JP2002010690A - Motor-driving unit and drive-control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driving unit and a drive-control method that materializes a smooth and proper operation at every time. SOLUTION: There are contained a clock-generation means 32 that generates a clock for driving a stepping motor 21, a driving means 34 that is capable of driving the stepping motor 21 with a full step or a micro step and a changeover means that switches a full-step drive and a micro-step drive. The full-step drive and the micro-step drive are switched by the switch means at the predetermined operation time of the stepping motor 21. The switch means switches only when the stepping motor 21 is decelerating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device and a drive control method for a motor, particularly a stepping motor.

[0002]

2. Description of the Related Art A stepping motor is often used as a drive source of a scanner such as a copying machine. The operation of the scanner includes a scan operation for scanning a document and a back scan operation for quickly returning to a scan start position after scanning. During a normal scan, micro-step driving is used to increase the rotational accuracy of the motor, and in a back scan, it is driven in full steps (eg, four-phase excitation with a five-phase stepping motor) to return at high speed.

[0003]

However, if the scanner is returned to the scan start position after scanning the image by performing full step driving, the stepping motor itself remains vibrated when stopped. In this case, when performing a continuous scan, the next scan is performed while the vibration at the time of the stop remains, which affects the image.

[0004] In view of such circumstances, an object of the present invention is to provide a motor drive device and a drive control method that always realize smooth and proper operation.

[0005]

According to the present invention, there is provided a motor driving apparatus comprising: a clock generating means for generating a clock for driving a stepping motor; a driving means capable of driving the stepping motor in full steps or micro steps; A switching means for switching between full-step driving and micro-step driving, wherein the switching means switches between the full-step driving and the micro-step driving by the switching means at a predetermined operation of the stepping motor. It is characterized by doing so.

Further, in the motor driving device of the present invention,
The switching means switches only when the stepping motor is decelerated. Further, in the motor driving device according to the present invention, the switching of the switching unit is determined based on a maximum frequency that can be output by the clock generating unit. Further, in the motor driving device of the present invention, the frequency F1 of the clock from the clock generating means after the switching by the switching means is defined as M, the number of excitation pattern phase divisions after the switching, and F0 as the clock frequency before the switching. It is characterized by the following equation. F1 = F0 × M

Further, the motor driving device of the present invention comprises a clock generating means for generating a clock for driving the stepping motor, a driving means capable of driving the stepping motor in micro steps, and a division number of micro step driving. And a switching means for switching the stepping motor, wherein the number of divisions is switched by the switching means at the time of the microstep driving operation of the stepping motor.

[0008] In the motor drive device of the present invention,
The frequency F3 of the clock from the clock generation means after the switching by the switching means is determined by dividing the number of divisions before the switching by M
0, the number of divisions after switching is M1, and the clock frequency before switching is F2. F3 = F2 × (M1 / M0)

Further, according to the motor drive control method of the present invention, a clock for driving a stepping motor is generated,
Driving the stepping motor in full steps or micro steps, including a step of switching between full step driving and micro step driving, a method for controlling the driving of the stepping motor, wherein the full step driving and the It is characterized in that the micro step drive is switched.

Further, in the motor drive control method according to the present invention, the drive is switched only when the stepping motor is decelerated. Further, in the motor drive control method according to the present invention, the drive switching is determined based on a maximum frequency of a clock that can be generated. Further, in the motor drive control method of the present invention, the clock frequency F1 after the drive is switched is given by the following equation, where M is the number of excitation pattern phase divisions after the switch, and F0 is the clock frequency before the switch. Features. F1 = F0 × M

Further, according to the motor drive control method of the present invention, a clock for driving a stepping motor is generated.
Driving the stepping motor in micro steps,
A method for controlling the driving of a stepping motor, including a step of switching the number of divisions of micro-step driving,
The number of divisions is switched at the time of the micro step driving operation of the stepping motor.

In the motor drive control method according to the present invention, the frequency F3 of the clock after the switching of the number of divisions is
The number of divisions before switching is M0, the number of divisions after switching is M1, and the clock frequency before switching is F2. F3 = F2 × (M1 / M0)

Further, in the image reading apparatus of the present invention, an image reading section for reading an original image is driven by a driving device, and image information obtained by scanning the image reading section is irradiated on a plurality of juxtaposed line sensors. An image reading device configured to read an image by scanning the image data, wherein the driving device includes any one of the motor driving devices described above.

Further, a recording medium of the present invention is a computer-readable recording medium storing a program for causing a computer to function as any one of the above means. Further, a recording medium of the present invention is a computer-readable recording medium storing a program for executing the processing procedure of any of the above methods.

According to the present invention, in order to solve the above-mentioned problem, when the motor speed becomes lower than a certain speed when the motor is decelerated, the drive is switched from the full step drive to the micro step drive. Thereby, the vibration caused by the stepping motor can be greatly reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram when the present invention is applied to a copying machine. In the drawing, reference numeral 1 denotes a platen glass for placing an original, 2 denotes an optical lamp for irradiating the original with light, 3 denotes a plurality of mirrors for reflecting image light, and 4 denotes an image light of the original including the optical lamp 2. A first mirror base 5 for reading out, a second mirror base 5 for sending image light from the first mirror base 4 to the lens 6, and a CCD 6 for transferring image light to be described later.
This is a lens for focusing on the line sensor.

Reference numeral 7 denotes a CCD line sensor for converting image light into an electric image signal, 8 denotes a CCD signal processing unit for processing the image signal from the CCD line sensor 7, and 9 denotes an image signal from the CCD signal processing unit 8. Image signal processing unit for processing, 1
Reference numeral 0 denotes a printing unit that records an image signal from the image signal processing unit 9 on a sheet, 11 denotes a scanner driving unit that moves the mirror tables 4 and 5 in the sub-scanning direction, 12 denotes a lens driving unit that drives the lens 6, and 13 denotes a lens driving unit. A control unit that controls the entire system.

Next, the operation will be described. The image light obtained from the original placed on the platen glass 1 by the first mirror table 4 passes through the second mirror table 5, is focused on the CCD line sensor 7 by the lens 6, and irradiates the CCD line sensor 7. Is done. The CCD line sensor 7 converts the irradiated image light into an electric signal as main scanning. Here, the first mirror table 4 is moved at a constant speed in the sub-scanning direction, and the main scanning signal is sequentially extracted from the CCD line sensor 7 to convert the image information of the original into an electric signal. At this time, the second mirror base 5 is configured to move at half the moving speed of the first mirror base 4 in order to keep the optical path length from the document constant.

Next, the scanner driving section 11, which is a main component of the present invention, will be described. FIG. 2 shows a mechanical configuration of the scanner driving unit 11. In FIG. 2, reference numeral 21 denotes a stepping motor for driving a mirror base; 22, a timing belt for transmitting the rotational force of the stepping motor 21 to a wire shaft 23; It is a wire axis that converts to directional force.

Reference numeral 24 denotes a wire connecting the first mirror base 4, and when the stepping motor 21 is rotated, the wire shaft 23 is rotated by the timing belt 22, thereby pulling the wire 24. Here, the first mirror base 4 can be moved regardless of the direction in which the wire 24 is pulled. Then, the first mirror base 4 connected to the wire 24 is moved in the pulling direction of the wire 24.

FIG. 3 is a block diagram showing the electrical configuration of the scanner driving section 11. 31 is a stepping motor 2
1, an excitation pattern generator 32 for generating a clock for use in the excitation pattern generator 31, a crystal oscillator 33 for determining a clock frequency of the clock generator 32 (the frequency is Reference numeral 34 denotes a motor drive unit for driving a stepping motor based on a control signal from the motor control unit. In the motor control unit, an excitation pattern is created based on the rotation information from the control unit 13, and the motor drive unit 3
4 to excite the motor coil to drive the stepping motor 21. In the excitation pattern generator 31, the control unit 1
When M = 1 according to the division number M information from 3, four-phase excitation,
When M ≧ 2, the motor is automatically driven in micro steps.

FIG. 4 shows an example of a driving circuit of the motor driving section 34 and the stepping motor 21 wired thereto. In the figure, each of the field effect transistors (FET _{1 to} FET ₁₀ ) is turned on / off by motor drive signals a ^{+ to} e ⁺ and a ^{− to} e ⁻ from the excitation pattern generator 31 to supply current to the coil of the stepping motor 21. To drive the stepping motor.

Next, a method of driving the stepping motor 21 will be described. FIG. 5 shows a five-phase stepping motor 21.
(A, b, c, d, e) when the four-phase excitation drive is performed
FIG. When it is "H", it is on the motor power supply side, and when it is "L", it draws the current flowing through the coil on the R1 side. Each excitation pattern is switched in synchronization with Mclk, and by switching the pattern of each phase as shown in the figure, one step is driven for each Mclk.

FIG. 6 shows an excitation pattern of each phase when the five-phase stepping motor 21 is driven by microsteps (divided into four parts). , And correspond to those of FIG. In the micro step, the switching phase (here, the b phase will be described), the current per unit time of the coil on both sides of the point b is 25% as shown in the figure,
Change to 50% and 75%. As a result, the torque distribution is proportional to the duty, and one step in the case of the four-phase excitation shown in FIG. 5 can be driven by dividing it into four steps.

As described above, the motor speed is proportional to Mclk and the number of divisions M, that is, the stepping motor 21 can be controlled by changing Mclk and M.

Next, the operation in the embodiment of the present invention will be described. FIGS. 7, 8, and 9 are flowcharts thereof, and FIG. 10 is a time chart in which a speed change according to the flowcharts is viewed on a time axis. FIG.
Timer interrupt processing for generating the Mclk pulse of
Interrupts are made at any given time interval. When an interrupt occurs, it is determined whether Tint is '0'. If it is "0", the value of Tmclk is substituted for Tint, the Mclk output is set to "H", the flag is set to 1, and the process proceeds (steps S701, 702, 703, 7).
04,705).

If not "0", Tmclk and Ti
nt / 2, and if Tmclk is smaller than Tint, Mclk is set to 'L' and the process proceeds. Tmcl
If k is equal to or greater than Tint, 1 is subtracted from the value of Tint and the next interrupt is waited for (steps S706, 707, S7).
08,709). Note that after step S906, Mc
This is to make lk a 50% duty clock. In this way, if an arbitrary value is substituted for Tmclk, Mclk will generate a pulse with a period of Tmclk × interruption time Ttim.

FIG. 8 is a flowchart for performing an operation of rotating at a constant speed when the target speed is reached by performing acceleration control from a motor stopped state. If there is a motor start instruction (step S801), the control unit 13 performs various processes associated with the motor start (step S802).
flag1 is set to 1, flag2 is set to 0, and Mclk is set to 'L' (step S803). At the time of motor start, the number of divisions M is set to 1 in order to perform four-phase excitation (step S8).
04), a period T for giving the self-starting frequency fs to Tmclk
The count value Tfs / Ttim corresponding to fs is substituted (step S805). The motor start is instructed by substituting 2 for N (steps S806, 807).

Since 1 is set in flag1, the process proceeds to the next step (step S808).
A value obtained by calculating the following equation (1) is substituted for clk (steps S810 and 811). √ (2L / k) · (√ (N) −√ (N−1)) / Ttim (1) where L is the distance the scanner actually moves in one step during four-phase excitation, and k is the acceleration is there.

Next, the cycle Ttag at the time of the target speed
Is determined, and if not, 1 is added to N and the process proceeds to step S808. If the cycle has reached the period Ttag, the apparatus waits for a deceleration instruction without any change.

If there is a deceleration instruction, step S901
Proceed to. By doing so, the self-starting frequency cycle Tfs
Are updated for each pulse, and Mmclk is generated. N in the numerator of the equation (1) indicates the pulse width at the Nth step when the motor is started from the speed 0 at the acceleration k. By dividing this by Tfs, a count value corresponding to the pulse width can be obtained. Therefore, the acceleration of the motor according to this flowchart is constant, and a linear acceleration curve as shown in FIG. 10 is drawn.

FIG. 9 is a flowchart showing the operation from deceleration to stop. When there is a deceleration instruction (step S814), 1 is subtracted from N, and it is determined whether or not N becomes 0 (steps S901, 902, 903).
If it is not 0, the calculation result of the expression (1) is substituted for Tmclk (steps S904 and 905). Next, it is determined whether or not f1ag2 is 1, and if it is 0, the process proceeds to step S912. If 1, Tmclk is compared with a count value Tr corresponding to a 4-phase excitation / microstep switching speed cycle,
If smaller, the process proceeds to step S912. If it is larger, 4 is substituted for M, N * M for N, L / M for L, and 1 for f1ag2 (steps S906, 907, 908, and 90).
9, 910, 911).

Next, wait until f1ag1 becomes 1 (step S912), and when it becomes 1, 1 is substituted for f1ag1 and the process proceeds to step S802. If N is 0 in step S803, stop processing is performed and the operation ends. In this manner, the stepping motor 21 is driven at a pulse cycle according to the equation (1) and decelerates at a constant slope k. Switching between four-phase excitation and micro-step driving is performed by dividing into M. By multiplying N by M and setting the step distance L to 1 / M, driving can be performed without changing the inclination of deceleration.
It is effective to determine the switching frequency based on the highest frequency that can be generated by a timer interrupt.

Here, each functional block and processing procedure shown in the above various embodiments may be constituted by hardware, or may be constituted by CPU or MPU, ROM and R.
It may be constituted by a microcomputer system composed of an AM or the like, and its operation may be realized according to a work program stored in a ROM or a RAM. The present invention also includes a software program for realizing the functions described above, which is provided to a RAM so as to realize the functions of the respective functional blocks, and which is executed by operating the functional blocks according to the programs. include.

In this case, the software program itself implements the functions of the above-described embodiments, and the program itself and means for supplying the program to a computer, for example, a recording medium storing the program Constitute the present invention. As a storage medium for storing such a program, the above-described ROM or RAM
Besides, for example, floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-I,
CD-R, CD-RW, DVD, zip, magnetic tape,
Alternatively, a nonvolatile memory card or the like can be used.

When the computer executes the supplied program, not only the functions of the above-described embodiments are realized, but also the OS (operating system) or other application software running on the computer. Needless to say, such a program is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with the above.

Further, after the supplied program is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the program is provided in the function expansion board or the function expansion unit based on the instruction of the program. It is needless to say that the present invention also includes a case where the CPU or the like performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0038]

As described above, according to the present invention, in this type of motor driving device, the motor can be stopped in fine steps by changing from four-phase driving to microstepping at the time of deceleration. Accordingly, there is an advantage that vibrations caused by the stepping motor can be reduced and smooth and proper operation can be ensured.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example when applied to a copying machine according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a mechanical configuration of a scanner unit according to the embodiment of the present invention.

FIG. 3 is a block diagram of a scanner driving unit according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a circuit configuration of a motor driving unit according to the embodiment of the present invention.

FIG. 5 is a diagram showing a four-phase excitation drive pattern of a five-phase stepping motor according to the embodiment of the present invention.

FIG. 6 is a diagram showing a micro step drive pattern of a five-phase stepping motor according to the embodiment of the present invention.

FIG. 7 is a flowchart illustrating a timer interrupt operation according to the embodiment of the present invention.

FIG. 8 is a flowchart showing a pulse generation operation for acceleration and constant speed in the embodiment of the present invention.

FIG. 9 is a flowchart illustrating a pulse generation operation for deceleration in the embodiment of the present invention.

FIG. 10 is a time chart of acceleration / deceleration in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platen glass 4 1st mirror stand 5 2nd mirror stand 6 Lens 7 CCD line sensor 8 Signal processing part 9 Image signal processing part 10 Printing part 11 Scanner driving part 12 Lens driving part 13 Control part 21 Stepping motor 31 Excitation pattern generator 32 Motor drive unit

Claims (15)

[Claims] 1. Clock generating means for generating a clock for driving a stepping motor, driving means for driving the stepping motor in full steps or micro steps, switching means for switching between full step driving and micro step driving A motor drive device for driving and controlling a stepping motor, wherein the full-step drive and the micro-step drive are switched by the switching means during a predetermined operation of the stepping motor. 2. The motor drive device according to claim 1, wherein said switching means switches only when the stepping motor is decelerated. 3. The motor drive device according to claim 1, wherein the switching of the switching unit is determined based on a maximum frequency that the clock generating unit can output. 4. The frequency F1 of the clock from the clock generating means after switching by the switching means is given by the following equation, where M is the number of excitation pattern phases after switching and F0 is the clock frequency before switching. The motor drive device according to claim 1, wherein: F1 = F0 × M 5. A clock generating means for generating a clock for driving a stepping motor, a driving means capable of driving the stepping motor in micro steps,
A switching unit for switching the number of divisions for micro-step driving, comprising: a switching unit for controlling the driving of the stepping motor, wherein the number of divisions is switched by the switching unit during the micro-step driving operation of the stepping motor. Stepping motor drive device. 6. The frequency F3 of the clock from the clock generating means after the switching by the switching means is defined as M0, the division number before the switching is M1, the clock frequency before the switching is F1, and the clock frequency before the switching is F2. The motor driving device according to claim 1, wherein the motor driving device is given by the following expression. F3 = F2 × (M1 / M0) 7. A step of generating a clock for driving a stepping motor, driving the stepping motor in full steps or micro steps, and switching between full step driving and micro step driving.
A method for controlling driving of a stepping motor, wherein the full-step driving and the micro-step driving are switched when a predetermined operation of the stepping motor is performed. 8. The motor drive control method according to claim 7, wherein the switching of the drive is performed only when the stepping motor is decelerated. 9. The motor drive control method according to claim 7, wherein the drive switching is determined based on a maximum frequency of a clock that can be generated. 10. The clock frequency F1 after the drive is switched is given by the following equation, where M is the number of excitation pattern phase divisions after the switch, and F0 is the clock frequency before the switch. The motor drive control method described in the above. F1 = F0 × M 11. A method for controlling the driving of a stepping motor, comprising the steps of: generating a clock for driving a stepping motor, driving the stepping motor in microsteps, and switching a division number of microstep driving. A stepping motor drive control method, wherein the number of divisions is switched during a micro-step drive operation of the stepping motor. 12. The frequency F3 of the clock after the switching of the number of divisions is given by the following equation, where M0 is the number of divisions before switching, M1 is the number of divisions after switching, and F2 is the clock frequency before switching. The motor drive control method according to claim 11, wherein: F3 = F2 × (M1 / M0) 13. An image reading unit for reading a document image is driven by a driving device, and image information obtained by scanning the image reading unit is irradiated on a plurality of line sensors arranged in parallel to read the image. An image reading device, comprising: a motor driving device according to claim 1, wherein the driving device includes the motor driving device according to claim 1. 14. A computer-readable recording medium storing a program for causing a computer to function as each means according to claim 1. Description: 15. A computer-readable recording medium storing a program for executing the processing procedure of the method according to claim 7. Description: