Backlight inverter for liquid crystal display panel of asynchronous pulse width modulation driving type
First Claim
1. A backlight inverter for a liquid crystal display (LCD) panel for driving a plurality of lamps in pairs, comprising:
- a main driving integrated circuit (IC) for generating first and second pulse width modulation (PWM) pulses in response to a dimming voltage based on a brightness control and an internally generated PWM oscillation signal, delaying the generated first and second PWM pulses by a predetermined period of time and outputting first and second PWM drive signals on the basis of the delayed first and second PWM pulses, respectively;
at least one sub-driving IC for secondarily delaying said delayed first and second PWM pulses from said main driving IC by said predetermined period of time and outputting third and fourth PWM drive signals on the basis of the secondarily delayed first and second PWM pulses, respectively; and
a plurality of lamp operating circuits for operating said pairs of lamps in response to said first and second PWM drive signals from said main driving IC and said third and fourth PWM drive signals from said sub-driving IC, respectively.
1 Assignment
0 Petitions
Accused Products
Abstract
A backlight inverter for an LCD panel of an asynchronous pulse width modulation (PWM) driving type which is capable of driving a plurality of cold cathode fluorescent lamps (CCFLs) in pairs and controlling a plurality of PWM drive signals for respective operations of the lamps to make the phases thereof different. The backlight inverter comprises a main driving integrated circuit (IC) for generating first and second PWM pulses in response to a dimming voltage based on a brightness control and an internally generated PWM oscillation signal, delaying the generated first and second PWM pulses by a predetermined period of time and outputting first and second PWM drive signals on the basis of the delayed first and second PWM pulses, respectively, at least one sub-driving IC for secondarily delaying the delayed first and second PWM pulses from the main driving IC by the predetermined period of time and outputting third and fourth PWM drive signals on the basis of the secondarily delayed first and second PWM pulses, respectively, and a plurality of lamp operating circuits for operating the pairs of lamps in response to the first and second PWM drive signals and the third and fourth PWM drive signals, respectively. The lamps have different PWM on/off periods so that overshoot of a power supply circuit can be reduced so as to keep the entire system power stable.
13 Citations
11 Claims
-
1. A backlight inverter for a liquid crystal display (LCD) panel for driving a plurality of lamps in pairs, comprising:
-
a main driving integrated circuit (IC) for generating first and second pulse width modulation (PWM) pulses in response to a dimming voltage based on a brightness control and an internally generated PWM oscillation signal, delaying the generated first and second PWM pulses by a predetermined period of time and outputting first and second PWM drive signals on the basis of the delayed first and second PWM pulses, respectively;
at least one sub-driving IC for secondarily delaying said delayed first and second PWM pulses from said main driving IC by said predetermined period of time and outputting third and fourth PWM drive signals on the basis of the secondarily delayed first and second PWM pulses, respectively; and
a plurality of lamp operating circuits for operating said pairs of lamps in response to said first and second PWM drive signals from said main driving IC and said third and fourth PWM drive signals from said sub-driving IC, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification