Light pen input systems
AssigneeU.S. Philips Corporation
InventorsNeil C. Bird, Oliver S. Davies
Life of this patent
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Abstract
A light pen input system includes a light sensing device (10) having a row and column array of light sensing elements (14) over which a light pen (12) is moved to write in information, e.g. for display on a display screen, the light beam emitted by the pen producing a light spot (20) on the array which covers, and is sensed by, adjacent elements and which, with the beam directed perpendicularly to the array, is substantially non-circular in shape, having dimensions in two directions over the array which differ from one another. Rotation of the pen around its axis is then detectable, providing additional functionality. An elongated light spot, e.g. elliptical, rectangular or triangular, provides further capabilities in enabling the width of a written stroke to be varied by twisting the pen.
Claims15
A light pen input system, comprising:
- (a) a light sensing device comprising a planar array of a large plurality of light sensing elements;
- and
- (b) a light pen which emits a light beam, the light beam producing a light spot on the array which light spot is sensed by the light sensing device, the light spot having an area corresponding to a plurality of adjacent light sensing elements, with the light beam directed perpendicular to the plane of the array, the light spot being non-circular and having a dimension in one dimension over the array different to the direction in another direction, and
- said light sensing device sensing rotation of the non-circular spot, whereby rotation of the pen by a user is sensed by the light pen system.
Dependencies are inferred from the claim text.