US 4,772,769 A · Apparatus for selective backlighting of keys of a keyboard

Abstract

An apparatus for selective backlighting individual transluscent keys of a terminal keyboard includes a horizontal, double-sided printed circuit board having a number of right angle LEDs equal to the number of backlit keys mounted on its bottom surface. A plurality of clearance holes in the printed circuit board admit a plurality of vertical light pipes that are integral with a transparent substrate. Integral alignment bosses on a bottom surface of the substrate fit precisely in corresponding holes of the printed circuit board. Each light pipe has a rectangular cross section and a 45 degree inclined bottom surface. A horizontal light beam emitted by a LED passes through a vertical wall of a light pipe, strikes its inclined bottom surface, and is reflected up through the light pipe into a recess within a key. The substrate supports a rubber sheet in which the keys are molded and a switch contact layer with printed conductors thereon. Depression of a key presses a conductive shorting pad against the printed conductors, actuating a switch.

Claims21

Dependent claims

A method of backlighting a keyboard including steps of:

(a) providing a plurality of keys with lens portions that can pass light;
(b) providing a plurality of conductive switch contact elements which cooperate to produce switching signals when the keys are respectively depressed;
(c) supporting a printed circuit board which has a plurality of holes under and in aligned relationship with the plurality of keys, respectively;
(d) supporting a plurality of light sources on a lower surface of the printed circuit board;
(e) supporting a plurality of light pipes to receive light beams from the light sources, respectively and conducting the light beams through the holes of the printed circuit board to the lens portions of the keys by means of the light pipes, respectively;
and
(f) turning on a selected one of the light sources to produce a light beam while leaving another of the light sources off, guiding the light beam into one of the light pipes, and conducting the light beam through that light pipe and through the printed circuit board to the lens portion of a corresponding key, thereby selectively backlighting that key.

4 more elements

A backlit keyboard comprising in combination:

(a) a plurality of flexible keys molded from and supported on a rubber-like sheet, each key having a lens portion and a recess aligned with the lens portion;
(b) a printed circuit board having an upper surface and a lower surface and a plurality of clearance holes aligned with the recesses of the respective keys;
(c) a substrate disposed above the printed circuit board in spaced relationship thereto;
(d) an insulative film disposed on the upper surface of the printed circuit board and a plurality of conductive switch contact elements on an upper surface of the insulative film, and a plurality of clearance holes in the insulative film aligned with the clearance holes of the printed circuit board;
(e) a plurality of light pipes supported by the substrate, each light pipe including an upper section extending upward through a clearance hole in the insulative film into the recess of a corresponding key and a lower section extending downward through a clearance hole in the printed circuit board;
(f) a plurality of inclined reflective surfaces each supported under the printed circuit board on a bottom of the lower section of each respective light pipe;
and
(g) a plurality of right angle light emitting diodes mounted on the lower surface of the printed circuit board adjacent to each clearance hole thereof, respectively, and aimed through a portion of the lower section of a corresponding light pipe at the inclined reflective surface of that light pipe.

5 more elements

Dependencies are inferred from the claim text.

Apparatus for selective backlighting of keys of a keyboard

Life of this patent

Apparatus for selective backlighting of keys of a keyboard

Life of this patent

Abstract

Claims21