Image-forming device and motor drive control device

Abstract

To provide an image-forming device capable of stably controlling a motor.SOLUTION: An image-forming device includes: a winding shaft 410 for winding a seal member 404; a stepping motor 300 for exclusively driving a development sleeve 403 and the winding shaft 410; and a system controller 200 for setting a target rotational speed of the stepping motor 300 to a first target rotational speed when winding the seal member 404, and setting the target rotational speed to a second target rotational speed higher than the first target rotational speed at the time of image-forming processing. The system controller 200 sets a first allowable rotational speed range showing an allowable range of a first error between the first target rotational speed and a rotational speed of the stepping motor 300 at the time of winding processing wider than a second allowable rotational speed range showing an allowable range of a second error between the second target rotational speed and a rotational speed of the stepping motor 300 at the time of image-forming processing.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a motor drive control device that controls a motor for driving a load, and an image forming apparatus that includes such a motor drive control device. [Background technology]

[0002] In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a photoreceptor, which is an image carrier, through a charging process and an exposure process, and the electrostatic latent image is developed with a developer such as toner through a developing process to form a developer image on the photoreceptor. The developer image on the photoreceptor is then transferred to a recording medium through a transfer process and a fixing process.

[0003] Some of such image forming devices use a cartridge system for components in order to accommodate replacement of components that have reached the end of their life and replenishment of consumables. For example, there is a cartridge-type developer (developer cartridge) that integrates a developer container that contains developer and a developer roller that supplies developer to a photoconductor. There is also a process cartridge that integrates a developer, a photoconductor, a charger that charges the photoconductor, and a cleaner that cleans the photoconductor.

[0004] In order to prevent leakage of developer during transportation or replacement of the developer cartridge, the opening of the developer container is sealed with a sealing member or the like. Patent Document 1 discloses an image forming apparatus having a configuration in which the sealing member is automatically wound up when the developer cartridge is installed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-278240 A Summary of the Invention [Problem to be solved by the invention]

[0006] The seal member is attached to the opening of the developer container with such strong adhesive force that it does not peel off during transportation of the developer cartridge. In order to automatically wind up and peel off the seal member using a motor, it is necessary to generate high torque by rotating the motor at a low speed using a motor drive control device. If the load on the motor increases due to the state of the developer inside the attached developer cartridge, the motor drive control device will rotate the motor at a low speed, making it difficult to stably control the rotation of the motor. As a result, there is a possibility that the seal member will not peel off properly. As a countermeasure, a motor that generates high torque in a high-speed rotation range where stable rotation control is possible can be used, but in this case, the product cost will be high.

[0007] SUMMARY OF THE PRESENT DISCLOSURE In view of the above problems, a main object of the present invention is to provide an image forming apparatus capable of stably controlling a motor. [Means for solving the problem]

[0008] The image forming apparatus of the present invention is an image forming apparatus in which a developing unit having a sealing member to be removed at the start of use and a developing sleeve for supplying developer during image formation processing is removably provided, and is equipped with a take-up shaft that takes up the sealing member, a drive source that exclusively drives the developing sleeve and the take-up shaft, a control means that sets a target rotational speed of the drive source to a first target rotational speed during the take-up processing of the sealing member and sets the target rotational speed to a second target rotational speed faster than the first target rotational speed during the image formation processing, and a drive control means that rotates the drive source at the first target rotational speed during the take-up processing and rotates the drive source at the second target rotational speed during the image formation processing, and is characterized in that the control means sets a first permissible rotational speed range indicating the permissible range of a first error between the first target rotational speed and the rotational speed of the drive source during the take-up processing wider than a second permissible rotational speed range indicating the permissible range of a second error between the second target rotational speed and the rotational speed of the drive source during the image formation processing.

[0009] The motor drive control device of the present invention comprises a drive source which exclusively drives a first component and a second component having a torque smaller than that of the first component when driven, a control means which sets a target rotational speed of the drive source to a first target rotational speed during a first process for operating the first component, and sets the target rotational speed to a second target rotational speed faster than the first target rotational speed during a second process for operating the second component, and a drive control means which rotates the drive source at the first target rotational speed during the first process and rotates the drive source at the second target rotational speed during the second process, wherein the control means sets a first permissible rotational speed range indicating a permissible range of a first error between the first target rotational speed and the rotational speed of the drive source during the first process to be wider than a second permissible rotational speed range indicating a permissible range of a second error between the second target rotational speed and the rotational speed of the drive source during the second process. Effect of the Invention

[0010] According to the present invention, the motor can be stably controlled. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 4 is an explanatory diagram of the operation of a stepping motor. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] 4 is a flowchart showing a rotation control process of a stepping motor. [Figure 8] 5A and 5B are diagrams illustrating the rotation speed of a stepping motor during a winding process and an image forming process. [Figure 9] FIG. 4 is a diagram illustrating a rotation speed error and a permissible rotation speed range. [Figure 10] FIG. 4 is a diagram illustrating a rotation speed error and a permissible rotation speed range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] 1 is a configuration diagram of an image forming apparatus according to this embodiment. Image forming apparatus 1 is an electrophotographic color image forming apparatus in which four image forming units that form developer images of the respective colors of yellow, magenta, cyan, and black are arranged in parallel. Each image forming unit has the same configuration, except that the color of the developer image that it forms differs.

[0014] Each image forming unit includes photosensitive drums 101a to 101d, charging rollers 102a to 102d, exposure devices 103a to 103d, developing devices 400a to 400d, primary transfer rollers 105a to 105d, and drum cleaners 107a to 107d. In the following description, when it is not necessary to distinguish between colors, the suffixes a, b, c, and d are omitted.

[0015] The photosensitive drum 101 is a drum-shaped photosensitive body having a photosensitive layer on its surface. The photosensitive drum 101 is rotatable in the direction of the arrow around the drum axis. The charging roller 102 is a charger, and uniformly charges the surface of the rotating photosensitive drum 101. The exposure device 103 exposes the charged surface of the photosensitive drum 101 to laser light whose emission is controlled based on image signals for each color, thereby forming an electrostatic latent image corresponding to each color on the surface of the photosensitive drum 101.

[0016] The developing units 400 contain developers of the corresponding colors inside, and form developer images corresponding to the respective colors on the surface of the photosensitive drum 101 by attaching the developers to the electrostatic latent images. In this embodiment, the developer contains toner, and a toner image is formed as the developer image. The developing units 400 are of a cartridge type that is detachable from the image forming apparatus 1 so that they can be easily replaced.

[0017] With the above configuration, a yellow toner image is formed on the surface of the photosensitive drum 101a. A magenta toner image is formed on the surface of the photosensitive drum 101b. A cyan toner image is formed on the surface of the photosensitive drum 101c. A black toner image is formed on the surface of the photosensitive drum 101d.

[0018] The primary transfer roller 105 is disposed opposite the corresponding photosensitive drum 101 with the intermediate transfer belt 106 sandwiched between the primary transfer roller 105 and the photosensitive drum 101. The intermediate transfer belt 106 is an endless belt-like image carrier and can rotate in a clockwise direction in the figure. The primary transfer roller 105 transfers a toner image from the photosensitive drum 101 to the intermediate transfer belt 106 by applying a predetermined bias voltage (primary transfer bias) at a timing according to the rotation of the intermediate transfer belt 106. At this time, the toner images of each color are transferred from each of the photosensitive drums 101a to 101d to the same position on the intermediate transfer belt 106. As a result, the toner images of each color are carried on the intermediate transfer belt 106 in a superimposed manner. The toner remaining on the photosensitive drum 101 after the transfer is collected by a drum cleaner 107.

[0019] The intermediate transfer belt 106 is wound around a plurality of rollers including the inner secondary transfer roller 109b. A secondary transfer roller 109a is disposed at a position facing the inner secondary transfer roller 109b across the intermediate transfer belt 106. The secondary transfer roller 109a and the inner secondary transfer roller 109b constitute a secondary transfer unit 118. The intermediate transfer belt 106 conveys the toner images of each color carried thereon to the secondary transfer unit 118 by rotating. A belt cleaner 108 is provided downstream of the secondary transfer unit 118 in the conveying direction of the intermediate transfer belt 106.

[0020] A recording material S, which is a sheet-shaped recording medium on which an image is printed, is fed from either a paper feed cassette 111 or a manual paper feed unit 113. The recording material S is fed at a timing corresponding to the start of an image forming operation by the image forming unit. A plurality of conveying rollers 114, a pre-registration roller 115, and a registration roller 116 are provided on a conveying path along which the recording material S is conveyed. The fed recording material S is conveyed to the pre-registration roller 115 by the plurality of conveying rollers 114. The pre-registration roller 115 conveys the conveyed recording material S to the registration roller 116. The registration roller 116 corrects skew of the recording material S and temporarily stops conveyance. The registration roller 116 conveys the recording material S to the secondary transfer unit 118 in accordance with the timing at which the toner image carried on the intermediate transfer belt 106 is conveyed to the secondary transfer unit 118.

[0021] In the secondary transfer section 118, the intermediate transfer belt 106 and the recording material S are nipped and conveyed between the secondary transfer roller 109a and the inner secondary transfer roller 109b. At this time, a predetermined bias voltage (secondary transfer bias) is applied to the secondary transfer roller 109a, so that the four color toner images are transferred collectively from the intermediate transfer belt 106 to the recording material S. Since the conveyance timing is adjusted by the registration roller 116, the toner image is transferred to a predetermined position on the recording material S. The toner remaining on the intermediate transfer belt 106 after the transfer is collected by the belt cleaner 108.

[0022] The secondary transfer unit 118 transports the recording material S onto which the toner image has been transferred to a fixing unit 110 arranged downstream of the secondary transfer unit 118 in the transport direction of the recording material S. The fixing unit 110 heats and pressurizes the recording material S onto which the toner image has been transferred, melting and mixing the toners of each color, and pressing them onto the recording material S. This fixes a full-color image onto the recording material S. The recording material S onto which the image has been fixed is discharged as a printed matter outside the image forming apparatus 1 by a discharge unit 119a or 119b arranged downstream of the fixing unit 110 in the transport direction of the recording material S.

[0023] In this embodiment, the developing units 400a to 400d are described as being of a cartridge type, but other components may also be configured to be replaceable in a cartridge type. For example, each image forming unit other than the exposure unit 103 and the primary transfer roller 105, and the intermediate transfer belt 106 may be configured in a cartridge type.

[0024] 2 is a configuration diagram of a control unit that comprehensively controls the operation of the image forming apparatus 1 configured as above. The control unit 204 performs processes such as drive control of each load provided in the image forming apparatus 1, collection of detection results by the sensors, and analysis of the detection results. The control unit 204 of this embodiment is connected to an image processing unit 202, an operation unit 203, a thermistor 211, a high-voltage unit 221, sensors 250, and a fixing unit 110.

[0025] In order to form an image with optimal image quality, the image processing unit 202 performs various types of image processing on the image signal under the control of the control unit 204, and transmits the image signal after the image processing to the control unit 204. The operation unit 203 is a user interface equipped with an input interface and an output interface. The input interface is, for example, various key buttons, a touch panel, etc. The output interface is, for example, a display, a speaker, etc.

[0026] The thermistor 211 is used to detect the temperature of the fixing unit 110. The high voltage unit 221 outputs a high voltage to be applied to, for example, the primary transfer rollers 105a-105b, the secondary transfer roller 109b, the charging rollers 102a-102d, and a developing sleeve (to be described later) of the developing unit 400 under the control of the control unit 204. The sensors 250 are arranged in various parts within the image forming apparatus 1 and are used to detect the operating state of the image forming apparatus 1, etc.

[0027] The control unit 204 includes a system controller 200, an AD converter 210, a high voltage control unit 220, a motor control unit 230, a DC load control unit 270, and an AC driver 260. The system controller 200 includes a CPU (Central Processing Unit) 200a, a ROM (Read Only Memory) 200b, and a RAM (Random Access Memory) 200c. The CPU 200a controls the operation of the image forming apparatus 1 by executing a computer program stored in the ROM 200b. The RAM 200c provides a working area for the CPU 200a to execute processing, and stores temporary data. The RAM 200c also stores, for example, various data, image formation command information input from the operation unit 203, and the like. In addition to the computer program, the ROM 200b stores various setting values ​​and thresholds for judgment required for controlling the image forming apparatus 1 in advance.

[0028] The system controller 200 instructs the image processing unit 202 to perform various settings (e.g., copy magnification, image density setting, number of prints) and processing for image processing. The system controller 200 also receives signals from each unit, such as an original image density signal, and performs optimal image formation by controlling the high voltage control unit 220 and the image processing unit 202 based on the received signals. The system controller 200 accepts instructions and settings (e.g., copy magnification, density setting value, etc.) input by the user from the operation unit 203. The system controller 200 transmits data to the operation unit 203 to notify the user of the state of the image forming apparatus 1, such as the number of prints and information on whether image formation is in progress, the occurrence of a jam and its location, etc.

[0029] The system controller 200 acquires a detection signal of the temperature of the fixing unit 110 output from the thermistor 211 via the AD converter 210. The detection signal output from the thermistor 211 is an analog signal. The AD converter 210 converts the analog detection signal acquired from the thermistor 211 into a digital signal that can be processed by the CPU 200a, and transmits the converted detection signal to the system controller 200. The system controller 200 detects the temperature of the fixing unit 110 based on the digital detection signal.

[0030] The system controller 200 controls the temperature of the fixing unit 110 via the AC driver 260. The system controller 200 transmits an instruction to the AC driver 260 to maintain the fixing unit 110 at a predetermined temperature based on the temperature of the fixing unit 110 detected using the thermistor 211. Upon receiving the instruction, the AC driver 260 controls the temperature of the fixing unit 110 by controlling the power supplied to the fixing unit 110.

[0031] The system controller 200 controls the operation of the high voltage unit 221 via the high voltage control section 220. The system controller 200 transmits a voltage application instruction to the high voltage control section 220 at a timing when application of a high voltage is required. When the high voltage control section 220 receives the voltage application instruction, it controls the high voltage unit 221 to output a high voltage (primary bias voltage, secondary bias voltage, charging voltage, etc.). The system controller 200 receives detection results from each of the sensors 250. The system controller 200 detects the state of the image forming apparatus 1 based on the detection results of each of the sensors 250, and controls the operation of the image forming apparatus 1, notifies of errors from the operation section 203, etc.

[0032] The system controller 200 controls the operation of a drive source such as a motor arranged in the image forming apparatus 1 via the motor control unit 230. To this end, the system controller 200 transmits a control signal for controlling the drive source to the motor control unit 230. The motor control unit 230 controls the drive of the drive source based on the control signal. Under the control of the motor control unit 230, a drive force is supplied from the drive source to a load, and the operation of the load is controlled. Details of the motor control unit 230 will be described later.

[0033] The system controller 200 controls the operation of the DC load arranged in the image forming apparatus 1 via the DC load control unit 270. To this end, the system controller 200 transmits a control signal for controlling the DC load to the DC load control unit 270. The DC load control unit 270 controls the operation of the DC load based on the control signal.

[0034] The operation control of the image forming apparatus 1 is performed by a system controller 200. In a series of operational controls, the motors serving as drive sources for the loads of the various sections are driven and controlled by a motor drive control section including a motor control section 230.

[0035] 3 is an explanatory diagram of the motor drive control unit. The motor drive control unit 2 includes a motor control unit 230, a PWM (Pulse Width Modulation) inverter 311, current detection units 312 and 313, and an A / D converter 315. The motor drive control unit 2 and the CPU 200a constitute a motor drive control device. The motor drive control unit 2 is composed of one circuit board. The motor drive control unit 2 is replaceable, and when an abnormality occurs, it is possible to deal with the abnormality by replacing the circuit board. Here, a configuration for controlling the drive of one stepping motor 300 will be described. When controlling the drive of a plurality of stepping motors, the motor drive control units 2 are provided in a number corresponding to the number of stepping motors.

[0036] The motor control unit 230 acquires a position command including a position command value θ_ref from the CPU 200a of the system controller 200. The motor control unit 230 performs position control involving vector control of the stepping motor 300 based on the position command. The motor control unit 230 is configured by, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0037] A description will now be given of vector control by the motor control unit 230. Note that, although a stepping motor is used in this embodiment, a brushless DC motor may also be used.

[0038] 4 is an explanatory diagram of the operation of the stepping motor 300, showing the relationship between a stationary coordinate system that represents the normal current vector flowing through phases A and B, and a rotating coordinate system represented by the d-axis and q-axis. The stationary coordinate system is transformed into the rotating coordinate system. The d-axis is defined along the direction of the magnetic flux created by the magnetic poles of the permanent magnet used in the rotor, and the q-axis is defined in the direction 90 degrees clockwise from the d-axis (direction perpendicular to the d-axis).

[0039] The inverter control is roughly divided into two control loops, namely, current control units 234 and 235 and a position control unit 232. The position control unit 232 outputs current command values ​​iq_ref and id_ref so that the deviation between the position θ of the output shaft of the stepping motor 300 detected by a position detection unit 314 such as an encoder and the position command value θ_ref from the CPU 200a is small. The position control unit 232 is composed of, for example, a proportional, integral, and differential compensator. The current command values ​​iq_ref and id_ref are current command values ​​converted from the αβ axis (stationary coordinate system) to the dq axis (rotating coordinate system). The α axis is an axis corresponding to the A-phase winding, and the β axis is an axis corresponding to the B-phase winding. The angle between the α axis and the d axis is defined as θ, and the rotation phase of the rotor is represented by the angle θ. The current flowing through the winding of the stepping motor 300 in the stationary coordinate system is represented by the following formulas (1-1) and (1-2). iα=I*cosθ …(1-1) iβ=I*sinθ …(1-2)

[0040] The current flowing through the windings of the stepping motor 300 in the rotating coordinate system is expressed by the following equations (2-1) and (2-2). id=cosθ*iα+sinθ*iβ …(2-1) iq=-sinθ*iα+cosθ*iβ …(2-2)

[0041] Through this conversion, the AC currents iα and iβ flowing through the A-phase and B-phase windings and the current command values ​​iq_ref and id_ref are expressed as DC currents. Here, the d-axis current is a component that can control the amount of magnetic flux and is not involved in torque. The q-axis current is a component that governs the torque generated by the stepping motor 300 and has a value proportional to the load torque. Therefore, by monitoring the value of the q-axis current, the magnitude of the load torque of the stepping motor 300 can be monitored.

[0042] The position θ of the output shaft of the stepping motor 300 is converted to a motor rotation speed ω by a differentiator 242. The position command value θ_ref is converted to a target rotation speed ω_ref by a target rotation speed generation unit 240. A difference value ω_diff between the motor rotation speed ω and the target rotation speed ω_ref indicates a speed difference (rotation speed error) indicating how far the rotation speed of the stepping motor 300 deviates from the target rotation speed ω_ref. The rotation speed determination unit 241 incorporates a rotation speed error calculation unit that calculates a rotation speed error, and an allowable rotation speed range holding unit that holds an allowable rotation speed range ω_tolval that can be set arbitrarily, both of which are not shown. The allowable rotation speed range ω_tolval indicates a permissible range of the rotation speed error. The rotation speed determination unit 241 outputs a rotation speed determination signal V_Lock_sig based on the allowable rotation speed range ω_tolval and the rotation speed error value ω_diffval. The CPU 200a monitors the rotation speed determination signal V_Lock_sig to monitor whether or not the rotation speed of the stepping motor 300 is stable. If the rotation speed error value ω_diffval is included in the allowable rotation speed range ω_tolval, it is determined that the rotation speed of the stepping motor 300 is stable.

[0043] The current values ​​of the currents flowing through each phase of the stepping motor 300 are detected by current detection units 312, 313 and converted by an A / D converter 315 into digital signals (iα, iβ) that can be input to the motor control unit 230. The coordinate conversion unit 231 of the motor control unit 230 performs dq conversion of the current signals iα, iβ using the above equations (2-1) and (2-2) to generate a q-axis current iq and a d-axis current id.

[0044] The deviations between the q-axis current iq and the d-axis current id and the current command values ​​iq_ref and id_ref output from the position control unit 232 are input to the current control units 234 and 235. In normal vector control, the current control unit 235 controls the d-axis current so that the id component (excitation current component) that is not involved in the torque becomes zero. The current control units 234 and 235 are composed of proportional and integral compensators like the position control unit 232, and amplify the current deviation amount. The coordinate conversion unit 236 inversely converts the q-axis current iq and the d-axis current id into current amounts iα1 and iβ1 in the stationary coordinate system. The inverse conversion is performed by the following equations (3-1) and (3-2). iα1=cosθ*id-sinθ*iq…(3-1) iβ1=sinθ*id+cosθ*iq …(3-2)

[0045] The coordinate conversion unit 236 outputs drive voltages Vα and Vβ obtained by voltage conversion of the current values ​​iα1 and iβ1. The drive voltages Vα and Vβ are input to the PWM inverter 311. The PWM inverter 311 includes a full bridge circuit that drives each phase winding of the stepping motor 300. The full bridge circuit controls the stepping motor 300 so that a desired amount of drive current flows through the windings by a PWM signal corresponding to the drive voltages Vα and Vβ. By constructing such a feedback system, the vector control can constantly apply to the stepping motor 300 the minimum drive current required according to the load. This realizes motor drive control with less power consumption and less noise than the open control drive that requires an excess current (torque margin) to avoid loss of synchronism.

[0046] (Developer) Fig. 5 is a diagram illustrating the configuration of the developing unit 400. Fig. 6 is a top view of the developing unit 400 (as viewed from above in Fig. 1).

[0047] As described above, the developing unit 400 is a cartridge-type component that is detachable from the image forming apparatus 1 and easily replaceable. The developing unit 400 has a first transport screw 401, a second transport screw 402, a developing sleeve 403, a first storage chamber 406, a second storage chamber 407, a partition wall 404, and a communication port 408. In addition, the developing unit 400 has, in an initial state, a seal member 405 that is removed when the developing unit 400 is attached to the image forming apparatus 1. The developing sleeve 403 is disposed in the second storage chamber 407 so as to face the photosensitive drum 101.

[0048] The first storage chamber 406 and the second storage chamber 407 store developer D, which is a two-component developer of non-magnetic toner and magnetic carrier. In FIG. 5 and FIG. 6, developer D is shown in a shaded area. The first storage chamber 406 and the second storage chamber 407 are separated by a partition wall 404. The partition wall 404 is provided with communication ports 408 (408a, 408b) that communicate between the first storage chamber 406 and the second storage chamber 407. In this embodiment, the communication ports 408 are provided at two locations on both ends of the partition wall 404 (communication ports 408a, 408b). In the initial state of the developing device 400, the communication ports 408 are sealed by a seal member 405. Therefore, in the initial state, developer D is stored only in the first storage chamber 406, and developer D is not stored in the second storage chamber 407.

[0049] The seal member 405 is connected to the take-up shaft 410. When the use of the developing device 400 starts, the take-up shaft 410 is driven by the stepping motor 300, so that the seal member 405 is peeled off and taken up onto the take-up shaft 410. As a result, the communication port 408 is opened. When the communication port 408 is opened, the first storage chamber 406 and the second storage chamber 407 communicate with each other, and the developer D inside the first storage chamber 406 flows into the second storage chamber 407 through the communication port 408.

[0050] The load applied to the stepping motor 300 when peeling off the sealing member 405 is larger than the load applied during image formation. Therefore, the rotation speed of the stepping motor 300 when peeling off the sealing member 405 is set lower than the rotation speed during image formation in order to increase the output torque. In other words, the rotation speed of the stepping motor 300 is set slower during the winding process of the sealing member 405 than during the image formation process.

[0051] The first transport screw 401 is rotatably attached inside the first storage chamber 406. The first transport screw 401 rotates to transport the developer D inside the first storage chamber 406 in the direction of one communication port 408a while stirring the developer D. The second transport screw 402 is rotatably attached inside the second storage chamber 407. The second transport screw 402 rotates to transport the developer D inside the second storage chamber 407 in the direction of the other communication port 408b while stirring the developer D.

[0052] During image formation processing, developer D is transported while being stirred through a circulation path indicated by the arrows in Fig. 6, which is formed by first storage chamber 406, communication port 408a, second storage chamber 407, and communication port 408b, by first transport screw 401 and second transport screw 402. As developer D is simultaneously stirred during the transport process, the toner and carrier are charged to opposite polarities due to friction between the toner particles and carrier particles. In this embodiment, the toner is charged to negative polarity, and the carrier is charged to positive polarity.

[0053] Inside the developing sleeve 403, a magnet is provided that is supported non-rotatably with multiple magnetic poles arranged on its surface. The developer D is supported on the surface of the developing sleeve 403 by the carrier (magnetic material) being bound by a magnetic flux formed between the magnetic poles of the magnet. A magnetic brush is formed on the surface of the developing sleeve 403 by electrostatically binding the negatively charged toner to the surface of the positively charged carrier. An amplitude voltage in which an AC voltage is superimposed on a negative DC voltage is applied from the high voltage unit 221 to the developing sleeve 403, so that the toner supported on the magnetic brush moves to the electrostatic latent image on the photosensitive drum 101 and adheres to the electrostatic latent image. This develops the electrostatic latent image.

[0054] The first conveying screw 401, the second conveying screw 402, and the developing sleeve 403 are connected to the stepping motor 300 via gears (not shown). The first conveying screw 401, the second conveying screw 402, and the developing sleeve 403 are driven to rotate by the stepping motor 300. Similarly, the take-up shaft 410 is connected to the stepping motor 300 via gears (not shown), and is driven to rotate by the stepping motor 300. When the first conveying screw 401, the second conveying screw 402, and the developing sleeve 403 are driven to rotate, the take-up shaft 410 is not driven to rotate. When the take-up shaft 410 is driven to rotate, the first conveying screw 401, the second conveying screw 402, and the developing sleeve 403 are not driven to rotate. That is, the first conveying screw 401, the second conveying screw 402, the developing sleeve 403, and the take-up shaft 410 are driven to rotate exclusively by the stepping motor 300. During driving, the torque of the take-up shaft 410 is greater than the torque of each of the first conveying screw 401, the second conveying screw 402, and the developing sleeve 403. As a method for exclusive driving, the driving may be switched between forward and reverse rotation of the motor, or the driving may be switched using a clutch.

[0055] The stepping motor 300 is controlled by a motor drive control unit 2. The system controller 200 transmits a position command (control signal) including a position command value θ_ref as a drive command for the stepping motor 300 to the motor control unit 230.

[0056] The motor control unit 230 generates a PWM signal that reduces the deviation between the position indicated by the position command value θ_ref included in the position command (control signal) and the actual position θ of the stepping motor 300, and transmits the signal to the PWM inverter 311. The PWM inverter 311 has a full bridge circuit (not shown), and operates the full bridge circuit (not shown) based on the PWM signal acquired from the motor control unit 230 to pass a predetermined current through the windings of the stepping motor 300. With the above-mentioned configuration and operation, the stepping motor 300 is driven, and the first conveying screw 401, the second conveying screw 402, the developing sleeve 403, and the take-up shaft 410 are exclusively rotated and controlled.

[0057] When performing vector control of the stepping motor 300, the motor control unit 230 transmits a rotation speed determination signal V_Lock_sig from an internal rotation speed determination unit 241 to the system controller 200. The system controller 200 can monitor the stability of the rotation speed of the stepping motor 300 based on the rotation speed determination signal V_Lock_sig.

[0058] 7 is a flowchart showing the rotation control process of the stepping motor 300. In this process, an error judgment is made on the rotation speed of the stepping motor 300. Here, the rotation control process of the stepping motor 300 when the winding process of the seal member 405 and the image forming process are performed will be described. The winding process of the seal member 405 is performed automatically by the image forming apparatus 1 or by the user operating the operation unit 203 after a new cartridge-type developer 400 from which the seal member 405 has not been peeled off is mounted in the image forming apparatus 1.

[0059] The system controller 200 detects that a new developer 400 has been installed in the image forming apparatus 1 or receives an instruction to start a print job, and then transmits an instruction to rotate the stepping motor 300 to the motor control unit 230 (S701). The system controller 200 determines whether the developer 400 is new (S702). The determination of whether the developer 400 is new can be performed, for example, as follows. The developer 400 has, for example, a memory (not shown). This memory stores information (such as an individual identification number) indicating the characteristics of the developer 400. When the developer 400 is installed, the system controller 200 can read the information stored in the memory and determine whether the developer 400 is a newly installed new developer 400.

[0060] If the developing device 400 is new (S702: Y), the system controller 200 sets (S703) the driving conditions of the stepping motor 300 for performing the winding process of the seal member 405. Here, as the driving conditions for performing the winding process of the seal member 405 of the developing device 400, the target rotation speed of the stepping motor 300 is set to 30 [mm / sec], and the allowable rotation speed range is set to the target rotation speed ±50%.

[0061] If the developing device 400 is not new (S702: N), the system controller 200 sets the driving conditions of the stepping motor 300 for performing the image forming process (S704). Here, as the driving conditions for performing the image forming process, the target rotation speed of the stepping motor 300 is set to 150 [mm / sec], and the allowable rotation speed range is set to the target rotation speed ±10%.

[0062] FIG. 8 is an explanatory diagram of the rotation speed of the stepping motor 300 during the winding process of the seal member 405 and during the image forming process.

[0063] The rotation speed of the stepping motor 300 is 30 [mm / sec] when winding the sealing member 405, which is slower than the rotation speed during image formation. This is because a large torque is required when winding the sealing member 405, and it is necessary to rotate the stepping motor 300 at a slow rotation speed. In addition, when winding the sealing member 405, the load fluctuation is large and the rotation speed is low, so that the rotation speed of the stepping motor 300 is difficult to stabilize.

[0064] When performing the image forming process, a large torque is not required, so the stepping motor 300 rotates at a higher rotation speed than the rotation speed during the winding process. Also, when performing the image forming process, the load fluctuation is small and the rotation speed is high, so the rotation speed of the stepping motor 300 is stable.

[0065] 9 and 10 are explanatory diagrams of the rotation speed error and the allowable rotation speed range set in the processes of S703 and S704. The solid line in FIG. 9 shows the rotation speed error of the stepping motor 300 with respect to the elapsed time when the winding process of the sealing member 405 is performed. The dashed lines in FIG. 9 show the upper and lower limits of the allowable rotation speed range when the winding process of the sealing member 405 is performed. The solid line in FIG. 10 shows the rotation speed error of the stepping motor 300 with respect to the elapsed time when the image forming process is performed. The dashed lines in FIG. 10 show the upper and lower limits of the allowable rotation speed range when the image forming process is performed.

[0066] When the winding process of the sealing member 405 is performed (solid line in FIG. 9), as described above, the rotation of the stepping motor 300 is unstable and the rotation speed error exceeds 20%. In contrast, when the image forming process is performed (solid line in FIG. 10), the rotation of the stepping motor 300 is stable and the rotation speed error is 10% or less.

[0067] The allowable rotation speed ranges of each will be described below. When winding up the sealing member 405, it is sufficient if the winding up process of the sealing member 405 can be performed even if the rotation of the stepping motor 300 is not stable. For that reason, as shown in Fig. 9, there is no problem in setting the allowable rotation speed range to a wide range of the target rotation speed ±50%.

[0068] On the other hand, when performing image formation processing, if the rotation of the stepping motor 300 is not stable, the rotation of the developing sleeve 403 will also be unstable, which will affect the image to be formed. Therefore, as shown in Fig. 10, the allowable rotation speed range needs to be set to a range narrower than that for the winding processing, such as the target rotation speed ±10%.

[0069] After setting the driving conditions of the stepping motor 300, the system controller 200 starts rotating the stepping motor 300 (S705). The system controller 200 rotates the stepping motor 300 under the driving conditions (target rotation speed, allowable rotation speed range) set in the process of S703 or the process of S704.

[0070] After the stepping motor 300 starts rotating, the system controller 200 monitors the rotation speed determination signal V_Lock_sig at a predetermined time interval (here, 50 millisecond intervals). The system controller 200 determines the stability of the rotation of the stepping motor 300 based on whether the rotation speed determination signal V_Lock_sig is acquired in a predetermined state a predetermined number of times in succession (S706). In this embodiment, the rotation speed determination signal V_Lock_sig becomes a low-level signal when the rotation speed error shown by the solid line in Fig. 9 and Fig. 10 is not included in the allowable rotation speed range shown by the dashed line. In this embodiment, if the rotation speed determination signal V_Lock_sig is at a low level six times in succession, it is considered that the rotation of the stepping motor 300 is not stable, and a signal related to an abnormality of the stepping motor 300 is output.

[0071] If the low-level rotation speed determination signal V_Lock_sig has not been detected six consecutive times (S706: Y), the system controller 200 checks whether or not there is an instruction to stop the stepping motor 300 (S708). If there is no instruction to stop (S708: N), the system controller 200 returns to the process of S706 and again determines the stability of the rotation of the stepping motor 300. If there is an instruction to stop (S708: Y), the system controller 200 stops the rotation of the stepping motor 300 (S709) and ends the process.

[0072] If the low-level rotation speed determination signal V_Lock_sig has been detected six times in succession (S706: N), the system controller 200 outputs a signal related to an abnormality in the stepping motor 300. The system controller 200 notifies the operation error of the stepping motor 300 based on this signal (S707). The error is notified, for example, by a display on the operation unit 203 or by outputting a warning sound from a speaker. The error may also be notified to an external service center. Thereafter, the system controller 200 stops the rotation of the stepping motor 300 (S709) and ends the process.

[0073] As described above, the image forming apparatus 1 of the present embodiment sets the allowable rotation speed range of the stepping motor 300 when performing the winding process of the seal member 405 to be wider than the allowable rotation speed range of the stepping motor 300 when forming an image. This allows the winding process of the seal member 405 to be continued even if the load on the stepping motor 300 increases and the rotation speed becomes unstable. In addition, the allowable speed error range is widened only when the stepping motor 300 rotates at a low speed when winding the seal member 405, and is not widened during image formation at a high speed. Since the allowable speed error range during image formation is narrower than during the winding process, an unstable state of the rotation speed of the stepping motor 300 during image formation is detected more quickly than during the winding process. Therefore, even if the rotation speed of the stepping motor 300 becomes unstable during image formation, it is possible to prevent the effect of this on the image to be formed.

[0074] In this configuration, since there is no need to use a motor that generates high output and high torque, it is possible to suppress an increase in costs. In the above explanation, specific values ​​are given for the target rotation speed and the allowable rotation speed range, but these values ​​are merely examples and other values ​​may be used.

[0075] In addition, the above description has been given as an example of the winding process of the seal member 405 of the developer 400 of a removable cartridge type, but the same process is possible for components other than the developer 400. That is, if the device has two components that are driven exclusively by one drive source, and the torque of the drive source when driving each component is different and the rotation speed of the drive source is different, the motor drive control unit 2 configured as described above is effective. The target rotation speed of the component with a relatively small torque when driven is set to be higher than the target rotation speed of the component with a relatively large torque when driven. In addition, the allowable rotation speed range of the component with a relatively large torque when driven is set to be wider than the allowable rotation speed range of the component with a relatively small torque when driven.

Claims

1. An image forming apparatus in which a developing unit having a seal member to be removed at the start of use and a developing sleeve for supplying a developer during an image forming process is detachably provided, a winding shaft for winding the sealing member; a drive source that exclusively drives the developing sleeve and the take-up shaft; a control means for setting a target rotation speed of the drive source to a first target rotation speed during a winding process of the seal member, and for setting the target rotation speed to a second target rotation speed higher than the first target rotation speed during an image forming process; a drive control means for rotating the drive source at the first target rotation speed during the winding process and rotating the drive source at the second target rotation speed during the image forming process, the control means sets a first allowable rotation speed range indicating an allowable range of a first error between the first target rotation speed and the rotation speed of the drive source during the winding process to be wider than a second allowable rotation speed range indicating an allowable range of a second error between the second target rotation speed and the rotation speed of the drive source during the image forming process. Image forming device.

2. the control means outputs a signal related to an abnormality of the drive source in both cases where the first error is not included in the first allowable rotation speed range during the winding process and where the second error is not included in the second allowable rotation speed range during the image forming process.

2. The image forming apparatus according to claim 1.

3. The control means notifies an operation error of the driving source based on a signal related to an abnormality of the driving source.

3. The image forming apparatus according to claim 2.

4. the drive control means outputs a rotation speed determination signal based on the first error and the first allowable rotation speed range; The control means outputs a signal related to an abnormality of the drive source during the winding process based on the rotation speed determination signal.

3. The image forming apparatus according to claim 2.

5. the drive control means outputs a rotation speed determination signal of a first state when the first error is not included in the first allowable rotation speed range, The control means outputs a signal related to an abnormality of the drive source during the winding process when the rotation speed determination signal is in the first state for a predetermined number of consecutive times.

5. The image forming apparatus according to claim 4.

6. the drive control means outputs a rotation speed determination signal based on the second error and the second allowable rotation speed range; The control means outputs a signal related to an abnormality of the driving source during the image forming process based on the rotation speed determination signal.

3. The image forming apparatus according to claim 2.

7. the drive control means outputs a rotation speed determination signal of a first state when the second error is not included in the second allowable rotation speed range, The control means outputs a signal related to an abnormality of the drive source during the image forming process when the rotation speed determination signal is in the first state for a predetermined number of consecutive times.

7. The image forming apparatus according to claim 6.

8. The control means stops the operation of the drive source based on a signal related to an abnormality of the drive source.

3. The image forming apparatus according to claim 2.

9. the control means determines whether the developing unit is new or not, and if it is new, sets the target rotation speed of the driving source to the first target rotation speed and sets the first allowable rotation speed range, and if it is not new, sets the target rotation speed of the driving source to the second target rotation speed and sets the second allowable rotation speed range.

2. The image forming apparatus according to claim 1.

10. The developing device includes: a first storage chamber that stores a developer; A second storage chamber; and A partition wall that separates the first storage chamber and the second storage chamber; a communication port provided in the partition wall for communicating between the first storage chamber and the second storage chamber, The sealing member seals the communication port in an initial state.

2. The image forming apparatus according to claim 1.

11. a first conveying screw is provided in the first storage chamber to convey the developer toward the communication port, a second conveying screw is provided in the second storage chamber to convey the developer that flows in through the communication port that is opened by winding up the seal member; the first conveying screw and the second conveying screw are driven by the driving source during the image forming process, The image forming apparatus according to claim 10.

12. a drive source that exclusively drives a first component and a second component having a smaller torque when driven than the first component; a control means for setting a target rotation speed of the drive source to a first target rotation speed during a first process for operating the first component, and for setting the target rotation speed to a second target rotation speed higher than the first target rotation speed during a second process for operating the second component; a drive control means for rotating the drive source at the first target rotation speed during the first processing and for rotating the drive source at the second target rotation speed during the second processing, the control means sets a first allowable rotation speed range indicating an allowable range of a first error between the first target rotation speed and the rotation speed of the drive source during the first processing to be wider than a second allowable rotation speed range indicating an allowable range of a second error between the second target rotation speed and the rotation speed of the drive source during the second processing. Motor drive control device.

Images