Backlight unit comprising first and second white color coordinates belonging to different white color coordinate areas, display device having the same, and method of manufacturing the same

• US 9,835,903 B2
• Filed: 05/27/2015
• Issued: 12/05/2017
• Est. Priority Date: 11/05/2014
• 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, Eui Jeong, Kim, Youra, Kim, Hyun-Jeong
• Primary Examiner(s): Lee, Paul
• Application Number:
  US14/722,943
• Publication Number:
  US 20160124271A1
• Time in Patent Office: 923 Days
• CPC Class Codes: G02F 1/133602 Direct backlight
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination

Abstract

A backlight unit that includes a light source driving substrate and first and second light source units connected to the light source driving substrate. The first light source unit includes first and second light sources respectively emitting a first light having a first color and a second light having a second color. The second light source unit may include third and fourth light sources respectively emitting a third light having the first color and a fourth light having the second color. The first light source unit emits a first white color light having a first white color coordinate by mixing the first light and the second light and the second light source unit emits a second white color light having a second white color coordinate by mixing the third light and the fourth light. The first and second white color coordinates belong to different white color coordinate areas.

Claims

1. A backlight unit, comprising:

a light source driving substrate;

a first light source unit connected to the light source driving substrate; and

a second light source unit connected to the light source driving substrate, wherein the first light source unit comprises a first light source emitting a first light having a first color and a second light source emitting a second light having a second color, the second light source unit comprises a third light source emitting a third light having the first color and a fourth light source emitting a fourth light having the second color, the first light source unit emits a first white color light having a first white color coordinate, which is obtained by mixing the first light and the second light, the second light source unit emits a second white color light having a second white color coordinate, which is obtained by mixing the third light and the fourth light, the first and second white color coordinates belong to different white color coordinate areas, wherein a color coordinate area of the first color is defined in an area on a CIE color coordinate system corresponding to the first color and classified into a plurality of first color coordinate ranks, a color luminous intensity of the first color is classified into a plurality of first color luminous intensity ranks, and the first and the third light sources belong to different first color ranks among a plurality of first color ranks classified in accordance with the first color coordinate ranks and the first color luminous intensity ranks.

2. The backlight unit of claim 1, wherein a color coordinate area of the second color is defined in an area on the CIE color coordinate system corresponding to the second color and classified into a plurality of second color coordinate ranks, a color luminous intensity of the second color is classified into a plurality of second color luminous intensity ranks, and the second and the fourth light sources belong to different second color ranks among a plurality of second color ranks classified in accordance with the second color coordinate ranks and the second color luminous intensity ranks.

3. The backlight unit of claim 1, wherein the first and second light source units are alternately arranged with each other.

4. The backlight unit of claim 1, further comprising a third light source unit connected to the light source driving substrate, wherein the third light source unit comprises a fifth light source emitting a fifth light having the first color and a sixth light source emitting a sixth light having the second color, the third light source unit emits a third white color light having a third white color coordinate, which is obtained by mixing the fifth and sixth lights, and the first, second, and third white color coordinates belong to different color coordinate areas.

5. The backlight unit of claim 4, wherein the third white color coordinate belongs to substantially the same color coordinate as an average color coordinate of the first and second white color coordinates.

16. The backlight unit of claim 3, wherein the first light source is spaced apart from the second light source by a first distance, the third light source is spaced apart from the fourth light source by the first distance, the first light source unit is spaced apart from the second light source unit in the row direction by a second distance, the second light source unit is spaced apart from the first light source unit in the column direction by a third distance, the first distance is set to be smaller than each of the second and third distances.

17. The backlight unit of claim 1, wherein a number of light sources arranged within the second light source unit is equal to a number of light sources arranged within the first light source unit.

19. The backlight of claim 1, wherein a difference in color coordinate of the first light source and the third light source amounting to no more than a variation in Cy of 0.05 and a variation in Cx of 0.03 in the CIE color coordinate system.

6. A display device, comprising:

a display panel displaying an image; and

a backlight unit providing a light to the display panel, the backlight unit comprising;

a light source driving substrate;

a first light source unit connected to the light source driving substrate; and

a second light source unit connected to the light source driving substrate, wherein the first light source unit comprises a first light source emitting a first light having a first color and a second light source emitting a second light having a second color, the second light source unit comprises a third light source emitting a third light having the first color and a fourth light source emitting a fourth light having the second color, the first light source unit emits a first white color light having a first white color coordinate, which is obtained by mixing the first light and the second light, the second light source unit emits a second white color light having a second white color coordinate, which is obtained by mixing the third light and the fourth light, the first and second white color coordinates belong to different color coordinate areas, wherein the first color is a yellow color and the second color is a blue color, and wherein the backlight unit is operated in the time division scheme in synchronization with a first field and a second field, which are obtained by timely dividing a frame, the first and third light sources respectively emit the first and third lights during the first field, and the second and fourth light sources respectively emit the second and fourth lights during the second field.

7. The display device of claim 6, wherein the display panel comprises a first pixel comprising a first color filter having a third color, a second pixel comprising a second color filter having a fourth color, and a third pixel comprising a transmission part.

8. The display device of claim 7, wherein the first color is obtained by mixing the third and fourth colors.

9. A method of manufacturing a backlight unit, comprising:

providing a plurality of first color light sources and a plurality of second color light sources;

classifying the first color light sources into a plurality of first color ranks classified in accordance with a plurality of first color coordinate ranks and a plurality of first color luminous intensity ranks;

classifying the second color light sources to a plurality of second color ranks classified in accordance with a plurality of second color coordinate ranks and a plurality of second color luminous intensity ranks;

combining the first color light sources emitting a light having a first color with the second color light sources emitting a light having a second color according to a combination of the first and the second color ranks to form a plurality of light source units;

determining a color coordinate of the light source units;

classifying the light source units into at least two white ranks in accordance with the color coordinate of each of the light source units; and

arranging the light source units on a light source driving substrate to allow the light source units belonging to different white ranks to be alternately arranged with each other, wherein a color coordinate area of the first color is defined in an area on a CIE color coordinate system corresponding to the first color and classified into the first color coordinate ranks, a color luminous intensity of the first color is classified into the first color luminous intensity ranks, and a color coordinate area of the second color is defined in an area on the CIE color coordinate system corresponding to the second color and classified into the second color coordinate ranks, a color luminous intensity of the second color is classified into the second color luminous intensity ranks.

10. The method of claim 9, wherein the color coordinate of the light source units is determined with reference to a combination table, and the combination table comprises information about white color coordinates according to the combination of the first color ranks and the second color ranks.

11. The method of claim 10, wherein the color coordinate of the light source units is determined by comparing information about the first and the second color ranks of the first and second color light sources, which respectively belong to the light source units, with the combination table.

12. The method of claim 9, wherein the at least two white ranks comprise a first white rank and a second white rank, first light source units belonging to the first white rank among the light source units emit a first white color light having a first white color coordinate, second light source units belonging to the second white rank among the light source units emit a second white color light having a second white color coordinate, and the first and second white color coordinates belong to different color coordinate areas.

13. The method of claim 12, wherein the two white ranks further comprise a third white rank, third light source units belonging to the third white rank among the light source units emit a third white color light having a third white color coordinate, and the third white color coordinate belongs to a color coordinate area different from the first and second white color coordinates.

14. The method of claim 13, wherein the third color coordinate belongs to substantially the same color coordinate area as an average color coordinate of the first and second white color coordinates.

15. The method of claim 14, wherein the first, second, and third light source units are alternately arranged with each other.

18. The method of claim 12, wherein a number of light sources arranged within the second light source unit is equal to a number of light sources arranged within the first light source unit.