JP2008161028A - Motor drive control method and sheet postprocessing device controlled therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive control method capable of facilitating the waveform correction of a driving signal in microstep control and of reducing the vibration of a stepping motor, and a sheet postprocessing device controlled therewith. <P>SOLUTION: A finisher controlled with the motor drive control method variably controls the time of a clock signal 8, input into a motor driver IC 5, for controlling the switching of each of a plurality of steps divided by microstep control. Accordingly, the rotational speed of each step is corrected to be kept constant, thereby facilitating suppression of the vibration of the stepping motor used in the sheet carrier parts of the finisher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor drive control method using microstep control in which a stepping motor is rotationally driven at a division step angle finer than a normal step angle, and a sheet post-processing apparatus controlled by the control method.

  In recent years, demand for products compatible with both color and black-and-white is increasing in copying machines and network multifunction peripherals, and color and black-and-white printing speeds are different, and the difference is gradually widening. Therefore, in a finisher (sheet post-processing apparatus) attached to this, it is necessary to convey and process paper (sheet) corresponding to a wide print speed difference. Conventionally, when a stepping motor has been used to drive the finisher transport unit, the motor or drive is used at the lower transport speed when the motor drive conditions, reduction ratio, etc. are adjusted to accommodate the higher transport speed. There is a problem that the part vibrates and generates noise.

  In order to reduce such vibrations during low-speed conveyance, microstep control (microstep drive) is used in which the normal step angle (step angle) determined by the motor structure is rotated by a fine step angle. It has been. This microstep control divides the unique step angle determined by the structure of the stepping motor into a plurality of parts, gradually changes the motor drive current value step by step, and approximates the current waveform to a sine wave, It is generally used as a technique for reducing vibration and noise by generating a uniform motor torque by rotating a stepping motor more smoothly.

  However, in the type of stepping motor that has a permanent magnet inside that is generally used at present, the permanent magnet has a holding force, and the cogging torque (detent torque) generated due to this holding force. As a result, the torque generated is not uniform even if microstep driving is performed.

  Therefore, as shown in FIG. 10, the stop position of the motor rotation shaft should theoretically stop at an interval of angle θ, but in reality, the rotation angle differs every time as angles θ1 to θ3. When operated continuously, the angular velocity of rotation becomes uneven, which causes vibration. In view of this, there has been proposed a method of correcting the drive current value so as to cancel the cogging torque generated in advance by open loop control (see Patent Document 1).

  The mini-step driving device disclosed in Patent Document 1 finely changes the magnitude of each phase excitation signal of the stepping motor, gradually moves the position of the stable point, refines the step angle, and the amount of rotation per pulse. The excitation signal is corrected in accordance with the motor characteristics so as to be uniform. The mini-step drive device further includes a forward correction table for correcting the excitation signal during motor forward rotation and a reverse correction table for correcting the excitation signal during motor reverse rotation. It is configured to perform excitation signal correction independent of time.

JP-A-01-218393

  FIG. 9 shows a drive current waveform of a drive signal when 2W1-2 phase excitation drive is performed using a commercially available clock input type microstepping motor driver. As shown in the figure, in the case of a clock input type motor driver, a current value of a ratio already determined in the motor driver is output according to the input clock. For this reason, it can be understood that it is not easy to correct the current value of the drive signal in accordance with the characteristics of the stepping motor as in the mini-step drive device described in Patent Document 1.

  The present invention has been made in view of the above circumstances, and facilitates correction of the waveform of a drive signal in microstep control and can reduce vibration of a stepping motor and control by the control method. An object of the present invention is to provide a sheet post-processing apparatus.

  The present invention relates to a driving signal for the stepping motor used in a motor drive control method using microstep control in which a stepping motor is rotationally driven at a divided step angle that is finer than a specific step angle determined by its structure. A correction time width of one pulse is previously stored in a data table as time ratio data, and the stepping motor is driven to rotate while correcting the drive signal for each pulse based on the stored time ratio data. Yes.

  In the present invention, the correction time width of one pulse of the driving signal of the stepping motor to be used is stored in advance in the data table as time ratio data. Then, the stepping motor is driven to rotate while correcting the drive signal for each pulse based on the stored time ratio data. Thereby, the waveform correction of the drive signal in the microstep control can be facilitated, and the stepping motor can be smoothly rotated to reduce vibration during rotation.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The present embodiment relates to a motor drive control method using microstep control in which a stepping motor is rotationally driven at a divided step angle that is finer than an inherent step angle determined by its structure. This motor drive control method is applied to a finisher (sheet post-processing apparatus). FIG. 1 is a block diagram showing a control system in the embodiment according to the present invention.

  As shown in FIG. 1, the control system includes a motor control unit 1 that transmits a control signal, a motor driver IC 5 that determines a current value to be input to the stepping motor 6 in accordance with the control signal and sends a drive current, and rotates by the drive current And a stepping motor 6 to be driven. The control system further includes a sensor 7 that is required when the below-described control method is applied to the finisher.

  The motor control unit 1 includes a ROM (Read Only Memory) 3 that stores a data table related to a clock signal. Further, the motor control unit 1 includes a CPU (Central Processing Unit) 2 that performs the control shown in the flowchart of FIG. 2 in accordance with a control program stored in the ROM 3. The CPU 2 has a built-in timer unit 4 that measures the time ratio between each pulse of the clock signal (drive signal) and the sequence time, and sends the measurement result to the motor driver IC 5 as a measurement signal (clock signal) 8. Has been.

  Conventionally, a signal having a constant time interval has been used as a clock signal to the stepping motor. For this reason, when the motor driver IC 5 is driven by 2W1-2 phase excitation, the step angle is divided into 8 divisions, so that the motor driver IC 5 is synchronized with the input clock signal from the reference current value defined in the motor driver IC. According to the ratio, a drive current waveform having a uniform current value switching time was output (FIG. 9).

  However, in general, the stepping motor does not have uniform rotation stop positions due to the cogging torque characteristics of the motor itself. This cogging torque characteristic has periodicity for every 90 ° electrical angle of the stepping motor (one step of the rotation angle motor). For this reason, in the present embodiment, the above-described uniform drive current waveform is corrected by using a data table described later. Regarding the setting of this data table, the following methods can be mentioned.

  That is, in this method, the actual stop angle for each pulse of the drive signal based on the excitation method of the stepping motor to be used is measured in advance, and the deviation angle between the actual stop angle and the theoretical stop angle is calculated. Further, the correction time width of one pulse of the drive signal to be corrected for each divided step angle based on the calculated deviation angle is stored in advance in the data table as time ratio data. Then, based on the stored time ratio data, the stepping motor is driven to rotate while correcting the time for each pulse of the drive signal.

Specifically, the actual stop angle of the stepping motor 6 is measured in advance for each division number of 1 pulse determined by the excitation method to be used. Here, the step angle is θ, the number of divisions of the step angle θ at an electrical angle of 90 ° is n (see FIG. 6), the number of steps is T, the measurement angle is θ ( _T ), and the theoretical stop angle is θ (n). . Based on the measured (calculated) deviation angle caused by the cogging torque, the deviation angle ratio for each electrical angle of 90 ° is calculated by the following equation.

That is, when the deviation angle is θh (n), the deviation angle θh (n) is
θh (n) = θ ( _T ) −θ (n)
It becomes. When the deviation angle ratio is P (n), the deviation angle ratio P (n) is
P (n) = θh (n) / θ (n)
It becomes.

  Then, the deviation of the calculated ratio sum P is corrected by the following equations (1) and (2) to calculate a corrected deviation angle ratio Pθ (n).

  Pθ (n) = P (n) / P (2)

Further, based on the obtained correction deviation angle ratio Pθ (n), the correction time width T (n) for each division step of the clock signal (drive signal) is calculated by the following equation:
T (n) = nPθ (n)
Calculate as

  The calculated correction time width T (n) for each division step is stored as time ratio data in a data table (see FIG. 3) described later, and the drive signal is corrected for each pulse based on the time ratio data. At the same time, the stepping motor 6 is controlled to rotate.

  FIG. 2 is a flowchart showing a motor control program controlled by CPU 2 of motor control unit 1 in the present embodiment.

  That is, when control starting with the label of the motor control program is started, in step S1, the CPU 2 reads a clock signal data table (not shown) stored in the ROM 3 in accordance with the program.

  In step S2, the CPU 2 writes the table data read from the table data in the built-in timer unit 4. Furthermore, when the timer counts up in step S3, the timer unit 4 outputs the clock signal 8 in step S4. In step S5, the CPU 2 slides the data table shown in FIG. 3 downward by one, and returns to step 1 again.

  FIG. 3 is a diagram schematically showing an example of a data table in which the correction time width T (n) for each division step in the clock signal (drive signal) 8 used in this embodiment is stored as time ratio data. . FIG. 4 is a diagram showing the relationship between the data table and the drive current waveform of the clock signal 8.

As shown in FIG. 3, the data table includes n pieces of time ratio data for each step divided into a plurality according to the excitation method to be used (that is, t ₁ , t ₂ , t ₃ ... T ( _n ). ) Is stored. The CPU 2 reads this data, writes it into the timer unit 4, and measures the clock signal. Thus, the drive signal is corrected for each pulse based on the time ratio data, and the stepping motor 6 is rotationally driven.

  FIG. 5 is a diagram illustrating an example of a timing chart of a motor drive current waveform when 2W1-2 phase excitation control is executed by the control system of the present embodiment.

  As shown in FIG. 5, the step of the drive current (output current) is switched in synchronization with each rising edge of the clock signal 8 output from the motor control unit 1. The clock signal switching time between each step is variably controlled using the table data in FIG. 3 to correct the motor drive current waveform so that it can be smoothly driven while maintaining the speed of each step constant. can do.

  Here, a finisher (sheet post-processing apparatus) that includes the sheet conveying unit including the above-described stepping motor 6 as the stepping motor 12 and is controlled by the above-described motor drive control method will be described. FIG. 7 is a schematic cross-sectional view when the motor drive control method of the present embodiment is applied to a finisher.

  The finisher has a finisher main body 9. The finisher main body 9 transports a recording paper (sheet) sent from a copying machine (not shown) inside the finisher and a recording path. It has a conveyance roller pair 11 for conveyance. Further, the finisher body 9 is actuated by this control method to drive a pair of conveying rollers 11, a paper path sensor 13 that detects a recording sheet fed from a copying machine and generates a motor-driven trigger, and a conveyance And a paper discharge tray 14 for collecting the recorded paper. The transport path 10, transport roller pair 11 and stepping motor 12 constitute a sheet transport section.

  FIG. 8 is a flowchart of a paper conveyance program when the recording paper is conveyed in the finisher. That is, when the recording paper enters and the paper path sensor 13 is turned on in step S11, motor control for the stepping motor 12 is started in step S12, and the stepping motor 12 is driven to rotate by the motor control program.

  In step S13, the trailing edge of the recording paper passes through the paper path sensor 13, and when the sensor 13 is turned OFF, in step S14, a preset sequence timer is transferred to the timer unit 4 (see FIG. 1). set. This sequence timer is the time from when the trailing edge of the recording paper passes through the sensor 13 until it completely leaves the conveying roller pair 11.

  Further, when the count of the sequence timer is incremented in step S15, the motor control program is terminated and the stepping motor 12 is stopped in step S16.

  As described above, in the motor drive control method of this embodiment and the finisher controlled by the control method, the clock that is input to the motor driver IC 5 and controls switching of each step divided into a plurality of steps by microstep control. The time of the signal 8 is variably controlled. As a result, the rotational speed of each step is corrected so as to be kept constant, and for example, vibration of the stepping motor 12 used in the sheet conveying unit of the finisher can be easily reduced. That is, the waveform of the drive current can be corrected by a simple method while using the clock input type microstepping stepping motor driver IC (motor driver IC5), thereby reducing the vibration of the stepping motors 6 and 12. be able to.

It is a control block diagram in an embodiment according to the present invention. It is a flowchart which shows the motor control program in this Embodiment. It is a figure which shows an example of the data table in this Embodiment. It is a conceptual diagram which shows the relationship between a drive current waveform and the time data of a data table. It is a timing chart at the time of performing 2W1-2 phase excitation drive using the clock input system motor driver IC by this motor drive control method. It is a figure which shows the relationship between the division | segmentation of a clock signal by this motor drive control method, and an electrical angle. It is a schematic sectional drawing at the time of applying this motor drive control method to a finisher. It is a flowchart of the paper conveyance program at the time of conveying a recording paper in the finisher of FIG. It is a timing chart at the time of performing 2W1-2 phase excitation drive using the stepping motor driver IC for clock input system microsteps. It is a conceptual diagram of the stop position shift by the influence of the cogging torque of a stepping motor.

Explanation of symbols

1 Motor control unit 2 CPU
3 ROM
4 Timer unit 5 Motor driver IC
6 Stepping motor 7 Sensor 8 Drive signal (clock signal)
9 Sheet post-processing equipment (finisher body)
10, 11, 12 Sheet conveying unit (conveying path, conveying roller pair, stepping motor)
13 Paper path sensor 14 Output tray

Claims (3)

In a motor drive control method using microstep control in which a stepping motor is rotationally driven at a divided step angle finely divided from an inherent step angle determined by its structure,
The correction time width of one pulse of the driving signal of the stepping motor to be used is stored in the data table in advance as time ratio data,
Rotating the stepping motor while correcting the drive signal for each pulse based on the stored time ratio data;
The motor drive control method characterized by the above-mentioned. The actual stop angle for each pulse of the drive signal should be measured in advance, the shift angle between the actual stop angle and the theoretical stop angle should be calculated, and correction should be made for each division step angle based on the calculated shift angle. The correction time width of the drive signal 1 pulse is calculated,
The motor drive control method according to claim 1. A sheet post-processing apparatus including a sheet conveying unit having the stepping motor,
The sheet conveyance unit is controlled by the motor drive control method according to claim 1 or 2.
A sheet post-processing apparatus.

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