Motor controller Number:7,417,400 from the United States Patent and Trademark Office (PTO) owispatent The present invention is a motor control device comprising a control system, the control system being capable of controlling the motor by PWM and having integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started. In this motor control device, an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.<H controller, Motor, Motor, controlle, 7417400.html, Patent, pto, 7417400

Title: Motor controller

Abstract: The present invention is a motor control device comprising a control system, the control system being capable of controlling the motor by PWM and having integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started. In this motor control device, an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Patent Number: 7,417,400 Issued on 08/26/2008 to Takeishi, et al.

Inventors: Takeishi; Tetsuji (Nagano-ken, JP), Tanaka; Hirotomo (Nagano-ken, JP), Anzai; Sumito (Nagano-ken, JP)
Assignee: Seiko Epson Corporation (Tokyo, JP)

Appl. No.: 10/362,447

Filed: July 5, 2002

PCT Filed: July 05, 2002

PCT No.: PCT/JP02/06849

371(c)(1),(2),(4) Date: August 18, 2003

PCT Pub. No.: WO03/005554

PCT Pub. Date: January 16, 2003

Foreign Application Priority Data


Jul 06, 2001 [JP]			2001-206670
Jul 06, 2001 [JP]			2001-206671
Jul 06, 2001 [JP]			2001-206672
Aug 31, 2001 [JP]			2001-264662

Current U.S. Class: 318/599 ; 318/459; 318/504; 318/609; 318/610; 318/811

Current International Class: G05B 11/28 (20060101)

Field of Search: 318/599,811,504,609,610,459,928.1

References Cited [Referenced By]

U.S. Patent Documents


4580084	April 1986	Takahashi
4869610	September 1989	Nishizawa et al.
5384526	January 1995	Bennett
5467173	November 1995	Sakata et al.
6232730	May 2001	Doyama et al.
6335604	January 2002	Kataoka

Foreign Patent Documents


61056715	Mar., 1986	JP
11-206178	Jul., 1999	JP
2001-128474	May., 2001	JP
2001-169584	Jun., 2001	JP

Other References

International Search Report of PCT/JP02/06849 dated Sep. 3, 2002. cited by other.

Primary Examiner: Donovan; Lincoln
Assistant Examiner: Glass; Erick
Attorney, Agent or Firm: Sughrue Mion, PLLC

Claims

The invention claimed is:

1. A motor control device method comprising preparing a control system, being capable of controlling said motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein said method comprising setting an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during rotating at said target rotation speed, wherein said motor is a paper-feed motor of a printer.

2. A motor control method according to claim 1, wherein for each of a plurality of target rotation speeds, a relation between the target rotation speed and the output value of said integral element when the motor was controlled by said control system to rotate at that target rotation speed is stored, and based on said stored relation, the output value of said integral element at said time when the control is to be started is set to have a value corresponding to the target rotation speed.

3. A motor control method according to claim 2, wherein the relation between the target rotation speed and the output value of said integral element is acquired when a difference between the rotation speed and the target rotation speed of said motor controlled by said control system has become equal to or less than a predetermined value.

4. A motor control method comprising preparing a control system being capable of controlling said motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein said method comprising setting an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during rotating at said target rotation speed, wherein an output value I1 of said integral element when said motor is being controlled by said control system to rotate at a target rotation speed V1, and an output value I2 of said integral element when said motor is being controlled by said control system to rotate at a target rotation speed V2 which is different from the rotation speed V1 are stored, and the output value of said integral element at said time when the control is to be started is determined based on a calculation using said V1, said V2, said I1 and said I2.

5. A motor control method according to claim 4, wherein, when VMAX is a maximum rotation speed of said motor, said V1 and said V2 satisfy relations 0<V1.ltoreq.(2.times.VMAX/3) and 0<V2.ltoreq.(2.times.VMA-X/3).

6. A motor control method comprising a control system, preparing a control system being capable of controlling said motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein said method comprising setting an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during rotating at said target rotation speed, wherein said control system further comprises derivative means being capable of outputting a value corresponding to a derivative value obtained by differentiating the deviation between the rotation speed and the target rotation speed of the motor, and proportional means being capable of outputting a value that is proportional to the deviation between the rotation speed and the target rotation speed of the motor.

7. A motor control method comprising a control system, preparing a control system being capable of controlling said motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein said method comprising setting an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during rotating at said target rotation speed, wherein said motor is a carriage motor of a printer.

8. A motor control device comprising: a control system capable of controlling said motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, said motor control device of starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein an output value of said integral element at a time when control with said control system is to be started to have a value that corresponds to a counter electromotive force generated in said motor during its rotation at said target speed, wherein said motor is a paper-feed motor of a printer.

9. A printer comprising a control system, said control system being capable of controlling said motor by PWM and having an integral element being capable of outpuffing an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, said printer being capable of starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during its rotation at said target speed, wherein said motor is a paper-feed motor of a printer.

10. A computer-readable storage medium storing a computer program for a motor control device, said motor control device comprising a control system that is capable of controlling said motor by PWM and that has an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, said motor control device being capable of starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, said computer program being capable of causing said motor control device to set an output value of said integral element at a time when control with said control system is to be started to have a value that corresponds to a counter electromotive force generated in said motor during its rotation at said target speed, wherein said motor is a paper-feed motor of a printer.

11. A computer system comprising: a main computer unit; a display device; an input device; and a printer having a control system that is capable of controlling said motor by PWM and that has an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and being capable of starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during its rotation at said target speed, wherein said motor is a paper-feed motor of a printer.

12. A printer comprising an image processor, a display section, a recording media mounting section, and a control system that is capable of controlling a motor by PWM and that has an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of said motor, said printer being capable of starting control with said control system for causing said motor to rotate at the target rotation speed after rotation of said motor has been started, wherein an output value of said integral element at a time when control with said control system is to be started is set to have a value that corresponds to a counter electromotive force generated in said motor during its rotation at said target speed, wherein said motor is a paper-feed motor of a printer.

13. A motor control device for starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving said motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when said rotation speed has reached a predetermined rotation speed, performing feedback control of said motor by a control system having an integral element, wherein at least one of said initial driving signal value and said predetermined value is set in accordance with a driving load of said motor.

14. A motor control device according to claim 13, wherein: said motor is driven by PWM; said initial driving signal value is an initial duty; said predetermined value is a predetermined duty; and at least one of said initial duty and said predetermined duty is set in accordance with an output value of said integral element when control of said motor was carried out with said control system.

15. A motor control device according to claim 14, wherein: for each of a plurality of target rotation speeds, a relation between said target rotation speed and the output value of said integral element when the motor was controlled by said control system to rotate at that target rotation speed is acquired; and based on said relation, at least one of said initial duty and said predetermined duty is set.

16. A motor control device according to claim 15, wherein the relation between the target rotation speed and the output value of said integral element is acquired when a difference between the rotation speed and the target rotation speed of said motor being controlled by said control system has become equal to or less than a predetermined value.

17. A motor control device for starting driving of a motor with an initial driving signal which is for causing a gear provided on a motor shaft to abut against an engaged gear that engages said gear, then, after driving said motor with a driving signal having a signal value larger than a value of said initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to this signal value while sequentially driving said motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when said rotation speed has reached a predetermined rotation speed, performing feedback control of said motor by a control system having an integral element, wherein at least one of said initial driving signal value, said signal value larger than said initial driving signal value, and said predetermined value is set in accordance with a driving load of said motor.

18. A motor control device according to claim 17 wherein: said motor is driven by PWM; said initial driving signal value is an initial duty; said predetermined value is a predetermined duty; and at least one of said initial driving signal value, said signal value larger than said initial driving signal value, and said predetermined duty is set based on an output value of said integral element when control of said motor was carried out with said control system.

19. A motor control device according to claim 18, wherein: for each of a plurality of target rotation speeds, a relation between said target rotation speed and the output value of said integral element when the motor was controlled by said control system to rotate at that target rotation speed is acquired; and based on said relation, at least one of said initial driving signal value, said signal value larger than said initial driving signal value, and said predetermined duty is set.

20. A motor control device according to claim 19, wherein the relation between the target rotation speed and the output value of said integral element is acquired when a difference between the rotation speed and the target rotation speed of said motor controlled by said control system has become equal to or less than a predetermined value.

21. A motor control device according to claim 13, wherein said motor is a paper-feed motor of a printer.

22. A motor control device according to claim 13, wherein said motor is a carriage motor of a printer.

23. A motor driving device for driving a motor while providing a forced standstill period when a total rotation amount of said motor reaches a threshold after starting rotation of the motor, wherein at least one of said threshold, a length of said standstill period, and a rotation amount of said motor that is permitted after said standstill period has ended until entering a next standstill period is set in accordance with a driving load of said motor, wherein said motor is driven by PWM with a control system that has integral element performing integration of a deviation between a rotation speed and a target rotation speed of said motor and performing output of a value corresponding to a value of the integration; and at least one of said threshold, a length of said standstill period, and a rotation amount of said motor that is permitted after said standstill period has ended until entering a next standstill period is set in accordance with an output value of said integral element when control of said motor was carried out with said control system, wherein, if the output value of said integral element taken when said motor was controlled with the control system exceeds a predetermined value, then driving of the motor is not performed and a warning is made to a user.

24. A motor driving device according to claim 23, wherein a relation between the target rotation speed and the output value of said integral element is acquired when a difference between the rotation speed and the target rotation speed of said motor being controlled by said control system has become equal to or less than a predetermined value.

25. A motor driving device according to claim 23, wherein said motor is a paper-feed motor of a printer.

26. A motor driving device according to claim 23, wherein said motor is a carriage motor of a printer.

Description

TECHNICAL FIELD

The present invention relates to a motor control device, a motor control method, a motor driving device, a motor driving method, a printer, a computer program, a computer-readable storage medium, and a computer system.

BACKGROUND ART

Presently, motors are used for a variety of information appliances, household appliances and industrial appliances, and various methods for controlling motors have been proposed. (1) One method for controlling a motor is PWM (pulse width modulation). In PWM control, which is also called "pulse width modulation control," the power that is input into the motor is controlled by arbitrarily changing the width of pulses of a predetermined voltage, during which electricity is supplied.

Furthermore, in general, when a motor turns, a counter electromotive voltage corresponding to the rotation speed is generated inside the motor.

If the motor is controlled by PWM control, then it is an important issue how a high-precision control can be achieved in consideration of the influence of the counter electromotive voltage generated inside the motor in correspondence to the rotation speed of the motor. (2) One method for controlling a motor is a motor control method, in which driving of the motor is started with an initial driving signal, the rotation speed is sequentially increased by successively adding a predetermined value to the value of the initial driving signal while driving the motor with a driving signal whose signal value is set to that value obtained as a result of successive addition, and when the rotation speed has reached a predetermined rotation speed, the motor is feedback controlled by a control system having an integration means. There is furthermore the motor control method, in which driving of the motor is started with an initial driving signal for letting a gear provided on the motor shaft abut against an engaged gear that engages that gear, and after the motor is driven with a driving signal of a signal value that is larger than the initial driving signal, the rotation speed is sequentially increased by successively adding a predetermined value to that signal value while driving the motor with a driving signal whose signal value is set to that value obtained as a result of successive addition, and when the rotation speed has reached a predetermined rotation speed, the motor is feedback controlled by a control system having integration means.

If the motor is controlled by such a motor control, then the time until the motor has reached a predetermined rotation speed will vary depending on the driving load of the motor if the initial driving signal or the like is set to a constant value regardless of the driving load of the motor. That is to say, if the driving load of the motor is small, then the predetermined rotation speed will be reached in a short period of time, and on the contrary, if the driving load of the motor is large, then a long period of time will be needed to reach the predetermined rotation speed. (3) A variety of motors are used at present for various kinds of information appliances, household appliances and industrial appliances. Among these motors, electromagnetic motors have a wiring resistance inside the motor, so that if one lets the motor rotate continuously, the motor will heat up. If the motor heats up and reaches a temperature outside the range in which proper operation is guaranteed, then there will be a risk that the motor will be damaged. To address this problem, operation of the motor is halted for a while when the motor becomes hot due to the generated heat, and cooling of the motor is performed.

However, the heating of the motor differs depending on the driving load of the motor. That is to say, when the driving load of the motor is large, then the amount of heat generated by the motor will become large, whereas if the driving load of the motor is small, the amount of heat generated by the motor will be small.

Consequently, if operation of the motor is halted when the total rotation amount of the motor has reached a predetermined amount, regardless of the driving load of the motor, then, if the driving load of the motor is small, the motor will be halted even though it would be possible to continue operating the motor, and conversely, if the driving load of the motor is large, there will be a danger that the motor will be operated in a state in which the guaranteed operating temperature of the motor is exceeded. (4) Motors are used at present for various kinds of information appliances, household appliances and industrial appliances, and also, a variety of control devices for motors have been proposed. One such motor control device is a motor control device controlling the motor by PWM control with a control system having an integration means.

In this motor control device, to recognize the load state of the motor, a so-called measurement is performed, wherein the motor is rotated at a certain rotation speed and the output value of the integration means at that time is detected. Recognizing the load state of the motor with this measurement is advantageous with regard to speed control and position control of the motor.

However, the output value of the integration means that is attained with this measurement is not the absolute value of the load, and should rather be termed a value corresponding to the load.

There are individual differences among motors, and the counter electromotive voltage coefficient, resistance values, etc. take different values for each motor. Thus, errors occur when calculating the value of the current flowing through the motor by indiscriminately using the counter electromotive voltage coefficient and resistance value of a predetermined motor, based on the output value of the integration means obtained by a measurement at a certain load state.

Consequently, in order to perform control with regard to the absolute motor load, that is, the current actually flowing through the motor, it is necessary to convert the output value of the integration means obtained by measurement to the absolute load value (current value), giving consideration to the individual differences among motors. It should be noted that, as an example of control with regard to the absolute motor load, that is, the current actually flowing through the motor, motor heating control or the like with regard to the current value flowing through the motor can be given.

DISCLOSURE OF THE INVENTION

(1) A first invention has been contrived in view of the above problems, and an object thereof is to realize a motor control device, a motor control method, a printer, a computer program, a computer-readable storage medium storing a computer program, and a computer system, which can control a motor by PWM control with high precision.

In order to achieve this object, according to a first invention, in a motor control device that comprises a control system, the control system being capable of controlling the motor by PWM and having integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, mainly, an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, in another first main invention, in a motor control device comprising a control system that is capable of controlling a motor by PWM based on a deviation between a rotation speed and a target rotation speed of the motor, the motor is controlled in accordance with a load of the motor due to a counter electromotive force generated in the motor. (2) A second invention has been contrived in view of the above problems, and an object thereof is to realize a motor control device, a motor control method, a printer, a computer program, a computer-readable storage medium storing a computer program, and a computer system, which can suitably control a motor in accordance with the driving load of the motor.

In order to achieve this object, according to a present second invention, in a motor control device for starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, mainly, at least one of the initial driving signal value and the predetermined value is set in accordance with a driving load of the motor.

Furthermore, according to another second main invention, in a motor control device for starting driving of a motor with an initial driving signal which is for causing a gear provided on a motor shaft to abut against an engaged gear that engages the gear, then, after driving the motor with a driving signal having a signal value larger than a value of the initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to this signal value while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, at least one of the initial driving signal value, the signal value larger than the initial driving signal value, and the predetermined value is set in accordance with a driving load of the motor. (3) A third invention has been contrived in view of the above problems, and an object thereof is to realize a motor driving device, a motor driving method, a printer, a computer program, a computer-readable storage medium storing a computer program, and a computer system, which can suitably drive a motor in accordance with the driving load of the motor.

In order to achieve this object, according to a present third invention is a motor driving device, in a motor driving device for driving a motor while providing a forced standstill period when a total rotation amount of the motor reaches a threshold after starting rotation of the motor, at least one of the threshold, a length of the standstill period, and a rotation amount of the motor that is permitted after the standstill period has ended until entering a next standstill period is set in accordance with a driving load of the motor. (4) A fourth invention has been contrived in view of the above problems, and an object thereof is to realize a motor control device and a printer with which an output value of the integration means obtained by measurement is converted into an absolute load value (current value), in consideration of individual differences among motors.

In order to achieve this object, according to a present fourth invention, obtained is a relation between a difference between an output value of an integral element when a measurement was performed at a first rotation speed and an output value of the integral element when a measurement was performed at a second rotation speed, and an error occurring in a result of calculating a value of a current flowing through a motor when the difference occurs; and the motor is controlled using the relation.

It should be noted that it is also possible to appreciate the present invention from different viewpoints. Furthermore, other features of the present invention will be made apparent from the accompanying drawings and the disclosure of the description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the overall configuration of the inkjet printer.

FIG. 2 is a perspective view showing the configuration of the surroundings of the carriage 3 of the inkjet printer.

FIG. 3 is an explanatory diagram schematically illustrating the configuration of the linear encoder 11 attached to the carriage 3.

FIG. 4(a) is a timing chart showing the waveform of the two output signals of the encoder 11 during forward rotation of the CR motor. FIG. 4(b) is a timing chart showing the waveform of the two output signals of the encoder 11 during reverse rotation of the CR motor.

FIG. 5 is a perspective view showing the parts related to paper supply and paper detection.

FIG. 6 is a perspective view showing the details of the parts of the printer related to paper feeding.

FIG. 7 is a control block diagram of the DC unit 6 serving as the DC motor control device.

FIG. 8(a) is a graph showing the duty signal value sent to the PWM circuit 6j of the PF motor 1 controlled by the DC unit 6. FIG. 8(b) is a graph showing the motor rotation speed.

FIG. 9 is a flowchart showing the procedure of an ordinary printer control method when the power is turned ON.

FIG. 10 is a flowchart for explaining the procedure of the PF measurement.

FIG. 11 is a graph showing the, motor rotation speed and the integral element output values during PF measurement.

FIG. 12 is a diagram showing the relation between the target rotation speed of the PF motor 1 and the output value of the integral element 6g.

In FIG. 13, FIG. 13(a) is a diagram for explaining the control characteristics for the case where the output value of the integral element 6g has not been set to a value obtained by calculation. FIG. 13(b) is a diagram for explaining the control characteristics for the case where the output value of the integral element 6g has been set to a value obtained by calculation.

FIG. 14 is a diagram showing the relation between the target rotation speed of the PF motor 1 and the output value of the integral element 6g, depending on the driving load.

FIG. 15 is a diagram for explaining a modified example of the acceleration control.

FIG. 16 is a diagram showing the relation between the driving load of the PF motor 1 and the output value of the integral element 6g.

FIG. 17 is a flowchart showing the procedure of a countermeasure against heating of the motor.

In FIG. 18, FIG. 18(a) is a diagram showing an example in which the threshold is set in accordance with the driving load. FIG. 18(b) is a diagram showing an example in which the length of the standstill period is set in accordance with the driving load. FIG. 18(c) is a diagram showing an example in which rotation amount of the PF motor 1 that is permitted after termination of a standstill period until entering of the next standstill period (permitted rotation amount) is set in accordance with the driving load.

FIG. 19 is an explanatory diagram showing the external configuration of a computer system.

FIG. 20 is a block diagram showing the configuration of the computer system shown in FIG. 19.

BEST MODE FOR CARRYING OUT THE INVENTION

===Outline of the Disclosure===

At least the following aspects become clear from the below disclosure.

A motor control device comprises a control system, the control system being capable of controlling the motor by PWM and having integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, wherein an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

In a motor control device comprising a control system that has integration means performing integration of a deviation between a rotation speed and a target rotation speed of a motor and performing output of a value corresponding to a value of the integration and that controls the motor by PWM, and starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, if the output value of the integration means at the time when control with the control system was started is inappropriate, the controllability of the motor becomes poor. When the motor rotates, a counter electromotive force corresponding to the rotation speed is generated inside the motor. Therefore, if, for example, the output value of the integration means at the time when the control was started is set to a constant value irrespective of the target rotation speed, then a considerable time may be needed until the rotation speed of the motor follows the target rotation speed and the output value of the integration means takes on a suitable value. In order to address this problem, the output value of the integration means at the time when the control with the control system was started is set to a value corresponding to the counter electromotive force generated in the motor by its rotation. Thus, the time it takes for the rotation speed of the motor to follow the target rotation speed and the output value of the integration means to take on a suitable value can be shortened, and the motor controllability of the motor control device can be improved.

Furthermore, for each of a plurality of target rotation speeds, a relation between the target rotation speed and the output value of the integration means when the motor was controlled by the control system to rotate at that target rotation speed may be stored, and based on the stored relation, the output value of the integration means at the time when the control is to be started may be set to have a value corresponding to the target rotation speed.

Accordingly, since the output value of the integration means at the time when the control was started is set to a value corresponding to the target rotation speed based on an actually measured value, it becomes possible to improve the controllability of the motor even further.

Furthermore, the relation between the target rotation speed and the output value of the integration means nay be acquired when a difference between the rotation speed and the target rotation speed of the motor controlled by the control system has become equal to or less than a predetermined value.

Accordingly, since the output value of the integration means at the time when the control was started is set to a value corresponding to the target rotation speed based on an actually measured value in a further suitable manner, it becomes possible to improve the controllability of the motor even further.

Furthermore, an output value I1 of the integration means when the motor is being controlled by the control system to rotate at a target rotation speed V1, and an output value I2 of the integration means when the motor is being controlled by the control system to rotate at a target rotation speed V2 which is different from the rotation speed V1 may be stored, and the output value of the integration means at the time when the control is to be started may be determined based on a calculation using the V1, the V2, the I1 and the I2.

Upon storing for each of a plurality of target rotation speeds the relation between a rotation speed of the motor and an output value of the integration means when the motor was controlled by the control system to rotate at the target rotation speed and setting the output value of the integration means at the time when the control is to be started to a value corresponding to the target rotation speed based on the stored relation, a problem may arise in process efficiency if it were to determine and store the relation between the target rotation speed of the motor and the output value of the integration means for many target rotation speeds.

It will be efficient if an output value I1 of the integration means when the motor is being controlled by the control system to rotate at a target rotation speed V1, and an output value I2 of the integration means when the motor is being controlled by the control system to rotate at a target rotation speed V2 which is different from the rotation speed V1 are stored, and the output value of the integration means at the time when the control is to be started is determined based on a calculation using the V1, the V2, the I1 and the I2.

Furthermore, in this motor control device, when VMAX is a maximum rotation speed of the motor, the V1 and the V2 may satisfy relations 0<V1.ltoreq.(2.times.VMAX/3) and 0<V2.ltoreq.(2.times.VMAX/3).

When the motor rotates at a relatively fast speed, then the time from starting the control with the control system until the motor is halted is relatively long; therefore, a very precise position control of the motor is possible with the control system. By contrast, when the motor rotates at a relatively slow speed, the motor will be halted soon after the control begins; therefore, if the output value, of the integration means at the start of the control is not suitably set, then there is the possibility that the precision of positioning the motor may drop. Then, by letting V1 and V2 satisfy the relations 0<V1.ltoreq.(2.times.VMAX/3) and 0<V2.ltoreq.(2.times.VMAX/3), it becomes possible to position the motor with high precision even when the motor rotates at a relatively slow speed.

Furthermore, the control system may further comprise derivative means being capable of outputting a value corresponding to a derivative value obtained by differentiating the deviation between the rotation speed and the target rotation speed of the motor, and proportional means being capable of outputting a value that is proportional to the deviation between the rotation speed and the target rotation speed of the motor. Accordingly, it becomes possible to further improve the control characteristics with the control system.

Furthermore, the motor may be a paper-feed motor of a printer. With favorable control of the paper-feed motor of a printer, it becomes possible to improve the printing quality of the printer.

Furthermore, the motor may be a carriage motor of a printer. With favorable control of the carriage motor of a printer, it becomes possible to improve the printing quality of the printer.

Furthermore, it is also possible to realize a motor control method relating to motor control, such as motor control method comprising preparing a control system being capable of controlling the motor by PWM and having an integral element being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, the method comprising setting an output value of the integral element at a time when control with the control system is to be started to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a printer performing such a motor control, such as a printer comprising a control system, the control system being capable of controlling the motor by PWM and having integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the printer being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, wherein an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a computer program capable of causing a motor control device execute such a motor control, such as a computer program for a motor control device, the motor control device comprising a control system that is capable of controlling the motor by PWM and that has integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, the computer program being capable of causing the motor control device to set an output value of the integration means at a time when control with the control system is to be started to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a computer-readable storage medium storing such a computer program, such as a computer-readable storage medium storing a computer program for a motor control device, the motor control device comprising a control system that is capable of controlling the motor by PWM and that has integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, the motor control device being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, the computer program being capable of causing the motor control device to set an output value of the integration means at a time when control with the control system is to be started to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a computer system comprising: a main computer unit; a display device; an input device; and a printer having a control system that is capable of controlling the motor by PWM and that has integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of a motor, and being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, wherein an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a printer comprising an image processor, a display section, a recording media mounting section, and a control system that is capable of controlling a motor by PWM and that has integration means being capable of outputting an integrated value obtained by integrating a deviation between a rotation speed and a target rotation speed of the motor, the printer being capable of starting control with the control system for causing the motor to rotate at the target rotation speed after rotation of the motor has been started, wherein an output value of the integration means at a time when control with the control system is to be started is set to have a value that corresponds to a counter electromotive force generated in the motor by its rotation.

Furthermore, it is also possible to realize a motor control device comprising a control system that is capable of controlling a motor by PWM based on a deviation between a rotation speed and a target rotation speed of the motor, wherein the motor is controlled in accordance with a load of the motor due to a counter electromotive force generated in the motor. It is further possible to realize such a motor control method, a printer, a computer program, a computer-readable storage medium storing a computer program, and a computer system.

Furthermore, in a motor control device for starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, at least one of the initial driving signal value and the predetermined value is set in accordance with a driving load of the motor.

Since at least one of the initial driving signal value and the predetermined value is set in accordance with the driving load of the motor, the time until the motor reaches a predetermined rotation speed can be made to be about the same, regardless of whether the driving load of the motor is large or small.

Furthermore, the motor may be driven by PWM; the initial driving signal value may be an initial duty; the predetermined value may be a predetermined duty; and at least one of the initial duty and the predetermined duty may be set in accordance with an output value of the integration means when control of the motor was carried out with the control system.

There are a variety of methods for actually measuring or estimating the driving load of the motor. For example, it is possible to measure the driving load by connecting, to the motor, a measurement equipment for measuring driving loads. However, if the driving load of the motor is measured by this method, then there will be several complications, for example, a separate measurement equipment becomes necessary and additional work will be needed to connect the measurement equipment. On the contrary, by setting at least one of the initial duty and the predetermined duty in accordance with an output value of the integration means when control of the motor was carried out with the control system, then it will become possible to set the control constants with high precision to values corresponding to the driving load in a simple way.

Furthermore, for each of a plurality of target rotation speeds, a relation between the target rotation speed and the output value of the integration means when the motor was controlled by the control system to rotate at that target rotation speed may be acquired; and based on the relation, it would be preferable to set at least one of the initial duty and the predetermined duty.

Thus, it becomes possible to set the control constants during acceleration control in consideration of the influence of the counter electromotive force that is generated in the motor depending on the rotation speed.

Furthermore, the relation between the target rotation speed and the output value of the integration means may be acquired when a difference between the rotation speed and the target rotation speed of the motor being controlled by the control system has become equal to or less than a predetermined value.

In this case, it becomes possible to set the control constants during acceleration control more suitably based on the actually measured values.

Furthermore, in a motor control device for starting driving of a motor with an initial driving signal which is for causing a gear provided on a motor shaft to abut against an engaged gear that engages the gear, then, after driving the motor with a driving signal having a signal value larger than a value of the initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to this signal value while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, at least one of the initial driving signal value, the signal value larger than the initial driving signal value, and the predetermined value is set in accordance with a driving load of the motor.

Since at least one of the initial driving signal value, the signal value that is larger than the initial driving signal value, and the predetermined value is set in accordance with the driving load of the motor, the time required for the motor to reach a predetermined rotation speed can be made to be about the same regardless of whether the driving load of the motor is large or small.

Furthermore, the motor may be driven by PWM; the initial driving signal value may be an initial duty; the predetermined value may be a predetermined duty; and at least one of the initial driving signal value, the signal value larger than the initial driving signal value, and the predetermined duty may be set based on an output value of the integration means when control of the motor was carried out with the control system.

Since at least one of the initial driving signal value, the signal value that is larger than the initial driving signal value, and the predetermined value is set based on the output value of the integration means when the motor is controlled with the control system, it becomes possible to set the control constants with high precision to values corresponding to the driving load in a simple way.

Furthermore, for each of a plurality of target rotation speeds, a relation between the target rotation speed and the output value of the integration means when the motor was controlled by the control system to rotate at that target rotation speed may be acquired; and based on the relation, at least one of the initial driving signal value, the signal value larger than the initial driving signal value, and the predetermined duty may be set.

Thus, it becomes possible to set the control constants during acceleration control in consideration of the influence of the counter electromotive force generated in the motor in accordance with the rotation speed.

Furthermore, the relation between the target rotation speed and the output value of the integration means may be acquired when a difference between the rotation speed and the target rotation speed of the motor controlled by the control system has become equal to or less than a predetermined value.

Thus, it becomes possible to set the control constants during acceleration control more suitably according to actually measured values.

Furthermore, the motor may be a paper-feed motor of a printer. With favorable control of the paper-feed motor of a printer, it becomes possible to improve the printing quality of the printer.

Furthermore, the motor may be a carriage motor of a printer. With favorable control of the carriage motor of a printer, it becomes possible to improve the printing quality of the printer.

Furthermore, it is also possible to realize a motor control method relating to such a motor control, such as a motor control method comprising starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having an integral element, the method comprising setting at least one of the initial driving signal value and the predetermined value in accordance with a driving load of the motor.

Furthermore, it is also possible to realize a printer executing such a motor control, such as a printer for starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, wherein at least one of the initial driving signal value and the predetermined value is set in accordance with a driving load of the motor.

Furthermore, it is also possible to realize a computer program capable of causing a motor control device to execute such a motor control, such as a computer program for a motor control device, the motor control device being capable of starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, the computer program being capable of causing the motor control device to set at least one of the initial driving signal value and the predetermined value in accordance with a driving load of the motor.

Furthermore, it is also possible to realize a computer-readable storage medium storing such a computer program, such as a computer-readable storage medium storing a computer program for a motor control device, the motor control device being capable of starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, the computer program being capable of causing the motor control device to set at least one of the initial driving signal value and the predetermined value in accordance with a driving load of the motor.

Furthermore, it is also possible to realize a computer system comprising: a main computer unit; a display device; an input device; and a printer being capable of starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, wherein at least one of the initial driving signal value and the predetermined value is set in accordance with a driving load of the motor.

Furthermore, it is also possible to realize a printer comprising an image processor, a display section, and a recording media mounting section, and being capable of starting driving of a motor with an initial driving signal, causing a rotation speed to increase by successively adding a predetermined value to a value of this initial driving signal while sequentially driving the motor with a driving signal whose signal value has a value obtained as a result of the successive addition, and, when the rotation speed has reached a predetermined rotation speed, performing feedback control of the motor by a control system having integration means, wherein at least one of the initial driving signal value and the predetermined value is set in accordance with a driving load of the motor.

Furthermore, in a motor driving device for driving a motor while providing a forced standstill period when a total rotation amount of the motor reaches a threshold after starting rotation of the motor, wherein at least one of the threshold, a length of the standstill period, and a rotation amount of the motor that is permitted after the standstill period has ended until entering a next standstill period is set in accordance with a driving load of the motor.

Since at least one of the threshold, the length of the standstill period, and the rotation amount of the motor that is permitted after terminating a standstill period until entering the next standstill period is set in accordance with the driving load of the motor, it becomes possible to realize a suitable heating countermeasure corresponding to the driving load of the motor.

Furthermore, the motor may be driven by PWM with a control system that has integration means performing integration of a deviation between a rotation speed and a target rotation speed of the motor and performing output of a value corresponding to a value of the integration; and at least one of the threshold, a length of the standstill period, and a rotation amount of the motor that is permitted after the standstill period has ended until entering a next standstill period may be set in accordance with an output value of the integration means when control of the motor was carried out with the control system.

There are a variety of methods for actually measuring or estimating the driving load of the motor. For example, it is possible to measure the driving load by connecting, to the motor, a measurement equipment for measuring driving loads. However, if the driving load of the motor is measured by this method, then there will be several complications, for example, a separate measurement equipment becomes