Abstract: An automated system for lapping thin film magnetic heads comprises a lapping fixture positioned in apposition to a rotary lapping plate. A ceramic bar, on which the magnetic heads are deposited and from which air bearing head sliders are fabricated, is attached to an adjustable transfer tool that is secured to a bow yoke holder. The holder is fixed securely on the lapping fixture so that the air bearing surface of the magnetic heads face the surface of the lapping plate. During the lapping process, digital data signals are obtained representative of throat height level of selected heads spaced along the bar. The signals are calibrated and processed by a computer which provides command signals for varying lapping pressure, changing direction of row bow, shifting a weight to achieve proportional lapping along the bar, changing the lapping process to a fine polishing step and forming tapers on the rails of the head sliders.

Abstract: A compact disk drive includes a rotary head actuator or voice coil motor for a head arm assembly formed with flexures. The baseplate for the drive is formed with recesses to contain the voice coil motor and a lower flexure whereby the depth of the drive is reduced. The magnet housing for the voice coil motor is contoured and located in a corner of the baseplate, and the head arms are oriented so that the length of the drive is reduced.

Abstract: The output stage of a differential operational amplifier includes a source follower amplifier and a common source amplifier which are driven by two complementary outputs of a differential input stage. Continuous-time feedback circuits are provided to set the quiescent biasing conditions accurately. The differential operational amplifier has a low output impedance and a large output voltage swing with negligible open loop gain degradation when the size of the load resistance is varied. Floating compensation capacitors reduce the total capacitor value and the physical area needed for the operational amplifier.

Abstract: An axial gap motor for use in a disk drive includes a rotatable magnet rotor and fixed first and second windings closely spaced from the rotor. The rotor and windings are disposed coaxially about a rotatable spindle to which the rotor is mounted. Current supplied to one winding actuates the rotor to rotate in a run mode. Current supplied to the other winding positions the rotor for maximum torque for starting the motor, and enables the sensing of the speed of the rotating rotor.

Abstract: An adjustable transfer tool is used to compensate for row bow during lapping a bar or a row of magnetic head sliders. The adjustable transfer tool enables establishing uniform and substantially precise throat heights for a multiplicity of thin film transducers disposed on said sliders. To allow the desired adjustment, the transfer tool incorporates slot means by which the shape of the surface of the tool on which the bar of sliders is mounted can be modified so that the slider transducers assume a collinear array across its entire length for the lapping process. Adjustment is accomplished by manual means, such as by a screw or a tapered pipe plug, or by electrical means, such as a piezoelectric actuator, in conjunction with a computer or microprocessor.

Abstract: An alignment tool for preparing through holes in a door to enable mounting a lock assembly includes a slidable bracket for securely positioning the tool in the mortise at the edge of the door. An angle element is connected to the bracket and to a support plate, which is perpendicularly disposed relative to the bracket. The support plate is formed with precisely positioned guide holes that indicates to the door installer exactly where the through holes are to be made.

Abstract: A data collection system useful for trade shows employs identification cards each having a semiconductor memory chip for recording and storing data relating to individual attendees. The system includes an encoder/decoder that is coupled between a keyboard and a computer. The encoder/decoder accepts the memory cards for recording the data generated at the keyboard and for reading the recorded data at a later time.

Abstract: An exponential analog-to-digital converter comprises two gain stages, each of which includes a binary-weighted capacitor array. The capacitors are switched in succession to multiply the gain of a sampled analog input signal, while a counter counts down for each switching step from an initial setting of binary 111. When the gain signal has a value outside a predetermined reference voltage range, a 3-bit binary digital word representative of the analog input signal sample is registered in the counter. If the gain signal produced after all the capacitors have been switched in to provide the maximum gain does not fall outside the reference range, then the binary word stored in the counter for the sample of the analog signal is 000.