JP2009204735A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus can suppress the occurrence of image deletion while securing convenience by shortening user's waiting time when performing a refresh mode. <P>SOLUTION: A control part 32 determines whether or not a printing request is made while performing the refresh mode, and interrupts the refresh mode and measurement of total performance time T when a printing instruction is input. After performing printing, the refresh mode and the measurement of the total performance time T are restarted, and the refresh mode is finished when the total performance time T achieves reference performance time T0 set in advance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using a photosensitive drum, and in particular, a method for polishing a surface of a photosensitive drum capable of suppressing image flow when an amorphous silicon (hereinafter referred to as a-Si) photosensitive drum is used. It is about.

  In recent years, an a-Si photosensitive drum has been widely used as an image carrier of an image forming apparatus using an electrophotographic process. The a-Si photoconductor drum has high hardness and excellent durability, and its characteristics as a photoconductor are hardly deteriorated even after long-term use. In addition, the image carrier is excellent in environmental safety.

  In an image forming apparatus using such an a-Si photosensitive drum, it is known that image flow tends to occur due to its characteristics. That is, when charging is performed using the charging unit, ozone is generated by discharging of the charging unit. The components in the air are decomposed by the ozone, and ion products such as NOx and SOx are generated. Since this ion product is water-soluble, it adheres to the photosensitive drum and enters into a roughness structure of about 0.1 μm on the surface of the photosensitive drum, so that it can be removed by a cleaning system used in a general-purpose machine. In addition, the resistance of the surface of the photosensitive drum is lowered by taking in moisture in the atmosphere. As a result, the lateral flow of the potential occurs at the edge portion of the electrostatic latent image formed on the surface of the photosensitive drum, and as a result, the image flow may occur.

  Conventionally, by putting a heater in the photosensitive drum, energy is given to release the moisture taken in by the ion product, and the resistance decrease on the surface of the photosensitive drum in a high humidity environment is suppressed. Already generalized. However, in such an apparatus, the number of parts for configuring the heater increases, a heater installation space is required, and power consumption increases, leading to an increase in the size and cost of the apparatus. In addition, it takes time for the surface of the photoreceptor to be heated to a predetermined temperature, which requires a long processing time and is not preferable from the viewpoint of safety.

In view of this, a method for reducing the image flow by suppressing a decrease in resistance on the surface of the photosensitive drum with a simple configuration has been proposed. Patent Documents 1 and 2 describe a developer (abrasive toner) mixed with an abrasive and an abrasive. A method of removing ozone products without using a heater or the like by executing a refresh mode in which a photosensitive member is polished by the interaction of members (a rubbing roller and a cleaning blade) at a predetermined timing is disclosed. In the above Patent Documents 1 and 2, the developer is printed or developed at the time of non-printing (when the apparatus is started up or in a standby mode after printing), and the polishing means in the photoreceptor unit is transferred without transferring the developer to the recording medium. To be used for polishing the surface of the photoreceptor.
Japanese Patent Laid-Open No. 10-63157 Japanese Patent Laid-Open No. 11-3014

  When a print request is made during execution of the refresh mode, if printing is prohibited until the refresh mode is completed, the user's print waiting time becomes longer and usability deteriorates. For this reason, the convenience of the user is ensured by usually interrupting the refresh mode and preferentially printing. However, when printing is prioritized, the refresh mode execution time is shorter than originally scheduled, so that there is a problem that the surface of the photosensitive drum is not sufficiently polished and the image flow is not eliminated.

  In view of the above problems, an object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of image flow while shortening the waiting time of the user when executing the refresh mode and ensuring convenience.

  To achieve the above object, the present invention provides an image carrier, developing means for forming a toner image corresponding to an electrostatic latent image by attaching a toner containing an abrasive to the surface of the image carrier, and the image carrier. A polishing member that is pressed against the surface of the body with a predetermined pressure and that polishes the surface of the image carrier, and supplies toner from the developing means to the image carrier side during non-image formation to remove the surface of the image carrier. In an image forming apparatus capable of executing a refresh mode for polishing, a refresh unit based on a measuring unit for measuring a total execution time per refresh mode, a total execution time measured by the measuring unit, and whether or not there is a print request Control means for determining whether to continue or suspend the printing, and when the printing request is made during execution of the refresh mode, the control means interrupts the refresh mode and performs printing. With rows, it is characterized by continuing the refresh mode after printing to resume the refresh mode until the total execution time reaches the reference execution time.

  Further, according to the present invention, in the image forming apparatus having the above configuration, when the total execution time is less than a predetermined time when the print request is made, the control unit performs printing until the total execution time reaches the predetermined time. It is characterized by delaying execution.

  According to the present invention, in the image forming apparatus having the above-described configuration, the control unit does not resume the refresh mode after the printing is completed when the total execution time is equal to or longer than a predetermined time when the printing request is made. .

  According to the first configuration of the present invention, when a print request is made during execution of the refresh mode, the refresh mode is temporarily interrupted to execute printing, and the refresh mode is resumed after printing is completed. It is possible to eliminate the problem and to ensure the convenience of the user. In addition, since the refresh mode is reliably executed for the reference execution time that was originally scheduled, it is possible to reliably prevent the occurrence of image flow in subsequent printing.

  Further, according to the second configuration of the present invention, in the image forming apparatus having the first configuration, since printing is not executed until the total execution time reaches a predetermined time, the image output during the execution of the refresh mode. Therefore, the waiting time of the user due to the execution of the refresh mode can be minimized while maintaining the quality of the image at a level at which image flow does not occur.

  According to the third configuration of the present invention, in the image forming apparatus having the first or second configuration, the refresh mode is not resumed when the total execution time at the end of printing reaches a predetermined time. Therefore, it is possible to eliminate the waiting time of the user due to resumption of the refresh mode while maintaining the image quality in the subsequent printing at a level at which no image flow occurs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus of the present invention, and FIG. 2 is a partial view showing in detail the periphery of the image forming unit in FIG. An image forming apparatus (here, a monochrome printer) 100 includes a photosensitive drum 1, a charging unit 2, an exposure unit 3, a developing unit 4, a transfer roller 5, a cleaning device 14, a toner storage unit 20, a sheet storage unit 21, and a conveyance unit 22. , A fixing unit 23, and a paper discharge unit 24.

  The photosensitive drum 1 is obtained by laminating a photosensitive layer made of a-Si or OPC (organic photosensitive layer) on an aluminum drum, and the surface of the photosensitive drum 1 is charged by a charging unit 2. Then, an electrostatic latent image in which charging is attenuated is formed on the surface that has received the laser beam from the exposure unit 3.

  The charging unit 2 charges the surface of the photosensitive drum 1 by discharging (for example, corona discharge). For example, the charging unit 2 is discharged by applying a high voltage using a thin wire or the like as an electrode. .

  The exposure unit 3 irradiates the photosensitive drum 1 with a light beam (for example, a laser beam) based on the image data to form an electrostatic latent image on the surface of the photosensitive drum 1. The developing unit 4 includes a developing roller 4a disposed so as to face the photosensitive drum 1, and a developer contained therein is attached to the electrostatic latent image on the photosensitive drum 1 by the developing roller 4a to form a toner image. It is something to be made.

  The cleaning device 14 includes a rubbing roller 6 which is a polishing system for polishing the photoconductor drum 1 and a cleaning blade 9. The rubbing roller 6 is pressed against the surface of the photoconductor drum 1 with a certain pressure by a spring (not shown). Has been.

  As is well known, an electrostatic latent image is recorded by the exposure unit 3 on the photosensitive drum 1 uniformly charged by the charging unit 2 after being neutralized by a static eliminating device (not shown), and the electrostatic latent image is inverted and developed. The developing unit 4 develops the toner image into a toner image, and the toner image is transferred onto the recording medium by the transfer roller 5. Untransferred toner that has not been transferred by the transfer roller 5 is removed as residual toner from the surface of the photosensitive drum 1 by the rubbing roller 6 and the cleaning blade 9, and the removed residual toner is discharged to a waste bottle (not shown) by the toner recovery device. Be transported.

  The toner storage unit (hopper) 20 supplies the developer to the development unit 4 and stores the developer when the developer (toner) in the development unit 4 becomes insufficient. The sheet storage unit 21 stores a sheet (paper, OHP, or the like) as a recording medium on which an image (toner image) is finally printed, and sends the sheet to the conveyance unit 22.

  The conveyance unit 22 is a sheet path from the sheet storage unit 21 to the paper discharge unit 24. The fixing unit 23 converts the toner image transferred onto the sheet into a stable permanent image. For example, the fixing unit 23 melts the toner image in a powder state by applying energy such as heat and pressure. The paper discharge unit 24 accommodates a sheet that has passed through the fixing unit 23, that is, a sheet on which a permanent image is printed and discharged to the outside of the apparatus.

  In addition, the image forming apparatus of the present invention develops in the developing unit 4 when the image forming apparatus is not transferred to a recording medium, for example, when the image forming apparatus is started up from a power-off state or a sleep (power saving) mode to a copy start state. A step of conveying the toner on the roller 4a to the photosensitive drum 1 side (hereinafter referred to as a toner supply step), and a toner conveyed to the photosensitive drum 1 side by the toner supply step is supplied to the rubbing roller 6 to supply the photosensitive member. A refresh mode including a step of polishing the surface of the drum 1 (hereinafter referred to as a polishing step) at least once each is configured to be executable.

  FIG. 3 is a side sectional view showing the configuration of the cleaning device. The cleaning device 14 removes residual toner on the surface of the photoconductive drum 1 and a housing 14a that forms an exterior having an opening toward the photoconductive drum 1, and slides the surface of the photoconductive drum 1 to rub it. A rubbing roller 6, a cleaning blade 9 for removing residual toner on the surface of the photosensitive member, a conveying spiral 25 as a toner discharging means, a scraper 26 for scraping off toner on the surface of the rubbing roller 6, and a housing 14a And a urethane seal 27 for preventing the waste toner from leaking to the outside.

  The rubbing roller 6 is pressed against the photosensitive drum 1 with a predetermined pressure, and is rotatably supported by front and rear side plates (not shown) of the housing 14a. The rubbing roller 6 is rotationally driven in the same direction on the contact surface with the photosensitive drum 1 by a driving means (not shown), but the peripheral speed is controlled to 1.2 times the peripheral speed of the photosensitive drum. . Examples of the rubbing roller 6 include a structure in which a foam layer made of EPDM rubber and having an Asuka C hardness of 55 ° is formed as a roller body around a metal shaft. The material of the roller body is not limited to EPDM rubber, but may be rubber or foam rubber body of other materials, and those having an Asuka C hardness in the range of 10 to 90 ° are preferably used. The rubbing roller 6 has not only a function of cleaning residual toner on the surface of the photosensitive drum 1 but also a function of polishing the surface of the drum by interposing a toner containing an abrasive with the photosensitive drum 1.

  Further, a scraper 26 is pressed in the counter direction with respect to the rotation direction on the surface of the rubbing roller 6 on the downstream side in the rotation direction from the contact surface with the photosensitive drum 1. The scraper 26 is, for example, an elastic plate made of SUS304 having a thickness of 0.02 to 2.0 mm, and its fixed end is attached to an attachment stay 28 attached to a front and rear side plate (not shown) of the housing 14a. The free end of the scraper 26 pressed against the rubbing roller 6 is positioned below the fixed end, and the toner scraped off from the rubbing roller 6 by the scraper 26 falls to the conveying spiral 25 side. Yes.

  Here, the attachment direction of the scraper 26 is the tangential direction at the pressure contact on the surface of the rubbing roller 6, but the present invention is not limited to this, and the pressure contact may have a predetermined angle with respect to the tangent. The material of the scraper 26 is not limited to weak magnetic SUS304, and nonmagnetic SUS plates, various resin, metal blade plates, rubber blade plates, and the like can be used.

The surface of the photosensitive drum 1 is fixed to the housing 14a via the mounting bracket 29 in a state where the cleaning blade 9 is in contact with the photosensitive drum 1 on the downstream side in the rotation direction from the contact surface with the rubbing roller 6. Has been. As the cleaning blade 9, for example, a polyurethane rubber cleaning blade having a JIS hardness of 78 ° is used, and is attached at a predetermined angle with respect to the tangential direction at a contact point with the photosensitive drum 1. The pressure contact force of the cleaning blade 9 to the photosensitive drum 1 side is set to about 5 g / mm ² , for example. Note that the material, hardness, dimensions, the amount of biting into the photosensitive drum 1, the pressure contact force, and the like of the cleaning blade 9 are appropriately set according to the specifications of the photosensitive drum 1.

  Further, a urethane seal 27 is attached to the side plate of the housing 14a located on the upstream side in the rotation direction of the photosensitive drum 1 (left side in the drawing) so as to make an acute angle with respect to the tangent at the contact point with the photosensitive drum 1. Yes.

  Residual toner removed from the surface of the photosensitive drum 1 by the rubbing roller 6 and the cleaning blade 9 moves upward and is discharged to the outside of the cleaning device 14 as the conveying spiral 25 rotates. As the toner used in the present invention, silica, titanium oxide, strontium titanate, alumina or the like is embedded in the toner particle surface as an abrasive and held so as to partially protrude on the surface. Those that are electrostatically attached to the surface are used.

  FIG. 4 is a schematic diagram illustrating a state in which the image forming unit of the image forming apparatus of the present invention is in each process during the refresh mode. Here, a case where positively charged toner is used is described, and description of the charging unit 2 and the exposure unit 3 is omitted. FIG. 4A shows a state where the image forming unit is in the toner supply process. In the toner supplying step, a developing bias having the same polarity (positive) as that of the toner is applied to the developing roller 4a in the developing unit 4 so that the toner used for polishing the surface of the photosensitive drum 1 is transferred from the developing unit 4 to the photosensitive drum 1. Supply to the side.

  The toner is supplied to the photosensitive drum 1 by exposing the entire drum surface uniformly charged by the charging unit 2 by the exposure unit 3 and applying a developing bias having the same polarity (positive) as the toner to the developing roller 4a. It can be performed by a normal development process (jumping development system) in which toner is allowed to fly on the drum surface.

  FIG. 4B shows a state where the toner supplied to the drum surface in the toner supply process reaches the rubbing roller 6 and the polishing process is started. In the polishing step, after supplying toner onto the photosensitive drum 1 in the toner supply step, the surface of the photosensitive drum 1 is polished by rotating the rubbing roller 6 with respect to the photosensitive drum 1 with a speed difference. This is a process for removing moisture and contaminants on the drum surface together with the toner. In addition, while supplying toner to the rubbing roller 6, a bias voltage having the same polarity (positive) as that of the toner is applied to the transfer roller 5 so that the toner does not adhere to the transfer roller 5.

  FIG. 4C shows a state where the toner supply process is completed during the polishing process. In the polishing process, even after the supply of toner from the developing roller 4a is stopped, the photosensitive drum 1 and the rubbing roller 6 continue to rotate for a while.

  The toner supply process and the polishing process shown in FIG. 4 are repeated once or a plurality of times, and the refresh mode is executed for a preset time (hereinafter referred to as a reference execution time) to thereby remove impurities on the surface of the photosensitive drum 1. An effective polishing system that can be removed in a short time, effectively prevents image flow over a long period of time, and makes the amount of polishing of the photosensitive layer on the drum surface constant. The reference execution time is appropriately set according to the configuration of the photosensitive layer to be used, the use environment of the apparatus, the execution interval of the refresh mode, and the like.

  FIG. 5 is a block diagram showing an example of a control path in the image forming apparatus of the present invention. The image forming apparatus 100 includes an image forming unit 15, an image input unit 31, a control unit 32, an operation panel 33, a temperature / humidity sensor 34, a storage unit 35, and a timer 36.

  When the image forming apparatus 100 is a copying machine, the image input unit 31 includes a scanning optical system equipped with a scanner lamp that illuminates the document during copying and a mirror that changes the optical path of reflected light from the document, and reflected light from the document. 1 is a printer such as that shown in FIG. 1, in which the image forming apparatus 100 includes a condensing lens that collects and forms an image and a CCD that converts the imaged image light into an electrical signal. In this case, the receiving unit receives image data transmitted from a personal computer or the like.

  The image signal read by the image input unit 31 is sent to the control unit 32, and image processing such as gradation processing is appropriately performed to convert the image signal into image data. The image forming unit 15 includes a photosensitive drum 1, a charging unit 2, an exposure unit 3, a developing unit 4, a transfer roller 5, a cleaning device 14, and the like, and is based on image data converted by the control unit 32. A latent image is formed on the drum 1, and after development, the toner image is transferred onto the sheet. The control unit 32 also controls each part of the image forming apparatus such as the image input unit 31 and the image forming unit 15 according to the set program.

  The operation panel 33 includes operation keys for the user to set device functions, printing conditions, and the like, and a display unit (none of which is shown) that displays the setting conditions, device states, and the like. The temperature / humidity sensor 34 constantly detects the humidity outside the apparatus every predetermined time, and the detected humidity is sent to the control unit 32. Based on the temperature and humidity outside the apparatus detected by the temperature / humidity sensor 34, the control unit 32 performs the refresh mode execution time, and the bias voltage applied to the developing roller 4a (see FIG. 1) and the transfer roller 5 in the developing unit 4. And the refresh mode is controlled.

  The refresh mode control is preferably performed using the detection value immediately before, but may be controlled using humidity detected at another timing. It is also possible to detect the temperature and humidity a predetermined number of times and use the average value of the detected values. The temperature / humidity sensor 34 is installed, for example, above the sheet storage unit 21 (see FIG. 1). However, the temperature / humidity sensor 34 may be installed in another place where the humidity outside the apparatus can be accurately detected.

  The storage unit 35 stores a control program for each unit used by the control unit 32. When the refresh mode execution time is changed according to the temperature and humidity detected by the temperature / humidity sensor 34, the number of times the refresh mode is repeated corresponding to the temperature and humidity (reference execution time) is also stored. The timer 36 measures the total execution time from the start to the end of the refresh mode.

  FIG. 6 is a flowchart showing a first control example of the refresh mode implemented in the image forming apparatus of the present invention. The refresh mode execution procedure will be described with reference to FIGS. When the image forming apparatus is turned on, in the sleep (power saving) mode, or when the refresh mode is started by setting by the user (step S1), measurement of the total execution time T of the refresh mode is also started by the timer 36 (step S1). Step S2).

  When the refresh mode is executed, the control unit 32 determines whether a print request is made during the execution of the refresh mode (step S3). When a print command is input from the operation panel 33, the toner supply from the developing roller 4a to the photosensitive drum 1 is stopped and the refresh mode is interrupted (step S4). At this time, the measurement of the total execution time T by the timer 36 is also interrupted at the same time. Then, a toner image corresponding to the image data is formed on the photosensitive drum 1 and printing is executed (step S5).

  Thereafter, when the printing is completed, the refresh mode is resumed (step S6), and the measurement of the total execution time T by the timer 36 is also resumed. The total execution time T is continuously measured from the time when the refresh mode is interrupted. On the other hand, if there is no print request in step S3, the refresh mode is continued as it is. Then, it is determined whether or not the total execution time T has reached a preset reference execution time T0 (step S7). When T = T0, the refresh mode is terminated. If T <T0, the process returns to step S2 again. If a print request is made, the same procedure is performed (steps S3 to S7).

  According to the above procedure, when a print request is made during execution of the refresh mode, the refresh mode is temporarily suspended and printing is performed. After the printing is completed, the refresh mode is resumed. Can be secured. In addition, regardless of whether or not printing is performed, since the reference execution time originally scheduled as the total execution time of the refresh mode is secured, it is possible to reliably prevent the occurrence of image flow in subsequent printing.

  FIG. 7 is a flowchart showing a second control example of the refresh mode implemented in the image forming apparatus of the present invention. In the second control example, when a print request is made during execution of the refresh mode (YES in step S3), it is determined whether or not the total execution time T measured by the timer 36 is equal to or longer than the predetermined time T1. Judgment is made (step S4). If T <T1, the interruption of the refresh mode and the execution of printing are delayed until T reaches T1. The other steps are the same as in the first control example of FIG.

  In the first control example shown in FIG. 6, when a print request is made immediately after the start of the refresh mode, printing is executed with insufficient polishing of the photosensitive drum 1, so that an image is output on the output image. There was a risk of flow. On the other hand, in the second control example, printing is not executed until the total execution time T reaches a predetermined time T1 at which no image flow occurs, so the quality of the image output during execution of the refresh mode is maintained. In addition, the waiting time of the user due to the execution of the refresh mode can be minimized.

  The predetermined time T1 may be set to a minimum time during which no noticeable image flow occurs. However, since the degree of image flow varies depending on the resolution and gradation, the image quality set by the operation panel 33 is set. It may be possible to change it according to. For example, when the character mode (low gradation mode) is set as the print mode, the refresh execution time may be set to T1 so that the halftone image is blurred and thinned but the characters are not blurred.

  FIG. 8 is a flowchart showing a third control example of the refresh mode implemented in the image forming apparatus of the present invention. In the third control example, when a print request is made during execution of the refresh mode and T ≧ T1 (YES in steps S3 and S4), after the refresh mode is interrupted and printing is performed (step S6), It is determined whether or not the total execution time T measured by the timer 36 is equal to or longer than the predetermined time T2 (step S7). If T ≧ T2, the process is terminated without restarting the refresh mode. The other steps are the same as in the second control example in FIG.

  In the first and second control examples, even when a print request is made immediately before the end of the refresh mode, the refresh mode is resumed after the end of printing, so that there is a possibility that the waiting time of the user becomes long. On the other hand, in the third control example, after completion of printing during the execution of the refresh mode, the refresh mode is not resumed when the total execution time T up to that point has reached a predetermined time T2 at which image quality can be maintained. Therefore, the waiting time of the user due to the restart of the refresh mode can be eliminated. The predetermined time T2 may be set to a minimum time during which no significant image flow occurs until the next refresh mode is executed. Further, it may be changed according to the set image quality in the same manner as the predetermined time T1.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the reference execution time (the number of repetitions) in the refresh mode is changed based on the temperature and humidity outside the apparatus detected by the temperature / humidity sensor 34, but based on either temperature or humidity. Can also be changed. Further, the temperature and humidity around the photosensitive drum may also be detected and the reference execution time may be changed based on the temperature and humidity difference from the outside of the apparatus. Further, the refresh mode may be automatically started according to the temperature / humidity detected by the temperature / humidity sensor 34 or the number of printed sheets since the previous refresh mode execution.

  Further, the present invention is not limited to the monochrome printer as shown in FIG. 1, and includes a photosensitive drum such as a tandem or rotary color copier and printer, a monochrome copier, a digital multifunction machine, a facsimile machine, or the like. Of course, the present invention can be applied to various image forming apparatuses.

  The image flow prevention performance in the refresh mode executed in the image forming apparatus of the present invention was evaluated. As an evaluation method, using a testing machine (KM-2550 manufactured by Kyocera Mita Co., Ltd.), after printing 20,000 test images with a printing rate of 6%, the power is turned off and high temperature and high humidity conditions (32.5 ° C. , 80% RH) for 8 hours. Thereafter, the power was turned on again, and a test image print request was input after 3 minutes during the 6-minute refresh mode.

  When the first control example shown in FIG. 6 is used, the refresh mode is interrupted to execute printing, the refresh mode is executed again for 3 minutes after the end of printing, and the present invention does not resume the refresh mode after the end of printing. In the case of Comparative Example 1 and the case where printing was executed after the 6-minute refresh mode was completed, Comparative Example 2 was used, and the image flow level was visually evaluated. In the present invention and Comparative Example 1, a test image was printed after 6 minutes to confirm the image flow level. Further, the image flow level was evaluated in the same manner as a control example in which printing was performed without executing the refresh mode. The image flow level was evaluated on a three-point scale, with ◯ when no image flow occurred, △ when characters were not blurred but the halftone image was thin, and X when characters were blurred as well as halftone. .

  As test conditions, an a-Si photosensitive drum with a diameter of 30 mm and a rubbing roller with a diameter of 14 mm were used, the drum rotation speed was 100 mm / sec (one drum in about 1 second), and the rubbing roller and the photosensitive drum The speed ratio was + 20%. The developing method used magnetic jumping development, and during execution of the refresh mode, a 20 mm toner band was developed on the drum surface every 30 seconds and the toner was supplied to the rubbing roller. Further, a positively chargeable magnetic one-component toner having an average particle size of 9 μm and containing 0.6% by weight of silica and 1.4% by weight of titanium oxide was used as an abrasive. The results are shown in Table 1.

  As shown in Table 1, in the present invention, in which the refresh mode is again executed for 3 minutes after 3 minutes have elapsed from the start of the refresh mode, the refresh mode for a total of 6 minutes is ensured before and after the printing. In the printing after the lapse of minutes, the halftone image was not thinned and the image flow was completely eliminated. In addition, even after 3 minutes of printing, although the image flow to such an extent that the halftone image becomes thin was confirmed, there was no bleeding of characters, and it was at a level that did not hinder normal character printing.

  On the other hand, in the comparative example 1 in which the refresh mode is not restarted after printing is performed after 3 minutes have elapsed since the start of the refresh mode, the total refresh execution time is 3 minutes. There was almost no change, and an image flow in which the halftone image became thin was generated. In Comparative Example 2 in which printing is performed after the end of the 6-minute refresh mode, the image flow is completely eliminated, but a waiting time of 3 minutes is generated from the print request, which is not satisfactory in terms of convenience. In the control example in which the printing was performed without executing the refresh mode, the image flow was considerably strong, and not only the halftone image but also the characters were blurred.

  From this result, it was confirmed that the present invention can effectively prevent image flow without deteriorating the convenience of the image forming apparatus. Although not shown here, when the second and third control examples for determining the printing timing during execution of the refresh mode and the necessity of restarting the refresh mode using the predetermined times T1 and T2, the convenience of the apparatus is used. It has been confirmed that more favorable results can be obtained with respect to the property and the effect of preventing image drift.

  The present invention includes an image carrier, development means for forming a toner image corresponding to an electrostatic latent image by attaching a toner containing an abrasive to the surface of the image carrier, and pressing the surface of the image carrier with a predetermined pressure. And a polishing member that polishes the surface of the image carrier, and is capable of executing a refresh mode that polishes the surface of the image carrier by supplying toner from the developing means to the image carrier side during non-image formation. Measuring means for measuring the total execution time per refresh mode, and control means for determining continuation and interruption of the refresh mode based on the total execution time measured by the measurement means and the presence or absence of a print request. When a print request is made during execution of the refresh mode, the control means interrupts the refresh mode and executes printing, and restarts the refresh mode after printing is completed. The total execution time is to continue the refresh mode until it reaches the reference execution time by.

  As a result, it is possible to provide an image forming apparatus that can immediately respond to a print request during execution of the refresh mode and can reliably suppress the occurrence of image flow after the execution of the refresh mode.

  Also, if the control that does not respond to the print request until the total execution time of the refresh mode reaches a predetermined time, the quality of the image output during the execution of the refresh mode and the shortening of the print waiting time are considered in a balanced manner. In addition, the image forming apparatus is more convenient.

  If the total execution time at the end of printing has reached a predetermined time, control that does not resume the refresh mode allows for a good balance between maintaining image quality and reducing print waiting time in subsequent printing. In addition, the image forming apparatus is more convenient.

FIG. 1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus of the present invention. FIG. 2 is a partially enlarged view around the image forming unit in FIG. 1. FIG. 3 is a side sectional view showing the configuration of the cleaning device. FIGS. 4A and 4B show the periphery of the photosensitive drum showing the toner supply process (FIG. 4A), the polishing process (FIG. 4B), and the polishing process (FIG. 4C) after the toner supply process is completed in the refresh mode. FIG. FIG. 3 is a block diagram showing a control path of the image forming apparatus of the present invention. These are the flowcharts which show the 1st example of control of the refresh mode implemented in the image forming apparatus of this invention. These are the flowcharts which show the 2nd control example of the refresh mode implemented in the image forming apparatus of this invention. These are flowcharts showing a third control example of the refresh mode implemented in the image forming apparatus of the present invention.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Charging unit 3 Exposure unit 4 Development unit (development means)
4a Developing roller 5 Transfer roller 6 Rub roller (abrasive member)
9 Cleaning blade (abrasive member)
DESCRIPTION OF SYMBOLS 14 Cleaning apparatus 15 Image formation part 25 Conveyance spiral 26 Scraper 31 Image input part 32 Control part (control means)
34 Temperature / Humidity Sensor 35 Storage Unit 36 Timer (Measurement Means)
100 Image forming apparatus

Claims (3)

An image carrier, a developing means for forming a toner image corresponding to the electrostatic latent image by attaching a toner containing an abrasive to the surface of the image carrier, and being pressed against the surface of the image carrier at a predetermined pressure A polishing member for polishing the surface of the image carrier,
In an image forming apparatus capable of executing a refresh mode in which toner is supplied from the developing unit to the image carrier side during non-image formation to polish the surface of the image carrier.
Measuring means for measuring the total execution time per refresh mode;
Control means for determining continuation and interruption of the refresh mode based on the total execution time measured by the measurement means and the presence or absence of a print request; and
When a print request is made during execution of the refresh mode, the control means interrupts the refresh mode and executes printing, and restarts the refresh mode after printing is completed until the total execution time reaches the reference execution time. An image forming apparatus characterized by continuing a refresh mode.   2. The control unit according to claim 1, wherein when the total execution time is less than a predetermined time at the time when the print request is made, the control unit delays the execution of printing until the total execution time reaches the predetermined time. The image forming apparatus described.   3. The image forming apparatus according to claim 1, wherein the control unit does not resume the refresh mode after the printing is completed when the total execution time is equal to or longer than a predetermined time when the printing request is made. .

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