JP2018087076A - Sheet conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that noise is generated by controlling a motor in a condition where responsibility to a change in a deviation between a command phase and a real rotational phase is relatively high, when the motor for driving a preregistration roller is controlled.SOLUTION: Only in a period where it is necessary to accurately control the rotation amount of a roller, phase control is performed, meanwhile, in other periods, speed control is performed. Where, responsibility to a change in a deviation between an estimation value and a command value is higher when the phase control is performed than when the speed control is performed. As a result, in a period where a motor for driving a preregistration roller is controlled, it is possible to shorten a period where noise caused by controlling the motor in a condition where responsibility to a change in a deviation between a command phase and a real rotational phase is relatively high is generated. That is, generation of noise can be suppressed.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a sheet conveying apparatus using a motor control device that controls driving of a motor.

  Conventionally, as a method of controlling a motor, a method of performing phase feedback control for controlling a drive current flowing in a motor winding so that a deviation between a command phase of a motor rotor and an actual rotation phase is small is known. Yes. There is also a method of performing speed feedback control that controls the drive current so that the deviation between the command speed of the rotor and the actual rotation speed becomes small.

  Patent Document 1 describes a configuration in which drive current is controlled so that a deviation between a command value and an estimated value is reduced by performing proportional control (P), integral control (I), and differential control (D). Yes. The P control is a control method for controlling the estimated value based on a value proportional to the deviation between the command value and the estimated value. The I control is a control method for controlling the estimated value based on a value proportional to the time integral of the deviation between the command value and the estimated value. The D control is a control method for controlling the estimated value based on a value proportional to the time change of the deviation between the command value and the estimated value. When the D control is performed, the command value and the estimated value can be matched earlier than when the D control is not performed. That is, the responsiveness to the change in the deviation between the command value and the estimated value is higher when the D control is performed than when the D control is not performed. Note that the higher the responsiveness, the shorter the time from when the deviation between the command value and the estimated value changes until the control for reducing the deviation is executed.

  In an image forming apparatus, a configuration is known in which a conveyance roller for conveying a recording medium is rotated at a predetermined rotation speed in order to convey the recording medium at a predetermined speed. That is, a configuration for controlling a motor that drives a conveyance roller using speed feedback control is known. In general, PI control is performed when a motor that drives the transport roller is controlled by speed feedback control. That is, D control is not performed. This is because by controlling the motor using speed feedback control by PI control, the motor can be controlled with an accuracy higher than the accuracy of the motor control required for transporting the recording medium.

  Further, in the image forming apparatus, skew may occur in which the side on the leading end side of the conveyed recording medium is inclined. In the image forming apparatus disclosed in Patent Document 2, a registration roller and a pre-registration roller are provided on the upstream side of the registration roller in the direction in which the recording medium is conveyed. In addition, a sheet sensor that detects the leading edge of the recording medium is provided upstream of the registration roller and downstream of the pre-registration roller. In Patent Document 2, skew correction of a recording medium conveyed by a conveyance roller provided upstream of a pre-registration roller is performed by a registration roller, a pre-registration roller, a sheet sensor, and the like. Specifically, after the sheet sensor detects the leading edge of the recording medium, the pre-registration roller is rotated for a predetermined time, and the leading edge of the recording medium is brought into contact with the nip portion of the stopped registration roller. As described above, the skew correction of the recording medium is performed by rotating the pre-registration roller to bend the recording medium.

JP, 2006-127649, A JP 2003-252485 A

  When the skew correction of the recording medium is performed, it is necessary to accurately control the deflection amount of the recording medium. Therefore, when the pre-registration roller is controlled, the rotation amount of the roller is smaller than when the conveyance roller is controlled. Accurate control is required. In order to accurately control the rotation amount of the roller, it is necessary to control the rotation phase so that the rotation phase of the rotor of the motor driving the roller becomes a predetermined phase at a predetermined timing. That is, when controlling the motor that drives the pre-registration roller, it is necessary to use phase feedback control instead of speed feedback control. Further, in order for the rotational phase of the rotor to become a predetermined phase at a predetermined timing, it is necessary to match the rotational phase and the command phase as soon as possible. Therefore, when driving the pre-registration roller, it is necessary to perform phase feedback control using PID control. That is, the responsiveness to the change in the deviation between the command value and the estimated value when controlling the pre-registration roller needs to be higher than the responsiveness to the change in the deviation between the command value and the estimated value when controlling the transport roller. There is.

  In motor control, for example, when the rotational phase is controlled so that the actual rotational phase and the command phase coincide with each other, the rotational phase may periodically advance or lag behind the command phase. . That is, the deviation between the actual rotational phase and the command phase may periodically vary. When D control is performed in such a case, the cycle in which the deviation fluctuates is shortened due to an attempt to make the actual rotational phase coincide with the command phase earlier. When the cycle in which the deviation fluctuates becomes shorter, the cycle in which the current supplied to the motor winding fluctuates becomes shorter. If the cycle of fluctuation of the current supplied to the motor winding is shortened, the cycle of fluctuation of the torque applied to the rotor of the motor is also shortened, and the vibration of the motor occurs due to the short fluctuation cycle of the torque. Will occur. That is, if the motor is controlled in a state in which the responsiveness to the change in deviation between the command phase and the actual rotational phase is relatively high, noise is generated. Therefore, when controlling the motor that drives the pre-registration roller, noise is generated due to controlling the motor in a relatively high responsiveness to a change in deviation between the command phase and the actual rotational phase. There has been a demand for a good configuration for suppressing the problem.

  The present invention is based on the fact that the motor is controlled in a relatively high responsiveness to a change in the deviation between the command phase and the actual rotation phase in the period for controlling the motor that drives the conveyance roller that bends the recording medium. The purpose is to shorten the period when noise is generated.

In order to solve the above problems, the present invention provides:
A transport roller for transporting the sheet;
A motor for driving the transport roller;
Phase determining means for determining the rotational phase of the rotor of the motor;
Speed determining means for determining the rotational speed of the rotor of the motor;
By controlling the current value of the drive current flowing in the winding of the motor so that the deviation between the rotational speed determined by the speed determining means and the command speed indicating the target speed of the rotor becomes small, the motor Of the drive current flowing in the winding of the motor so that the deviation between the first control mode for controlling the motor and the rotation phase determined by the phase determination means and the command phase representing the target phase of the rotor is small. A mode in which the motor is controlled by controlling a current value, and the rotational phase and the command phase are more than responsive to changes in deviation between the rotational speed and the command speed in the first control mode. A first control means comprising a second control mode that is more responsive to changes in the deviation of
An abutting member provided on the downstream side of the conveying roller in the conveying direction for conveying the sheet, and abutted against a leading edge of the sheet conveyed by the conveying roller;
Control is performed so that the sheet is bent between the contact member and the transport roller by transporting the sheet by the transport roller in a state where the leading end of the sheet is in contact with the contact member. Two control means;
Have
The first control means is configured such that the leading edge of the sheet is in contact with the contact member during a period in which the second control means performs control for causing the sheet to contact the contact member and deflecting the sheet. The period until reaching a predetermined position with the conveying roller controls the motor in the first control mode, and the period after the leading edge of the sheet reaches the predetermined position The motor is controlled in two control modes.

  According to the present invention, the motor is controlled in a state in which the responsiveness to the change in the deviation between the command phase and the actual rotation phase is relatively high in the period for controlling the motor that drives the conveyance roller that bends the recording medium. It is possible to reduce the period during which noise due to the noise occurs. As a result, the motor is controlled in a relatively high responsiveness to a change in deviation between the command phase and the actual rotational phase in the period for controlling the motor that drives the conveyance roller that bends the recording medium. Generation of noise can be suppressed.

1 is a cross-sectional view illustrating an image forming apparatus according to a first embodiment. 2 is a block diagram illustrating a control configuration of the image forming apparatus. FIG. It is a block diagram which shows the structure of the motor control apparatus which concerns on 1st Embodiment. It is a figure which shows the relationship between the two-phase motor which consists of A phase and B phase, and d-axis and q-axis of a rotation coordinate system. FIG. 10 is a diagram illustrating a method for correcting skew of a side on the leading end side of a recording medium. It is a time chart which shows the drive sequence of the pre-registration roller which concerns on 1st Embodiment. It is a flowchart explaining the switching method of the control gain which concerns on 1st Embodiment. It is a time chart which shows the drive sequence of the pre-registration roller which concerns on 2nd Embodiment. It is a flowchart explaining the switching method of the control gain which concerns on 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the shape of the component parts described in this embodiment and the relative arrangement thereof should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention is not limited. The present invention is not intended to be limited to the following embodiments. In the following description, a case where the motor control device is provided in the image forming apparatus will be described, but the motor control device is not limited to the image forming apparatus. For example, the present invention is also used for a sheet conveying apparatus that conveys a sheet such as a recording medium or a document, and other apparatuses.

[First Embodiment]
[Image forming apparatus]
FIG. 1 is a cross-sectional view illustrating a configuration of a monochrome electrophotographic copying machine (hereinafter referred to as an image forming apparatus) 100 having a sheet conveying device used in the present embodiment. The image forming apparatus is not limited to a copying machine, and may be, for example, a facsimile machine, a printing machine, a printer, or the like. The recording method is not limited to the electrophotographic method, and may be, for example, an ink jet. Furthermore, the image forming apparatus may be in either monochrome or color format.

  The configuration and function of the image forming apparatus 100 will be described below with reference to FIG. As shown in FIG. 1, the image forming apparatus 100 includes a document feeding device 201, a reading device 202, and an image forming device main body 301. The reading device 202 corresponds to the reading unit in the present invention. The document feeding device 201 and the reading device 202 correspond to the document reading device in the present invention.

  Documents stacked on the document stacking unit 203 of the document feeder 201 are fed one by one by a sheet feeding roller 204 and are registered by a pre-registration roller (hereinafter referred to as a pre-registration roller) 207 along a conveyance guide 206. It is sent to a distribution roller (hereinafter referred to as a registration roller) 208.

  Between the registration roller 208 and the pre-registration roller 207, a sheet sensor 217 for detecting the presence or absence of a recording medium is provided. The registration roller 208 and the pre-registration roller 207 correct skew of the side on the leading end side of the recording medium based on the detection result of the sheet sensor 217. A specific method of skew correction will be described later. Thereafter, the registration roller 208 and the pre-registration roller 207 convey the document to the document reading unit. The sheet sensor 217 in the present embodiment is, for example, an optical sensor, but is not limited to this.

  Further, the document is conveyed at a constant speed by the conveyance roller 219 and discharged to the discharge tray 220 by the discharge roller 210. Reflected light from the document image illuminated by the illumination 211 at the reading position of the reading device 202 is guided to the image reading unit 215 by the optical system 209 including the reflection mirrors 212, 213, and 214, and is converted into an image signal by the image reading unit 215. Converted. The image reading unit 215 includes a lens, a CCD that is a photoelectric conversion element, a drive circuit for the CCD, and the like. The image signal output from the image reading unit 215 is subjected to various correction processes by the image processing unit 112 configured by a hardware device such as an ASIC, and then output to the image forming apparatus main body 301. As described above, the document is read.

  Further, there are a flow reading mode and a fixed reading mode as a document reading mode in the reading device 202. The flow-reading mode is a mode in which an image of a document is read while the document is conveyed at a constant speed with the illumination 211 and the optical system 209 fixed at predetermined positions. The fixed reading mode is a mode in which an original is placed on the original glass 216 of the reading device 202 and an image of the original placed on the original glass 216 is read while the illumination 211 and the optical system 209 are moved at a constant speed. is there. Normally, a sheet-like document is read in a flow reading mode, and a bound document such as a book or booklet is read in a fixed reading mode.

  Inside the image forming apparatus main body 301, sheet storage trays 302 and 304 are provided. Each of the sheet storage trays 302 and 304 can store different types of recording media. For example, A4 size plain paper is stored in the sheet storage tray 302, and A4 size thick paper is stored in the sheet storage tray 304. The recording medium is an image on which an image is formed by an image forming apparatus, and includes, for example, paper, a resin sheet, cloth, an OHP sheet, a label, and the like.

  The recording medium stored in the sheet storage tray 302 is fed by the paper feed roller 303 and sent to the registration roller 308 by the pre-registration roller 306. The recording medium stored in the sheet storage tray 304 is fed by the paper feed roller 305 and sent out to the registration roller 308 by the transport roller 307 and the pre-registration roller 306. Note that the pre-registration rollers 207 and 306 in the present embodiment correspond to the conveyance rollers in the present invention. The registration rollers 208 and 308 in the present embodiment correspond to the contact member and the second transport roller in the present invention.

  The image signal output from the reading device 202 is input to an optical scanning device 311 including a semiconductor laser and a polygon mirror. Further, the outer peripheral surface of the photosensitive drum 309 is charged by the charger 310. After the outer peripheral surface of the photosensitive drum 309 is charged, a laser beam corresponding to an image signal input from the reading device 202 to the optical scanning device 311 passes through the polygon mirror and the mirrors 312 and 313 from the optical scanning device 311 and is photosensitive. The drum 309 is irradiated on the outer peripheral surface. As a result, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 309. For charging the photosensitive drum, for example, a charging method using a corona charger or a charging roller is used.

  Subsequently, the electrostatic latent image is developed with toner in the developing device 314, and a toner image is formed on the outer peripheral surface of the photosensitive drum 309.

  Between the registration roller 308 and the pre-registration roller 306, a sheet sensor 327 that detects the presence or absence of a recording medium is provided. The registration roller 308 and the pre-registration roller 306 correct skew of the side on the leading end side of the recording medium based on the detection result of the sheet sensor 327. A specific method of skew correction will be described later. The sheet sensor 327 in the present embodiment is, for example, an optical sensor, but is not limited to this.

  The toner image formed on the photosensitive drum 309 is transferred to a recording medium by a transfer charger 315 provided at a position (transfer position) facing the photosensitive drum 309. At this time, the registration roller 308 and the pre-registration roller 327 send the skew-corrected recording medium to the transfer position in synchronization with the toner image.

  As described above, the recording medium to which the toner image has been transferred is sent to the fixing device 318 by the conveyance belt 317, and is heated and pressurized by the fixing device 318 to fix the toner image to the recording medium. In this manner, the image forming apparatus 100 forms an image on the recording medium.

  When image formation is performed in the single-sided printing mode, the recording medium that has passed through the fixing device 318 is discharged to a discharge tray (not shown) by discharge rollers 319 and 324. When image formation is performed in the double-sided printing mode, after the fixing process is performed on the first surface of the recording medium by the fixing device 318, the recording medium is a discharge roller 319, a conveyance roller 320, and a reverse roller 321. Is conveyed to the reverse path 325. Thereafter, the recording medium is conveyed again to the registration roller 308 by the conveying rollers 322 and 323, and an image is formed on the second surface of the recording medium by the method described above. Thereafter, the recording medium is discharged to a discharge tray (not shown) by discharge rollers 319 and 324.

  When the recording medium on which the image is formed on the first surface is discharged face-down to the outside of the image forming apparatus 100, the recording medium that has passed through the fixing device 318 passes through the discharge roller 319 to the conveyance roller 320. Carry in the direction of heading. Thereafter, the rotation of the conveyance roller 320 is reversed immediately before the trailing edge of the recording medium passes through the nip portion of the conveyance roller 320. As a result, the recording medium is discharged to the outside of the image forming apparatus 100 via the discharge roller 324 with the first surface of the recording medium facing downward.

  The above is the description of the configuration and functions of the image forming apparatus 100.

  FIG. 2 is a block diagram illustrating an example of a control configuration of the image forming apparatus 100. As shown in FIG. 2, the system controller 151 includes a CPU 151a, a ROM 151b, and a RAM 151c. The system controller 151 includes an image processing unit 112, an operation unit 152, an analog / digital (A / D) converter 153, a high voltage control unit 155, a motor control device 157, sheet sensors 217 and 327, sensors 159, and an AC driver. 160 is connected. The system controller 151 can send and receive data and commands to and from each connected unit.

  The CPU 151a executes various sequences related to a predetermined image forming sequence by reading and executing various programs stored in the ROM 151b.

  The RAM 151c is a storage device. The RAM 151c stores various data such as a set value for the high-voltage control unit 155, a command value for the motor control device 157, and information received from the operation unit 152, for example.

  The system controller 151 transmits setting value data of various apparatuses provided in the image forming apparatus 100 necessary for image processing in the image processing unit 112 to the image processing unit 112. Furthermore, the system controller 151 receives signals from various devices (signals from the sensors 159), and sets a setting value for the high-voltage control unit 155 based on the received signals. The high voltage controller 155 supplies a necessary voltage to the high voltage unit 156 (the charger 310, the developer 314, the transfer separator 315, etc.) according to the set value set by the system controller 151.

  The motor control device 157 controls the motor 509 in accordance with the command output from the CPU 151a. In FIG. 2, only the motor 509 is described as the motor for driving the load. However, in reality, the image forming apparatus is provided with a plurality of motors. Examples of loads include various rollers such as paper feed rollers 204, 303, 305, pre-registration rollers 207, 327, registration rollers 208, 308, and paper discharge rollers 210, 319, a photosensitive drum 309, a conveyor belt 317, an illumination system 211, and an optical system. 209 etc. Moreover, the structure which controls a several motor with one motor control apparatus may be sufficient. Further, in FIG. 2, only one motor control device is provided, but in reality, a plurality of motor control devices are provided.

  The A / D converter 153 receives the detection signal detected by the thermistor 154 for detecting the temperature of the fixing heater 161, converts the detection signal from an analog signal to a digital signal, and transmits it to the system controller 151. The system controller 151 controls the AC driver 160 based on the digital signal received from the A / D converter 153. The AC driver 160 controls the fixing heater 161 so that the temperature of the fixing heater 161 becomes a temperature necessary for performing the fixing process. The fixing heater 161 is a heater used for fixing processing and is included in the fixing device 318.

  The system controller 151 controls the operation unit 152 so that an operation screen for the user to set the type of recording medium to be used is displayed on a display unit provided in the operation unit 152. The system controller 151 receives information set by the user from the operation unit 152 and controls an operation sequence of the image forming apparatus 100 based on the information set by the user. In addition, the system controller 151 transmits information indicating the state of the image forming apparatus to the operation unit 152. Note that the information indicating the state of the image forming apparatus is, for example, information such as the number of images formed, whether or not an image is being formed, occurrence of a jam, and a location where the jam occurs. The operation unit 152 displays information received from the system controller 151 on the display unit.

  As described above, the system controller 151 controls the operation sequence of the image forming apparatus 100.

[Vector control]
Next, the motor control device in the present embodiment will be described. The motor control device in the present embodiment controls the motor using vector control. In the following description, a stepping motor is used as a motor for driving a load, but another motor such as a DC motor may be used. Further, in the following description, a case where the motor is a two-phase motor will be described, but other motors such as a three-phase motor may be used. Furthermore, the motor in the present embodiment is not provided with a sensor such as a rotary encoder for detecting the rotational phase of the rotor of the motor, but may be configured with a sensor.

  First, a method in which the motor control device 157 according to the present embodiment performs vector control will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a block diagram showing an example of the configuration of a motor control device 157 that controls a stepping motor (hereinafter referred to as a motor) 509.

  FIG. 4 is a diagram showing a relationship between a motor 509 having two phases of A phase (first phase) and B phase (second phase) and the d-axis and q-axis of the rotating coordinate system. In FIG. 4, in the stationary coordinate system, the axis corresponding to the A-phase winding is defined as the α axis, and the axis corresponding to the B-phase winding is defined as the β-axis. In addition, an angle formed by the α axis in the stationary coordinate system and the direction of the magnetic flux (d-axis direction) created by the magnetic poles of the permanent magnet used in the rotor 402 is defined as θ. The rotational phase of the rotor 402 is represented by an angle θ. In the vector control, the motor 509 is represented by a d-axis along the magnetic flux direction of the rotor 402 and a q-axis along a direction advanced 90 degrees counterclockwise from the d-axis (perpendicular to the d-axis). A rotational coordinate system based on the rotational phase θ of the rotor 402 is used.

  Vector control is a control method for controlling a motor by controlling a current value in a rotating coordinate system based on the rotational phase of the rotor of the motor. Specifically, for example, by performing phase feedback control (hereinafter referred to as phase control) for controlling a current value so that a deviation between a command phase representing a target phase of the rotor and an actual rotational phase is small. To control. Also, there is a method of controlling the motor by performing speed feedback control (hereinafter referred to as speed control) for controlling the current value so that the deviation between the command speed representing the target speed of the rotor and the actual rotational speed becomes small. is there. The current value in the rotating coordinate system is the current value of the q-axis component (torque current component) that generates torque in the rotor of the motor, and the d-axis component (excitation current component) that affects the strength of the magnetic flux passing through the motor windings. Corresponds to the current value of.

  The motor control device 157 in this embodiment can control the motor by any control method of vector control using phase control and vector control using speed control. The motor controller 157 includes a phase controller 502, a speed controller 500, a control switch 540, a current controller 503, a coordinate inverse converter 505, a coordinate converter 511, and a PWM inverter that supplies a drive current to the motor windings. 506 etc. are provided. The coordinate converter 511 represents a current vector corresponding to the drive current flowing in the A-phase and B-phase windings of the motor 509 from the stationary coordinate system represented by the α-axis and the β-axis by the q-axis and the d-axis. Convert coordinates to the rotating coordinate system. As a result, the drive current to be supplied to the A-phase and B-phase windings of the motor 509 is expressed by the q-axis component current value (q-axis current) and the d-axis component current value (d-axis current) in the rotating coordinate system. Can be used. Note that the q-axis current corresponds to a torque current that causes the rotor 402 of the motor 509 to generate torque. Further, the d-axis current corresponds to an excitation current that affects the strength of magnetic flux passing through the winding of the motor 509 and does not contribute to the generation of torque of the rotor 402. The motor control device 157 can control the q-axis current and the d-axis current independently. That is, the motor control device 157 can efficiently generate the torque necessary for the rotor 402 to rotate by controlling the q-axis current according to the load torque applied to the rotor 402.

  The motor control device 157 determines the rotation phase θ and the rotation speed ω of the rotor 402 of the motor 509 by a method described later, and performs vector control based on the determination result. The CPU 151a generates a command phase θ_ref indicating the target phase of the rotor 402 of the motor 509 and a command speed ω_ref indicating the target speed, and outputs the command phase θ_ref and the command speed ω_ref to the motor control device 157 at a predetermined time period.

  The subtractor 101 calculates a deviation between the rotational phase θ of the rotor 402 of the motor 509 and the command phase θ_ref and outputs the deviation to the phase controller 502.

  The phase controller 502 uses the q-axis current command value iq_ref and the d-axis so that the deviation output from the subtractor 101 becomes small based on proportional control (P), integral control (I), and differential control (D). A current command value id_ref is generated and output. Specifically, the phase controller 502 controls the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation output from the subtractor 101 is 0 based on P control, I control, and D control. Is generated and output. That is, the phase controller 502 performs PID control. The P control is a control method for controlling the value to be controlled based on a value proportional to the deviation between the command value and the estimated value. The I control is a control method for controlling the value to be controlled based on a value proportional to the time integral of the deviation between the command value and the estimated value. The D control is a control method for controlling the value to be controlled based on a value proportional to the time change of the deviation between the command value and the estimated value. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref that normally affects the strength of the magnetic flux passing through the winding is set to 0, but the present invention is not limited to this.

  The subtractor 104 calculates a deviation between the rotation speed ω of the rotor 402 of the motor 509 and the command speed ω_ref and outputs the deviation to the speed controller 500.

  The speed controller 500 generates the q-axis current command value iq_ref and the d-axis current command value id_ref based on the proportional control (P) and the integral control (I) so that the deviation output from the subtractor 104 becomes small. And output. Specifically, the speed controller 500 generates the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation output from the subtractor 104 becomes 0 based on P control and I control. Output. That is, the speed controller 500 performs PI control. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref that normally affects the strength of the magnetic flux passing through the winding is set to 0, but the present invention is not limited to this.

The CPU 151a outputs a switching signal for switching between phase control and speed control to the control switch 540. The control switch 540 controls the switch 520 based on the switch signal.
Specifically, the control switch 540, when performing vector control using phase control, switches the switch 520 so that the q-axis current command value iq_ref output from the phase controller 502 is output to the subtractor 102. Control the state of Further, the state of the changeover switch 520 is controlled so that the d-axis current command value id_ref output from the phase controller 502 is output to the subtractor 103. As a result, vector control using phase control is performed. In addition, when performing vector control by speed control, the control switch 540 controls the state of the switch 520 so that the q-axis current command value iq_ref output from the speed controller 500 is output to the subtractor 102. . Further, the state of the changeover switch 520 is controlled so that the d-axis current command value id_ref output from the speed controller 500 is output to the subtractor 103. As a result, vector control using speed control is performed. Vector control by speed control corresponds to the first control mode in the present invention, and vector control by phase control corresponds to the second control mode in the present invention. As described above, the phase controller 502 in this embodiment performs PID control. Further, the speed controller 500 in this embodiment performs PI control. That is, the responsiveness to the change in the deviation between the rotational phase θ and the command phase θ_ref in the phase control is higher than the responsiveness to the change in the deviation between the rotational speed ω and the command speed ω_ref in the speed control. Note that the higher the responsiveness, the shorter the time from when the deviation between the command value and the estimated value changes until the control for reducing the deviation is executed.

  Drive currents flowing in the A-phase and B-phase windings of the motor 509 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 value converted from the analog value to the digital value by the A / D converter 510 is expressed by the following equation using the current vector phase θe shown in FIG. 4 as the current values iα and iβ in the stationary coordinate system. . The phase θe of the current vector is defined as an angle formed by the α axis and the current vector.
iα = I * cos θe (1)
iβ = I * sin θe (2)

  These current values iα and iβ are input to the coordinate converter 511 and the induced voltage determiner 512.

In the coordinate converter 511, the current values iα and iβ are coordinate-converted into the q-axis current value iq and the d-axis current value id in the rotating coordinate system by the following equations.
id = cos θ * iα + sin θ * iβ (3)
iq = −sin θ * iα + cos θ * iβ (4)

  As described above, the coordinate converter 511 converts the current vector corresponding to the drive current flowing in the A-phase and B-phase windings of the motor 509 from the static coordinate system represented by the α axis and the β axis to the q axis and Coordinates are converted into a rotating coordinate system represented by the d axis.

  The subtractor 102 calculates a deviation between iq_ref output from the control changeover switch 520 and the current value iq output from the coordinate converter 511, and outputs the deviation to the current controller 503. The subtractor 103 calculates a deviation between id_ref output from the control changeover switch 520 and the current value id output from the coordinate converter 511, and outputs the deviation to the current controller 503.

  The current controller 503 generates drive voltages Vq and Vd based on PID control so that the deviations are reduced. Specifically, the current controller 503 generates drive voltages Vq and Vd so that the deviations become 0, and outputs them to the coordinate inverse converter 505. That is, the current controller 503 functions as voltage generation means. Note that the current controller 503 in the present embodiment generates the drive voltages Vq and Vd based on PID control, but may generate the drive voltages Vq and Vd based on PI control, for example.

The coordinate inverse converter 505 converts the drive voltages Vq and Vd output from the current controller 503 in the rotating coordinate system into the drive voltages Vα and Vβ in the stationary coordinate system according to the following equation.
Vα = cos θ * Vd−sin θ * Vq (5)
Vβ = sin θ * Vd + cos θ * Vq (6)

  The coordinate inverse converter 505 converts the drive voltages Vq and Vd in the rotating coordinate system into the drive voltages Vα and Vβ in the stationary coordinate system, and then outputs Vα and Vβ to the induced voltage determiner 512 and the PWM inverter 506.

  The PWM inverter 506 has a full bridge circuit. The full bridge circuit is driven by a PWM signal based on the drive voltages Vα and Vβ input from the coordinate inverse converter 505. As a result, the PWM inverter 506 generates drive currents iα and iβ corresponding to the drive voltages Vα and Vβ, and drives the motor 509 by supplying the drive currents iα and iβ to the windings of each phase of the motor 509. . That is, the PWM inverter 506 functions as a supply unit that supplies current to the windings of each phase of the motor 509. In this embodiment, the PWM inverter has a full bridge circuit, but may be a half bridge circuit or the like.

Next, a method for determining the rotational phase θ will be described. For the determination of the rotational phase θ of the rotor 402, values of induced voltages Eα and Eβ induced in the A-phase and B-phase windings of the motor 509 by the rotation of the rotor 402 are used. The value of the induced voltage is determined (calculated) by the induced voltage determiner 512. Specifically, the induced voltages Eα and Eβ are input from the A / D converter 510 to the induced voltage determiner 512 and the current values iα and iβ input from the coordinate inverse converter 505 to the induced voltage determiner 512. From the drive voltages Vα and Vβ, it is determined by the following equation.
Eα = Vα−R * iα−L * diα / dt (7)
Eβ = Vβ−R * iβ−L * diβ / dt (8)

  Here, R is winding resistance, and L is winding inductance. The values of R and L are values specific to the motor 509 being used, and are stored in advance in a memory (not shown) or the like provided in the ROM 151b or the motor control device 157.

The induced voltages Eα and Eβ determined by the induced voltage determiner 512 are input to the phase determiner 513. The phase determiner 513 determines the rotational phase θ of the rotor 402 of the motor 509 based on the ratio of the induced voltage Eα and the induced voltage Eβ output from the induced voltage determiner 512 according to the following equation.
θ = tan ^ −1 (−Eβ / Eα) (9)

  In the present embodiment, the phase determiner 513 determines the rotational phase θ by performing a calculation based on Expression (9), but this is not restrictive. For example, a table indicating the relationship between the induced voltage Eα and the induced voltage Eβ and the rotational phase θ corresponding to the induced voltage Eα and the induced voltage Eβ is stored in the ROM 151b or the like, and the rotational phase θ is determined by referring to the table. You may decide.

  The rotational phase θ of the rotor 402 obtained as described above is input to the subtractor 101, the speed determiner 514, the coordinate inverse converter 505, and the coordinate converter 511.

The speed determiner 514 determines the rotational speed ω based on the temporal change of the rotational phase θ output from the phase determiner 513. The following equation (10) is used for determining the speed.
ω = dθ / dt (10)

Then, the speed determiner 514 outputs the determined rotation speed ω to the subtractor 104.

  Thereafter, the motor control device 157 repeatedly performs this control.

  As described above, the motor control device 157 according to the present embodiment can control the motor by any control method of vector control using phase control and vector control using speed control. When the vector control is performed, it is possible to suppress the motor from being stepped out, an increase in motor noise due to excessive torque, and an increase in power consumption. Further, when phase control is performed, it is possible to control the rotational phase of the rotor to be a predetermined phase. Moreover, when speed control is performed, it can control so that the rotational speed of a rotor may become predetermined | prescribed speed. In an image forming apparatus, it is necessary to rotate a conveyance roller for conveying a recording medium at a predetermined rotational speed in order to convey the recording medium at a predetermined speed. Therefore, in the present embodiment, vector control using speed control is applied when controlling a motor that drives a roller (for example, a conveyance roller 307) that conveys a recording medium. As a result, the recording medium can be conveyed at a predetermined speed.

[Skew correction]
FIG. 5 is a diagram for explaining a method of correcting skew of the side on the leading end side of the recording medium. A skew correction method performed by the registration roller 308 and the pre-registration roller 306 will be described below with reference to FIG. Note that the skew correction method performed by the registration roller 208 and the pre-registration roller 207 is the same as the method described below, and a description thereof will be omitted.

  First, the motor controller 157 controls the driving of the motor 509 to rotate the motor 509, and the motor 509 rotates to rotate the pre-registration roller 306. The recording medium P is conveyed in the conveying direction as the pre-registration roller 306 rotates, and the leading end of the recording medium P comes into contact with the nip portion of the stopped registration roller 308. Thereafter, the motor control device 157 further continues the rotation of the pre-registration roller 306 by continuing the rotation of the motor 509. As a result, the rear end side of the recording medium P can be further conveyed in the conveying direction, and the recording medium P can be bent.

  In the present embodiment, it is assumed that the pre-registration roller 306 is rotated for a predetermined time T1 after the sheet sensor 327 detects the leading edge of the recording medium P. Specifically, the CPU 151a outputs a command to the motor control device 157 to stop the rotation of the pre-registration roller 306 after a predetermined time T1 after the sheet sensor 327 detects the leading edge of the recording medium. More specifically, for example, the CPU 151a outputs the same command phase as the previously output command phase as the command phase θ_ref to the motor control device 157. Thereafter, the same command phase is continuously output to the motor control device 157. As a result, the position of the rotor 402 can be fixed. That is, the rotation of the pre-registration roller 306 can be stopped. Further, the rotation of the pre-registration roller 327 may be stopped by the CPU 151a outputting an enable signal 'L' to the motor control device 157 and the motor control device 157 stopping the motor 509 that drives the pre-registration roller 327. The enable signal is a signal that permits or prohibits the operation of the motor control device 157. When the enable signal is ‘L (low level)’, the CPU 151 a prohibits the operation of the motor control device 157. That is, the control of the motor 509 by the motor control device 157 is ended. When the enable signal is “H (high level)”, the CPU 151a permits the operation of the motor control device 157, and the motor control device 157 controls the drive of the motor 509 based on a command output from the CPU 151a. Do. It is assumed that the predetermined time T1 is set in advance in consideration of the time until the leading edge of the recording medium reaches the registration roller 308 and the time after which the recording medium is bent.

  As described above, after the leading edge of the recording medium P is detected by the sheet sensor 327, the pre-registration roller 306 is rotated for a predetermined time T1 to bend the recording medium P. As a result, an elastic force acts on the recording medium P, whereby the leading end of the recording medium P can be brought into contact with the nip portion of the registration roller. As a result, the skew of the recording medium P can be corrected.

  When skew correction is performed, the load torque applied to the rotor of the motor that drives the pre-registration roller is more likely to fluctuate than the load torque applied to the rotor of the motor that drives the conveyance roller 307 and the like. This is because when skew correction is performed, there are more factors that cause the load torque to fluctuate than when the conveyance roller 307 or the like is driven, such as when the recording medium comes into contact with the registration roller or the deflection amount of the recording medium increases. Because. Further, when skew correction is performed, it is necessary to accurately control the deflection amount of the recording medium. Therefore, when the pre-registration roller is controlled, the conveyance roller (for example, the conveyance roller 307) that conveys the recording medium is controlled. In comparison with the above, it is required to accurately control the rotation amount of the roller. In order to accurately control the rotation amount of the roller, it is necessary to control the rotation phase so that the rotation phase of the rotor of the motor driving the roller becomes a predetermined phase at a predetermined timing. That is, when controlling the motor 509 that drives the pre-registration roller, it is necessary to use phase control instead of speed control. Further, in order for the rotational phase of the rotor to become a predetermined phase at a predetermined timing, it is necessary to match the actual rotational phase and the command phase as soon as possible.

  As described above, in this embodiment, the phase controller 502 performs PID control. When the D control is performed, the command value and the estimated value can be matched earlier than when the D control is not performed.

  In motor control, for example, when the rotational phase is controlled so that the actual rotational phase matches the command phase, the actual rotational phase may periodically advance or lag behind the command phase. There is. That is, the deviation between the actual rotational phase and the command phase may periodically vary. When D control is performed in such a case, the cycle in which the deviation fluctuates is shortened due to an attempt to match the rotation phase and the command phase earlier. When the cycle in which the deviation fluctuates becomes shorter, the cycle in which the current supplied to the motor winding fluctuates becomes shorter. If the cycle of fluctuation of the current supplied to the motor winding is shortened, the cycle of fluctuation of the torque applied to the rotor of the motor is also shortened, and the vibration of the motor occurs due to the short fluctuation cycle of the torque. Will occur. That is, if the motor is controlled in a state in which the responsiveness to the change in deviation between the command phase and the actual rotational phase is relatively high, noise is generated. Therefore, in this embodiment, the noise caused by controlling the motor in a relatively high responsiveness to a change in the deviation between the command phase and the actual rotational phase by applying the following configuration to the motor control device. Is suppressed from occurring.

[Switching between phase control and speed control]
As described above, in this embodiment, the responsiveness to the change in the deviation between the rotational phase θ and the command phase θ_ref in the phase control is more than the responsiveness to the change in the deviation between the rotational speed ω and the command speed ω_ref in the speed control. High responsiveness. Therefore, the command value and the estimated value can be matched earlier when performing phase control than when performing speed control. That is, noise is less likely to occur when speed control is performed than when phase control is performed.

  Therefore, in the present embodiment, when the motor 509 is driven by speed control and phase control is necessary, the motor control method is switched from speed control to phase control. That is, phase control is performed only during a period where phase control is necessary.

  FIG. 6 is a time chart showing a sequence of driving the pre-registration roller in the present embodiment. Hereinafter, a driving sequence of the pre-registration roller 306 will be described with reference to FIGS. 5 and 6. Note that the sequence shown in FIG. 6 is an example in the present embodiment, and the present invention is not limited to this.

  As shown in FIG. 6, after the conveyance of the recording medium is started, driving of the pre-registration roller 306 by vector control using speed control is started at time t1. Note that the time t1 at which the pre-registration roller 306 starts to be driven is determined in advance by the operation sequence of the image forming apparatus. For example, the time t1 is a predetermined time after the sheet sensor (not shown) provided between the paper feed roller 303 and the pre-registration roller 306 detects the front end of the recording medium, and the front end of the recording medium is the pre-registration roller. It is set as the time before reaching 306.

  After that, at time t2, at a time t3 when a predetermined time T2 has elapsed since the sheet sensor 327 detected the leading edge of the recording medium, the CPU 151a performs control so that vector control using phase control is performed by the motor control device 157. A switch signal is output to the switch 540. As a result, the motor control device 157 performs vector control using phase control. Note that time t3 is a time period from time t2 when the sheet sensor 327 detects the leading edge of the recording medium to time t4 when the leading edge of the recording medium reaches the registration roller 308, and the leading edge of the recording medium reaches the registration roller 308. It is a time when the control is switched in time. The time t3 may be the same time as the time t2. That is, the predetermined time T2 may be zero. That is, when the sheet sensor 327 detects the leading edge of the recording medium, the CPU 151a may output a switching signal to the control switch 540. However, when the control period by the phase control is as short as possible, it is possible to more effectively suppress the occurrence of noise caused by using the D control. Therefore, the time t3 should be as close to the time t4 as possible. .

  Thereafter, the recording medium comes into contact with the registration roller 308 in a stopped state, and the skew correction of the recording medium is performed by the method described above. Further, as described above, the CPU 151a instructs the motor control device 157 to stop the rotation of the pre-registration roller 306 at the time t5 when the predetermined time T1 has elapsed from the time t2 when the sheet sensor 327 detects the leading edge of the recording medium. Output. As a result, the rotation of the pre-registration roller 306 stops and the skew correction of the recording medium is completed.

  As described above, the motor 509 is controlled by the vector control using the speed control during the period from the time t1 to the time t3 when the driving of the pre-registration roller is started. Further, after time t3, the motor 509 is controlled by vector control using phase control.

  FIG. 7 is a flowchart illustrating a method for switching the motor control method in the present embodiment. Hereinafter, a method of switching the motor control method in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the CPU 151a.

  When the print job is started, in S1001, the system controller 151 controls the operation sequence of the image forming apparatus 100 and starts conveying the recording medium.

  Thereafter, in S1002, the CPU 151a outputs a switching signal to the control switch 540 so that vector control using speed control is performed by the motor control device 157. Further, the motor control device 157 starts control of the motor 509 based on a command from the CPU 151a. As a result, the motor control device 157 starts driving the pre-registration roller 306 by vector control using speed control. Thereafter, the CPU 151a advances the process to S1003.

  In S1003, when the sheet sensor 327 detects the leading edge of the recording medium, the CPU 151a advances the processing to S1004. If the predetermined time T2 has elapsed since the sheet sensor 327 detected the leading edge of the recording medium in S1004, the CPU 151a advances the process to S1005.

  In step S <b> 1005, the CPU 151 a outputs a switching signal to the control switch 540 so that the motor control device 157 performs vector control using phase control. As a result, vector control using phase control is performed.

  Thereafter, in S1006, the motor control device 157 controls the motor 509 by vector control using phase control. Specifically, the CPU 151a controls the motor control device 157 to rotate the motor 509 for a predetermined time. The motor control device 157 rotates the pre-registration roller 306 by the amount of rotation corresponding to the predetermined time by rotating the motor 509 for a predetermined time in accordance with a command from the CPU 151a. By controlling the motor 509 by vector control using phase control, the amount of rotation of the pre-registration roller 306 can be accurately controlled.

  Next, when a predetermined time T1 has elapsed since the sheet sensor 327 detected the leading edge of the recording medium in S1007, in S1008, the CPU 151a controls the motor control device 157 to stop driving the motor 509. As a result, the rotation of the pre-registration roller 306 stops. As a result, the recording medium can be deflected by an appropriate amount, and skew correction can be performed appropriately. Thereafter, the CPU 151a advances the process to S1009.

  In step S1009, the image forming apparatus 100 resumes conveyance of the recording medium. Specifically, the CPU 151a controls a motor control device that controls the driving of the registration roller 308 so as to drive the registration roller 308. As a result, the conveyance of the recording medium is resumed.

  In step S1010, the image forming apparatus 100 forms (transfers) an image on a recording medium, and the CPU 151a advances the process to step S1011.

  Thereafter, the CPU 151a repeats the above-described processing until the print job is completed.

  As described above, in the present embodiment, the motor is controlled by the vector control using the speed control during the period from the time t1 to the time t3 when the driving of the pre-registration roller is started. After time t3, the motor is controlled by vector control using phase control. That is, phase control is performed only during a period in which it is necessary to accurately control the rotation amount of the roller. As a result, the skew correction of the recording medium can be performed appropriately. In the present embodiment, the phase controller 502 performs PID control. The speed controller 500 performs PI control. That is, noise is less likely to occur when speed control is performed than when phase control is performed. As a result, during the period for controlling the motor that drives the pre-registration roller, the period during which noise is generated due to controlling the motor in a relatively high responsiveness to a change in deviation between the command phase and the actual rotational phase is shortened. can do. That is, it is possible to suppress the occurrence of noise caused by controlling the motor in a state in which the responsiveness to the change in deviation between the command phase and the actual rotational phase is relatively high.

[Second Embodiment]
The description of the parts of the image forming apparatus and the motor control apparatus that are the same as those in the first embodiment will be omitted.

  In the first embodiment, when a predetermined time T2 has elapsed after the sheet sensor 327 detects the leading edge of the recording medium, the control method of the motor that drives the pre-registration roller 306 is switched from speed control to phase control. In the present embodiment, a configuration will be described in which the control method of the motor that drives the pre-registration roller 306 is switched from speed control to phase control when a predetermined time T3 has elapsed since the drive of the pre-registration roller 306 has started.

  FIG. 8 is a time chart showing a sequence of driving the pre-registration roller in the present embodiment. Hereinafter, a driving sequence of the pre-registration roller 306 will be described with reference to FIG. Note that the sequence shown in FIG. 8 is an example in the present embodiment, and the present invention is not limited to this.

  As shown in FIG. 8, after conveyance of the recording medium is started, at time t1, the CPU 151a outputs a switching signal to the control switch 540 so that vector control using speed control by the motor control device 157 is performed. . As a result, vector control using speed control by the motor control device 157 is performed. Note that the time t1 at which the pre-registration roller 306 starts to be driven is determined in advance by the operation sequence of the image forming apparatus. For example, the time t1 is a predetermined time after the sheet sensor (not shown) provided between the paper feed roller 303 and the pre-registration roller 306 detects the front end of the recording medium, and the front end of the recording medium is the pre-registration roller. It is set as the time before reaching 306. The time when the sheet sensor 327 detects the leading edge of the recording medium is defined as time t2.

  Thereafter, at time t3 when a predetermined time T3 has elapsed from time t1, the CPU 151a outputs a switching signal to the control switch 540 so that the motor control device 157 performs vector control using phase control. As a result, the motor control device 157 performs vector control using phase control. Time t3 is a time period from time t1 when driving of the pre-registration roller 306 is started to time t4 when the leading edge of the recording medium reaches the registration roller 308, and before the leading edge of the recording medium reaches the registration roller 308. It is a time when control switching is in time. Note that the front-rear relationship between time t2 and time t3 is not limited to the relationship shown in FIG. For example, the time t3 may be the same time as the time t2, or the time t3 may be a time before the time t2. However, when the control period by the phase control is as short as possible, it is possible to more effectively suppress the occurrence of noise caused by using the D control. Therefore, the time t3 should be as close to the time t4 as possible. . The predetermined time T3 is set in advance based on the operation sequence of the image forming apparatus 100.

  Thereafter, the recording medium comes into contact with the registration roller 308 in a stopped state, and the skew correction of the recording medium is performed by the method described above. Further, as described above, the CPU 151a instructs the motor control device 157 to stop the rotation of the pre-registration roller 306 at the time t5 when the predetermined time T1 has elapsed from the time t2 when the sheet sensor 327 detects the leading edge of the recording medium. Output. As a result, the rotation of the pre-registration roller 306 stops and the skew correction of the recording medium is completed.

  As described above, the motor 509 is controlled by the vector control using the speed control during the period from the time t1 to the time t3 when the driving of the pre-registration roller is started. Further, after time t3, the motor is controlled by vector control using phase control.

  FIG. 9 is a flowchart illustrating a method for switching the motor control method in the present embodiment. Hereinafter, a method of switching the motor control method in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the CPU 151a.

  When the print job is started, in step S2001, the system controller 151 controls the operation sequence of the image forming apparatus 100 and starts conveying the recording medium.

  Thereafter, in S2002, the CPU 151a outputs a switching signal to the control switch 540 so that vector control using speed control is performed by the motor control device 157.

  In step S2003, when it is time to rotate the pre-registration roller 306 determined in the operation sequence, the motor control device 157 starts control of the motor 509 by vector control using speed control. When driving of the pre-registration roller 306 is started, the process proceeds to S2004.

  In S2004, when a predetermined time T3 has elapsed since the driving of the pre-registration roller 306 is started, in S2005, the CPU 151a sends a switching signal to the control switch 540 so that the motor control device 157 performs vector control using phase control. Output. Thereafter, the motor control device 157 controls the motor 509 in the same manner as in S1006 of FIG. By controlling the motor 509 using phase control, the amount of rotation of the pre-registration roller 306 can be accurately controlled.

  Next, when a predetermined time T1 has elapsed since the sheet sensor 327 detected the leading edge of the recording medium in S2006, the CPU 151a controls the motor control device 157 to stop driving the motor 509 in S2007. As a result, the rotation of the pre-registration roller 306 stops. As a result, the recording medium can be deflected by an appropriate amount, and skew correction can be performed appropriately. Thereafter, the CPU 151a advances the process to S2007.

  In step S2008, the image forming apparatus 100 resumes conveyance of the recording medium. Specifically, the CPU 151a controls the motor control device 157 that controls the driving of the registration roller 308 so as to drive the registration roller 308. As a result, the conveyance of the recording medium is resumed.

  Next, in S2009, the image forming apparatus 100 forms an image on the recording medium, and the CPU 151a advances the processing to S2010.

  Thereafter, the CPU 151a repeats the above-described processing until the print job is completed.

  As described above, in the present embodiment, the motor is controlled by the vector control using the speed control during the period from the time t1 to the time t3 when the driving of the pre-registration roller is started. After time t3, the motor is controlled by vector control using phase control. That is, phase control is performed only during a period in which it is necessary to accurately control the rotation amount of the roller. As a result, the skew correction of the recording medium can be performed appropriately. In the present embodiment, the phase controller 502 performs PID control. The speed controller 500 performs PI control. That is, noise is less likely to occur when speed control is performed than when phase control is performed. As a result, during the period for controlling the motor that drives the pre-registration roller, the period during which noise is generated due to controlling the motor in a relatively high responsiveness to a change in deviation between the command phase and the actual rotational phase is shortened. can do. That is, it is possible to suppress the occurrence of noise caused by controlling the motor in a state in which the responsiveness to the change in deviation between the command phase and the actual rotational phase is relatively high.

  In the first and second embodiments, the configuration in which the motor control method is switched between phase control and speed control is applied to the motor that drives the pre-registration roller 306 of the image forming apparatus main body 301. However, the present invention is not limited to this. It is not a thing. For example, the above configuration may be applied to a motor that drives a conveyance roller that conveys a sheet in a sheet conveyance device (ADF, document feeder 201, or the like) that conveys a sheet such as a document.

  The configurations in the first and second embodiments are not limited to the case of controlling the motor by vector control, but can also be applied to the case of feeding back the rotation phase and rotation speed and controlling the motor based on the feedback result. .

151a CPU
157 Motor controller 306 Pre-registration roller 308 Registration roller 402 Rotor 502 Phase controller 509 Stepping motor 513 Phase determiner

Claims (17)

A transport roller for transporting the sheet;
A motor for driving the transport roller;
Phase determining means for determining the rotational phase of the rotor of the motor;
Speed determining means for determining the rotational speed of the rotor of the motor;
By controlling the current value of the drive current flowing in the winding of the motor so that the deviation between the rotational speed determined by the speed determining means and the command speed indicating the target speed of the rotor becomes small, the motor Of the drive current flowing in the winding of the motor so that the deviation between the first control mode for controlling the motor and the rotation phase determined by the phase determination means and the command phase representing the target phase of the rotor is small. A mode in which the motor is controlled by controlling a current value, and the rotational phase and the command phase are more than responsive to changes in deviation between the rotational speed and the command speed in the first control mode. A first control means comprising a second control mode that is more responsive to changes in the deviation of
An abutting member provided on the downstream side of the conveying roller in the conveying direction for conveying the sheet, and abutted against a leading edge of the sheet conveyed by the conveying roller;
Control is performed so that the sheet is bent between the contact member and the transport roller by transporting the sheet by the transport roller in a state where the leading end of the sheet is in contact with the contact member. Two control means;
Have
The first control means is configured such that the leading edge of the sheet is in contact with the contact member during a period in which the second control means performs control for causing the sheet to contact the contact member and deflecting the sheet. The period until reaching a predetermined position with the conveying roller controls the motor in the first control mode, and the period after the leading edge of the sheet reaches the predetermined position A sheet conveying apparatus that controls the motor in two control modes. The sheet conveying device detects the leading edge of the sheet downstream of the conveying roller in the conveying direction of conveying the sheet and upstream of the contact member in the conveying direction of conveying the sheet. Having means,
The first control means rotates the motor until a first predetermined time elapses after the detection means detects the leading edge of the sheet,
2. The motor according to claim 1, wherein the first control unit stops the rotation of the motor when the first predetermined time elapses after the detection unit detects the leading edge of the sheet. Sheet transport device. The second control means is a switching signal for switching the control mode for controlling the motor from the first control mode to the second control mode at the timing when the leading edge of the sheet reaches the predetermined position. To the first control means,
3. The seat according to claim 1, wherein the first control unit switches the control mode from the first control mode to the second control mode in response to reception of the switching signal. 4. Conveying device.   The second control means outputs the switching signal to the first control means at a timing when a second predetermined time has elapsed after the detection means detects the leading edge of the sheet. The sheet conveying apparatus according to claim 3.   The second control means outputs the switching signal to the first control means at a timing when a third predetermined time has elapsed since the first control means started driving the motor. The sheet conveying device according to claim 3. The first control means includes
Without using the D control for controlling the rotational speed based on the value proportional to the time change of the deviation between the rotational speed determined by the speed determining means and the command speed indicating the target speed of the rotor, the deviation is A first control mode for controlling the motor by controlling the current value of the drive current flowing in the winding of the motor to be small;
The deviation is reduced by using D control for controlling the rotational phase based on a value proportional to a temporal change in deviation between the rotational phase determined by the phase determining means and the command phase representing the target phase of the rotor. A second control mode for controlling the motor by controlling the current value of the drive current flowing in the winding of the motor to be
The sheet conveying apparatus according to any one of claims 1 to 5, further comprising: The sheet conveying apparatus is
Having transfer means for transferring an image to the sheet;
The contact member is a second roller that conveys the sheet to the transfer unit such that an image is transferred to a predetermined position of the sheet by the transfer unit;
The sheet conveying apparatus according to any one of claims 1 to 6, wherein the first control unit rotates the conveying roller in a state where the second roller is stopped. The first control means includes
Supply means for supplying a drive current to each of the first phase winding and the second phase winding of the motor;
Voltage generating means for generating a driving voltage for driving the supply means;
Detecting means for detecting a current value of a driving current supplied to each of the first phase winding and the second phase winding of the motor by the supply means;
Based on the drive voltage generated by the voltage generation means and the current value detected by the detection means, induction in the first phase winding and the second phase winding by rotation of the rotor of the motor. Induced voltage determining means for determining the magnitude of the induced voltage to be generated;
Have
The phase determining means determines the rotational phase based on the magnitude of the induced voltage of the first phase and the magnitude of the induced voltage of the second phase determined by the induced voltage determining means. Item 8. The sheet conveying apparatus according to any one of Items 1 to 7.   The sheet according to any one of claims 1 to 8, wherein the speed determining unit determines a rotational speed of the rotor based on a temporal change of the rotational phase determined by the phase determining unit. Conveying device. The first control means includes
Coordinate conversion means for coordinate-converting the current value in the stationary coordinate system detected by the detection means into the current value in the rotation coordinate system based on the rotation phase based on the rotation phase determined by the phase determination means; ,
Speed control means for generating and outputting a current value of the drive current in the rotating coordinate system so that a deviation between the command speed and the rotational speed determined by the speed determining means is small;
Have
When the first control unit controls the motor in the first control mode, the deviation between the current value output from the speed control unit and the current value coordinate-converted by the coordinate conversion unit is small. 10. The motor according to claim 8, wherein the motor is controlled by controlling a current value of a driving current flowing in each of the first phase winding and the second phase winding of the motor. Sheet conveying device. The voltage generation means generates a drive voltage of the rotating coordinate system so that a deviation between the current value output from the speed control means and the current value coordinate-converted by the coordinate conversion means is small,
The first control means includes coordinate reverse conversion means for reversely converting the driving voltage of the rotating coordinate system generated by the voltage generating means to the driving voltage of the stationary coordinate system,
The sheet conveying apparatus according to claim 10, wherein the supply unit is driven by a drive voltage that has undergone coordinate reverse conversion by the coordinate reverse conversion unit. The first control means includes
A coordinate conversion means for converting the current value of the stationary coordinate system detected by the detection means into a current value of a rotation coordinate system based on the rotation phase based on the rotation phase determined by the phase determination means; ,
Phase control means for generating and outputting a current value of the drive current in the rotating coordinate system so that a deviation between the command phase and the rotational phase determined by the phase determining means is small;
Have
When the first control unit controls the motor in the second control mode, a deviation between the current value output from the phase control unit and the current value coordinate-converted by the coordinate conversion unit is small. 10. The motor according to claim 8, wherein the motor is controlled by controlling a current value of a driving current flowing in each of the first phase winding and the second phase winding of the motor. Sheet conveying device. The voltage generation means generates a drive voltage of the rotating coordinate system so that a deviation between the current value output from the phase control means and the current value coordinate-converted by the coordinate conversion means is small,
The first control means includes coordinate reverse conversion means for reversely converting the driving voltage of the rotating coordinate system generated by the voltage generating means to the driving voltage of the stationary coordinate system,
The sheet conveying apparatus according to claim 12, wherein the supply unit is driven by a drive voltage that has undergone coordinate reverse conversion by the coordinate reverse conversion unit. The drive current is represented in the rotating coordinate system using a torque current component that generates torque in the rotor and an excitation current component that affects the strength of magnetic flux passing through the winding of the motor,
The first control means controls the motor by controlling the value of the exciting current component to be 0 and controlling the value of the torque current component. The sheet conveying apparatus as described in any one of these. A sheet conveying device according to any one of claims 1 to 14,
A document stacking unit for loading documents,
Have
An original feeding apparatus, wherein the original loaded on the original stacking unit feeds the original. A document feeder according to claim 15;
Reading means for reading the document fed by the document feeding device;
A document reading apparatus comprising: A sheet conveying device according to any one of claims 1 to 14,
Image forming means for forming an image on a recording medium;
Have
The image forming apparatus, wherein the image forming unit forms an image on the recording medium conveyed by the sheet conveying apparatus.

Images