JPH10171239A - Image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a deterioration in an image caused by reduction in density due to the degradation of developer and that of an image carrier caused by wearing, when an image forming device is used for a long period. SOLUTION: The image forming device is provided with the image carrier 1, an electrifying member coming into contact with the image carrier, to electrify its surface, a developing container for housing the developer, a developer carrier 3 for carrying the developer in the developing container to the image carrier and gap regulating members 14 which are arranged in both end parts of the developer carrier and come into contact with the image carrier, to regulate the gap between the image carrier and the developer carrier. In such a case, the end parts of the electrifying member 2 come into contact with the same circumference region of the image carrier in which the gap regulating members 14 are in contact with the image carrier 1, so that the image carrier and the developer carrier can draw near each other, in accordance with the wearing of the image carrier by the end parts of the electrifying member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge and an image forming apparatus capable of providing a good image for a long time by properly maintaining a gap between an image carrier and a developer carrier. It is about.

[0002]

2. Description of the Related Art The prior art will be described with reference to FIG. 11 showing an embodiment of an image forming apparatus according to the present invention. As shown in FIG.
Are rotatably supported, and the image carrier 1 is rotatably driven in a direction shown by an arrow a by a driving unit (not shown). A charging roller 2 which is a primary charging device for charging the surface of the image carrier 1 to a uniform potential, and a surface of the image carrier 1 are arranged around a photosensitive drum such as an electrophotographic photosensitive member as the image carrier 1 in order. A developing device 5 for forming a toner image by attaching toner as a developer to an electrostatic latent image formed by a laser beam 12 from an exposure device, and a cleaning device for removing toner remaining on the surface of the image carrier 1. 8 and so on are provided. A transfer device 10 that transfers the toner image on the surface of the image carrier 1 to a transfer material P such as paper by charging or the like is provided below the image carrier 1. The transfer material that has passed through the transfer device is conveyed to a fixing device (not shown), the developed image is fixed on the transfer material, and the transfer material is discharged out of the device by a paper discharge roller (not shown).

As a form, at least the image carrier 1 and the developing device 5 are integrated, and the charging roller 2, the cleaning device 8 and the like are appropriately integrated into a compact cartridge to be detachable from the image forming apparatus main body. There are various modes such as a device in which each of these devices is different, a device in which only the image carrier 1 and the cleaning device 8 are integrated, and a device in which the image carrier 1 is integrated as described above.

The developing device 5 rotates in the direction of arrow b,
A developing sleeve 3 which is a developing carrier for conveying the toner,
An elastic blade 4 for regulating the thickness of the toner coat on the developing sleeve 3, and an SD (sleeve-drum) gap for regulating the gap between the image carrier 1 and the developing sleeve 3 in contact with the image carrier 1. The image forming apparatus has a regulating member 14 provided at both ends of the developing sleeve 3 outside the image area.

The cleaning device 8 includes a cleaning blade 6 supported by a support member 13 for scraping off transfer residual toner from the image carrier 1, a squeeze sheet 7 for collecting the scraped transfer residual toner, It has a container for collecting the residual toner.

In particular, the positional relationship between the charging roller 2 and the SD gap regulating member 14 in the longitudinal direction of the image carrier 1 will be described in detail. As shown in FIG. The charging roller 2 has substantially the same longitudinal length as the charging roller 2, and the charging roller 2 is in contact with the image carrier 1 so as to cover at least the image area G. Accordingly, the SD gap regulating member 14 outside the image area G is in contact with the surface of the image carrier 1 outside the contact position of the charging roller 2.

[0007]

However, in the structure of the above-described conventional example, the life of the process cartridge has been extended from the viewpoint of environmental protection, which is the trend of the times, and the life of the process cartridge has been extended. In recent years, it is difficult to keep up with the prolongation of the life of the member, and mainly at the end of the durable life due to toner deterioration, abrasion deterioration of the image carrier 1 (even though the toner is sufficiently in the developing device), mainly due to the decrease in density. Image degradation may be caused.

[0008] The present invention solves the above problems,
An object of the present invention is to provide a process cartridge and an image forming apparatus in which image deterioration is reduced even in long-term durability life.

[0009]

Means for Solving the Problems To achieve the above object, a first invention according to the present application is directed to an image carrier, a charging member that contacts the image carrier and charges the surface of the image carrier, A developer container that stores the developer, a developer carrier that transports the developer in the developer container toward the image carrier, and an image carrier that is disposed at both ends of the developer carrier and is in contact with the image carrier. An image forming apparatus provided with a gap regulating member for regulating a gap between the image bearing member and the developer carrying member, wherein the gap regulating member has an end of the charging member on the same circumferential area of the image carrier in contact with the image carrier. The parts are abutted.

According to a second aspect of the present invention, there is provided a developing device having at least an image carrier, a developing container for storing the developer, and a developer carrier for transporting the developer in the developing container toward the image carrier. In a process cartridge of an image forming apparatus in which the apparatus is integrally formed as a cartridge, the gap between the image carrier and the developer carrier is regulated by contacting the image carrier provided at both ends of the developer carrier. A gap regulating member that contacts the image carrier on the same circumference of the image carrier in which the gap regulating member is in contact with the image carrier. It is characterized by contact.

A third invention according to the present application is characterized in that the charging member is a charging roller.

A fourth invention according to the present application is characterized in that the surface roughness of the end of the charging roller is larger than that of the center.

A fifth invention according to the present application is characterized in that the charging member is a charging brush.

A sixth invention according to the present application is characterized in that the bristle at the end of the charging brush is longer than that at the center.

A seventh invention according to the present application is characterized in that the flock density at the end of the charging brush is higher than that at the center.

An eighth invention according to the present application is characterized in that the gap regulating member is rotatable together with the developer carrier.

A ninth invention according to the present application is characterized in that the gap regulating member is a fixed member that does not rotate with the developer carrier.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 11 shows the overall configuration of an embodiment of the image forming apparatus according to the present invention.

FIG. 1 shows an embodiment of a main part of the present invention, in which a longitudinal positional relationship among an image carrier 1, a charging roller 2 as a charging member, a developing sleeve 3, and an SD gap regulating member 14 is shown. The configuration of the SD gap regulating member 14 is such that the peripheral surface of the developing sleeve 3 can be freely rotated with the rotation of the developing sleeve or the image carrier 1.

As described above, the edge scraping of the charging roller 2 used in the present invention will be described with reference to FIGS. 5, 6, 7 and 8. FIG.

First, a structure in which a resistance layer 20 is coated on a conductive layer 19 as shown in an enlarged cross-sectional shape of the end of the charging roller 2 in FIG. 5 is generally used. In the shape of the layer 20. The resistance layer 20 is coated on the conductive layer 19 with a film thickness of about several tens to several hundreds μm. When coated, the coating material sags at the ends to have a swollen shape as shown in FIG. .

That is, as shown in FIG. 6, when the charging roller 2 is brought into contact with the image carrier 1, the distance between the image carrier 1 and the charging roller 2 is several μm to several tens μm as indicated by a hatched portion h. A minute gap is always formed even when the roller 2 rotates, and when a high pressure is applied, discharge is always performed in the minute gap h according to Paschen's law. In addition, at locations other than the end portion where the contact is good, both sides of the normal contact portion (image carrier 1 in FIG. 6).
In the section perpendicular to the rotation axis of (1), the discharge is performed only in the small gap between the contact portions of the image carrier 1 and the charging roller 2 in the circumferential direction) according to Paschen's law. That is, at both ends of the charging roller 2, the image carrier 1 receives the combined discharge of the minute gap at the both ends in the longitudinal direction of the contact portion and the minute gap formed on both sides in the circumferential direction of the contact surface, The surface is deteriorated, and the shaving amount of the halftone dot portion of the image carrier 1 facing the minute gap at both ends increases. In FIG. 6, reference numeral 21 denotes a holder for holding the metal core 18, receiving the pressing force of the spring 22, and urging the charging roller 2 to the image carrier 1.

FIG. 7 shows a roller 2 in which both ends are cut after coating the resistance layer 20 in order to eliminate the sagging shape at the ends. However, in this configuration, the conductive layer 1 in the direction perpendicular to the longitudinal direction
9Because both ends are not covered with the resistance layer 20,
In the case where the conductive layer 19 is in contact with the image carrier 1 as shown in FIG.
9 approaches the surface of the image carrier 1, and a discharge as indicated by an arrow i occurs intensively between the two. Therefore, even in this configuration, the surface of the image carrier 1 is more likely to be deteriorated due to the discharge in the extreme portion than in the central portion, and the dot portion of the image carrier 1 is more easily scraped off.

In the present invention, the edge scraping phenomenon of the charging roller 2 is sufficiently utilized, and the configuration is shown in FIG.

Unlike the conventional example, in the present invention, the end of the charging roller 2 abuts on the same circumferential area of the image carrier 1 where the SD gap regulating member 14 is in contact with the surface of the image carrier 1. Let me. That is, as described above, in the image area, the surface of the normal image carrier 1 is gradually scraped by the contact of the cleaning blade 6 or the like, whereas the SD gap regulating member 1
Since the surface of the image carrier 1 at the four contact portions abuts the end of the charging roller 2, the scraping is promoted as described above, and the SD gap is intentionally reduced particularly at the end of the durable life. Because of the effect of the improvement of the electric field strength due to the above, development can be easily performed even when the image carrier 1 is worn and deteriorated or the toner is deteriorated. Images can be provided.

(Second Embodiment) FIG. 2 shows a second embodiment. Particularly, the difference from the first embodiment is as follows.
The SD gap regulating member 14 is not of a type that can rotate,
For example, it is a fixed type SD gap regulating member 15 integrated with the developing container of the developing device 5.

The contact conditions are exactly the same as those described above, and S is set on the same circumference at a longitudinal position on the surface of the image carrier 1.
The end of the charging roller 2 is in contact with the contact region of the −D gap regulating member 15. In other words, the SD gap regulating member 15 of the present embodiment is of a fixed type in addition to the end shaving due to the discharge of the charging roller 2, so that the SD gap regulating member 15 is formed.
The body itself cuts the surface of the image carrier 1, and the SD gap regulating member 15
The contact portion can be more effectively cut.

In the present embodiment, the regulating member 15 is, for example, integrated with the developing container and is hung between the image carrier 1 and the developing sleeve 3. The regulating member is, for example, a POM (polyacetal) having excellent wear resistance. ) Is preferable, and an abrasive may be adhered to the surface to promote abrasion of the image carrier. The container material must not be brittle and easy to chip. To the last, S-
The D gap regulating member 15 must cut the surface of the image carrier 1. Further, the SD gap regulating member 15 may be installed on the developing container or the process cartridge cover as a separate member without necessarily being integrated with the developing container. Then, the regulating member itself is deformed in the direction of the image carrier in accordance with the shaving amount of the surface of the image carrier, or the container of the regulating member installation portion is deformed and follows the shaving of the image carrier.

(Third Embodiment) FIGS. 3 and 4 show a third embodiment. The method of contacting the image carrier 1 is the same as that of the first and second embodiments. The portion is set so as to abut on the contact area of the SD gap regulating members 14 and 15 on the same circumference.

The feature of the present embodiment is that the charging roller 2
Are designed to more positively scrape the surface of the image carrier 1. FIG. 3 is an enlarged view of the end of the charging roller 2, and as shown in FIG.
The portion that contacts the same circumference where the D gap regulating members 14 and 15 abut has a larger surface roughness than the other portions.
With the above configuration, as described above, more discharge phenomena are generated in the minute gaps according to Paschen's law, and the surface of the image carrier 1 is actively scraped.

For example, a method of forming the above-described structure with the charging roller 2 will be described with reference to FIG. 4. First, FIG. 4 illustrates a cross-sectional structure of the charging roller 2. There is provided a foam layer 19 on which an undercoat layer 16 which is a conductive layer for giving a surface property is provided, and a resistance layer 20 for preventing a leak or the like is further provided thereon. In the present embodiment, the undercoat layer 16 is usually applied to the end portion, but the end portion is not applied, and the resistance layer 20 is applied directly on the foam layer 19 to thereby improve the surface property of the foam layer 19. The surface of the resistance layer 20 is lowered by intentionally spreading the badness,
Discharge is easy to occur. In other words, the surface of the charging roller 2 is made rougher than the image area, and the end scraping that normally occurs at the end of the roller 2 is further forcibly caused, so that the SD gap becomes smaller as the durability progresses positively. As a result, it is possible to provide a good image with no density reduction even if the toner deterioration or the wear deterioration of the image carrier 1 occurs at the end of the durable life similarly to the above.

(Fourth Embodiment) FIG. 9 shows an embodiment in which a charging brush 25 is used as a charging member, and the charging brush is charged by contacting the image carrier 1 as a matter of course. In the contact condition, similarly to the case of the charging roller 2 described above, the charging brush 25 is also configured such that the ends thereof abut on the same circumference of the surface of the image carrier on which the SD gap regulating member 14 contacts. I have.

The charging brush 25 holds the hair 2 around the metal core 23.
According to the present invention, the length of the bristles 24 is made longer at the ends than at the center, and the long portions j and k of the bristles 24 of the image carrier with which the SD gap regulating member 14 abuts. The brush is in contact with the same circumference and mechanically scrapes the surface of the image carrier larger than the central portion by the force of the brush 24. Charging brush 25
Is not limited to a cylindrical one, and the same effect can be obtained with a plate-like one. Further, the charging brush 25 may be driven, but it is better to rotate the image carrier 1 faster than the rotation speed from the viewpoint of image quality stability.

(Fifth Embodiment) FIG. 10 shows another embodiment in which a charging brush 25 is used as a charging member, and the same contact conditions as in the fourth embodiment are taken. However, in the present embodiment, the method of shaving the surface of the image carrier 1 is different, the flocking density of the charging brush 25 is increased at the ends m and n from the center, and the image carrier against which the SD gap regulating member 14 is in contact. The end portions abut on the same circumference on one surface. Then, the abrasion of the contact portion of the image carrier 1 is promoted by an increase in the mechanical amount and the discharge amount of the end portion, thereby preventing a decrease in density as in the first embodiment.

In the above embodiment, the charging device, the developing device,
Although the cleaning device has been described as an example in which the cartridge is integrally formed with the image carrier, in the present invention, at least the developing device and the image carrier are integrated without integrating all of the above units, and a charging device or a cleaning device is provided. It may be selectively integrated.

[0036]

As described above, according to the present invention,
The end portion of the charging member is brought into contact with the same circumferential region as the contact region of the surface of the image carrier 1 of the gap regulating member 14, and when the charging member is a charging roller, the surface roughness of the end portion of the charging roller When the charging member is a charging brush, the length of the bristle at the end of the charging brush is longer than that at the center, or the bristle implantation density at the end of the charging brush is higher than that at the center. Thereby, as the endurance progresses, the gap between the image carrier and the developer carrier is positively reduced, and the developer is deteriorated.
Even if the image carrier is worn and deteriorated, it is possible to provide a good image to the end without lowering the image density.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of a developer carrier and the like according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a main part of a developer carrier and the like according to a second embodiment of the present invention.

FIG. 3 is an end view of a charging roller according to a third embodiment of the present invention.

FIG. 4 is an enlarged view of an end of a charging roller according to a third embodiment of the present invention.

FIG. 5 is an enlarged view of one example of a conventional charging roller end.

FIG. 6 is a view for explaining drum scraping by an end of a charging roller.

FIG. 7 is an enlarged view of another example of a conventional charging roller end.

FIG. 8 is a view for explaining drum scraping by an end of a charging roller.

FIG. 9 is a diagram illustrating a charging brush according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a charging brush according to a fifth embodiment of the present invention.

FIG. 11 is a schematic diagram of an image forming apparatus according to the present invention.

FIG. 12 is a diagram illustrating a main part of a conventional developer carrier and the like.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image carrier 2 ... Charging roller 3 ... Developing sleeve 14 ... Gap regulating member (rotary type) 15 ... Gap regulating member (fixed type) 17 ... Surface roughened surface 25 ... Charging brush G ... Image area h ... Micro gap ( Discharge area)

Claims (9)

[Claims] An image bearing member, a charging member that contacts the image bearing member and charges the surface of the image bearing member, a developing container for storing the developer, and a developer in the developing container are transported toward the image bearing member. A developer carrying member, and an image forming apparatus including a gap regulating member disposed at both ends of the developer carrying member and in contact with the image carrying member to regulate a gap between the image carrying member and the developer carrying member. An image forming apparatus, wherein an end of the charging member is in contact with the same circumferential area of the image carrier in which the gap regulating member is in contact with the image carrier. 2. A cartridge comprising at least an image carrier, a developing device having at least a developer container for storing the developer, and a developer carrier for transporting the developer in the developer container toward the image carrier. A process cartridge of the image forming apparatus, comprising a gap regulating member disposed at both ends of the developer carrier to regulate a gap between the image carrier and the developer carrier in contact with the image carrier, The gap regulating member contacts an end of a charging member that contacts the image carrier and charges the surface of the image carrier on the same circumference of the image carrier that is in contact with the image carrier. A process cartridge for an image forming apparatus. 3. The image forming apparatus or the process cartridge according to claim 1, wherein the charging member is a charging roller. 4. An image forming apparatus or a process cartridge according to claim 3, wherein the surface of said charging roller has a greater surface roughness than that of a central portion thereof. 5. The image forming apparatus or the process cartridge according to claim 1, wherein the charging member is a charging brush. 6. The image forming apparatus or process cartridge according to claim 5, wherein the length of the bristle at the end of the charging brush is longer than that at the center. 7. The image forming apparatus or the process cartridge according to claim 5, wherein the flock density at the end of the charging brush is higher than that at the center. 8. The image forming apparatus or the process cartridge according to claim 1, wherein the gap regulating member is rotatable together with the developer carrier. 9. The image forming apparatus according to claim 1, wherein the gap regulating member is a fixed member that does not rotate with the developer carrier.
8. The image forming apparatus or the process cartridge according to any one of claims 1 to 7.