JP2014180135A - Motor control device, image forming apparatus, motor control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device capable of reducing wear of gears and noise.SOLUTION: A motor control device controls drive of a motor, and includes: target speed setting means for setting a target speed of the motor; control means for controlling the motor on the basis of a rotation speed and the target speed of the motor; and control gain setting means for setting, when the rotation speed reaches a reference speed at the start-up of the motor, at least one of a proportional gain and an integral gain that are used for control calculation of the control means, to a value larger than a value before the rotation speed reaches the reference speed.

Description

  The present invention relates to a motor control device, an image forming apparatus, a motor control method, and a program.

  For example, the image forming apparatus is provided with a plurality of motors that rotationally drive loads such as an image carrier and an intermediate transfer member. In the image forming apparatus, for example, a difference in surface linear velocity between the image carrier and the intermediate transfer member causes image quality deterioration, and thus each motor is controlled to be driven at a predetermined target speed (for example, Patent Document 1). reference).

  A plurality of gears are provided as a drive mechanism between the motor and the load, and as shown in FIG. 10, it is common to have a backlash BL between the tooth surfaces of the gears.

  For example, from the state shown in FIG. 10, when the motor is driven and the gear A is rotated in the direction of the arrow in the figure, the gear A rotates at an angle corresponding to the backlash BL and the gear A tooth surface becomes the gear B tooth surface. After the collision, gear B rotates with gear A. As described above, since the backlash BL is provided between the gears, there is a problem that the gears collide with each other before the load rotates when the motor is started, and the gears are worn and noise is generated.

  The present invention has been made in view of the above, and an object thereof is to provide a motor control device capable of reducing gear wear and noise.

  According to one aspect of the present invention, there is provided a motor control device that controls driving of a motor, the target speed setting means for setting a target speed of the motor, the rotation speed of the motor, and the target speed, A control means for controlling a motor; and when the rotational speed reaches a reference speed at the start of the motor, at least one of a proportional gain and an integral gain used for a control calculation of the control means, Control gain setting means for setting a value larger than before reaching the reference speed.

  According to the embodiment of the present invention, a motor control device capable of reducing gear wear and noise can be provided.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. 1 is a diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment. It is a figure which illustrates the function structure of the motor control part which concerns on embodiment. It is a figure which illustrates the flowchart of the motor starting process in embodiment. It is a figure which shows the example of a setting of the proportional gain and integral gain in embodiment. It is a figure which illustrates the measurement result of the rotational speed with respect to the target speed in embodiment. It is a figure which illustrates the measurement result of the rotational speed with respect to the target speed when not changing a control gain. It is a figure which illustrates the Bode diagram at the time of starting and steady driving in an embodiment. It is a figure which shows the other example of a setting of the proportional gain and integral gain in embodiment. It is a figure which illustrates backlash between gears.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<Configuration of image forming apparatus>
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus 200 according to the embodiment.

  As shown in FIG. 1, the image forming apparatus 200 includes an automatic document feeder (ADF) 140, an image reading unit 130, an image forming unit 110, a writing unit 120, and a paper feeding unit 150.

  The ADF 140 conveys the originals stacked on the original feeding table one by one onto the contact glass 11 of the image reading unit 130 and discharges them onto the paper discharge tray after the image data is read.

  The image reading unit 130 includes a contact glass 11 on which an original is placed, an exposure lamp 41, a first mirror 42, a second mirror 43, a third mirror 44, a lens 45, and a CCD 46. The exposure lamp 41, the first mirror 42, the second mirror 43, and the third mirror 44 scan the document while moving at a constant speed, and the reflected light from the document forms an image on the light receiving surface of the CCD 46 through the lens 45. And photoelectrically converted.

  The image data photoelectrically converted by the CCD 46 is A / D converted by an image processing circuit (not shown) and then subjected to various image processing (γ correction, color conversion, image separation, gradation correction, etc.) by the image processing circuit. The

  The writing unit 120 includes exposure devices 47y, 47m, 47c, and 47k that form electrostatic latent images of yellow (y), magenta (m), cyan (c), and black (k), respectively. When the user gives an instruction to copy an original image or prints an image as a printer, the writing unit 120 forms an electrostatic latent image corresponding to the image on the photosensitive drum for each color.

  In the image forming apparatus 200, four photoreceptor units 13y, 13m, 13c, and 13k on which toner images of respective colors are formed are arranged in parallel along the conveyance direction of the intermediate transfer belt 14. The photosensitive units 13y, 13m, 13c, and 13k include photosensitive drums 27y, 27m, 27c, and 27k, charging devices 48y, 48m, 48c, and 48k, developing devices 16y, 16m, 16c, and 16k, a cleaning device 49y, 49m, 49c, and 49k are provided, respectively. In the following description, the symbols y, m, c, and k representing colors are omitted.

  The exposure device 47 of the writing unit 120 performs exposure by, for example, an LED writing method including a light emitting diode (LED) array and a lens array. The exposure device 47 emits an LED according to the image data photoelectrically converted into each color, and forms an electrostatic latent image on the photosensitive drum 27.

  In the developing device 16, a developing roller that carries a developer and rotates supplies toner to the electrostatic latent image formed on the photosensitive drum 27, thereby forming a toner image of each color.

  Each color toner image formed on the photosensitive drum 27 is transferred onto the intermediate transfer belt 14 in a primary transfer position where the photosensitive drum 27 and the intermediate transfer belt 14 are in contact with each other.

  An intermediate transfer roller 26 is provided at a position facing the photosensitive drum 27 via the intermediate transfer belt 14. The intermediate transfer roller 26 is brought into contact with the inner peripheral surface of the intermediate transfer belt 14 to bring the intermediate transfer belt 14 into contact with the surface of each photoconductor. The intermediate transfer roller 26 is applied with a voltage, forms an intermediate transfer electric field for transferring the toner image on the photosensitive drum 27 to the intermediate transfer belt 14, and transfers the toner image onto the intermediate transfer belt 14. The toner images of the respective colors are superimposed and transferred, and a full color toner image is formed on the intermediate transfer belt 14.

  At the timing when the toner image formed on the intermediate transfer belt 14 reaches the position of the secondary transfer roller 18, the recording paper 53 reaches the secondary transfer position 50 between the secondary transfer roller 18 and the repulsive roller 17. The toner image is secondarily transferred to the recording paper 53.

The recording paper 53 is fed from any of the first tray 22a, the second tray 22b, the third tray 22c, and the fourth tray 22d. Each of the paper feed trays 22a to 22d feeds the recording paper 53 accommodated therein sequentially from the top, a paper feed roller 28, and separates the fed recording paper 53 and sends them out to the transport path 23. A separation roller 31 and a plurality of conveying roller pairs 29 are provided.

  The transport roller pair 29 sends the recording paper 53 transported from the paper feed tray 22 toward the transport roller pair 29 at the subsequent stage and the paper feed path 32 of the image forming unit 110. After the leading edge of the recording paper 53 fed into the paper feed path 32 is detected by the registration sensor 51, it is abutted against the registration roller 33 and stops once. The registration roller 33 feeds the sandwiched recording paper 53 to the secondary transfer position 50 at a predetermined timing. The predetermined timing is a timing at which the full color toner image formed on the intermediate transfer belt 14 is conveyed to the secondary transfer position 50.

  The full color toner image on the intermediate transfer belt 14 is transferred to the recording paper 53 at the secondary transfer position 50 between the secondary transfer roller 18 and the repulsive roller 17, and is conveyed to the fixing device 19 by the conveyance belt 24.

  The fixing device 19 includes a pressure roller 12 and a heating roller 25, and heats and presses the recording paper 53 to fix the full color toner image on the recording paper 53. The recording paper 53 on which the full color toner image is fixed by the fixing device 19 is discharged onto the paper discharge tray 21.

  The image forming apparatus 200 is exemplified by an image forming apparatus that forms an image on the recording paper 53 by an electrophotographic method, but the image is formed by another image forming method such as an ink jet method that forms an image by ejecting ink droplets. An image forming apparatus to be formed may be used.

<Hardware configuration of image forming apparatus>
FIG. 2 is a diagram illustrating a hardware configuration of the image forming apparatus 200 according to the embodiment.

  As shown in FIG. 2, the image forming apparatus 200 includes a controller 210, a scanner 220, a printer 230, a modem 240, an operation panel 250, a network I / F unit 260, a recording medium I / F unit 270, and a motor control unit 300. .

  The controller 210 includes a CPU 211, RAM 212, ROM 213, HDD 214, NVRAM 215, and the like. The ROM 213 stores various programs and data used by the programs. The RAM 212 is used as a storage area for loading a program, a work area for the loaded program, and the like. The CPU 211 realizes various functions by processing a program loaded in the RAM 212. The HDD 214 stores a program and various data used by the program. The NVRAM 215 stores various setting information and the like.

  The scanner 220 is hardware (image reading unit) for reading image data from a document. The printer 230 is hardware (image forming unit) for printing an image on a recording medium. The modem 240 is hardware for connecting to a telephone line, and is used to execute transmission / reception of image data by FAX communication. The operation panel 250 is hardware including an input unit such as a button for accepting input from a user, an operation screen such as a liquid crystal panel having a touch panel function, and the like.

  The network I / F unit 260 is hardware for connecting to a network such as a LAN (whether wired or wireless). The recording medium I / F unit 270 is an interface with the recording medium 271. The image forming apparatus 200 can read and / or write the recording medium 271 via the recording medium I / F unit 270. The recording medium 271 includes a flexible disk, a CD, a DVD (Digital Versatile Disk), an SD memory card, a USB memory (Universal Serial Bus memory), and the like.

  The motor control unit 300 is an example of a motor control device and controls driving of the motor 400. The motor 400 is, for example, a brushless DC motor or the like, and is provided in the image forming apparatus 200 to rotationally drive the photosensitive drum 27, the paper feed roller 28, the conveyance roller pair 29, and the like. The encoder 500 is a rotary encoder or the like, for example, and reads, for example, an optical sensor, slits carved in a code wheel provided in a drive mechanism constituted by a rotating shaft of the motor 400 or a plurality of gears. Outputs a pulse signal.

  The motor control unit 300 performs feedback control of the motor 400 by PID control based on the set target speed and the detection result of the encoder 500. Motor controller 300 may control motor 400 by PI control instead of PID control.

  The motor control unit 300 includes, for example, a CPU, a ROM, a RAM, and the like, and various functions of the motor control unit 300 are realized by reading a program recorded in the ROM or the like into the RAM and executing it by the CPU.

<Functional configuration of motor controller>
FIG. 3 is a diagram illustrating a functional configuration of the motor control unit 300 according to the embodiment.

  The motor control unit 300 includes a control gain setting unit 310, a target speed setting unit 320, a comparison calculation unit 330, a PID control calculation unit 340, a driver 350, and a signal processing unit 360.

  The control gain setting unit 310 sets control gains such as a proportional gain and an integral gain used for the control calculation in the PID control calculation unit 340 according to the driving state of the motor 400.

  The target speed setting unit 320 sets the target speed of the motor 400 at the time of start-up and in a steady driving state in which the rotational driving is performed at a constant speed.

  The comparison calculation unit 330 calculates a deviation between the target speed set by the target speed setting unit 320 and the actual rotation speed of the motor 400 obtained from the detection result of the encoder 500 by the signal processing unit 360.

  The PID control calculation unit 340 performs control calculation based on the control gain set by the control gain setting unit 310 from the deviation between the target speed of the motor 400 calculated by the comparison calculation unit 330 and the actual rotation speed. The PID control calculation unit 340 outputs to the driver 350 a PWM signal such that the deviation between the target speed of the motor 400 and the actual rotational speed is small.

  The driver 350 generates a drive current based on the PWM signal output from the PID control calculation unit 340, outputs the drive current to the motor 400, and rotates the motor 400.

  The signal processing unit 360 acquires the pulse signal output from the encoder 500 and calculates the actual rotational speed of the motor 400. The rotation speed of the motor 400 obtained by the signal processing unit 360 is output to the control gain setting unit 310 and the comparison calculation unit 330.

<Motor start-up process>
FIG. 4 illustrates a flowchart of the startup process of the motor control unit 300 when the motor 400 is started.

  First, in step S101, the target speed setting unit 320 sets a target speed from the start of driving of the motor 400 to the steady driving state. The target speed from when the motor 400 is started until it reaches the steady drive state is obtained by applying a second-order moving average filter to a step function that increases stepwise as time elapses. Set to increase the speed. Further, the target speed from the start to the steady drive state may be set based on, for example, a proportional function that increases with time.

  Next, in step S102, the control gain setting unit 310 sets a control gain used for the control calculation in the PID control calculation unit 340. For example, as shown in FIG. 5, the control gain setting unit 310 changes the control gain when the rotational speed of the motor 400 reaches the reference speed after activation. Specifically, when the rotational speed reaches the reference value after the motor 400 is started, the control gain setting unit 310 sets at least one of the proportional gain and the integral gain to a value larger than that before the rotational speed reaches the reference speed. Set to.

  In this embodiment, as shown in FIG. 5, until the rotational speed reaches the reference speed, the integral gain is set to zero, and when the rotational speed reaches the reference speed, the proportional gain and the integral gain are respectively set. Set a value larger than that until the rotation speed reaches the reference speed.

  In addition, the reference speed is set such that the motor 400 starts rotating, for example, a gear train between the motor 400 and a load connected to the motor 400 is rotated by the backlash BL or more, and the gears mesh with each other to connect to the motor 400. Set to the speed at which the load begins to rotate.

  At the start of the motor 400, the motor 400 rotates in an almost no-load state until the gear train rotates by the backlash BL or more and the gears mesh with each other. Therefore, when the motor 400 is started, if the motor 400 is controlled with the control gain set in the same manner as in the steady drive state, the output torque of the motor 400 is controlled to be larger than necessary. Therefore, when the motor 400 is started, the gears collide violently, causing problems such as gear wear and noise.

  Therefore, in this embodiment, as described above, at least one of the proportional gain and the integral gain is constantly driven until the rotational speed of the motor 400 reaches the reference speed at which the gear train meshes and the load starts to rotate. Set to a value smaller than the value in the state. With such a setting, it is possible to prevent an excessive torque from being output from the motor 400 in a no-load state before the gear train is engaged, reduce the impact caused by the collision between the gears, and cause problems such as gear wear and noise. Can be eliminated.

  Returning to the flowchart shown in FIG. 4, in step S <b> 103, the motor 400 is controlled and driven based on the proportional gain and integral gain set by the control gain setting unit 310. In step S <b> 104, a pulse signal corresponding to the rotation of the motor 400 is output from the encoder 500, the rotation speed of the motor 400 is calculated by the signal processing unit 360, and used for the control calculation by the PID control calculation unit 340.

  In step S105, the control gain setting unit 310 compares the rotational speed of the motor 400 with the reference speed. When the rotation speed has not reached the reference speed (step S105: No), the drive of the motor 400 is controlled based on the control gain that has been continuously set in step S103.

  When the rotation speed of the motor 400 reaches the reference speed (step S105: Yes), the control gain setting unit 310 changes the setting of the proportional gain and the integral gain as illustrated in FIG. 5 in step S106. . Specifically, the proportional gain and the integral gain are set to values larger than those until the rotation speed of the motor 400 reaches the reference speed. In step S107, based on the proportional gain and integral gain whose settings have been changed, the motor 400 is controlled so as to accelerate along the target speed and reach a steady driving state in which the motor 400 rotates at a constant speed.

  FIG. 6 is a diagram illustrating measurement results of the set target speed and the rotation speed of the motor 400 when the motor 400 is started.

  In the present embodiment, as shown in FIG. 6, the target speed is accelerated in an S shape from the start to the target steady speed based on a step function to which a second-order moving average filter is applied. Is set.

  The control gain setting unit 310 sets the proportional gain and the integral gain to smaller values than after reaching the reference speed until, for example, the reference speed set to 200 [pps] is reached. The output torque is reduced. Such control makes it possible to reduce the impact caused by the collision of gears caused by the backlash BL when the motor 400 is started. Further, as shown in FIG. 6, the rotation speed of the motor 400 can be controlled to accelerate following the target speed.

  FIG. 7 is a diagram illustrating the detection result of the rotational speed of the motor 400 when the control gain is not changed before and after the reference speed but is also controlled at the time of starting with the control gain in the steady driving state where the driving is performed at a constant rotational speed. It is. The target speed of the motor 400 is set as in the present embodiment (FIG. 6).

  When the control gain is not changed, when the motor 400 is started, control is performed so that the output torque of the motor 400 becomes larger than necessary in the no-load state before the gear rotates for the backlash BL and actually engages. The Therefore, as shown in FIG. 7, immediately after startup, the rotational speed of the motor 400 becomes oscillating with respect to the target speed, and the control is unstable.

  On the other hand, in this embodiment, as illustrated in FIG. 6, even immediately after startup, the rotational speed of the motor 400 follows the target speed without exhibiting vibrational behavior, and the motor 400 is stably controlled. I understand that. In this embodiment, as can be seen from the Bode diagram of the motor 400 illustrated in FIG. 8 when the motor 400 is started and in the steady driving state, the gain crossover frequency at the time of starting is lower than that in the steady driving state, and the motor 400 is stably controlled. It is possible to do.

  The motor control unit 300 according to the present embodiment changes the control gain before and after a reference speed at which the gears mesh with each other and the load starts to rotate when the motor 400 is started. The control gain setting unit 310 sets at least one of the proportional gain and the integral gain to be smaller than that in the steady driving state until the rotational speed of the motor 400 reaches the reference speed. With such a setting, it is possible to prevent the output torque of the motor 400 from becoming unnecessarily large before the gears mesh with each other at the start and the load starts to rotate. Therefore, it is possible to reduce the noise generated by the violent collision between the gears in the drive mechanism between the motor 400 and the load, and to reduce the wear of the gears, thereby extending the life of the motor 400 and the drive mechanism. It becomes possible. In addition, since the output voltage from the motor control unit 300 to the motor 400 becomes small at the time of startup, the power consumption by the motor 400 can be reduced.

  Further, the control gain setting unit 310 may set the proportional gain and the integral gain in accordance with the rotation speed of the motor 400 as shown in FIGS. 9A to 9E, for example.

  For example, in the example shown in FIG. 9A, the control gain setting unit 310 sets the proportional gain to zero until the rotational speed of the motor 400 reaches the reference speed. Further, after the rotation speed of the motor 400 reaches the reference speed, the proportional gain and the integral gain are set to values larger than those until the rotation speed of the motor 400 reaches the reference speed.

  In the example shown in FIG. 9B, the control gain setting unit 310 sets both the proportional gain and the integral gain so that the speed after the rotation speed of the motor 400 becomes larger than before the motor speed reaches the reference speed.

  In the example shown in FIG. 9C, the control gain setting unit 310 sets the proportional gain to a negative value until the rotational speed of the motor 400 reaches the reference speed. Further, after the rotational speed of the motor 400 reaches the reference speed, the proportional gain is set to a positive value, and the integral gain is set to a value smaller than that until the rotational speed of the motor 400 reaches the reference speed. .

  In the example shown in FIG. 9D, the control gain setting unit 310 sets the integral gain to zero until the rotational speed of the motor 400 reaches the reference speed, and the proportional gain increases as the rotational speed increases. Set based on proportional function. Further, after the rotation speed of the motor 400 reaches the reference speed, the proportional gain and the integral gain are set to values larger than those until the rotation speed of the motor 400 reaches the reference speed.

  In the example shown in FIG. 9E, the control gain setting unit 310 sets the integral gain to zero until the rotational speed of the motor 400 reaches the reference speed, and the proportional gain increases as the rotational speed increases. Set based on step function. Further, after the rotation speed of the motor 400 reaches the reference speed, the proportional gain and the integral gain are set to values larger than those until the rotation speed of the motor 400 reaches the reference speed.

  In any of the cases illustrated in FIGS. 9A to 9E, as in the above embodiment, the output of the motor 400 until the gears of the drive mechanism are rotated by the backlash BL and engaged with each other when the motor 400 is started. Torque can be reduced. By reducing the output torque of the motor 400, it is possible to reduce the impact caused by the collision between the gears and to prevent gear wear and noise. In addition, since the output voltage from the motor control unit 300 to the motor 400 becomes small at the time of startup, the power consumption by the motor 400 can be reduced.

  In this embodiment, when the rotational speed of the motor 400 reaches the reference speed, the control gain setting unit 310 changes the control gain. However, the control gain is changed based on the rotational position or the rotational distance of the motor 400. You may do it. For example, a reference rotation position or a reference rotation distance of the motor 400 that is considered that the rotation speed of the motor 400 reaches the reference speed is stored in advance, and when the rotation position of the motor 400 reaches the reference rotation position or the rotation distance is the reference rotation distance. When the value reaches the control gain, the control gain may be changed.

  The motor control device, the image forming apparatus, the motor control method, and the program according to the embodiments have been described above. However, the present invention is not limited to the above embodiments, and various modifications and improvements can be made within the scope of the present invention. Is possible.

200 Image forming apparatus 300 Motor control unit (motor control apparatus)
310 Control gain setting unit (control means setting means)
320 Target speed setting unit (target speed setting means)
340 PID control calculation unit (control means)
400 Motor 500 Encoder

JP 2005-114714 A

Claims (12)

A motor control device for controlling driving of a motor,
Target speed setting means for setting a target speed of the motor;
Control means for controlling the motor based on the rotational speed of the motor and the target speed;
When the rotation speed reaches a reference speed at the start of the motor, at least one of the proportional gain and the integral gain used for the control calculation of the control means is larger than before the rotation speed reaches the reference speed. Control gain setting means for setting the value,
A motor control device comprising: The control gain setting means sets the proportional gain and the integral gain to values larger than before the rotational speed reaches the reference speed when the rotational speed reaches the reference speed. The motor control device according to claim 1. The control gain setting means sets one of the proportional gain and the integral gain to zero until the rotation speed reaches the reference speed. Motor control device. The control gain setting means sets the integral gain to zero until the rotational speed reaches the reference speed, and based on a proportional function or step function that increases the proportional gain as the rotational speed increases. The motor control device according to claim 3, wherein the motor control device is set. The control gain setting means sets the proportional gain to a negative value until the rotation speed reaches the reference speed, and sets the proportional gain to a positive value when the rotation speed reaches the reference speed. The motor control device according to claim 1, wherein the motor control device is set to a value, and the integral gain is set to a value smaller than that before the rotation speed reaches the reference speed. 6. The target speed setting means sets the target speed from the start of the motor to a target steady speed based on a proportional function that increases with the passage of time. The motor control apparatus as described in any one. The target speed setting means sets the target speed from the start of the motor to the target steady speed by applying a moving average filter to a step function that increases stepwise with time. The motor control device according to any one of claims 1 to 5. A motor control device for controlling driving of a motor,
Target speed setting means for setting a target speed of the motor;
Control means for controlling the motor based on the rotational position of the motor and the target speed;
At the time of starting the motor, when the rotational position reaches the reference rotational position, at least one of the proportional gain and the integral gain used for the control calculation of the control means is determined from before the rotational position reaches the reference rotational position. Control gain setting means for setting a larger value,
A motor control device comprising: A motor control device for controlling driving of a motor,
Target speed setting means for setting a target speed of the motor;
Control means for controlling the motor based on the rotational distance of the motor and the target speed;
When the rotation distance reaches the reference rotation distance at the start of the motor, at least one of the proportional gain and the integral gain used for the control calculation of the control means is compared with before the rotation distance reaches the reference rotation distance. Control gain setting means for setting a larger value,
A motor control device comprising:   An image forming apparatus comprising the motor control device according to claim 1. A motor control method for controlling drive of a motor,
A speed detecting step for detecting the rotational speed of the motor;
A target speed setting step for setting a target speed of the motor;
A control step of controlling the motor based on the rotational speed and the target speed;
When the rotation speed reaches the reference speed at the start of the motor, at least one of the proportional gain and the integral gain used for the control calculation of the control step is larger than before the rotation speed reaches the reference speed. Control gain setting step to set the value,
A motor control method characterized by comprising:   A program for causing a computer to execute the motor control method according to claim 11.

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