formed from resin, it is possible to facilitate the manufacture of the developing sleeve and to make the developing sleeve 12d and the process cartridge B lightweight.

Now, the sliding directions of the sleeve bearings 12i will be explained with reference to Fig. 22. First, the driving of the developing sleeve 12d will be described. When the driving force is transmitted from the driving source (driving motor 54) of the image forming system to the flange gear 9c and then from the flange gear 12c to the sleeve gear 12k, the engaging force between the gears is directed in a direction which is inclined or shifted from a tangential line which touches a pitch circle of the flange gear 9c and which touches a pitch circle of the sleeve gear 12k by a pressure angle (20° in the illustrated embodiment). Therefore, the engaging force is directed in a direction shown by the arrow B in Fig. 22 (θ 20°). In this case, when the sleeve bearings 12i slide in a direction parallel to a line touching the fulcrum of the photosensitive drum 9 and the fulcrum of the developing sleeve 12d, when the engaging force P is divided into a force component Ps of a horizontal direction parallel to the sliding direction and a force component pH of a vertical direction perpendicular to the sliding direction as shown in Fig. 22, the force component of the horizontal direction parallel to the sliding direction is always directed away from the photosensitive drum 9. As a result, according to the drive of the developing sleeve 12d, the distance between the photosensitive drum 9 and the developing sleeve 12d is easily changed in accordance with the engagement force between the flange gear 9c and the sleeve gear 12k, with the result that the toner on the developing sleeve 12d cannot be properly moved to the photosensitive drum 9, thereby deteriorating the developing ability.

To avoid this, in the illustrated embodiment as shown in Fig. 21A, taking into account the transmission of the driving force from the flange gear 9c to the sleeve gear 12k, the sliding direction of the sleeve bearing 12i on the driving side (on the side on which the sleeve gear 12k is arranged) coincides with the directions shown by the arrow Q. That is, an angle φ formed between the direction of the engaging force P (between the flange gear 9c and the sleeve gear 12k) and the sliding direction is set to have a value of about 90° (92° in the illustrated embodiment) In this embodiment, the force component Ps of the horizontal direction parallel to the sliding direction is negligible, and in the illustrated embodiment, the force component Ps acts to slightly bias the developing sleeve 12d toward the photosensitive drum 9. In such a case, the developing sleeve 12d is pressed by an amount corresponding to the spring pressure α of the pressing springs 12j to keep the distance between the photosensitive drum 9 and the developing sleeve 12d constant, thereby ensuring proper development.

Next, the sliding direction of the plain bearing 12i on the non-driven side (on the side where the developing sleeve 12k is not arranged). On the non-driven side, in contrast to the driven side described above, since the sliding bearing 12i does not receive a driving force as shown in Fig. 21B, the sliding direction of the sliding bearing 12i is selected to be substantially parallel to a line connecting a center of the photosensitive drum 9 and a center of the developing sleeve 12d.

In this way, when the developing sleeve 12d is pressed to the photosensitive drum 9 by changing the pressure angle for pressing the developing sleeve 12d on the driving side from that on the non-driving side, the positional relationship between the developing sleeve 12d and the photosensitive drum 9 is always maintained appropriately, thereby enabling appropriate development.

Here, the sliding direction of the slide bearing 12i on the driven side may be set to be substantially parallel to the line connecting the center of the photosensitive drum 9 and the center of the developing sleeve 12d as in the case of the non-driven side. Note that, as in the above-described embodiment, on the driven side, since the developing sleeve 12d is pushed away from the photosensitive drum 9 by the component force Ps (the engagement force between the flange gear 9c and the sleeve gear 12k) directed to the sliding direction of the slide bearing 12i, in this embodiment, the urging force of the urging spring 12j on the driven side may be set to have a value larger than that on the non-driven side by an amount corresponding to the component force Ps. This means that when the pressing force of the pressing spring 12j on the developing sleeve 12d on the non-driven side is P, the pressing force P2 of the pressing spring 12j on the driven side is set to have a relationship P2 = P1 + Ps is satisfied, with the result that the developing sleeve 12d is always subjected to the appropriate pressing force, thereby ensuring that there is a constant distance between the developing sleeve and the photosensitive drum 9.

(Cleaning supplies)

The cleaning agent 13 serves to remove the residual toner remaining on the photosensitive drum 9 after the toner image on the photosensitive drum 9 has been transferred to the recording medium 4 by the transfer agent 6. As shown in Fig. 4, the cleaning means 13 includes an elastic cleaning blade 13a which contacts the surface of the photosensitive drum 9 and is adapted to remove or scrape off the residual toner remaining on the photosensitive drum 9, a squeegee blade 13b which lightly contacts the surface of the photosensitive drum 9 and is arranged below the cleaning blade 13a to collect the removed toner, and a waste toner container 13c for collecting the waste toner collected by the blade 13b. At this time, the squeegee blade 13b lightly contacts the surface of the photosensitive drum 9 and serves to allow the passing of the residual toner remaining on the photosensitive drum, but to direct the toner removed from the photosensitive drum 9 by the cleaning blade 13a in a direction away from the photosensitive drum 9.

Now, a method of attaching the squeegee blade 13b will be described. The squeegee blade 13b is attached to an attachment surface 13d of the waste toner container 13c via a double-sided adhesive tape 13e. In this case, the waste toner container 13c is made of a resin material such as high impact styrene (HIPS or the like), and has a slightly uneven surface. Therefore, as shown in Fig. 23; the double-sided adhesive tape 13e is adhered only to the attachment surface 13d and the squeegee sheet 13b is attached only to the adhesive tape 13e, there is a fear that a free edge of the squeegee sheet 13b (to be brought into contact with the photosensitive drum 9) is curved as shown by x. If such a curved edge x of the squeegee sheet 13b is generated, the squeegee sheet 13b does not contact the surface of the photosensitive drum 9 in a sealed manner, so that it cannot securely receive the toner removed by the cleaning sheet 13a.

To avoid this, it is considered that when the squeegee blade 13b is attached to the attachment surface as shown in Fig. 24A, the attachment surface 13d in a lower portion of the waste toner container is pulled downward by a pulling tool 20 to elastically deform the attachment surface to form a curve, and then the squeegee blade 13b is attached to the curved attachment surface, and thereafter, the curve of the attachment surface is released to apply the tension to the free edge of the squeegee blade 13b, thereby preventing the free edge from becoming wavy. However, in the recent small-sized process cartridges B, since the dimension of the mounting surface 13d is small, since the squeegee sheet 13b is fitted on the curved mounting surface 13d as shown in Fig. 24A, both lower ends or corners 13b1 of the squeegee sheet 13b are projected downward from the mounting surface 13d. At this time, when the squeegee sheet 13b is projected downward from the mounting surface 13d, it is apparent from the section of Fig. 1 that there is a fear that the recording medium 4 interferes with the projected squeegee sheet 13b.

Further, when the squeegee sheet 13b is attached to the curved attachment surface 13d as shown in Fig. 24A, the double-sided adhesive tape 13e protrude from the lower end of the squeegee sheet 13b. Therefore, in this state, if the squeegee sheet 13b is pressed against the double-sided adhesive tape 13e by an attachment tool 21 as shown in Fig. 24B, the protruding portion of the double-sided adhesive tape 13e will adhere to the attachment tool 21, with the result that when the attachment tool 21 is removed as shown in Fig. 24C, the double-sided adhesive tape 13e will be peeled off from the attachment surface 13d, thereby causing poor attachment of the squeegee sheet 13b.

To avoid this, in the illustrated embodiment as shown in Fig. 25A, the structure of the lower end of the squeezing roller blade 13b becomes substantially the same as the curved structure of the attachment surface 13d which has been curved by the pulling tool 20. It is to be noted that a width of the squeegee sheet 13b is changed from the both ends in the longitudinal direction to a middle portion so that the latter becomes larger than the former (for example, the width at the middle portion is about 7.9 mm and the width at both ends is about 7.4 mm). At this time, when the squeegee sheet 13b is attached to the attachment surface, the curved double-sided adhesive tape 13e does not protrude from the squeegee sheet 13b. Further, when the pulling tool 20 is removed to release the curvature of the attachment surface 13d to thereby apply the tension to the upper edge of the squeegee sheet 13b as shown in Fig. 25B, the lower end of the squeegee sheet 13b does not protrude downward from the attachment surface 13d. Therefore, the above-described interference between the recording medium 4 and the squeegee sheet 13b and the poor attachment of the squeegee sheet 13b can be prevented.

In view of the applicability and the service life of a machining tool, it is desirable that the lower edge of the squeezing roller blade 13b is straight. In this case, as shown in Fig. 26, the width of the squeegee roller blade 13 may be varied so that the width at the central portion becomes larger than that at both ends in the longitudinal direction in accordance with the amount of curvature of the attachment surface 13d. While in the above-described embodiment the attachment surface 13d was curved by being pulled by the pulling tool 20, it is understood that, as shown in Fig. 27, the attachment surface 13d may be curved by pressing toner container partition plates 13c1 formed integrally with the attachment surface 13d by pushing tools 20a.

Furthermore, while in the illustrated embodiment the squeegee blade attachment surface 13d was attached to the lower portion of the waste toner container 13c, the squeegee blade 13b may be attached to a metal plate attachment surface formed independently of the waste toner container 13c, and then the metal plate may be installed in the waste toner container 13c.

In the embodiment shown, the squeezing roller sheet 13b is made of polyethylene terephthalate (PET) and has a thickness of about 38 µm, a length of about 241.3 mm, a mean width of about 7.9 mm, a width at the ends of about 7.4 mm and a suitable radius of curvature of about 14556.7 mm.

(Upper and lower frame)

Next, the upper and lower frames 14, 15 which constitute the casing of the process cartridge B will be explained. As shown in Figs. 7 and 8, the photosensitive drum 9, the developing sleeve 12d and the developing blade 12e of the developing agent 12 and the cleaning agent 13 are provided in the lower frame 15. On the other hand, as shown in Figs. 7 and 9, the charging roller 10, the toner container 12a of the developing agent 12 and the toner supply mechanism 12b are provided in the upper frame 14.

In order to assemble the upper and lower frames 14, 15, four pairs of locking claws 14a are formed integrally with the upper frame 14, and they are arranged at equal intervals from each other in the longitudinal direction of the upper frame. Similarly, locking holes 15a and locking projections 15b for engaging with the locking claws 14a are provided integrally on the lower frame 15. Accordingly, when the upper and lower frames 14, 15 are pressed against each other with force to engage the locking claws 14a with the corresponding locking holes 15a and the locking projections 15b, the upper and lower frames 14, 15 are connected to each other. In order to ensure the connection between the upper and lower frames, as shown in Fig. 8, a locking claw 15c and a locking hole 15d are formed near both ends in the longitudinal direction of the lower frame 15, while as shown in Fig. 9, a locking hole 14b (to engage with the locking claw 15c) and a locking claw 14c (to engage with the locking hole 15d) are formed near both ends in the longitudinal direction of the upper frame 14.

When the parts constituting the process cartridge are separately contained in the upper and lower frames 14, 15 as described above, by arranging the parts which should be positioned with respect to the photosensitive drum 9 (for example, the developing sleeve 12b, the developing blade 12e and the cleaning blade 13a) within the same frame (lower frame 15 in the illustrated embodiment), it is possible to ensure that the excellent accuracy of positioning of each part is ensured and that the assembly of the process cartridge B is facilitated. Furthermore, as shown in Fig. 8, the fitting recesses 15n in the lower frame 15 are provided in the vicinity of a its side edges. On the other hand, as shown in Fig. 9, fitting projections 14h (to be fitted into the corresponding fitting recesses 15n) are formed on the upper frame 14 near one of its side edges, at positions midway between the adjacent locking claws 14a.

Furthermore, in the illustrated embodiment, as shown in Fig. 8, fitting projections 15e are formed on the lower frame 15 near two of its corners, while fitting recesses 15f are formed in the lower frame near the other two corners. On the other hand, as shown in Fig. 9, fitting recesses 14d (to engage with the corresponding fitting projections 15i) are formed on the upper frame 14 near two of its corners, while fitting projections 14e (to be inserted into the corresponding fitting recesses 15f) are formed in the lower frame near the other two corners. Accordingly, when the upper and lower frames 14, 15 are connected to each other by inserting the fitting projections 14h, 14e, 15e of the upper and lower frames 14, 15, respectively, into the corresponding fitting recesses 15n, 15f, 14d of the upper and lower frames 14, 15, respectively, they are firmly connected to each other so that even if a torsional force is applied to the upper and lower frames 14, 15 which are connected to each other, they are not separated from each other.

The positions of the above-described fitting projections and fitting recesses can be interchanged as long as the upper and lower frames 14, 15, which are connected to each other, are not separated from each other by any torsional force exerted on them.

Further, as shown in Fig. 9, a protective cover 22 is rotatably mounted on the upper frame 14 via pivot pins 22a. The protective cover 22 is biased in a direction indicated by an arrow h in Fig. 9 by coil torsion springs (not shown) arranged around the pivot pins 22a so that the protective cover 22 closes or covers the photosensitive drum 9 in the state where the process cartridge B is removed from the image forming system A as shown in Fig. 4. Specifically, as shown in Fig. 1, the photosensitive drum 9 is adapted to be exposed from an opening 159 provided in the lower frame 15 so as to face the transfer roller 6 to enable transfer of the toner image from the photosensitive drum to the recording medium 4. However, in the state where the process cartridge B is removed from the image forming system A, when the photosensitive drum 9 is exposed to the environment, it will be deteriorated by the ambient light and the dirt and the like adhering to the photosensitive drum 9. To avoid this, when the process cartridge B is removed from the image forming system A, the opening 15g is closed by the protective cover 22, thereby protecting the photosensitive drum 9 from the ambient light and the dirt. At this time, when the process cartridge B is mounted within the image forming system A, the protective cover 22 is rotated by a swing mechanism (not shown) to expose the photosensitive drum 9 from the opening 15g.

As can be further seen from Fig. 1, in the illustrated embodiment, the lower surface of the lower frame 15 also serves as a guide for conveying the recording medium 4. The lower surface of the lower frame is formed with guide sections 15h1 on both sides and a stepped central guide section 15h2 (Fig. 6). The longitudinal length (ie the distance between the steps) of the central guide section 15h2 is about 102 - 120 mm (107 mm in the illustrated embodiment), which is slightly larger than a width (about 100 mm), and the Depth of the step is selected to have a value of about 0.8 - 2 mm. With this arrangement, the middle guide portion 15h2 enlarges the conveying space for the recording medium 4, with the result that even when a thicker and stiffer sheet such as a postcard, a business card or an envelope is used as the recording medium 4, such a thicker sheet does not interfere with the guide surface of the lower frame 15, thereby preventing the recording medium from jamming. On the other hand, when a thin sheet having a width larger than that of a postcard such as a whole sheet is used as the recording medium, such a sheet (recording medium) is guided by both side guide portions 15h1 and it is possible to convey the sheet without slippage.

The lower surface of the lower frame 15, which serves as a conveying guide for the recording medium, will now be described in more detail. As shown in Fig. 28, both side guide portions 15h1 can be bent by an amount La (= 5 - 7 mm) with respect to a tangential direction X with respect to a gap N between the photosensitive drum and the transfer roller 6. Since both side guide portions 15hl are formed on the lower surface of the lower frame 15, which is designed to provide the required space between the lower frame and the developing sleeve 12d and the required space for sufficiently guiding the toner to the developing sleeve, such guide portions are determined by the position of the developing sleeve 12d, which is selected to obtain the optimum developing state. If the lower surfaces of the side guide portions approach the tangential line X, the thickness of the lower frame 15 is reduced, thereby causing a problem concerning the strength of the process cartridge B.

Further, the position of a lower end 13f of the cleaning means 13 is determined by the positions of the cleaning blade 13a, the squeegee blade 13b and the like constituting the cleaning means 13 as will be described later, and is selected to give a clearance Lb (= 3 - 5 mm) thereby preventing interference with the recording medium 4 being conveyed. In this case, in the illustrated embodiment, an angle β between a vertical line passing through the fulcrum of the photosensitive drum 9 as shown in Fig. 28 and a line connecting the fulcrum of a photosensitive drum and the fulcrum of the transfer roller 6 is selected to have a value of 5 - 20 degrees.

In view of the above provisions, by having the recesses or steps of a depth Lc (= 1 - 2 mm) only in the middle guide portion 15h2 to approximate this guide portion to the tangential line X, it is possible to smoothly feed a thicker and more rigid recording medium 4 without reducing the strength of the lower frame 15. In most cases, the thicker and more rigid recording medium 4 is a business card, an envelope or the like, which is narrower than the postcard under the general specification of the image forming system, as long as the width of the stepped or recessed middle guide portion 15h2 is selected to be slightly larger than that of the postcard, there is no problem for practical use.

Further, regulating projections 15i projecting downward are formed on the outer surface of the lower frame 15 in areas outside the recording medium guide zone. The regulating projections 15i each project from the guide surfaces of the lower frame for the recording medium 4 by about 1 mm. With this arrangement, even if the process cartridge is slightly lowered for some reason during the image forming process, the Further lowering of the process cartridge can be prevented because the regulating projections 15i abut against a lower guide member 23 (Fig. 1) of the image forming system body 16. Accordingly, a space of at least 1 mm is maintained between the lower guide member 23 and the lower guide surface of the lower frame 15 to provide a conveying path for the recording medium 4, thereby enabling the conveyance of the recording medium without jamming. Further, as shown in Fig. 1, a recess 15j is formed in the lower surface of the lower frame 15 so as not to interfere with the register roller 5c2. Therefore, when the process cartridge B is mounted in the image forming system A, the entire image forming system can be of small construction because it can be mounted near the register roller 5c2.

(Assembly of the process cartridge)

Next, the assembly of the process cartridge having the above-described structure will be explained. In Fig. 31, toner leakage prevention seals S having a regular shape and made of Moltopren (flexible polyurethane manufactured by INOAC Incorp.) rubber for preventing leakage of toner are attached to the ends of the developing means 12 and the cleaning means 13 and to the lower frame 14. Incidentally, each of the toner leakage prevention seals S need not have the regular shape. Alternatively, the toner leakage prevention seals may be attached by forming molding recesses in portions (to be attached) of the seals and by pouring liquid material, which becomes an elastomer when it solidifies, into the recesses.

A sheet support member 12el to which the developing sheet 12e is attached and a sheet support member 13al to which the cleaning sheet 13 is attached are attached to the lower frame 15 via pins 24a, 24b, respectively. According to the embodiment shown, as shown by As shown by broken lines in Fig. 29, the attachment surfaces of the sheet support members 12e1, 13a1 are substantially parallel to each other so that the pins 24a, 24b can be driven from the same direction. Therefore, when a large number of process cartridges B are manufactured, the developing sheets 12e and the cleaning sheets 13a can be continuously attached by the pins by using an automatic device. Furthermore, the assemblability of the sheets 12e, 13a can be improved by providing a space for a screwdriver, and the shape of a mold can be simplified by aligning the case removal direction from the mold, thereby achieving cost saving.

At this time, the developing sheet 12e and the cleaning sheet 13a need not be attached by the pins (screws), but they may be attached to the lower frame 15 by adhesives 24c, 24d as shown in Fig. 30. Furthermore, in this case, if the adhesives can be applied from the same direction, the attachment of the developing sheet 12e and the cleaning sheet 13a can be carried out automatically and continuously by using an automatic device.

After the sheets 12e, 13a have been attached as described above, the developing sleeve 12d is attached to the lower frame 15. Then, the photosensitive drum 9 is attached to the lower frame 15. In the illustrated embodiment, guide members 25a, 25b are attached to the surfaces (opposite to the photosensitive drum) of the sheet supporting members 12e1, 13a1, respectively, in areas outside the longitudinal image forming area C (Fig. 32) of the photosensitive drum 9. (In the illustrated embodiment, the guide members 25a, 25b are formed integrally with the lower frame 15.) A distance between the guide members 25a and 25b is set to be larger than the outer diameter D of the photosensitive drum 9. drum 9. Therefore, after various parts such as the developing blade 12e, the cleaning blade 13a and the like are attached to the lower frame 15 as shown in Fig. 31, the photosensitive drum 9 can be finally attached to the lower frame while the two ends in the longitudinal direction (outside the image forming area) of the photosensitive drum are guided by the guide members 25a, 25b. Note that the photosensitive drum 9 is attached to the lower frame 15 while the cleaning blade 13a is slightly bent and/or the developing sleeve 12d is slightly retarded and rotated.

If the photosensitive drum 9 is first attached to the lower frame 15 and then the sheets 12e, 13a and the like are attached to the lower frame, there is a fear that the surface of the photosensitive drum 9 will be damaged during the attachment of the sheets 12e, 13a and the like. Furthermore, during the assembling process, it is difficult or impossible to check the attachment position of the developing sheet 12e and the cleaning sheet 13a and to measure the contact pressures between the sheets and the photosensitive drum. In addition, although a lubricant must be applied to the blades 12e, 13a in order to prevent an increase in the torque and/or the setting up of the blade due to the tight contact between the original blades 12e, 13a (in the non-toner state) and the photosensitive drum 9 and the developing sleeve 12d before the blades 12e, 13a are attached to the lower frame, such a lubricant is likely to drip from the blades during the assembly of the blades. However, according to the illustrated embodiment, since the photosensitive drum 9 is ultimately attached to the lower frame, the above-described disadvantages and problems can be avoided.

As described above, it is, according to the According to the embodiment shown, it is possible to check the mounting positions of the developing agent 12 and the cleaning agent 13 in the state in which these agents 12, 13 are attached to the frame, and to prevent the image forming area of the photosensitive drum from being damaged or scratched during assembly of the drum. Furthermore, since it is possible to apply the lubricant to the blades in the state in which these agents 12, 13 are attached to the frame, dripping of the lubricant can be prevented, thereby preventing the occurrence of an increase in torque and/or the eruption of the blades due to the tight contact between the developing blade 12e and the developing sleeve 12d and between the cleaning blade 13a and the photosensitive drum 9.

While in the illustrated embodiment, the guide members 25a, 25b were formed integrally with the lower frame 15 as shown in Fig. 33, the projections 12e2, 13a2 may be formed integrally on the sheet support members 12e1, 13a1, or other guide members may be attached to the sheet support members at both end portions in the longitudinal direction of the sheet support members outside the image forming area of the photosensitive drum 9 so that the photosensitive drum 9 is guided by these projections or other guide members during the assembly of the drum.

After the developing sleeve 12d, the developing blade 12e, the cleaning blade 13a and the photosensitive drum 9 are mounted on the lower frame 15 as described above and as shown in Fig. 34 (axonometric view) and Fig. 35 (sectional view), the bearing members 26 are installed to support one end of the photosensitive drum 9 and the developing sleeve 12, respectively. The bearing member 26 is made of a wear-resistant material such as polyacetal, and comprises a drum bearing portion 26a to be assembled with the photosensitive drum 9, a sleeve bearing portion 26b to be assembled with the outer surface of the developing sleeve 12d, and a D-shaped cut hole portion 26c to be fitted on one end of a D-shaped cut magnet 12c. Alternatively, the sleeve bearing portion 26b may be fitted on the outer surface of the sleeve bearing 12i supporting the outer surface of the developing sleeve 12d, or it may be fitted between sliding surfaces 15Q of the lower frame 15 fitted on the outer surface of the sliding bearing 12i.

Accordingly, when the drum support portion 26a is attached to one end of the photosensitive drum 9, and when the end of the magnet 12c is inserted into the D-shaped cut hole portion 26c and the developing sleeve 12d is inserted between the sleeve support portion 26b and the support member 26 which is fitted into the side of the lower frame 15 while sliding in the longitudinal direction of the drum, then the photosensitive drum 9 and the developing sleeve 12d are rotatably supported. Here, as shown in Fig. 34, the ground contact 18a is attached to the bearing member 26, and when the bearing member 26 is fitted into the side of the lower frame, the ground contact 18a is in contact with the aluminum drum core 9a of the photosensitive drum 9 (see Fig. 10). Further, the development bias contact 18b is attached to the bearing member 26, and when the bearing member 26 is attached to the development sleeve 12d, the bias contact 18b is in contact with a conductive member 18d which contacts the inner surface of the development sleeve 12d.

By supporting the photosensitive drum 9 and the developing sleeve 12d by the single bearing member 26 in this way, it is possible to improve the accuracy of positioning of the elements 9, 12d and to reduce the number of parts, thereby facilitating the assembly process and achieving cost savings. Furthermore, since the positioning of the photosensitive drum 9 and the positioning of the developing sleeve 12d and the magnet 12c can be performed by using the single member, it is possible to determine the positional relationship between the photosensitive drum 9 and the magnet 12c with high accuracy, with the result that it is possible to constantly maintain a magnetic force with respect to the surface of the photosensitive drum 9, thereby obtaining a high quality image. Furthermore, since the ground contact 18a for grounding the photosensitive drum 9 and the developing bias contact 18b for applying the developing bias to the developing sleeve 12d are mounted on the bearing member 26, the compactness of the parts can be effectively achieved, thereby effectively making the process cartridge B small.

Further, by providing (on the bearing member 26) bearing portions for positioning the process cartridge B within the image forming system when the process cartridge is mounted within the image forming system, the positioning of the process cartridge B with respect to the image forming system can be accurately performed in an efficient manner.

As further apparent from Figs. 5 and 6, an outwardly projecting U-shaped projection, i.e., the drum axis portion 26d (Fig. 20) is also formed on the bearing member 26. When the process cartridge B is mounted within the body 16 of the image forming system, the drum axis portion 26d is supported by an axis bearing member 34 as will be described later, thereby positioning the process cartridge B. In this way, since the process cartridge B is positioned by the support member 26 for directly supporting the photosensitive drum 9 when the cartridge is installed in the system body 16, the photosensitive drum 9 can be accurately positioned regardless of manufacturing and/or assembly errors of other parts.

Further, as shown in Fig. 35, the other end of the magnet 12c is received in an inner recess formed in the sleeve wheel 12k, and an outer diameter of the magnet 12c is set to be slightly smaller than the inner diameter of the recess. Therefore, in the sleeve wheel 12k, the magnet 12c is held in the recess with a clearance, and it is held in a lower position in the recess by its own weight, or it is biased toward the blade support member 12e1 made of a magnetic metal, such as ZINKOTE (zinc-coated steel plate, manufactured by Shin Nippon Steel Incorp.), by a magnetic force of the magnet 12c. In this way, since the sleeve gear 12k and the magnet 12c are connected to each other with play, the friction torque between the magnet 12c and the rotatable sleeve gear 12k can be reduced, thereby reducing the torque affecting the process cartridge.

On the other hand, as shown in Fig. 31, the charger roller 10 is rotatably supported within the upper frame 14, and the shutter member 11b, the protective cover 22, and the toner supply mechanism 12b are also attached to the upper frame 14. The opening 12a1 for feeding the toner from the toner container 12a to the developing sleeve 12d to the outside is closed by a cover film 26 (Fig. 36) having a peel-off tape 27. Further, the lid member 12f is fixed to the upper frame, and thereafter, the toner is supplied to the toner container 12a through the filling opening 12a3, and then the filling opening 12a3 is closed by the lid 12a2, thereby sealing the toner container 12a.

At this time, as shown in Fig. 36, the release tape 27 of the cover film 28 adhered around the opening 12a1 extends from one end in the longitudinal direction (right end in Fig. 36) of the opening 12al to the other end in the longitudinal direction (left end in Fig. 36), and is bent at the other end and further extends along a gripping portion 14f which is formed on the upper frame 14 and projects outwardly therefrom.

Next, the process cartridge B is assembled by connecting the upper and lower frames 14, 15 via the above-described locking claws and locking holes or recesses. In this case, as shown in Fig. 37, the peeling tape 27 is disposed between the gripping portion 14f of the upper frame 14 and a gripping portion 15k of the lower frame 15. Therefore, when a new process cartridge B is used, the operator pulls a protruding portion of the peeling tape 27 protruding between the gripping portions 14f, 15k to peel the peeling tape 27 from the covering film 28 so as to open the opening 12a1, thereby allowing the movement of the toner in the toner container 12a to the developing sleeve 12d. Thereafter, the process cartridge is installed in the image forming system A.

As described above, by having the peeling tape 27 project between the gripping portions 14f, 15k of the upper and lower frames 14, 15, the peeling tape 27 can be easily made to project from the process cartridge when the upper and lower frames 14, 15 are assembled. The gripping portions 14f, 15k are used when the process cartridge B is installed in the image forming system. Therefore, if the operator forgets to remove the peeling tape 27 before installing the process cartridge in the image forming system, since he must grip the gripping portions when installing the process cartridge, he will know that the unremoved peeling tape 27 is there. Furthermore, if the color of the peel-off tape 27 is clearly distinguished from the color of the frames 14, 15 (for example, if the frames are black, a white or yellow peel-off tape 27 is used), then the visibility is improved, thereby reducing the risk of failure to remove the peel-off tape.

Further, when a U-shaped guide rib for temporarily holding the peel tape 27 is provided on the gripping portion 14f of the upper frame 14, it is possible to securely and easily protrude the peel tape 27 at a predetermined position during the assembly of the upper and lower frames 14, 15. Then, when the process cartridge B is assembled by connecting the upper and lower frames 14, 15 together, since the recess 15j for receiving the register roller 5c2 is formed on the outer surface of the lower frame 15 as shown in Fig. 38, the operator can securely grip the process cartridge B by inserting his fingers into the recess 15j. Furthermore, in the illustrated embodiment, as shown in Fig. 6, slip-preventing ribs 14i are formed on the process cartridge B so that the operator can easily grip the process cartridge by resting his fingers against the ribs. Furthermore, since the recess for receiving (preventing contact) the register roller 5c2 is formed in the lower frame 15 of the process cartridge B, it is possible to make the image forming system smaller.

Furthermore, as shown in Fig. 6, since the recess 15j is formed along and near the locking claws 14a and the locking holes 15b through which the upper and lower frames are connected to each other, when the operator grips the process cartridge B by pressing his fingers against the recess 15j, the operator's gripping force acts in the locking direction, thereby securely locking the locking claws 14a and the locking holes 15b to each other.

The assembly and delivery line for the process cartridge B will now be explained with reference to Fig. 39A. As shown, the various parts are assembled in the lower frame 15, and then the lower frame in which the various parts are installed are checked (for example, the positional relationship between the photosensitive drum 9 and the developing sleeve 12d is checked). Then, the lower frame 15 is connected to the upper frame 14 within which the parts such as the charger roller 10 are assembled, thereby forming the process cartridge B. After that, an overall check of the process cartridge B is carried out, and then the process cartridge is shipped. Therefore, the assembly and shipment line is very simple.

(Installing the cartridge)

Next, the structure for installing the process cartridge B into the image forming system A will be explained.

As shown in Fig. 40, a loading member 29 having a fitting window 29a conforming to the outer shape of the process cartridge B is provided on the upper opening/closing cover 19 of the image forming system A. The process cartridge B is inserted into the image forming system through the fitting window 29a by gripping the gripping portions 14f, 15k. In this case, a guide comb 31 formed in the process cartridge is guided by a guide groove (no reference numeral) formed in the cover 19, and the lower portion of the process cartridge is guided by a guide plate 32 having a hook at its free end.

In this case, as shown in Fig. 40, a projection 30 for preventing misassembly is formed on the process cartridge B, and the fitting window 29a has a recess 39b for receiving the projection 30. As shown in Figs. 40 and 41, the structure or position of the projection 30 differs depending on a particular process cartridge containing the toner having a development sensitivity suitable for the particular image forming system A (i.e., there are differences for each process cartridge), so that even if an attempt is made to mount a process cartridge having a different development sensitivity, it cannot be installed in this image forming system because the projection 30 does not fit with the fitting window 29a of this image forming system. In this way, erroneous mounting of the process cartridge B can be prevented, thereby preventing a bad image from being formed due to a toner having a different development sensitivity. Accordingly, it is also possible to prevent erroneous mounting of a process cartridge containing a different type of photosensitive drum such as is the case with the different development sensitivity. Furthermore, since the recess 29b and the projection 30 are located on this side when the process cartridge is installed, when the operator mistakenly tries to install the process cartridge in the image forming system, he can easily recognize with his eyes the fact that the projection 30 is blocked by the loading member 29. Therefore, the possibility that the operator forcibly pushes the process cartridge into the image forming system and damages the process cartridge B and/or the image forming system A as in the conventional case can be prevented.

After the process cartridge B is inserted into the fitting window 29a of the opening/closing cover 19, when the cover 19 is closed, the rotary shaft 9f of the photosensitive drum 9 projecting from one side of the upper and lower frames 14 is supported by a shaft support member 33 (Fig. 40) via a bearing 46a, and the rotary shaft 12d2 of the developing sleeve 12d projecting from one side of the upper and lower frames 14, 15 is supported by the shaft support member 33 via a sliding bearing 46b and a bearing 46c (Fig. 35). On the other hand, the drum shaft portion 26d (Fig. 35) of the support member 26 attached to the other end of the photosensitive drum 9 is supported by a shaft support member 34 shown in Fig. 42.

In this case, the protective cover 22 is rotated to expose the photosensitive drum 9, with the result that the photosensitive drum 9 comes into contact with the transfer roller 6 of the image forming system A. Further, the drum ground contact 18a contacting the photosensitive drum 9, the developing bias contact 18b contacting the developing sleeve 12d, and the charging bias contact 18c contacting the charger roller 10 are provided on the process cartridge B so that these contacts protrude from the lower surface of the lower frame 15, and these contacts 18a, 18b, 18c are respectively forcibly brought into contact with the drum ground contact pin 35a, the developing bias contact pin 35b, and the charging bias contact pin 35c (Fig. 42).

As shown in Fig. 42, these contact pins 35a, 35b, 35c are arranged such that the ground contact pin 35a and the charging leader contact pin 35c are arranged on the downstream side of the transfer roller 6 in the recording medium conveying direction, and that the developing leader contact pin 35b is arranged on the upstream side of the transfer roller 6 in the recording medium conveying direction. Accordingly, as shown in Fig. 43, the contacts 18a, 18b, 18c provided on the process cartridge B are similarly arranged so that the drum ground contact 18a and the charging bias contact 18c are arranged on a downstream side of the photosensitive drum 9 in the conveying direction of the recording medium, and that the developing bias contact 18b is arranged on the upstream side of the photosensitive drum 9 in the conveying direction of the recording medium.

Now, the arrangement of the electric contacts of the process cartridge B will be explained with reference to Fig. 51. Fig. 51 is a schematic top view showing the positional relationship between the photosensitive drum 9 and the electric contacts 18a, 18b, 18c.

As shown in Fig. 51, the contacts 18a, 18b, 18c are arranged at the end of the photosensitive drum 9 opposite to the end at which the flange gear 9c is arranged in the longitudinal direction of the drum. The development bias contact 18b is arranged at one side of the photosensitive drum 9 (i.e., at the side where the developing agent 12 is arranged), and the drum ground contact 18a and the charging bias contact 18c are arranged at the other side of the photosensitive drum (where the cleaning member 13 is arranged). The drum ground contact 18a and the charging bias contact 18c are arranged substantially along a straight line. Further, the developing bias contact 18b is arranged slightly outward from the positions of the drum ground contact 18a and the charging bias contact 18c in the longitudinal direction of the photosensitive drum 9. The drum ground contact 18a, the developing bias contact 18b and the charging bias contact 18c are arranged in a gradual manner from the outer peripheral surface of the photosensitive drum 9 in this order (i.e., the distance between the contact 18a and the drum is the smallest and the distance between the contact 18c and the drum is the largest). Further, an area of the developing bias contact 18b is larger than an area of the drum ground contact 18a and an area of the charging bias contact 18c. Further, the developing bias contact 18b, the drum ground contact 18a, and the charger bias contact 18c are arranged outward from a position where the arm portions 18a3 of the drum ground contact 18a are in contact with the inner surface of the photosensitive drum 9 in the longitudinal direction of the photosensitive drum 9.

As mentioned above, by arranging the electrical contacts between the process cartridge (which may be incorporated within the image forming system) and the image forming system at the location of the adjacent side of the process cartridge, it is possible to positionally By improving the accuracy between the contacts of the process cartridge and the contact pins of the image forming system, thereby preventing poor electrical contact, and by arranging the contacts on the non-driven side of the process cartridge, it is possible to make the structure of the contact pins of the image forming system simple and small in size.

Furthermore, since the contacts of the process cartridge are arranged within the periphery of the frames of the process cartridge, it is possible to prevent foreign matter from adhering to the contacts, and therefore it is possible to prevent corrosion of the contacts; and further, it is possible to prevent deformation of the contacts due to external forces. Furthermore, since the developing bias contact 18b is arranged on the side of the developing means 12, and since the drum ground contact 18a and the charger bias contact 18c are arranged on the side of the cleaning means 13, the arrangement of the electrodes in the process cartridge can be simplified, thereby making the process cartridge small.

Now, the dimensions of various parts in the illustrated embodiment will be listed below. However, it should be noted that these dimensions are only an example and the present invention is not limited to this example.

(1) Distance (X1) between the photosensitive drum 9 and the ground contact 18a about 6.0 mm;

(2) Distance (X2) between the photosensitive drum 9 and the charger bias contact 18c about 18.9 mm;

(3) Distance (X3) between the photosensitive drum 9 and the developing leader contact 18b about 13.5 mm;

(4) Width (Y1) of charger bias contact 18c approximately 4.9 mm;

(5) Length (Y2) of the charger pre-tension contact 18c about 6.5 mm;

(6) Width (Y3) of the drum-earth contact 18a approximately 5.2 mm;

(7) Length (Y4) of the drum-earth contact 18a approximately 5.0 mm;

(8) Width (Y5) of developing bias contact 18a about 8.2 mm;

(9) Length (Y6) of developing bias contact 18a about 8.0 mm;

(10) Diameter (Z1) of the flange wheel 9c approximately 28.6 mm;

(11) Diameter (Z2) of wheel 9i approximately 26.1 mm;

(12) Width (Z3) of the flange wheel 9c approximately 6.7 mm;

(13) Width (Z3) of wheel 9i approximately 4.3 mm;

(14) Number of teeth of the flange wheel 9c 33; and

(15) Number of teeth of the wheel 9i 30.

Now, the flange gear 9c and the gear 9i will be explained. The gears 9c, 9i have helical gears. When the driving force from the image forming system is transmitted to the flange gear 9c, the photosensitive drum 9 mounted in the lower frame 15 with play is subjected to the pressing force to be displaced toward the flange gear 9c, thereby positioning the drum on the side of the lower frame 15.

The gear 9c is used with a process cartridge containing the magnetic toner for forming a black image. When the black image forming cartridge is installed within the image forming system, the gear 9c meshes with a gear of the image forming system to receive the driving force to rotate the photosensitive drum 9, and meshes with a gear of the developing sleeve. 9d to rotate it. The wheel 9i meshes with a wheel connected to the transfer roller 6 of the image forming system to rotate the transfer roller. In this case, the load in the direction of rotation does not even act on the transfer roller 6.

Optionally, the gear 9i is used with a color image forming cartridge containing the non-magnetic toner. When the color image forming cartridge is installed within the image forming system, the gear 9c meshes with the gear of the image forming system to receive the driving force to rotate the photosensitive drum 9. On the other hand, the gear 9i meshes with the gear connected to the transfer roller 6 of the image forming system to rotate the transfer roller, and meshes with the gear of the developing sleeve 12d for the non-magnetic toner to rotate it. The flange gear 9c has a diameter larger than that of the gear 9i, a width larger than that of the gear 9i, and a number of teeth larger than that of the gear 9i. Therefore, even if a larger load is applied to the gear 9c, the gear 9c can receive the driving force to rotate the photosensitive drum 9 more securely, and can transmit the larger driving force to the magnetic toner developing sleeve 9c to rotate the latter more securely.

Optionally, as shown in Fig. 43, each of the contact pins 35a - 35c is held in a corresponding holder cover 36 in such a manner that it can be slid in the holder cover but cannot be removed from the holder cover. Each contact pin 35a - 35c is electrically connected to a circuit pattern printed on an electrical substrate 37 to which the holder covers 36 are attached, via a corresponding conductive compression spring 38. In this case, the charger biasing contact 18c to be pressed against the contact pin 35c has an arcuate curvature near the rotation axis 19b of the upper opening/closing cover 19 so that the opening/closing cover 19 to which the process cartridge B is attached is rotated about the pivot axis 19d in a direction shown by the arrow R to close the cover, whereby the charger bias contact 18c located closest to the pivot axis 19b (ie, having the minimum travel) can effectively come into contact with the contact pin 35c.

(Positioning)

When the process cartridge B is installed and the opening/closing cover 19 is closed, the positioning is made such that a distance between the photosensitive drum 9 and the lens unit 1c and a distance between the photosensitive drum 9 and the original glass platen 1a are kept constant. Such positioning will now be explained.

As shown in Fig. 8, the positioning projections 15m are formed on the lower frame 15 to which the photosensitive drum 9 is attached, near both ends of the frame in the longitudinal direction. As shown in Fig. 5, when the upper and lower frames 14, 15 are connected to each other, these projections 15m protrude upward through holes 149 formed in the upper frame 14.

Further, as shown in Fig. 44, the lens unit 1c having therein the lens assembly 1c2 for reading the original 2 is attached to the upper opening/closing cover 19 (to which the process cartridge B is attached) via a pivot pin 1c3 for easy pivoting about the pivot pin, and is biased downward (Fig. 44) by a compression spring 39. Therefore, when the process cartridge B is attached to the upper cover 19 and the latter is closed as shown in Fig. 44, the lower surface of the lens unit 1c rests on the positioning projections 15m of the process cartridge B. As a result, when the process cartridge B is positioned within the image forming system A, the distance between the lens array 1c2 in the lens unit 1c and the photosensitive drum 9 mounted on the lower frame 15 is accurately determined so that the light image optically read from the original 2 can be accurately projected onto the photosensitive drum 9 via the lens array 1c2.

Further, as shown in Fig. 45, positioning pins 40 are provided in the lens unit 1c, which positioning pins can slightly project upward from the top cover 19 through holes 19c formed in the top cover. As shown in Fig. 46, the positioning pins 40 slightly project on both sides in the longitudinal direction of an original reading slot Z (Figs. 1 and 46). Therefore, when the process cartridge B is attached to the upper frame 19, and when the latter is closed and when the image forming operation is started as described above, since the lower surface of the lens unit 1c abuts against the positioning projections 1sm, the original glass carrier 1a is displaced while being seated on the positioning pins 40. As a result, a distance between the original 2 resting on the original glass carrier 1a and the photosensitive drum 9 attached to the lower frame 15 is always kept constant, whereby the light reflected from the original 2 is accurately projected onto the photosensitive drum 9. Since the information written on the original 2 can be optically read accurately and since the photosensitive drum 9 can be exposed accurately, it is possible to obtain a high quality image.

(Drive transmission)

Next, the driving force transmission to the photosensitive drum 9 in the process cartridge B mounted in the image forming system A will be explained.

When the process cartridge B is mounted within the image forming system A, the rotation axis 9f of the photosensitive drum 9 is supported by the axis support member 33 of the image forming system as described above. As shown in Fig. 47, the axis support member 33 includes a support portion 33a for the rotation axis 9f of the drum and a stopper portion 33b for the rotation axis 12d2 of the developing sleeve 12d. An overlap portion 3c having a predetermined overhang L (1.8 mm in the illustrated embodiment) is formed on the support portion 33a, thereby preventing the drum rotation axis 9f from wandering upward. Further, when the drum rotation shaft 9f is supported by the bearing portion 33a, the rotation shaft 12d2 of the developing sleeve abuts against the stopper portion 33b, thereby preventing the rotation shaft 12d2 from falling downward. Further, when the upper opening/closing cover is closed, positioning projections 15p of the lower frame 15 protruding from the upper frame 14 of the process cartridge B abut against a stopper portion 19c of the opening/closing cover 19.

Accordingly, when the driving force is transmitted to the flange gear of the photosensitive drum 9 by driving the drive gear 41 of the image forming system meshing with the flange gear, the process cartridge B is subjected to a reaction force tending to rotate the process cartridge about the drum rotation axis 9f in a direction shown by the arrow i in Fig. 47. However, since the rotation axis 12d2 of the developing sleeve is supported against the stopper portion 33b and the positioning projections 15p of the lower frame 15 projecting from the upper frame 14 are supported on the stopper portion 19c of the upper cover, the rotation of the process cartridge B is prevented.

Although, as described above, the lower surface of the lower frame 15 serves as the guide for the recording medium 4, since the lower frame is positioned by abutting against the body of the image forming system as described above, the positional relationship between the photosensitive drum 9 of the transfer roller 6 and the guide portions 15h1, 15h2 for the recording medium 4 can be maintained with high accuracy, thereby performing the feeding of the recording medium and the image transfer with high accuracy.

During the transmission of the driving force, the developing sleeve 12d is biased downward not only by the rotational reaction force acting on the process cartridge B but also by a reaction force generated when the driving force is transmitted from the flange gear 9c to the developing sleeve 12j. In this case, if the rotational axis 12d2 of the developing sleeve is not supported on the stopper portion 33b, the developing sleeve 12d will always be biased downward during the image forming operation. As a result, there is a fear that the developing sleeve 12d will be displaced downward and/or the lower frame 15 on which the developing sleeve 12d is mounted will be deformed. However, since in the illustrated variant the rotation axis 12d2 of the development sleeve is supported on the stop section 33b without error, the disadvantage described above cannot occur.

At this time, as shown in Fig. 20, the developing sleeve 12d is biased against the photosensitive drum 9 by the springs 12j via the sleeve bearings 12i. In this case, the arrangement as shown in Fig. 48 can be used to facilitate the sliding movement of the sleeve bearings 12i. Note that a bearing 12m for supporting the rotational axis 12d2 of the developing sleeve is held in a bearing holder 12n in such a manner that the bearing 12m can slide along a slot 12n1 formed in the bearing holder. In this arrangement as shown in Fig. 49, the bearing holder 12n is supported on the stopper portion 33b of the axis support member 33, and is supported by it; in this state, the bearing 12m can slide along the slot 12n1 in the directions shown by the arrow. In the illustrated embodiment, an inclination angle θ (Fig. 47) of the stopper portion 33b is selected to have a value of about 40 degrees.

Further, the developing sleeve 12d may be supported not via the sleeve rotation axis, for example, as shown in Figs. 52A and 52B, it may be supported at its both end portions by sleeve bearings 42, the lower ends of which are supported by the lower frame 15, which in turn is supported by the receiving portions 53 formed on the image forming system.

Further, in the illustrated embodiment, the flange gear 9c of the photosensitive drum 9 meshes with the drive gear 41 for transmitting the driving force to the flange gear in such a manner that, as shown in Fig. 47, a line connecting a fulcrum of the flange gear 9c and a fulcrum of the drive gear 42 is offset from a vertical line passing through the fulcrum of the flange gear 9c in a counterclockwise direction by a small angle α; (about 10 in the illustrated embodiment), whereby a direction F of transmitting the driving force from the drive gear 41 to the flange gear 9c is upward. Although generally, the floating of the process cartridge by a downward force can be prevented by setting the angle α; is set to a value of 20 degrees or more, in the embodiment shown such an angle α; is set to approximately 1 degree.

By setting the above-described angle α to about 1 degree, when the upper opening/closing cover 19 is opened in a direction shown by the arrow j to remove the process cartridge B, the flange gear 9c is not blocked by the drive gear 41, and can therefore be smoothly disengaged from the drive gear 41. Further, when the direction F of the driving force transmission is directed upward as described above, the rotation axis 9f of the photosensitive drum is pushed upward and therefore tends to be disengaged from the drum support portion 33a. However, in the illustrated embodiment, since the overlap portion 33c is formed on the support portion 33a, the drum rotation axis 9f is not disengaged from the drum support portion 33a.

(Recycling)

The process cartridge having the structure described above enables recycling. It should be noted that the process cartridge(s) can be collected from the market and their parts can be reused to form a new process cartridge. Such recycling will now be explained. In the past, used up process cartridges were discarded or thrown away. However, the process cartridge B according to the illustrated embodiment can be collected from the market after the toner in the toner container has been used up in order to protect the earth's resources and the environment. Then, the collected process cartridge is disassembled into the upper and lower frames 14, 15, which are in turn cleaned. Thereafter, reusable parts and new parts are installed in the upper frame 14 or the lower frame 15 as required, and then new toner is again filled into the toner container 12a. In this way, a new process cartridge is obtained.

In particular, by releasing the connections between the locking claws 14a and the locking openings 15a, the locking claws 14a and the locking projections 15b, the locking claw 14c and the locking opening 15d, and the locking claw 15c and the locking opening 14b (Figs. 4, 8 and 9) which connect the upper and lower frames 14 and 15 to each other, the upper and lower frames 14, 15 can be easily separated from each other. Such disassembly operation can be easily performed, for example, by setting the used process cartridge B on a disassembly tool 42 and pushing the locking claw 14a by means of a push rod 42a as shown in Fig. 50. Even when the disassembly tool is not used, the process cartridge can be disassembled by pushing the locking claws 14a, 14c, 15c.

After the upper frame 14 and the lower frame 15 are separated from each other as described above (Figs. 8 and 9), the frames are cleaned by removing the toner waste adhering to them or remaining in the cartridge by an air jet method. In this case, a relatively large amount of toner waste remains adhering to the photosensitive drum 9, the developing sleeve 12d and/or the cleaning means 13 since they are in direct contact with the toner. On the other hand, the toner waste does not or almost does not adhere to the charger roller 10 since it is not in direct contact with the toner. Accordingly, the charger roller 10 can be cleaned more easily than the photosensitive drum 9, the developing sleeve 12d and the like. In this connection, according to the illustrated embodiment, since the charger roller 10 is mounted on the upper frame 14 and not on the lower frame 15 on which the photosensitive drum 9, the developing sleeve 12d and the cleaning sleeve 13 are mounted, the upper frame 14, which is separated from the lower frame 15, can be cleaned easily.

In the disassembling and cleaning line shown in Fig. 39B, first, the upper and lower frames 14, 15 are separated from each other as described above. Then, the upper frame 14 and the lower frame 15 are disassembled and cleaned independently of each other. Thereafter, as for the upper frame 14, the loader roller 10 is separated from the upper frame and cleaned; As for the lower frame 15, the photosensitive drum 9, the developing sleeve 12d, the developing blade 12e, the cleaning blade 13a and the like are separated from the lower frame and they are cleaned. Therefore, the disassembly and cleaning line is very simple.

After the toner is cleaned, as shown in Fig. 9, the opening 12a1 is again tightly closed by a new cover film 28, and new toner is replenished into the toner container 12a through the toner replenishing opening 12a3 formed in the side surface of the toner container 12a, and then the replenishing opening 12a3 is closed by the lid 12a2. Then, the upper frame 14 and the lower frame 15 are again connected to each other by making the connections between the locking claws 14a and the locking holes 15a, the locking claws 14a and the locking projection 15b, the locking claw 14c and the locking hole 15d, and the locking claw 15c and the locking hole 14b, whereby the process cartridge is again assembled into a usable state.

In this case, when the upper and lower frames 14, 15 are connected to each other, although the locking claws 14a and the locking holes 15a, the locking claws 14a and the locking projection 15b and the like are locked to each other, if the same process cartridge is recycled many times, there is a fear that the locking forces between the locking claws and the locking holes become weaker. To cope with this, in the illustrated embodiment, screw holes are formed in the frames near their four corners. It is to be noted that through-screw holes are formed in the fitting recesses 14d and in the fitting projections 14e of the upper frame 14 (Fig. 8) and in the fitting projections ise (to be fitted into the recesses 14b) and in the fitting recesses 15f (to be fitted onto the projections 14e) of the lower frame 15. Therefore, even if the Locking force due to the locking claws becomes weaker, after the upper and lower frames 14, 15 are connected to each other and the fitting projections and the fitting recesses are connected to each other, the upper and lower frames 14, 15 can be securely connected to each other by screwing screws into the screw holes.

Image formation process

Next, the image forming process performed by the image forming system A in which the process cartridge B is installed will be explained.

First, the original 2 is placed on the original glass platen 1a shown in Fig. 1. Then, when the copy start button A3 is depressed, the light source 1c1 is turned ON, and the original glass platen 1a is reciprocated on the image forming system in the left-right directions in Fig. 1 to optically read the information written on the original. On the other hand, in coordination with the reading of the original, the sheet feed roller 5a and the pair of register rollers 5c1, 5c2 are rotated to convey the recording medium 4 to the image forming station. The photosensitive drum 9 is rotated in the direction d in Fig. 1 in coordination with the timing of conveying the pair of register rollers 5c1, 5c2, and is uniformly charged by the charging means 10. Then, the light image read by the reading means 1 is projected onto the photosensitive drum 9 via the exposure means 11, thereby forming the latent image on the photosensitive drum 9.

At the same time when the latent image is formed, the developing agent 12 of the process cartridge 12b is activated to drive the toner supply mechanism 12b, thereby feeding the toner from the toner container 12a to the developing sleeve 12d outward, and the toner layer is formed on the rotatable developing sleeve 12d. Then, by applying a voltage to the developing sleeve 12d having the same charge polarity and potential as those of the photosensitive drum 9, the latent image on the photosensitive drum 9 is visualized as the toner image. In the illustrated embodiment, the voltage of about 1.2 KVVpp, 1590 Hz (square wave) is applied to the developing sleeve 12d. The recording medium 4 is conveyed between the photosensitive drum 9 and the transfer roller 6. By applying a voltage having the polarity opposite to that of the toner to the transfer roller 6, the toner image on the photosensitive drum 9 is transferred to the recording medium 4. In the illustrated embodiment, the transfer roller 6 is made of foam EPDM having a volume resistivity of about 10&sup9; Ωcm and an outer diameter of about 20 mm, and the voltage of -3.5 KV is applied to the transfer roller as the transfer voltage.

After the toner image is transferred to the recording medium, the photosensitive drum 9 continues to rotate in the direction d. In the meantime, the residual toner remaining on the photosensitive drum 9 is removed by the cleaning blade 13a, and the removed toner is collected in the waste toner container 13c via the squeegee blade 13b. On the other hand, the recording medium 4 onto which the toner image has been transferred is sent to the fixing means 7 by the conveying belt 5d, by permanently fixing the toner image on the recording medium 4 by heat and pressure. Then, the recording medium is ejected by the pair of ejection rollers Sf1, Sf2. Thereby, the information on the original is recorded on the recording medium.

Next, further design variants will be explained.

While in the first embodiment described above an example has been described in which the developing sheet 12e and the cleaning sheet 13a are Pins 24a, 24b are attached to the frame, as shown in Fig. 53, when the developing blade 12e and the cleaning blade 13a are attached to the lower frame 15, by pressingly inserting fitting projections 43a, 43b formed at both ends in the longitudinal direction of the developing blade 12e and the cleaning blade 13e into the corresponding fitting recesses 44a, 44b formed in the body 16 of the image forming system, pin holes 45 for receiving the pins for attaching the blades 12e, 13a may be formed in the vicinity of the fitting projections 43a, 43b, and corresponding pin holes 45 may be formed in the body 16 of the image forming system (instead of the fitting projections 43a, 43b studs or circular projections are used).

In this embodiment, if the fitting connections between the blades 12e, 13a and the lower frame are loosened by repeated recycling of the process cartridge B, then the blades 12e, 13a can be firmly attached to the lower frame by pins.

Furthermore, while in the first embodiment as shown in Fig. 29, an example has been given that the outer diameter D of the photosensitive drum 9 is smaller than the distance L between the drum guide members 25a, 25b to enable the photosensitive drum 9 to be finally attached to the lower frame 15, as shown in Fig. 54, even when the photosensitive drum 9 is accommodated in the upper frame 14, the outer diameter D of the photosensitive drum 9 may be smaller than the distance between the drum guide members 25a, 25b so that the photosensitive drum can be finally accommodated in the upper frame, thereby preventing the surface of the photosensitive drum 9 from being damaged, as in the first embodiment. In Fig. 54, elements or components having the same functions as those in the first embodiment are replaced by the same Furthermore, the upper and lower frames 14, 15 are connected to one another by connecting locking projections 47a and locking openings 47b and by their securing by pins 48.

Furthermore, as shown in Fig. 35, in the first embodiment, the photosensitive drum 9 and the developing sleeve 12d were supported by the bearing member 26, if the flange gear 12c is arranged at one end of the photosensitive drum 9 and the transfer roller gear 49 is arranged at the other end of the photosensitive drum, a structure as shown in Fig. 55 can be adopted. Here, in Fig. 55, too, elements having the same function as those in the first embodiment are designated by the same reference numerals.

Specifically, in Fig. 55, the flange gear 9c and the transfer roller gear 49 are bonded to both ends of the photosensitive drum 9 by an adhesive, a press fit or the like, or the positioning of the drum is performed by supporting a central projection 49a of the transfer roller gear 49 by the bearing portion 33a of the bearing member 26. In this case, in order to ground the photosensitive drum 9, a drum ground plate 50 having a central L-shaped contact portion is fixed to and in contact with the inner surface of the drum, and a drum ground axis 51 passing through a central hole in the transfer roller gear 49 is always in contact with the drum ground plate 50. The drum ground shaft 51 is made of a conductive metal such as stainless steel, and the drum ground plate 51 is also made of a conductive metal such as bronze phosphate, stainless steel or the like. When the process cartridge B is installed in the image forming system A, a head 52a of the drum ground shaft 51 is supported by the bearing member 26. In this case, the head 51a of the drum ground shaft 51 is in contact with the drum ground contact pin of the image forming system, the grounding of the photosensitive drum. In this case too, as in the first embodiment, the positional accuracy between the photosensitive drum 9 and the developing sleeve 12d can be improved by using the single bearing member 26.

Furthermore, the process cartridge B according to the present invention can be used not only to form a single color image as described above, but also to form a multi-color image (two-color image, three-color image or full-color image) by providing a plurality of developing means 12. Furthermore, the developing method can be of the known type of two-component magnetic brush development, cascade development type, touch-down development type or cloud development type. While in the first embodiment, the charging means was of the so-called contact charging type, in addition thereto, for example, another conventional charging method may be used in which three walls are formed by tungsten wires and metallic shields made of aluminum are provided on the three walls, and positive or negative ions generated by applying a high voltage to the tungsten wires are displaced to the photosensitive drum 9, thereby charging the surface of the photosensitive drum 9.

The contact charging may be, for example, of the blade type (charger blade), the pad type, the block type, the rod type or the wire type, such as the roller type mentioned above. Furthermore, the cleaning means for removing the residual toner remaining on the photosensitive drum 9 may be of the brush type or the magnetic brush type as well as the blade type.

Furthermore, the process cartridge B comprises an image-bearing member (for example, an electrophotographic photosensitive member) and at least two processing means. Therefore, as in the above-described construction, the process cartridge may integrally accommodate therein the image forming member and the charging means as a unit which can be removably mounted in the image forming system; or it may integrally accommodate therein the image forming member and the developing means as a unit which can be removably mounted in the image forming system; or it may integrally accommodate therein the image forming member and the cleaning means as a unit which can be removably mounted in the image forming system; or it may integrally accommodate therein the image forming member and two or more process means as a unit which can be removably mounted in the image forming system. It should be noted that the process cartridge integrally accommodates in its interior the charging means, the developing means or the cleaning means and the electrophotographic photosensitive member as a unit which can be removably mounted within the image forming system; or it integrally accommodates in its interior at least one of the charging means, the developing means and the cleaning means and the electrophotographic photosensitive member as a unit which can be removably mounted within the image forming system; or it integrally accommodates in its interior the developing means and the electrophotographic member as a unit which can be removably mounted within the image forming system.

Furthermore, while in the illustrated embodiment the image forming system was an electrophotographic copying machine, the present invention is not limited to the copying machine, but can also be applied to various other image forming systems such as a laser printer, a facsimile machine, a word processing device and the like.

The drive force transmission to the photosensitive drum 9 described above is now continued in will be described in greater detail. As shown in Fig. 56, the driving force from the driving motor 54 mounted on the image forming system body 16 is transmitted to a driving gear G6 via a gear chain G1-G5, and from the driving gear G6 to the flange gear 9c meshing with the driving gear, thereby rotating the photosensitive drum 9. Further, the driving force of the driving motor 54 is transmitted from the gear G4 to a gear chain G7-G11, thereby rotating the sheet feed roller 5a. Further, the driving force of the driving motor 54 is transmitted from the gear G1 to the driving roller 7a of the fixing means 7 via gears G12, G13.

Further, as shown in Figs. 57 and 58, the flange gear (first gear) 9c and the gear (second gear) 9i are integrally formed, and portions of the gears 9c, 9i protrude through an opening 159 formed in the lower frame 15. When the process cartridge B is installed in the image forming system A, as shown in Fig. 59, the drive gear G6 meshes with the flange gear 9c of the photosensitive drum 9, and the gear 9i integral with the gear 9c meshes with the gear 55 of the transfer roller 6; Here, in Fig. 59, the parts of the image forming system are shown by the solid lines, and the parts of the process cartridge are shown by the broken lines.

The number of teeth of the gear 9c is different from that of the gear 9i, so that the rotational speed of the developing sleeve 12d when the black image forming cartridge containing the magnetic toner is used is different from the rotational speed of the developing sleeve when the color image forming cartridge containing the non-magnetic toner is used. Note that when the black image forming cartridge containing the magnetic toner is installed in the image forming system as shown in Fig. 60A, the flange gear 9c meshes with the sleeve gear 12k of the developing sleeve 12d. On the other hand, when the Color image forming cartridge containing the non-magnetic toner is installed in the image forming system as shown in Fig. 60B, then the gear 9i meshes with the sleeve gear 12k of the developing sleeve 12d to rotate the developing sleeve.

As described above, since the gear 9c has a larger diameter and a larger width than the gear 9i, and has a larger number of teeth than the gear 9i, even if a larger force is applied to the gear 9c, the gear 9c can securely receive the driving force to securely rotate the photosensitive drum 9, and transmits the larger driving force to the magnetic toner developing sleeve 12d, thereby securely rotating the developing sleeve 12d.

As described above, according to the present invention, it is possible to provide a process cartridge and an image forming system which are capable of having such a process cartridge removably installed, whereby assemblability and disassemblability are significantly improved, and which are capable of being recycled to contribute to environmental protection.

Claims (11)

1. A process cartridge (B) to be removably mounted in a main body (A) of an electrophotographic image forming apparatus, the cartridge comprising: a lower frame (15); an upper frame (14) connected to the lower frame so as to be above the lower frame when the cartridge is mounted in the apparatus, the frames being separable from each other when the cartridge is removed from the apparatus; a rotatable electrophotographic photosensitive drum (9) mounted on the lower frame; charging means (10) for charging the drum; developing means (12) mounted on the lower frame for developing a latent image on the drum; a toner container (12a) provided in the upper frame for containing toner used by the developing means; and cleaning means (13) provided in the lower frame for cleaning the drum of the toner; characterized in that: the loading means comprises: a rotatable loading roller (10); means (10c, 10d) for mounting the loading roller on the upper frame to move it towards the drum; and means (10a) for biasing the loading roller towards the drum so that it rotates therewith. 2. Cartridge according to claim 1, wherein the frames are connected to each other by at least one hook member (14a, 15c) which is provided on at least one of the frames, which releasably engages in an opening (15a, 14c) or a projection (15b) on the other frame. 3. A cartridge according to claim 1 or 2, wherein the developing means comprises a developing sleeve (12d) for guiding the toner to a developing station, and a developing blade (12e) for regulating a thickness of the toner layer formed on a peripheral surface of the developing sleeve. 4. A cartridge according to any preceding claim, wherein the developing means comprises an elastic cleaning blade (13a) for removing the toner from the drum, and a toner waste collecting means (13c) for collecting the toner removed from the drum by the cleaning blade. 5. Cartridge according to one of the preceding claims, wherein an opening of the toner container (12a) is closed by a removable seal (27), and wherein the toner in the toner container can be fed to a development station after removal of the seal. 6. A cartridge according to any preceding claim, wherein a regulating projection (lsi) for regulating a change in the position of the cartridge in the image forming device is arranged in the vicinity of a recording sheet guide portion (15h₁, 15h₂) of the lower frame. 7. An electrophotographic image forming apparatus, comprising a main body (A), a cartridge as claimed in any preceding claim removably mounted in the main body, and means (5) for feeding a recording medium past the drum. 8. Apparatus according to claim 7, in the form of an electrophotographic copying machine. 9. Apparatus according to claim 7, in the form of a laser printer. 10. Device according to claim 7, in the form of a fax machine. 11. A method for recycling a cartridge as claimed in any one of claims 1 to 6, comprising the steps of separating the upper and lower frames, cleaning and/or replacing the parts of the cartridge, refilling the toner container and assembling the parts.