CN111781769B

CN111781769B - Backlight assembly and liquid crystal display device

Info

Publication number: CN111781769B
Application number: CN201910891738.4A
Authority: CN
Inventors: 李登仟; 耿玉旭; 张超杰; 雷嗣军; 高亮; 孙艳生; 戴威; 李旭; 徐景华
Original assignee: BOE Technology Group Co Ltd; Chongqing BOE Optoelectronics Technology Co Ltd
Current assignee: BOE Technology Group Co Ltd; Chongqing BOE Optoelectronics Technology Co Ltd
Priority date: 2019-04-03
Filing date: 2019-09-20
Publication date: 2023-04-18
Anticipated expiration: 2039-09-20
Also published as: CN111781769A

Abstract

The embodiment of the invention provides a backlight assembly and a liquid crystal display device, relates to the technical field of liquid crystal display, and can realize peep-proof display without increasing the thickness of the liquid crystal display device. The backlight assembly includes: the light guide plate, set up the light source on the side of the light guide plate; the light source comprises a first sub-light source; the light emitting angle α of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is: alpha is more than or equal to 0 and less than or equal to 100 degrees; the bottom surface of the light guide plate comprises a plurality of grooves or bulges extending along a first direction, and the bottom surface of the light guide plate is opposite to the light-emitting surface of the light guide plate; the first direction is the long side direction of the light incident surface of the light guide plate; the side wall or the bulge of the groove comprises a reflecting surface, and light emitted by the light source is reflected by the reflecting surface and then is emitted from the light emitting surface of the light guide plate; backlight unit is still including setting up the prism piece in light guide plate play plain noodles one side, and the prism piece includes the substrate layer and sets up at a plurality of arriss peaks of substrate layer light guide plate one side dorsad, and the extending direction of arris peak is first direction, and the apex angle t of arris peak is: t is more than or equal to 150 degrees and less than 180 degrees.

Description

Backlight assembly and liquid crystal display device

The present application is continued on the basis of the priority of application No. 201910267788.5 entitled "a backlight assembly, a liquid crystal display device, and a control method thereof".

Technical Field

The invention relates to the technical field of liquid crystal display, in particular to a backlight assembly, a liquid crystal display device and a control method thereof.

Background

Liquid Crystal Display (LCD) devices are increasingly widely used because of their advantages such as low power consumption, miniaturization, and lightness and thinness. With the development of display technology, the requirements of users on the performance of liquid crystal display devices are higher and higher. Among them, with the increase of mobile office and open work environment and the popularization of high resolution display, users have more and more demands for privacy protection.

At present, because the liquid crystal display device has a larger luminous visual angle in space, the information peeping of the screen becomes easier and easier, and the safety of the information is affected. For example, for some users, they may read some confidential information in public places, and the liquid crystal display device may be seen by others around due to its large light-emitting viewing angle, which may cause inconvenience to the users.

Disclosure of Invention

Embodiments of the present invention provide a backlight assembly, a liquid crystal display device, and a control method thereof, which can implement a privacy display without increasing the thickness of the liquid crystal display device.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

in a first aspect, there is provided a backlight assembly including: the light source comprises a light guide plate and a light source arranged on the side face of the light guide plate; the light source comprises a first sub-light source; the light emitting angle alpha of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is as follows: alpha is more than or equal to 0 and less than or equal to 100 degrees; the bottom surface of the light guide plate comprises a plurality of grooves or bulges extending along a first direction, and the bottom surface of the light guide plate is opposite to the light-emitting surface of the light guide plate; the first direction is the long side direction of the light incident surface of the light guide plate; the side wall or the bulge of the groove comprises a reflecting surface, and the reflecting surface is used for emitting light emitted by the light source so that the reflected light can be emitted out of the light emitting surface of the light guide plate; the backlight module is characterized by further comprising a prism sheet arranged on one side of the light emergent surface of the light guide plate, the prism sheet comprises a base material layer and a plurality of ridges arranged on one side of the light guide plate, the base material layer faces away from the light emergent surface of the light guide plate, the extending direction of the ridges is the first direction, and the vertex angle t of the ridges is as follows: t is more than or equal to 150 degrees and less than 180 degrees.

Optionally, a light emitting angle α of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is 0 ° or more and 50 ° or less.

Optionally, the first sub-light source is a first light bar extending along a first direction, or the first sub-light source includes a plurality of first light-emitting elements arranged in sequence along the first direction.

Optionally, the number of the first light bars is two, and the first light bars are respectively arranged on two opposite side surfaces of the light guide plate; or the first light-emitting elements are arranged in two rows along the first direction and are respectively arranged on two opposite side surfaces of the light guide plate.

Optionally, a light emitting angle γ of the first sub-light source in a plane perpendicular to both the light emitting surface of the light guide plate and the light incident surface of the light guide plate is 0 ° or more and 180 ° or less.

Optionally, the first cross section of the edge peak is an isosceles triangle, and the first cross section is perpendicular to the first direction.

Optionally, the center-to-center distance L between adjacent ridges is: l is more than or equal to 0.02mm and less than or equal to 0.1mm.

Optionally, the thickness H of the prism sheet is: h is more than or equal to 0.05 and less than or equal to 0.3mm.

Optionally, the number of the prism sheets is plural, and the plural prism sheets are stacked in sequence.

Optionally, the light source further comprises a second sub-light source; the light emitting angle of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is smaller than the light emitting angle of the second sub-light source in a plane parallel to the light emitting surface of the light guide plate.

Optionally, a light emitting angle β of the second sub-light source in a plane parallel to the light emitting surface of the light guide plate is: beta is more than or equal to 60 degrees and less than or equal to 180 degrees.

Optionally, a light emitting angle β of the second sub-light source in a plane parallel to the light emitting surface of the light guide plate is 120 °.

Optionally, the light source comprises a plurality of bimorph LEDs; the plurality of bicrystal LEDs positioned on the same side face of the light guide plate are sequentially arranged along a first direction; one LED particle in the double-crystal LED is used as the first sub-light source, and the other LED particle in the double-crystal LED is used as the second sub-light source.

Optionally, the second sub-light source includes a second light bar extending along the first direction, or the second sub-light source includes a plurality of second light emitting elements sequentially arranged along the first direction.

In a second aspect, there is provided a liquid crystal display device comprising a liquid crystal display panel and the backlight assembly of the first aspect; the backlight assembly is used for providing a light source for the liquid crystal display panel.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related arts, the drawings used in the description of the embodiments or the related arts will be briefly introduced below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is a first schematic structural diagram of an lcd device according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an lcd panel according to an embodiment of the present invention;

fig. 3a is a first schematic bottom view of a backlight assembly according to an embodiment of the present invention;

FIG. 3b is a schematic cross-sectional view along AA in FIG. 3 a;

FIG. 3c is a cross-sectional view along direction AA in FIG. 3 a;

FIG. 3d is a schematic cross-sectional view along AA in FIG. 3 a;

fig. 4a is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

FIG. 4b is a schematic cross-sectional view along direction BB in FIG. 4 a;

fig. 5 is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a related art LCD device;

FIG. 7 is a graph of a relationship between a viewing angle and a brightness according to an embodiment of the present invention;

fig. 8 is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

fig. 9 is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

fig. 10a is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

fig. 10b is a schematic bottom view of a backlight assembly according to an embodiment of the present invention;

FIG. 11 is a first schematic view illustrating a structure of a backlight assembly according to an embodiment of the present invention;

fig. 12 is a second schematic structural diagram of a backlight assembly according to an embodiment of the present invention;

fig. 13 is a schematic bottom view illustrating a backlight assembly according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a backlight assembly according to a third embodiment of the present invention;

fig. 15 is a second schematic structural diagram of a liquid crystal display device according to an embodiment of the present invention;

FIG. 16 is a flowchart illustrating a method for controlling a liquid crystal display device according to an embodiment of the present invention;

fig. 17a is a schematic bottom view of a partial structure of a backlight assembly according to an embodiment of the present invention;

FIG. 17b is a schematic cross-sectional view along AA in FIG. 17 a;

FIG. 18 is a schematic diagram illustrating the specification of a prism sheet of the backlight assembly shown in FIG. 17 b;

FIG. 19a is a graph showing a relationship between luminance and a viewing angle of the backlight assembly in comparative example 1;

FIG. 19b is a graph showing a relationship between luminance and a viewing angle of the backlight assembly in comparative example 2;

fig. 19c is a graph showing the relationship between the luminance and the viewing angle of the backlight assembly in comparative example 3.

Reference numerals are as follows:

1-a frame; 2-cover plate glass; 3-a liquid crystal display panel; 4-a backlight assembly; 5-a circuit board; 10-an array substrate; 20-pair of cassette substrates; 30-a liquid crystal layer; 40-frame sealing glue; 41-a light guide plate; 42-a light source; 43-privacy film (switchable diffuser); 44-twin LEDs; 45-a reflective sheet; 50-an upper polarizer; 60-lower polaroid; 70-a controller; 100-a first substrate; 101-pixel electrodes; 102-a thin film transistor; 103-common electrode; 104-a first insulating layer; 105-a second insulating layer; 200-a second substrate; 201-a color filter layer; 202-black matrix pattern; 410-grooves (protrusions); 4101-sub-grooves (sub-protrusions); 411-a reflective surface; 420-a first sub-light source; 421-a second sub-light source; 422-flexible circuit board; 6. a prism sheet; 61. a substrate layer; 62. and (5) ridge peaks.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

An embodiment of the invention provides a liquid crystal display device, as shown in fig. 1, the main structure of the liquid crystal display device includes a frame 1, a cover glass 2, a liquid crystal display panel 3, a backlight assembly 4, a circuit board 5, and other electronic components.

The longitudinal section of the frame 1 is U-shaped, the liquid crystal display panel 3, the backlight assembly 4, the circuit board 5 and other electronic accessories are all arranged in the frame 1, the backlight assembly 4 is arranged below the liquid crystal display panel 3, the circuit board 5 is arranged below the backlight assembly 4, and the cover glass 2 is arranged on one side of the liquid crystal display panel 3 far away from the backlight assembly 4.

As shown in fig. 1 and 2, the liquid crystal display panel 3 includes an array substrate 10 and an opposing-to-cell substrate 20 which are oppositely disposed, and a liquid crystal layer 30 disposed between the array substrate 10 and the opposing-to-cell substrate 20. As shown in fig. 1, the array substrate 10 and the opposing substrate 20 are bonded together by the sealant 40, so that the liquid crystal layer 30 is limited in the region surrounded by the sealant 40.

As shown in fig. 2, the array substrate 10 includes a plurality of sub-pixels, each of which includes a pixel electrode 101 and a Thin Film Transistor (TFT) 102 disposed on a first substrate 100. The thin film transistor 102 includes a source electrode, a drain electrode, an active layer, a gate electrode, and a gate insulating layer, and the pixel electrode 101 is electrically connected to the drain electrode of the thin film transistor 102.

On this basis, in some embodiments, as shown in fig. 2, the array substrate 10 further includes a common electrode 103 disposed on the first substrate 100. Here, the pixel electrode 101 and the common electrode 103 may be disposed on the same layer, and in this case, the pixel electrode 101 and the common electrode 103 are each a comb-tooth structure including a plurality of strip-shaped sub-electrodes. The pixel electrode 101 and the common electrode 103 may also be provided at different layers, in which case the first insulating layer 104 is provided between the pixel electrode 101 and the common electrode 103 as shown in fig. 2. In the case where the common electrode 103 is provided between the thin film transistor 102 and the pixel electrode 101, as shown in fig. 2, a second insulating layer 105 is further provided between the common electrode 103 and the thin film transistor 102. In the case where the array substrate 10 includes the common electrode 103 and the pixel electrode 101, the horizontal electric field generated by the common electrode 103 and the pixel electrode 101 drives the liquid crystal molecules in the liquid crystal layer 30 to rotate. In other embodiments, the counter cell substrate 20 comprises a common electrode 103. In the case where the counter substrate 20 includes the common electrode 103 and the array substrate 10 includes the pixel electrode 101, the liquid crystal molecules in the liquid crystal layer 30 are driven to rotate by the vertical electric field generated by the common electrode 103 and the pixel electrode 101.

In order to realize color display, the liquid crystal display panel 3 further includes a color filter layer, and the color filter layer includes a red photoresist unit, a green photoresist unit, and a blue photoresist unit.

In some embodiments, as shown in fig. 2, the opposing substrate 20 includes a second substrate 200 and a color filter layer 201 disposed on the second substrate 200, in which case, the opposing substrate 20 may also be referred to as a color filter substrate. The red photoresist unit, the green photoresist unit and the blue photoresist unit are respectively aligned with the sub-pixels on the array substrate 10 one by one. Here, the projections of the two facing each other on the first substrate 100 overlap each other in the thickness direction of the liquid crystal display panel 3. In an example, the red photoresist units, the green photoresist units and the blue photoresist units are periodically arranged along the horizontal direction, and the red photoresist units are arranged in rows, the green photoresist units are arranged in rows and the blue photoresist units are arranged in rows along the vertical direction.

On this basis, as shown in fig. 2, in order to avoid mutual crosstalk between lights emitted from adjacent sub-pixels, the counter substrate 20 may further include a Black Matrix pattern 202 (Black Matrix, BM for short). For example, the black matrix pattern 202 includes a plurality of parallel first light-shielding bars and a plurality of parallel second light-shielding bars, the plurality of first light-shielding bars and the plurality of second light-shielding bars enclose a plurality of grids, and the red light-shielding units, the green light-shielding units, and the blue light-shielding units are respectively disposed in the grids.

In other embodiments, the array substrate 10 includes the color filter layer 201, and the red photoresist unit, the green photoresist unit and the blue photoresist unit are respectively located in different sub-pixels. In this case, the Array substrate may be referred to as a COA substrate (Color filter on Array, in which a Color filter layer is integrated). Illustratively, in the horizontal direction, the sub-pixels including the red photoresist units, the sub-pixels including the green photoresist units, and the sub-pixels including the blue photoresist units are periodically arranged, and in the vertical direction, the sub-pixels including the red photoresist units are arranged in rows, the sub-pixels including the green photoresist units are arranged in rows, and the sub-pixels including the blue photoresist units are arranged in rows.

In the case where the array substrate 10 includes the color filter layer 201, it may be that the array substrate 10 includes a black matrix pattern 202 disposed on the first substrate 100; the counter substrate 20 may include a black matrix pattern 202 provided on the second substrate 200.

As shown in fig. 2, the liquid crystal display panel 3 further includes an upper polarizer 50 disposed on a side of the opposite-box substrate 20 away from the liquid crystal layer 30 and a lower polarizer 60 disposed on a side of the array substrate 10 away from the liquid crystal layer 30, and transmission axes of the upper polarizer 50 and the lower polarizer 60 are perpendicular or parallel to each other.

Based on the structure of the liquid crystal display panel 3 in fig. 2, taking the example that the transmission axes of the upper polarizer 50 and the lower polarizer 60 are perpendicular to each other, when the liquid crystal display panel 3 is applied to a liquid crystal display device, the display principle of the liquid crystal display device is as follows: the backlight assembly 4 emits white light, which is polarized in a specific polarization direction by the lower polarizer 60, and then enters the liquid crystal display panel 3, and is filtered by the color filter layer 201 to form polarized light of three colors, red, green, and blue. When the polarization direction of the polarized light is perpendicular to the polarization direction of the upper polarizer 50, the polarized light cannot pass through the upper polarizer; when the polarization direction of the polarized light is parallel to the polarization direction of the upper polarizer 50, the polarized light can pass through the upper polarizer 50, and the light intensity of the emergent light is strongest at this time. Since the liquid crystal molecules have a polarization property to polarized light, the polarization direction of the polarized light can be changed by a specific molecular arrangement direction, and when the arrangement direction of the liquid crystal molecules is controlled by an electric field generated between the pixel electrode 101 and the common electrode 103 to rotate, the polarization direction of the polarized light passing through the liquid crystal molecules is also changed, so that the amount of the polarized light emitted from the upper polarizer 50 can be controlled. When the pixel electrode 101 and the common electrode 103 regularly control the rotation of the liquid crystal molecules according to the electric signals applied to the respective electrodes, the light of the red, green and blue sub-pixels regularly transmits through the upper polarizer 50, and finally a color image is formed. The light path propagation sequence is as follows: the light emitted from the backlight assembly 4 sequentially passes through the lower polarizer 60, the array substrate 10, the liquid crystal layer 30, the opposite box substrate 20, and the upper polarizer 50.

Based on the above, the embodiment of the invention provides a backlight assembly 4, which can be applied to the liquid crystal display device described above for providing a light source for the liquid crystal display panel 3, and for other structures in the liquid crystal display device except the backlight assembly 4, reference may be made to the above, and details are not repeated here. As shown in fig. 3a and 4a, the backlight assembly 4 according to the embodiment of the present invention includes: a light guide plate 41 and a light source 42 disposed on a side surface of the light guide plate 41; the light source 42 includes a first sub-light source 420 and a second sub-light source 421, and a light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 is smaller than a light emitting angle β of the second sub-light source 421 in a plane parallel to the light emitting surface of the light guide plate 41; the bottom surface of the light guide plate 41 includes a plurality of grooves 410 or protrusions 410 extending along a first direction, and the bottom surface of the light guide plate 41 is disposed opposite to the light exit surface of the light guide plate 41; the first direction is a long side direction of the light incident surface of the light guide plate 41; the sidewall of the recess 410 or the protrusion 410 includes a reflective surface 411, and light emitted from the light source 42 is reflected by the reflective surface 411 and then exits from the light exit surface of the light guide plate 41.

Here, the reflecting surface 411 may be a curved surface, an inclined plane, or the like. In the drawings of the embodiments of the present invention, the reflecting surface 411 is taken as an inclined plane for illustration. In the case that the reflecting surface 411 is an inclined plane, in some embodiments, an included angle θ between the reflecting surface 411 and the light emitting surface, which is close to the light source 42 where the emitted light is reflected by the reflecting surface, is an acute angle.

The light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is smaller than the light emitting angle β of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41, that is, the light emitting angle of the first sub-light source 420 in the first direction is smaller than the light emitting angle of the second sub-light source 421 in the first direction.

It should be understood that the light-emitting angles of the first sub-light sources 420 mentioned in the embodiments of the present invention all refer to the light-emitting angles of the light emitted by the first sub-light sources 420, and the light-emitting angles of the second sub-light sources 421 all refer to the light-emitting angles of the light emitted by the second sub-light sources 421.

Here, the light guide plate 41 includes a light emitting surface, a bottom surface and side surfaces, the bottom surface is disposed opposite to the light emitting surface, and all the surfaces of the light guide plate 41 except the light emitting surface and the bottom surface are the side surfaces. The light source 42 is disposed on a side surface of the light guide plate 41, wherein the side surface on which the light source 42 is disposed is a light incident surface. When the backlight assembly 4 is applied to a liquid crystal display device and is used to provide a light source for the liquid crystal display panel 3, the light-emitting surface of the light guide plate 41 faces the liquid crystal display panel 3. Since the light source 42 is disposed at a side surface of the light guide plate 41, the backlight assembly 4 may be referred to as a side-in type backlight assembly.

The shape of the light guide plate 41 is not limited, and in some embodiments, as shown in fig. 3b and 4b, the light guide plate 41 has a rectangular parallelepiped shape. In other embodiments, as shown in FIG. 3c, the light guide plate 41 has a wedge shape.

Here, as shown in fig. 3b and 3c, the bottom surface of the light guide plate 41 includes a plurality of grooves 410 extending in the first direction; as shown in fig. 3d, the bottom surface of the light guide plate 41 may include a plurality of protrusions 410 extending in the first direction.

In some embodiments, as shown in fig. 3a and 4a, the groove 410 or the protrusion 410 continuously extends from one side edge of the light guide plate 41 to the other opposite side edge of the light guide plate 41 along the first direction. In other embodiments, as shown in FIGS. 5 and 10b, at least one indentation 410 includes a plurality of mutually unconnected sub-indentations 4101 extending in the first direction, or at least one protrusion 410 includes a plurality of mutually unconnected sub-protrusions 4101 extending in the first direction.

The number of the grooves 410 or the protrusions 410 included in the bottom surface of the light guide plate 41 is not limited, and the number of the grooves 410 or the protrusions 410 may be selected according to the area of the bottom surface of the light guide plate 41. In some embodiments, the grooves 410 or the protrusions 410 are uniformly distributed throughout the bottom surface of the light guide plate 41.

In the case where the bottom surface of the light guide plate 41 includes the groove 410, the groove 410 may be a V-groove. In the case where the bottom surface of the light guide plate 41 includes the protrusions 410, the protrusions 410 may alternatively be shaped as triangular prisms. In addition, when the bottom surface of the light guide plate 41 includes a plurality of grooves 410, the shapes of the plurality of grooves 410 may be the same or different. When the bottom surface of the light guide plate 41 includes the plurality of protrusions 410, the plurality of protrusions 410 may have the same shape or different shapes.

Further, as shown in fig. 3a, 3b and 3c, the light source 42 may be disposed at one side surface of the light guide plate 41; as shown in fig. 4a and 4b, the light sources 42 may be disposed on two opposite sides of the light guide plate 41.

On this basis, as shown in fig. 3b and 3c, in the case that the light source 42 is disposed on one side surface of the light guide plate 41, the side wall of each groove 410 or each protrusion 410 at least includes 410 a reflection surface 411 for reflecting the light emitted by the light source 42, and an included angle θ between the reflection surface 411 and the light emitting surface, which is close to the light source 42, is an acute angle, in which case, the opening direction of the acute angle faces the light source 42.

It should be noted that the reflection surface 411 and the light emitting surface form two included angles, one included angle is close to the light source 42, and the other included angle is far from the light source 42. Referring to fig. 3b and 3d, an included angle θ formed between the reflective surface 411 and the light-emitting surface is close to the light source 42, and an included angle θ' formed between the reflective surface 411 and the light-emitting surface is far from the light source 42.

As shown in fig. 4b, in the case that the light sources 42 are disposed on two opposite sides of the light guide plate 41, in order to ensure that the light emitted from the light sources 42 can be reflected by the reflecting surfaces 411 and then emitted from the light emitting surface of the light guide plate 41, the sidewall of each of the recesses 410 or each of the protrusions 410 at least includes two reflecting surfaces 411, the two reflecting surfaces 411 are respectively used for reflecting the light emitted from the light sources 42 disposed on the two opposite sides of the light guide plate 41, and the included angle between each of the reflecting surfaces 411 and the light emitting surface, which is close to the light source 42, where the light emitted is reflected by the reflecting surface, is an acute angle.

For example, referring to fig. 4b, taking the bottom surface of the light guide plate 41 as an example, the light sources 42 are respectively disposed on the left and right sides of the light guide plate 41, the side wall of the groove 410 includes two

reflective surfaces

411a and 411b, the reflective surface 411a is used for reflecting the light emitted by the left light source 42, so that the light emitted by the left light source 42 is reflected by the reflective surface 411a and then emitted from the light emitting surface of the light guide plate 41, and the reflective surface 411b is used for reflecting the light emitted by the right light source 42, so that the light emitted by the right light source 42 is reflected by the reflective surface 411b and then emitted from the light emitting surface of the light guide plate 41. An included angle θ between the reflecting surface 411a and the light-emitting surface and close to the left-side light source 42 is an acute angle, and an included angle θ between the reflecting surface 411b and the light-emitting surface and close to the right-side light source 42 is an acute angle.

The liquid crystal display device comprises an upper side, a lower side, a left side, a right side, a front side and a rear side, and a viewer is positioned at the front side of the liquid crystal display device to view a picture. In the case where the backlight assembly 4 is applied to the liquid crystal display device, and the light source 42 is disposed on the upper side and/or the lower side of the light guide plate 41, the first direction refers to the direction from the left eye to the right eye, and light emitted from the light source 42 is reflected by the reflection surface 411 of the groove 410 or the protrusion 410 of the light guide plate 41 and then emitted from the light emitting surface of the light guide plate 41 to the liquid crystal display panel 3. According to the principle of light reflection, the light emitting angles of the first sub-light source 420 and the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 affect the light emitting angles of the left and right sides of the liquid crystal display panel 3. The larger the light emitting angle of the first sub-light source 420 or the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 is, the larger the light emitting angles of the left and right sides of the liquid crystal display panel 3 are. Since the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is smaller than the light emitting angle β of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41, the light emitted from the first sub-light source 420 is reflected by the reflecting surface 411, and the light emitting angle of the light emitted from the left and right sides of the liquid crystal display panel 3 is smaller than the light emitting angle of the light emitted from the left and right sides of the liquid crystal display panel 3 when the light emitted from the second sub-light source 421 is reflected by the reflecting surface 411.

In order to provide the liquid crystal display device with a privacy function, in the related art, when manufacturing the liquid crystal display device, as shown in fig. 6, a privacy film 43 or a switchable diffusion sheet 43 is additionally provided between the liquid crystal display panel 3 and the light guide plate 41. The peeping prevention can be realized by controlling the light-emitting angle of the light through the peeping prevention film 43, and the peeping prevention film 43 may be, for example, a grating. Or, the switchable diffusion sheet 43 is used in combination with a collimated light source or a light source focused toward the center to realize peeping prevention, the switchable diffusion sheet 43 can be switched between a scattering state and a transparent state, and when the switchable diffusion sheet 43 is in the scattering state, non-peeping display (i.e., normal display, i.e., shared display) is realized; when the switchable diffusion sheet 43 is in the transparent state, the privacy display is implemented. The switchable diffuser 43 may be, for example, a PDLC (Polymer Dispersed Liquid Crystal) diffuser film. However, the addition of the privacy film 43 or the switchable diffuser 43 results in an increase in the thickness of the liquid crystal display device.

In addition, peep-proof is realized through the light-emitting angle of control light to peep-proof membrane 43, and when peep-proof membrane 43 was when the light-emitting angle of control light, the light that partly shines on peep-proof membrane 43 can be absorbed to the light that leads to backlight unit 4 to send is wasted, leads to the luminance to descend (luminance can descend 30%), and sets up the liquid crystal display device of peep-proof membrane 43 and can only carry out peep-proof and show, can not normally show, is unfavorable for user experience.

In contrast, an embodiment of the present invention provides a backlight assembly 4 applied in a liquid crystal display device for providing a light source for a liquid crystal display panel 3, the backlight assembly 4 includes a light guide plate 41 and a light source 42 disposed on a side surface of the light guide plate 41, the light source includes a first sub-light source 420 and a second sub-light source 421, a light emitting angle α of the first sub-light source 420 in a plane parallel to a light emitting surface of the light guide plate 41 is smaller than a light emitting angle β of the second sub-light source 421 in a plane parallel to the light emitting surface of the light guide plate 41, a bottom surface of the light guide plate 41 includes a plurality of grooves 410 or protrusions 410 extending along a first direction, side walls or the protrusions 410 of the grooves 410 include a reflective surface 411, and light emitted by the light source 42 is emitted from the light emitting surface of the light guide plate 41 after being reflected by the reflective surface 411. The light emitted by the first sub-light source 420 and the light emitted by the second sub-light source 421 are reflected by the reflection surface 411 of the groove 410 or the protrusion 410 of the light guide plate 41, and then emitted from the light emitting surface of the light guide plate 41, and emitted to the liquid crystal display panel 3. Since the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is smaller than the light emitting angle β of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41, when the first sub-light source 420 is turned on and the second sub-light source 421 is turned off, the light emitting angles of the left and right sides of the liquid crystal display panel 3 are smaller than the light emitting angles of the left and right sides of the liquid crystal display panel 3 when the second sub-light source 421 is turned on and the first sub-light source 420 is turned on or off, that is, when the first sub-light source 420 is turned on and the second sub-light source 421 is turned off, the left and right peep-proof display can be realized; when the second sub-light source 421 is turned on and the first sub-light source 420 is turned on or off, non-peep display (i.e., normal display, i.e., shared display) can be implemented. Compared with the related art, in the embodiment of the invention, the peep-proof display is realized by selecting the first sub-light source 420 with a smaller light-emitting angle in a plane parallel to the light-emitting surface of the light guide plate 41 without arranging the peep-proof film 43 or the switchable diffusion sheet 43, so that the thickness of the liquid crystal display device cannot be increased. In addition, by controlling the on or off of the first sub light source 420 and the second sub light source 421, the embodiment of the invention can control the liquid crystal display device to switch between the peep-proof display and the non-peep-proof display. Compared with the peep-proof film 43 arranged in the related art, which absorbs part of light to cause brightness reduction, the embodiment of the invention does not reduce the brightness of light emitted by the first sub-light source 420 when peep-proof is realized.

On this basis, when the peep-proof display is performed, that is, when the first sub light source 420 is turned on and the second sub light source 421 is turned off, in the angle between the reflecting surface 411 and the light emitting surface, the angle of the light source, which is reflected by the reflecting surface, near the emitted light can be controlled, and the light emitting angle of the light emitted from the upper side of the liquid crystal display panel 3 can be controlled, so that the peep-proof of the upper side of the liquid crystal display panel 3 can be realized, and further, the peep-proof of three sides (three sides, that is, the left side, the right side and the upper side) can be realized.

The light emitting angle of the first sub-light sources 420 in the plane parallel to the light emitting surface of the light guide plate 41 is not limited, and the light emitting angle of the first sub-light sources 420 in the plane parallel to the light emitting surface of the light guide plate 41 may be designed according to the maximum side viewing angle at which the display screen of the liquid crystal display panel 3 can be seen clearly on the left and right sides during the anti-peep display. Optionally, the light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 is: alpha is more than or equal to 0 and less than or equal to 100 degrees.

For example, the light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 may be 0 °, 50 °, 100 °, or the like.

When the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is 0 °, that is, the included angle of the first sub-light source 420 along the first direction is 0 °, that is, the first sub-light source 420 only emits light in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41, the viewer can only see the image displayed by the liquid crystal display panel 3 at the front viewing angle.

Considering that when the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is in the range of 50 ° to 100 °, and when the side viewing angle of the peeper viewing the liquid crystal display panel 3 is small, the peeper may see the picture displayed by the liquid crystal display panel 3, which is not favorable for the anti-peeping display, in some embodiments, the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is 0 ° or more and is not more than 50 °.

For example, the light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 may be 0 °, 20 °, 30 °, or 50 °.

Since the smaller the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is, the smaller the maximum side viewing angle at which the viewer can clearly see the display image of the liquid crystal display panel 3 is, when the light emitting angle α of the first sub-light source in the plane parallel to the light emitting surface of the light guide plate 41 is 0 ° or more and 50 ° or less, the smaller the maximum side viewing angle at which the viewer can clearly see the display image of the liquid crystal display panel 3 is, which is more beneficial to achieving the anti-peep display.

The light emitting angle of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 is not limited, and the light emitting angle of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 can be designed according to the maximum side viewing angle at which the display screen of the lcd panel 3 can be clearly seen at the left and right sides during the non-peep-proof display. Optionally, a light emitting angle β of the second sub-light source 421 in a plane parallel to the light emitting surface of the light guide plate 41 is: beta is more than or equal to 60 degrees and less than or equal to 180 degrees.

For example, the light emitting angle β of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 may be 60 °, 80 °, 100 °, 120 °, or 180 °.

In order to avoid the light from being wasted when the viewer watches the image displayed on the light guide plate 41, and to ensure that the viewer can see the image displayed on the liquid crystal display panel 3 clearly when the viewer watches the image displayed on the light guide plate 41, the light emitting angle β of the second sub-light source 421 in the plane parallel to the light guide plate 41 is 120 ° in some embodiments.

In the embodiment of the invention, when the light emitting angle β of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41 is 120 °, light is emitted from all directions, so that non-peep display, that is, shared display can be realized.

Referring to fig. 7, taking the case that the bottom surface of the Light guide plate 41 includes a plurality of grooves 410 extending along the first direction, the grooves 410 are V-shaped grooves, the Light source 41 is disposed on one side surface of the Light guide plate 41, and the Light emitting angle of the first sub-Light source 420 in the plane parallel to the Light emitting surface of the Light guide plate 41 is 50 °, the convergence between the Light emitting angle of the first sub-Light source 420 in the plane parallel to the Light emitting surface of the Light guide plate 41 and the left and right side viewing angles of the lcd panel 3 is tested by Light tools, which is a simulation result, in fig. 7. The curve a represents the viewing angles at the upper and lower sides, and the curve B represents the viewing angles at the left and right sides. As can be seen from fig. 7, in the case that the light emitting angle of the first sub light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is 50 °, the energy (i.e., the brightness) of the light is attenuated by 95% at the left and right viewing angles of 45 °, so that the left and right peep-proof display can be realized.

According to the principle of light reflection, the light emitting angles of the first sub-light source 420 and the second sub-light source 421 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 affect the light emitting angles of the upper and lower sides of the liquid crystal display panel 3. The light emission angle in a plane perpendicular to both the light exit surface of the light guide plate 41 and the light entrance surface of the light guide plate 41 increases, and the light exit angles at the upper and lower sides of the liquid crystal display panel 3 increase.

The "light emission angle in a plane perpendicular to both the light exit surface of the light guide plate 41 and the light entrance surface of the light guide plate 41" is a light emission angle in the thickness direction of the light guide plate 41.

Since many peepers peep the screen displayed on the liquid crystal display panel 3 from both the left and right sides of the liquid crystal display panel 3, it is difficult to peep the screen displayed on the liquid crystal display panel 3 from both the upper and lower sides of the liquid crystal display panel 3, and therefore the liquid crystal display device only needs to be capable of performing both the left and right peep-proof display when performing the peep-proof display. Based on this, optionally, the light emitting angles γ of the first sub-light source 420 and the second sub-light source 421 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 are 0 ° or more and 180 ° or less.

Here, the light emitting angle γ of the first sub-light source 420 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 may be the same as or different from the light emitting angle γ of the second sub-light source 421 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41. In some embodiments, the light emitting angle γ of the first sub-light source 420 in a plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 is smaller than the light emitting angle γ of the second sub-light source 421 in a plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41.

For example, the light emitting angles of the first sub-light source 420 and the second sub-light source 421 in a plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 may be 0, 50 °, 100 °, 120 °, 150 °, and 180 °.

It is considered that if the light emitting angles of the first sub-light source 420 and the second sub-light source 421 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 are too small, the image displayed by the liquid crystal display panel 3 will be obscured. In order to avoid the light with the light emitting angle larger than 120 ° in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 from entering the eyes of the viewer, and to ensure that the viewer can clearly see the image displayed by the lcd panel 3 when the first sub-light source 420 is turned on or the second sub-light source 421 is turned on, in some embodiments, as shown in fig. 3b, the light emitting angles γ of the first sub-light source 420 and the second sub-light source 421 in the plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 are 120 °.

Referring to fig. 3b and 3d, fig. 3b and 3d are optical path diagrams in a plane perpendicular to both the light exit surface of the light guide plate 41 and the light entrance surface of the light guide plate 41, and as can be seen from the optical path diagrams shown in fig. 3b and 3d, when the light emitting angles γ of the first sub-light source 420 and the second sub-light source 421 in the plane perpendicular to both the light exit surface of the light guide plate 41 and the light entrance surface of the light guide plate 41 are 120 °, light is emitted from both the upper side and the lower side of the liquid crystal display panel 3, so that a viewer can clearly see the image displayed by the liquid crystal display panel 3.

The type of the Light source 42 is not limited, and may be, for example, an LED (Light-Emitting Diode) or a CCFL (Cold Cathode Fluorescent Lamp).

Alternatively, as shown in FIG. 8, the light source 42 includes a plurality of bimorph LEDs 44; a plurality of bicrystal LEDs 44 positioned on the same side of the light guide plate 41 are sequentially arranged in a first direction; one LED particle of the bimorph LED44 is used as the first sub light source 420, and the other LED particle of the bimorph LED is used as the second sub light source 421.

Here, a bi-crystal LED44 refers to two LED particles packaged together. On this basis, the turning on and off of the two LED particles in each bimorph LED44 can be controlled individually.

In the case where the light source 42 includes a plurality of twin LEDs 44, the light emission angles of the LED particles used as the first sub light sources 420 in the plurality of twin LEDs 44 are the same, and the light emission angles of the LED particles used as the second sub light sources 421 in the plurality of twin LEDs 44, that is, the light emission angles of the second sub light sources 421 are the same. The light emission angle of the LED particles used as the first sub light source 420 in any one of the twin LEDs 44, that is, the light emission angle of the first sub light source 420, and the light emission angle of the LED particles used as the second sub light source 421 in any one of the twin LEDs 44, that is, the light emission angle of the second sub light source 421. The light emitting angle of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is smaller than the light emitting angle of the second sub-light source 421 in the plane parallel to the light emitting surface of the light guide plate 41, that is, the light emitting angle of the LED particles used as the first sub-light source 420 in each of the twin LEDs 44 is smaller than the light emitting angle of the LED particles used as the second sub-light source 421 in each of the twin LEDs 44.

Since one LED particle in each of the twinned LEDs 44 is used as the first sub-light source 420 and the other LED particle is used as the second sub-light source 421, the first sub-light source 420 includes the same number of LED particles as the second sub-light source 421.

In some embodiments, as shown in fig. 8, a plurality of bicrystal LEDs 44 are disposed at one side of the light guide plate 41. In this case, the first sub-light sources 420 and the second sub-light sources 421 are disposed at one side surface of the light guide plate 41. In other embodiments, as shown in FIG. 9, a plurality of twin LEDs 44 are disposed on opposite sides of the light guide plate 41. In this case, the first sub-light sources 420 and the second sub-light sources 421 are disposed at both opposite side surfaces of the light guide plate 41.

In the embodiment of the present invention, when the LED particles in the twin LED44 used as the first sub light source 420 are controlled to be turned on and the LED particles used as the second sub light source 421 are controlled to be turned off, in this case, the peep-proof display can be implemented; when the LED particles for the second sub light source 421 in the twinned LED44 are controlled to be turned on, and the LED particles for the first sub light source 420 are controlled to be turned on or off, in this case, the privacy display can be implemented.

Alternatively, as shown in fig. 10a, the first sub-light source 420 is a first LED light bar (which may be another type of light bar) extending along the first direction, or as shown in fig. 3a and 10b, the first sub-light source 420 includes a plurality of first light-emitting elements (specifically, LEDs) sequentially arranged along the first direction. As shown in fig. 10a, the second sub-light sources 421 are second LED light bars (which may be other types of light bars) extending along the first direction, or as shown in fig. 3a and 10b, the second sub-light sources 421 include a plurality of second light emitting elements (for example, LEDs) sequentially arranged along the first direction.

The first LED may be a single-crystal LED or a twin-crystal LED. The second LED may be a single crystal LED or a twin crystal LED.

Here, in the case that the first sub-light source 420 is a first LED light bar extending along the first direction, the light emitting angle of the first LED light bar is the light emitting angle of the first sub-light source 420; when the second sub-light source 421 is a second LED light bar extending along the first direction, the light emitting angle of the second LED light bar is the light emitting angle of the second sub-light source 421. In the case where the first sub light source 420 includes a plurality of first LEDs sequentially arranged in the first direction, when the first LEDs are single crystal LEDs, the light emission angles of the plurality of single crystal LEDs are the same, and the light emission angle of any one single crystal LED is the light emission angle of the first sub light source 420; when the first LED is a twin LED, the light emitting angles of the two LED particles in each twin LED are the same, and the light emitting angles of the LED particles in different twin LEDs are the same, and the light emitting angle of one LED particle in any one twin LED is the light emitting angle of the first sub-light source 420. In the case where the second sub light source 421 includes a plurality of second LEDs sequentially arranged in the first direction, when the second LEDs are single crystal LEDs, the light emission angles of the plurality of single crystal LEDs are the same, and the light emission angle of any one single crystal LED is the light emission angle of the second sub light source 421; when the second LED is a twin LED, the light emitting angles of the two LED particles in each twin LED are the same, and the light emitting angles of the LED particles in different twin LEDs are the same, and the light emitting angle of one LED particle in any one twin LED is the light emitting angle of the second sub-light source 421.

Based on the above, the arrangement of the first sub light source 420 and the second sub light source 421 is not limited, and it is to be noted that the light emitted from the first sub light source 420 and the light emitted from the second sub light source 421 do not affect each other. Two alternative arrangements of the first sub-light source 420 and the second sub-light source 421 are provided below.

The first method comprises the following steps: as shown in fig. 10a and 10b, the first sub light source 420 and the second sub light source 421 are respectively disposed at opposite sides of the light guide plate 41.

Here, the first sub-light source 420 may be a first LED light bar extending along a first direction, and the second sub-light source 421 may be a second LED light bar extending along the first direction. The first sub-light source 420 may be a first LED light bar extending along a first direction, and the second sub-light source 421 includes a plurality of second LEDs sequentially arranged along the first direction. Of course, the first sub-light source 420 may include a plurality of first LEDs sequentially arranged along a first direction, and the second sub-light source 421 is a second LED light bar extending along the first direction.

On this basis, in the case that the first sub light source 420 and the second sub light source 421 are respectively disposed on two opposite side surfaces of the light guide plate 41, the first sub light source 420 may be disposed on the light emitting surface of the light guide plate 41, and the second sub light source 421 may be disposed on the bottom surface of the light guide plate 41; the first sub-light sources 420 may be disposed on the bottom surface of the light guide plate 41, and the second sub-light sources 421 may be disposed on the light emitting surface of the light guide plate 41.

And the second method comprises the following steps: as shown in fig. 11 and 12, the first sub light source 420 and the second sub light source 421 located on the same side of the light guide plate 41 are sequentially disposed along the thickness of the light guide plate 41.

Fig. 11 and 12 illustrate an example in which the bottom surface of the light guide plate 41 includes a plurality of grooves 410.

In addition, the first sub-light source 420 may be close to the light exit surface of the light guide plate 41 relative to the second sub-light source 421; the second sub-light source 421 may be opposite to the first sub-light source 420 and close to the light emitting surface of the light guide plate 41. Fig. 11 illustrates the first sub-light sources 420 being close to the light exit surface of the light guide plate 41 relative to the second sub-light sources 421.

In addition, as shown in fig. 11, a first sub-light source 420 and a second sub-light source 421 may be disposed on one side surface of the light guide plate 41. As shown in fig. 12, the first sub light source 420 and the second sub light source 421 may be disposed on both opposite side surfaces of the light guide plate 41.

It should be noted that, no matter the light source in the embodiment of the present invention is a dual-crystal LED, a single-crystal LED, or an LED light bar, the light source is disposed on the flexible circuit board, and the circuit on the flexible circuit board controls the light source to be turned on or off. In the case that the first sub light source 420 and the second sub light source 421 located on the same side of the light guide plate 41 are sequentially disposed along the thickness of the light guide plate 41, as shown in fig. 11, the first sub light source 420 and the second sub light source 421 may be respectively disposed on two Flexible Printed Circuits (FPCs) 422, wherein one of the Flexible Printed circuits 422 is directly disposed at the edge of the bottom surface of the light guide plate 41, and the other Flexible Printed Circuit 422 is reversely buckled at the edge of the light emitting surface of the light guide plate 41.

In the embodiment of the present invention, when the backlight assembly 4 is applied to a liquid crystal display device, the first sub-light source 420 and the second sub-light source 421 located on the same side of the light guide plate 41 are sequentially disposed along the thickness of the light guide plate 41, so that the width of the light source 42 occupying the bezel can be reduced, thereby realizing a narrow bezel.

In the case where the first sub light source 420 includes a plurality of first LEDs sequentially arranged in the first direction, and the second sub light source 421 includes a plurality of second LEDs sequentially arranged in the first direction, as shown in fig. 3a and 4a, the first sub light source 420 and the second sub light source 421 positioned on the same side of the light guide plate 41 may be sequentially disposed in a direction close to the light guide plate 41; the first LED is arranged at the position opposite to the gap between two adjacent second LEDs; as shown in fig. 13, the first LEDs and the second LEDs on the same side of the light guide plate 41 may be alternately arranged in sequence along the first direction.

In a case where the first sub light source 420 and the second sub light source 421 located on the same side of the light guide plate 41 are sequentially disposed in a direction of approaching the light guide plate 41, it may be that the first sub light source 420 approaches the light guide plate 41 with respect to the second sub light source 421; the second sub light sources 421 may be close to the light guide plate 41 with respect to the first sub light sources 420.

On this basis, as shown in fig. 3a and 13, the first sub-light source 420 and the second sub-light source 421 may be disposed on one side surface of the light guide plate 41. As shown in fig. 4a, the first sub-light source 420 and the second sub-light source 421 may be disposed on both opposite side surfaces of the light guide plate 41.

In the embodiment of the present invention, the first sub light sources 420 include a plurality of first LEDs sequentially arranged along a first direction, the second sub light sources 421 include a plurality of second LEDs sequentially arranged along the first direction, the first sub light sources 420 and the second sub light sources 421 located on the same side of the light guide plate 41 are sequentially arranged along a direction close to the light guide plate 41, or the first LEDs and the second LEDs located on the same side of the light guide plate 41 are sequentially and alternately arranged along the first direction, and in a case that the first sub light sources 420 and the second sub light sources 421 are both turned on, the first sub light sources 420 may compensate for a dark space between two adjacent second sub light sources 421, or the second sub light sources 421 may compensate for a dark space between two adjacent first sub light sources 420, so as to reduce the severity of dark spots (Hot spots).

In some embodiments, as shown in fig. 14, the backlight assembly 4 further includes a reflective sheet 45, and the reflective sheet 45 is disposed on the bottom surface of the light guide plate 41.

In the embodiment of the present invention, the reflective sheet 45 is disposed on the bottom surface of the light guide plate 41 to improve the utilization rate of the light emitted from the light source 42.

In some embodiments, as shown in fig. 15, the liquid crystal display device provided in the embodiments of the present invention further includes a controller 70, where the controller 70 is electrically connected to the first sub light source 420 and the second sub light source 421, respectively, and is used for controlling the first sub light source 420 and the second sub light source 421 to be turned on and off.

Here, the controller 70 may be integrated on a PCB (Printed Circuit Board) Board.

In the embodiment of the present invention, under the condition of peep-proof display, the controller 70 controls the first sub-light source 420 to be turned on, and the second sub-light source 421 to be turned off; in case of normal display, the controller 70 controls the second sub light source 421 to be turned on, and the first sub light source 420 to be turned on or off. In the case of normal display, when the controller 70 controls both the first sub light source 420 and the second sub light source 421 to be turned on, the brightness of light emitted from the backlight assembly 4 may be increased.

An embodiment of the present invention further provides a method for controlling the liquid crystal display device, as shown in fig. 16, including:

s100, controlling the first sub light source 420 to be turned on and the second sub light source 421 to be turned off during peep-proof display; in the non-peep-proof display, the second sub-light source 421 is controlled to be turned on, and the first sub-light source 420 is controlled to be turned on or off.

Here, when the non-privacy display is performed, the second sub-light source 421 is controlled to be turned on, the first sub-light source 420 may be controlled to be turned on, the first sub-light source 420 may also be controlled to be turned off, and when the first sub-light source 420 is controlled to be turned on, the brightness of light emitted by the backlight assembly 4 may be improved.

Since the liquid crystal display device includes the backlight assembly 4, the structure and the beneficial effects of the backlight assembly 4 have been described in detail in the above embodiments, and thus are not described again here.

The inventor of the present invention has found that, in the foregoing embodiments, in order to realize the left and right peep-proof display, the grooves 410 or the protrusions 410 (hereinafter, collectively referred to as dots) are provided at the bottom surface of the light guide plate 41. After the backlight assembly is combined with the liquid crystal display panel to form the liquid crystal display device, the screen dots are invisible to naked eyes, and the display effect is influenced. In this regard, the inventors propose the following solution.

An embodiment of the present invention provides a backlight assembly including: a light guide plate 41 and a light source 42 disposed on a side surface of the light guide plate 41; the light source 42 includes a first sub-light source 420. Of course, the light source 42 may also include the second sub-light source 421 as disclosed in the above embodiments. The contents of the second sub-light source 421 are not repeated herein since the following only relates to how to eliminate the dots invisible to the naked eye on the premise of realizing the left-right peep-proof display. The technical details relating to the first sub-light source 420 can also be referred to the description hereinbefore.

The light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is: alpha is more than or equal to 0 and less than or equal to 100 degrees; the bottom surface of the light guide plate 41 includes a plurality of grooves 410 or protrusions 410 extending along a first direction, and the bottom surface of the light guide plate 41 is disposed opposite to the light exit surface of the light guide plate 41; the first direction is a long side direction of the light incident surface of the light guide plate 41; the sidewall or the protrusion 410 of the recess 410 includes a reflective surface 411 of the reflective sheet 411, and light emitted from the light source 42 is reflected by the reflective surface 411 of the reflective sheet 411 and then exits from the light exit surface of the light guide plate 41. Thus, left and right peep-proof display can be realized.

Further, as shown in fig. 17a, 17b and 18, the backlight assembly further includes a prism sheet 6 disposed on the light exit surface side of the light guide plate 41, the prism sheet 6 includes a substrate layer 61 and a plurality of ridges 62 disposed on the substrate layer 61 opposite to the light guide plate 41, the extending direction of the ridges 62 is a first direction, and the vertex angle t of the ridges 62 is: t is more than or equal to 150 degrees and less than 180 degrees.

The inventors have found that the peaks of the ridges 62 have a weak scattering effect on the light, which makes the dots on the light guide plate 41 more blurred. So that the dots are not visually apparent when the backlight assembly is used in conjunction with a liquid crystal display panel.

The extending direction of the ridges 62 is the first direction, so that the angular range of the projection of light in the plane perpendicular to the light exit surface of the light guide plate 41 and parallel to the first direction does not change greatly. Namely, the left and right peep-proof display is not greatly influenced.

The apex angle t of the ridge 62 is relatively large, also for the purpose of reducing the influence on the propagation direction of the light. It is easily understood that, when the apex angle of the ridge 62 is nearly 180 °, the influence of the prism sheet 6 on the propagation direction of light is almost negligible.

Therefore, the left and right peep-proof display is ensured, and the influence of the network point on the display effect is eliminated.

The material of the base layer 61 is, for example, polyethylene terephthalate (PET). The ridges 62 can generally be fabricated by an embossing process. The material of the ridge 62 is, for example, resin or ultraviolet curing adhesive (UV adhesive).

Referring to the foregoing description, in some embodiments, the light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 is 0 ≦ α ≦ 50 °.

In some embodiments, the first sub-light source 420 is a first LED light bar extending along a first direction, or the first sub-light source 420 includes a plurality of first LEDs arranged in sequence along the first direction.

In some embodiments, the first sub light sources 420 are disposed at opposite sides of the light guide plate 41.

In some embodiments, the light emitting angle γ of the first sub-light source 420 in a plane perpendicular to both the light emitting surface of the light guide plate 41 and the light incident surface of the light guide plate 41 is 0 ≦ γ ≦ 180 °.

In some embodiments, the first cross-section of the edge peaks 62 is an isosceles triangle, with the first cross-section being perpendicular to the first direction. Fig. 18 illustrates the first cross section. Of course, the first cross section of the ridge 62 may be a non-isosceles triangle, as long as the angle of the triangle toward the substrate layer 61 is within the predetermined angle range.

With reference to fig. 18, in some embodiments, the center-to-center spacing L of adjacent lands 62 is: l is more than or equal to 0.02mm and less than or equal to 0.1mm. If the center distance is too large, the density of the ridges 62 is too low, and the effect of eliminating visible dots is limited. This too small center distance is inconvenient to manufacture.

With reference to fig. 18, in some embodiments, the thickness H of the prism sheet 6 is: h is more than or equal to 0.05mm and less than or equal to 0.3mm. The thickness of the prism sheet 6 is at least partially contributed by the base material layer 61 and the prism ridges 62, and this thickness range is reasonable for the purpose of facilitating the process.

In some embodiments, the number of prism sheets 6 is plural, and the plural prism sheets 6 are stacked in order. Although only one prism sheet 6 is disposed in the backlight assembly of fig. 17, if a single prism sheet 6 has a poor effect of eliminating visible dots, a plurality of prism sheets 6 may be disposed to further eliminate visible dots.

In comparative example 1, the light emission angle α of the first sub-light source 420 in a plane parallel to the light exit surface of the light guide plate 41 was 40 °, and the prism sheet 6 described above was not disposed. As shown in fig. 19a, the luminance of the backlight assembly at a viewing angle inclined 45 ° left and right is attenuated to 0.8% of the luminance at a viewing angle of 0 °. The liquid crystal display device formed by the backlight component has better left and right peep-proof effect, but the screen dots are visible.

In comparative example 2, the light emitting angle α of the first sub-light source 420 in a plane parallel to the light emitting surface of the light guide plate 41 was 40 °, and the prism sheet 6 was disposed outside the light emitting surface of the light guide plate 41, but it is different from the previous examples in that the apex angle of the prism peaks 62 of the prism sheet 6 was a conventional 90 ° angle. As shown in fig. 19b, the left and right peep-proof effect is deteriorated, and the luminance of the backlight assembly at the viewing angle of 0 ° is greatly attenuated due to the scattering effect of the apexes of the ridges 62.

In comparative example 3, according to the scheme of the previous embodiment, the light emitting angle α of the first sub-light source 420 in the plane parallel to the light emitting surface of the light guide plate 41 is 40 °, and the prism sheet 6 is disposed outside the light emitting surface of the light guide plate 41, and the vertex angle of the prism peak 62 of the prism sheet 6 is 150 °. As shown in fig. 19c, the left and right peep-proof effect is restored, and the dots are not visible due to the weak scattering effect of the peaks of the ridges 62.

The remaining experimental parameters in the above three comparative examples were set to be the same. The light exit angles in fig. 19a to 19c each refer to a light exit angle in the left-right direction.

The embodiment of the invention also provides a liquid crystal display device, which comprises a liquid crystal display panel and the backlight assembly; the backlight assembly is used for providing a light source for the liquid crystal display panel.

The liquid crystal display device can realize left-right peep-proof display and eliminate visible dots.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A backlight assembly, comprising: the light source comprises a light guide plate and a light source arranged on the side face of the light guide plate; the light source comprises a first sub-light source; the light emitting angle alpha of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is as follows: alpha is more than or equal to 0 and less than or equal to 50 degrees; the bottom surface of the light guide plate comprises a plurality of grooves or bulges extending along a first direction, and the bottom surface of the light guide plate is opposite to the light-emitting surface of the light guide plate; the first direction is the long side direction of the light incident surface of the light guide plate; the side wall or the bulge of the groove comprises a reflecting surface, and the reflecting surface is used for transmitting the light emitted by the light source so that the reflected light can be emitted out of the light emitting surface of the light guide plate; the backlight module is characterized by further comprising a prism sheet arranged on one side of the light emergent surface of the light guide plate, the prism sheet comprises a base material layer and a plurality of ridges arranged on one side of the light guide plate, the base material layer faces away from the light emergent surface of the light guide plate, the extending direction of the ridges is the first direction, and the vertex angle t of the ridges is as follows: t is more than 150 degrees and less than 180 degrees.

2. The backlight assembly of claim 1, wherein the first sub-light source comprises a first light bar extending along a first direction, or the first sub-light source comprises a plurality of first light emitting elements arranged in sequence along the first direction.

3. The backlight assembly of claim 2, wherein the first light bars are two in number and are respectively disposed on two opposite side surfaces of the light guide plate; or the first light-emitting components are arranged in two rows along the first direction and are respectively arranged on two opposite side surfaces of the light guide plate.

4. The backlight assembly of claim 1, wherein the first sub-light source has a light emitting angle γ of 0 ° γ and 180 ° in a plane perpendicular to both the light emitting surface and the light incident surface of the light guide plate.

5. The backlight assembly of claim 1, wherein the first cross-section of the prism peak is an isosceles triangle, and the first cross-section is perpendicular to the first direction.

6. The backlight assembly of claim 1, wherein the center-to-center distance L between adjacent ridges is: l is more than or equal to 0.02mm and less than or equal to 0.1mm.

7. The backlight assembly of claim 1, wherein the prism sheet has a thickness H of: h is more than or equal to 0.05 and less than or equal to 0.3mm.

8. The backlight assembly of claim 1, wherein the prism sheet is plural in number, and the plurality of prism sheets are stacked in sequence.

9. The backlight assembly of any one of claims 1-8, wherein the light source further comprises a second sub-light source;

the light emitting angle of the first sub-light source in a plane parallel to the light emitting surface of the light guide plate is smaller than the light emitting angle of the second sub-light source in a plane parallel to the light emitting surface of the light guide plate.

10. The backlight assembly of claim 9, wherein the second sub-light source has a light emission angle β in a plane parallel to the light exit surface of the light guide plate: beta is more than or equal to 60 degrees and less than or equal to 180 degrees.

11. The backlight assembly of claim 10, wherein the second sub-light source has a light emitting angle β of 120 ° in a plane parallel to the light emitting surface of the light guide plate.

12. The backlight assembly of claim 9, wherein the light source comprises a plurality of twinned LEDs; the plurality of bicrystal LEDs positioned on the same side surface of the light guide plate are sequentially arranged along a first direction; one LED particle in the double-crystal LED is used as the first sub-light source, and the other LED particle in the double-crystal LED is used as the second sub-light source.

13. The backlight assembly of claim 9, wherein the second sub-light source comprises a second light bar extending along the first direction, or the second sub-light source comprises a plurality of second light emitting members sequentially arranged along the first direction.

14. A liquid crystal display device comprising a liquid crystal display panel and the backlight assembly according to any one of claims 1 to 13;

the backlight assembly is used for providing a light source for the liquid crystal display panel.