Filment switch for a lamp ballast
First Claim
1. A switching circuit for a rapid start type fluorescent lamp having a filament operating from a ballast transformer which supplies voltage to the filament and operating voltage to the lamp comprising a triggered switch in series with a lamp filament, voltage sensitive means connected to sense the voltage across the lamp, the triggered switch being connected to the voltage sensitive means and operated by the voltage sensitive means so that the triggered switch is on and the filament is supplied voltage from the ballast when the lamp arc is not struck and is essentially off when the voltage across the lamp drops after the lamp arc is struck to remove the voltage to the filament.
7 Assignments
0 Petitions
Accused Products
Abstract
A filament switch for a rapid start fluorescent lamp disconnects or reduces through phase modulation the heating current to a plurality of lamp filaments to save power. The switch uses a trigger in series with a voltage sensitive element and an impedance element, the switch being responsive to the difference between a lamp starting voltage and a lamp sustaining voltage for determining when and for how long the filaments are heated.
8 Citations
18 Claims
- 1. A switching circuit for a rapid start type fluorescent lamp having a filament operating from a ballast transformer which supplies voltage to the filament and operating voltage to the lamp comprising a triggered switch in series with a lamp filament, voltage sensitive means connected to sense the voltage across the lamp, the triggered switch being connected to the voltage sensitive means and operated by the voltage sensitive means so that the triggered switch is on and the filament is supplied voltage from the ballast when the lamp arc is not struck and is essentially off when the voltage across the lamp drops after the lamp arc is struck to remove the voltage to the filament.
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5. A multilamp circuit for rapid start type fluorescent lamps having respective filaments operating from a ballast transformer which supplies voltage to the filaments and operating voltage to the lamps:
- filament switch means for connection between the ballast transformer and to the lamps, said filament switch means comprising a triggered switch in series with a filament of each lamp operated by the ballast, voltage sensitive means connected to sense the voltage across each lamp operated by the ballast, the triggered switch being connected to the voltage sensitive means to be operated thereby, said voltage sensitive means operating the triggered switch means of the individual lamps in sequence so that the triggered switch means of a lamp is on when the lamp arc is not struck and essentially off when the voltage across the lamp drops after the lamp arc is struck to strike the arc of each lamp in sequence.
- View Dependent Claims (6, 8, 10, 12)
Specification