Abstract: A self-aligning configuration for establishing precisely where each of any number of tracks is to be recorded on a magnetic tape, utilizes therefor a photosensitive element (of perhaps even coarser structure than that of a given track), the signal output of which constitutes a measure of the location of the track(s). Thereafter, tracking control, say during playback, is pursuant to such signal, which is memorized.

Abstract: A technique for defining the gap depth of a magnetic head utilizes side-by-side knife edges which point in generally opposite directions, and define thereby a reference gap depth. The resistance of a conductive layer beneath the structure which defines one knife edge is the analog of the gap depth.

Abstract: In a MR head of the non-shunt bias type, one or more extremely thin coatings of a sacrificial conductive material are applied on the magnetoresistive strip, each such coating being so thin that it has extremely high sheet resistance in comparison to the sheet resistance of the MR strip. Because the sacrificial coating(s) is (are) in direct contact with the MR strip, the requirement for electrical conductivity between the coating(s) and the MR strip is (are) met; and because the sacrificial coating(s) is (are) of high resistivity, very little sense current is sapped away from the MR strip by the sacrificial coating(s), with attendantly very little decrease in the sensitivity of the head. By sandwiching the MR strip between equi-thick sacrificial coatings, whatever leakage currents flow through the high resistivity sacrificial coatings are productive of equal and opposite biasing effects vis-a-vis the MR strip, i.e.

Abstract: The invention teaches the use of a permanent magnet easy axis biasing structure having the same (or nearly so) physical geometry as the MR sense film itself, whereby a similar, but opposite, demagnetization field is generated in the biasing structure as is generated in the sense film. Thus, with the two demagnetization fields complementarily cancelling each other, any tendency of the sense film for multi-domain formation therein is cancelled (or at least lessened).

Abstract: Both hard and easy axis bias fields are applied to the sense film of an unshielded magnetoresistive (UMR) magnetic head by a single bias source. The easy and hard axis fields are applied to the UMR sense film by so angling the applied bias field that orthogonal components of the field lie, respectively, in the directions of the easy and hard axes of the film.

Abstract: To provide optimized performance in a magneto-resistive head having a soft adjacent magnetic biasing layer separated from a current-carrying magneto-resistive sense film by an extremely thin electrically insulating film, the invention provides that the soft adjacent magnetic biasing layer be comprised of a magnetically soft layer of high electrical resistivity, whereby the effect of pinholes in the electrically insulating film is significantly lessened.

Abstract: An improved form of magnetic erase head is provided which utilizes, in a magnetic erase head, leading and trailing "terminators", which suppress stray fields emanating from leading and trailing magnets.

Abstract: A video tape duplicator for duplicating a video signal simultaneously on a plurality of video tapes at high speed. The duplicator includes a source for providing a high frequency video signal and a record head for simultaneously recording the high frequency video signal on a plurality of duplicate magnetic tapes. The record head rotates at a speed which is related to the frequency of the high frequency signal so that the duplicate tape may be played back at normal head and tape speeds.

Abstract: In a multi-channel device for the processing of digital data bytes comprised of parallel arrangements of data bits, the invention calls for recognition of the fact that--irrespective of skew and other interchannel variations in the processing of such data bits--the median-occurring bit of each successive data byte constitutes a good representative of the time of occurrence of the byte in question. By suitably buffering the bits of successive data bytes, a "median clock" that is slaved to the aforenoted "median-occurring" bits may be used to clock data bytes--devoid of inter-channel timing errors--out of the apparatus used for the indicated buffering operation.

Abstract: Trackwise disparity between inductive record and magneto-resistive playback heads which are built on a common support is measured and memorized. Thereafter, during head-positioning, the memorized disparity is employed as a track-address bias for proper registration of the playback head, irrespective of its widthwise disparity relative to the record head. To achieve the aforesaid measurement, the invention provides for a self-calibrating algorithmic routine that generates the aforesaid bias.

Abstract: The invention in one embodiment thereof employs separate and respective heads for disparate signal frequency bands. One head is kept in intimate contact with the recording medium to maximize the response to the higher frequency signal band; and the other head is vibrated relative to the surface of the recording medium, thereby to augment(d.phi./dt)and to improve the playback response to the lower frequency signal band. Since the two heads cannot reside physically at the same location, a suitable delay device is employed to bring the signals from the two heads into proper timed relationship, the outputs of the two heads being appropriately band-passed to reconstruct a complex signal composed of the two signal bands.

Abstract: A yoke-type magneto-resistive head employs a thin magnetic film structure to bridge a gap in the flux conducting structure of the head and thereby sense magnetic flux. The invention provided means for reducing the magnetic reluctance of the interface between the magnetic film structures and the flux conducting structure of the head, to improve the coupling of magnetic flux from the flux conducting structure to the magnetic film structure and thereby increase the sensitivity of the magneto-resistive head.

Abstract: An apparatus is disclosed having means for shunting demagnetization fields to prevent "magnetostrictive knockdown" of a signal recorded on an isotropic recording medium.

Abstract: Slant gap magnetic heads, comprised of back-to-back wedges, are produced by an inventive procedure: Bars of discrete coil-wound thin-film heads--which bars are, cross-sectionally, L-shaped--are stacked with respect to each other. By dicing through the stack of bars at an angle commensurate with the degree of gap-slant, discrete slant gap head structures are produced. With minimal contouring/lapping, such head structures may be finished for use in recording equipment that records chevron-like alternating skewed information tracks.

Abstract: An antenna reflector is disclosed having a laminated reflector surface bonded to a rigid molded support structure. The reflector surface is thermoformable and has at least one metallized layer that is "sandwiched" between two plastic layers. The forming of the antenna reflector is accomplished in a single molding operation.

Abstract: In a multi-channel apparatus, a first plurality of N channels support user data and associated error correction and a second plurality of channels each contain a unique p-bit symbol followed by N consecutive M-bit samples of each of the N data channels. The receiver or retriever apparatus regenerates a system clock from all channels and examines the respective bit streams to score each bit phase as a match or a non-match of the sample in the synch channel with each M bit sample of the respective N data streams, and for each such N channels a counter corresponding to the then current phase is incremented or decremented. Relative skew for the N channels is derived from the addresses of the first counter to overflow for each of the N channels.

Abstract: Data is so recorded in tracks of a first radially disposed zone of a disc that the minimum bit length limit is not exceeded within the innermost track of the zone and, in another more inwardly radially disposed record zone (or zones) of the disc, the quantity of data recorded in the tracks thereof is binarily reduced so as again not to exceed the minimum bit length limit within the innermost track of the second zone, etc.

Abstract: The disclosure hereof calls for the shearing of a thin film dispersion of magnetic particles. Magnetic fields, selectively perpendicular to the plane of shear or the direction of shear, control the degree of clumping experienced by the dispersion particles.

Abstract: It has been found that, if a (negative) bias is applied to a substrate during the sputtering thereto of Alfesil, selective re-sputtering from the substrate film of aluminum and silicon will leave that film rich in iron and, attendantly, of higher saturation magnetization (17,000 gauss) than the starting material Alfesil (10,000 gauss). Such being the case, the invention provides that the sputtering of Alfesil-type material during the manufacture of a magnetic head be performed in two phases, first, while applying a bias of a first sense to a substrate to be sputtered upon, and, second, while applying a bias of different sense (e.g. a zero bias) to the substrate, thereby to cause a composite thin film to be formed on the substrate. The composition of the thin film in question is: 1. a (generally thin) region of material of high saturation magnetization layered with 2. a (generally thicker) region of lesser saturation magnetization.

Abstract: Slant gap magnetic heads, comprised of back-to-back wedges, are produced by an inventive procedure: Bars of discrete coil-wound thin-film heads--which bars are, cross-sectionally, L-shaped--are stacked with respect to each other. By dicing through the stack of bars at an angle commensurate with the degree of gap-slant, discrete slant gap head structures are produced. With minimal contouring/lapping, such head structures may be finished for use in recording equipment that records chevron-like alternating skewed information tracks.