Inverter for liquid crystal display

• US 8,723,780 B2
• Filed: 04/24/2008
• Issued: 05/13/2014
• Est. Priority Date: 09/04/2002
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Min, Woong-Kyu, Jang, Hyeon-Yong
• Primary Examiner(s): Moon, Seokyun
• Application Number:
  US12/108,951
• Publication Number:
  US 20080198183A1
• Time in Patent Office: 2,210 Days
• Field of Search: None
• US Class Current: 345/102
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence

Abstract

An inverter of driving a light source for a display device is provided. The inverter includes a temperature sensor sensing a temperature and generating an output voltage based on the sensed temperature, a buffer generating an output signal having a state depending on the output voltage of the temperature sensor, an oscillator generating an oscillating signal having a frequency depending on the state of the output signal of the buffer, and an inverter performing a switching operation in response to the oscillating signal from the oscillator. Therefore, the inverter increases the voltage applied to the light source when the temperature near the light source is lower than a predetermined temperature since the frequency of the oscillating signal is increased.

Claims

1. An inverter for a liquid crystal display, the inverter comprising:

an inverter controller generating a lamp driving signal having on-time and off-time, a carrier signal for pulse width modulation in synchronization with a horizontal synchronization signal, and an oscillating signal by pulse width modulating a reference signal based on the carrier signal;

a power switching element selectively transmitting a DC voltage in response to the oscillating signal from the inverter controller; and

a voltage booster for driving a lamp in response to a signal from the switching element,

wherein the carrier signal restarts whenever pulses of the horizontal synchronization signal are generated, and

wherein a falling edge of the carrier signal is synchronized with a falling edge of the horizontal synchronization signal.

2. The inverter of claim 1, wherein the liquid crystal display comprises a signal controller for providing the horizontal synchronization signal.

3. The inverter of claim 1, wherein the inverter controller comprises:

a control block for generating the lamp driving signal, the carrier signal, and the oscillating signal;

a time constant setting block for determining time constant of the carrier signal; and

an initiation block for resetting the time constant given by the time constant setting block whenever pulses of the horizontal synchronization signal are generated.

4. The inverter of claim 3, wherein the time constant setting block comprises a resistor and a capacitor connected in series and provides a signal at a node between the resistor and the capacitor to the control block.

5. The inverter of claim 4, wherein the initiation block comprises a multivibrator regulating pulse width of the horizontal synchronization signal and a diode connected in reverse direction from the multivibrator to the node between the resistor and the capacitor of the time constant setting block, the diode turned on by the pulses of the horizontal synchronization signal.

6. An inverter for a liquid crystal display, the inverter comprising:

an inverter controller generating first and second carrier signals for pulse width modulation, a lamp driving signal having on-time and off-time by pulse width modulating a dimming signal based on the first carrier signal, and an oscillating signal by pulse width modulating a reference signal based on the second carrier signal, and controlling the on-time of the lamp driving signal in response to pulses of at least one of a vertical synchronization signal and a horizontal synchronization signal;

a power switching element selectively transmitting a DC voltage in response to a signal from the inverter controller; and

a voltage booster for driving a lamp in response to a signal from the switching element,

wherein the second carrier signal restarts whenever pulses of the horizontal synchronization signal are generated, and

wherein a falling edge of the second carrier signal is synchronized with a falling edge of the horizontal synchronization signal.

7. The inverter of claim 6, wherein the liquid crystal display comprises a signal controller for providing the vertical synchronization signal and the horizontal synchronization signal, and the dimming signal is provided from the signal controller or an external device.