Ballast circuit having electromagnetic interference (EMI) reducing means for an improved lighting unit
First Claim
1. In a lighting unit having a gas discharge tube as the main light source, a filament serving as a supplementary light source and as a resistive ballast element, and a ballast circuit comprising means for coupling conduction inducing triggering pulses to said gas discharge tube, said ballast circuit being adapted to accept across its first and second input terminals an applied alternating current (A.C.) voltage, said first and second input terminals having connected thereacross rectifying means comprising four diodes arranged in a full-wave configuration and having at its output stage a filter capacitor, the improvement comprising:
- control means effective for developing an output signal indicative that at least one of said diodes of said rectifying means is in a forward-biased condition, and;
interrupt means responsive to said output signal of said control means and effective for generating a disabling signal to inhibit the coupling of said conduction inducing triggering pulses to said gas discharge tube.
1 Assignment
0 Petitions
Accused Products
Abstract
Various circuit embodiments for reducing the electromagnetic interference (EMI) typically created by a ballast circuit for an improved lighting unit is disclosed. The EMI reducing circuit adapts the operation of the source of the EMI of the ballast circuit to the conductive states of the rectifier means of the improved lighting unit.
-
Citations
6 Claims
-
1. In a lighting unit having a gas discharge tube as the main light source, a filament serving as a supplementary light source and as a resistive ballast element, and a ballast circuit comprising means for coupling conduction inducing triggering pulses to said gas discharge tube, said ballast circuit being adapted to accept across its first and second input terminals an applied alternating current (A.C.) voltage, said first and second input terminals having connected thereacross rectifying means comprising four diodes arranged in a full-wave configuration and having at its output stage a filter capacitor, the improvement comprising:
-
control means effective for developing an output signal indicative that at least one of said diodes of said rectifying means is in a forward-biased condition, and; interrupt means responsive to said output signal of said control means and effective for generating a disabling signal to inhibit the coupling of said conduction inducing triggering pulses to said gas discharge tube. - View Dependent Claims (2, 3, 4, 5, 6)
-
Specification