Liquid crystal display

• US 20080158267A1
• Filed: 01/28/2008
• Published: 07/03/2008
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kang, Moon-Shik, Han, Song-Yi, Lee, Inn-Sung
• Granted Patent: US 8,169,390 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The present invention relates to a method of controlling luminance of a backlight based on a processed image data after receiving information of image data, in order to improve the visibility of moving picture. An inverter according to the present invention includes a first block generating a first luminance control signal with an analog value depending on the luminance control signal with a duty ratio depending on a synchronization signal. The luminance control signals generated by the respective blocks are synthesized luminance control signal. Accordingly, a liquid crystal display employing two backlight control methods can be provided. Thus, it is possible to remove the drag phenomenon of a screen and, at the same time, to improve the visibility for moving picture.

Claims

1-6. -6. (canceled)

7. A liquid crystal display comprising:

a liquid crystal panel assembly including a plurality of gate lines, a plurality of data lines crossing the gate lines, and a plurality of pixels electrically connected to the gate lines and the data lines;

a signal controller receiving image data and a synchronization signal from an external graphics source, generating a control signal for driving the liquid crystal panel assembly, and converting format of the image data;

a gate driver scanning the gate lines of the liquid crystal panel assembly by unit of horizontal scan period based on a gate voltage;

a data driver selecting gray voltages corresponding to the image data from the signal controller for respective data lines on the liquid crystal panel assembly;

an inverter generating a driving signal based on a base signal having a predetermined pulse duty ratio and an amplitude depending on a luminance distribution of the image data; and

a lamp having on and off states and intensity controlled in response to the driving signal from the inverter.

8. The liquid crystal display of claim 7, wherein the inverter comprises:

a first block generating a first luminance control signal having an amplitude determined by the luminance distribution of the image data;

a second block generating a second luminance control signal having the predetermined duty ratio determined by a frequency of the synchronization signal;

a synthesizer synthesizing the first luminance control signal and the second luminance control signal to generate the base signal;

a transistor circuit generating a current based on the base signal outputted from the synthesizer; and

a lamp driving unit generating the driving signal based on the current supplied from the transistor circuit.

9. The liquid crystal display of claim 8, wherein the first block counts the image data depending on the luminance distribution, calculates the number of the image data representing a predetermined luminance range from the counting, and generates the first luminance control signal by comparing the calculation with a data stored in a reference table.

10. The liquid crystal display of claim 9, wherein the first block counts and calculates the luminance distribution of the image data by unit of horizontal scan period.

11. The liquid crystal display of claim 8, wherein the first block employs an analog dimming control and the second block employs a pulse-width modulation dimming control.

12. The liquid crystal display of claim 7, further comprising a voltage generator generating gray voltages and gate voltages for driving the liquid crystal panel assembly.

13. A liquid crystal display comprising:

a liquid crystal panel assembly including a plurality of gate lines, a plurality of data lines crossing the gate lines, and a plurality of pixels electrically connected to the gate lines and the data lines;

a signal controller receiving image data and a synchronization signal from an external graphic source, generating a control signal for driving the liquid crystal panel assembly, and converting format of the image data;

a gate driver scanning the gate lines of the liquid crystal panel assembly by unit of horizontal scan period based on a gate voltage;

a data driver selecting gray voltages corresponding to the image data from the signal controller for respective data lines on the liquid crystal panel assembly;

an inverter generating a driving signal based on a base signal having a predetermined pulse duty ratio and an amplitude depending on a luminance distribution of the image data;

a light source having on and off states and intensity controlled in response to the driving signal from the inverter.

14. The liquid crystal display of claim 13, wherein a duration ratio of the on state and the off state of the light source is determined by the pulse duty ratio of the base signal.