Abstract: In an information-bearing disk having, along concentric record tracks, pre-written equally spaced tracking pads which may or may not be aligned radially from one track to another, circuitry serves for improving the response time of a disk drive mechanism during a track-jump operation, i.e. when a read/write transducer head moves radially from one record track to any other track. The circuitry includes a phase-locked loop (PLL), coupled to the transducer head and responsive to a pulsed signal corresponding to the frequency at which the tracking pads sweep past the head, and thereby the actual speed of the disk, for producing an adjustable clock signal which controls the rate at which user data is transferred to or from track segments between adjacent tracking pads.

Abstract: Apparatus for rotating a flexible sheet of material includes a rotatable axle and a generally cylindrical drum mounted on the axle for rotation therewith. A generally cylindrical cam is secured to an end surface of the drum for rotation therewith, the cam defining at least one indentation extending towards the axle. A cam follower is provided positioned to generally follow the cam. A clamp normally biased against the surface of the drum for securing a first edge of the sheet material to the drum is provided. A biasing cam is journaled to the end surface of the drum in the cam indentation, the biasing cam responsive to pressure from the cam follower for biasing the clamp away from the drum surface so as to enable the positioning of an edge of the flexible sheet of material between the clamp and the surface of the drum.

Abstract: A write protect mechanism is disclosed for a cartridge of the type having top and bottom plates and an information recording medium interposed therebetween. The write protect mechanism comprises a button visible through an aperture in one of the plates and slideably moveable in the aperture between a write protect position and a write enabled position. In the write protect position, an interfacing recording device is actuated to prevent recording so that information previously recorded on the disk will not be inadvertently erased. In the write enabled position, the recording device is actuated to record information on the disk. The button further has a flag adapted to extend into a gap in a rear peripheral wall joining the top and bottom plates to visibly indicate that the button is in the write protect position and that information can not be recorded on the medium. When the flag is retracted, this visibly indicates that recording, if not prevented, could inadvertently erase previously recorded information.

Abstract: A disk cartridge comprises top and bottom opposed spaced-apart plates defining a compartment in which an information recording disk is rotatable. A front peripheral wall joins the top and bottom plates with an aperture in the front peripheral wall communicating with the compartment. The disk cartridge is provided with a brake mechanism that latches the disk axially and radially in an operative plane until the cartridge is inserted fully into a drive mechanism. The brake mechanism also functions to protect the disk against damage, abrasion, cracking and the like, by eliminating annoying rattling when the cartridge is jostled during transporting or in handling. The disk brake mechanism comprises a unitary spring-biased pivotally mounted brake member on one side of the disk center for engaging the periphery of the disk and clamping the disk between the brake member and a pair of angularly spaced nooks located on the opposite side of the disk center.

Abstract: An information-bearing disk (magnetic-rigid or floppy, magneto-optical-Kerr or Faraday, optical or an equivalent thereof) includes equally spaced data-storing tracks grouped in a plurality of annular zones encircling the center of the disk. The ratio of the radius of the innermost track of any given zone to the radius of the innermost track of the adjacent inner zone is a constant, k, calculated from: ##EQU1## where R.sub.o is the outer radius of the outermost zone of the disk,R.sub.i is the inner radius of the innermost zone of the disk, andN is the number of disk zones.With this arrangement of data and by rotating the disk at each one of N substantially constant speeds corresponding to the playing back of data, respectively, from each of the N zones at a fixed predetermined rate, an aggregate number of only (2N-1) individually distinct playback data rates occurs when data is read from each of the N zones.

Abstract: Pneumatically controlled apparatus serves jointly for automatically threading magnetic tape along a transport path past a magnetic transducer head external to a magnetic tape cassette, then transporting the tape along such path. Tape transport elements of the pneumatic-type--air-bearing guides, a vacuum capstan, etc.--are arranged, like the magnetic head, on the oxide surface side (the information-bearing surface) of the magnetic tape. To thread the tape, a vacuum source provides an air pressure gradient the effect of which is to draw tape, spanning a supply reel and a take-up reel, from the cassette in the form of an expandable loop which takes the shape of the transport path when the tape loop expands into operative engagement with each transport element and the transducer head. The transport elements further include a pair of concave air-bearing guides disposed immediately adjacent and tangential to opposing sides of the transducer head.

Abstract: A disk cartridge comprises top and bottom plates having integral peripheral lips joined together to form a peripheral wall when the top and bottom plates are secured together. The peripheral wall serves to space the lower surface of the top plate from the upper surface of the bottom plate to define a compartment in which an information recording medium, such as a disk is contained for rotatable movement. At least one of the top and bottom plates is provided with an elongate head-access opening through which a transducer head gains operational access to the record tracks of the disk when the cartridge is operatively loaded into a disk drive mechanism. To protect the disk from adverse external effects such as dirt, lint, fingerprints, and the like, the cartridge is provided with a spring-biased generally U-shaped shutter for automatically covering each head-access opening when the cartridge is removed from a disk drive mechanism.

Abstract: A method of and apparatus for automatically threading a web material from a supply reel to a take-up reel along an external transport path. In a preferred embodiment, the transport path is defined by a plurality of transport elements, arranged to cooperatively communicate with the oxide surface (the information-bearing side) of a magnetic tape, to cooperatively guide the tape along its transport path past a magnetic head station. A vacuum source serves for establishing an air pressure gradient the effect of which is to controllably pull tape, spanning the tape supply and take-up reels, toward the transport elements in the form of an expandable loop which takes the shape of the tape transport path when the loop expands to bring the information-bearing side of the tape into operative engagement with each transport element.

Abstract: Apparatus for enhancing the bit error rate performance of a storage medium, such as magnetic tape, magnetic disk, optical disk, or an equivalent thereof, includes two data transmission channels for recording in duplicate a stream of data bits corresponding to an information-bearing signal, each recorded bit stream being potentially influenced by a pattern of statistically distributed recording surface defects. During playback, error detection and correction circuitry for each channel provides an alarm signal synchronized with each uncorrected error condition in the corresponding stream of playback bits. A control circuit, responsive to the alarm signals from each channel, serves to interleave error-free bits from one channel, to the exclusion of error bits from the other channel, to provide a single continuous stream of relatively error-free bits corresponding to the information-bearing signal recorded.

Abstract: A transducer head, held in a fixed position as a preformatted disk is rotated a full revolution, reads any sector address accessible to the head. The addresses read come from a plurality of track revolutions that depend on the magnitude of the eccentricity of the disk. A computer, programmed with a least squares algorithm, first coordinates (1) data corresponding to the angular position of the disk each time an address is read, with (2) data corresponding to the actual radius of each address.

Abstract: Helical scan tape recorder/playback apparatus includes a pair of concave air-bearing surfaces disposed immediately adjacent and tangential to opposing sides of a circumferential surface of a rotary head scanner, to cooperatively form a path for guiding magnetic tape past the head scanner at a predetermined angle other than zero degrees. A vacuum source serves to evacuate air from the vicinity of each air-bearing surface to create an air pressure gradient the effect of which is to cause magnetic tape to ride on a thin film of air interposed between the tape and each air-bearing surface during transport of the tape from a supply reel to a take-up reel.

Abstract: A compact SLR camera embodies a zoom taking lens and a diagonal reflecting member along the axis of the taking lens that diverts the optical ray path coming through the lens element forwardly thereof to a viewing screen. The reflecting member is movable along the axis of the taking lens in coordination with the corresponding zooming movement of an adjacent lens element so that the reflecting member and the lens element occupy the same location during different stages of zooming; thereby eliminating the long back focus dictated by the fixed location of the reflecting member in conventional SLR cameras.

Abstract: Voltage regulating circuitry maintains a load voltage of a DC to DC converter within a prescribed range. For that purpose, an SCR latching switch is connected to conduct upon the load voltage increasing to a predetermined upper level, and to become non-conductive in response to the load voltage decaying from the upper level to a predetermined lower level. Bistable switching circuitry, connected to an output of the SCR switch, serves as a current source in response to the SCR conducting, and as a current sink in response to the SCR latch becoming non-conductive. The bistable circuitry provides "snap action" control of an output transistor, which is coupled to the converter, when its load voltage rises and falls, respectively, to the upper and lower levels of the prescribed range, so that the voltage regulating circuitry has a stable, well defined hysteresis.

Abstract: An information-bearing record medium (magnetic tape, disk, or an equivalent thereof) includes a stream of binary bits in which a binary 1 bit is normally represented by a signal transition at the middle of its corresponding bit cell and a binary 0 bit is normally represented by a signal transition at the trailing edge of its corresponding bit cell so long as the immediately following bit cell contains a binary 0 bit, whereby the spacing between successive normal signal transitions is at least one bit cell and is no greater than two bit cells. The binary bit stream includes an address mark byte, for identifying a future substream of data bits, defined by a unique pattern of signal transition having at least one normal signal transition missing, whereby at least one pair of successive signal transitions is separated by more than two bit cells and less than four bit cells.

Abstract: An information-bearing disk (magnetic-rigid or floppy, magneto-optical - Kerr or Faraday, optical or an equivalent thereof) includes equally spaced data-storing tracks grouped in a plurality of annular zones encircling the center of the disk. The ratio of the radius of the innermost track of any given zone to the radius of the innermost track of the adjacent inner zone is a constant, k, calculated from: ##EQU1## where R.sub.o is the outer radius of the outermost zone of the disk,R.sub.i is the inner radius of the innermost zone of the disk, andN is the number of disk zones.

Abstract: Rotary scanner apparatus includes a headwheel having at least one magnetic head arranged for making successive operative sweeps across a magnetic tape. To achieve high data rate transfer, a unitary microwave transmission link includes a fixed cylindrical waveguide on a stationary side of the head scanner and a cooperating cylindrical waveguide rotatably mounted on the rotating side of the scanner. The waveguides are coaxially arranged along the rotational axis of the headwheel for directing a microwave signal, corresponding to a high data rate signal, to and from the headwheel during recording and playback operations. When the headwheel carries multiple magnetic heads, the unitary transmission link serves advantageously for the simultaneously coupling of a recording signal and a playback signal to and from the head scanner, for testing and certifying a recording system in real time.

Abstract: A method and apparatus for characterizing a central circular aperture of a workpiece, for example a flexible information storage disk. The apparatus utilizes a noncontact sensor system having a rotary stage upon which the workpiece is placed. A reference edge extending approximately to the axis of rotation of the stage serves as a reference point from which a laser beam measures a plurality of radial distances extending from the reference edge to a plurality of points about the disk's central aperture. A computer utilizes these distances along with a known deviation of the reference edge from the center of rotation of the stage to construct a shape comprising a plurality of inscribed triangles. The center of the shape is found by mathematically determining its center of gravity. The center of gravity is then used to locate a reference coordinate system and precise reference circles are drawn around the center of gravity.

Abstract: A film video player includes an electronic strobe light operable for repetitively firing a flash tube to flash illuminate a solid state image sensor via a pulse of light projected via a photographic film during the vertical retrace interval of a standard television signal. Detector circuitry, responsive to a signal relating to an output of the image sensor, produces a control signal that is functionally related to whether or not the illumination of the image sensor is above, below, or within a predetermined range near the saturation level of the image sensor. A microprocessor adjusts an exposure level signal at the vertical retrace rate in accordance with the control signal.

Abstract: Apparatus for positioning and attaching a reinforcing ring in coaxial relationship to a floppy disk, includes a force translating mechanism mounted for movement to and from a resiliently mounted circular receiving member. A cylindrical positioning member, connected to the force translating mechanism, has first and second concentric reference surfaces corresponding respectively to the inner diameter of the reinforcing ring, which is carried by the force translating member, and the inner diameter of the floppy disk, which is disposed about the receiving member.

Abstract: A magnetic disk includes a pair of azimuth test tracks of relatively narrow trackwise width located adjacent each other so that a magnetic head, the azimuth of which is to be measured, straddles both tracks at the same time. Each test track includes a recording pattern comprising a series of separate, uniformly spaced magnetic domains of alternating orientation, the recording pattern on one track being in a particular phase relative to the recording pattern on the other track. Upon playback, the magnetic head produces a composite playback signal comprising a series of localized peaks, the time between adjacent peaks being functionally related to head azimuth.