# Patent

## Title
Protective shield and visor supporting same

## Abstract

While the system and ballast have been described and illustrated with many modifications and embodiments, those skilled in the art will recognize that further modifications and embodiments may be made within the ambit of the disclosure and claims without departing from the principles of the invention disclosed.

## Background
## Claims

1. An electrical system for supplying a high frequency AC voltage to gas discharge lamps, said system comprising: terminals, said inverter means coupled to the output of said rectifier means for converting said rectified DC voltage appearing across said pair of input terminals to a high frequency AC voltage across said pair of output terminals, said inverter means comprising: each of said transistors having a base, collector and emitter, the emitters of said transistors connected to one of said pair of input terminals, having first and second series-connected inductive windings respectively connected to the output terminals and connected with the collectors of said transistors, a .[.feed back.]. .Iadd.feedback .Iaddend.winding connecting the bases of said transistors, terminals and a junction point intermediate said first and second inductive windings for limiting the current in the collectors of said first and second transistors during the time period of simultaneous conduction of said transistors, and winding for increasing the switching .Iadd.speed .Iaddend.of said first and second transistors by decreasing base current of the transistor that is turning off and increasing base current of the transistor that is turning on; and terminals of said inverter means.

2. An electrical system for supplying a high frequency AC voltage to gas discharge lamps, said system comprising: terminals, said inverter means coupled to the output of said rectifier means for converting said rectified DC voltage appearing across said pair of input terminals to a high frequency AC voltage across said pair of output terminals, said inverter means comprising: each of said transistors having a base, collector and emitter, the emitters of said transistors connected to one of said pair of input terminals, series between the collectors of said transistors, a first feedback loop winding connecting the bases of said first and second transistors, and a second feedback loop winding connected by way of a pair of forward diodes to the base of each of said transistors, and terminals and a junction point intermediate said pair of primary windings for limiting the collector current of said first and second transistors during the time period of simultaneous conduction of said transistors; and terminals of said inverter means.

3. The system as claimed in claim 2 further comprising a combination of a third winding in series with a resistor, said third winding-resistor combination being connected between one of the input terminals and an intermediate point of said second feedback loop winding. .Iadd.

4.  A high frequency AC lighting system for gas discharge lamps comprising: lamps, each said fixture being distributed throughout an area which is to be lighted by said lamps; voltage and phase; power for distribution from said one or more subcenters to said plurality of lighting fixtures; subcenters to said fixtures; and terminals thereof and inverting said DC into high frequency AC at output terminals thereof, each of said inverting means being located at one of said fixtures, and being electrically connected at said output terminals to a plurality of said lamps, and each said inverting means comprising a semiconductor switching means in electrical connection with a transformer. .Iaddend. .Iadd.

5.  A system as set forth in claim 4 in which each said fixture comprises a ballast means electrically connected to said lamps held in said fixture, and in which each said inverting means is electrically connected to said ballast means of its own and a plurality of adjacent fixtures. .Iaddend. .Iadd.6. A system as set forth in claim 5 in which each said inverting means is connected to one or more ballast means of adjacent fixtures by two load-carrying wires. .Iaddend. .Iadd.7.  A system as set forth in claims 5 or 6 in which said ballast means comprises an inductor. .Iaddend. .Iadd.8. A system as set forth in claims 5 or 6 in which said ballast means comprises a capacitor. .Iadd.9. A system as set forth in claims 5 or 6 in which said ballast means comprises an inductor and a capacitor. .Iaddend. .Iadd.10. A system as set forth in claims 5 or 6 in which each said inverter means further comprises a pair of transistors in push-pull connection with a collector transformer. .Iaddend. .Iadd.11.  A system as set forth in claim 10 in which each said fixture holds at least one gas discharge lamp comprising one or more filaments, and in which each said inverter means further comprises heater windings on said transformer, said heater windings being adapted to make electrical connection with said filaments of one or more said lamps. .Iaddend. .Iadd.12. A system as set forth in claim 11 in which said means for electrically connecting said output terminals of said inverter means comprises a separate magnetic core transformer and wherein said heater windings derive induction from said separate magnetic core. .Iaddend. .Iadd.13. A system as set forth in claim 4 further comprising energy-saving transformer means for deriving lamp filament voltage from, and proportional to, lamp arc voltage so as to reduce lamp filament power after arc voltage drops as said lamps turn fully on. .Iaddend. .Iadd.14.  A system as set forth in claim 4 in which each said fixture holds at least one of said gas discharge lamps and each lamp comprises a filament, and in which each said inverting means is situated in a first fixture and is electrically connected to a second fixture, said second fixture comprising transformer means for heating the filament of each lamp in said second fixture, and said second fixture further comprising ballast means for each lamp in said second fixture. .Iaddend. .Iadd.15. A system as set forth in claim 4 in which the DC is delivered to each said inverting means by a two-wire circuit. .Iaddend. .Iadd.16. A system as set forth in claim 4 in which the DC is delivered to each said inverting means by a balanced three-wire circuit. .Iaddend. .Iadd.17.  A system as set forth in claim 4 further comprising voltage transforming means for inputting said AC power to said rectifying means, and said voltage transforming means also comprising means for transforming said commercial AC to proper voltage for conventional AC facilities comprising at least one of (a) single phase output terminals, (b) three phase output terminals, and (c) six phase output terminals. .Iaddend. .Iadd.18.  A high frequency AC lighting system system for gas discharge lamps comprising: voltage and phase; for distribution from said one or more subcenters; lamps each comprising one or more filaments; subcenters to said fixtures; said DC power at input terminals thereof and inverting said DC into high frequency AC at output terminals thereof for connection to said lamp, said inverting means comprising a semiconductor switching means in electrical connection with a transformer; and least one said lamp, for deriving lamp filament voltage from, and proportional to, lamp arc voltage so as to reduce lamp filament power after arc voltage drops as said lamp turns fully on. .Iaddend.