Display device

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.