JP5216403B2 - Image forming apparatus - Google Patents

Description

 The present invention relates to a rotation drive device and an image forming apparatus.

  In a rotational drive device such as a drum unit used in an image forming apparatus such as a printer or a copier, a motor is used to obtain rotational power of a driven object (photosensitive drum). For this reason, it is common to employ a configuration in which rotational power is transmitted from a motor shaft to a driven object via a gear. In such a rotary drive device, the drive load becomes large due to deterioration over time or external factors.

For example, Patent Document 1 below provides a load detection unit that detects a carriage conveyance load in a printer that includes a carriage on which a print head is mounted, a carriage motor, and a drive control device that controls the operation of the carriage motor. In addition, when the drive control device is provided with a function for controlling the rotation speed of the carriage motor based on the detection result of the load detection means, the carriage conveyance load increases due to deterioration over time or external factors. Even in such a case, a technique for stably controlling the carriage transport operation is disclosed.
JP 2006-240212 A

  In the above prior art, it is necessary to newly provide a load detection means for detecting a carriage load (drive load) of the carriage (drive object). It can be an obstacle. Further, the above-described prior art does not disclose any technique for reducing the transport load when the transport load of the carriage increases.

 The present invention has been made in view of the above-described circumstances, and can provide a rotational drive device capable of detecting a drive load and reducing the drive load without increasing the component cost and expanding the component mounting space. An object is to provide an image forming apparatus.

   In order to achieve the above-mentioned object, the present invention provides, as means for solving the rotational drive device, a motor that rotationally drives a drive object, a cleaning body provided for cleaning the surface of the drive object, and at least A rotary drive device including a control unit that controls the motor by feedback control having an integral element, the rotary drive device including a cleaning force adjusting unit for adjusting a cleaning force of the cleaning body with respect to the surface of the driven object, and the control The unit obtains an integral value calculated by an integral element of the feedback control as drive load information of the drive object, and controls the cleaning force adjustment unit based on the obtained integral value, thereby driving the drive The cleaning force of the cleaning body with respect to the surface of the driving object is controlled according to the magnitude of the driving load of the object.

  According to the present invention, as a first solving means related to the image forming apparatus, a motor that rotationally drives a driving object, a cleaning body that is provided to clean the surface of the driving object, and at least an integration element are provided. An image forming apparatus comprising: a control unit that controls the motor by feedback control and that integrally controls an image forming operation by an electrophotographic method, for adjusting a cleaning force of the cleaning body on the surface of the driving object A cleaning force adjusting unit, wherein the control unit acquires an integral value calculated by an integral element of the feedback control as driving load information of the driving object, and the cleaning force adjustment is performed based on the acquired integrated value. The cleaning force of the cleaning body with respect to the surface of the driving object is controlled according to the magnitude of the driving load of the driving object by controlling the portion. To.

  Further, as a second solving means relating to the image forming apparatus, in the first solving means, the driven object is a photosensitive drum, and the cleaning body is a rubbing roller disposed in pressure contact with the photosensitive drum. In some cases, the cleaning force adjusting unit is configured to mechanically connect a rubbing roller motor for rotationally driving the rubbing roller, a rotating shaft of the rubbing roller motor, and a rotating shaft of the rubbing roller. A connection switching unit for switching connection / disconnection, and the control unit controls the connection switching unit when the integral value is equal to or less than a predetermined threshold value to rotate the rotation shaft of the friction roller motor. And the rotating shaft of the rubbing roller are disconnected, and when the integrated value exceeds a predetermined threshold, the connection switching unit is controlled to rotate the rotating shaft of the rubbing roller motor and the rubbing roller. The shaft and the rubbing low And controls the use motor and controlling the rotational state of the rubbing roller cleaning force becomes large so that the rubbing roller against the photosensitive drum surface.

  Further, as a third solving means relating to the image forming apparatus, in the second solving means, the control unit is configured to make the sliding movement so that the rotation direction of the rubbing roller is the same as the rotation direction of the photosensitive drum. The cleaning force is increased by controlling the motor for the rubbing roller.

  Further, as a fourth solving means according to the image forming apparatus, in the second solving means, the control unit may be configured such that the rotation direction of the rubbing roller is the same as the rotation direction of the photosensitive drum, or The rubbing roller motor is controlled to be in the reverse direction, and the cleaning force is increased by controlling the rubbing roller motor so that the rotation speed of the rubbing roller is increased. To do.

  Further, as a fifth solving means according to the image forming apparatus, in the first solving means, the driven object is a photosensitive drum, and the cleaning body is a cleaning blade arranged in pressure contact with the photosensitive drum. In this case, the cleaning force adjustment unit is an actuator for adjusting the pressing force of the cleaning blade against the photosensitive drum, and the control unit controls the actuator when the integral value is equal to or less than a predetermined threshold value. Then, the pressing force of the cleaning blade against the photosensitive drum is set as an initial set value, and when the integrated value exceeds a predetermined threshold value, the actuator is controlled so that the pressing force of the cleaning blade against the photosensitive drum is By making the value higher than the initial setting value, the cleaning blur on the surface of the photosensitive drum is set. Characterized in that to increase the cleaning power of the de.

  In the present invention, the integral value calculated by the integral element of the feedback control is acquired as the driving load information of the driving object. In feedback control having an integral element, the integral value calculated by the integral element increases as the driving load of the driven object increases. That is, the state of the driving load of the driving object can be known from the integration value calculated by the integration element. Therefore, according to the present invention, there is no need for conventional load detection means for detecting the driving load of the object to be driven, and it is possible to detect the driving load without increasing the component cost or expanding the component mounting space. Is possible.

Further, in the present invention, a cleaning force adjusting unit for adjusting the cleaning force of the cleaning body with respect to the surface of the driving object is provided, and the driving is performed by controlling the cleaning force adjusting unit based on the integral value acquired as described above. The cleaning force of the cleaning body with respect to the surface of the driving object is controlled according to the magnitude of the driving load of the object. One of the causes of the increase in the driving load of the driving object is a deposit on the surface of the driving object. Therefore, by controlling the cleaning force of the cleaning body with respect to the surface of the driving object according to the magnitude of the driving load of the driving object, it is possible to perform cleaning according to the dirt state of the surface of the driving object. The driving load can be reduced.
As described above, according to the present invention, the driving load can be detected and the driving load can be reduced without causing an increase in component cost and an increase in component mounting space.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus 100 according to the present embodiment. An image forming apparatus 100 according to this embodiment is, for example, a full-color printer using an electrophotographic method, and includes a photosensitive drum (driving object) 1, a charging unit 2, an exposure unit 3, a developing unit 4, a transfer unit 5, and a cleaning. A blade (cleaning body) 6, a rubbing roller (cleaning body) 7, a paper feed roller 8, a paper transport roller 9, a fixing unit 10, a paper transport roller 11 and a paper discharge roller 12 are schematically configured.

    The photoconductor drum 1 is a rotating photoconductor for forming an electrostatic latent image on the surface thereof. As will be described in detail later, the photosensitive drum 1 has a rotating shaft connected to a rotating shaft of a DC brushless motor via a gear and is driven to rotate by the DC brushless motor. The charging unit 2 is installed above the photosensitive drum 1 and uniformly charges the surface of the photosensitive drum 1. The exposure unit 3 is composed of a laser irradiation unit, and forms an electrostatic latent image by irradiating the surface of the photosensitive drum 1 charged by the charging unit 2 with laser light.

    The developing unit 4 supplies toner of each color to the surface of the photosensitive drum 1 on which the electrostatic latent image is formed to form a toner image. Specifically, the developing unit 4 supplies a rotary rack 4a, a developing device 4Y for supplying yellow toner, and magenta toner, which are disposed at intervals of 90 degrees in the circumferential direction of the rotary rack 4a. The developing unit 4M includes a developing unit 4C that supplies cyan toner, and a developing unit 4K that supplies black toner. The rotary rack 4a rotates the rotation shaft 4b as a center to sequentially move the developing devices 4Y, 4M, 4C, and 4K of the respective colors to the developing positions facing the photosensitive drum 1 to perform development (toner supply). is there.

    The transfer unit 5 transfers the toner image on the photosensitive drum 1 onto the paper P, and includes an intermediate transfer belt 5a, primary transfer rollers 5b and 5c, a driving roller 5d, a secondary transfer counter roller 5e, and a secondary transfer roller 5f. It is composed of The intermediate transfer belt 5a is wound around the primary transfer rollers 5b and 5c, the drive roller 5d, and the secondary transfer counter roller 5e in an endless manner, and is driven by the drive roller 5d, so that the toner image formed on the photosensitive drum 1 is obtained. Plays the role of a transfer body that is transferred and temporarily held. The secondary transfer roller 5f is disposed at a position facing the secondary transfer counter roller 5e on the outer peripheral surface of the intermediate transfer belt 5a, and serves to secondary transfer the toner image primarily transferred to the intermediate transfer belt 5a onto the paper P. I'm in charge.

    The cleaning blade 6 is a cleaning body that cleans deposits such as residual developer remaining on the surface of the photosensitive drum 1. For example, urethane rubber is pressed against the photosensitive drum 1. The rubbing roller 7 is disposed in pressure contact with the surface of the photosensitive drum 1 and has a function of a cleaning body that collects and discharges toner remaining on the surface of the photosensitive drum 1. The rubbing roller 7 has a configuration in which a metal shaft is covered with foamed rubber, and is urged against the photosensitive drum 1 by a spring (not shown).

 The paper feed roller 8 is a roller for feeding the paper P stacked in the paper cassette one by one. The paper P fed by the paper feed roller 8 is transported between the secondary transfer counter roller 5e and the secondary transfer roller 5f by the paper transport roller 9, and the toner image is transferred to the fixing unit 10. Be transported. The fixing unit 10 includes a heating roller 10a that is a fixing body that is rotatably arranged, and a pressure roller 10b that is a pressure body that rotates while being pressed against the heating roller 10a. The sheet P conveyed to the fixing unit 10 is heated and pressed at a constant temperature and pressure from both the front and back sides when passing between the heating roller 10a and the pressure roller 10b. As a result, the toner image on the paper P is melted and fixed, and a full-color image is formed on the paper P. The paper P after the fixing process is transported to the paper discharge roller 12 by the paper transport roller 11 and is discharged to a paper discharge tray installed outside by the paper discharge roller 12.

  FIG. 2 is a functional block configuration diagram of the image forming apparatus 100 described above. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 2, reference numeral 20 is a CPU (Central Processing Unit), reference numeral 21 is a ROM (Read Only Memory), reference numeral 22 is a RAM (Random Access Memory), reference numeral 23 is a flash memory, reference numeral 24 is an operation display section, Reference numeral 25 is a communication I / F, reference numeral 26 is a first motor driver, reference numeral 27 is a first DC brushless motor, reference numeral 28 is a gear unit, reference numeral 29 is an encoder, reference numeral 30 is a second motor driver, reference numeral 31 is A second DC brushless motor (rubbing roller motor), 32 is a clutch device (connection switching unit). Reference numeral 200 denotes a PC (Personal Computer) for instructing the image forming apparatus 100 to print from the outside.

  The CPU 20 executes a control program stored in the ROM 21, image data stored in the flash memory 23, an operation signal input from the operation display unit 24, a pulse signal input from the encoder 29, and a second DC Based on the FG signal input from the brushless motor 31, the print instruction signal received from the PC 200 via the communication I / F 25, and the print image data (that is, print job), each function unit (photosensitive member) in the image forming apparatus 100. (Including drum 1, charging unit 2, exposure unit 3, developing unit 4, transfer unit 5, rubbing roller 7, paper feed roller 8, paper transport roller 9, fixing unit 10, paper transport roller 11 and paper discharge roller 12) Is integrated control.

  The CPU 20 detects the rotation speed of the photosensitive drum 1 by counting the pulse signal interrupted from the encoder 29 by a software counter as rotational drive control of the photosensitive drum 1, and rotates the photosensitive drum 1. PID calculation is performed so that the speed matches the preset target rotation speed (in other words, the speed deviation between the target rotation speed and the rotation speed becomes zero), and the operation amount obtained by the PID calculation is calculated. It has a function of outputting a corresponding PWM (Pulse Width Modulation) signal to the first motor driver 26 (that is, a function of performing PID control of the first DC brushless motor 27).

Further, the CPU 20 detects the rotational speed of the rubbing roller 7 by counting the FG signal interrupted from the second DC brushless motor 31 by a software counter as the rotational drive control of the rubbing roller 7. PID calculation is performed so that the speed deviation amount ΔV ′ between the detected rotation speed Vc ′ and the target rotation speed Vt ′ of the rubbing roller 7 becomes zero, and a PWM signal corresponding to the operation amount obtained by the PID calculation is generated. It also has a function of outputting to the second motor driver 30 (that is, a function of performing PID control of the second DC brushless motor 31) and a function of controlling the rotation direction of the rubbing roller 7.
This PID control is calculated by software in the CPU 20.

  Further, as a characteristic operation in the present embodiment, the CPU 20 causes the photosensitive drum 1 to be in a stable driving state (a state where the rotational speed of the photosensitive drum 1 is stable and matches the target rotational speed) for each print job. In this case, the integral value calculated by the integral calculation process of the speed deviation amount in the PID control at that time is acquired as drive load information of the photosensitive drum 1 and stored in the flash memory 23, and the acquired integral value On the basis of this, the second DC brushless motor 31 and the clutch device 32 constituting the cleaning force adjusting unit are controlled, so that the rubbing roller 7 against the surface of the photosensitive drum 1 according to the magnitude of the driving load of the photosensitive drum 1 is obtained. To control the cleaning power. Details of the operation of the CPU 20 will be described later.

 The ROM 21 is a nonvolatile memory that stores a control program used by the CPU 20 and other setting data (for example, a target rotation speed, a proportional gain constant, an integral gain constant, a differential gain constant, etc. used in PID control). The RAM 22 is a volatile working memory used as a temporary data storage destination when the CPU 20 executes a control program and performs various operations. The flash memory 23 is a rewritable nonvolatile memory that is used to store image data transmitted from the PC 200 and the integrated value of the speed deviation amount.

  The operation display unit 24 is constituted by, for example, a touch panel, displays a screen for notifying various operation keys and various information under the control of the CPU 20, and operates operation input information of various operation keys displayed on the touch panel. It outputs to CPU20 as a signal. The communication I / F 25 is an interface for performing communication between the image forming apparatus 100 (specifically, the CPU 20) and an external PC 200, and is connected to the PC 200 via a network such as a LAN (Local Area Network).

 The first motor driver 26 includes a semiconductor switching element that turns on / off the DC drive voltage applied to the first DC brushless motor 27 in accordance with the PWM signal input from the CPU 20, and is the same as the PWM signal. A DC drive voltage having a duty ratio is supplied to the first DC brassless motor 27. The first DC brushless motor 27 is a motor that rotates by a DC drive voltage supplied from the first motor driver 26, and the rotation shaft thereof is connected to the rotation shaft of the photosensitive drum 1 via the gear portion 28. ing. The encoder 29 is provided on an axis of rotation of the photosensitive drum 1, and includes an encoder plate 29a that rotates in synchronization with the photosensitive drum 1, and an encoder sensor (for example, an optical sensor) 29b that is disposed so as to sandwich the encoder plate 29a. The encoder sensor 29b outputs a rectangular wave pulse signal when a plurality of slits formed along the circumferential direction of the encoder plate 29a pass light. That is, the encoder 29 (specifically, the encoder sensor 29b) outputs a pulse signal corresponding to the rotational speed of the photosensitive drum 1 to the CPU 20.

 The second motor driver 30 includes a semiconductor switching element that turns on / off the DC drive voltage applied to the second DC brushless motor 31 in accordance with the PWM signal input from the CPU 20, and is identical to the PWM signal. A DC drive voltage having a duty ratio is supplied to the second DC brassless motor 31. The second DC brushless motor 31 is a motor that rotates by a DC drive voltage supplied from the second motor driver 30, and its rotation shaft is connected to the rotation shaft of the rubbing roller 7 via the clutch device 32. ing. Further, the second DC brushless motor 31 outputs an FG signal, which is a pulse signal corresponding to its own rotation speed, to the CPU 20. The clutch device 32 includes a first clutch plate 32 a provided on the rotating shaft side of the second DC brushless motor 31 and a second clutch plate 32 b provided on the rotating shaft side of the rubbing roller 7. Under the control of the CPU 20, the mechanical connection / disconnection between the rotating shaft of the second DC brushless motor 31 and the rotating shaft of the rubbing roller 7 is switched.

  Of the above components, at least the CPU 20, ROM 21, RAM 22, flash memory 23, first motor driver 26, second DC brushless motor 27, gear unit 28, encoder 29, photosensitive drum 1, second drum The motor driver 30, the second DC brushless motor 31, the clutch device 32, and the rubbing roller 7 constitute a rotational drive device.

  Next, the operation of the image forming apparatus 100 configured as described above, particularly the operation related to the rotational drive control of the photosensitive drum 1 in the CPU 20 will be described with reference to the flowchart of FIG. In the initial state, the clutch device 32 is in a disconnected state, that is, a state where the rotation shaft of the second DC brushless motor 31 and the rotation shaft of the rubbing roller 7 are separated. That is, the rubbing roller 7 is in a state of being driven by the rotation of the photosensitive drum 1.

  As shown in FIG. 3, first, when the CPU 20 receives a print instruction signal and print image data from the PC 200 and detects the occurrence of a print job (step S1), the CPU 20 sets setting data (photosensitive data) used for PID control. The target rotational speed Vt, the proportional gain constant Kp, the integral gain constant Ki, and the differential gain constant Kd) of the body drum 1 are read (step S2).

  Then, the CPU 20 detects the rotation speed of the photosensitive drum 1 by counting the pulse signal input from the encoder 29 by the software counter (step S3). Hereinafter, the current value of the rotational speed detected in step S3 is assumed to be Vc (n). Further, since the pulse signal is not output from the encoder 29 in the initial state where the photosensitive drum 1 has not started rotating, the rotational speed Vc (n) = 0.

  Subsequently, the CPU 20 calculates a speed deviation amount ΔV (n) between the target rotational speed Vt and the current rotational speed value Vc (n) (step S4). Then, the CPU 20 determines whether or not the photosensitive drum 1 is in a stable driving state based on the speed deviation amount ΔV (n) (step S5). Here, the stable driving state refers to a state where the rotational speed Vc (n) of the photosensitive drum 1 is stable and coincides with the target rotational speed Vt. For example, in this embodiment, when the current value ΔV (n) of the speed deviation amount becomes zero continuously several times, it is determined that the photosensitive drum 1 is in a stable driving state.

If it is determined in step S5 that the photosensitive drum 1 is not in a stable drive state (“No”), the CPU 20 performs proportional element calculation processing, integral element calculation processing, and differential element calculation processing related to PID control in parallel. Run. Specifically, the CPU 20 calculates the proportional operation amount Cp (n) based on the following equation (1) composed of the current value ΔV (n) of the speed deviation amount and the proportional gain constant Kp as the proportional element calculation process. (Step S6).
Cp (n) = Kp × ΔV (n) (1)

In addition, as an integral element calculation process, the CPU 20 calculates the speed based on the following equation (2) including the current value ΔV (n) of the speed deviation amount and the previous value Vi (n−1) of the integrated value of the speed deviation amount. The current value Vi (n) of the integrated value of the deviation amount is calculated (step S7), and the integration is performed based on the following equation (3) consisting of the current value Vi (n) of the integrated value of the speed deviation amount and the integral gain constant Ki. A manipulated variable Ci (n) is calculated (step S8).
Vi (n) = ΔV (n) + Vi (n−1) (2)
Ci (n) = Ki × Vi (n) (3)

Further, as the differential element calculation process, the CPU 20 calculates the speed deviation amount based on the following equation (4) consisting of the current value ΔV (n) of the speed deviation amount and the previous value ΔV (n−1) of the speed deviation amount. The current value Vd (n) of the differential value is calculated (step S9), and the differential manipulated variable Cd based on the following equation (5) consisting of the current value Vd (n) of the differential value of the speed deviation amount and the differential gain constant Kd. (n) is calculated (step S10).
Vd (n) = ΔV (n) −ΔV (n−1) (4)
Cd (n) = Kd × Vd (n) (5)

Then, the CPU 20 calculates the final manipulated variable based on the following equation (6) consisting of the proportional manipulated variable Cp (n), integral manipulated variable Ci (n), and differentiated manipulated variable Cd (n) calculated as described above. This time value C (n) is calculated (step S11).
C (n) = Cp (n) + Ci (n) + Cd (n) (6)

  The CPU 20 performs a software limiter process on the final value C (n) of the final operation amount calculated in step S12 (step S12), and then generates a PWM signal corresponding to the current value C (n) of the operation amount. Then, the data is output to the first motor driver 26 (step S13). As a result, a DC drive voltage having the same duty ratio as that of the PWM signal is supplied from the first motor driver 26 to the first DC brassless motor 27, and rotation of the photosensitive drum 1 is started.

  Then, the CPU 20 determines whether or not the print job has ended (step S14), and if the print job has not ended ("No"), the process returns to step S3. The CPU 20 loops the processing of steps S3 to S14 during the period until the print job ends (that is, the period until the end determination of the print job occurs in step S14), so that the rotation speed of the photosensitive drum 1 is increased. The PID control is continued so as to coincide with the target rotation speed Vt. If it is determined in step S5 that the photosensitive drum 1 is in a stable driving state (“Yes”), the CPU 20 uses the integral value Vi (n) of the speed deviation amount at this time for the photosensitive drum 1. After being acquired as drive load information and stored in the flash memory 23, PID control is continued until the print job is completed (step S15). Since the integrated value Vi (n) of the speed deviation amount does not change after the photosensitive drum 1 is in the stable drive state, the process of step S15 need only be performed once.

  Although not shown in FIG. 3, when the photosensitive drum 1 is in a stable driving state, the CPU 20 controls the paper feed roller 8 and the paper transport roller 9 to secondary transfer the paper P from the paper cassette. The toner image formed on the photosensitive drum 1 is transferred to the sheet P by being conveyed between the opposing roller 5e and the secondary transfer roller 5f and controlling the charging unit 2, the exposure unit 3, the developing unit 4, and the transfer unit 5. Then, the fixing unit 10 is controlled to fix the toner on the paper P, and then the paper transport roller 11 and the paper discharge roller 12 are controlled to discharge the paper P on which a full color image is formed (printed). The image forming process of discharging to the paper tray is performed in parallel.

 When the print job is completed by such an image forming process and it is determined in step S14 that the print job is completed (“Yes”), the CPU 20 reads the latest integrated value Vi ( n) is read (step S16), and it is determined whether or not the integrated value Vi (n) of the speed deviation amount is larger than a predetermined threshold value ViTH (step S17).

 In the PID control, when the driving load of the driving object (here, the photosensitive drum 1) increases, the integrated value (here, the integrated value Vi (n) of the speed deviation amount) calculated by the integral element calculation process also increases. That is, the state of the driving load of the photosensitive drum 1 can be known from the integrated value Vi (n) of the speed deviation amount. One cause of the increase in the driving load of the photosensitive drum 1 is a deposit (residual developer, toner, etc.) on the surface of the photosensitive drum. Therefore, by controlling the cleaning force of the rubbing roller 7 with respect to the surface of the photosensitive drum according to the magnitude of the driving load of the photosensitive drum 1, it is possible to perform cleaning according to the contamination state of the surface of the photosensitive drum. As a result, the driving load can be reduced.

 Specifically, if the integrated value Vi (n) ≦ threshold value ViTH (“No”) in step S <b> 17, the contamination state of the surface of the photosensitive drum is not deteriorated enough to change the cleaning force of the rubbing roller 7. Because of this, the CPU 20 controls the clutch device 32 to disconnect the rotation shaft of the second DC brushless motor 31 and the rotation shaft of the rubbing roller 7 (step S18). FIG. 4A shows the rotation state of the photosensitive drum 1 and the rubbing roller 7 in this case. As shown in FIG. 4A, when the clutch device 32 is in a disconnected state, the rubbing roller 7 is in a state of being driven by the rotation of the photosensitive drum 1. At this time, the rotation direction of the rubbing roller 7 is opposite to the rotation direction of the photosensitive drum 1. That is, in this case, the cleaning force of the rubbing roller 7 on the surface of the photosensitive drum is not different from the initial state.

 On the other hand, if the integrated value Vi (n)> threshold ViTH (“Yes”) in step S17, the contamination state of the surface of the photosensitive drum is deteriorated to the extent that the cleaning force of the rubbing roller 7 needs to be changed. Therefore, the CPU 20 controls the clutch device 32 to connect the rotation shaft of the second DC brushless motor 31 and the rotation shaft of the rubbing roller 7 (step S19). Then, the CPU 20 controls the second DC brushless motor 31 so that the rotation direction of the rubbing roller 7 is the same as the rotation direction of the photoconductor drum 1, thereby cleaning the rubbing roller 7 with respect to the surface of the photoconductor drum. The force is increased (step S20).

 FIG. 4B shows the rotation state of the photosensitive drum 1 and the rubbing roller 7 in this case. As shown in FIG. 4B, when the clutch device 32 is in the connected state, the rotation direction of the rubbing roller 7 and the rotation direction of the photosensitive drum 1 are the same direction (so-called counter drive state). The polishing force on the contact surface of the is increased. That is, in this case, the cleaning force of the rubbing roller 7 with respect to the surface of the photosensitive drum is increased, so that deposits on the surface of the photosensitive drum are easily cleaned, and as a result, the driving load of the photosensitive drum 1 is reduced.

 The control of the second DC brushless motor 31 in step S20 may use the same method as the control of the first DC brushless motor 27. In other words, the target rotational speed Vt ′, the proportional gain constant Kp ′, the integral gain constant Ki ′, and the differential gain constant Kd ′ for the rubbing roller 7 are read from the ROM 21 and an FG signal is input from the second DC brushless motor 31 as an interrupt. PID control of the second DC brushless motor 31 is performed so that the speed deviation amount ΔV ′ between the rotational speed Vc ′ of the rubbing roller 7 detected based on the above and the target rotational speed Vt ′ of the rubbing roller 7 becomes zero. Just do it.

 As described above, according to the image forming apparatus 100 according to the present embodiment, the load detecting unit for detecting the driving load of the driving object is not provided as in the related art, that is, the component cost is increased and the component mounting space is expanded. In this case, the driving load of the object to be driven (photosensitive drum 1) can be detected, and the driving load can be reduced according to the detected driving load.

In addition, this invention is not limited to the said embodiment, The following modifications can be considered.
(1) In the above embodiment, after the print job is completed, the rotation control of the rubbing roller 7 is performed when the integral value Vi (n) of the speed deviation amount is larger than the predetermined threshold value ViTH. 7 is not limited to this. For example, when the integral value Vi (n) of the speed deviation amount is larger than a predetermined threshold value ViTH, a predetermined flag is set to “1” and the next time If the flag is set to “1” when a print job occurs, rotation control of the rubbing roller 7 may be performed before the actual image forming process is performed.

  Alternatively, as the execution timing of the rotation control of the rubbing roller 7, the integrated value Vi (n) of the speed deviation amount is read from the flash memory 23 at the next power-on or warm-up, and the integrated value Vi ( When n) is larger than a predetermined threshold value ViTH, rotation control of the rubbing roller 7 may be performed. Alternatively, during printing, it is determined whether or not the integrated value Vi (n) of the speed deviation amount is larger than a predetermined threshold value ViTH. If it is determined that the speed deviation amount is larger, the printing operation is forcibly stopped and the rubbing roller is stopped. 7 rotation control may be performed. Alternatively, when the integral value Vi (n) of the speed deviation amount is larger than a predetermined threshold value ViTH, a screen that prompts the user to perform rotation control of the rubbing roller 7 may be displayed on the operation display unit 24.

(2) In the above embodiment, as the rotation control of the rubbing roller 7 in step S20, the second DC brushless motor 31 is controlled so that the rotation direction of the rubbing roller 7 is the same as the rotation direction of the photosensitive drum 1. However, the present invention is not limited to this, and the second DC brushless motor 31 is controlled so that the rotation direction of the rubbing roller 7 is the same as or opposite to the rotation direction of the photosensitive drum 1. At the same time, the second DC brushless motor 31 may be controlled so that the rotational speed of the rubbing roller 7 is increased to increase the cleaning force of the rubbing roller 7 on the surface of the photosensitive drum. In this case, the target rotational speed Vt ′ for the rubbing roller 7 may be set high.

(3) In the above embodiment, the case where the cleaning force on the surface of the photosensitive drum is increased by controlling the rotation of the rubbing roller 7 has been described as an example. However, the cleaning blade 6 which is also one of the cleaning bodies. May be used to increase the cleaning force on the surface of the photosensitive drum. Specifically, for example, an actuator (cleaning force adjusting unit) 40 for adjusting the pressing force of the cleaning blade 6 against the photosensitive drum 1 is provided, and when the integrated value Vi (n) is less than or equal to the threshold value ViTH by the CPU 20. As shown in FIG. 5A, the actuator 40 is controlled to set the pressing force of the cleaning blade 6 against the photosensitive drum 1 to the initial set value, while the integrated value Vi (n) exceeds the threshold value ViTH. In this case, as shown in FIG. 5B, the actuator 40 is controlled so that the pressing force of the cleaning blade 6 against the photosensitive drum 1 is set higher than the initial set value, whereby the cleaning blade 6 against the surface of the photosensitive drum 1 is set. Increase cleaning power.

(4) After the image forming apparatus 100 is manufactured, the integrated value Vi (n) at the time of stable driving of the first photosensitive drum 1 in a new state is stored in the flash memory 23 as the initial value Vini, and the next and subsequent photosensitive operations are performed. The difference value between the integral value Vi (n) acquired when the body drum 1 is driven and the initial value Vini may be compared with a predetermined threshold value.

(5) In the above embodiment, the photosensitive drum 1 has been described as an example of a driving target. However, the present invention can be applied to any driving target that is driven by feedback control having at least an integral element. . Further, as feedback control, the present invention can be applied not only to PID control but also to PI control.

(6) In the above embodiment, the printer is exemplified as the image forming apparatus 100. However, in addition to this, a multifunction machine having functions such as a copier, printer, and FAX, and a single OA device such as a copier and FAX. The present invention can also be applied to the above.

1 is a schematic configuration diagram of an image forming apparatus 100 according to an embodiment of the present invention. 1 is a functional block diagram of an image forming apparatus 100 according to an embodiment of the present invention. 3 is an operation flowchart of the image forming apparatus 100 according to an embodiment of the present disclosure. FIG. 6 is a supplementary diagram regarding the operation of the image forming apparatus 100 according to an embodiment of the present invention. 7 is a modification of the image forming apparatus 100 according to an embodiment of the present disclosure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 1 ... Photosensitive drum, 2 ... Charging part, 3 ... Exposure part, 4 ... Development part, 5 ... Transfer part, 6 ... Cleaning blade, 7 ... Rub roller, 8 ... Paper feed roller, 9 DESCRIPTION OF SYMBOLS ... Paper conveyance roller, 10 ... Fixing unit, 11 ... Paper conveyance roller, 12 ... Paper discharge roller, 20 ... CPU (Central Processing Unit), 21 ... ROM (Read Only Memory), 22 ... RAM (Random Access Memory), 23 DESCRIPTION OF SYMBOLS ... Flash memory, 24 ... Operation display part, 25 ... Communication I / F, 26 ... Motor driver, 27 ... DC brushless motor, 28 ... Gear part, 29 ... Encoder, 30 ... 2nd motor driver, 31 ... 2nd DC brushless motor, 32 ... clutch device, 40 ... actuator, 200 ... PC (Personal Computer)

Claims (3)

The motor is controlled by feedback control having a motor for rotationally driving the photosensitive drum, a rubbing roller and a cleaning blade arranged in pressure contact with the photosensitive drum to clean the surface of the photosensitive drum, and at least an integral element. And an image forming apparatus including a control unit that performs integrated control of an image forming operation by an electrophotographic method,
A rubbing roller motor for rotationally driving the rubbing roller;
A connection switching unit for switching mechanical connection / disconnection between the rotation shaft of the rubbing roller motor and the rotation shaft of the rubbing roller;
An actuator for adjusting the pressing force of the cleaning blade against the photosensitive drum,
The control unit acquires an integral value calculated by an integral element of the feedback control as drive load information of the photosensitive drum, and controls the actuator to control the photosensitive drum when the integral value is a predetermined threshold value or less. The pressing force of the cleaning blade against the body drum is set to an initial setting value, and the connection switching unit is controlled so that the rotation shaft of the rubbing roller motor and the rotation shaft of the rubbing roller are disconnected, and the integration When the value exceeds a predetermined threshold value, the actuator is controlled so that the pressing force of the cleaning blade against the photosensitive drum is higher than the initial set value, whereby the cleaning blade against the surface of the photosensitive drum is The cleaning force is increased, and the rotation of the rubbing roller and the rotation shaft of the rubbing roller motor are controlled by controlling the connection switching unit. With connecting the door to control the rotational state of the rubbing said with respect to the photosensitive drum surface by controlling the roller motor rubbing the sliding as the cleaning force of the roller is increased friction roller,
An image forming apparatus. The control unit increases the cleaning force by controlling the rubbing roller motor so that the rotation direction of the rubbing roller is the same as the rotation direction of the photosensitive drum. The image forming apparatus according to 1 . The control unit controls the rubbing roller motor so that the rotation direction of the rubbing roller is the same as or opposite to the rotation direction of the photosensitive drum, and the rubbing roller 2. The image forming apparatus according to claim 1, wherein the cleaning force is increased by controlling the rubbing roller motor so as to increase a rotational speed .

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