Motor driving apparatus Number:7,151,348 from the United States Patent and Trademark Office (PTO) owispatent A motor driving apparatus for driving a linear vibration motor having a spring member that supports a mover so as to form a spring vibration system including the mover. The motor driving apparatus employs an accurate spring constant of the spring member corresponding to an individual linear vibration motor at a position calculation for obtaining the position of the mover during the operation, thereby increasing the accuracy of the position calculation. The motor driving apparatus includes a mover force vibration unit for making the mover of the linear vibration motor freely vibrate, a relative position detection unit for detecting a timing when the freely vibrating mover passes through a fixed point (relative position), and a natural frequency detection unit for detecting a natural frequency of the mover based on output information from the relative position detection unit, thereby calculating the spring constant based on the detected natural frequency.<H apparatus, driving, Motor, driving, a, 7151348.html, Patent, pto, 7151348

Title: Motor driving apparatus

Abstract: A motor driving apparatus for driving a linear vibration motor having a spring member that supports a mover so as to form a spring vibration system including the mover. The motor driving apparatus employs an accurate spring constant of the spring member corresponding to an individual linear vibration motor at a position calculation for obtaining the position of the mover during the operation, thereby increasing the accuracy of the position calculation. The motor driving apparatus includes a mover force vibration unit for making the mover of the linear vibration motor freely vibrate, a relative position detection unit for detecting a timing when the freely vibrating mover passes through a fixed point (relative position), and a natural frequency detection unit for detecting a natural frequency of the mover based on output information from the relative position detection unit, thereby calculating the spring constant based on the detected natural frequency.

Patent Number: 7,151,348 Issued on 12/19/2006 to Ueda, et al.

Inventors: Ueda; Mitsuo (Nishinomiya, JP), Nakata; Hideki (Katano, JP), Yoshida; Makoto (Kusatsu, JP)
Assignee: Matsushita Electric Industrila Co., Ltd. (Osaka, JP)

Appl. No.: 10/822,805

Filed: April 13, 2004

Foreign Application Priority Data


Apr 14, 2003 [JP]			2003-109394

Current U.S. Class: 318/114 ; 310/12; 318/119

Current International Class: H02P 1/00 (20060101)

Field of Search: 318/119,126-128,135,686,114 310/12-15,17,36 417/417

References Cited [Referenced By]

U.S. Patent Documents


4150924	April 1979	Toyoda
4353220	October 1982	Curwen et al.
5342176	August 1994	Redlich
6880403	April 2005	Shimada et al.
6960893	November 2005	Yoshida et al.
6977474	December 2005	Ueda et al.

Foreign Patent Documents


0 860 933	Aug., 1998	EP
1 063 760	Dec., 2000	EP
1 349 265	Oct., 2003	EP
8-508558	Sep., 1996	JP
11-324911	Nov., 1999	JP
2002-354864	Dec., 2002	JP
94/23204	Oct., 1994	WO

Primary Examiner: Duda; Rina
Attorney, Agent or Firm: Wenderoth, Lind & Ponack, L.L.P.

Claims

What is claimed is:

1. A motor driving apparatus for driving a linear vibration motor having a mover which is reciprocatably provided and a spring member which supports the mover, said motor driving apparatus including: a mover force vibration unit for making the mover freely vibrate; a vibration parameter obtaining unit for obtaining a natural vibration parameter that shows natural vibration of the mover on the basis of a free vibration state of the mover; a spring constant decision unit for calculating a spring constant of the spring member by using the natural vibration parameter obtained by said vibration parameter obtaining unit; and a mover position calculation unit for calculating the position of the mover on the basis of a driving current and a driving voltage which are applied to the linear vibration motor, by using the spring constant calculated by said spring constant decision unit.

2. The motor driving apparatus as defined in claim 1, wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural frequency detection unit for detecting a natural frequency as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said spring constant decision unit is operable to calculate the spring constant by multiplying the natural frequency detected by said natural frequency detection unit by a twofold of the ratio of the circumference to the diameter, squaring the result of the multiplication, and multiplying the squared value by a mass of the mover.

3. The motor driving apparatus as defined in claim 1, wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural angular frequency detection unit for detecting a natural angular frequency as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said spring constant decision unit is operable to calculate the spring constant by squaring the natural angular frequency detected by said natural angular frequency detection unit and multiplying the squared natural angular frequency by a mass of the mover.

4. The motor driving apparatus as defined in claim 1, wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural frequency period detection unit for detecting a natural frequency period as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said spring constant decision unit is operable to calculate the spring constant by dividing the natural frequency period detected by said natural frequency period detection unit by a twofold of the ratio of the circumference to the diameter, squaring the result of the division, multiplying the squared value by an inverse of a mass of the mover, and calculating an inverse of the result of the multiplication.

5. The motor driving apparatus as defined in claim 1, wherein said vibration parameter obtaining unit includes a timing detection unit operable to detect a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration by using an induced voltage that occurs on a coil of the linear vibration motor due to the free vibration of the mover.

6. The motor driving apparatus as defined in claim 1, wherein said mover force vibration unit is operable to mechanically apply a force to the mover so that the mover freely vibrates.

7. The mover driving apparatus as defined in claim 1, wherein said mover force vibration unit is operable to temporarily cut off the current that is applied to the linear vibration motor so that the mover freely vibrates.

8. The motor driving apparatus as defined in claim 1, wherein said mover force vibration unit is operable to disconnect a load that is connected to the linear vibration motor so that the mover freely vibrates.

9. The motor driving apparatus as defined in claim 1, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode before a start of the operation of the load; said spring constant calculation unit is operable to calculate the spring constant in the arithmetic mode before the start of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant that has been calculated before the start of the operation of the load.

10. The motor driving apparatus as defined in claim 1, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode after a completion of the operation of the load; said spring constant calculation unit is operable to calculate the spring constant in the arithmetic mode after the completion of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant that has been calculated in a recently set arithmetic mode.

11. The motor driving apparatus as defined in claim 1, further including: a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member; a temperature detection unit for detecting a temperature of the linear vibration motor; and a spring constant estimation unit for estimating the spring constant in a load operating state, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode at least one of before a start of the operation of the load and after a completion of the operation of the load; said spring constant estimation unit is operable to, in the arithmetic mode, derive a relationship between the temperature of the linear vibration motor and the spring constant on the basis of the calculated spring constant and the temperature that is detected by said temperature detection unit when the spring constant is calculated, and in the driving mode, estimate the spring constant in the load operating state on the basis of the temperature detected by said temperature detection unit by using the derived relationship between the temperature and the spring constant; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant estimated by said spring constant estimation unit.

12. An air conditioner provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said air conditioner including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 1.

13. A refrigerator provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said refrigerator including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 1.

14. A cryogenic freezer provided with a compressor which has a cylinder and a piston, for compressing a liquid in the cylinder by a reciprocating motion of the piston, said cryogenic freezer including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 1.

15. A hot-water supply unit provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said hot-water supply unit including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; said motor driving apparatus is the motor driving apparatus as defined in claim 1.

16. A handy phone comprising a linear vibration motor for generating vibration, and a motor driving apparatus for driving said linear vibration motor, wherein: said linear vibration motor has a mover which is reciprocatably provided, and a spring member which supports said mover; and said motor driving apparatus is the motor driving apparatus as defined in claim 1.

17. A motor driving apparatus for driving a linear vibration motor having a mover which is reciprocatably provided and a spring member which supports the mover, said motor driving apparatus including: a motor driver for applying a driving current and a driving voltage to the linear vibration motor; a current detection unit for detecting a current that is applied from the said motor driver to the linear vibration motor; a voltage detection unit for detecting a voltage that is applied from said motor driver to the linear vibration motor; a resonance frequency detection unit for detecting a resonance frequency of the linear vibration motor from the detected current and the detected voltage; a spring constant decision unit for calculating a spring constant of the spring member by multiplying the resonance frequency detected by said resonance frequency detection unit by a twofold of the ratio of the circumference to the diameter, squaring the result of the multiplication, and multiplying the squared value by a mass of the mover; and a mover position calculation unit for calculating the position of the mover on the basis of the driving current and the driving voltage, by using the spring constant calculated by said spring constant decision unit.

18. The motor driving apparatus as defined in claim 17, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode before a start of the operation of the load; said spring constant calculation unit is operable to calculate the spring constant in the arithmetic mode before the start of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant that has been calculated before the start of the operation of the load.

19. The motor driving apparatus as defined in claim 17, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode after a completion of the operation of the load; said spring constant calculation unit is operable to calculate the spring constant in the arithmetic mode after the completion of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant that has been calculated in a recently set arithmetic mode.

20. The motor driving apparatus as defined in claim 17, further including: a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the spring constant of the spring member; a temperature detection unit for detecting a temperature of the linear vibration motor; and a spring constant estimation unit for estimating the spring constant in a load operating state, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode at least one of before a start of the operation of the load and after a completion of the operation of the load; said spring constant estimation unit is operable to, in the arithmetic mode, derive a relationship between the temperature of the linear vibration motor and the spring constant on the basis of the calculated spring constant and the temperature that is detected by said temperature detection unit when the spring constant is calculated, and in the driving mode, estimate the spring constant in the load operating state on the basis of the temperature detected by said temperature detection unit by using the derived relationship between the temperature and the spring constant; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the spring constant estimated by said spring constant estimation unit.

21. An air conditioner provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said air conditioner including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 17.

22. A refrigerator provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said refrigerator including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 17.

23. A cryogenic freezer provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said cryogenic freezer including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 17.

24. A hot-water supply unit provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said hot-water supply unit including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 17.

25. A handy phone comprising a linear vibration motor for generating vibration, and a motor driving apparatus for driving said linear vibration motor, wherein: said linear vibration motor has a mover which is reciprocatably provided, and a spring member which supports said mover; and said motor driving apparatus is the motor driving apparatus as defined in claim 17.

26. A motor driving apparatus for driving a linear vibration motor having a mover which is reciprocatably provided and a spring member which supports the mover, said motor driving apparatus including: a mover force vibration unit for making the mover freely vibrate; a vibration parameter obtaining unit for obtaining a natural vibration parameter that shows natural vibration of the mover on the basis of a free vibration state of the mover; a mass/spring ratio decision unit for deciding a mass/spring ratio that is a ratio between a mass of the mover and a spring constant of the spring member by using the natural vibration parameter obtained by said vibration parameter obtaining unit; and a mover position calculation unit for calculating the position of the mover on the basis of a driving current and a driving voltage which are applied to the linear vibration motor, by using the mass/spring ratio decided by said mass/spring ratio decision unit.

27. The motor driving apparatus as defined in claim 26, wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural frequency detection unit for detecting a natural frequency as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said mass/spring ratio decision unit is operable to decide the mass/spring ratio by multiplying the natural frequency detected by said natural frequency detection unit by a twofold of the ratio of the circumference to the diameter, squaring the result of the multiplication, and calculating an inverse of the squared value.

28. The motor driving apparatus as defined in claim 26 wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural angular frequency detection unit for detecting a natural angular frequency as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said mass/spring ratio decision unit is operable to calculate the mass/spring ratio by squaring the natural angular frequency detected by said natural angular frequency detection unit and calculating an inverse of the squared natural angular frequency.

29. The motor driving apparatus as defined in claim 26, wherein said vibration parameter obtaining unit includes: a timing detection unit for detecting a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration; and a natural frequency period detection unit for detecting a natural frequency period as the natural vibration parameter of the mover on the basis of an output from said timing detection unit, and wherein said mass/spring ratio decision unit is operable to decide the mass/spring ratio by dividing the natural frequency period detected by said natural frequency detection unit by a twofold of the ratio of the circumference to the diameter, and squaring the result of the division.

30. The motor driving apparatus as defined in claim 26, wherein said vibration parameter obtaining unit includes a timing detection unit operable to detect a timing when the freely vibrating mover passes through a prescribed relative position with respect to a reference position of the vibration by using an induced voltage that occurs on a coil of the linear vibration motor due to the free vibration of the mover.

31. The motor driving apparatus as defined in claim 26, wherein said mover force vibration unit is operable to mechanically apply a force to the mover so that the mover freely vibrates.

32. The motor driving apparatus as defined in claim 26, wherein said mover force vibration unit is operable to temporarily cut off the current that is appplied to the linear vibration motor so that the mover freely vibrates.

33. The motor driving apparatus as defined in claim 26, wherein said mover force vibration unit is operable to disconnect a load that is connected to the linear vibration motor so that the mover freely vibrates.

34. The motor driving apparatus as defined in claim 26, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode before a start of the operation of the load; said mass/spring ratio decision unit is operable to decide the mass/spring ratio in the arithmetic mode before the start of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio that has been calculated before the start of the operation of the load.

35. The motor driving apparatus as defined in claim 26, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode after a completion of the operation of the load; said mass/spring ratio decision unit is operable to decide the mass/spring ratio in the arithmetic mode after the completion of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio that has been calculated in a recently set arithmetic mode.

36. The motor driving apparatus as defined in claim 26, further including: a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio; a temperature detection unit for detecting a temperature of the linear vibration motor; a mass/spring ratio estimation unit for estimating the mass/spring ratio in a load operating state, wherein: said control unit temporarily is operable to set the operation mode to the arithmetic mode at least one of before a start of the operation of the load and after a completion of the operation of the load; said mass/spring ratio estimation unit is operable to, in the arithmetic mode, derive a relationship between the temperature of the linear vibration motor and the mass/spring ratio on the basis of the calculated mass/spring ratio and the temperature that is detected by said temperature detection unit when the mass/spring ratio is calculated, and in the driving mode, estimate the mass/spring ratio in the load operating state on the basis of the temperature detected by said temperature detection unit by using the derived relationship between the temperature and the mass/spring ratio; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio estimated by said mass/spring ratio estimation unit.

37. An air conditioner provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said air conditioner including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 26.

38. A refrigerator provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said refrigerator including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 26.

39. A cryogenic freezer provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said cryogenic freezer including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 26.

40. A hot-water supply unit provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said lot-water supply unit including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 26.

41. A handy phone comprising a linear vibration motor for generating vibration, and a motor driving apparatus for driving said linear vibration motor, wherein: said linear vibration motor has a mover which is reciprocatably provided, and a spring member which supports the mover; and said motor driving apparatus is the motor driving apparatus as defined in claim 26.

42. A motor driving apparatus for driving a linear vibration motor having a mover which is reciprocatably provided and a spring member which supports the mover, said motor driving apparatus including: a motor driver for applying a driving current and a driving voltage to the linear vibration motor; a current detection unit for detecting a current that is applied from said motor driver to the linear vibration motor; a voltage detection unit for detecting a voltage that is applied from said motor driver to the linear vibration motor; a resonance frequency detection unit for detecting a resonance frequency of the linear vibration motor from the detected current and the detected voltage; a mass/spring ratio decision unit for deciding a mass/spring ratio by multiplying the resonance frequency detected by said resonance frequency detection unit by a twofold of the ratio of the circumference to the diameter, squaring the result of the multiplication, and calculating an inverse of the squared value; and a mover position calculation unit for calculating the position of the mover on the basis of the driving current and the driving voltage, by using the mass/spring ratio decided by said mass/spring ratio decision unit.

43. The motor driving apparatus as defined in claim 42, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode before a start of the operation of the load; said mass/spring ratio decision unit is operable to decide the mass/spring ratio in the arithmetic mode before the start of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio that has been calculated before the start of the operation of the load.

44. The motor driving apparatus as defined in claim 42, further including a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode after a completion of the operation of the load; said mass/spring ratio decision unit is operable to decide the mass/spring ratio in the arithmetic mode after the completion of the operation of the load; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio that has been calculated in a recently set arithmetic mode.

45. The motor driving apparatus as defined in claim 42, further including: a control unit for setting an operation mode to either a driving mode for driving the linear vibration motor to operate a load that is connected to the linear vibration motor, or an arithmetic mode for calculating the mass/spring ratio; a temperature detection unit for detecting a temperature of the linear vibration motor; a mass/spring ratio estimation unit for estimating the mass/spring ratio in a load operating state, wherein: said control unit is operable to temporarily set the operation mode to the arithmetic mode at least one of before a start of the operation of the load and after a completion of the operation of the load; said mass/spring ratio estimation unit is operable to, in the arithmetic mode, derive a relationship between the temperature of the linear vibration motor and the mass/spring ratio on the basis of the calculated mass/spring ratio and the temperature that is detected by said temperature detection unit when the mass/spring ratio is calculated, and in the driving mode, estimate the mass/spring ratio in the load operating state on the basis of the temperature detected by said temperature detection unit by using the derived relationship between the temperature and the mass/spring ratio; and said mover position calculation unit is operable to calculate the position of the mover in the driving mode by using the mass/spring ratio estimated by said mass/spring ratio estimation unit.

46. An air conditioner provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said air conditioner including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 42.

47. A refrigerator provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said refrigerator including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 42.

48. A cryogenic freezer provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said cryogenic freezer including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 42.

49. A hot-water supply unit provided with a compressor which has a cylinder and a piston, and for compressing a liquid in the cylinder by a reciprocating motion of the piston, said hot-water supply unit including: a linear vibration motor for making the piston reciprocate, said linear vibration motor having a mover which is reciprocatably provided, and a spring member which supports said mover; and a motor driving apparatus for driving said linear vibration motor; wherein said motor driving apparatus is the motor driving apparatus as defined in claim 42.

50. A handy phone comprising a linear vibration motor for generating vibration, and a motor driving apparatus for driving said linear vibration motor, wherein: said linear vibration motor has a mover which is reciprocatably provided, and a spring member which supports said mover; and said motor driving apparatus is the motor driving apparatus as defined in claim 42.

Description

FIELD OF THE INVENTION

The present invention relates to motor driving apparatuses and, more particularly, to motor driving apparatuses for driving a linear vibration motor including a mover and a spring member that supports the mover.

BACKGROUND OF THE INVENTION

Conventional equipment using linear vibration motors include vibration generators that inform of incoming calls by mechanical vibration, such as handy phones, compressors that compress and circulate gas or liquid, and reciprocating electric razors. In this specification, the handy phones refer to portable phones such as mobile phones and cellular phones. The compressors and the reciprocating electric razors use the linear vibration motors as their driving sources.

A typical linear vibration motor has a structure of a single-phase sync motor, i.e., it has a mover comprising a permanent magnet and a stator obtained by winding a coil around an iron core, and the mover reciprocates when an AC voltage is applied to the coil.

When generating vibrations by the reciprocating motion of the mover, a strong electromagnetic force is needed. However, an energy required for driving the linear vibration motor can be suppressed by forming a spring vibration system including the mover and a spring member supporting the mover. That is, in the linear vibration motor in which the mover is supported by the spring member, the spring vibration system including the mover is vibrated at its natural frequency (resonance frequency), whereby the linear vibration motor can be driven with a relatively low energy.

In the linear vibration motor, however, when the stroke length of the mover becomes larger than a predetermined allowable value, a problem such as a collision between the mover and the motor housing or breakage of the spring member may occur. Therefore, the position of the mover must be detected and controlled.

Japanese Published Patent Application No. Hei.11-324911 discloses a driving apparatus for driving a linear vibration motor, which includes a detector such as a position sensor for detecting the position of the mover of the linear vibration motor, and reduces the output of the linear vibration motor when the stroke length of the mover becomes larger than a predetermined allowable value, i.e., decreases the amplitude value of the voltage or current applied to the linear vibration motor, thereby preventing the linear vibration motor from being broken due to collision between the mover and the motor housing or extension of the spring member over a critical value.

As the above-mentioned position detector, there is employed a sensor that can detect the degree of displacement of the mover (the mover displacement amount) with respect to a mover reference position such as a mover neutral position without contacting the mover of the linear vibration motor. For example, a displacement gauge using an eddy current system, a displacement gauge using a differential transformer, or the like is employed.

However, when such sensor is employed, not only the production cost of the linear vibration motor is increased but also a space for mounting the sensor is needed, which leads to an increase in the size of the housing of the linear vibration motor. Further, when considering the compressor as an application of the linear vibration motor, such sensor may be used with being exposed to a high-temperature and high-pressure gas. Therefore, a problem on reliability of the sensor itself occurs, in other words, a sensor that can be reliably used in high-temperature and high-pressure atmospheres is required.

So, as a method for detecting the position of the piston, there is proposed a method of directly measuring the linear motor driving current and voltage which are supplied to the linear vibration motor, and deriving the position of the mover on the basis of the measured values, without using a position sensor placed in the linear vibration motor (refer to Japanese Unexamined Patent Publication No.Hei.8-508558).

Hereinafter, a description will be given of the mover position detection method used for a linear vibration motor, which is described in the above-mentioned application. The linear vibration motor described in this application is applied to a linear compressor. Therefore, this application describes a case where a mover that reciprocates within a cylinder so as to compress gas in the cylinder constituting the linear compressor is prevented from colliding against a cylinder head.

FIG. 11 is a diagram illustrating an equivalent circuit of a linear vibration motor for driving a mover.

In FIG. 11, L indicates an equivalent inductance [H] of a coil as a component of the linear vibration motor, and R indicates an equivalent resistor [.OMEGA.] of the coil. V indicates an instantaneous voltage [V] applied to the linear vibration motor, and I indicates a current [A] applied to the linear vibration motor. Further, .alpha..times.v indicates a induced electromotive voltage [V] which is generated when the linear motor is driven, wherein .alpha. is a thrust constant [N/A] of the linear vibration motor, and v is an instantaneous velocity [m/s] of the linear vibration motor.

Here, the thrust constant .alpha. of the linear vibration motor indicates a force [N] which is generated when a unit current [A] is passed through the linear vibration motor. While the unit of the thrust constant .alpha. is expressed by [N/A], this unit is equivalent to [Wb/m] or [Vs/m].

The equivalent circuit shown in FIG. 11 is derived from Kirchhoff's law, and an instantaneous velocity v [m/s] of the linear vibration motor is obtained from the equivalent circuit.

That is, under the state where a driving voltage is applied to the linear vibration motor, the voltage (V) applied to the linear vibration motor is balanced with the sum of a dropped voltage (I.times.R) [V] due to the equivalent resistance of the coil of the linear vibration motor, a dropped voltage (LdI/dt)[V] due to the equivalent inductance of the coil, and the induced electromotive voltage (.alpha..times.v) [V] generated when driving the linear vibration motor, and then the following formula (1) is derived.

.alpha..times..times..times.dd.times..times. ##EQU00001##

The coefficients .alpha.[N/A], R[.OMEGA.], and L[H] used in formula (1) are constants unique to the motor, and these constants are known values. Accordingly, the instantaneous velocity v[m/s] can be obtained from these constants and the applied voltage V[V] and current I[A] which are measured, on the basis of formula (1).

Further, the mover displacement (a distance from an undefined reference position to the mover) x[m] is obtained by time integration of the instantaneous velocity v[m/s] as shown by the following formula (2). In formula (2), the constant Const. is a mover displacement at the start of the integration. x=.intg.vdt+Const. Formula (2)

As described above, in the mover position detection method as proposed in the above application, the measured value V of the applied voltage and the measured value I of the applied current associated with the linear vibration motor are subjected to arithmetic processing including differentiation based on formula (1) to obtain the instantaneous velocity v of the mover, and further, the instantaneous velocity v is subjected to arithmetic processing including integration based on formula (2), whereby the mover displacement x can be obtained.

However, the mover displacement x obtained by the arithmetic processing based on formulae (1) and (2) is a displacement with respect to a certain position on the mover axis, and it is impossible to obtain a distance from the cylinder head which may be collided by the mover to the mover top dead point, directly from the displacement x.

To be more specific, when the compressor to which the linear vibration motor is applied is under a loaded condition, the mover center position (mover amplitude center position) in the mover reciprocating motion is offset with respect to the mover neutral position (i.e., the mover amplitude center position when the pressure in the compression chamber is equal to the back pressure) due to the pressure of a cooling medium gas, and the mover reciprocates around the offset mover amplitude center position. In other words, the mover displacement x obtained by formula (2) includes an average component.

However, every actual analog or digital integrator does not perform ideal integration processing for outputting a perfect response signal with respect to a constant or a DC input, but it is restricted in responding to a DC input. Therefore, an actual integrator cannot subject the mover displacement x to integration processing in which its average component is reflected. The reason why the DC response of the actual integrator is restricted is because the output of the integrator should be prevented from being saturated by unavoidable DC components in the input signal.

As a result, the mover displacement x[m] obtained by the integration processing based on formula (2) using the actual integrator is not a displacement from which an actual distance between the mover and the housing cannot be obtained directly, but a displacement simply indicating the mover position with reference to a certain point on the mover axis.

Therefore, the mover displacement x[m] obtained from formula (2) is converted into a mover displacement x' indicating a mover position with respect to the mover amplitude center position. Further, using the converted mover displacement x', arithmetic processing for obtaining a mover displacement xav'' with reference to the cylinder head, which indicates the mover amplitude center position, is carried out.

Hereinafter, these arithmetic processings will be described in more detail.

FIG. 12 is diagram schematically illustrating the mover position in the linear vibration motor housing (the cylinder in this case).

In this figure, Me denotes a mover, and Mc denotes an inner wall (cylinder inner surface) of the linear vibration motor housing that contains the mover.

Initially, three coordinate systems shown in FIG. 12, i.e., a first coordinate system X, a second coordinate system X', and a third coordinate system X'', will be briefly described.

The first coordinate system X is a coordinate system expressing the mover displacement x and it has, as an origin (x=0), a certain point Paru on the mover axis. Accordingly, the absolute value of the displacement x indicates the distance from the point Paru to the mover front end position P.

The second coordinate system X' is a coordinate system expressing the mover displacement x' and it has, as an origin (x'=0), the mover amplitude center position Pav. Accordingly, the absolute value of the displacement x' indicates the distance from the amplitude center position Pav to the mover front end position P.

The third coordinate system X'' is a coordinate system expressing the mover displacement x'' and it has, as an origin (x''=0), the cylinder head position Psh on the mover axis. Accordingly, the absolute value of the displacement x'' indicates the distance from the cylinder head position Psh to the mover front end position P.

Next, an arithmetic operation for obtaining the mover displacement x'' will be described.

A mover position (mover top dead point position) Ptd in which the mover is closest to the cylinder head is indicated by a displacement xtd on the first coordinate system X, and a mover position (mover bottom dead point position)Pbd in which the mover is farthest from the cylinder head is indicated by a displacement xbd on the first coordinate system X. Then, a mover stroke Lps[m] is obtained from a difference between the displacement xtd corresponding to the mover top dead point position Ptd on the first coordinate system X and the displacement xbd corresponding to the mover bottom dead point position Pbd on the first coordinate system X.

Further, the mover amplitude center position Pav in the state where the mover is reciprocating is a position which is apart from the displacement xtd of the mover position (mover top dead point position) Ptd in which the mover is the closest to the cylinder head, by a length (Lps/2) equal to half the mover stroke Lps[m], away from the cylinder head. Accordingly, the mover amplitude center position Pav is expressed by a displacement xav (=(xbd-xtd)/2) on the first coordinate system X.

Further, when the constant Const. in formula (2) is 0, a new function that indicates the mover front end position P by the mover displacement x'[m] is derived with the mover amplitude center position Pav as a reference (origin), in other words, on the second coordinate system X'.

Subsequently, a description will be given of a method for obtaining the mover displacement xav'' indicating a distance from the cylinder head position Psh to the mover amplitude center position Pav on the third coordinate system X'' with the cylinder head position Psh as an origin.

Under the state where the linear compressor draws in a cooling medium gas (suction state), i.e., under the state where the inlet valve is open, both of the pressure in the compression chamber and the pressure on the back of the mover are equal to the cooling medium inlet pressure. This is because the linear compressor is constructed so that the differential pressure becomes zero under the state where the inlet valve is open. In this state, a force from the pressure of the cooling medium that acts on the mover can be ignored. That is, in this state, the forces acting on the mover are only the repulsive force of the spring that is generated by bending of the support spring and the electromagnetic force that is generated by applying a current to the linear vibration motor. According to Newton's law of motion, the sum of these forces is equal to the product of the total mass of the movable member that is moving, and its acceleration.

Accordingly, under this state, the following formula (3) holds as an equation of motion relating to the movable member. m.times.a=a.times.I-k(x'+xav''-xini'') Formula (3)

In formula (3), m is the total mass [kg] of the movable member that is reciprocating, a is the instantaneous acceleration [m/s/s] of the movable member, and k is the spring constant [N/m] of the support spring that is incorporated in the linear vibration motor. Further, xav'' is the above-mentioned displacement on the third coordinate system X'', which indicates the mover amplitude center position, and the absolute value of this displacement xav'' expresses the distance from the cylinder head position Psh to the mover amplitude center position Pav. Further, xini'' is the displacement on the third coordinate system X'', which indicates the mover neutral position Pini, and the absolute value of this displacement xini'' expresses the distance [m] between the mover neutral position (the position of the mover in the state where the support spring is not deformed) Pini and the cylinder head position Psh.

Here, the instantaneous acceleration a [m/s/s] is obtained as shown in the following formula (4), by differentiating the instantaneous velocity v[m/s] given by formula (1).

dd.times..times. ##EQU00002##

Furthermore, the displacement x'[m] on the second coordinate system X', which indicates the distance from the mover amplitude center position Pav to the mover front end position P, is obtained by setting the constant Const. in formula (2) at 0.

Furthermore, the total mass m[kg] of the movable member, the spring constant k[N/m] of the support spring, and the displacement xini''[m] on the third coordinate system X'', which indicates the distance from the cylinder head position Psh to the mover neutral position Pini, are known values, and the driving current I can be a measured value.

Accordingly, the displacement xav'' on the third coordinate system X'', which indicates the distance from the cylinder head position Psh to the mover amplitude center position Pav,. can be calculated using formula (3).

Further, the displacement xtd''[m] on the third coordinate system X'', which indicates the top dead point position of the mover (the position where the mover is closest to the cylinder head) Ptd, can be obtained as a displacement in a position which is apart from the displacement xav'' on the third coordinate system X'' obtained by formula (3) (the distance from the cylinder head position Psh to the mover amplitude center position Pav), by a distance equal to half the already-obtained mover stroke Lps[m] (=Lps/2), toward the cylinder head.

In this way, the mover stroke length Lps[m], and the displacement xtd'' on the third coordinate system X'', which indicates the mover top dead point position Ptd as a distance from the cylinder head position Psh, are calculated from the current I and the voltage V which are applied to the linear vibration motor.

Further, as an example of the method for detecting the mover position without using the position sensor, the inventors propose a method of using a mass/spring ratio m/k, without using the spring constant k (for example, referred to Japanese Published Patent Application No. 2002-354864).

However, in the above-mentioned method of deriving the mover position according to the position arithmetic operation based on the measured values of the driving current and the driving voltage of the linear vibration motor, the result of the arithmetic operation may include an error due to dispersion among units in the spring constant k or the mass/spring ratio m/k which are used in the arithmetic operation, their variations with time, changes caused by heat, and the like.

More specifically, when the spring constant k or the mass/spring ratio m/k .alpha. varies by 10%, the calculated mover absolute position varies by more than 10%. In such case, in order to avoid the collision between the mover and the cylinder head on the basis of the position of the mover calculated by the arithmetic operation using the above-mentioned formulae, a margin of 10% or more should be given to the clearance between the mover and the cylinder head. Accordingly, the stroke of the mover cannot be enlarged up to a position in which the mover approaches a collision critical position of the mover (i.e., a position where the mover contacts the cylinder head), which has been calculated by the arithmetic operation.

Further, when the mover reciprocates in such a manner that expansion and contraction of the support spring does not exceed an expansion/contraction range that is estimated for the support spring (estimated expansion/construction range), such reciprocating motion of the mover does not cause great variations with time. However, when the mover reciprocates in such a manner that the expansion and contraction of the support spring exceeds the estimated expansion/contraction range, as in the case of malfunction of the linear vibration motor, the spring constant k or the mass/spring ratio m/k may greatly vary.

In such cases, the linear vibration motor must be replaced together with the motor driving apparatus, which leads to deterioration in the reliability of the linear vibration motor as a driving apparatus.

It is also possible to make the support spring larger to prevent the expansion and contraction of the support spring from exceeding the estimated range even in the case of malfunction of the linear vibration motor. However, by doing so, not only the outer dimension of the linear vibration motor is increased but also the production cost is increased.

SUMMARY OF THE INVENTION

The present invention has for its object to provide a motor driving apparatus which can perform position calculation for obtaining the position of the mover with great accuracy on the basis of the spring constant or the mass/spring ratio which are calculated from the natural frequency of the mover of the linear vibration motor.

Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the spirit and scope of the invention will be apparent to those of skill in the art from the detailed description.

According to a 1st aspect of the present invention, there is provided a motor driving apparatus for driving a linear vibration motor having a mover which is reciprocatably provided and a spring member which supports the mover, including: a mover force vibration unit for making the mover freely vibrate; a vibration parameter obtaining unit for obtaining a natural vibration parameter that shows natural vibration of the mover on the basis of the free vibration state of the mover; a spring constant decision unit for deciding a spring constant of the spring member using the obtained natural vibration parameter; and a mover position calculation unit for calculating the position of the mover using the spring constant that is decided by the spring constant decision unit. Therefore, the position calculation for obtaining the position of the mover can be carried out with high precision by using an accurate spring constant.

That is, according to the conventional method in which a fixed spring constant is used at the position calculation for obtaining the mover position during the operation of the linear vibration motor, the accuracy of the mover position that is obtained by the position calculation becomes low due to variations in the spring constant among different linear vibration motors, while according to the present invention, the spring constant is calculated for respective linear vibration motors, whereby the position calculation can be performed without being affected by the variations in the spring constant among different linear vibration motors. In other words, it is possible to use an accurate value of the spring constant corresponding to an individual linear vibration motor at the position calculation, thereby increasing the precision in the position calculation.

In addition, according to the present invention, the processing for calculating the spring constant is performed after assembling the linear vibration motor. Accordingly, the following effect is also achieved relative to the case where the calculation of the spring constant is performed at the assembly of the linear vibration motor.

That is, in the method of deciding the spring constant that is used at the calculation of the position of the mover at the assembling of the linear vibration motor, complicated processes for correcting the spring constant are further required at the time of assembling, and also the linear vibration motor for which the spring constant has been decided would be combined with a driving apparatus which has been adapted to the decided spring constant. Consequently, when either the linear vibration motor or the motor driving apparatus is broken, both should be changed.

In contrast, since according to the present invention the processing for calculating the spring constant is performed after assembling the linear vibration motor, the processes for correcting the spring constant at the assembly are not required. In addition, since the spring constant is decided under the state where the motor driving apparatus is combined with the linear vibration motor, even when either the linear vibration motor or the motor driving apparatus is broken, the spring constant can be decided after the broken member is changed, that is, all that is needed is only the changing of the broken member.

According to a 2nd aspect of the present inventio