JP2000098829A - Process cartridge and electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from soiling an image forming device main body side by a processing cartridge provided with a magnetic brush electrifier. SOLUTION: In this process cartridge B, an exposure opening part 53 is closed with a light transmission member 51, or further, electrodes is disposed 52. The scattering toner from the magnetic brush electrifier 32 and a developing device 5 is respectively prevented from proceeding to an exposure source 50 on the image forming device main body side. Therefor, the exposure source 50 is prevented from toner soiling even when a photoreceptor drum 1 and the exposure source 50 are brought close the each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image in which a process cartridge is detachable and an electrostatic latent image formed on an image carrier corresponding to an image to be recorded is developed with a developer and recorded on paper or the like. The present invention relates to a forming apparatus and a process cartridge.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a process cartridge having an integrated unit structure in which a consumable component can be detached from a main body is used in view of simplification of configuration, life of consumable component, and cost. . Usually, the process cartridge includes a photoconductor, a charging unit, a developing unit, and the like, and is replaced with a proper life.

FIG. 3 shows a cross section of a process cartridge. The process cartridge includes a photosensitive drum 1 as an image carrier that is driven to rotate in a direction indicated by an arrow in FIG.
A charging blade 2 as a contact charging unit, a developing device 5 and a cleaning device 4 are disposed around the housing 5.
a, and is detachably mounted on an image forming apparatus main body (not shown). Exposure means for forming a latent image is disposed on the image forming apparatus main body side,
The exposure means exposes the photosensitive drum 1 through the exposure opening 9. The developer scattered from the developing device 5 and the cleaning device 4 of the process cartridge may contaminate the exposure unit through the exposure opening 9. If the exposure means is contaminated with a developer or the like, the amount of light cannot be reduced to form a clear electrostatic latent image, so that it is necessary to clean the exposure means.

[0004]

However, the cleaning of the above-mentioned exposure means requires a single simple cleaning member, and the cleaning member itself is immediately soiled, and the cleaning effect is impaired even if it is used repeatedly. In particular, when a cleaner-less process using a contact magnetic brush charging device is adopted, transfer residual toner mixed into the magnetic brush charging device scatters in the same manner as the developing device, and the chance of contaminating the inside of the device, especially the exposure means, is more than before. Therefore, a device for preventing contamination is required for both the developing device and the charging device so as not to be scattered. However, a container for collecting the developer and the like removed by cleaning and a member for further cleaning the cleaning member itself complicate the configuration and increase the cost. In addition, especially when the exposure means is an LED array writer head, the light emitting portion itself is very close to the photoreceptor, so that there are many restrictions on the arrangement and shape of the cleaning means, and the cleaning work is essentially unnecessary. Is desirable.

The present invention relates to a process cartridge and an electrophotographic image forming apparatus for preventing a member on the image forming apparatus main body having a longer life than a process cartridge from being contaminated by toner scattered from a developing device or a contact charging device without using a cleaning means. It is intended to provide a device. In particular, it is an object of the present invention to provide a process cartridge and an electrophotographic image forming apparatus which can easily and simultaneously prevent contamination caused by toner scattered from a developing device or a contact charging device.

[0006]

The main aspects of the present invention are as described below with reference to the claims.

According to a first aspect of the present invention, there is provided a process cartridge detachably mountable to an image forming apparatus main body, wherein an electrophotographic photosensitive member, a process means acting on the electrophotographic photosensitive member, and a constituent member on the image forming apparatus main body side are processed. A contamination preventing means for preventing contamination by scattered developer generated in the cartridge.

According to a ninth aspect of the present invention, there is provided an electrophotographic image forming apparatus for forming an image on a recording medium by detachably attaching a process cartridge, comprising: a. A process cartridge comprising: an electrophotographic photosensitive member; a process unit acting on the electrophotographic photosensitive member; and a contamination preventing unit for preventing a constituent member of the image forming apparatus main body from being contaminated by scattered developer generated in the process cartridge. Mounting means for removably mounting; b. The image forming apparatus main body side constituent member; c. An electrophotographic image forming apparatus, comprising: a conveying unit for conveying the recording medium.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. A laser beam printer will be described as an embodiment of the electrophotographic image forming apparatus.

In the following description, the longitudinal direction refers to a direction crossing the transport direction of the recording medium and parallel to the surface of the recording medium.

(Overall Configuration) This electrophotographic image forming apparatus A
As shown in FIG. 1, a light beam based on image information obtained by reading a document such as a book G placed on a document table 10a by an optical system 10 serving as a document reading device is transmitted from a LED array writer head 50 to a drum. A latent image is formed on the photosensitive drum 1 by irradiating the photosensitive drum 1, which is an electrophotographic photosensitive member having a shape,
The latent image is developed with a developer (hereinafter, referred to as “toner”) to form a toner image. Synchronously with the formation of the toner image, the sheet P is separated and fed one by one from a sheet feeding cassette 20a containing the recording material P by a pickup roller 20b, conveyed by a pair of registration rollers 20e, and formed into a cartridge as a process cartridge B. The toner image formed on the electrophotographic photosensitive member is transferred to a recording material P by applying a voltage to a transfer device 7 as a transfer unit, and the recording material P is conveyed to a fixing unit 6 by a conveyance belt 20f. The fixing unit 6 includes a driving roller 6a and a fixing roller 6c that is rotatably supported with a built-in heater 6b, and applies heat and pressure to the recording material P passing therethrough to fix the transferred toner image. The recording material P is transported by a pair of discharge rollers 20 g and discharged to a discharge unit 21.

(Process Cartridge) On the other hand, the process cartridge B is provided with an electrophotographic photosensitive member and at least one process means as shown in FIG. Here, as the process means, for example, a charging means for charging an electrophotographic photosensitive member, a developing means for developing a latent image formed on the electrophotographic photosensitive member, a cleaning means for cleaning toner remaining on the surface of the electrophotographic photosensitive member Etc. As shown in FIG. 4, the process cartridge B of the present embodiment rotates the photosensitive drum 1, which is an electrophotographic photosensitive member having a photosensitive layer, and applies a voltage to a magnetic brush charger 32, which is a charging unit, to apply the photosensitive drum. The surface of the drum 1 is uniformly charged, and a light image from the optical system 10 is exposed to the charged photosensitive drum 1 through an exposure opening 53 through an LED array writer head 50 to form a latent image. The developing device 5 forms the latent image and develops the latent image.

After applying a voltage having a polarity opposite to that of the toner image to the transfer device 7 to transfer the toner image to the recording material P,
The photosensitive drum 1 is provided in the charging device container 3 and rotates in the same direction as the photosensitive drum 1 at a small interval from the photosensitive drum 1 (photosensitive drum 1
The peripheral surface moves in the opposite direction.) The residual toner on the photosensitive drum 1 is removed by a magnetic brush charger 32.

(Removable Configuration of Process Cartridge) Next, a configuration for mounting and removing the process cartridge B from the image forming apparatus A will be described. As shown in FIGS. 5 and 6, an opening / closing member 25 for opening and closing a space entrance which is a cartridge mounting portion 26 of the apparatus main body 19 is attached to the apparatus main body 19 with a fulcrum shaft 25a. As shown in FIGS. 5 and 6, the process cartridge B is attached and detached as shown in FIGS.
Open 5 and perform. Spaced cartridge mounting part 2
As shown in FIG. 6, when the opening / closing member 25 is opened, guide rails 27 linearly formed in the front-rear direction of the apparatus main body 19 are provided substantially symmetrically at the lower corners on both right and left sides. The process cartridge B is transported between the entrance of the cartridge mounting portion 26 and the back side of the cartridge mounting portion 26 by fitting the cartridge B.

As described above, when the process cartridge B is mounted on the apparatus main body 19, the LED array writer head 50 is disposed in parallel with and close to the photosensitive drum 1. After the mounting, the opening / closing member 25 is closed.

In order to remove the process cartridge B, the opening / closing member 25 is opened and the process cartridge B is pulled out from the cartridge mounting portion 26 in the reverse of the above.

In recent years, an image forming apparatus that develops an electrostatic latent image formed on an image carrier corresponding to an image to be recorded with a developer and records the image on paper or the like has been reduced in size. There is a limit to the size of each of the members that perform the steps of exposure, development, transfer, fixing, and cleaning. Further, the transfer residual toner described above is collected as waste toner by the cleaning unit. However, it is preferable that this waste toner is not present in terms of environmental protection. Therefore, a cleaner-less device has been developed in which the above-mentioned cleaning means is removed and cleaning is performed simultaneously with development by a developing device.
The cleaning at the same time as the development is a method in which the toner slightly remaining on the photosensitive drum after the transfer is recovered by a fogging bias at the time of the development after the next step. According to this method, since the transfer residual toner is collected and used in the subsequent steps, the waste toner can be eliminated, and the trouble of maintenance can be reduced. In addition, there is a great advantage in terms of space, and the size can be significantly reduced.

Further, since it has advantages such as low ozone and low electric power, a contact charging device as a uniform charging member of the above-mentioned photosensitive drum, that is, a charging member to which a voltage is applied is brought into contact with a member to be charged to be charged. 2. Description of the Related Art Apparatuses for charging a body have been put to practical use.

As the charging member of this type, a magnetic brush type device is preferably used in terms of stability of charging contact.

In this embodiment, the cleanerless system as described above is employed, and a magnetic brush charging system is used as a charger. The magnetic brush charger 32 used in the present embodiment is a rotatable non-magnetic sleeve 32a having an outer diameter of 16 mm and having a fixed magnet 32b provided therein.
Above, magnetic particles are formed in a brush shape by a magnetic field,
The magnetic particles are transported as the non-magnetic sleeve 32a rotates. Further, the non-magnetic sleeve 32a rotates in the direction in which the peripheral surface moves in the counter direction with respect to the photosensitive drum 1. In the present embodiment, the magnetic brush charger is used for the rotation speed of the photosensitive drum 1 of 100 mm / sec. 32 is 1
It is rotating at 50 mm / sec. Non-magnetic sleeve 3
By applying a charging voltage to 2a, a charge is given from the magnetic particles onto the photosensitive drum 1, and charged to a potential corresponding to the charging voltage. The higher the rotation speed, the better the charging uniformity tends to be.

The magnetic carrier used as the charging member has an average particle diameter of 10 to 100 μm, a saturation magnetization of 20 to 250 emu / cm 3, and a resistance of 1 × 10 2 to 2 μm.
It is preferably 1 × 10 ・ 10 Ω · cm, more preferably 1 × 10 ＾ 6 Ω · cm or more in consideration of the fact that the photosensitive drum 1 has an insulation defect such as a pinhole. In order to improve the charging performance, it is better to use one having as small a resistance as possible. In this embodiment, the average particle diameter is 25 μm, and the saturation magnetization is 200 emu / cm.
3. Magnetic particles having a resistance of 5 × 10 6 Ω · cm were used.

Here, the resistance value of the carrier has a bottom area of 2
After 2 g of a carrier was placed in a 28 (mm ＾ 2) metal cell, the cell was weighted at 6.6 kg /, and a voltage of 100 V was applied to measure.

As the magnetic particles, a resin carrier formed by dispersing magnetite as a magnetic material in a resin and dispersing carbon black for conductivity and resistance adjustment;
Alternatively, a material in which the surface of a single magnetite such as ferrite is oxidized and reduced to adjust the resistance, or a material in which the surface of a single magnetite such as ferrite is coated with a resin and the resistance is adjusted may be used.

The nip width W of the magnetic brush formed on the photosensitive drum 1 was adjusted to be approximately 6 mm.
In the present embodiment, good charging properties can be obtained by applying a bias in which a rectangular alternating voltage of 100 Hz and 800 V is superimposed on a DC voltage of -700 V to the magnetic brush charger 32.

As the photosensitive drum 1 used in the present invention, a commonly used organic photosensitive member or the like can be used. Preferably, the resistance of the organic photosensitive member is 10 °.
When a material having a surface layer having a material of 9 to 10 ＾ 14 Ω · cm or an amorphous silicon photoreceptor is used, charge injection charging can be realized, which is effective in preventing ozone generation and reducing power consumption. Further, the chargeability can be improved. Therefore, in the present embodiment, a photosensitive drum 1 which is a negatively charged organic photoreceptor and is provided with the following five layers from the bottom in order from the bottom on a 30 mm diameter aluminum drum substrate is used.

The first layer is an undercoat layer, and is a conductive layer having a thickness of 20 μm provided for smoothing defects or the like of an aluminum substrate (hereinafter referred to as an aluminum substrate).

The second layer is a positive charge injection preventing layer, which serves to prevent positive charges injected from the aluminum substrate from canceling out negative charges charged on the surface of the photoreceptor, and comprises an amylan resin and methoxymethylated nylon. 1 × 10 ＾ 6Ω
A medium resistance layer having a thickness of 1 μm and a resistance adjusted to about cm.

The third layer is a charge generation layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates a positive and negative charge pair upon exposure.

The fourth layer is a charge transport layer in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore, the negative charges charged on the photoreceptor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoreceptor surface.

The fifth layer is a charge injection layer, and is a coating layer of a material in which ultrafine SnO2 particles are dispersed in a binder of an insulating resin. Specifically, a material obtained by dispersing 70% by weight of SnO2 particles having a particle diameter of about 0.03 [mu] m, which is obtained by doping an insulating resin with antimony as a light-transmitting insulating filler to reduce the resistance (conducting conductivity), with respect to the resin. It is a coating layer.
The coating solution thus prepared was applied to a thickness of about 3 μm by a suitable coating method such as dipping coating method, spray coating method, roll coating method, beam coating method, etc. to form a charge injection layer.

Here, the developing step will be described. FIG. 2 is a schematic view of the developing device 5 for two-component magnetic brush development used in the present embodiment. In the figure, 11 is a developing sleeve,
Reference numeral 12 denotes a magnet roller fixedly disposed in the developing sleeve 11, 13 and 14 denote stirring screws, 15 denotes a regulating blade disposed to form a thin layer of developer on the surface of the developing sleeve 11, and 16 denotes a developing container. Developing sleeve 1
Reference numeral 1 denotes an arrangement in which a region closest to the photosensitive drum 1 is at least about 500 μm at least at the time of development, and is set so that development can be performed in a state where the developer contacts the photosensitive drum 1. 2 used in the present embodiment
The component developer has an average particle diameter of 20 n for a negatively charged toner having an average particle diameter of 6 μm manufactured by a pulverization method.
A magnetic carrier having a saturation magnetization of 205 emu / cm 3 and an average particle diameter of 35 μm was used as the carrier. A mixture of the toner and the carrier at a weight ratio of 6:94 was used as a developer.

Here, the electrostatic latent image is transferred to the developing device 5 described above.
The following describes a developing process of visualizing the image by a two-component magnetic brush method using the method and a circulation system for the developer. First, the developer pumped by the N2 pole with the rotation of the developing sleeve 11 is transported from the S2 pole to the N1 pole in the process of being conveyed.
And a thin layer is formed on the developing sleeve 11. Here, when the developer formed in a thin layer is conveyed to the developing main pole S1, poles are formed by magnetic force.
The electrostatic latent image is developed by the spike-shaped developer, and thereafter the developer on the developing sleeve 11 is returned into the developing container 16 by the repulsive magnetic field of the N3 pole and the N2 pole.

A DC voltage and an AC voltage are applied to the developing sleeve 11 from a power supply (not shown). In this embodiment, the DC voltage is -500 V and the AC voltage is Vpp = 15.
00V and Vf = 2000 Hz are applied. In general, in the two-component developing method, when an AC voltage is applied, the developing efficiency is increased, and the quality of an image is high. On the contrary, there is a risk that fogging is likely to occur. For this reason, fog is generally prevented by providing a potential difference between the DC voltage applied to the developing sleeve 11 and the surface potential of the photosensitive drum 1.

This toner image is then transferred to the recording material P by the transfer device 7. The transfer device 7 hangs an endless belt 71 between a driving roller 72 and a driven roller 73 as shown in FIG. 1, and is rotated in the direction of arrow D in FIG. Further, a transfer charging blade 74 is provided in the transfer device 7. The transfer charging blade 74 generates a pressing force from the inside of the belt 71 in the direction of the photosensitive drum 1 and is supplied with power from a high-voltage power supply so that the back side of the recording material P Then, the toner image on the photosensitive drum 1 is sequentially transferred to the upper surface of the recording material P by performing charging of the polarity opposite to that of the toner.

Here, the recording material P is conveyed from the paper feeding and conveying device to the transfer section formed by the photosensitive drum 1 and the belt 71 at an appropriate timing in synchronization with the rotation of the photosensitive drum 1. In the present embodiment, a belt 71 made of a polyimide resin having a thickness of 75 μm is used.
The material of the belt 71 is not limited to a polyimide resin, and may be a polycarbonate resin, a polyethylene terephthalate resin, a polyvinylidene fluoride resin, a polyethylene naphthalate resin, a polyetheretherketone resin, a polyethersulfone resin, a polyurethane resin, or the like. Plastic, fluorine-based, or silicon-based rubber can be suitably used. 75 μm for thickness
Is not limited to about 25 to 2000 μm,
Preferably, those having a thickness of 50 to 150 μm can be suitably used.

Further, as the transfer charging blade 74, one having a resistance of 1 × 10 ＾ 5 to 1 × 10 ＾ 7Ω, a plate thickness of 2 mm, and a length of 306 mm was used. This transfer charging blade 7
4 was transferred by applying a bias of +15 μA under constant current control.

The toner image thus formed on the photosensitive drum 1 is electrostatically transferred onto the recording material P by the transfer charging blade 74. After that, the recording material P is fixed to the fixing unit 6.
And heat-fixed to output an image.

On the other hand, the transfer residual toner remains on the surface of the photosensitive drum 1 after the transfer of the toner image. If the transfer residual toner first passes through the magnetic brush charger 32 as it is, the above-mentioned ghost occurs. Even when the transfer residual toner passes under the magnetic brush by the magnetic brush charger 32 in contact with the photosensitive drum 1, in most cases, the shape of the previous image remains unchanged, and is uniform under the setting of the magnetic brush under appropriate charging conditions. Did not seem to be dispersed.
Therefore, it is necessary to remove the transfer residual toner that has reached the charged area with the rotation of the photosensitive drum 1 into the charged magnetic brush and erase the history of the previous image. At this time, the toner is not sufficiently taken into the magnetic brush charger 32 only by applying the DC voltage to the magnetic brush charger 32. However, when the alternating voltage is applied to the magnetic brush charger 32, the photosensitive drum 1 is charged. Due to the vibration effect of the electric field between the chargers 32, the toner is relatively easily taken into the chargers 32.

Further, once collected by a magnetic brush,
The toner charged to the normal polarity is discharged onto the photosensitive member due to the potential difference between the magnetic brush charger 32 and the photosensitive drum 1, reaches the developing area, stays on the photosensitive member in the image area, and In the developing unit.

FIG. 4 shows the process cartridge B and exposure means in this embodiment. LE as exposure means
A D array writer head 50 is used. In the cleanerless process as described above, since the transfer residual toner accumulates in the magnetic brush charger 32, the toner scattering phenomenon in the conventional development is also recognized from the magnetic brush charger 32 side, and an additional exposure unit located in the vicinity is required. May be contaminated. Conventionally, a cleaning unit is provided to perform manual or automatic cleaning. However, even if automatic cleaning is performed, the configuration of the image forming apparatus main body may be complicated or toner may spill out from the cleaning member.

Therefore, in the present invention, as shown in FIG. 4, the constituent members on the image forming apparatus main body side, in particular, the LED array writer head 50 disposed close to the photosensitive drum 1 is contaminated by the scattered toner generated in the process cartridge B. As a means for preventing contamination, a contamination prevention mylar 51 of a 50 μm-thick mylar sheet is disposed between the LED light emitting portion and the photosensitive drum 1, and the opening 53 on the upper surface of the process cartridge B is sealed. B
Attached to the side. With this arrangement, the toner scattered from both the developing device 5 side and the magnetic brush charger 32 side can be used as the LED array writer head 50 as an exposure unit.
Can be prevented at the same time.

In order to maintain a better exposure state for a long period of time, both sides of the opening 53 on the side of the contamination prevention mylar 51 facing the photosensitive drum 1 are made of aluminum in a direction parallel to the axial direction of the photosensitive drum 1. Electrode plate contamination prevention electrode 52
Is attached, and a DC voltage having a polarity opposite to that of the normal holding charge of the toner is applied to the contamination prevention electrode 52.

The life of the process cartridge B used in the present embodiment is 2 times the image ratio of A4 of Japanese Industrial Standard paper.
Although it is assumed that 50,000 sheets of the recording material P are passed through 0%, the toner scattered from the magnetic brush charger 32 and the developing device 5 is prevented from being contaminated in the endurance of 50,000 sheets with an image ratio of 20%. The toner trapped by the electrode 52 and not completely trapped adheres to the contamination prevention mylar 51, but does not affect the exposure amount.

Thereafter, by replacing the process cartridge B, the contamination prevention mylar 51, which has been contaminated at the same time, is renewed, so that the exposure surface returns to the same state as the initial state, and the LED array writer head is replaced no matter how many times the process cartridge B is replaced. 50, that is, the light emitting portion was not contaminated.

With the above configuration, the LED array writer head of the image forming apparatus main body, which has a longer service life than the process cartridge, is directly contaminated automatically with a simple cleaning member without human intervention. The required exposure amount could be maintained for a long time without any problem.

[0046]

According to a first aspect of the present invention, there is provided a process cartridge detachably mountable to an image forming apparatus main body, comprising: an electrophotographic photosensitive member; a process means acting on the electrophotographic photosensitive member; By using a process cartridge having a member for preventing the member from being contaminated by the scattered developer generated in the process cartridge, good image formation can be stably performed over a long period of time.

According to a second aspect of the present invention, in the first aspect, there is provided an opening for introducing light into the inside for exposing the electrophotographic photosensitive member, and the light is transmitted through the opening. As a result, the developer scattered from the process cartridge to the components on the image forming apparatus main body side is blocked by the light transmitting member.

According to a third aspect of the present invention, in the second aspect, the light transmitting member is mounted on the image forming apparatus main body, wherein the light transmitting member is a process cartridge which is close to an exposure source provided in the image forming apparatus main body. Accordingly, contamination by the developer scattered from the process cartridge of the exposure source disposed particularly close to the process cartridge can be prevented.

According to a fourth aspect of the present invention, in the second or third aspect, a process cartridge having an electrode for adsorbing the scattered developer is provided as a contamination preventing means, so that the developer scattered from the process cartridge is reduced. Since the developer is collected on the electrode, the movement of the scattered developer to the light transmitting member is substantially prevented.

According to a fifth aspect of the present invention, in the fourth aspect, the electrode is a process cartridge disposed in parallel with the axis of the electrophotographic photosensitive member. Scattered toner can be collected.

According to a sixth aspect of the present invention, in the fourth aspect, the electrode is a process cartridge provided on the inner side of the light transmitting member. Can be effectively suppressed from being contaminated.

According to a seventh aspect of the present invention, the process cartridge includes a magnetic brush charging device as a process means and a developing means using a two-component developer. Appropriate results are obtained when applied to the invention as described in any one of the inventions.

An eighth invention according to the present application is the invention according to the seventh aspect, wherein the electrode is on the side facing the peripheral surface of the electrophotographic photosensitive member moving from the magnetic brush charging device to the developing means, and Since the brush charging device and the developing device are separately disposed on the side close to each other, the scattered developer generated from the magnetic brush charging device and the developing device can be collected so that the scattering does not reach far. Therefore, contamination of both the process cartridge and the image forming apparatus main body can be suppressed.

According to a ninth aspect of the present invention, there is provided an electrophotographic image forming apparatus which detachably attaches a process cartridge and forms an image on a recording medium, comprising: a. A process cartridge comprising: an electrophotographic photosensitive member; a process unit acting on the electrophotographic photosensitive member; and a contamination preventing unit for preventing a component on the image forming apparatus main body side from being contaminated by scattered developer generated in the process cartridge. Mounting means for removably mounting the b. The image forming apparatus main body side constituent member; c. By providing the electrophotographic image forming apparatus having the conveying means for conveying the recording medium, it is not necessary to provide the electrophotographic image forming apparatus with a device for preventing the developer from scattering. Further, the operation for removing the scattered developer can be eliminated.

According to a tenth aspect of the present invention, in the ninth aspect, the constituent member on the image forming apparatus main body side is an exposure source for exposing to form a latent image on an electrophotographic photosensitive member. In addition, contamination of the exposure source due to scattering developer can be prevented.

According to an eleventh aspect of the present invention, in the tenth aspect, the exposure source is an LED array writer head, so that the LED array writer head disposed particularly close to the electrophotographic photosensitive drum can be used. A suitable result can be obtained by applying the present invention to an electrophotographic image forming apparatus.

A twelfth invention according to the present application is the electrophotographic image forming apparatus according to the tenth or eleventh invention, wherein the exposure source is disposed at a position close to the electrophotographic photosensitive member of the mounted process cartridge. It is effective to apply to

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an image forming apparatus used in an embodiment.

FIG. 2 is a longitudinal sectional view showing a two-component developing device used in the embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a process cartridge used in a conventional example.

FIG. 4 is a longitudinal sectional view of a process cartridge, an exposure unit, a contamination prevention mylar, and an electrode used in the embodiment.

FIG. 5 is an external perspective view of the image forming apparatus according to the embodiment.

FIG. 6 is an external perspective view of the image forming apparatus according to the embodiment.

[Explanation of symbols]

A: Image forming apparatus B: Process cartridge G: Book P: Recording material 1: Photosensitive drum 2: Charging blade 3: Charger container 4: Cleaning device 5: Developing device 5a: Housing 6: Fixing means 6a: Drive roller 6b Heater 6c
... Fixing roller 7 ... Transfer device 9 ... Exposure opening 10 ... Optical system 10a ... Document table 11 ... Developing sleeve 12 ... Magnetic roller 13 ... Agitating screw 14 ... Agitating screw 15 ... Regulator blade 16 ... Developing container 19 ... Device body 20 ... Conveying belt 20a Feeding cassette 20b Pickup roller 20e Registration roller 20g Discharge roller pair 21 Discharge section 25 Opening / closing member 25a Support shaft 26 Cartridge mounting section 27 Guide rail 32 Magnetic brush charger 50 LED Array writer head 51: contamination prevention mylar 52 ... contamination prevention electrode 53 ... exposure opening on the upper surface 71 ... belt 72 ... drive roller 73 ... driven roller 74 ... transfer charging blade

Continued on the front page (72) Inventor Yoshiyuki Komiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Takeda 3- 30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. F-term (reference) 2H027 JA03 JB08 JB11 JC04 JC15 ZA10 2H071 BA04 BA35 DA06 DA08 DA13 DA15 EA10 2H077 CA11

Claims (12)

[Claims] 1. A process cartridge detachably mountable to an image forming apparatus main body, wherein: an electrophotographic photosensitive member; a process means acting on the electrophotographic photosensitive member; And a contamination prevention means for preventing contamination by the process cartridge. 2. The contamination prevention means having an opening for introducing light into the inside of the electrophotographic photosensitive member for exposing the same, and closing the opening with a light transmitting member through which the light passes. The process cartridge according to claim 1, wherein: 3. The process cartridge according to claim 2, wherein the light transmitting member is close to an exposure source provided in the image forming apparatus main body when mounted on the image forming apparatus main body. 4. The process cartridge according to claim 2, further comprising an electrode for adsorbing the scattered developer as a means for preventing contamination. 5. The process cartridge according to claim 4, wherein the electrodes are arranged in parallel with an axis of the electrophotographic photosensitive member. 6. The process cartridge according to claim 4, wherein the electrode is provided inside the light transmitting member. 7. The process cartridge according to claim 1, wherein the process cartridge has a magnetic brush charging device as a process means and a developing means using a two-component developer. The process cartridge as described. 8. The electrode is separately arranged on a side facing the peripheral surface of the electrophotographic photosensitive member moving from the magnetic brush charging device to the developing means, and on a side close to each of the magnetic brush charging device and the developing means. The process cartridge according to claim 7, wherein the process cartridge is provided. 9. An electrophotographic image forming apparatus which detachably attaches a process cartridge and forms an image on a recording medium, comprising: a. A process cartridge having: an electrophotographic photosensitive member; a process unit that acts on the electrophotographic photosensitive member; and a contamination prevention unit that prevents the image forming apparatus main body side member from being contaminated by scattered developer generated in the process cartridge. Mounting means for removably mounting; b. The image forming apparatus main body side constituent member; c. An electrophotographic image forming apparatus, comprising: conveying means for conveying the recording medium. 10. The electrophotographic image forming apparatus according to claim 9, wherein the image forming apparatus main body side component member is an exposure source for exposing to form a latent image on an electrophotographic photosensitive member. apparatus. 11. An electrophotographic image forming apparatus according to claim 10, wherein said exposure source is an LED array writer head. 12. An electrophotographic image forming apparatus according to claim 10, wherein said exposure source is disposed at a position close to an electrophotographic photosensitive member of a mounted process cartridge.