Methods and apparatus for bi-stable actuation of displays

• US 20060187531A1
• Filed: 10/14/2005
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Barton, Roger, Hagood, Nesbitt W., Payne, Richard S., Steyn, Jasper Lodewyk
• Granted Patent: US 7,304,786 B2
• Time in Patent Office: Days
• US Class Current: 359/298
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38

Abstract

The invention relates to mechanically bi-stable shutter assemblies for use in display apparatus to form images.

Claims

1. A display apparatus comprising:

a shutter for interacting with a light in an optical path to form an image on the display apparatus;

a voltage input for receiving an actuation potential; and

an actuator, responsive to an actuation potential being applied to the voltage input, for moving the shutter from a first mechanically stable position in a plane to a second mechanically stable position in the plane.

2. The display apparatus of claim 1, wherein the actuator comprises a spring.

3. The display apparatus of claim 1, wherein the stiffness of the first compliant member varies along its length.

4. The display apparatus of claim 1, wherein the shutter comprises a plurality of shutter apertures through which light can pass.

5. The display apparatus of claim 1, wherein the actuator, responsive to a second actuation potential being applied to the voltage input, moves the shutter from one of the first and second mechanically stable states to a third mechanically stable state.

6. The display apparatus of claim 1, comprising a passive matrix array for selectively applying the actuation potential to the voltage input to form the image.

7. The display apparatus of claim 1, wherein the first compliant member includes a plurality of non-compliant members coupled by a plurality of compliant joints.

8. The display apparatus of claim 1, comprising a stabilizer having first and second mechanically stable states, wherein the movement of the shutter switches the state of the stabilizer between the first and second mechanically stable states.

9. The display apparatus of claim 1, wherein the first compliant member is shaped such that the work required to move the shutter from the first mechanically stable position to the second mechanically stable position is substantially equal to the work required to move the shutter from the second mechanically stable position to the first mechanically stable position.

10. The display apparatus of claim 1, wherein the first compliant member is shaped such that the work required to move the shutter from the first mechanically stable position to the second mechanically stable position is greater than the work required to move the shutter from the second mechanically stable position to the first mechanically stable position.

11. The display apparatus of claim 1, comprising a second actuator coupled to the shutter, wherein the second actuator has first and second mechanically stable states corresponding to the first and second mechanically stable positions of the shutter.

12. The display apparatus of claim 11, wherein the actuator couples to the shutter in a first location and the second actuator couples to the shutter in a second location.

13. The display apparatus of claim 11, wherein the actuator couples to a first side of the shutter and the second actuator couples to a second side of the shutter substantially opposite the first side.

14. The display apparatus of claim 1, comprising a first compliant member having a first mechanically stable state corresponding to the first mechanically stable position of the modulator and a second mechanically stable state corresponding to the second mechanically stable position of the modulator.

15. The display apparatus of claim 14, wherein the first compliant member comprises a first beam, and wherein in the first mechanically stable state, the first beam is bowed in a first direction, and in the second mechanically stable state, the beam is bowed in a second direction.

16. The display apparatus of claim 14, wherein the first compliant member, absent the application of force to the compliant member has a substantially straight shape.

17. The display apparatus of claim 14, wherein in both the first mechanically stable state and the second mechanically stable state, the first compliant member is substantially straight.

18. The display apparatus of claim 14, wherein, responsive to the voltage input receiving the actuation potential, the first compliant member deforms from the first stable state to the second stable state.

19. The display apparatus of claim 14, wherein moving the actuator from either of the first and second mechanically stable states requires the actuator to apply force to the first compliant member.

20. The display apparatus of claim 14, wherein the height of the compliant member is at least about 1.4 times the width of the compliant member.

21. The display apparatus of claim 14, wherein the compliant member is between about 0.5 μ

m and about 5 μ

m wide.

22. The display apparatus of claim 14, wherein the first compliant member comprises an insulator at least partially covering the first compliant member.

23. The display apparatus of claim 22, wherein the dielectric constant of the insulator is greater than or equal to about 2.

24. The display apparatus of claim 14, wherein the actuator comprises a second compliant member having a second beam with a corresponding bow.

25. The display apparatus of claim 24, wherein the first compliant member comprises a first beam having a corresponding bow, and, in the first mechanically stable state, the bow of the second beam is substantially the same as the bow of the first beam and in the second mechanically stable state, the bow of the second beam is substantially opposite the bow of the first beam.

26. The display apparatus of claim 14, wherein the first compliant member couples to the shutter to a first anchor connecting the first compliant member to a surface over which the shutter is moved.

27. The display apparatus of claim 26, wherein the first compliant member couples to a second anchor connecting the first compliant member to the surface, and wherein the first anchor connects the first compliant member to a first location on the surface and the second anchor connects the first compliant member to a second location on the surface.

28. The display apparatus of claim 26, comprising a working fluid having a dielectric constant of at least about 1.5 disposed between the first and second compliant members.

29. The display apparatus of claim 14, comprising a second compliant member having first and second mechanically stable states, and wherein in each of the first and second mechanically stable states the second compliant member is substantially straight.

30. The display apparatus of claim 29, wherein the first compliant member couples to the shutter in a first location on the shutter and the second compliant member couples to the shutter in a second location.

31. The display apparatus of claim 29, wherein the second compliant member couples to an anchor connecting the second compliant member to a surface over which the shutter is moved.

32. The display apparatus of claim 29, wherein the first and second compliant members are electrodes, which, in response to a voltage being applied across the first and second compliant members, are drawn together, thereby moving the shutter.

33. The display apparatus of claim 14, comprising a second compliant member, wherein each of the first and second compliant members includes a beam, at least one which of has a flat side facing the other of the beam.

34. The display apparatus of claim 1, wherein moving the shutter comprises rotation or translation of the shutter.

35. A method of forming an image on a display apparatus, comprising:

selectively applying an actuation potential to a voltage input;

moving a shutter, in response to the application of the actuation potential, in a plane, from a first mechanically stable position to a second mechanically stable position, thereby permitting light to contribute to the formation of an image.

36. The method of claim 35, wherein moving the shutter comprises deforming a compliant member to which the shutter is coupled.

37. The method of claim 35, wherein moving shutter comprises altering the curvature of a compliant member to which the shutter is coupled.

38. The method of claim 35, comprising, in response to the application of the actuation potential, generating a voltage across two compliant members, drawing them together.