Guzik Technical Enterprises

Vss Monitoring, Inc.

Ufuk Karaaslan

Nahum E Guzik

Ilia M Bokchtein

Cem Kilicci

Anatoli B Stein

Alexander Varlakhanov

James Crim

Boris Slutsky

An electronic equipment chassis assembly includes a housing, and a plurality of openings defined in the housing that allow airflow there-through. The openings include at least one intake opening defined in the front surface of the housing and at least one exit opening defined in the rear surface of the housing. The chassis also includes an air filter, and one or more rails disposed within the housing defining receiving slots that releasably secure a first plurality of circuit boards, and a second plurality of circuit boards, which second plurality of circuit boards are orthogonally oriented relative to the first plurality of circuit boards. The chassis includes an airflow assembly proximate the top surface of the housing, and one or more output fans proximate the rear surface of the housing. The airflow assembly and the output fans balance airflow throughout the chassis.

Cooling architecture for a chassis with orthogonal connector system

A read channel network of a magnetic data storage device receives analog signals representative of user data and servo data, wherein the servo data is usable to position a read/write magnetic head. The servo data is separately processed within the read channel network to improve the signal to noise ratio of the user data signal and, thereby, permit improved positioning accuracy of the read/write head within the magnetic data storage device. The servo signal applied to a multiplier along with an oscillating signal reference signal to produce a sideband signal, which is passed through a bandpass filter having a bandwidth about that of the sideband signal and having a center frequency substantially the same as that of the sideband signal. Additionally, the signal output by the bandpass filter is processed by an envelope detector, and then by an A/D converter and digital filter to produce a digital signal representative of the servo signal.

Method and apparatus for improved servo signal filtering in read channels

A magnetic head and disk tester includes a magnetic head which is selectively positioned relative to a rotatably mounted magnetic disk to accomplish testing of either of the head or disk or both. The magnetic head is secured to a carriage which is under electro-mechanical control, wherein displacement of the carriage causes a corresponding displacement of the head relative to the disk and, to some degree, may cause yaw in the carriage. Measurements of the linear position of a left and a right side of the carriage are detected, measured, and fed back to a control system. The control system responds to a difference between a desired command position and the actual position of each side of the carriage and causes actuators to adjust the position of each side of the carriage until the difference, and thereby the yaw, is substantially eliminated. Additionally, during a positioning operation, vibrations in the yaw direction are decreased, which decreases a corresponding settling time of the magnetic head.

Magnetic head and disk tester with yaw correction

A magnetic head and disk tester provides accurate positioning of a magnetic read-write head over a magnetic disk by means of a coarse positioning mechanism and a fine positioning mechanism. The coarse positioning mechanism includes a stepper motor, a lead screw, a nut, rear sliders and a housing. The fine positioning mechanism includes a piezoelectric actuator, slides and a carriage. The positioning displacements are along a linear axis, which lies on a horizontal plane. The carriage is connected to the housing via the fine positioning mechanism, which then moves the carriage with respect to the housing. Two pairs of linear encoders are mounted on the carriage about the axis and measure the position of the magnetic read-write head with respect to the magnetic disk. Each pair is mounted such that the pairs lie in separate horizontal planes. One linear encoder on each pair is mounted to the right of the magnetic read-write head and the other to the left of it, the magnetic read-write head being equal distances from the two linear encoders of each pair. The magnetic read-write head is mounted on the carriage with an offset from each pair of linear encoders in the vertical direction. Pitch during the fine positioning movement causes the head to move a different amount than that measured by any one of the pairs of linear encoders. By using both pairs of encoders, the amount of pitch is determined. A feedback circuit responsive to that determination causes the fine positioned to move the head to the correct pitch.

Magnetic head and disk tester with pitch correction

The head/disk tester of the invention has a housing 43 that houses spindle 44 that rotatingly supports a magnetic disk 31. The housing supports a moveable carriage 30 that, in turn, supports a magnetic head 32. Positioning means 39 and 41 are used to move the carriage and the magnetic head across the magnetic disk. These positioning means include stepper motors that realize coarse positioning of the magnetic head, and a piezo actuator 37 that is used for fine positioning. Linear encoders 40 and 42 located at both sides of the carriage provide feedback information to a closed-loop positioning system that controls the piezo actuator. A set of special signals ('servo bursts') pre-written at a given track of the magnetic disk is used as an additional source of feedback information for the same closed-loop positioning system. This positioning system includes a servo analyzer 45 that reads and processes servo burst signals from the magnetic disk, and a position controller 49 that controls the piezo actuator. The controller contains two control loops: a proportional-integral-derivative (PID) loop and an additional servo burst loop. During any movement of the magnetic head to a prescribed command position, the servo burst feedback is turned off, and feedback from linear encoders is used by the PID loop to move the head. When the magnetic head reaches the prescribed command position, servo burst loop is turned on; it changes the command position of the PID loop in a way to keep the ratio of pre-written burst signals constant. As a result, the position of the magnetic head with respect to the data track remains the same for as long as necessary, even in unstable temperature conditions.

Head and disk tester with a thermal drift-compensated closed-loop

An improved fine positioning mechanism in a magnetic head/disk tester includes a primary position actuator and a primary body that supports a read/write head to be tested, and an auxiliary body and auxiliary actuator. Both actuators operate contemporaneously and in mutually opposite directions. The masses of both bodies and the stiffnesses of both actuators are selected so that a ratio of the stiffness of the actuator to the mass of the body in the primary system is equal to a ratio of the stiffness of the actuator to the mass in the auxiliary system. In addition, the masses of both bodies and the expansion coefficients of both actuators are selected so that a product of the mass of the body with the expansion coefficient of the actuator in the primary system is equal to a product of the mass of the body with the expansion coefficient of the actuator in the auxiliary system. In this manner, forces operating on both bodies are equal in magnitude and opposite in direction and therefore counterbalance each other when the same control voltage is applied to both actuators. This, in turn, eliminates or reduces vibrations in the slide supporting the actuators and therefore the head-positioning settling time is significantly reduced.

Apparatus and method for improving dynamic characteristics of a

A magnetic head and disk tester which has linear encoders (40 and 42) installed on lateral sides of a carriage (30) which carries a magnetic head (34), movable in a radial direction along a hard disk. Positions of the magnetic head with respect to the hard disk are measured by means of the linear encoders which are arranged on both lateral sides of the carriage. Outputs of the encoders are supplied to an arithmetic unit (45) which calculates the arithmetic mean of the encoder's outputs and transmits the resulting signal via a feedback line (47) to a piezoelectric translator (37). The translator is the final drive element in the carriage-drive system and is used for fine positioning of the carriage. Thus, if during positioning of the magnetic head the latter is installed in an erroneous position, e.g., because of yawing which may result from asymmetrical friction on both sides of the carriage, the feedback-positioning system composed of the encoders, the arithmetic unit, and the piezoelectric translator calculates the error and shifts the carriage in a direction opposite to the error to the correct position.

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Sunnyvale, CA, United States of America

Ufuk Karaaslan