VEHICULAR CAMERA WITH VARIABLE FOCUS CAPABILITY

• US 20140036084A1
• Filed: 04/17/2012
• Published: 02/06/2014
• Est. Priority Date: 04/18/2011
• Status: Active Grant

• Current Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Original Assignee: Magna Electronics Incorporated (Magna International Incorporated)
• Inventors: Lu, Yuesheng
• Granted Patent: US 9,376,066 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G02B 7/028 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• 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

Abstract

A vehicular camera has a lens assembly, a housing and an image sensor. The lens assembly has at least one adjustable lens and a lens adjustment structure. The lens assembly has an effective focal length and an optical axis associated therewith and an effective distance from the image sensor. A controller may be operatively connected to the lens adjustment structure for controlling the operation of the lens adjustment structure. The lens adjustment structure is controllable to adjust at least one of an effective focal length and an effective distance of the lens assembly to the image sensor, so as to control the distance at which an object in the field of view of the camera appears in focus on the image sensor.

Claims

1. :

A camera for a vehicle, comprising;

a housing;

an image sensor positioned in the housing;

a lens assembly including at least one adjustable lens;

a lens adjuster,

wherein the lens adjuster is operable to control at least one property of the lens assembly selected from the group including;

(i) an effective focal length of the lens assembly and (ii) an effective distance of the lens assembly from the image sensor; and

a controller that is operable to control the operation of the lens adjuster.

2. :

A camera as claimed in claim 1, wherein the at least one adjustable lens is movable axially along an optical axis of the lens assembly by the lens adjuster.

3. :

A camera as claimed in claim 2, wherein the lens adjuster includes a piezo actuator.

4. :

A camera as claimed in claim 3, wherein the lens assembly includes a lens barrel which holds the at least one adjustable lens, and wherein the piezo actuator has a first end that is connected to the controller and a second end that is connected to a shoulder on the lens barrel.

5. :

A camera as claimed in claim 4, wherein the lens barrel has an outer surface that is slidable axially on an inner surface of the housing and along an optical axis of the lens assembly, and wherein the lens assembly further includes a seal that is positioned on the outer surface of the lens barrel and that engages the inner surface of the housing to limit intrusion of contaminants past the seal and into an interior of the housing.

6. :

A camera as claimed in claim 1, wherein the at least one adjustable lens comprises a liquid lens having at least one lens surface having a radius of curvature that is adjustable via application of a range of voltages thereto to adjust the focal distance of the liquid lens.

7. :

A camera as claimed in claim 1, wherein the at least one adjustable lens comprises a liquid crystal lens that has an index of refraction that is adjustable via application of a range of voltages thereto to adjust the focal length of the liquid crystal lens.

8. :

A camera as claimed in claim 1, wherein the lens assembly further includes at least one fixed lens that is positioned inboard of the at least one adjustable lens, wherein the at least one adjustable lens is electrically connected to the controller via an electrical conduit that is applied to an inner surface of the housing.

9. :

A camera as claimed in claim 1, wherein the controller is operable to receive input from a temperature sensor and to control the operation of the lens adjuster based on the input from the temperature sensor.

10. :

A camera as claimed in claim 1, wherein the lens adjuster is selectively operable to vaporize water droplets at a surface of the lens assembly.

11. :

A camera as claimed in claim 10, wherein the lens adjuster comprises a piezo actuator.

12. :

A camera as claimed in claim 11, wherein the controller is operable to process captured images to detect water droplets at the surface of the lens assembly and wherein the controller is operable to activate the lens adjuster to vaporize water droplets responsive to a detection of water droplets at the surface of the lens assembly.

13. :

A method of focusing a camera, said method comprising;

(a) providing a camera having a housing, an image sensor and a lens assembly;

(b) positioning a test image in the field of view of the camera;

(c) powering the camera;

(d) adjusting the value at least one property of the lens assembly, wherein the at least one property of the lens assembly comprises at least one of (i) an effective focal length of the lens assembly and (ii) an effective distance of the lens assembly from the image sensor;

(e) capturing an image of the test image using the camera;

(f) determining if the quality of the captured image exceeds a selected quality threshold;

(g) iteratively repeating steps (d), (e) and (f) until the quality of the camera image exceeds the selected quality threshold; and

(h) storing data related to the adjusted value of the at least one property of the lens assembly that results in the quality of the camera image exceeding the selected quality threshold.

14. :

A method as claimed in claim 13, wherein the camera includes a lens adjuster and the lens assembly includes at least one adjustable lens that is adjustable via the lens adjuster, and wherein adjustment of a voltage applied to the lens adjuster causes adjustment of the value of at least one property of the lens assembly in step (d).

15. :

A method as claimed in claim 14, wherein the value of the voltage applied to the lens adjuster that results in the camera image exceeding the quality threshold is stored in step (h).

16. :

A method as claimed in claim 13, wherein adjusting the value of at least one property of the lens assembly comprises actuating an actuator that is operable to adjust the value of at least one property of the lens assembly.

17. :

A method as claimed in claim 16, further comprising actuating said actuator to vaporize water droplets at a surface of the lens assembly.

18. :

A method as claimed in claim 17, wherein said actuator comprises a piezo actuator.

19. :

A method as claimed in claim 18, wherein actuating said actuator to vaporize water droplets comprises actuating said actuator responsive to a detection of water droplets at the surface of the lens assembly.

20. :

A method as claimed in claim 13, wherein the camera includes a lens adjuster and wherein the lens assembly includes an adjustable lens that is movable axially along an optical axis of the lens assembly by the lens adjuster.