Display device with micromechanical leaf spring switches

• US 4,681,403 A
• Filed: 06/19/1986
• Issued: 07/21/1987
• Est. Priority Date: 07/16/1981
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Te Velde, Ties S., Van de Venne, Joannes L. M.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Lewis, David
• Application Number:
  US06/877,696
• Time in Patent Office: 397 Days
• Field of Search: 350/334, 350/486, 350/487, 350/355, 350/356, 350/357, 307/112, 307/115, 307/117, 200/181, 200/283, 335/187, 361/207
• US Class Current: 349/41
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2201/0107 Sacrificial metal
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: G02F 1/0102 Constructional details, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• 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 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/38 using electrochromic devices
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A layer of liquid crystal is present between two supporting plates with a large number of picture electrodes arranged in rows and columns on at least one of the supporting plates. Strip-shaped row electrodes and strip-shaped column electrodes are provided between the respective rows and columns of the picture electrodes. The picture electrodes arranged in rows can be contacted with a respective row electrode by way of at least one micromechanical leaf spring which provides the liquid crystal with a sufficiently steep threshold with respect to the applied voltage, and provides the liquid crystal with a memory when the picture electrodes form picture elements of a display device. Because of this arrangement, the number of lines to be driven of the display device can be extended.

Claims

1. A display device comprising two separated supporting plates;

an electro-optical medium disposed between said supporting plates, wherein said electro-optical medium includes one of a liquid crystal, an electrophoretic suspension, or an electrochromic material;

a plurality of picture electrodes formed in rows and columns on facing surfaces of said supporting plates to form a system of picture elements;

a system of column electrodes disposed with said picture electrodes on one of said supporting plates;

a system of row electrodes disposed below said picture electrodes on a second of said supporting plates;

an insulating layer disposed between said picture electrodes and said row electrodes wherein each of said picture electrodes includes an aperture at an area over a row electrode, said row electrode being free of said insulating layer at said aperture;

switching means including at least one electrostatically controllable micromechanical leaf spring being disposed in each of said apertures for providing connection between said picture electrode and said row electrode, said micromechanical leaf spring only being a metal free of any insulating layer; and

an electrically conductive covering hood extending over said aperture to protect said leaf spring from said electro-optical medium.

2. A display device according to claim 1, wherein said picture electrodes and said covering hoods are reflecting.

3. A display device according to claim 1, wherein said picture electrodes and said column electrodes on said one supporting plate are integrated to strip-shaped electrodes.

4. A display device according to claim 1, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in series.

5. A display device according to claim 1, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in parallel.

6. A display device according to claim 1, wherein at least one of said supporting plates and said electrodes provided thereon are transparent.

7. A display device according to claim 1, wherein said electro-optical medium is a liquid crystal.

8. A display device according to claim 1, wherein said electro-optical medium is an electrophoretic suspension.

9. A display device according to claim 1, wherein said electro-optical medium is an electrochromic material.

10. A display device comprising two separated supporting plates, an electro-optical medium disposed between said supporting plates, wherein said electro-optical medium includes one of a liquid crystal, an electrophoretic suspension, or an electrochromic material;

a plurality of picture electrodes formed in rows and columns on facing surfaces of said supporting plates to form a system of picture elements;

a system of column electrodes disposed with said picture electrodes on one of said supporting plates, wherein said picture electrodes and said column electrodes on said one supporting plate are integrated to strip-shaped electrodes;

a system of row electrodes disposed with said picture electrodes on a second of said supporting plates; and

switching means including at least one electrostatically controllable micromechanical leaf spring for providing connection between said picture electrodes and said row electrodes, said micromechanical leaf spring only being a metal free of any insulating layer.

11. A display device according to claim 10, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in series.

12. A display device according to claim 10, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in parallel.

13. A display device according to claim 10, wherein at least one of said supporting plates and said electrodes provided thereon are transparent.

14. A display device according to claim 10, wherein said electro-optical medium is a liquid crystal.

15. A display device according to claim 10, wherein said electro-optical medium is an electrophoretic suspension.

16. A display device according to claim 10, wherein said electro-optical medium is an electrochromic material.

35. A display device according to claim 16, or claim 10, or claim 17, or claim 26, or claim 27, wherein said metal of said micromechanical leaf spring is nickel.

17. A display device comprising two separated supporting plates;

an electro-optical medium disposed between said supporting plates, wherein said electro-optical medium includes one of a liquid crystal, an electrophoretic suspension, or an electrochromic material;

a plurality of picture electrodes formed in rows and columns on one of said supporting plates;

a common counter electrode provided on a second of said supporting plates to form a system of picture elements with said plurality;

a system of row electrodes and column electrodes disposed on said one supporting plate, wherein at each crossing of row electrodes and column electrodes an electrically conductive bridge insulates a column electrode from a row electrode; and

switching means including at least one electrostatically controllable micromechanical leaf spring for providing connection between said column electrode and an associated picture electrode, said micromechanical leaf spring only being a metal free of any insulating layer, and said micromechanical leaf spring extending below said bridge and extending over both said row electrode and a portion of said associated picture electrode, wherein at least one end of said micromechanical leaf spring is connected to said column electrode.

18. A display device according to claim 17, wherein said micromechanical leaf spring also forms said conductive bridge.

19. A display device according to claim 18, wherein said portion of said associated picture electrode below said micromechanical leaf spring is provided on said row electrode, and wherein an insulating layer electrically insulates said associated picture electrode from said row electrode.

20. A display device according to claim 17, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in series.

21. A display device according to claim 17, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in parallel.

22. A display device according to claim 17, wherein at least one of said supporting plates and said electrodes provided thereon are transparent.

23. A display device according to claim 17, wherein said electro-optical medium is a liquid crystal.

24. A display device according to claim 17, wherein said electro-optical medium is an electrophoretic suspension.

25. A display device according to claim 17, wherein said electro-optical medium is an electrochromic material.

26. A display device comprising two separated supporting plates;

an electro-mechanical medium disposed between said supporting plates, wherein said electro-optical medium includes one of a liquid crystal, an electrophoretic suspension, or an electrochromic material;

a plurality of picture electrodes formed in rows and columns on facing surfaces of said supporting plates to form a system of picture elements;

a system of column electrodes disposed respectively between said picture electrodes on one of said supporting plates;

a system of row electrodes disposed respectively between said picture electrodes on a second of said supporting plates; and

switching means including at least one electrostatically controllable micromechanical leaf spring for providing connection between said picture electrodes and said row electrodes, said micromechanical leaf spring only being a metal free of any insulating layer.

29. A display device according to one of claims 26, 27 or 28, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in series.

30. A display device according to one of claims 26, 27 or 28, wherein each of said switching means is formed by at least two of said micromechanical leaf springs, said two micromechanical leaf springs being connected in parallel.

31. A display device according to one of claims 26, 42 or 43, wherein at least one of said supporting plates and said electrodes provided thereon are transparent.

32. A display device according to one of claims 26, 27 or 28, wherein said electro-optical medium is a liquid crystal.

33. A display device according to one of claims 26, 27 or 28, wherein said electro-optical medium is an electrophoretic suspension.

34. A display device according to one of claims 26, 27 or 28, wherein said electro-optical medium is an electrochromic material.

27. A display device comprising two separated supporting plates;

an electro-optical medium disposed between said supporting plates, wherein said electro-optical medium includes one of a liquid crystal, an electrophoretic suspension, or an electrochromic material;

a plurality of picture electrodes formed in rows and columns on one of said supporting plates;

a common counter electrode provided on a second of said supporting plates;

a system of row electrodes and column electrodes disposed on said one supporting plate, said row electrodes and said column electrodes being interspersed with said picture electrodes, and being electrically isolated from one another; and

switching means including at least one electrostatically controllable micromechanical leaf spring for providing connection between said picture electrodes and said row electrodes, said micromechanical leaf spring only being a metal free of any insulating layer.

28. A display device according to claim 27, wherein said row electrodes and said column electrodes are electrically isolated from each other at their crossings, wherein said leaf springs have fixed ends at said one supporting plate, and wherein each of said leaf springs extends over one of said row electrodes, a portion of one of said column electrodes, and a portion of an associated picture electrode.