Display device

• US 6,011,528 A
• Filed: 11/28/1994
• Issued: 01/04/2000
• Est. Priority Date: 11/28/1993
• Status: Expired due to Fees

• Current Assignee: Smartlight Ltd.
• Original Assignee: Smartlight Ltd.
• Inventors: Shaffir, Fran, Levy, Ben Zion, Inbar, Dan, Wolf, Hanan
• Primary Examiner(s): Brier, Jeffery
• Assistant Examiner(s): Kovalick, Vincent E.
• Application Number:
  US08/348,959
• Time in Patent Office: 1,863 Days
• Field of Search: 40/361, 359/53, 359/36, 359/250, 359/251, 359/252, 359/254, 359/485, 359/488, 359/489, 359/493, 359/599, 345/87, 345/33, 345/34, 345/38, 345/55, 345/77, 345/78, 345/84, 345/102, 345/118
• US Class Current: 345/77
• CPC Class Codes: G02B 27/026 and a display device, e.g. CRT, LCD, for adding markings or signs or to enhance the contrast of the viewed object
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13336 Combining plural substrates to produce large-area displays, e.g. tiled displays

Abstract

A transparency viewing device including a faceplate adapted for mounting at least one transparency thereon, a passive matrix LCD array comprising a plurality of row electrodes and a plurality of column electrodes separated by liquid crystal material, one of said plurality of electrodes having N electrodes and the other of said plurality of electrodes having M electrodes whereby the intersections of the row and column electrodes define a matrix of M×N pixel elements arranged in rows and columns, which pixels are excited by an RMS voltage difference between the two electrodes intersecting a pixel and a driver which electrifies the row and column electrodes such that at least one of a plurality n of the N electrodes or a plurality m of the M electrodes are identically electrified, wherein n≦N and m≦M.

Claims

1. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a backlit passive matrix LCD array comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of M×

N pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which identically electrifies a plurality of row electrodes which excite identical patterns of pixels, and which identically electrifies a plurality of column electrodes which excite identical patterns of pixels, wherein each of said patterns of pixels includes at least one pixel which is to be activated, and

wherein said voltage difference at each of the pixel elements is an RMS voltage having only one of two values.

2. A transparency viewing device according to claim 1 wherein the ratio of the two values is greater than 3.

3. A transparency viewing divide according to claim 1 wherein the ratio of the two values is greater than 5.

4. A transparency viewing device according to claim 1 wherein the ratio of the two values is greater than 50.

5. A transparency viewing device according to claim 1 wherein one of the values is substantially equal to zero.

6. A transparency viewing device according claim 1 wherein the electrification of at least one of the N electrodes is substantially the same as the electrification of one of the M electrodes.

7. A transparency viewing device according to claim 1 wherein at least some of said N electrodes or said M electrodes are not contiguous.

8. A transparency viewing device according to claim 1 wherein the excitation of the electrodes comprises pulsed voltages.

9. A transparency viewing device according to claim 1 wherein the pixel elements are transparent in the absence of an exciting voltage.

10. A transparency viewing device according to claim 1 and also comprising a second passive LCD array underlying said first array.

11. A transparency viewing device according to claim 1 wherein at least one matrix array comprises a plurality, r, of LC layers and a plurality, r+1, of polarizers, one of the polarizers being located between each adjoining pair of said layers and one polarizer being located at each outside surface of the outer ones of said layers.

12. A transparency viewing device according claim 1 wherein the LCD array is backlighted by a source of light and including a brightness enhancing (BE) device which accepts light at a relatively large angle from the normal to the LC device and which transmits the major portion of the accepted light through a relatively limited angle around the normal to the LCD array for which the LCD is substantially effective to selectively block the light and a lesser portion of the light at a range of angles around an off-normal angle far from the normal at which the LCD is not effective to block the light, said BE device being situated between the source and the LCD array.

13. A transparency viewing device according to claim 12 including a light detector which views the array, from an angle within the off-normal range of angles.

14. A transparency viewing device according to claim 1 wherein said passive LCD array is a normally bright LCD array and further comprising a normally dark passive LCD passive array underlying the normally bright array.

15. A transparency viewing device according to claim 1 wherein each of the patterns of pixels also includes at least one pixel which is not to be activated.

16. A transparency viewing device according to claim 1 wherein the row electrodes are electrified in two groups, each group having all those row electrodes which excite identical patterns of pixels.

17. A transparency viewing device according to claim 16 wherein the column electrodes are electrified in two groups, each group having all those column electrodes which excite identical patterns of pixels.

18. A transparency viewing device according claim 1 wherein all of the row electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified and wherein all of the column electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified.

19. A transparency viewing device according to claim 1 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

20. A transparency viewing device according to claim 19 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

21. A transparency viewing device according to claim 20 wherein the reference angles of the overlying and underlying arrays are oriented at a 180°

to each other.

22. A transparency viewing device according to claim 1 wherein the second LCD array comprises a matrix of pixel elements which are offset from the matrix of pixel elements of the overlying array. the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

23. A transparency viewing device according to claim 1 wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels including at least one pixel which is not to be activated and wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels all of whom are to be activated.

24. A viewing device comprising:

an overlying LCD matrix array and an underlying matrix array, each array comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of M×

N pixel elements arranged in N rows and M columns, and wherein the width of the electrodes is greater than the space between adjacent electrodes; and

a driver which selectively drives the electrodes thereby to change the optical transmission of the pixel elements, wherein the pixel elements of the overlying and underlying arrays are offset from each other.

25. A viewing device according to claim 24 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

26. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

an LCD array defining an array of pixels;

a driver which selectively varies the transparency of the pixels;

a source of back lighting for the LCD array;

a brightness enhancing (BE) device which accepts light at a relatively large angle from the normal to the LCD array and which transmits the major portion of the accepted light through a relatively limited angle around the normal to the LCD array for which the LCD is substantially effective to selectively block the light and a lesser portion of the light at a range of angles around an off-normal angle far from the normal at which the LCD is not effective to block the light, said BE device being situated between the source and the LCD array; and

a light detector which views the array, from an angle within the off-normal range of angles.

27. A transparency viewing device according to claim 26 wherein the detector is an imaging detector.

28. A transparency viewing device comprising:

a viewing surface;

a normally bright LCD array underlying the viewing surface;

a normally dark LCD array underlying the normally bright LCD array; and

a source of backlighting underlying the normally dark LCD array.

29. A transparency viewing device according to claim 28 wherein the normally bright LCD array and the normally dark LCD array are passive LCD arrays.

30. A transparency viewing device according to claim 28 and further comprising a diffuser intermediate the normally bright and normally dark arrays and spaced from the normally dark LCD array.

31. A transparency viewing device according to claim 30 wherein said diffuser is spaced by 1-10 mm from the normally dark LCD.

32. A transparency viewing device according to claim 30 wherein said diffuser is spaced by 2-8 mm from the normally dark LCD.

33. A transparency viewing device according to claim 30 wherein said diffuser is spaced by approximately 5 mm from the normally dark LCD.

34. A transparency viewing device according to claim 30 wherein the space is air filed.

35. A viewing device according to claim 30, wherein the diffuser substantially preserves the polarization of light passing through it.

36. A viewing device according to claim 28, wherein the normally bright and normally dark LC arrays are matrix arrays having different resolutions.

37. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which identically electrifies, using a non-scanning mode, row electrodes which excite identical patterns of pixels, and which identically electrifies, using a non-scanning mode, column electrodes which excite identical patterns of pixels.

38. A transparency viewing device according to claim 37, wherein each of said patterns of pixels includes at least one pixel which is to be activated and one pixel which is not to be activated.

39. A transparency viewing device according to claim 37 wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels including at least one pixel which is not to be activated and wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels all of whom are to be activated.

40. A transparency viewing device according to claim 37 wherein the row electrodes are electrified in two groups, each group having all those row electrodes which excite identical patterns of pixels.

41. A transparency viewing device according to claim 40 wherein the column electrodes are electrified in two groups, each group having all those column electrodes which excite identical patterns of pixels.

42. A transparency viewing device according claim 37 wherein all of the row electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified and wherein all of the column electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified.

43. A transparency viewing device according claim 37 wherein said voltage difference at each of the pixel elements is an RMS voltage difference having only one of two values.

44. A transparency viewing device according to claim 43 wherein the ratio of the two values is greater than 3.

45. A transparency viewing device according to claim 43 wherein the ratio of the two values is greater than 5.

46. A transparency viewing device according to claim 43 wherein the ratio of the two values is greater than 50.

47. A transparency viewing device according to claim 43 wherein one of the values is substantially equal to zero.

48. A transparency viewing device according to claim 37 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

49. A transparency viewing device according to claim 37 wherein at least some of the identically electrified row electrodes are not contiguous.

50. A transparency viewing device according to claim 37 wherein at least some of the identically electrified column electrodes are not contiguous.

51. A transparency viewing device according to claim 37 wherein the excitation of the electrodes comprises pulsed voltages.

52. A transparency viewing device according to claim 37 wherein the pixel elements are transparent in the absence of an exciting voltage.

53. A transparency viewing device according to claim 37 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

54. A transparency viewing device according to claim 53 wherein the second LCD array comprises a matrix of pixel elements which are offset from the matrix of pixel elements of the overlying array.

55. A transparency viewing device according to claim 54 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

56. A transparency viewing device according to claim 55 wherein the reference angles of the overlying and underlying arrays are oriented at a 180°

to each other.

57. A transparency viewing device according to claim 37 and including a brightness enhancing (BE) device which accepts light at a relatively large angle from the normal to the LC device and which transmits the major portion of the accepted light through a relatively limited angle around the normal to the LCD array for which the LCD is substantially effective to selectively block the light and a lesser portion of the light at a range of angles around an off-normal angle far from the normal at which the LCD is not effective to block the light, said BE device being situated between the source and the LCD array.

58. A transparency viewing device according to claim 57, and including a light detector which views the array from an angle within the off-normal range of angles.

59. A transparency viewing device according to claim 37 wherein said passive LCD array is a normally bright LCD array and further comprising a normally dark passive LCD passive array underlying the normally bright array.

60. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which identically electrifies at least one row electrode and one at least one column electrode.

61. A transparency viewing device according to claim 60 wherein the at least one row electrode includes a plurality of row electrodes.

62. A transparency viewing device according to claim 61 wherein at least some of the identically electrified row electrodes are not contiguous.

63. A transparency viewing device according to claim 62 wherein at least some of the identically electrified column electrodes are not contiguous.

64. A transparency viewing device according to claim 60 wherein the at least one column electrode includes a plurality of column electrodes.

65. A transparency viewing device according to claim 64 wherein at least some of the identically electrified column electrodes are not contiguous.

66. A transparency viewing device according to claim 60 wherein the excitation of the electrodes comprises pulsed voltages.

67. A transparency viewing device according to claim 60 wherein the pixel elements are transparent in the absence of an exciting voltage.

68. A transparency viewing device according to claim 60 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

69. A transparency viewing device according to claim 68 wherein the second LCD array comprises a matrix of pixel elements which are offset from the matrix of pixel elements of the overlying array.

70. A transparency viewing device according to claim 68 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

71. A transparency viewing device according to claim 70 wherein the reference angles of the overlying and underlying arrays are oriented at a 180°

to each other.

72. A transparency viewing device cording to claim 60 and including a brightness enhancing (BE) device which accepts light at a relatively large angle from the normal to the LC device and which transmits the major portion of the accepted light through a relatively limited angle around the normal to the LCD array for which the LCD is substantially effective to selectively block the light and a lesser portion of the light at a range of angles around an off-normal angle far from the normal at which the LCD is not effective to block the light, said BE device being situated between the source and the LCD array.

73. A transparency viewing device according to claim 72, and including a light detector which views the array from an angle within the off-normal range of angles.

74. A transparency viewing device according to claim 60 wherein said passive LCD array is a normally bright LCD array and further comprising a normally dark passive LCD passive array underlying the normally bright array.

78. A viewing device according to claim 74, wherein the normally bright and normally dark LC arrays are matrix arrays having different resolutions.

75. A viewing device comprising:

a viewing surface;

a first liquid crystal (LC) matrix array underlying the viewing surface;

a second LC matrix array underlying the first LC array; and

a source of backlighting underlying the second LC array, wherein the first and second matrix arrays have different resolutions.

76. A viewing device according to claim 75 wherein the first and second LC arrays are passive LC arrays.

77. A viewing device according to claim 75, wherein the viewing surface is adapted for mounting a transparency thereon.

79. A viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LC array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which electrifies p groups of row electrodes, each group containing a plurality of row electrodes which excite identical patterns of pixels, and which electrifies, q groups of column electrodes, each group containing a plurality of column electrodes which excite identical patterns of pixels, wherein

at least one of said p groups and at least one of said q groups contains a plurality of electrodes having a pattern of pixels including at least one pixel which is to be activated and one pixel which is not to be activated;

all the electrodes in a group are identically electrified;

2≦

p, 2<

q and at least one of p and q are greater than 2, and

at least one some of the identically electrified row electrodes are not contiguous.

80. A viewing device according to claim 79, wherein p=q=3.

81. A viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LC array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which electrifies, using a non-scanning mode, p groups of row electrodes, each group containing all those row electrodes which excite identical patterns of pixels, and which electrifies, q groups of column electrodes, each group containing all those column electrodes which excite identical patterns of pixels, wherein

all the electrodes in a group are identically electrified; and

2≦

p, 2≦

q and at least one of p and q are greater than 2.

82. A viewing device according to claim 81 wherein at least one of said p groups and at least one of said q groups contains a plurality of electrodes having a pattern of pixels including at least one pixel which is to be activated and one pixel which is not to be activated.

83. A viewing device according to claim 82, wherein p=q=3.

84. A viewing device according to claim 82 wherein at least some of the identically electrified column electrodes are not contiguous.

85. A viewing device according to claim 81, wherein p=q=3.

86. A liquid crystal array comprising:

an input polarizer;

an array of addressable liquid crystal elements;

an output polarizer; and

a diffuser situated between the liquid crystal elements and the output polarizer.

92. A transparency viewing device comprising:

a faceplate adapted for mounting at least one transparency thereon;

a source of back lighting;

a passive matrix LCD array situated intermediate the source of back lighting and the faceplate and comprising a plurality, N, of row electrodes and a plurality, M, of column electrodes separated by liquid crystal material, wherein the intersections of the row and column electrodes define a matrix of N×

M pixel elements arranged in N rows and M columns, which pixels can be excited by a voltage difference between the two electrodes intersecting a pixel; and

a driver which identically electrifies, all those row electrodes which excite identical patterns of pixels, and which identically electrifies all those column electrodes which excite identical patterns of pixels.

87. A liquid crystal array accor(1in(i to claim 96 wherein the diffuser is spaced from the liquid crystal elements.

88. A liquid crystal array according to claim 87 wherein the diffuser is spaced by 1-10 mm from the liquid crystal elements.

89. A liquid crystal array according to claim 87 wherein the diffuser is spaced by 2-8 mm from the liquid crystal elements.

90. A liquid crystal array according to claim 87 wherein the diffuser is spaced by approximately 5 mm from the liquid crystal elements.

91. A liquid crystal array according to claim 87 wherein the space is air filed.

93. A transparency viewing device according to claim 92, wherein each of said patterns of pixels includes at least one pixel which is to be activated and one pixel which is not to be activated.

94. A transparency viewing device according to claim 92 wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels including at least one pixel which is not to be activated and wherein one of the plurality of identically electrified row electrodes and one of the plurality of identically electrified column electrodes has a pattern of pixels all of whom are to be activated.

95. A transparency viewing device according to claim 92 wherein the row electrodes are electrified in two groups, each group having all those row electrodes which excite identical patterns of pixels.

96. A transparency viewing device according to claim 95 wherein the column electrodes are electrified in two groups, each group having all those column electrodes which excite identical patterns of pixels.

97. A transparency viewing device according claim 92 wherein all of the row electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified and wherein all of the column electrodes which intersect pixel elements which are to be excited and pixel elements which are not excited are identically electrified.

98. A transparency viewing device according claim 92 wherein said voltage difference at each of the pixel elements is an RMS voltage difference having only one of two values.

99. A transparency viewing device according to claim 98 wherein the ratio of the two values is greater than 3.

100. A transparency viewing device according to claim 98 wherein the ratio of the two values is greater than 5.

101. A transparency viewing device according to claim 98 wherein the ratio of the two values is greater than 50.

102. A transparency viewing device according to claim 98 wherein one of the values is substantially equal to zero.

103. A transparency viewing device according to claim 92 wherein the electrification of at least one of the N electrodes is substantially identical to the electrification of one of the M electrodes.

104. A transparency viewing device according to claim 92 wherein at least some of the identically electrified row electrodes are not contiguous.

105. A transparency viewing device according to claim 92 wherein at least some of the identically electrified column electrodes are not contiguous.

106. A transparency viewing device according to claim 92 wherein the excitation of the electrodes comprises pulsed voltages.

107. A transparency viewing device according to claim 92 wherein the pixel elements are transparent in the absence of an exciting voltage.

108. A transparency viewing device according to claim 92 wherein the distance between adjoining electrodes is substantially less than the width of the electrodes and further comprising a second passive LCD array underlying said first array.

109. A transparency viewing device according to claim 108 wherein the second LCD array comprises a matrix of pixel elements which are offset from the matrix of pixel elements of the overlying array.

110. A transparency viewing device according to claim 109 wherein the angular dependence of the transmission of the LCD array is a function of the viewing angle relative to a reference angle and wherein the underlying array is oriented with its reference angle at an angle different from that of the overlying array.

111. A transparency viewing device according to claim 110 wherein the reference angles of the overlying and underlying arrays are oriented at a 180°

to each other.

112. A transparency viewing device according to claim 92 and including a brightness enhancing (BE) device which accepts light at a relatively large angle from the normal to the LC device and which transmits the major portion of the accepted light through a relatively limited angle around the normal to the LCD array for which the LCD is substantially effective to selectively block the light and a lesser portion of the light at a range of angles around an off-normal angle far from the normal at which the LCD is not effective to block the light, said BE device being situated between the source and the LCD array.

113. A transparency viewing device according to claim 112, and including a light detector which views the array from an angle within the off-normal range of angles.

114. A transparency viewing device according to claim 92 wherein said passive LCD array is a normally bright LCD array and further comprising a normally dark passive LCD passive array underlying the normally bright array.