JP2014134579A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which reduces frictional resistance in an image carrier surface and prevents charging non-uniformity in a charging member to be caused by lubricant adhered thereto which is used for the purpose of reducing frictional resistance in the image carrier surface, without increasing device cost.SOLUTION: Image carriers 11 are arranged in each of a plurality of imaging units arranged along a stretched surface of an intermediate transfer body 17 having the stretched surface. An image forming apparatus has a mechanism of cleaning the image carriers 11 after subjecting the image carriers 11 to charging, latent image formation, development, and transfer. One of the image carriers 11 in the imaging units is provided with a lubricant supply mechanism 16, while the other image carriers 11 have no lubricant supply mechanism 16. Lubricant supplied from the lubricant supply mechanism 16 is conveyed to the image carriers 11 in the imaging units having no lubricant supply mechanism 16 via the intermediate transfer body 17.

Description

  The present invention relates to an image forming apparatus, and more particularly to a lubricant supply structure for forming a protective layer on the surface of a uniformly charged latent image carrier.

In an image forming apparatus using an electrophotographic process, a charging process, an exposure process, a development process, and a transfer process are performed on a photoreceptor used as a latent image carrier to form an image.
Specifically, when an electrostatic latent image corresponding to image information is formed after uniform charging of the photosensitive member, the electrostatic latent image is visualized by the charged toner supplied from the developing device.
The visible image is transferred to a transfer medium such as transfer paper, and then fixed to the transfer medium by heat and pressure or solvent gas through a melting / penetrating action to be an output image.

  The developing device includes a two-component developing method using a two-component developer in which toner particles and a carrier are stirred and mixed to charge the toner, or a one-component system that is charged by friction charging of the toner itself without using a carrier. A one-component development system using a developer is known.

  As the one-component development method, a magnetic one-component development method in which toner particles are held by a magnetic force with respect to a developing sleeve used for supplying a developer or a non-magnetic one-component development method in which no magnetic force is used is known.

  The two-component development system is a copier that requires stable chargeability, riseability and long-term stabilization of image quality in toner particles, a multi-function machine that combines functions as a facsimile machine and printer that can use the copier function. It is frequently used for etc. The above-described one-component development system is widely used in small printers and facsimile machines that require space saving and low cost.

On the other hand, the output image is not limited to a single color such as monochrome, but includes a multicolor image including a full color. In recent years, demands for higher image quality and image quality tend to increase.
For this reason, in order to meet these requirements, the quality of the members used for the image forming process needs to be maintained at a high level.

By the way, in the image forming apparatus, a cleaning process for removing foreign matters such as untransferred toner and paper dust is performed on the photoreceptor after image transfer regardless of the development method.
The structure used for the cleaning process is generally a structure using an inexpensive and mechanically simple member such as a rubber blade.

  However, since the rubber blade is pressed against the photoconductor to remove the residue on the surface of the photoconductor, stress due to friction between the surface of the photoconductor and the cleaning blade is large, and the rubber blade is likely to be worn. Further, in the organic photoreceptor used as the photoreceptor to which the rubber blade is pressed, the surface layer of the photoreceptor is worn or scratched, and the life of the rubber blade and the organic photoreceptor is shortened.

In recent years, toners used for image formation in response to the demand for higher image quality have been increasing in size.
In an image forming apparatus using a toner having a small particle diameter, the ratio of residual toner passing through the cleaning blade increases. In particular, the dimensional accuracy and assembly accuracy of the cleaning blade are not sufficient, and when the cleaning blade partially oscillates, toner slip-through becomes severe and may prevent high-quality image formation.

For this reason, in order to extend the life of the organic photoreceptor and maintain high image quality over a long period of time, it is necessary to reduce deterioration of the member due to friction and improve cleaning properties.
As a general means for reducing friction, for example, when a plurality of photoconductors are used to form a full-color image, a lubricant is supplied to the surface of each photoconductor to form a protective layer on the surface. A method is known (for example, Patent Document 1).

On the other hand, when a plurality of photoconductors for enabling full color image formation are used, the use frequency of each photoconductor may be different. For example, the use frequency of a black image is other than black used for a full color image. It is often higher than the frequency of use of images.
For this reason, if the same amount of lubricant is supplied to each photoconductor, wasteful supply of lubricant to an unused photoconductor is performed, which is disadvantageous in terms of running cost.

  Therefore, a configuration in which the amount of lubricant supplied between the photoconductors is made different (for example, Patent Document 2), the presence / absence of lubricant supply and the classification of charging methods (contact and non-contact) depending on the frequency of use of the photoconductors. The structure which combined the classification with a contact) is proposed (for example, patent documents 3-4).

  Furthermore, a plurality of types of lubricants are prepared, and lubricants containing boron nitride and metal soap are supplied as lubricants to the frequently used black image forming photoconductors, and other color image forming photoconductors are supplied. A configuration for supplying a lubricant containing only metal soap has also been proposed (for example, Patent Document 5).

  In the configuration disclosed in the above-mentioned patent document, when the supply amount of the lubricant is varied, a lubricant supply mechanism for all the color image forming photoreceptors is required. For this reason, since the lubricant supply mechanism is provided, the cost of the apparatus cannot be reduced by increasing the size of the mechanism or increasing the number of parts.

  On the other hand, in the configuration in which the charging method is selected, the lubricant is liable to be peeled off at the time of AC bias when AC and DC are biased, so that there is a risk of increasing the frictional resistance when the cleaning blade is used.

  When a lubricant is used, the lubricant may slip through the toner as well. For this reason, if the slipped lubricant adheres to a member used in the charging device, such as a roller, there is a risk of causing uneven charging due to contamination of the charging member. The same applies to charging unevenness when there is unevenness in the amount of adhesion in the longitudinal direction of the charging member.

  SUMMARY OF THE INVENTION In view of the above problems in the conventional image forming apparatus, the object of the present invention is to reduce the frictional resistance on the surface of the image carrier and to attach the lubricant used for this purpose without causing an increase in apparatus cost. The present invention provides an image forming apparatus having a configuration capable of preventing uneven charging.

In order to achieve this object, the present invention includes an image carrier in each of a plurality of image forming units arranged along the stretch surface of an intermediate transfer member having a stretch surface, and charging and latent images on the image carrier. In an image forming apparatus provided with a mechanism for performing a cleaning process of the image carrier after performing each process of forming, developing and transferring,
A lubricant supply mechanism is provided for one of the image carriers in each of the image forming units, and the lubricant supply mechanism is not provided in the image carriers of the other image forming units. In the image forming apparatus, the lubricant supplied from the supply mechanism is conveyed toward the image carrier of the image forming unit not provided with the lubricant supply mechanism via the intermediate transfer member.

  According to the present invention, the lubricant supply mechanism is not provided in all of the plurality of image forming units, thereby reducing the frictional resistance on the surface of the image carrier and attaching the lubricant used for this purpose without causing an increase in apparatus cost. It is possible to prevent uneven charging on the charging member due to the above.

1 is a diagram for explaining an example of an image forming apparatus according to an embodiment of the present invention. It is a figure for demonstrating the structure of the image forming part provided with the lubricant supply mechanism among the image forming parts used for the image forming apparatus shown in FIG. It is a figure which shows the structure of the image forming part which is not provided with the lubricant supply mechanism among the image forming parts used for the image forming apparatus shown in FIG. It is a figure for demonstrating the lubricant support structure used for a lubricant supply mechanism. It is a figure for demonstrating another structure of an image forming apparatus. FIG. 2 is a front view for explaining a configuration of a charging roller and a photoconductor used in the image forming apparatus shown in FIG. 1. FIG. 7 is a front view corresponding to FIG. 6 for explaining another relationship between the charging roller and the photoconductor shown in FIG. 6. FIG. 8 is a diagram for explaining a contact width between a charging roller and a photoreceptor obtained by the configuration shown in FIGS. 6 and 7. FIG. 7 is a front view for explaining the relationship between a charging roller intended for the configuration of the image forming apparatus shown in FIG. 6 and a cleaning member thereof. It is a figure for demonstrating the structure of the cleaning member shown in FIG. It is a figure for demonstrating the structure of the cleaning member aiming at a photoconductor. FIG. 4 is a diagram for explaining a distribution state of fillers used in a photoconductor of an image forming apparatus.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the drawings.
FIG. 1 is a diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus 1 shown in FIG. 1 is a tandem type color image in which a plurality of image forming portions capable of forming different color images are arranged along the extended surface of a transfer belt 17 used as an intermediate transfer member. Forming device.

In the image forming apparatus 1, a document conveying section 3, a document reading section 4, and a sheet discharge tray 5 are sequentially positioned downward on the upper side across an image forming section located at a substantially central portion in the vertical direction of the apparatus body. In the lower part, the paper feed unit 7 that stores the recording paper P is located.
In the image forming unit, process cartridges 10Y, 10C, 10M, and 10BK used for a plurality of image forming units are arranged along the extended surface of the transfer belt 17. Note that the subscript Y of 10 represents yellow, C represents cyan, M represents magenta, and BK represents black. Reference numeral 28 denotes a replenishment tank containing toner to be replenished toward the developing device of each image forming unit.

  In this embodiment, the process cartridges 10Y, 10C, 10M, and 10BK are arranged along the extending direction of the extending surface located below the transfer belt 17. In addition, the arrangement configuration of each process cartridge with respect to the transfer belt 17 may be opposed to the above-described extension surface in addition to the above-described extension surface positioned below the transfer belt 17. The latter configuration will be described later.

  The transfer belt 17 is a member that can move the expansion surface in the direction of the arrow shown in the drawing and can sequentially transfer the toner images formed by the process cartridges 10Y, 10C, 10M, and 10BK.

The configuration of each process cartridge 10Y, 10C, 10M, 10BK will be described in detail later with reference to FIGS.
A primary transfer roller 14 as a primary transfer member is disposed at a position facing each process cartridge across the transfer belt 17, and a toner image formed by each process cartridge is electrostatically transferred to the transfer belt 17. It can be done.
The transfer belt 17 is wound around a plurality of rollers, and a secondary transfer roller 18 serving as a secondary transfer member for performing secondary transfer onto a recording sheet is disposed so as to face one of the rollers. Yes.

The recording paper P fed from the paper supply unit 7 is conveyed to the secondary transfer position. In the paper feeding unit 7, a sheet of recording paper P is fed toward the position of the registration roller 19 by a feeding roller 8 through a separation mechanism (not shown). The registration roller 19 conveys the recording paper P toward the secondary transfer position after setting the registration timing.
As for the toner image carried on the transfer belt 17, a color image of a desired color is transferred onto the recording paper P at the secondary transfer position.
The recording paper P that has passed the secondary transfer position undergoes a fixing process by the fixing device 20 using the heat roller fixing method, and is then discharged toward the paper discharge tray 5 via the discharge roller 29. The copy output operation will be described later.

In the image forming apparatus 1 according to the present exemplary embodiment, each of the image forming apparatuses is configured to transfer only a black (BK) image onto the recording paper P and to transfer a full-color image onto the recording paper P using all the image forming units. The contact state of the transfer belt 17 with respect to the image portion is varied.
When a full-color image is formed, the extended surface of the transfer belt 17 is brought into contact with a drum-shaped photoconductor (hereinafter referred to as a photoconductor drum) 11 corresponding to a photoconductor that is an image carrier in each image forming unit.
On the other hand, in the case of only a black (BK) image, the opposing contact between the image forming unit other than this color and the transfer belt 17 is released.
As a method for this, for example, one of the rollers positioned at both ends of the transfer belt in the extending direction is displaced to a position where the transfer belt 17 is brought into contact with or separated from an image forming portion capable of forming an image other than black. There is. When the transfer belt 17 is separated from the image forming portion of a color other than black (BK), the primary transfer transfer roller 14 located inside the transfer belt 17 also moves in the same direction.

  The characteristics of this embodiment will be described for the image forming apparatus 1 having the above configuration.

The features of this embodiment are as follows.
(1) Of the image forming units, the lubricant supply mechanism 16 is provided only in an image forming unit that is frequently used.
(2) The image forming unit including the lubricant supply mechanism 16 is positioned and arranged on the upstream side or the most downstream side in the moving direction of the stretched surface of the transfer belt 17 used as an intermediate transfer member.
(3) The image forming section provided with the lubricant supply mechanism 16 moves the stretched surface of the transfer belt 17 when the transfer belt 17 is provided so as to be able to contact and separate from an image forming section other than black (BK). It is positioned on the most downstream side in the direction of
(4) The lubricant supplied from the lubricant supply mechanism 16 provided in the frequently used image forming unit moves the transfer belt 14 via the transfer belt 14 in contact with the photosensitive drum 11. Is supplied to the photosensitive drum 11 of the image forming unit located at the next stage upstream in the direction.
(5) As a charging method used for charging the photosensitive drum 11 included in each image forming unit, the image forming unit provided with the lubricant supply mechanism is a non-superimposing direct current (DC) and alternating current (AC) component. A contact charging method is used, and a contact charging method using only direct current (DC) is used in other image forming units.

Hereinafter, a configuration for achieving each feature will be described.
2 and 3 are schematic diagrams showing the configuration of a process cartridge used in the image forming unit. FIG. 2 shows a process cartridge capable of forming a black (BK) image, which is a frequently used color, and FIG. 3 shows a process cartridge of an image forming unit other than black (BK).

Among the image forming units shown in FIG. 2, the process cartridge 10BK used for the black (BK) image forming unit (for convenience, the process cartridge may be indicated by reference numeral 10BK) No lubricant supply mechanism (indicated by reference numeral 16 in FIG. 2) is provided.
In FIG. 2, a photosensitive drum 11 capable of carrying an image is provided inside a process cartridge used for each image forming unit.

Around the photosensitive drum 11, various devices for executing image forming processing are arranged along the rotation direction (the arrow direction in the drawing).
These various devices correspond to a charging device 12, a writing device used for forming a latent image (denoted by a symbol L for convenience), a developing device 13, a primary transfer roller 14, a cleaning device 15, and a lubricant supply mechanism 16. Yes.
Among the devices arranged around the photosensitive drum 11, the other devices except the charging device 12 and the lubricant supply mechanism 16 are the same as the devices used in the well-known electrophotographic copying process. Yes. In other words, the writing device (device denoted by reference numeral 6 in FIG. 1) is not shown, but a laser light source capable of irradiating the photosensitive member with writing light for each color separation color, a polygon mirror as a polarizing means, and a photosensitive member. A plurality of mirrors and lenses constituting the optical path are used.

The developing device 13 employs a two-component developing system in which a two-component developer containing toner and carrier is used.
For this reason, the developing device 13 defines the amount of developer carried on the developing sleeve 13a that is a developer carrying member for supplying the developer to the photosensitive drum 11, the developer agitating / conveying members 13b1 and 13b2, and the developing sleeve 13a. A layer thickness regulating blade 13c is provided.
The cleaning device 15 includes a cleaning blade 15 a that removes untransferred toner from the photosensitive drum 11 and a collection member 15 b that collects the removed toner. The substance removed from the photosensitive drum 11 by the cleaning device 15 corresponds to untransferred toner, paper powder, and discharge products generated during charging.

On the other hand, the lubricant supply mechanism 16 that is provided in the image forming unit that is used most frequently and is not provided in any other image forming unit includes a solid lubricant 16a, an application member 16b, a pressure member 16c, and a leveling member. A blade 16d is used.
The solid lubricant 16a is formed by dissolving a lubricating oil additive mainly composed of zinc stearate, which is one of fatty acid metal salts, and then solidified by molding, and is applied by a compression spring 16c used as a pressure member. It is biased toward 16b.
The solid lubricant 16 a is supplied to the photosensitive drum 11 by being scraped off by the coating member 16 b positioned between the solid lubricant 16 a and the photosensitive drum 11.
The application member 16b is a rotating brush in which brush hairs are planted on the outer peripheral surface of the foamed elastic layer.
The lubricant supplied to the photosensitive drum 11 by the coating member 16b is leveled to a uniform thickness by the leveling blade 16d.
The solid lubricant 16a is urged toward the application member 16b by the configuration shown in FIG.
That is, in FIG. 4, the solid lubricant 16a is attached to a support blade 16f that can slide in the casing 16e.
The support blade 16f has a pressing surface opposite to the support surface of the solid lubricant 16a.
That is, the oscillating ends of a pair of pressing plates 16g that are swingably supported by the casing 16e are in contact with the pressing surface. The pressing plates can swing in the direction in which the supporting blade 16f is pressed by the behavior of the tension spring 16h disposed between the opposing surfaces.
In this configuration, the pressing plate 16g swings following the change in thickness according to the amount of consumption of the solid lubricant 16a. Therefore, the solid lubricant can be applied with a constant force regardless of the thickness change of the solid lubricant 16a. 16a is urged toward the application member 16b.

  In the lubricant supply mechanism 16 having the above configuration, when the transfer belt 17 can be brought into contact with and separated from an image forming unit other than the black (BK) image forming unit, the stretched surface of the transfer belt 17 moves. The black (BK) image forming unit, which is the image forming unit located on the most downstream side in the direction in which the recording is performed, is provided.

On the other hand, as described in the feature (5), the charging device 12 used in the present embodiment is different in charging method between an image forming unit provided with the lubricant supply mechanism 16 and an image forming unit not provided.
As shown in FIG. 2, the image forming unit including the lubricant supply mechanism 16 uses a non-contact charging method in which a charging roller 12 a used as a charging member is not in contact with the photosensitive drum 11. A charging bias in which direct current (DC) and alternating current (AC) are superimposed is applied. In FIG. 2, symbol δ indicates a gap facing the photosensitive drum 11.
On the other hand, in the image forming unit not provided with the lubricant supply mechanism, as shown in FIG. 3, a contact charging method in which the charging roller 12a ′ contacts the photosensitive drum 11 is used, and a direct current (DC) charging bias is used. Is applied.

Since the present embodiment is configured as described above, as shown in FIG. 1, the image forming unit including the lubricant supply mechanism 16 is positioned at the most downstream side in the direction in which the stretched surface of the transfer belt 17 moves. Yes.
A part of the lubricant supplied to the photosensitive drum 11 in the lubricant supply mechanism 16 is transferred to the transfer belt 17 in contact with the photosensitive drum 11.
With the movement of the transfer belt 17, yellow (Y), which is the next image forming portion with respect to the black (BK) image forming portion, is positioned on the most upstream side in the moving direction of the extending surface of the transfer belt 17. The lubricant is supplied to the image forming unit via the transfer belt 17. The next-stage image forming unit described above corresponds to the image forming unit that receives the supply of lubricant the earliest.

In this configuration, an increase in the coefficient of friction on the surface of the photosensitive drum 11 can be suppressed without providing a lubricant supply mechanism in all the image forming units, so that the mechanism can be simplified and the apparatus cost can be increased. Can be suppressed.
In particular, by providing a lubricant supply mechanism in the image forming unit that is in constant contact with the transfer belt 17, the opportunity for supplying the lubricant to the transfer belt 17 is continued. The lubricant can be supplied to the image forming unit. For this reason, it is possible to prevent an increase in the coefficient of friction on the photosensitive member in the image forming portion that is not frequently used, and to stably supply the lubricant.

  In addition, since the lubricant supply mechanism 16 is permanently installed in the black (BK) image forming unit, which is a frequently used color, the photosensitive drum 11 and the cleaning device used in the frequently used image forming unit. It is possible to extend the lifetime of 15.

  Further, by selecting a charging method and a charging bias of the charging device 12 facing the photosensitive drum 11, a charging member is used in an image forming unit in which the lubricant is directly supplied to the photosensitive drum 11. The flying and adhesion of the lubricant to a certain charging roller 12a can be suppressed. Thereby, uneven charging due to contamination of the charging roller 12a can be suppressed.

Next, other features of the image forming apparatus according to the embodiment of the present invention will be described.
Another feature is that attention is paid to the adhesion of the lubricant to the charging roller 12a used for charging the photosensitive drum 11, and the adhesion state is made uniform to prevent charging unevenness.

  The charging rollers 12a and 12a 'facing the photosensitive drum 11 are members that affect the charging characteristics when a lubricant is attached. That is, when the lubricant adheres, charge increase at the time of charging is hindered due to an increase in resistance at the adhered portion. As a result, there is a possibility that a predetermined charged state cannot be obtained on the surface of the photoreceptor. In addition, since the adhesion of the lubricant is not always uniform in the longitudinal direction of the charging rollers 12a and 12a ', uneven charging in the longitudinal direction is likely to occur.

One of the causes of the uneven adhesion of the lubricant in the longitudinal direction of the charging rollers 12a and 12a ′ is the configuration of the image forming unit.
The cause of this will be described with reference to FIG.
FIG. 5 shows a configuration in which the photosensitive drum 11 is opposed to the upper upper surface of the transfer belt 17, unlike the configuration shown in FIG. 1. In FIG. 4, the members described in FIGS. 2 and 3 are denoted by the same reference numerals. Also. Reference numeral BCL indicates a cleaning device for the transfer belt 17.

  In this configuration, as in the case described with reference to FIGS. 2 and 4, the solid lubricant 16a used in the lubricant supply mechanism 16 is urged toward the photosensitive drum 11 by the compression spring 16c, and is applied by the coating member 16b. It is supplied to the surface of the photosensitive drum 11.

  The application member 16b is easily bent by being biased against the solid lubricant 16a, and the maximum position of the bending is the center in the longitudinal direction. For this reason, the nip determined by the facing gap of the coating member 16b with respect to the photosensitive drum 11 is maximized at the center in the longitudinal direction. Since the nip increases the degree of contact between the photosensitive drum 11 and the coating member 16b, the amount of lubricant supplied to the photosensitive drum 11 in this position is larger than that in other positions in the longitudinal direction.

  As a result, in the transfer belt 17 in which the lubricant is transferred from the photosensitive drum 11 of the image forming unit provided with the lubricant supply mechanism 16, the lubricant in the center portion increases in the width direction parallel to the longitudinal direction of the application member 16b. . As a result, the amount of lubricant adhering to the photosensitive drum 11 is increased in the central portion in the longitudinal direction in the next image forming unit.

  When the lubricant on the photosensitive drum 11 adheres to the charging roller 12a facing the photosensitive drum 11 of the image forming unit that receives the supply of the lubricant via the transfer belt 17, the amount of adhesion at the central portion in the longitudinal direction is increased. Become more. As a result, as described above, uneven charging occurs due to the difference in resistance in the longitudinal direction of the charging roller 12a depending on the amount of adhesion.

  In this embodiment, in order to control the adhesion state of the lubricant in the longitudinal direction of the charging roller 12a, the opposing relationship of the photosensitive drum 11 with respect to the stretched surface positioned above and below the transfer belt 17 and the non-contact charging in the charging device. The following configurations are used depending on the method and the contact charging method.

  First, as shown in FIG. 2, the photosensitive drum 11 is disposed below the extended surface of the transfer belt 17 below the extended surface, and a lubricant supply mechanism 16 is provided so that a non-contact charging method is used. The image forming unit used has the following configuration.

(A) As shown in FIG. 6, the gap between the charging roller and the photosensitive drum 11 is made wider at the center in the longitudinal direction than at the end.
The shape of the charging roller 12a for this configuration can be a drum shape in which both end portions in the longitudinal direction are expanded in diameter with respect to the central portion.
(B) In order to set the relationship of the opposing gaps listed in (A), as shown in FIG. 2, the photosensitive drum 11 is located below the developing surface located below the transfer belt 17, and the photosensitive drum 11. The charging roller 12a of the charging device 12 faces the lower peripheral surface side. FIG. 7 is a diagram showing an arrangement configuration of the photosensitive drum 11 and the charging roller 12a. In the drawing, the charging roller 12a has the maximum amount of bending at the center in the longitudinal direction due to its own weight.

  In the above configuration, since the adhesion state of the lubricant from the photosensitive drum 11 can be reduced in the longitudinal center of the charging roller 12a, the adhesion state of the lubricant is equalized over the entire longitudinal direction of the charging roller 12a. be able to. Thereby, it is possible to eliminate the difference in the surface resistance by eliminating the difference in the adhesion state that is the cause of the uneven charging. As a result, the occurrence of uneven charging is prevented.

The above-described configuration in which the amount of lubricant adhering at the central portion in the longitudinal direction of the charging roller 12a is different from that at the end portion in the longitudinal direction can be applied to an image forming unit using a contact charging method.
In other words, the contact charging method is based on the premise that the charging roller 12 a contacts the photosensitive drum 11. For this reason, the amount of lubricant adhering at the central portion in the longitudinal direction of the charging roller 12a tends to increase more than other positions for the reasons described above. Therefore, by using the above-described configuration, it is possible to reduce the amount of adhesion at the center in the longitudinal direction, and to suppress uneven charging.

On the other hand, in the contact charging method, the following configuration can be adopted in order to vary the lubricant adhesion amount in the central portion in the longitudinal direction described above.
(C) The contact width forming the charge width obtained by the contact between the photosensitive drum 11 and the charging roller 12a is wider at the end in the longitudinal direction than at the center in the longitudinal direction.
The contact width forming the charging width in this case means a state where the contact area at the center in the longitudinal direction is smaller than the end portion as shown in black in FIG. FIG. 8B shows a state where the above-described charging width is the same at the center and the end in the longitudinal direction.

Next, another feature of the present embodiment will be described.
Another feature in the present embodiment is as follows.
(D) In the image forming unit on the side that receives the supply of lubricant via the transfer belt 17, the charging roller 12 a and the photosensitive drum for the image forming unit positioned on the most upstream side in the moving direction of the transfer belt 17. 11 is linked in a relationship that does not cause a linear velocity difference.
In this feature, it is possible to prevent an increase in the scraping action of the lubricant due to a difference in speed between them, and to suppress the adhesion of the lubricant to the charging roller 12a.

(E) The absolute value of the central potential of the bias potential applied to the charging roller 12a in the image forming unit to be processed in (D) is determined by the lubricant via the transfer belt 17 in the same manner as this image forming unit. It is larger than the absolute value in one of the other image forming units supplied to the drum 11.
In this configuration, among the image forming portions where the lubricant is supplied to the photosensitive drum 11 via the transfer belt 17, the transfer belt on the most upstream side in the moving direction of the transfer belt, which is the position where the most lubricant is supplied. The increase in the resistance of the charging roller at the image forming unit can be canceled out by increasing the bias potential. As a result, even when the amount of lubricant adhering to the charging roller 12a is large, a decrease in the amount of charge on the photosensitive drum 11 is prevented.

  In the above configuration, the charging roller is controlled by controlling the adhesion state of the lubricant to the charging roller according to the shape of the charging roller, the opposing relationship between the charging roller and the photosensitive member, and the change of charging conditions assuming the case of adhesion. The occurrence of uneven charging at 12a can be prevented.

On the other hand, the uneven charging on the charging roller 12a is caused by the adhesion state of the lubricant adhering to the charging roller 12a. Therefore, the adhesion state can be controlled by a configuration other than the configuration on the charging roller side. .
For this purpose, there are firstly a solid lubricant, secondly cleaning the charging roller, thirdly a cleaning member for removing untransferred toner from the photoreceptor, and fourthly a state of the surface of the photoreceptor.

Each configuration will be described below.
Regarding the first solid lubricant, the hardness of the central portion in the longitudinal direction is made higher than the hardness of the end portion in the longitudinal direction.
As a result, the lubricant 16a pressed against the application member 16b by the urging force of the compression spring 16c is suppressed in the amount of scraping by the application member 16b from the end side at the center in the longitudinal direction.
For this reason, since the lubricant supplied to the photosensitive drum 11 is also supplied in the longitudinal direction less than the end side, even if the nip in the longitudinal direction due to the bending deformation of the coating member 16b is increased, the longitudinal direction is increased. The amount of lubricant attached at the center in the direction can be reduced.
As a result, in the image forming unit that receives the supply of lubricant from the transfer belt 17, the lubricant adhering to the photosensitive member is in a state of being equalized in the longitudinal direction, so that even when the lubricant adheres to the charging roller, the charging roller The adhesion state in the longitudinal direction is equalized, and the occurrence of uneven charging is suppressed.

For the cleaning of the second charging roller, the configuration shown in FIG. 9 is used.
The configuration shown in FIG. 9 is intended for a configuration in which the photosensitive drum 11 is arranged above the transfer belt 17 and the charging roller 12a is arranged facing the upper peripheral surface of the photosensitive member, as shown in FIG. It is said. It is also possible to target the configuration shown in FIGS.
The image forming section (reference numeral 10Y) in which the lubricant supplied to the transfer belt 17 from the image forming section provided with the lubricant supply mechanism 16 is first supplied to the photosensitive drum 11 is the most upstream side of the transfer belt 17 in the moving direction. The cleaning member 12b is in contact with the charging roller 12a.

  The cleaning member 12b is a roller using urethane foam, and is pressed against the upper peripheral surface of the charging roller 12a by a spring (not shown). The pressing force of the cleaning member 12b against the charging roller 12a corresponds to the resultant force of its own weight and the biasing force of the spring, and it is effective to remove the lubricant from the surface over the entire longitudinal direction of the charging roller 12a. Can be done.

As shown in FIG. 10, the cleaning member 12b has a crown shape as shown in FIG. 10, and the outer diameter of the central portion in the longitudinal direction is larger than the outer diameter of the end portion in the longitudinal direction.
In other words, the contact width corresponding to the charging width is reduced by the fact that the central portion in the longitudinal direction of the charging roller 12a has a smaller facing distance than the end side. As a result, the scraping amount at the central portion in the longitudinal direction of the charging roller 12a becomes larger than the scraping amount at the end portion side.
Moreover, when contacting the charging roller 12a, the urging force by the spring leads to its own elastic deformation and nighttime contraction deformation. Therefore, the contact property along the longitudinal direction of the charging roller 12a is also improved throughout the longitudinal direction. The amount of scraping can be secured.

In the image forming unit 10Y to which the lubricant is supplied most quickly by the transfer belt 17 in this configuration, even when the lubricant is supplied to the photosensitive drum 11 with the largest amount of lubricant, the charging roller 12a facing the photosensitive drum 11 is supplied. The adhered lubricant is removed by the cleaning member 12b.
As a result, the charging roller 12a avoids the adhesion of the lubricant in the longitudinal direction, thereby eliminating the occurrence of uneven charging in the longitudinal direction.

  The cleaning member 12b can also contain a melamine resin for the purpose of improving the heat resistance, weather resistance, rigidity enhancement and electrical insulation in the urethane foam.

Next, the third cleaning member will be described.
As shown in FIGS. 2 and 3, the cleaning device 15 that removes the untransferred toner from the photosensitive drum 11 after the secondary transfer uses a cleaning blade 15 a having a tip that contacts the photosensitive drum 11. Yes.
As shown in FIG. 11, the cleaning blade 15 a uses a counter contact in which the tip contacts the surface of the photosensitive drum 11 in a direction opposite to the moving direction of the photosensitive drum 11.
Of the cleaning blades 15b provided in each image forming unit, the image forming unit in the position where the lubricant is supplied first to the image forming unit through which the lubricant is supplied to the photosensitive drum 11 via the transfer belt 17. The cleaning blade 15b has a higher hardness than that of the other image forming portions.
That is, the cleaning blade 15b provided in the image forming unit 10Y located at the most upstream in the moving direction of the transfer belt 17 has a hardness of the contact surface 15a1 with the photosensitive drum 11 with respect to the other image forming units 10C and 10M. It is high.

In this configuration, the tip of the cleaning blade 15 b in the image forming unit 10 </ b> Y where the amount of lubricant supplied via the transfer belt 17 is the largest is less likely to be swung at the contact position with the photosensitive drum 11. As a result, the slipping of the lubricant that occurs when drowning is prevented, and the adhesion of the lubricant to the charging roller 12a is suppressed.
As a configuration for preventing the lubricant from slipping through, the contact pressure at the center in the width direction of the cleaning blade 15b parallel to the longitudinal direction of the photosensitive drum 11 is made stronger than that at the end in the longitudinal direction. Is also possible.

Incidentally, as with the cleaning blade 15b, a member whose tip is in contact with the photosensitive drum 11 is a leveling blade 16d provided in the lubricant supply mechanism 16.
The leveling blade 16d is leveled without damming the lubricant by using a trailing contact in which the tip contacts in a direction following the moving direction of the photosensitive drum 11.
In this case, as described above, there is a phenomenon in which the amount of lubricant attached at the center in the longitudinal direction of the charging roller is larger than that at the end.

Therefore, the contact pressure at the center in the longitudinal direction of the leveling blade 16d is made stronger than the contact pressure at the end in the longitudinal direction.
Thereby, slipping of the lubricant is suppressed at the longitudinal center of the leveling blade 16d on the photosensitive drum 11. As a result, the lubricant adhering to the charging roller 12a facing the photoconductor drum 11 is suppressed at the center in the longitudinal direction, and the amount of adhesion is made uniform over the entire longitudinal direction.
As a result, it is possible to prevent the occurrence of charging unevenness by suppressing the change in surface resistance due to the difference in the amount of lubricant adhering in the longitudinal direction of the charging roller 12a.

Next, the fourth configuration will be described.
The fourth configuration is characterized in that the composition on the surface of the photoconductor is a composition in which the lubricant is difficult to adhere.
That is, as shown in FIG. 12, filler material 11a made of fine particles is scattered on the surface layer of the photosensitive drum 11 included in the image forming unit 10BK provided with the lubricant supply mechanism 16. The distribution of the filler material 11a is formed between the transfer belt 17 and secures the transfer nip width. In this region, the distribution density is low, and in the other longitudinal side regions, the distribution density is higher than the central portion. ing.

  In such a configuration, the contact area with the transfer belt 17 on the surface of the photosensitive member can be reduced, so that the amount of lubricant adhering to the transfer belt 17 is not increased more than necessary. As a result, the amount of lubricant adhering to the photoreceptor in the image forming unit that receives the supply of lubricant via the transfer belt 17 does not become excessive. As a result, inadvertent adhesion of the lubricant to the charging roller 12a facing the photosensitive drum 11 is prevented.

Note that the adhesion of the lubricant to the charging roller, in particular, the charging roller in the image forming unit 10Y in the position where the supply is earliest among the image forming units that receive the supply of lubricant through the transfer belt 17 is targeted. In order to prevent the occurrence of uneven charging, there is the following method in addition to the above-described configuration.
(1) Use the developer to be used.
(2) Change the surface form of the charging roller.
(3) Bias control by a lubricant application member is performed.
(4) In a low-humidity and low-temperature environment, the linear speed of the coating member is switched to a low speed in cases other than this environment.

Hereinafter, the configuration described above will be described.
First, as the configuration relating to (1), a two-component developer including toner and carrier as a developer is used in the developing device in the image forming unit 10Y where the lubricant is supplied from the transfer belt 17 earliest.
Thereby, a part of the lubricant adhering to the photoconductor is scraped off by the carrier contained in the developer, so that it is possible to avoid the excessive lubricant adhering to the charging roller.
Note that the configuration using the two-component developer can be applied to the developing device of the image forming unit 10BK provided with the lubricant supply mechanism 16. Accordingly, excessive adhesion of the lubricant to the transfer belt 17 is suppressed, and adhesion of the lubricant to the charging roller 12a in the image forming unit 10Y that receives the supply of the lubricant from the transfer belt earliest is suppressed.

As a configuration relating to (2), the surface roughness (Rz) of the charging roller 12a is set to 30 μm or less.
In this configuration, the concave portion on the surface becomes shallow, so that the lubricant can be easily removed.

As a configuration relating to (3), the application member 12b is a member capable of injecting charges into the lubricant. Specifically, a biasable member capable of injecting charges having the same polarity as the toner is used.
Thereby, the lubricant adhering to the photosensitive drum 11 can be transferred to the recording paper P together with the toner. As a result, the excess lubricant adhering to the photosensitive drum 11 is eliminated, so that the amount of lubricant adhering to the charging roller 12a is reduced, and deterioration of the charging bias effect on the surface of the charging roller can be suppressed.
The configuration related to (4) is an item that affects the amount of lubricant consumed. In other words, when there is a characteristic that the material of the lubricant is likely to be scraped off in a low temperature and low humidity environment, the rotational speed of the coating member 16b is lowered to make the linear velocity equal to or lower than the speed other than in this environment. Thereby, the scraping amount can be reduced and the consumption amount can be made constant. As a measure for suppressing the consumption amount of the lubricant due to such an environmental change, it is possible to reduce the scraping amount by the application member 16b by making the longitudinal central portion of the lubricant concave.

  In the present embodiment having the above-described configuration, the lubricant transferred from the image forming section provided with the lubricant supply mechanism 16 to the transfer belt 17 is lubricated earliest among the image forming sections without the lubricant supply mechanism 16. It is possible to prevent the occurrence of uneven charging in the image forming unit 10Y that receives the supply of the agent.

  Next, the mechanical characteristics, material characteristics and operation of each member used in the image forming apparatus shown as the present embodiment will be described below.

First, the operation of the image forming apparatus 1 will be described as follows.
The document is transported from the document table by the transport rollers of the document transport unit 3 and placed on the contact glass of the document reading unit 4.
Then, the document reading unit 4 optically reads the image information of the document placed on the contact glass.
The document reading unit 4 scans an image of a document on the contact glass while irradiating light emitted from an illumination lamp. The light reflected from the document forms an image on the color sensor via the mirror group and the lens.
The color image information of the original is read for each color separation light of RGB (red, green, blue) by the color sensor, and then converted into an electrical image signal.
Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by an image processing unit (not shown) based on RGB color separation image signals, and yellow, magenta, cyan, and black color images are processed. get information.
Image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 6.

  In the writing unit 6, laser light (exposure light) based on the image information of each color is irradiated onto the corresponding photosensitive drums 11 of the process cartridges 10Y, 10M, 10C, and 10BK, respectively.

On the other hand, the four photosensitive drums 11 rotate in the clockwise direction in the figure.
First, the surface of the photosensitive drum 11 is uniformly charged at a position facing the charging roller 12a or 12′a (this is a charging process).
A charged potential is formed on the photosensitive drum 11 by a charging bias by a charging roller.

Thereafter, the surface of the charged photosensitive drum 11 reaches the irradiation position of each laser beam.
In the writing unit 6, laser light corresponding to the image signal is emitted from the light source corresponding to each color. Although not shown, the laser light is incident on the polygon mirror and reflected, and then passes through a plurality of lenses. The laser light that has passed through the plurality of lenses passes through different optical paths for each of the yellow, magenta, cyan, and black color components (this is an exposure process).
When a writing process corresponding to the image information of each color, that is, a so-called exposure process is performed, an electrostatic latent image is formed on the photosensitive drum 11.

The electrostatic latent image is subjected to a visible image processing by a developer supplied in a developing unit 13 (hereinafter also referred to as a developing device 13) provided around the photosensitive drum 11 (developing process). ).
When the toner image subjected to the visible image processing with the toner in the developer is opposed to the photosensitive drum 11, it receives a transfer bias from the primary transfer roller 14 and is transferred to the transfer belt 17 (this is a primary transfer process).

The superimposed images sequentially transferred from the photosensitive drums 11 to the transfer belt 17 are collectively transferred to the recording paper P at the secondary transfer position where the secondary transfer roller 18 is located (secondary transfer process).
The photosensitive drum 11 after the primary transfer to the transfer belt 17 is charged by the charging device 12 after the untransferred toner is removed by a cleaning unit (hereinafter also referred to as a cleaning device) 15 (in a cleaning process). The process is executed to prepare for the next image formation.
As described above, the recording paper P onto which the superimposed images are collectively transferred from the transfer belt 17 at the secondary transfer position is fixed by melting and penetrating the recording paper P with heat and pressure in the fixing device 20. .

The fixed recording paper P is discharged toward the paper discharge tray 5 via the discharge roller 29.
The above is the operation when a full-color image is formed. However, during black (BK) image formation, the image forming process for only a single color is performed by separating the transfer belt 17 from the image forming unit for other colors. Executed. Since black (BK) is also used to improve gradation when forming a full-color image, it always faces the transfer belt 17 not only when forming a single color image, and the photosensitive drum 11 is placed on the transfer belt 17. It is in contact.

Although not shown in the figure, a toner replenishing unit provided in the main body of the image forming apparatus 1 is configured to be replaceable with a bottle-shaped toner container 28, and the toner container 28 is held and rotated and the developing unit 13. And a toner hopper for replenishing new toner.
The toner container 28 contains new toner (which is one of yellow, magenta, cyan, and black).
A spiral protrusion is formed on the inner peripheral surface of the toner container 28 (toner bottle).

The new toner in the toner container 28 is appropriately replenished from the toner replenishing port into the developing unit 13 as the toner in the developing unit 13 (existing toner) is consumed.
Although illustration is omitted, the consumption of toner in the developing unit 13 is indirectly caused by a reflection type photosensor facing the photosensitive drum 11 and a magnetic sensor installed below the second conveying screw 23b2 of the developing unit 13. Or detected directly.

The configuration of the photosensitive drum 11 as an image carrier will be described below.
The photoreceptor drum 11 is a negatively charged organic photoreceptor, and a photosensitive layer or the like is provided on a drum-shaped conductive support.
Although not shown, the photosensitive drum 11 has an undercoat layer that is an insulating layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a protective layer (surface layer) in this order on a conductive support as a base layer. Are stacked.
As the conductive support (base layer) of the photosensitive drum 11, a conductive material having a volume resistance of 10 ¹⁰ Ωcm or less can be used.
The photosensitive layer of the photosensitive drum 11 can have a laminated structure or a single layer structure.

First, a case where the photosensitive layer has a laminated structure including a charge generation layer and a charge transport layer will be described.
The charge generation layer is a layer mainly composed of a charge generation material.
A known charge generation material can be used for the charge generation layer.
Specifically, as the charge generation material, monoazo pigment, disazo pigment, trisazo pigment, perylene pigment, perinone pigment, quinacridone pigment, quinone condensed polycyclic compound, squalic acid dye, other phthalocyanine pigment, na A phthalocyanine pigment, an azulenium salt dye, or the like can be used.
These charge generation materials can be used alone or in combination of two or more.
In the charge generation layer, the charge generation material is dispersed in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., and this is dispersed on the conductive support (or below). It is formed by applying on the pulling layer and drying.
As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used.
The thickness of the charge generation layer is suitably about 0.01 to 5 μm (more preferably about 0.1 to 2 μm).

The charge transport layer can be formed by dissolving or dispersing the charge transport material and the binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer.
If necessary, one or more plasticizers, leveling agents, antioxidants and the like can be added.
The amount of the charge transport material is appropriately 20 to 300 parts by weight (preferably 40 to 150 parts by weight) with respect to 100 parts by weight of the binder resin.
The thickness of the charge transport layer is preferably 25 μm or less from the viewpoint of resolution and responsiveness.
The lower limit varies depending on the image forming process (in particular, the charging potential), but is preferably 5 μm or more.

Next, a case where the photosensitive layer has a single layer structure will be described.
The photosensitive layer having a single-layer structure is obtained by dissolving or dispersing the above-described charge generating substance, charge transporting substance, binder resin, etc. in an appropriate solvent and coating it on a conductive support (or undercoat layer). It can be formed by drying.
You may comprise from a charge generation material and binder resin, without containing a charge transport material.
Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
As the binder resin, in addition to the binder resin used when the charge transport layer is formed, a binder resin used when the charge generation layer is formed may be mixed and used.
Furthermore, polymer charge transport materials can also be used favorably.
The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight (more preferably 50 to 150 parts by weight).

The photosensitive layer with a single-layer structure is a dip coating method or spray coating method in which a coating solution in which a charge generating material and a binder resin are dispersed together with a charge transporting material using a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane by a dispersing machine. It can be formed by coating with bead coat, ring coat or the like.
The film thickness of the photosensitive layer is suitably about 5 to 25 μm.
The undercoat layer of the photosensitive drum 11 is generally composed mainly of a resin. However, considering that the photosensitive layer is applied on the resin with a solvent, the undercoat layer has high solvent resistance with respect to a general organic solvent. A resin is desirable.
Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.

A fine powder pigment of metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide may be added to the undercoat layer in order to prevent moire and reduce residual potential.
In addition, these undercoat layers can be formed using an appropriate solvent and coating method in the same manner as the photosensitive layer described above.
The thickness of the undercoat layer is suitably about 0 to 5 μm.
The protective layer of the photosensitive drum 11 is for reducing mechanical wear on the surface of the photosensitive drum 11.

The protective layer in the present embodiment is formed of a binder resin having a crosslinked structure.
The crosslinked structure is a three-dimensional network structure formed by using a reactive monomer having a plurality of crosslinking functional groups in one molecule and causing a crosslinking reaction using light or thermal energy.
The binder resin having this network structure exhibits high wear resistance.
From the viewpoint of electrical stability, printing durability, and life, a monomer having a charge transporting ability can be used in whole or in part as the reactive monomer.
By using such a monomer, a charge transport site is formed in the network structure, and the function as a protective layer is sufficiently exhibited.

Examples of the reactive monomer having charge transporting ability include a compound containing at least one charge transporting component and a silicon atom having a hydrolyzable substituent in the same molecule, and a charge transporting component in the same molecule. A compound containing a hydroxyl group, a compound containing a charge transporting component and a carboxyl group in the same molecule, a compound containing a charge transporting component and an epoxy group in the same molecule, a charge transporting component in the same molecule And a compound containing an isocyanate group can be used.
These charge transport materials having a reactive group may be used alone or in combination of two or more.

A reactive monomer having a triarylamine structure can also be used as the monomer having a charge transporting ability because of its high electrical and chemical stability and high carrier mobility.
In addition, monofunctional and bifunctional polymerizable monomers and polymerizable oligomers are used in combination for viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, low surface energy, friction coefficient reduction, and other functions. You can also

As these polymerizable monomers and oligomers, known ones can be used.
The protective layer is formed by polymerizing or crosslinking the hole transporting compound using heat or light.
When performing the polymerization reaction by heat, there are cases where the polymerization reaction proceeds only with thermal energy and a polymerization initiator is required, but in order to advance the reaction efficiently at a lower temperature, the initiator Is preferably added.
In the case of polymerization by light, it is preferable to use ultraviolet light as light, but the reaction rarely proceeds only by light energy, and a photopolymerization initiator is generally used in combination.
The polymerization initiator in this case mainly absorbs ultraviolet rays having a wavelength of 400 nm or less, generates active species such as radicals and ions, and initiates polymerization.
In addition, it is also possible to use together the heat | fever and photoinitiator mentioned above.

The protective layer having a network structure formed in this manner has high wear resistance, but has a large volume shrinkage during the crosslinking reaction, and may become cracked if it is too thick.
In such a case, the protective layer has a laminated structure, a protective layer made of a low molecular weight dispersion polymer is formed on the lower layer (photosensitive layer side), and a protective layer having a crosslinked structure is formed on the upper layer (surface side). You may do it.

  The image carrier protecting agent used in the image forming apparatus according to the embodiment of the present invention is a powder compacted body obtained by solidifying a powder containing at least the fatty acid metal salt (A) and the inorganic lubricant (B) by pressure molding. It is configured.

The following can be used as the fatty acid metal salt (A).
Barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc stearate, zinc oleate, magnesium oleate , Iron oleate, cobalt oleate, copper oleate, lead oleate, manganese oleate, zinc palmitate, cobalt palmitate, lead palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, lead caprylate, caprin Lead acid, zinc linolenate, cobalt linolenate, calcium linolenate, zinc ricinoleate, cadmium ricinoleate and mixtures thereof, but are not limited thereto. Without, for example, it may be used by mixing them. In the present invention, zinc stearate is used because it has an advantage of being particularly excellent in film formability on an image carrier.

On the other hand, the following are used as the inorganic lubricant (B). The inorganic lubricant (B) here refers to an inorganic compound that cleaves and lubricates itself or causes internal slip.
Specific examples include talc, mica, boron nitride, molybdenum disulfide, tungsten disulfide, kaolin, smectite, hydrotalcite compound, calcium fluoride, graphite, plate-like alumina, sericite, and synthetic mica. However, it is not limited to this. For example, boron nitride is easily cleaved and lubricated because hexagonal mesh planes in which atoms are firmly combined overlap with each other at a wide interval, and the force acting between the layers is only a weak van der Waals force. These inorganic lubricants may be surface-treated as necessary for the purpose of imparting hydrophobicity.

  In the image forming apparatus according to the embodiment of the present invention, in order to protect the image carrier, the lubricant applying member 16b is used, and a certain amount of the lubricant is obtained in a state where the size is sufficiently aligned. It is necessary to supply onto the carrier. Further, from the viewpoint of ease of handling, it is preferable that the image carrier protecting agent is processed into a solid form rather than remaining in a powder form. For this reason, in the present embodiment, the lubricant is solid in the form of a powder compacted body in which powdery raw materials are pressure-molded.

  In the present invention including the embodiments described above, the present invention including the following configurations described in detail above can also be used suitably in combination with each embodiment.

  Among the charging members using the contact charging method, the charging member of the image forming unit in the position where the lubricant is supplied earliest in the image forming unit where the lubricant is supplied to the image carrier through the intermediate transfer member. Are opposed to the cleaning member. The cleaning member has a configuration characterized in that the amount of scraping at the central portion in the longitudinal direction of the charging member is larger than the amount of scraping at the end portion side.

  The cleaning member has a configuration characterized in that urethane foam is used.

  The cleaning member has a configuration characterized by containing a melamine resin.

  The cleaning member has a configuration characterized in that the distance between the cleaning member and the image carrier at the center in the longitudinal direction is smaller than that at the end in the longitudinal direction.

  The cleaning member has a configuration characterized in that the outer diameter of the central portion in the longitudinal direction is larger than the outer diameter of the end portion in the longitudinal direction.

  The cleaning member has a configuration characterized in that it has a crown shape along the longitudinal direction of the charging member.

  The surface of the image carrier located upstream or downstream in the moving direction of the intermediate transfer member includes a filler material made of fine particles.

  The image carrier is provided with a cleaning member for removing untransferred toner, and the cleaning member uses a counter contact in which the tip contacts with the direction opposite to the moving direction of the image carrier. The cleaning blade of the image forming unit at the position where the supply of lubricant by the intermediate transfer member is the earliest among the image forming units has a different contact surface hardness with the image carrier. The configuration is higher than the hardness of the cleaning blade at the image portion.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10BK Process cartridge which forms image forming part provided with lubricant supply mechanism 10Y Process cartridge which forms image forming part which receives supply of lubricant through transfer belt earliest 11 Photoconductor 12 Charging device 12a Charging roller 15 Cleaning device 15a Cleaning blade 16 Lubricant supply mechanism 16a Solid lubricant 16b Application member 16d Leveling blade

JP 2011-64790 A JP 2011-174958 A JP 2011-18317 A JP 2008-70813 A JP 2001-138106 A

Claims (16)

Each of the plurality of image forming units arranged along the extending surface of the intermediate transfer member having the extending surface is provided with an image bearing member, and each process of charging, latent image forming, developing, and transferring is performed on the image bearing member. Thereafter, in an image forming apparatus provided with a mechanism for performing a cleaning process of the image carrier,
A lubricant supply mechanism is provided for one of the image carriers in each of the image forming units, and the lubricant supply mechanism is not provided in the image carriers of the other image forming units. An image forming apparatus, wherein a lubricant supplied from a supply mechanism is conveyed toward the image carrier of an image forming unit not provided with a lubricant supply mechanism via the intermediate transfer member.   The image forming apparatus according to claim 1, wherein the image forming unit including the lubricant supply mechanism is disposed on an upstream side or a downstream side in a direction in which a stretched surface of the intermediate transfer member moves.   The lubricant supply mechanism is provided for an image forming unit used for image formation of a color that is used most frequently, and the image forming unit that is used most frequently is in a direction in which a stretched surface of the intermediate transfer member moves. The image forming apparatus according to claim 1, wherein the image forming apparatus is positioned on the most downstream side.   The lubricant supply mechanism is arranged on the most upstream side in the moving direction of the intermediate transfer body when the intermediate transfer body is provided so as to be able to come into contact with and separate from an image forming section other than the most frequently used image forming section. The image forming apparatus according to claim 1, wherein the image forming apparatus is positioned.   A non-contact charging method in which direct current (DC) and alternating current (AC) are superimposed is used as a charging method for the image carrier of the image forming unit having the lubricant supply mechanism, and the lubricant supply mechanism is not provided. 5. The image forming apparatus according to claim 1, wherein a direct current (DC) contact charging system is used as a charging system for the image carrier of the image forming unit.   In the contact charging method for an image carrier that does not include the lubricant supply mechanism, the charge width in the longitudinal direction of the image carrier is wider on the end side than the center in the longitudinal direction. The image forming apparatus according to claim 5.   In the non-contact charging method for an image carrier provided with the lubricant supply mechanism, the gap between the image carrier and the charging member in the longitudinal direction is wider on the center side than the longitudinal end. The image forming apparatus according to claim 5.   8. The image forming apparatus according to claim 6, wherein the charging member used in the non-contact charging method and the contact charging method is a roller.   9. The image forming apparatus according to claim 7, wherein a charging member used in the non-contact charging method has a drum shape in the longitudinal direction.   The image forming apparatus according to claim 6, wherein a charging member used in the contact charging method is opposed to the image carrier below the image carrier.   The image forming apparatus according to claim 8, wherein the charging member is interlocked with the image carrier without generating a linear velocity difference.   The contact charging type charging member provided on the image bearing member of the image forming unit located on the most upstream side in the moving direction of the intermediate transfer member has a charging bias applied to other contact charging type charging members. The image forming apparatus according to claim 1, wherein the image forming apparatus is larger than an absolute value of the center potential.   The lubricant supplied from the lubricant supply mechanism is in a solid form, and the hardness at the center in the longitudinal direction is higher than the hardness at the end in the longitudinal direction. 10. The image forming apparatus according to claim 1.   The lubricant supply mechanism is provided with a leveling blade that defines the layer thickness of the lubricant on the image carrier, and the leveling blade makes the tip contact in the direction of the movement of the image carrier. Trailing contact is used, and the contact width at the center in the longitudinal direction of the charging member at the image forming portion that receives the lubricant supply first through the transfer belt is smaller than that at the end side. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   15. The image forming apparatus according to claim 14, wherein the leveling blade has a contact pressure at a central portion in the longitudinal direction of the image carrier higher than a contact pressure at an end portion in the longitudinal direction.   The lubricant supply mechanism includes an application member that supplies lubricant to the image carrier, and the application member switches the linear speed in a low-temperature and low-humidity environment to a lower speed than in other environments. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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