Controller of linear motion device and control method of the same

Patent metadata

Field	Value
Publication number	US-9612600-B2
Application number	US-201314396182-A
Country	US
Kind code	B2
Filing date	May 8, 2013
Priority date	May 17, 2012
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

The present disclosure relates to controllers of linear motion devices and control methods of the same, in particular, to a controller of a linear motion device and a control method of the same capable of controlling the position of the linear motion device accurately, in a case where a misalignment of the mounting position of a magnetic sensor or a magnetizing variation of a magnet occurs, or in a case where a magnetic field detected by the magnetic sensor receives an interference of the magnetic field generated by a driving coil of the linear motion device.

First claim

The invention claimed is:

1. A controller of a linear motion device including a magnet attached to a moving body and disposed adjacent to a driving coil, the controller comprising:
a magnetic field sensor configured to detect a magnetic field generated by the magnet and output a detection position signal value corresponding to a value of the magnetic field;
a calibration operation circuit configured to obtain the detection position signal value and generate a detection position operation signal value;
a device position instruction signal generation circuit configured to output a target position signal value for instructing a target position to which the linear motion device is to move;
a leak magnetic field correction circuit configured to correct the target position signal value and output a target correction position signal value;
a PID control circuit configured to output a control signal based on the detection position operation signal value and the target correction position signal value; and
an output driver configured to supply a driving current to the driving coil to move the moving body to the target position based on the control signal,
wherein the leak magnetic field correction circuit is configured to correct the target position signal value based on the control signal and a value of a leak magnetic field caused by the driving coil, and the value of the leak magnetic is calculated based on a difference between the detection position signal value when an electric power is not supplied to the driving coil and the detection position signal value when the electric power is supplied to the driving coil.

2. The controller of the linear motion device according to claim 1 , wherein the leak magnetic field correction circuit is configured to correct the target position signal value based on the value of the leak magnetic field and a maximum value of the control signal.

3. The controller of the linear motion device according to claim 2 , wherein the leak magnetic field correction circuit is configured to operate a leak magnetic field correction amount by use of the control signal and a coefficient obtained by dividing the value of the leak magnetic field with the maximum value of the control signal, and to subtract the leak magnetic field correction amount from the target position signal value to correct the target position signal value.

4. The controller of the linear motion device according to claim 1 , further comprising an Analog/Digital (A/D) converter circuit configured to perform an A/D conversion on a detection position signal that has been detected by a magnetic field sensor configured to detect the magnetic field generated by the magnet, and to output the detection position signal value,
wherein the output driver comprises a Proportional Integral Derivative or Differential (PID) control circuit configured to output the control signal based on the detection position signal value and the target position signal value that has been corrected by the leak magnetic field correction circuit.

5. The controller of the linear motion device according to claim 1 , wherein the calibration operation circuit calculates the value of the leak magnetic field.

6. The controller of the linear motion device according to claim 1 ,
wherein the detection position signal value that is VPROC has a proportional relationship to (Vip−NEGCAL)/(POSCAL−NEGCAL), where Vip is the detection position signal value from the calibration operation circuit, NEGCAL is a first position signal value deriving from the detection position signal value and corresponding to a first position of the linear motion device, POSCAL is a second position signal value deriving from the detection position signal and corresponding to a second position of the linear motion device, and VPROC is the detection position signal value that is an output signal value from the calibration operation circuit.

7. The controller of the linear motion device according to claim 6 , wherein the value of the magnetic field that is LEAKB has a proportional relationship to (POSCAL−POSCAL′)/(POSCAL−NEGCAL) or (NEGCAL′−NEGCAL)/(POSCAL−NEGCAL), where NEGCAL′ derives from the detection position signal and is the first position signal value when influenced by the leak magnetic field, and POSCAL′ derives from the detection position signal and is the second position signal value when influenced by the leak magnetic field.

8. The controller of the linear motion device according to claim 7 , wherein the calibration operation circuit comprises:
a first memory device configured to store the first position signal value NEGCAL′ or the second position signal value POSCAL′;
a second memory device configured to store the first position signal value NEGCAL;
a third memory device configured to store the second position signal value POSCAL;
a first subtractor configured to subtract the first position signal value NEGCAL stored in the second memory device from the detection position signal value Vip;
a second subtractor configured to subtract the first position signal value NEGCAL stored in the second memory device from the second position signal value POSCAL stored in the third memory device;
a third subtractor configured to subtract the first position signal value NEGCAL stored in the second memory device from the first position signal value NEGCAL′ stored in the first memory device, or subtract the second position signal value POSCAL′ stored in the first memory device from the second position signal value POSCAL stored in the third memory device;
a first divider configured to divide an output value (Vip−NEGCAL) from the first subtractor with the output value (POSCAL−NEGCAL) from the second subtractor; and
a second divider configured to divide an output value (NEGCAL′−NEGCAL) from the third subtractor with an output value (POSCAL−NEGCAL) from the second subtractor, or divide an output value (POSCAL−POSCAL′) from the third subtractor with the output value (POSCAL−NEGCAL) from the second subtractor.

9. The controller of the linear motion device according to claim 8 , wherein the leak magnetic field correction circuit comprises:
a divider configured to divide the value of the magnetic field with the maximum value of the control signal stored in a memory device;
a multiplier configured to multiple an output value from the divider by the control signal of the output driver; and
a subtractor configured to subtract the device position instruction signal generation circuit from an output value from the multiplier from the target position signal value,
wherein the leak magnetic field correction circuit is configured to output a target correction position signal value in which the target position signal value is corrected.

10. The controller of the linear motion device according to claim 1 , wherein the magnetic field sensor is a Hall element.

11. The controller of the linear motion device according to claim 1 , wherein the linear motion device and the driving coil are configured to be incorporated into a camera module.

12. A calibration method of a controller of a linear motion device, the linear motion device comprising a driving coil configured to move the linear motion device; a magnetic field sensor configured to detect a magnetic field of the magnet, the calibration method comprising:
supplying a drive current to the driving coil to move the linear motion device to a first position;
obtaining in the first position a detection position signal value corresponding to a value of the magnetic field that has been detected by the magnetic field sensor, when an electric power is supplied to the driving coil;
obtaining in the first position the detection po

Assignees

• Asahi Kasei Microdevices Corp

Inventors

• Fukushima Takashi

Classifications

• G05B6/02

  electric · CPC title

• H02P25/06

  Linear motors · CPC title

• G05D3/1481 Primary

  with discrete position sensor · CPC title

• H02P2203/00

  Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor · CPC title

• G02B7/08 Primary

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