Display device having a movable structure for modulating light and method thereof

• US 20060274074A1
• Filed: 05/23/2006
• Published: 12/07/2006
• Est. Priority Date: 05/05/1994
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Mark W. Miles
• Inventors: Miles, Mark W.
• Granted Patent: US 7,372,619 B2
• Time in Patent Office: Days
• US Class Current: 345/540
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01L 5/0047 measuring forces due to residual stresses
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2006/12109 Filter
• CPC Class Codes: G02B 2006/12126 Light absorber
• CPC Class Codes: G02B 2006/12159 Interferometer
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/08 for controlling the direction of light in light guides G02B6/35
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/13 Integrated optical circuits characterised by the manufacturing method
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/3536 involving evanescent coupling variation, e.g. by a moving element such as a membrane which changes the effective refractive index mode converters G02B6/14; adjustable lateral coupling between waveguides G02B6/283; electro- optical refractive index variations G02F1/0118
• CPC Class Codes: G02B 6/357 : Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3578 : Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/3584 : constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/43 : Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: G09G 2310/02 : Addressing, scanning or driving the display screen or processing steps related thereto
• CPC Class Codes: G09G 2310/06 : Details of flat display driving waveforms
• CPC Class Codes: G09G 3/3466 : based on interferometric effect

Abstract

An interference modulator (Imod) incorporates anti-reflection coatings and/or micro-fabricated supplemental lighting sources. An efficient drive scheme is provided for matrix addressed arrays of IMods or other micromechanical devices. An improved color scheme provides greater flexibility. Electronic hardware can be field reconfigured to accommodate different display formats and/or application functions. An IMod'"'"'s electromechanical behavior can be decoupled from its optical behavior. An improved actuation means is provided, some one of which may be hidden from view. An IMod or IMod array is fabricated and used in conjunction with a MEMS switch or switch array. An IMod can be used for optical switching and modulation. Some IMods incorporate 2-D and 3-D photonic structures. A variety of applications for the modulation of light are discussed. A MEMS manufacturing and packaging approach is provided based on a continuous web fed process. IMods can be used as test structures for the evaluation of residual stress in deposited materials.

Claims

1. A display device comprising:

a film stack deposited on a substrate; and

a movable structure connected to the substrate, the structure being movable between at least a first and a second positions, wherein the structure is configured to roll up when in the first position and configured to unroll when in the second position, wherein light incident to the display device is interferometrically modulated by the moveable structure and the film stack, when the movable structure is in the second position.

2. The display device of claim 1, wherein the display device comprises an interferometric modulator.

3. The display device of claim 1, wherein the substrate is substantially transparent.

4. The display device of claim 1, wherein the moveable structure is anisotropically stressed so that the moveable structure naturally rolls up when in the first position.

5. The display device of claim 1, wherein the moveable structure forms a plate substantially parallel to the substrate when in the second position.

6. The display device of claim 1, wherein the moveable structure comprises a reflective layer.

7. The display device of claim 1, wherein the moveable structure comprises reflective metal.

8. The display device of claim 1, wherein the moveable structure comprises aluminum.

9. The display device of claim 1, wherein the moveable structure comprises at least one of dielectrics and organic materials, the materials coated with reflective metal.

10. The display device of claim 1, wherein the display device is configured to either absorb at least a portion of incident light or reflect light of a particular wavelength when the movable structure is in each position.

11. The display device of claim 1, wherein the display device is configured to reflect white light when the movable structure is in the first position.

12. The display device of claim 1, further comprising a cavity defined by the film stack and a fixed plate.

13. The display device of claim 12, wherein light incident to the display device is interferometrically modulated, by the fixed plate and the film stack, when the movable structure is in the first position.

14. The display device of claim 12, wherein the film stack is configured such that the display device reflects no visible light or light of a particular wavelength when the movable structure is in the second position.

15. The display device of claim 12, wherein the movable structure is in the first position, when no voltage is applied between the moveable structure and the film stack.

16. The display device of claim 12, wherein the movable structure is configured to be in the second position, when a voltage is applied between the moveable structure and the film stack.

17. The display device of claim 12, wherein the moveable structure remains within the optical cavity defined by the film stack and the fixed plate when in each position.

18. The display device of claim 12, wherein the moveable structure is mechanically connected to the substrate via a support tab, the support tab being deposited on the film stack.

19. The display device of claim 18, wherein light incident on the area overlapped by the support tab and the film stack is absorbed.

20. A display device comprising:

a substrate;

a cavity defined by a film stack deposited on the substrate and a fixed plate; and

a movable structure connected to the substrate, the structure being movable between at least a first and a second positions, wherein light incident to the display device is interferometrically modulated, by the fixed plate and the film stack, when the movable structure is in the first position, and by the moveable structure and the film stack, when the movable structure is in the second position.

21. The display device of claim 20, wherein the display device comprises an interferometric modulator.

22. The display device of claim 20, wherein the substrate is substantially transparent.

23. The display device of claim 20, wherein the moveable structure comprises a reflective layer.

24. The display device of claim 20, wherein the display device is configured to either absorb at least a portion of incident light or reflect light of a particular wavelength when the movable structure is in each position.

25. The display device of claim 20, wherein the display device is configured to reflect white light when the movable structure is in the first position.

26. The display device of claim 20, wherein the film stack is configured such that the display device reflects no visible light or light of a particular wavelength when the movable structure is in the second position.

27. The display device of claim 20, wherein the moveable structure remains within the optical cavity defined by the film stack and the fixed plate when in each position.

28. The display device of claim 20, wherein the moveable structure is mechanically connected to the substrate via a support tab, the support tab being deposited on the film stack.

29. The display device of claim 28, wherein light incident on the area overlapped by the support tab and the film stack is absorbed.

30. An apparatus for driving an electronic device, said apparatus comprising:

an input to receive data; and

a driving circuit coupled to said input and configured to generate a bias voltage and data voltages from said received data, and to apply said bias voltage to rows or columns of said device, and to apply said data voltages to the columns, in the case when said bias voltage is applied to the rows, or to the rows, in the case when said bias voltage is applied to the columns,

wherein actuation of the device occurs when the difference between the values of the data voltage and a select voltage is above a first predetermined level, and release of the device occurs when the difference between the values of the data voltage and the select voltage is below a second predetermined level lowest, and wherein the device maintains its state when the select voltage is at the bias level.

31. The apparatus of claim 30, wherein said device comprises a MEMS device.

32. The apparatus of claim 30, wherein said driving circuit further comprises:

a row driver circuit and a column driver circuit for addressing said device; and

a control circuit configured to send control signals to said row and column driver circuits to select the bias voltage and data voltages to be applied by said driver circuits to rows and columns of said device.

33. The apparatus of claim 32, wherein said row driver circuit is configured to apply one of a finite set of possible voltages to said device which is selected by said control signals, and said column driver circuit is configured to apply one of a finite set of voltages to said device which is selected by said control signals.

34. The apparatus of claim 30, wherein the data voltages include two possible values, the select voltages include two possible values such that the difference between one of the select voltages and one of the data voltages is above the first predetermined level, the difference between the other of the select voltages and one of the data voltages is below the second predetermined level, and the difference between the other of the select voltages and the other of the data voltages is below the second predetermined level.

35. The apparatus of claim 30, wherein the select voltages are applied in frames, the select voltages being applied to successive rows in separate portions of each frame.

36. An apparatus for driving an electronic device, said apparatus comprising:

a row driver circuit and a column driver circuit for addressing said device; and

a control circuit configured to send control signals to said row and column driver circuits to select a bias voltage and data voltages to be applied by said driver circuits to rows and columns of said device,

wherein data voltages are applied to the columns, in the case when said bias voltage is applied to the rows, or to the rows, in the case when said bias voltage is applied to the columns,

wherein actuation of the device occurs when the difference between the values of the data voltage and a select voltage is above a first predetermined level, and release of the device occurs when the difference between the values of the data voltage and the select voltage is below a second predetermined level lowest, and

wherein the device maintains its state when the select voltage is at the bias level.

37. The apparatus of claim 36, wherein said device comprises a MEMS device.

38. The apparatus of claim 36, wherein said row driver circuit is configured to apply one of a finite set of possible voltages to said device which is selected by said control signals, and said column driver circuit is configured to apply one of a finite set of voltages to said device which is selected by said control signals.

39. The apparatus of claim 36, wherein the data voltages include two possible values, the select voltages include two possible values such that the difference between one of the select voltages and one of the data voltages is above the first predetermined level, the difference between the other of the select voltages and one of the data voltages is below the second predetermined level, and the difference between the other of the select voltages and the other of the data voltages is below the second predetermined level.

40. The apparatus of claim 36, wherein the select voltages are applied in frames, the select voltages being applied to successive rows in separate portions of each frame.