TWI425261B - Light guide plate - Google Patents

Description

Light guide

The invention relates to a light guide plate, in particular to a light guide plate used in a backlight module of a display.

Liquid crystal display devices have been widely used in mobile phones, personal digital assistants, notebook computers, personal computers and televisions due to their low radiation, small size, short power consumption and low power consumption. Since the liquid crystal panel of the liquid crystal display device does not have the light-emitting property itself, in order to achieve the display effect, it is necessary to provide a backlight module to the liquid crystal panel to provide planar light with sufficient brightness and uniform distribution to the liquid crystal panel, thereby realizing display of the liquid crystal display device. Features.

The backlight module mainly comprises a light guide plate, a light source, a reflective sheet and a plurality of optical films. The light source is usually a point source or a line source, and a point source such as a light-emitting diode (LED) is increasingly used in a backlight module for providing light due to its energy saving and environmental protection advantages. The light guide plate is used to guide the direction of the light and achieve uniform brightness, thereby providing uniform distribution of planar light to the liquid crystal panel.

In order to be suitable for medium and large size liquid crystal panels, a plurality of point light sources may be arranged in a line-shaped light bar to replace a conventional line source such as a cold cathode lamp (CCFL). However, when the light provided by the point light source is incident on the light incident surface of the light guide plate, a phenomenon of alternating bright and dark, that is, a hot spot (Hotspot), which causes uneven light emission of the light guide plate, is apt to occur. In particular, when the Light bar circuit board has several light source dead lights due to the wiring relationship, the hot spot phenomenon is more serious, and the light output brightness of the light guide plate is also more uneven. Generally, a microstructure is disposed on the light-incident surface of the light guide plate to solve the problem of the hot spot, but the light beam is easily generated by the microstructure, and the light beam, the halo, and the dark band are easily generated.

In view of this, it is necessary to provide a light guide plate with uniform light emission.

A light guide plate includes two opposite light incident surfaces, a bottom surface connected to the two light incident surfaces, and a light emitting surface connected to the two light incident surfaces and opposite to the bottom surface, the bottom surface including a plurality of dots. The dot at the main portion of the bottom surface gradually becomes smaller in density from the two sides of the light incident surface to the center position, and the diameter gradually becomes larger.

Compared with the prior art, because the dot of the bottom surface of the light guide plate of the present invention has a large density and a small diameter on both sides of the bottom surface adjacent to the light incident surface, the density is small and the diameter is large at the middle position of the bottom surface, and the light is diffused through the mesh point. After that, a more detailed dispersion can be obtained, which not only can improve the unevenness of brightness and darkness caused by hot spots and dead lights, but also the light guide plate is not easy to generate light beams, halos and dark bands on the light-emitting surface, and the light is more Evenly.

Please refer to FIG. 1 , which is a perspective structural view of a first embodiment of a light guide plate according to the present invention. The light guide plate 10 includes two opposite light incident surfaces 11 , a bottom surface 12 connected to the light incident surface 11 , and a light exit surface 13 connected to the second light incident surface 11 and opposite to the bottom surface. The dichroic surface 11 includes a plurality of trough-shaped microstructures 110 extending perpendicularly to the bottom surface 12 and the light-emitting surface 13 . The trough-shaped microstructure is a continuously distributed V-groove.

Please refer to FIG. 2 , which is a schematic plan view of the bottom surface 12 of the light guide plate 10 . Wherein, the apex angle of each of the trough-shaped microstructures 110 is θ=60±5°, and the depth D=40±15 μm. The pitch of the adjacent two-groove microstructures 110 is P = 60 ± 10 μm. The cross section of each of the trough-shaped microstructures 110 parallel to the bottom surface is a V-shape. In this embodiment, the plurality of slot-shaped microstructures 110 of each of the light-incident surfaces 11 have the same opening direction of the V-shape, and the plurality of slot-shaped microstructures 110 of each of the light-incident surfaces 11 are successively arranged one after another, optionally Cross between adjacent two trough-shaped microstructures 110 The cross section forms a triangle.

A plurality of dots 120 are disposed on the bottom surface 12. The bottom surface 12 includes two opposing first sides and two opposing second sides joined to the first side. The two light incident surfaces 11 are connected to the two first side edges. An A-axis and a B-axis are defined on the bottom surface 12, the A-axis is parallel to the extending direction of the first side, the B-axis is parallel to the extending direction of the second side, and the A-axis intersects the B-axis At the center of the bottom surface 12. In the A-axis direction, with the B-axis as the axis of symmetry, the bottom surface 12 is divided into two major portions of symmetry, each of which is further divided into two small portions, and a small portion close to the second side is smaller than the center of the bottom surface 12 Another small part. For example, each of the plurality of portions may be divided into two small portions from about 2/7 of the center of the second side to the center of the bottom surface 12, respectively, or divided at other suitable positions according to actual needs. Two small portions near the center of the bottom surface 12 form a body region of the bottom surface 12, and two small portions near the second side edges form an edge region of the bottom surface 12.

In the main body portion of the bottom surface 12, the density of the dots 120 (i.e., the number of Internet access points per unit area) gradually decreases from the two first sides to the A-axis, that is, the dots 120 are close to the light at the bottom surface 12. The two sides of face 11 are encrypted. At the same time, the dots 120 are also encrypted at the four corners of the bottom surface 12.

In the B-axis direction, the diameter of the mesh point 120 of the main portion of the bottom surface 12 gradually changes from a minimum to a maximum from the first side to the A-axis of the bottom surface 12, wherein the minimum diameter of the mesh 120 is 0.15 mm. The largest diameter is 0.25mm. In the B-axis direction, the diameter of the mesh point 120 at the edge portion of the bottom surface 12 is gradually changed from the first side to the A-axis to the minimum, and then the mesh is located at the first side. The diameter of 120 is greater than the smallest diameter and less than the largest diameter. Further, in the direction from the four vertices of the bottom surface 12 to the center of the bottom surface 12, the diameter of the halftone dot 120 is from the top of the bottom surface 12 The point-to-center is also gradually changed to the minimum and then to the maximum, wherein the diameter of the dot 120 at the four vertices is larger than the minimum diameter and smaller than the maximum diameter. Please refer to FIG. 3 , which is a perspective view showing the relationship between the diameter of the dot 120 and the positional relationship of the dot 120 on the bottom surface 12 . Wherein, the x' axis represents the first side of the bottom surface 12, the y' axis represents the second side of the bottom surface 12, and the z axis represents the diameter of the mesh point 120.

Please refer to FIG. 4 together. FIG. 4 is a schematic diagram showing the relationship between the diameter of the mesh point 120 distributed at the main body portion of the bottom surface 12 and the location of the mesh point 120. Here, the horizontal axis x represents the distance from the halftone point 120 to the center in the B-axis direction, and the vertical axis y represents the diameter of the halftone dot 120. The diameter of the dot 120 satisfies the following equation: y=y0+A*exp(-c*((x-xc)/w)^2)

Where y0 represents the minimum diameter of the dot 120, xc represents the center point abscissa value, w is half of the width h of the light guide plate 10 or w=(0.32±3%)h, and A and c are constant. Among them, in the present embodiment, the preferred ranges of the constants A and c are as follows: 0 < A < 100, 0 < c < 100, and both A and c are natural numbers. The width h of the light guide plate 10 is the second side length of the bottom surface 12.

Please refer to FIG. 5 again. FIG. 5 is a schematic diagram showing the relationship between the diameter of the dot 120 distributed at four corners of the bottom surface 12 and the location of the dot 120. The curve in the elliptical dotted line indicates the relationship between the diameter of the dot 120 distributed at the corner of the bottom surface 12 and the position of the dot 120. The diameter of the dot 120 distributed at the corner of the bottom surface 12 satisfies the following equation: y=B*exp( -c1*((x-xd)/w)^2)

Xd represents the center point abscissa value. In the present embodiment, the preferred ranges of the constants B and c1 are as follows: 0 < B < 100, 0 < c1 < 100, and B and c1 are both natural numbers.

When light enters from the light incident surface 11 of the light guide plate 10, compared with the prior art In the case of the light guide plate 10, the light is split through the groove-shaped microstructures 110 on the light incident surface 11. When the light enters the inside of the light guide plate 10, the dot 120 has a large density and a small diameter on the bottom surface 12 adjacent to the light incident surface 11, and the density is small and the diameter is large at the middle position of the bottom surface 12. After the diffusion through the dot, a more fine dispersion is obtained, which not only can improve the uneven brightness caused by hot spots and dead lights, but also the light guide plate is not easy to generate light beams, halos and dark bands on the light-emitting surface. , the light is more even. In addition, since the dot 120 is encrypted at the corner of the bottom surface 12 and its diameter is slightly larger than the diameter of the dot 120 at the main portion at the first side, the problem of weak light at the corner can be improved, and the guide is further improved. The light uniformity of the light plate 10.

Please refer to FIG. 6 , which is a schematic plan view showing the bottom surface of the second embodiment of the light guide plate of the present invention. The light guide plate 20 is similar to the light guide plate 10 of the first embodiment in that the plurality of groove-shaped microstructures 210 of the light guide plate 20 are spaced apart such that a cross section between adjacent two groove-shaped microstructures 210 forms a cross section. Isosceles trapezoid.

Please refer to FIG. 7 , which is a schematic plan view of the bottom surface of the third embodiment of the light guide plate of the present invention. The light guide plate 30 is similar to the light guide plate 10 of the first embodiment, except that a portion of the plurality of slot-shaped microstructures 310 of the light guide plate 30 are continuously distributed and spaced apart, wherein each of the two adjacent groove-shaped microstructures 310 The cross section forms a W-shape with a plurality of W-shaped spacers formed by the cross-section of the plurality of channel-shaped microstructures 310.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10, 20, 30‧‧‧ light guide

11‧‧‧Into the glossy surface

12‧‧‧ bottom

13‧‧‧Glossy

110, 210, 310‧‧‧ trough microstructure

120‧‧‧ outlets

1 is a schematic perspective view showing a first embodiment of a light guide plate of the present invention.

2 is a schematic plan view showing the bottom surface of the light guide plate of FIG. 1.

3 is a perspective view showing the relationship between the diameter of the halftone dot on the bottom surface of the light guide plate of FIG. 1 and the positional relationship of the halftone dot on the bottom surface.

Fig. 4 is a schematic view showing the relationship between the diameter of the dot distributed at the intermediate portion of the bottom surface and the position of the dot.

Fig. 5 is a schematic view showing the relationship between the diameter of the dot distributed at the two side portions of the bottom surface and the position of the dot.

Fig. 6 is a plan view showing the structure of the bottom surface of the second embodiment of the light guide plate of the present invention.

Fig. 7 is a plan view showing the structure of the bottom surface of the third embodiment of the light guide plate of the present invention.

11‧‧‧Into the glossy surface

12‧‧‧ bottom

110‧‧‧ trough microstructure

120‧‧‧ outlets

Claims (11)

A light guide plate includes two opposite light incident surfaces, a bottom surface connected to the two light incident surfaces, and a light emitting surface connected to the second light incident surface and opposite to the bottom surface, the bottom surface including a plurality of dots, wherein a dot of the main body portion of the bottom surface gradually becomes smaller in density from a side to a center position of the diffractive surface, and a diameter gradually becomes larger; wherein the bottom surface includes two opposite first sides and two opposite and a second side connected to the first side, wherein the two first sides are two sides of the two light incident surfaces, and an A axis and a B axis are defined on the bottom surface, and the A axis is parallel to the first side a side, the B axis is parallel to the second side, the A axis intersects the B axis at the center of the bottom surface, and in the A-axis direction, the B-axis is an axis of symmetry, and the bottom surface is divided into two major parts of the symmetry Each of the majority is further divided into two small portions, and the small portion near the center of the bottom surface forms the main body portion. In the B-axis direction, the diameter of the mesh portion of the main body portion is respectively from the two first side edges to the A-axis. Gradually changing from minimum to maximum; wherein, near the second part of the second side Forming an edge portion of the bottom surface, in the direction of the B-axis, the diameter of the halftone dot at the edge portion is gradually changed from the first side to the A-axis to the minimum and then to the maximum, wherein the edge portion is The diameter of the half point at the first side edge is larger than the minimum diameter of the mesh point of the main body portion and smaller than the maximum diameter of the half point of the main body portion. The light guide plate of claim 1, wherein the diameter of the dot is gradually changed from a maximum of four vertices to a center of the bottom surface to a maximum, wherein a diameter of the halftone at the four vertices is larger than The minimum diameter of the mesh portion of the body portion is less than the maximum diameter of the mesh portion of the body portion. The light guide plate of claim 1, wherein the dot has a minimum diameter of 0.15 mm and a maximum diameter of 0.25 mm. The light guide plate of claim 1, wherein a small portion of each of the plurality of portions adjacent to the second side is smaller than another small portion near a center of the bottom surface. The light guide plate of claim 1, wherein the density of the dot is gradually reduced from a position where the main body portion is from the first side to the A axis, and the density of the dot is at four corners of the bottom surface. Increased. The light guide plate of claim 1, wherein the diameter of the halftone located near the main body portion satisfies the following equation: y=y0+A*exp(-c*((x-xc)/w)^2 Where y represents the diameter of the dot, x represents the distance from the Internet point to the center in the B-axis direction, y0 represents the minimum diameter of the dot, xc represents the abscissa of the center point, w is half of the width h of the light guide or w = (0.32 ± 3%) h, A and c are constants, and the ranges of constants A and c are: 0 < A < 100, 0 < c < 100, and both A and c are natural numbers. The light guide plate of claim 1, wherein the diameter of the halftone dot at the corner of the bottom surface satisfies the following equation: y=B*exp(-c1*((x-xd)/w)^2) Where y represents the diameter of the dot, x represents the distance from the Internet point to the center in the B-axis direction, xd represents the abscissa value of the center point, B and c1 are constant, and the preferred ranges of the constants B and c1 are as follows: 0<B<100 , 0 < c1 < 100, B and c1 are both natural numbers. The light guide plate of claim 1, wherein the light incident surface comprises a plurality of groove-shaped microstructures, wherein the groove-shaped microstructures extend perpendicularly to the bottom surface and the light-emitting surface, and the groove-shaped microstructure is V-shaped groove, the apex angle of each groove-shaped microstructure is θ=60±5°, the depth D=40±15 μm, and the pitch of adjacent two-groove microstructures is P=60±10 μm. The light guide plate of claim 8, wherein the groove-shaped microstructure is continuously distributed, and a cross section between adjacent two groove-shaped microstructures forms a triangle. The light guide plate of claim 8, wherein the groove-shaped microstructures are spaced apart, and a cross section between adjacent two groove-shaped microstructures forms an isosceles trapezoid. The light guide plate of claim 8, wherein the groove-shaped microstructure portion is continuously distributed in a portion, wherein a cross section of each two adjacent groove-shaped microstructures forms a W shape, and the plurality of grooves are formed. The complex cross-section of the microstructure forms a complex W-shaped spacing distribution.