JP2001249525A - Image forming device and processing cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease running cost of an image forming device. SOLUTION: In the device, gap rolls are attached to both end parts of an electrifying roll 4, both end parts of the electrifying roll 4 are abutted to both end parts of a driving roll 2 where a belt photoreceptor 1 is hung and installed and a gap with a width that is greater than diameter of a toner particle is formed between the belt photoreceptor 1 and the electrifying roll 4. Then, toner is recovered by a developing roll 6 by being passed through the gap when the toner that is recovered by electrostatic force of a cleaning roll 5 is attached to the photoreceptor belt 1 again. As a result, recycling of the toner is made possible and the running cost is brought down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus applied to a facsimile machine, a copying machine, a printer, or a multifunction machine combining these functions, and to be mounted on such an image forming apparatus. Regarding the process cartridge.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a corona discharge type charging apparatus for a photosensitive member has been applied. However, in recent years, problems such as environmental considerations and easiness of recycling have been considered. To solve the problem, an image forming apparatus using a charging method using a charging roller has appeared.

The charging roller is of a brush type or a solid type. The charging roller is brought into contact with a photoreceptor, and by applying a bias to the charging roller, the charging roller is rotated along with the rotation of the photoreceptor. The photoreceptor can be charged by the occurrence of a discharge phenomenon in the gap near the contact portion between the charging roller and the photoreceptor.

[0004] Further, the technology for producing a toner having a shape close to a true sphere, called a polymerized toner, has been improved. By using this polymerized toner, the transfer rate of the toner on the photoreceptor to the paper has been dramatically improved. It has become possible to reduce the amount of toner remaining on the photoreceptor surface after passing through the transfer device. In recent years, research has been conducted to realize an image forming apparatus without a cleaning device for collecting residual toner on the surface of the photoconductor.

Conventionally, some processing means for forming an image by an electrophotographic process have been unitized to facilitate maintenance. In recent years, however, there has been a demand for further energy saving and resource saving. The members that can be used to respond are being reused.

[0006]

As described above, in recent years, there has been a demand for realizing an image forming apparatus that is environmentally friendly and has high recyclability. Such a demand has been met without increasing running costs. Realization is a problem. Methods for reducing the running cost include reducing the number of processing means for forming an image by an electrophotographic process, improving the life of the main parts of the processing means, and further reducing waste of toner. can give. Broadly speaking, it can be said that reducing the recycling cost also contributes to the running cost.

[0007] It is an object of the present invention to provide an image forming apparatus and a process cartridge which meet such demands and realize a reduction in running cost.

[0008]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a photoreceptor; and a charging roller for charging the surface of the photoreceptor. In the image forming apparatus, the charging roller is disposed close to the photoconductor so that a gap larger than the toner particle diameter is formed. With this configuration, a gap larger than the toner diameter is formed between the charging roller and the photoconductor, so that when the residual toner on the surface of the photoconductor passes through the charging roller, the toner does not adhere to the charging roller. Then, the toner is sent to the developing device side, and is collected by the developing device if the toner has adhered to the outside of the electrostatic latent image area. Sent to the side.

According to a second aspect of the present invention, the diameter of both ends of the charging roller is configured to be larger than the diameter of a central portion, and both ends of the charging roller are located in areas other than the image forming area of the photoconductor. When the contact is made, the gap is formed between a surface of the image forming area of the photoconductor and a central portion of the charging roller.

The invention according to claim 3 is characterized in that cylindrical members are attached to both ends of the charging roller, and the diameter of both ends of the charging roller is made larger than the diameter of the central part.

The invention according to claim 4 is characterized in that a tape is wound around both ends of the charging roller so that the diameter of both ends of the charging roller is larger than the diameter of the central portion.

The invention according to claim 5 is characterized in that a paint is applied to both ends of the charging roller so that the diameter of both ends of the charging roller is larger than the diameter of the center.

According to a sixth aspect of the present invention, the photoreceptor is a belt, and at least one of a plurality of rollers on which the photoreceptor is stretched is longer than the width of the photoreceptor. The photosensitive member is brought into contact with the center of the roller, and both ends of the charging roller are brought into contact with both ends of the roller.

According to a seventh aspect of the present invention, the photosensitive member is a belt member, and at least one of a plurality of rollers on which the photosensitive member is stretched is longer than the width of the photosensitive member. The diameter of both ends of the roller located outside the area of the photoconductor was made larger than the diameter of the area of the area of the photoconductor, and both ends of the charging roller were brought into contact with both ends of the photoconductor. In this case, the gap is formed between a surface of the image forming area of the photoconductor and the charging roller.

According to an eighth aspect of the present invention, the thickness of the both ends of the photoconductor outside the image forming area is made larger than the thickness of the image forming area of the photoconductor, and both ends of the charging roller are formed. When the part is brought into contact with both ends of the photoconductor,
The gap is formed between the surface of an image forming area of the photoconductor and the charging roller.

According to the first to eighth aspects of the present invention, a gap can be formed at the same time when the charging roller is brought into contact with the photosensitive member.

According to a ninth aspect of the present invention, a cleaning roller for moving and collecting the toner on the surface of the photoconductor by electrostatic attraction is provided upstream of the charging roller in the rotation direction of the photoconductor. And With this configuration, it is possible to collect the toner remaining without being transferred to the paper, and return the collected toner to the photoconductor by changing the polarity of the potential difference between the photoconductor and the cleaning roller. The toner can be collected by the developing device by passing through the gap between the roller and the photoconductor.

According to a tenth aspect of the present invention, a toner adheres to an electrostatic latent image formed on the photosensitive member in contact with the photosensitive member at a position downstream of the photosensitive member in the rotation direction with respect to the charging roller. A developing roller is provided to switch the polarity of the potential difference between the cleaning roller and the photoconductor at a time other than the time of image formation so that the collected toner adheres to the photoconductor, and the toner is collected by the developing roller. A control means for performing control is provided. With this configuration, the toner can be reused.

According to a still further aspect of the present invention, a toner adheres to an electrostatic latent image formed on the photosensitive member, in contact with the photosensitive member, on the downstream side in the rotation direction of the photosensitive member with respect to the charging roller. A developing roller for causing the toner to adhere to the developing roller by electrostatic attraction and collecting the toner adhering to areas other than the area of the electrostatic latent image on the photoconductor, and developing and developing the electrostatic latent image on the photoconductor. The cleaning of the photoconductor is performed simultaneously at a contact portion between the developing roller and the photoconductor. With this configuration, it is not necessary to provide a device for collecting the toner remaining without being transferred.

According to a twelfth aspect of the present invention, the toner has a circularity of 0.98 or more. With such a configuration, it is possible to improve the transfer rate of the toner to the sheet, and it is possible to configure an image forming apparatus without cleaning.

According to a thirteenth aspect of the present invention, there is provided the image forming apparatus according to the ninth aspect, wherein the photosensitive member, the charging roller,
The developing roller and the cleaning roller are integrated so as to be detachable from the apparatus body. With such a configuration, a process cartridge capable of reusing the toner is configured.

The invention according to claim 14 is the invention according to claim 11
In the image forming apparatus according to the present invention, the photosensitive member, the charging roller, and the developing roller are integrated so as to be detachable from the apparatus main body. With such a configuration, the process cartridge without the cleaning roller according to the invention of claim 13 is configured, and can be configured to be mountable to an image forming apparatus to which the process cartridge of the invention of claim 13 is mounted.

According to a fifteenth aspect of the present invention, the photosensitive member is a belt member, and two rollers for stretching the photosensitive member are provided, and a forward path on the photosensitive member reciprocating between the two rollers is provided. Wherein the charging roller and the developing roller are disposed. With such a configuration, the size of the process cartridge and the size of the image forming apparatus in which the process cartridge is mounted can be reduced.

The invention according to claim 16 is a photoconductor,
A developing roller for attaching toner to the electrostatic latent image formed on the photoconductor, and in an image forming apparatus for forming an image by an electrophotographic process, the developing device includes a developing roller in contact with the photoconductor; A toner layer thickness regulating roller for regulating the thickness of the toner layer formed on the surface of the developing roller in contact with the developing roller, wherein the toner layer thickness regulating roller is pressed against the developing roller by its own weight. And With this configuration,
It is possible to apply pressure uniformly to the surface of the developing roller.

The invention according to claim 17 is characterized in that the contact position between the toner layer thickness regulating roller and the developing roller is changed at regular intervals. With such a configuration, the toner layer regulating member having the function of regulating the amount of toner on the developing roller and charging the toner at a constant level has been conventionally used because the contact point with the developing roller has always been the same. Although the filming has occurred, a new surface comes into contact with the film at regular intervals, so that the temperature rise due to frictional heat is suppressed, and filming can be prevented.

The invention according to claim 18 is characterized in that the toner layer thickness regulating roller is rotated at a linear velocity ratio of 1 or less with respect to the developing roller. With this configuration, a new surface is constantly in contact with the developing roller, so that a temperature rise due to frictional heat is suppressed, and filming can be prevented.

According to a nineteenth aspect of the present invention, there is provided an image forming apparatus having a belt-shaped photosensitive member and a plurality of rollers for stretching and circulating the photosensitive member and performing image formation by an electrophotographic process. One of the plurality of rollers is arranged at a position where the sheet after image transfer is separated from the photoreceptor, and the roller diameter is larger than 8 mm and 16 mm.
It is characterized by being set smaller. With this configuration, by setting the roller diameter to be smaller than 16 mm, the paper can be separated from the belt-shaped photoconductor without using the conventional paper removing device, and the roller diameter is set to 8 mm. By setting a larger value, the strength of the roller itself is maintained, and as a result, the durability of the photoconductor can be maintained.

According to a twentieth aspect of the present invention, a supporting member for simultaneously supporting a plurality of rollers for forming an image by an electrophotographic process and a case for accommodating the supporting member to which the rollers are attached are integrated. And is configured to be detachable from the image forming apparatus main body. With this configuration, the case side and the replacement part side can be divided into two in a short time.

According to a twenty-first aspect of the present invention, a plurality of rollers for stretching a belt-shaped photosensitive member in a roller member supported by the support member, a charging roller for charging the photosensitive member, the photosensitive member And a developing roller for attaching toner to the electrostatic latent image.

The invention according to claim 22 is characterized in that a roller body having the same life is integrally attached to the support member. With this configuration, it is possible to omit the operation of removing the roller that can be used for a long time,
It is possible to improve work efficiency related to component replacement.

According to a twenty-third aspect of the present invention, the developing member is provided on the supporting member, a toner supply roller for supplying toner to the developing roller, and a toner formed on the surface of the developing roller in contact with the developing roller. It is characterized in that a unit body is integrated with a toner layer thickness regulating roller for regulating the layer thickness. With this configuration, it is possible to remove the components related to the development process from the unit of the replacement component removed from the case at a time, thereby improving workability of recycling.

The invention according to claim 24 is characterized in that a toner accommodating portion for accommodating new toner to be supplied to the developing roller is formed in the case body, and an agitator for agitating the toner is provided in the toner accommodating portion. And

The invention according to claim 25 is the invention according to claim 20.
The invention is characterized in that the image forming apparatus has the process cartridge according to any one of (1) to (24) and forms an image by an electrophotographic process.

[0034]

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

FIG. 1 is an explanatory view showing a main part of an image forming apparatus according to a first embodiment of the present invention. Reference numeral 1 denotes a belt photoreceptor; And a driving roller 2
Has a configuration in which conductive rubber is wound around a cored bar and its outer periphery. Reference numeral 3 denotes a driven roller that supports the belt photoconductor 1 together with the driving roller 2 and stretches the belt photoconductor 1. The driven roller 3 is composed of a metal roller, a metal roller having rubber wrapped around its outer periphery, a plastic roller, or the like, and has a diameter in a range from 8 mm to 16 mm. Reference numeral 4 denotes a charging roller.
Is a configuration in which conductive rubber is wound around the outer periphery of a cored bar.

Reference numeral 5 denotes a cleaning roller. The cleaning roller 5 has a structure in which conductive rubber is wound around a cored bar. Reference numeral 6 denotes a developing roller of a contact one-component developing system. The developing roller 6 has a configuration in which a surface coat layer made of a melamine resin or the like is formed on a metal tube, and is in contact with the belt photoreceptor 1 at a constant pressure. are doing. Reference numeral 7 denotes a toner supply roller. The toner supply roller 7 has a configuration in which a sponge member is wound around a cored bar, and is in contact with the developing roller 6 in a state where the toner roller is bitten by about 0.5 mm. 8 denotes a doctor roller,
The doctor roller 8 has a structure in which an elastic member is wound around a cored bar and its outer periphery. The doctor roller 8 comes into contact with the developing roller 6 by its own weight, so that the entire surface of the doctor roller 8 can be uniformly contacted at the point of contact with the developing roller 6. Reference numeral 9 denotes an agitator for stirring the toner in the toner tank 10a, and the agitator 9 is formed of a metal round bar. Note that the agitator 9 does not have any problem even if it is an integrally molded product of plastic. Reference numeral 10 denotes a case. The case 10 is provided with a toner tank 10a. The case 10 includes a belt photoreceptor 1, a driving roller 2, a driven roller 3, a charging roller 4, a cleaning roller 5, a developing roller 6, a toner By accommodating the supply roller 7, the doctor roller 8, and the agitator 9, a process cartridge detachable from the image forming apparatus main body is formed.

In the case 10, the driven roller 3 is disposed below the driving roller 2 with reference to the position of the driving roller 2, the charging roller 4 is disposed above the driving roller 2, and the driving roller 2 is disposed on one side. The developing roller 6 is arranged so as to contact the belt photoconductor 1 stretched between the roller and the driven roller 3, and contacts the belt photoconductor 1 in contact with the driving roller 2 on the other side. The cleaning roller 5 is disposed at the position. Here, for the sake of convenience in the following description, the side where the developing roller 6 is located with respect to the line connecting the rotation shafts of the driving roller 2 and the driven roller 3 will be called the right side, and the cleaning roller 5 will be called the left side.

Reference numeral 11 denotes a transfer roller abutting on the belt photoreceptor 1 provided on the driven roller 3;
Reference numeral 3 denotes a registration roller that conveys the paper conveyed by the paper feeding device 12 to the contact portion between the transfer roller 11 and the belt photoreceptor 1 in a timely manner. Reference numeral 14 denotes a fixing device that presses / heats the paper on which the toner image has been transferred. The device is shown.

FIG. 2 is a perspective view including a partial cross section of the process cartridge according to the embodiment of the present invention, wherein 15 is a front support plate, and 16 is a rear support plate. The front support plate 15 and the rear support plate 16 are symmetrical, and include one end of a rotation shaft of a drive roller 2, a driven roller 3, a charging roller 4, a cleaning roller 5, a developing roller 6, a toner supply roller 7, and a doctor roller 8. Is the front support plate 15, and the other end is the rear support plate 1.
6 supported. Further, stay members 17 and 18 are disposed on the left and right sides of the front support plate 15 and the rear support plate 16 with respect to the position where the charging roller 4 is supported, and the stay members 17 and 18 allow the front support plate 15 and the rear support plate 16 to be positioned. Are connected.

FIG. 3 is a perspective view showing the support structure of each roller by the front support plate and the rear support plate of FIG.

A bearing 19 of the drive roller 2 is fixed to the center of the front support plate 15 and the rear support plate 16.
Bearing 19 on front support plate 15 and rear support plate 16
A long hole 20 extending vertically is formed below the
The bearing 21 of the driven roller 3 follows the slot 19
A spring 22 is provided between the upper end of the elongated hole 20 and the bearing 21, and a belt photosensitive member is interposed between the driven roller 3 and the driving roller 2 by the bias of the spring 22. 1 is installed. Further, a vertically extending elongated hole 23 is formed above the bearing 19 in the front support plate 15 and the rear support plate 16, and a bearing 24 of the charging roller 4 is slidably mounted in the elongated hole 23. A spring 25 is provided between the upper end of the elongated hole 23 and the bearing 24, and by the bias of the spring 25, both ends of the charging roller 4 are brought into contact with the driving roller 2 via the belt photoreceptor 1. Will be maintained.

The support structure for the cleaning roller 5 and the developing roller 6 is the same, and elongated holes 26 and 27 extending in the left-right direction are formed. The bearing 29 of the developing roller 6 is slidably mounted.
A spring 30 is provided between the left end of the long hole 6 and the bearing 28, and a spring 31 is provided between the right end of the elongated hole 27 and the bearing 29. 5 and developing roller 6
The contact state between the belt and the photoreceptor 1 is maintained.

Gap rollers 3 are provided on both sides of the charging roller 4.
The gap rollers 32 are cylindrical members having a thickness of 0.01 mm to 0.1 mm. When the charging roller 4 is installed on the front support plate 15 and the rear support plate 16 with the gap rollers 32, 32 attached, the gap roller 32 contacts both ends of the drive roller 2 via the belt photoreceptor 1. Therefore, the charging roller 4 has a thickness of 10 μm to 1 μm between the central portion of the charging roller 4 and the belt photoreceptor 1.
The state where the gap of 00 μm is formed is maintained. Here, in the present embodiment, the size of the gap is set to 10 μm.
Although it is set to m to 100 μm, the size of the gap is set to be larger than the particle size of the toner to be used.

FIG. 4 is a perspective view showing the configuration around the doctor roller. Reference numeral 33 denotes a support plate which is disposed on both sides of the doctor roller 8 and rotatably supports the doctor roller 8.
Is a rotating shaft which is installed in parallel with the doctor roller 8 and is rotatably mounted on the support plates 33, 33;
3, a support plate that supports both ends of the rotary shaft 34, 36 is a transmission gear fixed to one end of the rotation shaft of the doctor roller 8, 37 is an intermediate gear that meshes with the transmission gear 36, Reference numeral 38 denotes a drive gear that meshes with the intermediate gear 37 and transmits the rotation of a drive source (not shown) to the intermediate gear 37.

FIG. 5 is a perspective view showing a structure around a side portion of the developing roller. Numeral 39 denotes a bearing for supporting the rotating shaft of the toner supply roller 7, and numeral 40 is formed on the support plate 35, and the bearing 39 is slidable. The supporting hole in the bearing, 41 is the bearing 3
9 and one end of the long hole 40, and the bearing 39
FIG. 4 shows a spring for holding a state in which it is in contact with the other end of the long hole 40.

The bearing 29 of the developing roller 6 is fixed to the side of the elongated hole 40 in the support plate 35.
9, the rotating shaft of the developing roller 6 is attached to the supporting plates 35, 3
5, the end of the rotating shaft 34 is fixed, and the rotating shaft of the toner supply roller 7 is attached to the bearing 39, so that the developing roller 6, the toner supply roller 7 and the doctor roller 8 are fixed.
Are integrated. At this time, the doctor roller 8 can move up and down around the rotation shaft 34, and is in contact with the developing roller 6 while applying pressure by its own weight. The rotation of the developing roller 6 and the doctor roller 8 is transmitted from the same driving source, and the developing roller 6 and the doctor roller 8 rotate in the same direction. Therefore, the contact portion between the developing roller 6 and the doctor roller 8 moves in the counter direction, and the charging of the toner and the regulation of the toner pressure are performed at the contact portion. A rotational force is applied to the doctor roller 8 at regular intervals, and the contact surface with the developing roller 6 is changed.

Then, by attaching the bearing 29 to the front support plate 15 and the rear support plate 16, the developing roller 6, the toner supply roller 7 and the doctor roller 8 are simultaneously mounted on the front support plate 15 and the rear support plate 16, FIG.
A unit as shown in FIG.

Further, the unit constructed as shown in FIG. 3 is inserted into the case 10, and both sides are screwed on both sides of the case 10, and new toner is stored in the toner tank 10a and hermetically sealed. Thus, a process cartridge as shown in FIG. 2 is configured. Here, the toner stored in the toner tank 10a is a so-called polymerized toner, and is a substantially true sphere having a circularity of 0.98 with respect to the conventional product of 0.93.

Next, the operation of the image forming apparatus according to this embodiment will be described with reference to FIGS.
By rotating a rotation drive source (not shown), the rollers 2, 3, 4, 5, 6, 7, 11 and the agitator 9 rotate, and the belt photoreceptor 1 circulates in the direction shown by the arrow in FIG. As shown in FIG. 6, the driving roller 2 is grounded, and the charging roller 4, the cleaning roller 5, the developing roller 6, and the transfer roller 11 are connected to respective power supplies. A bias of -200 V is applied to the toner supply roller 7 and the doctor roller 8.

When a bias is applied to the charging roller 4, a discharge phenomenon occurs in a gap between the charging roller 4 and the belt photosensitive member 1, and the surface of the belt photosensitive member 1 becomes -8.
It is uniformly charged to 00V. When the surface of the charged belt photoreceptor 1 is exposed by the optical writing device A, the potential of the exposed portion changes to -100 V, and an electrostatic latent image is formed.

By applying a bias to the developing roller 6, the surface potential of the developing roller 6 becomes higher than −800 V and lower than −100 (for example, −200 V). , Toner charge by the doctor roller 8 and regulation of toner layer thickness, a toner layer having a uniform thickness is formed by negatively charged toner. And the belt photoreceptor 1
The electrostatic latent image formed on the belt photoreceptor 1 and the developing roller 6
The toner on the developing roller 6 adheres to the electrostatic latent image when passing through the contact portion with the toner, and a toner image is formed on the belt photoconductor 1;
It is sent to the transfer roller 11. At this time, the surface potential of the transfer roller 11 is set to be higher than -100 V (for example, +1
00V).

The registration roller 13 conveys the sheet at the timing when the leading edge of the sheet fed from the sheet feeding device 12 and the leading edge of the toner image on the belt photosensitive member 1 coincide with each other. The toner image moves to the transfer roller 11 side at the contact portion between the toner image and the belt photoconductor 1, and as a result, the toner image is transferred to the paper. The toner on the sheet to which the toner image has been transferred is fused to the sheet by heat and pressure by the fixing device 14, whereby an image is recorded on the sheet.

On the other hand, the toner remaining at the contact portion between the transfer roller 11 and the belt photoreceptor 1 without moving to the transfer roller 11 side moves to the cleaning roller 5 side. At this time, the surface potential of the cleaning roller 5 is changed to the transfer roller 11.
Higher than the surface potential of the belt photoreceptor 1 after passing (for example,
(+100 V to +500 V). As a result, the residual toner moves to the cleaning roller 5 and is collected.

After the end of a series of image forming operations, the bias applied to the cleaning roller 5 and the developing roller 6 is switched so that the surface potential of the cleaning roller 5 is lower than the charging potential of the belt photosensitive member 1 (for example, -100 V to -500).
V) The surface potential of the developing roller 6 is set higher than the charging potential of the belt photoconductor 1. As a result, the toner on the cleaning roller 5 adheres to the belt photoconductor 1 again, and the toner on the belt photoconductor 1 that has reattached is collected by the developing roller 6.

After completion of the toner collecting operation, the driven roller 2 is lifted upward by operating a solenoid (not shown), and the tension applied to the belt photoreceptor 1 is released. Thereafter, when the image forming operation is performed, The driven roller 2 is lowered by operating the solenoid to apply tension to the belt photoconductor 1, and the belt photoconductor 1 is stretched between the driving roller 2 and the driven roller 3.

The timing of returning the toner collected by the cleaning roller 5 to the developing roller 6 is not limited to after the end of a series of image forming operations, but may be determined when the power is turned on or at a predetermined time interval. It may be performed when it is confirmed and unused.

With this configuration, the following operation and effect can be obtained.

First, by providing a gap larger than the toner particle diameter between the belt photoreceptor 1 and the charging roller 4, the toner not collected by the cleaning roller 5 or the toner returned from the cleaning roller 5 to the developing roller 6 Since the charging roller 4 can be prevented from being soiled, the surface of the belt photoreceptor 1 can be uniformly charged. In addition, since the charging roller 4 is not in contact with the belt photoconductor 1, the life of the charging roller 4 can be improved.
Running costs can be reduced.

Also, an elastic roller is employed as the doctor roller 8, and the doctor roller 8 is disposed above the developing roller 6 so as to be in pressure contact with the developing roller 6 by its own weight. It is possible to make contact in the entire direction. That is, the developing roller 6 is configured to receive a uniformly distributed load, the shaft deflection of the doctor roller 8 is reduced as compared with the configuration in which a load is applied from the end points of the support at both ends, and a toner layer having a uniform thickness can be formed. Further, by adopting a hard material having a low friction coefficient as the surface layer material of the doctor roller 8, it is possible to extend the life. Specifically, a fluorinated resin or the like is optimal.

Further, the doctor roller 8 is operated intermittently to
By moving the contact surface with the developing roller at regular intervals, filming can be prevented from occurring on the roller surface.
The gear ratio may be set so that the ratio of the linear speed of the doctor roller 8 to the linear speed of the roller becomes 1 or less, and the doctor roller 8 may be rotated at a low speed to shift the contact surface little by little. By doing so, it is possible to suppress the generation of frictional heat and thereby further reduce filming. When the linear velocity is increased, not only the filming becomes easy, but also a toner layer having a constant thickness becomes difficult to be formed due to the influence of driving torque, the influence of component accuracy (fluctuation), the influence of surface properties, and the like. Therefore, it is desirable that the linear velocity ratio be 1 or less.

By returning the toner collected by the cleaning roller 5 to the developing roller 6, the amount of unused toner is reduced, and the running cost can be reduced. In particular, since the toner used is a polymerized toner, and its circularity is 0.98, which is almost a perfect sphere, compared to 0.93 of the normally used toner, the conventional transfer roller 1
In this case, the occurrence of a missing character image, which has occurred when using No. 1, is reduced. This is considered to be because the toner became hard to be crushed due to the fact that it was close to a true sphere, and it was hard to re-adhere to the belt photoconductor 1. Further, by using the toner having a shape close to a true sphere, the transfer rate to paper is greatly improved, and the transfer rate of about 80% in the past is increased to 95% or more. Is reduced, and good cleaning performance is maintained. In addition, if the degree of circularity of the toner is improved, a configuration in which the cleaning roller 5 is not required is also possible.

Further, by setting the diameter of the driven roller 3 of the belt photoreceptor 1 to 8 mm or more and 16 mm or less, the durability of the belt photoreceptor 1 is maintained and the paper can be separated from the belt photoreceptor 1. become. This is because if it is 16 mm or less, most of the paper can be separated from the photoreceptor without using a static eliminator, and if it is 8 mm or more, the durability of the belt photoreceptor 1 is maintained. is there.

In the process cartridge, the charging roller, the cleaning roller, the belt photoreceptor, the developing roller, the doctor roller, and the replenishing roller, which are replacement parts, are integrated so as to be detachable from the case 10, so that the case 10 side The replacement part is divided into two parts in a short time,
It is possible to greatly improve the case cleaning performance and significantly reduce the recycling cost.

Further, according to the above-described embodiment, the rollers for the developing process are integrated and attached to the front support plate 15 and the rear support plate 16 for the replacement parts. They may be integrated to be detachable. As a result, there is no need to remove a long-usable one, and the replacement work efficiency is improved.

Further, according to the above-described embodiment, the toner is recovered from the belt photoconductor 1 and the toner is reattached to the belt photoconductor 1 by switching the surface potential of the cleaning roller 5. Here, when the toner is collected, the surface potential of the cleaning roller 5 is set to −100.
It is necessary to set the surface potential to be higher than V and to set the surface potential to be lower than -800 V when the toner is re-attached. Therefore, the surface potential at the time of toner collection is
For example, control may be performed such that the surface potential is temporarily switched to −400 V and then set to a surface potential lower than −800 V. In addition,
In order for the toner on the cleaning roller 5 to be collected by the developing roller 6, the surface potential of the cleaning roller 5 should be lower and the surface potential of the developing roller 6 should be higher than the surface potential of the belt photoconductor 1. To fit
The bias applied to the charging roller 4, the cleaning roller 5, and the developing roller 6 may be switched.

As described above, the circularity of the toner is 0.98, which is 0.98 of the normal toner.
The transfer ratio to paper is dramatically improved by using a toner having a substantially spherical shape.
Also, a configuration that does not need to be performed is also possible. Next, a cleaningless image forming apparatus will be described as a second embodiment.

In the image forming apparatus according to the second embodiment, the cleaning roller 5 according to the image forming apparatus according to the first embodiment shown in FIG. 1 is omitted.

Next, the operation will be described. The process from charging the belt photoreceptor 1 to transferring the toner image to the sheet is the same as the operation of the image forming apparatus of the first embodiment shown in FIG.

At the contact portion between the belt photosensitive member 1 and the transfer roller 11, the toner remaining on the belt photosensitive member 1 without being transferred to the paper passes through the gap between the belt photosensitive member 1 and the charging roller 4. Then, the belt photoreceptor 1 is uniformly charged by the charging roller 4 and an electrostatic latent image is formed by optical writing. At this time, if the area where the toner adheres becomes the electrostatic latent image area, the developing roller 6 As a result, the toner is overwritten, and if the toner is outside the electrostatic latent image area, the electrostatic attraction in the direction of the developing roller 6 is applied to the toner by the potential difference between the charging potential of the belt photoreceptor 1 and the surface potential of the developing roller 6. The toner moves from the belt photoreceptor 1 to the developing roller 6 and is collected. That is, the developing roller 6 also has the function of the cleaning roller 5.

According to the second embodiment configured as described above, the cleaning roller 5 can be eliminated, so that the number of components can be reduced and the manufacturing cost can be reduced accordingly. In addition, since the power supply for driving the cleaning roller 5 and applying the bias can be omitted, the running cost can be reduced as a result.
Further, by eliminating the cleaning roller 5, the configuration on the left side in FIG. 1 is simplified, image formation is performed on the outward path from the charging roller 4 to the transfer roller 11 in the belt photoreceptor 1, and the transfer roller 11 to the charging roller In the return path up to 4, there is no longer any device for processing the belt photoreceptor 1, and the process cartridge and the image forming apparatus can be reduced in size. As long as the process cartridge shown in FIG. 2 can be mounted thereon, the process cartridge according to the above-described second embodiment can be mounted.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described configuration.
For example, in the above-described configuration, the surface of the charging roller 4 has elasticity, but the area of the charging roller 4 corresponding to the image forming area on the belt photoreceptor 1 is non-contact. May be configured. In this case, a gap can be formed between the belt photoreceptor 1 and the charging roller 4 by wrapping a tape around both sides of the charging roller 4 or by applying a thicker coating for forming a protective layer. Further, the length of the driving roller 2 is made longer than the width of the belt photoconductor 1, and the diameter of both side portions of the driving roller 2 protruding from both ends of the belt photoconductor 1 is added to the thickness of the belt photoconductor 1. The belt photoreceptor 1 and the charging roller 4 can be made larger by about 0.01 mm to 0.1 mm.
Can be formed between them. Further, when the durability of the belt photoconductor 1 itself is excellent, the gap can be formed by increasing the thickness of both ends of the belt photoconductor 1 by about 0.01 mm to 0.1 mm.

According to the above-described embodiment, a belt-shaped photosensitive member is used as the photosensitive member. However, if the developing roller 6 has an elastic surface, a drum-shaped photosensitive member is used. You may.

[0073]

As described above, according to the present invention, the toner remaining on the photoreceptor without being transferred is reused, the life of the developing roller and its peripheral members is extended, and parts are replaced in the process cartridge. In this case, it is possible to improve the working efficiency at the time of printing, and as a result, it is possible to reduce the running cost of the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a main part of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view including a partial cross section of the process cartridge according to the embodiment of the present invention.

3 is a perspective view showing a support structure of each roller by a front support plate and a rear support plate of FIG. 2;

FIG. 4 is a perspective view showing a configuration around a doctor roller.

FIG. 5 is a perspective view showing a configuration around a side portion of a developing roller.

FIG. 6 is an explanatory diagram showing an example of a bias voltage applied to each process means for performing image recording.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 belt photoreceptor 2 drive roller 3 driven roller 4 charging roller 5 cleaning roller 6 developing roller 7 toner replenishment roller 8 doctor roller 9 agitator 10 case 11 transfer roller 12 paper feed device 13 registration roller 14 fixing device 15 front support plate 16 rear support Plates 17, 18 Stay members 19, 21, 24, 28, 29, 39 Bearings 20, 23, 26, 27, 40 Slots 22, 25, 30, 31, 41 Spring 32 Gap rollers 33, 35 Support plate 34 Rotation Shaft 36 Transmission gear 37 Intermediate gear 38 Drive gear

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/00 350 G03G 15/00 556 2H077 (72) Inventor Yasuhiro Kawashima 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Company (72) Inventor Hideki Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh Company (72) Kenichi Kawabata 1-3-6 Nakamagome, Ota-ku, Tokyo Stock F-term (reference) in Ricoh Company 2H003 BB11 CC05 EE11 EE19 2H005 AA15 2H035 CB06 CD14 CF02 CG03 2H068 AA55 FA27 2H071 BA04 BA13 BA27 CA02 CA05 DA06 DA08 DA13 DA16 2H077 AA37 AD02 AD06 AD14 AD35 BA01 EA11 EA15

Claims (25)

[Claims] 1. An image forming apparatus comprising: a photosensitive member; and a charging roller for charging the surface of the photosensitive member, wherein the image forming apparatus forms an image by an electrophotographic process. An image forming apparatus, which is arranged close to a large gap. 2. A configuration in which the diameter of both ends of the charging roller is configured to be larger than the diameter of a central portion, and when both ends of the charging roller are brought into contact with an area other than an image forming area of the photoconductor,
The image forming apparatus according to claim 1, wherein the gap is formed between a surface of an image forming area of the photoconductor and a central portion of the charging roller. 3. The image forming apparatus according to claim 2, wherein cylindrical members are attached to both ends of the charging roller, and the diameter of both ends of the charging roller is larger than the diameter of a central portion. . 4. The image forming apparatus according to claim 2, wherein a tape is wound around both ends of the charging roller, and a diameter of both ends of the charging roller is larger than a diameter of a central part. 5. The image forming apparatus according to claim 2, wherein a paint is applied to both ends of the charging roller, and the diameter of both ends of the charging roller is configured to be larger than the diameter of a central portion. . 6. The photoreceptor is a belt member, and at least one of a plurality of rollers on which the photoreceptor is stretched is longer than the width of the photoreceptor. 6. The image forming apparatus according to claim 2, wherein a photosensitive member is brought into contact, and both ends of said charging roller are brought into contact with both ends of said roller. 7. The photoreceptor is a belt member, and at least one of a plurality of rollers on which the photoreceptor is stretched is longer than the width of the photoreceptor. When the diameter of both ends of the located roller is larger than the diameter in the region of the photoconductor, when both ends of the charging roller are brought into contact with both ends of the photoconductor,
The image forming apparatus according to claim 1, wherein the gap is formed between a surface of an image forming area of the photoconductor and the charging roller. 8. The image forming apparatus according to claim 1, wherein the thickness of the both ends of the photoconductor outside the image forming area is larger than the thickness of the image forming area of the photoconductor, and both ends of the charging roller are connected to both ends of the photoconductor. 2. The image forming apparatus according to claim 1, wherein the gap is formed between a surface of an image forming area of the photoconductor and the charging roller when the charging roller is brought into contact with the image forming section. 9. A cleaning roller provided upstream of the charging roller in the rotation direction of the photoconductor relative to the charging roller to move and collect toner on the surface of the photoconductor by electrostatic attraction. The image forming apparatus according to claim 1. 10. A developing roller is provided downstream of the charging roller in a rotation direction of the photoconductor, the developing roller being in contact with the photoconductor and adhering toner to an electrostatic latent image formed on the photoconductor. Control means for controlling the polarity of a potential difference between the cleaning roller and the photoconductor at a time other than the time of formation so that the collected toner adheres to the photoconductor and the developing roller collects the toner. The image forming apparatus according to claim 9, further comprising: 11. A developing roller, which is provided downstream of the charging roller in the rotation direction of the photoconductor and which abuts on the photoconductor and adheres toner to an electrostatic latent image formed on the photoconductor, The toner adhering to areas other than the area of the electrostatic latent image on the photoconductor is adhered to the developing roller by electrostatic attraction and collected, and the development of the electrostatic latent image on the photoconductor and the cleaning of the photoconductor are performed by the method. 2. The method according to claim 1, wherein the step is performed simultaneously in a contact portion between the developing roller and the photoconductor.
An image forming apparatus according to any one of claims 1 to 8. 12. The image forming apparatus according to claim 1, wherein the circularity of the toner is 0.98 or more. 13. A process cartridge according to claim 9, wherein the photosensitive member, the charging roller, the developing roller, and the cleaning roller in the image forming apparatus are integrated to be detachable from the apparatus body. 14. A process cartridge according to claim 11, wherein the photosensitive member, the charging roller, and the developing roller in the image forming apparatus are integrated to be detachable from the apparatus main body. 15. The photoconductor as a belt member, two rollers for stretching the photoconductor are provided, and the charging roller and the developing device are provided on a forward path side of the photoconductor reciprocating between the two rollers. The process cartridge according to claim 14, wherein a roller is disposed. 16. An image forming apparatus, comprising: a photosensitive member; and a developing roller for attaching toner to an electrostatic latent image formed on the photosensitive member, wherein the image forming apparatus forms an image by an electrophotographic process. A developing roller that contacts the photoconductor, and a toner layer thickness regulating roller that contacts the developing roller and regulates a toner layer thickness formed on the surface of the developing roller. An image forming apparatus characterized by being pressed by its own weight. 17. The image forming apparatus according to claim 16, wherein a contact position between the toner layer thickness regulating roller and the developing roller is changed at regular intervals. 18. The image forming apparatus according to claim 16, wherein the toner layer thickness regulating roller is rotated at a linear speed ratio of 1 or less with respect to the developing roller. 19. An image forming apparatus comprising: a belt-shaped photosensitive member; and a plurality of rollers for stretching and circulating the photosensitive member, and forming an image by an electrophotographic process.
An image forming apparatus, wherein one of the plurality of rollers is disposed at a position where a sheet after image transfer is separated from the photosensitive member, and a roller diameter is set to be larger than 8 mm and smaller than 16 mm. 20. A supporting member for simultaneously supporting a plurality of rollers for forming an image by an electrophotographic process, and a case for accommodating the supporting member to which the rollers are attached are integrated into a main body of the image forming apparatus. A process cartridge characterized by being detachable from the process cartridge. 21. A plurality of rollers for extending a belt-shaped photoconductor in a roller body supported by the support member, a charging roller for charging the photoconductor, and a toner on the electrostatic latent image of the photoconductor. 21. The process cartridge according to claim 20, further comprising a developing roller for adhering toner. 22. The apparatus according to claim 2, wherein roller members having the same life are integrally attached to said support member.
22. The process cartridge according to 0 or 21. 23. The developing device according to claim 23, wherein:
A unit body in which a toner supply roller that supplies toner to the developing roller and a toner layer thickness regulating roller that abuts on the developing roller and regulates a toner layer thickness formed on the surface of the developing roller is attached. The process cartridge according to claim 21, wherein 24. The image forming apparatus according to claim 22, wherein a toner storage section for storing new toner to be supplied to the developing roller is formed in the case body, and an agitator for stirring the toner is provided in the toner storage section. Process cartridge. 25. An image forming apparatus, comprising the process cartridge according to claim 20, wherein the image is formed by an electrophotographic process.