Optical image stabilization in a digital still camera or handset

• US 8,170,408 B2
• Filed: 03/17/2010
• Issued: 05/01/2012
• Est. Priority Date: 05/18/2009
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Nasiri, Steven S., Kiadeh, Mansur, Zheng, Yuan, Lin, Shang-Hung, Shi, Sheena
• Primary Examiner(s): Perkey, W. B.
• Assistant Examiner(s): Smith, Linda B
• Application Number:
  US12/726,244
• Publication Number:
  US 20100290769A1
• Time in Patent Office: 776 Days
• Field of Search: 396/55, 73510-511, 348/208.6
• US Class Current: 396/55
• CPC Class Codes: G03B 17/00 Details of cameras or camera bodies; Accessories therefor lens hoods or caps G03B11/04

Abstract

An optical image stabilization system for a camera module is disclosed. The stabilization system comprises a voice coil motor (VCM), at least one digital gyroscope for receiving signals from the VCM, and an angular velocity sensor for receiving signals from the digital gyroscope and outputting an angular position error signal. The stabilization system further comprises signal processing logic for receiving the error signal, and comparing the error signal to a reference signal and providing a stabilized image based upon that comparison, wherein the hard-coded logic, digital gyroscope and rate and position sensor resides on the same chip.

Claims

1. An optical image stabilization system for a camera module comprising:

a voice coil motor (VCM),

at least one gyroscope; and

signal processing logic for receiving a signal from the at least one gyroscope and for driving the VCM, and comparing the signal to a reference signal and providing a stabilized image based upon that comparison, wherein the signal processing logic comprises a peak filter, an estimator based controller and nonlinear control, wherein the signal processing logic and the at least one gyroscope reside on the same chip.

2. The optical image stabilization system of claim 1, wherein at least one gyroscope is a digital gyroscope.

3. The optical image stabilization system of claim 1, wherein the digital gyroscope is a dual axis gyroscope.

4. The optical image stabilization system of claim 1, wherein a Hall element is not required.

5. The optical image stabilization system of claim 1, wherein signal processing logic is within the at least one gyroscope.

6. The optical image stabilization system of claim 1, wherein the signal processing logic is hard-coded.

7. The optical image stabilization system of claim 1, wherein the peak filter increases the gain of low frequency in the forward loop without effecting stability.

8. The optical image stabilization system of claim 1, wherein the peak filter comprises a pair of lightly damped poles within a bi-quad filter structure.

9. The optical image stabilization system of claim 1, wherein the signal processing logic includes notch filters.

10. The optical image stabilization system of claim 1 wherein a flexible multi-input-multi-output (MIMO) control architecture utilizes electronics and control design to overcome mechanical design limitation of x-y cross dynamic coupling.

11. The optical image stabilization system of claim 1 wherein a nonlinear control system is utilized to improve system robustness and machine intelligence is incorporated with feedback control to overcome the limitations associated with linear control systems.

12. The optical image stabilization system of claim 11 wherein the nonlinear control system transitions between three control modes:

an acceleration state, a velocity state and a position control state.

13. The optical image stabilization system of claim 11 wherein an intelligence of the nonlinear control system provides hardware protection against any failures during operations.

14. An optical image stabilization system for a camera module comprising:

a voice coil motor (VCM),

a first gyroscope for providing a first estimation of the angular position in a first direction;

a second gyroscope for providing a second estimation of the angular position in a second direction; and

an estimator based controller for receiving signals from the first and second gyroscopes and outputting an angular position signal; and

signal processing logic for receiving, and comparing the angular position signal to a reference signal to drive the VCM and providing a stabilized image based upon that comparison, wherein the signal processing logic comprises a peak filter, wherein the peak filter increases the gain of low frequency in the forward look without effecting stability, wherein the signal processing logic, and the first and second digital gyroscopes reside on the same chip.

15. The optical image stabilization system of claim 14, wherein the first and second gyroscopes are digital gyroscopes.

16. The optical image stabilization system of claim 14, wherein a Hall element is not required.

17. The optical image stabilization system of claim 14, wherein signal processing logic is within at least one of the first and second gyroscopes.

18. The optical image stabilization system of claim 14, wherein the peak filter comprises a pair of lightly damped poles within a bi-quad filter structure.

19. The optical image stabilization system of claim 14, wherein the signal processing logic includes notch filters.

20. The optical image stabilization system of claim 14, wherein the signal processing logic resides in one or more digital signal processors.

21. The optical image stabilization system of claim 14, wherein the signal processing logic is hard coded.

22. A method for providing optical image stabilization for a camera module;

the method comprising;

receiving a reference signal by a summation element;

providing a signal from the summation element to a peak filter, the peak filter provides a filtered signal to increase rejection gain of hand jitter frequencies;

providing the filtered signal to an estimator based controller, the estimator based controller provides for compensation of the filtered signals with no integrators or differentiators;

providing the compensated filtered signal to notch filters, wherein the notch filters attenuate the compensated filtered signals for gyroscope errors;

utilizing the compensated filtered signal to drive a voice coil motor (VCM) to provide a corrective movement to the camera module;

sensing the corrective movement by a gyroscope to provide a resultant signal;

providing the resultant signal to the estimator based controller to provide a compensated signal; and

providing the compensated signal to the summation element to be compared with the reference signal.