Abstract: The stator for an electromagnetic pump is designed to improve output efficiency of the pump by decreasing leakage flux. An air-core electromagnetic coil (50a, 50b) is fitted around periphery of a cylinder, and axial end faces of an electromagnetic coil (50a, 50b) are provided with yokes (26a, 26b, 26c) made of a magnetic material.

Abstract: The present invention provides a check valve for a displacement-type pump, in which fluid pressure loss is reduced and which increases pump efficiency. The check valves are arranged in direction opposite to each other on the fluid discharge side and the fluid suction side of a pump chamber 22b, valve bodies 40 are opened and closed only by fluid pressure flowing into or flowing out form the pump chamber 22b, each of the valve bodies 40 has one axis in parallel with a flow path of the fluid, and a planar outer profile of the valve body is formed into a circular shape with the axis as the center.

Abstract: There is provided a method of driving an electromagnetic pump where noise and vibration that accompany abrupt fluctuations in pressure inside a pump chamber are reduced. A pulse voltage is applied alternately on a positive side and a negative side to drive the electromagnetic coil such that a change in voltage that occurs when the polarity of the pulse voltage is inverted has a continuous slope at least between the positive side and the negative side.

Abstract: The stator for an electromagnetic pump is designed to improve output efficiency of the pump by decreasing leakage flux. An air-core electromagnetic coil (50a, 50b) is fitted around periphery of a cylinder, and axial end faces of an electromagnetic coil (50a, 50b) are provided with yokes (26a, 26b, 26c) made of a magnetic material.

Abstract: The present invention provides an electromagnetic pump capable of highly precisely detecting operating positions of a moving member without enlarging the pump. An air-core detecting coil (53) for detecting reciprocating motion of the moving member (10) is fitted around a cylinder so as to be coaxial with electromagnetic coils (50a, 50b).

Abstract: The present invention relates to a voice coil motor with an encoder. In a voice coil motor whose rotor rotates in a prescribed angular width to a base, a rotary disc for encoding is attached to the fringe section of the rotor, and an encoder is provided on the base corresponding to the track of the rotary disc. Attaching the rotary disc to the fringe section of the rotor, the length of the track can be long, so that number of slits perforated on the rotary disc can be increased. Therefore, resolution of the angular position of the rotor can be high.