Digital camera system with piezoelectric actuators

• US 20030227560A1
• Filed: 12/10/2002
• Published: 12/11/2003
• Est. Priority Date: 06/05/2002
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Nokia Corporation
• Inventors: Johansson, Stefan, Jansson, Anders, Mattsson, Christer
• Granted Patent: US 7,212,358 B2
• Time in Patent Office: Days
• US Class Current: 348/335
• CPC Class Codes: G02B 7/022 lens and mount having complementary engagement means, e.g. screw/thread
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G02B 7/102 controlled by a microcomputer cameras with interchangeable lenses G03B17/14
• CPC Class Codes: G03B 2205/0061 using piezoelectric actuators
• CPC Class Codes: G03B 3/10 Power-operated focusing

Abstract

A digital camera is constructed with multiple lenses mounted in a pair of tubular elements which are nested together for relative axial movement. Movement is provided by piezoelectric actuators mounted externally to a support tube on flexible printed circuit board elements. Each lens tube is provided with a drive rail which extends at least partially over the length of the lens tube and projects radially outward from the periphery of each of the tubes. The rails are accessible to the engagement pads of the piezoelectric actuators to allow the transmission of drive forces to each of the tubes.

Claims

1. An adjustable support for an optical system of a digital camera comprising:

a support tube having a longitudinal axis, said support tube being secured within said camera;

a first lens tube in which at least one lens element is fixed, said first lens tube being mounted for relative movement coaxially on said support tube;

a drive rail fixed to said first lens tube and extending radially outward therefrom through a slot constructed in said support tube; and

at least one piezoelectric actuator mounted on said support tube in operative association with said drive rail, wherein said at least one piezoelectric actuator engages said drive rail to cause movement of said first lens tube along said axis.

2. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein said at least one piezoelectric actuator is mounted on a flexible printed circuit board.

3. An adjustable support for an optical system of a digital camera, as described in claim 2, wherein said printed circuit board is substantially U-shaped and further comprising:

a pair of piezoelectric actuators mounted on opposing surfaces of said U-shaped printed circuit board wherein said U-shaped printed circuit board is mounted on said support tube with said drive rail extending between said actuators.

4. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein the supporting surfaces between said lens tube and the supporting tube is very close to, or centered with, the engagement pads of the drive elements.

5. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein said lens tube is forced against said support tube by spring forces in the radial direction.

6. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein said lens tube is forced against said support with magnetic forces in the radial direction.

7. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein said drive rail is constructed with a wedge-shaped cross section having inclined engagement surfaces, wherein engagement of said at least one piezoelectric actuator exerts a radially outward force.

8. An adjustable support for an optical system of a digital camera, as described in claim 1, further comprising a position sensor mounted on said support tube in operative association with said first lens tube to monitor the axial position of said first lens tube.

9. An adjustable support for an optical system of a digital camera, as described in claim 8, wherein said position sensor comprises an optical sensor in line of sight communication with said first lens tube through said support tube.

10. An adjustable support for an optical system of a digital camera, as described in claim 8, wherein said position sensor is mounted on said flexible printed circuit board.

11. An adjustable support for an optical system of a digital camera, as described in claim 3, wherein said drive rail is constructed with a wedge-shaped cross section having inclined engagement surfaces;

and

further comprising a spring clip for securing said U-shaped printed circuit board to said support tube in a manner to exert a bias force on said U-shaped printed circuit board in a manner which tends to urge said piezoelectric actuators into engagement with said drive rail and thereby exert a radially outward force on said drive rail.

12. An adjustable support for an optical system of a digital camera, as described in claim 1, further comprising:

a second lens tube in which at least one lens element is fixed, said second lens tube being mounted on said support tube for axial movement relative to said first lens tube;

a second drive rail fixed to said second lens tube and extending radially outward therefrom through a slot constructed in said support tube; and

at least one piezoelectric actuator mounted on said support tube in operative association with said second drive rail, wherein said at least one piezoelectric actuator engages said second drive rail to cause movement of said second lens tube along said axis relative to said first lens tube.

13. An adjustable support for an optical system of a digital camera, as described in claim 12, further comprising:

multiple projections extending radially outward from said second lens tube;

travel grooves constructed in said first lens tube to receive the projections of said second lens tube for axial motion in said grooves.

14. An adjustable support for an optical system of a digital camera, as described in claim 13, wherein said projections and said travel grooves are constructed within mating surfaces which are beveled in order to maintain a consistent radial position of said second lens tube within said first lens tube.

15. An adjustable support for an optical system of a digital camera, as described in claim 1, wherein said at least one piezoelectric actuator in operative association with said second lens tube is mounted on a second flexible printed circuit board.

16. An adjustable support for an optical system of a digital camera, as described in claim 15, wherein said second flexible printed circuit board is substantially U-shaped and further comprising:

a pair of piezoelectric actuators mounted on opposing surfaces of said U-shaped printed circuit board wherein said U-shaped printed circuit board is mounted on said support tube with said second drive rail extending between said actuators.

17. An adjustable support for an optical system of a digital camera, as described in claim 12, wherein said second drive rail is constructed with a wedge-shaped cross section having inclined engagement surfaces, wherein engagement of said at least one piezoelectric actuator exerts a radially outward force on said second drive rail.

18. An adjustable support for an optical system of a digital camera, as described in claim 12, further comprising a second position sensor mounted on said support tube in operative association with said second lens tube to monitor the axial position of said second lens tube.

19. An adjustable support for an optical system of a digital camera, as described in claim 18, wherein said second position sensor comprises an optical sensor in line of sight communication with said second lens tube through said support tube.

20. An adjustable support for an optical system of a digital camera, as described in claim 18, wherein said second position sensor is mounted on said second flexible printed circuit board.

21. An adjustable support for an optical system of a digital camera, as described in claim 16, wherein said second drive rail is constructed with a wedge-shaped cross section having inclined engagement surfaces;

and

further comprising a spring clip for securing said second U-shaped printed circuit board to said support tube in a manner to exert a bias force on said second U-shaped printed circuit board in a manner which tends to urge said piezoelectric actuators into engagement with said second drive rail and thereby exert a radially outward force on said second drive rail.

22. An adjustable support for an optical system of a digital camera, as described in claim 12, wherein said first and second drive rails are spaced symmetrically around the periphery of said support tube.

23. An adjustable support for an optical system of a digital camera comprising:

a support tube having a longitudinal axis, said support tube being secured within said camera;

a first and second lens tubes each having a lens system fixed therein, said first and second lens tubes being mounted for relative movement coaxially on said support tube;

first and second drive rails fixed to said first and second lens tubes respectively, each of said drive rails extending radially outward from respective lens tubes through a slot constructed in said support tube; and

at least two piezoelectric actuators mounted on said support tube in operative association with said first and second drive rails, wherein said at least two piezoelectric actuators engage said first and second drive rails to cause axial movement of said first and second lens tubes relative to said support tube.

24. An adjustable support for an optical system of a digital camera, as described in claim 23, wherein said first and second drive rails are spaced symmetrically around the periphery of said support tube.

25. An adjustable support for an optical system of a digital camera, as described in claim 23, wherein said first and second drive rails are spaced asymmetrically around the periphery of said support tube.

26. An adjustable support for an optical system of a digital camera, as described in claim 23, wherein said support tube and said first lens tube are constructed with aligned spaces to allow said second lens tube to be assembled in a motion transverse to said support tube axis.

27. An adjustable support for an optical system of a digital camera, as described in claim 23, further comprising:

a projection extending radially outward from each of said first and second lens tubes;

a pair of travel grooves constructed in said support tube to receive the projections of said first and second lens tubes for axial motion in said grooves; and

wherein said projections and said travel grooves are constructed within mating surfaces which are beveled in order to maintain a consistent radial position of said first and second lens tubes within said support tube.

28. An adjustable support for an optical system of a digital camera, as described in claim 27, wherein said first and second drive rails are constructed with a wedge-shaped cross section having inclined engagement surfaces, wherein engagement of said piezoelectric actuators exert a radially outward forces on said first and second drive rail to maintain engagement between said projections of said first and second lens tubes and said travel grooves.

29. An adjustable support for an optical system of a digital camera, as described in claim 23, wherein said at piezoelectric actuators in operative association with said first and second lens tubes are mounted on a separate flexible printed circuit boards mounted on said support tube.

30. An adjustable support for an optical system of a digital camera, as described in claim 29, wherein said flexible printed circuit boards are substantially U-shaped and further comprising:

a pair of piezoelectric actuators mounted on opposing surfaces of each of said U-shaped printed circuit boards, wherein said U-shaped printed circuit boards are mounted on said support tube with said first and second drive rails extending between said actuators.

31. An adjustable support for an optical system of a digital camera, as described in claim 23, wherein said drive rails are constructed with a wedge-shaped cross section having inclined engagement surfaces, wherein engagement of said at piezoelectric actuators with said drive rails exerts a radially outward force on said drive rails.

32. An adjustable support for an optical system of a digital camera, as described in claim 23, further comprising a pair of position sensors mounted on said support tube in operative association with said first and second lens tubes to monitor the axial position of said first second lens tubes.

33. An adjustable support for an optical system of a digital camera, as described in claim 32, wherein said position sensors comprise optical sensors in line of sight communication with said first and second lens tubes through said support tube.

34. An adjustable support for an optical system of a digital camera, as described in claim 32, wherein said position sensors are mounted on said first and second flexible printed circuit boards.

35. An adjustable support for an optical system of a digital camera, as described in claim 30, wherein said first and second drive rails are constructed with wedge-shaped cross sections having inclined engagement surfaces;

and

further comprising a spring clip for securing said second U-shaped printed circuit board to said support tube in a manner to exert a bias force on said second U-shaped printed circuit board in a manner which tends to urge said piezoelectric actuators into engagement with said second drive rail and thereby exert a radially outward force on said second drive rail.