Liquid crystal display having gray voltages with varying magnitudes and driving method thereof

• US 7,109,984 B2
• Filed: 09/25/2002
• Issued: 09/19/2006
• Est. Priority Date: 09/27/2001
• Status: Active Grant

• Current Assignee: TCL China Star Optoelectronics Technology Co. Ltd. (TCL Technology Group Corp.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Moon, Seung-Hwan
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US10/255,903
• Publication Number:
  US 20030058235A1
• Time in Patent Office: 1,455 Days
• Field of Search: 345 76- 98, 345204-215, 345690-699, 245690-699
• US Class Current: 345/212
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A liquid crystal display (“LCD”) having a plurality of gray voltages with varying magnitudes and a driving method thereof. An LCD includes a reference voltage generator changing level of a supply voltage based on a first signal to generate a reference voltage. The first signal varies depending on the surrounding brightness of the LCD, the brightness of the on-screen images of the LCD, and user'"'"'s manipulation. The LCD also includes a gray voltage generator generating a plurality of gray voltages with magnitudes varying dependent on the magnitude of the reference voltage and a predetermined voltage such as a ground voltage. The LCD further includes a plurality of gate lines transmitting a plurality of gate signals, a plurality of data lines transmitting the gray voltages, and a plurality of pixels. Each pixel has a switching element connected to one of the gate lines and one of the data lines and transmitting the gray voltages to the pixels under the control of the gate signal. The LCD includes a gate driver supplying the gate signals to the gate lines and a data driver selecting the gray voltages based on gray data from an external source to supply to the pixels via the data lines.

Claims

1. A liquid crystal display comprising:

a reference voltage generator changing level of a first predetermined voltage based on a first signal to generate a reference voltage, the first signal varying depending on one of brightness of surroundings of the liquid crystal display, brightness of on-screen images of the liquid crystal display, and a users s manipulation; and

a gray voltage generator generating a plurality of gray voltages with magnitudes depending on a magnitude of the reference voltage and a second predetermined voltage,

wherein the reference voltage generator comprises resistor to change level of the first predetermined voltage based on the first signal.

2. The liquid crystal display of claim 1, further comprising:

a plurality of first signal lines, a plurality of second signal lines and a plurality of pixels connected to the first and the second signal lines; and

a first driver selecting the gray voltages based on gray data from an external source to supply to the pixels via the first signal lines.

3. The liquid crystal display of claim 2, further comprising a second driver supplying second signals to the second signal lines, each pixel including a switching element connected to one of the first signal lines and one of the second signal lines and transmitting the gray voltages to the pixels under the control of the second signals.

4. The liquid crystal display of claim 3, wherein the reference voltage generator comprises a first voltage divider dropping level of a third predetermined voltage for turning on the switching elements to generate the first signal.

5. The liquid crystal display of claim 2, further comprising a common voltage generator generating a common voltage to be applied to the pixels, based on the reference voltage.

6. The liquid crystal display of claim 1, wherein the gray voltage generator comprises a voltage divider connected between the reference voltage and the second predetermined voltage.

7. The liquid crystal display of claim 6, wherein the voltage divider comprises first and second series of resistors connected in series, and the first series of resistors is connected to the reference voltage while the second series of resistors is connected to the second predetermined voltage, the magnitudes of the gray voltages determined by magnitudes of the reference voltage and the second predetermined voltage and resistances of the first and the second series of resistors.

8. The liquid crystal display of claim 7, wherein the reference voltage generator comprises a transistor having a first terminal coupled to the tat signal, a second terminal coupled to the first predetermined voltage, and a third terminal outputting the reference voltage.