Polarization manipulating device modulator with retarder stack which preconditions light for modulation and isotropic states

• US 6,049,367 A
• Filed: 05/09/1997
• Issued: 04/11/2000
• Est. Priority Date: 05/23/1995
• Status: Expired due to Term

• Current Assignee: RealD Incorporated
• Original Assignee: ColorLink, Incorporated (RealD Incorporated)
• Inventors: Sharp, Gary D., Johnson, Kristina M.
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US08/853,909
• Time in Patent Office: 1,068 Days
• Field of Search: 349/97, 349/117, 349/18, 349/119, 349/106, 359/256, 359/245, 359/246
• US Class Current: 349/117
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/0136 for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation G02F1/0353 takes precedence
• CPC Class Codes: G02F 1/0322 Arrangements comprising two or more independently controlled crystals
• CPC Class Codes: G02F 1/09 based on magneto-optical elements, e.g. exhibiting Faraday effect
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• CPC Class Codes: G02F 1/23 for the control of the colour G02F1/03 - G02F1/21 take precedence
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4
• CPC Class Codes: G02F 2413/08 with a particular optical axis orientation
• CPC Class Codes: H04N 5/66 Transforming electric information into light information scanning details H04N3/00
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3111 for displaying the colours sequentially, e.g. by using sequentially activated light sources sequential projection in colour photography G03B33/08
• CPC Class Codes: H04N 9/3126 for spatial light modulators in series
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

The present invention provides a high brightness subtractive color filter formed by an electro-optic modulator positioned between two retarder stacks. The second retarder stack echoes the first retarder stack, having the same sequence of retardances but in reverse order and having an orientation rotated with respect to the first stack. The modulator changes the apparent orientation of the second stack so that, in a first switching state of the modulator the two stacks cooperate in filtering the spectrum of input light, and in a second switching state they vanish, leaving white light. Two or more stages can be used in series, each stage providing independent analog control of a primary color. One preferred embodiment eliminates internal polarizers between stages, thereby providing a full-color display with only two neutral polarizers. Hybrid filters can be made using the filter of this invention in combination with other active or passive filters. The color filters of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array and can be optically addressed.

Claims

1. A device for manipulating at least partially polarized light, comprising:

a retarder stack comprising at least two retarders, wherein at least one of the retarders in the retarder stack comprises a first retarder that has a retardance and an orientation with respect to said at least partially polarized light, so that said retarder stack receives said at least partially polarized and outputs transformed light which includes a first portion having a predetermined first spectrum with a first polarization and a second portion having a predetermined second spectrum with a second polarization; and

a modulator that receives said transformed light and outputs resulting modulator output light, wherein said modulator is adapted to affect the state of polarization of said first portion differently than said second portion.

2. The device as claimed in claim 1, wherein said modulator modulates said first portion more that said second portion.

3. The device as claimed in claim 1, wherein said modulator modulates said first portion and does not modulate said second portion.

4. The device as claimed in claim 1, wherein said modulator comprises at least a first state and said modulator appears more isotropic to one of said first portion than said second portion when said modulator is in said at least first state.

5. The device as claimed in claim 1, wherein said first and second polarizations are linear polarizations.

6. The device as claimed in claim 1, wherein said first and second polarizations are elliptical polarizations.

7. The device as claimed in claim 1, wherein said first and second polarizations are circular polarizations.

8. The device as claimed in claim 3, wherein said first and second polarizations are not equal or perpendicular.

9. The device as claimed in claim 1, wherein said modulator comprises an electro-optic modulator.

10. The device as claimed in claim 2, wherein said modulator comprises an electro-optic modulator.

11. The device as claimed in claim 3, wherein said modulator comprises an electro-optic modulator.

12. The device as claimed in claim 11, wherein said electro-optic modulator modulates said first portion of said transformed light in accordance with a modulating voltage, while said second portion of said transformed light is not modulated.

13. The device as claimed in claim 9, wherein said electro-optic modulator comprises a liquid crystal.

14. The device as claimed in claim 10, wherein said electro-optic modulator comprises a liquid crystal.

15. The device as claimed in claim 11, wherein said electro-optic modulator comprises a liquid crystal.

16. The device as claimed in claim 9, wherein said electro-optic modulator comprises a nematic liquid crystal.

17. The device as claimed in claim 16, wherein said electro-optic modulator comprises one of a twisted nematic (TN), super twist nematic (STN), an electrically controlled birefringent (ECB), optically controlled birefringent (OCB), aligned nematic, hybrid field effect (HFE), hybrid and surface mode device material.

18. The device as claimed in claim 9, wherein said electro-optic modulator comprises a pi-cell device.

19. The device as claimed in claim 9, wherein said electro-optic modulator comprises one of a pi-cell, a zero-twist mode, a hybrid mode effect, and a polymer dispersed liquid crystal device.

20. The device as claimed in claim 9, wherein said electro-optic modulator comprises a smectic liquid crystal.

21. The device as claimed in claim 10, wherein said electro-optic modulator comprises a smectic liquid crystal.

22. The device as claimed in claim 9, wherein said electro-optic modulator comprises a chiral smectic material.

23. The device as claimed in claim 9, wherein said electro-optic modulator comprises SmC*.

24. The device as claimed in claim 9, wherein said electro-optic modulator comprises one of a surface stabilized FLC and a volume stabilized FLC.

25. The device as claimed in claim 9, wherein said electro-optic modulator comprises one of a SmA*-electroclinic, distorted helix ferroelectric, anti-ferroelectric, flexoelectric, and achiral ferroelectric liquid crystal.

26. The device as claimed in claim 1, wherein said modulator comprises a magneto-optic modulator.

27. The device as claimed in claim 2, wherein said modulator comprises a magneto-optic modulator.

28. The device as claimed in claim 3, wherein said modulator comprises a magneto-optic modulator.

29. The device as claimed in claim 1, wherein at least one of said at least two retarders comprises a polymer retarder.

30. The device as claimed in claim 1, wherein each of said at least two retarders comprises a liquid crystal polymer retarder.

31. The device as claimed in claim 1, wherein at least one of said at least two retarders comprises one of a polymer birefringent material and a liquid crystal.

32. The device as claimed in claim 1, wherein at least one of said at least two retarders comprises a birefringent crystal such as calcite, quartz, or LiNbO₃.

33. The device as claimed in claim 1, wherein said modulator is adapted to modulate said first portion of transformed light in an analog fashion.

34. The device as claimed in claim 1, wherein said modulator is adapted to modulate the polarization of said first portion in an analog fashion.

35. The device as claimed in claim 1, wherein said second spectrum is complementary to said first spectrum.

36. The device as claimed in claim 1, wherein said first portion of transformed light is affected by at least one modulation state of said modulator and said second portion of transformed light is not affected by said at least one modulation state.

37. The device as claimed in claim 1, wherein said first and second polarizations are not equal.

75. The device as claimed in claim 1, wherein at least one of said first and second spectra comprise a color spectrum.

76. The device as claimed in claim 1, wherein a spectrum of said at least partially polarized input light comprises a white light spectrum.

77. The device as claimed in claim 1, wherein said at least partially polarized input light has an initial spectrum which is not a white light spectrum, and at least one of said first and second spectra is within said initial spectrum.

78. The device as claimed in claim 1, wherein at least one of said first and second spectra comprises a saturated spectrum.

79. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a color spectrum.

80. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises at least one primary color.

81. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a band of frequencies with multiple peaks.

82. The device as claimed in claim 78, wherein said output light comprises light having a sufficiently low resolution to isolate a desired band of frequencies.

83. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a series of high contrast peaks.

84. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a band of frequencies with at least one transmission peak with a normalized value greater than 0.5.

85. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a spectrum which is at least approximately 20% saturated.

86. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a spectrum which is at least approximately 40% saturated.

87. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a spectrum which is at least approximately 70% saturated.

88. The device as claimed in claim 78, wherein said at least one saturated spectrum comprises a spectrum which is at least approximately 90% saturated.

89. The device as claimed in claim 78, wherein said retarder stack and said modulator are arranged such that said at least one saturated spectrum exhibits a selectable degree of saturation.

90. The device as claimed in claim 1, wherein at least one of said first and second spectra comprises a spectrum having a selectable degree of saturation.

91. The device as claimed in claim 1, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 20% saturated.

92. The device as claimed in claim 1, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

93. The device as claimed in claim 1, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 70% saturated.

94. The device as claimed in claim 93, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

38. A device for manipulating at least partially polarized light, comprising:

a first retarder having a first retardance and a first orientation with respect to said at least partially polarized light that receives said at least partially polarized light and outputs transformed light;

a second retarder having a second retardance and a second orientation with respect to said at least partially polarized light that receives said initially transformed light and transforms it to output light comprising a first portion of output light having a first spectrum with a first polarization and a second portion of output light having a second spectrum with a second polarization, wherein said first and second orientations are different; and

a modulator that receives said output light and outputs modulator output light, wherein said modulator is adapted to modulate said first portion of output light differently than said second portion of output light.

39. The device as claimed in claim 38, wherein said modulator has at least one state in which said output light is not modulated and has at least one state in which one of said first and second portions of output light is modulated and the rest of said output light is not modulated.

40. The device as claimed in claim 38, wherein said first retarder and said second retarder are arranged such that the first and second polarizations are not orthogonal.

41. The device as claimed in claim 38, wherein said first retarder and said second retarder are arranged such that the first and second polarizations are orthogonal.

42. The device as claimed in claim 40, wherein the at least partially polarized light is partially linearly polarized and the first polarization of the first spectrum is not perpendicular to the second polarization of the second spectrum.

43. The device as claimed in claim 41, wherein the at least partially polarized light is partially linearly polarized and the first polarization of the first spectrum is perpendicular to the second polarization of the second spectrum.

44. The device as claimed in claim 40, wherein the at least partially polarized light is partially elliptically polarized and the first polarization of the first spectrum is not orthogonal to the second polarization of the second spectrum.

45. The device as claimed in claim 38, wherein said modulator comprises an electro-optic modulator.

46. The device as claimed in claim 45, wherein said electro-optic modulator modulates said first portion of output light in accordance with a modulating voltage, while said second portion of output light is not modulated.

47. The device as claimed in claim 45, wherein said electro-optic modulator comprises a liquid crystal.

48. The device as claimed in claim 45, wherein said electro-optic modulator comprises a nematic liquid crystal.

49. The device as claimed in claim 45, wherein said electro-optic modulator comprises one of a twisted nematic (TN), super twist nematic (STN), an electrically controlled birefringent (ECB), and a hybrid field effect (HFE) material.

50. The device as claimed in claim 45, wherein said electro-optic modulator comprises a surface mode device.

51. The device as claimed in claim 45, wherein said electro-optic modulator comprises one of a pi-cell, a zero-twist mode, a hybrid mode effect, and a polymer dispersed liquid crystal device.

52. The device as claimed in claim 45, wherein said electro-optic modulator comprises a smectic liquid crystal.

53. The device as claimed in claim 45, wherein said electro-optic modulator comprises a chiral smectic material.

54. The device as claimed in claim 45, wherein said electro-optic modulator comprises SmC*.

55. The device as claimed in claim 45, wherein said electro-optic modulator comprises one of a surface stabilized FLC and a volume stabilized FLC.

56. The device as claimed in claim 45, wherein said electro-optic modulator comprises one of SmA*-electroclinic, distorted helix ferroelectric, anti-ferroelectric, flexoelectric, and achiral ferroelectric liquid crystal.

57. The device as claimed in claim 38, wherein said modulator comprises a magneto-optic modulator.

58. The device as claimed in claim 38, wherein at least one of first retarder and said second retarder comprises a polymer retarder.

59. The device as claimed in claim 38, wherein at least one of said first retarder and said second retarder comprises a liquid crystal polymer retarder.

60. The device as claimed in claim 38, wherein at least one of said first retarder and said second retarder comprises one of a polymer birefringent material and a liquid crystal.

61. The device as claimed in claim 38, wherein at least one of said first retarder and said second retarder comprises a birefringent crystal such as calcite, quartz, or LiNbO₃.

62. The device as claimed in claim 38, wherein said modulator is adapted to modulate said first portion of output light in an analog fashion.

63. The device as claimed in claim 38, wherein said modulator is adapted to modulate the polarization of said first portion of output light in an analog fashion.

64. The device as claimed in claim 63, wherein said second spectrum is complementary to said first spectrum.

65. The device as claimed in claim 38, further comprising a liquid redirector for receiving said modulator output light and returning said modulator output light to serve as modulator input light to said modulator, whereby said modulator receives said modulator input light and outputs second-passed modulator output light.

66. The device as claimed in claim 65, wherein said second-passed modulator output light is received by said first and second retarders, which transform said second-passed modulator output light into second transformed light.

67. The device as claimed in claim 65, wherein said light redirector comprises a reflector.

68. The device as claimed in claim 65, wherein said light redirector comprises a plurality of reflectors.

69. The device as claimed in claim 63, wherein said modulator comprises a switchable quarter-wave-plate.

70. The device as claimed in claim 39, further comprising a light redirector for receiving said modulator output light and returning said modulator output light to serve as modulator input light to said modulator, whereby said modulator receives said modulator input light and outputs second-passed modulator output light.

71. The device as claimed in claim 65, wherein said second-passed modulator output light is received by said second retarder which transforms said second-passed modulator output light into third transformed light which is received by said first retarder which transforms said third transformed light into fourth transformed light.

72. The device as claimed in claim 65, wherein said light redirector comprises a reflector.

73. The device as claimed in claim 65, wherein said light redirector comprises a plurality of reflectors.

74. The device as claimed in claim 65, wherein said modulator comprises a switchable quarter-wave-plate.

95. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a color spectrum.

96. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum having a selectable degree of saturation.

97. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 20% saturated.

98. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 40% saturated.

99. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 70% saturated.

100. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum which is at least approximately 90% saturated.

101. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

102. The device as claimed in claim 38, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 97 nm.

103. A device for manipulating at least partially polarized light having a polarization direction, comprising:

a retarder stack comprising at least two retarders, including a first retarder and a second retarder, said first retarder having a first retardance and a first orientation with respect to the polarization direction of the at least partially polarized light, said second retarder having a second retardance and a second orientation with respect to the polarization direction of the at least partially polarized light; and

a modulator that is adapted to affect at least one polarization state differently than another polarization state;

wherein said first retarder, said second retarder and said modulator are optically coupled to each other and arranged such that the at least partially polarized light is transformed into output light which includes at least a first portion having a predetermined first spectrum with a first polarization and a second portion having a predetermined second spectrum with a second polarization.

104. The device of claim 103, wherein at least one of said first and second spectra comprises a spectrum having a selectable degree of saturation.

105. The device of claim 103, wherein one of said first and second spectra comprises a spectrum which is at least approximately 20 percent saturated.

106. The device of claim 103, wherein one of said first and second spectra comprises a spectrum which is at least approximately 40 percent saturated.

107. The device of claim 103, wherein one of said first and second spectra comprises a spectrum which is at least approximately 70 percent saturated.

108. The device of claim 105, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

109. The device of claim 106, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

110. The device of claim 107, wherein at least one of said first and second spectra comprises a spectrum with a full-width-half-maximum of at least 70 nm.

111. A device for manipulating at least partially polarized light having a polarization direction, comprising:

a retarder stack comprising at least two linear retarder films, including a first linear retarder film and a second linear retarder film, said first linear retarder film having a first retardance and a first orientation with respect to the polarization direction of the at least partially polarized light, said second linear retarder film having a second retardance and a second orientation with respect to the polarization direction of the at least partially polarized light; and

a liquid crystal modulator that is adapted to affect at least one polarization state differently than another polarization state;

wherein said at least two linear retarder films and said modulator are optically coupled to each other and arranged such that the at least partially polarized light is transformed into output light which includes at least a first portion having a predetermined first spectrum with a first polarization and a second portion having a predetermined second spectrum with a second polarization.

112. The device of claim 111, further comprising a neutral polarizer, positioned on an input side of the retarder stack, that receives input light and outputs the at least partially polarized light.

113. The device of claim 112, wherein the predetermined first spectrum comprises a blue spectrum and the predetermined second spectrum comprises a yellow spectrum.

114. The device of claim 112, wherein the predetermined first spectrum comprises a red spectrum and the predetermined second spectrum comprises a cyan spectrum.

115. The device of claim 111, wherein the liquid crystal modulator comprises a nematic liquid crystal modulator.

116. The device of claim 115, wherein at the nematic liquid crystal modulator comprises a twisted nematic liquid crystal modulator.

117. The device of claim 115, wherein the at least two linear retarder films comprise at least five linear retarder films.

118. The device of claim 117, further comprising:

a first neutral polarizer positioned on an input side of the retarder stacks, that receives input light and outputs the at least partially polarized light; and

a second neutral polarizer positioned to analyze the output light.

119. The device of claim 117, further comprising a neutral polarizer, positioned on an input side of the retarder stack, that receives input light and outputs the at least partially polarized light.

120. The device of claim 119, wherein the predetermined first spectrum comprises a blue spectrum and the predetermined second spectrum comprises a yellow spectrum.

121. The device of claim 119, wherein the predetermined first spectrum comprises a red spectrum and the predetermined second spectrum comprises a cyan spectrum.

122. The device of claim 119, further comprising a neutral polarizer, positioned on an input side of the retarder stack, that receives input light and outputs the at least partially polarized light.

123. The device of claim 122, wherein at least a portion of the input light includes a range of wavelengths between approximately 415 nm and approximately 500 nm, and wherein the intensity of the first portion of output light is at least 20% of the intensity of the input light between said range of wavelengths.

124. The device of claim 122, wherein at least a portion of the input light includes a range of wavelengths between approximately 440 nm and approximately 500 nm, and wherein the intensity of the first portion of output light is at least 35% of the intensity of the input light between said ranges of wavelengths.

125. A display device for receiving at least partially polarized light having a polarization direction, comprising:

a retarder stack comprising at least two retarder, including a first retarder and a second retarder, said first retarder having a first retardance and a first orientation with respect to the polarization direction of the least partially polarized light, said second retarder having a second retardance and a second orientation with respect to the polarization direction of the at least partially polarized light; and

a reflective display unit adapted to affect at least one polarization state differently than another polarization state at each pixel;

wherein said first retarder, said second retarder and said reflective display unit are optically coupled to each other and arranged such that light that passes through said retarder stack to said reflective display unit and back through said retarder stack is transformed into output light which includes a first portion having a predetermined first spectrum and a first polarization and a second portion having a predetermined second spectrum and a second polarization.

126. The display device of claim 125, wherein said reflective display unit comprises:

a reflector; and

a transmissive display positioned between the reflector and the retarder stack.

127. The display device of claim 126, wherein said transmissive display comprises a liquid crystal display.

128. The display device of claim 127, wherein said liquid crystal display comprises a polysilicon display.

129. The display device of claim 127, wherein said liquid crystal display comprises a TFT display.

130. The display device of claim 126, wherein said reflective display unit further comprises a waveplate positioned between the transmissive display and the reflector.

131. The display device of claim 125, wherein said reflective display unit comprises a liquid crystal on silicon display.

132. The display device of claim 125, wherein said reflective display unit comprises:

a DMD; and

a modulator positioned between the retarder stack and the DMD.

133. The display device of claim 125, wherein said reflective display unit comprises a passive matrix display.

134. The display device of claim 125, wherein said reflective display comprises a diffractive grating device.