Inductive-resistive fluorescent apparatus and method

• US 6,456,015 B1
• Filed: 02/06/2001
• Issued: 09/24/2002
• Est. Priority Date: 10/16/1996
• Status: Expired due to Fees

• Current Assignee: Carol A. Lovell, Estate of Walter Carl Lovell
• Original Assignee: Tapeswitch Corporation (Inductotherm Group)
• Inventors: Lovell, Walter C., Duhon, Edward, Brooks, Sheldon B., Geiger, Dana
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Lee, Wilson
• Application Number:
  US09/777,715
• Publication Number:
  US 20020074953A1
• Time in Patent Office: 595 Days
• Field of Search: 315/39-46, 315/246, 315/248, 315/291, 315/307, 315/219, 315/244
• US Class Current: 315/248
• CPC Class Codes: H01J 61/56 One or more circuit elements structurally associated with the lamp
• CPC Class Codes: H05B 41/16 in which the lamp is fed by dc or by low-frequency ac, e.g. by 50 cycles/sec ac, or with network frequencies
• 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 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence

Abstract

A fluorescent illuminating apparatus includes an inductive-resistive structure that induces fluorescence in a fluorescent lamp when an electric current is passed through the inductive-resistive structure while an electric potential is applied across the fluorescent lamp A source of rippled/pulsed direct current is responsive to a control sub-circuit, which outputs a lamp voltage signal representative of the electric potential to be applied to the fluorescent lamp. A power supply sub-circuit is responsive to the control sub-circuit and imposes the electric potential at the value indicated by the lamp voltage signal. A method of inducing fluorescence includes passing a current through an inductive structure adjacent to a fluorescent lamp. An alternating current drive circuit for illuminating the fluorescent lamp includes a source of rippled/pulsed DC voltage, a polarity-reversing circuit and a controller connected to the polarity-reversing circuit, which periodically generates a signal to reverse the polarity of the voltage applied to the lamp. The electric potential applied to the fluorescent lamp is delayed for a first time period until the fluorescent lamp heats to a first temperature. The electric potential is then applied to the fluorescent lamp at a first level, and delays to allow the value of the rippled/pulsed direct current to stabilize. The direct current is then measured, and the electric potential is applied to the fluorescent lamp at a second level. The value of the dimming voltage is measured, and the electric potential applied to the lamp is adjusted accordingly by varying its duty cycle.

Claims

1. A method of driving a fluorescent lamp, the method comprising the steps of:

providing a source of rippled/pulsed direct current (DC) electrical potential;

passing a current through an inductive-resistive structure adjacent to the fluorescent lamp in an amount sufficient to induce fluorescence in the presence of the electrical potential imposed on the fluorescent lamp;

delaying the application of the electrical potential to the fluorescent lamp for a first time period until the electrical potential imposed on the fluorescent lamp causes the fluorescent lamp to heat to a first temperature;

providing the electric potential imposed on the fluorescent lamp at a first level;

delaying a second time period to allow a value of the rippled/pulsed direct current to stabilize;

measuring the value of the rippled/pulsed direct current;

providing the electric potential imposed on the fluorescent lamp at a second level;

measuring the value of the rippled/pulsed direct current;

measuring the value of a dimming voltage; and

adjusting the value of the electric potential in response to the measured dimming voltage.

2. The method defined by claim 1, further comprising the steps of:

comparing the value of the rippled/pulsed direct current to a minimum current level;

delaying the application of the electrical potential to the fluorescent lamp for the first time period until the electrical potential imposed on the fluorescent lamp causes the fluorescent lamp to heat to the first temperature if the value of the rippled/pulsed direct current is less than the minimum current level;

providing the electric potential imposed on the fluorescent lamp at the first level;

delaying the second time period to allow the value of the rippled/pulsed direct current to stabilize; and

measuring the value of the rippled/pulsed direct current.

3. The method defined by claim 2, further comprising the steps of:

incrementing a variable if the value of the rippled/pulsed direct current is less than the minimum current level; and

waiting until a reset occurs if the value of the variable is equal to a first value.

4. The method defined by claim 1, further comprising the steps of:

comparing the value of the rippled/pulsed direct current to a maximum current level;

delaying the application of the electrical potential to the fluorescent lamp for the first time period until the electrical potential imposed on the fluorescent lamp causes the fluorescent lamp to heat to the first temperature if the value of the rippled/pulsed direct current is greater than the maximum current level;

providing the electric potential imposed on the fluorescent lamp at the first level;

delaying the second time period to allow the value of the rippled/pulsed direct current to stabilize; and

measuring the value of the rippled/pulsed direct current.

5. The method defined by claim 4, further comprising the steps of:

incrementing a variable if the value of the rippled/pulsed direct current is greater than the maximum current level; and

waiting until a reset occurs if the value of the variable is equal to a first value.

6. The method defined by claim 1, further comprising the steps of:

periodically reversing the polarity of the rippled/pulsed direct current electric potential applied to the fluorescent lamp, thereby producing an alternating current lamp drive voltage having a duty cycle;

providing a control sub-circuit capable of varying the duty cycle;

measuring a dimming voltage, the dimming voltage being representative of a desired brightness of the fluorescent lamp; and

adjusting the duty cycle in response to the measured dimming voltage.

7. A fluorescent illuminating apparatus comprising:

a fluorescent lamp including;

a translucent housing having a chamber for supporting a fluorescent medium, the housing having first and second ends;

electrical connections located on the housing to provide an electrical potential across the chamber, the connections being in the form of first and second electrical terminals;

a fluorescent medium supported in the chamber; and

first and second electrodes located respectively at the first and second ends of the translucent housing, the first and second electrodes being respectively electrically interconnected with the first and second electrical terminals;

an inductive-resistive structure fixed sufficiently proximate to the housing of the fluorescent lamp to induce fluorescence in the fluorescent medium when an electric current is passed through the inductive-resistive structure while an electric potential is applied across the housing, the inductive-resistive structure having third and fourth electrical terminals thereon, the second and third electrical terminals being electrically interconnected; and

a source of rippled/pulsed direct current (DC) voltage having first and second output terminals electrically interconnected with the first and fourth electrical terminals, the source having first and second alternating current (AC) input voltage terminals;

a control sub-circuit, the source of rippled/pulsed direct current being responsive to the control sub-circuit, the control sub-circuit outputting a lamp voltage signal representative of a value of the electric potential to be imposed on the fluorescent lamp; and

a power supply sub-circuit, the power supply sub-circuit being responsive to the control sub-circuit, the power supply sub-circuit imposing the electric potential on the fluorescent lamp at the value represented by the lamp voltage signal.

8. The fluorescent illuminating apparatus defined by claim 7, wherein the control sub-circuit includes at least one of a microcontroller and microprocessor.

9. The fluorescent illuminating apparatus defined by claim 7, further comprising an auxiliary power supply sub-circuit electrically connected to the power supply sub-circuit, the auxiliary power supply sub-circuit including an inductor, the inductor including a plurality of substantially isolated outputs, at least one of the plurality of outputs being electrically connected to a fluorescent lamp heater.

10. The fluorescent illuminating apparatus defined by claim 7, further comprising a dimmer control sub-circuit, the dimmer control sub-circuit inputting a dimming signal and outputting a dimming voltage signal, the control sub-circuit being responsive to the dimming voltage signal, the control sub-circuit outputting a lamp voltage signal representative of the dimming voltage signal.

11. The fluorescent illuminating apparatus defined by claim 10, wherein the dimming signal is output from a potentiometer.

12. The fluorescent illuminating apparatus defined by claim 10, wherein the dimming signal is an external signal inputted to the dimmer control sub-circuit, the external circuit being about 4 to about 20 ma.

13. The fluorescent illuminating apparatus defined by claim 10, wherein the dimmer control sub-circuit includes an analog optocoupler, the analog optocoupler electrically isolating the dimming signal from the dimming voltage signal.

14. The fluorescent illuminating apparatus defined by claim 7, further comprising a ballast sub-circuit responsive to the lamp voltage signal, the ballast sub-circuit being capable of periodically reversing the polarity of the rippled/pulsed direct current electric potential imposed on the fluorescent lamp producing an alternating current lamp drive voltage having a duty cycle, the ballast sub-circuit being capable of varying the duty cycle of the lamp drive voltage in response to the lamp voltage signal outputted from the control sub-circuit, thereby selectively dimming the fluorescent lamp.

15. The fluorescent illuminating apparatus defined by claim 14, wherein the ballast sub-circuit includes a pulse width modulator circuit, the pulse width modulator circuit providing at least two variable duty cycle output signals about 180 degrees out of phase with each other, the pulse width modulator circuit being responsive to the lamp voltage signal outputted from the control sub-circuit.

16. The fluorescent illuminating apparatus defined by claim 15, wherein the ballast sub-circuit includes at least two half bridge drivers, the at least two half bridge driver circuits being electrically connected to the pulse width modulator circuit, the at least two half bridge driver circuits providing an electrical interface between the pulse width modulator and an H-bridge.

17. The fluorescent illuminating apparatus defined by claim 14, wherein the ballast circuit includes a resistor and a capacitor, the resistor and the capacitor being configured as an RC filter and electrically connected to the fluorescent lamp, the resistor and the capacitor extracting an average value of current flowing through the fluorescent lamp and outputting the average value to the control sub-circuit.

18. The fluorescent illuminating apparatus defined by claim 17, wherein the control sub-circuit turns the fluorescent lamp off in response to the average value of the current flowing through the fluorescent lamp being one of above a maximum current level and below a minimum current level.