Lighting device for a dielectric barrier discharge lamp

• US 20050093478A1
• Filed: 08/24/2004
• Published: 05/05/2005
• Est. Priority Date: 08/26/2003
• Status: Active Grant

• Current Assignee: Harison Toshiba Lighting Corporation (Toshiba Corporation)
• Original Assignee: Harison Toshiba Lighting Corporation (Toshiba Corporation)
• Inventors: Shiba, Toshiaki
• Granted Patent: US 7,109,666 B2
• Time in Patent Office: Days
• US Class Current: 315/246
• CPC Class Codes: H05B 41/2806 with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

A lighting device for dielectric barrier discharge lamp according to the embodiment of the present invention includes a pulse number judging circuit 16. The judging circuit 16 is supplied with a dimming control signal LCS designating a dimming ratio of a discharge lamp as an input signals and judges a number of the drive signal pulses per unit time corresponding to the dimming ratio from the dimming control signal LCS. The judging circuit 16 then outputs the result as the pulse number setting signal. The lighting device includes a drive signal generating signal 18, which is supplied with the pulse number setting signal and outputs the drive signal pulse of the prescribed number of pulse per unit time designated by the number of the pulse setting signal. The lighting device further includes an inverter circuit 10, which is supplied with the output of the drive signal generating circuit 18 and generates HF pulse for driving the dielectric barrier discharge type fluorescent lamp.

Claims

1. Alighting device for a dielectric barrier discharge lamp comprising:

a pulse number judging circuit to which a dimming control signal is supplied as an input signal designating a dimming ratio of the dielectric barrier discharge type discharge lamp using rare gas, for judging a number of drive signal pulses per unit time corresponding to the dimming ratio from the dimming control signal, and for outputting the result as the pulse number setting signal,

a drive signal generating circuit to which the pulse number setting signal outputted from the pulse number judging circuit is supplied, for outputting the drive signal pulses having a number of pulses per unit time designated by the pulse number setting signal and

an inverter circuit which generates HF pulse voltage for driving the dielectric barrier discharge type fluorescent lamp.

2. A lighting device for a dielectric barrier discharge lamp according to claim 1, wherein the unit time is equal to a period T of a repetition cycle of the dimming control signal.

3. A lighting device for a dielectric barrier discharge lamp according to claim 2, wherein the drive signal pulse is a pair of pulse signals each having substantially an equal repetition cycle and each having a different phase from each other by substantially 180°

.

4. A lighting device for a dielectric barrier discharge lamp according to claim 3, wherein a fluctuation of the start timing of the first drive signal pulse in a repetition period T of the dimming control signal for a repetition period t of the drive pulse signals P1 and P2 is confined in the range from −

½

×

t to +½

×

t.

5. Alighting device for a dielectric barrier discharge lamp according to claim 4, wherein a fluctuation of the drive pulse signal in a repetition period of the driving pulse signals is confined in the range from −

{fraction (1/10)}×

t to +{fraction (1/10)}×

t.

6. Alighting device for a dielectric barrier discharge lamp according to claim 5, wherein the inverter circuit is either one of a full bridge type, half bridge type, push-pull type, or center tap type.

7. A lighting device for a dielectric barrier discharge lamp according to claim 1, wherein the pulse number judging circuit and the drive signal generating circuit are formed by a micro computer.

8. A lighting device for a dielectric barrier discharge lamp according to claim 7, wherein a pulse number judging unit in the micro computer judges dimming ratio X % from the inputted dimming control signal LCS and decides numbers of pulse Y in 1 cycle of dimming control signal LCS corresponding to the judged dimming ratio X %, wherein the pulse number judging unit transmits it to the drive signal generating circuit as the pulse number setting signal, and wherein the drive signal generating unit judges

(1) Has 1 cycle t of the drive signal P1, P2 completed entirely?

(2) Has 1 period T of the dimming control signal completed entirely?

and supplies the drive signal with Y number of pulses corresponding to the dimming ratio X % to the inverter circuit after each cycle has completed.

9. A lighting device for a dielectric barrier discharge lamp according to claim 8, wherein the unit time is the repetition cycle T of the dimming control signal.

10. A lighting device for a dielectric barrier discharge lamp according to claim 9, wherein the fluctuation of the start timing of the drive signal pulse at the repetition period T of the dimming control signal for a repetition period t of the drive pulse signals P1 and P2 is confined in the range from −

½

×

t to +½

×

t.

11. A lighting device for a dielectric barrier discharge lamp according to claim 10, wherein the fluctuation of the drive signal pulse in the repetition period t of the drive signal pulse is confined in the range from {fraction (1/10)}×

t to +{fraction (1/10)}×

t.

12. A lighting device for a dielectric barrier discharge lamp comprising:

a dielectric barrier discharge lamp having discharge plasma space filled with rare gases, which generates excimer molecules by dielectric barrier discharge and having a structure in which a dielectric material lies between the rare gases and at least one of the two electrodes for inducing the discharge in the rare gases, and

an HF source device for periodically supplying the electrodes of the dielectric barrier discharge lamp with a prescribed number of high voltage pulses,

wherein the HF source device further comprises;

a pulse number judging circuit, which is supplied with a dimming control signal for deciding the dimming ratio of the dielectric barrier discharge type discharge lamp as an input signal for judging a number of drive signal pulses per unit time corresponding to the dimming ratio determined by the dimming control signal and for outputting the result as a pulse number setting signal,

a drive signal generating circuit, which is supplied with the pulse number setting signal outputted from the pulse number judging circuit and outputs a drive signal pulse having a prescribed number of pulses per unit time designated by the pulse number setting signal, and

an inverter circuit, which is supplied with the output of the drive signal generating circuit and generates HF pulse voltage for driving the dielectric barrier discharge type discharge lamp.

13. A lighting device for a dielectric barrier discharge lamp according to claim 12, wherein the unit time is equal to a period T of a repetition cycle of the dimming control signal.

14. A lighting device for a dielectric barrier discharge lamp according to claim 13, wherein the drive signal pulse is a pair of pulse signals each having a substantially equal repetition cycle t and each having a different phase from each other by substantially 180°

.

15. A lighting device for a dielectric barrier discharge lamp according to claim 14, wherein the dielectric barrier discharge lamp is provided with a glass tube which is filled with rare gas for forming a discharge plasma space, and wherein one of the two electrodes is an inner electrode sealed at one end of the glass tube, and the other one is an external electrode composed of an electrically conductive material wound spirally around an outer surface of the glass tube.

16. A lighting device for a dielectric barrier discharge lamp according to claim 15, wherein the dielectric barrier discharge lamp is a dielectric barrier discharge lamp, in which a phosphor is provided on an inner wall of the glass tube.

17. A lighting device for a dielectric barrier discharge lamp according to claim 16, wherein the pulse number judging circuit and the drive signal generating circuit are composed of a micro computer.