IMAGE STABILIZATION CIRCUITRY FOR LIQUID LENS

• US 20100295987A1
• Filed: 12/12/2008
• Published: 11/25/2010
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Varioptic (Corning Incorporated)
• Inventors: Berge, Bruno
• Granted Patent: US 8,400,558 B2
• Time in Patent Office: Days
• US Class Current: 348/360
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 27/646 compensating for small deviations, e.g. due to vibration or shake movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position

Abstract

A method of controlling a liquid lens in an imaging device, the liquid lens including a liquid-liquid interface between first and second immiscible liquids deformable by electrowetting; a chamber containing the first and second liquids, the first liquid being an insulating liquid and the second liquid being a conducting liquid; and a first electrode in contact with the second liquid and at least one second electrode insulated from the second liquid by an insulating layer, the first and second electrodes being arranged to allow a plurality of voltages levels to be applied between the first and second electrodes to control the curvature of the liquid-liquid interface, the method including: determining motion data representative of a movement of the imaging device; determining focusing data representative of a desired focus of the imaging device; determining the plurality of voltage levels to be applied between the first and second electrodes, wherein each of the voltage levels is a function of the motion data, the focusing data and at least one parameter relating to the liquid lens and preliminary determined in a calibration phase.

Claims

1. A method of controlling a liquid lens in an imaging device, the liquid lens comprising a liquid-liquid interface between first and second immiscible liquids deformable by electrowetting, a chamber containing the first and second liquids, the first liquid being an insulating liquid and the second liquid being a conducting liquid, and a first electrode in contact with said second liquid and at least one second electrode insulated from said second liquid by an insulating layer, said first and second electrodes being arranged to allow a plurality of voltages levels to be applied between said first and second electrodes to control the shape of said liquid-liquid interface, the method comprising:

determining motion data representative of a movement of said imaging device;

determining focusing data representative of a desired focus of said imaging device; and

determining said plurality of voltage levels to be applied between said first and second electrodes,

wherein each of said voltage levels is a function of said motion data, said focusing data, and at least one parameter relating to the liquid lens, wherein said at least one parameter is preliminarily determined in a calibration phase.

2. The method of claim 1, wherein said step of determining said plurality of voltage levels comprises calculating each of said voltages levels based on the product of said motion data and a first parameter (α

) relating to the liquid lens, and the product of said focusing data and a second parameter (β

) relating to the liquid lens, wherein said first and second parameters are preliminarily determined in the calibration phase.

3. The method of claim 1, wherein said motion data comprises first and second values indicating a shift in a first dimension and a second dimension, respectively, of an image formed on an image sensor of said imaging device, and wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on both of said first and second values.

4. The method of claim 1, wherein said motion data comprises at least one value indicating a shift in a first dimension of an image formed on an image sensor of said imaging device, said at least one value further indicating whether said shift is in a first direction or a second direction opposite to said first direction, and wherein determining said plurality of voltage levels comprises multiplying said at least one value by a first constant when said shift is in the first direction, and multiplying said at least one value by a second constant when said shift is in the second direction.

5. The method of claim 1, wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on a function having a term comprising the product of said motion data and said focusing data.

6. The method of claim 1, wherein determining said plurality of voltage levels comprises calculating said voltage levels based on astigmatism data indicating a level of astigmatism to be applied to said lens.

14. The method of claim 1, wherein the at least one parameter is preliminarily determined in a calibration phase comprising the successive steps of:

varying said plurality of voltages until a determined focus is achieved;

applying a voltage change to a first one of said plurality of voltage levels applied at a first side of said liquid-liquid interface to cause a change in tilt of said liquid-liquid interface in a first direction;

varying a second one of said plurality of voltage levels applied to a second side of said liquid-liquid interface opposite to said first side to cause a change in tilt of said liquid-liquid interface in said first direction until said determined focus is achieved again; and

measuring the extent of said tilt to determine said at least one parameter.

15. The method of claim 3, wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on a function having a term dependent on the product of said first value and second value of said motion data.

16. The method of claim 15, wherein said function is a square root function.

7. An imaging device comprising:

a liquid lens comprising;

a liquid-liquid interface between first and second immiscible liquids deformable by electrowetting;

a chamber containing the first and second liquids, the first liquid being an insulating liquid and the second liquid being a conducting liquid; and

at least one first electrode in contact with said second liquid and at least one second electrode insulated from said second liquid by an insulating layer,

said first and second electrodes being arranged to allow a plurality of voltage levels to be applied between said first and second electrodes to control the shape of said liquid-liquid interface;

a processor arranged to receive motion data representative of a motion of said imaging device and focusing data representative of a desired focus of said imaging device, and to determining said plurality of voltage levels based on said motion data,

said focusing data, and at least one parameter relating to said liquid lens, wherein the at least one parameter is preliminarily determined in a calibration phase; and

a drive circuitry arranged to apply said determined plurality of voltage levels between said first and second electrodes.

8. The imaging device of claim 7, wherein said liquid lens comprises a plurality of second electrodes, each of said plurality of voltage levels being applied between said first electrode and one of said plurality of second electrodes.

9. The imaging device of claim 7, wherein said motion data comprises first and second values indicating a shift in a first and a second dimensions respectively of an image formed on an image sensor of said imaging device, and wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on said first and second values.

10. The imaging device of claim 7, wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on a function having a term dependent on the product of said motion data and said focusing data.

11. The imaging device of claim 7, wherein said second electrode comprises an annular body formed of a material having a conductivity in the range 10⁴ to 10⁷ Ohm·

cm.

12. A mobile telephone comprising an image sensor, a processor, a display, and the imaging device of claim 7.

13. A digital camera comprising an image sensor, a processor, and the imaging device of claim 7.

17. The imaging device of claim 9, wherein determining said plurality of voltage levels comprises determining at least one of said voltage levels based on a function having a term dependent on the product of said first value and second value of said motion data.

18. The imaging device of claim 17, wherein said function is a square root function.

19. The imaging device of claim 7, wherein the at least one parameter is preliminarily determined in a calibration phase comprising successive steps of:

varying said plurality of voltages until a determined focus is achieved;

applying a voltage change to at least one of said plurality of voltage levels to cause a change in tilt of said liquid-liquid interface in a first direction;

varying at least one of said plurality of voltage levels to cause a change of the shape of the liquid-liquid interface until said determined focus is achieved again and until an astigmatism lower to a given value is achieved; and

measuring the extent of said tilt to determine said at least one parameter.