JP2001324907A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image flowing caused by ion product without adding ozone retaining preventing constitution even in the case of using an inexpensive OPC photoreceptor and to obtain the durability of the photoreceptor. SOLUTION: When the power source of the device is turned on or when specified time elapses after finishing one image forming action, an electromagnetic solenoid 28 is turned off and lubricant 18 is separated from a brush roller 17. The preliminary action (idle rotation) of the photoreceptor 1 is performed in such a state, and the surface of the photoreceptor 1 is cleaned in a state where a friction coefficient is high. When the idle rotation of the photoreceptor 1 is finished, the solenoid 28 is turned on and the lubricant 18 is supplied to the photoreceptor 1 so that the friction coefficient of the surface of the photoreceptor 1 may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, a charging process for uniformly charging the surface of a photoreceptor as an image carrier, an exposure process for forming an electrostatic latent image based on image information, and an electrostatic latent image , A developing step of transferring the developed toner image, and a cleaning step of removing the toner remaining on the surface of the photoconductor after the transfer. In the cleaning step, usually, the surface of the photoconductor is mechanically rubbed with a cleaning blade or a cleaning brush. However, when the surface of the photoconductor is mechanically rubbed, the surface of the photoconductor is worn out early. When the surface of the photoreceptor wears, the photosensitive characteristics deteriorate,
It adversely affects the formation of a proper electrostatic latent image. It is known that in order to prevent the abrasion of the photoconductor during cleaning, it is effective to reduce the coefficient of friction of the surface of the photoconductor. Conventionally, a lubricant is applied (supplied) to the surface of the photoconductor. That is being done.

FIG. 14 shows an example of a configuration for applying a lubricant.
A solid lubricant 109 is provided in the casing 102 of the cleaning means, and the photoconductor 100 and the lubricant 10 are provided.
9, a brush roller 108 is provided. Reference numeral 106 denotes a cleaning blade, 107 denotes a holding member for holding the cleaning blade 106, 104 denotes an auxiliary blade, and 105 denotes a waste toner collecting screw. The lubricant 109 is scraped off by the brush roller 108, and the scraped lubricant 109 is transferred onto the photoconductor 100. There is also known a system in which a solid lubricant is supplied in direct contact with the surface of a photoreceptor.

In this type of image forming apparatus, there is a problem related to charging, in addition to the problem related to the cleaning. When discharging is performed for charging, ozone is generated, and the ozone and components in the air are decomposed to generate water-soluble ion products such as NOx and SOx. This ion product adheres to the surface of the photoreceptor and further takes in moisture in the atmosphere to form a composite product, which lowers the surface resistance of the photoreceptor. As a result, a horizontal flow of the potential occurs at the edge of the electrostatic latent image drawn on the surface of the photoconductor, and as a result, an image flow occurs. When image deletion occurs, print quality is degraded.

It is known that when the charging means is a charging charger, the amount of generated ozone is larger than when the charging roller is used. In a configuration in which the charging charger is disposed almost directly above the photoconductor, after leaving for a long time after the image forming process (the image forming operation is not performed for a long time) or after turning off the power, the ion product causing the image flow may be directly below the charging unit. A large amount adheres to the surface of the photoconductor. In order to remove the partially adhered ion products, a method of polishing the surface of the photoreceptor, that is, a method of passing through a cleaning blade or a cleaning brush is generally used.

[0006] By mechanically rubbing with a cleaning blade or a cleaning brush, ion products causing image deletion can be removed. However,
In a configuration that supplies a lubricant to reduce the wear of the photoconductor,
Since the friction coefficient is reduced over the entire surface of the photoreceptor, it is difficult to remove ion products immediately below the charging unit. Japanese Patent Application Laid-Open No. 11-133,642 discloses a technique of using an amorphous silicon-based photoconductor, reducing the hardness of the outermost surface of the photoconductor, and removing ion products.

[0007]

The main purpose of using an amorphous silicon type photoreceptor is to increase the durability. In general, however, it is necessary to use a low-cost OPC photoreceptor to increase the durability. Is desired. By the way, OPC
It has been confirmed by experiments that the durability can be improved by supplying a lubricant to the photoconductor. In addition, in the case where the apparatus is normally used in such a configuration, there is no problem because no image deletion occurs. However, it has been found by experiments by the present inventors that image deletion occurs depending on environmental conditions. For example, it has been confirmed that when used in places with a lot of cigarette smoke, image deletion is likely to occur. The components of tobacco seem to have an effect, but the causal relationship is unknown. Further, in the image forming apparatus currently used, some measures have been taken to prevent the ozone generated by the charging means from staying in the airflow of the fan, but it is not always possible to operate the fan except when the apparatus is in use. It is not desirable from the viewpoint of energy saving, which is expected to progress further in the future.

Accordingly, the present invention is directed to an image forming apparatus which can prevent image deletion and obtain durability of a photoreceptor without adding an ozone stagnation prevention structure even when a low-cost OPC photoreceptor is used. Provision is its primary purpose.

[0009]

In this type of image forming apparatus, an image forming process is started after the photosensitive member starts to operate and rotates for about three revolutions. Time) exists. The purpose of the present invention is to utilize this preliminary operation to temporarily increase the coefficient of friction only during this period to enhance the scraping function of the cleaning blade or the cleaning brush, thereby removing ion products. More specifically, according to the first aspect of the present invention, there is provided an image forming apparatus including a cleaning unit for cleaning a surface of an image carrier and a friction reducing unit for reducing a friction coefficient of the surface of the image carrier. When the power is turned on,
The preliminary operation of the image carrier is performed in a state where the friction coefficient of the surface of the image carrier is temporarily increased.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a cleaning unit for cleaning a surface of an image carrier; and a friction reducing unit for reducing a friction coefficient of the surface of the image carrier. When a predetermined time elapses after the operation is completed, a preliminary operation of the image carrier is performed with the friction coefficient of the surface of the image carrier temporarily increased.

According to the third aspect of the present invention, the first or second aspect is provided.
In the image forming apparatus described above, the low friction means has a configuration for supplying a lubricant to the surface of the image bearing member, and can be in a state where the lubricant is not supplied selectively, and a friction coefficient can be reduced. Is temporarily increased by not supplying a lubricant.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the friction reducing means selectively positions a solid lubricant and a position where the lubricant is supplied and a position where the lubricant is not supplied. It has a configuration of having a contact / separation mechanism.

According to the fifth aspect of the present invention, the first to fourth aspects are provided.
In the image forming apparatus described in any one of the above, the configuration is adopted in which the lubricant is polytetrafluoroethylene.

According to a sixth aspect of the present invention, when the power supply of the apparatus is turned on, the image carrier for which the friction coefficient on the surface is reduced is temporarily increased while the friction coefficient of the image carrier is temporarily increased. The operation is performed, and then the image forming operation is started.

According to the present invention, when a predetermined time elapses after one image forming operation is completed, the friction coefficient of the image carrier whose surface friction coefficient is reduced is temporarily increased. Performs a preliminary operation of the image carrier, and then starts an image forming operation.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a copying machine as an image forming apparatus according to the present embodiment includes a photoreceptor 1, a discharging lamp 2, a charging charger 3, a developing unit 23, a registration roller pair 12, a guide plate 13, 24, a transfer roller 14, a separating claw 15, a cleaning unit 25, a friction reducing unit 32 provided in the cleaning unit 25, and the like. The developing means 23 includes a casing 9, stirring screws 7 and 8 for stirring the developer housed in the casing 9, a developing roller 5, and a doctor blade 6 for regulating a layer thickness of the developer on the developing roller 5. have.

The cleaning means 25 comprises a casing 19
, A cleaning blade 22, a holding member 21 for holding the cleaning blade 22, a waste toner collecting screw 20, an auxiliary blade 16, and the like. The friction reducing means 32 includes a brush roller 17 supported in the casing 19 and driven to rotate, an arm 26 swingably provided around a shaft 27, and a lubricating material fixed to one end of the arm 26. 18, the electromagnetic solenoid 28, the tip of the movable rod 28 of the electromagnetic solenoid 28 and the arm 2
6 has an engaging member 30 for connecting the other end. The contact / separation mechanism is constituted by the electromagnetic solenoid 28, the arm 26, the engaging member 30, and the like.

When a print button of an operation unit (not shown) is pressed, a predetermined voltage or current is sequentially applied to the charge removing lamp 2, the charging charger 3, the developing roller 5, and the transfer roller 14 at a predetermined timing, and at the same time, the light is exposed. The body 1, the charging charger 3, the transfer roller 14, the developing roller 5, the stirring screws 7, 8, and the brush roller 17 start rotating in a predetermined direction. The photoconductor 1 is neutralized by the neutralization lamp 2 and is uniformly negatively charged by the charging charger 3 (−950).
V). Thereafter, based on the image information, a latent image is formed (black solid potential is -150 V) with laser light 4 as exposure light emitted from exposure means (not shown).

The electrostatic latent image is developed by a magnetic brush formed by the developing roller 5 (developing bias is -600 V) to form a toner image. On the other hand, the transfer paper fed from a paper feeding means (not shown) is sent between the photoreceptor 1 and the transfer roller 14 at a timing synchronized with the leading edge of the image after the oblique displacement or the like is corrected by the registration roller pair 12. The toner image is transferred onto the transfer paper (+10 μA is applied). The transfer paper is separated from the photoreceptor 1 by the separation claw 15, and is discharged as a copy image to a discharge tray (not shown) through a fixing unit (not shown).

On the other hand, the toner remaining on the photoreceptor 1 after the transfer is transferred to the cleaning means 25 by the rotation of the photoreceptor 1, and is removed from the photoreceptor 1 by the surface rubbing of the cleaning blade 22. Photoconductor 1 and brush roller 17
When the roller starts rotating, the brush roller 17 scrapes the lubricant 18, and the scraped lubricant 18 is applied to the photoreceptor 1 from the brush roller 17. The brush roller 17 is a photosensitive member 1
However, the trailing method may be used depending on the position of the lubricant 18. Lubricant 18
Is a polytetrafluoroethylene whose charging series is higher in the “−charging series”, and is charged to “−polarity” when rubbed. The brush roller 17 is formed by forming a brush of polyester or acrylic resin into a roll shape, and also functions as a cleaning brush in the present embodiment.

The lubricant 18 transferred to the photoreceptor 1 is partially recovered at the development site, and when it reaches the transfer site, the transfer roller 14
Is also partially recovered. Then, the lubricant 18 remaining on the photoreceptor 1 without being collected reaches the portion of the cleaning unit 25 and is applied again by the brush roller 17. This process is repeated, and a certain range (0.08 to 0.
The coefficient of friction falls to 4). The coefficient of friction of the surface of the photoreceptor 1 becomes substantially constant when the amount of application of the lubricant 18 and the amount of recovery at the development site and the transfer site are balanced.

The purpose of applying the lubricant 18 to the photoreceptor 1 to lower the friction coefficient is to lower the relative friction coefficient between the cleaning blade 22 and the photoreceptor 1 so that the cleaning blade 22 does not scrape the photoreceptor 1. In other words, the wear of the cleaning blade 22 and the photoconductor 1 is suppressed, and the life of the photoconductor 1 is extended. As shown in FIG. 2, the wear amount of the photoconductor 1 decreases as the coefficient of friction decreases. Therefore, in order to extend the life of the photosensitive member 1, the lower the friction coefficient, the better. FIG. 2 shows a photosensitive member 1 having a diameter of 30 cm, a linear velocity of “114 mm / sec”, and an A4 transverse feed of 1
ToK2 (repetition of continuous image formation of two sheets), a brush roller 17 having a diameter of 15 mm using a straight bristle brush is used, and 200K when the brush roller 17 bites into the photosensitive member 1 is 1.5 mm. The relationship between the coefficient of friction after one sheet and the wear amount of the photoconductor 1 is shown.

When the friction coefficient decreases, the surface of the photoreceptor 1 is no longer abraded, and in a region of wear (4 μm or less) as indicated by a dashed line in FIG. NO on the surface of photoconductor 1 at high humidity
As x absorbs moisture, the resistance drops and an original latent image cannot be formed, so-called image deletion (image deletion) occurs.
Therefore, it is necessary that the friction coefficient be in a certain range. In the present embodiment, the lubricant 18 has a thickness of 2
mm of sheet-like solid PTFE (polytetrafluoroethylene), the amount of biting of the brush roller 17 into the photoreceptor 1 is 1.5 mm, and the amount of biting of the brush roller 17 into the lubricant 18 is 1.2 mm. , Contact width is 5-1
It is set to 2 mm. Under these conditions, the coefficient of friction changed in the range of 0.1 to 0.35. In this case, if it becomes constant at the maximum friction coefficient “0.35”, 200
The amount of wear is about 12 μm for K sheets. When the lubricant 18 is not supplied to the photoreceptor 1 having a diameter of 30 cm, the wear amount is about 20 μm / 200K. Therefore, supplying the lubricant 18 has an effect of about 40%.

The coefficient of friction of the surface of the photoreceptor 1 is determined by an Euler belt type as shown in FIG. 3 (A3 Mechanics / Mechanical Mechanics P35 (1986), Handbook of Mechanical Engineering, The Japan Society of Mechanical Engineers).
It is a value measured and calculated by a method referred to as "a". For example, when the weight of the weight W is 100 g, the friction coefficient μ is μ = I
n (F / 100) / (π / 2).

As shown in FIG. 4, PTFE is a completely symmetric linear polymer having a chemical structure in which CF ₂ units are simply repeated. In addition, PTFE is a nonpolar polymer, has very low intermolecular cohesion, and has a very small molecular chain surface, and thus has a small friction coefficient. In addition, since slippage easily occurs between molecules, when applied to the surface of the photoreceptor 1, a part of the applied PTFE adheres to the cleaning blade 22 and the like. For this reason, PTFE is interposed at the contact portion between the photoconductor 1 and the cleaning blade 22 or the like.
The friction between the cleaning blade 22 and the like becomes friction between the PTFE. As described above, since the coefficient of friction between PTFE is small, the cleaning blade 22
As a result, a large shearing force due to the above-mentioned conditions does not act, and the wear of the surface of the photoconductor 1 is effectively reduced.

A part of the PTFE applied to the photoreceptor 1
After being transferred to a “member slidingly contacting the photoreceptor 1” such as the cleaning blade 22 and the friction between the PTFE becomes dominant in the friction between the two, the friction coefficient between the PTFE is extremely small. Decrease. For this reason,
Depending on the contact pressure between the photoreceptor 1 and a member that comes into sliding contact with the photoreceptor 1 or the sliding conditions, the amount of PTFE applied may be automatically limited, and the application of the lubricant 18 at a certain level or more may be suppressed. Further, the collapse between the molecules of PTFE also occurs due to friction between the PTFE. For this reason, the PTFE adhered on the photoreceptor 1 is repeatedly adhered and removed at a certain ratio. The removal is performed by, for example, the cleaning unit 25,
The development is performed on the developing unit 23, transfer paper, or the like. Generally, foreign substances such as discharge products (NOx, SOx, etc.) that cause image blurring adhere to the surface of the photoconductor 1. When the lubricant 18 is not applied, the foreign material is removed together with the abrasion (scraping) of the surface layer of the photoconductor 1 caused by the cleaning means 25 and the like. When the lubricant 18 is applied, the abrasion of the photoreceptor 1 is reduced, so that foreign substances cannot be removed.
Although image defects may occur, in the case of lubricants that are repeatedly supplied and removed, such as PTFE, foreign substances also adhere
Since the removal is repeated, image defects can be effectively reduced.

As shown in FIG. 5, when the electromagnetic solenoid 28 is turned off, the movable rod 28 extends, the arm 26 rotates upward, and the lubricant 18 separates from the brush roller 17. That is, the lubricant 18 is located at a position where the lubricant 18 is not supplied. Next, the operation of removing a substance (ion product) that causes image deletion will be described with reference to the flowchart of FIG. It is checked by a control means (not shown) whether or not the power of the copying machine is turned on (S1). If the power is turned on, the control means turns off the electromagnetic solenoid 28 (S1).
2). When the image forming operation is performed, the photosensitive member 1 idles without the lubricant 18 being applied in the preliminary operation (S3). In this preparatory operation, the friction coefficient of the surface of the photosensitive member 1 increases, and the substance causing image flow attached immediately below the charging charger 3 is the cleaning blade 2.
2 and brush roller 17 for easy removal.

When the preparatory operation (idling) of the photosensitive member 1 is completed, the electromagnetic solenoid 28 is turned on (S4), and the lubricant 1
8 is located at the supply position where it contacts the brush roller 17. Thereafter, the image forming operation is started. In the present embodiment, the ion product is removed by using the preparatory operation of the photoconductor 1. However, the number of idle rotations for removing the ion product may be different from the preparatory operation.

In order to remove ion products with the brush roller 17 as a cleaning brush, the surface of the photosensitive member 1 must be polished with a hard and strong brush. However, if the brush is always strong, the amount of wear of the photoconductor 1 increases, and a desired photoconductor life cannot be obtained. FIG. 7 is a graph showing the relationship between the pressing force of the brush roller 17 against the photoconductor 1 in the axial direction of the brush roller 17 with a width of 100 mm and the photoconductor wear amount. The pressing force of the brush roller 17 was measured by an apparatus shown in FIG. That is, the plate-shaped photoconductor 115 placed on the movable base 111 capable of measuring the pressing force is applied to the brush roller 17 rotatably supported between the support members 112 fixed to the base member 110 at a predetermined cutting position. It is configured to press up to The black circles indicate brushes of normal strength, and the wear amount of the photoreceptor is 12 μm. However, it can be seen that the wear amount of the photoreceptor increases with the use of a hard and strong brush indicated by a cross. Therefore, the increase in the amount of wear of the photoconductor by the hard and strong brush roller 17 is reduced by the supply of the lubricant 18, and the supply of the lubricant 18 is stopped when removing the ion product.

Next, another embodiment will be described with reference to the flowchart of FIG. The control unit (not shown) checks whether a predetermined time has elapsed after one image forming operation is completed (S1), and when it has elapsed, turns off the electromagnetic solenoid 28 (S2). When the next image forming operation is performed, the photoreceptor 1 idles without the lubricant 18 being applied in the preliminary operation (S3). In this preparatory operation, the friction coefficient of the surface of the photoreceptor 1 increases, and the substance causing image flow adhering immediately below the charging charger 3 is easily removed by the cleaning blade 22 and the brush roller 17.

When the preparatory operation (idling) of the photosensitive member 1 is completed, the electromagnetic solenoid 28 is turned on (S4), and the lubricant 1
8 is located at the supply position where it contacts the brush roller 17. Thereafter, the image forming operation is started. The predetermined time is determined by experiment. A predetermined time may be arbitrarily set by an operation unit (not shown) according to a change in conditions or the like.

Next, based on FIG.
Modifications will be described. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted unless particularly necessary (the same applies to other embodiments described below). In the present embodiment, the friction reducing means 33 includes the cleaning means 25.
The arm 34 includes an arm 34 provided swingably around a shaft 36 and a bar-shaped lubricant 38 fixed to one end of the arm 34. Lubricant 38
Is formed of the same material as the lubricant 18. When the apparatus power is turned on or when a predetermined time has elapsed after one image forming operation is completed, as shown in FIG. 10B, the electromagnetic solenoid 28 is turned off and a position where the lubricant 38 is not supplied is provided. It is positioned in.

Next, another modification of the friction reducing means 32 will be described with reference to FIGS. The friction reducing means 47 in the present embodiment includes an arm 43 provided swingably around a shaft 42, a base 40 having a U-shaped cross section pressed by one end of the arm 43, and an inside of the base 40. A lubricating material 51 fixed via a spring 41 and an arm 43
Eccentric cam 45 provided on the other end side of the eccentric cam 45
, And a spring 44 for constantly urging the other end of the arm 43 toward the eccentric cam 45 side. As shown in FIG. 12, the lubricant 51 has a bar-shaped lubricant main body 51a and a base plate 51b. FIG.
Shows a state in which the lubricant 51 is not supplied. When the eccentric cam 45 rotates and presses the other end of the arm 43 upward, the lubricant 51 is pressed against the surface of the photoconductor 1 and the lubricant 5
One supply is made. The arm 43, the eccentric cam 45, the motor 46, the spring 44 and the like constitute a contact / separation mechanism.
As shown in FIG. 13, a configuration may be adopted in which a sheet-like lubricant 54 is attached to the base member 52 via an elastic member 56 and the base member 52 is displaced.

[0034]

According to the first aspect of the present invention, when the power of the apparatus is turned on, the preliminary operation of the image carrier is performed in a state where the friction coefficient of the surface of the image carrier is temporarily increased. As a result, ion products generated while the image carrier is left for a long time without image formation can be removed in the preliminary operation of the image carrier, without increasing the time of the image forming operation and reducing ozone. Image flow can be suppressed without adding a stagnation prevention configuration or the like.

According to the second aspect of the present invention, when a predetermined time has elapsed after the completion of one image forming operation, the image carrier is kept in a state where the friction coefficient of the surface of the image carrier is temporarily increased. Since the operation is performed, ion products generated while the image carrier is left for a long time without forming an image can be removed in the preliminary operation of the image carrier, thereby increasing the time of the image forming operation. It is possible to suppress image deletion without adding an ozone retention prevention configuration or the like.

According to the third aspect of the present invention, the means for reducing friction has a structure for supplying a lubricant to the surface of the image carrier.
In addition, since the lubricant can be selectively not supplied, and the friction coefficient is temporarily increased by not supplying the lubricant, the lubricant is left for a long time without image formation. The ion products generated during the operation can be removed in the preliminary operation of the image carrier, and the image flow is suppressed without increasing the time of the image forming operation and without adding a configuration for preventing ozone retention. be able to.

According to the fourth aspect of the present invention, the friction reducing means has a solid lubricant and a contact / separation mechanism for selectively positioning the lubricant at a position where the lubricant is supplied and a position where the lubricant is not supplied. As a result, ion products generated while the image carrier is left for a long time without image formation can be removed in the preliminary operation of the image carrier, without increasing the time of the image forming operation and reducing ozone. Image flow can be suppressed without adding a stagnation prevention configuration or the like.

According to the fifth aspect of the invention, since the lubricant is made of polytetrafluoroethylene, the friction coefficient of the surface of the image carrier can be made appropriate, and the life of the image carrier can be extended. it can.

According to the sixth aspect of the present invention, when the power supply of the apparatus is turned on, the image bearing member whose surface friction coefficient is reduced is kept in a state where the friction coefficient is temporarily increased. The preliminary operation is performed, and then the image forming operation is started, so that the ion products generated while the image carrier is left for a long time without image formation can be removed in the preliminary operation of the image carrier. The image deletion can be suppressed without increasing the time of the image forming operation and without adding a configuration for preventing ozone from staying.

According to the present invention, when a predetermined time elapses after one image forming operation is completed, the friction coefficient of the image carrier whose surface friction coefficient is reduced is temporarily reduced. Since the preliminary operation of the image carrier is performed in the raised state, and then the image forming operation is started, the ion products generated while the image carrier is left for a long time without image formation are subjected to the preliminary operation of the image carrier. The flow of images can be suppressed without increasing the time of the image forming operation and without adding a configuration for preventing ozone from staying.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a copying machine as an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a photoconductor surface friction coefficient and a photoconductor wear amount.

FIG. 3 is a schematic front view showing a configuration for measuring a friction coefficient of a photoconductor.

FIG. 4 is a diagram showing a molecular structure of polytetrafluoroethylene.

FIG. 5 is a main part front view showing a state where the lubricant is not supplied.

FIG. 6 is a flowchart showing a control operation relating to removal of ion products.

FIG. 7 is a graph showing a relationship between a pressing force and a wear amount of a photoconductor in the case of a cleaning brush.

FIG. 8 is a diagram showing a configuration for measuring a pressing force in the case of a cleaning brush.

FIG. 9 is a flowchart showing a control operation relating to removal of ion products according to another embodiment.

FIGS. 10A and 10B are diagrams showing a modification of the low friction means, in which FIG. 10A shows a state in which lubricant is supplied, and FIG. 10B shows a state in which lubricant is not supplied.

FIG. 11 is a view showing a modification of the friction reducing means.

FIG. 12 is a perspective view of a lubricant in the low friction means shown in FIG. 11;

FIG. 13 is a view showing a modified example of the low friction means.

FIG. 14 is a diagram showing a conventional lubricant application configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor as image carrier 18 Lubricant 25 Cleaning means 32 Low friction means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA38 EA09 ED02 ED27 EF02 EG07 2H034 AA06 AA07 BD00 BF00 4H104 CD02A PA50 RA01

Claims (7)

[Claims] An image forming apparatus comprising: a cleaning unit for cleaning a surface of an image carrier; and a friction reducing unit for reducing a friction coefficient of the surface of the image carrier. An image forming apparatus, wherein a preliminary operation of the image carrier is performed in a state where the friction coefficient of the surface of the image carrier is temporarily increased. 2. An image forming apparatus comprising: a cleaning unit for cleaning the surface of an image carrier; and a friction reducing unit for reducing a friction coefficient of the surface of the image carrier. An image forming apparatus, wherein after a lapse of time, a preliminary operation of the image carrier is performed in a state where the friction coefficient of the surface of the image carrier is temporarily increased. 3. An image forming apparatus according to claim 1, wherein said low friction means supplies a lubricant to the surface of said image bearing member, and selectively supplies the lubricant. The image forming apparatus is characterized in that the friction coefficient can be temporarily increased by not supplying a lubricant. 4. The image forming apparatus according to claim 3, wherein said friction reducing means has a solid lubricant and a contact / separation mechanism for selectively positioning the lubricant at a position where the lubricant is supplied and a position where the lubricant is not supplied. An image forming apparatus comprising: 5. The image forming apparatus according to claim 1, wherein said lubricant is polytetrafluoroethylene. 6. When the power of the apparatus is turned on, a preliminary operation of the image carrier is performed in a state where the friction coefficient of the image carrier whose surface friction coefficient is reduced is temporarily increased. An image forming method, wherein a forming operation is started. 7. When a predetermined time elapses after one image forming operation is completed, the image carrier in which the friction coefficient of the surface is reduced while the friction coefficient is temporarily increased is reduced. Performing the preliminary operation of (1), and then starting the image forming operation.