An encoder pattern with matching aperture pattern, a method for designing said encoder pattern, and an optical shaft encoder in which the encoder pattern and aperture pattern are implemented

摘要

An encoder pattern (1,26,38,48,56,67) comprising at least two encoder tracks (2,3,4,5,27,28,39,40,41,42,43,44,51,52, 53,54,55,56,60,61,62,63,64,65,71,72,73,74,75,76) of alternating optically distinguishable fields (7',8',7a, 7b,7c,8a,8b,8c) periodically arranged with a period Px and an area Ax of the optically distinguishable fields (7',8',7a,7b,7c,8a,8b,8c), said encoder pattern (1, 26, 38, 48, 56, 67), when implemented in an encoder (89) configured for measuring movement and/or speed and/or position, is moved relatively to an aperture pattern (15, 35, 78) and gives rise to a varying encoder output signal. Two encoder tracks (2, 3, 4, 5, 27,28,39,40,41,42,43,44,51,52,53,54, 55,56,60,61,62,63,64,65,71,72,73,74,75,76) have a corresponding aperture track (16,17,18,19,33,34,79,80,81,82, 93,84). Encoder tracks (2,3,4,5,27,28,39,40,41,42,43,44, 51,52,53,54,55,56,60,61,62,63,64,65,71,72,73,74,75,76) with corresponding aperture tracks (16,17,18,3,34,79,80, 81,82,83,84) give rise to a harmonic signal. Harmonic signals can be combined to form sinusoidal encoder output signals. The encoder pattern with matching aperture pattern is configured to provide a very high precision of the encoder it is implemented in. The invention further relates to a method for designing these versatile encoder patterns and a shaft encoder in which encoder pattern and aperture pattern are implemented.