CN115576133A - Backlight module and display device - Google Patents

Abstract

The invention relates to a backlight module and a display device. The backlight module comprises: a light guide plate; a lower light source disposed adjacent to a side of the light guide plate; the light collecting element is arranged above the light guide plate in an adjacent mode, a plurality of light collecting structures are arranged on the bottom face of the light collecting element, and the light collecting structures face the light guide plate; and an upper light source disposed adjacent to the light incident side of the light collecting element. The backlight module and the display device realize a narrow visual angle peep-proof mode by only starting the lower light source or realize a wide visual angle sharing mode by simultaneously starting the lower light source and the upper light source.

Description

Backlight module and display device

Technical Field

The invention relates to the technical field of display, in particular to a backlight module capable of switching visual angles and a display device.

Background

With the advancement of technology, electronic devices equipped with liquid crystal displays have become indispensable articles in modern life. However, the viewing angle requirements of display devices vary from one application to another. For example, when it is necessary for a plurality of people to see the content of the display screen at different angles in order to share information with people, the display device is required to have a wide viewing angle, i.e., a sharing mode; when the user only needs to see the content of the display screen to protect privacy while processing personal data, the display product is required to have a narrow viewing angle function, i.e., a peep-proof mode.

In order to solve the above problems, as shown in fig. 1, a display device 10 of a dual light source backlight module includes, from top to bottom, a display panel 11, a first light guide plate 12, a light shielding sheet 13, a reverse prism sheet 14, a second light guide plate 15, a reflective sheet 16, and a first light source 17 and a second light source 18 respectively disposed adjacent to light incident sides of the first light guide plate 12 and the second light guide plate 15.

In the privacy mode, the display device 10 only turns on the second light source 18 below, and light emitted from the second light source 18 is guided by the second light guide plate 15, and then passes through the light-collecting and light-path-limiting elements of the inverse prism sheet 14 and the light-shielding sheet 13, so that the light-emitting angle of light emitted from the display panel 11 is narrow, and thus the display screen is visible only by the user, and the display device 10 has a narrow viewing angle function. In the sharing mode, the display device 10 simultaneously turns on the first light source 17 and the second light source 18, and includes the light emitted from the first light source 17 and guided out through the first light guide plate 12, in addition to the light guided by the second light guide plate 15, at this time, more light reaches the display panel 11, and the light-emitting angle is wider, so that the display screen content can be seen at different angles, and the display device 10 has a wide viewing angle function.

However, the aforementioned technology of switching the viewing angles employs two light guide plates, and actually uses two sets of backlight modules and a light shielding technology to achieve the purpose of switching the viewing angles, so that more layers of optical plates or optical films are used in the structure, thereby resulting in a high overall thickness and cost of the backlight module.

Disclosure of Invention

The invention aims to provide a backlight module technology for integrating a light guide plate and a steering plate, which can achieve the function of switching the visual angle by only one group of backlight modules, so that the overall thickness of the backlight module is reduced, and the cost is also reduced.

In order to achieve the above object, the present invention provides a backlight module, comprising: a light guide plate; a lower light source disposed adjacent to a side of the light guide plate; the light collecting element comprises a light incident side and a bottom surface, the light collecting element is adjacently arranged above the light guide plate, the bottom surface of the light collecting element is provided with a plurality of light collecting structures, and the light collecting structures face the light guide plate; and an upper light source disposed adjacent to the light incident side of the light collecting element.

Preferably, the light collecting element includes a first side and a second side connected to each other, the first side is parallel to a first direction, the second side is parallel to a second direction, the first direction is perpendicular to the second direction, the lower light source includes a plurality of light emitting diodes, and the plurality of light emitting diodes of the lower light source are arranged along the first direction at the side of the light guide plate.

Preferably, the light incident side of the light collecting element is located at the first side, the upper light source includes a plurality of light emitting diodes, and the plurality of light emitting diodes of the upper light source are arranged along the first direction at the first side of the light collecting element. Or, the light incident side of the light collecting element is located at the second side, the upper light source includes a plurality of light emitting diodes, and the plurality of light emitting diodes of the upper light source are arranged along the second direction at the second side of the light collecting element.

Preferably, the light collecting structure is a strip microstructure, and the extending direction of the strip microstructure is substantially parallel to the first direction and perpendicular to the second direction.

Preferably, the light collecting element is an inverse prism, and each light collecting structure has a prism angle, and a tip of the prism angle faces the light guide plate.

Preferably, the bottom surface of the light guide plate is a reflection surface, and the reflection surface is provided with a plurality of light guide structures. Each light guide structure is provided with a light facing surface and a non-light facing surface which are connected with each other, the light facing surface faces the light traveling direction of the light source below, a first included angle is formed between the light facing surface and the reflecting surface, a second included angle is formed between the non-light facing surface and the reflecting surface, and the first included angle is an acute angle and smaller than the second included angle.

Preferably, the light collecting element is provided with uniformly distributed diffusing particles. Or the upper surface of the light collecting element opposite to the bottom surface is provided with a diffusion particle layer.

Preferably, the backlight module further comprises a reflective sheet disposed below the light guide plate.

Another objective of the present invention is to provide a display device, which utilizes a backlight module technology integrating a light guide plate and a turning plate, and only one set of backlight module is needed to achieve the function of switching the viewing angle, so that the overall thickness of the display device is reduced, and the cost is also reduced.

To achieve the above object, the present invention provides a display device, comprising: the backlight module and the display panel are arranged above the backlight module in an adjacent mode.

Compared with the prior art, the invention has the following characteristics: the backlight module is provided with the light sources respectively for the light guide plate and the light collecting element above the light guide plate, so that when the lower light source is turned on and the upper light source is turned off, light rays emitted by the light guide plate are bent and concentrated by the light collecting element to emit light in the forward direction, and the narrow-view-angle peep-proof mode of the backlight module is realized; when the lower light source and the upper light source are both turned on, the light emitted from the light guide plate is bent by the light collecting element to emit light in the forward direction, and the light which does not pass through the light guide plate but only passes through the light collecting element is bent to emit light in a dispersed manner, so that the wide-view angle sharing mode of the backlight module is realized. The backlight module of the invention needs less optical plates or optical diaphragms, so that the overall thickness of the backlight module is reduced, and the cost is also reduced.

Drawings

Fig. 1 is a schematic side view of a display device of a conventional viewing angle switching backlight module.

Fig. 2 is a schematic view of a backlight module according to an embodiment of the present application.

Fig. 3 is a schematic view of a backlight module according to another embodiment of the present application.

Fig. 4 is a schematic side view of a display device to which the embodiment shown in fig. 3 is applied.

Fig. 5 is a schematic diagram of a first implementation of a light collecting element in an embodiment of the present application.

Fig. 6 is a schematic diagram of a second embodiment of a light collecting element in an embodiment of the present application.

Fig. 7 is a first schematic diagram of a ray path in an embodiment of the present application.

Fig. 8 is a second schematic diagram of a ray path in an embodiment of the present application.

Fig. 9 is a view angle-luminance graph of a display device to which the embodiment shown in fig. 3 is applied.

Fig. 10 is a schematic side view of a display device to which the embodiment shown in fig. 2 is applied.

Fig. 11 is a view angle-luminance graph of a display device to which the embodiment shown in fig. 2 is applied.

Detailed Description

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams mainly for illustrating the basic structure of the present invention in a schematic manner, so that only the elements related to the present invention are labeled in the drawings, and the illustrated elements are not drawn in terms of number, shape, size ratio and the like in implementation, and the specification and the size in actual implementation are actually an optional design, and the layout of the elements may be more complicated.

The following description of the embodiments refers to the accompanying drawings that illustrate specific embodiments in which the invention may be practiced. Directional phrases used in this disclosure, such as "up," "down," "front," "back," etc., refer to those directions only as viewed in drawing figures. Accordingly, the directional terms used are used for illustration and understanding of the present application, and are not used to limit the present application. In addition, in the description, unless explicitly described to the contrary, the word "comprise" will be understood to mean that a certain element is included, but not to exclude any other elements.

Please refer to fig. 2 and fig. 3, which are schematic diagrams of a backlight module according to an embodiment of the invention. The backlight module 100 includes: a light guide plate 200; a lower Fang Guangyuan adjacently disposed to the side edge 210 of the light guide plate 200; a light collecting element 300 including a light incident side 311 (shown in fig. 2) or 321 (shown in fig. 3) and a bottom surface 340, wherein the light collecting element 300 is disposed adjacent to the upper side of the light guide plate 200, the bottom surface 340 of the light collecting element 300 is provided with a plurality of light collecting structures 350, and the light collecting structures 350 face the light guide plate 200; and an upper light source 500 disposed adjacent to the light incident side 311 (shown in fig. 2) or 321 (shown in fig. 3) of the light collecting element 500.

In the backlight module 100 of the present application, the light sources 400 and 500 are respectively disposed on the light guide plate 200 and the light collecting element 300 above the light guide plate, so that when the light source 400 below is turned on and the light source 500 above is turned off, the light emitted from the light guide plate 200 is bent and concentrated into forward light through the light collecting element 300, thereby implementing the narrow-view peep-proof mode of the backlight module 100; when the lower light source 400 and the upper light source 500 are both turned on, the light emitted from the lower light source 400 through the light guide plate 200 is bent by the light collecting element 300 to emit light in the forward direction, and the light emitted from the upper light source 500 is dispersed by the light collecting element 300 to realize the wide viewing angle sharing mode of the backlight module 100. Compared with the prior art, the backlight module 100 of the present application requires a smaller number of optical plates or optical films, and the overall thickness of the structure can be reduced, thereby reducing the cost.

In an implementation application, the backlight module 100 further includes a reflective sheet 600, and the reflective sheet 600 is disposed below the light guide plate 200.

Referring to fig. 4, a schematic side view of a display device using the embodiment shown in fig. 3 is shown. When the backlight module 100 is applied to the display device 1000, the display device 1000 at least includes the display panel 700 and the backlight module 100, and the display panel 700 is disposed adjacent to the upper side of the backlight module 100.

In an implementation, the light collecting element 300 includes a first side 310 and a second side 320 connected to each other, the first side 310 is parallel to the first direction D1, the second side 320 is parallel to the second direction D2, and the first direction D1 is perpendicular to the second direction D2. In practice, the bottom light source 400 includes a plurality of light emitting diodes 410, the light emitting diodes 410 are arranged on the side 210 of the light guide plate 200 along the first direction D1, and the side 210 substantially serves as the light incident side of the light guide plate 200.

In an implementation, the light incident side 311 of the light collecting element 300 may be located at the first side 310, and the upper light source 500 includes a plurality of light emitting diodes 510, and the plurality of light emitting diodes 510 are arranged along the first direction D1 and disposed on the first side 310 (as shown in fig. 2) of the light collecting element 300. Alternatively, in an implementation, the light incident side 321 of the light collecting element 300 is located at the second side 320, the upper light source 500 includes a plurality of light emitting diodes 510, and the plurality of light emitting diodes 510 are arranged on the second side 320 (as shown in fig. 3) of the light collecting element 300 along the second direction D2.

In an implementation, the bottom surface 340 of the light collecting element 300 is provided with a plurality of light collecting structures 350, the light collecting structures 350 are strip-shaped microstructures, and an extending direction of the strip-shaped microstructures is substantially parallel to the first direction D1 and perpendicular to the second direction D2. In a preferred embodiment, the light collecting element 300 is an inverse prism, and the light collecting structure 350 has a prism angle 351, so that the light collecting structure 350 is a stripe-shaped microstructure having the prism angle 351, and a tip of the prism angle 351 faces the light guide plate 200.

In an implementation, as shown in fig. 7, since the light collecting element 300 needs a specific light incident angle range to convert the oblique light generated by the light guide plate 200 into the light in the front viewing direction through the light collecting element 300 and then emit the light, in order to improve the directivity of the light guide plate 200, the bottom surface of the light guide plate 200 is used as the reflective surface 230, and a plurality of light guide structures 240 are formed on the reflective surface 230. Each light guide structure 240 has a light-facing surface 241 and a non-light-facing surface 242 connected to each other, the light-facing surface 241 faces the light traveling direction of the downward light source 400, a first included angle α is formed between the light-facing surface 241 and the reflective surface 230, a second included angle β is formed between the non-light-facing surface 242 and the reflective surface 230, the first included angle α and the second included angle β are both acute angles, and the first included angle α is smaller than the second included angle β (as shown in fig. 4). The design of the first included angle α and the second included angle β can change the inclination degree of the light-facing surface 241 and the non-light-facing surface 242, so as to control the direction and concentration degree of the light emitted from the light-emitting surface of the light guide plate 200 for further use by the light collecting element 300, thereby effectively guiding the light to emit light at a normal viewing angle.

In the application of the present disclosure, if only the lower light source 400 is turned on, the display device 1000 only provides light through the lower light guide plate 200, and the light guide structure 240 of the light collecting element 300 is used for converting the light into forward light, so as to realize the narrow viewing angle privacy mode of the backlight module 100. If the lower light source 400 and the upper light source 500 are both turned on, the light from the upper light source 500 is further bent by the light collecting element 300 to be dispersed out of the light, in addition to the light from the lower light source 400 being emitted by the light guide plate 200 and then being bent by the light collecting element 300 to be emitted forward, so as to realize the wide view angle sharing mode of the backlight module 100.

Further, the light collecting device 300 can use diffusing particles to improve the side view angle energy of the sharing mode, providing a wide view angle distribution. In practice, when the light collecting element 300 is prepared, the light collecting element 300 is provided with the uniformly distributed diffusing particles 301 (as shown in fig. 5), so that the light passing through the light collecting element 300 can be better bent and dispersed to provide a wide viewing angle distribution. Alternatively, a diffusing particle layer 370 (as shown in fig. 6) is disposed on the upper surface 360 of the light collecting element 300 opposite to the bottom surface 340 thereof, and the light passing through the upper surface 360 of the light collecting element 300 can be better refracted and dispersed by the diffusing particle layer 370, so as to provide a wide viewing angle distribution.

Hereinafter, the principle of the narrow viewing angle privacy mode and the wide viewing angle sharing mode will be described in more detail, and the optical path applying the backlight module shown in fig. 3 will be described with reference to fig. 7 and 8. In the backlight module 100, the lower light sources 400 and the upper light sources 500 are respectively disposed on the light guide plate 200 and the light collecting element 300 above the light guide plate, the lower light sources 400 disposed on the light guide plate 200 are arranged along the first direction D1, the upper light sources 500 disposed on the light collecting element 300 are arranged along the second direction D2, and the lower light sources 400 and the upper light sources 500 are arranged vertically to each other.

When only the lower light source 400 is turned on, the light L1 emitted by the lower light source 400 is reflected by the light guide plate 200 with high directivity, and then is bent and concentrated into forward light (as shown by the upward arrow with the dotted line in fig. 7) by the light collecting structure 350 of the light collecting element 300, and the light is provided to the display panel 700 only by the light guide plate 200, so that the narrow viewing angle distribution of the light emitting direction of the backlight module 100 is realized, that is, the upward arrow with the dotted line in fig. 7 is the forward light, and the display device 1000 exhibits the narrow viewing angle peep-proof mode.

When the lower light source 400 and the upper light source 500 are both turned on, in addition to the forward light emitted by the light L1 of the lower light source 400 through the light guide plate 200 and the light collecting element 300, the light L2 of the upper light source 500 is also dispersed and emitted by the light collecting element 300 (as shown by the oblique arrows with dotted lines facing upward from left and upward from right in fig. 8), and the light is provided to the display panel 700 through the light guide plate 200 and the light collecting element 300, so that the wide viewing angle distribution of the light emitting direction of the backlight module 100 can be realized, that is, in fig. 8, in addition to the upward arrow with dotted lines facing upward from the forward light in fig. 7, the oblique arrows with dotted lines facing upward from left or/and upward from right are further added, so that the display device 1000 exhibits a wide viewing angle sharing mode. Moreover, as mentioned above, the light collecting element 300 can make the light L2 have better turning dispersion by means of the diffusing particles to improve the side view angle energy of the sharing mode, thereby providing a wide view angle distribution.

In addition, since the extending directions of the upper light source 500 and the light collecting structure 350 are parallel to the second direction D2 and the first direction D1 perpendicular to each other, respectively, that is, the upper light source 500 is located at a certain side of the light collecting element 300, when viewed along the first direction D1, the light collecting structure 350 presents a triangle as shown in fig. 7, and when viewed along the second direction D2, presents a plane as shown in fig. 8, which is easy to make the light emitted by the upper light source 500 generate total reflection, thereby further increasing the proportion of the oblique light outgoing from the direction away from the upper light source 500, so that the oblique light outgoing can also generate a left-right asymmetry phenomenon, that is, the light intensity represented by the oblique arrow with the dotted line facing upward to the right in fig. 8 is greater than the light intensity represented by the oblique arrow with the dotted line facing upward to the left, so that the wide-viewing angle sharing mode presented by the display device 1000 is more suitable for a vehicle-mounted display installed in the center of a driver's seat or an auxiliary seat in a certain side.

As can be seen from fig. 9, in the structure of the backlight module 100 shown in fig. 3, when only the lower light source 400 is turned on, the light-emitting luminance is concentrated between the viewing angle ranges of-40 degrees to 40 degrees, but when the lower light source 400 and the upper light source 500 are turned on simultaneously, the light-emitting luminance at the viewing angle greater than 40 degrees is improved. It was measured that the viewing angle energy increases at 40 and 45 degrees.

Please refer to fig. 10, which is a side view of a display device applying the embodiment shown in fig. 2. In the backlight module 100, the lower light sources 400 and the upper light sources 500 are respectively disposed on the light guide plate 200 and the light collecting element 300 above the light guide plate, the lower light sources 400 disposed on the light guide plate 200 are arranged along the first direction D1, the upper light sources 500 disposed on the light collecting element 300 are arranged along the first direction D1, and the lower light sources 400 and the upper light sources 500 are arranged in the same direction.

As can be seen from fig. 11, in the structure of the backlight module 100 in fig. 2, when only the lower light source 400 is turned on, the light-emitting luminance is concentrated between the viewing angle ranges of-40 degrees to 40 degrees, but when the lower light source 400 and the upper light source 500 are turned on simultaneously, the light-emitting luminance at the viewing angle greater than 40 degrees is also improved.

In summary, the light guide plate and the light collecting element above the light guide plate are respectively provided with the light source, so that when the lower light source is turned on and the upper light source is turned off, light emitted by the light guide plate is bent and concentrated into forward light through the light collecting element, and a narrow-view peep-proof mode of the backlight module is realized; when the lower light source and the upper light source are both turned on, the light emitted from the light guide plate is bent by the light collecting element to emit light in the forward direction, and the light which does not pass through the light guide plate but only passes through the light collecting element is dispersed to emit light, so that the wide-view angle sharing mode of the backlight module is realized. The invention can achieve the function of switching visual angles without using shading sheets, and the number of the optical plates or the optical films required by the invention is less, thereby reducing the overall thickness of the backlight module and reducing the cost.

The above-described embodiments are merely illustrative of the principles, features and effects of the present invention, and are not intended to limit the scope of the invention, which can be modified and varied by those skilled in the art without departing from the spirit and scope of the invention. Any equivalent changes and modifications made using the present disclosure should still be covered by the appended claims.

[ List of reference numerals ]

(conventional)

10: display device

11: display panel

12: first layer light guide plate

13: anti-dazzling screen

14: reverse prism lens

15: second layer light guide plate

16: reflector plate

17: first light source

18: second light source

(this application)

100: backlight module

200: light guide plate

210: side edge

230: reflecting surface

240: light guide structure

241: light-facing surface

242: non-light-facing side

300: light collecting element

301: diffusing particles

310: the first side edge

320: second side edge

311. 321: incident side

340: bottom surface

350: light collecting structure

351: prism angle

360: upper surface of

370: diffusion particle layer

400: lower light source

410. 510: light emitting diode

500: upper light source

600: reflector plate

700: display panel

1000: display device

D1: a first direction

D2: second direction

α: first included angle

Beta: and a second included angle.

Claims (12)

1. A backlight module, comprising:

a light guide plate;

the lower light source is arranged adjacent to the side edge of the light guide plate;

the light collecting element comprises a light incident side and a bottom surface, the light collecting element is adjacently arranged above the light guide plate, the bottom surface of the light collecting element is provided with a plurality of light collecting structures, and the light collecting structures face the light guide plate; and

and the upper light source is arranged adjacent to the light incident side of the light collecting element.

2. The backlight module according to claim 1, wherein the light collecting element comprises a first side and a second side connected to each other, the first side is parallel to a first direction, the second side is parallel to a second direction, the first direction is perpendicular to the second direction, the lower light source comprises a plurality of light emitting diodes, and the light emitting diodes of the lower light source are arranged along the first direction at the side of the light guide plate.

3. The backlight module according to claim 2, wherein the light incident side of the light collecting element is located at the first side, the upper light source comprises a plurality of light emitting diodes, and the plurality of light emitting diodes of the upper light source are arranged along the first direction at the first side of the light collecting element.

4. The backlight module according to claim 2, wherein the light incident side of the light collecting element is located at the second side, the upper light source comprises a plurality of light emitting diodes, and the plurality of light emitting diodes of the upper light source are arranged along the second direction at the second side of the light collecting element.

5. The backlight module as claimed in claim 2, wherein each of the light collecting structures is a stripe-shaped microstructure extending in a direction parallel to the first direction and perpendicular to the second direction.

6. The backlight module as claimed in claim 1, wherein the light collecting elements are inverse prism sheets, each of the light collecting structures has a prism angle, and a tip of the prism angle faces the light guide plate.

7. The backlight module as claimed in claim 1, wherein the bottom surface of the light guide plate is a reflective surface, and the reflective surface has a plurality of light guide structures formed thereon.

8. The backlight module according to claim 7, wherein each of the light guide structures has a light-facing surface and a non-light-facing surface connected to each other, the light-facing surface faces a light traveling direction of the lower light source, a first included angle is formed between the light-facing surface and the reflective surface, and a second included angle is formed between the non-light-facing surface and the reflective surface, and the first included angle is an acute angle and smaller than the second included angle.

9. The backlight module as claimed in claim 1, wherein the light collecting element is provided with uniformly distributed diffusing particles.

10. The backlight module of claim 1, wherein the top surface of the light collecting element opposite to the bottom surface has a diffusion particle layer.

11. The backlight module according to claim 1, further comprising a reflective sheet disposed under the light guide plate.

12. A display device, comprising:

a display panel; and

the backlight module according to any of claims 1-11, wherein the display panel is disposed adjacent to and above the backlight module.

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