JP5803202B2 - Image forming apparatus and program - Google Patents

Description

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

  In Patent Document 1, after controlling the surface potential of the photosensitive drum to be −300 V, a cleaning bias of −1800 V is applied to the transfer roll to ensure a predetermined potential difference Δ1500 V necessary for cleaning, and transfer is performed. In an image forming apparatus that reversely transfers negative toner on a conveying belt to a photosensitive drum, the surface potential of the photosensitive drum that has risen to −1000 V after passing through the transfer portion is irradiated with light by an exposure static eliminator. An image forming apparatus that repeats a constant potential cycle by applying a charging voltage of -800 again and reducing the surface potential to -300 V after reducing the surface potential to -150 V is disclosed.

  Patent Document 2 discloses a transfer roll in which a bias voltage control unit cleans a transfer roll in an image forming apparatus in which a bias voltage application unit selectively applies a transfer bias voltage and a bias voltage having a polarity opposite to the transfer bias voltage to the transfer roll. In the cleaning process, the bias voltage application unit is controlled to apply a transfer bias voltage and a reverse polarity bias voltage to the transfer roll alternately at least in units of a time when the photosensitive drum makes one round. Is disclosed.

JP 2003-140436 A JP 2005-140940 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and a program that suppress the occurrence of uneven potential on the surface of the image carrier when the excess developer attached to the transfer unit is attached to the image carrier by static electricity and cleaned. It is to be.

To achieve the above object, an image forming apparatus according to claim 1 has an outer peripheral surface, the image developer is formed by being applied to the electrostatic latent image formed on the outer peripheral surface An image holding body that rotates in a predetermined direction to hold, and has an opposing surface that rotates in a direction that does not prevent the rotation of the image holding body and faces the outer peripheral surface, and the opposing surface and the outer peripheral surface A transfer member is fed into the sandwiched area during image formation, and the transfer member is transferred between the opposing surface and the outer peripheral surface so that the image is transferred to the transfer member, and is attached to the opposing surface. Applying means for alternately applying a positive potential and a negative potential to the opposing surface so that the developing developer adheres to the outer peripheral surface, and the developer remaining on the opposing surface When adhering to a surface, the outer peripheral surface and the opposing surface The rotation of the image carrier and the transfer unit is controlled so as to circulate at a predetermined speed, and the length of the divided portion obtained by dividing the outer peripheral length of the image carrier into an odd number of 3 or more is calculated. Control means for controlling the applying means so that a positive potential and a negative potential are alternately applied to the facing surface at a time interval required for the outer peripheral surface to circulate, and The outer diameter is a length corresponding to a value obtained by multiplying the natural number by the odd number, the outer diameter of the transfer means is shorter than the outer diameter of the image carrier, and the least common multiple of the natural number is A length corresponding to a value determined so that the value obtained by dividing by a natural number becomes an odd number was used .

The image forming apparatus according to claim 1, as in the invention of claim 2, further each of the outer diameter of the outer diameter and the transfer unit of the image carrier, remains on the facing surface When the developer is transferred to the outer peripheral surface, the region of the opposing surface that passes the outer peripheral surface in the first round of the opposing surface passes between the outer peripheral surface in the second round of the opposing surface. The length was determined so as to have a polarity different from that of the rotating eye.

Program according to claim 3, a computer, a program to function as the control unit included in the image forming apparatus according to claim 1 or claim 2.
It was supposed to be.

According to the first and third aspects of the present invention, the divided portion obtained by dividing the outer peripheral length of the image carrier into an odd number of three or more in a state where the outer peripheral surface and the opposing surface are rotated at a predetermined speed. Compared to the case where there is no configuration in which a positive potential and a negative potential are alternately applied to the opposite surface of the transfer means at the time interval required for the outer peripheral surface to circulate for the length, the excess attached to the transfer means There is an effect that the occurrence of uneven potential on the surface of the image carrier when the developer is attached to the image carrier by static electricity and cleaned is suppressed.

According to the invention of claim 1, the outer diameter of the image carrier, the length Satoshi corresponds to a value obtained by multiplying an odd number in the natural numbers, the outer diameter of the transfer means, shorter than the outer diameter of the image carrier In addition, as compared with the case where the length obtained by dividing the least common multiple with the natural number by the natural number is not set to a length corresponding to a value determined to be an odd number, the excessive development adhered to the transfer unit An effect is obtained that the occurrence of uneven potential on the surface of the image carrier when the agent is attached to the image carrier by static electricity and cleaned is efficiently suppressed.

According to the invention according to claim 2, of the image carrier of each of the outer diameter of the outer diameter and the transfer means, the first round of the opposing surface when transferred to the outer peripheral surface of the developer remaining on the opposing surface When the region of the facing surface that passes the outer peripheral surface in the round does not have a length that is determined to have a polarity different from that of the first rotation while passing the outer peripheral surface in the second round of the opposing surface In comparison, it is possible to obtain an effect that excess developer adhering to the transfer unit is cleaned in a short time.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating an example of the configuration of an electrical system of an image forming apparatus according to an embodiment. FIG. 10 is a schematic diagram illustrating an example of a transition mode of switching polarity of a voltage applied to each of a transfer roll and a photosensitive drum in a conventional image forming apparatus. It is a flowchart which shows an example of the flow of a process of the transfer roll cleaning process program which concerns on embodiment. FIG. 6 is a schematic diagram illustrating an example of a transition mode of switching polarity of a voltage applied to each of a transfer roll and a photosensitive drum in the image forming apparatus according to the embodiment. FIG. 6 is a schematic diagram illustrating an example of a distribution of polarity of potential applied to a transfer roll when a cleaning determination result is “x”. FIG. 10 is a schematic diagram illustrating an example of a distribution of polarity of potential applied to a transfer roll when a cleaning determination result is “◯”.

  FIG. 1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus 10 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 10 includes a cylindrical photosensitive drum 12 having an outer peripheral surface 12A, and the outer peripheral surface 12A of the photosensitive drum 12 circulates in the clockwise direction in FIG. Rotate in the direction of arrow A. On the outer periphery of the photosensitive drum 12, a charging roll 14, an optical scanning device 16, a developing device 18, a transfer roll 20, and a cleaning device 22 are arranged in this order along the rotation direction of the photosensitive drum 12.

  The charging roll 14 is provided to rotate following the rotation of the photosensitive drum 12 and is electrically connected to a charging roll power supply 24. The charging roll power supply 24 applies a voltage (superimposed voltage) obtained by superimposing an AC voltage and a DC voltage to the charging roll 14. Accordingly, the outer peripheral surface 12A of the photoconductive drum 12 is charged by the charging roll 14 to a potential having a predetermined magnitude with a predetermined polarity. In this embodiment, since the superimposed voltage applied to the charging roll 14 has a negative polarity, the outer peripheral surface 12A of the photosensitive drum 12 is charged to a negative polarity by the charging roll 14.

  The optical scanning device 16 modulates the laser beam emitted from the light source in accordance with image information indicating an image to be formed, and deflects the laser beam on the outer peripheral surface 12A of the charged photosensitive drum 12 in the main scanning direction. Scanning is performed substantially parallel to the axis of the photosensitive drum 12. As a result, an electrostatic latent image is formed on the outer peripheral surface 12A of the photosensitive drum 12.

  The developing device 18 develops the electrostatic latent image by applying toner to a predetermined area including the electrostatic latent image formed on the outer peripheral surface 12 </ b> A of the photosensitive drum 12, and the toner on the outer peripheral surface 12 </ b> A of the photosensitive drum 12. Form an image. In the present embodiment, a developer including two components of toner particles (colored particles) having negative polarity and carriers (magnetic particles) having positive polarity is applied as the toner. Further, the developing device 18 according to the present embodiment includes a developing roll 18A. The developing roll 18A is applied with a superimposed voltage having a polarity (in this embodiment, negative polarity as an example) that is not different from that of the outer peripheral surface 12A of the photosensitive drum 12, and toner particles together with the positive polarity carrier supplied into the developing device 18 Is conveyed to the outer peripheral surface of the developing roll 18A. Further, the developing roller 18A is rotationally driven in the direction of arrow C of the photosensitive drum 12, and the toner attached to the developing roller 18A is supplied to the outer peripheral surface 12A of the photosensitive drum 12.

  The transfer roll 20 has an outer peripheral surface 20A as an opposing surface facing the outer peripheral surface 12A and is formed in a columnar shape having an outer diameter smaller than that of the photosensitive drum 12, and the outer peripheral surface 20A passes through the conveyance path of the recording paper P. The photoconductor drum 12 is disposed so as to face the outer peripheral surface 12A. The transfer roll 20 rotates in the direction of arrow B so that the outer circumferential surface 20A circulates in a direction that does not prevent the rotation of the photosensitive drum 12, and the toner image formed on the outer circumferential surface 12A of the photosensitive drum 12 is applied to the recording paper P. When transferring (when forming an image), the recording paper P as a transfer member fed between the outer peripheral surfaces 12A and 20A is sandwiched between the outer peripheral surfaces 12A and 20A, thereby being formed on the outer peripheral surface 12A of the photosensitive drum 12. The toner image is transferred to the recording paper P. The transfer roll 20 is electrically connected to a transfer roll power supply 26. The transfer roll power supply 26 applies a superimposed voltage to the transfer roll 20 during image formation and when the residual toner attached to the outer peripheral surface 20A of the transfer roll 20 is attached to the photosensitive drum 12 by static electricity (when the transfer roll is cleaned). In other words, the transfer roll 20 transfers a toner image formed on the outer peripheral surface 12A of the photosensitive drum 12 to the recording paper P by applying a positive bias voltage during image formation, and the outer peripheral surface during cleaning of the transfer roll. Positive and negative bias voltages are alternately applied at predetermined time intervals so that the positive and negative residual toner adhering to 20A is reversely transferred to the outer peripheral surface 12A of the photosensitive drum 12.

  The cleaning device 22 cleans the outer peripheral surface 12A by scraping the toner remaining on the outer peripheral surface 12A of the photosensitive drum 12 from the outer peripheral surface 12A using the blade 22A.

  On the upstream side of the transfer roll 20 in the sheet conveyance direction, a conveyance belt 32 stretched around the support rolls 28 and 30 is provided. It is sent between 20A.

  A fixing device 34 is disposed on the downstream side of the transfer roll 20 in the sheet conveyance direction. The fixing device 34 includes a heating roll 34A for heating the toner image on the paper P, and a roll 34B pressed against the heating roll 34A. The recording paper P includes a nip portion between the heating roll 34A and the roll 34B. As a result, the toner image is melted and solidified to be fixed on the recording paper P, and discharged to the outside of the image forming apparatus 10 by a paper discharge roll (not shown) disposed downstream of the fixing device 30 in the paper conveyance direction. The

  FIG. 2 is a block diagram showing a main configuration of the electrical system of the image forming apparatus 10 according to the present embodiment. As shown in the figure, the image forming apparatus 10 includes a CPU (Central Processing Unit) 60 that controls the operation of the entire image forming apparatus 10 and a ROM (Read Only Memory) 62 in which various processing programs and various parameters are stored in advance. A RAM (Random Access Memory) 64 used as a work area when the CPU 60 executes various processing programs, and a secondary storage unit (here, a hard disk device as an example) 66 used to store various information. A UI (user interface) that includes a touch panel display or the like in which a transmissive touch panel is superimposed on the display, displays various information on the display surface of the display, and accepts various information and instructions when the user touches the touch panel. ) Panel 68 and communication means (for example, LAN (Local Area Network)) For receiving various information such as image information indicating an image to be formed on the recording paper P from the external device 70 and transmitting various information to the external device 70 And an external interface 72 that controls communication with the external device 70.

  The CPU 60, ROM 62, RAM 64, NVM 66, UI panel 68, and communication interface 72 are connected to each other via a system bus BUS. Therefore, the CPU 60 accesses the ROM 62, RAM 64, and NVM 66, displays various information on the UI panel 68, grasps the user's operation instruction content on the UI panel 68, and the external interface 72 from the external device 70. Receiving various types of information and transmitting various types of information to the external device 70 via the external interface 72 are performed.

  In addition, the image forming apparatus 10 includes an image forming engine unit 74 that forms an image on the recording paper P by the xerographic method. The image forming engine unit 74 includes the photosensitive drum 12, the charging roll 14, the optical scanning device 16, the developing device 18, the transfer roll 20, the cleaning device 22, the charging roll power supply 24, the transfer roll power supply 26, and the fixing device 34. And a motor (not shown) for driving a transport system such as each roll. Image forming engine unit 74

Are also connected to the system bus BUS. Therefore, the CPU 60 controls the operation of the image forming engine unit 74 and grasps the state of the image forming engine unit 74, respectively.

  Next, the operation of the image forming apparatus 10 according to the present embodiment will be described.

  In the image forming apparatus 10 configured as described above, when the photosensitive drum 12 rotates in the direction of arrow A in FIG. 1, the outer peripheral surface 12A of the photosensitive drum 12 is first set to a predetermined negative size by the charging roll 14. It is charged to the potential. When the photosensitive drum 12 is further rotated, the surface of the photosensitive drum 12 is exposed by the optical scanning device 16, and the potential of the exposed portion of the photosensitive drum 12 is decreased as compared with other portions, so that an electrostatic latent image is formed. It is formed. The electrostatic latent image on the photosensitive drum 12 is developed by applying toner by the developing device 18.

  Thereafter, when the photosensitive drum 12 further rotates, the recording paper P is conveyed between the transfer roll 20 and the photosensitive drum 12 in accordance with the timing, and a transfer voltage having a polarity opposite to that of the toner is applied to the transfer roll 20. . As a result, the toner is electrically attracted to the transfer roll 20 and the toner image on the photosensitive drum 12 is transferred to the recording paper P. The toner image transferred to the recording paper P is heated and pressed by the fixing device 30 and fixed. Further, the outer peripheral surface 12A of the photosensitive drum 12 after the toner image is transferred is cleaned by the cleaning device 22 so that the toner remaining on the outer peripheral surface 12A is removed.

  Incidentally, since the outer peripheral surface 20A of the transfer roll 20 directly faces the outer peripheral surface 12A of the photosensitive drum 12, the toner remaining on the outer peripheral surface 12A of the photosensitive drum 12 may adhere and become dirty. Therefore, in the image forming apparatus 10 according to the present embodiment, the toner attached to the outer peripheral surface 20A of the transfer roll 20 is attached to the outer peripheral surface 12A of the photoconductive drum 12 by static electricity (reverse transfer) during cleaning of the transfer roll 20, and the photoconductor. The toner reversely transferred from the transfer roll 20 to the drum 12 is cleaned by a cleaning device 22. Since the positive polarity toner and the negative polarity toner are usually mixed and adhered to the outer peripheral surface 20A of the transfer roll 20, a positive voltage and a negative voltage are alternately applied to the transfer roll 20. By doing so, the toner of each polarity is reversely transferred to the photosensitive drum 12. In general, for example, as shown in FIG. 3, reverse transfer of positive and negative toners is realized by switching the polarity of the voltage applied to the transfer roll 20 every time the transfer roll 20 rotates once. ing. However, when the polarity of the voltage is switched in accordance with one rotation cycle of the transfer roll 20, a region where the charged potential is biased to one polarity occurs on the outer peripheral surface 12A of the photosensitive drum 12 as shown in FIG. May end up. In the example shown in FIG. 3, the length of 5/9 of the outer peripheral length of the outer peripheral surface 12 </ b> A of the photosensitive drum 12 corresponds to the outer peripheral length of the outer peripheral surface 20 </ b> A of the transfer roll 20. Since the negative polarity voltage and the positive polarity voltage are alternately applied every rotation cycle from the rotation of the first turn of 20, the negative polarity potential is concentratedly applied to the outer peripheral surface 12 </ b> A of the photosensitive drum 12. Region (region surrounded by a dashed-dotted rectangular frame shown in FIG. 3), and as a result, the potential of the outer peripheral surface 12A of the photosensitive drum 12 and the potential (developing potential) of the outer peripheral surface of the developing roll 18A The gap becomes larger locally. This causes a problem that the carrier is discharged and a so-called fogging stain. Therefore, in the image forming apparatus 10 according to the present embodiment, in order to suppress the occurrence of a phenomenon in which the charging polarity in a part of the outer peripheral surface 12A of the photosensitive drum 12 is different from the charging polarity in the other area when the transfer roll is cleaned. The transfer roll cleaning process is executed.

  In the image forming apparatus 10 according to the present embodiment, the transfer roll cleaning process is realized by a software configuration. As an example, there is a form in which a program is executed using a computer. However, the present invention is not limited to such a software configuration. Needless to say, it may be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  Hereinafter, a case where the image forming apparatus 10 according to the present embodiment realizes the transfer roll cleaning process by executing the above program will be described. In this case, a form in which the program is stored in the ROM 62 in advance, a form in which the stored content is stored in a recording medium that is read by a computer, a form in which the program is distributed via wired or wireless communication means, and the like May be applied.

  FIG. 4 shows image formation when a predetermined condition (for example, a condition that an image is formed on a predetermined number of recording sheets P) is satisfied as a condition for starting execution of the transfer roll cleaning process. 4 is a flowchart showing a process flow of a transfer roll cleaning process program executed by a CPU 60 of the apparatus 10.

  In step 100 in the figure, each rotation of the photosensitive drum 12 and the transfer roll 20 is started, and then the process proceeds to step 102 where each rotation speed of the photosensitive drum 12 and the transfer roll 20 is set to a predetermined rotation speed. Wait until it becomes stable. In step 102, when the photosensitive drum 12 and the transfer roll 20 reach a predetermined rotational speed and the speeds are stabilized, step 102 is affirmative and the process proceeds to step 104, where a predetermined polarity (here, an example) As a negative polarity), and applying a superposed voltage (eg, 700V superposed voltage) of a predetermined magnitude (as an example, superposed voltage of -700V) to the charging roll 14, while maintaining the superposed voltage value. By controlling 24, application of a potential having a predetermined polarity to the outer peripheral surface 12A of the photosensitive drum 12 is started.

  In the next step 106, the process is on standby until the potential applied to the outer peripheral surface 12A of the photosensitive drum 12 becomes a predetermined level, the size is stabilized, and the potential is applied to the entire area of the outer peripheral surface 12A. To do. In this step 106, the potential applied to the outer peripheral surface of the photosensitive drum 12 becomes a predetermined magnitude, the magnitude is stabilized, and the potential is applied to the entire outer peripheral surface 12A. Conditions determined in advance (for example, after the processing of step 104 is executed, the magnitude of the charging potential of the outer peripheral surface 12A of the photosensitive drum 12 is stabilized, and the potential is applied to the entire area of the outer peripheral surface 12A. The process waits until a predetermined time has passed as a time until the time is satisfied.

  In the next step 108, a potential (as an example, 2500 V) having a predetermined polarity (here, a negative potential as an example) with respect to the outer peripheral surface 20A of the transfer roll 20 (as an example). The transfer roll power supply 26 is controlled so that application of a potential of −2500 V is started.

  In the next step 110, the process waits until a predetermined time elapses after the execution of the process in step 108 is finished. The “predetermined time” used in the processing of this step 110 means that the outer peripheral surface 12A circulates by the length of the divided portion obtained by dividing the outer peripheral length of the photosensitive drum 12 by “3”. This means the time required, but the present invention is not limited to this. The outer peripheral length of the photosensitive drum 12 is divided into an odd number (for example, “5” or “7”) of 3 or more. The time required for the outer circumferential surface 12A to circulate may be used.

  In the next step 112, the transfer roll power supply 26 is controlled so that the application of the potential of one polarity to the outer peripheral surface 20A of the transfer roll 20 is stopped. From the start of the program to the present time, it is determined whether the number of times of switching the polarity of the potential applied to the outer peripheral surface 20A of the transfer roll 20 has reached a predetermined number of times, and a negative determination is made. If YES in step 124, the process proceeds to step 124. If an affirmative determination is made, the process proceeds to step 116. Here, the “predetermined number of times” used in the process of step 114 is the number of times of polarity switching required to eliminate the potential unevenness on the outer peripheral surface 12A of the photosensitive drum 12, and the transfer roll 20 The number of times of switching the polarity required to make the amount of the positive and negative toners remaining in the toner to be equal to or less than a predetermined amount is to eliminate potential unevenness at least on the outer peripheral surface 12A of the photosensitive drum 12. The number of times of switching the polarity required for this is sufficient.

  In Step 116, a potential (here, 800V as an example) having a predetermined polarity (here, 800V) of the other polarity (here, positive potential as an example) with respect to the outer peripheral surface 20A of the transfer roll 20 is illustrated. After the transfer roll power supply 26 is controlled so as to start the application of the ink, and in the next step 118, after the execution of the process of step 108 is completed, the process waits until the predetermined time elapses. Then, the process proceeds to step 120, and the transfer roll power supply 26 is controlled so that the application of the potential of the other polarity to the outer peripheral surface 20A of the transfer roll 20 is stopped.

  In the next step 122, the number of times of switching the polarity of the potential applied to the outer peripheral surface 20A of the transfer roll 20 from the start of the transfer roll cleaning processing program to the present time reaches the above-mentioned predetermined number of times. If the determination is negative, the process returns to step 108. If the determination is affirmative, the process proceeds to step 124. In step 124, the application of the potential to the outer peripheral surface 12A of the photosensitive drum 12 is stopped by controlling the charging roll power supply 24 so as to stop the application of the voltage to the charging roll 14, and then the process proceeds to step 126. After each rotation of the photosensitive drum 12 and the transfer roll 20 is stopped, the transfer roll cleaning processing program is terminated.

  In FIG. 5, a transition mode of switching the polarity of the potential applied to the outer peripheral surface 12 </ b> A of the photosensitive drum 12 by executing the transfer roll cleaning process in the image forming apparatus 10 and the outer peripheral surface 20 </ b> A of the transfer roll 20. A transition mode of switching the polarity of the applied potential is shown. As shown in FIG. 5, the polarity of the potential applied to the transfer roll 20 is equal to the length obtained by dividing the outer peripheral length of the photosensitive drum 12 by “3” at the time interval required for the outer peripheral surface 12A to circulate. Therefore, in the outer peripheral surface 12A of the photosensitive drum 12, a positive potential is applied to the region to which a negative potential is applied in the first round, and a positive polarity is applied in the first round. A negative potential is applied to the region to which the potential is applied in the second round. The polarity of the potential applied to the transfer roll 20 is switched until the unevenness of the potential applied to the outer peripheral surface 12A of the photosensitive drum 12 is eliminated.

  By the way, after the rotation of the transfer roll 20 is started at the time of cleaning the transfer roll, the number of times of polarity switching is divisible by the number of times of application of the positive voltage and the number of times of application of the negative voltage is divisible by the start of the next rotation. In this case, since the region of the outer peripheral surface 20A passing the outer peripheral surface 12A of the photosensitive drum 12 is set to one of positive polarity and negative polarity (for example, negative polarity) while passing the photosensitive drum 12, the other There arises a situation in which the toner of polarity (for example, positive polarity) is not removed. For example, as shown in FIG. 6, a positive voltage (in the example shown in FIG. 6) is applied to the transfer roll 20 at every round time of the outer peripheral surface 20A corresponding to the length obtained by dividing the outer peripheral length of the transfer roll 20 into four equal parts. A region having a positive polarity and a region having a negative polarity on the outer peripheral surface 20 </ b> A when a negative voltage (indicated as “negative bias” in the example shown in FIG. 6) is applied alternately. Therefore, toner that is not reversely transferred to the outer peripheral surface 12A of the photosensitive drum 12 may remain on the outer peripheral surface 20A.

  On the other hand, as shown in FIG. 7 as an example, a positive voltage (see FIG. In the example shown in FIG. 7, when a positive bias (noted as “negative bias” in the example shown in FIG. 7) is applied alternately, a region having a positive polarity in the previous round is displayed. Since the negative polarity in the current round and the negative polarity in the previous round is made positive in the current round and the polarity is changed every round, the outer circumferential surface 12A of the photosensitive drum 12 is replaced with the outer circumferential surface 20A. The occurrence of a situation in which toner that is not reversely transferred remains is suppressed.

Therefore, in the image forming apparatus 10 according to the present embodiment, the outer diameter of the photosensitive drum 12 is an odd number B (here, the above-described example is 3) with respect to a predetermined natural number A (“6” as an example). A length corresponding to a value obtained by multiplying by “3”, which is the number of divisions of the outer peripheral length of the photosensitive drum 12 used for defining the “predetermined time” used in the processing of step 110 (an example) And the value C (= L / A) obtained by dividing the outer diameter of the transfer roll 20 by the least common multiple L with the natural number A by the natural number A is set to an odd number. The length is equivalent. Tables 1 to 6 below show the correspondence between the BTR outer diameter (unit: mm), the least common multiple L, the value C, the BTR required rotation speed (BTR required circumference), and the cleaning determination result for natural numbers 2 to 7. ing. “BTR” shown in Tables 1 to 6 indicates the transfer roll 20, and “BTR outer diameter” indicates the outer diameter of the transfer roll 20 corresponding to the outer peripheral length of the transfer roll 20. ing. Further, “BTR required circumference” indicates the number of rotations required to remove the toner attached to the outer peripheral surface 20A of the transfer roll 20, and “cleaning determination result” indicates that the transfer roll 20 is in the cleaning state when the transfer roll is cleaned. This represents a determination result as to whether or not a predetermined amount or more remains on the outer peripheral surface 20A of the transfer roll 20 when the number of rotations determined as “BTR required circumference” is rotated. We have learned through tests using actual machines and simulations using computers. “◯” in the cleaning determination result indicates that the toner does not remain in a predetermined amount or more, and “X” indicates that the toner remains in a predetermined amount or more. In this embodiment, as the outer diameter of the transfer roll 20, the BTR outer diameter “18 mm” associated with C = 3 in the case of A = 6 shown in Table 5 is applied. The value of the BTR outer diameter for which the cleaning determination is “◯” may be applied. Further, each of the outer peripheral length of the photosensitive drum 12 and the outer peripheral length of the transfer roll 20 is the outer periphery of the outer peripheral surface 20A that passes the outer peripheral surface 12A in the first rotation of the transfer roll 20 during the cleaning of the transfer roll. It is preferable that the length is determined so as to have a polarity different from that of the first round while passing the surface 20A. In the examples shown in the following Tables 1 to 6, it is preferable to apply the value of the BTR outer diameter associated with the value “2” of “BTR required circumference” as the outer diameter of the transfer roll 20. In this case, the time required for removing the toner remaining on the transfer roll 20 is shortened as compared with the case where other values of the BTR outer diameter are used.

なお、上記実施形態では、転写ロール２０を例に挙げて説明したが、これに限らず、記録用紙Ｐに直接転写を行う転写ベルトであっても良い。この場合、転写ロール２０の外径に代えて転写ベルトの外径が適用される。

In the above embodiment, the transfer roll 20 has been described as an example. However, the present invention is not limited to this, and a transfer belt that directly transfers to the recording paper P may be used. In this case, the outer diameter of the transfer belt is applied in place of the outer diameter of the transfer roller 20.

  In the above-described embodiment, the cleaning device 22 is provided on the outer periphery of the photosensitive drum 12. However, the present invention is not limited thereto, and a blade that mechanically scrapes the toner attached to the outer peripheral surface 20A is provided on the outer periphery of the transfer roll 20. A configuration in which the toner on the outer peripheral surface 20A is directly removed by this blade and the toner on the transfer roll 20 is indirectly removed by the cleaning device 22 may be employed.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum 18 Developing apparatus 20 Transfer roll 22 Cleaning apparatus 26 Power supply 60 for transfer roll CPU

Claims (3)

An image carrier having an outer circumferential surface and rotating in a predetermined direction for holding an image formed by applying a developer to the electrostatic latent image formed on the outer circumferential surface;
The image holding member rotates in a direction that does not prevent the rotation of the image carrier and has an opposing surface that faces the outer peripheral surface, and a member to be transferred is sent to an area sandwiched between the opposing surface and the outer peripheral surface during image formation. Transfer means for transferring the image to the transfer member by sandwiching the transfer member between the opposing surface and the outer peripheral surface;
Applying means for alternately applying a positive potential and a negative potential to the opposing surface so that the developer attached to the opposing surface is attached to the outer peripheral surface;
When the developer remaining on the facing surface is adhered to the outer peripheral surface, each rotation of the image holding member and the transfer unit is controlled so that the outer peripheral surface and the facing surface circulate at a predetermined speed, and A positive potential and a negative polarity are applied to the opposing surface at a time interval required for the outer peripheral surface to circulate the length of the divided portion obtained by dividing the outer peripheral length of the image carrier into an odd number of 3 or more. Control means for controlling the applying means so that the potential is applied alternately ,
The outer diameter of the image carrier is a length corresponding to a value obtained by multiplying the natural number by the odd number,
The outer diameter of the transfer means is shorter than the outer diameter of the image carrier, and the value obtained by dividing the least common multiple with the natural number by the natural number corresponds to an odd number. An image forming apparatus having a length . Further, each of the outer diameter of the image holding member and the outer diameter of the transfer means is transferred by the first round of the opposing surface when the developer remaining on the opposing surface is transferred to the outer peripheral surface. according to claim 1, area of the opposing surface of the outer peripheral surface and passing each other has a length defined as a polarity different from the first rotation while passing each other and said outer peripheral surface in the second round of circulation of the facing surface Image forming apparatus. Computer
The program for functioning as a control means contained in the image forming apparatus of Claim 1 .

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