Claims
- 1. A high frequency, high pressure discharge lamp system, comprising:
- a high pressure discharge lamp comprising a discharge device sealed in a gas-tight manner and enclosing a discharge space, a discharge sustaining filling, and means for maintaining a discharge within said discharge space during lamp operation; and
- a ballast circuit coupleable to said discharge device for energizing said discharge lamp to maintain a gas discharge within said discharge space,
- characterized in that:
- the discharge device during normal lamp operation is free of acoustic resonances at alternating lamp currents below a lowest lamp resonant frequency,
- the ballast circuit energizes the discharge lamp so as to have an alternating lamp current having a fundamental frequency and harmonics which are integral multiples of the fundamental frequency,
- the lamp resonant frequency being greater than about 19 kHz, the fundamental frequency during nominal lamp operation being maintained only in a window between (i) about 19 kHz and (ii) below the lowest lamp resonant frequency, and
- the harmonics above the lowest lamp resonant frequency have amplitudes which are insufficient to induce acoustic resonance.
- 2. A lamp system according to claim 1, wherein said ballast maintains said fundamental frequency substantially constant during lamp operation.
- 3. A lamp system according to claim 2, wherein said discharge vessel comprises a ceramic and includes a central cylindrical zone with end walls, said end walls being spaced by an axial distance "L" and said central zone having an inner diameter "ID", and the ratio L:ID is about 1:1.
- 4. A lamp system according to claim 3, wherein said discharge lamp is a metal halide lamp and said discharge sustaining filling includes a buffer, a rare gas and a metal halide.
- 5. A lamp system according to claim 4, wherein said discharge lamp comprises an outer lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 6. A lamp system according to claim 2, wherein said discharge lamp is a metal halide lamp and said discharge sustaining filling includes a buffer, a rare gas and a metal halide.
- 7. A lamp system according to claim 2, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 8. A lamp system according to claim 1, wherein said discharge lamp is a metal halide lamp and said discharge sustaining filling includes a buffer, a rare gas and a metal halide.
- 9. A lamp system according to claim 1, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast to concurrently emit light.
- 10. A lamp system according to claim 1, further comprising a housing enclosing said ballast circuit and an outer lamp envelope enclosing said discharge device, said housing and said envelope forming an integral structure.
- 11. A lamp system according to claim 1, wherein said housing includes a screw base for being received by a screw-type socket, said screw base having base contacts connected to said ballast circuit for supplying electric power to said ballast when said base is received in a screw-type socket connected to an electric utility line voltage.
- 12. A high frequency metal halide lamp system, comprising:
- a) a metal halide lamp comprising a ceramic discharge vessel sealed in a gas-tight manner and enclosing a discharge space, a discharge sustaining filling within said discharge space including mercury, a metal halide, and a rare gas, a pair of discharge electrodes within said discharge space between which a gas discharge is maintained during lamp operation, and current conductors extending from said discharge electrodes to the exterior of said discharge vessel; and
- b) a ballast circuit connected to said metal halide lamp for igniting and maintaining a gas discharge between said discharge electrodes,
- characterized in that:
- the discharge lamp during normal lamp operation is free of acoustic resonances at alternating lamp currents below a lowest lamp resonant frequency,
- the ballast circuit energizes the discharge lamp so as to have an alternating lamp current having a fundamental frequency and harmonics which are integral multiples of the fundamental frequency,
- the lowest lamp resonant frequency being greater than about 19 kHz, the fundamental frequency during nominal lamp operation being maintained only in a window between (i) about 19 kHz and (ii) below the lowest lamp resonant frequency, and
- the harmonics above the lowest lamp resonant frequency have amplitudes which are insufficient to induce acoustic resonance.
- 13. A lamp system according to claim 12, wherein said discharge space enclosed by said discharge vessel is circular cylindrical between said electrodes and has planar end walls.
- 14. A lamp system according to claim 13, wherein said end walls are spaced by an axial distance "L" and said central zone has an inner diameter "ID", and the ratio L:ID is about 1:1.
- 15. A lamp system according to claim 14, wherein said ballast maintains said fundamental frequency substantially constant during lamp operation.
- 16. A lamp system according to claim 15, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 17. A lamp system according to claim 14, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 18. A lamp system according to claim 13, wherein said ballast maintains said fundamental frequency substantially constant during lamp operation.
- 19. A lamp system according to claim 13, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 20. A lamp system according to claim 12, wherein said ballast maintains said fundamental frequency substantially constant during lamp operation.
- 21. A lamp system according to claim 12, wherein said discharge lamp comprises a lamp envelope and a plurality of said discharge devices within said lamp envelope each energized by said ballast circuit to concurrently emit light.
- 22. A high frequency, high pressure discharge lamp system, comprising:
- a high pressure discharge lamp comprising a discharge device sealed in a gas-tight manner and enclosing a discharge space, a discharge sustaining filling, and means for maintaining a discharge within said discharge space during lamp operation; and
- a ballast circuit coupleable to said discharge device for energizing said discharge device to maintain a gas discharge within said discharge space,
- characterized in that:
- the discharge device during normal lamp operation is free of acoustic resonances at lamp power frequencies below a lowest lamp resonant power frequency,
- the ballast circuit energizes the discharge lamp so as to have a fundamental power frequency and harmonics which are integral multiples of the fundamental power frequency,
- the lowest lamp resonant power frequency being greater than about 38 kHz, the fundamental power frequency being maintained during nominal operation in a window between (i) about 38 kHz and (ii) below the lowest lamp resonant power frequency, and
- the harmonics above the lowest lamp resonant power frequency have amplitudes which are insufficient to induce acoustic resonance.
- 23. A high frequency metal halide lamp system according to claim 12, further comprising a starting aid for said discharge device, said starting aid comprising a length of conductive material extending from one said current conductor to the area of the other said current conductor and terminating adjacent the discharge vessel wall of the other said current conductor, said discharge vessel wall of the said other current conductor enclosing a narrow gap with the said other current conductor in which said discharge sustaining fill is present.
CROSS REFERENCE TO RELATED APPLICATIONS
This application relates to U.S. application Ser. No. 647,385, filed concurrently herewith entitled "Integrated HID Reflector Lamp" of Dale Work et al which discloses and claims a reflector lamp with an HID arc tube integrated in one embodiment with a high frequency ballast and avoiding acoustic resonance.
US Referenced Citations (10)
Non-Patent Literature Citations (2)
Entry |
An Autotracking System for Stable Hf Operation of HID Lamps, F. Bernitz, Symp. Light Sources, Karlsruhe, 1986. |
U.S. Appln. Serial No. 08/366, 135, filed Dec. 29, 1994. |