CN108646465B

CN108646465B - Display device

Info

Publication number: CN108646465B
Application number: CN201810443669.6A
Authority: CN
Inventors: 周育正; 林子圣
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2018-03-06
Filing date: 2018-05-10
Publication date: 2021-09-10
Anticipated expiration: 2038-05-10
Also published as: CN108646465A; TW201939080A; TWI657277B

Abstract

A display device comprises a display module and a backlight module. The backlight module is stacked on the display module. The backlight module comprises a light guide plate, a plurality of light sources and a first prism sheet. The light guide plate is provided with a light incident surface, a bottom surface and a light emergent surface opposite to the bottom surface. The first direction is perpendicular to the light-emitting surface. The light source is arranged on the light incident surface. The light source and the light guide plate have the shortest distance in the second direction. The light sources are arranged along a third direction. The first prism sheet is arranged on the light-emitting surface. The first prism sheet has a plurality of first protrusion structures. The refractive index of the first protrusion structure is greater than or equal to 1.6. A light provided by the light source passes through the light guide plate.

Description

Display device

Technical Field

The present invention relates to a display device, and more particularly, to a display device having a backlight module.

Background

With the advancement of science and technology, electronic products play more and more important roles in human life, and products such as mobile phones, computers, televisions, smart watches … … have more and more functions. However, energy consumption is required to use various functions of electronic products, and therefore how to reduce energy consumption of electronic products becomes a problem to be solved in the present circles.

In an electronic product having a display device, a backlight module of the display device often consumes a lot of energy in order to display a picture with sufficient brightness. In some portable electronic products (such as mobile phones, tablet computers, etc.), if the power consumption of the display device is too high, the electronic products are prone to have insufficient endurance. Therefore, how to reduce the power consumption of the display device becomes a problem to be solved urgently.

Disclosure of Invention

The invention provides a display device which can save energy consumed by a backlight module.

In at least one embodiment of the present invention, a display device includes a display module and a backlight module. The backlight module is arranged on the display module along the first direction in a stacked mode. The backlight module comprises a light guide plate, a plurality of light sources and a first prism sheet. The light guide plate is provided with a light incident surface, a bottom surface and a light emergent surface opposite to the bottom surface. The first direction is perpendicular to the light-emitting surface. The plurality of light sources are arranged on the light incident surface. The light source and the light guide plate have the shortest distance in the second direction. The light sources are arranged along a third direction. The first direction, the second direction and the third direction are orthogonal to each other. The first prism sheet is arranged on the light-emitting surface. The first prism sheet has a plurality of first protrusion structures. The refractive index of the first protrusion structure is greater than or equal to 1.6. The light provided by the light source passes through the light guide plate. In the light distribution of the light rays on the plane formed by the first direction and the second direction, the second direction is 90 degrees, and the first direction is 0 degree, the part of the light rays leaving the light-emitting surface at 13-70 degrees accounts for more than 35% of the total energy of the light rays leaving the light-emitting surface.

The display device comprises a display module and a backlight module. The backlight module is arranged on the display module in a first direction in an overlapping mode. The backlight module comprises a light guide plate, a plurality of light sources and a first prism sheet. The light guide plate is provided with a light incident surface, a bottom surface and a light emergent surface opposite to the bottom surface. The first direction is perpendicular to the light-emitting surface. The plurality of light sources are arranged on the light incident surface. The light source and the light guide plate have the shortest distance in the second direction. The light sources are arranged along a third direction. The first direction, the second direction and the third direction are orthogonal to each other. The first prism sheet is arranged on the light-emitting surface. The first prism sheet has a plurality of first protrusion structures. The refractive index of the first protrusion structure is greater than or equal to 1.6. The light provided by the light source passes through the light guide plate. The maximum brightness of the light leaving the light-emitting surface is 80 to 90 degrees in the light distribution of the light on the plane formed by the first direction and the second direction, with the second direction being 90 degrees and the first direction being 0 degree.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is an oblique view schematically illustrating a display device according to an embodiment of the present invention.

Fig. 2 is a light distribution diagram of a light guide plate according to an embodiment of the invention.

Fig. 3 is a light distribution diagram of a light guide plate according to an embodiment of the invention.

Fig. 4 is a light distribution diagram of a light guide plate according to an embodiment of the invention.

Fig. 5 is an oblique view schematically illustrating a display device according to an embodiment of the present invention.

FIG. 6 is a light distribution diagram of a diffuser according to an embodiment of the present invention.

Fig. 7 is a light distribution diagram of a light guide plate according to an embodiment of the invention.

FIG. 8 is a light distribution diagram of a diffuser according to an embodiment of the present invention.

FIG. 9 is a light distribution diagram of a diffuser according to an embodiment of the present invention.

Description of reference numerals:

10. 20: display device

100: display module

200: backlight module

210: light guide plate

220: a plurality of light sources

230: first prism sheet

240: second prism sheet

250: diffusion sheet

A1, A2: direction of rotation

B: bottom surface

D1: a first direction

D2: second direction

D3: third direction

E: light emitting surface

I: light incident surface

P: circuit board

P1: first bump structure

P2: second bump structure

R: reflector plate

X, Y: plane surface

α, γ: vertical angle

β, δ: horizontal angle

Detailed Description

Referring to fig. 1, in the present embodiment, a display device 10 includes a display module 100 and a backlight module 200, wherein the backlight module 200 is stacked on the display module 100 in a first direction. The backlight module 200 includes a light guide plate 210, a plurality of light sources 220, and a first prism sheet 230.

In the embodiment, the light guide plate 210 has a light incident surface I, a bottom surface B, and a light emitting surface E opposite to the bottom surface B. The light guide plate 210, the first prism sheet 230 and the display module 100 are stacked along the first direction D1, in other words, the first direction D1 is substantially perpendicular to the light emitting surface E. In some embodiments, the bottom surface B and/or the light emitting surface E of the light guide plate 210 have a plurality of microstructures (not shown), for example, the microstructures are distributed on the bottom surface B and/or the light emitting surface E. In some embodiments, the material of the light guide plate 210 is, for example, Polycarbonate (PC), Polymethyl methacrylate (PMMA), other polymer materials, or a combination thereof, but the invention is not limited thereto.

In the present embodiment, the light source 220 is disposed on the circuit board P, for example, and the light source 220 is disposed on the light incident surface I of the light guide plate 210, that is, the position of the light source 220 corresponds to the light incident surface I. In fig. 1, the light source 220 is disposed on a side surface (e.g., the light incident surface I) of the light guide plate 210, so that light rays provided by the light source 220 enter the light guide plate from the side surface of the light guide plate to form a side-in type backlight module. The light sources 220 and the light guide plate 210 have the shortest distance in the second direction D2, and the plurality of light sources 220 are arranged along the third direction D3. Specifically, the second direction D2 is substantially perpendicular to the light incident surface I, the third direction D3 is substantially parallel to the light incident surface I, and the first direction D1, the second direction D2 and the third direction D3 are substantially perpendicular to each other. The light source 220 can emit white light, blue light or other colors of light, and in the embodiment, the light source 220 emitting white light is taken as an example, but the invention is not limited thereto.

In the present embodiment, the first prism sheet 230 is disposed on the light-emitting surface E, such that the first prism sheet 230 is located between the display module 100 and the light guide plate 210. The first prism sheet 230 has a plurality of first protrusion structures P1. The first bump structures P1 are, for example, triangular pillar shapes, and the first bump structures P1 are arranged along the direction a 1. The refractive index of the first protrusion structures P1 is greater than or equal to 1.6. The material of the first protrusion structure P1 is, for example, a highly cross-linked acrylic resin (Crosslinked acrylic resin), other polymer materials, or a combination thereof, but the invention is not limited thereto.

In some embodiments, the backlight module 200 further includes a second prism sheet 240 and a reflective sheet R. The second prism sheet 240 is disposed between the first prism sheet 230 and the light guide plate 210, and the second prism sheet 240 has a plurality of second protrusion structures P2. The second bump structures P2 are, for example, triangular pillar shaped, and the second bump structures P2 are aligned along a direction a2, the direction a2 being, for example, perpendicular to the direction a 1. In fig. 1, the protrusion structures P1 of the first prism sheet 230 are arranged along the direction a1, and the direction a1 is substantially parallel to the second direction D2. Meanwhile, the protrusion structures P2 of the second prism sheet 240 are arranged along the direction a2, and the direction a2 is substantially parallel to the third direction D3. In another modification, the protrusion structures P1 of the first prism sheet 230 are arranged along the direction a2, and the protrusion structures P2 of the second prism sheet 240 are arranged along the direction a 1. In another variation, the direction a1 is substantially perpendicular to the direction a2, that is, the protrusion structure P1 of the first prism sheet and the protrusion structure P2 of the second prism sheet are substantially perpendicular to each other, but an angle is formed between the direction a1 and the second direction D2. In other words, the direction a1 is not parallel to the second direction D2, and compared to fig. 1, the direction a1 is rotated by an angle clockwise or counterclockwise with respect to the second direction D2, which helps to reduce the optical fringes. The refractive index of the second protrusion structures P2 is greater than or equal to 1.6. The second protrusion structure P2 is made of, for example, a highly cross-linked acrylic resin (Crosslinked acrylic resin), other polymer materials, or a combination thereof, but the invention is not limited thereto. In the present embodiment, the first protrusion structures P1 and the second protrusion structures P2 with the refractive index greater than or equal to 1.6 can be preferably matched with the light guide plate 210, so as to make the light leaving the first prism sheet 230 and the second prism sheet 240 more concentrated. Specifically, the prism sheet having a refractive index of 1.6 or more is preferably used, and the incident angle of light is preferably 13 to 70 degrees.

In the present embodiment, the reflective sheet R is disposed on the bottom surface B of the light guide plate 210. In some embodiments, the reflectivity of the reflective sheet R is greater than or equal to 95%, and more particularly, the reflectivity is greater than or equal to 95% in the visible wavelength range of 380-780 nm, so as to increase the optical utilization rate and further increase the brightness. In some embodiments, the reflective sheet further includes diffusing particles, which can reduce the absorption of the reflective sheet to the light guide plate, but the invention is not limited thereto.

Fig. 2 is a light distribution diagram of a light guide plate according to an embodiment of the invention. Fig. 3 is a light distribution diagram of a light guide plate according to an embodiment of the invention. Fig. 4 is a light distribution diagram of a light guide plate according to an embodiment of the invention. Fig. 2 to 4 are light distribution diagrams of the light guide plate of the embodiment of fig. 1, for example.

Fig. 2 is a diagram illustrating light distribution patterns of light rays provided by the light source 220 at different angles after passing through the light guide plate 210. For example, fig. 2 is a light distribution diagram of light rays emitted from the light source 220 in fig. 1 after entering the light guide plate 210, and leaving the center of the light guide plate 210 at different angles.

Fig. 3 is a light distribution diagram of light rays provided by the light source 220 leaving the light-emitting surface E at different vertical angles α after passing through the light guide plate 210, where the vertical angle α may be a positive value or a negative value. The vertical axis of fig. 3 is in nits and the horizontal axis in degrees. Referring to fig. 1 and fig. 3, in the light distribution of the light rays on the plane X formed by the first direction D1 and the second direction D2, the vertical angle α is, for example, an included angle between the light ray leaving the light emitting surface E and the plane X of the first direction D1, the vertical angle α between the first direction D1 and the second direction D2 is a positive value, and the vertical angle α between the first direction D1 and the direction opposite to the second direction D2 is a negative value, where the second direction D2 is 90 degrees and the first direction D1 is 0 degrees. In other words, referring to fig. 2 at the same time, fig. 3 corresponds to line segment L1 of fig. 2, and in fig. 2, the center point corresponds to 0 degrees of fig. 3, and the vertical angle α is larger above line segment L1 in fig. 2 and smaller below line segment L1 in fig. 2. In the present embodiment, in the light distribution on the plane X, the portion of the light leaving the light-emitting surface E at 13 degrees to 70 degrees occupies 35% or more, preferably 40% or more, of the total energy of the light leaving the light-emitting surface E. In other words, the light rays preferably concentrate to leave the light exit surface E at a vertical angle α of 13 to 70 degrees, and thus the light guide plate 210 can preferably cooperate with prism sheets (e.g., the first prism sheet 230 and the second prism sheet 240) to increase the optical brightness of the display device. The energy distribution of the light can be determined from the integrated area of the light distribution diagram of fig. 3, that is, the integrated area in the range of 13 degrees to 70 degrees occupies 35% or more of the total integrated area, and is preferably 40% or more.

In the present embodiment, in the light distribution on the plane X, the maximum brightness of the light leaving the light emitting surface E is located at 80 degrees to 90 degrees. In other words, in the present embodiment, the brightness of the light leaving the light-emitting surface E at the vertical angle α of 80 to 90 degrees is the maximum.

Fig. 4 is a light distribution diagram of light rays provided by the light source 220 reaching the display module 100 at different horizontal angles β, wherein the horizontal angle β may be a positive value or a negative value. The horizontal angle β is, for example, an angle between the light reaching the display module 100 and the first direction D1 on the plane Y, and the horizontal angle β between the first direction D1 and the third direction D3 is a positive value, and the horizontal angle β between the first direction D1 and the direction opposite to the third direction D3 is a negative value. In other words, referring to fig. 2 at the same time, fig. 3 corresponds to the line segment L2 of fig. 2. In some embodiments, the light emitted from the light source 220 passes through the light guide plate 210, the first prism sheet 230, the second prism sheet 240, and other optical films (such as a diffuser, a Brightness Enhancement Film (DBEF), or other optical films) before reaching the display module 100. The vertical axis of fig. 4 is in nits and the horizontal axis is in degrees. Referring to fig. 1 and 4, the half-width of the light distribution of the light leaving the light-emitting surface E on the plane Y formed by the first direction D1 and the third direction D3 is about 49 degrees to 52 degrees with the third direction D3 as 90 degrees and the first direction D1 as 0 degrees, wherein the half-width is a half-luminance angle of the light before entering the display module 100, and includes a region with a negative horizontal angle β and a region with a positive horizontal angle β, whereby the light emitted by the backlight module 200 can be more collimated, in some embodiments, the viewing angle of the display device is-24.5 to +24.5 degrees, that is, the first direction D1 is used as a reference to form a symmetric viewing angle distribution with positive and negative angles, and the half-width is 49 degrees, but the invention is not limited thereto. In other embodiments, the viewing angle of the display device may be-10 to +39 degrees, i.e., an asymmetric viewing angle distribution with positive and negative angles formed based on the first direction D1.

Fig. 5 is an oblique view schematically illustrating a display device according to an embodiment of the present invention. It should be noted that the embodiment of fig. 5 follows the element numbers and partial contents of the embodiment of fig. 1, wherein the same or similar element numbers are used to indicate the same or similar elements, and the description of the same technical contents is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which are not repeated herein.

The main difference between the embodiment of fig. 5 and the embodiment of fig. 1 is that: the backlight module 200 of the display device 20 of fig. 5 further includes a diffusion sheet 250. The diffusion sheet 250 is disposed, for example, parallel to the light exit surface E of the light guide plate 210. Referring to fig. 5, the diffusion sheet 250 is disposed between the light guide plate 210 and the first prism sheet 230.

FIG. 6 is a light distribution diagram of a diffuser according to an embodiment of the present invention. Fig. 6 is a light distribution diagram of light rays provided by the light source 220 at different angles after passing through the diffusion sheet 250. For example, fig. 6 is a light distribution diagram of light rays emitted from the light source 220 in fig. 5 after passing through the light guide plate 210 and entering the diffusion sheet 250, and leaving the center of the diffusion sheet 250 at different angles. Fig. 7 is a light distribution diagram of a light guide plate according to an embodiment of the invention, for example, the light distribution diagram of the light guide plate of the embodiment of fig. 5. Specifically, fig. 7 is a light distribution diagram of the light rays provided by the light source 220 leaving the light emitting surface E at different vertical angles α after passing through the light guide plate 210, where the vertical angle α may be a positive value or a negative value. The vertical axis of fig. 7 is in nits and the horizontal axis is in degrees.

Referring to fig. 5 and 7, in the light distribution of the light on the plane X formed by the first direction D1 and the second direction D2, the vertical angle α is, for example, an included angle between the light leaving the light emitting surface E and the plane X of the first direction D1, where the second direction D2 is 90 degrees and the first direction D1 is 0 degree. In other words, referring to fig. 6 at the same time, fig. 7 corresponds to the line segment L1 of fig. 6. In the present embodiment, in the light distribution on the plane X, the portion of the light leaving the light-emitting surface E at 13 degrees to 70 degrees occupies 35% or more, preferably 40% or more, of the total energy of the light leaving the light-emitting surface E. In other words, the light rays preferably concentrate to leave the light exit surface E at a vertical angle α of 13 to 70 degrees, and thus, the light guide plate 210 can preferably cooperate with prism sheets (e.g., the first prism sheet 230 and the second prism sheet 240) to increase the optical brightness of the display device. The energy distribution of the light can be determined from the integrated area of the light distribution diagram of fig. 6, that is, the integrated area in the range of 13 to 70 degrees occupies 35% or more, and preferably 40% or more of the total integrated area.

FIG. 8 is a light distribution diagram of a diffuser according to an embodiment of the present invention. FIG. 9 is a light distribution diagram of a diffuser according to an embodiment of the present invention. Fig. 7 to 9 are light distribution diagrams of the diffusion sheet of the embodiment of fig. 5, for example.

Fig. 8 is a light distribution diagram of light rays provided by the light source 220 leaving the diffusion sheet 250 at different vertical angles γ after passing through the light guide plate 210 and the diffusion sheet 250, wherein the vertical angle γ may be a positive value or a negative value. The vertical axis of fig. 8 is in nits and the horizontal axis is in degrees. Referring to fig. 5 and 8, in the light distribution of the light rays in the plane X formed by the first direction D1 and the second direction D2 with the second direction D2 being 90 degrees and the first direction D1 being 0 degree, the vertical angle γ is, for example, an included angle between the light rays exiting the diffusion sheet 250 and the first direction D1 in the plane X, the vertical angle γ between the first direction D1 and the second direction D2 is a positive value, and the vertical angle γ between the first direction D1 and the direction opposite to the second direction D2 is a negative value. In other words, referring to fig. 6 at the same time, fig. 8 corresponds to the line segment L1 of fig. 6, and in fig. 6, the center point corresponds to 0 degree of fig. 8, and the vertical angle γ in fig. 6 is larger above the line segment L1 and smaller below the line segment L1. In the present embodiment, in the light distribution on the plane X, the partial light rays leaving the diffusion sheet 250 at 13 to 70 degrees account for 70% or more of the total energy of the light rays leaving the light exit surface E. In other words, the light rays preferably concentrate to exit the diffuser plate 250 at a vertical angle γ of 13 to 70 degrees. Therefore, the light guide plate 210 and the diffusion sheet 250 may preferably cooperate with prism sheets (e.g., the first prism sheet 230 and the second prism sheet 240) to increase the optical brightness of the display device. The energy distribution of the light ray can be obtained from the integrated area of the light distribution diagram of fig. 8, that is, the integrated area in the range of 13 degrees to 70 degrees occupies 70% or more of the total integrated area.

In the present embodiment, the maximum brightness of the light exiting the diffusion sheet 250 is located at 40 to 60 degrees in the light distribution on the plane X. In other words, in the present embodiment, the brightness of the light leaving the light-emitting surface E at the vertical angle γ of 40 to 60 degrees is the maximum.

Fig. 9 is a light distribution diagram of light provided by the light source 220 reaching the display module 100 at different horizontal angles δ. Wherein the horizontal angle δ may be positive or negative. The horizontal angle δ is, for example, an angle between the light reaching the display module 100 and the first direction D1 on the plane Y, and the horizontal angle δ between the first direction D1 and the third direction D3 is a positive value, and the horizontal angle δ between the first direction D1 and the direction opposite to the third direction D3 is a negative value. In other words, referring to fig. 6 at the same time, fig. 9 corresponds to the line segment L2 of fig. 6. In some embodiments, the light emitted from the light source 220 passes through the light guide plate 210, the first prism sheet 230, the second prism sheet 240, and other optical films (such as a diffusion sheet, a reflective polarizer, or other optical films) before reaching the display module 100. The vertical axis of fig. 9 is in nits and the horizontal axis is in degrees. Referring to fig. 5 and 9, the half-width of the light distribution of the light reaching the display module 100 in the plane Y formed by the first direction D1 and the third direction D3 is about 49 degrees to 52 degrees with the third direction D3 being 90 degrees and the first direction D1 being 0 degree, wherein the half-width is a half-luminance angle of the light before entering the display module 100 and includes a region with a negative horizontal angle δ and a region with a positive horizontal angle δ, thereby the light emitted by the backlight module 200 can be more collimated, in some embodiments, the viewing angle of the display device is-24.5 to +24.5 degrees, that is, the first direction D1 is used as a reference to form a symmetric viewing angle distribution with positive and negative angles, and the half-width is 49 degrees, but the invention is not limited thereto. In other embodiments, the viewing angle of the display device may be-10 to +39 degrees, i.e., an asymmetric viewing angle distribution with positive and negative angles formed based on the first direction D1.

In summary, the display device of the present invention can make the backlight module have higher brightness and reduce the energy consumption of the display device by adjusting the angle of the light passing through the light guide plate or the light passing through the light guide plate and the diffusion sheet. In some embodiments, the light guide plate is used in combination with the first prism sheet and the second prism sheet to further reduce the horizontal angle of light, so that the light is more concentrated, and the brightness of the backlight module is further increased.

Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A display device, comprising:

a display module; and

a backlight module stacked on the display module along a first direction, the backlight module comprising:

a light guide plate having a light incident surface, a bottom surface and a light emergent surface opposite to the bottom surface, wherein the first direction is perpendicular to the light emergent surface;

the plurality of light sources are arranged on the light incident surface, have the shortest distance with the light guide plate in a second direction and are arranged along a third direction, wherein the first direction, the second direction and the third direction are orthogonal to each other; and

a first prism sheet arranged on the light emergent surface and having multiple first protrusion structures with refractive index greater than or equal to 1.6

The light provided by the light sources passes through the light guide plate, wherein the second direction is 90 degrees and the first direction is 0 degree, in the light distribution of the light on the plane formed by the first direction and the second direction, the part of the light leaving the light-emitting surface at 13-70 degrees occupies more than 35% of the total energy of the light leaving the light-emitting surface, and the maximum brightness of the light leaving the light-emitting surface in the light distribution of the light on the plane formed by the first direction and the second direction is 80-90 degrees and the second direction is 90 degrees and the first direction is 0 degree.

2. The display device of claim 1, wherein the backlight module further comprises:

and the second prism sheet is arranged between the first prism sheet and the light guide plate, and is provided with a plurality of second protrusion structures, and the refractive index of the second protrusion structures is more than or equal to 1.6.

3. The display device of claim 1, wherein the backlight module further comprises:

the reflecting sheet is arranged on the bottom surface of the light guide plate, and the reflectivity of the reflecting sheet is greater than or equal to 95%.

4. The display device according to claim 1, wherein a full width at half maximum of a light distribution of the light reaching the display module in a plane formed by the first direction and the third direction is 49 to 52 degrees with the third direction being 90 degrees and the first direction being 0 degree.

5. The display device of claim 1, wherein the backlight module further comprises:

and a diffusion sheet disposed between the light guide plate and the first prism sheet, wherein the light passes through the diffusion sheet, wherein the second direction is 90 degrees and the first direction is 0 degree, and in the light distribution of the light on the plane formed by the first direction and the second direction, a part of the light leaving the diffusion sheet at 13-70 degrees occupies more than 70% of the total energy of the light.

6. The display device according to claim 5, wherein a full width at half maximum of a light distribution of the light reaching the display module in a plane formed by the first direction and the third direction is 49 to 52 degrees with the third direction being 90 degrees and the first direction being 0 degree.

7. The display device of claim 1, wherein the backlight module comprises:

and the reflecting sheet is arranged on the bottom surface of the light guide plate and comprises diffusion particles.

8. A display device, comprising:

a display module; and

a backlight module stacked on the display module in a first direction, the backlight module comprising:

a light guide plate having a light incident surface, a bottom surface and a light emergent surface opposite to the bottom surface;

A light ray provided by the light sources passes through the light guide plate, wherein the second direction is 90 degrees and the first direction is 0 degree, and in the light distribution of the light ray on a plane formed by the first direction and the second direction, the maximum brightness of the light ray leaving the light-emitting surface is 80-90 degrees.

9. The display device according to claim 8, wherein a full width at half maximum of a light distribution of the light reaching the display module in a plane formed by the first direction and the third direction is 49 to 52 degrees with the third direction being 90 degrees and the first direction being 0 degree.

10. The display device of claim 8, wherein the backlight module further comprises:

and a diffusion sheet disposed between the light guide plate and the first prism sheet, wherein the light passes through the diffusion sheet, and the light leaves the light exit surface at 13-70 degrees in the light distribution of the light in the plane formed by the first direction and the second direction, wherein the second direction is 90 degrees and the first direction is 0 degree, and the total energy of the light is more than 70%.

11. The display device of claim 10, wherein a full width at half maximum of a light distribution of the light reaching the display module in a plane formed by the first direction and the third direction is 49 to 52 degrees, taking the third direction as 90 degrees and the first direction as 0 degree.