| 摘要 |
PURPOSE:To reduce the size of a device through compensation for gravity without a counterweight and a reduce the load of a table driving motor, by a method wherein a force exerted on a table coupled directly to a cylinder is controlled through the change of a differential pressure between the upper and the lower surface of the piston of a cylinder mechanism. CONSTITUTION:A moving table 1 is moved along a base bed 10 through the medium of a guide 3 with the aid of a drive motor 2. A cylinder mechanism 4 having a piston 5 is situated to the moving table 1. Compensation for gravity is effected by means of a differential pressure equivalent to the weight of the moving table 1, and a pressure control device 6 controls a differential pressure exerted on the piston 5. With the table 1 raised, a piston 5 of the cylinder 4 is also pushed up, a differential pressure exerted on the piston 5 is increased, and a force exerted by the cylinder mechanism 4 is increased over the gravity of the table 1. Therefore control is effected so that a differential pressure is decreased, and when the table 1 is lowered, control is made so that the differential pressure is increased to compensate for gravity. |
