TWI424208B - Light guide plate and backlight module - Google Patents

Description

Light guide plate and backlight module

The present invention relates to an optical component and a light source, and more particularly to a light guide plate and a backlight module.

1 is a schematic cross-sectional view of a conventional light guide plate. Referring to FIG. 1 , the conventional light guide plate 10 has a plurality of optical microstructures 14 disposed on the bottom surface 12 of the light guide plate 10 . Each optical microstructure 14 includes a first surface 14a that is angled θ1 from the bottom surface 12 and a second surface 14b that is coupled to the first surface 14a and perpendicular to the bottom surface 12. In the prior art, the light beam 1 can be emitted from the light exit surface 16 of the light guide plate 10 at a specific exit angle θ2 by controlling the angle θ1 between the first surface 14a of the optical microstructure 14 and the bottom surface 12. However, not all of the light beams 1 in the direction of transmission can be reflected through the first surface 14a, and light is emitted from the light exit surface 16 of the light guide plate 10 at a specific emission angle θ2. In general, about 30% of the light beam 1 is reflected by the first surface 14a, and then emitted from the light exit surface 16 of the light guide plate 10 at a specific emission angle θ2. Therefore, the conventional light guide plate 10 has low light utilization efficiency, and it is still necessary to use an additional optical film to adjust the transmission direction of the light beam 1 emitted from the light exit surface 16 to a specific direction.

A light guide plate is disclosed in the Republic of China Patent No. I321250. The second optical surface of the light guide plate is provided with a second microstructure having a light guiding portion composed of a sloped surface and a curved surface. The Republic of China Patent No. M264504 discloses a light guide plate having a water droplet type microstructure on the bottom surface thereof. An optical waveguide is disclosed in the Republic of China Patent Publication No. 200506426. The back surface of the optical waveguide remote from the light exit surface is provided with a plurality of serrated grooves. The light guide plate of the edge-lit backlight module is disclosed in the Republic of China Patent Publication No. 200839328. The bottom surface of the light guide plate is provided with a V-Cut structure. The Republic of China Patent No. I239419 discloses a light guide plate in which light transmitted through the light guide plate is incident on the inclined surface of the upper surface, and is completely reflected by the lower surface of the light guide plate by the internal total reflection condition, and is corrected by the slope of the upper surface. After that, the light incident on the lower surface no longer satisfies the internal total reflection condition and refracts the light guide plate, and the light re-enters the light guide plate through the reflection of the reflection sheet, and emits light from the upper surface. The Chinese Patent No. I282021 discloses a light guide plate in which incident light transmitted in the light guide plate is incident on a slope, and the incident angle satisfies a critical angle for forming an internal total reflection condition to form a reflected light, which is corrected by a slope, and the reflected light can be Form a positive exit with a small angle from the normal of the light exit surface. A light-emitting panel assembly comprising a light-emitting panel member, wherein a pattern of light-removing deformations of a shape defined on or within at least one of the panel surfaces is defined by the Republic of China Patent No. I246576 and US Pat. No. 6,712,481. And for generating a desired light output distribution by the panel member, at least some of the deformations having an inclined surface for reflecting or refracting light impinging on the inclined surface to leave the panel member at a desired angular distribution, and having a width in the deformation direction A laterally curved surface that reflects or refracts additional light impinging on the surface in different directions, spreading the light across the panel member to provide a more even distribution of the light emitted by the panel member.

The invention provides a light guide plate which can reduce light loss.

The invention provides a backlight module with high light utilization efficiency.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

In order to achieve one or a part or all of the above or other purposes, an embodiment of the present invention provides a light guide plate including a light emitting surface, a bottom surface opposite to the light emitting surface, and at least one light incident surface connecting the light emitting surface and the bottom surface, and A plurality of optical microstructures. The optical microstructure is disposed on the bottom surface. Each optical microstructure has a first surface and a second surface coupled to the first surface. The first surface is inclined toward a side facing the light incident surface, wherein the cut line obtained by cutting the first surface in a direction perpendicular to the light incident surface and the light exit surface includes a first cut line, the first cut line substantially It is part of the parabola. The second surface is inclined in a direction away from one side of the light incident surface, wherein the first surface is located between the light incident surface and the second surface.

Another embodiment of the present invention provides a backlight module including the light guide plate and at least one light emitting element. The light-emitting element is disposed beside the light-incident surface and is adapted to emit a light beam, wherein the light beam is adapted to enter the light guide plate via the light-incident surface, and is transmitted to the outside of the light guide plate via the light-emitting surface.

In summary, the light guide plate and the backlight module of the embodiment of the present invention have at least one of the following advantages: the light guide plate and the backlight module of the embodiment of the present invention can be used for the light-emitting element by the first surface of the optical microstructure. Most of the emitted light beam is reflected to the second surface of the optical microstructure, and the second surface of the optical microstructure is designed such that most of the light beam emitted by the light emitting element exits at an angle desired. In this way, the light utilization efficiency of the light guide plate and the backlight module of the embodiment of the present invention can be effectively improved and the operation mode is more flexible.

The above described features and advantages of the present invention will be more apparent from the following description.

First embodiment

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only directions referring to the additional drawings. Therefore, the directional terminology used is for the purpose of illustration and not limitation.

2A is a cross-sectional view of a backlight module according to an embodiment of the invention. Referring to FIG. 2A , the backlight module 1000 of the embodiment includes a light guide plate 100 and at least one light emitting element 200 . The light guide plate 100 of the embodiment includes a light-emitting surface 110 (for example, a plane parallel to the xy plane), a bottom surface 120 (for example, an xy plane) with respect to the light-emitting surface 110, and a light-incident surface 130 connecting the light-emitting surface 110 and the bottom surface 120 ( For example, a plane parallel to the xz plane) and a plurality of optical microstructures 140 disposed on the bottom surface 120. The light-emitting element 200 is disposed adjacent to the light-incident surface 130 and is adapted to emit a light beam 1 , wherein the light beam 1 enters the light guide plate 100 via the light-incident surface 130 and is transmitted from the light-emitting surface 110 to the outside of the light guide plate 100 . The backlight module 1000 of the present embodiment may further include a reflective sheet 300, and the bottom surface 120 is located between the reflective sheet 300 and the light emitting surface 110. The reflection sheet 300 can reflect the light beam leaking from the bottom surface 120 of the light guide plate 100 back into the light guide plate 100. The light-emitting element 200 of the present embodiment may be a light-emitting diode (LED) or a cold cathode ray tube (CCFL), but the invention is not limited thereto. In addition, the optical microstructure 140 of the present embodiment is a structure that protrudes from the bottom surface 120.

It is worth mentioning that the optical microstructure 140 of the light guide plate 100 has a first surface 142 and a second surface 144 connected to the first surface 142, wherein the first surface 142 can reflect most of the light beam l emitted by the light emitting element 200 To the second surface 144, the second surface 144 can reflect the light beam l to the light exit surface 110 and cause the light beam 1' to emit light from the light exit surface 110 at the desired exit angle. FIG. 2B is a partial enlarged view of the light guide plate 100 illustrated in FIG. 2A. The mechanism by which the first surface 142 of the optical microstructure 140 of the present embodiment can reflect most of the light beam l emitted by the light-emitting element 200 to the second surface 144 will be described below with reference to FIGS. 2A and 2B. Moreover, the second surface 144 can be used to reflect the light beam 1 to the light exiting surface 110 and to cause the light beam l' to emit light from the light exiting surface 110 at the desired light exiting angle.

First, a mechanism in which the first surface 142 can reflect most of the light beam 1 emitted by the light-emitting element 200 to the second surface 144 will be described. Referring to FIG. 2A , in the embodiment, the first surface 142 of the optical microstructure 140 is inclined toward the side 132 facing the light incident surface 130 , wherein the light incident surface 130 and the light exit surface 110 are perpendicular to the light incident surface 130 and the light exit surface 110 . The cut line obtained by cutting the first surface 142 in the direction includes a cut line K1 which is substantially a part of the parabola 150. With the beam 1 passing through the focus 152 of the parabola 150, the characteristic of the beam 150 passing parallel to the axis of symmetry 154 of the parabola 150 is transmitted toward the opening 150a of the parabola 150. The first surface 142 can carry most of the beam 1 (including the focus 152 that does not pass through the parabola 150). The direction of travel of the beam 1) is corrected to be close to the direction of the axis of symmetry 154 of the parallel parabola 150, such that most of the beam 1 is reflected by the first surface 142 and incident on the second surface in a direction close to the axis of symmetry 154 of the parallel parabola 150. 144. In one embodiment, the direction of the symmetry axis 154 of the parabola 150 is parallel to the bottom surface 120. Therefore, most of the beam 1 can be reflected through the first surface 142 and incident on the second surface 144 in a direction close to the parallel bottom surface 120.

Referring to FIG. 2B, further, the parabola 150 and the bottom surface 120 intersect the first end point P1, and the parabola 150 and the second surface 144 of the optical microstructure intersect the second end point P2, the first end point P1 and the parabola 150. The focus 152 is connected to the first reference line R1, and the second end point P2 is connected to the focus 152 of the parabola 150 to form a second reference line R2. The angle between the first reference line R1 and the axis of symmetry 154 is θ _MAX , and the angle between the second reference line R2 and the axis of symmetry 154 is θ _MIN . In the present embodiment, the values of the included angle θ _MAX and the included angle θ _MIN can be appropriately designed, and the efficiency at which the first surface 142 reflects the light beam 1 to the second surface 144 is good.

For example, in the embodiment, the angle θ _MAX and the angle θ _MIN can satisfy the following formula (1):

θ in the above formula satisfies: 0 < θ < θ _MAX - φ

Where n is the refractive index of the light guide plate 100, and φ is the angle between the reference plane 122 parallel to the bottom surface 120 and the axis of symmetry 154 of the parabola 150 (shown in FIG. 2A). When the angle θ _MAX and the angle θ _MIN satisfy the above formula (1), the efficiency of the first surface 142 reflecting the light beam 1 to the second surface 144 is better, and the light of the backlight module 1000 and the light guide plate 100 of the embodiment is utilized. Good efficiency.

Referring to FIG. 2B, in the embodiment, the distance between the first end point P1 and the second end point P2 in the direction parallel to the bottom surface 120 is L, and the first end point P1 and the second end point P2 are perpendicular. The distance in the direction of the bottom surface 120 is D. In this embodiment, the distance L between the first end point P1 and the second end point P2 in a direction parallel to the bottom surface 120 may be between 0 mm and 2 mm, and the first end point P1 and the second end point The distance D of P2 in a direction perpendicular to the bottom surface 120 may be between 0 micrometers and 500 micrometers. However, the present invention is not limited thereto, and the distance L and the distance D can be appropriately designed according to actual needs. When the distance L or the distance D, or the distance L and the distance D are selected, the structure of the parabola 150 is also determined.

Specifically, if the parabola 150 of the present embodiment is located in the yz plane, the parabola 150 can be expressed by the following formula (2).

y(z)=z ² /(4c) ---(2)

Where c is the distance between the apex 156 of the parabola 150 and the focus 152. Equation (2) is represented by a polar coordinate, that is, y=r‧cosθ and z=r‧sinθ are taken into equation (2), and equation (2) can be written as the following equation (3):

At this time, the distance between the first end point P1 and the second end point P2 in the direction perpendicular to the bottom surface 120 is D, and the distance L between the first end point P1 and the second end point P2 in the direction parallel to the bottom surface 120 may be The polar coordinates are expressed as follows (4) and (5):

r(θ _MIN )‧sin(θ _MIN )-r(θ _MAX )‧sin(θ _MAX )=D ---(4)

r(θ _MIN )‧cos(θ _MIN )-r(θ _MAX )‧cos(θ _MAX )=L ---(5)

Bringing the formula (3) into the formula (4) and the formula (5) can obtain the following formula (6) and the following formula (7):

4c‧(cotθ _MIN -cotθ _MAX )=D ---(6)

4c‧[(cotθ _MIN ) ² -(cotθ _MAX ) ² ]=L ---(7)

According to the above formula (6), the structure of the parabola 150 of the present embodiment (i.e., the distance c between the apex 156 of the parabola 150 and the focus 152) can be determined along with the determination of the distance D. For example, when the distance D=10 micrometers (um), n=1.49, θ _MAX =47.155°, θ _MIN =15°, c=0.891 micrometers (um) can be obtained according to the formula (6), and the distance is at this time. L = 46.595 micrometers (um). However, the present invention is not limited thereto, and according to the above formula (7), the structure of the parabola 150 (i.e., the distance c between the apex 156 of the parabola 150 and the focus 152) may also be determined in accordance with the determination of the distance L. For example, when the distance L=50 micrometers (um), n=1.49, θ _MAX =47.155°, θ _MIN =15°, c=0.957 micrometers (um) can be obtained according to the formula (7), and the distance is at this time. D = 10.731 microns (um). Alternatively, the structure of the parabola 150 (i.e., the distance c between the apex 156 of the parabola 150 and the focus 152) may also be determined as a function of the distance L and the distance D. That is, the distance c can satisfy the following formula (8) and the following formula (9)

For example, when the distance L 50 microns (eg distance L = 49.85 microns) when distance D 10 μm (for example, distance D=10.699 μm), n=1.49, θ _MAX =47.155°, θ _MIN =15°, c=0.954 μm (um) can be obtained according to the formulas (8) and (9).

Next, the second surface 144 of the embodiment can reflect the light beam l to the light exit surface 110 and cause the light beam 1 to emit light from the light exit surface 110 at the desired light exit angle.

With continued reference to FIG. 2A , the second surface 144 is inclined toward a direction opposite to one side 132 of the light incident surface 130 , wherein the first surface 142 is located between the light incident surface 130 and the second surface 144 . In this embodiment, the cut line obtained by cutting the second surface 144 along the direction perpendicular to the light incident surface 130 and the light exit surface 110 includes a cut line K2, and the cut line K2 is substantially a diagonal line inclined with respect to the bottom surface 120. In particular, the acute angle γ of the cut line K2 of the present embodiment and the normal line N of the light exit surface 110 satisfies the following formula (10):

Where Ψ is the angle between the desired outgoing beam 1′ and the normal N′ of the light exiting surface 110, φ is the angle between the reference plane 122 parallel to the bottom surface 120 and the axis of symmetry 154 of the parabola 150, and n is the refractive index of the light guide plate. rate. When the acute angle γ satisfies the above formula (10), the second surface 144 can reflect the light beam 1 reflected from the first surface 142 to the light exit surface 110 and extract the light at a specific angle. In other words, if the light beam 1 is to be extracted at a specific angle, the structure of the optical microstructure 140 can be reversed by using the above relationship, without using a complicated simulation method to calculate the structure of the optical microstructure 140, thereby reducing the backlight. The time required for module 1000 development.

For example, if the angle between the outgoing beam 1' and the normal N' of the light exiting surface 110 is 30=30° and n=1.49, φ=0°, the cut line K2 and the normal line N of the light exiting surface 110 are sandwiched. The acute angle γ can be designed to be between 39.8° and 69.8°. If the angle between the outgoing beam 1' and the normal N' of the light-emitting surface 110 is Ψ=0° and n=1.49, φ=0°, the acute angle γ between the cut line K2 and the normal N of the light-emitting surface 110 can be Designed to be between 30° and 60°.

However, the present invention is not limited to the above, as shown in FIG. 3A, in another embodiment, the cut line K2 obtained by cutting the second surface 144 in a direction perpendicular to the light incident surface 130 and the light exit surface 110 may substantially It is a curve that is convex away from the bottom surface 120 and the light incident surface 130. More specifically, this curve can be taken from an arc in a circle having a radius R greater than 100 microns (um). The second surface 144 shown in Fig. 3A allows the distribution angle Ψ of the outgoing beam 1' to be narrower. As shown in FIG. 3B, in another embodiment, the cut line K2 obtained by cutting the second surface 144 in a direction perpendicular to the light incident surface 130 and the light exit surface 110 may be substantially away from the bottom surface 120 and the light entering the light. The curve of the face 130 is concave. More specifically, the curve can be taken from an arc in a circle having a radius R greater than 100 microns (um). The second surface 144 shown in Fig. 3B allows the distribution angle Ψ of the outgoing beam l' to be widely distributed.

4 is a perspective view of the optical microstructure of the present embodiment. Referring to FIG. 4 and FIG. 2A simultaneously, in the embodiment, the first surface 142 of the optical microstructure 140 is cut along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane). The line includes a cut line K3, and the cut line K3 is a straight line. The cut line obtained by cutting the second surface 144 of the optical microstructure 140 along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane) includes a cut line. Line K4, the cut line K4 is also a straight line, and the cut line K3 is substantially parallel to the cut line K4. Furthermore, the cut line K3 and the cut line K4 are parallel to the light incident surface 130. In other words, the optical microstructure 140 of the present embodiment may be an elongated strip extending in a direction substantially parallel to the light exit surface 110. However, the invention is not limited thereto.

FIG. 5 is a perspective view of an optical microstructure according to another embodiment of the present invention. Referring to Figure 5, the optical microstructure 140A of this embodiment is similar to the optical microstructure 140 of the first embodiment of the present invention. The difference between the two is that in this embodiment, the distance H from the boundary E1 of the first surface 142 of the optical microstructure 140A to the bottom surface 120 to the boundary E2 of the second surface 144 of the optical microstructure 140A and the bottom surface 120 is from the optical The center of the microstructure 140A is tapered toward both sides of the optical microstructure 140A. From another point of view, the cut line obtained by cutting the first surface 142 along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane) includes a cut line K5, and the cut line K5 may be an arc. And the arc of the cut line K5 faces away from the light entrance surface 130. The cut line obtained by cutting the second surface 144 along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane) includes a cut line K6, and the cut line K6 may be a straight line or an arc.

6 is a perspective view of an optical microstructure according to still another embodiment of the present invention. Referring to FIG. 6 and FIG. 2A simultaneously, the optical microstructure 140B of this embodiment is similar to the optical microstructure 140 of the first embodiment of the present invention. The difference between the two is that in this embodiment, the cut line obtained by cutting the first surface 142 of the optical microstructure 140B along a direction parallel to the light incident surface 130 and perpendicular to the light exit surface 110 (ie, the xz plane) is obtained. Including the cut line K9, the cut line K9 may be an arc, and the cut line obtained by cutting the second surface 144 along a direction parallel to the light incident surface 130 and perpendicular to the light exit surface 110 (ie, the xz plane) includes a cut line K10, a cut line. K10 may also be an arc, and the arc opening of the cutting line K9 and the arc opening of the cutting line K10 face the light emitting surface 110.

FIG. 7 is a perspective view of an optical microstructure according to still another embodiment of the present invention. Referring to Figure 7, the optical microstructure 140C of this embodiment is similar to the optical microstructure 140 of the first embodiment of the present invention. The difference between the two is that, in this embodiment, the cut line obtained by cutting the first surface 142 along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane) includes a cut line K11, The cut line K11 may be an arc, and the cut line obtained by cutting the second surface 144 along a direction perpendicular to the light incident surface 130 and parallel to the light exit surface 110 (ie, the xy plane) includes a cut line K12, and the cut line K12 may also be an arc. The radius of curvature of the cut line K11 is greater than the radius of curvature of the cut line K12, and the cut line K11 and the cut line K12 are centered.

The optical microstructures 140 of the present embodiment can be disposed on the bottom surface 120 in various manners. The manner in which the optical microstructures 140 are disposed on the bottom surface 120 can be changed according to actual needs. For example, as shown in FIG. 8A , in the embodiment, each of the optical microstructures 140 may be an elongated strip extending along a direction substantially parallel to the light exit surface 110 . However, the present invention is not limited to the above, as shown in FIG. 8B, in another embodiment, each of the optical microstructures 140 may be a bump, and the bumps may be distributed on the bottom surface 120 in various ways. As shown in FIG. 8C, in another embodiment, each of the optical microstructures 140 may be an arc-shaped ridge extending along a direction substantially parallel to the light-emitting surface 110, and the arc-shaped ridges of the arc-shaped ridges face the light-incident surface 130. . In other words, the arcuate ridges can be radially extended by the light incident surface 130.

The curve S100 in FIG. 9 shows the light intensity distribution of the backlight module (ie, the backlight module designed to be 0°) according to an embodiment of the present invention at various viewing angles. It can be seen from the curve S100 in FIG. 9 that the backlight module according to an embodiment of the present invention can directly generate a light field in which the light intensity is concentrated in the front view direction (ie, the viewing angle is 0°) without the external optical film. In other words, the backlight module of one embodiment of the present invention can be directly used as a good backlight without any additional optical film. In addition, the curve S200 in FIG. 9 shows the light intensity distribution of the backlight module (ie, the backlight module whose design is 30°) at each viewing angle according to another embodiment of the present invention. As can be seen from the curve S200 in FIG. 9, the backlight module according to another embodiment of the present invention can directly generate a light field in which the light intensity is concentrated in the direction of the viewing angle of 30°. In other words, the backlight module of another embodiment of the present invention (ie, the light guide plate designed to be 30°) can also be designed as a backlight module suitable for matching with an optical film (for example, brightness enhancement film, BEF). The backlight module can be used as a good backlight after being matched with an optical film.

First Two embodiments

FIG. 10 is a cross-sectional view of a backlight module according to a second embodiment of the present invention. Referring to FIG. 10, the backlight module 1000A of the present embodiment is similar to the backlight module 1000 of the first embodiment. The difference between the two is that the backlight module 1000A of the embodiment includes two light emitting elements 200, 200' and the control unit 400, and the optical microstructure 140D of the embodiment is different from the optical microstructure 140 of the first embodiment. . The following is a description of the differences between the two, and the similarities between the two will not be repeated.

The backlight module 1000A of the present embodiment includes a light guide plate 100 and two light emitting elements 200, 200'. The light guide plate 100 includes a light-emitting surface 110, a bottom surface 120 opposite to the light-emitting surface 110, a first light-incident surface 130 and a second light-incident surface 130' that are connected to the light-emitting surface 110 and the bottom surface 120, and are disposed on the bottom surface 120. An optical microstructure 140D. The light-emitting elements 200 and 200' of this embodiment are disposed beside the first light-incident surface 130 and the second light-incident surface 130', respectively.

The optical microstructure 140D of the present embodiment includes a first optical microstructure 140D' and a second optical microstructure 140D". The first surface 142 of the first optical microstructure 140D' faces the side facing the first light incident surface 130. The direction of the first optical microstructure 140D' is inclined toward the side facing away from the side of the first light incident surface 130. The first surface 142 of the second optical microstructure 140D" is facing toward the direction The direction of one side of the second light incident surface 130' is inclined, and the second surface 144 of the second optical microstructure 140D" is inclined toward a direction away from one side of the second light incident surface 130'.

11 is a perspective view of the first optical microstructure 140D' and the second optical microstructure 140D" of the present embodiment. Referring to FIG. 11 and FIG. 10 simultaneously, in the embodiment, each of the first optical microstructures 140D' The first surface 142 is joined to the first surface 142 of one of the second optical microstructures 140D" to form an annular surface 142A. The second surface 144 of each of the first optical microstructures 142A' is in contact with the second surface 144 of a second optical microstructure 142A" to form an annular surface 144A, and the annular surface 142A surrounds the second annular surface 144A. In other words, The optical microstructure 140D of the present embodiment may be a ring body that protrudes outward from the bottom surface 120. However, in another embodiment, the first optical microstructure 140D' and the second optical microstructure 140D" may also be separated from each other. Not connected. Similarly, the optical microstructures 140, 140A, 140B, and 140C of the other embodiments described above may also be divided into a plurality of first optical microstructures and a plurality of second optical microstructures separated from each other.

Referring to FIG. 10, the control unit 400 of the backlight module 1000A of the present embodiment is electrically connected to the two light-emitting elements 200, 200' to drive the two light-emitting elements 200, 200' to alternately blink. In other words, when the light-emitting element 200 emits the light beam L, the light-emitting element 200' does not emit the light beam L', and when the light-emitting element 200' emits the light beam L', the light-emitting element 200 does not emit the light beam L. The display panel 500 can be disposed above the backlight module 1000A of the embodiment to form a stereoscopic display. The display panel 500 can be a transmissive display panel or a transflective display panel. In detail, when the light emitting element 200 emits the light beam L, the display panel 500 displays a left eye picture, and the light beam L emitted by the light emitting element 200 is sequentially applied to the first surface 142 and the second surface 144 of the first optical microstructure 140D'. Reflect and pass to the top right of Figure 10. At this time, the light beam L is mounted on the left eye screen through the display panel 500, and the left eye image is transmitted to the left eye EL of the user. Similarly, when the light emitting element 200' emits the light beam L', the display panel 500 displays a right eye picture, and the light beam L' emitted by the light emitting element 200' is sequentially followed by the first surface 142 of the second optical microstructure 140D" The second surface 144 of the second optical microstructure 140D" is reflected and passed to the upper left of FIG. At this time, the light beam L' is mounted on the right eye screen through the display panel 500, and the right eye image is transmitted to the right eye ER of the user. The left eye picture and the right eye picture are alternately mounted by the light beam L and the light beam L', and a stereoscopic image can be formed in the user's brain.

However, the invention is not limited to the above paragraph. FIG. 12 is a cross-sectional view of a backlight module according to another embodiment of the present invention. Referring to FIG. 12, in this embodiment, the light beam L emitted by the light-emitting element 200 can be sequentially guided by the first optical microstructure 140D' by adjusting the tilt angle of the second surface 144 of the first optical microstructure 140D'. The first surface 142 is reflected from the second surface 144 of the first optical microstructure 140D' and passes to the upper left of FIG. At this time, the light beam L is mounted on the right eye screen through the display panel 500, and the right eye image is transmitted to the right eye ER of the user. Similarly, by adjusting the tilt angle of the second surface 144 of the second optical microstructure 140D", the light beam L' emitted by the light emitting element 200' can be sequentially applied to the first surface 142 of the second optical microstructure 140D" The second surface 144 of the second optical microstructure 140D" is reflected and transmitted to the upper right of FIG. 12. At this time, the light beam L is carried by the display panel 500 to carry the left eye image, and the left eye image is transmitted to the left eye of the user. EL: The left eye picture and the right eye picture are alternately mounted by the light beam L and the light beam L', and a stereoscopic image can be formed in the user's brain.

First Three embodiments

FIG. 13 is a cross-sectional view showing a backlight module according to a third embodiment of the present invention. Referring to FIG. 13, a backlight module 1000B according to a third embodiment of the present invention is similar to the backlight module 1000 of the first embodiment. Therefore, the same elements are denoted by the same reference numerals. The backlight module 1000B of the present embodiment is different from the backlight module 1000 of the first embodiment in that the optical microstructure 140E of the embodiment further has a connection surface 146. The following is a description of this difference, and the similarities between the two will not be repeated.

The optical microstructure 140E of the present embodiment further has a connection surface 146. The connecting surface 146 joins the first surface 142 and the second surface 144. In the present embodiment, the connecting surface 146 is, for example, at least one plane. However, the shape of the connecting surface 146 is not particularly limited in the present invention, and the developer can design various connecting faces 146 of different shapes according to actual needs. For example, in other embodiments, the connecting surface 146 can also be at least one curved surface, or a combination of at least one plane and at least one curved surface. The backlight module 1000B of the present embodiment has similar advantages and functions as the backlight module 1000 of the first embodiment, and will not be repeated here.

Fourth embodiment

FIG. 14 is a cross-sectional view showing a backlight module according to a fourth embodiment of the present invention. Referring to FIG. 14, a backlight module 1000C according to a fourth embodiment of the present invention is similar to the backlight module 1000 of the first embodiment. Therefore, the same elements are denoted by the same reference numerals. The backlight module 1000C of the present embodiment is different from the backlight module 1000 of the first embodiment in that the first section line K1' of the present embodiment is different from the first section line K1 of the first embodiment. The following is a description of this difference, and the similarities between the two will not be repeated.

The first cut line K1' of this embodiment is substantially a part of the parabola. For example, the first section line K1' of the present embodiment may be composed of a plurality of oblique lines 142a inclined with respect to the bottom surface 120 and connected to each other. However, the present invention is not limited thereto, and the first cut line K1' may also be composed of a plurality of curves connected to each other. Alternatively, as shown in FIG. 15, the first cut line K1" in the backlight module 1000D according to another embodiment of the present invention may be interconnected by a diagonal line 142a and a curved line 142b inclined with respect to the bottom surface 120. The backlight module 1000C has similar advantages and functions as the backlight module 1000 of the first embodiment, and will not be repeated here.

In summary, the embodiments of the present invention may have at least one of the following advantages or effects. The light guide plate and the backlight module of the embodiment of the present invention can reflect most of the light beam emitted by the light emitting element to the second surface of the optical microstructure by the first surface of the optical microstructure, and then the second of the optical microstructure The surface reflects the light beams to the light exit surface of the light guide plate to emit light. In this way, the light utilization efficiency of the light guide plate and the backlight module of the embodiment of the present invention can be effectively improved.

In addition, the light guide plate and the backlight module of the embodiment of the present invention can utilize the second surface of the optical microstructure to illuminate the light beam emitted by the light source at a specific angle, thereby enabling the light guide plate and the backlight module of the embodiment of the present invention. The group has a wider range of applications. For example, the light guide plate and the backlight module of the embodiment of the present invention can be combined with the alternately flashing light-emitting elements and the display panel to form a stereoscopic display.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention. In addition, the terms "first", "second" and the like mentioned in the specification or the scope of the claims are only used to name the elements or distinguish different embodiments or ranges, and are not intended to limit the number of elements. Upper or lower limit.

1000, 1000A, 1000B, 1000C, 1000D. . . Backlight module

10,100. . . Light guide

16, 110. . . Glossy surface

12, 120. . . Bottom

122. . . a reference plane parallel to the bottom surface

130, 130’. . . Glossy surface

132. . . One side of the light side

14, 140, 140A, 140B, 140C, 140D, 140D', 140D", 140E... optical microstructure

14a, 142. . . First surface of optical microstructure

14b, 144. . . Second surface of the optical microstructure

142A, 144A. . . Annular surface

142a. . . Slash

142b. . . curve

146. . . Connection surface

150. . . parabola

150a. . . Parabolic opening

152. . . Parabolic focus

154. . . Parabolic symmetry axis

156. . . Parabolic apex

200, 200’. . . Light-emitting element

300. . . A reflective sheet

400. . . control unit

500. . . Display panel

c, D, L, H. . . distance

E1, E2. . . Junction

ER, EL. . . eye

K1～K12, K1’, K1”...cut line

l, l', L, L'. . . beam

N, N’. . . Normal

P1, P2. . . End point

R. . . Circular radius

R1, R2. . . reference line

S100, S200. . . curve

x, y, z. . . direction

Ψ, θ _MAX , θ _MIN , θ1, θ2, φ, γ. . . angle

FIG. 1 is a schematic cross-sectional view of a conventional backlight module.

2A, 3A, 3B, 10, 12, 13, 14, and 15 are schematic cross-sectional views of a backlight module according to an embodiment of the present invention.

2B is a partial enlarged view of the light guide plate shown in FIG. 2A.

4, 5, 6, 7, and 11 are schematic perspective views of an optical microstructure according to an embodiment of the present invention.

8A, 8B, and 8C are schematic views of a light guide plate according to an embodiment of the present invention.

FIG. 9 shows the light intensity distribution of the backlight module of the two embodiments of the present invention at various viewing angles.

1000. . . Backlight module

100. . . Light guide

110. . . Glossy surface

120. . . Bottom

122. . . a reference plane parallel to the bottom surface

130. . . Glossy surface

132. . . One side of the light side

140. . . Optical microstructure

142. . . First surface of optical microstructure

144. . . Second surface of the optical microstructure

150. . . parabola

150a. . . Parabolic opening

152. . . Parabolic focus

154. . . Parabolic symmetry axis

200. . . Light-emitting element

K1, K2. . . Cut line

l, l’. . . beam

N, N’. . . Normal

Ψ, φ, γ. . . angle

Claims (37)

A light guide plate comprising: a light exit surface; a bottom surface opposite to the light exit surface; at least one light incident surface connecting the light exit surface and the bottom surface; and a plurality of optical microstructures disposed on the bottom surface, each of the optical micro The structure has a first surface inclined toward a side facing the light incident surface, wherein the cut line obtained by cutting the first surface in a direction perpendicular to the light incident surface and the light exit surface includes a first a first line, the first line being substantially a portion of a parabola; and a second surface coupled to the first surface and inclined toward a direction opposite the side of the light incident surface, wherein the first The surface is located between the light incident surface and the second surface. The light guide plate of claim 1, wherein the parabola has a focus and an axis of symmetry, the parabola intersecting the bottom surface with a first end point, the parabola intersecting the second surface of the optical microstructure And at a second end point, the first end point is coupled to the focus of the parabola to form a first reference line, and the second end point is coupled to the focus of the parabola to form a second reference line, the first reference line and the first reference line The angle of the symmetry axis is θ _MAX , the angle between the second reference line and the axis of symmetry is θ _MIN , and the angle θ _MAX and the angle θ _MIN satisfy the following formula: θ _MAX Sin ^-1 (1/n)+5°-φθ _MIN =θ+φ where θ satisfies: 0<θ<θ _MAX -φ, n is the refractive index of the light guide plate, and φ is the bottom surface and the parabola The angle of the axis of symmetry. The light guide plate of claim 1, wherein the parabola has a focus, a vertex, and an axis of symmetry, and the distance c from the vertex to the focus satisfies at least one of the following two formulas: 4c‧(cotθ _MIN - cot θ _MAX )=D4c‧[(cot θ _MIN ) ² -(cot θ _MAX ) ² ]=L, wherein the parabola intersects the bottom surface at a first end point, the parabola intersecting the second surface of the optical microstructure And at a second end point, the distance between the first end point and the second end point in a direction parallel to the bottom surface is L, and the first end point and the second end point are in a direction perpendicular to the bottom surface The distance between the first end point and the focus of the parabola is a first reference line, and the second end point is connected with the focus of the parabola into a second reference line, the first reference line and the axis of symmetry angle is θ _MAX, the second angle between the reference line and the axis of symmetry of the parabola is θ _MIN. The light guide plate of claim 3, wherein a distance L between the first end point and the second end point in a direction parallel to the bottom surface is between 0 mm and 2 mm, and the first The distance D between the end point and the second end point in a direction perpendicular to the bottom surface is between 0 micrometers and 500 micrometers. The light guide plate of claim 1, wherein the parabola has a focus, a vertex, and an axis of symmetry, and the distance c from the vertex to the focus satisfies the following two formulas: The parabola intersects the bottom surface with a first end point, the parabola intersecting the second end of the optical microstructure with a second end point, the first end point being parallel to the second end point The distance in the direction of the bottom surface is L, the distance between the first end point and the second end point in a direction perpendicular to the bottom surface is D, and the first end point is connected with the focus of the parabola into a first reference line. The second end point is connected to the focus of the parabola to form a second reference line. The angle between the first reference line and the axis of symmetry is θ _MAX , and the angle between the second reference line and the axis of symmetry is θ _MIN . The light guide plate of claim 5, wherein a distance L between the first end point and the second end point in a direction parallel to the bottom surface is between 0 mm and 2 mm, and the first The distance D between the end point and the second end point in a direction perpendicular to the bottom surface is between 0 micrometers and 500 micrometers. The light guide plate of claim 1, wherein the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and the light exit surface comprises a second cut line, and the second cut line The line is essentially an oblique line that is inclined relative to the bottom surface. The light guide plate of claim 7, wherein the oblique line and an ordinary line of the light-emitting surface are at an acute angle of γ, and satisfy the following formula: Where Ψ is the angle between an outgoing beam and the normal of the light exiting surface, φ is the angle between the bottom surface and the axis of symmetry of the parabola, and n is the refractive index of the light guide plate. The light guide plate of claim 1, wherein the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and the light exit surface comprises a second cut line, and the second cut line The line is substantially a curve that is convex or concave away from the bottom surface and the light incident surface. The light guide plate of claim 1, wherein each of the optical microstructures is a bump, extending along a direction substantially parallel to the light exiting surface, or substantially parallel to The direction of the light-emitting surface extends as an arc-shaped ridge. The light guide plate of claim 1, wherein the cut line obtained by cutting the first surface along a direction perpendicular to the light incident surface and parallel to the light exit surface comprises a second cut line, the second The cut line is a straight line, and the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and parallel to the light exit surface includes a third cut line, the third cut line is a straight line, and the second line The stub is substantially parallel to the third stub. The light guide plate of claim 1, wherein a distance between the first surface and the bottom surface to a boundary between the second surface and the bottom surface is from a center of the optical microstructure to both sides of the optical microstructure Decrement. The light guide plate of claim 1, wherein at least one of the light incident surfaces is opposite to the first light incident surface and the second light incident surface, and the optical microstructures comprise a plurality of first optical microstructures and a plurality of second optical microstructures, the first surface of each of the first optical microstructures being inclined toward a side facing the first light incident surface, the second surface of each of the first optical microstructures facing The direction of the side of the first light incident surface is inclined, and the first surface of each of the second optical microstructures is inclined toward a side facing the second light incident surface, each of the second optics The second surface of the microstructure is inclined in a direction away from the side of the second light incident surface. The light guide plate of claim 13, wherein the first surface of each of the first optical microstructures and the first surface of one of the second optical microstructures are joined to form a first annular surface The second surface of each of the first optical microstructures is in contact with the second surface of one of the second optical microstructures to form a second annular surface, and the first annular surface surrounds the second ring Surface. The light guide plate of claim 1, wherein the cut line obtained by cutting the first surface along a direction parallel to the light incident surface and perpendicular to the light exit surface comprises a second cut line, the second The section line is a first arc line, and the section line obtained by cutting the second surface along a direction parallel to the light incident surface and perpendicular to the light exiting surface comprises a third section line, and the third section line is a second line An arc, and the arc of the first arc and the second arc face the light exiting surface. The light guide plate of claim 1, wherein the cut line obtained by cutting the first surface along a direction perpendicular to the light incident surface and parallel to the light exit surface comprises a second cut line, the second The cut line is a first arc, and the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and parallel to the light exit surface includes a third cut line, and the third cut line is a second The arc has a radius of curvature greater than a radius of curvature of the second arc, and the first arc is concentric with the second arc. The light guide plate of claim 1, wherein each of the optical microstructures further has a connection surface connecting the first surface and the second surface. The light guide plate of claim 17, wherein the connecting surface comprises at least one plane, at least one curved surface or a combination thereof. The light guide plate of claim 1, wherein the first cross-sectional line comprises a plurality of oblique lines inclined with respect to the bottom surface and connected to each other, a plurality of curves connected to each other, or a combination thereof. A backlight module includes: a light guide plate, comprising: a light emitting surface; a bottom surface opposite to the light emitting surface; at least one light incident surface connecting the light emitting surface and the bottom surface; and a plurality of optical microstructures disposed on the light emitting surface Each of the optical microstructures has a first surface inclined toward a side facing the light incident surface, wherein the first surface is cut along a direction perpendicular to the light incident surface and the light exit surface The resulting cut line includes a first cut line that is substantially a portion of a parabola; a second surface that is coupled to the first surface and that faces away from the side of the light incident surface Tilting, wherein the first surface is located between the light incident surface and the second surface; and at least one light emitting element disposed adjacent to the light incident surface and adapted to emit a light beam, wherein the light beam enters through the light incident surface The light guide plate is transmitted to the outside of the light guide plate via the light exit surface. The backlight module of claim 20, wherein the parabola has a focus and an axis of symmetry, the parabola intersecting the bottom surface with a first end, the parabola and the second surface of the optical microstructure Crossing the second end point, the first end point and the focus of the parabola are connected to form a first reference line, and the second end point is connected with the focus of the parabola to form a second reference line, the first reference line and the first reference line The angle of the axis of symmetry is θ _MAX , the angle between the second reference line and the axis of symmetry is θ _MIN , and the angle θ _MAX and the angle θ _MIN satisfy the following formula: θ _MAX Sin ^-1 (1/n)+5°-φθ _MIN =θ+φ where θ satisfies: 0<θ<θ _MAX -φ, n is the refractive index of the light guide plate, and φ is the bottom surface and the parabola The angle of the axis of symmetry. The backlight module of claim 20, wherein the parabola has a focus, a vertex, and an axis of symmetry, and the distance c from the vertex to the focus satisfies at least one of two: 4c‧(cotθ _MIN - cot θ _MAX )=D4c‧[(cot θ _MIN ) ² -(cot θ _MAX ) ² ]=L, wherein the parabola intersects the bottom surface at a first end point, the parabola intersecting the second surface of the optical microstructure And at a second end point, the distance between the first end point and the second end point in a direction parallel to the bottom surface is L, and the first end point to the second end point are in a direction perpendicular to the bottom surface The distance between the first end point and the focus of the parabola is a first reference line, and the second end point is connected with the focus of the parabola into a second reference line, the first reference line and the axis of symmetry angle is θ _MAX, the second angle between the reference line and the axis of symmetry of θ _MIN. The backlight module of claim 20, wherein the parabola has a focus, a vertex, and an axis of symmetry, and the distance c from the vertex to the focus satisfies the following two formulas: The parabola intersects the bottom surface with a first end point, the parabola intersecting the second end of the optical microstructure with a second end point, the first end point being parallel to the second end point The distance in the direction of the bottom surface is L, and the distance from the first end point to the second end point in a direction perpendicular to the bottom surface is D, and the first end point is connected with the focus of the parabola into a first reference line. The second end point is connected to the focus of the parabola to form a second reference line. The angle between the first reference line and the axis of symmetry is θ _MAX , and the angle between the second reference line and the axis of symmetry is θ _MIN . The backlight module of claim 20, wherein the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and the light exit surface comprises a second cut line, the second The stub is essentially a diagonal line that is inclined relative to the bottom surface. The backlight module of claim 24, wherein the oblique line and the normal line of the light-emitting surface are sharply γ, and satisfy the following formula: Where Ψ is the angle between an outgoing beam and the normal of the light exiting surface, φ is the angle between the bottom surface and the axis of symmetry of the parabola, and n is the refractive index of the light guide plate. The backlight module of claim 20, wherein the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and the light exit surface comprises a second cut line, the second cut The line is substantially a curve that is convex or concave away from the bottom surface and the light incident surface. The backlight module of claim 20, wherein each of the optical microstructures is a bump, extending along a direction substantially parallel to the light exiting surface, or along a substantially parallel strip An arc-shaped ridge extends in the direction of the illuminating surface. The backlight module of claim 20, wherein the cut line obtained by cutting the first surface along a direction perpendicular to the light incident surface and parallel to the light exit surface comprises a second cut line, the first The second cut line is a straight line, and the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and parallel to the light exit surface includes a third cut line, the third cut line is a straight line, and the first The two cut lines are substantially parallel to the third cut line. The backlight module of claim 20, wherein a distance between the first surface and the bottom surface to a boundary between the second surface and the bottom surface is from a center of the optical microstructure to two of the optical microstructure Side decrement. The backlight module of claim 20, wherein the cut line obtained by cutting the first surface along a direction perpendicular to the light incident surface and parallel to the light exit surface comprises a second cut line, the first The second line is a first arc, and the arc of the first arc faces away from the light incident surface, and the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and parallel to the light exit surface A third cut line is included, and the third cut line is a straight line or a second arc. The backlight module of claim 20, wherein at least one of the light incident surfaces is opposite to the first light incident surface and the second light incident surface, and the at least one light emitting element is respectively disposed in the first light input surface. a light emitting surface and a second light emitting element adjacent to the second light incident surface, the optical microstructures comprising a plurality of first optical microstructures and a plurality of second optical microstructures, the first surface of each of the first optical microstructures facing Inclining in a direction toward a side of the first light incident surface, the second surface of each of the first optical microstructures is inclined toward a direction opposite to the side of the first light incident surface, each of the second optics The first surface of the microstructure is inclined toward a side facing the second light incident surface, the second surface of each of the second optical microstructures facing away from the side of the second light incident surface Tilt in direction. The backlight module of claim 20, wherein the first surface of each of the first optical microstructures is in contact with the first surface of one of the second optical microstructures to form a first ring shape The second surface of each of the first optical microstructures and the second surface of the second optical microstructures are connected to form a second annular surface, and the first annular surface surrounds the second surface Annular surface. The backlight module of claim 20, wherein the cut line obtained by cutting the first surface along a direction parallel to the light incident surface and perpendicular to the light exit surface comprises a second cut line, the first The second cut line is a first arc line, and the cut line obtained by cutting the second surface along a direction parallel to the light incident surface and perpendicular to the light exit surface includes a third cut line, and the third cut line is a first a second arc, and the arc of the first arc and the second arc face the light exiting surface. The backlight module of claim 20, wherein the cut line obtained by cutting the first surface along a direction perpendicular to the light incident surface and parallel to the light exit surface comprises a second cut line, the first The second cut line is a first arc line, and the cut line obtained by cutting the second surface along a direction perpendicular to the light incident surface and parallel to the light exit surface includes a third cut line, and the third cut line is a first The second arc has a radius of curvature greater than a radius of curvature of the second arc, and the first arc is concentric with the second arc. The backlight module of claim 20, wherein each of the optical microstructures further has a connection surface connecting the first surface and the second surface. The backlight module of claim 35, wherein the connecting surface comprises at least one plane, at least one curved surface or a combination thereof. The backlight module of claim 20, wherein the first section line comprises a plurality of oblique lines inclined with respect to the bottom surface and connected to each other, a plurality of curves connected to each other, or a combination thereof.