| 摘要 |
PURPOSE:To enable compactness to be attained by determining the position of a table through height of six wedge mechanisms so as to prevent the wedge mechanism from interfering with each other by a five-degree of freedom bearing and forming a one- stage six-degree of freedom accurate positioning table for position alignment of a wafer. CONSTITUTION:A wedge 71 performs linear motion in a direction V1 through a ball thread 74 by rotating a servomotor 76 thereafter deceleration operation in a direction hi through a wedge mechanism, and the first-sixth wedge mechanisms are determined in their height h1-h6. Next, when the wedge heights h1-h6 are determined, because a table 52 is supported to the first-six wedge mechanisms 70-120 through five-degree of freedom bearings 53-58, positions x-z and attitudes alpha-gamma are uniformly determined. When the table 52 changes in six degrees of freedom by a fine position x- z, alpha- gamma, bearing ball center points P1-P6 also change in six degrees of freedom. However, the wedge mechanism provides only one degree of freedom, accordingly providing five degrees of freedom in the bearings 53-58, the wedge mechanism operates following up a change of position of the table. Since accurate positioning of six degrees of freedom can be performed by a table of one-stage constitution, compact constitution is obtained. |
