JP2010204212A - Image forming apparatus, image formation control method, image formation control program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, an image formation control method, an image formation control program and a recording medium, for transferring a developer image on a photoreceptor to a member to be recorded by a transfer current or a transfer voltage supplied to a transfer roller. <P>SOLUTION: In a printer device 1, when the transfer current is output to the photoreceptor 20 from a transfer high-voltage power supply section through the transfer roller 23 coming into contact with the photoreceptor 20, to transfer a toner image on the photoreceptor 20 to a paper P, a controller detects a flow-in current flowing between the transfer roller 23 and the photoreceptor 20 before the transfer current is supplied to the photoreceptor 20 from the transfer roller 23 and corrects a transfer control signal output to the transfer high-voltage power supply section on the basis of the flow-in current, to properly output the transfer current from the transfer high-voltage power supply section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, an image forming control method, an image forming control program, and a recording medium, and more specifically, an image forming apparatus that supplies a stable transfer voltage or transfer current to a photoreceptor at low cost, an image forming control method, The present invention relates to an image formation control program and a recording medium.

  2. Description of the Related Art Recently, image forming apparatuses such as copying machines, facsimile machines, and printers are performing image formation using an electrophotographic system. An image forming apparatus that forms an image by such an electrophotographic method forms an electrostatic latent image by irradiating a uniformly charged photoconductor with a laser beam modulated by image data. The formed electrostatic latent image is developed with toner (developer) in a developing unit, and transferred from a paper supply unit to a sheet conveyed between a photosensitive member and a transfer roller (transfer member) from a transfer power source to a transfer roller. A toner image is formed on the sheet by transferring a toner image on the photosensitive member by applying a high-voltage transfer bias (voltage, current) via the. In the electrophotographic image forming apparatus, the sheet on which the toner image is transferred in this manner is conveyed by the fixing unit while being heated and pressurized, thereby fixing the toner image on the sheet.

  Such an electrophotographic image forming apparatus requires different voltages and currents for charging the photosensitive member, developing the electrostatic latent image, transferring the toner image to the paper, fixing and transporting the paper, etc. Necessary voltages and currents are supplied from the high-voltage power supply unit.

  The transfer roller is generally formed of a semiconductive rubber material or the like, and its resistance value varies greatly depending on the environment. That is, the resistance value of the transfer roller is large in a low humidity environment, and the resistance value is small in a high humidity environment. Further, the resistance value between the transfer roller and the photoconductor varies depending on the type of paper. Therefore, conventionally, in the case of a constant current method in which a transfer bias current is applied via a transfer roller by constant current control, the transfer high-voltage power supply unit performs transfer by changing the set value of the transfer current for each sheet, and a constant voltage. In the case of a constant voltage method in which a transfer bias voltage is applied via a transfer roller by control, transfer is performed by changing the set value of the transfer voltage for each sheet.

  That is, in the image forming apparatus, the transfer high-voltage power supply unit is connected to the primary side of the high-voltage transformer, the primary side of the high-voltage transformer, and turned on / off by a pulsed control signal, the secondary-side output of the high-voltage transformer, and the preset value. A feedback circuit for comparing the output feedback value according to the output target and the control signal and outputting a drive pulse for turning the transistor on / off through the primary side of the high-voltage transformer to the transistor. By controlling the ON time by PWM (Pulse Wide Modulation), the drive current flowing on the primary side of the high voltage transformer is controlled, and the secondary output generated on the secondary side of the high voltage transformer is transferred or transferred. It outputs as current (hereinafter referred to as transfer output (current, voltage) as appropriate), and the transfer output (current, voltage) is output according to the output target. The output feedback value fed back is compared with the control signal to converge the transfer output (current, voltage) to the target value. Such a self-excited oscillation type high-voltage power supply unit is widely used because it has a small number of parts and can be reduced in cost.

  In an electrophotographic image forming apparatus, depending on the potential of the photoconductor, an inflow current that flows into the photoconductor from the transfer high-voltage power supply unit that is not in the output state of the transfer high-voltage or transfer high-voltage current may occur. If this inflow current is generated, the self-excited oscillation circuit of the transfer high-voltage power supply unit may cause a start-up failure. When a start-up failure of the self-excited oscillation circuit of the transfer high-voltage power supply unit occurs, there is a risk of image deterioration such as a transfer current and a transfer voltage being insufficient and an image becoming thin.

  Therefore, conventionally, a constant current transfer high voltage power supply unit equipped with a self-excited oscillation circuit uses a transfer current or transfer voltage for transferring the toner on the photosensitive member to the transfer paper, and a transfer cleaning voltage from the transfer cleaning power supply unit. There has been proposed a technique for supplying the same at the same time and preventing the start-up failure of the self-excited oscillation circuit (see Patent Document 1).

  This transfer cleaning power supply unit transfers a reverse bias to the transfer roller to the transfer roller so that the residual toner on the photoconductor does not adhere in accordance with the rotation start of the photoconductor and the output of the charging bias (voltage, current). A cleaning voltage is applied, and the occurrence of back contamination and the like is suppressed by the transfer cleaning voltage.

  However, in the above prior art, the transfer current or transfer voltage for transferring the toner on the photosensitive member to the transfer paper is transferred at the same time as the transfer cleaning voltage from the transfer cleaning power supply unit and includes a self-excited oscillation circuit. Since the supply current from the power supply unit to the photoconductor suppresses the influence of the flowing current and prevents the self-excited oscillation circuit from starting up poorly, the transfer high-voltage power supply unit including the self-excited oscillation circuit is a constant voltage system. And, it is necessary to use a high-voltage component as a circuit component of the transfer high-voltage power supply unit, which increases the cost, and when the transfer cleaning power supply unit is not provided, it is not possible to prevent the startup failure of the self-excited oscillation circuit, There was a problem of lack of versatility.

  Therefore, the present invention provides an image forming apparatus, an image forming control method, an image forming control program, and a recording medium that supply an appropriate transfer voltage or transfer current while preventing the influence of a flowing current on the transfer power supply means at a low cost and appropriately. The purpose is to provide.

  In order to achieve the above object, the present invention provides a control signal input to a photosensitive member holding a developer image obtained by developing an electrostatic latent image with a developer via a transfer roller in contact with the photosensitive member. When the transfer voltage or transfer current of a predetermined target value generated at a predetermined timing according to the output is output from the output terminal of the transfer power supply means and the developer image on the photosensitive member is transferred to the recording medium, the transfer roller Detects the inflow current flowing between the transfer roller and the photoconductor before the transfer voltage or the transfer current is supplied to the photoconductor, and controls the transfer power supply means based on the inflow current. It is characterized by correcting the signal.

  The transfer power supply unit may generate the transfer voltage or the transfer current by self-oscillating based on the control signal.

  Further, according to the present invention, the feedback means feeds back the output voltage or output current of the output terminal of the transfer power supply means as a feedback signal to the input side of the control signal of the transfer power supply means. The transfer voltage or the transfer current may be controlled based on the signal and the feedback signal, and the current detection unit may detect the inflow current based on the feedback signal.

  In the invention, it is preferable that the transfer power supply means outputs a cleaning voltage having a predetermined output value opposite to the transfer voltage or the transfer current at a predetermined timing before the output timing of the transfer voltage or the transfer current. It is also possible to provide a cleaning power supply means for outputting from the above.

  According to the present invention, before the transfer power supply means supplies the transfer voltage or transfer current to the photoconductor through the transfer roller, the influence of the flowing current flowing between the transfer roller and the photoconductor on the transfer power supply means is inexpensive and appropriate. Therefore, a transfer voltage or a transfer current can be appropriately supplied.

1 is a block diagram of a main part of a printer apparatus to which an embodiment of the present invention is applied. The principal part schematic block diagram of an image creation part. The circuit block diagram of a transfer high voltage power supply part. The figure which shows the relationship between a transcription | transfer output current and a transcription | transfer output feedback signal. FIG. 4 is a timing chart at the start of image formation. Explanatory drawing of an inflow current. FIG. 6 is a diagram illustrating transition of a transfer output potential during image formation. FIG. 6 is a diagram illustrating an example of a transfer current and an actual measurement value of a transfer potential, a voltage drop caused by a transfer roller, and a transfer roller impedance when the photoreceptor surface potential is −942V. The figure which shows the relationship between the transfer current and transfer voltage when a photoreceptor surface potential is -942V. The circuit block diagram of the transfer high voltage power supply part only of a transfer output power supply part. FIG. 11 is a diagram showing transition of a transfer output potential during image formation of the transfer high-voltage power supply unit in FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 11 are diagrams showing an embodiment of an image forming apparatus, an image forming control method, an image forming control program, and a recording medium according to the present invention. FIG. 1 is an image forming apparatus and image forming control according to the present invention. 1 is a block configuration diagram of a printer apparatus 1 as an image forming apparatus to which an embodiment of a method, an image forming control program, and a recording medium are applied.

  In FIG. 1, a printer device 1 includes a controller 2, a ROM (Read Only Memory) 3, a RAM (Random Access Memory) 4, a communication I / F 5, an operation unit 6, an image forming unit 7, a fixing unit 8, and an optical writing unit 9. Etc., and each part is connected by a system bus 10.

  The ROM 3 stores a basic program of the printer apparatus 1, an image formation control processing program, which will be described later, and necessary data. The RAM 4 is backed up by a battery, and the initial setting values and other information of the printer apparatus 1 are stored in the printer. It is retained even when the power of the device 1 is turned off or in the event of a power failure.

  The controller (control means) 2 includes a CPU (Central Processing Unit) and the like, and controls each part of the printer apparatus 1 using the RAM 4 as a work memory based on a program in the ROM 3. The image forming control method of the present invention is executed based on the image forming control processing program.

  That is, the printer apparatus 1 includes a ROM, an EEPROM (Electrically Erasable and Programmable Read Only Memory), an EPROM, a flash memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a CD-RW (Compact Disc Rewritable), a DVD ( An image forming control program for executing the image forming control method of the present invention recorded on a computer-readable recording medium such as a digital video disk (SD), a secure digital (SD) card, or an MO (Magneto-Optical Disc) is read. By being installed in the ROM 3 or the like, it is constructed as an image forming apparatus that executes an image formation control method for appropriately and inexpensively controlling a transfer power source described later. This image formation control program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark), an object-oriented programming language, or the like, and is stored in the recording medium. And can be distributed.

  Further, as will be described later, the ROM 3 holds information in which the transfer output feedback signal Sf has an output relationship proportional to the transfer current in a one-to-one relationship.

  The communication I / F 5 is connected to a network such as a LAN (Local Area Network), for example, and a computer or the like serving as a host device is connected to the printer device 1. The communication I / F 5 transmits and receives data to and from the host device via the network under the control of the controller 2.

  The operation unit 6 includes operation keys and a display for performing various operations necessary for causing the printer device 1 to perform various operations. Under the control of the controller 2, the operation unit 6 displays various types of information to be notified to the user on the display. Various commands and parameters input with the key are acquired and output to the controller 2.

  As shown in FIG. 2, the image forming unit 7 is provided with a charging roller 21, a developing roller 22, a transfer roller 23, a charge eliminating unit (not shown), a cleaning unit, and the like around the photoreceptor 20. The photoconductor 20 is rotationally driven in the counterclockwise direction indicated by an arrow in FIG. 2, and its shaft is in contact with the frame of the printer 1 and is electrically grounded to the frame.

  A charging high voltage power supply unit 24 is connected to the charging roller 21, and the charging high voltage power supply unit 24 supplies a high voltage charging voltage to the charging roller 21 under the control of the controller 2. The charging roller 21 and the charging high-voltage power supply unit 24 function as charging means as a whole.

  A development high voltage power supply unit 25 is connected to the development roller 22, and the development high voltage power supply unit 25 supplies a high development voltage to the development roller 22 under the control of the controller 2. The developing roller 22 and the developing high-voltage power supply unit 25 function as a developing unit as a whole.

  A transfer high-voltage power supply unit 26 is connected to the transfer roller 23, and the transfer high-voltage power supply unit 26 supplies a high-voltage transfer current or transfer voltage to the transfer roller 23 under the control of the controller 2. The transfer high-voltage power supply unit 26 of this embodiment uses a constant current power supply as will be described later, and supplies a high-voltage transfer current to the transfer roller 23.

  As the photoconductor 20 rotates, the photoconductor is neutralized by a neutralizing unit (not shown), and then rotates in contact with the charging roller 21, so that the charging voltage from the charging high-voltage power supply unit 24 is supplied through the charging roller 21. Then, the laser beam LB is uniformly charged and then irradiated with a laser beam LB modulated based on image data from an optical writing unit 9 (not shown) to form an electrostatic latent image on the surface. The developing roller 22 rotates together with the photoconductor 20, and a developing voltage from the developing high voltage power supply unit 25 is supplied through the developing roller 22 to supply toner to the surface of the photoconductor 20 on which the electrostatic latent image is formed. Then, a toner image is formed on the surface of the photoreceptor 20. The printer device 1 further rotates the photosensitive member 20 on which the toner image is formed in the direction of the transfer roller 23, and also feeds paper (covered material) from the paper feeding unit to the transfer nip portion where the transfer roller 23 and the photosensitive member 20 are in contact with each other. The recording medium) P is conveyed, and a transfer current is supplied from the transfer high-voltage power supply unit 26 to the transfer roller 23, whereby the toner image on the photoconductor 20 is transferred to the paper P at the transfer nip portion.

  The printer device 1 forms the image by conveying the paper P on which the toner image has been transferred to a fixing unit 8 (not shown) and heating and pressing the fixing unit 8 to fix the toner image on the paper P. The printer apparatus 1 is provided with a registration roller and a conveyance sensor in front of the transfer nip portion, detects the paper P conveyed to the transfer nip portion by the conveyance sensor, and based on the detection result of the conveyance sensor, The position of the paper P and the toner image on the photoconductor 20 is adjusted by controlling the driving of the roller and carrying the paper P.

  The fixing unit 8 includes, for example, a fixing roller that is driven to rotate in the conveyance direction of the paper P by a driving motor, a pressure roller that rotates with the transfer roller in contact with the fixing roller, and a fixing heater that heats the transfer roller to a predetermined fixing temperature. The toner image is fixed to the sheet P by heating and pressing the sheet P passing through the nip portion between the transfer roller and the pressure roller.

  The optical writing unit (optical writing means) 9 is a light source such as an LED (Light Emitting Diode) that emits a laser beam LB modulated based on data, and is driven to rotate at a rotational angular velocity corresponding to the pixel density and emitted from the light source. A polygon mirror that deflects and reflects the laser beam LB in the main scanning direction, a mirror group that irradiates the photosensitive member 20 with the laser beam LB reflected by the polygon mirror, and the like are provided.

  The transfer high-voltage power supply unit (transfer power supply unit) 26 includes a transfer output power supply unit 30 and a cleaning bias power supply unit (cleaning power supply unit) 40, as shown in FIG. The transfer control signal (control signal) Sp is input from the controller 2 to the cleaning bias power supply unit 40.

  The transfer output power supply unit 30 includes a smoothing circuit 31, a resistor R1, a drive circuit 32, a transistor Tr1, a transformer T1, a smoothing circuit 33, and the like, and is a constant current control power supply unit. Therefore, the transfer high-voltage power supply unit 26 generates a transfer current that is self-excited and controlled at a constant current, and outputs it from the transfer output terminal Wp.

  The smoothing circuit 31 includes a resistor R2 and a capacitor C1, and the transfer control signal Sp is input from the controller 2 to the smoothing circuit 31. The transfer control signal Sp is a pulse signal whose on-time (on-duty) is PWM-controlled by the controller 2. By controlling the on-duty, the transfer output power supply unit 30 of the transfer high-voltage power supply unit 26 transfers the transfer roller 23. This is a signal for variably controlling the supplied transfer current.

  The smoothing circuit 31 outputs the transfer control signal Sp to the drive circuit 32 as a transfer control DC voltage (DC voltage) that is smoothed and stabilized.

  The drive circuit 32 includes an amplifier Ap1, a resistor R3, a feedback resistor R4, and the like. The transfer control DC voltage from the smoothing circuit 31 is input to the amplifier Ap1, and the transfer output feedback current is resisted. The transfer output feedback voltage pulled up by R1 is input to the plus input terminal. The drive circuit 32 outputs the output of the amplifier Ap1 to the primary side of the transformer T1 through the resistor R3 and feeds it back to the negative input terminal to which the transfer control DC voltage is input from the smoothing circuit 31 through the feedback resistor R4. ing. The drive circuit 32 outputs to the primary side of the transformer T1 an output corresponding to the transfer control DC voltage obtained by smoothing the transfer control signal Sp and the transfer output feedback voltage.

  The transformer T1 includes a primary winding Tm1, a base drive winding Tmb, and a secondary winding Tm2. The primary winding Tm1 is applied with a constant voltage Vcc, It is connected to the collector of the transistor Tr1. In the transformer T1, when the primary winding Tm1 is turned on / off (switched) by the transistor Tr1, energy is transmitted to the secondary winding Tm2, and a high-voltage output is generated on the secondary side.

  A smoothing circuit 33 is connected to the secondary winding Tm2 on the secondary side of the transformer T1, and the smoothing circuit 33 includes diodes D1 and D2, capacitors C2 and C3, and resistors R5 and R6.

  The transistor Tr1 is grounded at the emitter, and the base drive winding Tmb of the transformer T1 is connected to the base. The base drive winding Tmb is connected to the output of the amplifier Ap1 via the resistor R3 of the drive circuit 32, and the transistor Tr1 is turned on / off by the drive output of the drive circuit 32.

  When the transformer T1 is turned on by the transistor Tr1, a voltage is applied to the primary winding Tm1, and at the same time, a voltage is generated in the base drive winding Tmb. The voltage generated in the base drive winding Tmb of the transformer T1 when the transistor Tr1 is turned on operates in a direction to further turn on (conduct) the transistor Tr1, and becomes a positive feedback voltage. A voltage is further applied to the primary winding Tm1 of T1. In this case, the voltage of the secondary winding Tm2 of the transformer T1 is reversely applied to the diodes D1 and D2 of the smoothing circuit 33. Therefore, no current flows through the secondary winding Tm2 of the transformer T1, and the primary of the transformer T The current flowing through the winding Tm1 is only the excitation current.

  When the base current flowing from the base drive winding Tmb of the transformer T1 to the base of the transistor Tr1 cannot maintain the saturation of the transistor Tr1, the transistor Tr1 is out of saturation and the collector-emitter voltage Vce increases, and the collector − As the emitter voltage Vce increases, the voltage of the primary winding Tm1 of the transformer T1 decreases, the voltage of the base drive winding Tmb also decreases, and the collector-emitter voltage Vce further increases. This series of changes is positively fed back, and the transistor Tr1 is quickly turned off. Even at the moment when the transistor Tr1 is turned off, the magnetic field is kept the same, and the secondary winding Tm2 also has a current in the direction from the start to the end so as to maintain the same energy as the current flowing in the primary winding Tm1. Flows and diode D1 becomes conductive. When all the energy accumulated in the transformer T1 is transferred to the secondary side (output side), the current of the diode D1 is turned off.

  At this moment, the voltages of the windings Tm1, Tmb, and Tm2 of the transformer T1 become zero, but the transistor Tr1 is turned on again by the output of the drive circuit 32, and the above operation is repeated to continue oscillation. That is, the transfer output power supply unit 30 is a self-excited oscillation type constant current power supply, and outputs a transfer current from the transfer output terminal Wp to the photoconductor 20 via the transfer roller 23.

  On the other hand, the cleaning bias power supply unit 40 includes a smoothing circuit 41, a cleaning bias drive circuit unit 42, a transformer T11, a smoothing circuit 43, and the like, and a cleaning control signal Sc PWM-controlled by the controller 2 is input to the smoothing circuit 41. The

  The controller 2 applies a transfer cleaning bias voltage having a reverse bias to that of printing so that the residual toner on the photoconductor 20 does not adhere to the transfer roller 23 in accordance with the rotation start of the photoconductor 20 and the output of the charging voltage. As described above, the cleaning control signal Sc is output to the cleaning bias power supply unit 40 of the transfer high-voltage power supply unit 26 to suppress problems such as back contamination.

  That is, the smoothing circuit 41 includes a resistor R11 and a capacitor C11, and outputs the cleaning control signal Sc to the cleaning bias drive circuit unit 42 as a cleaning control DC voltage (DC voltage) that is smoothed and stabilized.

  The cleaning bias drive circuit 42 causes a cleaning drive current to flow to the primary side of the transformer T11 in accordance with the cleaning control DC voltage input from the smoothing circuit 41 to generate a transfer cleaning bias voltage on the secondary side.

  A smoothing circuit 43 is connected to the secondary side of the transformer T11. The smoothing circuit 43 includes diodes D11 and D12, capacitors C12 and C13, and resistors R12 and R13. The smoothing circuit 43 is connected to the smoothing circuit 33 of the transfer output power supply unit 30, and outputs a high voltage generated on the secondary side of the transformer T11 by the cleaning bias drive circuit 42 as a transfer cleaning bias voltage from the transfer output terminal Wp. Let A feedback circuit (feedback means) 50 connected to the amplifier Ap1 of the drive circuit 32 of the transfer output power supply unit 30 is connected between the resistor R12 and the resistor R13. Then, a transfer output feedback current corresponding to the transfer current is fed back and input to the amplifier Ap1 as a transfer output feedback voltage by the pull-up resistor R1. The feedback circuit 50 is connected to an A / D (analog / digital) conversion circuit (not shown). The A / D conversion circuit converts the transfer output feedback current into a digital signal, thereby transferring the transfer output feedback signal (feedback signal). It outputs to the controller 2 as Sf.

  The controller 2 detects the current flowing between the transfer roller and the photoconductor based on the transfer output feedback signal Sf, performs PWM control of the transfer control signal Sp to the transfer output power supply unit 30, and performs the transfer output power supply unit 30. Controls the transfer current output by.

  The transfer current and the transfer output period signal Sf fed back by the feedback circuit 50 have a linear relationship as shown in FIG. 4, and the correspondence data between the transfer current and the transfer output feedback signal Sf is the ROM 3 Stored in advance. The controller 2 determines the transfer output current or the transfer output voltage based on the transfer output feedback signal Sf input through the feedback circuit 50, and performs PWM control of the transfer control signal Sp based on the determination result. The feedback circuit 50 and the controller 2 function as current detection means as a whole.

  Next, the operation of this embodiment will be described. The printer apparatus 1 of the present embodiment detects the inflow current Itz that flows from the transfer high-voltage power supply unit 26 via the transfer roller 23 into the photoconductor 20 and detects the flow-in current at the transfer current output timing of the transfer high-voltage power supply unit 26. Based on the current Itz, the transfer control signal Sp input to the transfer high-voltage power supply unit 26 is corrected, and the self-excited oscillation of the transfer high-voltage power supply unit 26 is appropriately performed.

  That is, as shown in FIG. 5, when a print start signal is input together with image data from the host device via the communication I / F 5, the printer device 1 simultaneously starts the rotation of the photoconductor 20 by the photoconductor motor. Then, a charging voltage is output from the charging high-voltage power supply unit 24 to the charging roller 21.

  Then, the printer apparatus 1 supplies the development high voltage power supply unit 25 from the development high voltage power supply unit 25 in accordance with the timing at which the charged portion of the photoreceptor 20 charged via the charging roller 21 by the charging high voltage power supply unit 24 reaches the development site where the development roller 4 is located. The developing voltage is output via the developing roller 22, and the transfer is performed from the transfer high-voltage power supply unit 26 via the transfer roller 23 in accordance with the timing when the charged portion of the photoconductor 20 reaches the transfer portion where the transfer roller 23 is located. Output current. By doing so, it is possible to prevent unnecessary toner from adhering to the photoconductor 20 or having a charging memory.

  Further, the printer device 1 determines that the portion of the photoconductor 20 that is image-exposed by the optical writing unit 9 according to the image signal when the transfer timing of the transfer roller 23 is at least one rotation with the cleaning bias applied. The image signal is output at the timing of reaching. Then, the printer apparatus 1 conveys the sheet P so that the leading end of the sheet P reaches the transfer portion in accordance with the timing when the image-exposed portion of the photoconductor 20 reaches the transfer portion, and the transfer high-voltage power supply unit The transfer current is output from 26 through the transfer roller 23 to transfer the toner image on the photoreceptor 20 onto the paper P.

  In addition, the printer apparatus 1 is configured so that the residual toner on the photoconductor 20 does not adhere to the transfer roller 23 from the cleaning bias power supply unit 40 in accordance with the rotation start of the photoconductor 20 and the output of the charging voltage. A reverse bias transfer cleaning bias voltage is applied to suppress problems such as back contamination. In FIG. 5, a period C is a switching period for preventing simultaneous operation of biases having different polarities from the transfer high-voltage power supply unit 26.

  As described above, the transfer output power supply unit 30 of the transfer high-voltage power supply unit 26 outputs an output corresponding to the transfer control DC voltage obtained by smoothing the transfer control signal Sp and the transfer output feedback voltage of the transformer T1. An output is made to the base of the transistor Tr1 via the base drive winding Tmb, and the transistor Tr1 is switched from OFF to ON. When the transformer T1 is turned on by the transistor Tr1, a voltage is applied to the primary winding Tm1, and at the same time, a voltage is generated in the base drive winding Tmb. The voltage generated in the base drive winding Tmb of the transformer T1 when the transistor Tr1 is turned on operates in a direction to further turn on (conduct) the transistor Tr1, and becomes a positive feedback voltage. A voltage is further applied to the primary winding Tm1 of T1. In this case, the voltage of the secondary winding Tm2 of the transformer T1 is reversely applied to the diodes D1 and D2 of the smoothing circuit 33. Therefore, no current flows through the secondary winding Tm2 of the transformer T1, and the primary of the transformer T The current flowing through the winding Tm1 is only the exciting current of the transformer T1.

  When the base current flowing from the base drive winding Tmb of the transformer T1 to the base of the transistor Tr1 cannot maintain the saturation of the transistor Tr1, the transistor Tr1 is out of saturation and the collector-emitter voltage Vce increases, and the collector − As the emitter voltage Vce increases, the voltage of the primary winding Tm1 of the transformer T1 decreases, the voltage of the base drive winding Tmb also decreases, and the collector-emitter voltage Vce further increases. This series of changes is positively fed back, and the transistor Tr1 is quickly turned off. Even at the moment when the transistor Tr1 is turned off, the magnetic field is kept the same, and the secondary winding Tm2 also has a current in the direction from the start of winding to the end of winding so as to maintain the same energy as the current flowing in the primary winding Tm1. Flows and diode D1 becomes conductive. When all the energy accumulated in the transformer T1 is transferred to the secondary side (output side), the current of the diode D1 is turned off.

  At this moment, the voltages of the windings Tm1, Tmb, and Tm2 of the transformer T1 become zero, but the transistor Tr1 is turned on again by the output of the drive circuit 32, and the above operation is repeated to continue oscillation.

  On the other hand, the printer apparatus 1 charges the surface potential of the rotating photoconductor 20 to about −900 V by the charging roller 21 connected to the power failure high-voltage power supply unit 24. At this time, the timing chart shown in FIG. In the period C, since the transfer bias (voltage, current) is not operated from the transfer high-voltage power supply unit 26, the secondary side circuit of the transfer high-voltage power supply unit 26 from GND to the transfer roller 23 along the path indicated by the arrow in FIG. The current flowing into the photoconductor 20 (flowing current Itz) is generated via When the difference between the feedback voltage to the drive circuit 32 of the transfer output power supply unit 30 and the transfer bias voltage due to the inflow current Itz is not large, the drive circuit 32 has a sufficient starting voltage for the transistor Tr1 to start self-excited oscillation. The transfer output (transfer bias) is not output from the transfer high-voltage power supply unit 26, the toner image transferred to the paper P becomes thin, or the toner image is not transferred to the paper P and transferred to the paper P. There is a risk that an image may not be formed.

  Therefore, in the printer apparatus 1 of this embodiment, the transfer output feedback current corresponding to the transfer current is fed back by the feedback circuit 50, and the transfer output feedback current is digitally converted by the A / D conversion circuit (not shown). The controller 2 outputs the signal Sf to the controller 2, and the controller 2 acquires the transfer current from the correspondence data between the transfer current stored in advance in the ROM 3 and the transfer output feedback signal Sf, and transfers the high-voltage power supply unit based on the inflow current Itz The transfer control signal Sp input to 26 is corrected, and the self-excited oscillation of the transfer high-voltage power supply unit 26 is appropriately performed.

  That is, the potential (transfer output voltage) of the transfer output terminal Wp of the transfer high-voltage power supply unit 26 at the time of image formation can be shown as shown in FIG. 7, and image formation is started by the print start signal as described above. Therefore, the rotation of the photoconductor 20 is started, and the charging voltage by the charging high-voltage power supply unit 24 and the developing voltage by the development high-voltage power supply unit 5 are sequentially applied to the photoconductor 20. At the same time as the surface of the charged photoconductor 20 reaches the transfer site, the printer apparatus 1 transfers the transfer cleaning bias voltage from the cleaning bias power supply unit 40 of the transfer high-voltage power supply unit 26 from the transfer output terminal to the transfer roller as shown in FIG. Then, the voltage is applied to the photoconductor 20 via 23. The voltage and current at the transfer output terminal Wp at this time are determined by the surface potential of the photoconductor 20, the transfer roller impedance Rt, and the cleaning bias voltage.

  Next, when the cleaning period elapses, the printer apparatus 1 stops the cleaning bias voltage from the cleaning bias power supply unit 40 and provides a bias switching period. During this bias switching period, since no bias voltage is applied from the transfer high-voltage power supply unit 26, when the surface potential of the photoconductor 20 is charged to about −900 V, a voltage of about −300 V is transferred according to Paschen's law. A voltage that appears on the surface of the portion on the transfer roller 23 side and drops due to the transfer roller impedance Rt appears at the transfer output terminal Wp of the transfer high-voltage power supply unit 26. Next, the printer apparatus 1 supplies the transfer control signal Sp to the transfer output power supply unit 30 of the transfer high voltage power supply unit 26 at the timing when the image area reaches the transfer site, and transfers the transfer current from the transfer output terminal Wp to the transfer roller. 23.

  Then, the transition state of the transfer output terminal Wp of the transfer high-voltage power supply unit 26 is input to the controller 2 as the transfer output feedback signal Sf.

  For example, when the surface potential of the photoconductor 20 is −942 V, the voltage (transfer voltage) of the transfer output terminal Wp when the transfer bias current (transfer current) is changed is shown as in FIG. The transfer current, transfer voltage, voltage drop caused by the transfer roller 23, and transfer roller impedance Rt in this case are shown in FIG. Therefore, the transfer terminal voltage at which the transfer current starts to flow is about −585 V, and even if the surface potential of the photoconductor 20 is changed, the voltage between the transfer roller and the photoconductor surface potential is about −600 V from Paschen's law. At that point, current begins to flow. Thus, when the transfer voltage, the surface potential of the photoconductor 20 and the transfer current are known, the transfer roller impedance Rt can be calculated.

  That is, in the printer apparatus 1 of this embodiment, since the transfer output power supply unit 30 is a constant current circuit and the cleaning bias power supply unit 40 is a constant voltage circuit, the transfer cleaning bias output voltage Vtm when the cleaning bias is applied can be known. The transfer current Itm can also be calculated from the transfer output feedback signal Sf. Further, the surface potential Vopc of the photoconductor 20 is a value obtained by subtracting 600 V from the absolute value of the charging bias setting voltage Vc according to Paschen's law because the charging bias setting voltage supplied from the charging high voltage power supply unit 24 is a constant voltage. It can be calculated (Vopc = Vc−600V). When the charging roller 21 is a contact charging system, the charging roller 21 has an impedance Rt of about 0.4 MΩ to about 1.8 MΩ, which is very small compared to the impedance of the photoconductor 20, and the charging high-voltage power supply unit. The surface potentials of the 24 output terminals and the charging roller 21 can be considered to be substantially the same.

  Therefore, the transfer roller impedance Rt can be calculated from Equation 1 shown below. Note that Vopc, Vtm, Vc, and Vtp are absolute values.

(Vopc−Vtm) / Itm = Rt Equation 1
Here, the inflow current Itz flowing into the switching period C shown in FIG. 5 can be directly detected. However, since the switching time is short and the discharge time is required, the correct value may not be detected. Calculation is performed according to Equation 2 shown below.

(Vopc−600) / Rt = Itz Equation 2
Accordingly, the setting current Itk at the time of starting self-oscillation can be calculated from the following equation 3 from the setting current Itp and the flowing current Itz at the time of transfer.

Itk = Itz + Itp ... Formula 3
The controller 2 performs PWM control of the transfer control signal Sp (correction of the transfer control signal Sp) so that the self-excited oscillation starting setting current Itk flows when the transfer output power supply unit 30 of the charging high-voltage power supply unit 24 is started. Thus, when the transfer control signal Sp is PWM-controlled based on the flowing current Itz when the transfer output power supply unit 30 of the charging high voltage power supply unit 24 is started, the transfer output feedback voltage and the transfer control signal Sp based on the transfer output feedback signal Sf are obtained. The voltage difference with the transfer control DC voltage (DC voltage) stabilized by smoothing is increased. As a result, the output of the drive circuit 32 is increased, the first self-excited oscillation of the transfer high-voltage power supply unit 26 can be increased, and the transfer current output operation is started without stopping the self-excited oscillation. Can do.

  As described above, the printer apparatus 1 according to the present exemplary embodiment transfers the transfer control signal to the photoconductor 20 that holds the toner image in which the electrostatic latent image is developed with the toner via the transfer roller 23 that is in contact with the photoconductor 20. When a transfer current having a predetermined target value generated at a predetermined timing according to Sp is output from the transfer output terminal Wp of the transfer high-voltage power supply unit 26 to transfer the toner image on the photoconductor 20 onto the paper P, the controller 2 However, the inflow current Itz flowing between the transfer roller 23 and the photoconductor 20 before the transfer current is supplied from the transfer roller 23 to the photoconductor 20 is detected, and the transfer high voltage power supply unit 26 is detected based on the inflow current Itz. The output transfer control signal Sp is corrected.

  Therefore, before the transfer current is supplied from the transfer roller 23 to the photoconductor 20, the influence of the flowing current Itz flowing between the transfer roller 23 and the photoconductor 20 on the transfer high-voltage power supply unit 26 is appropriately prevented, and the transfer high voltage The power supply unit 26 can be reliably operated, and transfer performance can be improved at low cost by supplying a transfer current at low cost and appropriately.

  In the printer apparatus 1 of the present embodiment, the transfer high-voltage power supply unit 26 generates a transfer current by self-oscillating based on the transfer control signal Sp.

  Therefore, the self-excited oscillation can be surely performed without being influenced by the flowing current Itz, and the transfer performance can be improved.

  Further, the printer apparatus 1 of the present embodiment uses the output voltage or output current of the transfer output terminal Wp of the transfer high-voltage power supply unit 26 as a feedback signal to transfer the transfer control signal Sp of the transfer high-voltage power supply unit 26, particularly the transfer output power supply unit 30. The transfer output power supply unit 30 includes a feedback circuit 50 that feeds back to the input side, and controls the transfer current based on the transfer control signal Sp and the transfer output feedback current. The controller 2 converts the transfer output feedback current into a digital output. The inflow current Itz is detected based on the feedback signal Sf.

  Therefore, it is possible to detect the inflow current Itz even more inexpensively and appropriately while using the existing configuration and reducing the additional configuration, and to appropriately prevent the influence of the inflow current Itz, and to appropriately control the transfer current. Thus, transfer performance can be improved appropriately at low cost.

  Further, in the printer apparatus 1 of this embodiment, the transfer high-voltage power supply unit 26 outputs a cleaning bias voltage having a predetermined output value opposite to the transfer current from the transfer output terminal Wp at a predetermined timing before the transfer current output timing. A cleaning bias drive circuit 42 is provided.

  Therefore, an appropriate transfer current can be supplied from the transfer high-voltage power supply unit 26 while appropriately preventing the occurrence of stains on the back, and the image quality of the formed image can be further improved.

  Further, in the printer apparatus 1 of the present embodiment, the controller 2 causes the inflow current Itz to flow based on the current that flows to the transfer output terminal Wp when the cleaning bias drive circuit 42 outputs the cleaning bias voltage from the transfer output terminal Wp. Is detected.

  Therefore, an appropriate transfer current can be supplied from the transfer high-voltage power supply unit 26 while appropriately preventing the occurrence of stains on the back, and the image quality of the formed image can be further improved.

  Further, the printer apparatus 1 of the present embodiment irradiates the charging roller 21 for uniformly charging the photosensitive member 20 and the writing light modulated based on the image data on the photosensitive member 20 uniformly charged by the charging roller 21. And an optical writing unit 9 for forming an electrostatic latent image, and a developing roller 4 for supplying toner to the photoconductor 20 on which the electrostatic latent image is formed to form a toner image. The inflow current Itz is detected when the charging region charged by the charging roller 21 of the photoconductor 20 is in a state of facing the transfer roller 23.

  Therefore, it is possible to accurately detect the inflow current Itz and supply an appropriate transfer current from the transfer high-voltage power supply unit 26, and it is possible to further improve the image quality of the formed image.

  In the above description, the case where the transfer high-voltage power supply unit 26 includes the cleaning bias power supply unit 40 has been described, but the same applies to the case where the transfer high-voltage power supply unit does not include the cleaning bias power supply unit. Can do.

  For example, as shown in FIG. 10, the transfer high-voltage power supply unit 60 includes a transfer output power supply unit 30 and a resistor R61, and does not need to include a cleaning bias power supply unit. In FIG. 10, the same components as those in the transfer high-voltage power supply unit 26 in FIG.

  The transfer high-voltage power supply unit 60 feeds the transfer current from the smoothing circuit 33 back to the drive circuit 32 as a transfer output feedback voltage via the resistor R61, and after A / D conversion as a transfer output feedback signal Sf, inputs it to the controller 2 To do.

  In the transfer high-voltage power supply unit 60 that does not include the cleaning bias power supply unit, the potential of the transfer output terminal Wp during image formation transitions as shown in FIG. That is, the printer apparatus 1 starts rotation of the photosensitive member 20 in response to the print start signal, as described above, and starts development of the charging voltage by the charging high-voltage power supply unit 24 and development by the development high-voltage power supply unit 5. A voltage is sequentially applied to the photoreceptor 20. Since the printer device 1 does not include a cleaning bias power supply unit as shown in FIG. 11 at the same time as the surface of the charged photoconductor 20 reaches the transfer site, the transfer high-voltage power supply unit outputs no cleaning bias voltage. The output of the transfer bias from 60 is stopped. At this time, since no bias voltage is applied from the transfer high-voltage power supply unit 60, when the surface potential of the photoconductor 20 is charged to about −900 V, a voltage of about −300 V is transferred to the transfer portion according to Paschen's law. A voltage that appears on the surface on the roller 23 side and has dropped due to the transfer roller impedance Rt appears at the transfer output terminal Wp of the transfer high-voltage power supply unit 60. Next, the printer apparatus 1 supplies the transfer control signal Sp to the transfer output power supply unit 30 of the transfer high voltage power supply unit 60 at the timing when the image area reaches the transfer site, and transfers the transfer current from the transfer output terminal Wp to the transfer roller. 23.

  Then, the transition state of the transfer output terminal Wp of the transfer high-voltage power supply unit 60 is input to the controller 2 as the transfer output feedback signal Sf.

  Now, the transfer output power supply unit 30 of the transfer high voltage power supply unit 60 is a constant current circuit, and when the charged region of the photoconductor 20 reaches the transfer site by the transfer output feedback signal Sf, it can be detected stably. An inflow current Itz flowing from the transfer roller 23 into the photoconductor 20 is detected. Assuming that the photoreceptor potential is Vopc, and the transfer voltage when the charged photoreceptor 20 reaches the transfer site is Vtz, the transfer roller impedance Rt can be obtained by the following equation (4).

(Vopc−Vtz−600) / Itz = Rt Equation 4
The transfer voltage Vtz can be calculated from the following equation 5.

(R5 + R6) × Itz + Vf × 2 = Vtz Expression 5
Vf is the forward voltage of the diodes D1 and D2.

  Thereafter, similarly to the above, the controller 2 performs PWM control of the transfer control signal Sp in consideration of the inflow current Itz to control the transfer voltage.

  Therefore, even when the transfer high-voltage power supply unit 60 does not include a cleaning bias power supply unit, self-excited oscillation can be reliably performed without being influenced by the flowing current Itz, and transfer performance can be improved.

  As described above, since the resistance value and the like of the printer device 1 vary depending on the type of the paper P, in the case of constant current control, the transfer current set value is variably controlled for each paper P, and constant voltage control is performed. In this case, the set value of the transfer voltage is variably controlled for each sheet P.

  In the above description, the case where the transfer output power supply unit 30 of the transfer high-voltage power supply unit 26 outputs a transfer current as a transfer output by self-excited oscillation type constant current control has been described. However, the transfer output is generated and output. The transfer output power supply unit is not limited to one using constant current control, and may be a power supply unit that outputs a transfer voltage as transfer output by self-excited oscillation type constant voltage control.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  The present invention can be used for an image forming apparatus, an image forming control method, an image forming control program, and a recording medium for transferring a developer image on a photosensitive member to a recording member by a transfer current or a transfer voltage supplied to a transfer roller. it can.

1 Printer device 2 Controller 3 ROM
4 RAM
5 Communication I / F
DESCRIPTION OF SYMBOLS 6 Operation part 7 Image forming part 8 Fixing part 9 Optical writing part 10 System bus 20 Photoconductor 21 Charging roller 22 Developing roller 23 Transfer roller 24 Charging high voltage power supply part 25 Development high voltage power supply part 26 Transfer high voltage power supply part 30 Transfer output power supply part 31 Smoothing circuit R1 Resistance 32 Drive circuit 33 Smoothing circuit Tr1 Transistor T1 Transformer R2, R3, R5, R6 Resistance C1, C2, C3 Capacitor Ap1 Amplifier R4 Feedback resistance D1, D2 Diode Tm1 Primary winding Tmb Base drive winding Tm2 Secondary Winding 40 Cleaning bias power supply unit 41 Smoothing circuit 42 Cleaning bias drive circuit unit 43 Smoothing circuit 50 Feedback circuit T11 Transformer R11 Resistor C11 Capacitor D11, D12 Diode C12, C13 Capacitor R12, R13 Resistor P Paper Sp Copy control signal Sc Cleaning control signal Sf Transfer output feedback signal 60 Transfer high voltage power supply R61 Resistor

Japanese Patent No. 4045413

Claims (9)

A photoreceptor for holding a developer image in which an electrostatic latent image is developed by a developer;
A transfer power supply means for generating a transfer voltage or transfer current of a predetermined target value at a predetermined timing in accordance with an input control signal and outputting it from an output terminal;
A transfer roller for contacting the photoconductor and supplying a transfer voltage or transfer current generated by the transfer power supply means to the photoconductor to transfer the developer image on the photoconductor to a recording medium;
Current detection means for detecting an inflow current flowing between the transfer roller and the photoconductor before the transfer voltage or the transfer current is supplied from the transfer roller to the photoconductor;
Control means for controlling the control signal to the transfer power supply means and correcting the control signal based on the flow-in current;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the transfer power supply unit generates the transfer voltage or the transfer current by self-oscillating based on the control signal. The image forming apparatus includes a feedback unit that feeds back an output voltage or an output current of the output terminal of the transfer power supply unit to the input side of the control signal of the transfer power supply unit as a feedback signal,
The transfer power supply means controls the transfer voltage or the transfer current based on the control signal and the feedback signal,
The image forming apparatus according to claim 1, wherein the current detection unit detects the inflow current based on the feedback signal.   The transfer power supply means outputs, from the output terminal, a cleaning voltage having a predetermined output value opposite to the transfer voltage or the transfer current at a predetermined timing before the output timing of the transfer voltage or the transfer current. The image forming apparatus according to claim 1, further comprising:   The current detection means detects the inflow current based on a current flowing through the output terminal when the cleaning power supply means outputs the cleaning voltage from the output terminal. Image forming apparatus. The image forming apparatus includes:
Charging means for uniformly charging the photoreceptor;
Light writing means for forming an electrostatic latent image by irradiating the photosensitive member uniformly charged by the charging means with writing light modulated based on image data;
Developing means for supplying a developer to the photoreceptor on which an electrostatic latent image is formed to form a developer image;
With
6. The current detection unit detects the inflow current when a charging area charged by the charging unit of the photoconductor is in a state of facing the transfer roller. An image forming apparatus according to claim 1. A photosensitive member holding a developer image in which an electrostatic latent image is developed by a developer, and a transfer voltage or a transfer current having a predetermined target value are generated at a predetermined timing according to an input control signal and output from an output terminal. A transfer power supply means; a transfer roller that contacts the photoconductor and supplies a transfer voltage or transfer current generated by the transfer power supply means to the photoconductor to transfer the developer image on the photoconductor to a recording medium; An image forming control method in an image forming apparatus comprising:
A current detection processing step for detecting an inflow current flowing between the transfer roller and the photoconductor before the transfer voltage or the transfer current is supplied to the photoconductor from the transfer roller;
A control processing step of controlling the control signal to the transfer power supply means and correcting the control signal based on the inflow current detected in the current detection processing step;
An image formation control method characterized by comprising: A photosensitive member holding a developer image in which an electrostatic latent image is developed by a developer, and a transfer voltage or a transfer current having a predetermined target value are generated at a predetermined timing according to an input control signal and output from an output terminal. A transfer power supply means; a transfer roller that contacts the photoconductor and supplies a transfer voltage or transfer current generated by the transfer power supply means to the photoconductor to transfer the developer image on the photoconductor to a recording medium; An image formation control program that can be installed in an image forming apparatus comprising:
In the computer mounted on the image forming apparatus,
A current detection process for detecting an inflow current flowing between the transfer roller and the photoconductor before the transfer voltage or the transfer current is supplied to the photoconductor from the transfer roller;
A control process for controlling the control signal to the transfer power supply means and correcting the control signal based on the inflow current detected in the current detection process step;
An image formation control program for executing   A computer-readable recording medium on which the image forming control program according to claim 8 is recorded.

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