Abstract: A magnetic tape drive having a motor with a magnetically shielded cavity or hole in one cover of the motor providing additional room for movement of a magnetic head. The cavity eliminates a mechanical interference problem, enabling direct drive of a roller (puck) combined with short overall drive height. In motors having an internal stator, some of the stator poles are eliminated and a magnetically shielded cavity is provided in the area where the stator poles are eliminated. In motors having an external stator, no stator modification is required and a shielded cavity provides access into an open area of the rotor. In addition, for motors having an external stator and sufficient magnetic shielding, a simple hole in one cover of the motor may be sufficient rather than a magnetically shielded cavity.

Abstract: A method for reliably measuring preformatted servo patterns, on a magnetic tape, for positioning a magnetic head. The tape has constant frequency stripes marking servo pattern areas. The drive reading the preformatted tape has a read channel amplifier with automatic gain control (AGC). When a stripe is detected, AGC is enabled. Before leaving a stripe, AGC is placed on hold. The amplitudes of two servo bursts are then measured with a gain that has been calibrated by a signal from a stripe. During the time AGC is enabled, the amplifier peak output is limited to less than half the maximum amplifier peak output. The servo pattern signal amplitude is about twice the signal amplitude of a stripe, so that servo patterns are measured with almost the maximum signal-to-noise ratio. When a stripe is detected, a counter counts pulses resulting from the stripe signal, for a fixed time, to ensure that the stripe detection is valid.

Abstract: A system and method for reducing non-repeatable positioning errors. Non-repeatable positioning errors caused by the effects stiction and backlash in the mechanical system are reduced by "shaking" or vibrating the positioning system in a controlled manner. After the system input is set to the desired value, the positioning system is "shaken" by inputting a series of offsets that oscillate around the desired location and gradually decrease in amplitude, eventually reaching zero. In a specific embodiment, a lead screw is threaded through a follower nut which is connected to a magnetic tape read/write head. The lead screw is rotated by a mechanical transmission which provides gear reduction from a computer controlled stepper motor. The tape head's non-repeatable positioning error is reduced by alternately stepping the stepper motor in opposite directions a specified number of steps and periodically reducing the specified number of steps until zero is eventually reached.

Abstract: A tape guide for a digital tape mini-cartridge providing decreased tape wander in a direction transverse to the intended path. The guide provides an increased area of tape having increased transverse stiffness without interfering with an adjacent drive wheel. In one embodiment, the guide is cylindrical and has a cylindrical cut-out to provide clearance for an adjacent cylindrical drive wheel. Preferably, the guide has top and bottom flanges. If a top flange of the guide is present, the cut-out continues through the top flange of the guide. The top flange of the guide may be relatively thin to fit below a top flange of the adjacent drive wheel. Alternatively, the top flange of the guide may have a larger cut-out to avoid interference with the top flange.

Abstract: A magnetic tape drive having a motor with a magnetically shielded cavity or hole in one cover of the motor providing additional room for movement of a magnetic head. The cavity eliminates a mechanical interference problem, enabling direct drive of a roller (puck) combined with short overall drive height. In motors having an internal stator, some of the stator poles are eliminated and a magnetically shielded cavity is provided in the area where the stator poles are eliminated. In motors having an external stator, no stator modification is required and a shielded cavity provides access into an open area of the rotor. In addition, for motors having an external stator and sufficient magnetic shielding, a simple hole in one cover of the motor may be sufficient rather than a magnetically shielded cavity.

Abstract: A position sensor for providing an electronic output indicating the magnitude of transverse movement of an edge of a magnetic tape. A first light pipe and lens arrangement is used to deliver light to one side of a tape. A second light pipe with a small light receiving aperture is used to receive light and to deliver the received light to a detector. The focal point for the lens in the first light pipe is at the receiving aperture of the second light pipe, enabling the aperture to be very small but still receive substantially all the transmitted light. The light pipe arrangement enables use of a variety of light sources and light detectors without having to place either a source or a detector physically close to the tape or the magnetic head.

Abstract: A magnetic read channel employs an artificial neural network for reconstruction of a recorded magnetic signal and its corresponding synchronization signal. A magnetic read head receives magnetic signals from a magnetic recording media such as a magnetic tape or disk and converts it to an electronic signal. A preamplifier receives and amplifies the electronic signal from the magnetic read head to produce an amplified electronic signal. A delay line receives the amplified electronic signal from the preamplifier, storing delayed successive representations of the received signal. An artificial neural network receives the delayed successive representations from the delay line for reconstruction of the originally recorded data signal. Prior to use in an application, the artificial neural network is trained via a training method with a known training set of corresponding simultaneously generated data and clock pairs.

Abstract: A tape guide for a digital tape mini-cartridge providing decreased tape wander in a direction transverse to the intended path. The guide provides an increased area of tape having increased transverse stiffness without interfering with an adjacent drive wheel. In one embodiment, the guide is cylindrical and has a cylindrical cut-out to provide clearance for an adjacent cylindrical drive wheel. Preferably, the guide has top and bottom flanges. If a top flange of the guide is present, the cut-out continues through the top flange of the guide. The top flange of the guide may be relatively thin to fit below a top flange of the adjacent drive wheel. Alternatively, the top flange of the guide may have a larger cut-out to avoid interference with the top flange.

Abstract: A system and method for calibrating amplifier gain and a comparator threshold for use in verification of magnetic media integrity in a magnetic data storage device. Commercially available read data processors are used which have an amplifier with controllable gain and a comparator with an internal indirectly-controllable threshold. An on-board voltage reference is provided for gain calibration. The calibrated gain is used to provide signals with known peak values for calibrating the comparator threshold. In one embodiment, the numeric control value for the threshold is reduced from a calibrated peak value to a specified fraction for media verification. In a second embodiment, the gain is reduced to the industry specified fraction and the threshold is calibrated to match peak signal magnitudes at the reduced gain. The gain is then returned to the calibrated level for media verification.