Feed apparatus

A feed apparatus comprising:

• two guide rails arranged in parallel along a predetermined feeding direction;
• at least four sliders arranged at least two by two on the two guide rails and engaged with the guide rails to be movable along the feeding direction;
• a movable carriage mounted on the sliders and configured to be moved in the feeding direction;
• and
• a drive mechanism configured to move the movable carriage in the feeding direction, wherein:
• the feed apparatus includes:
• a scale arranged along the feeding direction on at least one of the guide rails;
• read heads respectively arranged on at least two sliders selected from the at least four sliders and engaged with the guide rail having the scale arranged thereon, the read heads being configured to detect a position in the feeding direction and a position in a direction orthogonal to the feeding direction by reading information given to the scale;
• and
• a motion error calculator configured to calculate a motion error of the movable carriage based on position information in two directions detected by the read heads, wherein:
• the scale is arranged on each of the two guide rails and the read heads are respectively arranged on the four sliders;
• and
• the motion error calculator is configured to calculate a motion error of the movable carriage based on position information in two directions detected by the four read heads.