JP2007322798A - Image forming apparatus, and control method for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can be made low in cost and small in occupancy space by decreasing the number of components, and to provide a control method therefor. <P>SOLUTION: The image forming apparatus 10 has an image carrier 40 which carries a toner image, a transfer member 62 which transfers the toner image carried on the image carrier 40 to a sheet, a transfer voltage applying means 86 of applying a voltage to the transfer member 62, a resist roller 24 which temporarily stops the sheet and carries the sheet to between the image carrier 40 and transfer member 62 in suitable timing, a resist roller voltage applying means 82 of applying a voltage to the resist roller 24, a sheet resistance value measuring means 84 of measuring the resistance value of the sheet passing by the resist roller based upon the voltage applied to the resist roller voltage applying means 82, and a voltage control means of controlling the voltage applied by the transfer voltage applying means based upon the resistance value measured by the sheet resistance value measuring means 84. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile, and a control method for the image forming apparatus.

  In this type of image forming apparatus, the image carrier is uniformly charged by a charging device, a latent image is formed by an exposure device, the latent image is visualized with toner by a developing device, and the toner image is formed on a sheet by a transfer device. Is known as a xerographic system in which toner is transferred onto a sheet by a fixing device. In such an image forming apparatus, the optimum value of the transfer voltage varies depending on the surrounding environment such as temperature and humidity and the type of sheet used. For this reason, it is well known to measure the resistance value of a sheet and control the transfer voltage based on the measured resistance value of the sheet (Patent Document 1).

JP-A-8-104286

  However, in the prior art, a special conductive roller is provided to detect the sheet resistance, and the resistance value of the sheet passing through the conductive roller is measured. Therefore, since it is necessary to provide the conductive roller separately from the conveying roller, there is a problem that the number of parts is increased, the cost is increased, and space is required.

  An object of the present invention is to provide an image forming apparatus capable of reducing the number of parts, reducing costs, and reducing the space, and a control method thereof.

  The first feature of the present invention is that an image carrier carrying a toner image, a transfer member for transferring the toner image carried on the image carrier to a sheet, and applying a voltage to the transfer member. A transfer voltage applying unit, a registration roller for temporarily stopping the sheet and taking the timing to convey the sheet between the image carrier and the transfer member, and a registration roller voltage applying unit for applying a voltage to the registration roller; The sheet resistance value measuring means for measuring the resistance value of the sheet passing through the registration roller based on the voltage applied by the registration roller voltage applying means, and the resistance value measured by the sheet resistance value measuring means. And an image forming apparatus having voltage control means for controlling an applied voltage of the transfer voltage applying means. Therefore, since the resistance value of the sheet can be measured using the registration roller, the number of parts can be reduced, the cost can be reduced, and the space can be reduced.

  The image forming apparatus according to the present invention preferably further includes a registration roller resistance value measuring unit that measures a resistance value of the registration roller when the sheet does not pass. By measuring the resistance value of the registration roller when passing through the non-sheet, the environmental state relating to temperature and humidity can be measured.

  The image forming apparatus according to the present invention preferably includes a charging unit for charging the image carrier, and a charging voltage of the charging unit based on the resistance value of the registration roller measured by the registration roller resistance value measuring unit. And charging voltage control means for controlling.

  Preferably, the image forming apparatus according to the present invention has a developing unit that develops the latent image formed on the image carrier and a resistance value of the registration roller measured by the registration roller resistance value measuring unit. Bias voltage control means for controlling the bias voltage of the developing means on the basis thereof.

  Preferably, the image forming apparatus according to the present invention includes a static elimination unit that neutralizes the image carrier, and the neutralization unit based on a resistance value of the registration roller measured by the registration roller resistance measurement unit. And a static elimination voltage control means for controlling the voltage.

  Preferably, in the image forming apparatus according to the present invention, there are a plurality of transfer members, and the voltage control unit controls voltages to the plurality of transfer members.

  The second feature of the present invention is that an image carrier on which a toner image is carried, a transfer member for transferring the toner image carried on the image carrier to a sheet, the sheet is temporarily stopped, and the timing is adjusted. A registration roller that conveys the sheet between the image carrier and the transfer member, and measures a resistance value of the sheet passing through the registration roller, and the transfer is performed based on the measured resistance value. An image forming apparatus control method for controlling a voltage applied to a member.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12. A paper feeding device 14 is disposed below the image forming apparatus main body 12, and a paper discharge unit 16 is disposed above the image forming apparatus main body 12. Is formed.

  The paper feeding device 14 includes a paper tray 18, and a large number of sheets are stacked on the paper tray 18. A feed roll 20 is disposed on the upper end of the paper tray 18, and a roll 22 is provided facing the feed roll 20. The uppermost sheet on the sheet tray 18 is picked up by the feed roll 20, and the sheet is turned and conveyed by the cooperation of the feed roll 20 and the cutting roll 22.

  The sheet conveyed from the sheet tray 18 is temporarily stopped by the registration roller 24, and at a predetermined timing, between the image carrier unit 26 and the transfer unit 28 and through the fixing device 30, the sheet discharge unit 16 by the sheet discharge roller 32. Is discharged.

  At least one roll of the registration roller 24 is made of a semiconductive member such as polyurethane. A voltage is applied to the registration roller 24 as will be described later. The resistance value of the registration roller 24 varies with environmental changes such as temperature and humidity. Further, the resistance value of the sheet can be measured by applying a voltage when the sheet passes through the registration roller 24.

  An image carrier unit 26, a transfer unit 28, a power supply unit 34, and a control unit 36 are disposed in the image forming apparatus main body 12. In the image carrier unit 26, for example, four image carriers 40 are rotatably supported. Around each image carrier 40, a charging member 42 as a charging unit provided with a charging roll for uniformly charging the image carrier 40, and a latent image written on each image carrier 40 are developed with a developer (toner). ), A developing device 44 as developing means, a charge removing member 46 as charge removing means for discharging the image carrier 40 after transfer, and development for removing developer remaining on the image carrier 40 after transfer. And a cleaning device 48 as an agent removing means.

  The four toner boxes 50 are connected to the back side of the image carrier unit 26. Each toner box 50 is for magenta, yellow, cyan, and black, and a toner supply unit 54 and a toner collection unit 52 are integrated. The toner supply unit 54 is connected to the developing device 44 to supply each color toner to the developing device 44, and the toner recovery unit 52 is connected to the cleaning device 48 to collect each color toner.

  Each of the optical writing devices 56 is composed of a laser exposure device, and is disposed on the back side of the image carrier unit 26 at a position corresponding to each image carrier 40, with respect to the uniformly charged image carrier 40. A latent image is formed by laser irradiation.

  The transfer unit 28 is on the front side of the image carrier unit 26 and is arranged in the vertical direction facing the image carrier unit 26. In the transfer unit 28, a conveyance belt 60 is hung on two support rolls 58 provided in the vertical direction. Further, a transfer member 62 is provided so as to face each image carrier 40 with the conveyance belt 60 interposed therebetween. The image carrier unit 26 can be attached to and detached from the image forming apparatus main body 12 by tilting the transfer unit 28.

  Accordingly, each image carrier 40 is uniformly charged by the charging device 42, a latent image is formed by the optical writing device 56, and the latent image is visualized by toner by the developing device 44. The toner image formed on each image carrier 40 is transferred onto the conveyed paper by the transfer member 62 of the transfer unit 28 in order from below, and is fixed on the paper by the fixing device 30.

  2 and 3, an outline of the electrical system of the image forming apparatus 10 is shown. The control unit 36 described above includes a voltage control unit 64 and a voltage storage unit 66. The voltage control unit 64 includes a registration roller voltage control unit 68 that supplies a voltage to the registration roller 24, and a charging member 42, a developing device 44, a charge removal member 46, and a transfer member based on a control signal from the registration roller voltage control unit 68. 62 (in FIGS. 2 and 3, 62Y for a yellow (Y color) transfer member, 62M for a magenta (M color) transfer member, 62C for a cyan (C color) transfer member, and a black (K color) transfer member. Is provided with YMCK, such as 62K.) Each part voltage control unit 70 for controlling the voltage to. That is, each voltage control unit 70 includes a Y color transfer voltage control unit 72Y, an M color transfer voltage control unit 72M, a C color transfer voltage control unit 72C, a K color transfer voltage control unit 72K, and a charge removal voltage control unit. 74, a charging voltage controller 76, and a developing voltage controller 78. The voltage storage unit 68 stores the voltage set by the registration roller voltage control unit 68.

  The power supply unit 34 described above has a registration roller voltage circuit 80. The registration roller voltage circuit 80 includes a constant voltage output circuit 82 that applies a constant voltage to the registration roller 24 and a current detection circuit 84 that detects a current flowing through the registration roller 24. The detection result of the current detection circuit 84 is fed back to the registration roller voltage control unit 68.

  The power supply unit 34 controls the Y color transfer voltage circuit 86Y and the M color transfer voltage control unit 72Y that supply a voltage adjusted based on the control signal of the Y color transfer voltage control unit 72Y to the Y color transfer member 62Y. The voltage adjusted based on the signal is supplied to the Y color transfer member 62M, and the voltage adjusted based on the control signal of the C color transfer voltage control unit 72C is supplied to the C color transfer member 62C. There is provided an M color transfer voltage circuit 86K for supplying a voltage adjusted based on the control signals of the C color transfer voltage circuit 86Y and the K color transfer voltage control unit 72K to be supplied to the K color transfer member 62K. Further, the power supply unit 34 is adjusted based on the control signal of the charge voltage control unit 76 and the charge voltage control unit 76 that supplies the voltage adjusted based on the control signal of the charge control unit 74 to the charge removal member 46. A charging voltage circuit 90 that supplies a voltage to the charging member 42 and a developing voltage circuit 92 that supplies a bias voltage (DC−) adjusted based on a control signal from the developing voltage control unit 78 to the developing device 44 are provided.

  A K color AC power supply circuit 94K is connected to the Y color developing device, a YMC AC power supply circuit 94YMC is connected to the Y, M, and C color developing devices, and AC current is supplied to each developing device. A voltage on which direct current is superimposed is applied.

  In this embodiment, the environmental state is detected by measuring the resistance value of the registration roller 24 when the sheet does not pass. However, as another embodiment, as shown in FIG. An environmental condition may be detected by providing a humidity sensor 96 inside or outside the machine.

  4 to 6, the control flow in the embodiment of the present invention is shown. As shown in FIG. 4, first, in step S100, environment setting is performed for each part of the image forming apparatus. When the environment setting in step S100 is completed, sheet printing control is executed in step S200, and the process ends.

  As shown in FIG. 5, in step S100, the environment setting is performed by applying a constant voltage from the constant voltage output circuit 82 to the registration roller 24 before the sheet is supplied in step S102. In the next step S104, the current flowing through the registration roller 24 is detected by the current detection circuit 84. By this step S104, the resistance value of the registration roller 24 when the sheet does not pass can be acquired. Since the resistance value of the registration roller 24 varies according to environmental changes such as temperature and humidity, the environmental state can be detected by measuring the resistance value of the registration roller 24. The environmental conditions may be divided into zones such as high temperature-high humidity, high temperature-low humidity, low temperature-high humidity, and low temperature-low humidity, and it may be determined which zone the current environment belongs to, and each is detected numerically. May be. In the next step S106, a voltage determined for each environment is applied to each part, that is, the registration roller 24, the charging member 42, the developing device 44, the charge removing member 46, and the transfer members 62Y, 62M, 62C, and 62K.

  As shown in FIG. 6, the sheet printing control in step S <b> 200 starts sheet conveyance by driving the feed roll 20 in step 202. In the next step 204, driving of the registration roller 24 is started after a predetermined time has elapsed from the start of sheet conveyance. Until the predetermined time elapses, the driving of the registration roller 24 is stopped, a loop is formed on the sheet, the skew of the sheet is corrected, and the driving of the registration roller 24 is started after the predetermined time elapses so that the image forming timing is reached. Sheet conveyance can be adjusted.

  In the next step 206, a constant voltage is applied from the registration roller 24 constant voltage output circuit 82. In the next step 208, the current in the sheet sandwiched between the registration rollers 24 as a result of applying the voltage to the registration rollers 24 in step 206 is detected as a signal from the current detection circuit 84. The detection of the current in the sheet may be performed not only once but also a plurality of times, and the average value may be obtained. In the next step 210, a transfer voltage corresponding to the sheet resistance value is determined for each color. That is, since it is necessary to adjust the transfer voltage to an optimum value depending on the type of the sheet, an adjustment value of the transfer voltage based on the sheet resistance value is obtained.

  In the next step 212, the voltage applied to each transfer member 62Y, 62M, 62C, 62K is corrected with the in-sheet transfer voltage obtained in step S210. The corrected transfer voltage is applied to each transfer member 62Y, 62M, 62C, 62K, and the toner image is transferred to the sheet by applying the transfer voltage to the sheet passing through the transfer members 62Y, 62M, 62C, 62K. In the next step S214, the driving of the feed roll 20 is stopped when the trailing edge of the previously conveyed sheet passes through the feed roll 20, and in the next step S216, the trailing edge of the previously conveyed sheet is the registration roller. At the time when it passes 24, the driving of the registration roller 24 is stopped. In step S218, it is determined whether printing of the set number of sheets has been completed. If printing of the set number of sheets has not been completed, the process returns to step S202, and printing of the set number of sheets has been completed. If so, the process ends.

  In the above embodiment, the voltage of the charging member, the developing device, the charge removal member, and the transfer member is controlled by detecting the resistance value of the registration roller 24. However, the present invention is not limited to this. Alternatively, the temperature of another member or device, for example, a fixing device may be controlled.

  As described above, the present invention can be used in an image forming apparatus that performs control by obtaining a sheet resistance value.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. 1 is a circuit diagram showing an electrical system used in an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a control unit and a power supply unit in an electrical system used in the image forming apparatus according to the embodiment of the present invention. 3 is a flowchart illustrating an overall control flow of the image forming apparatus according to the embodiment of the present invention. 4 is a flowchart illustrating a control flow for performing environment-friendly setting of the image forming apparatus according to the embodiment of the present invention. 5 is a flowchart illustrating a control flow for performing sheet printing control of the image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 26 Image carrier unit 40 Image carrier 42 Charging member 44 Developer 46 Destaticizing member 62 Transfer member

Claims (7)

 An image carrier on which a toner image is carried; a transfer member that transfers the toner image carried on the image carrier to a sheet; transfer voltage application means that applies a voltage to the transfer member; A registration roller that conveys a sheet between the image carrier and the transfer member in time, a registration roller voltage application unit that applies a voltage to the registration roller, and a voltage that is applied by the registration roller voltage application unit And a voltage for controlling the applied voltage of the transfer voltage applying means based on the resistance value measured by the sheet resistance value measuring means. And an image forming apparatus.   The image forming apparatus according to claim 1, further comprising a registration roller resistance value measuring unit configured to measure a resistance value of the registration roller when the sheet does not pass.   A charging unit configured to charge the image bearing member; and a charging voltage control unit configured to control a charging voltage of the charging unit based on a resistance value of the registration roller measured by the registration roller resistance value measuring unit. Item 3. The image forming apparatus according to Item 2.   Developing means for developing the latent image formed on the image carrier, and bias voltage control means for controlling the bias voltage of the developing means based on the resistance value of the registration roller measured by the registration roller resistance measurement means The image forming apparatus according to claim 2, further comprising:   And a static elimination voltage control unit for controlling a voltage of the static elimination unit based on a resistance value of the registration roller measured by the registration roller resistance measurement unit. 5. The image forming apparatus according to any one of 2 to 4.   6. The image forming apparatus according to claim 1, wherein there are a plurality of transfer members, and the voltage control unit controls voltages to the plurality of transfer members.   An image carrier on which a toner image is carried, a transfer member for transferring the toner image carried on the image carrier to a sheet, a sheet is temporarily stopped, and the timing between the image carrier and the transfer member An image forming apparatus for measuring a resistance value of a sheet passing through the registration roller and controlling a voltage applied to the transfer member based on the measured resistance value. Control method.

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