Abstract: A linear actuator for controlling access to a track element belonging to a plurality of adjacent track elements arranged in a reference surface of an optical disk rotatable about a spindle. The linear actuator includes an objective lens for projecting a light spot for interaction with a selected one of the track elements. A first moving mechanism is provided for supporting the objective lens for movement along a first direction substantially perpendicular to the reference surface for controlling the focusing of the light spot. A second moving mechanism in the linear actuator supports the objective lens for movement along a second direction substantially parallel to the reference surface and generally transverse to the track elements for controlling the access thereto. The second moving mechanism includes a pair of spaced apart, parallel rods which extend generally transverse to the track elements. The rods have a round cross-section and are made of a ferromagnetic material.

Abstract: Means for reducing the effects of vertical perturbations of a phonograph disc surface resulting from disc and/or playback system mechanical imperfections. Such imperfections are compensated by closed loop and/or open loop means wherein the deviations of the record path are detected and employed to minimize the effects of the mechanical imperfections.

Abstract: A record player with a scanner for record disks is provided, where the vertical recording track angle .alpha. is to be placed within predetermined limits, but where, in general, the value of .alpha. is not known. The scanner comprises a transducer which generates useful signals and which is provided with elastically supported and therefore movable scanning elements. According to the invention, means are provided for determining the difference .alpha.-.beta. of the recording track angle .alpha. and of the tracking track angle .beta.. The angle difference determining means generate a voltage which depends on the longitudinal motion of the scanning elements moved during the useful modulation and which is displayed and/or employed for correcting the track angle. A record player with a tracking sound pick-up arm for the tracking of record disks is provided. Means for tracking a groove on a side of a record disk are disposed elastically supported and thus movable on the sound pick-up arm.

Abstract: A system for playing back information recorded on a recording disc includes a first servo control system responsive to a tracking error signal, which adjusts the position of an information reading point of a pickup relative to the recording track on the recording disc, and a second servo control system responsive to a synchronizing signal contained in the playback information signal, which adjusts the speed of rotation of the recording disc.

Abstract: A tracking apparatus applicable to a rotatable magnetic recording medium which is provided with a plurality of discrete tracks thereon includes a head for sensing signals out of the tracks, a head transport mechanism for moving the head to a position on a desired one of the tracks, an envelope detector for detecting an envelope of signals sensed by the head, and a controller for performing tracking by controlling the head transport mechanism responsive to the detected envelope. A sync signal generator circuit is provided for producing a reference signal which is synchronous to the rotation of the recording medium. The controller controls the head transport mechanism and causes the envelope detector to detect an envelope, responsive to the reference signal.

Abstract: A system for recovering information from a videodisc and performing special functions which enhance the operational character of the system. To increase the reliability of landing at or near a target track, provisions are made to search for a track adjacent a target track whose track identifier has been obliterated. Further, a method and means for stepping forward or reverse one field at a time is disclosed. Another aspect of the invention concerns a capability to respond to a random command instruction resulting in subsequent functioning of the system in a random manner. Yet a further aspect of the invention is related to controlled jumping of one or more tracks during vertical blanking time to produce unique forward or backward motions; multiples of playing speed, both forward and reverse, and visual special effects can be realized using the multiple track jumping feature. Finally, a method and means are described which permit synchronous transmission of video from a videodisc to an external using device.

Abstract: A record disc reproducing apparatus determines the magnitude and polarity of the difference between a preselected data address and a current data address and moves a pickup assembly in a direction to reduce that difference until it drops below a prescribed address tolerance. The amount of movement can either be a given distance or some fraction either of the difference between the current and prescribed data addresses, or of the breadth of a program portion.

Abstract: An optical disk apparatus has an optical head for photoelectrically detecting track data and a track jump data component corresponding to an accidental track jump on an optical disk. A circuit is provided wherein the track jump data component is detected from the data detected by the optical head so as to determine the number of jumped tracks and a jump direction therefrom. A tracking section performs tracking control of the optical head in accordance with a signal corresponding to jump direction and the number of the jumped tracks and returns a laser beam to the track at which the laser beam was directed before the track jump.

Abstract: A jitter compensation system is applied to a rotary recording medium reproducing apparatus having a reproducing transducer including a reproducing element for reproducing recorded signals from a rotary recording medium, where the rotary recording medium is recorded with an information signal track and also recorded with reference signals for tracking control having predetermined frequencies. The jitter compensation system comprises a separating circuit for separating the reference signals from a signal reproduced by the reproducing transducer, a detecting circuit for frequency-detecting frequencies of the separated reference signals, to produce a jitter compensation signal, and a displacing circuit responsive to the output jitter compensation signal of the detecting circuit, for displacing the reproducing element of the reproducing transducer along a relative scanning direction with respect to the rotary recording medium.

Abstract: A reproducing rate control apparatus for an information recording disc in which pieces of information and absolute times for respective information pieces (representative of the reproduction time measured from the innermost circumference of the information recording disc) are recorded on the disc at a constant linear velocity, a revolution number of the disc at a command position is predicted, rotation of a disc drive motor is controlled so that the disc rotates at a predicted revolution number, and an information reader adapted to read the information recorded on the disc is moved to the command position when the revolution number controlling is effected or after the revolution number controlling has been completed.

Abstract: A pick-up positioning apparatus for a recording disc playback apparatus such as a video disc player, comprising a control circuit, a memory circuit, a scanning mechanism for moving the pick-up of the playback apparatus along a radius of a recording disc mounted on the playback apparatus, and pick-up sensing circuit for producing signals to indicate the current pick-up position along that radial direction. When a disc is first set on the playback apparatus, the scanning mechanism moves the pick-up along the radial direction to thereby successively read out a number of addresses recorded on the disc, which are stored in the memory circuit together with corresponding position data. Subsequently, to search for a specified address position on the disc, the address stored in the memory circuit which is closest to the specified address is read out and the corresponding stored position data is used in moving the pick-up close to the specified address position.

Abstract: A head drive control apparatus has a head and a scale reader. When the head is moved by a head drive mechanism, the scale reader detects the marks on a scale and converts them into a scale signal. In a speed control mode, the scale signal is compared with a target signal by an access signal generator, which produces an access signal representing the difference between the compared signals. The head is moved in accordance with the access signal until the scale signal becomes identical with the target signal. When these signals become equal, the speed control mode is switched to a position control mode. In the position control mode, a scale signal generator, a pulse generator, an up/down counter, a D/A converter, an adder and an interpolator convert the scale signal into an analog signal which represents the position of the head. The analog signal is compared with a position designating signal by a differential amplifier. The head is moved in accordance with the output signal of this amplifier.

Abstract: An optical head for reading a signal recorded along spiral or concentric tracks on an optical disc including a semiconductor laser for emitting a linearly polarized light beam, a polarization prism for transmitting the light beam, an objective lens for projecting the light beam upon the optical disc and for collecting a light beam reflected by the optical disc, a critical angle prism for totally reflecting the light beam reflected by the polarization prism and a light detector for receiving the light beam totally reflected by an optical surface of the critical angle prism. The polarization prism and critical angle prism are integrally coupled with each other to form an assembly of prisms which is rotated to adjust an incident angle of the light beam impinging upon the optical surface of critical angle prism substantially at a critical angle of total reflection.

Abstract: The lateral position of a magnetic head is controlled in response to tracking information derived from an adjacent guide track formed by a series of minute pits on a grooveless recording medium having ferromagnetic and dielectric properties. Microwave energy is applied to an electrode mounted for movement with the magnetic head to sense the variations in capacitance resulting from the geometrical variations of the minute pits. The recording medium comprises an underlying layer of ferromagnetic material in which the minute pits are formed in spiral or concentric pattern and an overlying layer of a dielectric material which conforms to the pit contours of the underlying layer.

Abstract: A video disc reproducing apparatus is provided with a pickup by which the information recorded on a video disc is detected as a variation in electrostatic capacity. The signal output from the pickup is processed so as to generate a control signal proportional to the logarithm of the pickup signal. This control signal is then utilized to control the pressure of the pickup on the video disc. Element functions of the apparatus may be combined such that an automatic gain control device may also serve to generate the logarithmic control signal.

Abstract: A tracking servo circuit corrects for closed loop gain variations due to wear of the disc, the width of the electrode of the reproducing stylus, etc. The disc contains an information track bounded by servo tracks used to derive a tracking error signal. This tracking error signal is supplied to an AGC circuit after being filtered and detected. The gain of the AGC circuit decreases as the voltage level of the tracking error signal increases. The tracking error is also supplied to an electric-mechanical conversion system after an oscillatory signal of constant frequency and amplitude is added to it. The oscillator signal is used to stabilize the gain of the servo loop. The electric-mechanical conversion system corrects the position of the stylus in response to these signals.

Abstract: A beam access apparatus for an optical disc system. The apparatus includes a lens position detector for generating a lens position signal indicating a position of the objective lens in a radial direction of the disc with respect to the optical head which is movable relative to the disc. The apparatus is operated in a head access mode in which the optical head is moved in the radial direction of the disc and the objective lens is caused to follow the movement of the optical head such that the objective lens is positioned at a predetermined location with respect to the optical head. The apparatus is also operable in a lens access mode wherein the objective lens is moved in the radial direction and the optical head is caused to follow the objective lens such that the objective lens is located at a predetermined position with respect to the optical head.

Abstract: A periodical signal detection circuit in a reproducing apparatus which reproduces an information signal and a periodical signal from a recording medium recorded with the information and periodical signals comprises a separation circuit for separating the periodical signal from the reproduced signal, a reference pulse generating circuit for generating a reference pulse having a same repetition frequency as the periodical signal, a window signal forming circuit for forming window signals respectively having differing widths, with a repetition period identical to that of the reference pulse, a first gate circuit for producing the periodical signal from the periodical signal obtained from the separation circuit and the window signal obtained from the window signal forming circuit, a first counter for generating a switching control signal every time the reference pulse is counted N (N is an integer including zero) times, to produce an output when counting is performed for a predetermined number of times, a window

Abstract: The rotation speed of a disc rotation motor is controlled such that a synchronizing signal derived from an output signal reproduced from a disc coincides with a reference oscillation frequency. The amount of data accumulated in a memory provided for absorbing jitter of the output signal reproduced from the disc is detected. In response to a result of the detection, a control signal in the disc rotation control is corrected such that the amount of data accumulated in the memory becomes substantially constant.

Abstract: An apparatus and method are disclosed for piecemeal recording of data on an optical disc using a spiral track format without the necessity of leaving a guard band between recordings or even providing a leader on the subsequently recorded track. A new recording is added to the end of a previously recorded track by first playing back the previous track. The tracking servo is locked to the data track and the translation stage motion is adjusted to match the spiral rate of the track. As the end of the previous track is approached, the translation stage drive is switched to a constant dc drive, the tracking servo is disabled, the tracking mirror is electronically locked to a nominal position, and the new recording begins. This operation may be repeated for each new data file to be recorded in piecemeal fashion.

Abstract: A video disc record system having a stylus for recovering information effects kicks which induce limited stylus translations across a disc record surface. Control circuitry responsive to a desired stylus translation are coupled to kicker means for inducing the stylus translation. Actual stylus translations are used to calibrate the kicker activation signals to minimize the kick used to induce stylus translations thereby reducing damage to the disc surface incurred during a stylus translation.

Abstract: A magnetic tape has luminance and chroma components recorded in different tracks with the horizontal sync signal recorded between them. On playback, if there is mistracking, the sync signal will be present in either the luminance or the chroma signal. This is detected and used to control the deflection of a bimorph to correct the mistracking.

Abstract: A disc player for reproducing an information signal from a rotating disc having record tracks defined by successive turns of a spiral signal path in which the information signal is recorded, which is adapted to perform a small scale track jump operation for rapidly moving the reading position determined by a pick-up device in the direction transverse to the spiral signal path on the disc to a relatively short distance repeatedly in the fast forwarding or fast reversing mode and is so arranged that the number of times of the small scale track jump operation performed repeatedly for a certain period in the fast reversing mode is larger than the number of times of the small scale track jump operation performed repeatedly for the same certain period in the fast forwarding mode, whereby the substantial moving distance measured along the spiral signal path in respect of the reading position by the pick-up device moved for the certain period in the fast forwarding mode coincides with or closes to the substantial mov

Abstract: In a video disc mastering system, player control data is conveyed by a block code having framing and field number bits and data for use by a computer external to the player is conveyed by a convolutional code having no framing bits, having error check bits related to a subset of the field number bits conveyed by the player control data and having vertical parity selected to spread data required for predictive and reconstructive error correction over a number of video fields greater than that recorded on one convolution of the disc information track.

Abstract: A magneto-optical head assembly for a reflection type magneto-optical memory apparatus uses a laser beam for recording, retrieving, and erasing data on a recording medium comprised of a vertical, magnetic, and anisotropic thin film. The light beam emitted from the head assembly is guided to a fixed position on said recording medium. Included are a light detection apparatus for receiving a control signal, and a separate light detection apparatus for receiving a data signal. A beam splitter, to which has been applied a multicoated thin film dielectric body capable of increasing the Kerr rotation angle of the laser beam reflected from the recording medium, is positioned in the optical system through which the laser beam passes.

Abstract: Video disc track numbers are conveyed during each video line by means of a tri-phase modulation of a data carrier recorded along with the picture and sound carriers on a video disc. Upon playback, the data sequence is processed to identify tracking errors occurring within each video field to thereby enable immediate correction of disc tracking errors on a line-by-line basis thus minimizing picture and sound interruptions caused by intra-field tracking errors.

Abstract: An information storage disk is provided with a dense array of detectable marks. This pattern does not interfere with or use any otherwise available recording capacity of the storage medium. The marks are detected by a sensor different from any transducer used to read or write information into the storage medium. Information storage tracks are defined by the pattern rather than by any recorded information in the storage medium. In the preferred embodiment the storage medium is a conventional magnetic recording layer and the pattern of detectable marks are optically reflective or non-reflective spots overlying or underlying the magnetic storage medium.The sensor is mounted over the pattern for common movement with the storage medium transducer. As the storage disk spins, the sensor produces a signal which varies as individual marks pass by. From the sensor signal is derived a signal directly related to the rate at which marks are passing under the sensor.

Abstract: A magnetic recording disk substrate is provided with a capacitive servo pattern by implanting dopant material in the substrate to modify the substrate conductivity in a desired servo pattern.

Abstract: A bobbin which supports at least optical lens includes a portion on which two or three coils are disposed. Each of the coils disposed on the bobbin portion is wound thereon at a given finite angle with respect to the center axis of the bobbin, at least one such angle being non-perpendicular to the central axis, and the coils form together a composite coil assembly. A magnetic circuit includes a gap and defines a magnetic flux in the region of the gap which passes through the composite coil assembly in a direction substantially perpendicular to the center axis of the bobbin. Support means support the bobbin within the gap of the magnetic circuit so it is freely movable. By controlling the current passed through each coil, the location of the bobbin is adjusted, thus adjusting the position of the optical lens with respect to a disc.

Abstract: Video disc track numbers are conveyed during each video line by means of data subcarriers present in the recorded stereo audio channels. Upon playback, the data sequence is processed to identify tracking errors occurring within each video field to thereby enable immediate correction of disc tracking errors on a line-by-line basis thus minimizing picture and sound interruption caused by intra-field tracking errors.

Abstract: An address signal reproducing system is provided in a rotary recording medium reproducing apparatus which reproduces signals from a rotary recording medium by a reproducing element, where the rotary recording medium is recorded with an address signal in units of predetermined sections for a plurality of sections for each track turn of the rotary recording medium.

Abstract: A video disc player comprising an arm servo system having means for driving a pickup arm with a cartridge mounted thereon to move in parallel with the surface of a disc, and a kicker drive system for driving a stylus tip mounted on the cartridge to be kicked on the basis of the information from a picture signal processing circuit of the pickup upon special reproduction, wherein when the width of a kicker drive pulse in the kicker drive system exceeds a predetermined value, the drive means of the arm servo system is driven to change the balance position of the stylus tip on the surface of the disc.

Abstract: A video disc tracking information encoding system includes a primary encoder for tracking information on a field-by-field basis and a secondary encoder for conveying a subset of the tracking information every N lines within a field. A video disc player for discs recorded with doubly conveyed complete and partial tracking information includes means for recovering the partial tracking information every N lines, comparing it with the complete tracking information recovered during the start of each field and effecting tracking error correction if the partial tracking information differs from a predetermined subset of the complete tracking information thereby facilitating intra-field track error correction so as to enable rapid correction of tracking errors.

Abstract: Video disc track numbers are conveyed during each video line by means of a quadrature phase shift keyed data carrier recorded along with the picture and sound carriers on a video disc. Upon playback, the data sequence is processed to identify tracking errors occurring within each video field to thereby enable immediate correction of disc tracking errors on a line-by-line basis thus minimizing picture and sound interruption caused by intra-field tracking errors.

Abstract: An information reading and reproducing apparatus in which a recording disc having an information-carrying face formed with recorded tracks is to be driven for rotation and which includes drive means operative to drive a signal pick-up means for movement radially of the disc at a velocity controlled by a velocity control device and to produce signals indicative of the locations of the pick-up spot relative to the tracks on the disc in a radial direction of the disc, the velocity control device comprising velocity detecting means operative to extract from said signals information indicative of the velocity of movement of the signal pick-up means with respect to the disc.

Abstract: A control signal recording and reproducing system for exactly tracking a record track in a helical scan type VTR or the like is disclosed.Intermittent pilot signals are recorded with the frequency spectra thereof being interleaved between adjacent tracks. In a reproducing operation, the main track pilot signals and the adjacent track pilot signals are separated by a comb type filter, and using a time position of the main pilot signals as a reference, the adjacent track pilot signals are separated in time to the front adjacent track pilot signal and the rear adjacent track pilot signal to detect the direction of a tracking error.

Abstract: A telephone switching network is disclosed having an announcement system coupled to a toll switching center.A plurality of short phrases are recorded in corresponding sectors of a disc store and announcements are assembled in real time by concatenating the appropriate phrases. Initial requests for announcements are sorted so that the reading heads seek across the disc in a straight line in a first direction to play back the recorded phrases. Any additional requests for playback received while the initial requests are being played back, are sorted in the opposite order for playback while the heads are driven in a second direction to their original position. All further requests are combined with any unfinished work for playback as the heads once again move in the first direction.The method of playing back while traversing the disc in both directions shortens the waiting interval for the listeners.

Abstract: In an apparatus for reproducing, from a record disc, audio information recorded in the form of a pulse code modulation (PCM) in a run length limited code, a reproduced signal derived from the rotated record disc, for example, by a pick-up in the form of photo detector in the case of optical recording and reproducing, is compared with a first reference level or signal to provide an output signal corresponding to the reproduced signal and having portions of opposite polarities, the interval between transitions from one to the other of the opposite polarity portions of the output signal is detected for providing a corresponding detecting signal, a velocity servo circuit compares the detecting signal with a second reference signal which corresponds, for example, to a maximum transition interval when the record disc is driven at a predetermined linear velocity at the location scanned by the pick-up, so as to produce a corresponding velocity control signal for maintaining the record medium at such predetermined lin

Abstract: A tracking information detecting device for recording a video signal together with a pilot signal on one track of a magnetic disc and detecting tracking information at the time of reproduction. In this device, the pilot signal has a predetermined frequency at least ten times that of the horizontal synchronizing signal. The pilot signal is recorded in such a manner that its phase is displaced with respect to the horizontal synchronizing signal at every track. The horizontal synchronizing signal is displaced at every track at the time of reproduction of the recorded video signal, and the phase difference between the horizontal synchronizing signal and the pilot signal is detected as the tracking information.

Abstract: A pickup device for compensating for jitter by driving a scanning needle in the direction of a record track on a disc comprises a resiliently held support which supports a cantilever having the scanning needle mounted thereon and a permanent magnet mounted at an end thereof, and a driver to which a drive current is supplied to generate a magnetic field to be acted on the permanent magnet. A drive force created by the action of the magnetic field is in parallel to a surface of the disc so that the scanning needle is driven in parallel to the surface of the disc.

Abstract: A system for recovering information from a videodisc and performing special functions which enhance the operational character of the system. To increase the reliability of landing at or near a target track, provisions are made to search for a track adjacent a target track whose track identifier has been obliterated. Further, a method and means for stepping forward or reverse one field at a time is disclosed. Another aspect of the invention concerns a capability to respond to a random command instruction resulting in subsequent functioning of the system in a random manner. Yet a further aspect of the invention is related to controlled jumping of one or more tracks during vertical blanking time to produce unique forward or backward motions; multiples of playing speed, both forward and reverse, and visual special effects can be realized using the multiple track jumping feature. Finally, a method and means are described which permit synchronous transmission of video from a videodisc to an external using device.

Abstract: A data recording apparatus is provided which has a recording/reproduction head for recording data on or reproducing the data from a recording medium, a moving mechanism for moving the recording/reproducing head on the recording medium, an error detector for detecting an error in accordance with a signal from the recording/reproduction head in the recording mode, and a control section for detecting that an access to a recording start track cannot be made by the recording/reproduction head for recording data, for determining a track number in the vicinity of the recording start track by the recording/reproduction head in accordance with a detection result, and for controlling a moving mechanism to move the recording/reproduction head to a target track ahead of a predetermined number of tracks which correspond to a distance between the target track and the recording start track without performing recording of data on the predetermined number of tracks in accordance with a detection result from a tracking error d

Abstract: The focus actuator, turntable and translation stage in an optical disc record/playback system may effect relatively large reaction forces on the components of the system. These reaction forces can cause vibrations which interfere with or distort information recording or retrieving operations which occur at the same time that high speed access is being effected. A momentum compensating mass is coupled to the focus actuator, turntable and other moving elements to reduce or eliminate the reaction forces which can affect system operation.

Abstract: A jitter compensation system in a rotary recording medium reproducing apparatus having a reproducing transducer including a reproducing element for reproducing recorded signals from a rotary medium, where the rotary recording medium is recorded with an information signal and also recorded with reference signals for tracking control with predetermined periods, comprises a separation circuit for separating the reference signals from a signal reproduced by the reproducing transducer, a detection circuit for detecting the separated reference signals and obtaining a signal having a predetermined period and predetermined frequency, a standard signal supplying circuit for supplying a standard signal having a frequency equal to the predetermined frequency, a phase comparator for comparing phases of the predetermined frequency signal thus obtained and the standard signal supplied thereto, to produce a phase comparison error signal, and a displacing circuit for displacing the reproducing element of the reproducing tran

Abstract: An actuator for use in a pickup device for a video disk plunger having a cylindrical yoke made of a soft magnetic material, a pair of tubular solenoid coils disposed in said yoke such that the same polarity appears at adjacent portions thereof, and a movable element disposed axially movably inside of the tubular solenoid coils, the movable element having an axially magnetized permanent magnet and pole shoes attached to both ends of the permanent magnet. Dampers made of a resilient material such as a butyl rubber are secured to both ends of the yoke. The dampers support projections projected from both ends of the movable element such that the projections project axially outwardly of the dampers. A permanent magnet for magnetically attracting a stylus is secured to the outer end of one of the projections.

Abstract: Digital audio data to be recorded in a pseudo-video format on a disc record is applied to an error check encoder that encodes each line of data with an error check code. The encoder is preset to an initial state corresponding to a recording track number prior to encoding each data line. The track number is changed periodically during recording whereby track information is conveyed by the form of the error check code without requiring additional bits of information in the data lines. Upon playback of the disc, the encoded data is applied to an error check decoder that is preset to an initial state corresponding to an expected track number. Upon decoding, errors in the recovered data are corrected and the recorded track number is recovered. The expected and recovered track numbers are compared to provide a track error correction signal whereby tracking errors may be corrected on a line-by-line basis within each pseudo-video field without need for additional bits in the recorded data.

Abstract: A reproducing element feeding and driving circuit is provided in a rotary recording medium reproducing apparatus consisting of a signal pickup device having a reproducing element for reproducing recorded signals from a rotary recording medium, a feeding mechanism for feeding the signal pickup device, and a tracking error signal obtaining circuit for obtaining a tracking error signal so as to perform tracking control with respect to the reproducing element.

Abstract: A skip/arm servo system for a video disc player comprises a device adapted to skip a signal sensing element, such as a stylus for detection of information recorded on a disc, in a direction crossing a recording track, a stylus position detector adapted to detect the relative position of the stylus to a cartridge movably mounting the stylus, a comparator comparing the detected relative position with a reference relative position to produce an error output, a cartridge driver responsive to the error output to move the cartridge so as to maintain the stylus in the reference relative position. A setting device is adapted to variably set the reference relative position in accordance with a reproduction mode selected by the operator, whereby a special mode reproduction can readily be accomplished or the stylus can be readily released from a locked groove in the disc.

Abstract: A velocity correction apparatus for a disc record player includes a permanent magnet attached to a cartridge mounted pickup arm and an electromagnetic coil secured in a cartridge supporting carriage. The coil is fixed to a supporting member which conformally engages structural features of the cartridge to guarantee proper alignment of coil and magnet. The coil support is mounted to permit limited rotation thereof to facilitate installation of the cartridge in the carriage and is mechanically biased to maintain coil-cartridge engagement and to maintain the cartridge in its normally operative position in the carriage.

Abstract: A playback head (155) is moved across a recording medium (151) orthogonally to a data track by playback head-moving means (157, 159, and 161), said data track being independently moved so that previously-recorded data is sequentially recovered. An electrical signal, which bears a direct relationship to the velocity of the head-moving means, is produced by a position sensor affixed to the head-moving means and a differentiator (169). Said signal is used to close a velocity loop, through a summing junction (171) and a power amplifier (173), around the head-moving means. The playback head is moved in addition, at a relatively high frequency, by dithering means which causes an amount of head motion that is small with respect to the width of the data track. The dither motion causes an amplitude modulation of the signal being recovered from the data track by the playback head.