| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a travel distance even in the presence of strong vibration or the attachment of dust and the like. SOLUTION: A moving position of a moving body is detected by relatively moving a scale member and an image detecting means. The image detecting means is composed of a light irradiating member irradiating the light toward the scale member, and an image sensor formed by arranging a predetermined number of image elements detecting the light from the scale member in the moving direction of the moving body, and outputting the image data of the scale member. The scale member has a number of absolute scales composed of the predetermined number of image elements at intervals to allow the image sensor to constantly detect at least one absolute scale, and an absolute identifying part for identifying each absolute scale. The moving position of the moving body is measured with the resolution agreed with an image element pitch by adding or subtracting a value obtained by multiplying the number of image elements from a center in the image element direction of the image sensor to a center of the absolute scale by the image element pitch, to or from a value obtained by multiplying the number of absolute scales detected by the image sensor and identified by the absolute identifying part by the mutual interval of the absolute scales. COPYRIGHT: (C)2004,JPO&NCIPI
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