JP6597206B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus having a function of supplying a lubricant onto an image carrier and an image forming method in the image forming apparatus.

  2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses such as multifunction peripherals, copying machines, and printers have been widely used. Such an electrophotographic image forming apparatus generally includes an image carrier on which a toner image is formed while being rotated, and a transfer apparatus that transfers the formed toner image to a transfer body or a medium. And a cleaning device for removing residual toner such as untransferred toner and transfer residual toner on the image carrier. As a cleaning device, for example, a blade cleaning system is known in which a flat cleaning blade made of an elastic body is brought into contact with the surface of an image carrier to remove residual toner on the image carrier.

  Due to the recent demand for higher image quality and the demand for stable printing operation over a long period of time, the level required for the cleaning device is increasing. On the other hand, the cleaning ability of the blade cleaning method may vary due to various influences. Typically, cleaning blade edge wear. The cleaning blade presses the edge of the cleaning blade against the image carrier and applies a high peak pressure to block the toner, thereby removing residual toner remaining on the image carrier. However, this peak pressure is weakened due to edge wear, so that the cleaning ability of the cleaning blade is lowered, and as a result, the possibility of cleaning failure is increased.

  Further, for the purpose of reducing the frictional force generated between the cleaning member and the image carrier, a lubricant supply mechanism for supplying a lubricant (hereinafter also referred to as “slider”) is provided on the image carrier. It is becoming common. Generally, a metal soap such as a stearic acid metal salt is used as the lubricant. As a lubricant supply mechanism, a mechanism provided with a brush or the like is provided upstream or downstream of the cleaning member, a lubricant is added to the toner and the lubricant is supplied to the developing unit, or they are A combination is known. By providing the lubricant supply mechanism, the lubricant is applied to the surface of the image carrier, and the friction coefficient of the toner on the surface of the image carrier is reduced. Due to the reduction in the friction coefficient, transfer failure when the toner image formed on the surface of the image carrier is transferred to a transfer material or the like is suppressed, and the image quality of the toner image can be improved. In addition, since the coefficient of friction between the image carrier and a member (for example, a cleaning blade) pressed against the image carrier is also reduced, there is an effect of suppressing wear (scraping) on the surface of the image carrier. Life can be extended.

  The following prior art exists regarding the addition of such a lubricant and the improvement of cleaning properties.

  For example, Japanese Patent Application Laid-Open No. 2011-232572 (Patent Document 1) makes it possible to determine the state of the amount of lubricant adhering to the surface of the carrier, and prevents the occurrence of poor cleaning caused by the state of the amount of lubricant adhering. The structure for doing is disclosed. Specifically, in Patent Document 1, the state of the amount of lubricant adhering to the photosensitive drum is determined based on the printing rate and the torque detected from the torque detection unit, and the toner is determined according to the determination result. Formation of a forced discharge pattern toner image or an increase in the amount of lubricant applied by the lubricant application portion is performed.

  Japanese Patent Application Laid-Open No. 2009-047782 (Patent Document 2) prevents the consumption of lubricant from increasing rapidly over time, prevents slipping from the coating blade, and not only the life of the lubricant but also the application brush and charging roller. Disclosed is a lubricant applicator that adjusts the amount of lubricant applied to extend life. Specifically, Patent Document 2 detects the coefficient of friction on the photoconductor by rotational torque, and when the solid lubricant is separated from the application brush, the application brush rotates along with the rotation direction of the photoconductor. The configuration is disclosed.

  Japanese Patent Laying-Open No. 2005-249896 (Patent Document 3) provides an image forming apparatus in which the amount of toner passing through the photoconductor is small by detecting the relationship between the cleaning device and the photoconductor and controlling the cleaning conditions. And a configuration for providing an image forming apparatus in which the cleaning blade is not turned over at the time of cleaning. Specifically, Patent Document 3 discloses a configuration including a detection unit that detects a friction coefficient of the surface of the photosensitive member and an adjustment unit that adjusts the cleaning condition of the photosensitive member based on the friction coefficient detected by the detection unit. .

JP 2011-232572 A JP 2009-047782 A JP 2005-249896 A

  Patent Document 1 focuses on preventing the occurrence of defective cleaning caused by the state of the amount of lubricant attached, and does not solve a solution to the problem of ensuring cleaning performance for a longer period of time.

  Patent Document 2 focuses on extending the life of the lubricant, the application brush, and the charging roller by adjusting the amount of application of the lubricant, and a solution to the problem of ensuring the cleaning performance for a longer period of time. Is not a solution.

  Patent Document 3 focuses on reducing the amount of toner passing through the photoreceptor and reducing the turning of the cleaning blade at the time of cleaning, that is, preventing the deterioration of the cleaning performance. It does not solve the solution to the problem of securing for a longer period.

  Therefore, realization of a new solution is demanded in order to ensure the cleaning property for a longer period.

  An image forming apparatus according to an aspect of the present invention includes an image carrier, a developing unit that develops an electrostatic latent image formed on the image carrier as a toner image, and a transfer unit that transfers the toner image to a transfer medium. A cleaning member that collects toner remaining on the image carrier after the transfer, a lubricant supply unit that supplies a lubricant onto the image carrier, and a measurement unit that measures torque required for rotational driving of the image carrier. And control means capable of adjusting the amount of lubricant supplied to the image carrier. The control means determines whether or not the torque measured by the measurement means is within a predetermined target range during the period in which the cleaning member is in contact with the image carrier while forming an image for the predetermined image. When the measured torque exceeds the target range, the lubricant application conditions are changed so that less lubricant is supplied to the image carrier, while the measured torque falls below the target range. Changing means for changing the application condition of the lubricant so that the amount of lubricant supplied to the image carrier increases.

  Preferably, the changing unit changes a lubricant application condition by controlling a development potential difference given by the developing unit.

  Preferably, the changing unit changes the lubricant application condition by controlling a transfer potential difference given by the transfer unit.

  Preferably, the measuring unit measures torque based on a current value of a motor that rotationally drives the image carrier.

  Preferably, the determination means determines using at least one member other than the cleaning member measured using torque measured in a state where the member is separated from the image carrier.

  Preferably, the determination means makes a determination using torque measured in a state where the members other than the cleaning member and the developing member are separated from the image carrier.

  Preferably, the determination unit determines using a torque measured in a state where a member other than the cleaning member is separated from the image carrier.

  Preferably, the image forming apparatus further includes a charging unit for charging the image carrier, and the determination unit determines using the torque measured in a state where the output of charging by the charging unit is turned off.

Preferably, the predetermined image is a white solid image.
Preferably, the predetermined target range is determined based on a torque measured in an initial stage after replacement of at least one of the image carrier and the cleaning member.

  Preferably, after replacement of at least one of the image carrier and the cleaning member, the predetermined target range is determined based on the torque when the variation rate of the measured torque converges to the predetermined range.

  Preferably, the measuring means outputs an average value obtained by measuring the torque of the image carrier over one round or more as a measured value.

  Preferably, the measurement unit performs the torque measurement after performing the refresh mode for removing the deposits on the surface of the image carrier.

  Preferably, the measuring unit performs the torque measurement after outputting the predetermined number of reference images after the refresh mode.

Preferably, the lubricant is added to the toner.
Preferably, the lubricant supply means includes a mechanism for applying a lubricant independent of the developing means.

  According to another aspect of the present invention, an image forming method in an image forming apparatus is provided. The image forming apparatus includes an image carrier, a developing unit that develops the electrostatic latent image formed on the image carrier as a toner image, a transfer unit that transfers the toner image to a transfer medium, and an image carrier after transfer. It includes a cleaning member that collects toner remaining on the surface, a lubricant supply unit that supplies a lubricant onto the image carrier, and a measurement unit that measures a torque required to rotate the image carrier. In the image forming method, the step of determining whether or not the torque measured by the measuring means is within a predetermined target range during the period in which the cleaning member is in contact with the image carrier while forming an image of the predetermined image. When the measured torque exceeds the target range, the lubricant application conditions are changed so that less lubricant is supplied to the image carrier, while the measured torque falls below the target range. And changing the lubricant application conditions so that the amount of lubricant supplied to the image carrier increases.

  According to the present invention, it is possible to ensure cleaning performance for a longer period.

1 is a schematic configuration diagram showing a cross-sectional configuration of an image forming apparatus according to the present embodiment. It is a schematic diagram which shows one structural example of the imaging unit according to this Embodiment. It is a schematic diagram which shows another structural example of the imaging unit according to this Embodiment. It is a schematic diagram which shows another example of a structure of the imaging unit according to this Embodiment. It is a schematic diagram which shows the evaluation apparatus used for the principle experiment for verifying the main effect of the new knowledge of the present inventors. It is a figure which shows an example of the evaluation result of cleaning property and blade torque using the evaluation apparatus shown in FIG. It is a figure which shows an example of the evaluation result of the lubricating material application amount and blade torque corresponding to the evaluation result shown in FIG. It is a schematic diagram for demonstrating the outline | summary of the process in the image forming apparatus according to this Embodiment. It is a schematic diagram for demonstrating the outline | summary of the process in the image forming apparatus according to this Embodiment. It is a schematic diagram for demonstrating the outline | summary of the process in the image forming apparatus according to this Embodiment. It is a flowchart which shows the process sequence which optimizes the lubricant application conditions performed in the image forming apparatus according to the present embodiment.

  Embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the same or equivalent part in a figure, the same code | symbol is attached | subjected and the description is not repeated.

<A. Device configuration of image forming apparatus>
First, the apparatus configuration of image forming apparatus 100 according to the present embodiment will be described. An image forming apparatus 100 described below is a color image forming apparatus that is mounted as a multi-function peripheral (MFP) as a typical example. However, the mechanism and method for removing the deteriorated lubricant according to the present embodiment can also be applied to a monochrome image forming apparatus. Further, as a mechanism for forming a color image, a tandem method is exemplified, but the present invention can also be applied to a cycle method (typically a 4-cycle method).

  FIG. 1 is a schematic configuration diagram showing a cross-sectional configuration of image forming apparatus 100 according to the present embodiment. Referring to FIG. 1, image forming apparatus 100 includes a print engine 110, a document reading unit 120, and a discharge tray 130.

  The print engine 110 executes an electrophotographic image forming process. In the configuration shown in FIG. 1, full-color print output is possible. The printed medium is discharged to the discharge tray 130. The detailed configuration of the print engine 110 will be described later.

  The document reading unit 120 reads a document and outputs the read result as an input image to the print engine 110. More specifically, the document reading unit 120 includes an image scanner 122, a document feed table 124, an automatic document feeder 126, and a document discharge table 128.

  The image scanner 122 scans a document placed on the platen glass. The image scanner 122 includes, as main components, a light source that irradiates light on a document, an image sensor that acquires an image generated by reflection of light irradiated from the light source, and an image signal output from the image sensor. An AD (Analog to Digital) converter, and an imaging optical system disposed in front of the image sensor.

  The automatic document feeder 126 continuously scans the document placed on the document feeder 124. Documents placed on the document feeder 124 are fed one by one by a delivery roller (not shown), and sequentially scanned by an image sensor arranged in the image scanner 122 or the automatic document feeder 126. The scanned document is discharged to the document discharge table 128.

  The print engine 110 includes imaging units 10C, 10M, 10Y, and 10K (hereinafter referred to as “imaging unit 10”) that generate toner images of cyan (C), magenta (M), yellow (Y), and black (K). May be collectively referred to.)

  As an example, image forming apparatus 100 according to the present embodiment employs a configuration in which a toner image generated by each imaging unit 10 is transferred to medium S that is a transfer target member via an intermediate transfer member. The image forming apparatus 100 includes an intermediate transfer belt 12 stretched by intermediate transfer body driving rollers 14 and 16 as an intermediate transfer body. The intermediate transfer belt 12 is rotated in a predetermined direction by the rotational drive of the intermediate transfer body drive rollers 14 and 16. As the intermediate transfer member, an intermediate transfer roller may be employed instead of the intermediate transfer belt shown in FIG. FIG. 1 illustrates a configuration in which the toner image is once transferred to the intermediate transfer member and then transferred to the medium S. However, the toner image on the photosensitive member may be directly transferred to the medium S.

  The imaging units 10 </ b> C, 10 </ b> M, 10 </ b> Y, and 10 </ b> K are arranged in that order along the intermediate transfer belt 12 that is stretched and rotated in the print engine 110. Each of the imaging units 10 includes a photoreceptor 1, a charging unit 2, an exposure unit 3, and a developing unit 4 (4C, 4M, 4Y, and 4K corresponding to the color of the toner image generated by the corresponding imaging unit 10. And a cleaning blade 5 and an intermediate transfer member contact roller 6.

  The photoreceptor 1 is an image carrier that carries a toner image, and a photoreceptor roller having a photosensitive layer formed on the surface thereof is used. The photoreceptor 1 is arranged so that a toner image is formed on the surface thereof, and rotates in a direction corresponding to the rotation direction of the intermediate transfer belt 12. As the image carrier, a photosensitive belt may be employed instead of the photosensitive roller.

  On the photoreceptor 1, an electrostatic latent image is formed by the exposure unit 3, and the electrostatic latent image is developed by the developing unit 4 to generate a toner image. That is, the charging unit 2, the exposure unit 3, and the developing unit 4 form an electrostatic latent image and a toner image on the photoreceptor 1.

  The charging unit 2 uniformly charges the surface of the photoreceptor 1. The exposure unit 3 exposes the surface of the photoreceptor 1 according to a designated image pattern by laser writing or the like, thereby forming an electrostatic latent image on the surface. Typically, the exposure unit 3 includes a laser diode that generates laser light and a polygon mirror that exposes the surface of the photoreceptor 1 with the laser light along the main scanning direction.

  The developing unit 4 develops the electrostatic latent image formed on the photoreceptor 1 as an image carrier as a toner image. As a typical example, the developing unit 4 develops the electrostatic latent image using a two-component developer composed of toner and carrier. As the developing means, a one-component developer (toner) may be used.

  The toner image formed on the surface of the photoreceptor 1 is transferred to the intermediate transfer belt 12 by the intermediate transfer body contact roller 6. The intermediate transfer member contact roller 6 transfers the toner image developed on the photoreceptor 1 to an intermediate transfer belt 12 that is a transfer medium. The photosensitive member 1 and the intermediate transfer belt 12 are in contact with each other at a portion where the intermediate transfer member contact roller 6 is provided. A predetermined transfer potential difference (transfer bias) is applied to the contacted portion, and the toner image on the photoreceptor 1 is transferred to the intermediate transfer belt 12 by the transfer potential difference. That is, the intermediate transfer belt 12 and bias voltage applying means correspond to transfer means (transfer device).

  On the intermediate transfer belt 12, the toner images are sequentially transferred from the respective photoreceptors 1, and the four color toner images are superimposed. The superimposed toner images are transferred from the intermediate transfer belt 12 to the medium S by the transfer rollers 20 and 21. As a configuration related to the transfer of the medium S, the print engine 110 includes a paper feeding unit 30 that holds the medium S, a sending roller 32, conveyance rollers 34 and 36, and a fixing unit 22. The feed roller 32 sequentially feeds the medium S from the paper feeding unit 30 and is transported by the transport rollers 34 and 36. The toner image can be transferred to an appropriate position on the medium S by synchronizing the timing of sending and conveying the medium S with the position where the toner image is superimposed on the intermediate transfer belt 12. The medium S on which the toner image is transferred is transported to the fixing unit 22 along the transport path 38, and the fixing process of the toner image is executed by the fixing unit 22. Then, the medium S after the toner image is fixed is discharged to the discharge tray 130.

  The print engine 110 includes a control unit 50 that controls the entire image forming apparatus 100. The control unit 50 includes, as main components, a processor such as a CPU (Central Processing Unit), a volatile memory such as a DRAM (Dynamic Random Access Memory), a nonvolatile memory such as an HDD (Hard Disk Drive), and various interfaces. Including. Typically, in the print engine 110, processing related to image formation in the image forming apparatus 100 is executed by the processor executing various programs stored in the nonvolatile memory.

  The control unit 50 is realized by a processor executing a program, but instead of this, all or part of the processing may be realized by using dedicated hardware. When the processor executes a program, the program may be installed in a non-volatile memory via various recording media, or may be downloaded from a server device (not shown) via a communication line.

<B. Basic Image Forming Process in Image Forming Apparatus>
Next, a basic image forming process executed by the image forming apparatus 100 shown in FIG. 1 will be described in the order of execution.

  In each of the imaging units 10, the surface of the photosensitive member 1 is uniformly charged by the charging unit 2, and then subjected to scanning exposure of a laser whose emission is controlled according to the information of the input image by the exposure unit 3. As a result, an electrostatic latent image is formed on the surface of the photoreceptor 1. The image information used in the process of forming the electrostatic latent image (optical writing process) by scanning exposure with the exposure unit 3 while rotating the photosensitive member 1 includes the designated input image (full color image) as cyan, magenta, This is monochromatic image information obtained by decomposing each color information of yellow and black, and the control unit 50 controls laser emission and scanning according to each image information.

  The electrostatic latent image on the photoreceptor 1 formed in accordance with the single color image information is composed of corresponding cyan, magenta, yellow, and black toner by the developing units 4C, 4M, 4Y, and 4K on the respective photoreceptors 1. The toner is developed with a single color developer, and a toner image corresponding to each image information is formed. That is, a single color toner image of a corresponding color is formed on each photoconductor 1. Each single color toner image is sequentially transferred and superimposed on the intermediate transfer belt 12 in synchronism with the corresponding photoreceptor 1 by the action of a predetermined transfer potential difference. The single color toner images superimposed on the intermediate transfer belt 12 are collectively transferred onto the medium S conveyed from the paper feeding unit 30 by the transfer rollers 20 and 21. At this time, a predetermined transfer potential difference is applied between the intermediate transfer belt 12 and the medium S. After the transfer is completed, the toner image on the medium S is fixed by the fixing unit 22, so that a full-color image is completed, and the medium S on which the full-color image is formed is discharged to the discharge tray 130.

  As a final step of the image forming process on the photoconductor 1, the transfer residual toner on the photoconductor 1 (the toner remaining after the toner image formed on the surface of the photoconductor 1 is transferred to the intermediate transfer belt 12) is cleaned. In order to perform cleaning on the surface of the photoreceptor 1, a cleaning blade 5 that is always in pressure contact with the photoreceptor 1 is provided. The cleaning blade 5 is a cleaning member that collects toner remaining on the photoconductor 1 as an image carrier after the toner image is transferred, and presses against the photoconductor 1 to scrape off transfer residual toner from the surface.

  Similarly, the transfer residual toner on the intermediate transfer belt 12 is also cleaned. In order to perform cleaning on the surface of the intermediate transfer belt 12, a cleaning blade 18 that presses against the intermediate transfer belt 12 is provided. The cleaning blade 18 is a cleaning member that collects toner remaining on the intermediate transfer belt 12 as an image carrier after the toner image is transferred.

<C. Lubricant supply mechanism>
Next, a lubricant supply mechanism for supplying a lubricant (lubricant) onto the photoreceptor 1 that is an image carrier will be described. Examples of the configuration of the peripheral members of the image carrier are shown in FIGS. FIG. 2 is a schematic diagram showing a configuration example of the imaging unit 10 according to the present embodiment. FIG. 3 is a schematic diagram showing another configuration example of imaging unit 10 according to the present embodiment. FIG. 4 is a schematic diagram showing still another configuration example of imaging unit 10 according to the present embodiment.

  In the imaging unit 10 shown in FIG. 2, in addition to the charging unit 2, the exposure unit 3, the developing unit 4, and the cleaning blade 5 around the photosensitive member 1, the lubricant supply unit 8 and the leveling agent are provided as a lubricant supply mechanism. A member 9 is arranged.

  The lubricant supply unit 8 includes an application brush 81 that presses against the photoreceptor 1 and the solid lubricant 84. The application brush 81 rotates relative to the photoreceptor 1 to scrape the solid lubricant 84 and apply it to the photoreceptor 1. The leveling member 9 promotes the formation of the lubricant layer on the surface of the photoreceptor 1 by leveling the lubricant supplied by the lubricant supply unit 8.

  The application brush 81 includes a shaft member 82 extending in the width direction (depth direction in the drawing) of the photoreceptor 1 and a plurality of raised hairs 83 disposed on the outer peripheral surface of the shaft member 82. As an example, the application brush 81 is configured by winding and fixing a base fabric having a plurality of raised brushes around a shaft member 82. The length of the base fabric is adjusted so that the raised portions can be brought into contact with at least the entire width direction of the photoreceptor 1. The shaft member 82 is mechanically coupled to a motor (not shown) and can be driven independently of the photoreceptor 1. Further, even if a dedicated motor is not provided, it can be driven by being mechanically coupled to a driving portion of another member.

  After the application brush 81 is rotated, the solid lubricant 84 is scraped off and attached to the raised brush of the application brush 81 and then applied to the surface of the photoreceptor 1. That is, when the application brush 81 is rotationally driven, the lubricant supply unit 8 functions as a lubricant supply mechanism.

  Although FIG. 2 shows a configuration example in which the lubricant supply unit 8 is arranged downstream of the cleaning blade 5, it may be arranged upstream of the cleaning blade 5. In the configuration example shown in FIG. 3, the lubricant supply unit 8 is disposed downstream of the cleaning blade 5 so that the cleaning blade 5 supplies the lubricant in addition to the function of cleaning the transfer residual toner on the photoreceptor 1. The function of leveling the lubricant supplied by the section 8 is exhibited.

  Alternatively, the developing unit 4 may exhibit a lubricant supply function. In the configuration example shown in FIG. 4, the lubricant is supplied to the photoreceptor 1 by adding the lubricant to the toner supplied by the developing unit 4. That is, in the configuration example shown in FIG. 4, the developing unit 4 has a function as a lubricant supply unit.

  In the configuration shown in FIGS. 2 to 4, in order to cancel the residual potential of the photosensitive member 1 and to adjust the toner charge amount, a sub-charging unit 7 is arranged upstream of the cleaning blade 5 (cleaning member). Also good. Furthermore, you may combine the structural example shown in FIGS. 2-4 suitably.

  As described above, as a lubricant supply mechanism that can be employed in the image forming apparatus 100 according to the present embodiment, a lubricant is applied independently of the developing unit 4 (developing means) as shown in FIGS. It is also possible to include a mechanism for Or you may employ | adopt the structure which adds a lubricant to the toner which the image development part 4 supplies as shown in FIG. Further, as shown in FIGS. 2 and 3, a mechanism for applying a lubricant independent of the developing unit 4 (developing unit) and a configuration in which a lubricant is added to the toner supplied by the developing unit 4 are used in combination. It may be.

<D. Lubricant>
In image forming apparatus 100 according to the present embodiment, fatty acid metal salt, silicone oil, fluorine resin, or the like can be used as the solid lubricant. These lubricants can be used alone or in combination of two or more. In particular, fatty acid metal salts are preferred.

  As the fatty acid of the fatty acid metal salt, a linear hydrocarbon is preferable, for example, myristic acid, palmitic acid, stearic acid, oleic acid and the like are preferable, and stearic acid is more preferable. Examples of the metal of the fatty acid metal salt include lithium, magnesium, calcium, strontium, zinc, cadmium, aluminum, cerium, titanium, and iron. Of these, zinc stearate, magnesium stearate, aluminum stearate, iron stearate and the like are preferred, and zinc stearate is most preferred. Natural wax such as carnauba wax may also be used. Of these, metal stearates are particularly preferred.

<E. Developer>
In image forming apparatus 100 according to the present embodiment, a developer including toner and a carrier for charging the toner is used. The toner is not particularly limited, and known toners that are generally used can be used. For example, a colorant and, if necessary, a charge control agent, a release agent and the like contained in a binder resin and then processed with an external additive can be used as a toner. The toner particle size is not limited to this, but is preferably about 3 to 15 μm.

  Further, the toner may contain a lubricating external additive. The lubricating external additive is not particularly limited, and fatty acid metal salts, silicone oils, fluororesins, and the like can be used. These lubricating external additives can be used alone or in admixture of two or more. In particular, fatty acid metal salts are preferred.

  As the fatty acid of the fatty acid metal salt, a linear hydrocarbon is preferable, for example, myristic acid, palmitic acid, stearic acid, oleic acid and the like are preferable, and stearic acid is more preferable. Examples of the metal of the fatty acid metal salt include lithium, magnesium, calcium, strontium, zinc, cadmium, aluminum, cerium, titanium, and iron. Of these, zinc stearate, magnesium stearate, aluminum stearate, iron stearate and the like are preferred, and zinc stearate is most preferred.

  It does not specifically limit as a carrier, The well-known carrier generally used can be used. For example, a binder type carrier, a coat type carrier and the like can be used. Although it is not limited to this as a carrier particle size, 15-100 micrometers is preferable.

<F. New knowledge by the present inventors>
Hereinafter, new knowledge of the inventors of the present application employed by image forming apparatus 100 according to the present embodiment will be described in detail.

  FIG. 5 is a schematic diagram showing an evaluation apparatus used in a principle experiment for verifying the main effect of the new knowledge of the inventors of the present application. Using an evaluation apparatus as shown in FIG. 5, the relationship between cleaning properties and torque was investigated. In this specification, “torque” means a torque (dynamic torque) required for rotational driving of the photoreceptor 1 as an image carrier, and can be measured by an arbitrary method as described below.

  As an example, in the mechanism shown on the left side of FIG. 5, the photoconductor 1 is connected to a motor (not shown), and a torque measuring device (TP-10KCE manufactured by Kyowa Denki Co., Ltd.) (not shown) is used to measure the driving torque of the motor. It is connected.

  A cleaning device including a cleaning blade 5 is attached to the photoreceptor 1. A developing unit 4 for developing the toner image is attached so that an arbitrary potential difference can be given to the photosensitive member 1. In this evaluation, since evaluation is performed by paying attention to torque between the photosensitive member 1 and the cleaning blade 5 (hereinafter referred to as “blade torque”), members other than the developing unit 4 and the cleaning blade 5 (for the photosensitive member 1). For example, a transfer rotor and a charging roller are arranged.

  Further, in order to investigate the behavior when the lubricant was applied, a lubricant supply unit 8 as shown on the right side of FIG. 5 was separately prepared. Specifically, the lubricant supply unit 8 has a lubricant rod made of zinc stearate, a brush, and a leveling blade (leveling member 9) so that the lubricant can be applied onto the photoreceptor 1. did.

  The cleaning blade 5 was made of urethane rubber and had a rebound resilience of 50% (25 ° C.), a JIS A hardness of 70 °, a thickness of 2 mm, and a free length of 10 mm. Further, the contact load with respect to the photoreceptor 1 was set to 16 N / m.

  Using the evaluation apparatus shown in FIG. 5, the cleaning performance and the blade torque required for driving the photoreceptor 1 were evaluated.

The cleaning property was quantified by supplying a uniform black solid image (adhesion amount 4 g / m ² ) to the cleaning blade 5 and measuring the toner amount after passing through the cleaning blade 5.

  The toner amount was evaluated by peeling the toner remaining on the photoreceptor 1 after passing through the cleaning blade 5 with a PET tape and measuring the transmission density (measured with X-Rite 310 manufactured by Sakata Inx Corporation).

  Regarding the blade torque, a voltage equivalent to the background portion (+200 V) was applied to the developing portion 4 and the driving torque of the motor generated when the white solid image was formed was measured.

  Two types of cleaning blades 5 were tried: one that was not worn and one that was worn to a blade edge wear width of 40 μm. In addition, in the case of using a worn product, an attempt was made to apply a lubricant to the surface of the photoreceptor 1. The amount of the lubricant on the photoreceptor 1 was changed by changing the number of times the lubricant was applied using the mechanism shown on the right side of FIG. After applying the lubricant, the photoconductor 1 was removed from the lubricant applicator and the cleaning property and blade torque were measured again. In the above experiment, the surrounding environment was a room temperature of 15 ° and a humidity of 15%.

  FIG. 6 is a diagram illustrating an example of evaluation results of cleaning performance and blade torque using the evaluation apparatus shown in FIG. In FIG. 6, the filled plot (no wear BL) shows the result when the cleaning blade 5 is not worn, and the white plot (wear BL) shows the result when the cleaning blade 5 is worn.

  The vertical axis (CL index (TD)) in the graph of FIG. The smaller the value on the vertical axis in FIG. 6, the smaller the amount of toner that has passed through the cleaning blade 5, and the smaller the value, the better the cleaning property. From the graph shown in FIG. 6, it can be seen that a high correlation exists between the cleaning performance and the blade torque.

  In addition, when the wear error is given, the cleaning performance is lowered by wearing the cleaning blade 5, but as shown in FIG. 6, the cleaning performance is improved by applying the lubricant, and the blade torque is accordingly increased. You can see that it is rising. That is, it can be said that the cleaning property can be controlled to a desired level if the blade torque can be measured and controlled.

  Next, the relationship between the amount of lubricant applied and the blade torque when the lubricant was applied in the above experiment was also investigated.

  FIG. 7 is a diagram showing an example of the evaluation result of the lubricant application amount and the blade torque corresponding to the evaluation result shown in FIG. In FIG. 7, the fretting material application amount was substituted with the Nell friction coefficient. The Nell friction coefficient was measured using HEIDON Tribogear 94i. In general, it is known that the friction coefficient decreases as the amount of lubricant applied increases.

  As shown in FIG. 7, by applying blade wear, the blade torque is reduced (see solid plot (no wear BL) and white plot (wear BL) at the right end of FIG. 7).

  It can also be seen that even in the system using the worn cleaning blade 5, the torque is increased by applying the lubricant (the torque values in each plot in FIG. 7 correspond to the torque values in each plot in FIG. 6). is doing). It can also be seen that the blade torque increases uniformly by increasing the application amount sequentially from the state where no lubricant is applied.

  The above-described result, that is, an assumed mechanism that causes a close correspondence between the amount of the lubricant and the blade torque will be described below. By applying the lubricant, the unevenness of the surface of the photoreceptor 1 is filled and the smoothness is increased, or the friction force between the fog toner and the external additive and the photoreceptor 1 is decreased. As a result, toner or external additives passing between the cleaning blade 5 and the photoreceptor 1 are reduced. It is considered that the toner or external additive particles passing between the cleaning blade 5 and the photosensitive member 1 reduce the blade torque due to the rolling effect. That is, although the torque between the cleaning blade 5 and the photoconductor 1 is suppressed by the rolling effect, the contact area between the cleaning blade 5 and the photoconductor 1 is increased by reducing the rolling effect, It is considered that the blade torque is increasing.

  With such an assumed mechanism, it is considered that the blade torque is uniformly increased by the application of the lubricant. From this assumed mechanism, it is considered that a good result is that the cleaning performance and the blade torque correspond well.

Summarizing the above experimental results leads to the following new findings.
(1) There is a close correspondence between blade torque and cleanability (FIG. 6).
(2) There is a close correspondence between the amount of lubricant and blade torque (FIG. 7).
(3) By increasing the amount of lubricant, the blade torque increases uniformly (FIGS. 6 and 7).
<G. Outline of processing>
Based on the new knowledge found by the inventors of the present application as described above, the following control is performed. Image forming apparatus 100 according to the present embodiment is equipped with a measurement function for measuring torque required for rotational driving of photosensitive member 1 that is an image carrier, and the amount of lubricant supplied to photosensitive member 1 is adjusted. Adjustable control functions are implemented. Then, a processing procedure as described below is executed.

  8 to 10 are schematic diagrams for illustrating the outline of processing in image forming apparatus 100 according to the present embodiment. In general, the blade torque decreases with wear, and when the blade torque decreases to exceed the cleaning failure threshold, cleaning failure occurs or cleaning failure is very likely to occur. As a general setting, in consideration of such a phenomenon, as shown in FIG. 8, a blade torque (cleaning property) with a margin is adopted as an initial setting.

  On the other hand, in image forming apparatus 100 according to the present embodiment, a decrease in blade torque is measured, and the application condition of the lubricant is controlled accordingly. As a result, it is possible to always maintain the blade torque with guaranteed cleaning performance. That is, as shown in FIG. 9, the cleaning property can be secured for a longer period of time as compared with the conventional method. In other words, if the generated blade torque is low, the amount of lubricant on the photoreceptor 1 is controlled to increase.

  On the other hand, if the generated blade torque is high, the wear of the cleaning blade is promoted. Therefore, it is preferable to set the blade torque in consideration of wear. According to the present embodiment, as shown in FIG. 10, it is possible to always set the optimum condition that suppresses blade wear and secures the cleaning property. In other words, it is possible to extend the life of the blade while ensuring the cleaning property. Also in this case, if the blade torque is low, the amount of lubricant on the photosensitive member 1 is controlled to be increased. Conversely, if the blade torque is high, the amount of lubricant on the photosensitive member 1 is decreased.

<H. Processing procedure>
Next, a processing procedure for optimizing the lubricant application condition according to the present embodiment will be described. FIG. 11 is a flowchart showing a processing procedure for optimizing the lubricant application condition executed in image forming apparatus 100 according to the present embodiment. Each step shown in FIG. 11 is typically executed by the control unit 50 executing a control program installed in advance.

  Referring to FIG. 11, control unit 50 determines whether or not an instruction to start image formation has been issued (step S100). If the start of image formation is not instructed (NO in step S100), the processes in and after step S100 are repeated.

  If the start of image formation is instructed (YES in step S100), control unit 50 starts image formation in print engine 110 (step S102). That is, the print job is turned on. Subsequently, the control unit 50 counts the number of printed sheets (number of printed sheets) by the formed image formation (step S104).

  Subsequently, the control unit 50 determines whether or not the number of prints after counting up has reached a specified value (step S106). If the number of prints after the count-up has not reached the specified value (NO in step S106), the processing from step S100 onward is repeated.

  If the number of prints after counting up has reached the specified value (YES in step S106), control unit 50 transitions to a torque measurement mode (step S108). In the torque measurement mode, the control unit 50 measures the torque generated in the photoconductor 1. Subsequently, the control unit 50 determines whether or not the acquired measured value of torque is within a predetermined target range (step S110). In other words, the control unit 50 forms torque for a predetermined image (typically, a solid white image), and the torque measured by the torque measurement function during the period in which the cleaning blade 5 is in contact with the photoreceptor 1. It is determined whether it is within a predetermined target range.

  If the acquired torque measurement value is not within the predetermined target range (NO in step S110), control unit 50 determines whether or not the acquired torque measurement value is below the predetermined target range. (Step S112). If the acquired measured value of torque is below the predetermined target range (YES in step S112), control unit 50 increases the amount of lubricant applied (step S114). That is, if the torque measurement result is lower than the predetermined lower threshold, control is performed to change the lubricant application condition so that the amount of the lubricant on the photoreceptor 1 is increased. And the process after step S110 is repeated.

  On the other hand, if the acquired measured value of torque is not below the predetermined target range (NO in step S112), control unit 50 determines whether or not the acquired measured value of torque exceeds the predetermined target range. Is determined (step S116). If the acquired measured value of torque exceeds the predetermined target range (YES in step S116), control unit 50 decreases the lubricant application amount (step S118). That is, if the torque measurement result is higher than the predetermined upper limit threshold, control is performed to change the lubricant application condition so as to reduce the amount of lubricant on the photoreceptor 1. And the process after step S110 is repeated.

  If the acquired measured torque value does not exceed the predetermined target range (NO in step S116), the processing in step S110 and subsequent steps is repeated.

  In this way, the lubricant application condition is changed as needed so that the measured torque value falls within the predetermined torque range. That is, when the measured torque exceeds the target range, the control unit 50 changes the application condition of the lubricant so that the amount of the lubricant supplied to the photoreceptor 1 is reduced, while the measured torque Is less than the target range, the lubricant application condition is changed so that the lubricant supplied to the photoreceptor 1 increases.

  If the acquired measured torque value is within the predetermined target range (YES in step S110), the control unit 50 sets the current lubricant application condition as the lubricant application condition at the time of new image formation. In addition to updating (step S120), the number of prints is reset (step S122). And the process after step S100 is repeated.

  That is, torque measurement and control of the lubricant application conditions are repeated until the measured torque falls within a predetermined range. Then, the lubricant application condition determined by the result of this repeated processing is fed back as a condition at the time of image formation (printing). When this series of operations is completed, the image forming operation (printing operation) is resumed. Note that when the image formation (printing) is finished, an end command is issued as appropriate.

  By the processing procedure as described above, the lubricant application condition in image forming apparatus 100 according to the present embodiment is optimized.

  Even if the above-described steps S112 to S118 are performed a predetermined number of times, if the measured torque value does not fall within the predetermined target range, the life of the cleaning blade 5 may be determined. In this case, the image forming process may be prohibited until the user is notified of the replacement of the cleaning blade 5 or until the cleaning blade 5 or the imaging unit including the cleaning blade 5 is replaced. By implementing such a process, it is possible to prevent problems caused by defective cleaning.

  If the measured torque does not increase until the predetermined lower threshold is exceeded even after adjusting the amount of lubricant, the lubricant application amount is set to the maximum and the image forming process (printing process) is continued. It may be.

  A specific method for adjusting the amount of the lubricant supplied to the photosensitive member 1 (increasing the amount of lubricant applied (step S114) and decreasing the amount of lubricant applied (step S118)) will be described later in <K. The control method of the lubricant application amount will be described in detail below.

  FIG. 11 shows a typical processing procedure of the processing for optimizing the lubricant application condition according to the present embodiment, and various processing elements described later or known elements are appropriately combined with these processing procedures. Also good.

<I. Setting method of torque target value and control range>
Next, a torque target value and control range setting method used in the above-described control procedure will be described.

  The magnitude of the driving torque necessary for rotating the photosensitive member 1 is affected by the composition of the photosensitive member 1, the device size, the driving system, and the like. Therefore, it is preferable not to uniquely determine the torque target value and the absolute value of the control range, but to set in consideration of the cleaning performance and the degree of wear according to the model of the image forming apparatus 100 and the like.

(I1: Setting method 1)
As an example of a method for setting the torque target value, the torque is measured immediately after the cleaning blade 5 is replaced or immediately after the drum unit including the photosensitive member 1 is replaced, and the target necessary for the above control based on the measured value of the torque. A value or target range may be set. That is, the predetermined target range used for the above-described control is preferably determined based on the torque measured in the initial stage after replacement of at least one of the photoreceptor 1 and the cleaning blade 5.

  This is because it is generally considered that the cleaning performance is sufficiently ensured in the initial stage of the unit durability immediately after the cleaning blade and / or the drum unit is replaced. Further, according to the control method according to the present embodiment, it is possible to accurately control the torque with a guaranteed cleaning property even if there is a machine difference, an individual difference of the cleaning blade, an individual difference of the photosensitive member, and the like.

(I2: Setting method 2)
As another example of the method for setting the torque target value, the torque measured after printing for a certain period (or a certain number of sheets) after replacing the cleaning blade or after replacing the drum unit is used as the initial torque, What is necessary is just to set the target value or target range required for said control on the basis of the said initial torque. In the initial drum unit, there are several fluctuation factors such as sharp wear or chipping of the edge of the cleaning blade, fluctuation of the attitude of the cleaning blade, and influence of oil applied at the time of shipment, and torque fluctuation is large. Therefore, immediately after replacement, there is a possibility that it is not always in a preferable state (a state in which both cleaning properties and wear are compatible).

  Therefore, in order to confirm that the cleaning blade is in a preferable state (that is, a steady state in which steep torque fluctuations are settled), a new drum unit or a new cleaning blade unit is mounted, and the photosensitive from the start of printing is performed. The body torque is measured, and the torque at the time when the rate of change in torque (current measurement value / previous measurement value) falls within the threshold may be set as the target torque. That is, it is preferable to determine the predetermined target range based on the torque when the variation rate of the measured torque converges to the predetermined range after replacement of at least one of the photoreceptor 1 and the cleaning blade 5.

<J. Torque measurement method>
Next, a method for measuring torque necessary for carrying out the control method according to the present embodiment will be described.

  For example, the torque of the photoconductor can be measured by attaching a torque meter to the drive shaft of the photoconductor 1 and monitoring the output value. That is, the torque measurement function mounted on the image forming apparatus 100 may measure torque (dynamic torque) based on the current value of the motor that rotationally drives the photoreceptor 1.

  As another method, the photoconductor torque may be calculated by monitoring the value of the current flowing through the motor that drives the photoconductor 1. By adopting a configuration for monitoring the value of the current flowing through the motor, it is possible to measure the photoreceptor torque without increasing the size and cost of the apparatus.

  When measuring the torque, it is preferable to keep the members other than the necessary members away from the photoreceptor 1. That is, it is preferable that the torque used for determining whether or not it is within the predetermined target range is a value measured in a state where at least one member other than the cleaning blade 5 is separated from the photoreceptor 1.

  More specifically, it is preferable that parts other than the cleaning blade 5 and the developing unit 4 are separated from the photoreceptor 1. That is, it is preferable to determine whether or not the cleaning member and the member constituting the developing unit 4 are within a predetermined target range by using torque measured in a state where the member is separated from the photoreceptor 1. This is because the inventor's new knowledge as described above is mainly based on the torque between the photosensitive member 1 and the cleaning blade 5, and even in actual control, between the photosensitive member 1 and the cleaning blade 5. It is preferable to measure only the torque generated between them. Here, when a member other than the cleaning blade 5 (for example, a transfer unit and a charging roller) is in contact with the photosensitive member 1, a torque component derived from the member is also measured together.

  Therefore, as the most preferable mode, it is preferable to measure in a state where only the cleaning blade 5 is in contact with the photosensitive member 1 in order to obtain torque necessary for control. That is, it is preferable to determine whether or not a member other than the cleaning blade 5 is within a predetermined target range by using the torque measured in a state where the members are separated from the photoreceptor 1.

  Further, when measuring the torque, it is preferable to use a white solid image as the predetermined image to be formed. This is because when a toner image is formed on the photosensitive member 1, a torque component caused by the toner is added to the measured torque value, which causes an error.

  Further, when measuring the torque, it is preferable to remove torque fluctuation factors other than the lubricant on the photoreceptor 1. During image formation, discharge products and the like discharged from the charging unit 2 adhere to the photoreceptor 1. This discharge product combines with moisture to form a low resistance component, which causes image blurring, and can cause abnormal torque increase by altering the surface of the lubricant and the photoreceptor 1. Therefore, by measuring and adjusting the torque in a state where these error factors are removed, the cleaning property can be accurately controlled according to the target state. It is preferable to implement a so-called refresh mode as a method for removing such torque fluctuation factors. Various methods have been proposed as a refresh mode method for the photoreceptor 1, and a method according to need may be employed. For example, the discharge product on the photoreceptor 1 can be removed by providing a mode in which toner is supplied from the developing unit 4 and cleaning is performed by the cleaning blade 5. At this time, if the transfer electric field is controlled to supply more toner to the cleaning blade, the removal effect can be enhanced. As described above, it is preferable to perform the torque measurement after performing the refresh mode for removing the deposits on the surface of the photoreceptor 1.

  Further, when the torque is measured after the refresh mode as described above is performed, it is preferable to perform after a specified number of reference images have been printed. That is, it is more preferable to perform torque measurement after outputting a predetermined number of reference images after performing the refresh mode. The control method according to the present embodiment is to control the blade torque generated during image formation within a predetermined target range. For this reason, when evaluating the blade torque, it is preferable that the blade torque be in the same state as during image formation. At this time, it is more preferable to eliminate the influence of discharge products as much as possible.

  On the other hand, the blade torque is adjusted after the refresh mode for the photosensitive member 1 is performed. However, there is a possibility that the value of the blade torque does not accurately correspond to that during image formation. This is because during the image formation, in addition to the supply of the lubricant from the lubricant application mechanism, the recovery of the lubricant by the toner supplied to the cleaning blade 5 and the recovery of the lubricant by the developing unit 4 also occur. This is because the amount of the lubricant on the photoreceptor 1 is determined depending on the balance. For this reason, if a predetermined number of reference images (for example, a horizontal band pattern formed over the entire axial direction) are printed and then torque measurement is performed, the blade torque corresponding to the image formation can be measured.

  In addition, the image formation that occurs during the torque measurement may be printed on the actual paper surface. However, the voltage of the intermediate transfer or the secondary transfer is adjusted, and the photoreceptor 1 or the intermediate before the toner reaches the paper. The toner image may be collected with a transfer blade cleaning blade. In this way, it is not necessary to use paper during adjustment, and costs can be reduced.

  Further, when the torque is measured in a state where the developing unit 4 is in contact with the photosensitive member 1, the output of the charging unit 2 is turned off and bias development with the photosensitive member 1 is preferably performed. In other words, it is preferable to determine whether or not the vehicle is within a predetermined target range using the torque measured with the charging output from the charging unit 2 turned off. By adopting such a method, it is possible to avoid the generation of discharge products and the influence thereof when measuring torque. Such an operation may be applied when the above-described reference image is printed.

  Further, when measuring the torque, it is preferable to measure at least the torque of the photosensitive member 1 over one turn. More specifically, an average value obtained by measuring the torque of the photosensitive member 1 over one turn or more may be output as a measured value. This is to reduce the influence of abnormal points (for example, scratches) on the photoconductor 1 and to remove the influence of the eccentricity of the photoconductor 1.

<K. About control method of lubricant application amount>
Next, a method for controlling the amount of lubricant applied to the photoreceptor 1 will be described. Hereinafter, a case where a lubricant is added to the toner will be described as an example.

  In the developer, most of the lubricant is attached to the toner particles. However, a part of the lubricant does not adhere to the toner but exists in the developer in a free state. When the developer is carried to the developing unit 4 in such a state, the toner is developed on the photosensitive member 1 in the image portion, and the lubricant adheres to the toner and is carried onto the photosensitive member 1. Normally, the lubricant is charged with a polarity opposite to that of the toner. Therefore, the lubricant that is free in the developer and a part of the lubricant attached to the toner are not only in the image area but also in the background area. Also adhere.

  Thereafter, the photosensitive member 1 contacts the intermediate transfer member, and the toner is transferred to the intermediate transfer member by the voltage applied to the intermediate transfer member. The electric field at the transfer portion is an electric field that presses the lubricant toward the photoreceptor 1, and the lubricant attached to the toner leaves the toner and remains on the photoreceptor 1 side.

  Since the toner and the lubricant are charged with opposite polarities, if an electric field opposite to the electric field in which the toner moves is applied, the amount of lubricant supplied onto the photoreceptor 1 increases. Even when an electric field for moving the toner is applied, the amount of lubricant supplied to the photosensitive member 1 increases as the electric field strength decreases.

Considering such an operating principle, when a lubricant is added to the toner, the amount of lubricant on the photoreceptor 1 can be effectively controlled by the following method.
(1) Controlling the development potential difference By reducing the development potential difference, the amount of lubricant supplied to the photoconductor 1 is increased, and conversely, by increasing the development potential difference, the lubricant supplied to the photoconductor 1 is increased. The amount decreases. However, when an electric field opposite to toner movement is applied, the development potential difference is increased, so that the amount of lubricant supplied to the photoreceptor 1 is increased, and conversely, the development potential difference is decreased to reduce the photosensitive potential. The amount of lubricant supplied to the body 1 decreases. In this way, the control unit 50 changes the application condition of the lubricant by controlling the development potential difference (development bias) given by the development unit 4.
(2) Controlling the transfer potential difference By increasing the transfer potential difference, the amount of lubricant supplied to the photoconductor 1 increases, and conversely, by reducing the transfer potential difference, the lubricant supplied to the photoconductor 1. The amount decreases. In this way, the control unit 50 changes the application condition of the lubricant by controlling the transfer potential difference (transfer bias) given by the transfer device (transfer means).

  Both the development potential difference and the transfer potential difference may be controlled. Further, the amount of lubricant supplied to the photoreceptor 1 can be increased by increasing the amount of lubricant added to the toner.

  With respect to the development potential difference and the transfer potential difference, when these operations are applied in patch formation performed during normal image formation, the amount of the lubricant on the photoreceptor 1 can be controlled without directly affecting the image formation conditions. It becomes possible.

  For example, when a patch is formed during image formation, if the development potential difference is made smaller than that during normal image formation, the amount of lubricant transferred onto the photoreceptor 1 increases. Further, if the transfer potential difference is made larger than that during normal image formation, the amount of the lubricant on the photoconductor 1 increases.

<L. Lubricant supply from the lubricant supply unit 8>
When supplying the lubricant from the lubricant application mechanism, it is effective to change the rotation speed of the supply member as a method for adjusting the lubricant supply amount. Taking the lubricant supply unit 8 shown in FIG. 2 as an example, an application brush 81 is provided as a supply member.

  As an example, a case where the rotation direction of the application brush 81 counter-rotates with respect to the photoreceptor 1 will be described. When the rotation speed of the application brush 81 is increased, the number of times of contact with the photoreceptor 1 and the sliding rod per unit time increases. As a result, the amount of the application brush 81 scraping the lubricant from the lubricant rod per unit time and the number of times per unit time to be transferred to the photoreceptor 1 are increased, and as a result, the lubricant that is transferred onto the photoreceptor 1. The amount of increases. Even when the application brush 81 rotates with respect to the photosensitive member 1, the same relationship is established.

  Further, as a method for adjusting the lubricant supply amount, the pressing force of the lubricant rod against the application brush 81 may be changed. In this case, the amount of the application brush 81 scraping the lubricant from the lubricant rod per unit time increases, and as a result, the amount of lubricant supplied onto the photoreceptor 1 increases. In addition, when the lubricant is applied by the lubricant application mechanism, the developing unit 4 scrapes the lubricant on the photosensitive member 1, so that the lubricant can be mixed into the developing unit 4. Therefore, in consideration of the integrated value of the number of printed sheets, if the lubricant is mixed into the developing unit 4, the control when the lubricant is added to the toner may be used together.

  Further, when the lubricant application mechanism and the toner addition to the lubricant are used in combination, both of the two control methods described above can be applied. In addition to the control method described above, a method effective for controlling the amount of lubricant applied to the photoreceptor 1 can be applied to the control method according to the present embodiment.

<M. Effect confirmation experiment>
The results of several experiments (Examples 1 to 3 and Comparative Examples 1 to 4) for confirming the effect of the cleaning property by the image forming apparatus 100 according to the present embodiment described above are shown below.

  As a specific experimental procedure, the life of the cleaning blade was evaluated by continuously passing the A4 horizontal band pattern (5%) based on the image forming apparatus shown in FIG. Specifically, a half image was output every 10 kp (10000 sheets), the generation of streaks originating from the cleaning blade being left unwiped was evaluated, and the life of the blade was determined when a significant streak occurred.

  As a specific apparatus configuration, the configuration of the photosensitive member 1, the developing unit 4, the transfer device, the cleaning blade, the toner, and the like according to the configuration shown in FIG. As a base image forming apparatus, a modified version of bizhub PRESS C1000 manufactured by KONICA MINOLTA was used.

(1) Photoconductor 1
As the photoreceptor 1, an organic photoreceptor having a diameter of 80 mm in which a photosensitive layer made of polycarbonate resin and having a thickness of 25 μm was formed on the outer peripheral surface of a drum-shaped metal substrate made of aluminum was used. The photoreceptor 1 was rotated at 400 mm / sec.

(2) Development unit 4
The developing unit 4 has a developing sleeve that is rotationally driven at a linear velocity of 600 mm / min. A bias voltage having the same polarity as the surface potential of the photoreceptor 1 is applied to the developing sleeve, and reversal development is performed by a two-component developer. What was done was used.

(3) Transfer device An endless belt made of a polyimide resin imparted with conductivity is used as an intermediate transfer member of the transfer device, and is brought into pressure contact with the photosensitive member 1 through the belt, and a voltage having a polarity opposite to the charged polarity of the toner is applied. A transfer roller provided with a transfer roller was used.

(4) Cleaning blade 5
As the cleaning blade 5, a urethane rubber having a rebound resilience of 50% (25 ° C.), a JIS A hardness of 70 °, a thickness of 2 mm, a free length of 10 mm, and a width of 324 mm was used. For the cleaning blade 5, the contact load with respect to the photoreceptor 1 was changed for each condition, and the contact angle was set to 15 °.

(5) Toner As a toner constituting the two-component developer, a toner particle having a volume average particle diameter of 6.5 μm produced by an emulsion polymerization method was used. The toner was given negative chargeability. When the lubricant was added to the toner particles, the toner particles added with zinc stearate were used. For details, see <E. Since it was described in “Developer>, it will not be repeated here.

(6) Lubricant Bar As a case where the lubricant supply unit 8 shown in FIG. 2 is arranged, a mechanism is adopted in which the lubricant is scraped from the lubricant bar with a brush and transferred to the photoreceptor 1. As the shape of the brush, a straight hair shape was used, and as the lubricant rod, a material obtained by compression molding zinc stearate was used. Further, as the leveling blade (leveling member 9), a material having the same physical properties as the cleaning blade 5 was disposed so as to be pressed in the trail direction. The linear pressure was 20 N / m, and the contact angle was 50 °. The brush was rotated in the counter direction with respect to the photoreceptor 1.

  The results of the effect confirmation experiment are shown in the table below.

  In the above table, Comparative Examples 1 to 4 are experiments for evaluating the cleaning performance when the control according to the present embodiment is not applied, and the mechanism of the imaging unit 10 shown in FIG. 2 or FIG. 4 is employed. Specifically, it is as follows.

  In Comparative Example 1, the mechanism shown in FIG. 4 was used, and a toner added with 0.2 parts by weight of a lubricant was used. The blade pressure was 30 N / m. The initial torque at this time was 200 mN / m.

  In Comparative Example 2, the mechanism shown in FIG. 2 was used, and the peripheral speed ratio of the coating brush to the photoreceptor 1 was set to 0.4. The blade pressure was 30 N / m. The initial torque at this time was 400 mN / m.

  In Comparative Example 3, the mechanism shown in FIG. 4 was used, and a toner added with 0.2 parts by weight of a lubricant was used. The blade pressure was 24 N / m. The initial torque at this time was 160 mN / m.

  In Comparative Example 4, the mechanism shown in FIG. 2 was used, and a toner added with 0.2 parts by weight of a lubricant was used. The blade pressure was 24 N / m. The initial torque at this time was 320 mN / m.

  The initial torque is measured by measuring the blade torque generated when the reference image (solid white image) is formed when 5 kp (5000 sheets) has elapsed. When measuring the initial torque, the other members except the developing unit 4 and the cleaning blade 5 were controlled to be separated from the photoreceptor 1.

  Examples 1 to 3 are experiments for evaluating the cleaning performance by the control according to the present embodiment, and the mechanism of the imaging unit 10 shown in FIG. 2 or FIG. 4 was adopted. Specifically, it is as follows.

  In Example 1, the mechanism shown in FIG. 4 was used, and a toner added with 0.2 parts by weight of a lubricant was used. The blade pressure was 30 N / m. The initial torque at this time was 200 mN / m. Using this initial torque as a reference, development conditions and transfer conditions were controlled according to the control logic according to the present embodiment.

  In Example 2, the mechanism shown in FIG. 2 was used, and a toner to which no lubricant was added was used. The peripheral speed ratio of the coating brush to the photoreceptor 1 was set to 0.4. The blade pressure was 30 N / m. The initial torque at this time was 400 mN / m. Using this initial torque as a reference, development conditions and transfer conditions were controlled according to the control logic according to the present embodiment.

  In Example 3, the mechanism shown in FIG. 4 was used, and a toner added with 0.2 parts by weight of a lubricant was used. The blade pressure was 24 N / m. The initial torque at this time was 160 mN / m. Using this initial torque as a reference, development conditions and transfer conditions were controlled according to the control logic according to the present embodiment.

  In Examples 1 to 3, the torque target value was set to ± 10% with respect to the initial torque. When the torque decreases with respect to the threshold range (± 10% with respect to the initial torque) and does not fall within the threshold range, printing is continued with the maximum lubricant supply condition. Further, torque measurement and supply condition control were performed every 10 kp (10000 sheets). At this time, the measured value of the blade torque generated when the reference image (solid solid image) was image-formed at the time when every 10 kp (10000 sheets) had elapsed was used.

  As a result of the above-described effect confirmation experiment, the blades of Comparative Examples 1 to 3 were all at a level that did not reach the target. This is presumably because the cleaning performance deteriorated due to edge wear of the cleaning blade because the control logic according to the present embodiment was not applied. In Comparative Example 3 and Comparative Example 4, the blade pressure was set low in order to reduce edge wear, but conversely, the cleaning performance deteriorated and the life was shortened.

  In contrast to these comparative examples, in Examples 1 to 3, it was possible to extend the life of the cleaning blade 5 even with the same configuration as that of the comparative example. That is, it means that the reliability during long-term driving of the image forming apparatus can be improved.

  In particular, in Example 3 in which the blade pressure was set low, the lifespan was shortened in comparison examples 3 and 4, but the lifespan was successful. This is because the torque is kept small (that is, the wear rate is small), and the blade wear is suppressed and the cleaning property is maintained.

<N. Summary>
As described above, as a result of intensive research, the inventors of the present application have a close relationship with the driving torque (torque between the photosensitive member and the cleaning blade) generated when the cleaning blade is pressed against the photosensitive member. I found out. The inventors of the present application have also found that the torque can be controlled by the amount of the lubricant on the photoreceptor. Furthermore, the inventors of the present application have found that there is a close relationship between the amount of the lubricant and the torque, and that the torque increases as the amount of the lubricant increases, and the torque decreases as the amount of the lubricant decreases.

  Based on such new knowledge, the torque generated on the photoconductor during image formation is maintained at an appropriate value by controlling the coating amount of the lubricant on the photoconductor. Thereby, cleaning property can be maintained and long-term reliability for cleaning can be ensured. In other words, the function of measuring torque is adopted, and the coating condition of the lubricant during printing is updated as needed so that the torque generated during image formation is maintained within a predetermined target range, thereby cleaning at the initial stage. Long-term cleaning reliability is improved while maintaining the properties.

  In this way, by controlling the amount of the lubricant applied to the photoreceptor 1 during image formation so that the torque generated during image formation is maintained within a predetermined target range, the amount of wear of the cleaning blade is not affected. Therefore, the cleaning can be performed stably and the reliability can be improved.

  In addition, by controlling the amount of lubricant applied to the photosensitive member 1 during image formation so as to match the initial torque generated immediately after the drum unit or cleaning blade is replaced, it is stable regardless of the difference in the image forming apparatus. Thus, torque control can be performed. As a result, stable cleaning can be performed and reliability can be improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Photoconductor, 2 charging part, 3 exposure part, 4,4C, 4K, 4M, 4Y developing part, 5,18 cleaning blade, 6 intermediate transfer body contact roller, 7 sub-charging part, 8 lubricant supply part, 9 average Member, 10, 10C, 10K, 10M, 10Y Imaging unit, 12 Intermediate transfer belt, 14 Intermediate transfer body drive roller, 20 Transfer roller, 22 Fixing unit, 30 Paper feed unit, 32 Delivery roller, 34 Transport roller, 38 Transport Path, 50 control unit, 81 coating brush, 82 shaft member, 83 brushed, 84 solid lubricant, 100 image forming apparatus, 110 print engine, 120 document reading unit, 122 image scanner, 124 document feeding table, 126 automatic document feeding Device, 128 document discharge tray, 130 discharge tray.

Claims (18)

An image forming apparatus,
An image carrier;
Developing means for developing the electrostatic latent image formed on the image carrier as a toner image;
Transfer means for transferring the toner image to a transfer medium;
A cleaning member for recovering toner remaining on the image carrier after transfer;
Lubricant supply means for supplying a lubricant onto the image carrier;
Measuring means for measuring the torque required for rotational driving of the image carrier;
Control means capable of adjusting the amount of lubricant supplied to the image carrier, the control means,
A determination unit that determines whether the torque measured by the measurement unit is within a predetermined target range during a period in which the cleaning member is in contact with the image carrier while forming an image for a predetermined image;
When the measured torque exceeds the target range, the lubricant application conditions are changed so that the lubricant supplied to the image carrier is reduced, while the measured torque is the target. An image forming apparatus comprising: a changing unit that changes a coating condition of the lubricant so that the amount of the lubricant supplied to the image carrier increases when it is below the range.   The image forming apparatus according to claim 1, wherein the changing unit changes a coating condition of the lubricant by controlling a developing potential difference given by the developing unit.   The image forming apparatus according to claim 1, wherein the changing unit changes a coating condition of the lubricant by controlling a transfer potential difference given by the transfer unit.   The image forming apparatus according to claim 1, wherein the measuring unit measures the torque based on a current value of a motor that rotationally drives the image carrier.   5. The image formation according to claim 1, wherein the determination unit makes a determination using a torque measured in a state where at least one member other than the cleaning member is separated from the image carrier. 6. apparatus.   5. The determination unit according to claim 1, wherein the determination unit makes a determination using a torque measured in a state in which a member other than the cleaning member and the member constituting the developing unit is separated from the image carrier. 6. Image forming apparatus.   5. The image forming apparatus according to claim 1, wherein the determination unit makes a determination using a torque measured with a member other than the cleaning member being separated from the image carrier. 6. The image forming apparatus further includes a charging unit for charging the image carrier,
5. The image forming apparatus according to claim 1, wherein the determination unit makes a determination using a torque measured in a state where an output of charging by the charging unit is turned off.   The image forming apparatus according to claim 1, wherein the predetermined image is a white solid image.   10. The image according to claim 1, wherein the predetermined target range is determined based on a torque measured in an initial stage after replacement of at least one of the image carrier and the cleaning member. Forming equipment.   The predetermined target range is determined based on a torque when a variation rate of a measured torque converges to a predetermined range after replacement of at least one of the image carrier and the cleaning member. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the measurement unit outputs an average value obtained by measuring the torque of the image carrier over one round or more as a measurement value.   The image forming apparatus according to claim 1, wherein the measurement unit performs a torque measurement after performing a refresh mode for removing deposits on a surface of the image carrier.   The image forming apparatus according to claim 13, wherein the measurement unit performs a torque measurement after outputting a predetermined number of reference images after the refresh mode is performed.   The image forming apparatus according to claim 1, wherein the lubricant is added to toner.   The image forming apparatus according to claim 1, wherein the lubricant supply unit includes a mechanism for applying the lubricant independent of the developing unit. 17. The change means according to claim 1, wherein when the measured torque is within the target range, a condition for applying a lubricant to be supplied to the image carrier is maintained. Image forming apparatus. An image forming method in an image forming apparatus, wherein the image forming apparatus includes: an image carrier; a developing unit that develops an electrostatic latent image formed on the image carrier as a toner image; Transfer means for transferring to a transfer medium, a cleaning member for collecting toner remaining on the image carrier after transfer, a lubricant supply means for supplying a lubricant onto the image carrier, and rotation of the image carrier Measuring means for measuring torque required for driving, the image forming method,
Determining whether the torque measured by the measuring means is within a predetermined target range during a period in which the cleaning member is in contact with the image carrier while forming an image for the predetermined image;
When the measured torque exceeds the target range, the lubricant application conditions are changed so that the lubricant supplied to the image carrier is reduced, while the measured torque is the target. And a step of changing a lubricant application condition so that the amount of lubricant supplied to the image carrier increases when it is below the range.

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