Display device

• US 20030002126A1
• Filed: 07/02/2002
• Published: 01/02/2003
• Est. Priority Date: 11/23/1997
• Status: Active Grant

• Current Assignee: Citala Ltd.
• Original Assignee: Adact Ltd.
• Inventors: Doron, Marco
• Granted Patent: US 6,807,012 B2
• Time in Patent Office: Days
• US Class Current: 359/242
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: H01H 19/585 provided with printed circuit contacts
• CPC Class Codes: H01H 2009/0077 using recyclable materials, e.g. for easier recycling or minimising the packing material
• CPC Class Codes: H01H 3/004 for operating contacts periodically
• CPC Class Codes: H01H 57/00 Electrostrictive relays; Piezoelectric relays
• CPC Class Codes: H01H 61/063 making use of a bimetallic element

Abstract

A picture display device is disclosed comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour and/or of emitting electromagnetic energy at least in the form of visible light Each said colour cell comprises colour change and/or luminescent means characterised in enabling said cell to exhibit a colour change from said first colour to said second colour and/or in enabling said cell to emit electromagnetic energy at least in the form of visible light in correlation to the application of electrical current and/or voltage to the said cell; suitable electrical connections electrically connectable to a suitable electrical power supply and adapted to provide said colour cell with a suitable electrical current and/or voltage; said device characterised in being substantially disposable.

Claims

1. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour and/or of emitting electromagnetic energy at least in the form of visible light, each said colour cell comprising:

colour change and/or luminescent means characterised in enabling said cell to exhibit a colour change from said first colour to said second colour and/or in enabling said cell to emit electromagnetic energy at least in the form of visible light in correlation to the application of electrical current and/or voltage to the said cell;

suitable electrical connections electrically connectable to a suitable electrical power supply and adapted to provide said colour cell with a suitable electrical current and/or voltage;

said device characterised in being substantially disposable.

3. A picture display device according to claim 1, wherein

said suitable electrical connections comprises at least one pair of electrodes comprising a lower electrode comprised on said substrate and an upper electrode superposed and distanced from said lower electrode;

said at least one pair of electrodes capable of being electrically connected to at least one suitable electrical power source capable of providing at least a predetermined voltage and/or current between said upper electrode and said lower electrode of said at least one pair of electrodes; and

said colour change and/or luminescent means comprises at least one dielectric layer comprised of suitable dielectric material disposed intermediate said upper electrode and said lower electrode of said at least one pair of electrodes;

wherein said dielectric layer comprises at least one luminescent layer of luminescent material substantially parallel to and in electrical contact with at least one of said upper electrode and said lower electrode of said at least one pair of electrodes, said at least one luminescent layer being capable of emitting electromagnetic energy at least in the form of visible light in response to the establishment of said predetermined voltage and/or current between said upper electrode and said lower electrode of said at least one pair of electrodes, wherein said emission of said visible light is such as to be capable of being observed from the exterior of said colour cell.

4. A picture display device as claimed in claim 3, wherein said luminescent layer is such that the emission of said visible light by said cell ceases in correlation with the magnitude of said voltage between said upper electrode and said lower electrode of said at least one pair of electrodes falling to substantially below a predetermined voltage threshold.

5. A picture display device as claimed in claim 3, wherein said luminescent layer is such that the emission of said visible light by said cell endures for a substantial period of time after the magnitude of said voltage between said upper electrode and said lower electrode of said at least one pair of electrodes falls to substantially below a predetermined voltage threshold.

6. A picture display device as claimed in claim 5, wherein said at least one luminescent layer comprises a suitable phosphorescent material.

7. A picture display device as claimed in claim 3, wherein each said colour cell comprises at least a first said pair of electrodes and a second said pair of electrodes, and wherein a first said luminescent layer intermediate said first pair of electrodes is such that the emission of said visible light by said cell ceases in correlation with the magnitude of said voltage between said upper electrode and said lower electrode of said first pair of electrodes falling to substantially below a predetermined voltage threshold, and wherein a second said luminescent layer intermediate said second pair of electrodes is such that the emission of said visible light by said cell endures for a substantial period of time after the magnitude of said voltage between said upper electrode and said lower electrode of said second pair of electrodes falls to substantially below a predetermined voltage threshold.

8. A picture display device as claimed in claim 7, wherein said first pair of electrodes and corresponding said first luminescent layer disposed therebetween is nested within said second pair of electrodes and corresponding said second luminescent layer disposed therebetween.

9. A picture display device as claimed in claim 8, wherein said first luminescent layer is substantially disc-shaped, and wherein said second luminescent layer is substantially annular-shaped.

10. A picture display device as claimed in claim 7, wherein said luminescent layer intermediate said second pair of electrodes comprises a suitable phosphorescent material.

11. A picture display device as claimed in claim 3, wherein said luminescent layer is such that the visible light emitted by said cell is of a wavelength corresponding to a predetermined one of the three primary colours.

12. A picture display device as claimed in claim 3, wherein said luminescent layer is such that the visible light emitted by said cell is substantially white light.

13. A picture display device as claimed in claim 12, wherein each said colour cell further comprises a filter layer comprising a suitable optical filter superposed over said upper electrode of said at least one pair of electrodes, said optical filter adapted to enable the visible light emitted by said cell to be of a predetermined colour.

14. A picture display device as claimed in claim 13, wherein said predetermined colour is one of the primary colours.

15. A picture display device as claimed in claim 3, wherein said predetermined voltage is in the range of about 105 volts to about 110 volts.

16. A picture display device as claimed in claim 3, wherein said luminescent layer comprises zinc sulphide activated with silver or copper.

17. A picture display device as claimed in claim 3, wherein said luminescent layer is comprises zinc silicate activated with manganese.

19. A picture display device according to claim 1, wherein

said suitable electrical connections comprises an electrically heatable base comprising at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said base to a suitable electrical power source, said base capable of being electrically heated at least from a first temperature to at least a second temperature in response to the supply of a predetermined voltage and/or current thereto;

and

said colour change and/or luminescent means comprises thermally responsive colour change means in thermal contact with said base, said colour change means enabling said cell to exhibit a colour change from said first colour to said second colour in response to said temperature change of the said base from said first temperature to said at least second temperature.

20. A picture display device according to claim 19, wherein said colour change means comprises a suitable layer of thermochromic material capable of exhibiting a colour change from said first colour to said second colour in response to a change of temperature of said base from said at least first temperature to said at least said second temperature.

21. A picture display device according to claim 19, wherein said colour change means comprises a suitable layer of thermochromic material capable of exhibiting a colour change from said first colour to colourless in response to a change of temperature of said base from said at least first temperature to said at least said second temperature, said thermochromic material superposed directly or indirectly over a colour layer of said second colour, such that the said colour cell may exhibit said second colour when said thermochromic layer is colourless.

22. A picture display device according to claim 19, wherein said colour change means comprises a suitable layer of thermochromic material capable of exhibiting a colour change from colourless to said second colour in response to a change of temperature of said base from said at least first temperature to said at least said second temperature, said thermochromic material superposed directly or indirectly over a colour layer of said first colour, such that the said colour cell may exhibit said first colour when said thermochromic layer is colourless.

23. A picture display device according to claim 21, wherein said colour layer is disposed at least intermediate said thermochromic layer and said base.

24. A picture display device according to claim 21, wherein said colour layer is disposed at least intermediate said base and said substrate, said base being substantially colourless.

25. A picture display device according to claim 21, wherein said colour layer is disposed on a lower face of said substrate and substantially aligned at least with said thermochromic layer, said base and said substrate being substantially colourless.

26. A picture display device according to claim 19, wherein said colour change means comprises a suitable layer of thermochromic material capable of exhibiting a colour change from said first colour to said second colour in response to a change of temperature of said base from said at least first temperature to said at least said second temperature, wherein at least the colour of said second colour is variable with respect to the magnitude of said second temperature.

27. A picture display device according to claim 19, wherein said colour change means comprises:

a suitable bimaterial strip comprising a first layer of a first material having a first coefficient of thermal expansion superposed on, and in substantially shearless contact with, a second layer of a second material having a second coefficient of thermal expansion, said second coefficient of thermal expansion being greater than said first coefficient of thermal expansion, said bimaterial strip being in thermal contact at an edge thereof with said base such that at least a part of said first layer and at least a part of said second layer are in thermal contact with said base, said strip projecting from said base;

a colour layer of said second colour comprised on an exposed face of said second layer of said strip; and

a first area at least on said base having said first colour, said first area in juxtaposition with an exposed face of said first layer of said strip;

whereby said bimaterial strip bends from a first configuration to a second configuration in response to said temperature change of said base from said at least first temperature to said at least second temperature, wherein in said first configuration said strip is substantially perpendicular to said base enabling said first colour on said first area to be exhibited, and wherein in said second configuration said strip is substantially bent towards said first area substantially covering said first colour on said first area and enabling said second colour of the said colour layer comprised on the said second layer to be exhibited.

28. A picture display device according to claim 19, wherein said colour change means comprises:

a suitable bimaterial strip comprising a first layer of a first material having a first coefficient of thermal expansion superposed on, and in substantially shearless contact with, a second layer of a second material having a second coefficient of thermal expansion, said second coefficient of thermal expansion being greater than said first coefficient of thermal expansion, said bimaterial strip being in thermal contact at an edge thereof with said base such that at least a part of said first material and at least a part of said second material are in thermal contact with said base, said strip projecting from said base;

a colour layer of said first colour comprised on an exposed face of said first layer of said strip; and

a second area at least on said base having said second colour, said second area in juxtaposition with an exposed face of said second layer of said strip;

whereby said bimaterial strip bends from a first configuration to a second configuration in response to said temperature change of said base from said at least first temperature to said al least second temperature, wherein in said first configuration said strip is substantially bent towards said second area substantially covering said second colour on said second area and enabling said first colour of the said colour layer comprised on the said first layer to be exhibited, and wherein in said second configuration said strip is substantially perpendicular to said base enabling said second colour on said second area to be exhibited.

29. A picture display device according to claim 19, wherein said colour change means comprises:

a suitable bimaterial strip comprising a first layer of a first material having a first coefficient of thermal expansion superposed on, and in substantially shearless contact with, a second layer of a second material having a second coefficient of thermal expansion, said second coefficient of thermal expansion being greater than said first coefficient of thermal expansion, said bimaterial strip being in thermal contact at an edge thereof with said base such that at least a part of said first material and at least a part of said second material are in thermal contact with said base, said strip projecting from said base;

a colour layer of said first colour comprised on an exposed face of said first layer of said strip;

a first area at least on said base having said first colour, said first area in juxtaposition with an exposed face of said first layer of said strip;

a colour layer of said second colour comprised on an exposed face of said second layer of said strip;

a second area at least on said base having said second colour, said second area in juxtaposition with an exposed face of said second layer of said strip; and

whereby said bimaterial strip changes from a first configuration to a second configuration in response to said temperature change of said base from said at least first temperature to said at least second temperature, wherein in said first configuration said strip is substantially bent towards said second area substantially covering said second colour on said second area and enabling said first colour of the said colour layer comprised on the said first layer and said first colour on said first area to be exhibited, and wherein in said second configuration said strip is substantially bent towards said first area substantially covering said first colour on said first area and enabling said second colour of the said colour layer comprised on the said second. layer and said second colour on said second area to be exhibited.

30. A picture display device according to claim 27, wherein the said bimaterial strip constitute a bimetallic strip comprised of two suitable metals having substantially different coefficients of thermal expansion.

31. A picture display device according to claim 27, wherein said first material is iron and said second material is brass.

32. A picture display device according to claim 19, wherein said colour change means are reversible such that the said colour cell is capable of exhibiting a colour change from said second colour to said first colour in response to a reduction of the temperature of the said base to a temperature at least substantially below said second temperature.

34. A picture display device according to claim 1, wherein

said suitable electrical connections comprises at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said liquid crystal layer to a suitable electrical power source,;

and

said colour change and/or luminescent means comprises

a colour layer superposed on said substrate;

a layer of liquid crystal material comprising said at least one suitable electrical input connection means and at least one suitable electrical output connection means, said liquid crystal layer capable of exhibiting a colour change in response to the supply of a predetermined voltage and/or current thereto;

said layer of liquid crystal material being substantially superposed over said colour layer and substantially spaced therefrom by at least a suitable clearance.

42. A picture display device according to claim 1, wherein

said suitable electrical connections comprises at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said actuator element to a suitable electrical power source;

and

said colour change and/or luminescent means comprises;

an upper substantially transparent layer comprising an inverted substantially transparent prismatic element protruding from a lower surface thereof, said transparent layer being superposed over said substrate and distanced therefrom by suitable spacing means;

a substantially transparent movable element comprising an upper concavity complementary to and substantially aligned with said prismatic element, said movable element capable of being displaced a first distance between a first position and a second position, wherein in said first position said concavity is spaced from said prismatic element by a predetermined spacing, and wherein in said second position said concavity is substantial direct optical contact with said prismatic element;

a colour layer comprising said second colour disposed below said movable element and in optical communication therewith;

guiding means for enabling said movable element to reciprocate between said first position and said second position;

at least one actuator element in abutting contact with said movable element comprising said at least one suitable electrical input connection means and at least one suitable electrical output connection means, said actuator element characterised in being capable of increasing at least one dimension thereof in the direction of displacement of said movable element by said first distance in response to the supply of a predetermined voltage and/or current thereto, thereby displacing said movable element to said first position;

whereby said at least one actuator element increases said at least one dimension thereof by said first distance in response to the supply of a predetermined voltage and/or current to said actuator element, thereby propelling said movable element from said first position to said second position and bringing said concavity is substantial direct optical contact with said prismatic element thereby enabling said second colour on said colour layer to be exhibited by said colour cell, and whereby said actuator element returns to its datum dimension when said electrical power source is subsequently disconnected or alternatively when the polarity of the said voltage and/or current supply is reversed, returning said movable element to the said first position and establishing said spacing between said prismatic element and said concavity, said prismatic element having a configuration such as to internally reflect light entering said cell via said upper transparent layer thereby enabling said colour cell to exhibit a first colour as determined by the reflection of external light by said prismatic element.

43. A picture display device according to claim 42, wherein said prismatic element and said movable element comprise substantially equal refractive indexes.

44. A picture display device according to claim 42, wherein said at least one actuator element is bonded to said movable element.

45. A picture display device according to claim 42, wherein said at least one actuator element comprises an active gel.

46. A picture display device according to claim 42, wherein said at least one actuator element comprises a shape memory alloy.

47. A picture display device according to claim 42, wherein said at least one actuator element comprises a suitably configured piezoelectric crystal.

48. A picture display device according to claim 42, wherein said at least one actuator element comprises a ferromagnetic material.

49. A picture display device according to claim 42, wherein said colour layer is disposed at least intermediate said actuator element and said movable element.

50. A picture display device according to claim 42, wherein said colour layer is disposed at least intermediate said actuator element and said substrate, said actuator element being substantially transparent.

51. A picture display device according to claim 42, wherein said colour layer is disposed on a lower face of said substrate and substantially aligned at least with said movable element, said actuator element and said substrate being substantially transparent.

52. A picture display device according to claim 42, further comprising at least one passage on said upper transparent layer optionally including said prismatic element for enabling fluid communication between said spacing and the external environment at least when said movable element is in said first position.

54. A picture display device according to claim 1, wherein

said suitable electrical connections comprises:

at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said at least one actuator element to a suitable electrical power source; and

said colour change and/or luminescent means comprises;

a first, upper, substantially transparent layer comprising an inverted substantially transparent prismatic element protruding from a lower surface thereof;

said transparent layer being superposed over;

a second, lower, substantially transparent layer comprising an upper concavity complementary to and substantially aligned with said prismatic element, said second transparent layer being superposed over said substrate;

said first transparent layer capable of being displaced a first distance between a first position and a second position, wherein in said first position said concavity is substantial direct optical contact with said prismatic element, and wherein in said second position said concavity is spaced from said prismatic element by a predetermined spacing;

a colour layer comprising said first colour disposed below said second transparent layer and in optical communication therewith;

at least one actuator element in abutting contact with first transparent layer comprising said at least one suitable electrical input connection means and said at least one suitable electrical output connection means, said at least one actuator element characterised in being capable of increasing at least one dimension thereof in the direction of displacement of said first transparent layer by said first distance in response to the supply of a predetermined voltage and/or current thereto, thereby displacing said first transparent layer to said first position;

whereby said actuator element increases said at least one dimension thereof by said first distance in response to the supply of a predetermined voltage and/or current to said actuator element, thereby propelling said first transparent layer from said first position to said second position and establishing said spacing between said prismatic element and said concavity, said prismatic element having a configuration such as to internally reflect light entering said cell via said upper transparent layer thereby enabling said colour cell to exhibit a second colour as determined by the reflection of external light by said prismatic element, and whereby said actuator element returns to its datum dimension when said electrical power source is subsequently disconnected or alternatively when the polarity of the said voltage and/or current supply is reversed, returning said first transparent layer to the said first position and bringing said concavity is substantial direct optical contact with said prismatic element thereby enabling said first colour on said colour layer to be exhibited by said colour cell.

55. A picture display device according to claim 54, wherein said prismatic element and said second transparent layer comprise substantially equal refractive indexes.

56. A picture display device according to claim 54, wherein said at least one actuator element is bonded to said first transparent layer.

57. A picture display device according to claim 54, wherein said at least one actuator element comprises an active gel.

58. A picture display device according to claim 54, wherein said at least one actuator element comprises a shape memory alloy.

59. A picture display device according to claim 54, wherein said at least one actuator element comprises a suitably configured piezoelectric crystal.

60. A picture display device according to claim 54, wherein said at least one actuator element comprises a ferromagnetic material.

61. A picture display device according to claim 54, wherein said colour layer is disposed at least intermediate said second transparent layer and said substrate.

62. A picture display device according to claim 54, wherein said colour layer is disposed on a lower face of said substrate and substantially aligned at least with said prismatic element, said substrate being substantially transparent.

63. A picture display device according to claim 54, further comprising at least one passage on said first transparent layer optionally including said prismatic element for enabling fluid communication between said spacing and the external environment at least when said first transparent layer is in said first position.

64. A picture display device according to claim 54, further comprising at least one guiding means for facilitating reciprocation of said first transparent layer between said first position and said second position.

66. A picture display device according to claim 1, wherein

said colour change and/or luminescent means comprises a layer of electrochromic material comprised on said substrate, said electrochromic material capable of changing colour from said first colour to second colour in response to the passage of a suitable electrical current therethrough and/or the application of a suitable voltage thereto;

said suitable electrical connections comprises at least one pair of electrical conductors in electrical contact with said electrochromic layer, said pair of electrical conductors capable of being electrically connected to a suitable electrical power source and being adapted to provide a suitable current and/or voltage to said electrochromic layer such as to enable said cell to exhibit a colour change from said first colour to second colour.

67. A picture display device according to claim 1, wherein said substrate is flexible.

68. A picture display device according to claim 1, wherein said substrate is substantially rigid.

69. A picture display device according to claim 1, wherein at least the corresponding electrically conducting elements of adjacent colour cells are electrically insulated one from another.

70. A picture display device according to claim 69, wherein said insulation is achieved by means of an insulating material placed at least between the said corresponding electrically conducting elements of adjacent colour cells.

71. A picture display device according to claim 69, wherein said insulation is achieved by means of a non-electrically-conductive space existing between at least the said corresponding electrically conducting elements of adjacent colour cells.

72. A picture display device according to claim 1, wherein the said plurality of colour cells are arranged in the form of a substantially rectangular grid.

73. A picture display device according to claim 1, wherein the said colour cells are substantially divided into a first, a second and a third group, the said second colour of the colour cells in said first group being a colour of red, the said second colour of the colour cells of said second group being a colour of blue, and the second colour of the colour cells in said third group being a colour of green.

74. A picture display device according to claim 73, wherein the colour cells comprising said three groups are substantially homogeneously distributed over the said substrate.

75. A picture display device according to claim 1, wherein the said colour cells are between 0.1 mm and 1.0 meter in equivalent diameter.

76. A picture display device according to claim 1, wherein the said power source comprises a suitable DC power supply including a suitable battery.

77. A picture display device according to claim 1, wherein the said power source comprises a suitable photoelectric cell.

78. A picture display device according to claim 1, wherein the said power source is comprised on said substrate.

79. A picture display device according to claim 78, wherein the said power source is suitably printed onto said substrate.

80. A picture display device according to claim 1, wherein the said power source comprises a suitable AC power supply optionally operatively connected to a suitable rectifier.

81. A picture display device according to claim 1, wherein the said power source is electrically connected to at least a portion of said plurality of said colour cells via a frame circuit board, said frame circuit board being characterised in providing suitable interconnections between said power source and at least one of the said input and output connection means of each of the said colour cells of the said portion of said colour cells.

82. A picture display device according to claim 81, wherein said portion of colour cells are chosen such that when the said colour cells of said portion of said colour cells are electrically connected to said power source a predetermined image comprised of each said second colour of each corresponding said colour cells of said portion of colour cells is exhibited by the said device.

83. A picture display device according to claim 81, further comprising sequencing means wherein said sequencing means electrically connects the said power source selectively to each said frame circuit board.

84. A picture display device according to claim 83, wherein the said sequencing means electrically connects said power source to each said frame circuit board of said plurality of frame circuit boards in a predetermined sequence.

85. A picture display device according to claim 84, wherein the said sequencing means electrically connects said power source to each of successive frame circuit board of said plurality of frame circuit boards at a predetermined rate.

86. A picture display device according to claim 84, wherein the said predetermined rate may be between about 1 and about 30 frame circuit board connections per second, and preferably about 15 frame circuit board connections per second.

87. A picture display device according to claim 83, wherein each said frame circuit board enables a predetermined image to be exhibited by the said device.

88. A picture display device according to claim 87, wherein the said predetermined images are chosen such as to produce an illusion of movement of an image in correlation to the sequential connection of said plurality of frame circuit boards to said power source by means of said sequencing means.

89. A picture display device according to claim 84, wherein the said sequencing means electrically connects said power source to each of said successive frame circuit board of said plurality of frame circuit board on demand by means of a suitable switch.

90. A picture display device according to claim 89, wherein said switch is operable by a user of said device.

91. A picture display device according to claim 84, wherein said sequencing means operates in consecutive cycles, whereby in each said cycle the said sequencing means electrically connects said power source to each said frame circuit board of said plurality of frame circuit boards in said predetermined sequence.

92. A picture display device according to claim 83, wherein said sequencing means comprises a suitably programmed microprocessor chip.

94. A picture display device according to claim 83, wherein said sequencing means comprises a first switch for electrically connecting between at least one pair of electrical conductors, one conductor of said pair being electrically connectable to a suitable power source and the other conductor of said pair being connectable to a corresponding frame circuit board, said first switch comprising:

a suitable substantially non-electrically-conducting fluid medium in the form of a closed loop and having a free upper surface;

said closed loop bounded by at least an inner wall and an outer wall, said inner and outer walls being concentric one to the other and comprising an upper inner wall portion and an inner wall portion, respectively, protruding from the mean level of the said fluid free surface;

at least one said pair of conductors, one said conductor of said pair comprising a suitable first electrical contact on said upper inner wall portion, and the other said conductor comprising a suitable second electrical contact on said upper outer wall portion;

at least one electrically actuable oscillating element immersed in said fluid medium capable of providing at least one travelling wave on said free surface in response to suitable vibrations thereof;

an electrically-conductive dynamic contact element, substantially on said free surface and capable of being carried by said wave, said contact element extending at least between said first electrical contact and said second electrical contact;

whereby when said oscillating element is suitably vibrated, at least one travelling wave is provided on said free surface carrying the said dynamic element along said free surface element alternately to a position providing electrical contact between said first contact and said second contact and to a position in which said first contact and said second contact are electrically disconnected.

95. A picture display device according to claim 94, wherein said oscillating element is operatively connected to any suitable electrical power source.

96. A picture display device according to claim 94, wherein said first contact and said second contact of each said pair of conductors are substantially facing one another.

97. A picture display device according to claim 94, wherein said first switch comprises a plurality of said pairs of conductors.

98. A picture display device according to claim 97, wherein the said first contact of each of said plurality of said pairs of conductors are electrically interconnected.

99. A picture display device according to claim 98, wherein the said first contact of each of said plurality of said pairs of conductors are in the form of a suitable single electrical contact.

100. A picture display device according to claim 98, wherein said single electrical contact is in the form of a conducting band on said upper inner wall portion.

101. A picture display device according to claim 97, wherein the said second contact of each of said plurality of said pairs of conductors are electrically interconnected.

102. A picture display device according to claim 101, wherein the said second contact of each of said plurality of said pairs of conductors are in the form of a suitable single electrical contact.

103. A picture display device according to claim 101, wherein said single electrical contact is in the form of a conducting band on said upper outer wall portion.

104. A picture display device according to claim 94, wherein said dynamic contact element is substantially spherical.

105. A picture display device according to claim 94, wherein said dynamic contact element comprises a suitable liquid droplet.

106. A picture display device according to claim 105, wherein said liquid droplet comprises a water droplet.

107. A picture display device according to claim 94, wherein said fluid medium comprises a suitable liquid including oil.

108. A picture display device according to claim 94, wherein said closed loop is substantially annular.

110. A picture display device according to claim 83, wherein said sequencing means comprises a second switch for electrically connecting between at least one pair of electrical conductors, one conductor of said pair being electrically connectable to a suitable power source and the other conductor of said pair being connectable to a corresponding frame circuit board, said second switch comprising:

an inner substantially non-electrically-conducting ring and an outer concentric substantially non-electrically-conducting ring;

at least one said pair of conductors, one said conductor of said pair comprising a suitable first electrical contact on said inner ring, and the other said conductor comprising a suitable second electrical contact on said outer ring;

an electrically-conductive dynamic contact element, substantially extending at least between said first electrical contact and said second electrical contact;

a suitable motor suitably operatively connected to at least one of said inner ring, said outer ring and said contact element such as to provide relative rotational motion between said contact element and at least one of said inner ring and said outer ring;

whereby when said motor provides suitable relative rotational motion between said contact element and at least one of said inner ring and said outer ring, the said dynamic element is brought alternately to a position providing electrical contact between said first contact and said second contact and to a position in which said first contact and said second contact are electrically disconnected.

111. A picture display device according to claim 110, wherein said motor is a flat electrical motor operatively connectable to any suitable electrical power source.

112. A picture display device according to claim 110, wherein said first contact and said second contact of each said pair of conductors are substantially facing one another.

113. A picture display device according to claim 110, wherein said second switch comprises a plurality of said pairs of conductors.

114. A picture display device according to claim 113, wherein the said first contact of each of said plurality of said pairs of conductors are electrically interconnected.

115. A picture display device according to claim 114, wherein the said first contact of each of said plurality of said pairs of conductors are in the form of a suitable single electrical contact.

116. A picture display device according to claim 114, wherein said single electrical contact is in the form of a conducting band on said inner ring.

117. A picture display device according to claim 114, wherein the said second contact of each of said plurality of said pairs of conductors are electrically interconnected.

118. A picture display device according to claim 117, wherein the said second contact of each of said plurality of said pairs of conductors are in the form of a suitable single electrical contact.

119. A picture display device according to claim 117, wherein said single electrical contact is in the form of a conducting band on said outer ring.

120. A picture display device according to claim 110, wherein said inner ring and said outer ring are substantially static, and said dynamic element is suitably carried on a rotor arm operatively connected to said motor capable of rotating about the common axis of said inner ring and said outer ring.

121. A picture display device according to claim 110, wherein said dynamic contact element comprises a suitable electrical conductor.

123. A picture display device according to claim 83, wherein said sequencing means comprises a third switch for electrically connecting between a first electrical conductor and a plurality of electrical output conductors, said first electrical conductor being electrically connectable to a suitable power source and each said electrical output conductor being connectable to a corresponding frame circuit board, said third switch comprising:

a base;

a plurality of suitable bimetallic strips, each said bimetallic strip being suitably attached at a first end thereof to said base, said bimetallic strips being reversibly deformable from a first configuration to a second configuration in response to at least a predetermined change in temperature of said bimetallic strip, such that the second end of each said bimetallic strip is correspondingly displaced from a first position to a second position, respectively;

a first electrical conductor electrically connected at least to each said first ends of said bimetallic strips;

a second electrical conductor spaced from said base, said second end of each said bimetallic strip being substantially free to reciprocate between said first position and said second position, respectively capable of establishing and breaking electrical contact between said bimetallic strip and said second electrical conductor;

said first electrical conductor and said second electrical conductor being operatively connectable to a suitable electrical power source;

said bimetallic strips being electrically heatable to at least to said predetermined change in temperature when said second ends thereof are in electrical contact with said second conductor;

a plurality of electrical output conductors, wherein each said output conductor is suitably disposed with respect to said second end of a corresponding said bimetallic strip such that said output conductor may be brought into common electrical contact with said corresponding bimetallic strip and said second conductor only when said corresponding bimetallic strip is in electrical contact with said second conductor;

characterised in that the heating and/or cooling rates of at least one of the said plurality of bimetallic strips may be different from the heating and/or cooling rates, respectively, of at least one other bimetallic strip, wherein said difference in heating and/or cooling rates enables at least one said output conductor to be electrically connected to a corresponding bimetallic strip and said second conductor while at least another said output conductor is concurrently electrically disconnected from its corresponding bimetallic strip and said electrical conductor.

124. A picture display device according to claim 123, wherein said first electrical conductor and said second electrical conductor are electrically connected to a suitable electrical power source.

125. A picture display device according to claim 123, wherein said first electrical conductor and said base are integral.

126. A picture display device according to claim 123, wherein said first electrical conductor and said second electrical conductor are substantially parallel.

127. A picture display device according to claim 123, wherein at least one said electrical output conductor is suitably attached to corresponding said bimetallic strip.

128. A picture display device according to claim 123, further comprising at least one common bimetallic strip in series with said first electrical conductor and/or said second electrical conductor.

129. A picture display device according to claim 128, wherein said at least common bimetallic strip has a heating rate which is substantially slower than the heating rate of any one of said plurality of bimetallic strips.

130. A picture display device according to claim 128, wherein said at least common bimetallic strip has a cooling rate which is substantially slower than the heating rate of any one of said plurality of bimetallic strips.

131. A picture display device according to claim 123, wherein said plurality of bimetallic strips are substantially parallel one to another.

133. A picture display device according to claim 83, wherein said sequencing means comprises a third switch for electrically connecting between a first electrical conductor and a plurality of electrical output conductors, said first electrical conductor being electrically connectable to a suitable power source and each said electrical output conductor being connectable to a corresponding frame circuit board, said third switch comprising:

a base;

a plurality of suitable piezoelectric elements, each said piezoelectric element being suitably attached at a first end thereof to said base, each said piezoelectric element being vibratory between a first amplitude and a second amplitude in response to the supply of a suitable electrical current and/or voltage to said piezoelectric element, such that the second end of each said piezoelectric elements is correspondingly displaced from a first position to a second position, respectively;

a first electrical conductor electrically connected at least to each said first ends of said piezoelectric elements;

a second electrical conductor spaced from said base, said second end of each said piezoelectric elements being substantially free to reciprocate between said first position and said second position, respectively capable of establishing and breaking electrical contact between said piezoelectric elements and said second electrical conductor;

said first electrical conductor and said second electrical conductor being operatively connectable to a suitable electrical power source;

said piezoelectric elements being vibratory when said second ends thereof are in electrical contact with said second conductor;

a plurality of electrical output conductors, wherein each said output conductor is suitably disposed with respect to said second end of a corresponding said piezoelectric element such that said output conductor may be brought into common electrical contact with said corresponding piezoelectric element and said second conductor only when said corresponding piezoelectric element is in electrical contact with said second conductor;

characterised in that the phase of vibration of at least one of the said plurality of piezoelectric elements may be different from the phase of vibration of at least one other piezoelectric element, wherein said phase difference enables at least one said output conductor to be electrically connected to a corresponding piezoelectric element and said second conductor while at least another said output conductor is concurrently electrically disconnected from its corresponding piezoelectric element and said electrical conductor.

134. A picture display device according to claim 133, wherein said first electrical conductor and said second electrical conductor are electrically connected to a suitable electrical power source.

135. A picture display device according to claim 133, wherein said first electrical conductor and said base are integral.

136. A picture display device according to claim 133, wherein said first electrical conductor and said second electrical conductor are substantially parallel.

137. A picture display device according to claim 133, wherein at least one said electrical output conductor is suitably attached to corresponding said piezoelectric element.

138. A picture display device according to claim 133, wherein said plurality of piezoelectric elements are substantially parallel one to another.

139. A picture display device according to claim 133, wherein said difference in phase of vibration between adjacent piezoelectric elements is achieved by live-connecting the said power source to said first ends of said plurality of piezoelectric elements at a predetermined rate.

140. A method for manufacturing the device of claim 20, comprising the steps of:

(a) preparing a suitable substrate;

(b) printing a plurality of bases on said substrate corresponding to each cell of said device using a suitable printing material, each said base being suitably spaced with respect to an adjacent base;

(c) for each said base, printing corresponding said electrical input connection means and said electrical output connection means using a suitable conducting ink;

(d) applying a layer of thermochromic material over said substrate, bases and input and output connection means.

141. A method for manufacturing the device of claim 27, comprising the steps of:

(a) preparing a suitable substrate;

(b) preparing a suitable zebra plate comprising a plurality of bimaterial elements and applying a layer of said second colour over the exposed face of said second layer of said bimaterial elements;

(c) printing a plurality of bases on said substrate corresponding to each cell of said device using a suitable printing material, each said base being suitably spaced with respect to an adjacent base;

(d) for each said base, printing corresponding said electrical input connection means and said electrical output connection means using a suitable conducting ink;

(e) applying a colour layer of said first colour over said first area of each cell;

(f) bonding said zebra plate onto said substrate such that each bimaterial element of said strip is bonded to a corresponding set of bases;

(g) cutting each bimaterial element adhered to each set of bases into individual bimaterial strips for each cell.

142. A method for manufacturing the device of claim 28, comprising the steps of:

(a) preparing a suitable substrate;

(b) preparing a suitable zebra plate comprising a plurality of bimaterial elements and applying a layer of said first colour over the exposed face of said first layer of said bimaterial strips, said bimaterial strips being in said first configuration at least at said first temperature;

(c) printing a plurality of bases on said substrate corresponding to each cell of said device using a suitable printing material, each said base being suitably spaced with respect to an adjacent base;

(d) for each said base, printing corresponding said electrical input connection means and said electrical output connection means using a suitable conducting ink;

(e) applying a colour layer of said second colour over said second area of each cell;

(f) preheating said zebra plate to a predetermined temperature such that said bimaterial elements are substantially perpendicular to said zebra plate;

(g) bonding said zebra plate onto said substrate substantially at said predetermined temperature such that each bimaterial element of said strip is bonded to a corresponding set of bases;

(h) cutting each bimaterial element adhered to each set of bases into individual bimaterial strips for each cell.

143. A method for manufacturing the device of claim 29, comprising the steps of:

(a) preparing a suitable substrate;

(b) preparing a suitable zebra plate comprising a plurality of bimaterial elements and applying a layer of said first colour over the exposed face of said first layer of said bimaterial strips, and a layer of said second colour over the exposed face of said second layer of said bimaterial strips, said bimaterial strips being in said first configuration at least at said first temperature;

(c) printing a plurality of bases on said substrate corresponding to each cell of said device using a suitable printing material, each said base being suitably spaced with respect to an adjacent base;

(d) for each said base, printing corresponding said electrical input connection means and said electrical output connection means using a suitable conducting ink;

(e) applying a colour layer of said second colour over said second area of each cell;

(f) applying a colour layer of said first colour over said first area of each cell;

(g) preheating said zebra plate to a predetermined temperature such that said bimaterial elements are substantially perpendicular to said zebra plate;

(h) bonding said zebra plate onto said substrate substantially at said predetermined temperature such that each bimaterial element of said strip is bonded to a corresponding set of bases;

(i) cutting each bimaterial element adhered to each set of bases into individual bimaterial strips for each cell.

145. A method for manufacturing the device of claim 42, comprising the steps of:

(a) preparing a suitable substrate;

(b) suitably bonding a first spacing layer onto said substrate;

(c) forming a well in said first spacing layer corresponding to each said colour cell;

(d) printing suitable electrical input means or electrical output means in said well using a suitable conducting ink;

(e) inserting said actuator element in said well at least over said electrical input connection means or said electrical output connection;

(f) printing suitable electrical output means or electrical input means, respectively, over said actuator element using a suitable conducting ink.

(g) suitably aligning and bonding a second spacing layer onto said first layer around the periphery of each said well, said second spacing layer comprising suitable indentations over the upper surface thereof corresponding to said concavities of said cells;

(h) cutting suitable slots in said second spacing layer to separate said movable element from said second spacing layer;

(i) suitably bonding a third spacing layer onto said second spacing element and forming an aperture on said third element at least equal to the cross-sectional profile of said movable element;

(j) suitably bonding said upper transparent layer onto said third spacing layer,

(k) applying a colour layer of said second colour either in step (a) optionally above or below said substrate, or in step (g) on the lower surface of said second spacing element prior to bonding same onto said first spacing layer.

146. A method for manufacturing the device of claim 54, comprising the steps of:

(a) preparing a suitable substrate;

(b) suitably aligning and bonding said second transparent layer onto said substrate, said second transparent layer comprising suitable indentations over the upper surface thereof corresponding to said concavities of said cells;

(c) forming at least one suitable well in said second transparent layer corresponding to each said colour cell;

(d) printing suitable electrical input means or electrical output means in said well using a suitable conducting ink;

(e) inserting said actuator element in said well at least over said electrical input connection means or said electrical output connection;

(f) printing suitable electrical output means or electrical input means, respectively, over said actuator element using a suitable conducting ink.

(g) aligning and suitably bonding said first transparent layer onto said actuator element and/or said electrical output means, or electrical input means respectively;

(h) cutting suitable slots in said first transparent layer to separate said transparent layer into sections each corresponding to said cells;

(i) applying a colour layer of said first colour in step (a) optionally above or below said substrate.

147. A picture display device as claimed in claim 1 adapted for use as a display for an in-flight entertainment system.

148. A picture display device as claimed in claim 1 adapted for use as a display for an electronic or electromechanical slot-machine.

149. A picture display device as claimed in claim 1 adapted for use as a display of an electronic game.

150. A picture display device according to claim 1, wherein said device is attachable to an article of manufacture.

151. A picture display device according to claim 1, wherein said device is attachable to packaging means.

152. A picture display device according to claim 151, wherein said device is integral with said packaging means.

153. A picture display device according to claim 1, further comprising suitable interface means for using said device as a suitable display screen optionally for use with a computer, television/video means or telephone means.

154. A picture display device according to claim 81, wherein said frame circuit cards are suitably configured such as to enable said device to display images corresponding to normally-printed matter including texts and pictures.

155. A picture display device according to claim 154, wherein said printed matter includes any book, newspaper, magazine, booklet, manual, greeting card, personal card, seasonal card, visiting card, advertisement card, postage and other stamp, postcard, sticker, label, poster, banner, flag, emblem, badge, prospectus, illustration guide, map, picture, and printed propaganda, among others.

156. A picture display device according to claim 81, further comprising suitable chronometer means operatively connected thereto, wherein said frame circuit cards are suitably configured such as to enable said device to display images corresponding to the time and/or the date.

157. A picture display device according to claim 81, further comprising suitable meter means operatively connected thereto, wherein said frame circuit cards are suitably configured such as to enable said device to display images corresponding to the magnitude of a variable quantified by said meter.

158. A picture display device according to claim 81, further comprising suitable chronometer means operatively connected thereto, wherein said frame circuit cards are suitably configured such as to enable said device to display different images according to the current to the time and/or the date.

159. A picture display device according to claim 158, wherein said device is suitably configured as a traffic or road sign.

160. A picture display device according to claim 81, wherein said device is adapted for use as a lottery ticket.

161. A picture display device according to claim 81, wherein said device is adapted for use as a credit card.

162. A picture display device according to claim 81, wherein said device is adapted for use as an identity card or identity document.

163. A picture display device according to claim 81, wherein said device is adapted for use as a billboard for outdoor use.

2. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of emitting electromagnetic energy at least in the form of visible light, each said colour cell comprising:

at least one pair of electrodes comprising a lower electrode comprised on said substrate and an upper electrode superposed and distanced from said lower electrode;

said at least one pair of electrodes capable of being electrically connected to at least one suitable electrical power source capable of providing at least a predetermined voltage and/or current between said upper electrode and said lower electrode of said at least one pair of electrodes;

at least one dielectric layer comprised of suitable dielectric material disposed intermediate said upper electrode and said lower electrode of said at least one pair of electrodes;

wherein said dielectric layer comprises at least one luminescent layer of luminescent material substantially parallel to and in electrical contact with at least one of said upper electrode and said lower electrode of said at least one pair of electrodes, said at least one luminescent layer being capable of emitting electromagnetic energy at least in the form of visible light in response to the establishment of said predetermined voltage and/or current between said upper electrode and said lower electrode of said at least one pair of electrodes, wherein said emission of said visible light is such as to be capable of being observed from the exterior of said colour cell.

18. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour, each said colour cell comprising:

an electrically heatable base comprising at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said base to a suitable electrical power source, said base capable of being electrically heated at least from a first temperature to at least a second temperature in response to the supply of a predetermined voltage and/or current thereto;

thermally responsive colour change means in thermal contact with said base, said colour change means enabling said cell to exhibit a colour change from said first colour to said second colour in response to said temperature change of the said base from said first temperature to said at least second temperature.

33. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour, each said colour cell comprising:

a colour layer superposed on said substrate;

a layer of liquid crystal material comprising at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said liquid crystal layer to a suitable electrical power source, said liquid crystal layer capable of exhibiting a colour change in response to the supply of a predetermined voltage and/or current thereto;

said layer of liquid crystal material being substantially superposed over said colour layer and substantially spaced therefrom by at least a suitable clearance.

35. A picture display device according to claim 34, wherein said liquid crystal layer is capable of exhibiting a colour change from said first colour to colourless in response to the supply of a predetermined voltage and/or current to said liquid crystal layer, and wherein said colour layer is of said second colour, such that the said colour cell may exhibit said second colour when said liquid crystal layer is colourless, wherein said first colour is the colour exhibited by the said liquid crystal layer when opaque.

36. A picture display device according to claim 34, wherein said liquid crystal layer is capable of exhibiting a colour change from colourless to said second colour in response to the supply of a predetermined voltage and/or current to said liquid crystal layer, and wherein said colour layer is of said first colour, such that the said colour cell may exhibit said first colour when said liquid crystal layer is colourless wherein said second colour is the colour exhibited by the said liquid crystal layer when opaque.

37. A picture display device according to claim 34, further comprising light scattering means.

38. A picture display device according to claim 37, wherein said light scattering means comprise a layer of water droplets disposed over said liquid crystal layer and suitably electrically insulated at least therefrom.

39. A picture display device according to claim 37, wherein said light scattering means comprises a layer of light diffractive material comprising at least one of light scattering centres.

40. A picture display device according to claim 39, wherein said at least one light scattering centre comprise substantially hemispherical protrusions.

144. A method for manufacturing the device of claim 34, comprising the steps of:

(a) preparing a suitable substrate;

(b) printing a colour layer on said substrate;

(c) printing suitable spacers along the periphery of each cell;

(d) forming suitable substantially colourless electrical input means or electrical output means over said spacers using a paste mask method in which desired parts of a foil of suitable material superposed over said spacers is rendered, or remains conductive, while other parts remain, or are rendered, respectively, non-conductive;

(e) applying a layer of suitable liquid crystal material at least over said electrical input connection means or said electrical output connection;

(f) forming suitable substantially colourless electrical output means or electrical input means, respectively, over said liquid crystal material using a paste mask method.

41. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour, each said colour cell comprising:

an upper substantially transparent layer comprising an inverted substantially transparent prismatic element protruding from a lower surface thereof, said transparent layer being superposed over said substrate and distanced therefrom by suitable spacing means;

a substantially transparent movable element comprising an upper concavity complementary to and substantially aligned with said prismatic element, said movable element capable of being displaced a first distance between a first position and a second position, wherein in said first position said concavity is spaced from said prismatic element by a predetermined spacing, and wherein in said second position said concavity is substantial direct optical contact with said prismatic element;

a colour layer comprising said second colour disposed below said movable element and in optical communication therewith;

guiding means for enabling said movable element to reciprocate between said first position and said second position;

at least one actuator element in abutting contact with said movable element comprising at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said actuator element to a suitable electrical power source, said actuator element characterised in being capable of increasing at least one dimension thereof in the direction of displacement of said movable element by said first distance in response to the supply of a predetermined voltage and/or current thereto, thereby displacing said movable element to said first position;

whereby said at least one actuator element increases said at least one dimension thereof by said first distance in response to the supply of a predetermined voltage and/or current to said actuator element, thereby propelling said movable element from said first position to said second position and bringing said concavity is substantial direct optical contact with said prismatic element thereby enabling said second colour on said colour layer to be exhibited by said colour cell, and whereby said actuator element returns to its datum dimension when said electrical power source is subsequently disconnected or alternatively when the polarity of the said voltage and/or current supply is reversed, returning said movable element to the said first position and establishing said spacing between said prismatic element and said concavity, said prismatic element having a configuration such as to internally reflect light entering said cell via said upper transparent layer thereby enabling said colour cell to exhibit a first colour as determined by the reflection of external light by said prismatic element.

53. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour, each said colour cell comprising:

a first, upper, substantially transparent layer comprising an inverted substantially transparent prismatic element protruding from a lower surface thereof;

said transparent layer being superposed over;

a second, lower, substantially transparent layer comprising an upper concavity complementary to and substantially aligned with said prismatic element, said second transparent layer being superposed over said substrate;

said first transparent layer capable of being displaced a first distance between a first position and a second position, wherein in said first position said concavity is substantial direct optical contact with said prismatic element, and wherein in said second position said concavity is spaced from said prismatic element by a predetermined spacing;

a colour layer comprising said first colour disposed below said second transparent layer and in optical communication therewith;

at least one actuator element in abutting contact with first transparent layer comprising at least one suitable electrical input connection means and at least one suitable electrical output connection means capable of connecting said at least one actuator element to a suitable electrical power source, said at least one actuator element characterised in being capable of increasing at least one dimension thereof in the direction of displacement of said first transparent layer by said first distance in response to the supply of a predetermined voltage and/or current thereto, thereby displacing said first transparent layer to said first position;

whereby said actuator element increases said at least one dimension thereof by said first distance in response to the supply of a predetermined voltage and/or current to said actuator element, thereby propelling said first transparent layer from said first position to said second position and establishing said spacing between said prismatic element and said concavity, said prismatic element having a configuration such as to internally reflect light entering said cell via said upper transparent layer thereby enabling said colour cell to exhibit a second colour as determined by the reflection of external light by said prismatic element, and whereby said actuator element returns to its datum dimension when said electrical power source is subsequently disconnected or alternatively when the polarity of the said voltage and/or current supply is reversed, returning said first transparent layer to the said first position and bringing said concavity is substantial direct optical contact with said prismatic element thereby enabling said first colour on said colour layer to be exhibited by said colour cell.

65. A picture display device comprising a suitable substrate carrying a plurality of colour cells wherein each colour cell is capable of exhibiting a change in its external colour from a first colour to a second colour, each said colour cell comprising:

a layer of electrochromic material comprised on said substrate, said electrochromic material capable of changing colour from said first colour to second colour in response to the passage of a suitable electrical current therethrough and/or the application of a suitable voltage thereto;

at least one pair of electrical conductors in electrical contact with said electrochromic layer, said pair of electrical conductors capable of being electrically connected to a suitable electrical power source and being adapted to provide a suitable current and/or voltage to said electrochromic layer such as to enable said cell to exhibit a colour change from said first colour to second colour.

93. A first switch for electrically connecting between at least one pair of electrical conductors comprising:

a suitable substantially non-electrically-conducting fluid medium in the form of a closed loop and having a free upper surface;

said closed loop bounded by at least an inner wall and an outer wall, said inner and outer walls being concentric one to the other and comprising an upper inner wall portion and an inner wall portion, respectively, protruding from the mean level of the said fluid free surface;

at least one said pair of conductors, one said conductor of said pair comprising a suitable first electrical contact on said upper inner wall portion, and the other said conductor comprising a suitable second electrical contact on said upper outer wall portion;

at least one electrically actuable oscillating element immersed in said fluid medium capable of providing at least one travelling wave on said free surface in response to suitable vibrations thereof;

an electrically-conductive dynamic contact element, substantially on said free surface and capable of being carried by said wave, said contact element extending at least between said first electrical contact and said second electrical contact;

whereby when said oscillating element is suitably vibrated, at least one travelling wave is provided on said free surface carrying the said dynamic element along said free surface element alternately to a position providing electrical contact between said first contact and said second contact and to a position in which said first contact and said second contact are electrically disconnected.

109. A second switch for electrically connecting between at least one pair of electrical conductors comprising:

an inner substantially non-electrically-conducting ring and an outer concentric substantially non-electrically-conducting ring;

at least one said pair of conductors, one said conductor of said pair comprising a suitable first electrical contact on said inner ring, and the other said conductor comprising a suitable second electrical contact on said outer ring;

an electrically-conductive dynamic contact element, substantially extending at least between said first electrical contact and said second electrical contact;

a suitable motor suitably operatively connected to at least one of said inner ring, said outer ring and said contact element such as to provide relative rotational motion between said contact element and at least one of said inner ring and said outer ring;

whereby when said motor provides suitable relative rotational motion between said contact element and at least one of said inner ring and said outer ring, the said dynamic element is brought alternately to a position providing electrical contact between said first contact and said second contact and to a position in which said first contact and said second contact are electrically disconnected.

122. A third switch for electrically connecting between a first electrical conductor and a plurality of electrical output conductors comprising:

a base;

a plurality of suitable bimetallic strips, each said bimetallic strip being suitably attached at a first end thereof to said base, said bimetallic strips being reversibly deformable from a first configuration to a second configuration in response to at least a predetermined change in temperature of said bimetallic strip, such that the second end of each said bimetallic strip is correspondingly displaced from a first position to a second position, respectively;

a first electrical conductor electrically connected at least to each said first ends of said bimetallic strips;

a second electrical conductor spaced from said base, said second end of each said bimetallic strip being substantially free to reciprocate between said first position and said second position, respectively capable of establishing and breaking electrical contact between said bimetallic strip and said second electrical conductor;

said first electrical conductor and said second electrical conductor being operatively connectable to a suitable electrical power source;

said bimetallic strips being electrically heatable to at least to said predetermined change in temperature when said second ends thereof are in electrical contact with said second conductor;

a plurality of electrical output conductors, wherein each said output conductor is suitably disposed with respect to said second end of a corresponding said bimetallic strip such that said output conductor may be brought into common electrical contact with said corresponding bimetallic strip and said second conductor only when said corresponding bimetallic strip is in electrical contact with said second conductor;

characterised in that the heating and/or cooling rates of at least one of the said plurality of bimetallic strips may be different from the heating and/or cooling rates, respectively, of at least one other bimetallic strip, wherein said difference in heating and/or cooling rates enables at least one said output conductor to be electrically connected to a corresponding bimetallic strip and said second conductor while at least another said output conductor is concurrently electrically disconnected from its corresponding bimetallic strip and said electrical conductor.

132. A fourth switch for electrically connecting between a first electrical conductor and a plurality of electrical output conductors comprising:

a base;

a plurality of suitable piezoelectric elements, each said piezoelectric element being suitably attached at a first end thereof to said base, each said piezoelectric element being vibratory between a first amplitude and a second amplitude in response to the supply of a suitable electrical current and/or voltage to said piezoelectric element, such that the second end of each said piezoelectric elements is correspondingly displaced from a first position to a second position, respectively;

a first electrical conductor electrically connected at least to each said first ends of said piezoelectric elements;

a second electrical conductor spaced from said base, said second end of each said piezoelectric elements being substantially free to reciprocate between said first position and said second position, respectively capable of establishing and breaking electrical contact between said piezoelectric elements and said second electrical conductor;

said first electrical conductor and said second electrical conductor being operatively connectable to a suitable electrical power source;

said piezoelectric elements being vibratory when said second ends thereof are in electrical contact with said second conductor;

a plurality of electrical output conductors, wherein each said output conductor is suitably disposed with respect to said second end of a corresponding said piezoelectric element such that said output conductor may be brought into common electrical contact with said corresponding piezoelectric element and said second conductor only when said corresponding piezoelectric element is in electrical contact with said second conductor;

characterised in that the phase of vibration of at least one of the said plurality of piezoelectric elements may be different from the phase of vibration of at least one other piezoelectric element, wherein said phase difference enables at least one said output conductor to be electrically connected to a corresponding piezoelectric element and said second conductor while at least another said output conductor is concurrently electrically disconnected from its corresponding piezoelectric element and said electrical conductor.