Abstract: A return-to-zero (RZ) vertical digital magnetic recording method and apparatus comprising a selectively magnetizable recording medium which includes a recording layer of magnetic material having a low vertical remanence. A magnetic recording head is positioned in close proximity to the recording medium, and relative motion is produced between the recording medium and the recording head. To record data, the recording head is energized with one short duration current pulse for each unit of data to be recorded. The resulting bipolar magnetic write field closes substantially perpendicular through the recording medium thereby producing, in the medium, a similarly bipolar flux configuration having the magnetic transition centered about the gap of the magnetic recording head. Data is represented by these transitions in RZ vertical magnetic recording.

Abstract: A method for making a thin film magnetic head assembly comprising the steps of depositing a first magnetic pole piece layer, depositing a nonmagnetic material gap forming layer, and depositing a protective layer of etch resistant material. A layer of insulation is deposited upon which is formed a conductive coil. A leveling pad of insulation is deposited over the conductive coil, and the part of the protective layer which is not covered by the insulation is removed. The gap forming layer is therefore protected during the processing steps so that a desired gap length is produced. The second magnetic pole piece layer is then deposited to complete the magnetic circuit.

Abstract: A magnetic head assembly includes a magnetoresistive (MR) element for reading magnetically recorded information from a record medium. The MR element comprises an elongated member having a predetermined height and a plurality of elongated attachments which are contiguous with and made of the same material as the MR element. The elongated attachments have a predetermined width and a predetermined spacing and the attachments are unidirectionally magnetized along their length so that a bias is produced to maintain the MR sensor in a single domain state and to obtain a substantially linear component in the MR response in the MR element so that Barkhausen noise is suppressed and so that previously recorded information is read from the medium with optimum sensitivity.

Abstract: A magnetic head has three pole pieces that form a magnetic circuit. The magnetic pole pieces are arranged in a common plane so that the two outside pole pieces are each spaced from the central pole piece to form a transducing gap between each of the outside pole pieces and the central pole piece. A first and a second coil, each having the same magnetic sense, is wound on the magnetic structure between an outside and the center pole piece. The coils are connected in series for a write operation so that the flux in the outside pole pieces is additive for writing, and the coils are connected in series opposition for a read operation so that the flux produced in the center pole by a previously recorded magnetic transition in the magnetic recording medium adjacent to the transducing gaps is sensed additively in the coils.

Abstract: For making rails in workpieces for magnetic head sliders for sensors of magnetizable media, anodic oxidation of highly pure aluminum substrates is applied. For that purpose, the respective surface of the substrates is covered with a mask cover which leaves uncovered the zones in the substrate surface area which are intended for the forming of rails. By means of anodic oxidation of the aluminum in the exposed regions, rail layer regions of oxide are formed which after the removal of the mask cover can themselves be used as an etching mask in order to provide a recessed region between two respective rails by means of chemical wet etching.

Abstract: A character generator for a raster printer which prints in the page mode. Input format data is generated in response to the input print data which defines for each pattern the position of the pattern on the page, the size of the pattern and the location of the pattern in the raster pattern storage. The format data is accessed for all patterns beginning within a predetermined plurality of scan lines and raster data is accessed in response to the format data to store in an output buffer the raster pattern data in the sequence, size and position defined by the format data. The raster pattern data can then be accessed to control a printer to print on a print medium a pattern defined by the input print data.

Abstract: An MR sensor is disclosed in which a pair of thin film magnetoresistive strips are connected electrically in parallel between two terminals. Strips are spaced apart a distance which is small relative to the density of the stored data to be sensed. The strips are mutually-biased in opposite directions to corresponding points in the linear region of their respective curves by current from a constant source attached to one terminal. Since the resistance of each strip is equal, the current divides equally between the strips.The sensor is positioned adjacent the magnetic surface containing stored data. Vertical components of the magnetic field (preferably vertically recorded data) influence the resistance of the strips differentially. When the sensor encounters a vertical flux transition, the output voltage varies to produce a unimodal type pulse.

Abstract: A print head assembly with interchangeable pluggable printed circuit print heads has means for automatically positioning a head during insertion with the aim of ensuring registration of printed circuit electrodes on the head with correspondingly positioned conductors on a body portion. The print heads are supplied as a variety of types all of which are interchangeable as a simple push-fit in the body portion. A clamp ensures that ohmic contact is established and maintained between the registering electrodes and conductors. Each head is also provided with a pattern of electrodes which serve to identify the head type. The pattern bridges selected additional conductors on the body portion and provides a decodable pattern of signals in response to an interrogate signal unique to heads of that type.

Abstract: A dual element magnetic transducer in which the thin film MR read element is transversely biased by flux in the air gap of the inductive write core generated by a bias current supplied to the write winding. Flux in the air gap biases the MR element because different integral portions of the MR element have a different spatial relationship to parallel opposing portions of the inductive core. The flux which would normally pass through the gap substantially normal to the sides of the core defining the gap now tends to follow the MR element along a direction normal or transverse to the media to a point where the distance between the MR element and the core is smaller than where it entered. By appropriate control of the bias current and the spatial relationships, a relatively efficient, simple to manufacture dual element magnetic transducer is provided.

Abstract: A method for recording high frequency signals representing data with simultaneous readout of low frequency information, such as servo information prerecorded on a magnetic disk, comprises the step of modulating with the data a carrier signal having a repetition frequency displaced significantly from the baseband of the data. The nonlinearity of the recording channel converts the modulated signal spectrum into the low frequency baseband so that the data is magnetically recorded while the low frequency prerecorded information is read out.

Abstract: Apparatus for producing a line source of a desired shape from a light source such as an excimer laser comprising means for directing the light source along a predetermined path to a cylindrical lens positioned to produce a virtual line image having uniform intensity along its length at a first location. However, the image is intercepted by a cylindrical mirror inclined at an angle so that the beam is transformed into a curved shape and directed onto a quartz diffuser. This apparatus produces a curved self-luminous distribution having uniform intensity over its length. In a specific embodiment, the diffuser is a directional diffuser.

Abstract: A laser light source for a high resolution projection lithography system and transforming optical apparatus which transforms the laser light into an optically equivalent self-luminous curved line source. The transforming optical apparatus comprises a two-dimensional array of fly's eye lenses positioned to intercept light from the light source and to produce a series of point sources having a selected numerical aperture. An optical fiber array is positioned so that the imput end of each fiber receives the light output from one of the lenses in the array. The position of the fibers is chosen so that light from the lenses underfills the fibers to preserve the numerical aperture. The output ends of the fibers are arranged in position to produce a curved line source of a desired shape. Alternate embodiments are described in which lens arrays can be selectively positioned to change the numerical aperture of the transforming optical apparatus.

Abstract: An ink jet drop-on-demand printing system comprising an ink jet print head having an ink cavity supplied with a suitable ink. An electromechanical transducer is mounted in mechanical communication with the ink cavity, and a source of electrical signals is provided to selectively actuate the transducer to produce an ink drop of a selected size. To produce ink drops of a selected size the source of electrical signals produces one or more electrical drive signals each separated by a fixed time delay which is short with respect to the drop-on-demand drop production rate. Each electrical drive signal ejects a predetermined volume of ink and all the volumes of ink merge to form a single drop prior to the time the ink drops reach the print medium for printing.

Abstract: A test sample (7) of the same material, or with the same structure as the workpiece (5) exposed to subtractive processing is simultaneously exposed to such processing and consists of a wedge (10) with the angle.alpha. covered by two covering plates (11) which are complementary to its two surfaces (14). By measuring the distance x.sub.1 between the thus formed gaps (15), and by comparing it with the original distance x.sub.

Abstract: A method and apparatus for simultaneously recording multiple Fourier Transform Infrared (FT-IR) signals using an interferometer. The analog signals are coupled to switching means which is operable in response to a first control signal for synchronizing the operation of the interferometer and the control circuits and a second control signal for defining data acquisition intervals to direct the sampled data of the analog input signals over a circuit path including Sample and Hold and Analog to Digital Conversion circuits to a processor for storing the digital data corresponding to the analog input signals. The switching means is operated so that samples of the analog input signals are taken in sequence and stored in sequential storage locations in interleaved fashion. The processor is operable under program control to access the digital data so that all data samples for the same input signals are separated to produce an interferogram for each of the input signals.

Abstract: An electronic circuit arrangement effecting current flow simulating the faradaic current, oxidation reduction potential and the like of an electrochemical cell encompasses two key concepts. The first recognizes that since the semi-integral of the cell current effectively deconvolves the diffusion aspect of the phenomenon with the resultant describing the surface concentration of reacted species, then the semiderivative of a function describing a surface concentration of reacted species results in an output representing the cell current, including diffusion. The second is embodied in a circuit arrangement properly simulating this concentration behavior cell double layer potential and in yielding an output proportional to the surface concentration of reactant species corresponding to that potential in response to applied cell barrier potential.

Abstract: For the point-by-point interferometric measuring of surfaces which are scanned along lines, or which are subjected to a processing procedure (e.g. etching) a focused laser beam is directed with oblique incidence as a measuring beam onto the respective measured points. The respective height of a measured point determines the path difference (phase difference) between the measuring beam and a reference beam which has been suitably split off the input beam. The oblique incidence (angle of incidence .gtorsim.80.degree.) makes it possible to measure interferometrically very rough surfaces. The measuring range may be extended if the reference beam is directed at an oblique angle of incidence, differing only slightly from that of the measuring beam onto the surface to be examined.

Abstract: An ink jet drop-on-demand printing system having gray scale capability comprising a transducer having a plurality of separately actuable sections. Print data is provided which defines a selected drop volume and control means is provided which is operable in response to the print data to produce drive signals to selectively actuate a particular combination of the separately actuable sections of the transducer to produce a drop of the volume specified by the print data. To provide further control over the drop volume while maintaining the drop velocity within selected limits, the amplitude of the drive signals can also be varied. A further refinement can be provided by varying not only the amplitude of the drive signals but also the pulse width of the drive signals. In a first embodiment the transducer sections are of equal length, while the sections are of unequal length in a second embodiment.

Abstract: A drop-on-demand ink jet printing apparatus comprising a print head having an electromechanical transducer mounted in mechanical communication with the fluid in a fluid chamber within the print head. The transducer is selectively energized with a drop ejecting signal so that one drop of ink is ejected for each drop ejecting signal. In addition the transducer is energized with a series of low amplitude excitation signals which serve to maintain substantially constant dynamic ink characteristics so that quality printing is produced especially during start-up of the apparatus. The excitation pulses can be asynchronous with respect to the drop ejecting signals or synchronous but delayed with respect to the drop ejecting signals. Isolation means are provided to prevent concurrent excitation of the transducer with both a drop ejecting signal and an excitation signal.

Abstract: The invention is directed to circuitry for reproducing the data on a magnetic stripe recorded. A security access card is manually passed through a card-reading device at an uneven low velocity, storing the data in one half cycle of operation in uniform number of data storage cells despite the unevenness of speed, and reading out the data at a predetermined rate, during the other half cycle of operation for delivery to a data processing unit.