# US 7,015,660 B2 · Circuit for driving cold cathode tubes

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- Number: US 7,015,660 B2
- Document ID: US7015660B2
- Status: Granted
- Kind: B2
- Application number: 10/672,371
- Filed: 2003-09-25
- Published: 2004-03-25
- Granted: 2006-03-21
- Earliest claimed: 2002-09-25
- Assignees: Design Rite, LLC
- Inventors: Gilbert Fregoso
- Web page: https://patentgrep.com/patent/US7015660B2

## CPC

- H05B 41/2828: {using control circuits for the switching elements (H05B41/2827 takes precedence)}
- Y10S 315/05: Starting and operating circuit for fluorescent lamp
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The subject invention is a circuit for driving a cold cathode tube using a 110V power supply. Power is provided to the cold cathode tube through a direct current converter circuit. A resonance capacitor works in conjunction with the inductive storage device until the start resonance of the tube is attained as directed by a resistor/capacitor (R/C) network. Once the tube starts conducting, another R/C network maintains and controls the circuit at a run resonance. The main driver is an oscillator with a high side and low side MOSFET driver.

## Claims

### Claim 1

A circuit for driving cold cathode tubes comprising:
an oscillator having a high side MOSFET driver and a low side MOSFET driver;
two high voltage MOSFETs;
a resistor/capacitor network; and
a set of resonance elements comprising a single wound inductive storage device, a resonance capacitor and a cold cathode tube, wherein said resistor/capacitor network directs said oscillator to achieve a first resonance frequency to drive said resonance elements and causes said cold cathode tube to conduct and thereafter said resistor/capacitor network directs said oscillator to achieve a second resonance frequency to drive said resonance elements and illuminate said cold cathode tube.

### Claim 2 (depends on 1)

The circuit of claim 1, further comprising a low direct current voltage power source to supply power to said oscillator.

### Claim 3 (depends on 1)

The circuit of claim 1, wherein said circuit has a first resistor/capacitor network to direct said oscillator to achieve said first resonance frequency and a second resistor/capacitor network to direct said oscillator to achieve said second resonance frequency.

### Claim 4 (depends on 1)

The circuit of claim 1, wherein said set of resonance elements further comprises a filter capacitor and said circuit further comprises a current sensor.

### Claim 5 (depends on 1)

The circuit of claim 1, wherein said circuit further comprises a direct current converter circuit to rectify and filter an alternating current input.

### Claim 6 (depends on 5)

The circuit of claim 5, wherein said direct current converter circuit is a split voltage device.

### Claim 7 (depends on 5)

The circuit of claim 5, wherein said direct current converter circuit is a full wave device and said circuit further comprises a direct current blocking capacitor.

### Claim 8 (depends on 4)

The circuit of claim 4, wherein said circuit has at least two sets of resonance elements.

### Claim 9

A circuit for driving cold cathode tubes comprising:
a full wave direct current power converter;
a low direct current voltage power source;
an oscillator having a high side MOSFET driver and a low side MOSFET driver;
two high voltage MOSFETs;
a direct current blocking capacitor;
a resistor/capacitor network;
a set of resonance elements comprising a single wound inductive storage device, a filter capacitor, a resonance capacitor and a cold cathode tube, and
a current sensor, wherein said resistor/capacitor network directs said oscillator to achieve a first resonance frequency to drive said resonance elements and causes said cold cathode tube to conduct and thereafter said resistor/capacitor network directs said oscillator to achieve a second resonance frequency to drive said resonance elements and illuminate said cold cathode tube.

### Claim 10 (depends on 9)

The circuit of claim 9, wherein said circuit comprises a plurality of sets of resonance elements and a plurality of current sensors.

### Claim 11

A circuit for driving cold cathode tubes comprising:
a split voltage direct current power converter;
a low direct current voltage power source;
an oscillator having a high side MOSFET driver and a low side MOSFET driver;
two high voltage MOSFETs;
a resistor/capacitor network; and
a set of resonance elements comprising a single wound inductive storage device, a resonance capacitor and a cold cathode tube, wherein said resistor/capacitor network directs said oscillator to achieve a first resonance frequency to drive said resonance elements and causes said cold cathode tube to conduct and thereafter said resistor/capacitor network directs said oscillator to achieve a second resonance frequency to drive said resonance elements and illuminate said cold cathode tube.

### Claim 12 (depends on 11)

The circuit of claim 11, wherein said circuit has a first resistor/capacitor network to direct said oscillator to achieve said first resonance frequency and a second resistor/capacitor network to direct said oscillator to achieve said second resonance frequency.