| 摘要 |
On the +X and −X sides of a projection unit, a plurality of Y heads are arranged in parallel to the X-axis by a predetermined distance half or less than half the effective width of the scale, so that two heads each constantly form a pair and face a pair of Y scales. Similarly, on the +Y and −Y sides of the projection unit, a plurality of X heads are arranged in parallel to the Y-axis by the predetermined distance described above, so that two heads each constantly form a pair and face a pair of X scales. Of the pair of heads consisting of two heads which simultaneously face the scale, measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to malfunction of the head, measurement values of the other head is used. Then, by using the measurement values of the two pairs of Y heads and the pair of X heads, a position of a stage within a two-dimensional plane is measured in a stable manner and with high precision. |
| 主权项 |
1. A movable body apparatus including a movable body which substantially moves along a predetermined plane and is movable to a predetermined position within the predetermined plane, the apparatus comprising:
a scale which is arranged at one of the movable body and an outside of the movable body, with a first direction within a plane parallel to the predetermined plane serving as a longitudinal direction, the scale having a predetermined width in a second direction orthogonal to the first direction within the plane parallel to the predetermined plane, the scale having a length extending in the first direction and having a width extending in the second direction, the length being substantially longer than the width; a measurement device having a plurality of sensors each of which measures positional information of the movable body in a periodic direction of the scale at a plurality of measurement points placed on the scale within the width of the scale so that of the plurality of measurement points, n (wherein, n is an integer of two or more) or more points are positioned within the predetermined width of the scale, and when the movable body is at the predetermined position, n+1 or more of the plurality of measurement points are positioned within the predetermined width of the scale; and a controller which performs position control of the movable body, using, as primary information, a first measurement information including measurement information at a first measurement point out of the n or more measurement points positioned within the predetermined width of the scale or the n+1 or more measurement points positioned within the predetermined width of the scale when the movable body is located at the predetermined position, wherein the controller switches measurement information to use as the primary information in position control of the movable body to a second measurement information including measurement information at a second measurement point different from the first measurement point, when abnormality occurs, due to malfunction of one of the sensors, in the first measurement information at the first measurement point positioned within the predetermined width of the scale. |
