| 摘要 |
PURPOSE:To read immediately an absolute position from the origin of a measure reading part by adding code patterns indicating specific positions to a scale plate and detecting these positions independently of the length and the direction of movement of the measure reading part. CONSTITUTION:The position of a code pattern 4 which faces a measure reading part 2 is detected to read the position of the measure reading part 2 in units of a pitch (p) of index graduations 5. A reading circuit part 13 reads a cell of a linear image sensor 10 which the index graduation 3 in a visual field 17 of the linear image sensor 10 faces. The place of this cell out of individual cells constituting the linear image sensor 10 is read, and a relative positional relation between the measure reading part 2 and the index graduation 3 is calculated on a basis of the address of this cell to calculate the position of the measure reading part 2 within the range of the visual field in minute units. |
