Collimation backlight source, display device and driving method thereof

1. A collimation backlight source comprising:

a light guide plate with a surface and a lateral side adjacent to the surface;

a plurality of light sources of different colors at the lateral side;

a light-extraction grating assembly in each of a plurality of light-extraction regions on the surface of the light guide plate,

wherein the light-extraction grating assembly includes a third light-extraction grating in each light-extraction region; periods of the third light-extraction gratings in all the light-extraction regions are the same,

wherein the collimation backlight source further includes a second buffer layer covering the third light-extraction grating; a refractive index of the second buffer layer is less than a refractive index of the light guide plate,

wherein, for each light-extraction region, the third light-extraction grating directly projects by diffraction, the light rays of a certain color transmitted in the light guide plate at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface by diffraction, and projects the light rays of other color transmitted in the light guide plate at a diffraction angle greater than 0°,

wherein the light-extraction grating assembly further includes a plurality of fourth light-extraction gratings in each light-extraction region; the fourth light-extraction gratings are on the second buffer layer and at a light-emitting side of the third light-extraction grating,

wherein periods of the fourth light-extraction gratings in each light-extraction region are different; the third light-extraction grating is a step grating, and the fourth light-extraction grating is a step grating, and

wherein the fourth light-extraction gratings in each light-extraction region sequentially diffract by diffraction, the light rays of other colors projected at a diffraction angle greater than 0° by the third light-extraction grating, and project the light rays of other colors onto preset irradiation areas.

2. The collimation backlight source according to claim 1 , wherein each light-extraction region includes a plurality of spaced light-extraction sub-regions,

wherein the light-extraction grating assembly includes a first light-extraction grating set in each light-extraction sub-region; the collimation backlight source further includes a first buffer layer covering the first light-extraction grating set; a refractive index of the first buffer layer is less than a refractive index of the light guide plate,

wherein the first light-extraction grating set in each light-extraction sub-region includes:

a first electrode and a second electrode on the light guide plate; wherein the first electrodes of adjacent two light-extraction sub-regions are insulated from each other;

a first light-extraction grating on the first electrode or the second electrode; wherein the first light-extraction grating is between the first electrode and the second electrode, and the first light-extraction grating is a step grating; and

first liquid crystal filled between the first electrode and the second electrode,

wherein when the refractive index of the first light-extraction grating is the same as the refractive index of the first liquid crystal, the first light-extraction grating is in a light transmission state, and

wherein for one light-extraction sub-region, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, for any two light-extraction sub-regions in the same light-extraction region, the first light-extraction gratings in the two light-extraction sub-regions project light rays of different colors transmitted in the light guide plate by diffraction.

3. The collimation backlight source according to claim 2 , wherein for each light-extraction region, periods of the first light-extraction gratings in all the light-extraction sub-regions are different, and

wherein for each light-extraction sub-region, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, the first light-extraction grating directly projects the light rays of a certain color transmitted in the light guide plate at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface by diffraction.

4. The collimation backlight source according to claim 2 , wherein for each light-extraction region, periods of the first light-extraction gratings in all the light-extraction sub-regions are the same, and

wherein for one of the light-extraction sub-regions, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, the first light-extraction grating directly projects the light rays of a certain color transmitted in the light guide plate at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface by diffraction; for other ones of the light-extraction sub-regions, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, the first light-extraction grating projects the light rays of other color transmitted in the light guide plate at a diffraction angle greater than 0° by diffraction.

5. The collimation backlight source according to claim 4 , wherein the light-extraction grating assembly further includes a second light-extraction grating set in each light-extraction region; the second light-extraction grating set is on the first buffer layer and is at a light-emitting side of the first light-extraction grating set,

wherein the second light-extraction grating set in each light-extraction region includes a plurality of second light-extraction gratings; periods of the second light-extraction gratings are different; the second light-extraction gratings are in other ones of the light-extraction sub-regions in a one-to-one manner; the light rays projected at a diffraction angle greater than 0° by the first light-extraction grating in corresponding light-extraction sub-region, are further diffracted by the second light-extraction grating by diffraction and are projected at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface, and

wherein the second light-extraction grating is a step grating.

6. The collimation backlight source according to claim 2 , wherein the first light-extraction grating is composed of a plurality of light-transmission stripes arranged at equal intervals, and space between two adjacent light-transmission stripes is transparent.

7. The collimation backlight source according to claim 2 , wherein in the first light-extraction grating set in each light-extraction sub-region, the first light-extraction grating is in the first liquid crystal.

8. The collimation backlight source according to claim 1 , wherein the light-extraction grating assembly in each light-extraction region is on a light emitting surface of the light guide plate.

9. A display device comprising:

a display panel; and

a backlight source,

wherein the display panel includes a plurality of pixel regions; the display panel includes a cell defined by an array substrate and a color filter substrate, and second liquid crystal filled between the array substrate and the color filter substrate; each pixel region of the color filter substrate includes a light-shielding pattern and a light transmission region around the light-shielding pattern,

wherein the backlight source adopts the collimation backlight source according to claim 1 ; light-extraction regions of the backlight source are corresponding to positions of the pixel regions in a one-to-one manner,

wherein the display device further includes:

a controller configured to control the light sources of different colors in the backlight source to emit light rays, and control the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction; when the second liquid crystal corresponding to one light-extraction region is not deflected, control the light-extraction grating assembly in the one light-extraction region to project the light rays to a region where the light-shielding pattern of the corresponding pixel region on the color film substrate is located; when the second liquid crystal corresponding to one light-extraction region is deflected, the light rays projected by the light-extraction grating assembly in the one light-extraction region, are adjusted by the second liquid crystal and projected onto the light-transmission region of the corresponding pixel region on the color filter substrate, and then are emitted to a display side.

10. The display device according to claim 9 , wherein the light-extraction region includes a plurality of spaced light-extraction sub-regions; the pixel region includes a plurality of sub-pixel regions,

wherein the light-extraction grating assembly includes a first light-extraction grating set in each light-extraction sub-region, and

wherein the controller is configured to, by applying a voltage to a first electrode and a second electrode, control a refractive index of the first liquid crystal in one light-extraction sub-region to be different from a refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the one light-extraction sub-region to project light rays of a certain color transmitted in the light guide plate by diffraction; for any two light-extraction sub-regions in the same light-extraction region, control the first light-extraction gratings in the two light-extraction sub-regions to project light rays of different colors transmitted in the light guide plate by diffraction.

11. A driving method of the display device according to claim 9 , comprising:

controlling the light sources of different colors in the backlight source to sequentially emit light rays, and controlling the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction; when the second liquid crystal corresponding to one light-extraction region is not deflected, controlling the light-extraction grating assembly in the one light-extraction region to project the light rays to a region where the light-shielding pattern of the corresponding pixel region on the color film substrate is located; when the second liquid crystal corresponding to one light-extraction region is deflected, adjusting by the second liquid crystal, the light rays projected by the light-extraction grating assembly in the one light-extraction region, and projecting the adjusted light rays onto the light-transmission region of the corresponding pixel region on the color filter substrate for emitting adjusted light rays to a display side.

12. The driving method according to claim 11 , wherein controlling the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction, includes:

by applying a voltage to a first electrode and a second electrode, controlling a refractive index of the first liquid crystal in one light-extraction sub-region to be different from a refractive index of the first light-extraction grating, thereby controlling the first light-extraction grating in the one light-extraction sub-region to project light rays of a certain color transmitted in the light guide plate by diffraction; for any two light-extraction sub-regions in the same light-extraction region, controlling the first light-extraction gratings in the two light-extraction sub-regions to project light rays of different colors transmitted in the light guide plate by diffraction.

13. The driving method according to claim 12 , wherein the backlight sources include a red light source, a green light source and a blue light source; each light-extraction region includes a red-light-extraction sub-region, a green-light-extraction sub-region and a blue-light-extraction sub-region; each pixel region includes a red sub-pixel region, a green sub-pixel region and a blue sub-pixel region,

wherein a duration for displaying one frame picture includes a red-image display period, a green-image display period and a blue-image display period; the driving method specifically includes:

during the red-image display period in the duration for displaying one frame picture, controlling the red light source to emit light rays, controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region to be different from a refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the green-light-extraction sub-region and the blue-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the red-light-extraction sub-region to project red light rays transmitted in the light guide plate by diffraction; meanwhile, controlling the second liquid crystal in the red sub-pixel region to deflect, thereby achieving corresponding grayscale display;

during the green-image display period in the duration for displaying one frame picture, controlling the green light source to emit light rays, controlling a refractive index of the first liquid crystal in the green-light-extraction sub-region to be different from the refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region and the blue-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the green-light-extraction sub-region to project green light rays transmitted in the light guide plate by diffraction; and

during the blue-image display period in the duration for displaying one frame picture, controlling the blue light source to emit light rays, controlling a refractive index of the first liquid crystal in the blue-light-extraction sub-region to be different from the refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region and the green-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the blue-light-extraction sub-region to project blue light rays transmitted in the light guide plate by diffraction.

14. A collimation backlight source comprising:

a light guide plate with a surface and a lateral side adjacent to the surface;

a plurality of light sources of different colors at the lateral side;

a light-extraction grating assembly in each of a plurality of light-extraction regions on the surface of the light guide plate, each light-extraction region including a plurality of spaced light-extraction sub-regions,

wherein the light-extraction grating assembly includes a first light-extraction grating set in each light-extraction sub-region; the collimation backlight source further includes a first buffer layer covering the first light-extraction grating set; a refractive index of the first buffer layer is less than a refractive index of the light guide plate,

wherein the first light-extraction grating set in each light-extraction sub-region includes:

a first electrode and a second electrode on the light guide plate; wherein the first electrodes of adjacent two light-extraction sub-regions are insulated from each other;

a first light-extraction grating on the first electrode or the second electrode; wherein the first light-extraction grating is between the first electrode and the second electrode, and the first light-extraction grating is a step grating; and

first liquid crystal filled between the first electrode and the second electrode,

wherein when the refractive index of the first light-extraction grating is the same as the refractive index of the first liquid crystal, the first light-extraction grating is in a light transmission state,

wherein for one light-extraction sub-region, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, for any two light-extraction sub-regions in the same light-extraction region, the first light-extraction gratings in the two light-extraction sub-regions project light rays of different colors transmitted in the light guide plate by diffraction,

wherein for each light-extraction region, periods of the first light-extraction gratings in all the light-extraction sub-regions are the same,

wherein for one of the light-extraction sub-regions, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, the first light-extraction grating directly projects the light rays of a certain color transmitted in the light guide plate at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface by diffraction; for other ones of the light-extraction sub-regions, when the refractive index of the first light-extraction grating is different from the refractive index of the first liquid crystal, the first light-extraction grating projects the light rays of other color transmitted in the light guide plate at a diffraction angle greater than 0° by diffraction,

wherein the light-extraction grating assembly further includes a second light-extraction grating set in each light-extraction region; the second light-extraction grating set is on the first buffer layer and is at a light-emitting side of the first light-extraction grating set,

wherein the second light-extraction grating set in each light-extraction region includes a plurality of second light-extraction gratings; periods of the second light-extraction gratings are different; the second light-extraction gratings are in other ones of the light-extraction sub-regions in a one-to-one manner; the light rays projected at a diffraction angle greater than 0° by the first light-extraction grating in corresponding light-extraction sub-region, are further diffracted by the second light-extraction grating by diffraction and are projected at a diffraction angle of 0° to a corresponding irradiation area of the light receiving surface, and

wherein the second light-extraction grating is a step grating.

15. A driving method of a display device, wherein the display device comprises a display panel and a backlight source; the display panel includes a plurality of pixel regions; the display panel includes a cell defined by an array substrate and a color filter substrate, and second liquid crystal filled between the array substrate and the color filter substrate; each pixel region of the color filter substrate includes a light-shielding pattern and a light transmission region around the light-shielding pattern,

wherein the backlight source adopts a collimation backlight source, the collimation backlight source includes a light guide plate with a surface and a lateral side adjacent to the surface; a plurality of light sources of different colors at the lateral side; and a light-extraction grating assembly in each of a plurality of light-extraction regions on the surface of the light guide plate; light-extraction regions of the backlight source are corresponding to positions of the pixel regions in a one-to-one manner,

wherein the display device further includes a controller configured to control the light sources of different colors in the backlight source to emit light rays, and control the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction; when the second liquid crystal corresponding to one light-extraction region is not deflected, control the light-extraction grating assembly in the one light-extraction region to project the light rays to a region where the light-shielding pattern of the corresponding pixel region on the color film substrate is located; when the second liquid crystal corresponding to one light-extraction region is deflected, the light rays projected by the light-extraction grating assembly in the one light-extraction region, are adjusted by the second liquid crystal and projected onto the light-transmission region of the corresponding pixel region on the color filter substrate, and then are emitted to a display side,

wherein the driving method comprises controlling the light sources of different colors in the backlight source to sequentially emit light rays, and controlling the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction; when the second liquid crystal corresponding to one light-extraction region is not deflected, controlling the light-extraction grating assembly in the one light-extraction region to project the light rays to a region where the light-shielding pattern of the corresponding pixel region on the color film substrate is located; when the second liquid crystal corresponding to one light-extraction region is deflected, adjusting by the second liquid crystal, the light rays projected by the light-extraction grating assembly in the one light-extraction region, and projecting the adjusted light rays onto the light-transmission region of the corresponding pixel region on the color filter substrate for emitting adjusted light rays to a display side,

wherein controlling the light-extraction grating assembly in each light-extraction region to project light rays of all colors transmitted in the light guide plate by diffraction, includes by applying a voltage to a first electrode and a second electrode, controlling a refractive index of the first liquid crystal in one light-extraction sub-region to be different from a refractive index of the first light-extraction grating, thereby controlling the first light-extraction grating in the one light-extraction sub-region to project light rays of a certain color transmitted in the light guide plate by diffraction; for any two light-extraction sub-regions in the same light-extraction region, controlling the first light-extraction gratings in the two light-extraction sub-regions to project light rays of different colors transmitted in the light guide plate by diffraction,

wherein the backlight sources include a red light source, a green light source and a blue light source; each light-extraction region includes a red-light-extraction sub-region, a green-light-extraction sub-region and a blue-light-extraction sub-region; each pixel region includes a red sub-pixel region, a green sub-pixel region and a blue sub-pixel region,

wherein a duration for displaying one frame picture includes a red-image display period, a green-image display period and a blue-image display period; the driving method specifically includes:

during the red-image display period in the duration for displaying one frame picture, controlling the red light source to emit light rays, controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region to be different from a refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the green-light-extraction sub-region and the blue-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the red-light-extraction sub-region to project red light rays transmitted in the light guide plate by diffraction; meanwhile, controlling the second liquid crystal in the red sub-pixel region to deflect, thereby achieving corresponding grayscale display;

during the green-image display period in the duration for displaying one frame picture, controlling the green light source to emit light rays, controlling a refractive index of the first liquid crystal in the green-light-extraction sub-region to be different from the refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region and the blue-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the green-light-extraction sub-region to project green light rays transmitted in the light guide plate by diffraction; and

during the blue-image display period in the duration for displaying one frame picture, controlling the blue light source to emit light rays, controlling a refractive index of the first liquid crystal in the blue-light-extraction sub-region to be different from the refractive index of light-transmission stripes of the first light-extraction grating while controlling a refractive index of the first liquid crystal in the red-light-extraction sub-region and the green-light-extraction sub-region to be the same as the refractive index of light-transmission stripes of the first light-extraction grating, thereby controlling the first light-extraction grating in the blue-light-extraction sub-region to project blue light rays transmitted in the light guide plate by diffraction.