Abstract: This invention describes a means and method for moving an arm in precise angular increments to a degree of precision far beyond the capacity of a normal reduction gear assembly acting at the impetus of a stepper motor. At rest a set of paired and unequal high precision gear sets hold the member in place. To accomplish movement, they are decoupled and a normal reduction gear mechanism is employed to drive the member to the approximate location desired. The more precise location of the member is accomplished by the recoupling the high precision gear sets. Thus, without high precision movement a high precision location is attained.

Abstract: An integrated circuit package includes a leadless ceramic chip carrier and four connectors mounted thereto. The chip carrier has a rectangular surface with a plurality of conductive pads at its periphery. Each connecter includes a set of elongate conductive arms attached to the contact pads and extended outward therefrom and parallel to one another. The outer ends of the arms in each connector are attached to a generally flat and dielectric member. The arms are folded back upon themselves to position each member opposite the leadless chip carrier surface, with the outer ends of its associated arms aligned with the pads. So aligned, the arm ends are positioned for direct connection to selected contacts on a printed circuit board.

Abstract: Apparatus is shown for mixing an epoxy adhesive. An epoxy resin and its associated curing agent are simultaneously loaded from separate cartridges into a length of flexible PVC tubing, part of which is contained between a rotor and a stator. Bearings, mounted rotatably about the rotor, engage and travel along the tubing as the rotor is revolved, each bearing compressing the tubing at its point of engagement. The tubing, repeatedly compressed and released by each bearing in succession, kneads the epoxy resin and curing agent into a homogeneous mixture.

Abstract: Pseudo-random numbers (PRNs) have great importance in data processing and encryption. The standard technique for generating PRNs on computers at the present time involves software implementation of recursively computing PRN.sub.n+1 =(PRN.sub.n)(b) mod M, in real number field which means that a relatively slow and involved multiplication must occur for each PRN, and each PRN calculation is strictly subsequent to previous PRM calculations. This disclosure shows a systolic multiplier implemented by a series of exclusive OR operations which generates simultaneously a new set of the PRN's from the current set of PRN's in parallel. The operation of multiplication mod M is performed over a finite field instead of a real number field. To facilitate the multiplication, the input operands are first transformed into a different representation that consists of more bits than that of the original ones. The operation of multiplication is then carried out in this transformed representation.

Abstract: A construction for actuator assemblies is disclosed using a material of low permeance as a structural element, included normal to the axis of coil movement to lower coil inductance by reducing reactance flux in support structures and providing a channel for eddy currents set up in response to coil reactance. The net result is enhanced coil responsiveness to energization.

Abstract: A disk cartridge assembly includes a rotatable magnetic disk enclosed within a rectangular cartridge. Attached to the top and bottom covers of the cartridge are a plurality of leaf springs which urge the top and bottom sections toward and against one another. Resilient cloth liners are mounted to the inside surfaces of the top and bottom covers. As the leaf springs urge these sections toward one another, the liners engage the disk surface to prevent the disk from moving freely within the cartridge. The leaf springs are flexible in the axial direction but rigid in the radial direction, thus to maintain the top and bottom sections in alignment with one another.

Abstract: An optical disk cartridge has two opposed cartridge sections held together by four locking assemblies. Each locking assembly includes a first locking jamb attached to one section, a second locking jamb attached to the other section, a locking detent and a spring. The jambs can be locking fingers parallel to and adjacent to one another when the cartridge sections are joined, in which case the detent surrounds the fingers as a sleeve, preventing the fingers from moving apart. The spring biases the detent into locking engagement with the fingers, keeping the cartridge closed. Alternatively, the jambs can be aligned slots in the cartridge top and bottom sections, with each detent having a protrusion that enters its associated slots. The spring and most of the detent are contained inside the cartridge. However, each detent includes a leg extended outside the cartridge through an aperture in the cartridge side wall. Also disclosed is a drive apparatus for use with the cartridge.

Abstract: A cable sensor for sensing a DC signal sent by a cable system's headend in order to switch a converter from converting one set of frequencies to another. When the cable sensor detects such a DC signal, it provides isolation from the DC for a cable tv ratings monitor connected to the cable system and further provides a signal to the monitor that the signal has occurred in order for the monitor to switch frequency/program assignments.

Abstract: An optical recording system has a system optical apparatus carried by a fine tracking system which moves the optical apparatus for small track seeking movements and for track following. The fine tracking system is carried by a linear actuator coarse tracking system which makes large track seeking movements so that the entire area of the optical recording media is available to the system. Both the coarse tracking system and the fine tracking system are operated by servo control loops. The fine tracking system responds to tracking status signals with respect to track following and track seeking signals in response to track addressing information. The coarse tracking system responds to position sensor signals derived from a position sensor which is associated with the fine tracking system and provides signals related to the relative position of the fine tracking system to the coarse tracking system.

Abstract: A static eliminator comprises a contact mounted to a gimbal spring backed by a damping pad supported by a load spring. The contact bears against the polished end surface of the motor shaft of a disk drive so static electricity is grounded through the gimbal. The geometric arrangement of the contact and shaft is such as to prevent generation of vibration and excess noise as the spindle rotates.

Abstract: A disk drive is provided with a vent tube which is long (i.e., 20 inches) compared to its bore (i.e., 0.013 inch) to minimize diffusion of water vapor into the drive without seriously affecting pressure gradients along the length. Minimum bore diameters are given for specified lengths of vent tube. Conveniently, a desiccant is employed with a heater to absorb water vapor admitted to the drive and to expel water vapor when the drive is operated. A thermally-operated valve is also employed to expel water vapor when the drive operates. The desiccant may be employed in a chamber separated from the disk chamber, whereupon pressure valves are provided to adjust the pressures in the drive.

Abstract: An apparatus for positioning a magnetic transducer member with respect to a magnetic disk has an actuator which is rotated about an axis and includes an arm having a first end secured to the actuator for rotation of the arm about the axis. The arm has an oppositely disposed second end. A load spring member has a first end and a second end and is secured at its first end to the second end of the arm. A gimbal spring is secured to the second end of the load spring member and supports the transducer member. The gimbal spring permits the transducer member to move vertically and to pitch and roll as it flies over the rotating surface of the magnetic disk. The arm, load spring member, and gimbal spring are symmetrical with respect to a straight line running from the axis of rotation of the actuator to the center of the transducer. The transducer member is a two ski head and has a magnetic read/write core secured to the trailing edge of one of the skis.

Abstract: A demand driven access mechanism comprises logic apparatus at each station capable of seizing use of the shared communication channel for enabling access by a selected single station. The logic apparatus receives status signals from all stations so that if one station seeks access to the channel it will be enabled. If two or more stations simultaneously seek access to the channel, the logic apparatus establishes a priority order between them, thereby enabling access to only one station at a time. The stations time-share the channel so that relatively slow stations may make more effective use of the relatively fast communication channel.

Abstract: Two thick film resistors calibrate the output of the feedback light detector circuit for monitoring the light power of a laser diode. The output is connected to the power control circuit for the laser diode. Calibration of the feedback output during manufacture permits replacement of the laser diode/feedback light detector combination in the field without recalibration of the power control circuit.

Abstract: Disclosed is a Reed-Solomon error correction apparatus which is programmable to perform several distinct error correction functions. The apparatus performs the following functions: encoding, error detection, syndrome generation, burst error trapping, and Chien searching.

Abstract: A magnetic read head has a first embodiment comprising an elongated magnetoresistive element having a central region and distant ends. The central region has equipotential strips disposed intermediate to its ends, and detection circuitry is electrically connected to these intermediate equipotential strips to sense the changing resistance of the central region in the presence of data magnetically recorded on a medium. In a second embodiment, the magnetoresistive element is folded into a picture frame shape and has its ends joined. The element is vertically arranged so that one of the legs of the element is positioned in proximity to a selected track of a recording medium. A pair of equipotential strips are disposed at opposite ends of the leg to define a sensing region therebetween. Detection circuitry is connected to these equipotential strips to detect the changing resistance of the sensing region in the presence of the magnetic fields of the medium.

Abstract: A disk memory assembly has a carriage structure which has a coil assembly secured to one end and is supported by bearings for rectilinear movement in response to the energization of a voice coil. The carriage has four fins, a tower member and a horizontal shoe member. The tower supports a plurality or arms carrying heads. The heads read or write upon disks rotated by a spindle about a spindle axis. A servo system is provided to energize the coil to position the heads at the desired locations on the disks. Rectilinear movement of the carriage in response to the servo excites resonances in the carriage. The carriage structure is designed to minimize low frequency resonance modes and to increase the frequency of the first major resonance mode of the carriage to improve servo control. The four fins of the carriage are orthogonally disposed with respect to one another and disposed at 45.degree. angles with respect to the spindle axis.

Abstract: A phase comparator and data separator is disclosed capable of establishing a detection window of the order of 100 percent of the clock cycle at a data recovery rate at least as great as 100 MHz. One of the preferred embodiments of the invention comprises three bistable flip-flops interconnected with OR gates to respond to a data input pulse stream and a clock pulse stream to provide, in response to each data pulse, a reference pulse having a width equal to the bit cell period and a variable pulse having a duration which is greater or less than the reference pulse duration in accordance with the direction and amount of time displacement of the input pulse from the center of the bit cell in which the input pulse occurs.

Abstract: A process for fabricating a negative pressure slider is disclosed which briefly comprises the steps of: (a) applying a dry negative photoresist layer to the surface of the slider; (b) positioning a mask having alignment marks which are too narrow to be resolved during exposure and development to pattern the photoresist layer to expose the portions of the flying surface of the slider to be milled by an ion milling process; (c) ion milling the slider wherein the patterned photoresist layer protects the flying surface of the slider while the negative pressure cavities of the slider are being milled; and (d) removing the remaining portions of the photoresist layer once the negative pressure cavities have been milled.