Abstract: Shown is a disk drive arrangement with servo-mechanism for controlling (thin-film) head position, etc.; the servo having a disk face dedicated to servo tracks, rendered in "Quad" code, with special timing indicia to separate position indicia, with position signals being deployed to follow, and to be terminated by, like, distinct timing sequences.

Abstract: Seek drive forces coupled between head actuators in a magnetic disk storage system employing separately controllable head actuators are prevented from affecting reliable head actuator operation. For this purpose a compensating signal is derived proportional to the driving current employed in performing an actuator seek operation. This compensating signal is fed forward into the drive circuit of the other actuator so as to cause this other actuator to begin moving its heads in a direction opposite to that which would be caused by the later arriving coupled drive forces, thereby making it possible to prevent driving forces coupled between actuators from deleteriously interferring with reliable actuator operation.

Abstract: Damaging head crashes are prevented in a disk drive system by providing a specially chosen RC network between the head position control servo and the head actuator. The values of the RC network are chosen in conjunction with the servo output voltage so that, without detracting from head access time, the maximum head velocity will be limited to a value which will prevent damaging head crashes even when a fault occurs in the system.

Abstract: A system for rotating a data storage disc in a disc drive and for rapidly bringing the disc to a halt comprises a brushless motor fed with direct current in its windings by a motor drive circuit which current is also fed to a solenoid to hold a spring loaded solenoid arm from pressing a brake against a shaft to brake the disc, the motor control circuit using the current caused by back emf in the windings of the motor to provide motor braking while passing the current through the solenoid which applies the brake when the motor speed falls below a predetermined limit, the solenoid also being employed as a current smoothing choke.

Abstract: A servomechanism avoids load-damaging conditions by being shut down whenever a power-amplifier saturation detector fails to detect a change in the saturation state of the power amplifier in response to the periodic and momentary replacement of the demand signal by one or other of two test signals, which of the two test signals is selected being dependent upon the expected direction of possible saturation of the power amplifier and the polarity of both test signals being the same as the polarity of the applied demand signal.

Abstract: A reel-to-reel tape drive system is disclosed in which primary control signals are applied to motors to drive both the payout and takeup reels and in which secondary control signals are provided to first and second torque driving circuits which, responsive to the secondary control signals, continuously provide first and second tensioning control signals to the first and second reel motors respectively. The first and second tensioning control signals operate to activate the first and second reel motors to take up slack and provide tension in the tape when the first and second reel motors are not receiving primary control signals. Thus, slack is taken up when the reels are stopped and adequate tension is supplied prior to restart, enhancing starting and stopping performance of the tape transport mechanism.

Abstract: A control unit for a six-pulse reversing (two-quadrant) thyristor converter is disclosed. More particularly, a first integrator is provided for generating a sawtooth voltage for controlling the thyristors associated with all negative half-waves of the applied phase voltage, and a second integrator is provided for generating a sawtooth voltage for controlling the thyristors associated with all positive half-waves of the phase voltages. Additionally, an evaluation circuit is provided which is responsive to the zero crossings and polarities of the phase voltages and which controls the integrations of the integrators so that they start and end above and below respective first and second predetermined limits.

Abstract: A control unit for the thyristors of a cycloconverter is disclosed. The thyristors are supplied by a three phase network and the control unit is also responsive to such network. In particular, in the control unit a measuring voltage is derived from a phase voltage, and phase-shift means and smoothing means are provided to shift the phase of the measuring voltage so that its zero crossing is in the vicinity of the zero crossing of a phase voltage. The phase-shifted measuring voltage is then fed to a sawtooth integrator which generates a sawtooth voltage in dependence on the zero crossing of the applied phase-shifted measuring voltage. The sawtooth voltage is then used to generate firing commands for the thyristors.