DISPLAY APPARATUS AND METHOD OF DRIVING THE SAME

• US 20100245398A1
• Filed: 12/17/2009
• Published: 09/30/2010
• Est. Priority Date: 03/25/2009
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Amino, Tadashi
• Granted Patent: US 8,368,726 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/106 Determination of movement vectors or equivalent parameters within the image
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/2092 Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

Disclosed are a display apparatus and a method of driving the same. An image signal receiver sequentially outputs frames for image display. A local illumination calculation unit displays an image on a display unit based on the frames and calculates light emission amount of a light source provided for each section of a backlight unit. A frame interpolator generates sub-frames based on the frames and outputs the sub-frames and the frames. A pixel adjuster adjusts light transmittance of each pixel according to the brightness of each pixel and the amount of the light emitted from each section which is calculated by the local illumination calculation unit when the image is displayed based on the frames and the sub-frames sequentially output from a frame interpolator. Local illumination is realized without increasing the number of memory devices while a frame frequency is increased.

Claims

1. A display apparatus, comprising:

a backlight unit having a plurality of sections each generating a light;

a display unit having a plurality of pixels allowing the light to pass therethrough;

an image signal receiver receiving an image signal having a plurality of consecutive frames to sequentially output the frames;

a local illumination calculation unit calculating a target amount of the light generated from the sections based on a brightness of a (n+1)-th (n is an integer larger than

     1) frame of the frames;

a backlight controller controlling the backlight unit based on the calculated target amount of the light;

a frame interpolator generating at least one (n+1)-th sub-frame based on the (n+1)-th and an n-th frame previous to the (n+1)-th frame and sequentially outputting the (n+1)-th frame and the (n+1)-th sub-frame; and

a pixel adjuster adjusting a light transmittance of the pixels according to a pixel brightness of the (n+1)-th frame and the (n+1)-th sub-frame and the calculated target amount of the light.

2. The display apparatus of claim 1, wherein the local illumination calculation unit calculates the target amount of the light from the sections within a first period at which the image signal receiver outputs a frame.

3. The display apparatus of claim 2, wherein the pixel adjuster adjusts the pixel brightness of the (n+1)-th frame and the (n+1)-th sub-frame at a second period shorter than the first period.

4. The display apparatus of claim 1, wherein the frame interpolator outputs the (n+1)-th sub-frame between the (n+1)-th frame and an (n+2)-th frame next to the (n+1)-th frame.

5. The display apparatus of claim 4, wherein the frame interpolator comprises:

a difference value calculator calculating a difference value between the n-th frame and the (n+1)-th frame output from the image signal receiver; and

a sub-frame generator generating the (n+1)-th sub-frame by applying the calculated difference value to the (n+1)-th frame.

6. The display apparatus of claim 5, wherein the difference value calculator calculates a motion vector between the n-th and (n+1)-th frames as the difference value, and the sub-frame generator generates the (n+1)-th sub-frame by shifting positions of pixels in the (n+1)-th frame along a direction of the motion vector calculated by the difference value calculator.

7. The display apparatus of claim 6, wherein the frame interpolator generates the (n+1)-th sub-frame equal to the (n+1)-th frame when no motion vector is calculated by the difference value calculator.

8. The display apparatus of claim 5, wherein the frame interpolator comprises two frame memories that store the n-th frame and the (n+1)-th frame, respectively, and

the local illumination calculation unit reads the (n+1)-th frame from one of the two frame memories to calculate the target amount of the light.

9. The display apparatus of claim 1, wherein the local illumination calculation unit comprises:

a distribution calculator calculating a brightness distribution of the pixels of the (n+1)-th frame with respect to each section;

a brightness calculator sequentially counting a number of pixels from a pixel having a darkest level based on the brightness distribution of the pixels with respect to each section, and calculates brightness when the number of the pixels exceeds a predetermined value;

a spatial adjuster calculating a weighted average of the brightness calculated for each section and brightness calculated for sections adjacent to the each section; and

a temporal adjuster that calculates a time average of the weighted average calculated with respect to each section.

10. The display apparatus of claim 1, wherein the pixel adjuster adjusts the transmittance of the (n+1)-th sub-frame according to pixel brightness of the (n+1)-th sub-frame and the target amount of the light calculated by the local illumination calculation unit based on the brightness of the (n+1)-th frame.

11. A method driving a display apparatus provided with a backlight unit having a plurality of sections each of which generates a light and a display unit having pixels that allow the light to pass therethrough, the method comprising:

receiving an image signal having consequentially a plurality of frames to sequentially output the frames;

generating at least one (n+1)-th (n is an integer larger than

     1) sub-frame to put the sub-frame between an (n+1)-th frame and an (n+2)-th frame;

calculating a target light amount of a plurality of sections generating a light based on a brightness of the (n+1)-th frame;

sequentially outputting the (n+1)-th frame and the (n+1)-th sub-frames while generating the light having the target light amount from the sections. and

adjusting a light transmittance of pixels of the display unit according to a pixel brightness of the (n+1)-th frame and the (n+1)-th sub-frame, and the target light amount from the sections.

12. The method of claim 11, wherein the (n+1)-th sub-frame is generated based on the (n+1)-th frame and an n-th frame previous to the (n+1)-th frame.

13. The method of claim 11, wherein the target amount of the light generated from the sections is calculated within a first period in which the image signal receiver outputs a frame.

14. The method of claim 11, wherein the light transmittance of the pixels is adjusted at a second period shorter than the first period.

15. The method of claim 11, wherein the (n+1)-th sub-frame is generated by calculating a difference value between the n-th frame and the (n+1)-th frame and applying the difference value to the (n+1)-th frame.

16. The method of claim 11, wherein the adjusting of the light transmittance comprises increasing a light transmittance of the pixels corresponding to each section according to a difference value between the target light amount and a maximum light amount generated from each section.

17. The method of claim 11, wherein the transmittance of the (n+1)-th sub-frame is adjusted according to the pixel brightness of the (n+1)-th sub-frame and the target light amount calculated based on the (n+1)-th frame.

18. The method of claim 11, wherein the (n+1)-th frame and the (n+1)-th sub-frames are displayed while an (n+2)-th frame next to the (n+1)-th frame is received.

19. A display apparatus, comprising:

a backlight unit having a plurality of sections each generating a light;

a display unit having a plurality of pixels allowing the light to pass therethrough;

an image signal receiver receiving an image signal having a plurality of consecutive frames to sequentially output the frames;

a frame interpolator generating at least one (n+1)-th sub-frame (n is an integer larger than

     1) and sequentially outputting an (n+1)-th frame and the (n+1)-th sub-frame;

a local illumination calculation unit calculating a target light amount generated from the sections based on a brightness of the (n+1)-th frame; and

a backlight controller controlling the backlight unit to generate the target amount of the light from the sections while the (n+1)-th frame and the (n+1)-th sub-frame are being displayed.

20. The display apparatus of claim 19, further comprising a pixel adjuster adjusting a light transmittance of the pixels of each of the (n+1)-th frame and the (n+1)-th sub-frame according to a pixel brightness of each of the (n+1)-th frame and the (n+1)-th sub-frame and the target light amount calculated based on the (n+1)-th frame.