Lockheed Electronics Co., Inc.

Other

Vincent J Rizzo

William J Bigley

Harris C Rawicz

Wayne K Mans

Bigley William J

William R Buntemeyer

A ballast circuit for a gaseous discharge lamp, particularly a neon light, includes a diode bridge rectifier for producing a d-c voltage from an a-c input and a transformer with a secondary winding connected to the lamp and a primary winding connected to the rectifier. A switching circuit is connected to the transformer primary winding for controlling a flow of current therethrough from the rectifier. The switching circuit includes at least one MOSFET having a drain terminal connected to the transformer primary winding and a grounded source terminal. A control circuit is connected to a gate terminal of the MOSFET for controlling the on and off times thereof, the control circuit including a pulse generator for producing a train of pulse-width-modulated rectangular pulses of substantially a single frequency fed to the MOSFET's gate terminal. The pulse generator includes circuitry for changing the width of the rectangular pulses to enable a gradual energization of the gaseous discharge lamp from one end thereof towards an opposite end to create a writing effect of selectively different speeds in the gaseous discharge lamp. The circuitry in the pulse generator for changing the pulse width can be used to control the widths of the pulses so that the pulses are a train of square waves having a common duration equal to an interpulse period, whereby striations are generated in the gaseous discharge lamp.

Ballast circuit for gaseous discharge lamp

An improved electronic control system employs a primary servomechanism loop which includes an error signalling difference node and a stability compensating forward gain/drive element intermediate an input command signal source and a controlled output element. A second, similar image feed back loop is operative upon a simulated representation of the controlled output element or plant, and is exercised by the input command source. The error node in the second image loop generates a loop error signal responsive to the difference between the input command and the simulated, predicted response for the controlled element. In accordance with the present invention, the two error signals produced by the actual and image feed back loops are compared and generate a supplementary feed back signal which is summed with the plant-driving signal applied to the controlled element. Accordingly, the structure above considered operates to vitiate any difference between the error signals in the actual and image loops, thereby forcing the response of the controlled element to track the desired, predicted response therefor in the image loop notwithstanding any degredation experienced by the controlled plant.

Electronic controller apparatus

Load actuating servomechanism apparatus includes dynamic regeneration to equalize and overcome a frequency-varying load/load drive train mechanical resonance. The drive circuitry comprises a per se conventional primary motor speed controlling rate feedback loop including a cascaded rate signal command source, summing error-signal producing node, and loop frequency response shaping filter and driver amplifier for exciting a load driving motor, and a rate tachometer signal feedback element connecting a measure of the motor output speed to a subtractive input of the summing node. To broaden the response band of the primary feedback circuit and accommodate a mechanical resonance otherwise interfering therewith, a secondary, positive feedback path supplements the input rate command with a signal dependent upon motor current, and thus upon motor load. Accordingly, output load drive automatically increases as motor current increases when a load drive retarding mechanical resonance is encountered.

Load actuating servomechanism with resonance equalization

Load actuating servomechanism apparatus includes dynamic regeneration and a mechanically damped motor-load coupling to equalize and overcome a frequency-varying load/load drive train mechanical resonance. The drive circuitry comprises a per se conventional primary motor speed controlling rate feedback loop including a cascaded rate signal command source, summing error-signal producing node, and loop frequency response shaping filter and driver amplifier for exciting a load driving motor, and a rate tachometer signal feedback element connecting a measure of the motor output speed to a subtractive input of the summing node. To broaden the response band of the primary feedback circuit and accommodate a mechanical resonance otherwise interfering therewith, a secondary, positive feedback path supplements the input rate command with a signal dependent upon motor current, and thus upon motor load. Accordingly, output load drive automatically increases as motor current increases when a load drive retarding mechanical resonance is encountered. Further, the mechanical damping, for example implemented by a slip clutch, lowers the effective Q of the resonance, thereby facilitating load actuation.

Load driving apparatus

A rate-control servomechanism includes a load driving motor and a tachometer mounted on the motor shaft to produce a feedback signal hich corresponds to the rotational speed of the motor. An additional signal corresponding to the motor current is added to the tachometer feedback signal to compensate for the resonance-like effects resulting from the inductive coupling between the motor and tachometer windings.

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Basking Ridge, NJ, United States of America

Vincent J Rizzo