Abstract The invention relates to a particularly simple and economical keyboard, of which the major part, the base, can be made as a one-piece plastics moulding. Thus the base includes two sets of intersecting channels along which radiant energy, particularly light, can be passed, the channels of the first set being perpendicular to the channels of the second set. Keys representing letters, numbers, symbols or the like are arranged at the respective intersections of each pair of channels so as to be capable of controlling the passage of light along the channels. Thus in one embodiment, light is directed along the channels, and the operation of a particular key blocks the passage of the light in the unique pair of channels (one from each of the first and second sets) at whose intersection the particular key is located. Respective photo-electric detectors at one end of each channel produce output signals representative of the particular key operated. A circuit is provided which detects when the energy passing along at least two channels has changed which indicates that at least two keys have been operated.
A keyboard comprising an assembly of keys; a first set of paths along which radiant energy can be passed; a second set of paths, angularly disposed relative to said first set, along which radiant energy can be passed, said keys and said first and second sets of paths being so arranged that, in operation, actuation of a key causes a change in the energy passing along a unique combination of paths including at least one path from each of said sets; and output means for providing an indication of which key has been actuated by detecting the change in energy passing along the unique combination of paths associated with the actuated key, said output means comprising means for detecting when the energy passing along at least two paths of either one of the sets of paths has been changed, whereby to indicate that at least two keys have been actuated.
Claim 2
Dependent Claim
150 words
A keyboard comprising an assembly of keys; a first set of paths along which radiant energy can be passed; a second set of paths, angularly disposed relative to said first set, along which radiant energy can be passed, said keys and said first and second sets of paths being so arranged that, in operation, actuation of a key causes a change in the energy passing along a unique combination of paths including at least one path from each of said sets; and output means for providing an indication of which key has been actuated by detecting the change in energy passing along the unique combination of paths associated with the actuated key, said output means comprising means for detecting when the energy passing along at least two paths of either one of the sets of paths has been changed, whereby to indicate that at least two keys have been actuated.