Bistable paper white direct view display

• US 6,329,967 B1
• Filed: 12/20/1999
• Issued: 12/11/2001
• Est. Priority Date: 10/28/1998
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Gifford, Eric A., Little, Michael J., Robinson, William P.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Nguyen, Jimmy H
• Application Number:
  US09/466,886
• Time in Patent Office: 722 Days
• Field of Search: 345/55, 345/108, 345/109, 345/102, 359/227, 359/233, 359/234, 359/243, 359/290, 359/291
• US Class Current: 345/55
• 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 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

A thin low power, paper white, direct-view display includes an array of bistable micromirrors that are deflected between two stable states, a dark state in which the mirror covers a portion of the background and a white state in which the mirror uncovers the background. The drive electronics are similar to those used in multiplexed LDCs but are modified in order to drive the micromirrors to one of their two stable states. The micromirrors in the enabled row are attracted up or down with sufficient force to exceed the micromirrors'"'"' bistable threshold and deflect the micromirrors to their dark and white states, respectively. The attractive forces on the micromirrors in the remaining non-enabled rows are insufficient to exceed the micromirrors'"'"' bistable threshold so that the micromirrors remain in their current stable state.

Claims

1. A direct view display, comprising:

a background; and

an array of micromirrors that are adapted to be electrostatically actuated to switch between two states, an open state in which the micromirror covers a portion of the background corresponding to a pixel of the display and a closed state in which the micromirror substantially uncovers the portion of the background, wherein said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

2. The display of claim 1, further comprising a controller that applies a potential to produce electrostatic forces for actuating the micromirrors between their two states.

3. The display of claim 2, wherein the controller applies a first potential to enable selected micromirrors for a period longer than a response time of the micromirrors, and then applies a second potential to actuate the enabled micromirrors between their open and closed states, the remaining non-enabled micromirrors remaining in their current state.

4. The display of claim 1, further comprising a stability mechanism that causes said micromirrors to remain in either of the first and second states unless and until an actuating force is applied to the micromirrors that is sufficient to overcome an actuation threshold.

5. The display of claim 4, wherein the stability mechanism comprises an array of hinges mechanically coupled to the array of micromirrors, each of the hinges having a bistable response that actuates a corresponding micromirror between the open state and the closed state and holds the micromirror in either state when power is removed from the array of micromirrors.

6. The display of claim 4, wherein the stability mechanism comprises first and second stops associated with each of the micromirrors, the first and second stops positioned so that their respective micromirror contacts the first and second stops when the respective micromirror is in the open and closed states, respectively, wherein the micromirrors and their respective first and second stops are adapted so that Van der Walls forces are created when the micromirrors contact their respective first or second stops that hold the micromirrors in either state when power is removed from the array of micromirrors.

7. The display of claim 1, further comprising a backlight, said background surface transmitting light from the backlight and reflecting ambient light.

8. The direct-view display of claim 1, wherein in the closed state the micromirror substantially uncovers the portion of the background without covering another portion of the background.

9. A direct-view display, comprising:

a background;

an array of micromirrors that are adapted to be electrostatically actuated to switch between a first stable state, in which the micromirror covers a portion of a background corresponding to a pixel of the display, and a second stable state, in which the micromirror substantially uncovers the portion of the background, in response to an actuating force; and

a stability mechanism that causes said micromirrors to remain in either stable state unless and until the actuating force applied to the micromirrors is sufficient to overcome an actuation threshold, wherein said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

10. The display of claim 9, wherein the stability mechanism comprises a bistability mechanism for maintaining said micromirrors in either stable state when power is removed from the micromirror array.

11. The display system of claim 10, further comprising a controller that applies a potential to produce electrostatic forces for actuating the micromirrors between the two stable states.

12. The display of claim 11, wherein the controller applies a first potential to enable selected micromirrors for a period longer than a response time of the micromirrors, and then applies a second potential to actuate the selected micromirrors.

13. The display of claim 10, wherein the bistable mechanism comprises an array of bistable hinges mechanically coupled to the array of micromirrors.

14. The display of claim 10, wherein the bistable mechanism comprises first and second stops associated with each of the micromirrors and positioned to contact their respective micromirror when the micromirror is in the first or second stable state, said contact creating Van der Walls forces that create the actuation threshold.

15. The direct-view display of claim 9, wherein in the second stable state the micromirror substantially uncovers the portion of the background without covering another portion of the background.

16. A direct-view display, comprising:

a background;

an array of electrostatically-actuable micromirrors that deflect with a known response time between two stable states, an open state in which the mirror covers a portion of said background corresponding to a pixel of the display and a closed state in which the mirror substantially uncovers the portion of the background, in response to an actuating force to produce a direct-view image; and

a controller that applies a first potential to enable selected micromirrors for a period longer than the mirrors'"'"' known response time and applies a second potential to produce an actuating force on the enabled micromirrors that exceeds an actuation threshold and actuate the enabled mirrors between their two stable states, the actuating forces on the remaining non-enabled micromirrors being insufficient to overcome the actuation threshold so that the non-enabled mirrors remain in their current stable state, wherein the said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

17. The direct-view display of claim 16, further comprising an array of hinges that actuate said respective micromirrors between their open and closed states, said hinges having a bistable response that actuates the micromirrors between their two stable states.

18. The direct-view display of claim 16, further comprising first and second stops that contact said micromirror in its open and closed states, respectively, wherein Van der Walls forces that occur when the micromirrors contact said stops create a bistable response.

19. The display of claim 16, wherein the controller receives updated image information, updates the direct-view image in accordance with the updated image information by applying the first and second potentials, and once the direct-view image is updated, removes power from micromirror array.

20. The direct-view display of claim 16, wherein in the closed state the micromirror substantially uncovers the portion of the background without covering another portion of the background.

21. A bistable direct-view display, comprising:

a background;

an array of micromirrors that are adapted to be electrostatically actuated to switch between two stable states, an open state in which the micromirror covers a portion of the background corresponding to a pixel of the display and a closed state in which the micromirror substantially uncovers the portion of the background; and

a bistable mechanism that causes said micromirrors to remain in either stable state unless and until an actuating force is applied to the micromirrors that is sufficient to overcome an actuation threshold, wherein said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

22. The display of claim 21, further comprising a controller that applies a first potential to enable selected micromirrors, and then applies a second potential to the micromirrors to produce actuating forces on the enabled micromirrors that are sufficient to overcome the actuation threshold and switch the enabled micromirrors between their open and closed states, but which on the remaining non-enabled micromirrors are insufficient to overcome the actuation threshold so that the non-enabled micromirrors remain in their current stable state.

23. The display of claim 22, further comprising an array of hinges mechanically coupled to the array of micromirrors, each of the hinges having a bistable response that defines the actuation threshold and actuates a corresponding micromirror.

24. The display of claim 22, further comprising first and second stops associated with each of the micromirrors, the first and second stops positioned so that their respective micromirror contacts the first and second stops when the respective micromirror is in the open and closed states, respectively, wherein the micromirrors and their respective first and second stops are adapted so that Van der Walls forces are created when the micromirrors contact their respective first or second stops that, the Van der Walls forces defining the actuation threshold.

25. The direct-view display of claim 21, wherein in the closed state the micromirror substantially uncovers the portion of the background without covering another portion of the background.

26. A bistable direct-view display, comprising:

a background;

an array of micro mirrors that are adapted to switch between two stable states, an open state in which the micromirror covers a portion of the background corresponding to a pixel of the display and a closed state in which the micromirror substantially uncovers the portion of the background;

a bistable mechanism that causes said micromirrors to remain in either stable state unless and until an actuating force is applied to the micromirrors that is sufficient to overcome an actuation threshold; and

a controller that applies a first potential to the micromirrors a row at a time to enable that row and applies a second potential to each column of micromirrors to produce an actuating force on the micromirrors in the enabled row that exceeds the actuation threshold and actuate the enabled mirrors between their two stable states, the actuating forces on the micromirrors in the remaining non-enabled rows being insufficient to overcome the actuation threshold so that the non-enabled mirrors remain in their current stable state, wherein said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

27. The display of claim 26, wherein the bistable mechanism comprises an array of hinges mechanically coupled to the array of micromirrors, each of the hinges having a bistable response that defines the actuation threshold and actuates a corresponding micromirror.

28. The display of claim 26, wherein the bistable mechanism comprises first and second stops associated with each of the micromirrors, the first and second stops positioned so that their respective micromirror contacts the first and second stops when the respective micromirror is in the open and closed states, respectively, wherein the micromirrors and their respective first and second stops are adapted so that Van der Walls forces are created when the micromirrors contact their respective first or second stops that, the Van der Walls forces defining the actuation threshold.

29. The direct-view display of claim 26, wherein in the closed state the micromirror substantially uncovers the portion of the background without covering another portion of the background.

30. A direct-view display, comprising:

a background; and

an array of micromirrors that are adapted to be electrostatically actuated to switch between two states, an open state in which the micromirror covers a portion of the background and a closed state in which the micro mirror is substantially vertically oriented to uncover the portion of the background, wherein said background has a surface that reflects ambient light, and each micromirror has an interior surface that absorbs light and an exterior surface that reflects light, said micromirrors being configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light and their exterior surfaces are exposed to reflect ambient light to and from the background.

31. The display of claim 30, further comprising a controller that applies a potential to produce electrostatic forces for actuating the micromirrors between their two states.

32. The display of claim 30, further comprising a backlight, said background surface transmitting light from the backlight and reflecting ambient light.

33. A direct-view display, comprising:

a backlight;

a translucent substrate that is illuminated by the backlight, said substrate having a surface that both reflects ambient light and transmits incident light from the backlight;

an array of micromirrors, each micromirror having an absorbent interior surface and being adapted to switch between two states, an open state in which the micromirror covers a portion of the substrate corresponding to a pixel of a display to block incident light and absorb ambient light and a closed state in which the micromirror substantially uncovers the portion of the substrate to allow ambient light to reflect off of and incident light to pass through that portion of the substrate.

34. The direct view display of claim 33, wherein each micromirror in said closed state uncovers the portion of the substrate without covering another portion of the substrate.

35. The display of claim 33, wherein each micromirror in said closed state is oriented approximately vertically to substantially uncover the portion of the substrate.

36. The display of claim 33, wherein each micromirror has a reflective exterior surface that reflect ambient light to and from the substrate when in the closed state to increase the amount of light reflected.

37. The display of claim 33, wherein said micromirrors are configured in pairs that switch together so that, in said open state, their interior surfaces absorb ambient light and, in said closed state, their interior surfaces face each other to reduce the absorption of ambient light.

38. The display of claim 37, wherein each micromirror has a reflective exterior surface that reflect ambient light to and from the substrate when in the closed state to increase the amount of light reflected.

39. The display of claim 33, wherein the micromirrors are adapted to be electrostatically actuated.

40. The display of claim 39, further comprising a controller that applies a potential to produce electrostatic forces for actuating the micromirrors between the two states.

41. The display of claim 40, wherein the controller applies a first potential to enable selected micromirrors for a period longer than a response time of the micromirrors, and then applies a second potential to actuate the selected micromirrors.

42. The display of claim 33, wherein further comprising a stability mechanism that causes said micromirrors to remain in either of the open or closed states unless and until an actuating force is applied to the micromirrors that is sufficient to overcome an actuation threshold.