DISPLAY PANEL CONTROL DEVICE, LIQUID CRYSTAL DISPLAY DEVICE, ELECTRONIC APPARATUS, AND DISPLAY PANEL DRIVE CONTROL DEVICE

• US 20090243995A1
• Filed: 03/30/2009
• Published: 10/01/2009
• Est. Priority Date: 03/31/2008
• Status: Active Grant

• Current Assignee: HannStar Display Corporation
• Original Assignee: NEC LCD Technologies Limited (NEC Corporation)
• Inventors: KIMURA, Hiroaki
• Granted Patent: US 8,264,451 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

To provide a display panel control device capable of improving gap of moving pictures, etc., without increasing the dividing number of the backlight. The device includes: a black image insertion driving part which performs, on a display panel, black image insertion drive in which video display scanning and black image display scanning are executed in a specific period; and a light-up timing control part which controls a light-up start timing and a light-off start timing of each light source block based on a synchronous signal which synchronizes with the start timing of the video display scanning or the black image display scanning. The light-off period of the light source block is equal to or less than a period from the end of black image display scanning performed on all display lines within a block area to the start of video scanning performed on the first display line within the area.

Claims

1. A display panel control device for controlling a display panel and a back-face light source which configures a plurality of light source blocks formed on a back face of the display panel in parallel to a line sequential scanning direction, the control device comprising:

a black image insertion driving part which starts video display scanning and black or dark image display scanning for the display panel, and performs black or dark image insertion drive in a specific period; and

a light-up timing control part which sets and controls a light-up and a light-off start timing of each of the plurality of light source blocks, based on a synchronous signal that synchronizes with a timing for starting the video display scanning or a timing for starting black or dark image display scanning performed by the black image insertion part, wherein

the light-up timing control part controls the setting of the light-up start timing or the light-off start timing so as to satisfy a period condition, i.e., a light-off period of a given light source block becomes equal to or less than a period from an end of the black or dark image display scanning on all display lines within a block area of the display panel corresponding to a given light source block to a start of the video scanning on the first display line within the block area.

2. The display panel control device as claimed in claim 1, wherein the light-up timing control part shifts the light-off start timing of each of the light source blocks from the start timing of the black or dark image display scanning by a specific period, while satisfying the period condition.

3. The display panel control device as claimed in claim 1, wherein, provided that driven line number of the display panel is “

Vtotal”

, scanning line number that is display line number of the display panel is “

Vdisp”

, dividing number of the divided light source blocks is “

N”

, a black image insertion rate in a frame period by the black image insertion driving part is “

Xp”

, and a light-off rate that is a ratio of the light-off period in the frame period is “

Xb”

, the light-up timing control part performs controls based on the light-off period and the number of blocks set according to the black image insertion rate, by satisfying a co-relational condition between the black image insertion rate Xp and the light-off rate Xb expressed as follows.

Xb≦

XP−

(Vdisp/N)/Vtotal

4. The display panel control device as claimed in claim 1, wherein:

the black image insertion driving part includes

a double-speed conversion control part which, when supplying a black image insertion signal that alternately contains a video part for displaying video in accordance with a video signal and a black or dark image part for displaying a black or dark display in accordance with a black or dark image signal to the display panel, performs controls to convert the video signal to that of k×

speed and divides one frame period into k-number of sub-frame periods, and

a black image insertion signal conversion part which inserts the black or dark image signal at least to one of the sub-frame periods; and

provided that driven line number of the display panel is “

Vtotal”

, display line number of the display panel is “

Vdisp”

, dividing number of the divided light source blocks is “

N”

, a black image insertion rate in a frame period by the black image insertion driving part is “

Xp”

, a light-off rate that is a ratio of the light-off period in the frame period is “

Xb”

, and number of sub-frame periods is “

k”

, the light-up timing control part performs controls based on the light-off period and the number of blocks set according to the black image insertion rate, by satisfying a co-relational condition between the black image insertion rate Xp and the light-off rate Xb expressed as follows.

Xb≦

Xp−

(Vdisp/kN)/Vtotal

5. The display panel control device as claimed in claim 3, wherein the light-up timing control part performs controls based on the light-off period and the number of blocks set according to the black image insertion rate, by having a practical black image insertion rate as “

Xp′

=Tp′

/Tv”

where a practical black image insertion period of the display panel is “

Tp′

” and

the frame period is “

Tv”

, and by having the practical light-off rate as “

Xb′

=Tb′

/Tv”

where the practical light-off period of the back-face light source is “

Tb′

” and

the frame period is “

Tv”

.

6. The display panel control device as claimed in claim 3, wherein the light-up timing control part drive-controls each of the light source blocks by dividing the blocks to satisfy “

N≧

6/k”

.

7. The display panel control device as claimed in claim 4, wherein the light-up timing control part drive-controls each of the light source blocks by dividing the blocks to satisfy “

N≦

6/k”

.

8. A liquid crystal display device, comprising:

a display panel in which a pixel is formed in each of intersection points between a plurality of gate lines and a plurality of source lines arranged in matrix;

a source line driving part which supplies, to each of the source lines, a black image inserted video signal which alternately contains a video part which displays video in accordance with a video signal and a black or dark image part which displays a black or dark display in accordance with a black or dark image signal;

a plurality of gate line driving parts which are provided to each of gate line groups (groups obtained by dividing the plurality of gate lines into groups), which sequentially supply a gate driving signal to the respective gate lines;

a light-up control part which performs controls to light up and off, by a unit of block, the plurality of light source blocks provided on the back face of the display panel in parallel to a line sequential scanning direction;

a backlight unit disposed in the back face of the display panel, which contains the plurality of light source blocks; and

the display panel control device as claimed in claim 1, which controls the light-up control part, the gate line driving part, and the source line driving part, wherein the backlight unit has a space part formed over each block boundary part between the light source blocks neighboring to each other.

9. The liquid crystal display device as claimed in claim 8, wherein:

the backlight unit has a projected part that is formed in the block boundary part of the light source blocks neighboring to each other by being protruded from a bottom part of the backlight unit; and

the space part is formed between a projection end part of the projected part and a top part of the backlight unit.

10. An electronic apparatus, comprising the liquid crystal display device claimed in claim 8 mounted as a display panel.

11. A display panel drive control method, comprising:

starting video display scanning and black or dark image display scanning for a display panel in a specific period, and performing black or dark image insertion drive; and

controlling setting of a light-up start timing and a light-off start timing of each of a plurality of light source blocks formed on a back-face part of the display panel in parallel to a line sequential scanning direction, based on a synchronous signal that synchronizes with a timing for starting the video display scanning or a timing for starting the black or dark image display scanning performed by the black image insertion driving step, wherein

when controlling setting of the light-up start timing and the light-off start timing of each of the plurality of light source blocks, the setting of the light-up start timing or the light-off start timing is controlled so as to satisfy a period condition, i.e., a light-off period of a given light source block becomes equal to or less than a period from an end of the black or dark image display scanning on all display lines within a block area of the display panel corresponding to the given light source block to a start of the video scanning on a first display line within the block area.

12. Display panel control means for controlling a display panel and a back-face light source which configures a plurality of light source blocks formed on a back face of the display panel in parallel to a line sequential scanning direction, the control means comprising:

black image insertion driving means for starting video display scanning and black or dark image display scanning for the display panel in a specific period, and performing black or dark image insertion drive; and

light-up timing control means for controlling setting of a light-up start timing and a light-off start timing of each of the plurality of light source blocks, based on a synchronous signal that synchronizes with a timing for starting the video display scanning or a timing for starting black or dark image display scanning performed by the black image insertion means, wherein

the light-up timing control means controls the setting of the light-up start timing or the light-off start timing so as to satisfy a period condition, i.e., a light-off period of a given light source block becomes equal to or less than a period from an end of the black or dark image display scanning on all display lines within a block area of the display panel corresponding to a given light source block to a start of the video scanning on the first display line within the block area.