JP2002123063A - Electrifier, developing device and processing cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the balance of the pressure of a spacer roller on a driving side and a non-driving side and also to stabilize the pressure in an electrifier or a developing device which is supported so that it can oscillate and whose oscillation center axis is aligned with the rotation center axis of a driving input coupling. SOLUTION: A pressure spring 30 is positioned outside from an interstice guarantee member with a photoreceptive drum 7 on the non-driving side. The pressing position of the pressure spring 30 is positioned at an area 33 on a side near 3) a contact in two areas divided by a vertical bisector V defined by two points which are 1) an oscillation center point and 2) the contact 32 of the photoreceptive drum 7 and the spacer roller. An electrifying roller 8a is driven by a shaft coupling on the driving side. Also, an oscillating shaft 23 to support the electrifying roller 8a is made movable in a direction vertical to a line segment L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, a developing device, and a process cartridge, and more particularly, to a magnetic brush type contact charging device and a process cartridge including the charging device. These are used in an electrophotographic image forming apparatus.

Here, an electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming method. And, as an example of the electrophotographic image forming apparatus,
For example, an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, and the like), a facsimile machine, a word processor, and the like are included.

A process cartridge is a unit in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive drum are integrally formed into a cartridge, and this cartridge is made detachable from an image forming apparatus main body. In addition, at least one of the charging unit, the developing unit, and the cleaning unit and the electrophotographic photosensitive drum are integrally formed into a cartridge so that the cartridge can be attached to and detached from the image forming apparatus main body. Further, it means that at least the charging means and the electrophotographic photosensitive drum are integrally formed into a cartridge so as to be detachable from the apparatus main body.

[0004]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image process, an electrophotographic photoreceptor and process means acting on the electrophotographic photoreceptor (photoreceptor drum) are integrally formed as a cartridge. Of the image forming apparatus is adopted. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself without relying on a serviceman, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

Conventionally, a corona charger has been used as a charging device. In recent years, contact charging devices have been put to practical use instead. This aims at low ozone and low power, and among them, a roller charging method using a conductive roller as a charging member is particularly preferably used in terms of charging stability. In the roller charging, a conductive elastic roller is brought into pressure contact with the photosensitive drum, and a voltage is applied thereto to charge the photosensitive drum.

However, even in such a contact charging device, the essential charging mechanism uses a discharging phenomenon from the charging member to the photosensitive drum, and is required for charging as described above. The voltage is required to be higher than the surface potential of the photosensitive drum, and when AC charging is performed for uniform charging, vibration and noise of the charging member and the photosensitive drum due to the electric field of the AC voltage (hereinafter referred to as AC charging). (Referred to as "sound"), and the deterioration of the surface of the photosensitive drum due to discharge has become remarkable, which has been a new problem. For this reason, charging by direct injection of charges to the photosensitive drum has been desired.

Therefore, a method has been devised in which a charge injection layer is provided on the surface of the photosensitive drum and charges are injected by a contact charging member. In this method, by providing the charge injection layer, even a charging member having a resistance value of 1 × 10 ⁴ Ω or more can be sufficiently charged in a short charging time, so that it is caused by discharge as in the other charging methods described above. It is possible to fundamentally solve the problem and the problem that the time required for charging is long.

More specifically, a magnetic brush portion formed by magnetically constraining conductive magnetic particles is provided as a charging member, and the magnetic brush member for bringing the magnetic brush portion into contact with the photosensitive drum is provided in contact with the photosensitive drum. It is preferably used because a large nip can be obtained and uniform contact with the surface of the photoreceptor drum does not occur and there is no microscopic charging failure.

The magnetic brush member is 1 × 10 ⁴ -1 ×
A magnetic brush portion is formed by magnetically constraining magnetic particles such as ferrite having a resistance value of 10 ⁸ Ωcm directly on a magnet or on a supporting member such as a sleeve containing a magnet. Then, the magnetic brush unit is brought into contact with the photosensitive drum, and a voltage is applied to the photosensitive brush to start charging the photosensitive drum.

[0010] Further, the uniform contact of the magnetic brush with the photosensitive drum affects the chargeability of the magnetic brush type charging device. It is preferable to provide a magnetic particle layer thickness regulating means upstream of the portion facing the photoconductor drum in the rotation direction of the supporting member. This configuration is preferable because uniform chargeability of the photosensitive drum can be obtained and charging can be performed very stably.

As the charge injection layer on the photosensitive drum, a layer in which conductive fine particles are dispersed in an insulating and translucent binder is preferably used. When a magnetic brush to which a voltage is applied comes into contact with the charge injection layer, conductive particles are present on the conductive substrate of the photosensitive drum as if they were countless independent floating electrodes. The effect of charging the formed capacitor can be expected.

Accordingly, the voltage applied to the contact charging member and the surface potential of the photosensitive drum converge to the same value, and a low voltage charging method can be realized.

Such a charging method (charging of an object to be charged by direct injection of electric charge) is referred to as “injection charging”. By using this injection charging device, an image forming apparatus without a cleaner can be configured.

The following describes the construction of the injection charging system incorporated in a process cartridge. Many process cartridges have a structure in which a developing container for developing is swingably supported with respect to a frame that supports a cleaning unit and a photosensitive drum. Because the cleaning unit is not provided, the design is how to support the injection charging device, which has the same configuration as the developing device, in which the driven roller is moved closer to the photosensitive drum with a certain gap, in the process cartridge. Had become a point.

In view of the above, a configuration has been devised in which an injection charging device is swingably supported by a frame having a developing portion and a photosensitive drum support portion. In this configuration, the driving of the photosensitive drum, the developing roller, and the charging roller is input from the printer main body via a separate shaft coupling. By doing this,
It has been found that the driving rotation of the roller is stabilized so as not to adversely affect the image quality.

The injection charging roller keeps a constant gap by abutting a gap ensuring member against the photosensitive drum. In order to stabilize the pressure applied to the gap ensuring member, the swing center axis of the injection charging device is arranged on the rotation center line of the shaft joint. The drive torque applied to the coupling directly affects the pressure applied to the gap ensuring member, so that the pressure fluctuation of the gap ensuring member can be reduced, and the distance between the rollers can be reliably ensured.

[0017]

By applying the above configuration to a process cartridge having an injection charging system, it is possible to reliably ensure the gap between the injection charging roller and the photosensitive drum. Due to the increase in driving torque due to the shaft coupling of the injection charging device, the pressure increases between the gap ensuring member and the roller. As a result, there is a problem that the contact portions are scraped off each other, and it becomes difficult to guarantee the gap as the durability increases. Was. This shaving is more remarkable on the longitudinal drive side of the injection charging device having the drive shaft coupling, causing an imbalance in the amount of gap with the longitudinal non-drive side, and the image also has a different density on the drive side and the non-drive side. Was thought to have a negative effect.

Although a slight improvement has been achieved by changing the material of the gap ensuring member and the roller in order to prevent this scraping, it is insufficient, but is insufficient. As a more effective measure, it is necessary to reduce the pressure on the gap ensuring member. Was sought.

Even if the pressure is reduced, the gap assurance member may be cut to some extent, so that it is necessary to maintain the balance between the cut amount on the longitudinal drive side and the non-drive side, that is, equalize the pressure balance. Had been.

Further, in the future, a developing device using the same structure as the above-mentioned charging device is considered, and it has been demanded to realize a pressurizing structure applicable to this developing device.

According to the present invention, the charging device or the developing device is swingably supported with respect to the electrophotographic photosensitive drum, and the center axis of the swing coincides with the rotation center of the drive input shaft joint from the image forming apparatus main body. In the charging device or the developing device, the gap between the electrophotographic photosensitive drum and the charging roller or the developing roller is ensured. An object of the present invention is to provide a charging device or a developing device and a process cartridge capable of reliably applying a pressing force to a gap ensuring member even when twisting occurs in the device and ensuring a gap.

[0022]

SUMMARY OF THE INVENTION The main aspects of the present invention will be described with reference to the claims and the following description.

According to a first aspect of the present invention, there is provided a charging device for charging an electrophotographic photosensitive drum, comprising: a charging roller disposed at a gap from the electrophotographic photosensitive drum and carrying magnetic particles; A gap ensuring member provided coaxially with the charging roller at both ends of the charging roller and contacting the electrophotographic photosensitive drum to secure the gap; and supporting the charging roller at a swing center parallel to the electrophotographic photosensitive drum. A support member provided on the oscillating axis, a coupling for receiving the drive input of the charging roller, and biasing the support member to bring the gap ensuring member into contact with the electrophotographic photosensitive drum. Pressurizing means, comprising a pressurizing means provided outside the gap ensuring member on the side opposite to the side with the shaft coupling with respect to the longitudinal direction of the charging roller,
The charging device is characterized in that the pressing means is provided only on the side opposite to the side where the shaft coupling is located.

According to a fourth aspect of the present invention, there is provided a developing device for developing an electrostatic latent image formed on an electrophotographic photosensitive drum using a developer, the developing device being provided with a gap from the electrophotographic photosensitive drum. A developing roller, a gap ensuring member provided coaxially with the developing roller at both ends of the developing roller and in contact with the electrophotographic photosensitive drum to secure the gap, and the developing roller having the electrophotographic photosensitive drum and A support member that is supported at the center of the parallel swing, a shaft coupling that is provided on the swing axis for the developing roller to receive a drive input, and that causes the gap ensuring member to contact the electrophotographic photosensitive drum. Pressurizing means for urging the support member, wherein the pressurizing means is provided outside the gap ensuring member on the side opposite to the side where the shaft coupling is provided in the longitudinal direction of the developing roller. And said Pressure means is a developing apparatus which is characterized in that the a shaft coupling side is provided only on the opposite side.

According to a seventh aspect of the present invention, there is provided a process cartridge detachably mountable to a main body of an image forming apparatus, comprising: a, an electrophotographic photosensitive member; Charging roller,
A gap ensuring member provided coaxially with the charging roller at both ends of the charging roller to secure the gap by contacting the electrophotographic photosensitive drum, and the charging roller is pivoted at a swing center parallel to the electrophotographic photosensitive drum. A support member for supporting the shaft, a shaft coupling provided on the swing axis for receiving the drive input of the charging roller, and the support member for bringing the gap ensuring member into contact with the electrophotographic photosensitive drum. Pressurizing means, which is provided outside the gap ensuring member on the side opposite to the side where the shaft coupling is located in the longitudinal direction of the charging roller, and A process cartridge provided only on a side opposite to a side where a shaft coupling is provided.

According to a tenth aspect of the present invention, there is provided a process cartridge detachably mountable to an image forming apparatus main body, comprising: a, an electrophotographic photosensitive member, and a developing roller disposed at a gap from the electrophotographic photosensitive drum. A gap ensuring member provided coaxially with the developing roller at both ends of the developing roller and in contact with the electrophotographic photosensitive drum to ensure the gap,
A support member for supporting the developing roller at a swing center parallel to the electrophotographic photosensitive drum, a shaft joint provided on the swing axis for receiving a drive input from the developing roller, and the gap ensuring member Pressurizing means for urging the support member to make contact with the electrophotographic photosensitive drum, the outer side of the gap ensuring member on the side opposite to the side where the shaft coupling is located in the longitudinal direction of the developing roller. And a pressurizing means provided, wherein the pressurizing means is provided only on the side opposite to the side where the shaft coupling is provided.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

In the following description, the longitudinal direction refers to a direction crossing the recording medium transport direction and parallel to the recording medium. The left and right are the left and right as viewed in the transport direction of the recording medium. Further, "above the process cartridge" means above the process cartridge in the mounted state.

Embodiment 1 (Image Forming Apparatus and Image Forming Process) FIG. 1 is a drawing showing an image forming apparatus to which the present invention is applied. This image forming apparatus includes image forming units 31Y, 31M, 31C, 31BK for forming a toner image on a photosensitive drum as an image carrier.
And an intermediate transfer belt 4a for temporarily transferring the toner image, a secondary transfer roller 40 as transfer means for transferring the toner image on the belt 4a to the recording medium 2, and a secondary transfer between the recording medium 2 and the intermediate transfer belt 4a. The image forming apparatus includes a feeding unit, a fixing unit, and a sheet discharging unit that convey the recording medium 2 to a sheet feeding unit that sends out between the rollers 40 and a transfer unit.

Hereinafter, image formation will be described.

As shown in FIG. 1, a plurality of recording media (for example, recording paper, OHP sheet, cloth, etc.)
Is mounted detachably. Paper feed cassette 3 by pickup roller 3b
The recording medium 2 fed from a is separated one by one by a pair of retard rollers 3c, and is conveyed to a pair of registration rollers 3g by conveyance rollers 3d and 3f.

When the recording medium 2 is conveyed, the registration roller pair 3g stops rotating, and the recording medium 2 is skewed by being hit against the nip.

Process cartridge B including image carrier
In the case of the four-drum full-color system, four colors of yellow, magenta, cyan, and black are arranged in parallel in Y, BM, BC, and BB as shown in the figure. Each of the process cartridges BY, BM, BC, and BB is provided with an optical scanning system 1Y, 1M, 1C, and 1BK. After a toner image is formed on a photosensitive drum for each color by an image signal, transfer is performed. The toners of the respective colors are superimposedly transferred onto the intermediate transfer belt 4a running in the direction indicated by the arrow by the rollers 4Y, 4M, 4C, and 4BK.

Thereafter, the recording medium 2 is sent to the secondary transfer roller 40 at a predetermined timing, and the toner image on the intermediate transfer belt 4a is transferred onto the recording medium 2 and the fixing device 5
Is discharged by the discharge roller pairs 3h and 3i, and is stacked on the tray 6 on the apparatus main body 14.

The image forming units 31Y, 31M, 31C,
31BK is a process cartridge BY, BM, BC, BB except for the optical scanning systems 1Y, 1M, 1C, 1BK.
Is composed. Since the configuration of the process cartridge is the same, the process cartridge BY will be described.

As shown in FIG.
Y is a device in which a charging unit, an exposure unit, a developing unit, and a transfer opening are provided around the photosensitive drum 7. In this embodiment, a two-component developer having a magnetic carrier powder is used.
Therefore, the photosensitive drum 7 used in the embodiment of the present invention
As the organic photoreceptor, a commonly used organic photoreceptor can be used. Desirably, an organic photoreceptor having a surface layer having a material having a resistance of 10 ² to 10 ¹⁴ Ω · cm or an amorphous When a silicon photoreceptor or the like 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 7 having a negatively charged organic photosensitive member provided on an aluminum drum base is used.

The charging means is a magnetic brush charger 8 using a magnetic carrier.

This charger 8 has a fixed magnet 8b disposed inside a hollow cylindrical charging roller 8a rotatably supported. After the transfer, the toner remaining on the photosensitive drum 7 is taken into the charger 8 which rotates in the direction of the arrow shown in the figure.

In the present embodiment, a developing method in which a two-component developer is brought into contact with the developing means (two-component non-contact development) is employed.

FIG. 2 shows the developing means 10 for two-component magnetic brush development used in the present embodiment. The developing sleeve 10d has a hollow cylindrical shape and is rotatably supported. A fixed magnet 10c is provided in the developing sleeve 10d. The developing sleeve 10d rotates in the same direction as the photosensitive drum 7, and the peripheral surface moves in a direction opposite to the moving direction of the peripheral surface of the photosensitive drum 7. The photosensitive drum 7 and the developing sleeve 10d are in non-contact with each other in a range of 0.2 to 1.0.
A gap of about mm is provided so that development can be performed in a state where the developer contacts the photosensitive drum 7.

The toner mixed with the carrier is supplied by stirring screws 10g and 10h in a casing partitioned by a longitudinal partition wall 10f excluding both ends. The toner supplied from a toner supply container (not shown) is
g is dropped to one end side and is agitated while being sent in one direction in the longitudinal direction, passes through the portion without the partition wall 10f on the other end side, moves to one end side with the stirring screw 10h, and then moves to the partition wall 10f on one end side. The mixture is stirred and circulated while being fed by the stirring screw 10h through the portion without.

Here, the developing step of visualizing the electrostatic latent image formed on the photosensitive drum 7 by the two-component magnetic brush method using the developing means 10 and the circulation system of the developer will be described. First, the developer pumped up by the poles of the magnet 10c with the rotation of the developing sleeve 10d is regulated by a regulating blade 10e arranged perpendicular to the developing sleeve 10d in the process of being conveyed, and is placed on the developing sleeve 10d. A thin layer is formed. When the developer having a thin layer formed thereon is conveyed to the main developing pole, ears are formed by magnetic force. The electrostatic latent image on the photosensitive drum 7 is developed by the spike-shaped developer, and then the developer on the developing sleeve 10 d is moved by the repulsive magnetic field to the developing container 3.
Returned to 5

A DC voltage and an AC voltage are applied to the developing sleeve 10d from a power source (not shown). Generally, in the two-component developing method, when an AC voltage is applied, the developing efficiency increases,
Although the image has high quality, fogging tends to occur easily. For this reason, usually, the developing sleeve 1
By providing a potential difference between the DC voltage applied to 0d and the surface potential of the photosensitive drum 7, it is possible to prevent toner from adhering to the non-image area during development.

This toner image is then transferred to the intermediate transfer belt 4a by the intermediate transfer device 4. Intermediate transfer device 4
The endless belt 4a is driven by a driving roller 4b and a driven roller 4b.
c and the secondary transfer facing roller 4d, and is rotated in the direction of the arrow in FIG. Further, transfer charging rollers 4Y, 4M, 4C, and 4BK are provided in the transfer belt 4a, and each transfer charging roller is supplied with power from a high-voltage power supply while generating a pressing force from the inside of the belt 4a toward the photosensitive drum 7. By that
The toner image on the photosensitive drum 7 is sequentially transferred to the upper surface of the intermediate transfer belt 4a by performing charging of the polarity opposite to that of the toner from the back side of the belt 4a.

As the intermediate transfer belt 4a, a belt made of a polyimide resin can be used. The material of the belt 4a is not limited to the polyimide resin,
Dielectrics such as polycarbonate resin, polyethylene terephthalate resin, polyvinylidene fluoride resin, polyethylene naphthalate resin, polyetheretherketone resin, polyethersulfone resin, polyurethane resin and other plastics, and fluorine-based and silicon-based rubbers are suitable. Can be used.

Transfer residual toner remains on the surface of the photosensitive drum 7 after the transfer of the toner image. If the transfer residual toner is allowed to pass through the charger as it is, there occurs a phenomenon (hereinafter, referred to as a ghost) in which the charged potential of only the remaining image portion decreases, or the previous image portion becomes thinner or darker on the next image. Would. Even if the transfer residual toner passes under the charged magnetic brush in contact with the photosensitive drum 7, the shape of the previous image remains in most cases. Therefore, the photosensitive drum 7
With the rotation of, the transfer residual toner that has reached the charged area needs to be taken into the magnetic brush charger 8 to erase the history of the pre-image. At this time, when an AC voltage is applied to the magnetic brush charger 8, the toner is easily taken into the charger by the vibration effect of the electric field between the photosensitive drum and the charger. Here, the transfer residual toner on the photosensitive drum 7 often has both positive and negative polarities due to peeling discharge at the time of transfer, but the toner is easily taken into the magnetic brush charger 8. In consideration of this, it is desirable that the transfer residual toner is positively charged.

In the present embodiment, the conductive brush 11 is brought into contact with the photosensitive drum 7 between the intermediate transfer device 4 and the magnetic brush charger 8, and a bias having a polarity opposite to the charging bias is applied. The transfer residual toner of the positive polarity passes through the magnetic brush charger 8, and the transfer residual toner of the negative polarity is temporarily captured by the conductive brush 11, and is discharged onto the photosensitive drum 7 again after the charge is removed. Thereby, the transfer residual toner is more easily taken in the direction of the magnetic brush.

(Attaching Process Cartridge to Image Forming Apparatus Main Body) Next, a procedure for attaching the process cartridge B to the apparatus main body 14 will be described with reference to FIG. FIG. 10 is a perspective view schematically illustrating the appearance of the image forming apparatus main body 14. As shown in FIG. 10, a front door 58 that can be opened and closed is disposed on the front of the image forming apparatus main body 14. When the front door 58 is opened to the front, the process cartridges BY to BB are exposed.

A centering plate 59 rotatably supported is disposed in the opening for inserting the process cartridge B. When the process cartridge B is inserted and removed, the centering plate 59 is opened. . Image forming apparatus main body 1
4, a guide rail (not shown) for guiding the mounting of the process cartridge B is provided in the front-rear direction. The mounting direction of the process cartridge B is a direction parallel to the axial direction of the photosensitive drum 7, and the above-described guide rails are also arranged in the same direction. The process cartridge B is slid from the near side to the far side in the apparatus main body 14 along the guide rail and inserted.

When the process cartridge B is inserted to the innermost part, a centering shaft (not shown) provided on the inner side of the apparatus main body 14 is inserted into a center hole (not shown) of the photosensitive drum 7, and the photosensitive drum 7 Is determined with respect to the apparatus body 14. At the same time, the respective drive couplings 15, 26, 27 (see FIG. 3) of the process cartridge B are respectively connected to the respective drive couplings (not shown) of the apparatus main body 14.

A rotatable centering plate 59 is disposed on the front side of the apparatus body 14, and a bearing case (not shown) of the process cartridge B is fitted and supported on the centering plate 59. Is done. By these series of insertion operations, the photosensitive drum 7 and the process cartridge B are moved to the apparatus main body 14.
Is positioned with respect to

(Injection Charging Device) A method of installing the injection charging device 8 in the process cartridge B and a pressurizing means will be described.

As shown in FIG. 4 (a), the injection charging device 8 has a shaft 17 of the injection container holder R16 and a hole of the cartridge holder R20 on the drive side having a drive shaft coupling (hereinafter referred to as a coupling) 15. 21 and on the non-driving side in the longitudinal reverse direction, the long hole portion 19 of the injection container holder F18 is fitted to the shaft portion 23 of the cartridge holder F22 to be supported by the process cartridge B. The cartridge holder R20 and the cartridge holder F22 are fixed to the frame of the process cartridge B.

The photosensitive drum 7 is a process cartridge B
The injection charging device 8 swings the center axis 25 of the cartridge holder R hole 21 and the cartridge holder F shaft 23 with respect to the process cartridge (see FIG. 7). It is swingably supported as a moving shaft, and is also swingable with respect to the photosensitive drum 7.

The injection container holders R16 and F18 shown in FIG.
Are fixed to both ends of the charging container 12 shown in FIG. Accordingly, the charging container 12 extends over substantially the entire length of the process cartridge B. In addition, cartridge holder R2
Reference numerals 0 and L22 are respectively fixed to both longitudinal ends of a developing frame 35 which is a basic frame of the process cartridge B.

As described above, the injection charging device (magnetic brush charger) 8 is located at the center of the swinging center 25R which is the center of the cartridge holder R hole 21 on the driving side and the center of the cartridge holder F shaft 23 on the non-driving side. It is supported so as to swing about a swing center line 25 which is a straight line connecting the swing centers 25F.

In FIG. 4A, the drive coupling 15
Is fitted into the coaxial hole of the shaft 17 of the injection container holder R16. Next, when the cartridge holder R20 and the injection container holder R16 are fitted together, the drive coupling 15 is exposed to the outside of the process cartridge B as shown in FIG. In this part, driving is input from the apparatus main body 14.

In FIG. 3C, reference numeral 26 denotes a drive coupling of the photosensitive drum 7, and reference numeral 27 denotes a drive coupling of the developing device 10. The drive of the photosensitive drum 7, the developing means 10, and the injection charging device 8 is such that drive inputs from the device main body 14 are respectively passed through separate couplings. By doing so, the rotation stability of the injection charging sleeve 8a, the photosensitive drum 7, and the developing sleeve 10d can be ensured to such an extent that the image quality is not adversely affected.

Next, the injection charging roller 8a and the photosensitive drum 7
The following describes how to guarantee the gap between the two.

The injection charging device 8 supporting the injection charging roller 8a is swingable with respect to the photosensitive drum 7 as described above. As shown in FIG.
As shown in (a), the SD spacer R28 and the SD spacer F29 are attached. By contacting these SD spacers with the photosensitive drum 7, an injection charging sleeve 8 is formed.
a and the photosensitive drum 7 is secured. The SD spacers 28 and 29 are designed in advance so as to have a predetermined gap between the charging roller 8a and the photosensitive drum 7.

Next, means for pressing the SD spacer, which is a gap ensuring member, will be described.

By applying a constant pressure to the gap ensuring member, even if a force is generated in the direction in which the gap ensuring member is separated from the photosensitive drum 7 due to disturbance, the gap ensuring member reliably contacts the photosensitive drum. Always ensure a certain amount of clearance.

The pressure applied to the SD spacer R 28 on the drive coupling side in the longitudinal direction of the injection charging device is obtained by the rotation of the injection drive coupling 15 by the drive input of the apparatus main body 14.

As shown in FIGS. 4A and 4B, the center axis of rotation of the drive coupling 15 coincides with the swing axis of the injection charging device 8, that is, the center line 25 in FIG. is there. Therefore, the rotational moment of the drive torque for rotating the drive coupling 15 is substantially unchanged as it is from the SD spacer R28.
Appears as pressure on If the rotational direction is constant, the rotational moment of the driving torque is not applied in the negative direction of the pressing direction, so this shaft configuration has an advantage in that the pressing force to the SD spacer can be stably obtained. .

Next, the arrangement of the pressurizing means on the non-driving side in the longitudinal direction of the injection charging device will be described.

As shown in FIG. 4C, pressure is applied mainly to the SD spacer F29, which is the non-driving-side gap ensuring member, by the non-driving-side pressing spring 30. As shown in FIGS. 4A and 5, the non-drive-side pressure spring 30 is located outside the SD spacer F29 in the longitudinal direction of the injection charging device. For this reason, as shown in FIG.
29 works as it is, but the SD spacer R28 on the drive side
Works in the direction in which the SD spacer R28 is separated from the photosensitive drum 7 with the SD spacer F29 as a fulcrum. The pressurization of the drive side SD spacer R28 is mainly obtained by the drive moment of the injection charging device. When the drive moment is large and the pressing force on the SD spacer R28 increases, the above spring arrangement should be adopted. Reduces the pressure applied to the SD spacer R28, and the non-drive side SD spacer F2
9 is effective in the sense of balancing the pressure.

Next, a description will be given of the arrangement of the pressurizing means for nullifying the twist of the injection charging device.

It is conceivable that the injection charging device is slightly twisted in terms of component accuracy and assembly accuracy. In the case where the swing center line 25 of the injection charging device is fixed to the photosensitive drum 7 and the injection charging device is twisted, whether the SD spacer, which is the gap ensuring member, is driven or not driven. However, it is separated from the photosensitive drum, and the gap cannot be guaranteed. In order to prevent this, it is necessary to provide a mechanism for moving the swing center line 25 in accordance with the amount of twist of the injection charging device. More specifically, as shown in FIG. 6, the injection charging device moves the process cartridge B and the photosensitive drum 7 to the illustrated (drive input position).
(Contact between the SD spacer R28 and the photosensitive drum 7),
(The contact point between the SD spacer F29 and the photosensitive drum 7) is spatially positioned at a total of three points. The point is the swing center 25F on the non-driving side, but this portion must be equalized according to the amount of twist of the injection charging device. For this reason, the embodiment of the present invention has the following configuration.

As shown in FIG. 7, the holes 19 of the injection container holder 18 were elongated holes 0.5 mm larger on both sides than the shaft 23 of the cartridge holder F. The direction of the elongated hole is perpendicular to a line connecting the contact point 32 between the photosensitive drum 7 and the SD spacer F29 and the swing center 25F of the injection charging device. Can now be equalized. There are various methods for determining the direction of the elongated hole. In short, it is sufficient that the direction of the elongated hole is substantially parallel to the line connecting the photosensitive drum 7 and the center of the charging roller 8a. In the embodiment of the present invention, the above has been determined.

The arrangement of the pressure spring in the equalizing mechanism will be described below.

As shown in FIG. 7, the pressure spring 30 comes into contact with the injection container holder F18 at the contact point 34, and applies a pressing force to the SD spacer.

In addition, the arrangement of the pressure spring 30 is
The position of 4 is 1) swing center 25F, 2) photosensitive drum 7
The two regions divided by the perpendicular bisector V of the line segment L connecting the contact 32 with the SD spacer F29 are located in the region 33 closer to the contact 32.

By arranging the contacts 34 at the above positions,
The pressing force of the pressure spring 30 is applied to the contact 32 between the photosensitive drum 7 and the SD spacer F29 more than the swing center 25F. Due to this pressurizing force, the SD spacer F29 comes into contact with the photosensitive drum 7 earlier than the cartridge holder F shaft 23 comes into contact with one of the long holes 19 of the injection container holder.

By applying the above configuration, even if the injection charging device is twisted, the swing center axis is equalized, and the pressure is securely applied to the SD spacer, which is the gap ensuring member, to secure the gap. It became possible.

Next, a method of attaching the pressure spring 30 will be described.

As shown in FIG. 8, the pressure spring 30 is a compression coil spring, and is first attached to the spring seat pin 36b of the spring receiving member 36. And the injection charging device 8
Developing container 35 which is a basic frame of process cartridge B
In this state, the spring receiving member 36 is attached to the developing container 35 by using the elastically deformed pawl 36a so that the pressure spring 30 rides on the spring receiving portion 37 of the injection container holder F18. That is, the elastically deformed claw 36a is snap-fitted to the locking projection 35a projecting into the recess 35b of the developing container 35.

[Embodiment 2] The above is an embodiment in which the injection charging device is swingably attached to the process cartridge. However, in the case where the developing device is attached to the process cartridge in a similar configuration. Can also be suitably applied.

The developing device receives a drive input through the coupling 27 shown in FIG. 3C and swings with respect to the photosensitive drum 7 with reference to the swing center 38 in FIG.

[0080]

According to the present invention, the charging device or the developing device is supported so as to be able to swing with respect to the electrophotographic photosensitive drum, and the swing center axis is the rotation center of the drive input coupling from the image forming apparatus main body. In the charging device or the developing device that coincides with the axis, the charging device optimizes the pressure balance between the driving side and the non-driving side of the gap ensuring member to ensure a gap between the photosensitive drum and the charging roller or the developing roller. Alternatively, even if the developing device is twisted, it is possible to provide a charging device or a developing device and a process cartridge capable of reliably applying a pressure to the gap ensuring member and ensuring the gap.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electrophotographic image forming apparatus.

FIG. 2 is a vertical sectional view of a process cartridge.

FIG. 3A is a side view of the process cartridge.
Is a front view, and FIG.

FIG. 4A is a front view of the injection charging device, FIG.
(C) is a side view.

FIG. 5 is a conceptual diagram of a pressure spring arrangement.

FIG. 6 is a schematic view of an arrangement perspective view of an injection charging device and a photosensitive drum.

FIG. 7 is a layout diagram of a pressure spring on a non-drive side.

FIG. 8 is an assembly diagram of a non-drive-side pressure spring, and FIG.
Is a front view and (b) is a side view.

FIG. 9 is a longitudinal sectional view of a process cartridge according to a second embodiment.

FIG. 10 is a perspective view of the electrophotographic image forming apparatus.

[Explanation of symbols]

B (BY, BM, BC, BB) Process cartridge 1Y, 1M, 1C, 1BK Scanning optical system 2 Recording medium 3a Paper cassette 3b Pickup roller 3c
... Retard roller pair 3d, 3f ... Transport roller 3g ... Registration roller pair 3
h, 3i: discharge roller pair 4: intermediate transfer device 4a: intermediate transfer belt 4b: drive roller 4c: driven roller 4
d: Secondary transfer opposed roller 4Y, 4M, 4C, 4BK ...
Transfer roller 5 Fixing device 6 Tray 7 Photoconductor drum 8 Injection charging device (magnetic brush charger) 8a Charging roller 8b Magnet 10 Developing means 10c Magnet 10d Developing sleeve 10e Regulator blade 10f Partition wall 10
g, 10h Stirring screw 11 Conductive brush 12 Charging container 13 Stirring member 14 Device body 15 Injection charging device drive coupling 16 Injection container holder R 17 Injection container holder R shaft part 18 Injection container holder F 19: Injection container holder F slot 20: Cartridge holder R 21: Cartridge holder R hole 22: Cartridge holder F 23: Cartridge holder F shaft 24: Process cartridge frame 25: Injection charging device swinging shaft 25: Swing center line 25F
... Swing center 25R ... Swing center 26 ... Photosensitive drum drive coupling 27 ... Developing device drive coupling 28 ... SD spacer R 29 ... SD spacer F 30 ... Non-drive side pressure spring 31Y, 31M, 31C, 31BK ... Image Forming part 32: Contact point between photosensitive drum and SD spacer 33: Area in two divided areas near contact point 32 34: Contact point between pressure spring 30 and injection container holder F18 35: Developing container 35a: Lock Projection 35b Concave part 36 Spring receiving member 36a Elastic deformation pawl 36b
Spring seat pin 37 ... Injection container holder F Spring receiving part 38 ... Swing center 40 ... Secondary transfer roller 58 ... Front door 59 ... Centering plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H003 AA01 BB11 CC04 EE16 EE19 2H071 BA04 BA16 BA27 BA36 CA01 CA02 CA05 DA06 DA08 DA15 DA26 2H077 AD06 BA03 BA07

Claims (12)

[Claims] 1. A charging device for charging an electrophotographic photosensitive drum, comprising: a charging roller disposed with a gap from the electrophotographic photosensitive drum to carry magnetic particles; and charging rollers at both ends of the charging roller. A gap ensuring member provided coaxially with the electrophotographic photosensitive drum to secure the gap by contacting the electrophotographic photosensitive drum; a supporting member for supporting the charging roller at a swing center parallel to the electrophotographic photosensitive drum; A shaft coupling provided on a moving axis for the charging roller to receive a drive input; and a pressing unit for urging the support member to bring the gap ensuring member into contact with the electrophotographic photosensitive drum. ,
Pressurizing means provided outside the gap ensuring member on the side opposite to the side with the shaft coupling with respect to the longitudinal direction of the charging roller, and the pressurizing means is on the side opposite to the side with the shaft coupling. A charging device provided only in the charging device. 2. The pressure position of the pressure means, when viewed from the direction of the oscillation axis of the charging device, is perpendicular to the line connecting the contact point between the electrophotographic photosensitive drum and the gap ensuring member and the oscillation center. 2. The charging device according to claim 1, wherein the two areas divided by the dividing line are located on an area closer to a contact point between the electrophotographic photosensitive drum and the gap ensuring member. 3. 3. A supporting member supported so that a swing center on a side provided with the pressing means is allowed to move in a direction substantially parallel to a direction connecting centers of the electrophotographic photosensitive drum and the charging roller. The charging device according to claim 1, further comprising: 4. A developing device for developing an electrostatic latent image formed on an electrophotographic photosensitive drum using a developer, wherein: a developing roller disposed with a gap from the electrophotographic photosensitive drum; A gap ensuring member provided coaxially with the developing roller at both ends of the developing roller and contacting the electrophotographic photosensitive drum to secure the gap; and supporting the developing roller at a swing center parallel to the electrophotographic photosensitive drum. A shaft coupling provided on the swing axis for receiving the drive input of the developing roller; and urging the support member to bring the gap ensuring member into contact with the electrophotographic photosensitive drum. Pressurizing means,
Pressurizing means provided on the side opposite to the shaft joint with respect to the longitudinal direction of the developing roller and outside the gap ensuring member; and the pressurizing means is on the side opposite to the side with the shaft joint. A developing device provided only in the developing device. 5. When viewed from the direction of the swing axis of the developing device, the pressing position of the pressing means is perpendicular to the line connecting the contact point between the electrophotographic photosensitive drum and the gap ensuring member and the center of swing. 5. The developing device according to claim 4, wherein the two areas divided by the dashed line are located on an area closer to a contact point between the electrophotographic photosensitive drum and the gap ensuring member. 6. A supporting member supported so that a swing center on a side provided with the pressing means is allowed to move in a direction substantially parallel to a direction connecting respective centers of the electrophotographic photosensitive drum and the developing roller. The developing device according to claim 4, further comprising: 7. A process cartridge detachable from an image forming apparatus main body, comprising: a, an electrophotographic photosensitive member, a charging roller disposed with a gap from the electrophotographic photosensitive drum and carrying magnetic particles; A gap ensuring member provided coaxially with the charging roller at both ends of the roller and contacting the electrophotographic photosensitive drum to secure the gap; and supporting the charging roller at a swing center parallel to the electrophotographic photosensitive drum. A support member, a shaft coupling provided on the swing axis for receiving the drive input of the charging roller, and urging the support member to bring the gap ensuring member into contact with the electrophotographic photosensitive drum. Pressurizing means,
Pressurizing means provided on the side opposite to the shaft coupling with respect to the longitudinal direction of the charging roller and outside the gap ensuring member; and A process cartridge provided only in the process cartridge. 8. When viewed from the direction of the swing axis of the charging device, the pressing position of the pressing means is perpendicular to the line connecting the contact point between the electrophotographic photosensitive drum and the gap ensuring member and the swing center. 8. The process cartridge according to claim 7, wherein the two areas divided by the dashed line are located on an area closer to a contact point between the electrophotographic photosensitive drum and the gap ensuring member. 9. A support member supported so that a swing center on a side provided with the pressing unit is allowed to move in a direction substantially parallel to a direction connecting centers of the electrophotographic photosensitive drum and the charging roller. The process cartridge according to claim 7, further comprising: 10. A process cartridge detachable from an image forming apparatus main body, comprising: a, an electrophotographic photoreceptor, a developing roller disposed with a gap from the electrophotographic photoreceptor drum, and two ends of the developing roller. A gap ensuring member provided coaxially with a developing roller and ensuring the gap by contacting the electrophotographic photosensitive drum; a supporting member supporting the developing roller at a swing center parallel to the electrophotographic photosensitive drum; A shaft coupling provided on the swing axis for receiving a drive input to the developing roller; and a pressing unit for urging the support member to bring the gap ensuring member into contact with the electrophotographic photosensitive drum. So,
Pressurizing means provided on the side opposite to the shaft joint with respect to the longitudinal direction of the developing roller and outside the gap ensuring member; and the pressurizing means is on the side opposite to the side with the shaft joint. A process cartridge provided only in the process cartridge. 11. When viewed from a swing axis direction of the developing device,
The pressurizing position of the pressurizing means is two regions divided by a perpendicular bisector of a line connecting the contact point between the electrophotographic photoreceptor drum and the gap ensuring member and the swing center. The process cartridge according to claim 10, wherein the process cartridge is located in a region closer to a contact point with the gap ensuring member. 12. A supporting member which is supported so that a swing center on a side provided with the pressing means is allowed to move in a direction substantially parallel to a direction connecting respective centers of the electrophotographic photosensitive drum and the developing roller. 11. The method according to claim 10, wherein:
2. The process cartridge according to 1.