CN103899994A - High-directivity backlight module - Google Patents

Abstract

The invention discloses a high-directivity backlight module. The high-directivity backlight module comprises a high-collimation light source and a light guide board, wherein the light guide board is a hexahedron composed of a first side surface, a second side surface, a third side surface, a fourth side surface, a bottom surface and a top surface, the second side surface, the third side surface and the bottom surface are respectively of a micro-structure, light which is emitted by the high-collimation light source and penetrates through the first side surface can be totally reflected through the microstructures and reflected out through the top surface finally, and a light source is provided for display equipment. According to the high-directivity backlight module, the half-height and full-width number of an emergent light field can be greatly reduced, emergent light has the high-collimation characteristic, the optical use ratio can be effectively increased, and therefore energy consumption of the display equipment is reduced.

Description

High Directivity Backlight Module

technical field

The invention relates to a backlight module, in particular to a high-directivity backlight module capable of improving optical utilization and reducing power consumption.

Background technique

Liquid crystal displays have been widely used, including mobile phones, tablet computers, car monitors, TVs, etc. However, the TFT-LCD display is a non-self-illuminating display and requires an external backlight module to provide a planar light source. The traditional side-firing backlight module uses a light guide plate to form a plane light source. In addition to the LED light source, light guide plate, reflector, and diffuser, there are at least two light-collecting prisms perpendicular to each other as the main components, which function to limit the light output angle. Make most of the light exit at +/-22-25° from the frontal viewing angle, and return the rest of the light for reuse to achieve the effect of light collection and brightening. The light utilization rate of traditional liquid crystal displays is only 6%-10%. For notebook computers, the power consumption of liquid crystal displays is 40%-50% of the total. If the optical utilization rate and power consumption can be improved, the battery life can be greatly extended time.

Therefore, it is necessary to provide a backlight module capable of improving optical utilization and reducing power consumption, so as to solve the problems existing in the prior art.

Contents of the invention

The main purpose of the present invention is to provide a backlight module for realizing a display device with high optical efficiency, low power consumption and low cost.

To achieve the above object, the present invention provides a highly directional backlight module, including a highly collimated light source and a light guide plate, the light guide plate is a first side, a second side, a third side, a fourth side, A hexahedron composed of a bottom surface and a top surface; wherein, the second side is opposite to the fourth side, the third side is opposite to the first side, and the top and bottom are parallel to each other; the height The collimated light source is placed close to the light incident surface;

The second side is provided with a first microstructure, and the first microstructure enables light emitted from the highly collimated light source and passing through the first side to be reflected to the third side; the third The side is provided with a second microstructure, and the second microstructure enables the light incident on the third side to be reflected to the bottom surface; the bottom surface is provided with a third microstructure, and the third microstructure enables the incident light to Light from the bottom surface can be reflected to the top surface.

Further, the highly collimated light source is light emitting diode, organic light emitting diode, laser, spontaneously formed or modulated light source with high directivity.

Further, the included angle between the second side and the fourth side is a first angle, and the first angle is larger than 0°.

Further, the third side is set so that the included angle with the vertical plane is a second angle, and the second angle is greater than 0°.

Further, the first microstructure is an array composed of a plurality of wedges, and the projection of each wedge on the bottom surface is a triangle.

Further, the second microstructure is an array composed of a plurality of wedges, and the projection of each wedge on the bottom surface is a triangle.

Further, the upper surface of the wedge is parallelogram, rectangle, square or trapezoid.

Further, the third microstructure is an array composed of a plurality of triangular prisms, and the projection of each triangular prism on the second side or the fourth side is a triangle.

Further, the surfaces of the first microstructure, the second microstructure and the third microstructure are all coated with a total reflection material.

A high-directivity backlight module of the present invention can greatly reduce the full width at half maximum (FWHM) of the outgoing light field, and the outgoing light has high collimation characteristics, which can effectively improve optical utilization and reduce display The energy consumption of the equipment.

Description of drawings

Figure 1 is an isometric view of a preferred embodiment of the present invention;

Fig. 2 is a top view of a preferred embodiment of the present invention;

Fig. 3 is a partial sectional view of a preferred embodiment of the present invention along the section 1-1 in Fig. 1;

Fig. 4 is a schematic diagram of the light propagation path in the embodiment shown in Fig. 2;

Fig. 5 is a schematic diagram of the light propagation path in the embodiment shown in Fig. 3;

FIG. 6 is the FWHM of the light field of the high directivity backlight module of a preferred embodiment of the present invention and the traditional backlight module.

Detailed ways

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the scope of protection of the present invention is not limited to the following Example.

In a preferred embodiment of the present invention, as shown in FIGS. 1-3 , a highly directional backlight module includes a highly collimated light source 10 and a light guide plate. Wherein the highly collimated light source is a light emitting diode, in other alternative embodiments, it may also be an organic light emitting diode, a laser, a spontaneously formed or modulated light source with high directivity. The light guide plate is a hexahedron consisting of a first side 31, a second side 32, a third side 33, a fourth side 34, a bottom 21 and a top 20; wherein the second side 32 is opposite to the fourth side 34, and the third The side surface 33 is opposite to the first side surface 31, the top surface 20 and the bottom surface 21 are opposite and parallel to each other, and the second side surface 32 and the fourth side surface 34 form an included angle, denoted as the first angle α ₁ , the third side surface 33 and the vertical surface form an included angle, which is denoted as the second angle α ₂ , where both α ₁ and α ₂ are greater than 0°; the highly collimated light source 10 is placed close to the first side 31 .

The second side 32 is provided with a first microstructure, and the first microstructure is an array composed of a plurality of wedges 40. The projection of each wedge 40 on the bottom surface 21 is a triangle, and the upper surface and the lower surface of each wedge 40 The included angle of is denoted as β ₁ , and the upper surface of the wedge body 40 can be parallelogram, rectangle, square or trapezoid.

The third side 33 is provided with a second microstructure, the second microstructure is an array of a plurality of wedges 41, the projection of each wedge 41 on the bottom surface 21 is a triangle, the upper surface and the lower surface of each wedge 41 The included angle is denoted as β ₂ , and the upper surface of the wedge 41 can be parallelogram, rectangle, square or trapezoid.

The bottom surface 21 is provided with a third microstructure, the third microstructure is an array composed of a plurality of triangular prisms 42, the projection of each triangular prism 42 on the second side 32 or the fourth side 34 is a triangle, one of the triangular prisms 42 The angle between the side surface 82 and its bottom surface is denoted as β ₄ .

In a preferred embodiment of the present invention, the surfaces of the first microstructure, the second microstructure and the third microstructure are all coated with a total reflection material.

Fig. 4 is the light propagation path shown in the top view of the high directivity backlight module of the preferred embodiment of the present invention, as shown in Fig. The upper surface of the wedge 40 in one microstructure undergoes total reflection and becomes light 200 ; On the upper surface of the wedge 40, the angle between the light 100 and the normal 51 is marked as θ ₁ , and the angle between the light 200 and the normal 51 is marked as θ ₂ ; on the upper surface of the wedge 41, the angle between the light 200 and the normal 52 The angle between ray 300 and normal 52 is denoted as θ ₃ , the angle between ray 300 and normal 52 is denoted as θ ₄ , the angle between ray 200 and the lower surface of wedge 41 is denoted as δ, and the angle between ray 200 and ray 100 is denoted as γ . Each included angle satisfies the following formula:

α ₁ =tan ^-1 (H _cls /L)

γ=tan ^-1 (W/L)

δ=tan ^-1 (L/W)

θ ₁ =θ ₂ =(180-γ)/2

θ ₃ =θ ₄ =(90-δ)/2

β ₁ =90-α ₁ -θ ₁

β ₂ =90-δ–θ ₃

In the formula, L is the length of the second side 32 , W is the length of the third side 33 , and H _cls is the width of the highly collimated light source 10 .

；在三棱柱42的表面，光线300与法线54的夹角记为ω₃，光线300与水平方向夹角记为ψ，光线400与法线54的夹角记为ω₄。各夹角满足下列公式：Fig. 5 is the light propagation path shown in the cross-sectional view of the high directivity backlight module of the preferred embodiment of the present invention along the 1-1 section in Fig. 1, as shown in Fig. 5, the light 200 is incident into the second microstructure The upper surface of the wedge-shaped body 41 is totally reflected and becomes light 300, and the light 300 is incident on the surface of the triangular prism 42 and is totally reflected to become 400; finally, as shown in FIG. 3 , the light 400 emerges from the top surface 20, as The display device provides a light source. On the upper surface of the wedge 41, the angle between the light 200 and the normal 53 is denoted as ω ₁ , the angle between the ray 300 and the normal 53 is denoted as ω ₂ , and the angle between the ray 300 and the vertical direction is denoted as

; On the surface of the triangular prism 42, the angle between the light 300 and the normal 54 is marked as ω ₃ , the angle between the light 300 and the horizontal direction is marked as ψ, and the angle between the light 400 and the normal 54 is marked as ω ₄ . Each included angle satisfies the following formula:

ψ=tan ^-1 (H/L)

ω ₃ =ω ₄ =(90-ψ)/2

β ₄ =90-ψ-ω ₃

In the formula, L is the length of the second side 32 , and H is the height of the light guide plate, that is, the distance between the bottom surface 21 and the top surface 20 .

Using the optical simulation software Lighttools to simulate the light intensity distribution on the exit surface of the high-directivity backlight module of the preferred embodiment of the present invention, it was found that the light intensity in five different areas (four corners and the center) on the exit surface of the light guide plate is uniform The degrees are 96%, 100%, 92%, 95% and 91%, respectively, showing the uniformity of the exit light height.

Fig. 6 compares the FWHM of the light-emitting light field of the high-directivity backlight module of the preferred embodiment of the present invention and the traditional backlight module, as shown in Figure 6, the FWHM of the light-emitting light field of the traditional backlight module is ± 60 °, and The FWHM of the output light field of the high-directivity backlight module of the preferred embodiment of the present invention is only ±5°, which greatly reduces the FWHM of the light output field, shows the high collimation of the output light, and greatly improves the optical utilization rate , thereby reducing the power consumption of the display device.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (9)

1. A high-directivity backlight module, comprising a highly collimated light source and a light guide plate, characterized in that the light guide plate is a structure consisting of a first side, a second side, a third side, a fourth side, a bottom and a top A hexahedron composed of faces; wherein, the second side is opposite to the fourth side, the third side is opposite to the first side, and the top surface and the bottom surface are parallel to each other; the highly collimated light source placed against said first side; The second side is provided with a first microstructure, and the first microstructure enables light emitted from the highly collimated light source and passing through the first side to be reflected to the third side; the third The side is provided with a second microstructure, and the second microstructure enables the light incident on the third side to be reflected to the bottom surface; the bottom surface is provided with a third microstructure, and the third microstructure enables the incident light to Light from the bottom surface can be reflected to the top surface. 2. The high directivity backlight module according to claim 1, wherein the highly collimated light source is a light emitting diode, an organic light emitting diode, a laser, a spontaneously formed or modulated light source with high directivity. 3. The high-directivity backlight module according to claim 1, wherein the angle between the second side and the fourth side is a first angle, and the first angle is greater than 0°. 4. The high-directivity backlight module according to claim 1, wherein the angle between the third side surface and the vertical surface is set to be a second angle, and the second angle is larger than 0°. 5. The high-directivity backlight module according to claim 1, wherein the first microstructure is an array composed of a plurality of wedges, and the projection of each wedge on the bottom surface is a triangle. 6. The high-directivity backlight module according to claim 1, wherein the second microstructure is an array composed of a plurality of wedges, and the projection of each wedge on the bottom surface is a triangle. 7. The high-directivity backlight module according to claim 5 or 6, wherein the upper surface of the wedge is in the shape of a parallelogram, a rectangle, a square or a trapezoid. 8. The high directivity backlight module according to claim 1, wherein the third microstructure is an array composed of a plurality of triangular prisms, and each of the triangular prisms is on the second side or the fourth The projection on the side is triangular. 9. The high directivity backlight module according to claim 5, 6 or 8, wherein the surfaces of the first microstructure, the second microstructure and the third microstructure are all coated with reflective material.

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