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AssigneeKoninklijke Philips Electronics N.V.
InventorsMarcel Schemmann, Carsten Heinks, Paraskevas Dunias, Aalbert Stek
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A method and optical module for measuring relative movement of an input device and object (15) along at least one measuring axis. A laser device (3) having a laser cavity is provided for generating a measuring beam (13) in respect of each measuring axis. The measuring beam (13) is used to illuminate the object (15) and measuring beam radiation reflected from the object (15) and re-entering the laser cavity generates a self-mixing effect in the laser and causes changes in operation of the laser cavity. A detector (4) is used to generate a measurement signal representative of these changes and an electronic processing circuit (18) selects, in dependence on the speed of relative movement, one of at least two parameters of the measurement signal for use in determining the speed and direction of relative movement.
A method of measuring movement of an input device and object (15) relative to each other along at least one measuring axis, the method comprising the steps of illuminating an object surface with a measuring laser beam (13), emitted from the laser cavity of a laser device (3), for each measuring axis, generating a measurement signal representative of changes in operation of the laser cavity, said changes being due to interference of measuring beam radiation re-entering said laser cavity and an optical wave in said laser cavity and being representative of said movement along said at least one measuring axis, selecting, in dependence on the speed of movement of said input device and said object (15) relative to each other, one of at least two parameters of said measurement signal and determining from said selected parameter the speed and direction of said movement, and generating an electric signal representative of said speed and direction of movement.
An optical module for performing a method of measuring movement of an input device and object relative to each other along at least one measuring axis, the optical module comprising a laser device (3) for each measuring axis, said laser device (3) having a laser cavity for generating a measuring laser beam (13), means for illuminating an object surface with said measuring beam (13), detector means (4) for generating a measurement signal representative of changes in operation of the laser cavity, said changes being due to laser self-mixing interference of measuring beam radiation re-entering said laser cavity and an optical wave in said laser cavity and being representative of said movement along said at least one measuring axis, and electronic processing means (18) for selecting, in dependence on the speed of movement of said input device and said object (15) relative to each other, one of at least two parameters of said measurement signal, determining from said selected parameter the speed and direction of said movement and generating an electric signal representative of said speed and direction of movement.
Dependencies are inferred from the claim text.