Display device having an array of spatial light modulators with integrated color filters

• US 20060077512A1
• Filed: 02/04/2005
• Published: 04/13/2006
• Est. Priority Date: 09/27/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Cummings, William J.
• Granted Patent: US 7,710,632 B2
• Time in Patent Office: Days
• US Class Current: 359/289
• 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: Y02D 30/70 in wireless communication networks

Abstract

By selectively placing color filters with different transmittance spectrums on an array of modulator elements each having the same reflectance spectrum, a resultant reflectance spectrum for each modulator element and it'"'"'s respective color filter is created. In one embodiment, the modulator elements in an array are manufactured by the same process so that each modulator element has a reflectance spectrum that includes multiple reflectivity lines. Color filters corresponding to multiple colors, such as red, green, and blue, for example, may be selectively associated with these modulator elements in order to filter out a desired wavelength range for each modulator element and provide a multiple color array. Because the modulator elements are manufactured by the same process, each of the modulator elements is substantially the same and common voltage levels may be used to activate and deactivate selected modulation.

Claims

1. A display region comprising:

a plurality of display elements, each of the display elements comprising a fixed surface and a moveable surface configured so as to define a cavity therebetween that is sufficiently large so that light reflected from each of the display elements has a reflectivity spectrum including multiple lines; and

a color filter associated with at least one of the display elements, wherein the color filter is configured to allow a range of wavelengths to pass through the color filter, the display region being configured so that a user views the light that passes through the color filter.

2. The display region of claim 1, wherein the fixed surface is partially reflective and the moveable surface is reflective.

3. The display region of claim 1, wherein the distance between the fixed and moveable surfaces are substantially equal in each of the plurality of display elements when the display elements are in an open state.

4. The display region of claim 1, wherein the distance between the fixed and moveable surfaces of the display elements is sufficiently large so that light incident on each of the display elements has maximum reflectivity lines in red, green, and blue visible light wavelengths.

5. The display region of claim 4, further comprising a plurality of color filters, wherein a first group of the color filters is configured to transmit wavelengths of visible light in only the red visible light wavelengths, a second group of the color filters is configured to transmit wavelengths of visible light only in the green visible light wavelengths, and a third group of the color filters is configured to transmit wavelengths of visible light only in the blue visible light wavelengths.

6. The display region of claim 1, wherein the distance between the fixed and moveable surfaces of the display elements is sufficiently large so that visible light incident on each of the display elements has maximum reflectivity lines in the ranges of about 625 to 740 nanometers, about 500 to 565 nanometers, and about 440 to 485 nanometers.

7. The display region of claim 6, further comprising a plurality of color filters, wherein a first group of the color filters is configured to transmit wavelengths of visible light only in the range of about 625 to 740 nanometers, a second group of the color filters is configured to transmit wavelengths of visible light only in the range of about 500 to 565 nanometers, and a third group of the color filters is configured to transmit wavelengths of visible light only in the range of about 440 to 485 nanometers.

8. The display region of claim 1, further comprising a plurality of color filters, wherein a first group of the color filters is configured to transmit wavelengths of light only in the range of about 610 to 630 nanometers, a second group of the color filters is configured to transmit wavelengths of light only in the range of about 530 to 550 nanometers, and a third group of the color filters is configured to transmit wavelengths of light only in the range of about 440 to 460 nanometers.

9. The display region of claim 1, wherein the distance between the fixed and moveable surface of the display elements is in the range of about 10,000 to 15,000 Angstroms.

10. The display region of claim 1, wherein the reflective surface of each of the plurality of display elements consists of the same materials.

11. An interferometric modulator configured to output multiple lines in a range of wavelengths that are visible to a human eye, the modulator comprising:

a partially reflective surface;

a reflective surface located with respect to the partially reflective surface such that a gap therebetween is sufficiently large so that light output from the interferometric modulator has a spectrum including multiple lines; and

a filter configured to transmit wavelengths of light that are only within a desired range of wavelengths, wherein the filter is disposed so as to receive light reflected from at least one of the surfaces such that the received light is transmitted through the filter toward a viewer.

12. The interferometric modulator of claim 11, wherein the gap between the partially reflective and reflective surfaces is greater than about 5000 Angstrom.

13. The interferometric modulator of claim 11, wherein the filter comprises one of a red color filter, a green color filter, and a blue color filter.

14. An interferometric modulator comprising:

a partially reflective surface;

a reflective surface;

a dielectric layer disposed between the partially reflective and reflective surfaces; and

a gap defined between the partially reflective surface and the reflective surface, wherein a gap distance is the distance between the partially reflective surface and the reflective surface;

wherein a thickness of the dielectric layer is sufficiently small such that when the modulator is in a closed state interference of a large range of wavelengths of visible light is frustrated so that the modulator reflects visible light, and wherein when the modulator is in an open state the gap distance is sufficiently large to cause destructive interference, such that the modulator substantially inhibits reflection of visible light.

15. The interferometric modulator of claim 14, wherein the dielectric thickness is less than about 100 Angstroms.

16. The interferometric modulator of claim 14, further comprising a color filter.

17. The interferometric modulator of claim 16, wherein the color filter is configured to preferentially transmit light within a range of wavelengths, wherein the range of wavelengths is selected to include at least one of the following:

red wavelengths, green wavelengths, and blue wavelengths.

18. The interferometric modulator of claim 14, further comprising a band pass filter that transmits white light.

19. The interferometric modulator of claim 14, wherein the modulator is configured so that light incident on the modulator when the gap distance is in the range of about 500 to 1200 Angstroms undergoes destructive interference.

20. A method of manufacturing an interferometric modulator, the method comprising:

fabricating a partially reflective surface;

fabricating a reflective surface, wherein a gap distance is defines as a distance between the partially reflective surface and the reflective surface;

positioning a dielectric layer between the partially reflective and reflective surfaces, wherein a thickness of the dielectric layer is sufficiently small such that when the modulator is in a closed state interference of a large range of wavelengths of visible light is frustrated so that the modulator reflects visible light, and wherein when the modulator is in an open state the gap distance is sufficiently large to cause destructive interference, such that the modulator substantially inhibits reflection of visible light.

21. An interferometric modulator manufactured by the process comprising:

fabricating a partially reflective surface;

fabricating a reflective surface, wherein a gap distance is defines as a distance between the partially reflective surface and the reflective surface;

positioning a dielectric layer between the partially reflective and reflective surfaces, wherein a thickness of the dielectric layer is sufficiently small such that when the modulator is in a closed state interference of a large range of wavelengths of visible light is frustrated so that the modulator reflects visible light, and wherein when the modulator is in an open state the gap distance is sufficiently large to cause destructive interference, such that the modulator substantially inhibits reflection of visible light.

22. A low-capacitance interferometric modulator comprising:

a reflective surface;

a partially reflective surface, said reflecting surface and said partially reflecting surface movable with respect to each other to provide an open state and a closed state for said interferometric modulator; and

a dielectric layer disposed between the partially reflective and reflective surfaces, the thickness of the dielectric layer is sufficiently large to cause reflectivity lines at about 370 nanometers and about 730 nanometers when the modulator is in the closed state.

23. The interferometric modulator of claim 22, further comprising a filter structure configured to transmit wavelengths of visible light that are within the ranges of about 420 to 650 nanometers and block said reflectivity lines at about 370 nanometers and about 730 nanometers such that when the interferometric modulator is in an actuated state, the partially reflective surface of the interferometric modulator appears substantially black to a human eye.

24. The display region of claim 23, wherein the filter structure is further configured to produce at least one of red color light, green color light, and blue color light by preferentially transmitting red, green, and blue wavelengths respectively.

25. The interferometric modulator of claim 23, wherein the filter is further configured to transmit light within a range of wavelengths, wherein the range of wavelengths is selected to include at least one of the following:

red wavelengths, green wavelengths, blue wavelengths, and white wavelengths.

26. The interferometric modulator of claim 22, wherein the dielectric layer comprises an oxide film.

27. The interferometric modulator of claim 22, wherein a thickness of the dielectric layer is in the range of about 2200 to 2500 Angstroms.

28. The interferometric modulator of claim 22, wherein a distance between the reflective surface and the partially reflective oxide layer is selected so that the interferometric modulator has a reflectance spectrum that includes at least three peaks in wavelengths that are visible to a human eye.

29. A method of manufacturing a display region comprising:

fabricating an array of display elements, each of the display elements comprising a fixed surface and a moveable surface so as to define a cavity therebetween that is sufficiently large so that light reflected from each of the display elements has a reflectivity spectrum including multiple lines;

fabricating a color filter that is configured to allow a range of wavelengths to pass through the color filter; and

coupling the color filter to at least one of the display elements so that a user views the light that passes through the color filter.

30. The method of claim 29, wherein the distance between the fixed and moveable surfaces of the display elements is sufficiently large so that light incident on each of the display elements has maximum reflectivity lines in each of the blue, green, and red wavelengths.

31. A display region, manufactured by the process of:

fabricating an array of display elements, each of the display elements comprising a fixed surface and a moveable so as to define a cavity therebetween that is sufficiently large so that light reflected from each of the display elements has a reflectivity spectrum including multiple lines;

fabricating a color filter that is configured to allow a range of wavelengths to pass through the color filter; and

coupling the color filter to at least one of the display elements so that a user views the light that passes through the color filter.

32. A display comprising:

an array of interferometric modulators each comprising

a partially reflective surface comprising a transparent conductor layer and a partially reflective layer;

a reflective surface;

a dielectric layer disposed between the partially reflective and reflective surfaces; and

a gap defined between the partially reflective surface and the reflective surface, wherein a size of the gap is selected so that each interferometric modulator has a reflectance spectrum that includes a reflectivity line centered around first order green and extending to cover at least a portion of first order blue and first order red; and

at least one color filter disposed so as to receive light reflected from the reflective surface such that the received light is transmitted through the filter toward a viewer.

33. The display of claim 32, wherein the dielectric layer has a thickness in the range of about 300 to 1000 Angstroms and the gap size is in the range of about 1400 to 2000 Angstroms.

34. The display of claim 32, wherein the at least one color filter comprises a red color filter, a blue color filter or a green color filter.

35. The display of claim 32, further comprising a plurality of color filters, each of the color filters being associated with at least one of the interferometric modulators.

36. The display of claim 32, wherein the at least one color filter includes a green color filter and a red color filter, wherein the green color filter is less absorptive of light than the red color filter.

37. The display of claim 32, wherein the at least one color filter includes a green color filter and a blue color filter, wherein the green color filter is less absorptive of light than the blue color filter.

38. The display of claim 32, wherein the reflectivity line is centered at about 520 nm.

39. The display of claim 32, wherein each interferometric modulator has a reflectance spectrum that reflects at least about 40% of light having wavelengths of about 450 nanometers, 520 nanometers, and 620 nanometers.

40. The display of claim 32, wherein the gap size of each interferometric modulator is about 2000 Angstroms.

41. A method of manufacturing a display, the method comprising:

fabricating an array of interferometric modulators each comprising a partially reflective surface, a reflective surface, a dielectric layer disposed between the partially reflective and reflective surfaces, and a gap defined between the partially reflective surface and the reflective surface, wherein a size of the gap is selected so that each interferometric modulator has a reflectance spectrum that includes a reflectivity line centered around first order green and extending to cover at least a portion of first order blue and first order red; and

fabricating at least one color filter so that the color filter transmits light within a range of wavelengths selected to include at least one of the following;

red wavelengths, green wavelengths, and blue wavelengths; and

positioning the color filter so as to receive light reflected from the reflective surface such that the received light is transmitted through the filter toward a viewer.

42. A display manufacturing by the process:

fabricating an array of interferometric modulators each comprising a partially reflective surface, a reflective surface, a dielectric layer disposed between the partially reflective and reflective surfaces, and a gap defined between the partially reflective surface and the reflective surface, wherein a size of the gap is selected so that each interferometric modulator has a reflectance spectrum that includes a reflectivity line centered around first order green and extending to cover at least a portion of first order blue and first order red; and

fabricating at least one color filter so that the color filter transmits light within a range of wavelengths selected to include at least one of the following;

red wavelengths, green wavelengths, and blue wavelengths; and

positioning the color filter so as to receive light reflected from the reflective surface such that the received light is transmitted through the filter toward a viewer.

43. An interferometric modulator comprising:

means for partially reflecting light;

means for reflecting light, wherein the means for partially reflecting and the means for reflecting are configured so as to provide a reflectivity spectrum including multiple lines; and

means for filtering only a desired one of the multiple lines for viewing by a human eye.

44. A low-capacitance interferometric modulator comprising:

a reflective surface;

a partially reflective surface;

a dielectric layer disposed between the partially reflective and reflective surfaces, wherein a thickness of the dielectric layer is sufficiently large to cause reflectivity lines at around first order red and second order blue wavelengths of visible light when the interferometric modulator is in an actuated state.

45. The low-capacitance interferometric modulator of claim 44, further comprising a filter structure configured to transmit wavelengths of visible light that are within the ranges of about 420 to 650 nanometers and block said first order blue and second order red reflectivity lines such that when the interferometric modulator is in an actuated state, the partially reflective surface of the interferometric modulator appears substantially black to a human eye.