Abstract: A beam scanning galvanometer is disclosed which oscillates a mirror in a non-resonant mode. The moving parts of the galvanometer are made with as small a moment of inertia as possible because the mirror is oscillated in a non-resonant mode. The galvanometer uses two sets of crossed leaf-springs to support the mirror instead of bearings which are usually used in non-resonant galvanometers. Each of the sets of leaf-springs is formed of a single strip of cold rolled stainless steel. The springs are embedded in uniquely shaped cavities in a permanent magnet that supports the mirror at a distance very close to an axis of rotation of the mirror. The mirror is specially shaped with beveled edges so that its moment of inertia is low and so that it can oscillate in very close proximity to a driving current coil which surrounds the mirror supporting magnet. A magnetic position sensor is used to detect an angular position of the mirror during operation of the galvanometer.

Abstract: An improved method of, and electrical circuit for driving with precision and accuracy an electro-mechanical device such as a galvanometer is disclosed. The method precisely controls high speed linear scanning of the device in a forward scan segment of each cycle of operation, and further provides very fast re-set of the device without position overshoot during a re-trace segment of a cycle. The electrical circuit includes memory means for generating an electrical command waveform for controlling the device during each cycle of operation, and drive servo means for applying electrical power to the device. The servoing action of this circuit substantially eliminates any difference between an actual position of the device and the position directed by the command waveform during each forward scan segment of a cycle of operation, with the result that each forward scan segment is highly accurate and repeatable.

Abstract: A beam scanning galvanometer is disclosed which oscillates a mirror in a non-resonant mode. The moving parts of the galvanometer are made with as small a moment of inertia as possible because the mirror is oscillated in a non-resonant mode. The galvanometer uses two sets of crossed leaf-springs to support the mirror instead of bearings which are usually used in non-resonant galvanometers. Each of the sets of leaf-springs is formed of a single strip of cold rolled stainless steel. The springs are embedded in uniquely shaped cavities in a permanent magnet that supports the mirror at a distance very close to an axis of rotation of the mirror. The mirror is specially shaped with beveled edges so that its moment of inertia is low and so that it can oscillate in very close proximity to a driving current coil which surrounds the mirror supporting magnet. A magnetic position sensor is used to detect an angular position of the mirror during operation of the galvanometer.

Abstract: A focus actuator for controlling the focal position of an objective lens used in an optical recording system to maintain a write/read laser beam in focus on a moving optical recording element. In a preferred embodiment, such actuator comprises a pair of juxtaposed coils which concentrically surround a ferromagnetic cylindrical member of low coercivity (e.g. soft iron). The cylindrical member, in turn, is concentrically arranged with respect to the objective lens and is rigidly coupled thereto. When current is applied to one coil or the other, the cylindrical member (and its coupled lens) move along the optical axis of the lens, in one direction or the other, depending on which of the coils is receiving current. Preferably, the cylindrical member is supported for movenent within the coils by a pair of flexure blades. A particularly important advantage over similar devices of the prior art is that the focus actuator of the invention requires no permanent magnet.

Abstract: A circuit for driving a focus actuator of the "double-solenoid" (i.e. twin-coil) variety comprises circuit means for selectively supplying current to one or the other of the actuator's coils in such a manner as to eliminate any dead-band discontinuity in the actuator response while current-switching between the coils. Such circuitry comprises a current source and/or amplifier for selectively providing current to the actuator coils, means for detecting the difference in current flowing in the coils, an a differential amplifier, connected in a feedback loop, for comparing the output of the detecting means with a signal indicating the focal position of a focusing lens. The output of the differential amplifier is used to control the output of the current source, controlling which of the two actuator coils receives current and how much.

Abstract: The optical element assembly in a read head device is supported by a single four-member flexure structure that prevents the assembly from tilting while providing for tracking movement about an axis spaced from the optical element and for focusing movement along the direction of that axis. Preferably, the flexure structure is symmetrical and comprised of identical flexure members to optmize resonance characteristics and the center of mass of the optical element assembly is coincident with the pivot axis to isolate that element from inertial forces resulting from positioning movement of the read head device.

Abstract: A motor assembly incorporated in an optical read head to effect tracking or focusing movement of an optical element comprises a generally horseshoe-shaped field assembly having two slotted pole pieces magnetized with opposite polarity of a permanent magnet to provide two pairs of field poles confronting corresponding poles of a moveable armature. A single coil is wound through the slots of the pole pieces around the inner field poles. The direction and intensity of the current flowing in the field coil determines the degree to which the permanent magnetism is reinforced in one pole of each pole piece and counteracted in the other pole of each pole piece, thereby causing corresponding movement of the armature.

Abstract: A laser printer is disclosed which uses a rotating polygon and a cylindrical mirror disposed between the polygon and an image zone. The cylindrical mirror corrects for pyramidal errors in an output image formed on a moving photosensitive member disposed at the image zone by making the operative polygon facet and the image zone optically conjugate in the page scan direction. To change the length of the image in the line scan direction at the image zone, the distance between the polygon and image zone is varied. This is accomplished by moving the cylindrical mirror or by positioning a different cylindrical mirror at a new optical path position. The velocity of the photosensitive member is adjusted to change the length of the output image in the page scan direction. The tilt angle of the cylindrical mirror moved to the new optical path position is changed or the cylindrical mirror is removed from the path and a different cylindrical mirror is inserted at a new optical path position.

Abstract: An optical disk assembly includes a flexible disk-shaped support carrying a record layer. The support has an information storage region. An annular retaining ring engages the annular peripheral region of the support. The support, and preferably a cover sheet, are captured between the outer annular reference ring member and an inner annular reference ring member which has been conically deformed to spring toward the outer ring member.

Abstract: A cartridge for handling an extended length of strip material, such as motion picture film, includes cooperating drive means for advancing such material through apparatus such as a motion picture camera. The cartridge defines a closed web loop operable effectively to slave the operation of a strip-driving member of the cartridge to the functioning of a strip-feeding member of the apparatus, and further includes a specially-mounted integral drive motor for responsively rotating a pair of storage spools on which the strip may be wound.