| 摘要 |
PURPOSE:To raise the resolution, and also, to improve the position detecting accuracy by providing a light emitting means and a light receiving means on one face and the other face, respectively of a band-like code plate having an opening whose width in the longitudinal direction corresponds to an absolute position, and whose height is constant. CONSTITUTION:In the title encoder of a linear type, a band-like code plate 6 is provided with an opening 61 whose width (s) along the longitudinal direction (the right and left direction in the figure) corresponds to an absolute position, but whose height (d) in the direction (height direction in the figure) being orthogonal to the longitudinal direction is constant. Also, a light emitting means 31 and a light receiving means 3 are provided so as to be opposed to one face of the code plate 6, and the other face, respectively, and also, a period T of the opening 61 is made constant. In this state, light is radiated to the opening 61 by the means 31, the light which has passed through the opening 61 is received by the means 3, and also, in a period corresponding to the period T, the light which has passed through the corresponding opening 61 is selected so that the detection of a representative absolute position is completed. In such a way, the influence based on ununiformity [ununiformity in the height (d) direction in the figure] of the light emission intensity of the means 31 is obviated. |
