Display apparatus with adjustable backlight unit and control method thereof

• US 20040008177A1
• Filed: 05/15/2003
• Published: 01/15/2004
• Est. Priority Date: 07/10/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ahn, Yoon-Soon
• Granted Patent: US 7,289,098 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A display apparatus having a backlight unit whose brightness is adjusted according to input image signals. The display apparatus processes input image signals in order for them to be appropriate to a display characteristic in an image signal processing unit and outputs each chromatic signal, R, G, and B, related to a color configuration of the image signals, processed in the chromatic signal output unit. Then a display panel drives an image display screen according to each chromatic signal. Meanwhile, a chromatic averaging unit calculates average brightness of the input images from each chromatic signal to transfer to a controller. The controller controls an inverter through an inverter current limiting unit in order for currents provided to the backlight unit in the display panel, to be controlled according to the average brightness of the input images calculated in the chromatic signal averaging unit.

Claims

1. A display apparatus comprising;

an image signal processing unit for processing an input image signal of an input image in order to satisfy a display characteristic, thereby to produce a processed input image signal;

a chromatic signal output unit which is provided with the processed input image signal and which outputs a chromatic signal related to a color configuration of the input image;

a display panel for driving an image display screen according to the chromatic signal output from the chromatic signal output unit, having a backlight unit for providing illuminating light on the image display screen;

a chromatic signal averaging unit which is provided with the chromatic signal from the chromatic signal output unit and which calculates an average brightness of the input image from the chromatic signal;

an inverter for switching a current to the backlight unit included in the display panel;

an inverter current limiting unit for limiting the current provided to the backlight unit; and

a controller for controlling the inverter current limiting unit in order for an amount of the current provided to the backlight unit to be adjusted through the inverter according to the average brightness of the input image calculated in the chromatic signal averaging unit.

2. The display apparatus according to claim 1, wherein the chromatic signal comprises R, G, and B signals.

3. The display apparatus according to claim 1, wherein the controller controls the inverter current limiting unit in order for the amount of the current provided to the backlight unit in an inverse proportion to the average brightness of the input image transferred from the chromatic signal averaging unit, and within a predetermined range of brightness of the input image.

8. The display apparatus according to claim 3, wherein the average brightness is determined to be low when the average brightness is below a predetermined threshold level and the average brightness gets high when the average brightness is above the predetermined threshold level.

4. A method for controlling a display apparatus having a backlight unit, comprising the steps of;

(a) extracting a chromatic signal from an input image signal of an input image;

(b) calculating an average brightness of the input image using the extracted chromatic signal; and

(c) adjusting an amount of a current provided to the backlight according to the average brightness of the input image.

5. The method according to claim 4, wherein the chromatic signal comprises R, G, and B signals.

6. The method according to claim 4, wherein the step (c) controls the amount of the current provided to the backlight unit in an inverse proportion to the average brightness of the input image, and within a predetermined range of brightness of the input image.

9. The display apparatus according to claim 6, wherein the average brightness is determined to be low when the average brightness is below a predetermined threshold level and the average brightness gets high when the average brightness is above the predetermined threshold level.

7. A display apparatus comprising;

an image signal processing unit for processing an input image signal of an input image in order to satisfy a display characteristic thereby to produce a processed image signal;

a chromatic signal output unit which is provided with the processed input image signal and which outputs a chromatic signal related to a color configuration of the input image;

a display panel for driving an image display screen according to the chromatic signal output from the chromatic signal output unit, comprising a backlight unit for providing illuminating light on the image display screen;

a chromatic signal averaging unit which is provided with the chromatic signal from the chromatic signal output unit and which calculates an average brightness of the input image from the chromatic signal;

an inverter for switching a current to the backlight unit included in the display panel; and

an inverter current limiting unit for limiting the current provided to the backlight unit according to the average brightness of the input image calculated in the chromatic signal averaging unit.