Apparatus for controlling position of voice coil motor using voltage/frequency conversion techniques

Patent metadata

Field	Value
Publication number	US-10554163-B2
Application number	US-201816144070-A
Country	US
Kind code	B2
Filing date	Sep 27, 2018
Priority date	Nov 1, 2017
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

An apparatus for controlling a position of a voice coil motor (VCM) includes a coil disposed to face a magnetic member provided on one surface of a lens carrier; a driving circuit applying a superimposed current, including a driving current and a position detecting current, to the coil; a filter circuit extracting an alternating current (AC) voltage from a voltage across the coil; a voltage/frequency conversion circuit converting the AC voltage extracted by the filter circuit into a frequency signal; and a digital control circuit detecting positional information of the VCM based on a frequency component of the frequency signal.

First claim

What is claimed is:

1. An apparatus for controlling a position of a voice coil motor (VCM), the apparatus comprising:
a coil disposed to face a magnetic member that is provided on one surface of a lens carrier;
a driving circuit configured to apply a superimposed current, including a driving current and a position detecting current, to the coil;
a filter circuit configured to extract an alternating current (AC) voltage from a voltage across the coil;
a voltage/frequency conversion circuit configured to convert the AC voltage extracted by the filter circuit into a frequency signal; and
a digital control circuit configured to detect positional information of the VCM based on a frequency component of the frequency signal.

2. The apparatus of claim 1 , wherein the position detecting current includes a specific frequency component, and
the specific frequency component is used to measure a change in impedance of the coil.

3. The apparatus of claim 1 , wherein the position detecting current has one of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave waveform.

4. The apparatus of claim 1 , wherein the voltage/frequency conversion circuit includes a voltage controlled oscillator that is configured to generate the frequency signal, the frequency signal having a frequency based on a magnitude of the AC voltage extracted by the filter circuit.

5. The apparatus of claim 1 , wherein the digital control circuit is configured to perform one or both of position controlling of the VCM and position correction controlling of the VCM through the driving circuit, based on the positional information.

6. An apparatus for controlling a position of a voice coil motor (VCM), the apparatus comprising:
a coil disposed to face a magnetic member provided on one surface of a lens carrier;
a driving circuit configured to apply a superimposed current, including a driving current and a position detecting current, to the coil;
a filter circuit configured to extract a first alternating current (AC) voltage from a voltage between a middle tap of the coil and one end of the coil and to extract a second AC voltage from a voltage between the middle tap of the coil and the other end of the coil;
a voltage/frequency conversion circuit configured to convert the first AC voltage extracted by the filter circuit into a first frequency signal and to convert the second AC voltage extracted by the filter circuit into a second frequency signal; and
a digital control circuit configured to detect positional information of the VCM based on a first frequency component of the first frequency signal and a second frequency component of the second frequency signal.

7. The apparatus of claim 6 , wherein the position detecting current includes a specific frequency component, and
the specific frequency component is used to measure an amount of change in impedance of the coil.

8. The apparatus of claim 6 , wherein the position detecting current has one of a sinusoidal wave, a triangle wave, a sawtooth wave, and a square wave waveform.

9. The apparatus of claim 6 , wherein the coil comprises a first coil between the middle tap and the one end of the coil, and a second coil between the middle tap and the other end of the coil,
the first coil is configured to provide the first AC voltage based on a change in impedance caused by a change in a position of the magnetic member, and
the second coil is configured to provide the second AC voltage based on impedance that is not changed, even in the case that the position of the magnetic member is changed.

10. The apparatus of claim 9 , wherein the digital control circuit is configured to perform a subtraction operation or a division operation on the first frequency signal and the second frequency signal to remove a change in a signal according to noise and a change in temperature.

11. The apparatus of claim 6 , wherein the coil includes a first coil between the middle tap and the one end of the coil, and a second coil between the middle tap and the other end of the coil, and
the second coil has impedance that is blocked from being affected by a change in a position of the magnetic member by a shielding member provided between the second coil and the magnetic member.

12. The apparatus of claim 6 , wherein the voltage/frequency conversion circuit includes a voltage controlled oscillator configured to generate the first frequency signal based on a magnitude of the first AC voltage and to generate the second frequency signal based on a magnitude the second AC voltage.

13. The apparatus of claim 6 , wherein the digital control circuit is configured to perform predetermined signal processing using the first frequency signal and the second frequency signal to remove noise included in the first frequency signal and the second frequency signal before detecting the positional information.

14. The apparatus of claim 6 , wherein the digital control circuit is configured to perform one or both of position controlling of the VCM and position correction controlling of the VCM through the driving circuit, based on the positional information.

15. The apparatus of claim 6 , wherein a first inductance between the middle tap of the coil and the one end of the coil is set to be greater than a second inductance between the middle tap of the coil and the other end of the coil.

16. An apparatus for controlling a voice coil motor (VCM), the apparatus comprising:
a coil disposed to face a magnetic member;
a filter circuit configured to extract an alternating current (AC) voltage from a voltage across the coil and to output the AC voltage;
a voltage/frequency conversion circuit configured to generate a frequency signal and to output the frequency signal, the frequency signal having frequency based on a magnitude of the AC voltage output from the filter circuit; and
a digital control circuit configured to perform one or both of position controlling and position correction controlling of the VCM based on the frequency signal output from the voltage/frequency conversion circuit.

Assignees

• Samsung Electro Mech

Inventors

• Park Jung Eui
• Choi Woo Young
• Lee Joo Hyoung
• Ko Joo Yul

Classifications

• H02P6/00

  Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor (vector control H02P21/00) · CPC title

• H02P25/034 Primary

  Voice coil motors (voice coil motors driven by DC H02P7/025) · CPC title

• G02B7/04

  with mechanism for focusing or varying magnification · CPC title

• G02B7/08

  adapted to co-operate with a remote control mechanism · CPC title