Displacement device, lithographic apparatus and positioning method

A displacement device comprising:

• a first part and a second part that are displaceable relative to each other in a first direction and a second direction substantially perpendicular to the first direction, the first part comprising a carrier that extends substantially parallel to the first and second direction and on which a system of magnets is arranged in accordance with a pattern, wherein the system of magnets includes first magnets having a magnetization direction substantially perpendicular to the carrier and directed towards the second part and second magnets having a magnetization direction substantially perpendicular to the carrier and directed away from the second part, the first and second magnets being arranged in accordance with a pattern of rows and columns substantially perpendicular thereto and enclosing an angle of approximately 45° with one of the first or second direction, such that the first magnets and the second magnets are arranged in each row and in each column alternately,
• wherein the second part includes an electric coil system having a set of coil block units, each coil block unit having current conductors that are arranged in a magnetic field of the system of magnets and are, in use, fed by a multi-phase system,
• wherein the set of coil block units comprises
• a first main coil block unit having current conductors oriented substantially parallel to the second direction,
• a second main coil block unit having current conductors oriented substantially parallel to the first direction,
• wherein the first and second main coil block units define a minimal first range in the first direction in which the first and second main coil block units are located, and wherein the first and second main coil block units further define a minimal second range in the second direction in which the first and second main coil block units are located,
• wherein the set of coil block units further comprises a first secondary coil block unit having current conductors oriented substantially parallel to the second direction, wherein the first secondary coil block unit is located inside the second range and outside the first range, the second range being large enough so that the first secondary coil block unit can be placed in the second range at multiple distinct positions seen in the second direction to position a center of force determined by all coil block units in the second direction.