JP6435910B2 - Power supply apparatus, image forming apparatus, and power supply method - Google Patents

Description

  The present invention relates to a power supply apparatus, an image forming apparatus, and a power supply method, and more particularly, to a power supply apparatus, an image forming apparatus, and a power supply that supply power to each unit that requires high voltage power in an electrophotographic image forming apparatus. It relates to a supply method.

  2. Description of the Related Art Recently, electrophotographic image forming apparatuses have become widespread in image forming apparatuses such as copying apparatuses, facsimile apparatuses, printer apparatuses, copying apparatuses, and composite apparatuses.

  In an electrophotographic image forming apparatus, a recording agent image such as a toner image on a photoconductor is transferred between a photoconductor and a transfer roller disposed opposite to the photoconductor, such as paper or film. Directly transferred to a recording medium, or transferred to a primary transfer belt conveyed between a photoconductor and a transfer roller arranged opposite to the photoconductor, and then placed opposite to the primary transfer belt. The recording agent image is finally transferred onto the recording medium by performing secondary transfer onto the recording medium conveyed between the secondary transfer roller and the opposing roller.

  In the transfer of the recording agent image, the image forming apparatus performs a feedback control to a transfer voltage corresponding to the type, size, etc. of the recording medium to be transferred, thereby making the transfer performance constant and forming an image with a stable density. Is going.

  In the image forming apparatus, a power source controlled at a constant current is generally used as transfer power in order to make transfer performance constant, and a load of the transfer power is mainly a transfer roller. This transfer roller is highly dependent on the environment of its impedance, and tends to have a high resistance value in a low temperature / low humidity environment.

  In addition, electrophotographic image forming apparatuses often use a high voltage. For example, electrostatic charging power supplied to a charging unit for charging a photosensitive member on which an electrostatic latent image is formed, and a recording agent such as toner are statically discharged. Development power supplied to the developing unit to be applied to the photosensitive member on which the electrostatic latent image is formed and developed, and transfer power supplied to the transfer unit for transferring the recording material image on the photosensitive member to the primary transfer belt or recording medium In addition, high power such as separation power for separating the recording medium from the transfer roller and cleaning power for the recording material attached to the transfer roller is required.

  That is, the power supply unit of the conventional image forming apparatus is provided with a separation transformer 101 and a separation output control unit 102 for the separation output Pb as shown in FIG. 21, for example. The power supply unit connects the cleaning transformer 111, the cleaning output control unit 112, the transfer transformer 113, and the transfer output control unit 114 to the transfer output unit Pt, and feeds back the transfer output power using the CPU 121. I have control.

  In such a power supply unit, the proportion of the transformer, which is a high-voltage power component, is large in the component cost.

  In view of this, there has been proposed an image forming apparatus that reduces the component cost by sharing a transformer.

  For example, a separation power supply unit that applies a positive potential voltage to the separation electrode in order to separate the transfer material from the photoconductor at the time of separation, and a toner image formed on the surface of the photoconductor at the time of transfer And a transfer power supply unit that applies a negative potential voltage to the transfer roller for transfer onto the transfer roller, the positive potential generated by the separation power supply unit during cleaning of the transfer roller Or a voltage obtained by dividing the positive voltage is supplied to the transfer power supply unit and applied to the transfer roller (see Patent Document 1). .

  That is, when this prior art is applied to FIG. 21, as shown in FIG. 22, the output of the separation transformer 101 is divided by the voltage dividing resistors 131 and 132 and connected to the transfer output portion Pt for cleaning the transfer roller. The positive potential voltage generated by the separation transformer 101 or the voltage obtained by dividing the positive potential voltage by the voltage dividing resistors 131 and 132 is supplied to the transfer output unit Pt.

  In this case, the bias applied to the load during cleaning depends on the cleaning load resistance and the voltage dividing resistors 131 and 132.

  Even in an electrophotographic image forming apparatus, when a recording material image of a photosensitive member is primarily transferred to an intermediate transfer belt and then secondarily transferred to a recording medium such as paper by a transfer roller, the CPU 121 loads The image quality is improved by monitoring the bias applied to and controlling the secondary transfer bias.

  However, in the prior art described in the above publication, the separation bias is simply divided and output as a cleaning bias. As a result, there is a problem that the bias value applied to the cleaning load cannot be controlled due to the influence of the cleaning load resistance value, and appropriate operation control cannot be performed.

  That is, even if a bias that is simply divided from the separation bias is applied to the cleaning, the bias that is actually applied to the cleaning load depends on the cleaning load and the voltage dividing resistance, and thus deviates from the target bias value. Therefore, the cleaning operation cannot be performed properly.

  In the prior art described in the publication, since the bias value applied to the load cannot be controlled, in the case of the secondary transfer system, the bias applied to the load is monitored to control the image quality. Cannot be performed, and image quality may be affected.

  Therefore, an object of the present invention is to appropriately control the cleaning power when cleaning the transfer member while reducing the number of high-voltage power generation units of the power supply unit.

  In order to achieve the above object, the power supply device according to claim 1 is configured such that the recording agent image transferred from the image carrier to the transfer member is conveyed between the transfer member and the transfer power supply member. Transfer power supply means for supplying transfer power to be transferred to the recording medium to be supplied to the transfer power supply member, and when the transfer power is supplied from the transfer power supply means to the transfer power supply member, it is applied to a load. Feedback means for converting a bias value having a characteristic opposite to that of the transfer power into power and outputting it as a feedback signal; and control means for controlling the transfer power supplied by the transfer power supply means based on the feedback signal; Separation power supply means for supplying separation power to the separation power supply member for separating the recording medium onto which the recording agent image has been transferred from the transfer member; The transfer power obtained by dividing the power output by the predetermined division ratio is at least an appropriate period other than the image formation period due to transfer of the recording agent image from the recording medium to the transfer member. Cleaning power supply means for supplying the transfer power supply member as cleaning power for removing the recording agent on the supply member, and the control means has a load resistance value viewed from the transfer power supply means through the feedback means, A load resistance under a specific condition based on the feedback signal output from the feedback means under a specific condition that causes an error of a predetermined value or less compared with a load resistance value when supplying the cleaning power from the cleaning power supply means Value is calculated and based on the load resistance value and the division ratio under the specific condition, the cleaning During, it is characterized by controlling the power supplied by the separating power supply means.

  According to the present invention, it is possible to appropriately control the cleaning power when cleaning the transfer member while reducing the number of high-voltage power generation units of the power supply unit.

1 is a schematic configuration diagram of a main part of an image forming apparatus to which an embodiment of the present invention is applied. The principal part block block diagram of an electric power supply part. The principal part block block diagram of the electric power supply part which used resistance for the cleaning output extraction part. The principal part block diagram of the cleaning output extraction part using a isolation | separation transformer and its secondary subwinding. The principal part block diagram of the cleaning output extraction part using a isolation | separation transformer and its secondary main winding. FIG. 6 is a diagram illustrating a configuration pattern example of a separation power unit, a cleaning output extraction unit, and a secondary transfer power unit in FIGS. 3 to 5. The principal part block diagram of the cleaning output extraction part utilized by reversing the polarity of the separation transformer and its secondary sub-winding. The principal part block diagram of the cleaning output extraction part utilized by reversing the polarity of the isolation transformer and its secondary main winding. FIG. 9 is a diagram illustrating a configuration pattern example of a separation power unit, a cleaning output extraction unit, and a secondary transfer power unit in FIGS. 7 and 8. The figure which shows the operation | movement timing of the conventional isolation | separation, cleaning, and secondary transfer. The figure which shows the relationship between a secondary transfer output, a separation output, and a cleaning output when dividing | segmenting a separation output and producing | generating a cleaning output. The figure which shows the simple model of the load at the time of image formation and cleaning. The figure which shows the relationship between the temperature of a transfer belt, and resistance value. The figure which compares the time passage after power-on, and the relationship between load at the time of image formation and the time of non-image formation. Explanatory drawing of load measurement at the time of cleaning. The figure which shows the residual electric potential on a transfer belt, and its decay time. The figure which shows the relationship between attenuation | damping of the residual charge on a transfer belt, and secondary transfer. The flowchart which shows the separation output power calculation process at the time of cleaning. 6 is a flowchart illustrating a printing process that includes a cleaning output power calculation process during cleaning. The flowchart which shows an electric power control process. FIG. 10 is a schematic block diagram of a power supply unit of a conventional image forming apparatus. FIG. 6 is a schematic block diagram of a power supply unit of a conventional image forming apparatus that divides a separation output and uses it as a cleaning output.

  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 20 are diagrams showing an embodiment of a power supply apparatus, an image forming apparatus, and a power supply method according to the present invention. FIG. 1 is a diagram of the power supply apparatus, the image forming apparatus, and the power supply method according to the present invention. 1 is a schematic configuration diagram of a main part of an image forming apparatus 1 to which an embodiment is applied.

  In FIG. 1, an image forming apparatus 1 includes a paper feed unit 10, a transfer unit 20, image forming units 30Y, 30C, 30M, and 30K, a fixing unit 40, and a power supply unit 50 (see FIG. ) Etc. In addition to the above, the image forming apparatus 1 includes a motor, a drive mechanism unit that transmits a drive source to each unit driven by the motor, an operation display unit that displays various operations and information, and the like.

  The paper feed unit 10 includes a paper feed tray 11, a paper feed roller 12, a separation roller 13, a registration roller (not shown), and the like. The paper supply unit 10 separates the paper (recording medium) P in the paper supply tray 11 one by one by the paper supply roller 12 and the separation roller 13 and is disposed in front of the transfer unit 20 (not shown). Send to registration roller. In the paper supply unit 10, the registration rollers adjust the timing of the paper P sent from the paper supply tray 11, and send the paper P to the transfer unit 20 at a predetermined timing.

  The transfer unit 20 includes a transfer belt 21, a drive roller 22, a driven roller 23, a secondary transfer roller 24, and the like. The transfer belt (transfer member) 21 is an endless ring-shaped belt, It is stretched around the driven roller 23.

  The transfer unit 20 is driven in a counterclockwise direction indicated by an arrow in FIG. 1 when the drive roller 22 is rotationally driven by a drive mechanism such as a motor (not shown) under the control of the main control unit 61 (see FIG. 2). Driven by rotation. The transfer unit 20 conveys the transfer belt 21 in a state of sequentially passing through the image forming units 30Y, 30C, 30M, and 30K of the respective colors as the driving roller 22 is driven to rotate counterclockwise. The transfer unit 20 sequentially transfers a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image on the transported transfer belt 21 in each color image forming unit 30Y, 30C, 30M, and 30K. As a result, a color toner image (recording agent image) is formed.

  Image forming units 30Y, 30C, 30M, and 30K correspond to yellow (Y), cyan (C), magenta (M), and black (K) colors, respectively, and photoreceptors 31Y, 31C, 31M, and 31K, respectively. Are arranged at predetermined intervals along the conveying direction of the transfer belt 21. The image forming units 30Y, 30C, 30M, and 30K for the respective colors are respectively charged around the photosensitive members 31Y, 31C, 31M, and 31K, and charging units 32Y, 32C, 32M, and 32K, exposure units 33Y, 33C, 33M, and 33K, and developing units. 34Y, 34C, 34M, and 34K, transfer portions 35Y, 35C, 35M, and 35K, cleaning portions 36Y, 36C, 36M, and 36K, a static elimination portion (not shown), and the like are disposed. The photoconductors 31Y, 31C, 31M, and 31K function as image carriers.

  Each of the image forming units 30Y, 30C, 30M, and 30K includes photosensitive members 31Y, 31C, 31M, and 31K that are driven to rotate clockwise in FIG. 1 by a driving mechanism (not shown), and charging units 32Y, 32C, 32M, and 32K. Charge uniformly. The image forming units 30Y, 30C, 30M, and 30K are photoreceptors 31Y, 31C, and 31M in which writing light modulated by image data of each color is uniformly charged from the exposure units 33Y, 33C, 33M, and 33K. , 31K to form an electrostatic latent image. The image forming units 30Y, 30C, 30M, and 30K are respectively provided with the toners (YCMK color toners) in the developing units 34Y, 34C, 34M, and 34K on the photoreceptors 31Y, 31C, 31M, and 31K on which the electrostatic latent images are formed. A toner image of each color is formed by attaching a recording agent). The image forming units 30Y, 30C, 30M, and 30K are disposed on the back surface of the transfer belt 21 when the toner images on the photoconductors 31Y, 31C, 31M, and 31K rotate to a position facing the transfer belt 21. A transfer potential is applied to the transfer portions 35Y, 35C, 35M, and 35K, and toner images of each color of YCMK on the photoconductors 31Y, 31C, 31M, and 31K are sequentially transferred to the transfer belt 21. The photoreceptors 31Y, 31C, 31M, and 31K that have completed the transfer of the toner image are cleaned of residual toner by the cleaning units 36Y, 36C, 36M, and 36K, discharged by the discharging unit, and then again charged by the charging units 32Y, 32C, Charged by 32M and 32K and used for the next image forming operation.

  The transfer unit 20 further conveys the transfer belt 21 onto which the color toner images are transferred by sequentially superimposing and transferring the toner images of each color of YCMK as described above, and the drive roller 22 and the secondary transfer roller 24. Transport to and from. The paper P is conveyed from the paper feeding unit 10 to the nip portion between the driving roller 22 and the secondary transfer roller 24.

  The transfer unit 20 is fixed at a nip portion between the drive roller 22 and the secondary transfer roller (transfer power supply member) 24 through the transfer belt 21 and the paper P between the secondary transfer roller 24 and the drive roller 22. The transfer power (transfer voltage) is supplied. The transfer unit 20 transfers the toner image on the transfer belt 21 to the paper P conveyed from the paper supply unit 10 by supplying transfer power.

  The image forming apparatus 1 includes a separation power supply unit (separation power supply member) that supplies separation power for separating the paper P from the transfer belt 21 downstream of the nip portion between the driving roller 22 and the secondary transfer roller 24 in the paper conveyance direction. ) 25 is provided. For example, the separation power supply unit 25 is disposed in the vicinity of the transfer belt 21, and an electrode or the like that supplies separation power to the transfer belt 21 is used.

  The image forming apparatus 1 conveys the paper P on which the toner image is transferred by the transfer unit 20 to the fixing unit 40.

  The fixing unit 40 includes a fixing roller 41, a pressure roller 42, a thermistor (not shown), a thermostat, a fixing heater, and the like. The fixing roller 41 and the pressure roller 42 are pressed with a predetermined pressing force, and when one of them is driven to rotate, the other rotates. The fixing roller 41 has a built-in fixing heater that heats the fixing roller 41 to a temperature corresponding to the energization amount when energized. By controlling the energization amount to the fixing heater, a predetermined fixing temperature is set. The heating is controlled.

  The fixing unit 40 fixes the color toner image onto the paper P by conveying the paper P onto which the color toner image on which each color of YCMK is superimposed is transferred while being heated and pressed by the fixing roller 41 and the pressure roller 42. The paper is discharged onto a paper discharge tray (not shown).

  The thermistor is disposed in the vicinity of the fixing roller 41, detects the surface temperature of the fixing roller 41, and outputs a detected temperature signal of an analog voltage value. The thermostat is connected to the power line to the fixing heater in the vicinity of the fixing roller 41. When the thermostat rises above a predetermined cutoff temperature, the thermostat is turned off to cut off the energization to the fixing heater.

  The exposure units 33Y, 33C, 33M, and 33K include, for example, LED array heads for each color of YCMK. The LED array head for each color irradiates writing light to the photoconductors 31Y, 31C, 31M, and 31K by controlling the lighting of the LEDs according to the image data of each color of YCMK.

  In the image forming apparatus 1, the main part of the power supply unit (power supply device) 50 is configured as a block as shown in FIG. The power supply unit 50 includes a separation power unit 51, a cleaning output extraction unit 52, a secondary transfer power unit 53, and an output feedback circuit 54, and the image forming apparatus 1 includes a main control unit 61.

  The separation power unit (separation power supply means) 51 includes a separation transformer 51a and a separation output control unit 51b. The separation output control unit 51b supplies power from a power supply unit (not shown) to the primary winding of the separation transformer 51a. The separation transformer 51a has a secondary winding connected to the separation output Pb, and outputs power generated in the secondary winding to the separation output Pb as separation power Vb. The separation output Pb applies a constant separation power Vb from the separation transformer 51a to a load such as the transfer belt 21 and the paper P. Further, the separation transformer 51 a outputs the power generated by the secondary winding to the cleaning output extraction unit 52.

  The separation output control unit 51b receives the separation power Vb generated in the secondary winding of the separation transformer 51a as the separation output monitor Vb, and receives a separation control signal from the main control unit 61. The separation output control unit 51b controls the power supplied to the separation transformer 51a so that the separation output monitor Vb becomes the target separation power set by the separation control signal from the main control unit 61.

  As will be described later, the cleaning output extraction unit (cleaning power supply unit) 52 is configured to divide the output power of the separation power unit 51 by a division ratio that is obtained in advance by the main control unit 61 and set in advance. . The cleaning output extraction unit 52 outputs the divided power obtained by dividing the separated power (separated output power during cleaning) by the division ratio to the transfer output Pt as the cleaning power Vc during the non-image forming period. The power supply unit 50 supplies the cleaning power Vc from the transfer output Pt to the transfer belt 21 through the separation power supply unit 25, and performs a cleaning process for removing toner and the like attached to the transfer belt 21.

  Then, the main control unit 61 outputs a cleaning control signal to the separation output control unit 51b during the cleaning process, and the separation power unit 51 sets the cleaning power Vc to a target cleaning power as described later. Controls output power.

  The secondary transfer power unit (transfer power supply means) 53 includes a secondary transfer transformer 53a and a secondary transfer output control unit 53b. The secondary transfer output controller 53b supplies power from a power supply unit (not shown) to the primary winding of the secondary transfer transformer 53a. The secondary transfer transformer 53a has a secondary winding connected to the transfer output Pt, and outputs the power generated in the secondary winding to the transfer output Pt as the secondary transfer power Vt. As the transfer output Pt, the secondary transfer power (transfer power) Vt from the secondary transfer transformer 53a is applied to the secondary transfer roller 24.

  The secondary transfer output controller 53b receives the secondary transfer power Vt generated in the secondary winding of the secondary transfer transformer 53a as a secondary transfer output monitor Vt, and the secondary transfer output monitor Vt is a target secondary transfer. The power supplied to the secondary transfer transformer 53a is controlled so that the transfer power is obtained.

  The output feedback circuit (feedback means) 54 is connected to the transfer output Pt to which the secondary transfer transformer 53a and the cleaning output extraction unit 52 are connected. The output feedback circuit 54 converts the bias value of the reverse characteristic applied to the load L when transferring the toner image onto the paper P into a voltage value and outputs it as a feedback signal to the main control unit 61. Here, the reverse bias value means a voltage value when the bias is current, and means a current value when the bias is voltage. The bias means a voltage or current applied for transfer, cleaning, and separation.

  The main control unit (control means) 61 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The main control unit 61 stores a basic program of the image forming apparatus 1 and a power supply program for executing the power supply method of the present invention in the ROM. The main control unit 61 performs basic processing as the image forming apparatus 1 by controlling each part of the image forming apparatus 1 while the CPU uses the RAM as a work memory based on a program in the ROM. The power supply method of the present invention is executed. In particular, the main control unit 61 monitors the bias applied to the load L based on the feedback signal input from the output feedback circuit 54, and corrects the target secondary transfer power controlled by the secondary transfer output control unit 53b. By doing so, the image quality is feedback-controlled. Further, the main control unit 61 uses the output feedback circuit 54 to make an error in which the resistance value of the load L viewed from the secondary transfer power unit 53 is less than a predetermined value compared to the resistance value of the load L during the non-image forming period. The resistance value of the load L is measured under the following conditions. The main control unit 61 calculates a voltage value at which the separation voltage divided by the measured resistance value of the load L and the division ratio of the cleaning output extraction unit 52 is applied to the load L when the transfer belt 21 is cleaned.

  The non-image forming period is, for example, a cleaning period of the transfer belt 21.

  In the image forming apparatus 1, the division ratio of the cleaning output extraction unit 52 of the power supply unit 50 is set based on the voltage value calculated by the main control unit 61.

  The cleaning output extraction unit 52 may be, for example, a cleaning output extraction unit 52a using divided resistors Ra and Rb as shown in FIG. In the cleaning output extraction unit 52a, the dividing resistor Ra is connected in series and the dividing resistor Rb is connected in parallel between the output of the separation transformer 51a and the transfer output Pt, and the cleaning output extracting unit 52a corresponds to the resistance ratio between the dividing resistor Ra and the dividing resistor Rb. The separation voltage is divided (divided) at the divided ratio and output to the transfer output Pt.

  Further, for example, as shown in FIG. 4, the cleaning output extraction unit 52 supplies the secondary main winding M2a and the secondary subwinding M2b facing the primary winding M1 of the separation transformer 51a for separation voltage and cleaning. It may be used as

  That is, at the time of separation, the separation transformer 51a generates the separation power Vb by the primary winding M1, the secondary main winding M2a, and the smoothing circuit H1, and outputs it to the separation output Pb. The smoothing circuit H1 includes, for example, two diodes D11 and D12 and two capacitors C11 and C12. The secondary power generated in the secondary main winding M2a is smoothed to be divided power.

  The cleaning output extraction unit 52b generates a cleaning power Vc at the time of cleaning by the secondary sub winding M2b and the smoothing circuit H2 of the separation transformer 51a, and outputs the cleaning power Vc to the cleaning output (transfer output) Pt. The smoothing circuit H2 includes, for example, two diodes D21 and D22 and two capacitors C21 and C22. The secondary power generated in the secondary auxiliary winding M2b is smoothed to obtain the cleaning power Vc. .

  The cleaning output extraction unit 52b in FIG. 4 can control the output power of the separated output to the target value by the separated output control unit 51b, but the cleaning power that is the output of the secondary auxiliary winding M2b is the secondary power. The output is a certain ratio with respect to the output of the main winding M2a. The cleaning power depends on the resistance value of the load L because the voltage value applied to the load L changes according to the resistance value of the load L. However, since the output paths of the separated output power and the cleaning output power are different, compared with the case where the divided resistors Ra and Rb shown in FIG. There is an advantage that it is difficult to influence the output power.

  Further, for example, as shown in FIG. 5, the cleaning output extraction unit 52 connects a smoothing circuit H1 for separation output and a smoothing circuit H2 for cleaning output to the secondary main winding M2 of the separation transformer 51a. The cleaning output extraction unit 52c may be used.

  That is, the separation transformer 51a generates split power and cleaning power in the secondary main winding M2. The smoothing circuit H1 is composed of, for example, two diodes D11 and D12 and two capacitors C11 and C12. The smoothing circuit H1 smoothes secondary power generated in the secondary main winding M2 and separates it as separated power Vb. Output to output Pb. The smoothing circuit H2 is composed of, for example, two diodes D21 and D22 and two capacitors C21 and C22, and the secondary power generated in the secondary main winding M2 is smoothed to obtain the cleaning power Vc. .

  The separation power unit 51, the cleaning output extraction unit 52, and the secondary transfer power unit 53 in the cleaning output extraction units 52a, 52b, and 52c shown in FIGS. 3, 4, and 5 are configured as shown in FIG. Can take a pattern.

  That is, in the power supply unit 50 of the image forming apparatus 1 of the present embodiment, the outputs of the separation power unit 51 and the cleaning output extraction unit 52 may be either the same polarity or different polarities. The output feedback circuit 54 uses the output current when the secondary transfer power 53 controls the secondary transfer power as a feedback signal at the time of cleaning. Are fed back each output voltage. Therefore, regardless of whether the secondary transfer power unit 53 is in constant current control or constant voltage control, the main control unit 61 can determine the resistance value of the load L from the relationship between voltage and current. 1 to 4 can be applied. That is, in FIG. 6, the secondary transfer power unit 53 may be either constant current control or constant voltage control, so the configurations 1 and 2 can be adopted. In FIG. 6, the separation power unit 51 and the cleaning output extraction unit 52 may have either the same polarity or a different polarity as the polarities. .

  Further, for example, as shown in FIG. 7, the cleaning output extraction unit 52 converts the secondary main winding M2a and the secondary sub winding M2b facing the primary winding M1 of the separation transformer 51a into the separation voltage and the cleaning output. You may utilize for the extraction part 52d.

  That is, the separation transformer 51a generates the separation power Vb by the primary winding M1, the secondary main winding M2a, and the smoothing circuit H1 and outputs the separation power Pb to the separation output Pb, as in FIG. Similarly to the above, the smoothing circuit H1 includes two diodes D11 and D12 and two capacitors C11 and C12. The smoothing circuit H1 smoothes the secondary power generated in the secondary main winding M2a and separates the separated power Vb. And

  The cleaning output extraction unit 52d generates the cleaning power Vc whose polarity is reversed from that in the case of FIG. 4 by the secondary sub winding M2b and the smoothing circuit H4 of the separation transformer 51a, and outputs the cleaning power Vc to the cleaning output Pt. The smoothing circuit H4 is composed of, for example, two diodes D41 and D42 and two capacitors C21 and C22 similar to the above, and the secondary power generated in the secondary auxiliary winding M2b is shown in FIG. And reverse the polarity and smooth the cleaning power. However, since the secondary transfer output and the cleaning output are always in a reverse polarity relationship, the secondary transfer output and the separation output have the same polarity.

  Accordingly, also in this case, the main control unit 61 can calculate the resistance value of the load L during cleaning using the feedback signal of the secondary transfer output from the output feedback circuit 54. As a result, as in the cleaning output extraction unit 52d in FIG. 7, if the polarity of the secondary transfer output and the cleaning output has a reverse polarity relationship, the polarity of the secondary transfer output and the separation output is the same or opposite. May be.

  Further, for example, as shown in FIG. 8, the cleaning output extraction unit 52 connects a smoothing circuit H1 for separation output and a smoothing circuit H4 for cleaning output to the secondary main winding M2 of the separation transformer 51a. Thus, the cleaning output extraction unit 52e may be used.

  That is, the separation transformer 51a generates the separation power Vb and the cleaning power Vc in the secondary main winding M2. Similarly to the above, the smoothing circuit H1 includes two diodes D11 and D12 and two capacitors C11 and C12. The smoothing circuit H1 smoothes the secondary power generated in the secondary main winding M2 and separates the separated power Vb. To the separated output Pb. As in FIG. 7, the smoothing circuit H4 includes two diodes D41 and D42 and two capacitors C21 and C22. The smoothing circuit H4 generates secondary power generated in the secondary main winding M2 in the case of FIG. And reverse the polarity and smooth the cleaning power Vc.

  The separation power unit 51, the cleaning output extraction unit 52, and the secondary transfer power unit 53 in the cleaning output extraction units 52d and 52e shown in FIGS. 7 and 8 can take a configuration pattern as shown in FIG. it can.

  That is, in the case shown in FIG. 9, as in the case of FIG. 6, the secondary transfer power unit 53 can control the secondary transfer power Vt by either constant current control or constant voltage control. A configuration like the configuration 6 can be adopted. Further, the direction of the diodes D41 and D42 is adjusted in the opposite direction to that in FIGS. 4 and 5 so that the secondary transfer power Vt and the separation power Vb have the same polarity, while the cleaning output has a different polarity. Therefore, a configuration such as configuration 7 and configuration 8 can be adopted. Since the cleaning power and the secondary transfer power are output from the transfer output Pt, which is the same output terminal, to the secondary transfer roller 24, they cannot have the same polarity.

  The image forming 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), and a DVD. The power supply method of the present invention recorded on a computer-readable recording medium such as (Digital Versatile Disk), USB (Universal Serial Bus) memory, SD (Secure Digital) card, MO (Magneto-Optical Disc) is executed. A power supply method for appropriately controlling the cleaning power when cleaning the transfer member while reducing the number of power supply units to be described later by loading the power supply program to be read and introducing it into the ROM or the like of the main control unit 61 It is constructed as an image forming apparatus equipped with a power supply unit 50 to be executed. This power supply program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented programming language, and is stored in the recording medium. Can be distributed.

  Next, the operation of this embodiment will be described. The image forming apparatus 1 of this embodiment appropriately controls the cleaning power when cleaning the secondary transfer roller 24 that is a transfer member while reducing the number of transformers that are high-voltage power generation units of the power supply unit 50. .

  That is, the image forming apparatus 1 performs the secondary transfer of the toner image transferred on the transfer belt 21 to the secondary transfer roller 24 onto the paper P conveyed between the transfer belt 21 and the secondary transfer roller 24. Secondary transfer onto the paper P is performed by the secondary transfer power Vt supplied from the power unit 53.

  Under the control of the main control unit 61, the image forming apparatus 1 divides the power from the separation power unit 51 by the cleaning output extraction unit 52 at a preset division ratio before and after the secondary transfer. Is output to the transfer output Pt as the cleaning power Vc.

  The transfer output Pt is connected to the secondary transfer roller 24, and the secondary transfer roller 24 is supplied with cleaning power Vc to remove foreign matters such as residual toner remaining on the secondary transfer roller 24. .

  The image forming apparatus 1 outputs the separated power Vb whose power is adjusted to the predetermined target divided power from the separated power unit 51 to the separated output Pb at the secondary transfer timing.

  The separation output Pb is connected to the separation power supply unit 25, and the separation power supply unit 25 supplies the separation power Vb to the transfer belt 21 to separate the paper P on which the toner image has been transferred from the transfer belt 21. Let

  In the image forming apparatus 1, when the separation output, the transfer output, and the cleaning output are separated as in the conventional case, as shown in FIG. 10, the separation output, the cleaning output, and the transfer output are separated from each other. Is output.

  However, the image forming apparatus 1 of this embodiment supplies the secondary transfer power Vt from the secondary transfer power unit 53 to the secondary transfer roller 24 via the transfer output Pt at the time of secondary transfer (image formation). At the same time, the separated power Vb is output from the separated power unit 51 to the separated power supply unit 25 via the separated output Pb.

  The cleaning output extraction unit 52 receives the power output from the separation power unit 51 even during image formation, and outputs the divided power Vbt obtained by dividing the power by the above-described division ratio from the transfer output Pt to the transfer belt 21. .

  Therefore, in the image forming apparatus 1, as indicated by a broken line in FIG. 11, during cleaning, cleaning power is output from the separation power unit 51, and the cleaning output Vc divided by the cleaning output extraction unit 52 is transferred to the transfer output Pt. Output from. The image forming apparatus 1 cleans the secondary transfer roller 24 with the cleaning output Vc. At the time of image formation, the secondary transfer power unit 53 normally outputs the secondary transfer power Vt to the transfer output Pt and outputs the separated power Vb from the separated power unit 51 to the separated output Pb. The divided power Vbt obtained by dividing the output power 51 by the cleaning output extraction unit 52 is output to the transfer output Pt. Therefore, the main control unit 61 causes the secondary transfer power unit 53 to output, as the secondary transfer power, power (Vt + Vbt) obtained by adding the divided power Vbt to the normal secondary power Vt to the transfer output Pt.

  Then, as shown in FIGS. 2 to 5, 7, and 8, the cleaning output extraction unit 52 cleans the divided power obtained by dividing the power output from the separated power unit 51 by a preset division ratio. Output as electric power Vc.

  The cleaning power Vc is determined by the power output from the separation power unit 51 during cleaning, the resistance value of the load L during cleaning (load resistance value during cleaning), and the internal resistance value.

  Therefore, the image forming apparatus 1 measures the load resistance value Rt during cleaning, and calculates the separation output power during cleaning that the separation power unit 51 should output in order to output the cleaning power Vc during cleaning. However, when the load resistance value during cleaning is measured, if there is a load other than the above circuit conditions, an incorrect load resistance value is measured.

  Therefore, the image forming apparatus 1 uses the load resistance value at the time of cleaning as the load resistance value viewed from the secondary transfer power unit 53 through the output feedback circuit 54 and the load resistance value when the cleaning power is supplied from the cleaning output extraction unit 52. Under a specific condition in which an error is equal to or less than a predetermined value, the main control unit 61 calculates the load resistance value Rt under the specific condition based on the feedback signal output from the output feedback circuit 54.

  The cleaning load resistance value Rt varies depending on the material, operating conditions, installation environment, and the like of the load L of the image forming apparatus 1. The cleaning load L is due to the transfer belt 21 and the paper P. Furthermore, the resistance value varies with temperature, as will be described later.

  Therefore, in the image forming apparatus 1 according to the present embodiment, the main control unit 61 uses the same conditions as at the time of cleaning as the specific conditions, and the main control unit 61 uses the specific conditions based on the feedback signal output from the output feedback circuit 54. The lower load resistance value Rt is calculated.

  That is, as a simple model, the load L is shown as shown in FIG. 12A at the time of image formation. In addition to the load of the transfer belt 21 and the secondary transfer roller 24, the charge of the paper P and toner is superimposed. The load has been reduced. However, at the time of cleaning, the load L is only the load of the transfer belt 21 and the secondary transfer roller 24 as shown in FIG.

  Further, the load L at the time of cleaning has a resistance as shown in FIG. 12, and the resistance of the transfer belt 21 changes depending on the temperature as shown in FIG. It fluctuates depending on the in-machine temperature after the power of the forming apparatus 1 is turned on. As shown in FIG. 14, the load L of the image forming apparatus 1 is greatly different between the time of image formation and the time of non-image formation with the passage of time after the power is turned on. That is, the load L changes greatly as the in-machine temperature changes due to the image forming operation at the time of image formation, but changes smoothly because there is little change in the in-machine temperature at the time of non-image formation.

  As described above, the resistance value Rt of the load L under specific conditions needs to be measured under the same conditions as possible during cleaning. That is, as shown in FIG. 15, when the residual charge due to the primary transfer moves to the secondary transfer roller 24 while remaining on the transfer belt 21, the main control unit 61, as shown in FIG. Under the influence of charge, the load resistance value cannot be measured under specific conditions. In other words, at the time of image formation, charged toner or paper P intervenes, so it cannot be said that it is under a specific condition as described above, and is suitable as a measurement timing of a load resistance value under a specific condition. Not. Further, even when the image is not formed in the adjustment mode or the like, since the transfer portions 35Y to 35K exist, residual charges due to the primary transfer bias may remain on the transfer belt 21 as shown in FIG. . Even in this case, the load resistance value measured using the output feedback circuit 54 does not match the load resistance value at the time of cleaning. That is, as a specific condition for measuring the load L during cleaning, it is necessary that there is no residual charge on the transfer belt 21.

  However, if the cleaning load measurement mode is specially provided, the printing time is affected and the productivity is affected. Therefore, it is necessary to measure the cleaning load in another adjustment mode that can avoid the specific condition. .

  On the other hand, when there is no charged toner on the transfer belt 21, the residual potential on the transfer belt 21 attenuates with time as shown in FIG. Depending on the material of the transfer belt 21, as shown in FIG. 16, even if the transfer belt 21 is charged to 500 V, the residual potential becomes 30 V or less after 0.1 s. .

  Now, if the transfer output (in the case of constant current control) at the time of load measurement at the time of cleaning is 50 uA, the error of the resistance value is 0.6 MΩ. Generally, since the load resistance value at the time of cleaning is several tens of MΩ, when the error tolerance is ± 1 MΩ or less, the error of 0.6 MΩ falls within the allowable range. Therefore, for example, as shown in FIG. 17, it is assumed that the transfer speed of the transfer belt 21 is 150 mm / s, and primary transfer exists at 50 mm upstream of the secondary transfer. In this case, the charge on the transfer belt 21 applied in the primary transfer reaches the secondary transfer after 0.33 s, and therefore satisfies the specific condition of the cleaning load measurement.

  That is, the main control unit 61 uses the transfer operation of the toner image (recording agent image) from the transfer belt 21 to the paper P as a non-operation as a specific condition and sets the load resistance value under the specific condition based on the feedback signal. Calculation may be performed.

  Further, the main control unit 61 sets the charge amount on the transfer belt 21 so that the influence of the residual charge on the transfer belt 21 on the calculation of the load resistance value can be ignored under specific conditions based on the feedback signal. The load resistance value may be calculated under specific conditions based on the feedback signal, with the timing of attenuation being obtained and the timing satisfying the specific condition.

  Further, the main control unit 61 transfers the toner (recording agent image) from the photoconductors (image carriers) 31Y, 31C, 31M, and 31K to the transfer belt (transfer member) 21 to the secondary transfer roller of the transfer belt 21. (Transfer power supply member) The influence of the residual charge on the transfer belt 21 on the calculation of the load resistance value under specific conditions based on the feedback signal based on the conveyance speed to the position facing the transfer power 24 and the residual charge attenuation characteristic of the transfer belt 21 The load resistance value may be calculated under the specific condition based on the feedback signal, with the timing at which the signal is attenuated to a negligible charge amount being determined and the timing as the timing satisfying the specific condition.

  Therefore, the main control unit 61, when the specific condition is satisfied, as shown in FIG. 18, the cleaning separated output power (cleaning) to be output by the separation power unit 51 at the time of cleaning based on the load resistance value under the specific condition. A process for obtaining a time separation output voltage) is performed.

  That is, when shifting to the cleaning separation output power calculation mode, as shown in FIG. 18, the main control unit 61 sets the set current It for cleaning separation output power calculation mode to the transfer output Pt, and performs secondary transfer. Output from the power unit 53 (step S101). It should be noted that the cleaning output power output calculation mode is also referred to as an adjustment mode as appropriate.

  The main control unit 61 obtains the output voltage Vt, which is a feedback signal converted into a voltage value, from the output feedback circuit 54 when the set current It is flowing to the transfer output Pt (step S102).

  The main control unit 61 calculates the cleaning load resistance value (load resistance value under specific conditions) Rt from the set current It and the output voltage Vt (step S103).

  The main control unit 61 assumes that the separation power unit 51 necessary for outputting the intended cleaning voltage Vc to the transfer output Pt during cleaning, assuming that the load L during cleaning is the load resistance value Rt under this specific condition. A cleaning separation output power Vc + to be output is calculated. The main control unit 61 calculates the cleaning separated output power (cleaning separated output voltage) Vc + based on the load resistance value Rt and the division ratio of the cleaning output extracting unit 52 under the specific conditions. The main controller 61 stores the calculated separated output power Vc + during cleaning in the internal memory, and ends the separated output power calculation process during cleaning (step S104).

  Then, the main control unit 61 executes a printing process involving the cleaning output power calculation process as shown in FIG. In other words, when the image forming apparatus 1 is turned on (ON) and a return from the sleep state occurs (step S201), the main control unit 61 first performs the cleaning output power calculation process (step S202).

  The main control unit 61 checks whether a predetermined number of preset sheets have been printed or whether the predetermined temperature has changed (step S203). The predetermined number of prints is set in advance as the number of prints required for recalculating the cleaning output power Vc + when the cleaning load resistance value changes. Further, the predetermined temperature change is set in advance as a temperature change necessary for re-calculating the cleaning output power Vc + when the change in the cleaning load resistance value due to the temperature is repeated.

  In step S203, when both the predetermined number of printings and temperature change have not occurred (NO in step S203), the main control unit 61 executes printing (step S204), and checks whether printing is completed. (Step S205).

  If the printing is not completed in step S205 (NO in step S205), the main control unit 61 returns to step S203 and performs the same processing as described above from the printing of a predetermined number of sheets and the temperature change check (step S205). S203 to S205).

  When printing is finished in step S205 (YES in step S205), the main control unit 61 checks whether the power is off (step S206). If the power is not OFF in step S206 (NO in step S206), the main control unit 61 returns to step S203 and performs the same processing as above (steps S203 to S206).

  In step S203, when at least one of a predetermined number of prints and a predetermined temperature change occurs (YES in step S203), the main control unit 61 returns to step S202 to calculate the separated output power during cleaning. The processing is performed in the same manner as described above (steps S202 to S206).

  When the power is off in step S206 (YES in step S206), the main control unit 61 turns off the power and ends the process (step S207).

  Then, at the time of printing, as shown in FIG. 20, the main control unit 61 controls the output power (output voltage in the case of voltage control) of the separation power unit 51 to the separation output power and the cleaning output power. Perform power control processing.

  That is, when starting printing, the main control unit 61 waits for a cleaning output start request, that is, until the cleaning timing is reached (step S301).

  If there is a cleaning output start request in step S301 (YES in step S301), the main control unit 61 sets the output of the separation power unit 51 to the output power during cleaning and turns on the output of the separation power unit 51. (ON) (step S302). In this state, the power supply unit 50 divides the cleaning output power from the separation power unit 51 by the cleaning output extraction unit 52, and outputs the cleaning output Vc from the transfer output Pt to the secondary transfer roller 24. Then, the secondary transfer roller 24 is cleaned before image formation.

  When the output of the separation power unit 51 is turned on, the main control unit 61 waits for a cleaning output stop request, that is, until the cleaning end timing is reached (step S303).

  If there is a cleaning output stop request in step S303 (YES in step S303), the main control unit 61 turns off the output of the separation power unit 51 to complete the pre-image cleaning (step S303). S304).

  When the pre-image cleaning is completed, the main control unit 61 waits for a separation output start request, that is, until the image formation timing (separation timing) is reached (step S305).

  If there is a separation output start request in step S305 (YES in step S305), the main control unit 61 sets the output of the separation power unit 51 to the output power during separation, and outputs the separation power unit 51. Is turned on (step S306).

  In this state, the power supply unit 50 outputs the separation output power from the separation power unit 51 as the separation power Vb from the separation output Pt, and separates the sheet P on which image formation has been completed from the transfer belt 21. At this time, the power supply unit 50 outputs the divided power Vbt obtained by dividing the separation output power by the cleaning output extraction unit 52 from the transfer output Pt to the secondary transfer roller 24 as shown in FIG. Thus, as described above, the main control unit 61 causes the secondary transfer power unit 53 to output the power (Vt + Vbt) obtained by adding the divided power Vbt to the transfer output Pt.

  In this way, the secondary transfer power Vt can be supplied to the secondary transfer roller 24 to appropriately transfer the toner image from the transfer belt 21 to the paper P.

  When the output of the separation-time output power is turned on, the main control unit 61 waits for a separation output stop request, that is, until the separation end timing is reached (step S307).

  If there is a separation output stop request in step S307 (YES in step S307), the main control unit 61 turns off the output of the separation power unit 51 and ends the separation process, that is, the secondary transfer process. (Step S308).

  When the separation process is completed, the main control unit 61 waits for a cleaning output start request, that is, until the cleaning timing after image formation (step S309).

  If there is a cleaning output start request in step S309 (YES in step S309), the main control unit 61 sets the output of the separated power unit 51 to the output power during cleaning, and outputs the separated power unit 51. Is turned on (step S310). In this state, the power supply unit 50 divides the cleaning output power from the separation power unit 51 by the cleaning output extraction unit 52, and outputs the cleaning output Vc from the transfer output Pt to the secondary transfer roller 24. Then, the secondary transfer roller 24 is cleaned after image formation.

  When the output of the separation power unit 51 is turned on, the main control unit 61 waits for a cleaning output stop request, that is, until the cleaning end timing is reached (step S311).

  If there is a cleaning output stop request in step S311 (YES in step S311), the main control unit 61 turns off the output of the separation power unit 51 and ends cleaning after image formation. The power control process ends (step S312).

  Therefore, the power supply unit 50 can supply appropriate power as the cleaning power Vc, the secondary transfer power Vt, and the separation power Vb in the image forming operation in the image forming apparatus 1. Further, the power supply unit 50 can generate the cleaning power Vc by accurately dividing it from the separated power Vb.

  Although the present invention has been described with respect to the case where the power supply unit 50 mainly performs voltage control of power control, the present invention can be similarly applied to the case of current control.

  As described above, in the image forming apparatus 1 of the present embodiment, the power supply unit (power supply device) 50 is transferred from the photoreceptors (image bearing members) 31Y, 31C, 31M, and 31K to the transfer belt (transfer member) 21. Transfer power for transferring the transferred toner image (recording agent image) onto a sheet (recording medium) P conveyed between the transfer belt 21 and a secondary transfer roller (transfer power supply member) 24. To the secondary transfer roller 24, and when the transfer power is supplied from the secondary transfer power unit 53 to the secondary transfer roller 24, to the load. An output feedback circuit (feedback means) 54 that converts a bias value having a characteristic opposite to that of the applied transfer power into electric power and outputs it as a feedback signal, and the secondary transfer power based on the feedback signal. A main control unit (control means) 61 for controlling the transfer power supplied by the unit 53; and a separation power supply unit (separation power supply) for separating power for separating the paper P onto which the toner image has been transferred from the transfer belt 21. A separation power unit (separation power supply means) 51 to be supplied to the member 25 and a divided power obtained by dividing the power output from the separation power unit 51 by a predetermined division ratio from at least the transfer belt 21 to the paper P. A cleaning output extraction unit that supplies an appropriate period other than the image forming period for transferring the toner image to the secondary transfer roller 24 as a cleaning power for removing the toner (recording agent) on the secondary transfer roller 24 using a cleaning period. (Cleaning power supply means) 52, and the main control unit 61 passes the output feedback circuit 54 through the secondary transfer power unit. The output feedback circuit 54 outputs the load resistance value as viewed from 3 under a specific condition in which the load resistance value when compared with the load resistance value when the cleaning power is supplied from the cleaning output extraction unit 52 is less than a predetermined value. A load resistance value Rt is calculated under specific conditions based on the feedback signal, and the power supplied by the separation power unit 51 is controlled during the cleaning period based on the load resistance value Rt and the division ratio under the specific conditions. To do.

  Therefore, the separation resistance that can accurately measure the load resistance at the time of cleaning as the load resistance value Rt under specific conditions, and the cleaning output extraction unit 52 can output the cleaning power at the time of cleaning based on the load resistance value Rt under the specific conditions. The output power of the unit 51 is calculated and controlled. As a result, the cleaning power for cleaning the transfer belt 21 can be appropriately controlled while reducing the number of transformers in the power supply unit 50.

  Further, in the image forming apparatus 1 of this embodiment, the power supply unit (power supply apparatus) 50 transfers the toner image transferred to the transfer belt 21 from the photoreceptors 31Y, 31C, 31M, and 31K. A transfer power supply processing step of supplying transfer power to be transferred to the secondary transfer roller 24 from the secondary transfer power unit 53 to the sheet P conveyed between the secondary transfer roller 24 and the secondary transfer roller 24; When supplying the transfer power from the transfer power unit 53 to the secondary transfer roller 24, the output feedback circuit 54 converts a bias value having a characteristic opposite to that of the transfer power applied to the load L into power and a feedback signal. And the transfer power supplied from the secondary transfer power unit 53 is controlled by the main control unit 61 based on the feedback processing step of outputting A control processing step, a separation power supply processing step of supplying separation power for separating the paper P on which the toner image has been transferred from the transfer belt 21, from the separation power unit 51 to the separation power supply unit 25, and the separation power A divided power obtained by dividing the power output from the supply unit 25 by a predetermined division ratio is generated by the cleaning output extraction unit 52, and at least other than the image forming period in which the toner image is transferred from the transfer belt 21 to the paper P. A cleaning power supply processing step that supplies the secondary transfer roller 24 as cleaning power for removing the toner on the secondary transfer roller 24, and the control processing step includes: The load resistance value viewed from the secondary transfer power unit 53 through the feedback circuit 54 is the cleaning output. The load resistance under a specific condition based on the feedback signal output from the output feedback circuit 54 under a specific condition that causes an error of a predetermined value or less compared with the load resistance value when the cleaning power is supplied from the extraction unit 52 A value Rt is calculated, and the power supplied by the separation power unit 51 during the cleaning period is controlled based on the load resistance value Rt and the division ratio under the specific condition.

  Therefore, the separation resistance that can accurately measure the load resistance at the time of cleaning as the load resistance value Rt under specific conditions, and the cleaning output extraction unit 52 can output the cleaning power at the time of cleaning based on the load resistance value Rt under the specific conditions. The output power of the unit 51 is calculated and controlled. As a result, the cleaning power for cleaning the transfer belt 21 can be appropriately controlled while reducing the number of transformers in the power supply unit 50.

  Further, in the power supply unit 50 of the image forming apparatus 1 of the present embodiment, the main control unit 61 determines that the transfer operation of the toner image from the transfer belt 21 to the paper P is inactive. As a condition, the load resistance value Rt is calculated under the specific condition based on the feedback signal.

  Therefore, the load resistance value Rt can be accurately calculated under specific conditions, and the cleaning power for cleaning the transfer belt 21 can be more appropriately controlled while reducing the number of transformers in the power supply unit 50. it can.

  In the power supply unit 50 of the image forming apparatus 1 according to the present embodiment, the main control unit 61 determines that the residual charge on the transfer belt 21 is converted into the feedback signal based on the residual charge attenuation characteristic of the transfer belt 21. Determining the timing at which the influence on the calculation of the load resistance value based on the specific condition is attenuated to a negligible charge amount, and assuming that the timing satisfies the specific condition as a timing satisfying the specific condition, the load resistance value based on the feedback signal Rt is calculated.

  Therefore, the load resistance value Rt can be calculated more accurately under specific conditions, and the cleaning power for cleaning the transfer belt 21 can be more appropriately controlled while reducing the number of transformers in the power supply unit 50. Can do.

  Further, in the power supply unit 50 of the image forming apparatus 1 of the present embodiment, the main control unit 61 causes the toner image transfer from the photoconductors 31Y, 31C, 31M, and 31K to face the secondary transfer roller 24. Based on the conveyance speed of the transfer belt 21 to the position and the residual charge attenuation characteristic of the transfer belt 21, the residual charge on the transfer belt 21 has an influence on the calculation of the load resistance value Rt under the specific condition based on the feedback signal. Is determined to be a negligible charge amount, and the load resistance value Rt is calculated under the specific condition based on the feedback signal, with the timing satisfying the specific condition.

  Accordingly, the load resistance value Rt can be calculated more accurately under specific conditions, and the cleaning power for cleaning the transfer belt 21 can be more appropriately controlled while reducing the number of transformers in the power supply unit 50. be able to.

  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.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Paper feed part 11 Paper feed tray 12 Paper feed roller 13 Separation roller 20 Transfer part 21 Transfer belt 22 Drive roller 23 Driven roller 24 Secondary transfer roller 25 Divided power supply part 30Y, 30C, 30M, 30K Image formation Part 31Y, 31C, 31M, 31K Photoconductor 32Y, 32C, 32M, 32K Charging part 33Y, 33C, 33M, 33K Exposure part 34Y, 34C, 34M, 34K Development part 35Y, 35C, 35M, 35K Transfer part 36Y, 36C, 36M, 36K Cleaning unit 40 Fixing unit 41 Fixing roller 42 Pressure roller 50 Power supply unit 51 Separation power unit 51a Separation transformer 51b Separation output control unit 52 Cleaning output extraction unit 53 Secondary transfer power unit 53a Secondary transfer transformer 53b Secondary transfer transformer 53b Transfer output controller 54 Output fee Back circuit 61 Main controller L Load Ra, Rb Dividing resistor M2a Secondary main winding M2b Secondary sub winding H1 Smoothing circuit D11, D12 Diode C11, C12 capacitor H2 Smoothing circuit D21, D22 Diode C21, C22 capacitor H4 Smoothing circuit D41, D42 Diode P Paper Pb Separation output Pt Transfer output Vb Separation power Vc Cleaning power Vt Secondary transfer power Vbt Division power

JP 2007-034092 A

Claims (6)

Supplying transfer power to the transfer power supply member for transferring the recording agent image transferred from the image carrier onto the transfer member to the recording medium conveyed between the transfer member and the transfer power supply member Transfer power supply means,
When supplying the transfer power from the transfer power supply means to the transfer power supply member, a feedback means for converting a bias value having a characteristic opposite to that of the transfer power applied to a load into power and outputting it as a feedback signal;
Control means for controlling the transfer power supplied by the transfer power supply means based on the feedback signal;
Separation power supply means for supplying to the separation power supply member separation power for separating the recording medium to which the recording agent image has been transferred from the transfer member;
The divided power obtained by dividing the power output from the separated power supply unit by a predetermined division ratio is at least a suitable period other than the image forming period in which the recording agent image is transferred from the transfer member to the recording medium. Cleaning power supply means for supplying the transfer power supply member as cleaning power for removing the recording agent on the transfer power supply member;
With
The control means includes
Under a specific condition in which the load resistance value viewed from the transfer power supply unit through the feedback unit is an error equal to or less than a predetermined value compared to the load resistance value when the cleaning power is supplied from the cleaning power supply unit. A load resistance value is calculated under specific conditions based on the feedback signal output from the feedback means, and the separated power supply means supplies the cleaning power during the cleaning period based on the load resistance value under the specific conditions and the division ratio. An electric power supply apparatus that controls electric power. The control means includes
The load resistance value is calculated under the specific condition based on the feedback signal as the specific condition that the transfer operation of the recording agent image from the transfer member to the recording medium is non-operation. The power supply device according to claim 1. The control means includes
Based on the residual charge attenuation characteristic of the transfer member, the timing at which the residual charge on the transfer member attenuates to a charge amount that can ignore the influence on the calculation of the load resistance value under the specific condition based on the feedback signal, 3. The power supply apparatus according to claim 1, wherein the load resistance value is calculated under the specific condition based on the feedback signal, with the timing being the timing that satisfies the specific condition. The control means includes
Based on the transfer speed of the transfer member from the transfer of the recording agent image from the image carrier to the position facing the transfer power supply member and the residual charge attenuation characteristics of the transfer member, the residual charge on the transfer member Determining the timing at which the influence on the calculation of the load resistance value under the specific condition based on the feedback signal is attenuated to a negligible charge amount, and setting the timing based on the feedback signal as the timing satisfying the specific condition 3. The power supply apparatus according to claim 1, wherein the load resistance value is calculated under conditions. The recording agent image transferred from the image carrier to the transfer member to be conveyed is transferred to a recording medium by a transfer power supply member to which transfer power is supplied to form an image, and the transfer power and the recording medium An image forming apparatus that supplies a separation power for separating the recording material from the transfer member and a cleaning power for removing the recording material remaining on the transfer member from the power supply unit.
An image forming apparatus comprising the power supply device according to claim 1 as the power supply unit. The transfer power for transferring the recording agent image transferred from the image carrier to the transfer member onto the recording medium conveyed between the transfer member and the transfer power supply member is transferred to the transfer power supply member. A transfer power supply processing step supplied from the power supply means;
When supplying the transfer power from the transfer power supply means to the transfer power supply member, the feedback means converts a bias value having a characteristic opposite to that of the transfer power applied to the load into power and outputs a feedback signal. A feedback processing step;
A control processing step of controlling the transfer power supplied from the transfer power supply means by a control means based on the feedback signal;
A separation power supply processing step of supplying separation power for separating the recording medium onto which the recording agent image has been transferred from the transfer member from a separation power supply means to a separation power supply member;
A division power generated by dividing the power output from the separation power supply unit by a predetermined division ratio is generated by the cleaning power supply unit, and at least other than an image forming period in which the recording agent image is transferred from the transfer member to the recording medium. A cleaning power supply processing step of supplying the transfer power supply member as a cleaning power for removing the recording material on the transfer power supply member with an appropriate period of
Have
The control processing step includes
Under a specific condition in which the load resistance value viewed from the transfer power supply unit through the feedback unit is an error equal to or less than a predetermined value compared to the load resistance value when the cleaning power is supplied from the cleaning power supply unit. A load resistance value is calculated under specific conditions based on the feedback signal output from the feedback means, and the power supplied by the separated power supply means during the cleaning period based on the load resistance value under the specific conditions and the division ratio The power supply method characterized by controlling.

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