Wedge-shaped light guide plate for a collimating backlight module and collimating backlight module

Abstract

A wedge-shaped light guide plate (01) for a collimating backlight module and the collimating backlight module thereof, wherein the wedge-shaped light guide plate (01) is surrounded by a thick end light-input surface (003), a first light-output surface (001), a second light-output surface (002) and two side surfaces, the first light-output surface (001) and the second light-output surface (002) form a wedge angle, and a light-input microprism structure is provided on the light-input surface (003), and the collimating backlight module has at least one The collimated backlight module comprises a wedge-shaped light guide plate (01), a strip light source (02) disposed on the light incident surface (003) side of the wedge-shaped light guide plate (01), an inverted prism film (03) disposed on the first light exit surface (001), and a reflective film (04) disposed on the second light exit surface (002), the strip light source (02) extending from one side to the other of the wedge-shaped light guide plate (01), and the surface of the inverted prism film (03) with the microprism structure facing the first light exit surface (001). This method can achieve the purpose of controlling the light exit angle to suit various application requirements, and the half-width distribution of the light exit angle of the collimated backlight module can reach ±25°.

Description

Technical Field

[0001] The present invention relates to a collimating backlight module for a liquid crystal display, and to a wedge-shaped light guide plate for a collimating backlight module and a collimating backlight module thereof.

Background Art

[0002] In recent years, as people's requirements for the confidentiality of electronic data have been increasing, the demand for anti-peeping screens has been increasing, and the demand in the terminal market is high. Currently, the solutions for preventing peeping of display screens are mainly divided into two types. (1) Adding an anti-peeping film to the original display module. (2) By using a backlight module with anti-peeping characteristics, the purpose of preventing peeping is achieved.

[0003] However, the collimating backlight module belonging to the second type of application scenario still has room for improving the light emission collimation in the dimension perpendicular to the light propagation direction.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technical problem to be solved by the present invention is to provide a wedge-shaped light guide plate for a backlight module and a collimating backlight module thereof that can effectively improve the light emission collimation in the dimension perpendicular to the light propagation direction.

Means for Solving the Problems

[0005] As a technical means for the present invention to solve the above technical problems, a wedge-shaped light guide plate for a collimating backlight module, which is surrounded by a light incident surface, a first light emitting surface, a second light emitting surface and two side surfaces at the thick end, the first light emitting surface and the second light emitting surface form a wedge angle, and a light incident micro prism structure is installed on the light incident surface.

[0006] The incident light micro prism structure is composed of a plurality of incident light micro prism strips installed in parallel, and the incident light micro prism strip extends from one side surface of the wedge-shaped light guide plate to the other side surface, or extends from the first light emitting surface to the second light emitting surface.

[0007] The cross section of the incident light micro prism strip is triangular.

[0008] The incident light micro prism structure is composed of a plurality of incident light micro prism grooves installed in parallel, and the incident light micro prism groove extends from one side surface of the wedge-shaped light guide plate to the other side surface, or extends from the first light emitting surface to the second light emitting surface.

[0009] The incident light micro prism groove is a triangular groove.

[0010] A light emitting micro prism structure is installed on at least one of the first light emitting surface and the second light emitting surface.

[0011] The light emitting micro prism structure is composed of a plurality of light emitting micro prism strips installed in parallel, and the light emitting micro prism strip extends from the thick end portion of the wedge-shaped light guide plate to the thin end portion.

[0012] The cross section of the light emitting micro prism strip is a triangle, an arc or a trapezoid with an apex angle of 40° - 170°.

[0013] The light emitting micro prism structure is composed of a plurality of light emitting micro prism grooves installed in parallel, and the light emitting micro prism groove extends from the thick end portion of the wedge-shaped light guide plate to the thin end portion.

[0014] The light emitting micro prism groove is a triangular groove, an arc groove or a trapezoid groove with an apex angle of 40° - 170°.

[0015] The collimating backlight module equipped with the wedge-shaped light guide plate comprises at least one wedge-shaped light guide plate, a strip-shaped light source installed on the light incident surface side of the wedge-shaped light guide plate, a reverse prism film installed on the first light emitting surface side, and a reflection film installed on the second light emitting surface side. The strip-shaped light source extends from one side surface of the wedge-shaped light guide plate to the other side surface, and the surface on which the micro prism structure of the reverse prism film is installed faces the first light emitting surface.

[0016] There is one wedge-shaped light guide plate, a first light emitting micro prism structure is installed on the first light emitting surface, and a second light emitting micro prism structure is installed on the second light emitting surface.

[0017] There are a plurality of wedge-shaped light guide plates, and the plurality of wedge-shaped light guide plates are stacked up and down. A first light emitting micro prism structure is installed on the first light emitting surface of the wedge-shaped light guide plate adjacent to the reverse prism film, and a second light emitting micro prism structure is installed on the second light emitting surface of the wedge-shaped light guide plate adjacent to the reflection film.

[0018] The micro prism structure of the reverse prism film is a symmetric or asymmetric triangular structure.

Advantages of the Invention

[0019] Compared with the prior art, the advantages of the present invention are that a specific light incident micro prism structure is installed on the light incident surface of the wedge-shaped light guide plate, and by combining with the reverse prism film of a specific structure, the purpose of controlling the light emitting angle can be achieved to meet the requirements of various applications. The collimating backlight module using the wedge-shaped light guide plate and the reverse prism film structure of the present invention can achieve a half-value width distribution of the light emitting angle of ±25°, which is superior to the viewing prevention angle of most of the currently commercially available viewing prevention films.

Brief Description of the Drawings

[0020]

Figure 1

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Figure 9

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the present invention will be described in more detail with reference to the drawings and examples.

[0022] Example: As shown in FIG. 1, the novel collimating backlight module includes a wedge-shaped light guide plate 01, a strip light source 02, a reverse prism film 03, and a reflective film 04. As shown in FIGS. 2 and 3, the structure of the wedge-shaped light guide plate 01 is surrounded by a light incident surface 003 at the thick end, a first light exit surface 001, a second light exit surface 002, and two side surfaces. The first light exit surface 001 and the second light exit surface 002 of the wedge-shaped light guide plate 01 form a wedge angle α. A first light exit micro-prism structure is installed on the first light exit surface 001, a second light exit micro-prism structure is installed on the second light exit surface 002, and a light incident micro-prism structure is installed on the light incident surface 003. Both the first light exit micro-prism structure and the second light exit micro-prism structure are composed of a plurality of parallel light exit micro-prism strips or light exit micro-prism grooves extending from the thick end to the thin end of the wedge-shaped light guide plate 01. The light incident micro-prism structure is composed of a plurality of parallel light incident micro-prism strips or light incident micro-prism grooves extending from one side surface to the other side surface of the wedge-shaped light guide plate 01. The strip light source 02 is installed on the side of the light incident surface 003 of the wedge-shaped light guide plate 01 and extends from one side surface to the other side surface of the wedge-shaped light guide plate 01. The reflective film 04 is installed on the side of the second light exit surface 002, and the reverse prism film 03 is installed on the side of the first light exit surface 001. The surface of the reverse prism film 03 on which the micro-prism structure is installed faces the first light exit surface 001. In this embodiment, the micro-prism structure of the reverse prism film 03 is a symmetric isosceles triangle structure.

[0023] In this embodiment, the cross-section of the light exit micro-prism strip may be a symmetric or asymmetric triangle with an apex angle of 40° - 170°, or may be arc-shaped or trapezoidal, and the cross-section of the light incident micro-prism strip is a triangle.

[0024] On the other hand, the light exit micro-prism groove may be a symmetric or asymmetric triangular groove with an apex angle of 40° - 170°, or may be an arc-shaped groove or a trapezoidal groove.

[0025] FIG. 4 is a schematic diagram of the wedge-shaped light guide plate 01 in this embodiment. The incident light micro prism structure is a symmetric triangular structure, the first light-emitting micro prism structure is an arc-shaped structure, and the second light-emitting micro prism structure is a symmetric triangular structure.

[0026] FIG. 5 shows the process of light propagating between the first light-emitting micro prism structure, the reflective film 04, and the second light-emitting micro prism structure in the vertical direction. Light 11 is directly emitted from the inside of the wedge-shaped light guide plate 01 to the first light-emitting micro prism structure, refracted by the first light-emitting micro prism structure, and emitted into the air. In this process, the first light-emitting micro prism structure has a certain converging effect on the light emitted into the air. Light 12 is emitted from the inside of the wedge-shaped light guide plate 01 to the second light-emitting micro prism structure, then passes through the reflective film 04, is reflected by the reflective film 04 and recovered, passes through the second light-emitting micro prism structure, returns to the inside of the wedge-shaped light guide plate 01, and performs the next cycle.

[0027] FIG. 6 shows that after light 13 and light 14 are emitted from the strip light source 02 and pass through the incident light micro prism structure, they are refracted from the original propagation direction to the first light-emitting surface 001 and the second light-emitting surface 002. The main function of the incident light micro prism structure is to adjust the distribution of the light introduced into the wedge-shaped light guide plate 01 to achieve the purpose of changing the light emission of the wedge-shaped light guide plate 01.

[0028] FIG. 7 shows the process of light 15, light 16, and light 17 from the inside of the wedge-shaped light guide plate 01 propagating inside the collimating backlight module.

[0029] After light 15 is emitted from the incident surface 003, it propagates from the inside of the light guide plate to the first light-emitting surface 001. Since the total reflection condition is not satisfied, it is refracted by the first light-emitting surface 001 and enters the air and propagates to the reverse prism film 03. The light is refracted from one surface of the micro structure of the reverse prism film and enters the inside of the micro structure, reaches the other surface of the micro structure. At this time, the light satisfies the total reflection condition, and the emission direction of the light after total reflection is substantially parallel to the normal direction of the reverse prism film.

[0030] Light 16 emits from the light incident surface 003, propagates to the second light exit surface 002. At this time, since the total reflection condition is not satisfied, it is refracted by the second light exit surface 002 and propagates to the surface of the reflection film 04, and is specularly reflected on the surface of the reflection film 04. Then light 16 is refracted by the second light exit surface and enters the light guide plate again. Light 16 travels straight inside the light guide plate to the first light exit surface 001. Since the total reflection condition is not satisfied, after being refracted by the first light exit surface 001, light 16 propagates to one surface of the prism structure in the reverse prism film 03, is refracted and enters the inside of the micro-structure. When the light incident position is close to one bottom angle of the micro prism, the refracted light cannot reach the other surface of the micro-structure. At this time, light 16 travels straight at the refracted angle until it exits from the other surface of the reverse prism film 03. The light passing through this process is not totally reflected on the other surface of the micro-structure, so its propagation direction deviates slightly more from the normal direction of the reverse prism film, forming a certain included angle with the light ray emitted by light 15. This is also the origin of the half-value width of the emitted light of the collimating backlight module according to the present invention.

[0031] After light 17 emits from the light incident surface 003, it propagates to the second light exit surface 002 inside the light guide plate 01. At this time, since the total reflection condition is satisfied, the light is totally reflected by the second light exit surface 002, and the direction of the light is changed and it continues to propagate inside the light guide plate. Until the total reflection condition is no longer satisfied, the light emits like light 15 or light 16.

[0032] Embodiment 2: As shown in FIGS. 8 and 9, there are two light guide plates 011 and 012 laminated from top to bottom. In this embodiment, taking two layers of light guide plates as an example, the process of light propagating in multiple layers of light guide plates will be described.

[0033] As shown in FIG. 9, the light 18 propagates from the incident surface 003 to the first light-emitting surface 001 of the wedge-shaped light guide plate 011. At this time, since the total reflection condition is not satisfied, it is refracted by the first light-emitting surface 001 and enters the air, and propagates to one side of the micro prism structure of the reverse prism film 03. The light 18 is refracted and enters the inside of the micro prism structure. At this time, since the light 18 is close to one bottom angle of the micro prism structure, the light travels straight to the uppermost boundary of the reverse prism film 03, is refracted and directly emitted. Since the light 18 is not refracted by the other side of the micro prism structure of the reverse prism film 03, the included angle between the emission direction and the normal direction of the reverse prism film 03 is relatively large.

[0034] The light 19 is emitted from the incident surface 003 and travels straight to the first light-emitting surface 001 of the wedge-shaped light guide plate 011 inside the wedge-shaped light guide plate 011. At this time, the light satisfies the total reflection condition and is totally reflected by the first light-emitting surface 001, and the direction is changed to continue propagating inside the wedge-shaped light guide plate 011. When the total reflection condition is satisfied, each time the light is totally reflected on the first light-emitting surface 001 and the second light-emitting surface 002, the included angle with the normal direction of the corresponding light-emitting surface decreases by one wedge angle until the total reflection condition is no longer satisfied and it is emitted. As shown in FIG. 9, when the light does not satisfy the total reflection condition for the first time at the first light-emitting surface 001 of the wedge-shaped light guide plate 011, the light 19 is refracted by the first light-emitting surface 001 and enters the air, and propagates to one side of the micro prism structure of the reverse prism film 03. After being refracted, it enters the inside of the micro prism structure. When the light is close to the apex angle of the micro prism structure of the reverse prism film 03, the light 19 travels straight to the other side of the micro prism structure after being refracted, and after being totally reflected by this side, it is refracted by the uppermost boundary of the reverse prism film 03 and emitted. At this time, the included angle between the light 19 and the normal direction of the reverse prism film 03 is very small and it is collimated and emitted.

[0035] The light 20 emits from the light incident surface 003 and travels straight inside the wedge-shaped light guide plate 011 towards the second light-emitting surface 002 of the wedge-shaped light guide plate 011. At this time, since the total reflection condition is not satisfied, the light is refracted by the second light-emitting surface 002 and enters the gap between the wedge-shaped light guide plate 011 and the wedge-shaped light guide plate 012. Then it travels straight towards the first light-emitting surface 001 of the wedge-shaped light guide plate 012, is refracted by the first light-emitting surface 001 and enters the inside of the wedge-shaped light guide plate 012. Inside the wedge-shaped light guide plate 012, it travels straight towards the second light-emitting surface 002 of the wedge-shaped light guide plate 012. At this time, the light 20 still does not satisfy the total reflection condition and is refracted by the second light-emitting surface 002 of the wedge-shaped light guide plate 012 and enters the air, then travels straight towards the reflection film 04. After specular reflection, it is refracted by the second light-emitting surface 002 of the wedge-shaped light guide plate 012 and returns to the inside of the wedge-shaped light guide plate 012, then travels straight towards the first light-emitting surface 001 of the wedge-shaped light guide plate 012. As can be seen from the above analysis, here the light does not satisfy the total reflection condition and is refracted by the first light-emitting surface 001 of the wedge-shaped light guide plate 012 and returns to the gap between the wedge-shaped light guide plate 011 and the wedge-shaped light guide plate 012 again, then travels straight towards the second light-emitting surface 002 of the wedge-shaped light guide plate 011 and is refracted by the second light-emitting surface 002 and enters the inside of the wedge-shaped light guide plate 011. The light 20 travels straight towards its first light-emitting surface 001 inside the wedge-shaped light guide plate 011, is refracted and enters the air, propagates along one side of the micro prism structure of the reverse prism film 03, is refracted by the micro prism structure and enters the inside of the reverse prism film. The subsequent propagation process is similar to that of the light 18, and finally it is emitted into the air.

[0036] The light 21 emits from the light-incident surface 003, travels straight inside the wedge-shaped light guide plate 012 towards the second light-emitting surface 002 of the wedge-shaped light guide plate 012. At this time, it satisfies the total reflection condition and is totally reflected, then continues to propagate inside the wedge-shaped light guide plate 012 towards its first light-emitting surface 001. At this time, since the light 21 has been totally reflected once, the angle between the direction of the light 21 and the normal direction of the first light-emitting surface 001 of the wedge-shaped light guide plate 012 becomes smaller by one wedge angle α. At this time, the light 21 no longer satisfies the total reflection condition at the first light-emitting surface 001, is refracted by the first light-emitting surface 001 and enters the gap between the wedge-shaped light guide plate 011 and the wedge-shaped light guide plate 012. The light 21 travels straight inside the gap towards the second light-emitting surface 002 of the wedge-shaped light guide plate 011, is refracted and enters the inside of the wedge-shaped light guide plate 011, and continues to travel straight towards the first light-emitting surface 001 of the wedge-shaped light guide plate 011. At this time, it still does not satisfy the total reflection condition and is refracted by the first light-emitting surface 001 and enters the air. The light 21 travels straight towards one side of the micro prism structure of the reverse prism film 03 in the air, is refracted here and enters the inside of the micro prism structure. When it reaches the other side of the micro prism structure, it is totally reflected and propagates to the interface of the uppermost layer of the reverse prism film 03, and is refracted and emitted.

[0037] In this embodiment, the representative light propagation process in the collimating backlight module provided with a plurality of layers of light guide plates is described in detail. For other lights not described, they can refer to the lights in the above embodiment and this embodiment and propagate inside the module, and finally be emitted into the air.

[0038] In the present invention, the prism structure of the reverse prism film 03 may be an asymmetric triangular structure.

Claims

1. A collimating backlight module comprising a wedge-shaped light guide plate, having a plurality of the wedge-shaped light guide plates stacked one above the other, each of the wedge-shaped light guide plates being surrounded by a light incident surface at the thick end, a first light emitting surface, a second light emitting surface and two side surfaces, the first light emitting surface and the second light emitting surface forming a wedge angle, each of the wedge-shaped light guide plates having the light incident surface facing the same side, and a light incident micro prism structure being provided on each of the light incident surfaces, a strip light source being provided on the light incident surface side of the plurality of the wedge-shaped light guide plates, the topmost wedge-shaped light guide plate being provided with a reverse prism film on the first light emitting surface side thereof, and a first light emitting micro prism structure being provided on the first light emitting surface of the topmost wedge-shaped light guide plate, the lowermost wedge-shaped light guide plate being provided with a reflective film on the second light emitting surface side thereof, and a second light emitting micro prism structure being provided on the second light emitting surface of the lowermost wedge-shaped light guide plate, the strip light source extending from one side surface of the wedge-shaped light guide plate to the other side surface, the surface of the reverse prism film on which the micro prism structure is provided facing the first light emitting surface of the topmost wedge-shaped light guide plate, the collimating backlight module, wherein each of the first light emitting micro prism structure and the second light emitting micro prism structure extends from the thick end to the thin end of the wedge-shaped light guide plate.

2. The collimating backlight module according to claim 1, wherein the micro prism structure of the reverse prism film is a symmetric or asymmetric triangular structure.

3. At least one of the first light emitting micro prism structure and the second light emitting micro prism structure comprises a plurality of light emitting micro prism strips arranged in parallel, the collimating backlight module according to claim 1 or claim 2, wherein a cross section of the light emitting micro prism strip is a triangle, an arc or a trapezoid with an apex angle of 40° - 170°.

4. At least one of the first light emitting micro prism structure and the second light emitting micro prism structure comprises a plurality of light emitting micro prism grooves arranged in parallel, the collimating backlight module according to claim 1 or claim 2, wherein the light emitting micro prism groove is a triangular groove, an arc-shaped groove or a trapezoidal groove with an apex angle of 40° - 170°.

5. The incident light microprism structure is composed of a plurality of incident light microprism strips installed in parallel, and the incident light microprism strip extends from one side surface of each of the wedge-shaped light guide plates to the other side surface, or extends from the first light emitting surface to the second light emitting surface. The collimating backlight module according to claim 1 or claim 2, characterized in that.

6. The collimating backlight module according to claim 5, characterized in that the cross section of the incident light microprism strip is triangular.

7. The incident light microprism structure is composed of a plurality of incident light microprism grooves installed in parallel, and the incident light microprism groove extends from one side surface of each of the wedge-shaped light guide plates to the other side surface, or extends from the first light emitting surface to the second light emitting surface. The collimating backlight module according to claim 1 or claim 2, characterized in that.

8. The collimating backlight module according to claim 7, characterized in that the incident light microprism groove is a triangular groove.

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