Abstract: The invention relates to a method and a device for optically determining the position of an object in a particular area of a substantially plane surface. According to the invention at least one directional single-point emitter associated with at least two directional single-point light receivers covering the particular area are disposed near said particular area, each light emitter and receiver having an axis substantially parallel to the particular area and on which maximum emission, respectively maximum sensing angle, is observed, so that the axes of the receivers intersect the axis of the emitter at different points. The light emitter is energized and the position of the object on the axis of the emitter is determined as a function of a comparison of the light signals reflected and diffused by the object toward each of the two light receivers.

Abstract: This detection method comprises: a step during which a receiver measures the quantity of light reflected by an object when the object is illuminated by an emitter for at least two different emitter—receiver pairs on the same side relative to the object, a step of calculating at least two characteristic values from the measured values, and a step of determining at least one position of the object by directly reading a table indexed by the two characteristic values, the content of said table being predetermined and set before said measurement step.

Abstract: The present invention relates to a method and to a device enabling data to be input, and also to an optical system for detecting the position of an article or a member and suitable for being used (or incorporated) in such a method (or device). The technical field of the invention is that of making keyboards and similar devices enabling manual input of data for processing by a digital computer. The method of the invention for determining the position of an article in a zone uses the steps of structuring a neural network by training, applying data to the input of the structured neural network, the data being the result of converting signals delivered by a plurality of detectors sensitive to illumination of said zone, and determining the position of the article in the zone as a function of at least one data item output by the structured neural network.