Light distribution for illuminated keyboard switches and displays

A backlit display, said display comprising:

• an at least partially light transmissive outer cover;
• at least one light source means for illuminating at least a portion of said cover, said at least one light source means having a variable light intensity distribution along said at least a portion of said cover;
• and
• at least one means for modifying said light intensity distribution along said at least a portion of said cover, said modifying means located at least partially between said light source and said cover and comprising a variable transmittance layer, said variable transmittance layer comprising a photoemulsion negative of light distribution from said light source means membrane at said modifying means.

A multi-layer backlit membrane switch, said switch comprising:

• an at least partially light transmissive external membrane switch cover including a key;
• at least one electrical switch;
• at least one light source means for illuminating at least a portion of said cover, said at least one light source means having a light intensity distribution along said at least a portion of said cover;
• and
• an at least partially light transmissive layer located at least partially between said switch cover and said light source means, said layer including at last one means for reducing light transmittance in a direction parallel to said membrane switch, said reducing means comprising at least one slot, said at least one slot not completely surrounding said key.

A backlit display, said display comprising:

• an at least partially light transmissive outer cover;
• at least one light source means for illuminating at least a portion of said cover;
• and
• an at least partially light transmissive layer located at least partially between said outer cover and said light source means, said layer including at least one means for reducing light transmittance in a direction parallel to said backlit display, said reducing means comprising at least one slot, said at least one slot not completely surrounding at least one limited area of said cover.

A multi-layer backlit membrane switch, said switch comprising:

• an at least partially light transmissive external membrane switch cover;
• at least one electrical switch;
• at least one light source means for illuminating at least a portion of said cover, said at least one light source means having a light intensity distribution along said at least a portion of said cover;
• at least one means for modifying said light intensity distribution along said at least a portion of said cover, said modifying means located at least partially between said light source and said switch cover and comprising a variable transmittance layer, wherein said layer is comprised of an at least partially light transmissive material, at least portions of which are covered by a material at least partially reflective of visible light from said light source means, said covered portions comprising a percentage of the area of said layer, said percentage varying along said layer;
• a further visible light reflective layer means, located with said light source means at least partially between said light reflective layer means and said switch cover, for reflecting visible light from said at least partially reflective material back towards said switch cover;
• and
• an at least partially light transmissive spacer layer at least partially between said further visible light reflective layer means and said at least partially reflective material.

A backlit display, said display comprising:

• an at least partially light transmissive outer cover;
• at least one light source means for illuminating at least a portion of said cover, said at least one light source means having a light intensity distribution along said at least a portion of said cover;
• at least one means for modifying said light intensity distribution along said at least a portion of said cover, said modifying means located at least partially between said light source and said cover and comprising a variable transmittance layer, wherein said layer is comprised of an at least partially light transmissive material, at least portions of which are covered by a material at least partially reflective of visible light from said light source means, said covered portions comprising a percentage of the area of said layer, said percentage varying along said layer;
• a further visible light reflective layer means, located with said light source means at least partially between said light reflective layer means and said cover, for reflecting visible light from said at least partially reflective material back towards said cover;
• and
• an at least partially light transmissive spacer layer at least partially between said further visible light reflective layer means and said at least partially reflective material.

A method of providing an even distribution of light at a specific plane from a light source means, said method comprising the steps of:

• providing a light transmissive substrate covered with a reflective layer, said layer coated with a positive photoresist, positive photoresist is defined as photoresist which is not polymerized by exposure to light and is polymerized by the lack of exposure to light, after completing photoresist processing;
• making a negative, by a photographic process, of the light distribution from said light source means at said plane;
• locating said negative over said photoresist covered reflective layer;
• exposing said photoresist layer to light travelling through said negative;
• processing said substrate to polymerize any non-exposed photoresist;
• etching all unpolymerized photoresist and associated portions of said reflective layer from said substrate;
• and
• locating said substrate at said plane with said reflective layer towards said light source means, whereas said substrate blocks a greater portion of light from said light source means where the illumination level is higher and said substrate blocks a lesser portion of light from said light source means where the illumination level is lower, resulting in the appearance to an observer of a generally even level of illumination at said plane.

A method of providing an even distribution of light at a specific plane from a light source means, said method comprising the steps of:

• providing a light transmissive substrate covered with a reflective layer, said layer coated with a negative photoresist, negative photoresist is defined as photoresist which is polymerized by exposure to light and is not polymerized by the lack of exposure to light, after completing photoresist processing;
• temporarily locating said substrate and said photoresist covered reflective layer at said plane over said light source means;
• exposing said photoresist layer to light from said light source means;
• processing said substrate to polymerize any non-exposed photoresist;
• etching all unpolymerized photoresist and associated portions of said reflective layer from said substrate;
• and
• locating said substrate at said plane with said reflective layer towards said light source means, whereas said substrate blocks a greater portion of light from said light source means where the illumination level is higher and said substrate blocks a lesser portion of light from said light source means where the illumination level is lower, resulting in the appearance to an observer of a generally even level of illumination at said plane.