Window, a method for displaying a character on a window, and a visual display panel

• US 20040160388A1
• Filed: 12/12/2003
• Published: 08/19/2004
• Est. Priority Date: 06/12/2001
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: Vlyte Innovations Limited
• Inventors: OʼKeeffe, Donal Martin
• Granted Patent: US 7,259,730 B2
• Time in Patent Office: Days
• US Class Current: 345/30
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G09F 9/35 being liquid crystals G09F9/302 takes precedence; liquid crystal materials C09K19/00; liquid crystal panels comprising a number of electrodes in a single cell per se G02F1/13

Abstract

A window (1) comprising a window pane (3) is provided with a visual display panel (5) laminated to the window (1). The visual display panel (5) comprises a cholesteric liquid crystal medium (15) sandwiched between inner and outer substrates (11,12) which are patterned with row and column electrodes (18,19) for defining individual pixels (8) which are individually addressable for displaying information on the panel (5). Inner and outer protective panels (9,10) sandwich the inner and outer substrates (11,12) and the liquid crystal medium (15) therebetween. An ultraviolet film filter (16) is located between the outer protective panel (10) and the outer substrate (11). The outer panel (10) is bonded to the window pane (3). The protective panels (9,10), the substrates (11,12) and the film filter (16) are all of transparent material. The pixels (8) are operable in a light transmitting state when powered up, and in a light scattering state when powered down. Letters and numerals to display the information are formed by operating appropriate selected ones of the pixels (8) in the light scattering state. The remaining pixels (8) which form the background of the visual display panel (5) are operated in the light transmitting state. Accordingly, the panel facilitates the display of information on a shop window with minimum impairment to viewing of goods and other items in the shop window behind the panel (5) by the viewing public.

Claims

1. A window comprising a window pane (3) characterised in that a visual display panel (5,51,69,71,81,95) is secured to the window, the visual display panel comprising a plurality of individually addressable pixels (1,50,60,70,80,90) arranged in a matrix of rows and columns, the pixels (8) being alternately and selectively operable in at least two states, namely, a first state whereby light is transmitted through the panel (5,51,69,71,81,95), and a second state whereby light is scattered, dispersed, reflected or blocked, so that at least one character (7) can be selectively displayed on the panel (5,51,69,71,81,95) by selectively operating at least one of the pixels (8) in the second state to form the character (7) to be displayed, and visual access is provided through the panel (5,51,69,71,81,95) through the pixels (8) in the first state.

2. A window as claimed in claim 1 characterised in that the area of the panel (5,51,69,71,81,95) is substantially similar to the area of the window pane (3).

3. A window as claimed in claim 1 characterised in that the area of the panel (5,51,69,71,81,95) is less than the area of the window pane (3).

4. A window as claimed in any preceding claim characterised in that the window pane (3) forms a part of the panel (5,51,69,71,81,95).

5. A window as claimed in claim 1 characterised in that the panel (5,51,69,71,81,95) forms a part of the window pane.

6. A window as claimed in any preceding claim characterised in that the panel (5,51,69,71,81,95) lies substantially parallel to the window pane (3).

7. A window as claimed in any preceding claim characterised in that the panel (5,51,69,71,81,95) is laminated to the window pane (3).

8. A window as claimed in any preceding claim characterised in that the window pane (3) is a window pane of a window of single glaze construction.

9. A window as claimed in claim 8 characterised in that the panel (5,51,69,71,81,95) is secured to an inner surface of the window pane (3) of single glaze construction.

10. A window as claimed in any of claims 1 to 7 characterised in that the window pane (91) is a window pane of a window (90) of double glaze construction.

11. A window as claimed in claim 10 characterised in that the panel is located in a cavity (93) defined between an inner pane (91) and an outer pane (92) of the window (90) of double glaze construction.

12. A window as claimed in claim 10 or 11 characterised in that the panel (5,51,69,71,81,95) is secured to the inner pane (91) of the window (90) of double glaze construction.

13. A window as claimed in any preceding claim characterised in that the panel (5,51,69,71,81,95) comprises an electro-optical medium (15).

14. A window as claimed in claim 13 characterised in that the panel (5,51,69,71,81,95) comprises a pair of panel substrates (11,12) of transparent material, and the electro-optical medium (15) is located sandwiched between the respective substrates (11,12).

15. A window as claimed in claim 14 characterised in that one of the substrates (11) is patterned with a plurality of row electrodes (18), and the other substrate (12) is patterned with a plurality of column electrodes (19), so that the respective row and column electrodes (18,19) co-operate for defining the pixels (8).

16. A window as claimed in claim 15 characterised in that the electrodes (18,19) are of a transparent material.

17. A window as claimed in claim 15 or 16 characterised in that the electrodes (18,19) on the respective substrates (11,12) are patterned from a layer of idium tin oxide formed on the respective substrates (11,12).

18. A window as claimed in any of claims 15 to 17 characterised in that the electrodes (18,19) on the respective substrates (11,12) define respective patterned areas (20,21), and when co-operating to form the pixels (8) the respective patterned areas (20,21) define a common patterned area (22) which is common to each of the respective patterned areas, and the pixels (8) are defined within the common patterned area (22).

19. A window as claimed in claim 18 characterised in that the electro-optical medium (15) is contained within the common patterned area (22).

20. A window as claimed in any of claims 15 to 19 characterised in that at least one track carrying portion (24,28,54,62) extends from the patterned area (20,21) of each substrate (11,12), and a connecting means (2,6,30) is carried on each track carrying portion (24,28,54,62), a plurality of tracks (25,29) are patterned on each track carrying portion for connecting the electrodes (18,19) of the corresponding substrate (11,12) to the corresponding connecting means (26,30) for facilitating addressing of the electrodes (18,19) through the connecting means (26,30).

21. A window as claimed in claim 20 characterised in that the connecting means (26,30) of each track carrying portion (24,28,54,62) is located towards an edge of the track carrying portion (24,28,54,62).

22. A window as claimed in claim 20 or 21 characterised in that the track carrying portion (24,28,54,62) of one of the substrates (11,12) extends to one side of the patterned area (20,21) thereof.

23. A window as claimed in claim 22 characterised in that a pair of track carrying portions (24,28,54,62) extend from respective opposite sides of the patterned area (20,21) of one of the substrates (11,12).

24. A window as claimed in any of claims 20 to 23 characterised in that the connecting means (26,30) on the respective track carrying portions (24,28,54,62) are located adjacent edges of the respective track carrying portions (24,28,54,62), which are adjacent each other.

25. A window as claimed in any of claims 20 to 24 characterised in that the track carrying portion (24,28,54,62) of one of the substrates (11,12) extends upwardly from the patterned area of the substrate.

26. A window as claimed in claim 25 characterised in that respective track carrying portions (24,28,54,62) extend from one of the substrates (11,12) upwardly and downwardly from the patterned area thereof.

27. A window as claimed in any of claims 20 to 26 characterised in that each respective track carrying portion (24,28,54,62) extends to a peripheral edge of the window pane (3) so that the connecting means (26,30) can be located within a frame (2) of the window.

28. A window as claimed in any of claims 20 to 27 characterised in that the electrically conductive tracks on each track carrying portion (24,28,54,62) are patterned from a layer of idium tin oxide formed on the respective substrates (11,12).

29. A window as claimed in any of claims 15 to 28 characterised in that the pixels (8) are operable between the respective first and second states by applying or removing a voltage to or from the respective electrodes (18,19) which define the pixels (8), the state of which are to be changed.

30. A window as claimed in any of claims 15 to 29 characterised in that the pixels (8) are operated from the second state to the first state by applying a voltage across the electrodes (18,19) defining the pixels (8) the state of which are to be changed from the second state to the first state.

31. A window as claimed in any of claims 15 to 30 characterised in that the pixels (8) are operated from the first state to the second state by removing a voltage applied across the electrodes (18,19) defining the pixels (8) the state of which are to be changed from the first state to the second state.

32. A window as claimed in any of claims 15 to 31 characterised in that a driver circuit (38) is provided for applying voltages to respective selected electrodes (18,19) on the respective substrates (11,12) for selectively operating the pixels (8) defined by the electrodes (18,19) from one of the first and second states to the other of the first and second states.

33. A window as claimed in claim 32 characterised in that the driver circuit (38) is incorporated in a window frame of the window (1,50,60,70,80,90).

34. A window as claimed in any of claims 14 to 33 characterised in that an ultraviolet film filter (16) is located adjacent one of the substrates (11,12) for protecting the electro-optical medium (15) from ultraviolet light.

35. A window as claimed in any of claims 14 to 34 characterised in that at least one protective panel (9,10) is provided for protecting the visual display panel (5,51,69,71,81,95).

36. A window as claimed in claim 35 characterised in that a pair of protective panels (9,10) are provided and the substrates (11,12) are located between the respective protective panels (9,10).

37. A window as claimed in claim 35 or 36 characterised in that each protective panel (9,10) is of PET material.

38. A window as claimed in claim 35 or 36 characterised in that each protective panel (9,10) is of acrylic material.

39. A window as claimed in any of claims 35 to 38 characterised in that the window pane (3) forms one of the protective panels (9,10).

40. A window as claimed in any of claims 13 to 39 characterised in that the electro-optical medium (15) is a liquid crystal medium.

41. A window as claimed in claim 40 characterised in that the liquid crystal medium is a cholesteric liquid crystal medium.

42. A window as claimed in any of claims 13 to 39 characterised in that the electro-optical medium (15) is a suspended particle device medium.

43. A window as claimed in any of claims 13 to 39 characterised in that the electro-optical medium (15) is an electrochromic medium.

44. A window as claimed in any of claims 13 to 39 characterised in that the electro-optical medium (15) is a polymer dispersed liquid crystal medium.

45. A window as claimed in any of claims 13 to 39 characterised in that the electro-optical medium (15) is an organic light emitting diode medium.

46. A window as claimed in claim 45 characterised in that each pixel (8) defines a light emitting diode such that when a voltage is applied to the respective electrodes (18,19) which define the pixel (8) the light emitting diode operates in the second state.

47. A window as claimed in any preceding claim characterised in that the pixels (8) are bi-state pixels.

48. A window as claimed in any preceding claim characterised in that the pixels (8) are bi-stable pixels.

49. A window as claimed in any preceding claim characterised in that the pixels s (8) are selectively addressable for forming the at least one character.

50. A window as claimed in any preceding claim characterised in that the pixels (8) are selectively addressable for displaying a plurality of characters.

51. A window as claimed in any preceding claim characterised in that some of the characters are letters of the alphabet.

52. A window as claimed in any preceding claim characterised in that some of the characters are numerals.

53. A window as claimed in any preceding claim characterised in that the respective pixels (8) are selectively addressable to display letters and/or numerals to convey information.

54. A window as claimed in any preceding claim characterised in that each pixel (8) when operated in the second state back scatters a proportion of light incident on the pixel (8).

55. A method for displaying a character on a window pane of a window characterised in that the method comprises the steps of securing a visual display panel to the window wherein the visual display panel comprises a plurality of individually addressable pixels arranged in a matrix of rows and columns, the pixels being alternately selectively operable in at least two states, namely, a first state whereby light is transmitted through the panel, and a second state whereby light is scattered, dispersed, reflected, blocked or emitted, so that at least one character can be selectively displayed on the panel by selectively operating at least one of the pixels in the second state to form the character to be displayed, and visual access is provided through the panel through the pixels in the first state.

56. A method as claimed in claim 55 characterised in that the area of the panel is substantially similar to the area of the window pane.

57. A method as claimed in claim 55 characterised in that the area of the panel is less than the area of the window pane.

58. A method as claimed in any of claims 55 to 57 characterised in that the window pane forms a part of the panel.

59. A method as claimed in any of claims 55 to 57 characterised in that the panel forms a part of the window pane.

60. A method as claimed in any of claims 55 to 59 characterised in that the panel lies substantially parallel to the window pane.

61. A method as claimed in any of claims 55 to 60 characterised in that the panel is laminated to the window pane.

62. A method as claimed in any of claims 55 to 61 characterised in that the window pane is a window pane of a window of single glaze construction.

63. A method as claimed in claim 62 characterised in that the panel is secured to an inner surface of the window pane of single glaze construction.

64. A method as claimed in any of claims 55 to 61 characterised in that the window pane is a window pane of double glaze construction.

65. A method as claimed in claim 64 characterised in that the panel is located in a cavity defined between an inner pane and an outer pane of the window of double glaze construction.

66. A method as claimed in claim 64 or 65 characterised in that the panel is secured to the inner pane of the window of double glaze construction.

67. A method as claimed in any of claims 55 to 66 characterised in that the panel comprises an electro-optical medium.

68. A method as claimed in claim 67 characterised in that the panel comprises a pair of panel substrates of transparent material, and the electro-optical medium is located sandwiched between the respective substrates.

69. A method as claimed in claim 68 characterised in that one of the substrates is patterned with a plurality of row electrodes, and the other substrate is patterned with a plurality of column electrodes, so that the respective row and column electrodes co-operate for defining the pixels.

70. A method as claimed in claim 69 characterised in that the electrodes are of a transparent material.

71. A method as claimed in claim 69 or 70 characterised in that the electrodes on the respective substrates are patterned from a layer of idium tin oxide formed on the respective substrates.

72. A method as claimed in any of claims 69 to 71 characterised in that the electrodes on the respective substrates define respective patterned areas, and when co-operating to form the pixels the respective patterned areas define a common patterned area which is common to each of the respective patterned areas, and the pixels are defined within the common patterned area.

73. A method as claimed in claim 72 characterised in that the electro-optical medium is contained within the common patterned area.

74. A method as claimed in any of claims 69 to 73 characterised in that at least one track carrying portion extends from the patterned area of each substrate, and a connecting means is carried on each track carrying portion, a plurality of tracks are patterned on each track carrying portion for connecting the electrodes of the corresponding substrate to the corresponding connecting means for facilitating addressing of the electrodes through the connecting means.

75. A method as claimed in claim 74 characterised in that the connecting means of each track carrying portion is located towards an edge of the track carrying portion.

76. A method as claimed in claim 74 or 75 characterised in that the track carrying portion of one of the substrates extends to one side of the patterned area thereof.

77. A method as claimed in claim 76 characterised in that a pair of track carrying portions extend from respective opposite sides of the patterned area of one of the substrates.

78. A method as claimed in any of claims 74 to 77 characterised in that the connecting means on the respective track carrying portions are located adjacent edges of the respective track carrying portions, which are adjacent each other.

79. A method as claimed in any of claims 74 to 78 characterised in that the track carrying portion of one of the substrates extends upwardly from the patterned area of the substrate.

80. A method as claimed in claim 78 characterised in that respective track carrying portions extend from one of the substrates upwardly and downwardly from the patterned area thereof.

81. A method as claimed in any of claims 74 to 80 characterised in that each respective track carrying portion extends to a peripheral edge of the window pane so that the connecting means can be located within a frame of the window.

82. A method as claimed in any of claims 74 to 81 characterised in that the electrically conductive tracks on each track carrying portion are patterned from a layer of idium tin oxide formed on the respective substrates.

83. A method as claimed in any of claims 69 to 82 characterised in that the pixels are operable between the respective first and second states by applying or removing a voltage to or from the respective electrodes which define the pixels, the state of which are to be changed.

84. A method as claimed in any of claims 69 to 83 characterised in that the pixels are operated from the second state to the first state by applying a voltage across the electrodes defining the pixels the state of which are to be changed from the second state to the first state.

85. A method as claimed in any of claims 69 to 84 characterised in that the pixels are operated from the first state to the second state by removing a voltage applied across the electrodes defining the pixels the state of which are to be changed from the first state to the second state.

86. A method as claimed in any of claims 69 to 85 characterised in that a diver circuit is provided for applying voltages to respective selected electrodes on the respective substrates for selectively operating the pixels defined by the electrodes from one of the first and second states to the other of the first and second states.

87. A method as claimed in claim 86 characterised in that the driver circuit is incorporated in a window frame of the window.

88. A method as claimed in any of claims 68 to 87 characterised in that an ultraviolet film filter is located adjacent one of the substrates for protecting the electro-optical medium from ultraviolet light.

89. A method as claimed in any of claims 68 to 88 characterised in that at least one protective panel is provided for protecting the visual display panel.

90. A method as claimed in claim 89 characterised in that a pair of protective panels are provided and the substrates are located between the respective protective panels.

91. A method as claimed in claim 89 or 90 characterised in that each protective panel is of PET material.

92. A method as claimed in claim 89 or 90 characterised in that each protective panel is of acrylic material.

93. A method as claimed in any of claims 89 to 92 characterised in that the window pane forms one of the protective panels.

94. A method as claimed in any of claims 67 to 92 characterised in that the electro-optical medium is a liquid crystal medium.

95. A method as claimed in claim 94 characterised in that the liquid crystal medium is a cholesteric liquid crystal medium.

96. A method as claimed in any of claims 67 to 92 characterised in that the electro-optical medium is a suspended particle device medium.

97. A method as claimed in any of claims 67 to 92 characterised in that the electro-optical medium is an electrochromic medium.

98. A method as claimed in any of claims 67 to 92 characterised in that the electro-optical medium is a polymer dispersed liquid crystal medium.

99. A method as claimed in any of claims 67 to 92 characterised in that the electro-optical medium is an organic light emitting diode medium.

100. A method as claimed in claim 99 characterised in that each pixel defines a light emitting diode such that when a voltage is applied to the respective electrodes which define the pixel the light emitting diode operates in the second state.

101. A method as claimed in any of claims 55 to 100 characterised in that the pixels are bi-state pixels.

102. A method as claimed in any of claims 55 to 100 characterised in that the pixels are bi-stable pixels.

103. A method as claimed in any of claims 55 to 101 characterised in that the pixels are selectively addressable for forming the at least one character.

104. A method as claimed in any of claims 55 to 103 characterised in that the pixels are selectively addressable for displaying a plurality of characters.

105. A method as claimed in any of claims 55 to 104 characterised in that some of the characters are letters of the alphabet.

106. A method as claimed in any of claims 55 to 105 characterised in that some of the characters are numerals.

107. A method as claimed in any of claims 55 to 106 characterised in that the respective pixels are selectively addressable to display letters and/or numerals to convey information.

108. A method as claimed in any of claims 55 to 107 characterised in that each pixel when operated in the second state back scatters a proportion of light incident on the pixel.

109. A visual display panel comprising a plurality of individually addressable pixels arranged in a matrix of rows and columns, the pixels being alternately selectively operable in at least two states, namely, a first state whereby light is transmitted through the panel, and a second state whereby light is scattered, dispersed, reflected, blocked or emitted, characterised in that the visual display panel is adapted for securing to a window pane of a window, so that at lease one character can be selectively displayed on the panel by selectively operating at least one of the pixels in the second state to form the character to be displayed, visual access is provided through the panel through the pixels in the first state.

110. A visual display panel as claimed in claim 109 characterised in that the area of the panel is substantially similar to the area of the window pane.

111. A visual display panel as claimed in claim 109 characterised in that the area of the panel is less than the area of the window pane.

112. A visual display panel as claimed in any of claims 109 to 111 characterised in that the window pane forms a part of the panel.

113. A visual display panel as claimed in any of claims 109 to 111 characterised in that the panel forms a part of the window pane.

114. A visual display panel as claimed in any of claims 109 to 113 characterised in that the panel lies substantially parallel to the window pane.

115. A visual display panel as claimed in any of claims 109 to 114 characterised in that the panel is laminated to the window pane.

116. A visual display panel as claimed in any of claims 109 to 115 characterised in that the window pane is a window pane of a window of single glaze construction.

117. A visual display panel as claimed in claim 116 characterised in that the panel is secured to an inner surface of the window pane of single glaze construction.

118. A visual display panel as claimed in any of claims 109 to 115 characterised in that the window pane is a window pane of double glaze construction.

119. A visual display panel as claimed in claim 118 characterised in that the panel is located in a cavity defined between an inner pane and an outer pane of the window of double glaze construction.

120. A visual display panel as claimed in claim 118 or 119 characterised in that the panel is secured to the inner pane of the window of double glaze construction.

121. A visual display panel as claimed in any of claims 109 to 120 characterised in that the panel comprises an electro-optical medium.

122. A visual display panel as claimed in claim 121 characterised in that the panel comprises a pair of panel substrates of transparent material, and the electro-optical medium is located sandwiched between the respective substrates.

123. A visual display panel as claimed in claim 122 characterised in that one of the substrates is patterned with a plurality of row electrodes, and the other substrate is patterned with a plurality of column electrodes, so that the respective row and column electrodes co-operate for defining the pixels.

124. A visual display panel as claimed in claim 123 characterised in that the electrodes are of a transparent material.

125. A visual display panel as claimed in claim 123 or 124 characterised in that the electrodes on the respective substrates are patterned from a layer of idium tin oxide formed on the respective substrates.

126. A visual display panel as claimed in any of claims 123 to 125 characterised in that the electrodes on the respective substrates define respective patterned areas, and when co-operating to form the pixels the respective patterned areas define a common patterned area which is common to each of the respective patterned areas, and the pixels are defined within the common patterned area.

127. A visual display panel as claimed in claim 126 characterised in that the electro-optical medium is contained within the common patterned area.

128. A visual display panel as claimed in any of claims 123 to 127 characterised in that at least one track carrying portion extends from the patterned area of each substrate, and a connecting means is carried on each track carrying portion, a plurality of tracks are patterned on each track carrying portion for connecting the electrodes of the corresponding substrate to the corresponding connecting means for facilitating addressing of the electrodes through the connecting means.

129. A visual display panel as claimed in claim 128 characterised in that the connecting means of each track carrying portion is located towards an edge of the track carrying portion.

130. A visual display panel as claimed in claim 128 or 129 characterised in that the track carrying portion of one of the substrates extends to one side of the patterned area thereof.

131. A visual display panel as claimed in claim 130 characterised in that a pair of track carrying portions extend from respective opposite sides of the patterned area of one of the substrates.

132. A visual display a panel as claimed in any of claims 128 to 131 characterised in that the connecting means on the respective track carrying portions are located adjacent edges of the respective track carrying portions, which are adjacent each other.

133. A visual display panel as claimed in any of claims 128 to 132 characterised in that the track carrying portion of one of the substrates extends upwardly from the patterned area of the substrate.

134. A visual display panel as claimed in claim 128 characterised in that respective track carrying portions extend from one of the substrates upwardly and downwardly from the patterned area thereof.

135. A visual display panel as claimed in any of claims 128 to 134 characterised in that each respective track carrying portion extends to a peripheral edge of the window pane so that the connecting means can be located within a frame of the window.

136. A visual display panel as claimed in any of claims 128 to 135 characterised in that the electrically conductive tracks on each track carrying portion are patterned from a layer of idium tin oxide formed on the respective substrates.

137. A visual display panel as claimed in any of claims 123 to 136 characterised in that the pixels are operable between the respective first and second states by applying or removing a voltage to or from the respective electrodes which define the pixels, the state of which are to be changed.

138. A visual display panel as claimed in any of claims 123 to 137 characterised in that the pixels are operated from the second state to the first state by applying a voltage across the electrodes defining the pixels the state of which are to be changed from the second state to the first state.

139. A visual display panel as claimed in any of claims 123 to 138 characterised in that the pixels are operated from the first state to the second state by removing a voltage applied across the electrodes defining the pixels the state of which are to be changed from the first state to the second state.

140. A visual display panel as claimed in any of claims 123 to 139 characterised in that a diver circuit is provided for applying voltages to respective selected electrodes on the respective substrates for selectively operating the pixels defined by the electrodes from one of the first and second states to the other of the first and second states.

141. A visual display panel as claimed in claim 140 characterised in that the driver circuit is incorporated in a window frame of the window.

142. A visual display panel as claimed in any of claims 122 to 141 characterised in that an ultraviolet film filter is located adjacent one of the substrates for protecting the electro-optical medium from ultraviolet light.

143. A visual display panel as claimed in any of claims 122 to 142 characterised in that at least one protective panel is provided for protecting the visual display panel.

144. A visual display panel as claimed in claim 143 characterised in that a pair of protective panels are provided and the substrates are located between the respective protective panels.

145. A visual display panel as claimed in claim 143 or 144 characterised in that each protective panel is of PET material.

146. A visual display panel as claimed in claim 143 or 144 characterised in that each protective panel is of acrylic material.

147. A visual display panel as claimed in any of claims 143 to 146 characterised in that the window pane forms one of the protective panels.

148. A visual display panel as claimed in any of claims 121 to 147 characterised in that the electro-optical medium is a liquid crystal medium.

149. A visual display panel as claimed in claim 148 characterised in that the liquid crystal medium is a cholesteric liquid crystal medium.

150. A visual display panel as claimed in any of claims 121 to 147 characterised in that the electro-optical medium is a suspended particle device medium.

151. A visual display panel as claimed in any of claims 121 to 147 characterised in that the electro-optical medium is an electrochromic medium.

152. A visual display panel as claimed in any of claims 121 to 147 characterised in that the electro-optical medium is a polymer dispersed liquid crystal medium.

153. A visual display panel as claimed in any of claims 121 to 147 characterised in that the electro-optical medium is an organic light emitting diode medium.

154. A visual display panel as claimed in claim 153 characterised in that each pixel defines a light emitting diode such that when a voltage is applied to the respective electrodes which define the pixel the light emitting diode operates in the second state.

155. A visual display panel as claimed in any of claims 109 to 154 characterised in that the pixels are bi-state pixels.

156. A visual display panel as claimed in any of claims 109 to 155 characterised in that the pixels are bi-stable pixels.

157. A visual display panel as claimed in any of claims 109 to 156 characterised in that the pixels are selectively addressable for forming the at least one character.

158. A visual display panel as claimed in any of claims 109 to 157 characterised in that the pixels are selectively addressable for displaying a plurality of characters.

159. A visual display panel as claimed in any of claims 109 to 158 characterised in that some of the characters are letters of the alphabet.

160. A visual display panel as claimed in any of claims 109 to 159 characterised in that some of the characters are numerals.

161. A visual display panel as claimed in any of claims 109 to 160 characterised in that the respective pixels are selectively addressable to display letters and/or numerals to convey information.

162. A visual display panel as claimed in any of claims 109 to 161 characterised in that each pixel when operated in the second state back scatters a proportion of light incident on the pixel.