JP2003149964A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately clean a photoreceptor drum 1 by a simple structure by preventing curling of a cleaning blade 6 used for cleaning the photoreceptor drum of an image forming device of an inversion development system. SOLUTION: Grinding layers 14, each having a high resistance and serving as a resistant layer that does not transfer-electrify the photoreceptor drum 1, are formed on the surface of a transfer roller 10 that contacts areas, indicated by oblique lines, which are within the primary electrifying area of the photoreceptor drum 1 and outside a transfer-electrifying area and in which lubricant on the cleaning blade is electrically scraped off easily. Thus, the areas of the photoreceptor drum 1, indicated by the oblique lines, are ground. The coefficient of friction between the cleaning blade and the photoreceptor drum 1 is maximum in the areas indicated by oblique lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a cleaning blade and a transfer charging device.

[0002]

2. Description of the Related Art FIG. 5 shows a schematic sectional view of a conventional image forming apparatus.

In the conventional image forming apparatus shown in FIG.
The photosensitive drum 1 as an image bearing member is rotatably supported, and is rotationally driven in a direction indicated by an arrow a in the drawing (clockwise direction in the drawing) by a driving unit (not shown).

On the peripheral surface of the photoconductor drum 1, a charging roller 2 as a primary charging device that charges the surface of the photoconductor drum 1 to a uniform potential in order along the rotation direction, and the surface of the photoconductor drum 1. A developing device 5 that attaches toner to the electrostatic latent image formed on the surface to form a toner image, a cleaner 8 that removes the toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 after transfer, and the like are provided. Has been done.

These photosensitive drum 1, charging roller 2,
The developing device 5, the cleaner 8 and the like are compactly made into a cartridge in the housing 9 and integrally constitute a process cartridge 11.

As the process cartridge 11,
It is detachable from the main body of the image forming apparatus.
A transfer roller 10 as a transfer charging device that transfers the toner image on the surface of the photosensitive drum 1 onto the transfer material P is disposed below the photosensitive drum 1 with the process cartridge 11 mounted.

As the developing device 5, the developing sleeve 3 which rotates in the direction of arrow b in the drawing (counterclockwise direction in the drawing) and conveys toner, and the toner coat thickness on the developing sleeve 3 are regulated. An elastic blade 4 is provided.

The cleaner 8 includes a cleaning blade 6 supported by a support member 13 for scraping off the transfer residual toner from the photosensitive drum 1, and a squeeze sheet 7 for collecting the scraped transfer residual toner. And are provided. As the cleaning blade 6, usually urethane rubber is often used from the viewpoint of durability, but since urethane rubber has a high degree of adhesion and poor slidability, silicone resin fine particles or fine particles are used at the contact portion with the photosensitive drum 1. Fluorine particles are applied to obtain lubricity.

Then, the transfer material P, which has passed through the transfer roller 10 and holds the unfixed toner image, is conveyed to a fixing device (not shown), and the toner image is fixed by heating and pressure of the fixing device.

Next, the charging polarity will be described.

For example, when a toner that is negatively charged is used in the reversal developing system, the charging roller 2 performs negative charging and the transfer roller 10 performs positive charging with respect to the photosensitive drum 1.

In such a reversal developing system, the toner is developed on the exposed portion where the charging potential is lowered, so that the both ends in the longitudinal direction of the photosensitive drum 1 which are not desired to be toner-developed are primarily charged. The area is widened and negatively charged to prevent the toner from being developed.

Therefore, in the reversal developing system, the length of the charging roller 2 in the longitudinal direction is longer than that of the transfer roller 10.

[0014]

However, as shown in FIG. 5, since the cleaning blade 6 is in contact with the surface of the photosensitive drum 1 in the counter direction, the direction of arrow F in the drawing (in the drawing) There is a problem in that the frictional force between the photosensitive drum 1 and the cleaning blade 6 becomes excessive due to the force applied to the upper side), and so-called blade flipping occurs in which the edge of the cleaning blade 6 is inverted in the arrow F direction. .

Further, as described above, by applying a lubricant to the edge of the cleaning blade 6, the cleaning blade 6 has lubricity and the friction between the photosensitive drum 1 and the cleaning blade 6 is reduced. is there. However, if the lubricant is peeled off, blade turning may occur immediately under high temperature and high humidity.

The cause of such lubricant peeling will be described below with reference to the schematic sectional views of the image forming apparatus shown in FIGS. 6 and 7.

FIG. 6 shows the inside of the primary charging area and the transfer charging area located at the center of the photosensitive drum 1 in the longitudinal direction, and FIG. 7 shows the inside of the primary charging area located at both ends of the photosensitive drum 1 in the longitudinal direction. The area outside the transfer charging area is shown. In FIGS. 6 and 7, the small circles indicating the polarities are the lubricant, and the other polarities are the surface potential of the photosensitive drum 1 and the charging potential of the cleaning blade 6.

In FIGS. 6 and 7, when the cleaning blade 6 is made of urethane rubber, the charging polarity of the cleaning blade 6 rubbing against the photosensitive drum 1 is measured to be positive. On the other hand, the silicon resin fine particles and the fluorine particles used as the lubricant are negative in terms of charge series, but the lubricant existing as powder is mostly powder negatively charged by frictional charging, while it is frictionally charged. There are also powders that have been reversed and positively charged. Then, the cleaning blade 6 that is positively charged
Holds a negatively charged lubricant, but on the contrary, tries to electrically repel and peel away from the positively charged lubricant.

Further, paying attention to the charging potential of the surface of the photosensitive drum 1, the organic photosensitive drum 1 which is normally negatively charged.
In the case of using, the surface of the end portion in the longitudinal direction of the photosensitive drum 1 is always negatively charged by the charging roller 2. On the other hand, the surface potential in the area of the photosensitive drum 1 charged on the transfer roller 10 is not uniform, but is substantially positively charged after passing through the transfer roller 10.

Within the longitudinal range where the transfer roller 10 is charged, as shown in FIG. 6, the surface of the photosensitive drum 1 is positively charged, but the negatively charged lubricant is positively charged, and the cleaning blade 6 is positively charged. It adheres firmly to both electrically and physically and does not come off.

On the other hand, in the area charged by the charging rollers 2 at both ends in the longitudinal direction where the transfer roller 10 is not charged, as shown in FIG. 7, the surface potential of the photosensitive drum 1 is a negative potential. , The lubricant which is reversed and positively charged is electrically peeled off, and further repelled and peeled off from the cleaning blade 6 which is positively charged, and when the charging roller 2 is a contact charging member, the lubrication is peeled off. Contamination occurs when the agent adheres. Further, the lubricant that has not adhered to the charging roller 2 returns to the cleaner 8 portion again unless it adheres to the transfer material, but is scraped off by the cleaning blade 6 and collected in the cleaner 8, so that the lubricant Is useless as

As described above, in the charging area of the charging roller 2 and outside the charging area of the transfer roller 10, the lubricant applied to the cleaning blade 6 is peeled off, and the frictional force of the peeled off portion becomes excessive and the blade May turn over.

Therefore, it is an object of the present invention to provide an image forming apparatus which can prevent the above-mentioned problems and can always stably and favorably clean the photosensitive drum 1.

[0024]

A first structure of an image forming apparatus according to the present invention comprises a primary charging device for uniformly charging the surface of an image carrier, and the image carrier which is in contact with the surface of the image carrier. An image forming apparatus comprising: a transfer charging device that transfers the above toner image onto a transfer material; and a cleaning blade that contacts the surface of the image carrier and cleans the surface of the image carrier. A polishing layer for polishing the outside of the image area on the surface of the image bearing member was provided on the end surface.

A second configuration of the image forming apparatus according to the present invention is a primary charging device for uniformly charging the surface of the image carrier,
A transfer charging device that contacts the surface of the image carrier to transfer the toner image on the image carrier to a transfer material; and a cleaning blade that contacts the surface of the image carrier and cleans the surface of the image carrier. In the image forming apparatus, a lubricant substance application layer for applying a lubricant substance is provided on the surface of the end portion in the longitudinal direction of the transfer charging device outside the paper passing area on the surface of the image carrier.

A third structure of the image forming apparatus according to the present invention is the same as the second structure, except that a lubricant substance supplying member which is in contact with the lubricant substance coating layer on the surface of the transfer charging device and supplies the lubricant substance is provided. .

A fourth configuration of the image forming apparatus according to the present invention is the image forming apparatus according to any one of the first to third configurations, in which a resistance layer is provided on an end surface in a longitudinal direction of the transfer charging device. The surface of the end portion in the longitudinal direction is not transfer-charged.

A fifth structure of the image forming apparatus according to the present invention is the same as the fourth structure, wherein the resistance layer is integrally formed with the polishing layer.

A sixth structure of the image forming apparatus according to the present invention is the same as the fifth structure, except that abrasive particles are dispersed in the resistance layer to form a polishing layer.

In a seventh structure of the image forming apparatus according to the present invention, in the fourth structure, the resistance layer is formed integrally with the lubricating substance coating layer.

An eighth construction of the image forming apparatus according to the present invention is the construction of any one of the first to seventh constructions, wherein the length of the transfer charging device in the longitudinal direction is larger than the length of the primary charging device in the longitudinal direction. .

In a ninth configuration of the image forming apparatus according to the present invention, in any one of the first to seventh configurations, image formation is performed by a reversal development system in which the primary charging polarity and the toner charging polarity are the same. .

According to the first structure, the surface roughness of the image carrier at least in the primary charging area and outside the transfer charging area is made larger than that in at least the other image forming area, and the image carrier is made. It is possible to prevent the friction coefficient between the surface of the image carrier and the cleaning blade from becoming excessively large even if the lubricant of the cleaning blade is electrically peeled off by lowering the adhesion between the cleaning blade and the cleaning blade.

According to the above-mentioned second structure, the lubricating substance is constantly supplied to the surface of the image carrier at least in the primary charging region and outside the transfer charging region, and this lubricating substance adheres to the edge of the cleaning blade. Therefore, even if the lubricant is electrically peeled off from the surface of the cleaning blade, the lubricity of the cleaning blade is always maintained. Further, the supply of the lubricant substance makes it difficult for the original lubricant to be peeled off due to the connection with the lubricant originally applied to the cleaning blade.

With the above-mentioned structure, the functions can be separated in the longitudinal direction of the transfer charging device, the blade can be turned up at an accurate longitudinal position, and at the same time, a space-saving and simple structure can be taken.

Therefore, in any of the above means, it is possible to prevent the blade from being turned over without increasing the friction coefficient between the cleaning blade and the image carrier.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the exemplification in the embodiments does not limit the present invention.

(Embodiment 1) Embodiment 1 according to the present invention will be described below with reference to FIGS. 1 and 2. The members common to the drawings, including the drawings shown in the conventional example, are designated by the same reference numerals.

FIG. 1 is a front view in the longitudinal direction of the periphery of a photosensitive drum 1 as an image carrier according to the first embodiment, in which the blade turn-up portion is indicated by hatched portions, and a transfer roller 10 as a transfer charging device is shown. Polishing layers 14 that scrape the surface of the photosensitive drum 1 to increase the surface roughness are provided at both ends in the longitudinal direction.

FIG. 2 is a side view of FIG. 1 viewed from the side, showing the photosensitive drum 1, the transfer roller 10, and the polishing layer 14 provided on the end surface of the transfer roller 10 in the longitudinal direction. ing.

In the following description, the overall structure of the image forming apparatus and the process cartridge 11 is omitted because it is the same as the structure described with reference to FIG. 5 of the conventional example, and other structures are characteristically embodied in the present invention. The detailed description will be given below.

First, in FIG. 1, as the primary charging device, a charging roller 2 which contacts the surface of the photosensitive drum 1 to perform charging is adopted, and as the transfer charging device, the surface of the photosensitive drum 1 is contacted to perform transfer charging. The transfer roller 10 is used.

In the first embodiment, the charging roller 2 is not limited to the contact charging system, but the charging area is clearer in the contact portion and the non-contact portion than in the conventional corona charging system. Therefore, it is easy to set in describing and implementing the present embodiment.

Next, the photosensitive drum 1, the cleaning blade 6 made of urethane rubber, and the transfer roller 10
The longitudinal positional relationship with the polishing layer 14 that is provided on the surface of the photoconductor drum 1 to roughen the surface to increase the surface roughness will be described.

The transfer roller 10 is composed of a sponge layer in which EPDM or urethane rubber material is foamed around a core metal and has a volume resistance of about 10 ⁶ Ω · cm to 10 ⁸ Ω · cm and a medium resistance sponge layer. A positive bias is applied to the surface of the photosensitive drum 1 with a total pressure of several hundreds g by means of springs (not shown) provided at both ends in the longitudinal direction of the photosensitive metal drum. The toner image on the first surface is transferred.

As the first embodiment, the transfer roller 10 is used.
It is characterized in that the polishing layer 14 is provided at both ends in the longitudinal direction of the photosensitive drum 1 to roughen the surface of the photosensitive drum 1 to increase the surface roughness. The structure of the polishing layer 14 is such that the surface roughness of the surface of the photosensitive drum 1 is increased and the volume resistance is at least 10 ¹¹ Ω · c so as not to charge the photosensitive drum 1.
For example, sandpaper or the like having m or more is adhered and fixed to the surface of the transfer roller 10.

Further, the structure of the polishing layer 14 is not limited to the above-mentioned adhesive fixing, and it is possible to use, for example, PTF having high resistance.
It is also possible to coat the end portion of the transfer roller 10 with E or the like to form a resistance layer, and disperse abrasive particles in the resistance layer to form the polishing layer 14.

In particular, in most cases, the blade turning does not occur in the latter half of the durability, but it occurs in the first half of the durability. This is because the surface of the photoconductor drum 1 is scraped by the transfer roller 10 and becomes uneven as the durability advances, so that the contact area between the cleaning blade 6 and the photoconductor drum 1 decreases and the friction coefficient decreases.

That is, as a method of adhering and fixing the polishing layer 14 such as the sandpaper mentioned above to the transfer roller 10,
Considering its polishing ability, the idea is to prevent the blade from turning over even in the first half of durability. On the other hand, as the polishing layer 14 in which the polishing particles are dispersed, the polishing ability is sustained, and it is possible to exert the power to prevent the blade from being turned over even in the latter half of the durability.

The thickness of the polishing layer 14 is affected by the spring pressure that presses the transfer roller 10, and cannot be generally stated. However, the transfer roller 10 contacts the photosensitive drum 1 with the required pressure in the charging area. The thickness is set to be equal to or less than the thickness at which they can contact. In the first embodiment, the thickness is 1
mm or less. Transfer roller 10 surface and polishing layer 14
If the difference in level is not made as small as possible, it should be noted that in the worst case, the transfer error at the image end portion may occur due to the void due to the level difference. On the other hand, if the transfer roller 10 has a large longitudinal width, there is no such problem, and a margin can be provided in the direction of increasing the thickness of the polishing layer 14.

Next, with respect to the cause of the blade flipping, the shaded portion shown in FIG. 1 at the longitudinal end of the surface of the photosensitive drum 1 will be described.

First, on the charging roller 2, an AC voltage is superimposed on a negative DC voltage from the power source S shown in FIG. The charging polarity is omitted because it has been described in the conventional example, but since the photosensitive drum 1 which is an organic photosensitive member is negatively charged in most cases, the charging roller 2 is negatively charged in the first embodiment. Charging is performed. In the reversal developing system, negatively charged toner is used.

A positive voltage is applied to the transfer roller 10 in order to transfer the toner from the surface of the photosensitive drum 1 to the transfer material P. That is, where the transfer roller 10 contacts the photosensitive drum 1 and is charged, when the surface of the photosensitive drum 1 passes the transfer roller 2, the potential of the photosensitive drum 1 is not uniform but becomes almost positive potential.

On the other hand, in the area shown by the hatched portion in FIG. 1 where the charging roller 2 is contacted and charged on the surface of the photosensitive drum 1 and the transfer roller 10 is not charged, the potential of the photosensitive drum 1 is always a negative potential. .

Now, the relationship between the lengths of the charging roller 2 and the transfer roller 10 in the longitudinal direction will be described.

The length of the transfer roller 10 in the longitudinal direction naturally covers at least the image area, and is the same as the maximum width of the transfer material P for transporting the transfer material P.

Further, in the reversal developing system, the toner is not developed on the charged portion on the photosensitive drum 1,
The toner is developed where the potential of the photosensitive drum 1 is dropped by being exposed by the image exposing means 12. Therefore, it is natural that the longitudinal length of the charging roller 2 is longer than the maximum transfer material P width in order to prevent unnecessary development in the end area in the longitudinal direction of the photosensitive drum 1. In order to prevent the end portion from being soiled with unnecessary toner, it is configured to be longer than the charging area of the transfer roller 10.

According to this structure, the photosensitive drum 1
In the shaded portions shown in FIG. 1 at both ends in the longitudinal direction of the surface, there are always negatively charged portions.

What is different from the prior art is that the length of the transfer roller 10 in the longitudinal direction is larger than that of the charging roller 2, and this is a feature of the present invention.

However, although the length of the transfer roller 10 in the longitudinal direction is larger than that of the charging roller 2, at least the volume resistance for forming the non-charged region on the surfaces of both ends of the transfer roller 10 in the longitudinal direction is 10 ¹¹ Ω · cm. Polishing layer 1 as described above
4 is provided, the charging polarity in the longitudinal direction on the surface of the photosensitive drum 1 remains unchanged.

That is, even if the length of the transfer roller 10 in the longitudinal direction becomes long, the charging area of the charging roller 2 and the charging area of the transfer roller 10 remain the same, so that the photosensitive drum 1 is always provided at both ends in the longitudinal direction. Due to the shaded portions shown in FIG. 1 that are negatively charged, there is no portion in which both ends of the photosensitive drum 1 in the longitudinal direction develop unnecessary toner.

On the other hand, when the charging potential of the cleaning blade 6 whose outermost layer is made to rub against the photosensitive drum 1 made of, for example, polycarbonate is measured, it is positively charged.
On the surface of the cleaning blade 6, the photosensitive drum 1
In order to reduce the friction coefficient between the cleaning blade 6 and the photosensitive drum 1, powder such as silicon resin fine particles or fluorine particles, which is a lubricant, is applied to the edge portion of the cleaning blade 6 that is in contact with the photosensitive drum 1.

The coating agent as the lubricant is usually negatively charged, but the coating agent is triboelectrically charged. Therefore, if negatively charged due to triboelectric charging, powder which is positively charged as a reversal component is naturally generated. is there.

The coating agent is the cleaning blade 6.
However, since the cleaning blade 6 is positively charged, the negatively charged powder is electrically adhered to the cleaning blade 6 and is inverted and positively charged. The powder will electrically repel the cleaning blade 6.

Next, the relationship between the cleaning blade 6 and the surface potential of the photosensitive drum 1 is shown in FIG.
And FIG. 7 will be described.

In the charging area of the transfer roller 10 of the photosensitive drum 1, as shown in FIG. 6, the potential of the surface of the photosensitive drum 1 after passing through the transfer roller 10 is almost positively charged, and the cleaning blade 6 described above is used. The powder, which is a negatively charged coating agent, is particularly electrically attached to the cleaning blade 6 by the electric force and the physical adhesive force of the cleaning blade 6 due to the positive potential of the cleaning blade 6. The photoconductor drum 1 also electrically repels and eventually does not physically come off as it is from the cleaning blade.

On the other hand, in FIG. 1 inside the charging area of the charging roller 2 of the photosensitive drum 1 and outside the charging area of the transfer roller 10.
In the shaded area shown in FIG. 7, as shown in FIG. 7, the potential of the surface of the photosensitive drum 1 is always negatively charged, and the negatively charged powder naturally adheres firmly to the cleaning blade 6. . On the other hand, the positively charged powder repels the cleaning blade 6 and is electrically strongly transferred to the photosensitive drum 1. Further, not only the positively charged powder but also a part of the negatively charged powder is The positively charged toner is attached to the toner electrically and physically, and the toner is gradually peeled off from the cleaning blade 6, and the friction coefficient between the cleaning blade 6 and the photosensitive drum 1 is increased. It may turn over.

Therefore, in the first embodiment, as shown in FIG.
The unevenness is formed by constantly polishing the longitudinal end portion of the surface of the photosensitive drum 1 corresponding to the shaded area shown in FIG. 3, and the contact surface between the cleaning blade 6 and the surface of the photosensitive drum 1 is reduced to reduce the cleaning blade 6 and the photosensitive member. The coefficient of friction with the drum 1 is reduced.

Therefore, it is possible to prevent the friction coefficient from unnecessarily increasing over the entire area of the cleaning blade 6 in the longitudinal direction and prevent the blade from being turned over.

Here, it is necessary to pay attention to the polishing width of the polishing layer 14 to cover the width of the hatched portion shown in FIG. Alternatively, a seal member (not shown) is usually provided at the end of the cleaning blade 6 so as not to leak the collected toner, but the polishing width does not reach the seal member. This is because there is a high possibility that the unevenness on the surface of the photosensitive drum 1 will convey the toner toward the end portion in the longitudinal direction and cause toner leakage from the cleaner 8.

Further, the polishing width of the polishing layer 14 on the inner side in the longitudinal direction should not be in the image area as a matter of course. If the unevenness of the polishing layer 14 has a surface roughness of 1 μm or more, there is a problem that an image defect is caused as a scratch image on the photoconductor drum 1, and if the resistance layer as the polishing layer 14 reaches the image area before that, transfer occurs. A bias may not be applied, which may lead to transfer failure.

As described above, according to the first embodiment, in the charging area of the charging roller 2 of the photosensitive drum 1,
In addition, the friction coefficient between the photoconductor drum 1 and the transfer roller 10 is reduced in the areas outside the charging area of the transfer roller 10 and in the shaded portions shown in FIG. In order to regulate the transfer charge of the transfer roller 10, the cleaning blade 6 is provided by providing the polishing layer 14 also serving as the resistance layer at the longitudinal end of the transfer roller 10.
It is possible to more reliably reduce the coefficient of friction between the photosensitive drum 1 and the photosensitive drum 1, and it is possible to prevent the blade from being turned over.

The polishing layer 14 is formed on the transfer roller 10
Since it is provided on both end surfaces of the longitudinal direction, the positional relationship in the longitudinal direction is accurate, and since it is integrated with the transfer roller 10, space saving and simplification of the configuration can be achieved.

Further, the transfer roller 10 is the photosensitive drum 1
If you are driven to be, or by receiving a driving also be rotated with the photosensitive drum 1 and the peripheral speed difference, the polishing layer 14 may be in either configuration for will not be affected by it.

However, although slightly, it is more preferable to rotate by rotation rather than to provide a peripheral speed difference, especially at the adhesive interface between the surface of the transfer roller 10 and the polishing layer 14 when the adhesive fixing type polishing layer 14 is used. There is difficulty in peeling.

(Second Embodiment) The second embodiment according to the present invention will be described below with reference to FIGS. 3 and 4. It should be noted that members common to the drawings, including the above-mentioned drawings, are denoted by the same reference numerals, and parts that are not particularly described have the same configuration as that of the first embodiment described above.

FIG. 3 of the longitudinal end portion of the surface of the photosensitive drum 1.
The shaded portion shown in is a portion that is always at a negative potential as described in the first embodiment.

In the second embodiment, the transfer roller 1
It is characterized in that the lubricant substance coating layer 15 is provided on the surfaces of both end portions of No. 0.

Further, the transfer roller 10 has a longer length in the longitudinal direction than the charging roller 2 as in the first embodiment, and although there is almost no difference in the configuration other than the lubricating substance coating layer 15, the lubricating substance coating layer is provided. The regulation of the lubricant substance application width of No. 15 is slightly different.

The lubricant substance coating width on the inner side in the longitudinal direction is, of course, outside the image region, and should be outside the sheet passing region in consideration of the transfer of the lubricant substance. Further, both ends in the longitudinal direction of the transfer roller 10 can be made wider than those in the first embodiment, and if it is made wider, the toner is transported to the outside of the cleaner 8 by the lubricant substance from the lubricant substance application layer 15 and the toner leaks from the cleaner 8. It is possible to prevent it from happening. Further, it is more advantageous for the blade to be turned over if the lubricating substance is exactly supplied to the end of the cleaning blade 6.

Next, as the lubricant substance coating layer 15, even if the longitudinal length of the transfer roller 10 is longer than that of the charging roller 2, the charging area of the transfer roller 10 is made smaller than the charging area of the charging roller 2. , The area of the lubricant coating layer 15 is at least 10 ¹¹ Ω so that the area is not charged.
・ The resistance layer is cm or more. Therefore, the shaded portion shown in FIG. 3 at the end portion of the photosensitive drum 1 in the longitudinal direction is always negatively charged to prevent unnecessary toner development.

FIG. 4 shows a side view around the photosensitive drum 1 according to the second embodiment.

In FIG. 4, the transfer roller 10 is in contact with the photosensitive drum 1 via the lubricant substance coating layer 15. Further, the lubricant substance supplying member 16 which supplies the lubricant substance to the lubricant substance applying layer 15 is in contact with the lubricant substance applying layer. As a matter of course, the lubricant substance supplying member 16 has the lubricant substance coating layer 15
Within the range of the longitudinal direction, and is not in contact with the charging area of the transfer roller 10.

In the above-mentioned structure, the lubricant substance is supplied to the non-sheet passing region of the photosensitive drum 1, so that it may be powder or lubricant oil.

For example, when silicone oil is used as the lubricating substance, the lubricating substance supply member 16 is not necessary when using one having a molecular weight of several thousands, and the lubricating substance coating layer which is the above-mentioned high resistance layer. It is preferable that the silicone oil 15 is soaked in advance and gradually supplied to the surface of the photosensitive drum 1.

Here, the lubricant substance coating layer 15 is conveniently of a type that is napped with a woven fabric, such as a pile, as a type that is adhered and fixed to the longitudinal end surface of the transfer roller 10. In addition, it is necessary to pay sufficient attention so that the thickness of the lubricant coating layer 15 does not hinder the charging area of the transfer roller 10.

Further, when a lubricating oil is selected as the lubricating substance, there is a possibility that adverse effects may occur other than the photosensitive drum 1 in consideration of evaporation in the machine. I have to. However, the lubricating oil is supplied to the edge portion of the cleaning blade 6 so that the lubricating oil and the coating agent, and further the cleaning blade 6 have an increased adhesive force, which improves the holding force of the coating agent and enables more effective operation. You can

Further, in the case of supplying powder as the lubricating substance, if the material which is the original coating agent of the cleaning blade 6 is supplied as the lubricant, it can be applied without any adverse effect. In this structure, the powder which is the lubricating substance is gradually supplied from the powder reservoir which is the lubricating substance supply member 16.

The nap type is convenient for carrying and applying powder as described above. In addition, solid zinc stearate may be applied onto the photosensitive drum 1 as a fusion agent or an image flow preventing agent. In this case, solid zinc stearate is also used as the lubricant substance supply member 16. It can be installed and supplied as a lubricant.

However, the lubricant substance coating layer 15 is not limited to the raised type, and is a high resistance layer which can be an uncharged region, and a material capable of sufficiently conveying the lubricant substance and not contaminating the photosensitive drum 1, Any configuration will do.

As described above, according to the second embodiment, by positively supplying the lubricant substance to the shaded portion shown in FIG. 3 on the surface of the photosensitive drum 1, the cleaning blade 6 that abuts on the shaded portion. Even if the coating agent is peeled off electrically at the site, the friction coefficient between the cleaning blade 6 and the photosensitive drum 1 is not excessively increased,
The blade can be prevented from turning over.

[0092]

As described above, according to the first aspect of the present invention, the surface roughness outside the image area of the longitudinal end portion of the image carrier is provided by the polishing layer provided on the longitudinal end surface of the transfer charging device. By increasing, it is possible to prevent the friction coefficient between the image carrier and the cleaning blade from becoming excessive.

Further, according to the second aspect of the present invention, the lubricating substance is applied to the outside of the sheet passing area at the longitudinal end portion of the image carrier by the lubricating substance coating layer provided on the longitudinal end surface of the transfer charging device. As a result, it is possible to prevent the friction coefficient between the image carrier and the cleaning blade from becoming excessive, and since the lubricant originally applied to the cleaning blade and this lubricating substance are combined, the original lubricant is less likely to come off from the cleaning blade.

According to the third aspect of the present invention, the lubricant substance can be always supplied to the image carrier by applying the lubricant substance to the lubricant substance application layer of the transfer charging device by the lubricant substance supplying member.

According to the fourth aspect of the present invention, a resistance layer is provided on the longitudinal end surface of the transfer charging device, and the longitudinal end surface of the image carrier is not transfer-charged. It is possible to prevent unnecessary toner from developing on the end portions in the direction.

Further, according to any one of the fifth to seventh aspects of the present invention, the resistance layer of the transfer charging device and the polishing layer or the lubricant substance coating layer are integrally formed so that the longitudinal positional relationship is appropriate. And the structure of the member can be simplified.

According to the eighth aspect of the present invention, by making the length of the transfer charging device in the longitudinal direction larger than the length of the primary charging device in the longitudinal direction, the primary charging outside the image area or the paper passing area on the surface of the image carrier is performed. Surface roughness can be increased or a lubricant can be added to the end portion in the longitudinal direction of the portion charged by the apparatus, and the friction between the image carrier and the cleaning blade can be reduced. Further, the positional relationship among the transfer charging device, the image carrier, and the primary charging device can be easily set.

Further, according to the ninth aspect of the present invention, the above-mentioned effects can be obtained more effectively by applying the above-mentioned structure to the apparatus for forming an image in the reversal development system.

As described above, by separating the functions of the transfer charging device in the longitudinal direction, it is possible to take measures against the accurate position of the image carrier, and to save space and simplify the structure between the cleaning blade and the image carrier. It is possible to prevent the friction coefficient from always becoming excessive, prevent the blade from being turned over, and always perform stable and excellent cleaning of the image bearing member.

[Brief description of drawings]

FIG. 1 is a front view around a photosensitive drum according to a first embodiment of the present invention.

FIG. 2 is a side view of the periphery of the photosensitive drum according to the first embodiment of the present invention.

FIG. 3 is a front view around the photosensitive drum according to the second embodiment of the present invention.

FIG. 4 is a side view around the photosensitive drum according to the second embodiment of the present invention.

FIG. 5 is a schematic sectional view of a conventional image forming apparatus.

FIG. 6 is a cross-sectional view showing a charging polarity around a central portion in a longitudinal direction of a photosensitive drum of a conventional example.

FIG. 7 is a cross-sectional view showing a charging polarity around a longitudinal end portion of a photoconductor drum of a conventional example.

[Explanation of symbols] 1 photoconductor drum 2 charging roller 3 Development sleeve 4 elastic blade 5 Development device 6 cleaning blade 7 Squishy sheet 8 cleaner 9 housing 10 Transfer roller 11 Process cartridge 12 Image exposure means 13 Support members 14 Polishing layer 15 Lubricant coating layer 16 Lubricant supply member P transfer material S power supply

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H134 GA01 GB02 HD01 HD17 HD19                       KD08 KG04 KH15 LA01                 2H200 FA02 GA14 GA16 GA23 GA44                       GA59 GB12 HA02 HB12 HB20                       JA02 JA25 JA26 JA27 JA28                       JB10 LC04 MA03 MA08 MA20                       MB02 MB03 MB04 MC01 MC05                       MC06 NA02

Claims (9)

[Claims] 1. A primary charging device for uniformly charging the surface of an image carrier, a transfer charging device for contacting the surface of the image carrier to transfer a toner image on the image carrier onto a transfer material, and the image carrier. In an image forming apparatus equipped with a cleaning blade that contacts the body surface and cleans the surface of the image carrier, a surface roughness outside the image area of the surface of the image carrier is increased on the end surface in the longitudinal direction of the transfer charging device. An image forming apparatus having a polishing layer for controlling the image forming apparatus. 2. A primary charging device for uniformly charging the surface of the image carrier, a transfer charging device for contacting the surface of the image carrier to transfer the toner image on the image carrier to a transfer material, and the image carrier. An image forming apparatus comprising: a cleaning blade that abuts on a body surface and cleans the surface of the image carrier; a lubricant is applied to a surface of a longitudinal end portion of the transfer charging device outside a sheet passing area of the surface of the image carrier. An image forming apparatus provided with a lubricant substance coating layer. 3. The image forming apparatus according to claim 2, further comprising a lubricant substance supply member which is in contact with the lubricant substance application layer on the surface of the transfer charging device and supplies a lubricant substance. 4. The transfer layer is provided with a resistance layer on the end surface in the longitudinal direction, and the end surface in the longitudinal direction of the image carrier is not transfer-charged. Image forming device. 5. The image forming apparatus according to claim 4, wherein the resistance layer is formed integrally with the polishing layer. 6. The image forming apparatus according to claim 5, wherein polishing particles are dispersed in the resistance layer to form a polishing layer. 7. The image forming apparatus according to claim 4, wherein the resistance layer is formed integrally with the lubricating substance coating layer. 8. The image forming apparatus according to claim 1, wherein the length of the transfer charging device in the longitudinal direction is longer than the length of the primary charging device in the longitudinal direction. 9. The image forming apparatus according to claim 1, wherein an image is formed by a reversal development system in which the primary charging polarity and the toner charging polarity are the same.