Dimmer for electrodeless discharge lamp

• US 5,561,351 A
• Filed: 10/26/1994
• Issued: 10/01/1996
• Est. Priority Date: 10/14/1992
• Status: Expired due to Fees

• Current Assignee: Diablo Research Corporation
• Original Assignee: Diablo Research Corporation
• Inventors: Pezzolo, Donald E., Lincoln, Larry A., Vrionis, Nickolas G., Bray, Derek, Pfeiffer, James W., Siao, Roger
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Philogene, Haissa
• Application Number:
  US08/329,696
• Time in Patent Office: 706 Days
• Field of Search: 315/248, 315/307, 315/194, 315/DIG. 4, 315/DIG. 7, 315/267, 315/282, 315/111.21, 315/291
• US Class Current: 315/248
• CPC Class Codes: H05B 41/24 in which the lamp is fed by high frequency ac, or with separate oscillator frequencyH05B41/26 takes precedence
• CPC Class Codes: H05B 41/36 Controlling
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

An arrangement for adjusting the intensity of an electrodeless discharge lamp is described. In one embodiment the high-frequency signal delivered to the induction coil is interrupted during a predetermined portion of a full duty cycle. This function is provided by a dimmer control unit which may be in an analog or digital form and may respond to a control signal provided by a potentiometer, a three-way lighting fixture or an addressable, remote controlled interface with data transmitted over the power lines or over a radio or infrared communication channel. In another embodiment the dimmer control unit alters the amplitude of the high-frequency signal supplied to the lamp'"'"'s induction coil.

Claims

1. An electrodeless discharge lamp comprising:

a power supply;

an induction coil for supplying electromagnetic radiation to a gaseous mixture enclosed within a vessel;

a driver for supplying an oscillating electrical signal to said induction coil so as to create a plasma of circulating charged particles within said vessel, said driver comprising a power supply and a power amplifier;

a gate for controlling the flow of an input signal to said power amplifier; and

a dimming control unit for controlling the state of said gate,

wherein said dimming control unit is operative to periodically open and close said gate at a selected periodic rate, said rate defining a time period between successive openings of said gate, said gate being open so as to allow said induction coil to receive said oscillating electrical signal during a selected duty cycle portion of said time period, said gate being closed so as to prevent said induction coil from receiving said oscillating electrical signal during a non-duty cycle portion of said time period.

2. The electrodeless discharge lamp of claim 1 wherein the duration of said non-duty cycle portion of said time period is set such that said plasma does not completely subside during said non-duty cycle portion.

3. The electrodeless discharge lamp of claim 1 wherein said dimming control unit comprises a sawtooth waveform generator, said generator being for delivering a sawtooth waveform to an input of a comparator.

4. The electrodeless discharge lamp of claim 1 wherein said dimming control unit comprises a period counter, a duty cycle counter and a decoder for holding a binary number representative of said duty cycle portion, a carry output of said period counter being connected to a load terminal of said duty cycle counter, said unit being structured such that said binary number is loaded into said duty cycle counter when said period counter carries.

5. The electrodeless discharge lamp of claim 1 wherein said dimming control unit comprises a microprocessor.

6. The electrodeless discharge lamp of claim 1 comprising in addition an input control device/interface for supplying an analog or digital control value to said dimming control unit.

7. The electrodeless discharge lamp of claim 6 wherein said input control device/interface comprises first and second terminals for connecting to first and second hot leads of a three-way lighting fixture, respectively, and a third terminal for connecting to the neutral lead of said three-way lighting fixture, a current of a first magnitude flowing in said first terminal when an AC voltage appears on said first hot lead, a current of a second magnitude flowing in said second terminal when an AC voltage appears on said second hot lead, and circuitry for adding said current of said first magnitude and said current of said second magnitude to form a current of a third magnitude when said AC voltages appear on both said first and second hot leads.

8. The electrodeless discharge lamp of claim 6 wherein said input control device/interface comprises a manually operated transducer located on said lamp, said transducer being capable of providing a signal for controlling said means for enabling and disabling said driving means.

9. The electrodeless discharge lamp of claim 6 wherein said input control device/interface comprises an interface for receiving data transmitted over a power line.

10. The electrodeless discharge lamp of claim 9 wherein said input control device/interface comprises a memory for storing data transmitted over a power line.

11. The electrodeless discharge lamp of claim 10 wherein said memory comprises an EEPROM.

12. The electrodeless discharge lamp of claim 6 wherein said input control device/interface comprises a means for detecting the level of light.

13. The electrodeless discharge lamp of claim 2 wherein the duration of said non-duty cycle portion is less than about 1.0 millisecond.

14. The electrodeless discharge lamp of claim 2 wherein duration of said duty cycle portion is equal to at least 5% of said time period.

15. The electrodeless discharge lamp of claim 7 wherein said second magnitude is twice said first magnitude.

16. The electrodeless discharge lamp of claim 4 wherein said dimming control unit further comprises a latch, said output of said period counter being connected to a set terminal of said latch, an output of said duty cycle counter being connected to a reset terminal of said latch.

17. The electrodeless discharge lamp of claim 16 wherein an output of said latch is connected to said gate.

18. The electrodeless discharge lamp of claim 4 further comprising first and second terminals for connecting to first and second hot leads of a three-way lighting fixture, respectively, said first and second terminals being connected to first and second AC detectors, respectively, said AC detectors being connected to input terminals of said decoder.

19. The electrodeless discharge lamp of claim 1 further comprising a triac connected in an AC power line leading to said power supply and a detector having an input connected to said triac and an output connected to said gate, said detector detecting a vertical leading edge of a chopped signal generated by said triac and in response to said leading edge generating a signal which opens said gate.

20. The electrodeless discharge lamp of claim 1 wherein said driver further comprises a crystal-controlled oscillator, an output terminal of said oscillator being connected to an input terminal of said power amplifier through said gate.