STEREOSCOPIC IMAGE DISPLAY AND METHOD OF CONTROLLING BACKLIGHT THEREOF

• US 20120013601A1
• Filed: 12/10/2010
• Published: 01/19/2012
• Est. Priority Date: 07/14/2010
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: PARK, Joonyoung, Park, Jaewoo, Kim, Jeongki
• Granted Patent: US 9,618,758 B2
• Time in Patent Office: Days
• US Class Current: 345/419
• CPC Class Codes: G02B 30/24 involving temporal multiplexing, e.g. using sequentially activated left and right shutters
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/003 to produce spatial visual effects
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H04N 13/341 using temporal multiplexing
• CPC Class Codes: H04N 13/398 Synchronisation thereof; Control thereof

Abstract

A stereoscopic image display device comprises a frame rate conversion unit that divides 3D input data into left eye image data and right eye image data, inserts reset frame data containing black grayscale data between the left eye image data and the right eye image data, and generates the (n+1)-th frame data to the (n+4)-th frame data containing the left eye image data, the black grayscale data, the right eye image data, respectively, and the black grayscale data, a look-up table that stores local dimming values used to control brightness for the overall local dimming zones to the minimum during the (n+2)-th and (n+4)-th frame periods, and local dimming values used to control brightness for each local dimming zone to target brightness during the (n+1)-th and (n+3)-th frame periods, and a backlight controller that controls light source brightness of the backlight unit for each local dimming zone.

Claims

1. A stereoscopic image display device comprising:

a liquid crystal display panel where frame data is addressed in an order of a (n+1)-th (where n is a positive integer) frame data to a (n+4)-th frame data;

a backlight unit of which an emission surface is divided into local dimming zones which can be controlled in brightness and which provides light to the liquid crystal display panel;

a frame rate conversion unit that divides 3D input data into left eye image data and right eye image data, inserts reset frame data containing black grayscale data between the left eye image data and the right eye image data, and thereby generates the (n+1)-th frame data containing the left eye image data, the (n+2)-th frame data containing the black grayscale data, the (n+3)-th frame data containing the right eye image data, and the (n+4)-th frame data containing the black grayscale data;

a local dimming value selection unit that selects local dimming value used to control brightness for the overall local dimming zones to the minimum during the (n+2)-th and (n+4)-th frame periods, and local dimming values used to control brightness for each local dimming zone to target brightness for the left eye image data or the right eye image data during the (n+1)-th and (n+3)-th frame periods;

a backlight controller that controls light source brightness of the backlight unit for each local dimming zone of the backlight unit, depending on the local dimming values output from the local dimming value selection unit.

2. The stereoscopic image display device of claim 1, wherein the local dimming zone has the size of one pixel of the liquid crystal display panel.

3. The stereoscopic image display device of claim 1, wherein the local dimming zone has the size of a block larger than one pixel of the liquid crystal display panel and smaller than a display screen of the liquid crystal display panel.

4. The stereoscopic image display device of claim 1, further comprising a look-up table that stores the local dimming values.

5. The stereoscopic image display device of claim 4, wherein the look-up table stores the local dimming values in addresses indicated by pre-previous frame data and current frame data, and the look-up table outputs local dimming values by comparing the pre-previous frame data and the current frame data inputted from the local dimming value selection unit.

6. The stereoscopic image display device of claim 5, wherein the local dimming value selection unit inputs an average value of pixel data in each block, to the look-up table, as the pre-previous frame data and current frame data.

7. The stereoscopic image display device of claim 4, wherein, the look-up table is divided into a 2D look-up table for storing the local dimming values for 2D images and a 3D look-up table for storing the local dimming values for 3D images.

8. The stereoscopic image display device of claim 1, wherein, the ratio of the turned-on to turned-off of the backlight unit during one frame period is adjusted depending on the local dimming value selected by the local dimming value selection unit.

9. The stereoscopic image display device of claim 1, wherein, the backlight unit is turned off depending on the local dimming value selected by the local dimming value selection unit during the (n+2)-th and (n+4)-th frame periods.

10. The stereoscopic image display device of claim 1, wherein the backlight unit is one of a direct type LED backlight unit, a field emission backlight unit and an OLED backlight unit.

11. The stereoscopic image display device of claim 1, further comprises shutter glasses having a left eye shutter which transmits light for an left eye image from the liquid crystal display panel and a right eye shutter which transmits light for a right eye image from the liquid crystal display panel.

12. A backlight control method of a stereoscopic image display device having a liquid crystal display panel where frame data is addressed in an order of a (n+1)-th (where n is a positive integer) frame data to a (n+4)-th frame data, and a backlight unit of which an emission surface is divided into local dimming zones which can be controlled in brightness and which provides light to the liquid crystal display panel, the method comprising:

dividing 3D input data into left eye image data and right eye image data, inserting reset frame data containing black grayscale data between the left eye image data and the right eye image data, and thereby generating the (n+1)-th frame data containing the left eye image data, the (n+2)-th frame data containing the black grayscale data, the (n+3)-th frame data containing the right eye image data, and the (n+4)-th frame data containing the black grayscale data;

controlling brightness for the overall local dimming zones to the minimum during the (n+2)-th and (n+4)-th frame periods; and

controlling brightness for each local dimming zone to target brightness for the left eye image data or the right eye image data during the (n+1)-th and (n+3)-th frame periods.

13. The backlight control method of claim 12, wherein the local dimming zone has the size of one pixel of the liquid crystal display panel.

14. The backlight control method of claim 12, wherein the local dimming zone has the size of a block larger than one pixel of the liquid crystal display panel and smaller than a display screen of the liquid crystal display panel.