Abstract: A device for removing extraneous signal components from signals containing a series of pulse components appearing on a signal transmission line at regular intervals and having a predetermined repetition frequency, wherein the signal transmission line is periodically connected to a predetermined potential for periods of time when the signals on the transmission line contain extraneous signal components so that only the regular pulse components contained in the original signals are delivered from the transmission line.

Abstract: An optical player signal reading device in which a supporting member having inner and outer cylinders pivotally supports an optical pickup. One of the inner and outer cylinders is made of an elastic material or, alternatively, an elastic piece is disposed between the inner and outer cylinder. The pickup is pivoted by a pair of tracking-direction drive sections disposed above and below the supporting member with the elastic component of the supporting member acting as a fulcrum. A focus-direction drive section moves the pickup in the focusing direction.

Abstract: In a tracking servo system of a recording-disc information reading and reproducing apparatus such as a video disc player, a tracking error signal indicative of an amount of deviation of an information pickup medium such as a focused spot of a scanning beam of light from a target track of the recording disc being scanned is amplified with a gain which is varied as the pickup medium is displaced radially of the recording disc between an outer peripheral area and a central area of the disc.

Abstract: A video disc player featuring a signal correcting device capable of compensating for the attenuation of the signal level of high frequency components of the reproducing signal read out from an optically electromagnetically or electrostatically scanned video disc, a device for detecting the presence or absence of recorded information on a video disc being played back, or a tracking servo system which can be locked in reliably and in a stable condition when the servo loop is to be closed from an open condition.

Abstract: A video switch circuit for turning off and on picture portions of a composite video signal while leaving a synchronizing signal contained within the composite video signal so that a video device using the output video signal does not have to resynchronize when it is desired to switch on the overall composite video signal. A synthetic synchronizing signal is produced by operating an electronic switch between two fixed voltage levels corresponding to the pedestal level and synchronization peak level of the composite video signal in response to synchronization pulses separated therefrom. A second switch selects between the synthetic synchronizing signal and fixed voltage levels. A third output switch selects between the output of a clamp circuit which clamps one of the pedestal levels of a composite video signal and the synchronization peak level of the synchronizing signal contained within the composite video signal to a predetermined clamp potential and the output of the second switch.

Abstract: A system for compensating and correcting errors in the time base of video signals read from a video disc in which the errors are corrected first coarsely in response to phase differences between horizontal sync signals of the video signals following which a fine correction is made in response to measured phase differences of burst signals of the video signal. A first phase detector produces an output signal in response to phase differences between the burst signals and an output of a reference frequency generator operating at the burst frequency. A second phase detector produces an output signal in response to phase differences between the horizontal signals and the reference signal divided down by a predetermined factor. The output signals of the two phase detectors are summed and then applied to the control input of a variable delay line which adjusts the delay time and hence phase errors in the video signal accordingly.

Abstract: A focus servo apparatus for an optical information reading system is disclosed, which includes an optical system for a light from an information carrying surface of a recording medium composed of a condenser lens, a cylindrical lens and a light receiving element. A subsystem is employed for maintaining light illuminating focussed on the information carrying surface in response to an output of the light receiving element. The distance between the cylindrical lens and the light receiving element is larger than the focus distance of the lenticular lens.

Abstract: A focus lens protecting and in-focus detecting device has light receiving circuit and a comparator for comparing the output of said light receiving elements with a reference potential. A switch network is controlled by the output of the comparator to supply signals to a focus control amplifier from the light receiving circuit.

Abstract: A focussing lens servo driving device for an optical information reading device in which the lens is first driven towards the focussed position with a controlling servo circuit operated in an open loop mode. Once the lens has passed a predetermined position an opposition force is produced in dependance on the lens position. The opposition force is gradually reduced and the servo loop is closed when the lens has been turned back to the predetermined position so that stable operation is provided.

Abstract: A servo unit in an optical information reading device having a lens for focussing an irradiation light beam on the record surface of a disk. A movable mirror positions the focal point of the irradiation light beam formed on the track of the disk. A cylindrical lens is arranged so that the central axis of the cylinder forms a 45.degree. angle with the track direction of the disk to allow a light beam from the record surface to pass through the cylindrical lens. A focussing light receiver having four separate light receiving units is arranged on two orthogonal straight lines. The focussing light receiver receives a focus controlling light beam passed through the cylindrical lens at a distance twice as long as the focal distance of the cylindrical lens.

Abstract: A movable mirror device for an optical information recording and reproducing system has a base portion with a bottom section and an up-standing section extending from the bottom section. A permanent magnet having opposite magnetic poles at opposite ends thereof is fixedly mounted on the bottom section of the base portion. A pair of yokes have their ends engaged with opposite ends of the magnet, respectively. A plate member is supported by the up-standing section of the base portion disposed between the other ends of said yokes and a movable portion having a core. A mirror substrate is supported by an end plate formed on one end of the core and a mirror is fixed to the mirror substrate. A supporting portion provided on the other end of said core pivotally supports the core with respect to the up-standing section and a coil portion is wound around the mirror substrate.

Abstract: A tracking servo drawing device in an optical type information reading device utilizes a tracking servo to allow an irradiation light beam to track a record track on an information record surface to read information by using said irradiation light beam illuminating said record surface. A speed detection circuit is used to sense a relative speed of the record track and the irradiation light beam at which the irradiation light beam goes across the video track. When the relative speed is lower than predetermined value, a first detection signal is produced. A signal level detection circuit detects the reproduction signal level of the information. When the level reaches a predetermined value, a second detection signal is produced. When the first and second detection signals are produced simultaneously an instruction signal is generated to close the servo loop of said tracking servo means.

Abstract: A beam splitter employed in an optical disc player comprises a pair of triangular prisms which are combined and adhered together to form an integral rectangular prism. The thus formed beam splitter is positioned on a metal chip whose surface is substantially rectangular having adjacent two sides projecting upward. The adjacent lower surfaces of the beam splitter fit the upward projecting sides of the metal chip and an adhesion material is coated only on the half triangular region defined by the sides and the combining line of the prisms to adhere the beam splitter to the metal chip.