Cold cathode discharge lamp lighting circuit
US6281639A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 2000 |
| Grant date | Aug 28, 2001 |
| Priority date | — |
| Expiry date | Feb 1, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
To reduce a change in an electric current flowing through a cold cathode discharge lamp caused by a change in power source voltage. There is provided a cold cathode discharge lamp lighting circuit, in which a secondary high voltage of a transformer 13 is changed by controlling an oscillating period of a ROYER oscillating circuit 12 by a duty ratio of a PWM signal, to thereby control an amount of the electric current flowing through a cold cathode discharge lamp 11. In this lighting circuit, a resistor Rx is additionally connected between an inversion input terminal of a comparator X4 for generating the PWM signal and a power source, and a power source voltage divided by resistors Rx and R20 is inputted to the inversion input terminal. Thus, when the power source voltage is changed in an increase direction, an oscillating voltage is increased and the electric current flowing through the cold cathode discharge lamp begins to increase. However, since a voltage inputted to the comparator X4 through the resistor Rx is increased, an H (high voltage) period of the PWM signal is shortened and the oscillating period of the ROYER oscillating circuit is shortened, so that the electric current…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.