Control device, optical device, control method, and storage medium

Patent metadata

Field	Value
Publication number	US-10715064-B2
Application number	US-201815975194-A
Country	US
Kind code	B2
Filing date	May 9, 2018
Priority date	May 10, 2017
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

A control device for controlling a stepping motor includes at least one processor which function as a control unit configured to control the stepping motor through a first control method or a second control method by using a control signal, wherein the memory configured to store a plurality of locus data indicating a relationship between an advance angle and a rotation speed of the stepping motor at each waveform of the control signal, the advance angle being a phase difference between a phase corresponding to a rotation position of the stepping motor and a phase of the control signal, and wherein the control unit select one piece of locus data from the plurality of locus data stored in the memory before switching a control method between the first control method and the second control method.

First claim

What is claimed is:

1. A control device for controlling a stepping motor comprising:
a memory configured to store a plurality of locus data indicating a relationship between an advance angle and a rotation speed of the stepping motor at each amplitude of a control signal, the advance angle being a phase difference between a phase corresponding to a rotation position of the stepping motor and a phase of the control signal; and
at least one processor which functions as
a control unit configured to control the stepping motor through an open loop control method or a feedback control method by using a control signal,
wherein, in a case where the control unit switches a control method between the open loop control method to the feedback control method, the control unit selects one piece of locus data from the plurality of locus data stored in the memory before switching a control method between the open loop control method and the feedback control method.

2. The control device according to claim 1 , wherein the control unit selects one piece of locus data from the plurality of locus data stored in the memory to reduce fluctuation of the rotation speed occurring when a control method is switched between the open loop control method and the feedback control method.

3. The control device according to claim 1 , wherein, in a case where the control unit switches the open loop control method to the feedback control method, the control unit
acquires, before the open loop control method is switched to the feedback control method, the advance angle and the rotation speed while control is being executed through the open loop control method,
selects the one piece of locus data from the plurality of locus data stored in the memory based on a combination of the advance angle and the rotation speed acquired while control is being executed through the open loop control method, and
starts executing control through the feedback control method based on the one piece of locus data.

4. The control device according to claim 3 , wherein, in a case where the rotation speed of the stepping motor has reached a first threshold value as a rotation number controllable by the control executed through the feedback control method, the control unit switches the open loop control method to the feedback control method.

5. The control device according to claim 4 , wherein, in a case where the target rotation speed of the stepping motor is determined to be greater than the first threshold value when the control method is switched to the feedback control method, the control unit switches the open loop control method to the feedback control method without processing of controlling the amplitude of the control signal while changing the advance angle to make the rotation speed be constant.

6. The control device according to claim 1 , wherein, in a case where the control unit switches the feedback control method to the open loop control method, the control unit
selects, before switching the feedback control method to the open loop control method, the one piece of locus data from the plurality of locus data stored in the memory based on the amplitude of the control signal which is used for the open loop control method, and
starts executing control through the open loop control method after selecting the one piece of locus data.

7. The control device according to claim 6 , wherein the control unit
acquires, before switching the feedback control method to the open loop control method, the rotation speed while control is being executed through the feedback control method, and
starts executing control through the open loop control method after controlling the stepping motor through the feedback control method based on a target advance angle based on the one piece of locus data and the rotation speed.

8. The control device according to claim 1 , wherein the control unit
adjusts, in a case where it is determined that the one piece of locus data selected from the plurality of locus data is not appropriate for the target rotation speed of the stepping motor after the open loop control method is switched to the feedback control method, the amplitude of the control signal while changing the advance angle to make the rotation speed be constant,
selects the one piece of locus data from the plurality of locus data stored in the memory based on the adjusted amplitude of the control signal, and starts executing control through the feedback control method based on the one piece of locus data.

9. The control device according to claim 1 , wherein, in a case where the control unit switches the feedback control method to the open loop control method, the control unit
adjusts the amplitude of the control signal while changing the advance angle based on the one piece of locus data to make the rotation speed be constant through the feedback control method,
selects, after adjusting the amplitude of the control signal to an amplitude of the control signal which is used for the open loop control method, executing control through the open loop control method.

10. The control device according to claim 1 , wherein the memory stores a parameter acquired by measuring a relationship between the advance angle and the rotation speed as the locus data.

11. The control device according to claim 1 , wherein the storage unit stores coefficient data in an approximate expression based on a relationship between the advance angle and the rotation speed acquired through measurement as the locus data.

12. The control device according to claim 1 , wherein, in a case where specific locus data based on the relationship between the advance angle and the rotation speed which is detected during control of the stepping motor is not stored in the memory, the control unit selects locus data that is closest to the specific locus data from the plurality of locus data stored in the memory.

13. The control device according to claim 1 , wherein, in a case where specific coefficient data based on the relationship between the advance angle and the rotation speed which is detected during control of the stepping motor is not stored in the memory, the control unit corrects the coefficient data stored in the memory.

14. The control device according to claim 1 , wherein the locus data is locus data which includes a target rotation speed of the stepping motor, the locus data falling within a range in which a correspondence relationship between the advance angle and the rotation speed is approximated linearly.

15. The control device according to claim 1 ,
wherein the amplitude of the control signal is an amplitude of the control signal,
wherein the control signal is a pulse width modulation (PWM) signal, and
wherein the amplitude of the control signal corresponds to a duty difference of the PWM signal.

16. The control device according to claim 1 , wherein the processor includes a circuit.

17. The control device according to claim 1 , wherein, in a case where the control unit switches the open loop control method to the feedback control method, the control unit selects the one piece of locus data from the plurality of pieces of locus data stored in the memory based on a combination of the advance angle and the rotation speed acquired while control is being executed through the open loop control method before switching the open loop control method to the feedback control method, and
wherein, in a case where the control unit switches the feedback loop control method to the open loop control method, the control unit selects the one piece of locus data from the plurality of piece

Assignees

• Canon Kk

Inventors

• Honda Hirofumi

Classifications

• H02P6/153

  wherein the commutation is advanced from position signals phase in function of the speed · CPC title

• H02P8/22

  Control of step size; Intermediate stepping, e.g. microstepping · CPC title

• H02P8/14 Primary

  Arrangements for controlling speed or speed and torque (H02P8/12, H02P8/22 take precedence) · CPC title

• H02P8/34

  Monitoring operation (H02P8/36 takes precedence) · CPC title

• H02P8/38

  the fault being step-out · CPC title