JP2000083400A - Drive controller and drive control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress noise and vibration during 1 step drive by switching excitation pattern of each excitation phase, in response to the number of revolutions of a rotor. SOLUTION: When drive start of a stepping motor 501 is designated, data having a predetermined pattern from a central processing unit(CPU) are output, and the data are input to excitation signal input terminals 401a to 401d for drive. Then, an IC 401 for drive switches the excitation phase of the stepping motor 501 based on the data, and furthermore the current is controlled so as to become a preset current value. In this way, the rotor drives 1 step at the time when the torque generated by the motor exceeds the load torque, and no excessive torque is applied so that the response of the rotor does not become vibrative, thereby suppressing generation of noise or vibrations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device and a drive control method used for, for example, motor drive control at the time of electrophotographic image formation.

[0002]

2. Description of the Related Art FIG. 11 shows a configuration example of an image forming apparatus provided with a stepping motor as a power source.

The paper 11 stored in a paper feed tray 10 is fed into the apparatus by a paper feed roller 12 or the like. The leading edge of the fed paper 11 is held by the clipper 13 and held on the outer circumference of the transfer drum 14.

On the other hand, the photosensitive drum 15 is charged by a charger 25, and an electrostatic latent image is formed for each color by the optical unit 16. The electrostatic latent image formed on the photosensitive drum 15 is developed by the respective color developing units 17 to 20 and is transferred to the sheet 11 on the transfer drum 14. Thereafter, the transferred sheet 11 is separated from the transfer drum 14 and fixed by the fixing unit 21. The fixed paper 11 is
The paper is discharged to the paper discharge tray 23 by the paper discharge unit 22.

[0005] The photosensitive drum 15 is cleaned by a cleaning blade 24 to prepare for the next development. However, if the cleaning blade 24 has been in contact with the same location on the photosensitive drum 15 for a long time, the surface of the photosensitive drum 15 where the cleaning blade 24 has been in contact has increased slipperiness. As a result, at the time of the next printing, when the contact portion passes through the cleaning blade 24,
The peripheral speed of the photosensitive drum 15 instantaneously increases, resulting in exposure blurring, which adversely affects image quality.

In order to prevent this adverse effect on the image quality, the photosensitive drum 15 is rotated at a very low speed and the cleaning blade 2 is rotated.
4 needs to be adjusted so as not to touch the same place for a long time. For this adjustment, the drive of the stepping motor is controlled at a rate of one step every several seconds while the printing operation is not performed.

[0007]

However, in the above conventional example, since the stepping motor is always driven with a constant current, the following problems occur.

[0008] The value of the drive current is set so as to generate a torque greater than the load torque when the motor is rotated at the maximum speed. Therefore, when driving is performed one step at a time in several seconds, the torque generated by the motor becomes considerably larger than the load torque, and the rotor behaves with damped vibration as shown in FIG. As a result, noise and vibration during driving are increased, and the quality of the printer is impaired.

Although there is a method of reducing the drive current only when driving one step at a time in several seconds, a margin must be provided for setting the drive current, and it is difficult to obtain the effect of suppressing noise and vibration.

[0010] Further, when the micro-step driving is used,
Although noise and vibration can be reduced, since the maximum generated torque in the case of micro-step driving is equal to the generated torque in the case where only one phase is excited, the maximum driving current must be increased. As a result, a motor driver having a large allowable loss is required, which leads to an increase in the size of the device and an increase in cost. Further, the control is complicated, and the load on a control means such as a microprocessor increases.

It is therefore an object of the present invention to provide a drive control device and a drive control method capable of suppressing noise and vibration during one-step drive, maintaining print quality, and performing small and simple drive control.

[0012]

SUMMARY OF THE INVENTION The present invention is an apparatus for controlling the drive of a motor by sequentially switching a plurality of excitation phases, and by switching the excitation pattern of each excitation phase according to the rotation speed of a rotor. The drive control device is configured by including control means for controlling the drive current of each excitation phase.

The present invention also relates to a device for controlling a two-phase excitation motor, wherein the torque generated by the motor during one-phase excitation is defined as T1, the generated torque of the motor during two-phase excitation is defined as T2, and the load torque is controlled. Where T is a maximum drive current such that T1 <T <T2, and control means for controlling the magnitude of the drive current of each excitation phase is provided. One phase is a constant current drive, and the other phase is a drive control device by controlling the drive current as an excitation pattern that increases stepwise from 0 to a maximum drive current value.

According to the present invention, an image forming apparatus can be configured by including the above-described drive control device and image forming means for forming an image using a motor driven by the drive control device. .

Further, the present invention is a control method for controlling the drive of a motor by sequentially switching a plurality of excitation phases, wherein the excitation pattern of each excitation phase is switched according to the number of rotations of a rotor. A drive control method is provided by including a control step of controlling a drive current of an excitation phase.

Further, the present invention is a control method for controlling a two-phase excitation motor, wherein the generated torque of the motor during one-phase excitation is defined as T1, and the generated torque of the motor during two-phase excitation is defined as T2.
When the load torque is T, the maximum drive current is set so that T1 <T <T2, and when driving at a constant current, one phase is driven at a constant current and the other phase is driven from 0 A drive control method is provided by controlling the magnitude of the drive current of each excitation phase by using an excitation pattern that is gradually increased to a maximum drive current value.

Further, the present invention provides an image forming method by forming an image by an image forming means using a motor driven by the drive control method.

Further, the present invention is a medium in which a program for controlling the drive of a motor by a computer is recorded, and the control program causes the computer to switch the excitation pattern of each excitation phase according to the number of rotations of the rotor. By controlling the drive current of each excitation phase, a recording medium on which a drive control program is recorded is provided.

Also, the present invention provides a computer-based computer
A medium in which a program for performing drive control of a phase-excited motor is recorded. The control program causes a computer to generate a torque generated by the motor during one-phase excitation as T1, and to generate a torque generated by the motor during two-phase excitation. When the load torque is T and the load torque is T, the maximum drive current is set so that T1 <T <T2. When driven at a constant current, one phase is driven at a constant current and the other phase is driven at a constant current. A recording medium on which a drive control program is recorded is provided by controlling the magnitude of the drive current of each excitation phase by forming an excitation pattern that increases stepwise from 0 to a maximum drive current value.

Here, the switching of the excitation pattern of each excitation phase in accordance with the rotation speed is performed between a case where the rotor is rotated at a high speed and a case where the rotor is rotated at a low speed such that the response of the rotor is oscillatory. Can be.

The control means can be driven with a constant current when the rotor is rotated at a low speed such that the response of the rotor is oscillatory.

As the motor, a stepping motor can be used.

The image forming means can form an image by an electrophotographic method.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Outline) First, an outline of the present invention will be described.

According to the present invention, in an image forming apparatus using a two-phase stepping motor as a power source, the generated torque of the motor at the time of one-phase excitation is T1, the generated torque of the motor at the time of two-phase excitation is T2, and the load torque is Is T, T
Control means for setting the maximum drive current so that 1 <T <T2 and controlling the magnitude of the drive current of each excitation phase is provided. When driven by constant current drive, the response of the rotor becomes oscillatory. In the case of such an interval, for example, in the example of FIG.
The phase is constant current drive, and the drive current is 0 for the other phase.
The control is characterized in that control is performed such that the current is gradually increased from the maximum drive current value to the maximum drive current value.

By such control, the generated torque τ of the motor increases in proportion to the drive current I as shown in FIG. FIG. 6 shows that the drive current I is 50 from 0 to the maximum value.
5 shows the response of the rotor when it is raised for ms. When the generated torque τ of the motor exceeds the load torque τ0, the rotor is driven by one step.

(Specific Example) Hereinafter, a specific example will be described.

(First Example) A first embodiment of the present invention will be described with reference to FIGS.

This embodiment is an example in which the above-described image forming apparatus shown in FIG. 11 is applied to the present invention. Here, a case in which a two-phase stepping motor is used and driven by two-phase excitation by a constant current chopper control type stepping motor driver will be described.

FIG. 1 shows a schematic configuration of a control system of the present apparatus.

Reference numeral 30 denotes a printer as an image forming apparatus. A printer control unit 1 controls each device in the printer 30. Reference numeral 2 denotes a power supply that supplies power to each device in the printer 30. Reference numeral 3 denotes sensors for detecting the status of each unit in the printer 30. Reference numeral 4 denotes a drive circuit that drives the motors 5 according to an instruction from the printer control unit 1.
Reference numeral 5 denotes motors such as a stepping motor 501 which is a power source of each device in the printer 30. Reference numeral 6 denotes a display unit that notifies the user of the operation status of the printer 30. Reference numeral 7 denotes a communication controller that performs communication between the printer 30 and the host computer 8. 8 is a printer 30
Is a host computer that transfers data to be printed.

FIG. 2 shows a configuration of a main part according to the present invention.

Reference numeral 101 denotes a CPU mounted in the printer control unit 1, which is composed of, for example, a μPD78054 having two channels of D / A converters having 8-bit resolution. 101a is a digital output port, 101b is D /
This is an analog output port of the A converter.

Reference numeral 401 denotes an IC for driving the stepping motor 501 mounted on the drive circuit 4, for example, SL.
A7024M etc.

Reference numerals 401a to 401d denote A phase, / A phase,
An excitation signal input terminal for performing on / off control of a current flowing in the B and / B phases, and is connected to a digital output port 101a of the CPU 101.

Reference numerals 401e and 401f denote terminals for connecting detection resistors for detecting the current values flowing in the A and / A phases and the B and / B phases, respectively. The current flowing in the motor is converted into a voltage by the detection resistors. Is done.

Reference numerals 402a and 402b denote detection resistors connected to the terminals 401e and 401f.

401 g and h are A phase, / A phase,
The drive current setting voltage input terminals refA,
refB. This drive current setting voltage input terminal 401
g and h are connected to the analog output port 101b of the D / A converter of the CPU 101.

Next, the operation of this circuit will be described.

The maximum drive current is such that T1 <T <T2, where T1 is the generated torque of the motor during one-phase excitation, T2 is the generated torque of the motor during T2-phase excitation, and T is the load torque. Set.

When the start of driving of the stepping motor 501 is instructed, data having a predetermined pattern is output from the CPU 101, and the data is input to the excitation signal input terminals 401 a to 401 d of the driving IC 401. Such an operation is continued during driving of the motor.

The driving IC 401 switches the excitation phase of the stepping motor 501 based on the data, and controls the current so that the current value becomes a set current value.

The control of the driving current is performed by the detection resistors 402a and 402b.
Are compared by the comparator 410 inside the driving IC 401, and the reference voltage applied to the driving current setting voltage input terminals 401 g and h are compared by the chopping circuit 411 inside the driving IC 401. Is executed by chopping.

Hereinafter, description will be made with reference to FIGS.

FIG. 3 shows signal waveforms during normal rotation of the stepping motor 501.

At the time of normal rotation, the driving phase is A
The phase, the B phase, the / A phase, and the / B phase are sequentially switched, and a constant voltage that becomes the maximum drive current is applied to the drive current setting voltage input terminals 401g, h to perform the constant current drive.

Next, one-step driving will be described.

FIG. 4 shows a case where the driving is performed one step per second.
The signal waveforms when shifting to the phase-on hold state are shown.

X1 corresponds to a hold state in which the A phase and the B phase are on.

Next, in X2, the excitation signal is set to A-phase ON,
The terminal refA is set to 0 at the same time as switching from / A phase off to A phase off and / A phase on. Then, the terminal ref
A is increased stepwise from 0, and after 50 ms, is increased to the maximum drive current. Accordingly, the torque generated by the motor increases.

When the generated torque τ exceeds the load torque τ0 as shown in FIG. 5, the rotor is driven by one step as shown in FIG.
The phase B is in the ON hold state.

As described above, when the generated torque τ of the motor exceeds the load torque τ0, the rotor is driven by one step, and no excessive torque is applied. Vibration can be suppressed.

In this example, the drive current I is linearly increased from 0 to the maximum value during 50 ms, but the present invention is not limited to this. For example, the drive current I may be increased in a sinusoidal manner. Various excitation patterns can be applied.

(Second Example) Next, a second embodiment of the present invention will be described with reference to FIGS.

This embodiment is an example in which a two-phase stepping motor is driven by two-phase excitation by a constant current chopper control type stepping motor driver using the image forming apparatus having the configuration shown in FIG.

In FIG. 7, reference numeral 101 denotes a CPU mounted on the printer control unit 1, for example, CXP8753.
2 etc. 101a is a digital output port.

Reference numeral 401 denotes a driving IC for driving a stepping motor mounted on the driving circuit 4.
29M or the like.

Reference numerals 401i and j denote A phase, / A phase,
An excitation signal input terminal for performing on / off control of a current flowing in the B-phase and / B-phase, and is connected to the digital output port 101a.

Reference numerals 401e and f denote terminals for connecting detection resistors for detecting current values flowing in the A-phase, / A-phase, B-phase, and / B-phase, respectively. The current flowing in the motor is converted into a voltage by the detection resistors. Convert.

Reference numerals 405a and 405b are detection resistors connected to the terminals 401e and 401f.

[0062] 401 g and h are A phase, / A phase,
The drive current setting voltage input terminals refA,
refB. This drive current setting voltage input terminal 401
g and h are connected to the outputs of the D / A converters 403a and 403b.

Reference numerals 403a and 403b denote D / A converters having a resolution of 3 bits, each comprising, for example, a ladder resistor. These D / A converters 403a and 403b
Each of the 3-bit data is received from the PU 101, converted into an analog voltage, and output.

Next, the operation of this circuit will be described.

The maximum drive current is represented by T1 which is the torque generated by the motor during the one-phase excitation, and Tmax is the torque generated by the motor during the two-phase excitation.
2. When the load torque is T, T1 <T <T2 is set.

When the start of driving of the stepping motor 501 is instructed, data having a predetermined pattern is output from the CPU 101, and the data is input to the excitation signal input terminals 401 i, j of the driving IC 401. Such an operation is continued during driving of the motor.

The driving IC 401 switches the excitation phase based on the data, and controls the current so that the current value becomes a set current value.

The control of the driving current is performed by the detection resistors 402a and 402b.
Are compared by the comparator 410 inside the driving IC 401, and the reference voltage applied to the driving current setting voltage input terminals 401 g and h are compared by the chopping circuit 411 inside the driving IC 401. Is done by chopping.

Hereinafter, description will be made with reference to FIGS. 8 and 9.

FIG. 8 shows signal waveforms during normal rotation.

At the time of normal rotation, the driving phase is A
The phase, B phase, / A phase, and / B phase are sequentially switched, and 7 is input to the D / A converters 403a and 403b to perform constant current driving at the maximum driving current value.

Next, the case of one-step driving will be described.

FIG. 9 shows an example in which the driving is performed one step per second.
The signal waveforms when shifting to the hold state where the phase and the B phase are on are shown.

At X1, the A-phase and the B-phase correspond to a hold state in which they are on.

Next, in X2, the excitation signal is turned on in the A-phase,
At the same time as switching from A-phase off to A-phase off and / A-phase on, the data input to the D / A converters 403a and 403b are set to 0, and the drive current is set to 0. Then, D / A
The data input to the converters 403a and 403b is gradually increased from 0 to 7, and is increased to the maximum drive current after 50 ms. Accordingly, the torque generated by the motor increases.

Then, as shown in FIG.
Exceeds the load torque τ0, the rotor is driven by one step as shown in FIG.
And B phases are in the ON hold state.

Also in this example, the drive current is linearly increased from 0 to the maximum value within 50 ms. However, the present invention is not limited to this. For example, the drive current is increased in a sinusoidal manner. Patterns can be applied.

The D / A converter can also be set so that the current value in the vicinity where the load torque and the generated torque of the motor become equal can be finely controlled.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer).
The present invention may be applied to an apparatus including two devices (for example, a copying machine and a facsimile machine).

Further, it is needless to say that the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. Then, a storage medium storing a program represented by software for achieving the present invention is supplied to a system or an apparatus, and the computer (or CPU or M) of the system or the apparatus is supplied.
PU) can read and execute the program code stored in the storage medium, so that the effects of the present invention can be enjoyed.

In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, magnetic tape, nonvolatile memory card, ROM
(A mask ROM, a flash EEPROM, or the like) can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a function expansion port inserted into the computer or a memory provided in a function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0085]

As described above, according to the present invention,
In a device using a two-phase excitation motor, T1 <T <T2, where T1 is the generated torque of the motor during one-phase excitation, and T2 is the generated torque of the motor during two-phase excitation.
Means for controlling the magnitude of the drive current of each excitation phase while setting the maximum drive current so that Since the drive current is increased stepwise from 0 to the maximum drive current value, when the generated torque of the motor exceeds the load torque, the rotor is driven by one step and no excessive torque is applied. Is not oscillating, noise and vibration can be suppressed, and print quality in print processing can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a control system in an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a drive circuit unit according to the present invention.

FIG. 3 is a waveform diagram showing signals of various parts during normal rotation.

FIG. 4 is a waveform diagram showing signals of respective units during one-step driving.

FIG. 5 is a waveform diagram showing a relationship between a driving current and a generated torque of a motor.

FIG. 6 is a waveform chart showing the behavior of the rotor.

FIG. 7 is a block diagram illustrating a schematic configuration of a drive circuit unit in an image forming apparatus according to a second embodiment of the present invention.

FIG. 8 is a waveform chart showing signals of various parts during normal rotation.

FIG. 9 is a waveform chart showing signals of respective units during one-step driving.

FIG. 10 is a waveform diagram showing the behavior of a conventional rotor.

FIG. 11 is a cross-sectional view illustrating a configuration of an image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer control part 4 Drive circuit 5 Motors 30 Image forming apparatus 101 CPU 401 Driving IC 410 Comparator 411 Chopping circuit 501 Stepping motor

Claims (19)

[Claims] An apparatus for controlling the driving of a motor by sequentially switching a plurality of excitation phases, wherein the drive current of each excitation phase is switched by switching the excitation pattern of each excitation phase according to the rotation speed of a rotor. A drive control device comprising control means for controlling the drive. 2. The method according to claim 1, wherein the switching of the excitation pattern of each excitation phase according to the rotation speed is performed between a case where the rotor is rotated at a high speed and a case where the rotor is rotated at a low speed such that the response of the rotor is oscillatory. The drive control device according to claim 1, wherein: 3. An apparatus for controlling a two-phase excitation motor, wherein a torque generated by the motor during one-phase excitation is T1, a torque generated by the motor during two-phase excitation is T2, and a load torque is T. At this time, the maximum drive current is set so that T1 <T <T2, and control means is provided for controlling the magnitude of the drive current of each excitation phase. A drive control device wherein constant current drive is performed, and the other phase is controlled as an excitation pattern in which the drive current is increased stepwise from 0 to a maximum drive current value. 4. The drive control device according to claim 3, wherein the control means drives at a constant current when the rotor is rotated at a low speed such that the response of the rotor is oscillatory. 5. The drive control device according to claim 1, wherein the motor is a stepping motor. 6. An image comprising: the drive control device according to claim 1; and an image forming unit configured to form an image using a motor driven by the drive control device. Forming equipment. 7. An image forming apparatus according to claim 6, wherein said image forming means forms an image by an electrophotographic method. 8. A control method for controlling driving of a motor by sequentially switching a plurality of excitation phases, wherein the excitation pattern of each excitation phase is switched according to the number of rotations of a rotor to drive each excitation phase. A drive control method comprising a control step of controlling a current. 9. The switching of the excitation pattern of each excitation phase according to the number of rotations is performed between a case where the rotor is rotated at a high speed and a case where the rotor is rotated at a low speed such that the response of the rotor is oscillatory. 9. The drive control method according to claim 8, wherein: 10. A control method for controlling a two-phase excitation motor, wherein a generated torque of the motor during one-phase excitation is T1, a generated torque of the motor during two-phase excitation is T2, and a load torque is T. Then, the maximum drive current is set so that T1 <T <T2, and when driving at a constant current, one phase is driven at a constant current and another
A drive control method characterized in that the magnitude of the drive current of each excitation phase is controlled by forming an excitation pattern in which the drive current is increased stepwise from 0 to a maximum drive current value. 11. The drive control method according to claim 10, wherein the drive with the constant current is performed when the rotor is rotated at a low speed such that the response of the rotor is oscillatory. 12. The drive control method according to claim 8, wherein the motor is a stepping motor. 13. An image forming method, wherein an image is formed by an image forming unit using a motor driven by the drive control method according to claim 8. 14. The image forming method according to claim 13, wherein said image forming means forms an image by an electrophotographic method. 15. A medium in which a program for performing drive control of a motor by a computer is recorded, wherein the control program causes the computer to switch an excitation pattern of each excitation phase according to a rotation speed of a rotor. A recording medium on which a drive control program for controlling the drive current of each excitation phase is recorded. 16. The switching of the excitation pattern of each excitation phase according to the number of rotations is performed when the rotor is rotated at a high speed.
16. The recording medium according to claim 15, wherein the recording is performed between a time when the rotor is rotated at a low speed such that the response of the rotor is vibratory. 17. A medium in which a program for performing drive control of a two-phase excitation motor by a computer is recorded. The control program causes the computer to generate a torque generated by the motor during one-phase excitation as T1. When the generated torque of the motor at the time of excitation is T2 and the load torque is T, the maximum drive current is set so that T1 <T <T2. When driven at a constant current, one phase is driven at a constant current. And a drive control program for controlling the magnitude of the drive current of each excitation phase by using an excitation pattern in which the drive current is increased stepwise from 0 to the maximum drive current value for the other phase. Recording medium. 18. The recording medium according to claim 17, wherein the driving of the constant current is performed when the rotor is rotated at a low speed such that the response of the rotor is oscillatory. 19. The recording medium according to claim 15, wherein the motor is a stepping motor.