US 6,075,326 A · High intensity discharge lamp ballast and lighting system

Abstract

A versatile ballast and method of controlling and operating a high intensity discharge lamp. Lamp ignitor circuitry provides a high frequency alternating current starting voltage that is at least several times the nominal operating voltage of the lamp, thus shortening the starting time. This starting voltage is applied in series with normal operating voltage. After sustained ignition of the lamp has begun and a substantial lamp arc current has developed, the relatively low current supply characteristic of the alternating current starting voltage results in its becoming relatively insignificant. As lamp startup proceeds, the internal arc voltage typically falls to a fraction of its steady-state value; and circuit provision is made to correspondingly change applied current so as to maintain an essentially constant wattage operating power input to the lamp as the arc voltage changes. This automatic control of current also compensates for changes that occur in lamp characteristics as the lamp ages. In addition to the foregoing, provision is also made for adjusting the level of constant power input so as to provide for dimming and also to set the desired constant power level at any desired value over a wide range of from about 10 to 100 percent of lamp rated power.

Claims60

Dependent claims

A ballast for a direct current high intensity arc discharge lamp comprising:

(a) starting circuits having an output producing high frequency alternating current starting voltage of at least ten times the nominal voltage of said lamp;
(b) operating circuits including a source of direct current lamp energizing power interconnected with said lamp for providing operating power for energizing said lamp, said starting circuits and said source of direct current lamp energizing power being effectively connected in series;
(c) control circuits interconnected with said starting and operating circuits;
(d) means including said starting circuits for establishing an operating arc within said lamp;
(e) means for monitoring levels of voltage and current through said arc;
and
(f) control means responsive to said voltage and current through said arc for maintaining the product of said voltage and said current substantially constant at predetermined selectable wattage levels.

4 more elements

A ballast for a direct current high intensity arc discharge lamp comprising:

(a) starting circuits having an output producing high frequency alternating current starting voltage of at least several times the nominal voltage of said lamp, said frequency being in a range of from about 80 to 120 kilohertz, said starting circuits further including:
(i) means for establishing an operating arc within said lamp;
(ii) means for automatically rendering said starting voltage essentially ineffective as soon as said arc is established, and
(iii) counting means effective upon starting said lamp for defining predetermined timing intervals for applying operating current and said high frequency alternating current starting voltage to said lamp;
(b) operating circuits including a source of direct current lamp energizing power interconnected with said lamp for providing operating power for energizing said lamp, said starting circuits and said source of direct current lamp energizing power being effectively connected in series;
said operating circuits including:
(i) a pulse width modulated power supply;
(ii) means for supplying variable width pulses to said power supply;
and
(iii) means for supplying boost voltage to boost output of said operating circuits when in an open circuit condition to a value of more than twice a steady state operating voltage of said lamp;
(c) control circuits interconnected with said starting and operating circuits;
(d) means for monitoring levels of voltage and current through said arc;
and
(e) control means, including means for varying widths of said variable width pulses, responsive to said voltage and current through said arc for maintaining the product of said voltage and said current through said arc substantially constant at predetermined selectable wattage levels, said wattage levels being selectable within a range of from about 10 to 100 percent of rated maximum power input to said lamp.

11 more elements

Dependencies are inferred from the claim text.

High intensity discharge lamp ballast and lighting system

Life of this patent

High intensity discharge lamp ballast and lighting system

Life of this patent

Abstract

Claims60