US 5,510,681 A · Operating circuit for gas discharge lamps

Abstract

A half-bridge inverter is powered from a constant-magnitude DC supply voltage and provides at the inverter's output a first AC output voltage that is describable as a modified squarewave voltage. This first AC voltage is applied across a series-combination of an inductor and a capacitor, the junction between which is clamped to the DC supply voltage. As a result, a second AC voltage gets established across the capacitor; which second AC voltage is also describable as being a modified squarewave voltage. However, the phasing of the second AC voltage is delayed by approximately 90 degrees with respect to the first AC voltage; which results in the voltage across the inductor being of approximately sinusoidal waveform. A fluorescent lamp is connected in series with a ballast capacitor; and the lamp-capacitor series combination is connected across the inductor, thereby resulting in a nearly sinusoidal current being provided to the fluorescent lamp. Lamp starting aid is provided by a voltage-doubling circuit supplying a high-magnitude current-limited DC voltage across the ballast capacitor for ignition purposes.

Claims17

Dependent claims

An arrangement comprising:

a source functional to provide an AC voltage between a first and a second source terminal;
there being substantially no galvanic connection between the first source terminal and earth ground;
there being substantial galvanic connection between the second source terminal and earth ground;
the term galvanic connection being defined as a connection by way of which a unidirectional current can flow;
a capacitor having a first and a second capacitor terminal;
the first capacitor terminal being connected with the second source terminal;
and
gas discharge lamp having a first and a second lamp terminal disconnectably connected with the first source terminal and the second capacitor terminal, respectively;
whereby neither the first source terminal nor the second capacitor terminal exhibits galvanic connection with earth ground.

6 more elements

An arrangement comprising:

a power source providing a power line voltage at a pair of power line terminals;
a first sub-circuit connected with the power line terminals and operative to provide a DC voltage at a pair of DC terminals;
a second sub-circuit connected with the DC terminals and operative to provide an AC voltage between a pair of AC terminals;
the second sub-circuit being characterized by having two transistors series-connected between the DC terminals;
the AC voltage being characterized by being non-sinusoidal and by having a peak-to-peak magnitude distinctly higher than the peak magnitude of the power line voltage;
the AC voltage being further characterized by having a fundamental period:
(i) during a first part of which its instantaneous magnitude remains substantially constant at a first given level;
and (ii) during a second part of which its instantaneous magnitude remains substantially constant at a second given level, the second part having a total duration substantially equal to that of the first part as well as substantially equal to at least one fourth the total duration of the whole fundamental period;
gas discharge lamp having lamp terminals;
and
a third sub-circuit connected between the AC terminals and the lamp terminals;
the third sub-circuit being operative, in response to the AC voltage, to cause a lamp current to flow through the lamp.

9 more elements

An arrangement comprising:

a first sub-circuit adapted to connect with the power line voltage of an ordinary electric utility power line and, when indeed so connected, operative to provide a DC voltage at a pair of DC terminals;
a second sub-circuit connected with the DC terminals and operative to provide an AC voltage between a pair of AC terminals;
the AC voltage being characterized by having a fundamental period:
(i) during a first part of which its instantaneous magnitude remains substantially constant at a first given level;
and (ii) during a second part of which its instantaneous magnitude remains substantially constant at a second given level, the second part having a total duration substantially equal to that of the first part as well as distinctly longer than one fourth the total duration of the whole fundamental period;
gas discharge lamp having lamp terminals;
a third sub-circuit connected between the AC terminals and the lamp terminals;
the third sub-circuit being operative, in response to the AC voltage, to cause a lamp current to flow through the lamp;
and
physical structure combining the three subcircuits and the gas discharge lamp in such manner as to result in a single substantially rigid physical structure characterized by having a protruding threaded portion adapted to be screwed into and held by an Edison-type lamp socket.

7 more elements

Dependencies are inferred from the claim text.

Operating circuit for gas discharge lamps

Life of this patent

Operating circuit for gas discharge lamps

Life of this patent

Abstract

Claims17