JP6225677B2 - Image forming apparatus and program - Google Patents

Description

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

  In Patent Document 1, the potential applied to the charging roll is switched to the ground potential to shift the image forming apparatus to the cleaning mode, and the charging roll is transferred to the photosensitive member to remove the charging roll. An image forming apparatus is disclosed.

  In Patent Document 2, in order to remove the positive toner remaining on the charging roll, the photosensitive drum is charged to a negative polarity by a transfer roll, and a positive voltage is applied to the charging roll. An image forming apparatus that transfers residual toner to a photosensitive drum is disclosed.

JP2013-92576A JP-A-10-161500

  The problem of the present invention is that, compared with the case where the neutralization target region in the neutralization state reaches the developer transfer position, the developer is removed from the holding means for retaining the developer due to the potential fluctuation of the image carrier in accordance with the static elimination. To provide an image forming apparatus and a program in which leakage is suppressed.

In order to solve the above-described problem, an image forming apparatus according to claim 1, wherein a latent image is formed on an image holding member, and the latent image is developed by a potential difference at a developer transfer position from a holding unit that holds the developer. Applying means for applying a potential for transferring the agent to the image carrier at a potential application position; and for the charge removal target region that has passed through the transfer position of the image carrier, the charge removal target region has the potential application. In the case where the state of removing dirt from the applying means due to the potential difference generated on the condition that the charge removal is stopped is canceled by the start of the charge removal, the charge removal means that performs charge removal before reaching the position. Before the discharge target area reaches the developer transfer position with respect to the discharge target area , a direct current is applied to the application unit and then an alternating current is applied, whereby the potential polarity of the holding unit Key Comprising a control means for controlling so that the potential is applied, the.
A latent image is formed on the image carrier, and a potential for transferring the developer to the latent image by a potential difference at a developer transfer position from a holding unit that holds the developer is applied to the image carrier at the potential application position. Granting means;
The image forming apparatus according to claim 2, wherein a static elimination unit performs static elimination on the static elimination target area that has passed the transfer position of the image carrier before the static elimination target area reaches the potential application position. When the state of removing dirt from the applying means due to the potential difference generated on the condition that the charge removal is stopped is canceled by the start of charge removal, the charge removal target region is different from the charge removal target region where the charge removal is performed. Control is performed so that an adjustment potential of the potential polarity of the holding unit is applied before reaching the developer transfer position, and the applying unit from a state where a superimposed voltage in which direct current and alternating current are superimposed is applied to the applying unit. And the control means for controlling the application of the direct current to be suppressed after the application of the alternating current is suppressed.

According to a first aspect of the present invention, in the image forming apparatus according to the third aspect , when the control unit cancels the state of removing dirt from the applying unit by the start of the neutralization, the neutralization is performed. The applying means is controlled so that the adjustment potential is applied to the broken static elimination target region at the potential applying position.

In the image forming apparatus according to any one of claims 1 to 3 , as in the invention according to claim 5, the dirt removing voltage applied to the applying unit is the image holding body and the image forming apparatus. The voltage is such that discharge by the applying means is avoided.

In order to solve the above problem, a program according to a fifth aspect causes a computer to function as a control unit in the image forming apparatus according to any one of the first to fourth aspects.

According to the first , second, and fifth aspects of the present invention, compared with the case where the charge removal target region in the charge removal state reaches the developer transfer position, the charge is applied from the holding means that holds the developer. The leakage of the developer due to the potential fluctuation of the image carrier is suppressed.

According to the third aspect of the present invention, the adjustment potential is applied to the static elimination target region with a simple configuration as compared with the case where the applying means is not controlled so that the adjustment potential is applied to the static elimination target region at the potential applying position. Is done.

According to the fourth aspect of the present invention, the potential of the image carrier is caused by the discharge as compared with the case where the voltage for avoiding the discharge by the image carrier and the applying unit is not used as the dirt removing voltage applied to the applying unit. Fluctuation to the ground potential side is suppressed.

1 is a schematic configuration diagram illustrating an example of a main configuration of an image forming apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional view illustrating an example of a main configuration of a developing device included in the image forming apparatus according to the embodiment. 1 is a block diagram illustrating an example of a main configuration of an electric system of an image forming apparatus according to an embodiment. It is a flowchart which shows an example of the flow of the electric potential control process which concerns on embodiment. FIG. 5 is a time chart showing an example of potentials of a charging roll and a developing roll when the potential control process shown in FIG. 4 is not performed, and an on / off switching state of a static elimination lamp. FIG. 5 is a time chart showing an example of the charging roll and developing roll potential and the charge-off lamp on / off switching state when the potential control process shown in FIG. 4 is performed and image formation is subsequently performed after the cleaning operation period. is there. The time shown in FIG. 4 is an example of the potential control process and the potential of the charging roll and the developing roll when the operation of the image forming apparatus is stopped or stopped after the cleaning operation period, and the on / off switching state of the charge removal lamp. It is a chart. 5 is a time chart showing an example of signal levels corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the potential control processing shown in FIG. 4 is not performed. 6 is a time chart showing an example of signal levels corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the potential control processing shown in FIG. 4 is performed. An example of the signal level corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the direct current of the superimposed voltage applied to the charging roll is lowered to the ground potential during the cleaning operation period is shown. It is a time chart. 6 is a time chart showing another example of the signal level corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the potential control process shown in FIG. 4 is not performed. FIG. 6 is a time chart showing another example of the signal level corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the potential control process shown in FIG. 4 is performed. Another example of the signal level corresponding to the potential of the developing roll and the photosensitive drum and the direct current applied to the charging roll when the direct current of the superimposed voltage applied to the charging roll is lowered to the ground potential during the cleaning operation period It is a time chart which shows. FIG. 5 is a schematic configuration diagram illustrating another example of a main configuration of the image forming apparatus according to the embodiment.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, as an example, in the image forming apparatus 10 shown in FIG. 1, toner and a carrier that plays a role of transporting the toner using electrostatic force to adhere the toner to the electrostatic latent image are mixed. The case where an electrostatic latent image is developed with a component developer will be described as an example. However, the present invention is not limited to this, and can be applied to any image forming apparatus that develops an electrostatic latent image with a developer other than the two-component developer. In this embodiment, “toner” refers to fine particles in which color particles such as carbon are attached to plastic particles having chargeability, for example. In the present embodiment, “carrier” refers to fine particles obtained by coating a magnetic material with an epoxy resin or the like, for example, and mixed with toner.

  As an example, as shown in FIG. 1, the image forming apparatus 10 includes a photosensitive drum 30 (an example of an image carrier according to the present invention), a charger 32, an exposure unit 34, a developing unit 36, and a charge eliminating lamp 38 (according to the present invention). An example of such a static eliminating unit) and a cleaner 40 are provided.

  The photosensitive drum 30 includes a conductive base 30A formed in a cylindrical shape and a photosensitive film 30B. The photosensitive film 30B has, for example, a photosensitive layer in which a charge generation layer and a charge transport layer are laminated on the outer peripheral surface of the base body 30A, and is formed of a photosensitive member containing an organic charge generation material in the charge generation layer. Film.

  The photosensitive drum 30 is arranged so that the outer peripheral surface faces the paper P, and is predetermined in a predetermined direction (the direction of the arc arrow G shown in FIG. 1) upon receiving a driving force from a driving source 106 described later. Rotate at the specified speed.

  The charger 32 is disposed on the outer peripheral surface of the photosensitive drum 30. The charger 32 includes a charging roll 32A (an example of an applying unit according to the present invention) and a cleaning roll 32B.

  The charging roll 32 </ b> A is a conductive roll, the outer peripheral surface thereof is in contact with the outer peripheral surface of the photosensitive drum 30, and rotates following the rotational operation of the photosensitive drum 30. A superimposed voltage in which DC (direct current) and AC (alternating current) are superimposed is applied to the charging roll 32A by an application unit 100 described later. The charging roll 32 </ b> A charges the outer peripheral surface of the photosensitive drum 30 to the image forming potential over the entire area while rotating so as to follow the rotation of the photosensitive drum 30 in a state where the superimposed voltage is applied. Here, the image forming potential refers to, for example, a negative potential (for example, −700 V) at which an electrostatic latent image is formed by the exposure device 34. The alternating current applied to the charging roll 32A is applied with a peak-to-peak voltage that is twice or more the discharge start voltage (hereinafter referred to as “the potential of the photosensitive drum 30”). Is a voltage that substantially matches the DC voltage applied to the charging roll 32A, and is responsible for improving charging uniformity and charging environment fluctuation.

  Hereinafter, for convenience of explanation, “applying a potential to the outer peripheral surface of the photosensitive drum 30” is referred to as “applying a potential to the photosensitive drum 30”. In the following, for convenience of explanation, “charging of the outer peripheral surface of the photosensitive drum 30” is referred to as “charging of the photosensitive drum 30”.

  The cleaning roll 32B is in contact with the outer peripheral surface of the charging roll 32A, and removes dirt such as toner and carrier adhering to the charging roll 32A.

  An exposure unit 34 is provided on the downstream side of the charger 32 in the rotation direction of the photosensitive drum 30. The exposure device 34 exposes a charged region on the photosensitive drum 30 in a state where the outer peripheral surface of the photosensitive drum 30 is charged by the charging roll 32A. The exposure device 34 includes an LED array in which a plurality of LEDs (light emitting diodes) are arranged along the main scanning direction (the front-rear direction in FIG. 2) during image formation. The LED array irradiates a light beam based on input image information while scanning in the axial direction of the photosensitive drum 30 charged by the charging roll 32A. The potential of the region irradiated with the light beam by the exposure device 34 decreases (transitions to the ground potential side from the current potential), and an electrostatic latent image is formed on the photosensitive drum 30.

  A developing device 36 is provided on the downstream side of the exposure device 34 in the rotation direction of the photosensitive drum 30. When the electrostatic latent image formed on the photosensitive drum 30 moving in the direction of the arc G shown in FIG. 1 reaches the developer transfer position, the developing unit 36 converts the electrostatic latent image into a predetermined color (here, Then, as an example, the toner image is formed by developing with black toner. The developer transfer position refers to, for example, a position on the outer peripheral surface of the photosensitive drum 30 that faces a developing roll 54 described later.

  As an example, as shown in FIG. 2, the developing device 36 includes a developer housing 50 in which a two-component developer is stored. On the bottom surface of the developer housing 50, a magnetic permeability sensor 52 is fixed by being leaned against the inner wall of the developer housing 50. Therefore, the magnetic permeability sensor 52 is buried in the two-component developer. In this state, the magnetic permeability sensor 52 measures the magnetic permeability of the two-component developer stored in the developer housing 50.

  Inside the developer housing 50, a developing roll 54 (an example of a holding unit according to the present invention) is provided. The developing roll 54 is attached to the developer housing 50 so as to be rotatable around an axis so as to be close to the outer peripheral surface of the photosensitive drum 30. A developer transport roll 56 is provided inside the developer housing 50. The developer conveying roll 56 is disposed adjacent to the developing roll 54 and conveys the two-component developer in the developer housing 50 and conveys the toner contained in the two-component developer to the developing roll 54.

  In the developer housing 50, the two-component developer stored in the developer housing 50 is agitated by rotating the agitation paddle 58 and the agitation screw 60 in response to a driving force from a driving source 106, which will be described later, so that the toner is a carrier. Electrostatically adsorbed on. The carrier to which the toner is attached in this manner is attracted to the developer transport roll 56 having magnetism by a magnetic force and transported to the development roll 54, and is attracted to the development roll 54, which is a magnet roll, by a magnetic force. A developing roll voltage is applied to the developing roll 54 by an application unit 100 described later. Here, the “developing roll voltage” is, for example, a predetermined value in which a direct current (developing bias potential) of a polarity (negative polarity in this embodiment) and an alternating current that are not different from the potential of the photosensitive drum 30 is superimposed. Refers to the applied voltage.

  In this way, the developing roll voltage is applied to the developing roll 54 and the developing roll 54 receives a driving force of a driving source 106 described later and rotates in a predetermined direction (the direction indicated by the circular arc in FIG. 3). The toner on the developing roll 54 is transferred to the photosensitive drum 30. In other words, the toner adhering to the outer peripheral surface of the developing roll 54 is transferred from the developing roll 54 to the region irradiated with the light beam on the photosensitive drum 30 (an electrostatic latent image on the photosensitive drum 30), thereby electrostatically The latent image is developed to form a toner image.

  A toner replenishing device 62 is provided above the developer housing 50. The toner replenishing device 62 includes a toner cartridge 64 that contains toner, and a replenishing flow channel 66 that communicates the inside of the toner cartridge 64 and the inside of the developer housing 50. Inside the toner cartridge 64, an auger 68 as a conveying member for conveying toner is provided. The auger 68 rotates in response to a driving force of a driving source 106 described later. Therefore, the toner stored in the toner cartridge 64 is supplied into the developer housing 50 through the supply channel 66 when the auger 68 rotates. In the present embodiment, the amount of toner replenished inside the developer housing 50 is adjusted by the rotation time of the auger 68. In the present embodiment, a configuration is adopted in which the carrier is not replenished inside the developer housing 50 and only the toner is replenished.

  On the other hand, in FIG. 1, a transfer roll 70 is provided on the downstream side of the developing device 36 in the rotation direction of the photosensitive drum 30, and the transfer roll 70 receives a driving force of a driving source 106 described later and receives an arc arrow. Rotate in H direction. A positive voltage is applied to the transfer roll 70 by an application unit 100 described later. At a position where the toner image is transferred, that is, a position facing the outer peripheral surface of the transfer roll 70 on the outer peripheral surface of the photosensitive drum 30 (hereinafter referred to as “transfer position”), the paper P is fed at a predetermined speed. Be transported. Therefore, the transfer roll 70 transfers the toner image formed on the outer peripheral surface of the photosensitive drum 30 onto the paper P by applying a positive bias voltage while the paper P passes through the transfer position. .

  A fixing device 72 is provided in the conveyance path of the paper P on which the toner image is transferred in this way. The fixing device 72 includes a pressure roll 72A and a heating roll 72B, and the pressure roll 72A and the heating roll 72B are disposed to face each other. The paper P transported to the fixing device 72 is sandwiched and transported between the pressure roll 72A and the heating roll 72B, whereby the toner image on the paper P is melted and pressed against the paper P to be fixed on the paper P. .

  A neutralizing lamp 38 is provided on the downstream side of the transfer roll 70 in the rotation direction of the photosensitive drum 30. The neutralization lamp 38 irradiates the outer peripheral surface of the photosensitive drum 30 with neutralizing light, thereby removing the residual potential of the photosensitive drum 30 (for example, setting the potential of the photosensitive drum 30 to the ground potential). Hereinafter, for convenience of explanation, the removal of the residual potential is referred to as “static elimination”.

  A cleaner 40 is provided on the downstream side of the static elimination lamp 38 in the rotation direction of the photosensitive drum 30. The cleaner 40 includes a cleaning blade 40A and a waste toner bottle 40B. After the transfer process of the toner image by the transfer roll 70 is completed, a region passing through the transfer position on the outer peripheral surface of the photosensitive drum 30 (hereinafter, referred to as a “charge removal target region”) is discharged by the charge removal lamp 38. Residual toner, paper dust, and the like (hereinafter referred to as “residual toner etc.”) on the static elimination target area that has been eliminated by the static elimination lamp 38 are removed by the cleaner 90. That is, residual toner and the like are removed by the cleaning blade 40A coming into contact with the charge removal target area while the photosensitive drum 30 is rotated, and the removed residual toner and the like is stored in the waste toner bottle 40B.

  In the following description, the area to be neutralized that has been neutralized by the neutralizing lamp 38 on the outer peripheral surface of the photosensitive drum 30 rotating at a predetermined speed in the direction of the arc G in FIG. The time until the position is reached is called “time α”. Here, the potential application position refers to a position to which a potential is applied by the charging roll 32A. In the following, for convenience of explanation, the time required from the start of applying the image forming voltage to the charging roll 32A in a state where no voltage is applied until the image forming potential is applied to the charge removal target region. Is “time β” longer than time α. Here, the image forming voltage means a voltage corresponding to the image forming potential, and the voltage applied to the charging roll 32A because the image forming potential is applied to the photosensitive drum 30 by the charging roll 32A. Point to.

  As an example, as illustrated in FIG. 3, the image forming apparatus 10 includes a CPU (Central Processing Unit) 80, a primary storage unit 82, and a secondary storage unit 84. The primary storage unit 82 is a volatile memory (eg, RAM (Random Access Memory)) used as a work area or the like when executing various programs. The secondary storage unit 84 is a non-volatile memory (for example, a flash memory or an HDD (Hard Disk Drive)) that stores in advance a control program for controlling the operation of the image forming apparatus 10 and various parameters. The CPU 80, the primary storage unit 82, and the secondary storage unit 84 are connected to each other via a bus 86.

  The secondary storage unit 84 stores a potential control program 88. The CPU 80 reads the potential control program 88 from the secondary storage unit 84 and develops it in the primary storage unit 82 to execute the potential control program 88. The CPU 80 operates as a control unit according to the present invention by executing the potential control program 88.

  Although the case where the potential control program 88 is read from the secondary storage unit 84 is illustrated here, it is not necessary to store it in the secondary storage unit 84 from the beginning. For example, the potential control program 88 is first stored in an arbitrary portable storage medium such as an SSD (Solid State Drive), an IC card, a magneto-optical disk, or a CD-ROM that is connected to the image forming apparatus 10. It may be left. Then, the CPU 80 may acquire and execute the potential control program 88 from these portable storage media. Further, the potential control program 88 may be stored in a storage unit of an external computer such as a computer or a server device connected to the image forming apparatus 10 via a communication line. In this case, the CPU 30 acquires and executes the potential control program 88 from the external electronic computer.

  The image forming apparatus 10 includes an input / output interface (I / O) 90 that electrically connects the CPU 80 and various input / output devices to control transmission and reception of various information between the CPU 80 and various input / output devices. It has. The image forming apparatus 10 is connected to the I / O 90, and as an input / output device electrically connected to the CPU 80 via the bus 86, a reception unit 92, a display unit 94, and a communication interface (I / F) 96. And an external I / F 98. Further, the image forming apparatus 10 includes an application unit 100, a drive source 106, and an exposure device 34 as input / output devices.

  The accepting unit 92 accepts an operation input from, for example, a user of the image forming apparatus 10 or a supplier who performs maintenance and inspection of the image forming apparatus 10. As an example of the accepting unit 92, an input device such as a transmissive touch panel that is used over a display, an operation button for turning on the power, an operation button for setting various information, and a scroll key can be cited.

  The display unit 94 displays various information. An example of the display unit 94 is a liquid crystal display. Note that the image forming apparatus 10 employs a touch panel display formed by superimposing a touch panel which is a part of the receiving unit 92 on a liquid crystal display as the display unit 94.

  The communication I / F 96 is connected to a communication network such as a LAN (Local Area Network) or the Internet, for example, and transmits / receives various information to / from an information processing apparatus (for example, a personal computer) connected to the communication network. To manage. In this embodiment, the communication I / F 96 receives image formation request information from an information processing apparatus connected to the communication network. The “image formation request information” referred to here is information requesting to form a single image or a plurality of images on a sheet as an example of a recording medium. Image information indicating a power image is included. In the present embodiment, the CPU 80 acquires image formation request information via the communication I / F 96 and temporarily stores the acquired image formation request information in the primary storage unit 82. Then, the exposure unit 34, the application unit 100, and the drive source 106 are controlled based on the image formation request information.

  The external I / F 98 is connected to an external device (for example, a USB memory), and manages transmission / reception of various information between the external device and the CPU 30.

  The application unit 100 is connected to a commercial power source 104 via an AC adapter 102. The application unit 100 is connected to electronic components including the charging roll 32 </ b> A, the charge removal lamp 38, and the developing roll 54. The application unit 100 individually applies voltages to the charging roll 32A and the developing roll 54, thereby charging the charging roll 32A and the developing roll 54 to a potential corresponding to the applied voltage. The application unit 100 turns on the charge removal lamp 38 by applying a voltage to the charge removal lamp 38, and turns off the charge removal lamp 38 by stopping the application of voltage to the charge removal lamp 38 in the lit state.

  The driving source 106 generates a rotational driving force to be applied to various members that rotate by receiving the rotational driving force among the members included in the image forming apparatus 10. Drive source 106 includes a plurality of motors each controlled by CPU 80. As an example of the motors included in the plurality of motors, for example, a motor that applies a rotational driving force to the transport roll in order to rotate a transport roll (not shown) for transporting the paper P can be cited. Further, for example, a motor that applies a rotational driving force to the photosensitive drum 30, a motor that applies a rotational driving force to the charging roll 32 </ b> A, and a motor that applies a rotational driving force to the developing roll 54 can be cited. Further, for example, a motor that applies rotational driving force to the stirring paddle 58, a motor that applies rotational driving force to the stirring screw 60, a motor that applies rotational driving force to the auger 68, and a rotational driving force to the transfer roll 70 are applied. Motor.

  By the way, in the image forming apparatus 10 according to the present embodiment, the image forming voltage is applied to the charging roll 32A while the photoconductive drum 30 is rotating in the direction of the arc G shown in FIG. The drum 30 is charged to an image forming potential (negative potential). An electrostatic latent image based on image formation request information is formed by the exposure device 34 on the charged region to which the image forming potential is applied on the photosensitive drum 30, and the developing roller 54 is formed on the formed electrostatic latent image. Thus, reversal development is performed. In other words, the negative toner held on the developing roll 54 to which the negative potential is applied via the positive carrier is transferred to the electrostatic latent image, and the negative toner is formed on the outer peripheral surface of the photosensitive drum 30. An image is formed. The toner image is transferred to the paper P by the positive potential applied to the transfer roll 70. Most of the residual toner including the toner remaining in the charge removal target region on the outer peripheral surface of the photosensitive drum 30 without being transferred to the paper P is removed by the cleaner 40. However, the residual toner or the like that has passed through the cleaner 70 is positively charged by the transfer roll 70, and therefore adheres to the charging roll 32A.

  In the image forming apparatus 10, as an example, residual toner or the like attached to the charging roll 32 </ b> A is removed during the cleaning operation period 108 shown in FIG. 5. The cleaning operation period 108 starts when the static elimination lamp 38 is turned off (off), and ends when the static elimination lamp 38 is turned on (on) again. When the photosensitive drum 30 rotates once after entering the cleaning operation period 108, a ground potential is applied to the charging roll 32A. When the ground potential is applied to the charging roll 32A, the residual toner on the charging roll 32A is transferred to the photosensitive drum 30 due to the potential difference between the charging roll 32A and the photosensitive drum 30, and the residual toner on the charging roll 32A is removed. Is done.

  However, as shown in FIG. 5 as an example in order to end the cleaning operation period 108, when the static elimination lamp 38 is turned on, the static elimination target area of the photosensitive drum 30 is eliminated. As described above, the potential reversal period 110 occurs. The potential reversal period 110 refers to a period in which the potential relationship between the photosensitive drum 30 (for example, a neutralization target area) and the developing roll 54 is temporarily reversed. For this reason, when the charge removal target area reaches the developer transfer position, the negative polarity toner held on the developing roll 54 may be transferred to the charge removal target area regardless of the image forming period. Although the potential of the developing roll 54 can be made to follow the potential fluctuation of the photosensitive drum 30, the reverse phenomenon of the potential relation between the outer peripheral surface of the photosensitive drum 30 and the developing roll 54 can be suppressed. It is difficult to make the potential of the current follow the instantaneous potential fluctuation.

  Therefore, in the image forming apparatus 10 according to the present embodiment, for example, the potential control process illustrated in FIG. 4 is performed with the start of the cleaning operation period 108 illustrated in FIG. 6. The potential control process is performed by the image forming apparatus 10 when the CPU 80 executes the potential control program 88. Hereinafter, for convenience of explanation, a case where the photosensitive drum 30 rotates in the direction of the arc G shown in FIG. 1 will be described. In the following, for convenience of explanation, a case where the paper P is not transported and a ground potential is applied to the transfer roll 70 will be described.

  In the potential control process shown in FIG. 4, first, in step 150, the CPU 80 determines whether or not a condition (cleaning start condition) for starting removal of residual toner and the like from the charging roll 32A is satisfied. The cleaning start condition is, for example, a condition that the photosensitive drum 30 makes one revolution after the cleaning operation period 108 starts, or a condition that the photosensitive drum 30 makes one revolution after the cleaning operation period 108 starts. It refers to the condition that time has passed. If the cleaning start condition is not satisfied in step 150, the determination is negative and the determination in step 150 is performed again. In step 150, if the cleaning start condition is satisfied, the determination is affirmative and the routine proceeds to step 152.

  In step 152, the CPU 80 controls the application unit 100 to stop the application of alternating current to the charging roll 32 </ b> A, and then proceeds to step 154.

  By the way, when the potential of the charging roll 32A is changed to the ground potential as shown in FIG. 5 as an example, discharge by the charging roll 32A and the photosensitive drum 30 occurs. When discharge occurs, as shown in FIG. 8 as an example, a potential decrease period 112 in which the potential of the photosensitive drum 30 fluctuates to the ground potential side occurs.

  Therefore, in step 154, the CPU 80 controls the application unit 100 to reduce the direct current applied to the charging roll 32A to a predetermined voltage value as shown in FIG. Migrate to The predetermined voltage value is an example of the magnitude of the dirt removal voltage according to the present invention. The predetermined voltage value refers to, for example, a voltage value (for example, −200 V) that does not generate discharge due to a potential difference between the charging roll 32A and the photosensitive drum 30. In this way, by reducing the direct current applied to the charging roll 32A to the predetermined voltage value in step 154, as shown in FIG. 9 as an example, as compared with the case shown in FIG. Potential fluctuation is suppressed.

  Further, since the application of alternating current, which has the function of causing the potential of the photosensitive drum 30 to follow the direct current voltage value in step 152, is stopped, the application of direct current is suppressed in step 154. Potential fluctuation (potential fluctuation toward the ground potential side) is suppressed.

  In step 156, the CPU 80 determines whether or not a condition for ending the cleaning operation period 108 (cleaning end condition) is satisfied. The cleaning end condition is, for example, a condition that the photosensitive drum 30 has made two revolutions after the completion of the processing in step 154, or a condition that the photosensitive drum 30 has to make two revolutions after the completion of the processing in step 154. It refers to the condition that time has passed. If the cleaning end condition is satisfied in step 156, the determination is affirmed and the routine proceeds to step 158. If the cleaning end condition is not satisfied in step 156, the determination is negative and the determination in step 156 is performed again.

  In step 158, the CPU 80 starts applying the adjustment direct current to the charging roll 32 </ b> A using the application unit 100 as shown in FIG. 6 as an example. The adjustment direct current is, for example, a step of applying the alternating current to the charging roll 32A in step 160 to be described later, thereby removing the charge removal target area from the potential of the developing roll 54 (hereinafter referred to as “adjustment”). This refers to the direct current that is charged to “potential”. Note that the adjustment potential refers to, for example, a potential corresponding to an image forming potential. As described above, the use of the potential corresponding to the image forming potential as the adjustment potential is more significant when the cleaning operation period 108 transits to the image forming period than when the potential corresponding to the image forming potential is not used. This is advantageous in that it is not necessary to adjust the potential.

  In the next step 160, the CPU 80 starts applying an alternating current to the charging roll 32 </ b> A using the applying unit 100. In this way, by applying the alternating current to the charging roll 32A in a state where the adjustment direct current is applied, the adjustment potential (for example, −700 V) is applied to the charge removal target region when the charge removal target region reaches the potential application position. ) Is given. Further, by starting the application of alternating current in step 160 after the application of the adjustment direct current is started in step 158, the photosensitive drum 30 is compared with the case where the application of alternating current is not delayed after the start of the application of direct current. Local potential fluctuations are suppressed.

  Next, in step 162, the CPU 80 determines whether or not a condition for turning on the charge removal lamp 38 (charge removal lamp on condition) is satisfied. The static elimination lamp on condition refers to, for example, a condition that time γ (= time β−time α) has elapsed since the completion of the process of step 160. Here, a time obtained by subtracting the time α from the time β is adopted as the time γ. However, the present invention is not limited to this, and the time γ may be longer than the time obtained by subtracting the time α from the time β. Good. That is, the time γ is a standby time (application) where the adjustment potential is applied to the static elimination start area when the static elimination start area (static elimination start area) of the static elimination target area reaches the potential application position. The time required to secure the time required from the start until the adjustment potential is applied may be used.

  In step 162, if the static elimination lamp on condition is satisfied, the determination is affirmed, and the routine proceeds to step 164. In step 162, if the static elimination lamp on condition is not satisfied, the determination is negative and the determination in step 162 is performed again.

  In step 164, the CPU 80 turns on the charge removal lamp 38, and then proceeds to step 166. Since the adjustment potential is applied to the charge removal target area when the charge removal target area that has been discharged by the process of Step 164 reaches the potential application position, as shown in FIG. 9 as an example, the photosensitive member is compared with the case shown in FIG. Inversion of the potential relationship between the drum 30 and the developing roll 54 is suppressed. In the example shown in FIG. 9, the case where the direct current applied to the charging roll 32A is reduced to the predetermined voltage value in step 154 is illustrated. However, the direct current applied to the charging roll 32A in step 154 is reduced to the ground voltage. You may reduce to a value. In this case, the surface potential of the photosensitive drum 30 varies as shown in FIG. 10 as an example, and the potential relationship between the photosensitive drum 30 and the developing roll 54 is suppressed from being reversed as compared with the case shown in FIG. .

  In the example shown in FIG. 8, the potential relationship between the photosensitive drum 30 and the developing roll 54 is reversed because the potential of the charging roll 32 </ b> A is higher than the area of the static elimination target area where static elimination is started. This is because the grant was not in time. In contrast, in the image forming apparatus 10 according to the present embodiment, the charge removal lamp 38 is turned on in step 164 on condition that the charge removal lamp on condition is satisfied in step 162. Therefore, a situation in which the application of the potential by the charging roll 32A is not in time for the area of the static elimination target area that has started to be neutralized is avoided, and the static elimination target area including the area where the static elimination is started is included. On the other hand, an adjustment potential is applied by the charging roll 32A.

  In step 166, the CPU 80 determines whether or not image formation request information is stored in the primary storage unit 82. In step 166, when the image formation request information is not stored in the primary storage unit 82, the determination is affirmed and the process proceeds to step 168. If the image formation request information is stored in the primary storage unit 82 in step 166, the determination is negative and the potential control process is terminated.

  In step 168, the CPU 80 controls the application unit 100 to sequentially stop the application of voltage to the charging roll 32A and the application of voltage to the developing roll 54, as shown in FIG. Migrate to The stop of the voltage application to the charging roll 32A is preferably performed by staircase control (control that lowers the voltage value stepwise (for example, at a predetermined time interval)). Further, the time from the start of the voltage application stop to the charging roll 32A to the start of the voltage application stop to the developing roll 54 is, for example, a time corresponding to the phase difference from the charging roll 32A to the developing roll 54. .

  In the next step 170, the CPU 80 determines whether or not a condition for turning off the charge removal lamp 38 (charge removal end condition) is satisfied. The neutralization termination condition refers to, for example, a condition that the time required for one rotation of the photosensitive drum 30 has elapsed since the application of voltage to the developing roll 54 was stopped in step 168. In step 170, if the static elimination end condition is satisfied, the determination is affirmed and the routine proceeds to step 172. In step 170, if the static elimination end condition is not satisfied, the determination is negative and the determination in step 170 is performed again.

  In step 172, the CPU 80 controls the application unit 100 to turn off the charge removal lamp 38 as shown in FIG. 7 as an example, and then ends the potential control process.

  As described above, in the image forming apparatus 10, when the cleaning operation period 108 ends with the start of charge removal, before the charge removal target area reaches the developer transfer position with respect to the charge removal target area. An adjustment potential of the potential polarity of the developing roll 54 is applied. As a result, as compared with the case where the neutralization target region in the neutralization state reaches the developer transfer position, the leakage of toner from the developing roll 54 due to the potential fluctuation of the photosensitive drum 30 corresponding to the neutralization is suppressed.

  Further, in the image forming apparatus 10, when the cleaning operation period 108 ends with the start of static elimination, the charging roll 32 </ b> A is controlled so that the adjustment potential is applied at the potential application position with respect to the static elimination target area. The Thereby, compared with the case where the charging roll 32A is not controlled so that the adjustment potential is applied to the neutralization target region at the potential application position, the adjustment potential is applied to the neutralization target region with a simple configuration.

  Further, in the image forming apparatus 10, when the cleaning end condition is satisfied, the alternating current is superimposed and applied after the adjustment direct current is applied to the charging roll 32 </ b> A. Thereby, the potential fluctuation of the photosensitive drum 30 is suppressed as compared with the case where the alternating current is not superimposed and applied after the adjustment direct current is applied to the charging roll 32A.

  Further, in the image forming apparatus 10, when the cleaning start condition is satisfied, the application of direct current to the charging roll 32 is suppressed after the application of alternating current is suppressed. Thereby, the potential fluctuation of the photosensitive drum 30 is suppressed as compared with the case where the application of the direct current is not suppressed after the application of the alternating current to the charging roll 32 is suppressed.

  In the image forming apparatus 10, a predetermined current value that avoids discharge by the photosensitive drum 30 and the charging roll 32 </ b> A is adopted as the DC voltage value applied to the charging roll 32 when the cleaning start condition is satisfied. Has been. As a result, the potential of the photosensitive drum 30 is discharged as compared to the case where the predetermined current value that avoids the discharge by the photosensitive drum 30 and the charging roll 32A is not used as the DC voltage value applied to the charging roll 32. As a result, fluctuation to the ground potential side is suppressed.

  In the above embodiment, as an example, as shown in FIGS. 8 to 10, the potential of the photosensitive drum 30 is controlled so as not to differ before and after the cleaning operation period 108, but the present invention is not limited to this. It is not something. For example, as shown in FIGS. 11 to 13, when the cleaning operation period 108 elapses, the potential of the photosensitive drum 30 is higher than the potential before the cleaning operation period 108 is started (more negative potential). ). Further, in this case, the photosensitive drum is held so that the potential difference between the developing roll 54 and the photosensitive drum 30 is maintained at a predetermined potential difference (for example, about −100 V) (as shown in FIGS. 11 to 13 as an example). It is preferable to follow the potential fluctuation of the body drum 30. Note that the potentials of the charging roll 32A and the developing roll 54 after the cleaning operation period 108 has elapsed are determined by the voltage values of the voltages applied to the charging roll 32A and the developing roll 54.

  In the above embodiment, the example in which the adjustment potential is applied to the photosensitive drum 30 by the charging roll 32A has been described. However, the present invention is not limited to this. For example, as illustrated in FIG. An adjustment potential may be applied to the drum 30. For example, as illustrated in FIG. 14, the auxiliary charging roll 140 may be disposed downstream of the charging roll 32 </ b> A and upstream of the developing roll 54 in the rotational direction of the photosensitive drum 30. In this case, the CPU 80 may control the voltage applied to the auxiliary charging roll 140 so that the adjustment potential is applied to the photosensitive drum 30.

  In the above embodiment, the case where the application of the adjustment direct current is started before the static elimination lamp 38 is turned on in step 164 is exemplified, but the present invention is not limited to this. In step 164, the application of the adjustment direct current is started before the static elimination lamp 38 is turned on. The application of the adjustment direct current is not started before the static elimination lamp 38 is turned on. This is because the application of the adjustment potential to the part (region at the start of static elimination) is not in time. If the adjustment potential is not applied in time, for example, the adjustment potential is not applied to a part of the charge removal target area (area at the start of charge removal). However, even if the application of the adjustment direct current to the charging roll 32A is started after the static elimination lamp 38 is turned on, if the adjustment potential is applied to the static elimination target area in time, the charging roll is turned on after the static elimination lamp 38 is turned on. You may start application of adjustment direct current with respect to 32A. In this case as well, it is preferable to apply an alternating current to the adjusted direct current in an applied state after the adjusted direct current is applied.

  In the above embodiment, the case where the direct current is reduced without performing the staircase control in step 154 is exemplified, but the present invention is not limited to this, and the voltage value may be reduced by the staircase control. Further, the voltage value of the adjusted direct current applied in step 158 may be increased by staircase control.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 30 Photosensitive drum 38 Static remover 54 Developing roll 80 CPU
140 Auxiliary charging roll

Claims (5)

A latent image is formed on the image carrier, and a potential for transferring the developer to the latent image by a potential difference at a developer transfer position from a holding unit that holds the developer is applied to the image carrier at the potential application position. Granting means;
A neutralization unit that performs neutralization before the neutralization target region reaches the potential application position with respect to the neutralization target region that has passed through the transfer position of the image carrier,
When the state of removing dirt from the applying means due to a potential difference generated on the condition that the charge removal is stopped is canceled by the start of charge removal, the charge removal target region is the charge removal target region. Control means for controlling so that an adjustment potential of the potential polarity of the holding means is applied by applying an alternating current after a direct current is applied to the applying means before reaching the developer transfer position. When,
An image forming apparatus including: A latent image is formed on the image carrier, and a potential for transferring the developer to the latent image by a potential difference at a developer transfer position from a holding unit that holds the developer is applied to the image carrier at the potential application position. Granting means;
A neutralization unit that performs neutralization before the neutralization target region reaches the potential application position with respect to the neutralization target region that has passed through the transfer position of the image carrier,
When the state of removing dirt from the applying means due to a potential difference generated on the condition that the charge removal is stopped is canceled by the start of charge removal, the charge removal target region is the charge removal target region. Control is performed so that an adjustment potential of the potential polarity of the holding unit is applied before reaching the developer transfer position, and a superimposed voltage in which direct current and alternating current are superimposed is applied from the applying unit to the applying unit. When transitioning to a state to remove dirt, control means for controlling the application means to suppress the application of direct current after the application of alternating current is suppressed,
An image forming apparatus including: When the control unit releases the state of removing dirt from the applying unit by the start of the static elimination, the adjustment potential is applied at the potential application position to the static elimination target region where the static elimination has been performed. the image forming apparatus according to claim 1 or claim 2 for controlling said applying means. The stain removal voltage applied to application means, the image forming apparatus according to any one of claims 1 to 3 is a voltage discharge by the image carrier and said applying means is avoided. Computer
The program for functioning as a control means in the image forming apparatus of any one of Claims 1-4 .

Images