Patent ID: 7588432

Claim:
A pump, comprising: a case having a hollow inside defined by an inner wall surface thereof and including a first through hole through which fluid is sucked in the hollow and a second through hole through which the fluid is ejected from the hollow; a rotor that is rotatable in the hollow and having a rotary shaft and a through groove formed on the rotor in a direction across the rotary shaft; and a partition supported in the through groove slidably in the direction across the rotary shaft, the partition being rotatable with the rotor with at least both ends of the partition, with respect to the direction across the rotary shaft, in constant contact with the inner wall surface defining the hollow upon rotation of the rotor, wherein: the hollow is partitioned into a plurality of chambers each enclosed by the case, the rotor, and the partition member; the rotor and the case are structured such that at least one of the rotor and the case selectively moves between a first position where the rotor is in contact with the inner wall surface defining the hollow during a purging operation and a second position where the rotor and the inner wall surface are separate from each other during a printing operation; during the purging operation when the rotor rotates and makes contact with the inner wall surface, the first through hole and the second through hole are present in different chambers; and during the printing operation, the rotor stops at a rotational position where the first through hole and the second through hole are in fluid communication with each other.