| 摘要 |
A pick-up device for optical recording and playback includes two linear actuators coupled to an optical module and lying in a plane normal to the surface of an optical recording medium. The actuators are obliquely inclined to the optical axis of the optical module. Proportional differential actuation of the linear actuators moves the optical module bi-axially, i.e., normal or parallel to the recording medium surface, permitting control of both focus and tracking of information bits on the surface. The preferred embodiment employs two bi-directional linear actuators, each comprising a pair of back-to-back uni-directional actuators, each of which includes a flexible tubular housing enclosing a stack of thin, perforated disc-shaped electrodes separated by a dielectric fluid. Conductive elastomeric spacer rods support the disks in a parallel, longitudinally, spaced apart arrangement. Applying a voltage to adjacent pairs of disks via the conductive elastomeric rods causes an electrostatic attraction force between adjacent disks to shorten the stack. Contraction of the stack housing causes an elongated actuator rod disposed longitudinally through the housing and attached to a transverse end cap sealing the housing at one end to be extended further from the opposite end cap of the housing, the free end of the rod thus being able to exert a pushing force.
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