Patent ID: 7525085
Filing Date: 2009-04-28
Classification: G01D

Abstract:
1. An optical encoding apparatus for the detection of position and/or motion of a mechanical device, the apparatus comprising: a codescale; an encoder housing having one or more portions; a light-detecting sensor embedded within the encoder housing; and a processing device linked to the light-detecting sensor and configured to determine an amount of light received by each light-detection element, the processing device being configured to determine at least one of a linear offset and an angular offset of the codescale with respect to the encoder housing based on signals received from the light-detecting sensor, wherein the light-detecting sensor is capable of sensing a pattern produced by the codescale superimposed on the light-detecting sensor, and wherein the light-detecting sensor includes a two-dimensional array of light detection elements having dimensions n-by-m where n and m are both integers greater than 4, a vertical dimension of the two-dimensional array of light detection elements being longer than a corresponding vertical dimension of the pattern produced by the codescale so that some of the light detection elements along the vertical dimension of the two-dimensional array are not affected by the pattern on the light-detecting sensor when the codescale is displaced with respect to the encoder housing, the vertical dimension being the dimension along a direction orthogonal to the moving direction of the codescale relative to the encoder housing.