JP2006227265A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely reduce a load variation due to a decrease in the coefficient of the surface friction of an image carrier. <P>SOLUTION: The image forming apparatus includes a photoreceptor drum 1, a cleaning blade for removing developer in contact with the surface of the photoreceptor drum 1. In the image forming apparatus, the coefficient of the friction of the cleaning blade against the photoreceptor drum 1 is set to 2.0 or below. The photoreceptor drum 1 is stopped in such a manner that the photoreceptor drum 1 is once stopped, then intermittently rotated one or more times in the same direction as rotated during image formation, and then stopped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image by an electrophotographic method or an electrostatic recording method, and more particularly, to a latent image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric, or an intermediate The present invention relates to an image forming apparatus of a type that removes developer on an image carrier by bringing an elastic or flexible cleaning member such as a cleaning blade into contact with the image carrier such as a transfer member.

  In a transfer type electrophotographic image forming apparatus, a toner image as a developer image formed and supported on the surface of an image carrier such as a photoreceptor or an intermediate transfer member as a latent image carrier is transferred to a transfer material as a recording medium. There is known a cleaning device that removes (cleans) the transfer residual toner on the image carrier after the above.

  In general, a blade cleaning method is widely used. In this method, a cleaning blade having flexibility (rubber elasticity) as a cleaning member is brought into contact with the image carrier in a predetermined pressure contact state, and the image carrier surface is wiped to remove residual toner from the image carrier. It is scraped off and removed. In order to improve the cleaning efficiency, the cleaning blade is generally in contact with the counter in the rotational direction when the image carrier is formed with respect to the image carrier.

  In the image forming apparatus using the blade cleaning method as described above, the blade sometimes turns up due to friction with the image carrier. Therefore, in order to prevent the blade from turning up, a technique for subjecting the surface of the blade to a low friction treatment has been proposed. For example, Patent Document 1 discloses a structure having a low friction structure by increasing the hardness of the blade surface of polyurethane and decreasing the sticking force with the image carrier.

  On the other hand, in the image forming apparatus using the blade cleaning method, the image carrier corresponding to the cleaning blade contact area (nip area) of the image carrier when the image forming apparatus is stopped (when the image carrier rotation is stopped). The slipperiness (friction coefficient μ) of the body surface area changes to a different state compared to other areas, which causes streaks and image blurring (density fluctuation, etc.) on the image during the next image formation. There are things to do.

  The above slip change phenomenon is caused by agglomeration of a residue (developer) such as fine toner having a small particle size or an external additive remaining in the cleaning blade contact area with the pressure contact force of the cleaning blade against the image carrier surface. This occurs because the slipperiness changes only in that portion on the image carrier due to the change in the size. In general, the friction coefficient μ in the region where the sliding property has changed fluctuates lower than the friction coefficient μ in the other regions.

  Therefore, when the image forming apparatus is driven again to rotate the image carrier, and the region where the coefficient of friction is lowered contacts the cleaning blade, the frictional force between the image carrier and the cleaning blade changes, and the image carrier is instantaneously The rotation speed of the body changes faster. At that time, streaks of the image carrier rotation period and image blurring (density fluctuation, etc.) occur in the portion where the image was formed on the image carrier and the portion where the image was transferred to the transfer material.

More specifically, the friction coefficient of the region once reduced in friction coefficient is assimilated to the friction coefficient of other regions by repeated rubbing with the cleaning blade during the rotation of the image carrier. However, even if the image carrier rotates 4 to 5 times during the “pre-rotation process” period, it still does not assimilate to the friction coefficient of other areas, and image blurring occurs from the start of printing to about the third to fourth sheets. It ends up.

  FIG. 8 is an enlarged schematic view of the edge portion of the cleaning blade for explaining this conventional example. Reference numeral 1 denotes a photosensitive drum as an image carrier, 6a denotes a rubber cleaning blade, and W1 denotes a width of a contact area between the cleaning blade 6a and the photosensitive drum 1. FIG. 8A shows a contact state during image formation, and the photosensitive drum 1 is driven to rotate in the direction of arrow a. The cleaning blade 6a has its tip end abutted against the counter drum 1 with a predetermined pressing force in the positive rotation direction when the photosensitive drum 1 forms an image. For this reason, the edge portion of the cleaning blade 6 a is dragged by the photosensitive drum 1, so that distortion occurs and the edge is in close contact with the photosensitive drum 1. The surface of the photosensitive drum 1 is wiped by the edge portion of the cleaning blade 6a that is in contact with the surface, and the transfer residual toner is scraped off from the photosensitive drum 1.

  In front of the edge portion of the cleaning blade 6a, the toner t is accumulated by being dammed by the blade 6a. If the photosensitive drum 1 is kept in a rotation stopped state with the toner t remaining in the state, the toner t aggregates and is fixed to the photosensitive drum 1, and the next positive rotation of the photosensitive drum 1 is performed. When starting up, the edge of the cleaning blade 6a may slip through. The slipping-aggregated toner adhering portion becomes a slipperiness changing portion.

  The occurrence of streaks and image blur due to the change in slipperiness caused by leaving the cleaning blade in contact with the image forming apparatus in the stopped state as described above is particularly suitable as a multicolor image forming method suitable for high speed. A so-called tandem type image forming apparatus in which a plurality of, for example, four image carriers are arranged side by side, adopting a “one motor system” in which four image carriers are driven by one motor as a driving method of the four image carriers. May occur remarkably in the image forming apparatus.

  That is, since the portions where the friction coefficient μ of all image carriers having the same drive system are reduced appear in the same cycle, the drive load fluctuates when the cleaning blade passes at the same timing. Therefore, the magnitude of the load fluctuation of the entire drive system is amplified according to the number of image carriers belonging to the same drive system. At this time, the latent image on the image carrier drawn by the exposure apparatus is blurred and appears on the image as a streak of the image carrier pitch. Due to such a principle, it occurs remarkably in a halftone pattern.

  In order to avoid this fundamentally, it is most reliable to retract the cleaning blade from the surface of the image carrier when the image forming apparatus is stopped, but the retracting mechanism is expensive. In addition, it is difficult to ensure the accuracy of the contact state, leading to poor cleaning, and consequently the quality of the image is deteriorated. Further, when the cleaning blade is brought into contact again, it is necessary to make contact with the image carrier area that has been cleaned before retraction in order not to form an uncleaned area.

In addition, when a means for finely moving the contact position at regular time intervals is used, it is necessary to always supply power to the control device for periodic control, and also drive power for fine movement drive. Required regularly. As a result, power consumption during standby time increases.
JP 2003-015492 A

  An object of the present invention is to reliably reduce load fluctuations due to a decrease in the surface friction coefficient of an image carrier.

In order to achieve the above object, the present invention adopts the following configuration. That is,
An image carrier;
A cleaning blade that contacts the image carrier and removes the developer;
In an image forming apparatus having
The cleaning blade is provided with a coefficient of friction of 2.0 or less with the image carrier,
In the case of stopping the image carrier, the image carrier is stopped after the image carrier is temporarily stopped and then moved several times intermittently in the same direction as the image formation. Device.

  According to the present invention, load fluctuation due to a partial reduction in the surface friction coefficient of the image carrier can be reduced at a low cost, and a good image is always output without causing streak-like image defects due to blurring during exposure. be able to.

(First embodiment)
(1) Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the first embodiment of the present invention. The image forming apparatus according to the present embodiment is a tandem type in which a plurality of image bearing members (latent image bearing members) photosensitive drums are arranged one above the other, and is an electrophotographic color (multicolor image) printer using an intermediate transfer belt. is there.

  Y, M, C, and Bk are first to fourth image forming units (image forming units) that form toner images of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively. Unit), which are arranged in the image forming apparatus main body in parallel from the bottom to the top. The image forming unit includes process cartridges (hereinafter referred to as cartridges) PC, PY, PM, and PB that are detachable and replaceable with respect to the image forming apparatus main body 1. Each of the cartridges PC, PY, PM, and PB has four process units: a photosensitive drum 1, a charging roller 2, a developing device 4, and a blade cleaning device 6.

  The image forming portions Y, M, C, and Bk have the same electrophotographic process mechanism except that they have different color developers. That is, each of the first to fourth image forming units includes a drum-type electrophotographic photosensitive member (photosensitive drum) 1 as a first image carrier, a charging roller 2 as a primary charging unit, and an LED array device. It comprises a laser irradiation device 3 as exposure means, a development device 4 as development means, a primary transfer roller 5 as primary transfer means, a blade cleaning device 6 as cleaning means, and the like. The developers contained in the developing devices 4 of the first to fourth image forming units are yellow toner, magenta toner, cyan toner, and black toner, respectively. As the toner of each color, a spherical toner having an average particle diameter of 6 μm was used. The external additive is silica.

  Reference numeral 30 denotes an endless belt-shaped intermediate transfer belt as a second image carrier, and the whole of the four image forming units on the photosensitive drum 1 side (the front side of the printer) of the cartridges PC, PY, PM, and PB. In such a manner, it is stretched between a plurality of support rollers (not shown) so as to be long in the vertical direction. In each of the first to fourth image forming units, the primary transfer roller 5 is brought into pressure contact with the photosensitive drum 1 via the intermediate transfer belt 30. A contact portion between each photosensitive drum 1 and the intermediate transfer belt 30 is a primary transfer portion.

In the image forming apparatus according to the present embodiment, the driving method of the photosensitive drums 1 of the cartridges PY, PM, PC, and PBk is “1 motor” in which four photosensitive drums 1 are driven by one motor 11 as shown in FIG. "Method". The “1-motor system” has a relatively small number of motors, which are relatively expensive driving sources, compared to other systems, and the control system when there are multiple motors (rotational speed detection mechanism of each motor and its control mechanism) is also 1 Therefore, it is generally advantageous in terms of cost. That is, in the image forming apparatus of the present embodiment, one drive motor 11 is used as a drive source, and the drive force of the motor 11 is transmitted to the drum gears GY, GM, GC, GBk of each photosensitive drum 1 via the gear train 12. Thus, the four photosensitive drums 1 are driven to rotate at the same cycle.

  A CPU (computer) 80 controls the sequence of image forming operations of the entire image forming apparatus. The drive motor 11 is also controlled by the CPU 80 in forward rotation drive control, reverse rotation drive control, and stop control. When the drive motor 11 is controlled to be driven forward, the four photosensitive drums 1 are driven to rotate in the counterclockwise direction indicated by the arrow a in FIGS. When the drive motor 11 is reversely driven, the four photosensitive drums 1 are in the reverse rotation drive state opposite to the arrow a. When the drive motor 11 is controlled to stop, the four photosensitive drums 1 are stopped.

  When the CPU 80 receives an image formation trigger (print job start signal), it sends a signal to the driver of the drive motor 11 so as to drive it in the forward rotation. As a result, the drive motor 11 is controlled to rotate forward, and the photosensitive drum 1 of each of the first to fourth image forming units rotates in the counterclockwise direction indicated by the arrow a in FIGS. 1 and 2, for example, at a circumference of 100 mm / sec. It becomes a forward rotation drive state at the speed.

  Further, the CPU 80 activates a drive mechanism (not shown) of the intermediate transfer belt 30 and rotates at a substantially same speed as the photosensitive drum 1 in the clockwise direction of the forward arrow c with respect to the positive rotation direction a of each photosensitive drum 1. Driven.

  In each of the first to fourth image forming units Y, M, C, and Bk, each photosensitive drum 1 that is driven to rotate forward is charged by a charging roller 2 to which a charging bias is applied from a power circuit (not shown) during the rotation process. Thus, primary charging is uniformly performed to a predetermined polarity and potential. Then, light image exposure LY, LM, LC, and LBk according to image patterns of yellow, magenta, cyan, and black, which are color separation component images of full-color images, are respectively applied to the charged surface by the laser irradiation device 3. Thus, an electrostatic latent image of image information is formed on each photosensitive drum 1. The electrostatic latent image is developed as a toner image by the developing device 4, so that a color separation component image of a full color image is formed on the surface of each photosensitive drum 1 of the cartridges PY, PM, PC, and PBk by an electrophotographic process. A certain yellow, magenta, cyan, and black color toner image is formed at a predetermined sequence control timing.

  In the cartridges PY, PM, PC, and PBk, yellow, magenta, cyan, and black color toner images formed on the surfaces of the photosensitive drums 1 are forward arrows in the forward rotation direction of the photosensitive drums 1. In the primary transfer portions of the first to fourth image forming portions Y, M, C, and Bk with respect to the surface of the intermediate transfer belt 30 that is driven to rotate at the same speed as the photosensitive drum 1 in the clockwise direction. The transfer roller is sequentially superimposed and transferred by a primary transfer bias applied from a power supply circuit (not shown). As a result, an unfixed full-color toner image (mirror image) is synthesized and formed on the surface of the intermediate transfer belt 30 that is rotationally driven.

  In each of the first to fourth image forming units Y, M, C, and Bk, the transfer residual toner remaining on each photosensitive drum 1 after the primary transfer of the toner image to the intermediate transfer belt 30 is the cleaning blade of the blade cleaning device 6. It is removed by 6a (FIG. 4) and stored in the storage unit 6b in the device 6.

32 is a secondary transfer roller, and 32a is a counter roller. The counter roller 32 a is disposed inside the intermediate transfer belt 30 on the lower end side of the intermediate transfer belt 30. The secondary transfer roller 32 sandwiches the intermediate transfer belt 30 between the counter roller 32a and the intermediate transfer belt 3.
It is disposed in contact with the outer surface of 0. A contact portion between the secondary transfer roller 32 and the intermediate transfer belt 30 is a secondary transfer portion.

  Reference numeral 40 denotes a feeding cassette disposed in the lower part of the image forming apparatus main body. A transfer material P as a recording medium is loaded and accommodated. The CPU 80 drives the conveying means (pickup roller) 31 at a predetermined sequence control timing to separate and feed one transfer material P in the feeding cassette 40, and feeds it to the secondary transfer unit at a predetermined timing. . The unfixed full-color toner image synthesized and formed on the intermediate transfer belt 30 is collectively applied to the surface of the transfer material P by the secondary transfer bias applied from the power supply circuit (not shown) to the secondary transfer roller 32 in the secondary transfer portion. It will be transcribed.

  The transfer material P that has passed through the secondary transfer portion is separated from the surface of the intermediate transfer belt 30 and sent to the fixing device 7 by the transport belt 35.

  The transfer residual toner remaining on the intermediate transfer belt 30 is removed by the cleaning blade of the blade cleaning device 33 and sent to the waste toner box 34 to be stored.

  The unfixed full-color toner image on the transfer material P sent to the fixing device 7 is melted and fixed to the transfer material P by applying heat and pressure by the fixing device 7, passes through the sheet path 41, and the upper surface of the image forming apparatus main body. Is discharged as a color image formed product onto a discharge tray 36 disposed in

(2) Operation Process of Image Forming Apparatus FIG. 3 shows the operation process of the image forming apparatus.

1) Pre-multi-rotation process This is a start (start) operation period (warming period) of the image forming apparatus. When the main power switch of the image forming apparatus is turned on, the image forming apparatus is activated to execute a preparation operation for a required process device.

2) Standby
After the predetermined start-up operation period, the image forming apparatus stops driving and the image forming apparatus is held in a standby state until an image forming trigger (print job start signal) is input.

3) Pre-rotation process This is a period in which the image forming apparatus is re-driven based on the input of the image forming trigger and the pre-print job operation of the required process equipment is executed.

  More practically, (a) the image forming apparatus receives the image forming trigger, (b) the image is developed by the formatter (the developing time varies depending on the data amount of the image and the processing speed of the formatter), and (c) the pre-rotation step The order is start.

  If an image forming trigger is input during the previous multi-rotation process of 1), the process proceeds to the pre-rotation process without waiting for 2) after the completion of the pre-multi-rotation process.

4) Execution of print job When a predetermined pre-rotation process is completed, an image forming process is subsequently executed, and an image-formed transfer material is output.

  In the case of a continuous print job, the image forming process is repeated, and a predetermined number of image-formed transfer materials are sequentially output.

5) Inter-sheet process This is an interval process between the trailing edge of one transfer material P and the leading edge of the next transfer material P in the case of a continuous print job.

6) Post-rotation process After printing the image-formed transfer material in the case of a single print job (end of print job), or in the case of a continuous print job, the last image-formed transfer of the continuous print job After the material is output (end of print job), the image forming apparatus is continuously driven to execute a post-print job operation of a required process device.

7) Standby After the completion of the predetermined post-rotation process, the drive of the image forming apparatus is stopped, and the image forming apparatus is held in a standby state until the next image forming trigger is input.

  From the pre-rotation process to the post-rotation process is one image forming process A, and the next image forming process B is executed by inputting the next image forming trigger.

(3) Measures to reduce load fluctuation caused by leaving the cleaning blade in contact with the cleaning blade FIG. 4 is an enlarged model view of the blade cleaning device 6 with respect to the photosensitive drum 1. As a cleaning blade (hereinafter referred to as a blade) 6a, a conventional product uses urethane rubber having a Wallace hardness of 70 degrees. Reference numeral 6c denotes a support portion of the blade 6a. The tip edge portion of the blade 6a is brought into contact with the photoconductor drum 1 with a predetermined pressing force with respect to the counter in the positive rotation direction a when the photoconductor drum 1 forms an image. The cleaning device 6 is firmly fixed and supported on the housing. In the conventional product, the contact pressure between the blade 6a and the photosensitive drum 1 was 70 g / cm. Note that the spherical toner having an average particle diameter of 6 μm according to the present embodiment is harder to clean than the irregular toner, so that the contact pressure is required to be 50 g / cm or more, and preferably 70 to 120 g / cm.

  On the other hand, in the embodiment of the present invention, the surface hardening cleaning blade 6e is used as the low friction processed product. FIG. 5 is an enlarged model view of the blade cleaning device 6 equipped with the surface hardening cleaning blade 6e. This blade is described in Patent Document 1, and the manufacturing method is shown in FIG.

  The blade 6a is a polyurethane elastic body and has a Wallace hardness of 70 degrees. Further, the surface hardening cleaning blade 6e is provided with a hardened layer on the surface of the surface hardening cleaning blade 6e and the contact portion with the photosensitive drum 1. The cured layer is formed by impregnating at least an isocyanate compound for a predetermined time without impregnating with an active hydrogen compound, and then reacting the isocyanate compound with a polyurethane resin. An example method is described below.

  First, as a method of forming the cleaning blade before forming the hardened layer, (a) polymer polyol, polyisocyanate, cross-linking agent, catalyst and the like are mixed at a time and injected into a mold or a centrifugally-molded cylindrical mold. (B) Pre-react polymer polyol and polyisocyanate to make a prepolymer, then mix a cross-linking agent, catalyst, etc., and inject this into a mold or centrifugal mold (C) A semi-prepolymer obtained by reacting a polymer polyol with polyisocyanate and a curing agent obtained by adding a polymer polyol to a crosslinking agent are reacted with each other, and this is used as a mold or a centrifugal molded cylinder. For example, a semi-one shot method in which molding is performed by pouring into a mold.

  The hardness of the cleaning blade formed in this way before forming the cured layer is preferably 62 ° or more and 85 ° or less (IRHD). Thereby, it is possible to ensure good adhesion and followability to the rotating photosensitive drum 1, and to prevent the surface of the photosensitive drum 1 from being damaged.

  Next, as an example of a method for forming a hardened layer, the tip of the blade 6a is placed in the tank 20 only at the contact portion of the cleaning blade with the photosensitive drum 1, for example, as shown in the upper diagram of FIG. Is impregnated with the isocyanate compound 21 stored in The predetermined time for impregnating the isocyanate compound is, for example, 10 minutes or more and 80 minutes or less. The liquid isocyanate compound at this time is preferably conditioned at 30 ° C. or higher and 90 ° C. or lower. Thereafter, the isocyanate compound remaining on the surface of the cleaning blade is wiped off, and the reaction between the impregnated isocyanate compound and the polyurethane resin is allowed to proceed for 10 minutes to 80 minutes under conditions of 50 ° C. or more and 140 ° C. or less. Can be mentioned. Then, a hardened layer 6f is formed on the surface as shown in the lower diagram of FIG.

  As thickness of a hardened layer, 0.12 mm or more and 1.2 mm or less are preferable. If the thickness is thin, the hardness is low and the friction coefficient remains large. If the thickness is thick, the hardness is high, and good adhesion and followability to the rotating photosensitive drum 1 cannot be ensured, so that The surface of the body drum 1 may be damaged, and the hardness of the hardened layer is preferably 75 ° or more and 100 ° or less (IRHD).

  Further, it is preferable that the region where the hardened layer is formed is only a limited range of the contact portion with the photosensitive drum 1 and the vicinity thereof, that is, the tip of the cleaning blade. When formed over a wide range, the rigidity of the entire cleaning blade becomes high, and good adhesion and followability to the rotating photosensitive drum 1 cannot be ensured, and good cleaning performance cannot be obtained.

  By adjusting the degree of curing of the surface described above, for example, by varying the production conditions such as the impregnation time, the friction coefficients were set to (2) 2.3, (3) 1.8, and (4) 0.7. Three cleaning blades were created. The friction coefficient was measured by cutting the cleaning blade to a width of 50 mm in the longitudinal direction and bringing the tip into contact with the polyethylene phthalate film in the so-called counter direction, pressurizing 0.3 N / cm, moving speed 100 mm / min. The surface property tester (manufactured by Haydon Co., Ltd.) was used under the above conditions. In addition, the conventional blade 6a which does not have a hardened layer in the front-end | tip part was made to contact | abut in the counter direction. Then, the contact part turned over and the friction coefficient (1) was not measurable.

  For example, in order to maintain the optimum contact pressure with the photosensitive drum 1 with respect to the cleaning blade having a friction coefficient (4) of 0.7, the amount of penetration into the photosensitive drum 1 is 1 in order to maintain the optimum pressure of 70 g / cm. Adjusted by reducing 0.6 mm from 2 mm. In addition to the increase in hardness, the nip width W1 of the conventional blade 6a shown in FIG. 8 was 0.5 mm as the penetration amount decreased, but the nip width W2 of the surface hardening cleaning blade 6e shown in FIG. Diminished. In addition, when fixing the support part 6c of the cleaning blade to the casing of the cleaning device 6, the amount of intrusion was reduced by sliding the fixing seating surface upward.

  Reference numeral 6d denotes a seal sheet (squeeze sheet) that functions as a seal to prevent the toner scraped off from blowing out. The sheet 6d is cleaned by bringing the leading end thereof into contact with the photosensitive drum 1 in the forward direction of the photosensitive drum 1 in the forward direction a on the upstream side of the rotational direction a of the photosensitive drum 1 relative to the blades 6a and 6e. It is attached to the front end of the housing of the device 6 with double-sided tape or the like. This squeeze sheet 6d is a flexible sheet, for example, a polyethylene terephthalate film having a thickness of 30 μm to 100 μm.

  The transfer residual toner that adheres to the surface of the photosensitive drum 1 from the primary transfer portion and is conveyed by the positive rotation of the photosensitive drum 1 passes through the squeeze sheet 6d, is removed from the surface of the photosensitive drum 1 by the blade 6a, and is stored in the storage portion. It is stored in 6b. In the housing of the cleaning device 6, a conveying member (not shown) that conveys waste toner removed from the surface of the photosensitive drum 1 by the blade 6 a to the back of the storage unit 6 b is disposed.

  Hereinafter, various controls of the rotation of the photosensitive drum 1 including the conventional comparative example and the state of the streak image will be described.

1) Comparative Example 1
Conventional cleaning blade 6a <forward rotation a → stopped>
FIG. 7 shows the evaluation result of the streak image resulting from leaving the cleaning blade in contact with the photosensitive drum 1 when the stop time of the photosensitive drum 1 after printing with the positive rotation a of the photosensitive drum 1 is changed. The evaluated image is the first halftone image after being stopped for 1 second to 6 minutes. The streak of exposure blur due to the blade contact part slipping through the agglomerated toner portion caused by leaving the cleaning blade in contact was judged as follows.

  There is no ◎. ○ is close and there are slight streaks. △ shows streaks. X shows streaks clearly.

  The horizontal axis indicates the stop time of the photosensitive drum 1, and the vertical axis indicates the quality of the stripe. From this graph, it can be seen that streaks occur when stopped for 2 to 3 minutes or longer. Fine powder toner and external additives are agglomerated at the position on the photosensitive drum 1 where the streaks are generated. From this result, it can be seen that the agglomeration is more agglomerated when the stop time is longer.

  FIG. 8 is a schematic diagram showing a state in which the contact portion between the blade 6a and the photosensitive drum 1 is observed with respect to the control of <normal rotation a → stop leaving> of the photosensitive drum 1. FIG. Although briefly described above as a conventional example, a more detailed description will be given here for comparison with the examples.

  FIG. 8A shows that the photosensitive drum 1 is rotating forward a during printing, and there is distortion at the tip of the blade 6a. This distortion occurs when the leading edge portion of the blade 6 a is in contact with the photosensitive drum 1 in the counter direction with respect to the positive rotation direction of the photosensitive drum 1, and the leading edge portion is dragged by the photosensitive drum 1. The friction coefficient of the blade 6a was not measurable by the method described above. At this time, the contact area width (nip width) W1 including the pulverized toner and external additives was 0.5 mm. The fine toner and the external additive t removed from the photosensitive drum 1 are also moved in the normal rotation direction of the photosensitive drum 1 and easily enter the gap between the distorted edge portion and the photosensitive drum 1. Further, since the fine toner and the external additive t tend to adhere to the blade 6a, they gradually accumulate in this gap during printing, and the amount of adhesion increases.

  FIG. 8B shows a state where printing is finished and the photosensitive drum 1 is stopped. During the stop, the fine toner and the external additive t accumulated between the blade 6a and the photosensitive drum 1 are pressurized while being left by the distorted blade 6a. In addition, the fine powder toner and the external additive t accumulated between the edge portion and the photosensitive drum 1 are aggregated due to a large amount of adhesion due to the pressurization during standing. Due to the pressurization due to the standing, the particles are gradually agglomerated while being pressed in the direction of the photosensitive drum 1, thereby being fixed to the photosensitive drum 1. From the result of FIG. 7, it can be seen that if the stop is performed for 1 minute or less, the blade 6a remains stationary, so that the aggregation does not deteriorate and the cleaning can be performed. It can also be seen that when left for 2 to 3 minutes, the adhering to the photosensitive drum 1 proceeds and the cleaning becomes difficult.

  FIG. 8C shows a state where fine toner and external additive t have passed through the blade 6a. The fine toner and the external additive t fixed to the photosensitive drum 1 make one round of the photosensitive drum 1 and return to the blade 6a again. At this time, the fine toner and the external additive t pass through the blade 6a, and the exposure is blurred due to the rotational load fluctuation of the photosensitive drum 1, so that a streak-like image defect occurs.

  According to Comparative Example 1, when the photosensitive drum 1 is stopped at the forward rotation a, the blade 6a may not be aggregated enough to pass through the blade 6a even if the blade 6a is stopped within one minute if the distortion of the blade 6a is maintained. all right.

2) Comparative Example 2
Surface-curing cleaning blade 6e <forward rotation a-> stop left>
FIG. 9 is a schematic diagram showing a state in which the contact portion between the surface hardening cleaning blade 6e and the photosensitive drum 1 is observed with respect to the control of <normal rotation a → stop leaving> of the photosensitive drum 1. FIG. Since the surface was cured, the friction with the photosensitive drum 1 was lowered and it was not dragged by the forward rotation a. The friction coefficient of the surface hardening cleaning blade 6e was (4) 0.7 in the above-described method. The surface-curing cleaning blade 6e was not distorted, and the nip width W2 including the fine powder toner and external additives was 0.2 mm. It is smaller than the nip width W1 (= 0.5 mm) of the conventional blade 6a. This decrease in nip is caused by a decrease in the friction coefficient, a decrease in the sandwiching width of the fine toner and the external additive, and an intrusion amount of 1.2 mm in order to keep the contact pressure at the above-mentioned appropriate value of 70 g / cm. It is because it dropped to 0.6mm.

  FIG. 9A shows that the photosensitive drum 1 is rotating forward a during printing, and there is almost no distortion at the tip of the cleaning blade 6e compared to the conventional blade 6a.

  That is, unlike the conventional blade 6a of Comparative Example 1, the edge portion of the tip is not dragged to the photosensitive drum 1, and the Comparative Example 2 has a smaller gap between the photosensitive drums 1 and fine powder toner or external additives. The amount of t entering is small. Moreover, the fine toner and the external additive t are less likely to adhere to the surface hardening cleaning blade 6e. Therefore, the fine toner and the external additive t do not further push the gap with the adhesion to the blade 6e as a foothold. That is, the amount of fine powder toner and external additive t collected in the gap at the nip portion can be reduced as compared with Comparative Example 1. However, a small amount of fine toner and external additive t still remained.

  FIG. 9B shows a state where printing is finished and the photosensitive drum 1 is stopped. During the stoppage, the fine powder toner and the external additive t collected between the blade 6e and the photosensitive drum 1 are pressurized by the blade 6e while being left, and gradually agglomerate. If it is left for 2 to 3 minutes, the fixation with the photosensitive drum 1 proceeds and it becomes difficult to clean.

  FIG. 9C shows a state where the fine powder toner and the external additive t have passed through the blade 6e. The fine toner and the external additive t fixed to the photosensitive drum 1 make one round of the photosensitive drum 1 and return to the cleaning blade 6e again. At this time, the fine toner and the external additive t pass through the cleaning blade 6e, and the exposure blurs due to fluctuations in the rotational load of the photosensitive drum 1, causing streak-like image defects.

  According to Comparative Example 2, the surface-curing cleaning blade 6e hardly adheres the fine powder toner and the external additive t. However, when the surface hardening cleaning blade 6e is stopped at the forward rotation a, the fine powder toner and the external additive t remain in a small amount. It was found that the agglomeration occurred during the suspension.

3) Comparative Example 3
Conventional cleaning blade 6a <3 fine movement positive rotation b-> stop left>
10 and FIG. 11 are schematic diagrams showing a state in which the contact portion between the conventional blade 6a and the photosensitive drum 1 is observed with respect to the control of <three fine movement positive rotation b → stop leaving> of the photosensitive drum 1. FIG. The fine movement positive rotation b is a control to perform a positive rotation that is equal to or greater than the nip width and immediately stop, and after repeating this three times, it was left to stand.

  FIG. 10A shows that the photosensitive drum 1 is rotating forward a during printing, and there is distortion at the tip of the blade 6a. This distortion occurs when the leading edge portion of the blade 6 a is in contact with the photosensitive drum 1 in the counter direction with respect to the positive rotation direction of the photosensitive drum 1, and the leading edge portion is dragged by the photosensitive drum 1. Due to this distortion, the nip width W1 was 0.5 mm, which was wider than that at rest without distortion. The fine toner and the external additive t removed from the photoconductive drum 1 are also moved in the normal rotation direction of the photoconductive drum 1 and easily enter the gap between the distorted blade edge portion and the photoconductive drum 1. Further, since the fine toner and the external additive t tend to adhere to the blade 6a, they gradually accumulate in this gap during printing, and the amount of adhesion increases.

  FIG. 10B shows a state when the photosensitive drum 1 is stopped after the forward rotation a. As described above, the aggregation of the fine toner and the external additive t does not affect the image within 1 minute after the forward rotation of the photosensitive drum 1 is stopped. The stop time here is 5 seconds, but the value is not limited to this value as long as it is within 1 minute.

  FIGS. 10 (c) to 11 (e) show a state in which the photosensitive drum 1 is intermittently positively rotated with a fine movement positive rotation b after stopping after 5 seconds.

  FIG. 10C shows the first intermittent forward rotation. The photosensitive drum 1 was rotated at 100 mm / sec for 10 ms. At this time, the moving distance of the photosensitive drum 1 was about 1 mm. The fine toner and the external additive t sandwiched between the edge of the conventional blade 6a and the photosensitive drum 1 within 5 seconds after the stop are aggregated so as not to affect the image, and the movement of the photosensitive drum 1 As a result, the conventional blade 6a was passed through. Note that the fine movement positive rotation b in which the positive rotation a is shortened is also within one minute after the stop, and the aggregation of the fine toner and the external additive t does not affect the image. t1 is the fine toner or external additive that has passed through. At this time, a part of the pulverized toner and the external additive that has passed through is agglomerated, and the pulverized toner and the external additive t that have not aggregated are still in the gap between the edge portion of the conventional blade 6a and the photosensitive drum 1. It remained. In particular, the conventional blade 6a tends to adhere fine powder toner and external additive t, and easily remains in this gap.

  The moving distance per rotation when the photosensitive drum 1 is intermittently rotated forward is at least equal to or greater than the contact area width W1 of the blade 6a with respect to the photosensitive drum 1. In this embodiment, since the contact area width (nip width) W1 of the blade 6a with respect to the photosensitive drum 1 is 0.5 mm and the moving distance of the photosensitive drum 1 is about 1 mm, the fine toner and the external additive t are applied. It was enough to extrude from the contact area.

  FIG. 10D shows the second intermittent forward rotation. 5 seconds after the end of the first intermittent positive rotation, the photosensitive drum 1 was rotated forward under the same conditions as the first time. At the end of the first intermittent forward rotation, a part of the fine toner and the external additive t remaining in the gap between the edge of the cleaning blade 6e and the photosensitive drum 1 without agglomeration affects the image as in the first time. Aggregated to a certain extent, and passed through the blade 6 a as the photosensitive drum 1 moved. t2 is the fine powder toner or external additive that has passed through. The fine powder toner and the external additive t in the gap between the blade 6a and the photosensitive drum 1 were reduced due to aggregation and slipping through, but the non-aggregated fine powder toner and external additive t still remained.

FIG. 11E shows the third intermittent forward rotation. 5 seconds after the end of the second intermittent positive rotation, the photosensitive drum 1 was rotated forward under the same conditions as the first and second. After the second forward rotation, the fine toner and the external additive t remaining in the gap between the edge portion of the blade 6a and the photosensitive drum 1 without agglomerating are aggregated to the extent that they do not affect the image. As the drum 1 moved, the blade 6a passed through. t3 is the fine powder toner or external additive that has passed through. After the third forward rotation, the amount of fine powder toner and external additive t in the gap between the blade 6a and the photosensitive drum 1 has decreased from one to three times each time, but the conventional blade 6a is fine powder toner. Since the external additive t tends to adhere, it could not be completely removed from this gap.

  FIG. 11 (f) shows a state where the photosensitive drum 1 is stopped and stopped after three fine movement positive rotations b. During the stop, the fine toner and the external additive t accumulated between the blade 6a and the photosensitive drum 1 are pressurized while being left by the distorted blade 6a. In addition, the fine toner and the external additive t accumulated between the edge portion and the photosensitive drum 1 are gradually agglomerated while being pressed in the direction of the photosensitive drum 1 due to the pressurization while being left. It was fixed to the photosensitive drum 1.

  FIG. 11G shows a state immediately after starting the next print after stopping for 5 minutes. The fine powder and the external additive t are completely aggregated and fixed to the photosensitive drum 1 during the stop, and pass through the blade 6a.

  The fine toner and the external additive t fixed to the photosensitive drum 1 make one round of the photosensitive drum 1 and return to the blade 6a again. At this time, the fine toner and the external additive t pass through the blade 6a, and the exposure is blurred due to the rotational load fluctuation of the photosensitive drum 1, so that a streak-like image defect occurs.

  According to the comparative example 3, even if the photosensitive drum 1 repeats a slight intermittent rotation, the conventional blade 6a cannot easily be completely removed from the gap because the fine toner and the external additive t are liable to adhere. It was found that the agglomeration occurred during the suspension.

4) Summary of Comparative Examples 1 to 3 [Comparative Example 1] Stop by rotating forward with a conventional cleaning blade 6a ・ Since fine toner and external additives are likely to adhere to the blade and remain in the gap, leave it alone. [Comparative Example 2] The surface hardening cleaning blade 6e stopped at the forward rotation a, and adhesion of fine toner and external additives to the blade decreased. However, pulverized toner and external additives remain in the minute gaps, and are pressed and agglomerated while being left. [Comparative Example 3] The finely rotating forward rotation b is rotated 3 times with the conventional blade 6a, and the pulverized toner remaining outside the gaps Reduced additive. However, the fine powder toner and the external additive are attached to the blade and cannot be removed, and are pressed and agglomerated while being left. Based on these, the embodiment of the present invention will be described.

5) Example 1
Surface-curing cleaning blade 6e <Three times of fine movement and positive rotation b-> Stop left>
FIG. 12 and FIG. 13 are schematic views showing a state in which the contact portion between the surface hardening cleaning blade 6e and the photosensitive drum 1 is observed with respect to the control when the photosensitive drum 1 is stopped in the present embodiment. Since the surface was cured, the friction with the photosensitive drum 1 was lowered and it was not dragged by the forward rotation a. The friction coefficient of the surface-curing cleaning blade 6e was (4) 0.7 as measured by the method described above. Therefore, there was no distortion in the surface hardening cleaning blade 6e, and the nip width W2 was 0.2 mm, which was the same as when stationary. Moreover, the nip width W1 of the conventional blade 6a is less than 0.5 mm. As described above, the decrease in the nip is due to the decrease in hardness, and the decrease in the penetration amount from 1.2 mm to 0.6 mm in order to maintain the contact pressure at the above-described appropriate value of 70 g / cm.

  12 (a) to 13 (f), the photoconductive drum 1 is obtained when the photoconductive drum 1 is stopped after the photoconductive drum 1 is intermittently positively rotated as the fine movement positive rotation b after the photoconductive drum 1 is stopped. It is the state of 1 above. In this example, the number of intermittent forward rotations was 3, the waiting time for each rotation was 5 seconds, the amount of rotation for one forward rotation was 1 mm on the drum, and the reverse rotation was 5 mm on the drum.

  FIG. 12A shows a state in which the photosensitive drum 1 is rotating forward a during printing, and there is almost no distortion at the tip of the surface hardening cleaning blade 6e compared to the conventional blade 6a. This is because the surface is cured as described above, so that the friction with the photosensitive drum 1 is reduced and is not dragged by the forward rotation a. There was no distortion, and the nip width W2 including pinching of the fine toner and the external additive t was 0.2 mm.

  Here, the fine toner and the external additive t removed from the photosensitive drum 1 similarly move in the normal rotation direction of the photosensitive drum 1 and enter the gap between the edge portion and the photosensitive drum 1. However, the edge portion at the tip is not dragged to the photosensitive drum 1 as in the conventional blades 6a of Comparative Examples 1 and 3, and the gap of the photosensitive drum 1 is smaller in this embodiment, so that fine toner or external The amount of additive t entering is small. In addition, since the fine powder toner and the external additive t do not easily adhere to the surface-curing cleaning blade 6e, the fine powder toner and the external additive t do not further widen the gap by using the adhesion to the blade as a foothold. That is, it was possible to reduce the amount of fine toner and the external additive t accumulated in the gap at the nip portion as compared with Comparative Examples 1 and 3. However, a small amount of fine toner and external additive t still remained. In order to remove this small amount of fine powder toner and external additive t, the following control is performed.

  FIG. 12B shows a state when the photosensitive drum 1 is stopped after the forward rotation a. As described above, the aggregation of the fine toner and the external additive t does not affect the image within 1 minute after the forward rotation of the photosensitive drum 1 is stopped. The stop time here is 5 seconds, but the value is not limited to this value as long as it is within 1 minute.

  12 (c) to 13 (e) show a state in which the photosensitive drum 1 is intermittently positively rotated with the fine movement positive rotation b after being stopped after 5 seconds.

  FIG. 12C shows the first intermittent forward rotation. The photosensitive drum 1 was rotated at 100 mm / sec for 10 ms. At this time, the moving distance of the photosensitive drum 1 was about 1 mm. The fine toner and the external additive t sandwiched between the edge of the cleaning blade 6e and the photosensitive drum 1 within 5 seconds after the stop are aggregated so as not to affect the image, and the photosensitive drum 1 is moved. Accordingly, the cleaning blade 6e was slipped through. In particular, since the fine toner and the external additive t hardly adhere to the surface-curing cleaning blade 6e, compared to the conventional blade 6a of Comparative Example 3, the blade 6e is easy to slip through. t1 is the fine powder toner or external additive that has passed through. At this time, a part of the pulverized toner and the external additive that has passed through is agglomerated, and the pulverized toner and the external additive t that are not aggregated still remain in the gap between the edge of the cleaning blade 6e and the photosensitive drum 1. It was.

  The moving distance (predetermined distance) per rotation when the photosensitive drum 1 is intermittently positively rotated is at least equal to or larger than the contact area width W2 of the cleaning blade 6e with respect to the photosensitive drum 1. In this embodiment, the contact area width (nip width) W of the cleaning blade 6e with respect to the photosensitive drum 1 is 0.2 mm, and the moving distance of the photosensitive drum 1 is about 1 mm. It was sufficient to push out from the contact area.

FIG. 12D shows the second intermittent forward rotation. 5 seconds after the end of the first intermittent positive rotation, the photosensitive drum 1 was rotated forward under the same conditions as the first time. At the end of the first intermittent forward rotation, a part of the fine toner and the external additive t remaining in the gap between the edge of the cleaning blade 6e and the photosensitive drum 1 without agglomeration affects the image as in the first time. Aggregated to a certain extent, and passed through the cleaning blade 6e as the photosensitive drum 1 moved. t2 is the fine powder toner or external additive that has passed through. Since the fine powder toner and the external additive are less likely to adhere to the surface-curing cleaning blade 6e, the fine blade toner and the external additive can pass through the cleaning blade 6e with the photosensitive drum 1 in both the fine rotation and forward rotation. In other words, the combination of the surface hardening cleaning blade 6e and the property of being difficult to adhere sufficiently exerts the effect of the intermittent operation of the fine and positive rotation. Further, the fine powder toner and the external additive t in the gap between the cleaning blade 6e and the photosensitive drum 1 are reduced due to aggregation and slipping through. However, although it was extremely small, unaggregated fine powder toner and external additive t still remained.

  FIG. 13E shows the third intermittent forward rotation. 5 seconds after the end of the second intermittent positive rotation, the photosensitive drum 1 was rotated forward under the same conditions as the first and second. After the second forward rotation is completed, the fine toner and the external additive t remaining in the gap between the edge of the cleaning blade 6e and the photosensitive drum 1 without agglomeration do not affect the image. Aggregated and passed through the cleaning blade 6 e as the photosensitive drum 1 moved. Since the fine powder toner and the external additive are less likely to adhere to the surface-curing cleaning blade 6e, the fine blade toner and the external additive can pass through the cleaning blade 6e with the photosensitive drum 1 in both the fine rotation and forward rotation. t3 is the fine powder toner or external additive that has passed through. After the third forward rotation, almost no fine toner or external additive t remained in the gap between the edge of the cleaning blade 6e and the photosensitive drum 1.

  In this embodiment, most of the fine toner and external additives in the gap between the cleaning blade 6e and the photosensitive drum 1 have passed through the cleaning blade 6e after three intermittent positive rotations, so the number of forward rotations was set to three. However, the number of times may be increased or decreased depending on the level of the streak image, and the number is not limited to this number.

  However, the fine toner and the external additive t that have passed through the cleaning blade 6e reach the contact position of the photosensitive drum of the charging roller 2 that is the contact charging means. Then, these may contaminate the charging roller 2 and cause image defects such as streaks and fogging due to charging defects. Therefore, it is desirable that the total amount of positive and negative photosensitive drum movement is smaller than the distance from the contact portion of the drum cleaning blade to the charging roller contact portion.

  In this embodiment, the distance from the contact portion of the cleaning blade 6e to the contact portion of the charging roller 2 with respect to the photosensitive drum 1 is 13 mm, and the total amount of photosensitive drum movement in intermittent positive rotation is about 3 mm (= 1 mm × 3 times). The fine powder toner and the external additive that have passed through the cleaning blade 6e do not contaminate the charging roller 2.

  In this embodiment, the rotation amount of the three intermittent positive rotations is 1 mm. However, the movement amount of each rotation is not necessarily the same, and different movement amounts may be used.

  FIG. 13 (f) shows a state where the photosensitive drum 1 is stopped and left after three fine movement positive rotations b. During the stop, the fine powder toner and the external additive t in the gap between the blade 6a and the photosensitive drum 1 are almost removed from the nip portion by three fine rotations, and the cleaning blade 6e is pressurized while being left. However, no aggregation of the fine powder toner and the external additive t was observed.

  FIG. 13G shows a state immediately after starting the next printing after stopping for 5 minutes. Aggregation of fine powder and external additive t is hardly observed on the photosensitive drum 1, and the fine powder and external additive t adhering to a very small amount do not pass through the cleaning blade 6 e, and the exposure is caused by blurring. There was no generation of images.

  12 and 13 depict a blade having a friction coefficient of (4) 0.7. In addition, cleaning blades having friction coefficients of (2) 2.3 and (3) 1.8 were prepared by changing manufacturing conditions such as the above-described surface hardening impregnation time.

  First, the blade with a friction coefficient of (3) 1.8 had a reduced friction with the photosensitive drum 1 and was not dragged by the forward rotation a. On the other hand, as the surface layer was not sufficiently cured, the blade having a friction coefficient of (2) 2.3 started to be dragged by the forward rotation a. When the control of Example 1 was performed, the fine toner and the external additive t were removed with the blade having a friction coefficient of (3) 1.8, and no streak image was generated due to exposure blurring. On the other hand, in the blade having a friction coefficient of (2) 2.3, the fine powder and the external additive t adhering to the blade cannot be completely removed while being sandwiched in the nip due to the distortion generated in the photosensitive drum 1, and the exposure is blurred. A streak image has been generated. The results are shown in Table 1.

  According to Table 1, good results were obtained by controlling fine rotation intermittent rotation using a cleaning blade having a friction coefficient of 2.0 or less. If the friction coefficient is 2.0 or less, the tackiness is weak, so that the fine powder and the external additive t are difficult to adhere to the blade surface. In addition, since the blade is less likely to be distorted during rotation, the gap in the nip is small, and fine powder and external additive t can be efficiently removed by fine rotation intermittent rotation.

  As described above, since the fine toner and the external additive t are less likely to adhere to the surface-curing cleaning blade 6e, the cleaning blade 6e can pass through the photosensitive drum 1 and the fine movement forward rotation due to the adhesion to the photosensitive drum 1. Then, by repeating this fine movement forward rotation intermittently, the fine toner and the external additive t can be effectively removed from the nip portion (between the blade and the photosensitive drum 1).

(Second Embodiment)
In the second embodiment, a coating layer is provided on the surface of the cleaning blade as a low friction treatment.

  The cleaning blade is an elastic blade mainly composed of urethane, and at least a portion of the blade surface in contact with the image bearing member, here, both surfaces of the blade 6a as shown in FIG. A nylon coating layer in which carbon fluoride having a particle size of 10 μm or less was dispersed was used. The cleaning blade 6h provided with the nylon coating layer 6g is fixed to the support portion 6c of the blade-attached sheet metal.

As a manufacturing method of this blade, first, the urethane rubber of the base material was blasted with a polishing machine, and an adhesive layer was formed thereon by a dipping method. The solution 22 for forming the adhesive layer was obtained by adding diisopropyl ether and N-β-γ-aminopropyltrimethoxysilane to a solution of alcohol-soluble nylon dissolved in methanol and stirring at room temperature for 30 minutes. Next, graphite fluoride (particle size of 10 μm or less, manufactured by Central Glass Co., Ltd.) is added to the solution in which nylon is dissolved on the adhesive layer, and the dispersed solution is applied again by dipping, and then at 80 ° C. for 5 minutes. It was made to dry and the nylon resin coating layer was formed. The method performed in this embodiment is a coating method using a dipping method, but the coating method is not particularly limited, and other methods include a screen printing method, a spray method, and a roll coating method.

6) Example 2
Coating cleaning blade 6h <3 fine forward rotation b-> left unattended>
When the photosensitive drum is stopped, the photosensitive drum is rotated forward and then reversely rotated. In addition, the coating cleaning blade 6h prepared in FIG. 14 was used. As in Example 1, three cleaning blades of (2) 2.3, (3) 1.8, and (4) 0.7 were prepared.

  There is almost no distortion at the tip of the coating cleaning blade 6h compared to the conventional blade 6a. This is because the surface is coated with a low friction layer, so that the friction with the photosensitive drum 1 is reduced and is not dragged by the forward rotation a.

  Using the coating cleaning blade 6h, the same control as in Example 1 (three fine movement positive rotation b → stopped standing) was performed, and the same effect as in Example 1 was obtained. In other words, the blades having the friction coefficients (3) 1.8 and (4) 0.7 had a reduced friction with the photosensitive drum 1 and were not dragged by the forward rotation a. On the other hand, assuming that the coating was insufficient, the blade having a friction coefficient of (2) 2.3 started to be dragged by the forward rotation a. When the control of Example 1 was performed, fine powder and external additive t were removed with the blades having friction coefficients (3) 1.8 and (4) 0.7, and streak images were generated due to exposure blurring. Was also not seen. On the other hand, in the blade having a friction coefficient of (2) 2.3, the fine powder and the external additive t adhering to the blade cannot be completely removed while being sandwiched in the nip due to the distortion generated in the photosensitive drum 1, and the exposure is blurred. A streak image has been generated.

  Since the fine powder toner and the external additive t are less likely to adhere to the coating cleaning blade 6h, the cleaning blade 6e can be slipped through the photosensitive drum 1 and the fine rotation forward by the adhesion to the photosensitive drum 1. Then, by repeating this fine movement forward rotation intermittently, the fine toner and the external additive t can be effectively removed from the nip portion. Since the pulverized toner and the external additive t are almost removed from the nip portion, the pulverized toner and the external additive t adhering to a very small amount without agglomerating on the photosensitive drum 1 are removed from the cleaning blade 6h. There is no slipping through. Therefore, in the next printing process, the coating cleaning blade 6h could not be passed through, and no streak due to exposure blurring occurred.

<Others>
1) The latent image carrier or intermediate transfer member as the image carrier can be a drum type or an endless belt type. The latent image carrier can also be an electrostatic recording dielectric. The image carrier can form and carry a toner image (developer image) by any image forming means.

  2) In the image forming apparatus according to the embodiment, as described above, spherical toner having an average particle diameter of 6 μm is used as the developer. The measurement method of the average particle diameter of the toner and the definition of the spherical toner in this embodiment will be described below.

(A) Measuring method of average particle size of toner As a measuring device, Coulter counter TA-2 type (manufactured by Coulter), an interface (manufactured by Nikkiki Co., Ltd.) for outputting number average distribution and volume average distribution, and CX-1 Personal A computer (manufactured by Canon) is connected, and 1% NaCl aqueous solution is prepared using first grade sodium chloride as the electrolyte.

  As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzenesulfonate is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 0.5 to 50 mg of a measurement sample is further added.

  The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and a particle distribution of 2 to 40 μm is measured by using the Coulter counter TA-2 type with a 100 μ aperture as an aperture. Determine the volume average distribution. Volume average particles are obtained from the obtained volume average distribution.

(B) Spherical toner SF-1 and SF-2 were used as shape factors representing the sphericity of the toner. SF-1 represents the degree of roundness of the toner, and is 100 for a perfect sphere, and the value changes from spherical to indefinite as the value increases. SF-2 represents the degree of unevenness of the toner, and is 100 in a perfect sphere. As this value increases, the unevenness of the toner surface becomes remarkable.

The values of SF-1 and SF-2 as spherical toner are
SF-1 value = 100 to 160
SF-2 value = 100-140
And more preferably
SF-1 value = 100-140
SF-2 value = 100 to 120
It is.

The values of SF-1 and SF-2 were randomly sampled using a FE-SEM (S-800) manufactured by Hitachi, Ltd., and 100 pieces of toner images enlarged at a magnification of 500 times. This is a value calculated by the following equation after being introduced into an image analysis apparatus (LUZEX3) manufactured by Nicole and analyzed (see FIGS. 15 and 16).
The calculation formula is
SF-1 value = {(MXLNG) ² / AREA} × (π / 4) × 100
SF-2 value = {(PERI) ² / AREA} × (1 / 4π) × 100
AREA: Toner projected area MXLNG: Absolute maximum length PERI: Perimeter.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. Schematic diagram of a “1-motor system” drive system that drives four photosensitive drums Operation process diagram of image forming apparatus Enlarged model of conventional blade cleaning device The enlarged model figure of the low-friction processing blade cleaning device part concerning a 1st embodiment Manufacturing process diagram of low friction processing blade Relationship diagram between stop time and streak image in Comparative Example 1 Schematic of the blade tip in the photosensitive drum stop control of Comparative Example 1 Schematic of the blade tip in the photosensitive drum stop control of Comparative Example 2 Schematic of the blade tip in the photosensitive drum stop control of Comparative Example 3 Schematic of the blade tip in the photosensitive drum stop control of Comparative Example 3 Schematic of the blade tip in the photoreceptor drum stop control of Embodiment 1 Schematic of the blade tip in the photoreceptor drum stop control of Embodiment 1 Manufacturing Process Diagram of Low Friction Processing Blade according to Second Embodiment (Example 2) Explanatory drawing of toner shape factor SF-1 Explanatory drawing of toner shape factor SF-2

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Laser irradiation apparatus 4 Developing apparatus 6 Blade cleaning apparatus 6a Conventional cleaning blade 6b Storage part 6c Support part 6d Squee sheet 6e Surface hardening cleaning blade 6f Curing layer 6g Nylon coating layer 6h Coating cleaning blade 7 Fixing apparatus 11 Drive motor 30 Intermediate transfer belt

Claims (3)

An image carrier;
A cleaning blade that contacts the image carrier and removes the developer;
In an image forming apparatus having
The cleaning blade is provided with a coefficient of friction of 2.0 or less with the image carrier,
In the case of stopping the image carrier, the image carrier is stopped after the image carrier is temporarily stopped and then moved several times intermittently in the same direction as the image formation. apparatus.   The image forming apparatus according to claim 1, wherein a surface of the cleaning blade is subjected to a low friction treatment in which an isocyanate compound is impregnated and the surface is cured.   2. The image forming apparatus according to claim 1, wherein the surface of the cleaning blade is subjected to a low friction process for forming a low friction coating layer.

Images