Variable control, current sensing ballast

Abstract

The present invention is directed to an electronic ballast device for the control of gas discharge lamps. The device is comprised of a housing unit with electronic circuitry and related components. The device accepts a.c. power and rectifies it into various low d.c. voltages to power the electronic circuitry, and to one or more high d.c. voltages to supply power for the lamps. Both the low d.c. voltages and the high d.c. voltages can be supplied directly, eliminating the need to rectify a.c. power. The device switches a d.c. voltage such that a high frequency signal is generated. Because of the choice of output transformers matched to the high frequency (about 38 kHz) and the ability to change frequency slightly to achieve proper current, the device can accept various lamp sizes without modification. The ballast can also dim the lamps by increasing the frequency. The device can be remotely controlled.

Claims

2. The electronic device of claim 1, further comprising the means to be remotely controlled, for switching on and off.

3. The electronic device of claim 1, further comprising the means to remotely control the device such that the lights may be dimmed by controlling the PWM circuitry.

4. The electronic device of claim 1, further comprising the means to control the device by a programmable timer and dimmer.

6. The electronic device of claim 5 further comprising the means to be remotely controlled, for switching on and off.

7. The electronic device of claim 5 further comprising the means to remotely control the device such that the lights may be dimmed by controlling the PWM circuitry.

8. The electronic device of claim 5 further comprising the means to control the device by a programmable timer and dimmer..Iadd.

9. An electronic ballast for controlling the power to a set of one or more gas discharge lamps, comprising:

(a) a switching circuit for generating a high frequency a.c. voltage;

(b) a waveshaping circuit for smoothing the high frequency a.c. voltage;

(c) at least one transformer having a primary winding and at least one secondary winding, each of the primary and secondary windings having a first end and a second end;

(d) wherein the switching circuit, waveshaping circuit and Primary winding are connected together in series; and

(e) the set of one or more gas discharge lamps and the at least one secondary winding is connected in parallel with the waveshaping circuit such that the first end of said at least one secondary winding is connected to a node between the primary winding and the waveshaping circuit..Iaddend..Iadd.10. The electronic ballast of claim 9, wherein the set of one or more gas discharge lamps comprises one lamp..Iaddend..Iadd.11. The electronic ballast of claim 9, wherein the set of one or more gas discharge lamps comprises two or more lamps and connections between lamps in the set of two or more gas discharge lamps is serial and each connection is provided by one of said at least one

secondary winding..Iaddend..Iadd.12. The electronic ballast of claim 9, wherein the waveshaping circuit comprises a capacitor in parallel with a varistor..Iaddend..Iadd.13. The electronic ballast of claim 11, wherein the primary winding has approximately 85 turns and each secondary winding that provides a serial connection between lamps in the set of one or more gas discharge lamps has approximately two turns..Iaddend..Iadd.14. The electronic ballast of claim 9, wherein the switching circuit comprises:

(a) means for connecting to an a.c. power supply at an input;

(b) a rectifying circuit to convert an a.c. voltage received from the a.c. power supply to a d.c. voltage; and

(c) a converting circuit connected to an output of the rectifying circuit for converting the d.c. voltage into a high frequency a.c. voltage..Iaddend..Iadd.15. The electronic ballast of claim 14, wherein the converting circuit comprises:

(a) a pulse width modulator;

(b) a gate driver connected to the pulse width modulator;

(c) a switch controlled by the gate driver for converting the d.c. voltage from the rectifying circuit into the high frequency a.c. voltage;

(d) wherein the pulse width modulator provides timing signals to the gate

driver..Iaddend..Iadd.16. The electronic ballast of claim 15, wherein the switch comprises one or more MOSFETs..Iaddend..Iadd.17. The electronic ballast of claim 9, further comprising dimming means for controlling the frequency of the high frequency a.c. voltage..Iaddend..Iadd.18. The electronic ballast of claim 14, further comprising a lamp sensing circuit connected to one of the at least one secondary winding for detecting a current passing through the one of the at least one secondary winding..Iaddend..Iadd.19. The electronic ballast of claim 18, further comprising a shutdown circuit connected to the lamp sensing circuit for decreasing power to the set of one or more gas discharge lamps when the detected current is indicative of a lamp fault..Iaddend..Iadd.20. The electronic ballast of claim 18, further comprising a comparator circuit connected to the lamp sensing circuit, the comparator circuit receiving an external control signal and comparing the control signal to the signal received from the lamp sensing circuit and thereby controlling the pulse width modulator..Iaddend.