JPH04350671A - Process cartridge for image forming device - Google Patents

Abstract

PURPOSE:To obtain such structure that the interval of a developing area between the electrostatic latent image forming surface of a belt-like image carrier and the surface of a developer carrier is precisely and easily secured, to stably form an image and to improve and stabilize assembling accuracy as for the process cartridge of an image forming device obtained by integrally molding the structure of the housing of the process cartridge, which is obtained by unitizing the belt-like image carrier which is turnably held and on which an electrostatic latent image is formed and plural developing devices which form a toner image by developing the electrostatic latent image on the image carrier, by resin and which can be loaded and unloaded in the device main body. CONSTITUTION:By inserting both shaft ends of the turnable developer carrier 21 which has a magnet body in the inside and which carries developer on the surface in the inside diameter parts of respective bearing members provided on both side walls of the housing of the process cartridge, turnably supporting it and making both end parts of a gap holding member 28, which is made to press-contact with the inside of the belt-like image carrier 21 and which is disposed at a position where it is faced to the developer carrier, abut on the outside diameter part of the respective bearing members 274 in the plural developing devices, the gap between the surface of the image carrier and the surface of the developer carrier is kept constant.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to an electrostatic recording type image forming apparatus such as an electrophotographic copying machine or a printer, and in particular, it relates to an image forming apparatus such as an electrostatic recording type electrophotographic copying machine or a printer, and more particularly, it relates to an image forming apparatus such as an electrostatic recording type electrophotographic copying machine or a printer. The present invention relates to a process cartridge of an image forming apparatus that can be replaced by a process cartridge that can be installed and removed.

0002

2. Description of the Related Art As image forming apparatuses such as printers and copying machines have become more compact, lighter, and more functional, they have become more dense and complex.

[0003] On the other hand, in order to allow operators, who are general users, to easily perform maintenance and management, image forming apparatuses having a process cartridge in which an image bearing member and at least one means of image forming means such as a developing means and a cleaning means are integrated into a unit. A forming device was developed. In image forming apparatuses such as printers and copying machines equipped with this process cartridge, when the image bearing member inside the process cartridge becomes worn out or deteriorated, the process cartridge itself can be replaced, allowing operators without specialized knowledge to image the image by themselves. This makes it possible to easily maintain and manage the forming device. To this end, a guide member for the process cartridge is provided in the main body of the apparatus, and the process cartridge can be loaded by simply inserting the process cartridge along this guide member so as to obtain an optimal image.

The developing device installed in the process cartridge has a fixedly arranged magnet body (magnetic roller) having a plurality of magnetic poles, and has the magnet body inside, carries developer on its surface, and is driven and rotated. a developer carrying member (developing sleeve), a developer amount regulating member (briefing regulation member) supported on the developer carrying member and regulating the amount of developer, and supplying the developer to the developer carrying member. The developer supplying member (developer supplying screw) supplies and stirs the developer to the supplying member, and the developer stirring member (toner transporting screw) supplies and stirs the developer to the supplying member.

installed in the process cartridge,
Belt-shaped image carrier (photoreceptor belt) that carries an electrostatic latent image
is stretched between a driving roller and a driven roller, and is rotatably supported under tension by a belt tension plate (spacing member).

[0006] The spacing member is installed at a position facing the developing sleeve via the photosensitive belt, and positions and supports the photosensitive belt surface and the developing sleeve at a predetermined minute gap.

Further, a process cartridge used in a color image forming apparatus includes a plurality of developing devices, each of which contains color developers of different colors, such as yellow, magenta, cyan, and black. A color image is formed using toner.

Each member such as a plurality of developing sleeves, a magnet roll, a toner conveying screw, a developer supplying screw, etc. is positioned and arranged in each developing unit of the process cartridge, and is driven by a driving source of the apparatus main body via a transmission means. be rotated. The rotatable photoreceptor belt and the plurality of developing devices are positioned and fixed at predetermined minute gaps.

[0009]

Strict precision is required for the gap size of the developing area where the photosensitive belt and each developing device are disposed facing each other. For this reason, the holding structure of the spacing member that backs up the photoreceptor belt and the developing sleeve becomes complicated, resulting in difficulty in assembly and adjustment, high manufacturing costs, and
There are problems with long-term accuracy stability, etc.

0010

[Means for Solving the Problems] It is an object of the present invention to improve the process cartridge of an image forming apparatus which has the above-mentioned problem, and it is an object of the present invention to provide a simple structure for holding and positioning the photoreceptor belt and the developing sleeve. The object of the present invention is to provide a configuration that can be assembled accurately, easily, and quickly, and can stabilize the gap accuracy in the developing area over a long period of time, thereby solving the above-mentioned problems.

A process cartridge of an image forming apparatus according to the present invention that achieves the above object includes a belt-like image carrier that is rotatably held and on which an electrostatic latent image is formed, and a belt-like image carrier that is rotatably held and on which an electrostatic latent image is formed. In the process cartridge of an image forming apparatus, the housing of the process cartridge is formed into a unit with a plurality of developing devices that develop a toner image to form a toner image, and the casing of the process cartridge is made into an integrated resin molded structure and can be inserted into and removed from the main body of the apparatus. In each of the plurality of developing units, both shaft ends of a rotatable developer carrier having the magnetic body therein and carrying developer on its surface are connected to each other provided on both side walls of the housing of the process cartridge. It is fitted into the inner diameter part of the bearing member and rotatably supported, and is disposed on the outer diameter part of each of the bearing members in pressure contact with the inner side of the belt-shaped image carrier and at a position facing the developer carrier. The present invention is characterized in that the distance between the surface of the image carrier and the surface of the developer carrier is maintained constant by bringing both ends of the provided spacing member into contact with each other.

[0012] Furthermore, the spacing member is characterized in that at least a portion that abuts the bearing member is formed of an insulating member.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a main sectional view of a color printer to which the present invention is applied, viewed from the left side. The apparatus main body 10 is surrounded by an operation panel 11, an openable and closable upper cover 12, a toner supply cover 13, a front cover 14, etc. on the front side, and inside the opening of the apparatus main body 10 is a removable process cartridge 20. Paper cassette 30
is provided.

The process cartridge 20 includes an image carrier,
It consists of a developing means, a charging means, a cleaning device, etc.

The photosensitive belt 21, which is an image carrier, has a photosensitive layer such as an organic photoconductive layer (OPC) coated on the surface of a flexible belt, and includes a driving roller 22A and a driven roller 22B.
and rotated clockwise.

Around the photoreceptor belt 21, charging means,
An exposure means, a development means, a transfer means, and a cleaning device are provided.

The charging means is an existing charger 24 such as a corona charger or a scorotron charger.

The developing means uses different color developers, such as yellow, magenta, cyan, and black color toners (
A plurality of developing units 23a and 2 each containing a developer (developing agent).
3b, 23c, and 23d. Each of these developing devices 23a~
23d has a function of developing an electrostatic latent image on the photoreceptor belt 21 into a toner image using a non-contact development method.

The cleaning blade 251 of the cleaning device 25 is kept at a position apart from the surface of the photoreceptor belt 21 during the image forming process, and is pressed against the surface of the photoreceptor belt 21 only during cleaning after transferring the toner image to the transfer material P. The photoreceptor belt 21 is then cleaned.

The toner collection box 26 collects and stores the residual toner on the photoreceptor belt 21 that has been removed by the cleaning device 25.

In this embodiment, the photoreceptor belt 21, charger 24, and
Each process section of the developing devices 23a to 23d containing toner of each color, the cleaning device 25, and the toner collection box 252 is housed in the integrated process cartridge 20 to form a unit, and can be attached to and detached from the apparatus main body 10 all at once. Can be done.

On the other hand, on the main body side of the image forming apparatus, when the process cartridge 20 is installed and the image formation is possible, an exposing means, a transferring means, etc. are arranged around the photosensitive belt 21.

The exposure means is a semiconductor laser writing optical system unit (hereinafter referred to as optical system unit) 40, which exposes the surface of the photoreceptor belt 21 charged by the charger 24 to form a charged latent image.

The transfer means 50 transfers the toner image formed on the photosensitive belt 21 onto the transfer material P using the transfer drum 51 and the transfer device 54.

The process of forming a color image using the color image forming apparatus having the above configuration is performed as follows.

First, the process cartridge 20 is loaded in a predetermined position within the image forming apparatus main body 10, and is ready for image formation. When a first color image signal output from an image reading device separate from the main body 10 of the apparatus is input to the optical system unit 40, a laser beam is generated by a semiconductor laser in the optical system unit 40. . The laser beam is rotated and scanned by a polygon mirror 42 rotated by a drive motor 41,
The light is projected through the cylindrical lens 43, the fθ lens 44, and the mirrors 45 and 46 onto the circumferential surface of the photoreceptor belt 21, which has been uniformly charged to a predetermined charge by the charger 24, to form a bright line.

On the other hand, regarding the sub-scanning direction, a belt index (not shown) corresponding to a specific position of the photoreceptor belt 21 is detected, or a print command signal is received, and this detection or command signal is used as a reference. Then, the main scanning line where modulation of the semiconductor laser by the image signal is started is determined. When scanning is started, in the main scanning direction, a laser beam is detected by an index sensor (not shown), and based on this detected signal, a semiconductor laser beam based on an image signal of the first color is directed to the photoreceptor belt. Scan over the surface of 21.

Therefore, a latent image corresponding to the first color is formed on the uniformly charged surface of the photoreceptor belt 21 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photoreceptor belt 21. This latent image is developed by a developing device 23a containing yellow toner corresponding to the first color among the developing means, and a yellow toner image is formed on the surface of the photoreceptor belt 21.

Thereafter, the photoreceptor belt 21 is rotated while holding the yellow toner image on its surface.
After passing under the cleaning blade 251 which is spaced apart from the surface of the image forming apparatus, the second color image formation begins.

That is, the photoreceptor belt 21 on which the yellow toner image has been formed is uniformly charged again by the charger 24, and then the image signal of the second color is transferred to the optical system unit 4.
0, and as in the case of the first color image signal described above, writing is performed on the surface of the photoreceptor belt 21 to form a latent image. The latent image is developed by a developer 23b containing magenta toner as the second color. A magenta toner image is formed in the presence of a previously formed yellow toner image.

Similarly, after forming a latent image using the third color image signal, a cyan toner image is formed in the developing device 23c containing cyan toner, and furthermore, after forming a latent image using the fourth color image signal, a black toner image is formed. A color toner image is formed on the surface of the photoreceptor belt 21 by superimposing a black toner image on the surface of the photoreceptor belt 21 using a developing device 23d containing toner.

A direct current or even an alternating current bias is applied to the developing sleeves 231a to 231d (see FIG. 2) of each of the developing units 23a to 23d, and reverse development is performed without contact with the photoreceptor belt 21 whose base is grounded. is now being carried out. Incidentally, for this non-contact development, either a two-component developer or a one-component developer can be used. When using a one-component developer, there is no need to provide a toner hopper separate from the developing section, allowing for downsizing, but a development method using a two-component developer is superior in terms of development stability. Therefore, it is preferable in terms of color reproduction.

As described above, the color toner image formed on the surface of the photoreceptor belt 21 is transferred to a transfer material P that is supplied from a paper feed cassette 30 by a paper feed roller 31 and is timed with the color toner image by a timing roller 32. transcribed into. The transfer device 50 performs transfer by applying a high-voltage power output having a polarity opposite to that of the toner.

The transfer material P onto which the color toner image has been transferred in this way moves sharply (small diameter curvature) along the drive roller 22A.
They are reliably separated by the photoreceptor belt 21 which changes direction, and are conveyed upward by a conveyor belt 60 having a built-in suction means 61.

After the toner is melted and fixed on the transfer material P by heat and pressure contact between the fixing roller 71 and the pressure roller 72 of the fixing device 70, the transfer material P is transferred to the upper surface of the upper cover 12, which also serves as a paper ejection tray, by the paper ejection roller 73. be discharged.

FIG. 2 is a side sectional view of the process cartridge 20, and FIG. 3 is an enlarged sectional view of a main part of one developing device representative of the plurality of developing devices in the process cartridge.

The process cartridge 20 includes a developing device 23
a, 23b, 23c, 23d, a charger 24, a cleaning device 25, etc., and a drive roller 22 that rotates the photoreceptor belt (image carrier) 21 above it.
A, driven roller 22B, and spacing member 28a
, 28b, 28c, 28d, and an upper unit consisting of a back plate 28e, etc., and has a structure that can be separated and combined.

Near the bottom of the housing 27 of the lower unit are a plurality of developing units 23a, 23b, 23c, 2.
The 3d casing is a developer tank formed into a concave shape. Inside each of these developing tanks, there is a developing sleeve (developer carrier) 2.
3la, 23lb, 23lc, 23ld, and toner conveying screws (developer stirring members) 232a, 232b, 2
32c, 232d, and developer supply screws (developer supply members) 233a, 233b, 233c, 233d are rotatably mounted on both side surfaces of the housing 27.

[0040] The developing devices 23a, 23b, 23c, 23
d all have similar structures, and one representative developing device (23) will be described with reference to FIG.

[0041] The developer sleeve 23l can be driven and rotated.
A magnet body (magnet roller) 236 having a plurality of magnetic poles is fixedly arranged on both side surfaces of the housing 27 inside the housing 27 concentrically. The magnet body 236 is attached to the photoreceptor belt 21
It consists of a main magnetic pole N0 that faces the main magnetic pole N0, and a plurality of sub magnetic poles N and S (for example, six in the figure).

Toner transport screw 23 in developing device 23
2 and the developer supply screw 233, a non-magnetic partition plate 234 is fixed. A peeling member (scraper) 235 is attached to the partition plate 234,
The tip thereof is in light pressure contact with the cylindrical surface of the developing sleeve 231. Note that 237 is a shielding plate for preventing toner scattering.

In the vicinity of the developing sleeve 231, a magnetic and rigid thin layer forming rod 29 is supported by a holder 291 and pressed by an elastic member 292 to come into pressure contact with the developing sleeve 231, thereby forming a developer layer regulating means. It consists of

The developing sleeve 231 and the photosensitive belt 2
The gap δ between the developing sleeve 231 and the photoreceptor belt 2 is such that a bearing member (described later) 274 coaxially provided at the shaft end of the developing sleeve 231
By coming into contact with the spacing member 28 that slides on the spacer 1, a constant gap of around 0.5 mm is maintained at all times.

Here, E is a developing area 23 formed between the photoreceptor belt 21 and the developing sleeve 231.
8 is an AC bias power supply in which DC voltage and AC voltage are superimposed.

The toner supplied from the toner storage device (toner hopper) is sent to a toner conveying screw 232, and is further stored in a developing tank in advance by a developer stirring screw 233 that rotates in opposite directions. After being sufficiently stirred and mixed with a two-component developer D consisting of a magnetic carrier and a toner, it is sent to the developing sleeve 231. A magnet roller 236 having a fixed magnetic pole is disposed inside the rotating developing sleeve 231, and the developing roller 230 consisting of the rotating developing sleeve 231 and the magnetic roller 236 allows the developer D to be developed It is deposited in a layered manner on the sleeve 231, is conveyed in the direction of the arrow, passes through the pressing position of the thin layer forming rod 29, and forms a predetermined thin layer.

After that, the development of the electrostatic latent image on the development area E is completed, and the remaining developer D on the development sleeve 231 is returned to the housing 27 of the development device 23.
When reaching a non-magnetic field area, that is, a position where the magnetic flux density is almost zero and where the developer D can fall under its own weight, the developer D is scraped off from the circumferential surface of the developing sleeve 231 by the scraper 235, and then the developer D is scraped off by the screw 232 again. , 233, and are uniformly stirred and dispersed onto the developing sleeve 231.
Development is performed continuously.

FIG. 4 shows a longitudinal sectional view of the process cartridge 20.

A drive roller 22A is provided on the side surface of the process cartridge 20 to rotate the photoreceptor belt 21.
A drive gear G14 connected to is provided. The drive gear G14 is connected to a drive motor (not shown) in the device main body 10 via a gear train that can be moved into and out of contact with the drive gear G14. Further, another drive motor in the apparatus main body 10 is connected to a drive gear G28 fixed to the shaft end of the toner conveying screw 232 of the developing device 23 and the developer supply screw 233 via a gear train (not shown). Transmit power. At the same time, the developing sleeve 231 driving gear G29, the waste toner screw driving gear, etc. are driven and rotated.

On the right side of the casing 27 of the process cartridge 20, shaft ends of the drive shafts of the plurality of developing devices 23a to 23d protrude outward from the respective bearings, and the drive gear group is fitted therein. There is.

The leading end of the drive shaft is fitted into and supported by a bearing provided on a support plate 26B common to each developing device. The drive support plate 26B is fixed to the side wall of the housing 27.

That is, one shaft end (on the right side in the figure) of the developer supply member screws (a to d) having the gear G28 is connected to each bearing 271 provided in the housing 27 and the support plate 2.
It is fitted into each bearing 272 provided in 6B and is rotatably supported. Further, the developer supply screw 233 (a
The other shaft ends (on the left side in the figure) of -d) are fitted into respective bearings 273 provided in the housing 27 and are rotatably supported.

Both shaft ends of the toner conveying screw 232 are also
Similarly to the above, both ends are supported by bearings, making it rotatable.

FIG. 5 is an enlarged sectional view of the developing rollers 230 (a to 230d), and FIG. 6 is a perspective view thereof.

Both left and right shaft ends (flange portions) 231A and 231B of the developing sleeve 231 have a protruding hollow pipe shape, and the outer diameter portions thereof are fixed in through holes in both side walls of the developer housing 27. The bearing members 274A and 274B (for example, rolling bearings such as ball bearings) are fitted into the inner diameter portions and are rotatably supported horizontally. Note that the right shaft end 2
The gear G29 is fixed to the outer diameter portion near the rightmost end of 31B, and the driving force is transmitted thereto.

Both shaft ends 236A and 236B of the magnet roller 236 included in the developing sleeve 231 are as follows:
Both shaft ends 231A, 231B of the developing sleeve 231
The magnetic roller 23 penetrates the hollow portion and is fitted into and supported by holes bored in left and right support plates 26A and 26B fixed to both side walls of the developer housing 27, respectively.
The cylindrical portion 6 is positioned and fixed concentrically with the cylindrical portion of the developing sleeve 231 .

The tip of one shaft end 236A of the magnet roller 236 has a shape for locking rotation in the circumferential direction, such as a two-sided cut (oval shape) on the shaft cylindrical surface, or a prismatic shape. The shape, key groove shape, etc. have been processed. This locking shape is formed to match the circumferential position of the main magnetic pole N0 of the magnet roller 236 (
(See Figure 3).

The hole portion of the support plate 26A that penetrates the shaft end portion 236A has the same shape as the locking shape of the shaft end portion 236A, and is closely fitted to the center position and circle of the magnet roller 236. Determines the circumferential direction.

At one end of the outer circumferential surface of the bearing members 274A, 274B, both end members 2 of the spacing member 28 are attached.
81A and 281B are pressed against each other by a spring (not shown).

Both end members 281A of the spacing member 28
, 281B has a concave cylindrical surface shape, is formed to have the same curvature as the outer diameter portion (diameter D1) of the bearing members 274A, 274B, and is spring-biased so as to straddle the outer diameter portion. Supported. Further, the lower end surface of the central member 282 of the spacing member 28 has a convex curved surface, and forms a predetermined minute gap (
δ+t) to form a development area E. Here, t is the thickness of the photoreceptor belt 21, and δ is the thickness of the photoreceptor belt 21.
The distance between the developing area E between the electrostatic latent image bearing surface of No. 1 and the circumferential surface of the developing sleeve 231 is shown.

That is, the bearing members 274A, 274B, the shaft end 231A of the developing sleeve 231, Each dimension of 231B is determined.

Furthermore, the radius of curvature of both end members 281A and 281B constituting the spacing member 28, and the radius of curvature of the center member 28
Even if the radius of curvature of No. 2 is not the same size, as long as the developing area interval δ is set so as to satisfy the above equation, the radius of curvature may be changed to provide a step on both curved surfaces.

Both end members 281A of the spacing member 28
, 281B are made of an insulating material such as resin. The developing sleeve 231 and its shaft ends 231A, 231
B is conductive, and the AC bias power supply 238
It is electrically connected to metal bearing members 274A and 274B made of ball bearings and the like. On the other hand, the conductive layer on the surface of the photoreceptor belt 21 is electrically grounded via a conductive member (not shown). Therefore, the bearing member 2 is electrically connected to the photoreceptor belt 21 and the developing sleeve 231.
74A and 274B refer to the above-mentioned both end members 231A and 281B.
is maintained in an insulated state by Note that the intermediate member 28
2 may be formed integrally or separately from an insulating material such as resin, but in order to obtain strength from the elongated member and to ensure a uniform development area interval δ with high accuracy, aluminum in the shape with reinforcing ribs is used. Metal materials such as alloys may also be used.

In this embodiment, as an image forming process, an image forming method was described in which a color toner image is formed on a belt-shaped image carrier (photoreceptor belt) and then transferred to a transfer material in one step. Alternatively, a color imaging method may be used in which toner images are transferred onto a transfer material on a transfer drum in an overlapping manner. Also,
It is also applicable to ordinary monochrome printers using monochrome processes. Furthermore, although the non-contact development method has been described as a developing method, the present invention is not limited to this non-contact development, but can also be applied to contact development. Furthermore, the present invention is also applicable to a developing device that uses a one-component developer in addition to a two-component developer.

[0065]

Effects of the Invention As described in detail above, the process cartridge of the image forming apparatus of the present invention allows the interval between the developing areas between the developer carrier and the belt-like image carrier to be maintained accurately through the interval retaining member and the bearing member. This ensures stable image formation.

In addition, the structure is simple, the positioning accuracy is improved, and the assembly of the above-mentioned members does not require troublesome adjustments, making it easy to assemble.
Since the work can be done accurately and quickly, it is extremely effective in reducing manufacturing costs. Furthermore, the above-mentioned development area interval has an excellent effect on long-term precision stability.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a multicolor image forming apparatus equipped with a developing device according to the present invention.

FIG. 2 is a side sectional view of a process cartridge of the multicolor image forming apparatus.

FIG. 3 is an enlarged sectional view of main parts of a developing device according to the present invention.

FIG. 4 is a longitudinal sectional view of the process cartridge.

FIG. 5 is a sectional view of a developer carrier and a spacing member.

FIG. 6 is a perspective view of the developer carrier and the spacing member.

[Explanation of symbols] 10...Device body
20... Process cartridge 21... Photoreceptor belt (belt-shaped image carrier) 23a, 23
b, 23c, 23d...Developer (developing device) 230 (23
0a, 230b, 230c, 230d)...Developing roller 2
31 (231a, 231b, 231c, 231d)...Developer carrier (developing sleeve) 231A, 231B...Shaft end portion 232 (232a, 232b, 232c, 232d)...
Developer stirring member (toner transport screw) 233 (233a, 233b, 233c, 233d)...
Developer supply member (developer supply screw) 236 (236a, 236b, 236c, 236d)...
Magnet body (magnet roller) 236A, 236B...Shaft end
238... AC bias power supply 26A (a to d), 26B (a to d)... Support plate 27... Developing device casing (housing) 274A, 2
74B... Bearing member 28 (28a, 28b, 28c, 28d)... Spacing member 281A, 281B... Both end members
282...Central member D1...Outer diameter of bearing member D2...Outer diameter t of developer carrier...Thickness of image carrier
δ…Development area interval

Claims (2)

[Claims] Claims: 1. A belt-shaped image carrier that is rotatably held and on which an electrostatic latent image is formed; a plurality of developing devices that develop the electrostatic latent image on the image carrier to form a toner image; In the process cartridge of an image forming apparatus, the housing of the process cartridge is made into a resin molded integral structure and can be inserted into and removed from the main body of the apparatus. Both shaft ends of a rotatable developer carrier carrying developer on its surface are fitted into inner diameter portions of respective bearing members provided on both side walls of the casing of the process cartridge, and are rotatably supported. and bringing into contact with the outer diameter portion of each of the bearing members, both ends of a spacing member that is in pressure contact with the inner side of the belt-like image carrier and is disposed at a position facing the developer carrier. A process cartridge for an image forming apparatus, wherein the distance between the surface of the image carrier and the surface of the developer carrier is maintained constant. 2. The process cartridge for an image forming apparatus according to claim 1, wherein at least a portion of the spacing member that contacts the bearing member is formed of an insulating member.