JP2014207773A - Motor control device, image forming apparatus, and motor control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device that can reliably stop a motor driven in an overload state.SOLUTION: A motor control device includes control means for feedback-controlling a motor to output a control voltage value, driving means for outputting a drive voltage on the basis of the control voltage value to drive the motor, restriction detection means for blocking the output of the drive voltage from the driving means to the motor when detecting a restriction state of the motor, and limiting means for limiting, when the control voltage value continues to be equal to or higher than a threshold over a prescribed time, the control voltage value output from the control means to be a control upper limit value in which the motor is not rotated and is lower than the threshold.

Description

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

  For example, in a configuration in which a load is driven by a motor, when an abnormality occurs in the load and the motor enters an overload state, an excessive current may flow through the motor, resulting in failure due to heat generation or the like.

  Therefore, a technique for protecting the motor by comparing the motor current detected during driving with the stored normal motor current and stopping the motor when an overload condition is detected is disclosed. (For example, refer to Patent Document 1).

  However, when the overload state is determined based on the detection result of the motor current and the motor is stopped by software control such as a program, the control may run away after the stop and the motor may start to rotate again in the overload state There is sex.

  The present invention has been made in view of the above, and an object thereof is to provide a motor control device capable of reliably stopping a motor driven in an overload state.

  According to the motor control device of one aspect of the present invention, a control unit that feedback-controls the motor and outputs a control voltage value; a drive unit that outputs a drive voltage based on the control voltage value and drives the motor; , When detecting the restraint state of the motor, the restraint detection means for cutting off the output of the drive voltage from the drive means to the motor, and when the state where the control voltage value is equal to or greater than a threshold value has passed for a certain period of time, Limiting means for limiting the control voltage value output from the control means to a control upper limit value that is lower than the threshold and does not rotate the motor.

  According to the embodiment of the present invention, it is possible to provide a motor control device capable of reliably stopping a motor driven in an overload state.

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 apparatus which concerns on embodiment. It is a figure which illustrates the control voltage value at the time of the motor drive in embodiment, a motor coil electric current, and a motor rotational speed. It is a figure which illustrates the flowchart of the overload detection process in embodiment.

  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 feeder on the contact glass 11 of the image reading unit 130 one by one, and discharges them onto the paper output tray after reading the image data.

  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.

  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 device 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 device 300 controls driving of a DC motor (hereinafter referred to as “DCM”) 400. The DCM 400 is, for example, a brushless DC motor or the like, and is provided in the image forming apparatus 200 for rotationally driving the photosensitive drum 27, the paper feed roller 28, the transport roller pair 29, and the like. The encoder 500 is, for example, a rotary encoder or the like, and pulses obtained by reading slits carved in a code wheel provided in a drive mechanism constituted by a rotating shaft of the DCM 400 or a plurality of gears at a predetermined angular interval, for example, with an optical sensor. Is output.

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

<Configuration of motor control device>
FIG. 3 is a diagram illustrating a functional configuration of the motor control device according to the embodiment.

  As shown in FIG. 3, the motor control device 300 includes a motor control unit 310 and a motor driver 320. The motor control unit 310 includes a motor controller 311 and an overload detection unit 312, and the motor driver 320 includes a drive unit 321 and a constraint detection unit 322. The motor control device 300 includes, for example, a CPU, a ROM, a RAM, and the like, and various functions of the motor control device 300 are realized by reading a program recorded in the ROM or the like into the RAM and executing it by the CPU.

  The motor controller 311 outputs a control voltage value to the motor driver 320 based on the rotational position or target speed of the DCM 400 detected by the encoder 500 and the target position or target speed of the DCM 400 input from the outside. The motor controller 311 performs, for example, PID control calculation based on the deviation between the rotational position and the target position detected by the encoder 500 or the deviation between the rotational speed and the target speed, and outputs a control voltage value. Perform feedback control.

  The motor controller 311 outputs, for example, the duty ratio of the PWM signal to the drive unit 321 as the control voltage value. The drive unit 321 generates a drive voltage subjected to pulse width modulation based on the duty ratio of the PWM signal output from the motor controller 311, and applies the generated drive voltage to the DCM 400 for driving.

  The overload detection unit 312 acquires the control voltage value output from the motor controller 311 and detects this when the DCM 400 is in an overload state. For example, the overload detection unit 312 determines that the DCM 400 is in an overload state when a certain time elapses when the acquired control voltage value is equal to or greater than the control threshold. When the overload detection unit 312 detects that the DCM 400 is in an overload state, the overload detection unit 312 limits the control voltage value output from the motor controller 311 to a control upper limit value that is lower than the control threshold and does not rotate the motor.

  The control threshold is appropriately set according to conditions such as the DCM 400 used and the load so that it can be detected that the DCM 400 is overloaded based on the control voltage value. Further, the control upper limit value is lower than the above-described control threshold value, and is set in a range where a voltage is applied and the motor coil current of DCM 400 does not become zero.

  After the overload detection unit 312 limits the control voltage value to the control upper limit value, the motor controller 311 does not output a control voltage value that is equal to or higher than the control upper limit value. It becomes a restraint state that can not be.

  The constraint detection unit 322 detects whether the DCM 400 is in a constraint state based on the motor coil current of the DCM 400 and the driving state of the DCM 400. The restraint detection unit 322 blocks the drive voltage output from the drive unit 321 to the DCM 400 when the DCM 400 is restrained and a predetermined time or more has elapsed. When the driving voltage from the driving unit 321 is cut off, the DCM 400 is completely stopped without being applied with the driving voltage.

<Motor control>
FIG. 4 is a diagram illustrating a control voltage value, a motor coil current, and a motor rotation speed when the motor is driven in the embodiment. In each graph illustrated in FIG. 4, the upper stage represents the control voltage value, the middle stage represents the motor coil current, and the lower stage represents the change in the motor rotation speed.

  As shown in FIG. 4, when DCM 400 is controlled by motor controller 300 at time T0 and driving is started, the control voltage value rises so that DCM 400 accelerates to the target speed, and DCM 400 drives according to the control voltage value. A voltage is applied to drive. At this time, along with the control voltage value, the motor coil current of DCM 400 and the motor rotation speed also increase.

  In the example illustrated in FIG. 4, after the DCM 400 accelerates, the control voltage value reaches the control threshold at time T <b> 1, and the DCM 400 enters an overload state. The overload detection unit 312 of the motor control unit 310 detects that the DCM 400 is driven in an overload state because the control voltage value is equal to or greater than the control threshold value. The overload detection unit 312 limits the control voltage value output from the motor controller 311 to the control upper limit value at time T2 when the overload state has elapsed for a predetermined time from time T1. Note that the predetermined elapsed time from the time T1 to the time T2 is appropriately set according to the conditions of the DCM 400, the load driven by the DCM 400, and the like.

  When the control voltage value output from the motor controller 311 is limited to the control upper limit value, the motor coil current of the DCM 400 decreases and becomes a constant value (> 0) corresponding to the control upper limit value. Further, since the motor coil current is reduced, the DCM 400 cannot drive the load and stops rotating (motor rotation speed = 0). That is, DCM 400 is in a restrained state in which motor coil current flows at time T2 but cannot rotate.

  Here, the constraint detection unit 322 of the motor driver 320 detects that the DCM 400 is in a constraint state based on the motor coil current of the DCM 400 and the motor rotation speed. The restraint detection unit 322 blocks the control voltage output from the drive unit 321 to the DCM 400 at a time T3 when the restraint state of the DCM 400 has elapsed for a fixed time.

  After time T3, the motor controller 311 continues to output a control voltage value limited to the control upper limit value. However, since the control voltage from the drive unit 321 to the DCM is cut off by the constraint detection unit 322, the motor coil current Becomes zero. Further, the DCM 400 is not applied with a drive voltage, and the motor coil current is zero, and the DCM 400 is completely stopped.

  In this manner, the overload detection unit 312 limits the control voltage value output from the motor controller 311 to the control upper limit value when the DCM 400 is driven for a predetermined time in an overload state. When the control voltage value is limited, the DCM 400 enters a restraint state, and the restraint detection unit 322 detects the restraint state and cuts off the control voltage from the drive unit 321 to the DCM 400. Therefore, the motor control device 300 can reliably stop the DCM 400 that is driven in an overload state.

  FIG. 5 is a diagram illustrating a flowchart of overload detection processing in the motor control device 300 according to the embodiment.

  As shown in FIG. 5, during the drive control of the DCM 400, first, in step S <b> 101, the overload detection unit 312 acquires a control voltage value output from the motor controller 311.

  In step S102, the control voltage value acquired by the overload detection unit 312 is compared with the control threshold value. If the control voltage value is less than the control threshold value (step S102: No), in step S107, the overload time counter that counts the time during which the DCM 400 is in the overload state is cleared, and the process ends.

  If the control voltage value is greater than or equal to the control threshold (step S102: Yes), the overload detection unit 312 adds “1” to the overload time counter in step S103. In step S104, the overload detection unit 312 compares the value of the overload time counter with a predetermined elapsed time set in advance.

  If the overload time counter is less than the predetermined elapsed time (step S104: No), the process is terminated as it is.

  If the overload time counter is equal to or longer than the predetermined elapsed time (step S104: Yes), the overload detection unit 312 sets a control upper limit value for the control voltage value output from the motor controller 311 in step S105.

  Next, in step S106, the overload detection unit 312 sets the overload abnormality flag to “ON”. For example, the external device of the motor control device 300 can confirm the overload abnormality flag, and can notify the user of an overload state and record an abnormality history.

  Subsequently, in step S107, after the overload detection unit 312 clears the overload time counter, the process ends.

  The overload detection unit 312 executes the above-described overload detection process at a cycle of, for example, 1 msec, and sets a control upper limit value in the motor controller 311 when the overload state of the DCM 400 is detected.

  After the overload detection unit 312 sets the control upper limit value in the motor controller 311, the DCM 400 is in a constraint state, and the constraint detection unit 322 detects the constraint state of the DCM 400 and cuts off the control voltage from the drive unit 321 to the DCM 400. To do. Therefore, the DCM 400 stops without being driven in an overloaded state.

  As described above, in the motor control device 300 according to the embodiment, the overload detection unit 312 compares the control voltage value output from the motor controller 311 with the control threshold value that the DCM 400 is in an overload state. Detect based on. When the overload detection unit 312 detects that the DCM 400 is in an overload state, the overload detection unit 312 restricts the control voltage value output from the motor controller 311 to the control upper limit value, thereby placing the DCM 400 in a restrained state. When the restraint detection unit 322 of the motor driver 320 detects the restraint state of the DCM 400, the restraint detection unit 322 stops the DCM 400 by cutting off the drive voltage from the drive unit 321 to the DCM 400. Since the restraint detection unit 322 cuts off the drive voltage from the drive unit 321 to the DCM 400 in hardware, the control program of the motor control device 300 runs out of control, and the DCM 400 is driven again in an overload state to cause a malfunction or the like. It does not lead to.

  Up to this point, the present invention has been described based on the above embodiment, but the function of the motor control device 300 according to the above embodiment is the same as that of each processing procedure described above according to the motor control according to the above embodiment. This can be realized by executing on a computer as a program coded in a programming language suitable for the apparatus 300. Therefore, the program for realizing the motor control device 300 according to the above embodiment can be stored in a computer-readable recording medium.

  Therefore, the program according to the above embodiment is stored in a recording medium such as a floppy (registered trademark) disk, a CD (Compact Disc), a DVD (Digital Versatile Disk), and the like, and from these recording media to the motor control device 300. Can be installed. The motor control device 300 can also download and install a program via an electric communication line such as the Internet.

  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 controller 310 Motor controller 311 Motor controller (control means)
312 Overload detection unit (limitation means)
320 Motor driver 321 Drive unit (drive means)
322 Constraint detection unit (Constraint detection means)
400 DCM (motor)
500 Encoder (Rotation detection means)

JP 2006-307471 A

Claims (6)

Control means for feedback-controlling the motor and outputting a control voltage value;
Driving means for driving the motor by outputting a driving voltage based on the control voltage value;
Constraint detection means for cutting off the output of drive voltage from the drive means to the motor when detecting the constraint state of the motor;
Limiting means for limiting the control voltage value output from the control means to a control upper limit value that is lower than the threshold value and does not rotate the motor when a state where the control voltage value is equal to or greater than a threshold value has elapsed for a certain period of time;
A motor control device comprising: Having rotation detection means for detecting the rotation position or rotation speed of the motor;
The motor control apparatus according to claim 1, wherein the control unit performs feedback control of the motor based on a deviation between a target position and the rotational position or a deviation between a target speed and the rotational speed.   The motor control apparatus according to claim 1, wherein the control unit outputs a duty ratio of a PWM signal.   An image forming apparatus comprising the motor control device according to claim 1. Control means for feedback-controlling the motor and outputting a control voltage value;
Driving means for driving the motor by outputting a driving voltage based on the control voltage value;
Constraint detection means for cutting off the output of drive voltage from the drive means to the motor when detecting the constraint state of the motor;
A motor control method in a motor control device having:
A limiting step of limiting the control voltage value output from the control means to a control upper limit value that is lower than the threshold value and does not rotate the motor when a state in which the control voltage value is equal to or greater than a threshold value has elapsed for a certain period of time; The motor control method characterized by the above-mentioned.   A program for causing a computer to execute the motor control method according to claim 5.

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