Starting circuit for gaseous discharge lamps

• US 4,415,837 A
• Filed: 01/18/1982
• Issued: 11/15/1983
• Est. Priority Date: 11/05/1981
• Status: Expired due to Term

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: International Telephone and Telegraph Corporation
• Inventors: Sodini, Gregory L.
• Primary Examiner(s): Dixon, Harold
• Application Number:
  US06/340,192
• Time in Patent Office: 666 Days
• Field of Search: 315/207, 315/208, 315/289, 315/276, 315/DIG. 5, 315/243, 315/177
• US Class Current: 315/177
• CPC Class Codes: H05B 41/042 using semiconductor devices
• CPC Class Codes: Y10S 315/05 Starting and operating circuit for fluorescent lamp

Abstract

A starting circuit for a high intensity discharge lamp. To provide the high voltage necessary for starting the lamp, the circuit uses a tapped transformer feeding a resistance-capacitance charging network coupled across the lamp. A voltage sensitive symmetrical switch is located in the network between the transformer tap and the RC junction to trigger the circuit when the open circuit voltage of the ballast is at its peak. A diode within the network is in series with resistance to allow current to flow during one half cycle of the cycle allowing the use of an inexpensive resistor in the RC network. A bleed resistor is placed in shunt of the capacitor to stabilize the triggering time of the network.

Claims

1. A circuit for starting and operating a high intensity discharge lamp having at least two electrodes from a source of alternating current, means coupling said lamp across said source, said coupling means comprising a transformer with its output winding in series with the lamp and a starting network connected at the output end of the transformer output winding, said starting network including a series circuit comprising a capacitive member and a resistance member in series with one another with a junction terminal therebetween, said series circuit connected across the lamp, a voltage sensitive symmetrical switch connected from said junction terminal to an intermediate tap in said transformer output winding to discharge said capacitive member through the switch and the transformer section between the tap into said transformer output winding and the output end thereof to generate a high voltage charge to said lamp when the voltage across the switch rises above a predetermined threshold starting level for the lamp, and a diode in series with the members of said series circuit for limiting the charging of said capacitive member to unidirectional current flow during alternate half cycles of said alternating current whereby to limit the starting power applied to said lamp.

2. A starting and operating circuit as claimed in claim 1 in which there is a bleeder resistor connected directly across said capacitive member to provide a bleed discharge path from said capacitive member.

3. A starting and operating circuit as claimed in claim 1 in which said starting network includes an inductor in series with the components of said series circuit.

4. A starting and operating circuit as claimed in claim 1 in which said transformer output winding includes said tapped section and another section between the tap terminal and the coupling to said source, and in which the turns ratio of said other section to said tapped section is approximately forty to one.

5. A starting and operating circuit as claimed in claim 1 in which said transformer is a reactive transformer.

6. A starting and operating circuit as claimed in claim 1 is a ferroresonant transformer.

7. A starting and operating circuit as claimed in claim 1 in which said transformer includes a primary winding across said source and said output winding comprises the secondary winding of said transformer.