Apparatus and method for controlling auto focus of camera module

Patent metadata

Field	Value
Publication number	US-9930223-B2
Application number	US-201715455060-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Mar 9, 2016
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

Disclosed are an apparatus and method for controlling auto focus of a camera module. The present invention includes a lens unit, a moving coil, a fixed coil, and a controller configured to provide a signal comprising first frequency signal and second frequency signal to the moving coil, the fixed coil receiving a variable current or a variable voltage through the second frequency signal, calculate a focus location value based on the received variable current or variable voltage and an image signal, and control the lens unit to move by applying the first frequency signal to the moving coil according to the calculated focus location value, the second frequency signal is higher than the first frequency signal and is comprised of the signal during a prescribed time.

First claim

What is claimed is:

1. A mobile terminal capable of controlling an auto focus, the mobile terminal, comprising:
a fixed unit having a hole formed therein;
a magnet placed inside the fixed unit;
a lens unit including at least one lens and configured to move;
a moving coil placed on a surface of the lens unit,
a fixed coil;
an image signal processing unit processing an image signal sensed by an image sensing unit; and
a controller configured to:
provide a first current or voltage signal to the moving coil,
wherein a second current or voltage signal is induced to the fixed coil by electromagnetic induction between the moving coil and the fixed coil, the second current or voltage signal being varied according to a distance between the moving coil and the fixed coil, and
determine a position of the lens unit for the auto focus based on the second current or voltage signal and the image signal processed by the image signal processing unit,
wherein the first current or voltage signal includes a first frequency signal and a second frequency signal,
wherein the second frequency signal has a higher frequency than the first frequency signal and is comprised of the first current or voltage signal during a prescribed time.

2. The mobile terminal of claim 1 , wherein a time slot of the first frequency signal not synthesized with the second frequency signal is in synchronization with a time slot of the processed image signal of the image signal processing unit.

3. The mobile terminal of claim 1 , wherein a time slot for processing the image signal does not overlap a time slot for providing the second frequency signal.

4. The mobile terminal of claim 1 , wherein a time slot for applying an OIS (optical image stabilizer) signal does not overlap a time slit for providing the second frequency signal.

5. The mobile terminal of claim 1 , wherein a time slot for processing the image signal, a time slot for applying an OIS (optical image sterilizer) signal, and a time slot for providing the second frequency signal do not overlap one another.

6. The mobile terminal of claim 1 , wherein if noise is detected from the image signal processed by the image signal processing unit, the controller decreases amplitude of the second frequency signal.

7. The mobile terminal of claim 1 , wherein the fixed coil is placed by being evenly spaced apart from one side of the lens unit and located on a line of a moving direction of the lens unit.

8. The mobile terminal of claim 1 , wherein the image sensing unit comprises an image sensor sensing an image incident through the at least one lens of the lens unit.

9. The mobile terminal of claim 1 , wherein the fixed coil and the image sensing unit are placed either in a manner of being spaced evenly apart from one side of the lens unit or in a manner of opposing each other with the lens unit in-between.

10. The mobile terminal of claim 1 , wherein the controller is further configured to:
detect the second current or voltage signal from the fixed coil; and
calculate the position of the lens unit for the auto focus based on the image signal processed by the image signal processing unit and the detected second current or voltage signal.

11. The mobile terminal of claim 10 , further comprising:
a half-wave rectifying unit rectifying a frequency signal for the second current or voltage signal sensed from the fixed coil into a half-wave signal;
a converting unit converting the half-wave signal received from the half-wave rectifying unit into a third current or voltage signal;
an amplifying unit amplifying a frequency signal for the third current or voltage signal converted by the converting unit; and
a peak detecting unit detecting a peak of the frequency signal amplified by the amplifying unit.

12. The mobile terminal of claim 1 , wherein a number of the fixed coil windings is different from the number of the moving coil windings.

13. The mobile terminal of claim 1 , further comprising:
a spring connectedly provided between the fixed unit and the lens unit to provide an elastic force in accordance with the movement of the lens unit.

14. A method of controlling an auto focus of a camera module the method comprising:
moving a lens unit of the camera module by applying a first current or voltage signal to a moving coil of the camera module, wherein a second current or voltage signal is induced to a fixed coil of the camera module by electromagnetic induction between the moving coil and the fixed coil, the second current or voltage signal being varied according to a distance between he moving coil and the fixed coil;
sensing an image incident on the lens;
processing the sensed image;
determining a position of the lens unit for the auto focus based on the processed image and the second current or voltage signal,
wherein the first current or voltage signal includes a first frequency signal and a second frequency signal,
wherein the second frequency signal has a higher frequency than the first frequency signal and is comprised of the first current or voltage signal during a prescribed time.

15. The method of claim 14 , wherein a time slot of the first frequency signal not synthesized with the second frequency signal is in synchronization with a time slot of the processed image.

16. The method of claim 14 , wherein a time slot for processing the image is different from a time slot for providing the second frequency signal.

17. The method of claim 14 , wherein a time slot for applying an OIS (optical image stabilizer) signal does not overlap a time slot for providing the second frequency signal.

18. The method of claim 14 , wherein a time slot for processing the image signal, a time slot for applying an OIS (optical image stabilizer) signal, and a time slot for providing the second frequency signal do not overlap one another.

19. The method of claim 14 , wherein if noise is detected from the processed image, amplitude of the second frequency signal is decreased.

20. A mobile terminal capable of controlling an auto focus, the mobile terminal, comprising:
a fixed unit having a hole formed therein;
a magnet placed inside the fixed unit;
a lens unit including at least one lens and configured to move;
a moving coil placed on a surface of the lens unit,
a fixed coil;
an image signal processing unit processing an image signal sensed by an image sensing unit; and
a controller configured to:
provide a first current or voltage signal to the moving coil, wherein a second current of voltage signal is induced to the fixed coil by electromagnetic induction between the moving coil and the fixed coil, the second current or voltage signal being varied according to a distance between the moving coil and the fixed coil, and
control the lens unit to move for the auto focus based on the second current or voltage signal and the processed image, wherein the first current or voltage signal includes a low frequency signal and a high frequency signal, and wherein the low frequency signal is for moving the lens unit and the high frequency signal is for determining a position of the lens unit for the auto focus.

Assignees

• Lg Electronics Inc

Inventors

• Park Haejin
• Kwon Sungdu
• Kwon Youngman
• Lee Jayong
• Cho Taegil
• Ji Salkmann
• Hong Samnyol

Classifications

• G02B7/08 Primary

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

• H04N23/67 Primary

  Focus control based on electronic image sensor signals · CPC title

• H04N23/6811

  based on the image signal · CPC title

• H04N23/68

  for stable pick-up of the scene, e.g. compensating for camera body vibrations · CPC title

• H02P29/64

  Controlling or determining the temperature of the winding · CPC title