Matrix-addressed display having micromachined electromechanical switches

• US 6,037,719 A
• Filed: 04/09/1998
• Issued: 03/14/2000
• Est. Priority Date: 04/09/1998
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Lam, Juan, Yap, Daniel, Loo, Robert Y.
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US09/057,894
• Time in Patent Office: 705 Days
• Field of Search: 315/161, 315/169.1, 315/169.2, 315/169.3, 362/800, 333/100, 333/101, 359/230, 216/41
• US Class Current: 315/169.3
• 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 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01G 5/38 Multiple capacitors, e.g. ganged
• CPC Class Codes: H01G 5/40 Structural combinations of variable capacitors with other electric elements not covered by this subclass, the structure mainly consisting of a capacitor, e.g. RC combinations
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A display includes a plurality of light-emitting devices arranged as a matrix of pixels and an addressing circuit coupled to each respective light-emitting device. The addressing circuit includes a plurality of micromachined electromechanical (MEM) switches operable to control the plurality of light-emitting devices. Each MEM switch includes a cantilever beam and a control electrode spaced therefrom to deflect the cantilever beam electrostatically in order to close or open the switch.

Claims

1. A display, comprising:

a plurality of light-emitting elements; and

a circuit coupled to each respective light-emitting element and comprising a plurality of switches operable to control the plurality of light-emitting elements;

wherein each switch of the plurality of switches comprises a cantilever beam and a control electrode spaced therefrom;

the plurality of switches including a first switch and a second switch;

the first switch being operable to couple at least one of the plurality of light-emitting elements to a power supply; and

the second switch being operable to couple the control electrode of the first switch to an input signal representative of light emission data for at least one of the plurality of light-emitting elements.

2. The display of claim 1, wherein:

the plurality of switches includes a first switch and a second switch wherein the cantiever beam of the first switch includes a conductive portion;

the conductive portion of the cantilever beam of the first switch is coupled to one of a power supply and the light emittng element when the first switch is in a first state; and

the conductive portion of the cantilever beam of the first switch being coupled to both the power supply and the light-emitting element when the first switch is in a second state.

3. The display of claim 1, wherein the cantilever beam of at least one of the plurality of switches includes a conductive portion at a floating potential.

4. The display of claim 1, wherein:

the respective cantilever beams of the first and second switches have a conductive end portion; and

the circuit further comprises;

a first line coupled to a power supply and one of the plurality of light-emitting devices and having a gap spaced from the conductive end portion of the first switch; and

a second line coupled to an input signal source and the control electrode of the first switch and having a gap spaced from the conductive end portion of the second switch.

5. The display of claim 1, wherein the plurality of switches includes a floating switch operable to couple the light-emitting element to a power supply.

6. The display of claim 5, wherein the floating switch includes a further control electrode and a further cantilever beam spaced from the further control electrode.

7. The display of claim 5, wherein the floating switch includes a further cantilever beam spaced from the control electrode.

8. The display of claim 7, wherein the circuit further comprises a line having a first branch and a second branch, the first and second branches each having a gap spaced from the first-named cantilever beam and the further cantilever beam, respectively.

9. The display of claim 8, wherein the first branch and the second branch have different widths.

10. The display of claim 8, wherein the gaps of the first and second branches have different lengths.

11. The display of claim 7, wherein:

the control electrode includes a first portion spaced from the first-named cantilever beam and a second portion spaced from the further cantilever beam; and

the second portion has a greater surface area than the first portion.

12. The display of claim 1, wherein the plurality of switches and the plurality of light-emitting elements are secured to a substrate which comprises a material selected from the group consisting of glass and plastic.

13. An electromechanical switch for use in a circuit disposed on a substrate, comprising:

a control electrode secured to the substrate;

a cantilever beam structure having a plurality of beams spaced from the substrate; and

a plurality of conductors for connecting the electromechanical switch in the circuit wherein each respective conductor comprises a disconnect associated with a corresponding beam of the plurality of beams;

wherein at least one beam of the plurality of beams is spaced from the control electrode.

14. The electromechanical switch of claim 13, further comprising a further control electrode secured to the substrate and wherein:

the plurality of beams includes a first beam and a second beam; and

the first beam and the second beam are spaced from the first-named control electrode and the further control electrode, respectively.

15. The electromechanical switch of claim 13, wherein the plurality of conductors are coupled together to compose a single line.

16. The electromechanical switch of claim 15, wherein:

the plurality of beams includes a first beam and a second beam;

the control electrode includes a first portion spaced from the first beam and a second portion spaced from the second beam; and

the second portion has a greater surface area than the first portion.

17. The electromechanical switch of claim 13, wherein the plurality of conductors includes a first conductor and a second conductor having different widths.

18. The electromechanical switch of claim 13, wherein each disconnect comprises a gap spaced from the corresponding beam.

19. The electromechanical switch of claim 18, wherein:

the plurality of conductors includes a first conductor and a second conductor; and

the respective gaps of the first and second conductors have different lengths.

20. The electromechanical switch of claim 18, wherein:

the cantilever beam structure includes a common end secured to the substrate;

each beam is coupled to the common end; and

each beam includes a conductive end portion spaced from the gap of the respective conductor and a non-conductive portion between the common end of the cantilever beam structure and the conductive end portion.

21. The electromechanical switch of claim 13, wherein the substrate comprises a material selected from the group consisting of glass and plastic.

22. The electromechanical switch of claim 13 in combination with a light-emitting element and a power supply wherein the electromechanical switch is operable to couple the light-emitting element to the power supply.

23. A circuit coupled to a first input signal source and a second input signal source for controlling a light-emitting element powered by a power supply, comprising:

a first switch having a first control electrode and a cantilever beam structure having a beam spaced from the first control electrode;

a second switch having a second control electrode coupled to the second input signal source and a cantilever beam spaced from the second control electrode wherein the cantilever beam has a conductive end portion;

a first conductor coupled to the first input signal source and the first control electrode and having a gap spaced from the conductive end portion of the cantilever beam of the second switch; and

a second conductor coupled to the power supply and the light-emitting element and having a gap spaced from the beam of the cantilever beam structure of the first switch.

24. The circuit of claim 23, wherein the light-emitting element and the circuit are secured to a substrate comprising a material selected from the group consisting of glass and plastic.

25. The circuit of claim 23, wherein:

the second input signal source comprises a clock; and

the conductive end portion of the second switch bridges the gap in the first conductor when the second input signal source supplies a clock pulse to the second control electrode of the second switch.

26. The circuit of claim 25, wherein:

the cantilever beam structure of the first switch includes a further beam; and

the second conductor includes a segment comprising a first branch and a second branch wherein each branch includes a gap spaced from the first-named beam and the further beam of the cantilever beam structure, respectively.

27. The circuit of claim 26, wherein:

the first-named and further beams include a respective conductive end portion; and

a voltage magnitude of the first input signal source is representative of the light emission intensity intended for the light-emitting element and determinative of which of the conductive end portions of the first-named and further beams will bridge the respective gaps in each of the first and second branches of the second conductor provided that the clock pulse is supplied to the second control electrode.

28. The circuit of claim 26, wherein:

the cantilever beam structure of the first switch includes a common end secured to a substrate; and

the first-named and further beams are coupled to the common end.

29. The circuit of claim 23, wherein:

the cantilever beam structure of the first switch includes a plurality of beams;

the first control electrode is one of a plurality of control electrodes of the first switch, each of which is spaced from a corresponding beam of the plurality of beams;

the first conductor is one of a plurality of lines coupling the first input signal source to the plurality of control electrodes for the first switch, respectively; and

the first input signal source supplies a digital code to the plurality of control electrodes via the plurality of lines, the digital code being representative of the light emission intensity intended for the light-emitting element.