Abstract:
A method is disclosed for operating a magnetic tape drive. The tape drive includes a plurality of DC motors, each having a plurality of Hall sensors, and each under the control of a servo system which is configured to read location information from the magnetic tape. The servo system computes a primary tape velocity from location information, and senses a secondary and tertiary velocity signal and computes a tape velocity based on these. If the primary velocity location information is available this is used, if not then one of the secondary or tertiary velocity signals is used. The secondary velocity signal is employed when an absolute value of a term related to tape velocity is less than a predetermined value, and the tertiary velocity signal is used when it is greater than the predetermined value.
Abstract:
A system is provided for creating sound represented by the varying width of a motion picture film soundtrack, which provides a 'flat' frequency response up to 12.5 kHz with maximum phase coherence, even though the film speed is only 62 % to 78 % of the present speed of 90 feet per minute (27 meters per minute). The projector photocell which detects a slit-shaped area of light passing throug the soundtrack, produces an output that is amplifed so the amplification is progressively greater at higher frequencies, with the gain at 12.5 kHz being at least 6 dB greater than at 1 kHz. A photocell is selected whose output at 12.5 kHz is within 1 dB of its output at 1 kHz for light of a wavelength of substantially 1000 nanometers.
Abstract:
A tape drive comprising: first and second motors (3b, 4b); first and second spool supports (3a, 4a), respectively receiving first and second spools of tape (3, 4), the first spool support (3a) being driveable by the first motor (3b) and the second spool support (4a) being drivable by the second motor (4b); a sensor (5a) arranged to provide a signal indicative of linear movement of tape (2) between the tape spools along a predetermined tape path; a controller (9) arranged to control energization of said first and second motors (3b, 4b) for transport of the tape in at least one direction between the first and second spools of tape along the predetermined tape path; wherein the controller is arranged to generate data indicating the diameter of said first and second spools of tape based upon said signal provided by the sensor and data indicating rotation of each of said first and second spools.
Abstract:
A sequential data storage medium, comprising a sequence of plurality of servo patterns that provide lateral position information and longitudinal position information, wherein each of the plurality of servo patterns comprises a first burst comprising a first plurality of pulses, a second burst comprising a second plurality of pulses, a third burst comprising a third plurality of pulses, and a fourth burst comprising a fourth plurality of pulses. The spacings between the first plurality of pulses, in combination with the spacings between the second plurality of pulses, encode a first bit without affecting the recovery of lateral position information. The spacings between the third plurality of pulses, in combination with the spacings between the fourth plurality of pulses, encode a second bit without affecting the recovery of lateral position information. The sequence of plurality of servo patterns comprises a sequence of the first bits and a sequence of the second bits to form an error-correction codeword providing error-correction capability.
Abstract:
A voice coil motor (VCM) driver (28) has four field effect transistors (90, 94, 98, 104) connected to a motor coil (24) as an H-bridge (Viso). A sense resistor (R5) in series with the coil (24) and the H-bridge (Viso) senses coil current. A feedback amplifier (62) provides a feedback signal from a voltage developed across the sense resistor (R5). A summing junction sums current command signals with the feedback signal. A transconductance loop compensation amplifier (56) has an inverting input connected to the summing junction, has a non-inverting input connected to a reference level, and has an output control signal node. The control level is connected to control linear transconductance differential driver amplifiers (56) including the four field effect transistors during a linear drive mode. A pulse width modulation (PWM) generator (72) connected to the output control level during a PWM drive mode applies the pulses to a first one of the four field effect transistors, and a polarity control circuit (86) responds to a driving current direction signal by controlling another one of the four field effect transistors during the PWM drive mode.
Abstract:
A method and system for outputting and reproducing information representing a digital image alleviates system bus bottlenecks by downloading image information from the RAM (Figure 2, 230) to an Application Specific Integrated Circuit (ASIC) (Figure 2, 280), download controlled by the ASIC (Figure 2, 280), and allowing the ASIC (Figure 2, 280) to directly interface with and directly control the operation of an output device (Figure 2, 250). The ASIC (Figure 2, 280) and the output device (Figure 2, 250) are directly connected thereto via a dedicated bus (Figure 2, 290). While the ASIC (Figure 2, 280) downloading image information from the RAM (Figure 2, 230), the system processor (Figure 2, 210) performs calculations needed from certain portions of the image prior to output and reproduction.
Abstract:
A drive unit comprising a drive means which switches the number of turns of coils of phases of a motor having a plurality of phases to drive the motor in a first mode by using all the coils of each phase or to drive the motor in a second mode by using the number of turns of the coils fewer than that of the first mode, a power source voltage detecting means for detecting a power source voltage supplied to the drive means, a temperature detecting means for detecting the ambient temperature in which the motor is used, and a control means for switching the drive means so as to drive the motor in either the first mode or the second mode based upon the result of detection from the power source voltage detecting means or the result of detection from the temperature detecting means, thus making it possible to save the consumption of electric power while maintaining the revolution of the motor constant.
Abstract:
A method for in-drive monitoring of stiction in a hard disk drive and corresponding improved hard disk drive are provided. Stiction is monitored by measuring starting current of the spindle motor of the drive without having to remove the printed circuit board of the disk drive, open the disk drive, or remove the drive from a given test environment. The method includes steps of initializing the motor driver control chip (step 200), initializing the motor (step 202), determining an initial disk position (step 204), applying an initial current (step 206) and determining if the disk position has changed (step 208 and 210). If the disk position has not changed, then the method applies a next higher current (step 212) to the spindle motor, wherein the method repeatedly increases the current until the disk position changes (step 208, 210 and 212). The last applied current which caused the disk position to change becomes the starting current (step 208, 210, 212 and 214). The method is implemented as an on-board electronic torque meter (ETM) by integrating specialized firmware with the motor driver control chip, to produce an improved hard disk drive.