JP2018163257A - Image forming apparatus and image forming program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a deterioration in an image carrier in comparison with a case of stopping charging by a charging roll without considering a relation between a stop period of discharging by a discharge part and a stop period of charging by the charging roll.SOLUTION: A discharge lamp is switched from ON to OFF at a timing of a time (t1), and the discharge lamp is turned off during a first predetermined time (T1). The charging of a charging roll is turned off at a timing of a time (t3) of a second predetermined time (T2) before a timing of a time (t2) when a surface position of a photoreceptor drum when the discharge lamp is turned off at the timing of the time (t1) reaches a position where the photoreceptor drum is charged by the charging roll. Thus, a discharged and uncharged potential portion is formed on a surface portion of the photoreceptor drum, and toner is shifted such that the toner can be supplied to a blade of a drum cleaner, and that surface abrasion of the photoreceptor drum can be suppressed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus and an image forming program.

  In an image forming apparatus using an electrophotographic system, charge removal of an image carrier such as a photoconductor is performed, and after residual toner is removed, the image carrier is charged by a charging roll or the like. The surface is exposed by an exposure device to form an electrostatic latent image, and the electrostatic latent image on the image carrier is developed by a developing device having a developing roll. Then, transfer from the image carrier to the intermediate transfer member, the recording medium, or the like is performed, and the toner remaining on the image carrier without being transferred is removed again by the image carrier remover.

  When the image bearing member is charged using the charging roll, the toner that has passed through without being removed by the removing unit and the external additive of the toner may adhere to the charging roll. In order to suppress contamination due to adhesion of the toner and toner external additives to the charging roll, the charge of the image carrier and the voltage of the charging roll are set so that the voltage of the charging roll is lower than the surface potential of the image carrier. (See, for example, Patent Document 1). In Patent Document 1, after neutralization by the neutralization unit is turned off, charging by the charging roll is turned off after the part of the image carrier from which static elimination has been turned off reaches the part where charging is started by the charging roll.

JP 2007-171380 A

By the way, when the removal unit is slidably contacted with the image carrier and the residual toner is removed by the mechanical pressure force and electrostatic attraction force generated between the removal unit and the image carrier, the charge removal unit is turned off. Deterioration such as wear of the image carrier may occur with time.
The present invention suppresses the deterioration of the image carrier as compared with the case where the charging by the charging roll is stopped without considering the relationship between the timing of stopping the discharging by the discharging section and the timing of stopping the charging by the charging roll. An object of the present invention is to provide an image forming apparatus and an image forming program.

  According to the first aspect of the present invention, there is provided a charging roll for charging an image carrier, an exposure unit for exposing a charged part of the image carrier, a developing roll for developing the exposed part of the image carrier with toner, and transferring from the image carrier. An image forming apparatus comprising: a transfer unit that transfers a toner image to a medium; a neutralization unit that neutralizes the image carrier after transfer of the transfer unit; and a removal unit that removes residual toner remaining on the image carrier. After removing the residual toner remaining on the image carrier after the transfer of the transfer unit, the position where the charge removal is started in the removal unit passes through the charging roll and the position where the charge removal is stopped reaches the charging roll. A controller that controls charging to stop at a variable timing before the toner image is applied, and to remove the toner adhering to the image carrier after the toner is adhered to the image carrier from the developing roll without exposure. Prepare.

  According to a second aspect of the present invention, the timing at which the charging is stopped is changed so that the neutralized region remaining when the charging is stopped becomes a target size.

  According to a third aspect of the invention, the timing for stopping the charging is changed according to at least one of an environmental condition and a toner amount when developed by the developing roll.

  The invention according to claim 4 is modified such that as at least one of the environmental temperature and the environmental humidity increases, the area of charge removal remaining when the charging is stopped increases.

  According to a fifth aspect of the present invention, as the amount of toner at the time of development with the developing roll increases, the area of charge removal remaining when the charging is stopped is changed so as to increase.

  According to a sixth aspect of the invention, the timing at which the timing is variable is after the timing at which neutralization of the image carrier is stopped, and the position of the image carrier at which neutralization of the image carrier is stopped is at the charging roll. It is assumed that the timing is a predetermined time that can be varied from the time at which the signal reaches.

  According to a seventh aspect of the invention, the controller controls the neutralization unit so that the neutralization of the image carrier is stopped for a first predetermined time from the first timing when the neutralization is stopped by the removal unit. And a third timing before the second timing from the second timing after the first timing and when the position where the charge removal is stopped by the removing unit passes through the charging roll and reaches the charging roll. The charging roll is controlled so that charging of the image carrier is stopped for a variable second predetermined time until timing.

  In the invention of claim 8, the first predetermined time is lengthened as at least one of the environmental temperature and the environmental humidity increases.

  According to a ninth aspect of the present invention, the first predetermined time is lengthened as the cumulative amount of toner attached to the image carrier by the developing roll increases.

  In a tenth aspect of the present invention, the second predetermined time is increased as the first predetermined time is increased.

  An image forming program according to an invention of claim 11 includes a charging roll for charging the image carrier, an exposure unit for exposing a charged part of the image carrier, a developing roll for developing the exposed part of the image carrier with toner, and development. The transfer unit of the image forming apparatus, comprising: a transfer unit that transfers the toner image, a neutralization unit that neutralizes the image carrier after the transfer of the transfer unit, and a removal unit that removes residual toner remaining on the image carrier After removing the residual toner remaining on the image carrier after the transfer of the toner, the position where the charge removal is started passes through the charging roll, and the position where the charge removal is stopped is before the charge roll is reached and the timing is variable. The charging process is stopped at this timing, and after the toner adhering to the developing roll without being exposed is adhered to the image carrier, the control is performed to remove the toner adhering to the image carrier. To be executed by a computer.

  According to the present invention, the deterioration of the image carrier is suppressed as compared with the case where the charging by the charging roll is stopped without considering the relationship between the timing of stopping the discharging by the discharging section and the timing of stopping the charging by the charging roll. be able to.

1 is a configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. 1 is a configuration diagram illustrating an example of an image forming unit according to an embodiment of the present invention. 6 is a timing chart showing an example of the relationship between the surface potential of the photosensitive drum, the on / off of the charge removal lamp, and the potential of the charging roll when cleaning the charging roll. 6 is a timing chart showing an example of the relationship between the surface potential of the photosensitive drum, the on / off of the charge removal lamp, and the potential of the charging roll when suppressing surface abrasion of the photosensitive drum. 2 is a block diagram illustrating an example of a configuration of a control unit of the image forming apparatus. FIG. It is a flowchart which shows an example of the flow of the process performed with the computer which operate | moves as a control part.

  Hereinafter, an example of an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is provided to the component and process which an effect | action and a function bear the same function through all drawings, and the overlapping description may be abbreviate | omitted suitably.

FIG. 1 is a schematic side view showing a main configuration of an image forming apparatus 10 using an electrophotographic system according to this embodiment. The image forming apparatus 10 has an image forming function for receiving various data via a communication line (not shown) and performing color image forming processing based on the received data.
An image forming apparatus 10 shown in FIG. 1 is a so-called tandem color printer, and includes an image forming unit 19 that forms an image based on image data, a fixing device 50, a control unit 31 that controls the operation of the entire image forming apparatus 10, and the like. It has. In addition, for example, a communication unit 32 that receives image data by communicating with a personal computer (PC) 3 or an image reading device (scanner) 4, and a predetermined image for the image data received by the communication unit 32. An image processing unit 33 that performs processing is provided.

  The image forming unit 19 includes four image forming units 11Y, 11M, 11C, and 11K that are arranged in parallel at regular intervals. These four image forming units 11Y, 11M, 11C, and 11K have substantially the same configuration except for toner stored in a developing unit 15 described later, and each of them has yellow (Y), magenta (M), and cyan (C ), A black (K) toner image is formed. In the following description, when it is necessary to distinguish Y, M, C, and K, any one of Y, M, C, and K is added after the reference symbol, and Y, M, C And Y, M, C, and K are omitted when it is not necessary to distinguish between K and K.

  FIG. 2 is a schematic cross-sectional side view showing the main configuration of each image forming unit 11 of the image forming unit 19 in the image forming apparatus 10 according to the present embodiment.

  As shown in FIG. 2, the image forming unit 11 includes a photosensitive drum 12 that rotates in the direction of arrow A, which is an example of an image carrier that forms an electrostatic latent image and holds a toner image, and a charger 13. ing. The charger 13 includes a charging roll 130 that uniformly charges the surface of the photosensitive drum 12 with a predetermined potential. The charging roll 130 is pressed against the photosensitive drum 12 by an urging mechanism (not shown), and rotates following the photosensitive drum 12. The charging roll 130 is provided with a charging roll cleaner 132. The charging roll cleaner 132 is urged to the peripheral surface of the charging roll 130 by an urging mechanism (not shown), and is rotated by the charging roll 130 and adheres to the peripheral surface of the charging roll 130, such as toner and external toner additives. Scrape off foreign material and clean.

  On the upstream side of the charger 13 (upstream side of the photosensitive drum 12 rotating in the direction of arrow A), a drum cleaner 16 and a charge eliminating lamp 17 for cleaning the surface of the photosensitive drum 12 after transfer (reverse to the direction of arrow A). In the direction). The drum cleaner 16 includes a blade 160 and a toner recovery bottle 162. The blade 160 scrapes off the waste toner on the surface of the photosensitive drum 12. The toner collection bottle 162 collects the toner scraped by the blade 160. The neutralization lamp 17 neutralizes the surface of the photosensitive drum 12.

  On the other hand, on the downstream side of the charger 13 (downstream side of the photosensitive drum 12 rotating in the direction of arrow A), an LED (Light Emitting Diode) print head 14 and a developing unit 15 are provided in order (in the direction of arrow A). Yes. The LED print head 14 forms an electrostatic latent image on the photosensitive drum 12 by exposing the photosensitive drum 12 charged by the charger 13 based on each color image data.

  The developing device 15 develops the electrostatic latent image formed on the photosensitive drum 12. The developing device 15 includes a developing roll 150 that attaches toner to the surface of the photosensitive drum 12. The developing roller 150 is pressed against the photosensitive drum 12 by an urging mechanism (not shown), and rotates following the photosensitive drum 12. The toner stored in the toner storage unit 152 is supplied to the developing roll 150.

  Further, on the downstream side of the developing device 15 (downstream side of the photosensitive drum 12 rotating in the direction of arrow A), the primary transfer roll 21 included in the transfer unit that transfers the toner image formed on the photosensitive drum 12. Is provided.

  As shown in FIG. 1, the image forming unit 19 is formed by the intermediate transfer belt 20 to which the color toner images formed on the photoconductive drums 12 of the image forming units 11 are transferred and the image forming units 11. In addition, primary transfer rolls 21Y, 21M, 21C, and 21K that sequentially transfer (primary transfer) each color toner image to the intermediate transfer belt 20 are provided. Further, a secondary transfer roll 22 is provided which collectively transfers (secondary transfer) each color toner image transferred superimposed on the intermediate transfer belt 20 onto a sheet P which is an example of a recording medium. The fixing device 50 fixes each color toner image secondarily transferred to the paper P onto the paper P.

  In the image forming apparatus 10 of the present embodiment, the intermediate transfer belt 20, the primary transfer roll 21, and the secondary transfer roll 22 constitute a transfer unit.

  In the image forming apparatus 10 of the present embodiment, under the operation control by the control unit 31, for example, an image forming process is performed by the following process.

  That is, image data from the PC 3 or the scanner 4 is received by the communication unit 32 and subjected to predetermined image processing by the image processing unit 33, and then becomes image data for each color to each image forming unit 11. Sent. For example, in the image forming unit 11K that forms a black (K) color toner image, the photosensitive drum 12 is charged to a predetermined potential by the charger 13 while rotating in the direction of arrow A. The charged photosensitive drum 12 is scanned and exposed by the LED print head 14 based on the K color image data transmitted from the image processing unit 33, thereby forming an electrostatic latent image of the K color image on the photosensitive drum 12. Is done.

  The K-color electrostatic latent image formed on the photosensitive drum 12 is developed by the developing device 15, and a K-color toner image is formed on the photosensitive drum 12. Similarly, yellow (Y), magenta (M), and cyan (C) toner images are formed in the image forming units 11Y, 11M, and 11C, respectively.

  Each color toner image formed on the photosensitive drum 12 of each image forming unit 11 is sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 20 that moves in the direction of arrow B by the primary transfer roll 21, and each color toner is superimposed. A superimposed toner image is formed. The superimposed toner image on the intermediate transfer belt 20 is conveyed to a region (secondary transfer portion T) where the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves. When the superimposed toner image is conveyed to the secondary transfer unit T, the paper P is supplied from the paper holding unit 40 to the secondary transfer unit T by the paper supply unit 64 in accordance with the timing. The superimposed toner image is collectively electrostatically transferred (secondary transfer) onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 22 in the secondary transfer portion T.

  Thereafter, the sheet P on which the superimposed toner image is electrostatically transferred is conveyed to the fixing device 50. The toner image on the paper P conveyed to the fixing device 50 receives heat and pressure when passing through the fixing device 50 and is fixed on the paper P. Then, the sheet P on which the fixed image is formed is discharged to the discharge unit 30 by the sheet discharge unit 66 of the image forming apparatus 10.

  On the other hand, toner (secondary transfer residual toner) adhering to the intermediate transfer belt 20 after the secondary transfer is removed by the belt cleaner 25. The photosensitive drum 12 after the primary transfer is neutralized by the static elimination lamp 17, and the toner (primary transfer residual toner) adhering to the photosensitive drum 12 after the primary transfer is removed by the drum cleaner 16.

  In this manner, the image forming process in the image forming apparatus 10 is repeatedly executed for the number of printed sheets.

  By the way, in the charging roll 130, surface contamination in which foreign matters such as toner and external additives adhere to the surface may occur. For example, when the charging roll cleaner 132 is made of foamed urethane rubber, which is a porous elastic body, and configured to scrape off foreign matters such as toner and external additives, the foreign matter may be accumulated in the charging roll cleaner 132. is there. The accumulated foreign matter may be discharged from the charging roll cleaner 132 and attached to the charging roll 130, causing surface contamination of the charging roll 130 in some cases.

  Therefore, in order to suppress surface contamination of the charging roll 130, the charging roll 130 is cleaned. In the present embodiment, the control unit 31 (see FIG. 1) controls on / off of light irradiation of the static elimination lamp 17 so that the foreign matter attached to the charging roll 130 is transferred to the photosensitive drum 12 and is collected by the drum cleaner 16. Perform cleaning.

  FIG. 3 is a timing chart showing the relationship between the surface potential of the photosensitive drum 12, the on / off of the charge removal lamp 17, and the potential of the charging roll 130 when the charging roll 130 is cleaned. In the example illustrated in FIG. 3, the potential relationship is −V1 <−V2 <−V3.

  As shown in FIG. 3, at the timing of time t1, the light irradiation of the static elimination lamp 17 is switched from on to off, and the static elimination lamp 17 is turned off for the first predetermined time T1. Further, the charging roll 130 is at the timing t2 (= t1 ′) when the surface position of the photosensitive drum 12 reaches the position charged by the charging roll 130 when the static elimination lamp 17 is turned off at the timing t1. Turn off the charging. By doing so, during the first predetermined time T1, the surface of the photosensitive drum 12 is not neutralized by turning off the neutralizing lamp 17, and is not charged by the charging roll 130, that is, the previously charged residual potential. Is included in a period corresponding to the period Tx (= T1) in which is maintained. In the portion where the residual potential is maintained, the foreign matter attached to the charging roll 130 is transferred to the photosensitive drum 12. The foreign matter transferred to the photosensitive drum 12 is collected by the drum cleaner 16.

  However, the surface wear of the photosensitive drum 12 by the blade 160 of the drum cleaner 16 increases as the first predetermined time T1 for turning off the static elimination lamp 17 in order to improve the performance of suppressing the surface contamination of the charging roll 130 is increased. . The surface wear of the photosensitive drum 12 causes the image quality of the image formed by the image forming unit 11 to deteriorate.

  Therefore, in this embodiment, in order to suppress the surface wear of the photosensitive drum 12, the toner is applied to the blade 160 of the drum cleaner 16 by controlling the on / off of the static elimination lamp 17 and the on / off of the charging roll 130. Supply.

  FIG. 4 is a timing chart showing the relationship between the surface potential of the photosensitive drum 12, the on / off state of the charge removal lamp 17, and the potential of the charging roll 130 when suppressing surface wear of the photosensitive drum 12.

  As shown in FIG. 4, at the timing of time t1, the light irradiation of the static elimination lamp 17 is switched from on to off, and the static elimination lamp 17 is turned off for the first predetermined time T1. Further, the second predetermined timing is determined from the timing of time t2 (= t1 ′) when the surface position of the photosensitive drum 12 reaches the position charged by the charging roll 130 when the static elimination lamp 17 is turned off at the timing of time t1. Charging of the charging roll 130 is turned off at the timing of time t3 before time T2. By doing so, a portion of the surface of the photosensitive drum 12 where the electric potential is maintained without being charged and charged for the second predetermined time T2 before the period Tx during which the residual potential is maintained. Is formed on the surface of the photosensitive drum 12. That is, a static-removed area remaining when charging is stopped is formed on the surface of the photosensitive drum 12.

  During the second predetermined time T2, when the surface portion of the photosensitive drum 12 that has been neutralized and is not charged is maintained, reaches the position where the developing device 15 develops the toner, the toner is transferred to the photosensitive drum 12. The drum cleaner 16 is reached by the rotation of the photosensitive drum 12. As described above, by supplying the toner to the blade 160 of the drum cleaner 16, it is possible to suppress the surface wear of the photosensitive drum 12.

  The timing of the above-described time t3 is a timing with variable timing, and the timing can be changed. That is, the timing of time t3 is changed by changing the second predetermined time T2. Although details will be described later, the control unit 31 performs control so that the second predetermined time T2 becomes a predetermined standard time as a target.

  It should be noted that the surface contamination of the charging roll 130 described above varies depending on the usage environment such as the temperature and humidity when the image forming apparatus 10 is used and the amount of processing. For example, the surface contamination of the charging roll 130 proceeds as the temperature and humidity during use of the image forming apparatus 10 decrease. Further, the surface contamination of the charging roll 130 proceeds as the processing amount of the image forming apparatus 10 (for example, the number of processed paper sheets P) increases. Therefore, the first predetermined time T1 is controlled to be increased as the temperature / humidity during use of the image forming apparatus 10 decreases from a predetermined temperature / humidity. Further, the first predetermined time T1 is controlled to be increased in accordance with an increase in the processing amount (for example, the number of processed paper sheets P) of the image forming apparatus 10 from a predetermined standard processing amount. By doing in this way, the surface contamination of the charging roll 130 which progresses according to use environment can be suppressed.

  Here, the case where the number of processed sheets P is used as an example of the processing amount of the image forming apparatus 10 has been described, but the cumulative toner amount developed by the charging roll 130 may be used. In this case, the cumulative toner amount can be estimated by calculating the toner amount when the toner image is formed on the image data processed by the image processing unit 33. Alternatively, the processing amount of the image forming apparatus 10 may be estimated by detecting the amount of toner remaining in the developing device 15 and estimating the amount of processed toner.

  Further, as the first predetermined time increases, the surface wear of the photosensitive drum 12 by the blade 160 of the drum cleaner 16 increases. For this reason, the second predetermined time is controlled to become longer as the first predetermined time becomes longer than a predetermined time. By doing so, surface abrasion of the photosensitive drum 12 can be suppressed.

  FIG. 5 shows an example of the configuration of the control unit 31 that performs operations that enable the image forming apparatus 10 to suppress surface contamination of the charging roll 130 and to suppress surface wear of the photosensitive drum 12. FIG. 5 shows an example of a computer 31X in which the control unit 31 is configured by a computer.

  The computer 31X includes a CPU (Central Processing Unit) 31A, a ROM (Read Only Memory) 31B, a RAM (Random Access Memory) 31C, a non-volatile memory 31D, and an input / output interface (I / O) 31E via a bus 31F. The I / O 31E includes an image forming unit 19 including a charging roll 130 and a static elimination lamp 17, an operation display unit 62, a paper supply unit 64, a paper discharge unit 66, a thermometer 67, a hygrometer 68, and A communication unit 32 is connected.

  The ROM 31B stores an image formation control program 31P that is executed by the computer 31X. The CPU 31A reads the image formation control program 31P from the ROM 31B, expands it in the RAM 31C, and executes processing by the image formation control program 31P. The computer 31X operates as the control unit 31 by the CPU 31A executing the processing by the image formation control program 31P. The image formation control program 31P may be provided by a recording medium such as a CD-ROM.

  As described above, the image forming unit 19 includes an apparatus necessary for the image forming apparatus 10 to execute an image forming operation (see FIG. 1). The communication unit 32 is an interface for performing data communication with the PC 3 or the like.

  The operation display unit 62 includes a display button that realizes reception of an operation instruction, a touch panel type display (not shown) on which various types of information are displayed, a hardware key (not shown) such as a numeric keypad and a start button, and the like. . Note that the operation display unit 62 is not an essential component, and may acquire information indicating acceptance of an operation instruction from the PC 3 or output information to the PC 3 to display various types of information.

  The paper supply unit 64 includes, for example, a paper storage unit T that stores the paper P, a supply mechanism that supplies the paper P from the paper storage unit T to the image forming unit 19, and the like (see FIG. 1). The paper discharge unit 66 includes, for example, a discharge unit for discharging the paper P, a discharge mechanism for discharging the paper P on which the image is formed by the image forming unit 19 onto the discharge unit (see FIG. 1).

  The thermometer 67 measures the temperature in the image forming operation environment of the image forming apparatus 10 as an example of the environmental temperature. The thermometer 67 is not limited to the measurement of the internal temperature of the image forming apparatus 10, and may measure the temperature of the place where the image forming apparatus 10 is installed, for example, the external temperature of the image forming apparatus 10. . The hygrometer 68 measures the humidity in the image forming operation environment of the image forming apparatus 10 as an example of the environmental humidity. As with the thermometer 67, the hygrometer 68 is not limited to the measurement of the internal humidity of the image forming apparatus 10. For example, the humidity at the place where the image forming apparatus 10 is installed, for example, the external humidity of the image forming apparatus 10 is measured. You may make it measure. Moreover, at least one of environmental temperature and environmental humidity is an example of environmental conditions.

  Next, a process for enabling the control unit 31 realized including the computer 31X to suppress the surface contamination of the charging roll 130 and the surface wear of the photosensitive drum 12 will be described in detail. Note that the first predetermined time T1 and the second predetermined time T2 used in the following description are pre-stored in the nonvolatile memory 82 in accordance with at least one of the temperature and humidity of the usage environment and the usage amount. I shall keep it.

  FIG. 6 shows a flow of processing of the image formation control program 31P executed by the CPU 31A of the computer 31X operating as the control unit 31.

  First, in step S <b> 100, various types of information for enabling suppression of surface contamination of the charging roll 130 and suppression of surface wear of the photosensitive drum 12 are acquired in response to reception of a processing start instruction from the CPU 31 </ b> A of the image forming apparatus 10. Is done. The various information acquired in step S100 indicates a first predetermined time T1 and a second predetermined time T2 that are determined in advance according to at least one of the temperature and humidity of the usage environment and the usage amount stored in advance in the nonvolatile memory 82. Information. Further, the first time, the second time, and the third time are derived from the information indicating the first predetermined time T1 and the second predetermined time T2. That is, in step S100, information indicating the predetermined first predetermined time T1 and second predetermined time T2 corresponding to the standard temperature and humidity during the standard processing of the image forming apparatus 10 is acquired from the nonvolatile memory 82. To do.

  In addition, when the use environment shown with the thermometer 67 and the hygrometer 68 is fluctuating from standard temperature and humidity, the 1st predetermined time T1 can be increased / decreased. That is, information indicating the first predetermined time T <b> 1 determined according to the use environment indicated by the thermometer 67 and the hygrometer 68 can be acquired from the nonvolatile memory 82. Further, as the processing amount of the image forming apparatus 10, for example, the number of sheets P processed by the sheet supply unit 64 or the sheet discharge unit is acquired from the sheet supply unit 64 or the sheet discharge unit, and is indicated by the number of sheets P. Information indicating the first predetermined time T <b> 1 determined according to the environment can be acquired from the nonvolatile memory 82. When the first predetermined time T1 is increased or decreased, the second predetermined time T2 is preferably increased or decreased in accordance with the increase or decrease of the first predetermined time T1. Moreover, you may increase / decrease only 2nd predetermined time T2.

  Next, in step S102, an image forming process is executed. In step S102, a series of processes are executed as described above. That is, in each image forming unit 11, the photosensitive drum 12 from which the charge is removed by the charge removal lamp 17 and the adhered toner is removed by the drum cleaner 16 is charged by the charger 13, and is scanned and exposed by the LED print head 14. The formed electrostatic latent image is developed by the developing device 15, and each color toner image is transferred to the paper P by the transfer unit, and after fixing by the fixing device 50, the paper P on which the image is formed is discharged to the discharge unit 30. The

  In the next step S104, a negative determination is made until the photosensitive drum 12 reaches the position corresponding to the time t1 of the first timing set in step S100, that is, the position at which the static elimination lamp 17 is turned off. Is repeated. The first time t1 is preferably set to a period after image formation and before the next image formation.

  If an affirmative decision is made in step S104, the process proceeds to the next step S106, and the static elimination lamp 17 is turned off. The discharging lamp 17 is kept off for the first predetermined time T1.

  Next, in step S108, the negative determination is repeated until the part of the photosensitive drum 12 corresponding to the time t3 of the third time set in step S100 reaches the position of the charging roll 130. That is, the time t3 at the third time is the time t2 when the surface position of the photoconductive drum 12 reaches the position charged by the charging roll 130 when the static elimination lamp 17 is turned off at the time t1 at the first time. It is the timing of time t3 before the second predetermined time T2 from the timing of (= t1 ′).

  If the determination in step S108 is affirmative, the process proceeds to the next step S110, and charging of the charging roll 130 is turned off. That is, the control unit 31 performs control so that the second predetermined time T2 becomes a standard time predetermined as a target.

  In the next step S112, it is determined whether or not the image forming process on the paper P has been completed. If the determination is affirmative, the present processing routine is terminated. If the determination is negative, the process returns to step S102 and the above process is repeated.

  As described above, according to the present embodiment, at the timing of time t1, the light irradiation of the static elimination lamp 17 is switched from on to off, and the static elimination lamp 17 is turned off for the first predetermined time T1. Further, the time t3 before the second predetermined time T2 from the timing of the time t2 when the surface position of the photosensitive drum 12 when the static elimination lamp 17 is turned off at the time t1 reaches the position charged by the charging roll 130. At this timing, charging of the charging roll 130 is turned off. By doing so, the photosensitive drum 12 is maintained on the surface of the photosensitive drum 12 for the second predetermined time T2, that is, the potential that has been neutralized and not charged, is maintained before the period Tx during which the residual potential is maintained. The toner is transferred to the surface portion of the body drum 12 and reaches the drum cleaner 16 by the rotation of the photosensitive drum 12. As a result, the toner is supplied to the blade 160 of the drum cleaner 16 and the surface wear of the photosensitive drum 12 can be suppressed.

  Although the image forming apparatus 10 according to the present embodiment performs color image formation, it is needless to say that the image forming apparatus 10 may perform monochrome image formation.

  Moreover, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  All documents, patent applications and technical standards mentioned in this specification are to the same extent as if each individual document, patent application and technical standard were specifically and individually stated to be incorporated by reference. Incorporated by reference in the book.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image forming unit 12 Photosensitive drum (an example of an image carrier)
13 Charging Device 14 LED Print Head (Example of Exposure Unit)
15 Developer (example of development unit)
16 Drum cleaner (example of removal part)
17 Static elimination lamp (an example of static elimination part)
20 Intermediate transfer belt 21 Primary transfer roll (an example of a transfer section)
31 Control part (an example of a control part)
50 Fixing Device 130 Charging Roll 150 Developing Roll T1 First Predetermined Time T2 Second Predetermined Time

Claims (11)

A charging roll for charging the image carrier, an exposure unit for exposing a charged portion of the image carrier, a developing roll for developing the exposed portion of the image carrier with toner, a transfer unit for transferring the developed toner image, and the transfer An image forming apparatus comprising: a charge eliminating unit that neutralizes the image carrier after transfer of a portion; and a removing unit that removes residual toner remaining on the image carrier,
After removing the residual toner remaining on the image carrier after the transfer of the transfer unit, the position where the charge removal is started passes through the charging roll, and the position where the charge removal is stopped is before reaching the charging roll. An image provided with a control unit that controls charging so that charging is stopped at a variable timing, and toner is attached to the image carrier from the developing roll without exposure, and then the toner attached to the image carrier is removed. Forming equipment. The image forming apparatus according to claim 1, wherein the timing at which the charging is stopped is changed so that a static-eliminated area remaining when the charging is stopped becomes a target size. The image forming apparatus according to claim 1, wherein the timing at which the charging is stopped is changed according to at least one of an environmental condition and a toner amount when developed by the developing roll. The at least one of environmental temperature and environmental humidity is changed so that the static-eliminated area remaining when the charging is stopped is increased so as to increase. Image forming apparatus. The neutralized area remaining when the charging is stopped is changed so as to increase as the amount of toner when developed by the developing roll increases. The image forming apparatus described in 1. The timing at which the timing is variable can be changed after the timing at which the charge removal of the image carrier is stopped and from the timing at which the position of the image carrier at which the charge removal of the image carrier has stopped reaches the charging roll. The image forming apparatus according to claim 1, wherein the timing is a predetermined time before. The controller is
Controlling the charge removal unit so that the charge removal of the image carrier is stopped for a first predetermined time from the first timing when the charge removal is stopped by the removal unit, and after the first timing, and During a variable second predetermined time from the second timing when the position where static elimination is stopped by the removing unit passes through the charging roll and reaches the charging roll to a third timing before the second timing. The image forming apparatus according to claim 1, wherein the charging roll is controlled so that charging of the image carrier is stopped. The image forming apparatus according to claim 7, wherein the first predetermined time is increased as at least one of the environmental temperature and the environmental humidity increases. The image forming apparatus according to claim 7, wherein the first predetermined time is lengthened as the cumulative amount of toner attached to the image carrier by the developing roll increases. The image forming apparatus according to claim 7, wherein the second predetermined time is increased as the first predetermined time is increased. A charging roll for charging the image carrier, an exposure unit for exposing a charged portion of the image carrier, a developing roll for developing the exposed portion of the image carrier with toner, a transfer unit for transferring the developed toner image, and the transfer Remaining on the image carrier after transfer of the transfer portion of the image forming apparatus, comprising: a charge eliminating portion that neutralizes the image carrier after the transfer of the portion; and a removal portion that removes residual toner remaining on the image carrier. After the toner is removed, the position where static elimination is started passes through the charging roll, and the position where static elimination is stopped is before reaching the charging roll, and charging is stopped and exposure is performed at a variable timing. An image forming program for causing a computer to execute a process including controlling the toner to adhere to the image carrier without removing the toner attached to the image carrier after the toner attached to the developing roll is removed. .