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: An equipment module for holding printed circuit boards. The equipment module contains pin and slot combinations which permit it to be lifted from a casing and tilted for efficient access to the printed circuit boards for maintenance. The pin and slot combinations comprise a plurality of slots molded into the sides of the equipment module for cooperation with pins mounted on the casing.

Abstract: A mechanism for receiving, cradling, and loading, under force, a disk drive cartridge onto the drives spindle is disclosed. The mechanism has an U-shaped cradle, a transverse yoke, and a centrally mounted nub for applying downward pressure on the cartridge. A lever, actuated by motion of the drive's door, moves the cradle/yoke combination in the vertical direction.

Abstract: A workpiece carrier includes a flat support surface to which a workpiece is attached by bonding. The carrier includes means for bending the carrier support surface so that it becomes concave. When dealing with a relatively flexible workpiece, one can cause the workpiece's surface to be machined to attain a convex shape by bending the support surface of the carrier concavely, and then bonding the workpiece attachment surface to the carrier while the carrier support surface is concavely bent. Allowing the carrier's support surface to assume a less concave shape then imparts a convex shape to the surface of the workpiece to be machined.

Abstract: A dual channel read recovery system having a high resolution channel and a low resolution channel and logic for recovering digital information from the high and low resolution signals from the channels, is improved by the inclusion of a variable delay in the low resolution channel. The variable delay is responsive to the high and low resolution signals to more closely match the delays in both channels.

Abstract: A method is disclosed for verifying the integrity of servo data stored as a series of parallel servo tracks on a disk. Each track includes automatic gain control data and servo positioning data. The peak amplitudes of the automatic gain control pulses on a first track determine a first effective threshold or AGC gain level. The first threshold level is then shifted to a higher, enhanced threshold level. Servo data pulses from a second track are then detected, based on the enhanced threshold level and the AGC gain level of the first track. Should these servo data pulses not be fully detected, an error is recorded for the second servo track.

Abstract: A quarterwave retarder prism such as can be used in optical recording has a shape similar to a dove prism, and has three internal reflections, with the retarder prism designed to have the emerging light beam on the same axis or collinear with the entering light beam such that the accumulated phase retardation in the device is one quarterwave over a wide range of wavelengths of light.

Abstract: A process for producing high precision apertures in plastic components comprises the steps of: injection molding the component from a crystalline or semicrystalline thermoplastic material wherein at least one aperture is formed in the component during the molding step; inserting an annealing rod having an oversized diameter with respect to the aperture into the aperture; placing the component, with the annealing rod inserted into the aperture, into an oven at an elevated temperature for a period of time; allowing the component to cool; and withdrawing the annealing rod from the aperture of the component.

Abstract: A simplified power on/off protect circuit is provided to enable logic above a predetermined power supply voltage level and disable the logic below such predetermined voltage level. The circuit comprises a zener diode in combination with a transistor such that the zener controls the voltage level at which the transistor turns on. The transistor enables the logic.

Abstract: A system and method of accurately locating the center of a previously recorded magnetic track on a rotating magnetic storage disk and moving a transducer to the center of the track. The system measures in increments the amplitude of the feedback signal as the transducer is moved to each side of the recorded track and compares the signal amplitude measured with a predetermined reference level. Through the use of an offset measuring system connected to a computer processor the number of increments moved in each direction is recorded and a simple calculation is made to determine the center of the magnetic track. The transducer for recording and replaying information on the disk is then moved to the center of the track.

Abstract: A method for use with an article of manufacture allows great accuracy in machining the edge of a face on a prism to a predetermined position respective a feature carried on the face and formed by deposition of insulating material. The preferred application for this invention is in accurately machining the transducing surface of a disk memory transducer assembly so that the throat height of the thin-film head carried on an end face of the assembly has a precise value.

Abstract: A carriage assembly has a carriage frame which supports a transducer for reading and/or writing on a recording medium. The carriage frame is slideably supported upon support members for rectilinear movement with respect to the recording medium. The carriage assembly includes an auxiliary mass slideably supported upon a support rod of a support framework secured to the carriage frame. The auxiliary mass is slideably mounted on the support rod between elastomeric spring dampers disposed at opposite ends of the mass. The carriage assemby is driven by a flexible band which is secured at its ends to the carriage frame and is in wrapped engagement with the drive shaft of a stepper motor. The drive force of the motor is applied to the carriage assembly along a drive axis. The effect of the auxiliary mass and mass support framework is to align the drive axis with the center of mass of the carriage assembly in order to damp carriage vibrations and improve transducer/track alignment.

Abstract: A diskette picker for gripping a magnetic data storage disk and retracting it from a disk storage housing and releasing the disk for loading onto a disk drive. The picker also returning the disk to the disk storage housing after the disk has been used. The picker automatically grips an edge of the disk when removing the disk from the storage housing and automatically releases the disk while loading the disk on a disk drive.

Abstract: In an optical recording system for both reading and writing, the laser beam is projected to the media through a diffraction grating which generates a plus one and minus one order beam ahead of and behind the main zero order beam. The grating is driven by an oscillating driver so as to wobble in a fashion which leaves the zero order beam unaffected but causes the plus one and minus one order beams to move inwardly and outwardly, radially, with respect to the information track on the media in opposite fashions. The wobbling plus one and minus one order beams are used to generate differential signals from separate detectors and are passed through a band pass filter to generate a radial position error signal which may be used to drive the write/read head inwardly or outwardly to remain positioned over a particular information track.

Abstract: A workpiece carrier has a support bar centrally supported at one end of a stem portion. The stem is carried at its opposite end on a base. Columns are interposed between the ends of the support bar and the base. Heat is applied to the columns, preferably by resistive heating elements, to heat them and cause their thermal expansion, causing the support bar ends to be bent away from the base. A relatively flexible workpiece which has been bonded to the support arms on a surface facing away from the base will undergo the same bend.

Abstract: In an optical recording system, a media disk for writing information has a plurality of information tracks with preformatted clock location indications written on the tracks. Writing is accomplished by making a written indication at a predetermined location between preformatted clock locations where the predetermined location is representative of the particular data to be written. Proper location of the preformatted clock location indicia on adjacent tracks provides for proper track crossing information when track addressing occurs as well as proper address location on particular tracks.

Abstract: A focus initialization system is provided for optical data recording of the type in which an objective lens relatively near to the optical recording media is moved back and forth in comparatively small excursions to maintain focus for the read beam and write beam on the media. This system initializes or loads a conventional focusing system by starting the objective lens at a position at the far end of its travel limit, preferably, with the objective lens furthest from the optical media. The objective lens moves slowly towards the optical media while the system operates to detect when a near focus condition exists. Known focusing detection systems produce a bipolar output voltage having a peak on either side of the exact focus point when a near to focus condition is achieved. The present system detects when the objective lens is at a near to focus condition in the range between bipolar voltage peaks on either side of the focused point.

Abstract: Focus sensing using a light detector array is accomplished in an optical recording system using the light beam returned from the recording media through the objective focusing lens by passing the beam through a spherical focusing lens using a mask such as a knife edge which only passes a portion of the beam to the light detector array. The light detector array is matched to the mask and detects the different partial image patterns formed as a result of the close to focus condition with the recording media too far away from the objective lens and the near to focus condition with the media too close to the objective lens. In the focused condition, the light detector array receives a comparatively fine focused spot of light. Alternative embodiments of the present invention may use a cylindrical lens which in the focused condition creates a longitudinal bar of light.

Abstract: A desired feature of deposition material is produced on a substrate by forming an adhesion inhibitor on the substrate in a pattern whose inner edges are adjacent the bounds of the feature being produced. A seedlayer is deposited over the adhesion inhibitor and exposed portions of the substrate, and a mask is formed over the seedlayer adjacent the edges of the adhesion inhibitor, the inner edges of the mask defining the feature being produced. A deposition material is deposited over the exposed seedlayer, and the mask is removed. Unwanted portions of the seedlayer and deposition layer are removed by mechanically lifting off. The adhesion inhibitor serves to inhibit the bonding of the seedlayer to the substrate sufficiently to enable the mechanical lift-off. The adhesion inhibitor is removed, either by lifting off with the seedlayer and deposition layer, or subsequently.

Abstract: A mechanism is disclosed for receiving a disk cartridge and guiding the cartridge to an operating position within a disk drive, and for subsequently ejecting the cartridge when its use is complete, all responsive to the opening and closing of the disk drive door. The mechanism for ejecting the cartridge also automatically opens a transducer head access door when the cartridge is inserted into the receiver, and automatically closes the door upon cartridge ejection. Improvements are also disclosed in the manner of mounting a lift collar designed to support the disk and hub within a cartridge, and for an improved method of adjusting the cartridge to operate alternatively in write protect and write enable modes.