Image forming device

Abstract

To provide a technique that can prevent rupture of a cleaning web even if the amount of toner attached to a recovery roller increases.SOLUTION: An image processing apparatus 100 comprises: a fixing roller 201; a recovery roller 204; and a cleaning unit 210 that has a supply roller 211, a take-up roller 214, and a pressing roller 213. A web motor 240 is configured to drive the take-up roller 214. A load driving circuit 153 has a torque detection unit 154 that detects the torque of the web motor 240 and is configured to drive the web motor 240. When a torque detection value output from the torque detection unit 154 during the drive of the web motor 240 exceeds a threshold, a CPU 151 causes the load driving circuit 153 to stop the drive of the web motor 240.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] An electrophotographic image forming apparatus has a fixing device that fixes a toner image formed on a recording material to the recording material. When a jam occurs in the fixing device, unfixed toner may adhere to a fixing member (fixing roller) of the fixing device. Therefore, after the recording material that caused the jam is removed from the fixing device, the fixing roller may be cleaned.

[0003] For example, such cleaning is performed by rotating the fixing roller with a cleaning web (cleaning member) made of nonwoven fabric in contact with the fixing roller and wiping off the toner adhering to the fixing roller with the cleaning web. Patent Document 1 describes a technology in which a cleaning web is supplied from a web supply shaft (roller) by rotating a web winding shaft (roller) by turning a web feed solenoid ON / OFF via a one-way clutch. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-282029 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the image forming apparatus as described above, a large amount of toner may adhere to the fixing roller and the recovery roller that is interposed between the fixing roller and the cleaning web and recovers the toner from the fixing roller. For example, after a jam is cleared or when the heat required for the fixing process is insufficient due to an incorrect recording material setting, a large amount of toner may adhere to the fixing roller and the recovery roller. This leads to an increase in the friction force between the recovery roller and the cleaning web that cleans the recovery roller. As a result, the recovery roller and the cleaning web pull against each other, and the cleaning web may break. If the cleaning web breaks, the toner adhered to the fixing roller cannot be removed, resulting in a defective image. In addition, the cleaning web must be replaced.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a technique capable of preventing the cleaning web from breaking even when the amount of toner adhering to the collection roller increases. [Means for solving the problem]

[0007] An image forming apparatus according to one aspect of the present invention includes a cleaning unit having a fixing member that fixes a toner image transferred onto a recording material to the recording material, a collection roller that collects toner adhering to the fixing member, a cleaning web that cleans the collection roller, a first roller around which the cleaning web is wound in advance, a second roller that takes up the cleaning web supplied from the first roller, and a third roller that is disposed opposite the collection roller and presses the cleaning web, which is sent from the first roller toward the second roller as the second roller rotates, against the collection roller in order to clean the collection roller, a motor that drives the second roller, and a drive motor. Driving current flowing through the winding A detection means for detecting A parameter value that varies depending on the load torque of the motor is determined based on the drive current detected by the detection means, and the drive current supplied to the winding is controlled based on the parameter value. The present invention is provided with a driving means for driving the motor, and a control means for controlling the driving means, and the control means The parameter value is a predetermined value When the detected value exceeds the threshold value, the driving means stops driving the motor. Effect of the Invention

[0008] According to the present invention, even if the amount of toner adhering to the collection roller increases, the cleaning web can be prevented from breaking. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of an image forming apparatus. [Figure 2-1] FIG. 2 is a diagram showing an example of the configuration of a fixing unit; [Figure 2-2] FIG. 2 is a diagram showing an example of the configuration of a fixing unit; [Diagram 3] FIG. 1 is a block diagram showing an example of a control configuration related to control of a fixing unit; [Figure 4-1] A block diagram showing a configuration example of a load driving circuit. [Figure 4-2] Diagram showing the relationship between the motor and the rotating coordinate system [Diagram 5] 1 is a flowchart showing a procedure for executing a print job in an image forming apparatus. [Figure 6] Flowchart showing the procedure of recovery processing (S510) (first embodiment) [Figure 7] Flowchart showing the procedure of recovery processing (S510) (second embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] [First embodiment] <Image forming device> 1 is a cross-sectional view showing an example of the configuration of an image forming apparatus according to a first embodiment. The image forming apparatus 100 conveys a recording material P stored in a storage unit 103 to an image forming unit 110, which then forms a toner image on the recording material P. The image forming apparatus 100 then conveys the recording material P on which the toner image has been formed from the image forming unit 110 to a fixing device 200. The fixing device 200 fixes the toner image on the recording material P to the recording material P. The recording material P is, for example, a sheet of paper or an OHP.

[0012] The image forming apparatus 100 includes an image forming section 110 that forms (prints) an image on a recording material P. The image forming section 110 includes four stations 120a, 120b, 120c, and 120d, each corresponding to a different toner color. The image forming section 110 further includes an intermediate transfer belt 115 and a transfer roller 116. The stations 120a, 120b, 120c, and 120d form toner images of yellow, magenta, cyan, and black, respectively, and transfer the formed toner images to the intermediate transfer belt 115. The following mainly describes the configuration of the station 120a, but the stations 120b, 120c, and 120d also have the same configuration as the station 120a.

[0013] The station 120a includes a photosensitive drum 111, a primary charger 112, a laser unit 113, and a developing unit 114. The photosensitive drum 111 is an example of an image carrier, and rotates counterclockwise (in the direction of the arrow) in FIG. 1. The primary charger 112 uniformly charges the surface of the photosensitive drum 111. The laser unit 113 has a light source that outputs laser light, and forms an electrostatic latent image on the photosensitive drum 111 by exposing the charged surface of the photosensitive drum 111 to the laser light. The developing unit 114 develops the electrostatic latent image formed on the photosensitive drum 111 with toner (developing agent), thereby forming a toner image on the photosensitive drum 111. Toner images are also formed on the photosensitive drums of the stations 120b, 120c, and 120d in the same manner.

[0014] The toner images formed on the photosensitive drums at stations 120a, 120b, 120c, and 120d are transferred onto intermediate transfer belt 115. As the circumferential surface of intermediate transfer belt 115 moves, the toner image on intermediate transfer belt 115 moves to a transfer position where transfer of the toner image onto recording material P is performed by transfer roller 116. Transfer roller 116 transfers the toner image on intermediate transfer belt 115 onto recording material P transported from storage unit 103. The recording material P onto which the toner image has been transferred is transported from image forming unit 110 to fixing unit 200.

[0015] The fixing device 200 has a fixing roller 201 (fixing member), a pressure roller 202 (pressure member), and a cleaning unit 210. The fixing device 200 applies heat and pressure to the recording material P to fix the toner image transferred to the recording material P to the recording material P. As will be described later, the cleaning unit 210 is configured to clean the fixing roller 201 by removing unfixed toner adhering to the fixing roller 201.

[0016] In the case of single-sided printing, the image forming apparatus 100 discharges the recording material P, which has been processed by the image forming unit 110 and the fixing device 200, to the outside of the apparatus by guiding the recording material P to a discharge path 139 by a flapper 132. The flapper 132 operates to selectively guide the recording material P, which has passed through the fixing device 200, to a conveying path 134 or a discharge path 139.

[0017] On the other hand, in the case of double-sided printing, the image forming apparatus 100 conveys the recording material P, on which image formation on the first side has been completed, to the image forming section 110 again so that image formation on the second side can be performed. Specifically, the image forming apparatus 100 guides the recording material P, which has passed through the fixing device 200, to a conveying path 134 by a flapper 132, and conveys the recording material P to an inversion section 136. When the rear end of the recording material P is detected by an inversion sensor 135, the image forming apparatus 100 reverses the conveying direction of the recording material P by the inversion section 136, and guides the recording material P to a conveying path 137 by the flapper 135. The image forming apparatus 100 further conveys the recording material P to the image forming section 110 (transfer position by the transfer roller 116) through the conveying path 137, and further conveys the recording material P, on which the toner image has been transferred to the second side, to the fixing device 200. The fixing process by the fixing device 200 completes image formation on both sides (first side and second side) of the recording material P. The image forming apparatus 100 guides the recording material P that has passed through the fixing device 200 to a discharge path 139 by a flapper 132, thereby discharging the recording material P to the outside of the apparatus.

[0018] The image forming apparatus 100 further includes a control board 150 and an operation unit 180. The operation unit 180 has a display unit capable of displaying various screens, and an operation input unit including operation keys that can be operated by a user. The display unit is used to display the state of the image forming apparatus 100 and the operation screen, etc. The operation input unit is used to receive instructions from a user. The operation input unit may include a touch panel disposed on the display unit.

[0019] The control board 150 includes a CPU 151 and a memory 152. The CPU 151 functions as a control unit that controls the overall operation of the image forming apparatus 100 by controlling each device in the image forming apparatus 100. The CPU 151 controls each device in the image forming apparatus 100 based on signals output from each sensor in the image forming apparatus 100 and information (data) stored in the memory 152. The memory 152 stores data required for controlling each device, and the data can be used by the CPU 151.

[0020] <Configuration of Fixing Unit 200> 2-1 and 2-2 are diagrams showing an example of the configuration of the fixing unit 200 in this embodiment. FIG. 2-1(A) shows an example of the state of the fixing unit 200 in a cleaning state in which the cleaning unit 210 cleans the fixing roller 201. FIG. 2-1(B) shows an example of the state of the fixing unit 200 in a standby state. FIG. 2-2 shows an example of the state of the fixing unit 200 in a refresh state in which the refreshing roller 220 refreshes the fixing roller 201.

[0021] 3 is a block diagram showing an example of a control configuration related to control of the fixing device 200. The control board 150 includes a CPU 151, a memory 152, and a load driving circuit 153. The CPU 151 controls the load driving circuit 153, and controls the operation of each electric component in the fixing device 200 (various motors, various sensors, halogen heater 205, thermistor 206, etc.).

[0022] The load driving circuit 153 is configured to drive the web motor 240, the attachment / detachment motor 241, the halogen heater 205, the fixing motor 244, and the attachment / detachment motor 245 under the control of the CPU 151. The load driving circuit 153 also has a torque detection unit 154 that detects the torque of the web motor 240. The attachment / detachment motor 241 drives an attachment / detachment mechanism (not shown) that attaches and detaches the cleaning unit 210, the collection roller 204, and the fixing roller 201. The collection roller 204 can be switched between a contact state in which it is in contact with the web 212 and a non-contact state in which it is separated from the web 212 by this attachment / detachment mechanism. The attachment / detachment motor 245 drives an attachment / detachment mechanism (not shown) that attaches and detaches the refresh roller 220 to and from the fixing roller 201. The refresh roller 220 can be switched between a contact state in which it is in contact with the fixing roller 201 and a non-contact state in which it is separated from the fixing roller 201 by this attachment / detachment mechanism. In this embodiment, the load driving circuit 153 has a detection means (torque detection unit 154) for detecting the torque of the motor and is an example of a driving means for driving the motor, and the CPU 151 is an example of a control means for controlling the driving means (load driving circuit 153).

[0023] 2-1 and 2-2, the fixing device 200 includes a fixing roller 201 (fixing member), a pressure roller 202 (pressure member), a collection roller 204, a thermistor 206, a cleaning unit 210, a refresh roller 220, and a web motor 240. A fixing process of the toner image on the recording material P is performed in a nip portion formed between the fixing roller 201 (fixing member) and the pressure roller 202 (pressure member).

[0024] Fixing roller 201 is configured as a hollow roller, and has halogen heater 205 as a heat source inside the hollow roller. Thermistor 206 is a sensor for measuring the temperature of fixing roller 201. CPU 151 controls the on / off of halogen heater 205 based on the temperature measured by thermistor 206, thereby maintaining or adjusting the temperature of fixing roller 201 to a predetermined temperature.

[0025] The fixing roller 201 is configured to rotate by being driven (rotationally driven) by a fixing motor 244, and the pressure roller 202 is configured to rotate following the fixing roller 201. The fixing roller 201 and the pressure roller 202 convey the recording material P downstream in the conveying direction (in the direction of the arrow in FIG. 2) while applying heat and pressure to the recording material P at the nip portion between them.

[0026] The collection roller 204 is configured to follow the fixing roller 201 while in contact with the fixing roller (FIG. 2-1(A)) and collect toner (unfixed toner) adhering to the fixing roller 201 (fixing member). The collection roller 204 is configured to be a roller made of, for example, SUS (stainless steel). The cleaning unit 210 is configured to clean the fixing roller 201 by removing the adhering matter adhering to the fixing roller 201 via the collection roller 204.

[0027] The cleaning section 210 has a supply roller 211, a cleaning web 212 (hereinafter simply referred to as "web"), a pressure roller 213, and a take-up roller 214. The take-up roller 214 is rotated by being driven by a web motor 240, and the supply roller 211 is rotated following the take-up roller 214. In this manner, the web motor 240 is an example of a motor that drives the second roller (the take-up roller 214).

[0028] The web 212 is a sheet-like (strip-like) cleaning member made of nonwoven fabric or the like, and cleans the collection roller 204. The web 212 is wound in advance around the supply roller 211 in an unused state. The web 212 is arranged so that an unused portion is sent out (supplied) according to the rotation of the supply roller 211, passes through a pressure roller 213 arranged opposite the collection roller 204, and is wound up by a winding roller 214.

[0029] The pressure roller 213 is configured to press the web 212 against the collection roller 204 in a region of a predetermined width in a width direction perpendicular to the rotation direction. With the web 212 pressed against the collection roller 204 ( FIG. 2-1(A) ), the take-up roller 214 is driven to intermittently take up the web 212 supplied from the supply roller 211, thereby rubbing the web 212 against the collection roller 204. As a result, the toner on the collection roller 204 is wiped off by the unused portion of the web 212 (the portion supplied from the supply roller 211).

[0030] Thus, in this embodiment, the supply roller 211 is an example of a first roller around which a cleaning web is wound in advance, and the take-up roller 214 is an example of a second roller that takes up the cleaning web supplied from the first roller (supply roller 211). The pressure roller 213 is an example of a third roller that is disposed opposite the collection roller 204 and presses the cleaning web, which is sent from the first roller (supply roller 211) toward the second roller as the second roller (take-up roller 214) rotates, against the collection roller 204 to clean the collection roller 204.

[0031] The refreshing roller 220 is composed of a polishing roller with a rough surface. The refreshing roller 220 is used for a refreshing operation to remove scratches or deposits that may occur on the fixing roller 201, for example, when a print job is executed in which images are continuously formed on a large amount of recording material P. During the refreshing operation, the refreshing roller 220 is in contact (pressurized) with the fixing roller 201 (FIG. 2-2) and rotates in accordance with the fixing roller 201.

[0032] <Operational state of the fixing unit 200> In this embodiment, the operation state of the fixing device 200 transitions among a cleaning state (FIG. 2-1(A)), a standby state (FIG. 2-1(B)), and a refresh state (FIG. 2-2).

[0033] In the cleaning state (FIG. 2-1(A)), the cleaning unit 210 and the collection roller 204, and the collection roller 204 and the fixing roller 201 are in contact with each other (pressurized state in which they press each other). In the standby state (FIG. 2-1(B)), the cleaning unit 210, the collection roller 204, and the fixing roller 201 are in a non-contact state in which they are separated from each other (non-pressurized state in which they do not press each other). Switching between the contact state and the non-contact state (attachment / detachment) of the cleaning unit 210, the collection roller 204, and the fixing roller 201 is performed by using an attachment / detachment motor 241 and an attachment / detachment sensor 242. The attachment / detachment sensor 242 is configured to output an ON signal when the collection roller 204 is in contact with the fixing roller 201, and to output an OFF signal when the collection roller 204 is not in contact with the fixing roller 201.

[0034] In the cleaning state and the standby state, the refresh roller 220 is in a non-contact state away from the fixing roller 201. In the refresh state (FIG. 2-2), the refresh roller 220 is in a contact state in which it is in contact with the fixing roller 201. Switching (attaching / detaching) between the contact state and the non-contact state of the refresh roller 220 is performed using an attachment / detachment motor 245 and a refresh sensor 243. The refresh sensor 243 is configured to output an ON signal when the refresh roller 220 is in contact with the fixing roller 201, and to output an OFF signal when the refresh roller 220 is not in contact with the fixing roller 201.

[0035] When performing a cleaning operation by the cleaning unit 210, the CPU 151 operates the attachment / detachment motor 241 until the output of the attachment / detachment sensor 242 switches from an OFF signal to an ON signal, thereby bringing the cleaning unit 210, the collection roller 204, and the fixing roller 201 into a contact state (pressure state).

[0036] When the CPU 151 transitions the operating state of the fixing device 200 from the cleaning state to the standby state, the CPU 151 operates the attachment / detachment motor 241 until the output of the attachment / detachment sensor 242 switches from an ON signal to an OFF signal. This places the cleaning unit 210, the collection roller 204, and the fixing roller 201 in a non-contact state (non-pressurized state). When executing a print job (image formation), the CPU 151 operates the fixing motor 244 in this non-pressurized state to rotate the fixing roller 201. Furthermore, the CPU 151 controls the halogen heater 205 based on the temperature of the fixing roller 201 measured by the thermistor 206 so that the temperature of the fixing roller 201 is maintained within a predetermined range.

[0037] Furthermore, when performing a refresh operation using the refresh roller 220, the CPU 151 operates the attachment / detachment motor 245 until the output of the refresh sensor 243 switches from an OFF signal to an ON signal. This causes the refresh roller 220 to be in contact with the fixing roller 201 (pressurized state). In this pressurized state, the CPU 151 operates the fixing motor 244 to rotate the fixing roller 201, thereby removing scratches or deposits on the surface of the fixing roller 201 with the refresh roller 220.

[0038] <Configuration of the Load Driving Circuit 153> In this embodiment, while the cleaning operation is being performed, the torque (load torque) of the web motor 240 is detected by the torque detection unit 154 provided in the load drive circuit 153, and the operation of the web motor 240 is stopped based on the detection result. For example, when the torque detection value of the web motor 240 exceeds a predetermined threshold value, the operation of the web motor 240 is stopped. This prevents the web 212 from breaking due to a pulling action between the web 212 and the collection roller 204 caused by an increase in friction between the web 212 and the collection roller 204.

[0039] A configuration example of the load drive circuit 153 will be described with reference to Figs. 4-1 and 4-2. A drive configuration for the web motor 240 will be described below, but a similar drive configuration may be used for other motors (attachment / detachment motors 241, 245 and fixing motor 244). In this embodiment, a stepping motor having two phases, A phase (first phase) and B phase (second phase), is used as the web motor 240, and a configuration using vector control is adopted for drive control of the motor. As described below, a current value (current value of q-axis current) in the rotating coordinate system obtained in this configuration is used for detection of the torque of the web motor 240 by the torque detection unit 154.

[0040] FIG. 4-1 is a block diagram showing a configuration example of the load driving circuit 153. The web motor 240 is provided with a phase detection unit 512 for detecting a rotation phase θ of a rotor 401 of the motor. The phase detection unit 512 may be formed of, for example, a rotary encoder. The rotation phase θ may be estimated based on estimated values ​​of induced voltages (back electromotive voltages) Eα and Eβ induced in the A-phase and B-phase windings of the web motor 240 by the rotation of the rotor 401. That is, sensorless control may be applied to the drive control of the web motor 240. In the following description, the motor is controlled based on the rotation phase θ, command phase θ_ref, etc. as electrical angles, but, for example, the electrical angle may be converted into a mechanical angle, and the motor may be controlled based on the mechanical angle.

[0041] FIG. 4-2 is a diagram showing the relationship between the motor and a rotating coordinate system represented by a d-axis and a q-axis. In FIG. 4-2, in the stationary coordinate system, an α-axis corresponding to the A-phase winding and a β-axis corresponding to the B-phase winding are defined. In addition, a d-axis is defined along the direction of the magnetic flux created by the magnetic poles of the permanent magnet used in rotor 401, and a q-axis is defined along the direction 90 degrees counterclockwise from the d-axis (direction perpendicular to the d-axis). The angle between the α-axis and the d-axis is defined as θ, and the rotation phase of rotor 401 is represented by angle θ.

[0042] Vector control uses a rotating coordinate system based on the rotation phase θ of the rotor 401. Specifically, the value of the current component in the rotating coordinate system of a current vector corresponding to the drive current flowing through the windings of the motor (web motor 240) is used. The current vector in the rotating coordinate system includes a q-axis component (torque current component) that generates torque in the rotor 401 and a d-axis component (excitation current component) that affects the strength of the magnetic flux that penetrates the windings. The values ​​of the d-axis component and q-axis component of this current vector are used for vector control.

[0043] Vector control is a control method for controlling a motor by performing phase feedback control that controls the value of torque current component iq and the value of excitation current component id so as to reduce the deviation between a command phase that represents a target phase of the rotor 401 and the actual rotation phase. There is also a control method for controlling a motor by performing speed feedback control that controls the value of torque current component iq and the value of excitation current component id so as to reduce the deviation between a command speed that represents a target speed of the rotor 401 and the actual rotation speed.

[0044] 4-1, the load driving circuit 153 includes a motor control unit 157, a PWM inverter 506, current detectors 507 and 508, an A / D converter 510, and a torque detection unit 154. The motor control unit 157 receives an input of a control signal indicating a command phase θ_ref representing a target phase of the rotor 401 of the web motor 240 from a CPU 151 corresponding to a higher-level controller. The motor control unit 157 is composed of at least one ASIC, and executes each function described below.

[0045] The PWM inverter 506 drives the web motor 240 by supplying a drive current to the windings of the web motor 240 in accordance with a PWM signal based on the drive voltages Vα and Vβ output from the motor control unit 157. The motor control unit 157 performs the above-mentioned vector control, in which the drive current supplied to the web motor 240 is controlled by a current value in a rotating coordinate system based on the rotation phase θ of the rotor 401 of the web motor 240.

[0046] In vector control, a current vector corresponding to the drive current flowing through the A-phase and B-phase windings of the web motor 240 is converted from a stationary coordinate system represented by the α-axis and β-axis to a rotating coordinate system represented by the d-axis and q-axis. As a result of such conversion, the drive current supplied to the web motor 240 is represented by a d-axis component (d-axis current) and a q-axis component (q-axis current) of DC in the rotating coordinate system. In this case, the q-axis current corresponds to a torque current component that generates torque in the web motor 240, and is a current that contributes to the rotation of the rotor 401. The d-axis current corresponds to an excitation current component that affects the strength of the magnetic flux of the rotor 401 of the web motor 240.

[0047] The motor control unit 157 can independently control the q-axis component (q-axis current) and the d-axis component (d-axis current) of the current vector, thereby efficiently generating the torque required for the rotor 401 to rotate.

[0048] The motor control unit 157 performs vector control based on the rotational phase θ detected by the phase detection unit 512. In the outer control loop including the phase controller 502, the phase control of the web motor 240 is performed based on the determined result of the rotational phase θ of the rotor 401 of the web motor 240.

[0049] The CPU 151 generates a command phase θ_ref that indicates a target phase of the rotor 401 of the web motor 240, and outputs the command phase θ_ref to the motor control unit 157 at a predetermined time period. The command phase θ_ref is, for example, a pulsed rectangular wave signal, and one pulse corresponds to the minimum change in the rotation angle of the web motor 240 (stepping motor). The subtractor 551 calculates the deviation between the rotation phase θ of the rotor 401 of the web motor 240 and the command phase θ_ref, and outputs the deviation to the phase controller 502.

[0050] The phase controller 502 generates and outputs a q-axis current command value iq_ref and a d-axis current command value id_ref based on, for example, PID control (proportional control (P), integral control (I), and differential control (D)) so that the deviation output from the subtractor 551 becomes small. Specifically, the phase controller 502 generates and outputs a q-axis current command value iq_ref and a d-axis current command value id_ref based on the PID control so that the deviation output from the subtractor 551 becomes zero. Note that, in the phase controller 502, for example, PI control may be used instead of the PID control. Furthermore, when a permanent magnet is used in the rotor 401, the d-axis current command value id_ref, which affects the strength of the magnetic flux penetrating the winding, is usually set to zero, but this is not limited thereto.

[0051] In a control loop including current controllers 503 and 504, the drive current flowing through each phase winding of the web motor 240 is controlled based on the detection value of the drive current flowing through each phase winding of the web motor 240. Here, the drive currents (AC currents) flowing through the A-phase and B-phase windings of the web motor 240 are detected by current detectors 507 and 508, and then converted from analog values ​​to digital values ​​by an A / D converter 510. The current values ​​of the drive currents converted from analog values ​​to digital values ​​by the A / D converter 510 are expressed as current values ​​iα and iβ in a stationary coordinate system as shown in the following equations. Here, I indicates the magnitude of the amplitude of the current. iα=I*cosθ iβ=I*sinθ (1) These current values ​​iα and iβ are input to a coordinate converter 511.

[0052] The coordinate converter 511 converts the current values ​​iα and iβ in the stationary coordinate system into a current value iq of the q-axis current and a current value id of the d-axis current in the rotating coordinate system by the following equation. id = cosθ*iα+sinθ*iβ iq = -sinθ*iα+cosθ*iβ (2)

[0053] The subtractor 552 receives the q-axis current command value iq_ref output from the phase controller 502 and the current value iq output from the coordinate converter 511. The subtractor 552 calculates the deviation between the q-axis current command value iq_ref and the current value iq, and outputs the deviation to the current controller 503. The subtractor 553 also receives the d-axis current command value id_ref output from the phase controller 502 and the current value id output from the coordinate converter 511. The subtractor 553 calculates the deviation between the d-axis current command value id_ref and the current value id, and outputs the deviation to the current controller 504.

[0054] The current controller 503 generates a drive voltage Vq based on PID control so that the input deviation becomes small. Specifically, the current controller 503 generates a drive voltage Vq so that the input deviation becomes zero, and outputs the drive voltage Vq to the coordinate converter 505. Furthermore, the current controller 504 generates a drive voltage Vd based on PID control so that the input deviation becomes small. Specifically, the current controller 504 generates a drive voltage Vd so that the input deviation becomes zero, and outputs the drive voltage Vd to the coordinate converter 505. Note that in the current controller 503, for example, PI control may be used instead of the PID control.

[0055] The coordinate converter 505 inversely converts the drive voltages Vq and Vd in the rotating coordinate system output from the current controllers 503 and 504 into drive voltages Vα and Vβ in the stationary coordinate system by the following equations. Vα=cosθ*Vd-sinθ*Vq Vβ=sinθ*Vd+cosθ*Vq (3)

[0056] The coordinate converter 505 outputs the converted drive voltages Vα and Vβ to the PWM inverter 506. A full bridge circuit included in the PWM inverter 506 is driven by a PWM (pulse width modulation) signal based on the drive voltages Vα and Vβ input from the coordinate converter 505. As a result, the PWM inverter 506 generates drive currents iα and iβ according to the drive voltages Vα and Vβ, and supplies the drive currents iα and iβ to windings of each phase of the web motor 240 to drive the web motor 240. The PWM inverter 506 may include a half bridge circuit or the like.

[0057] In this embodiment, the current value iq of the q-axis current output from the coordinate converter 511 is input not only to the subtractor 552 but also to the torque detection unit 154. The current value iq of the q-axis current changes according to the torque generated in the web motor 240, and this torque is proportional to the load torque. That is, the current value iq changes according to the load torque of the web motor 240. Therefore, the load torque of the web motor 240 can be detected by detecting the current value iq. The torque detection unit 154 detects the torque (load torque) of the web motor 240 based on the current value iq of the input q-axis current, and outputs a torque detection value. Note that the torque detection value output from the torque detection unit 154 may be the current value iq of the q-axis current itself.

[0058] In this way, the current value iq of the q-axis current changes according to the torque (load torque) of the web motor 240, and this load torque changes according to the frictional force between the web 212 and the collection roller 204. Therefore, in this embodiment, the CPU 151 obtains a torque detection value of the web motor 240 based on the current value iq of the q-axis current, and detects the occurrence of a pulling action between the web 212 and the collection roller 204 by using the torque detection value. Specifically, when the torque detection value exceeds a predetermined value (threshold value), the CPU 151 determines that the frictional force between the web 212 and the collection roller 204 has increased and a pulling action has occurred. In this case, the CPU 151 stops the operation (driving) of the web motor 240 to prevent the web 212 from breaking.

[0059] <Processing Procedure> 5 is a flowchart showing a procedure for executing a print job in the image forming apparatus 100 according to the present embodiment. The processing of each step in FIG. 5 may be realized in the image forming apparatus 100 by the CPU 151 reading and executing a control program stored in the memory 152.

[0060] When the process according to this procedure is started, in S501, the CPU 151 transitions the image forming apparatus 100 to a standby state. In the fixing unit 200 in the standby state, the cleaning unit 210, the collection roller 204, and the fixing roller 201 are in a non-contact state as shown in FIG. 2-1(B). After transition to the standby state, in S502, the CPU 151 waits until a print job is accepted, and when a print job is accepted, the process proceeds to S503. In S503, the CPU 151 controls the operation of each device in the image forming apparatus 100 to start the execution of the print job. When starting the execution of the print job, the CPU 151 transitions the fixing unit 200 to a cleaning state shown in FIG. 2-1(A).

[0061] Next, in S504, CPU 151 drives web motor 240 by load drive circuit 153 in fixing unit 200 in the cleaning state. After starting to drive web motor 240, in S505 CPU 151 determines whether a torque detection value indicating the torque (load torque) of web motor 240 output from torque detection unit 154 (of load drive circuit 153) is below a threshold value. If the torque detection value is below the threshold value, CPU 151 advances the process to S506, and if the torque detection value is equal to or greater than the threshold value, CPU 151 advances the process to S508.

[0062] In S506, the CPU 151 determines whether the operation time of the web motor 240 has reached a time (required time) corresponding to the required winding amount of the web 212. If the operation time of the web motor 240 has not reached the required time, the CPU 151 returns the process to S504 and continues driving the web motor 240. On the other hand, if the operation time of the web motor 240 has reached the required time, the CPU 151 advances the process to S507 and stops driving the web motor 240. This causes the winding operation of the web 212 by the winding roller 214 driven by the web motor 240 to normally end.

[0063] If the torque detection value of the web motor 240 is equal to or greater than the threshold value, the web 212 and the collection roller 204 start to tug against each other, which may lead to the breakage of the web 212. In this case, the CPU 151 stops the driving of the web motor 240 in S508, and suspends the execution of the print job in S509. Then, in S510, the CPU 151 performs a recovery process according to the procedure in FIG. 6, which will be described later. The recovery process is a process for releasing the state in which the torque of the web motor 240 (frictional force between the web 212 and the collection roller 204) is high, and for removing toner adhering to the collection roller 204 and the fixing roller 201.

[0064] When the recovery process in S510 is completed and the high torque state of the web motor 240 is released, in S511, the CPU 151 resumes the execution of the print job. Thereafter, in S512, the CPU 151 determines whether or not to end the execution of the print job. If the CPU 151 does not end the execution of the print job, the process returns to S504, and the above-mentioned process (S504 to S511) is repeated until the execution of the print job is ended. If the CPU 151 ends the execution of the print job, in S513, the CPU 151 transitions the image forming apparatus 100 to a standby state, and ends the process.

[0065] <Recovery process> 6 is a flowchart showing the procedure of the recovery process in S510. First, in S601, CPU 151 drives attachment / detachment motor 241 by load drive circuit 153 in a direction in which collection roller 204 moves away from web 212. CPU 151 drives attachment / detachment motor 241 until the output of attachment / detachment sensor 242 switches from an ON signal to an OFF signal, thereby causing collection roller 204 to change from a contact state (pressurized state) to a non-contact state (non-pressurized state). When the output of attachment / detachment sensor 242 switches to an OFF signal, CPU 151 stops driving attachment / detachment motor 241.

[0066] Next, in S602, CPU 151 determines whether the value of the attachment / detachment counter held in memory 152 is "0". The attachment / detachment counter is used to manage the number of times that attachment / detachment operations (S601 to S604) of cleaning unit 210, collection roller 204, and fixing roller 201 are performed by attachment / detachment motor 241 in the recovery process according to the procedure of Fig. 6. A attachment / detachment counter value of "0" indicates that the current attachment / detachment operation in S601 to S604 is the first one. If the attachment / detachment counter value is "0", CPU 151 advances the process to S603, and if the attachment / detachment counter value is not "0", CPU 151 advances the process to S604.

[0067] In S603, the CPU 151 drives the web motor 240 for a predetermined time by the load driving circuit 153. In this manner, the winding operation of the web 212 by the winding roller 214 driven by the web motor 240 is performed, and the high torque of the web motor 240 (frictional force between the web 212 and the collection roller 204) can be released. Thereafter, the CPU 151 advances the process to S604.

[0068] In S604, CPU 151 drives attachment / detachment motor 241 by load drive circuit 153 in a direction in which collection roller 204 contacts web 212. CPU 151 drives attachment / detachment motor 241 until the output of attachment / detachment sensor 242 switches from an OFF signal to an ON signal, thereby changing collection roller 204 from a non-contact state (non-pressurized state) to a contact state (pressurized state). When the output of attachment / detachment sensor 242 switches to the ON signal, CPU 151 stops driving attachment / detachment motor 241.

[0069] In this way, when the attachment / detachment operation (S601 to S604) of the cleaning unit 210, the collection roller 204, and the fixing roller 201 by the attachment / detachment motor 241 is completed, in S605, the CPU 151 counts up the attachment / detachment counter. Furthermore, in S606, the CPU 151 determines whether the value of the attachment / detachment counter has reached the target value. If the value of the attachment / detachment counter has not reached the target value, the CPU 151 returns the process to S601. As a result, the processes of S601 to S604 are repeated until the value of the attachment / detachment counter reaches the target value (i.e., until the attachment / detachment operation of the cleaning unit 210, the collection roller 204, and the fixing roller 201 has been performed a predetermined number of times). If the value of the attachment / detachment counter has reached the target value, the CPU 151 advances the process to S607.

[0070] In S607, the CPU 151 clears the attachment / detachment counter (initializes it to "0") and proceeds to S608. In S608, the CPU 151 drives the web motor 240 by the load drive circuit 153 for a predetermined time while the collection roller 204 is in contact with the web 212. This causes the toner adhering to the collection roller 204 to be removed by the web 212.

[0071] Thereafter, in S609, CPU 151 determines whether or not a torque detection value indicating the torque (load torque) of web motor 240, output from torque detection unit 154 while web motor 240 is being driven, is below a threshold value. In this way, CPU 151 checks whether the state in which the torque of web motor 240 (frictional force between web 212 and collection roller 204) is high has been released. If the torque detection value is below the threshold value, CPU 151 ends the process according to the procedure in FIG. 6 and proceeds to S511, and if the torque detection value is equal to or greater than the threshold value, proceeds to S610.

[0072] In S610, the CPU 151 determines whether the number of times the processes of S601 to S608 have been executed (the number of repetitions) has reached a predetermined upper limit. In this embodiment, the processes of S601 to S608 are repeatedly executed until the high torque state of the web motor 240 (frictional force between the web 212 and the collection roller 204) is released. However, if the high torque state of the web motor 240 is not released even after the processes of S601 to S608 are repeated and the number of repetitions of the processes reaches the upper limit, the CPU 151 determines that some abnormality has occurred in the web 212. In this case, in S611, the CPU 151 displays a replacement message on the operation unit 180 to prompt the user to replace the web 212, and ends the process according to the procedure of FIGS. 5 and 6.

[0073] As described above, image forming apparatus 100 of this embodiment includes fixing roller 201 (fixing member), collection roller 204, and cleaning unit 210 having web 212, supply roller 211, winding roller 214, and pressure roller 213. Web motor 240 is configured to drive winding roller 214. Load driving circuit 153 has torque detection unit 154 that detects the torque of web motor 240, and is configured to drive web motor 240. CPU 151 causes load driving circuit 153 to stop driving web motor 240 when the torque detection value output from torque detection unit 154 exceeds a threshold value while web motor 240 is being driven.

[0074] In this way, when CPU 151 detects a high torque (frictional force between web 212 and collection roller 204) of web motor 240 while collection roller 204 is being cleaned by web 212, CPU 151 stops driving web motor 240. That is, even if the amount of toner adhering to collection roller 204 increases and the frictional force between web 212 and collection roller 204 increases, breaking of web 212 (cleaning web) can be prevented by stopping driving web motor 240. That is, according to this embodiment, breaking of web 212 (cleaning web) can be prevented even if the amount of toner adhering to collection roller 204 increases.

[0075] As exemplified in this embodiment, the CPU 151 may execute an attachment / detachment operation to switch the collection roller 204 from a contact state to a non-contact state and further switch the non-contact state to a contact state after the drive of the web motor 240 is stopped (S601 and S604). Furthermore, the CPU 151 may drive the web 212 by the load drive circuit 153 for a predetermined time while the collection roller 204 is in a non-contact state with respect to the web 212 (S603). By such control, it is possible to release the state in which the torque of the web motor 240 (frictional force between the web 212 and the collection roller 204) is high.

[0076] Furthermore, the CPU 151 may execute the above-mentioned attachment / detachment operation of the collection roller 204 a predetermined number of times (S606). After executing the predetermined number of attachment / detachment operations, the CPU 151 may drive the web motor 240 for a predetermined time by the load driving circuit 153 (S608), and repeatedly execute the predetermined number of attachment / detachment operations until the torque detection value output from the torque detection unit 154 while the web motor 240 is being driven falls below the threshold value ("YES" in S609). This makes it possible to more reliably prevent breakage of the web 212 (cleaning web). Also, it becomes possible to prevent breakage of the web 212 (cleaning web) with a relatively simple (low-cost) configuration.

[0077] [Second embodiment] In the second embodiment, an example will be described in which, after the driving of the web motor 240 is stopped, the collection roller 204 is switched from a contact state to a non-contact state, and the refreshing roller 220 is switched from a non-contact state to a contact state with the fixing roller 201 to perform a refreshing operation. In the following, differences from the first embodiment will be mainly described, and descriptions of parts common to the first embodiment will be omitted.

[0078] The procedure for executing a print job in the image forming apparatus 100 of this embodiment is the same as that of the first embodiment (FIG. 5). However, the recovery process (S510) that is executed when the torque detection value of the web motor 240 is equal to or greater than the threshold value (NO in S504) is executed according to the procedure in FIG.

[0079] 7, in the recovery process (S510), first, in S701, the CPU 151 drives the attachment / detachment motor 241 by the load drive circuit 153 in a direction in which the collection roller 204 moves away from the web 212. The CPU 151 drives the attachment / detachment motor 241 until the output of the attachment / detachment sensor 242 switches from an ON signal to an OFF signal, thereby causing the collection roller 204 to change from a contact state (pressurized state) to a non-contact state (non-pressurized state). When the output of the attachment / detachment sensor 242 switches to an OFF signal, the CPU 151 stops driving the attachment / detachment motor 241.

[0080] Next, in S702, the CPU 151 drives the web motor 240 by the load drive circuit 153 for a predetermined time while the collection roller 204 is in a non-contact state with the web 212. In this manner, the winding operation of the web 212 by the winding roller 214 driven by the web motor 240 is performed, and the state in which the torque of the web motor 240 (the frictional force between the web 212 and the collection roller 204) is high can be released.

[0081] Furthermore, CPU 151 performs a refresh operation using refresh roller 220. Specifically, in S703, CPU 151 drives attachment / detachment motor 245 by load drive circuit 153 in a direction in which refresh roller 220 contacts fixing roller 201. CPU 151 drives attachment / detachment motor 245 until the output of refresh sensor 243 switches from an OFF signal to an ON signal, thereby changing refresh roller 220 from a non-contact state (non-pressurized state) to a contact state (pressurized state). When the output of refresh sensor 243 switches to the ON signal, CPU 151 stops driving attachment / detachment motor 245.

[0082] Thereafter, in S704, the CPU 151 drives the fixing motor 244 by the load driving circuit 153 for a predetermined time while the refreshing roller 220 is in contact with the fixing roller 201. By such a refreshing operation, the toner adhering to the fixing roller 201 is removed by the refreshing roller 220. By removing the toner adhering to the fixing roller 201 in this manner, the amount of toner collected from the fixing roller 201 by the collection roller 204 can be reduced, and an increase in the frictional force between the web 212 and the collection roller 204 can be suppressed.

[0083] After the above-mentioned refreshing operation is completed, in S705, CPU 151 drives attachment / detachment motor 241 by load drive circuit 153 in a direction in which collection roller 204 contacts web 212. CPU 151 drives attachment / detachment motor 241 until the output of attachment / detachment sensor 242 switches from an OFF signal to an ON signal, thereby changing collection roller 204 from a non-contact state (non-pressurized state) to a contact state (pressurized state). When the output of attachment / detachment sensor 242 switches to an ON signal, CPU 151 stops driving attachment / detachment motor 241.

[0084] Furthermore, in S706, the CPU 151 drives the web motor 240 by the load driving circuit 153 for a predetermined time while the collection roller 204 is in contact with the web 212. As a result, the toner adhering to the collection roller 204 is removed by the web 212.

[0085] Thereafter, in S707, CPU 151 determines whether or not a torque detection value indicating the torque (load torque) of web motor 240 output from torque detection unit 154 is below a threshold value. As a result, CPU 151 checks whether the state in which the torque of web motor 240 (frictional force between web 212 and collection roller 204) is high has been released. If the torque detection value is below the threshold value, CPU 151 ends the process according to the procedure in FIG. 7 and proceeds to S511, and if the torque detection value is equal to or greater than the threshold value, proceeds to S708.

[0086] In S708, the CPU 151 determines whether the number of times the processes of S701 to S706 have been executed (the number of repetitions) has reached a predetermined upper limit. In this embodiment, the processes of S701 to S706 are repeatedly executed until the high torque state of the web motor 240 (frictional force between the web 212 and the collection roller 204) is released. However, if the high torque state of the web motor 240 is not released even after the processes of S701 to S706 are repeated and the number of repetitions of the processes reaches the upper limit, the CPU 151 determines that some abnormality has occurred in the web 212. In this case, in S709, the CPU 151 displays a replacement message on the operation unit 180 to prompt the user to replace the web 212, and ends the process according to the procedures of FIGS. 5 and 7.

[0087] When the process (S510) according to the procedure in FIG. 6 is completed, the CPU 151 performs the same processes as in the first embodiment from S511 onwards.

[0088] As described above, in image forming apparatus 100 of this embodiment, when the torque detection value output from torque detection unit 154 exceeds a threshold value while web motor 240 is being driven, CPU 151 causes load drive circuit 153 to stop driving web motor 240. After stopping the driving of web motor 240, CPU 151 switches collection roller 204 from a contact state to a non-contact state with respect to web 212 (S701). CPU 151 further switches refreshing roller 220 from a non-contact state to a contact state with fixing roller 201 (S703), and performs a refreshing operation of collection roller 204 (S704).

[0089] In this way, by performing the refreshing operation of the collection roller 204 while the web motor 240 is stopped, it is possible to release the state in which the torque of the web motor 240 (frictional force between the web 212 and the collection roller 204) is high. Therefore, even if the amount of toner adhering to the collection roller 204 increases, it is possible to prevent the web 212 (cleaning web) from breaking. Also, it is possible to prevent the web 212 (cleaning web) from breaking with a relatively simple (low-cost) configuration.

[0090] <Modification> In the above embodiment, the fixing device 200 includes the fixing roller 201 and the pressure roller 202, but the present invention is not limited to this, and for example, a fixing belt may be used instead of the fixing roller. Also, a pressure belt may be used instead of the pressure roller.

[0091] Furthermore, although the torque of the web motor 240 is detected based on the current value iq of the q-axis current used for vector control in the load drive circuit 153, the torque of the web motor 240 may be detected by a different configuration. For example, when a solenoid is used to wind up the web 212, the torque of the web motor 240 may be detected based on detection of a difference in magnetization time of the solenoid. Alternatively, the torque of the web motor 240 may be detected based on detection results of phase currents of a stepping motor.

[0092] [Other embodiments] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0093] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0094] 100: image forming apparatus, 110: image forming section, 150: control board, 151: CPU, 153: load driving circuit, 154: torque detection section, 200: fixing unit, 210: cleaning section, 240: web motor

Claims

1. An image forming apparatus, a fixing member for fixing the toner image transferred onto the recording material onto the recording material; a recovery roller for recovering the toner adhering to the fixing member; a cleaning means including a cleaning web for cleaning the collection roller, a first roller around which the cleaning web is wound in advance, a second roller for winding up the cleaning web supplied from the first roller, and a third roller disposed opposite the collection roller and for pressing the cleaning web, which is sent from the first roller toward the second roller as the second roller rotates, against the collection roller in order to clean the collection roller; A motor that drives the second roller; a drive means for driving the motor by determining a parameter value that varies in accordance with a load torque of the motor based on the drive current detected by the detection means and controlling a drive current supplied to the windings based on the parameter value; and A control means for controlling the driving means, The control means causes the drive means to stop driving the motor when the parameter value exceeds a predetermined value while the motor is being driven.

1. An image forming apparatus comprising:

2. the collection roller is switchable between a contact state in which it is in contact with the cleaning web and a non-contact state in which it is spaced from the cleaning web, The control unit executes an attachment / detachment operation for switching the collection roller from the contact state to the non-contact state after the driving of the motor is stopped, and further switching the collection roller from the non-contact state to the contact state.

2. The image forming apparatus according to claim 1,

3. The control means drives the motor by the driving means for a predetermined time while the collection roller is in the non-contact state.

3. The image forming apparatus according to claim 2,

4. The control means executes the attachment / detachment operation a first predetermined number of times after the driving of the motor is stopped.

4. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

5. The control means drives the motor by the drive means for a predetermined time after the first predetermined number of times of the attachment / detachment operations, and repeatedly executes the attachment / detachment operations while the motor is being driven until the parameter value falls below the predetermined value.

5. The image forming apparatus according to claim 4.

6. The control means determines that an abnormality has occurred in the cleaning web when the number of times the attachment and detachment operation has been repeated reaches a second predetermined number.

6. The image forming apparatus according to claim 5,

7. the fixing member is a fixing roller that is driven to rotate, a refresh roller that is switchable between a contact state in contact with the fixing roller and a non-contact state in which the refresh roller is spaced from the fixing roller, and that is used for refreshing the fixing roller in the contact state, the collection roller is switchable between a contact state in which it is in contact with the cleaning web and a non-contact state in which it is spaced from the cleaning web, The control means performs the refreshing operation by switching the collection roller from the contact state to the non-contact state and switching the refreshing roller from the non-contact state to the contact state after the driving of the motor is stopped.

2. The image forming apparatus according to claim 1,

8. The control means switches the collection roller from the non-contact state to the contact state after the refreshing operation is completed, drives the motor by the driving means for a predetermined time, and repeatedly executes the refreshing operation until the parameter value falls below the predetermined value while the motor is being driven.

8. The image forming apparatus according to claim 7,

9. The control means determines that an abnormality has occurred in the cleaning web when the number of times the refreshing operation has been repeated reaches a second predetermined number of times.

9. The image forming apparatus according to claim 8,

10. the driving means controls a driving current to be supplied to the windings based on a torque current component that generates a torque in the rotor and an excitation current component that affects the intensity of a magnetic flux passing through the windings of the motor in a rotating coordinate system based on a rotation phase of the rotor of the motor; The parameter value is a current value of the torque current component.

10. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

Images