Abstract: Servomechanisms (58 and 60) control a takeup reel (12) and a tension arm (16) in a cassette recorder. The servomechanisms receive control signals (54 and 56) generated in accordance with respective control functions, each of which includes a respective constituent function of the difference between a commanded tension-arm position and a measured tension-arm position. In a position of the tension arm that prevails at the beginning of tape threading the constituent of the tension-arm control function that depends on this arm-position error is a relatively large contribution and gradually decreases to zero as the tension arm moves to the position that it assumes for normal recording and playback. During the same time, the the constituent of the reel-control function that depends on arm-position error begins at zero and gradually increases. Such a gradual transfer of position-error-based control suppresses tape-tension transients that would otherwise result.

Abstract: A head having very low leakage flux loss since the head is constructed with a very small elongate magnetic intercore, having a winding window formed therein if desired, with the intercore being supported on either side by non-magnetic side support blocks. The side support blocks enable mounting of the head to the usual style of head block and provide the physical structure and size necessary for formation of a low wear head profile, if desired.

Abstract: A video special effects system and method includes at least one signal system operating in real time to transform one or more input video signals to generate an output video in response thereto, a work station, an operator control panel and a control system communicating with the signal systems, the work station and the control panel. Control surfaces defined by one or two control curves are developed at the work station and subsequent used by the control system to define a video effect in which portions of the input video images are selectively mapped to the control surfaces and subsequently manipulated to define an output video image. The control system operates to define each parameter controlling the output image at selected event times and to individually interpolate each given parameter between the event times at which the parameter is defined. The signal systems generate the output images in response to input images and the instantaneous values of control parameters defined by the control system.

Abstract: A video special effects system and method includes at least one signal system operating in real time to transform one or more input video signals to generate an output video in response thereto, a work station, an operator control panel and a control system communicating with the signal systems, the work station and the control panel. Control surfaces defined by one or two control curves are developed at the work station and subsequent used by the control system to define a video effect in which portions of the input video images are selectively mapped to the control surfaces and subsequently manipulated to define an output video image. The control system operates to define each parameter controlling the output image at selected event times and to individually interpolate each given parameter between the event times at which the parameter is defined. The signal systems generate the output images in response to input images and the instantaneous values of control parameters defined by the control system.

Abstract: An automatic scan tracking, helical tape type of data recorder is disclosed herein along with its method of operation. Data is written onto magnetic recording tape along with data retrieval information by means of a rotating scanner assembly forming part of the recorder as the recording tape moves at a given recording speed in cooperative engagement with the scanner assembly. Data is normally retrieved from the recording tape along with the data retrieval information by means of the rotating scanner assembly as the recording tape moves longitudinally at the same given recording speed. In operation, the rotating scanner assembly of the recorder retrieves data and data retrieval information from a segment of the recording tape while the latter is not moving, that is, during a period when the tape is stationary for enabling adjustment of the read head position relative to the track depending on the evaluation of the data resulting from the stationary tape read.

Abstract: An improved magnetic head obviates the need for separate read and write heads in a magnetic storage system by providing a head core having two physical gaps configured to generate a reproduce track width that is narrower than a record track width. The core of the head comprises a tapered center pole disposed between two generally symmetrical main poles to form physical record and reproduce gaps. A magnetically saturable, high permeability element is disposed within the core in a manner that bridges the rear of the record gap.

Abstract: Drivers (24, 26, and 28) in the controller for a motor (14) drive the motor in accordance with a pulse-width-modulation scheme in which each pulse-width-modulation cycle includes a positive interval and a negative interval so that the value of the filtered output is proportional to the difference in duration between the positive and negative intervals. The pulse-width-modulator cycle also includes dead times between the positive and negative intervals, and these dead times are varied so that a change in a positive interval's duration in a fixed-duration pulse-width-modulation cycle does not necessarily result in an opposite change in the negative interval's duration. Consequently, the value resolution for a system in which the pulse-width-modulation cycle is a given number of system clock periods can be finer than it would be if the dead-time interval's duration were fixed.

Abstract: An improved, shielded magnetic core structure is disclosed that is particularly well suited for use in magnetic read and write heads adapted for narrow track, short wavelength magnetic recording systems, and for transformers of high performance, wide band application. The improved magnetic cores use novel field confinement structures to reduce or eliminate leakage magnetic paths which normally do not link the head gap or do not link the transformer windings. This shielding arrangement substantially improves the performance of such devices, as compared to conventional, unshielded heads and transformers. Embodiments involving toroidal cores, thin film heads, and MR heads are disclosed, along with high performance, wide band transformer structures.

Abstract: In an azimuth recording format, the crosstalk of the A channel into the B channel is higher than the crosstalk of the B channel into the A channel because, at the ends of a magnetic recording where the switching contour of constant magnetic field strength is equal to the media magnetization switching field, the switching contour follows a curve. The resulting curvature at the ends of the magnetic recording vary accordingly the angle of azimuth rejection between the B to A azimuth relative to the A to B azimuth at the edges of the track. The use of a record head of a unique design wherein the trailing pole face of the head extends laterally beyond its leading pole face at the over-writing side of the head, removes the curvature at the ends of the transition recordings forming the recorded tracks.

Abstract: A flexural pantographic mount for use in a helical scan magnetic tape transport, the mount being a boxed leaf stiffened flexural pantograph mount, for holding and varying the position of a moveable head in a helical scan automatic scan tracking magnetic tape transport. The mount includes a moveable body such as a magnetic transducing head assembly coupled at one end of first and second generally parallel spaced apart elongated flexural pantographic leaves configured at the opposite free ends thereof for attachment to a fixed body. Each leaf includes first and second integrally formed and bent leaf edge extensions, which act as side stiffeners. A triangularly configured opening and a trapezoidally configured opening are formed in each leaf with each opening being configured to include tab projections for bending into the opening to provide transverse or lateral stiffening.

Abstract: A translatable capstan/tachometer assembly for use, for example, in transporting a magnetic media in a data record/reproduce apparatus, includes a capstan rotatably coupled to a tachometer unit. The assembly is supported for movement from an initial, unthreaded media position within a threading cavity of a data cassette, to a threaded or locked working position. The media path is arranged so that moving the capstan/tachometer assembly into the threaded position causes the media to wrap around the capstan with a substantial wrap angle. In play, record, jog or variable speed operational modes, movement is provided between a motor/disc assembly and the capstan/tachometer assembly to rotatably drive the capstan. In a high speed shuttle mode, the motor/disc assembly is disengaged but the capstan/tachometer assembly remains in contact with the media, thereby still providing tape speed information via the integral tachometer unit.

Abstract: A method and apparatus for data storage and retrieval including first and second banks of refreshable memory, such as DRAMs. The user application provides a write clock and a read clock, the read clock being independent of the write clock. FIFO buffers are provided between the user application and the memory, with the buffers providing for read data with associated addresses and write data with associated addresses. A DRAM controller system is provided including a timing generator for the DRAM controlled by an external clock. The controller system controls the buffers to enable the continuous writing of user data to one of the first and second banks at a given address, with the user address and data synchronized to the write clock, while enabling simultaneous reading of data at a user provided address from the other of the first and second banks, with the loading of read addresses and outputting of read data occurring continuously and synchronously to the read clock.

Abstract: A magnetic transducer is batch fabricated from a pair of confronting elongate composite block substrates each formed of a thin cap of non-magnetic material bonded to a much larger block of magnetic material, such as ferrite. An intermediate winding groove is formed in proximate relation to the non-magnetic material along the length of one or both composite block substrates. One (or both) of the substrates is provided with a plurality of parallel spaced V-shaped grooves oriented in a direction perpendicular to the winding groove, wherein adjacent grooves form therebetween track width defining [prtopms. A core layer of high permeability magnetic material, such as Alfesil material, is deposited over the edges whereby magnetic poles are formed of the edges. A gap layer of insulating material is deposited on the edges over the high permeability magnetic material. Two of the composite block substrates are placed with the edges in aligned abutting relation and are assembled by glass bonding.

Abstract: A recording and reproducing system which has the capability of recording user data and system format data in physical blocks of predetermined size on a recording area of a tape, with the user data being identified by files and contained in data blocks having a predetermined size. Partial overrecording of data blocks can be performed in that physical blocks are retained which have valid data blocks, and new physical blocks are then recorded beginning with a rewritten data block.

Abstract: The presence and stability of the input digital video signal of a digital video device, such as a digital video tape recorder system, is determined by a system control microprocessor running a program for periodically reading signals from an input data clock presence detector circuit, a circuit detecting presence of timing reference code words in the input digital video signal, and circuits measuring rates of single-bit and multiple-bit errors in the detected timing reference code words. The input signal is determined present and stable if the input data clock is present, timing reference code words are present, and if measured sync data error rates do not exceed some experimentally determined threshold values.

Abstract: A method and apparatus for the generation of a signal flag in response to illegal channel code patterns from an information channel, the signal flag may typically be used as an erasure flag by a subsequent error correction decoder. This erasure flag, being indicative of a data error position which can then be fed into a utilization circuit such as an error correction logic for performance improvement. In particular, a Miller-squared channel code format decoder in accordance with the present invention can easily and inexpensively provide error position information thereby enhancing error correction power, such as that of a Reed-Solomon error correction code.

Abstract: A rotary access arm, e.g. for an optical disk has crossed voice coil actuators (6a,b) for in-plane and vertical movements, e.g. track and focus control; the actuators are secured to its distal end in close proximity to the focussing optical system (5a,b). The heavy elements like laser light source (8) and beam analyzer (11) are arranged near the rotational axis (10) of the arm (or are completely separated therefrom) allowing a very lightweight construction. In an optical storage system using stacked disks coaxial access arms with individual position control are provided. For increased reliability of operation each access arm has two focussing optical systems at its distal end, viewing in opposite directions, and a bistable optical switch (12) to selectively focus the laser beam on one of the two adjacent optical disks. The focussing optical system can be realized with individual lenses or with two conjugate plano-aspheric lenses bonded to a 90.degree. reflection prism.

Abstract: A disk cartridge file employs a cartridge which is a rigid enclosure containing a flexible information storage disk mounted on a drive hub. One wall of the cartridge comprises a central hub drive aperture and an arcuate radially extending access slot for a read/write transducer. In operation, the disk flies over the inner surface of the apertured wall on an air bearing. This surface is planar over a major portion including the access slot but has a smoothly contoured raised land bordering the slot on the downstream side thereof. When employed in combination with a transducer of the ring stabilized type which projects through the slot and penetrates into the normal path of the medium, the transducer is coupled with the medium in a stable closely spaced air bearing relationship. The raised land extends the range of penetration over which the transducer is coupled, particularly at the outer diameter of the disk.

Abstract: Flat objects (6), e.g. non-transparent wafers, are tested over their entire surface for thickness variations in an interferometric set-up (FIG. 1) where symmetrical opposite points on the front and rear surface, respectively are sensed by the same light ray (10). A laser beam (3) impinges under oblique angle of incidence on a beam splitter (e.g. a grating 4) to generate a reference beam (3a) and a measurement beam (3b). The latter is directed by a first of a pair of plane mirrors (5a) to the front surface of sample (6) from which it is reflected again to plane mirror (5a) to reach blazed grating (7) which deflects it symmetrically to plane mirror (5b). The rear surface of sample (6) is thus illuminated under the same angle of incidence in a way that each ray (10) is directed to the point on the rear surface that is exactly opposite to its reflection point at the front surface.

Abstract: With high density reel-to-reel tape drives, slight perturbations in the tape path can cause instantaneous speed variations in the tape which can alter the recording density of data on the tape over a very short interval. This condition can be detected by measuring changes in recording intervals on a plurality of data tracks. Whenever all of the tracks indicate an unacceptable change in the recording interval an unacceptable speed variation has been encountered.