Inverter for liquid crystal display

• US 7,417,616 B2
• Filed: 09/04/2003
• Issued: 08/26/2008
• Est. Priority Date: 09/04/2002
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: Jang, Hyeon-Yong, Min, Woong-Kyu
• Primary Examiner(s): Lefkowitz; Sumati
• Assistant Examiner(s): Moon; Seokyun
• Application Number:
  US10/656,696
• Publication Number:
  US 20040056825A1
• Time in Patent Office: 1,818 Days
• Field of Search: 345/102, 315/291, 315/294, 315/295, 315/300
• 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 for a display includes; an inverter controller generating a carrier signal for pulse width modulation and a lamp driving signal having on-time and off-time by pulse width modulating a dimming signal based on the carrier signal and controlling the on-time of the lamp driving signal in response to at least one of a vertical synchronization signal and a vertical synchronization start signal from the signal controller, a power switching element 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 inverter controller includes a control block which generates the carrier signal and the lamp driving signal, a time constant setting block which determines a time constant of the carrier signal, and an initiation block which resets the time constant given by the time constant setting block.

Claims

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

an inverter controller generating a carrier signal for pulse width modulation and a lamp driving signal having on-time and off-time by pulse width modulating a dimming signal based on the carrier signal and controlling the on-time of the lamp driving signal in response to at least one of a vertical synchronization signal and a vertical synchronization start 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 inverter controller includes a control block which generates the carrier signal and the lamp driving signal, a time constant setting block which determines a time constant of the carrier signal, and an initiation block which resets the time constant given by the time constant setting block whenever pulses of the vertical synchronization signal are generated.

2. The inverter of claim 1, wherein the liquid crystal display comprises a signal controller for providing the vertical synchronization signal and the vertical synchronization start signal and the dimming signal is provided from the signal controller or an external device.

3. The inverter of claim 1, wherein the time constant setting block comprises a resistor and a capacitor connected between the dimming signal and a ground and provides a signal at a node between the resistor and the capacitor to the control block.

4. The inverter of claim 3, wherein the initiation block comprises a transistor having a collector connected to the node between the resistor and the capacitor of the time constant setting block, a grounded emitter, and a based supplied with the vertical synchronization signal via a resistor, the transistor turned on by the pulses of the vertical synchronization signal.

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

an inverter controller generating a carrier signal for pulse width modulation and a lamp driving signal having on-time and off time by pulse width modulating a dimming signal based on the carrier signal and controlling the on-time of the lamp driving signal in response to at least one of a vertical synchronization signal and a vertical synchronization start signal, wherein the inverter controller comprises a control block for generating the first and the second carrier signals, the lamp driving signal, and the oscillating signal, first and second time constant setting blocks for determining time constant of the first and the second carrier signal, a first initiation block for resetting the time constant given by the first time constant setting block whenever pulses of the vertical synchronization signal are generated, and a second initiation block for resetting the time constant given by the second time constant setting block whenever pulses of the horizontal synchronization signal are generated;

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.

6. The inverter of claim 5, wherein the first time constant setting block comprises a resistor and a capacitor connected between the dimming signal and a ground and provides a signal at a node between the resistor and the capacitor to the control block as the first carrier signal.

7. The inverter of claim 6, wherein the first initiation block comprises a transistor having a collector connected to the node between the resistor and the capacitor of the time constant setting block, a grounded emitter, and a based supplied with the vertical synchronization signal via a resistor, the transistor turned on by the pulses of the vertical synchronization signal.

8. The inverter of claim 5, wherein the second 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 as the second carrier signal.

9. The inverter of claim 8, 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.