Light guide plate, backlight module and display device

A light guide plate, a backlight module and a display device are provided. The light guide plate includes a main body, plural first strip structures and second strip structures. The main body includes a light incident surface, an end portion and a light guide portion. The end portion has at least one inclined surface. The light guide portion is connected to the end portion. The light guide portion has a first optical surface and a second optical surface. At least one portion of each of the first strip structures is disposed on the first optical surface. At least one portion of each of the second strip structures is disposed on the second optical surface. An inherent type, an arrangement manner or an arrangement position of the first strip structures is different from an inherent type, an arrangement manner or an arrangement position of the second strip structures.

BACKGROUND

Field of Invention

The present invention relates to a light guide element and its application. More particularly, the present invention relates to a light guide plate and its applications in a backlight module and a display device.

Description of Related Art

In order to meet the design trend of thinness of the backlight module, light guide plates are designed to be thinner. However, when the thickness of the light guide plate is reduced, the light emitting diodes cannot be reduced to the same height as the thickness of the light guide plate. If the height of the light-emitting diode is greater than the thickness of the light guide plate, the light guide plate cannot effectively use the light generated from the light-emitting diode, thus leading to a light leakage problem in the light guide plate.

In order to solve the aforementioned problem, a light guide plate with special shape is used to replace the conventional flat-plate type light guide plate in the general backlight module. The light guide plate with special shape mainly includes a tapered portion and a flat plate portion connected to the tapered portion. A thickness of one end of the tapered portion near a light source is greater than a thickness of the other end of the tapered portion which is connected to the flat plate portion. Therefore, light generated from the light source can enter the light guide plate from the tapered portion with a greater thickness and can propagate towards the flat plate portion. Therefore, the tapered portion can effectively utilize light generated from the light source, and the thickness of the flat plate portion can be reduced accordingly.

However, although the light guide plate with special shape can solve the aforementioned problem, when light propagates in such light guide plate with special shape, a portion of light will leak from a connection portion between the tapered portion and the flat plate portion, thus seriously affecting the optical appearance of the light guide plate.

SUMMARY

An object of the invention is to provide a light guide plate, a backlight module and a display device, in which the light guide plate has strip structures which can be used to mix light leaked from a light-incident side of the light guide plate, so as to increase illumination uniformity of the backlight module and the display device.

According to the aforementioned object, a light guide plate is provided. The light guide plate includes a main body, plural first strip structures and plural second strip structures. The main body includes a light incident surface, an end portion and a light guide portion. The end portion has at least one inclined surface. The light guide portion is connected to the end portion, in which the light guide portion has a first optical surface and a second optical surface opposite to the first optical surface. At least one portion of each of the first strip structures is disposed on the first optical surface. At least one portion of each of the second strip structures is disposed on the second optical surface. An inherent type, an arrangement manner or an arrangement position of the first strip structures is different from an inherent type, an arrangement manner or an arrangement position of the second strip structures.

According to an embodiment of the present invention, an extending direction of each first strip structure and an extending direction of each second strip structure are vertical to the light incident surface.

According to an embodiment of the present invention, each of the second strip structures has a more significant feature than each of the first strip structures.

According to an embodiment of the present invention, a length of each second strip structure is greater than that of each first strip structure.

According to an embodiment of the present invention, each of the second strip structures and the first strip structures is a convex portion, and a height of each second strip structure is greater than a height of each first strip structure.

According to an embodiment of the present invention, each of the second strip structures and the first strip structures is a concave portion, and a depth of each second strip structure is greater than a depth of each first strip structure.

According to an embodiment of the present invention, an arrangement density of the second strip structures is greater than an arrangement density of the first strip structures.

According to an embodiment of the present invention, a thickness of one end near the light incident surface of the end portion is greater than the other end of the end portion.

According to an embodiment of the present invention, the end portion includes a first inclined surface and a second inclined surface. The first inclined surface is connected to the first optical surface, in which each of the first strip structures is connected to a first bottom edge of the first inclined surface. The second inclined surface is connected to the second optical surface, in which each of the second strip structures is connected to a second bottom edge of the second inclined surface.

According to an embodiment of the present invention, the end portion includes a first inclined surface and a second inclined surface. The first inclined surface is connected to the first optical surface. The second inclined surface is connected to the second optical surface, in which a first distance between each first strip structure and a first bottom edge of the first inclined surface is different from a second distance between each second strip structure and a second bottom edge of the second inclined surface.

According to an embodiment of the present invention, the end portion includes a first inclined surface and a second inclined surface. The first inclined surface is connected to the first optical surface, in which one portion of each first strip structure is located on the first inclined surface, and the other portion of each first strip structure is located on the first optical surface. The second inclined surface is connected to the second optical surface, in which one portion of each second strip structure is located on the second inclined surface, and the other portion of each second strip structure is located on the second optical surface.

According to an embodiment of the present invention, one end of each of the first strip structures and the second strip structures away from the light incident surface is located between the light incident surface of the main body and a side surface opposite to the light incident surface.

According to an embodiment of the present invention, the end portion includes a first inclined surface and a second inclined surface. The first inclined surface has a first top edge and a first bottom edge, in which the first bottom is connected to the first optical surface. The second inclined surface has a second top edge and a second bottom edge, in which the second bottom edge is connected to the second optical surface. The light incident surface is connected to the first top edge and the second top edge.

According to an embodiment of the present invention, the end portion includes a first platform surface, a second platform surface, a first inclined surface and a second inclined surface. The first inclined surface has a first top edge connected to the first platform surface and a first bottom edge connected to the first optical surface. The second inclined surface has a second top edge connected to the second platform surface and a second bottom edge connected to the second optical surface. The light incident surface is connected to the first platform surface and the second platform surface.

According to the aforementioned object, a backlight module is provided. The backlight module includes the aforementioned light guide plate and a light source. The light source is disposed adjacent to the light incident surface.

According to the aforementioned object, a display device is provided. The display device includes the aforementioned backlight module and a display panel. The display panel is disposed in front of the backlight module.

According to an embodiment of the present invention, the display panel is disposed in front of the first optical surface, and the display panel has a non-display area, and the first strip structures are located in an area of the light guide plate which is corresponding to the non-display area.

It can be known from the aforementioned embodiments of the present invention that, the light guide plate has different first strip structures and second strip structures respectively disposed on first optical surface and the second optical surface. Therefore, the first strip structures can effectively mix light leaked from the first optical surface near the connection portion between the end portion and the light guide portion, and the second strip structures can effectively mix light leaked from the second optical surface near the connection portion between the end portion and the light guide portion, thereby solving the problems of bright band or non-uniform brightness.

DETAILED DESCRIPTION

Referring toFIG. 1,FIG. 1illustrates a perspective view of a backlight module400in accordance with an embodiment of the present invention. The backlight module400of the present embodiment mainly includes a light guide plate500and a light source410. The light source410is disposed at a side of the light guide plate500. The light guide plate500mainly includes a main body510, plural first strip structures520and plural second strip structures530. The first strip structures520and the second strip structures530are disposed on the main body510. The first strip structures520and the second strip structures530are used to mix light leaked from a portion near the light-incident side of the light guide plate500, thereby reducing a non-uniform brightness phenomenon generated adjacent to the light-incident side of the light guide plate500and increasing illumination uniformity of the backlight module400.

Referring toFIG. 1again, the main body510of the light guide plate500mainly includes a light incident surface511, an end portion512, a light guide portion513and a side surface514. The end portion512is a tapered structure and has one end with greater thickness and the other end with smaller thickness. The light incident surface511is located at the end of the end portion512which has greater thickness. The light guide portion513is connected to the end of the end portion512which has smaller thickness. The light guide portion513is a flat plate with a uniform thickness. In the present embodiment, the end portion512has a first inclined surface512aand a second inclined surface512brespectively connected to two opposite sides of the light incident surface511. In addition, the light guide portion513has a first optical surface513aand a second optical surface513bopposite to each other. The side surface514is located at a side of the light guide portion513away from the end portion512, and the side surface514is connected to the first optical surface513aand the second optical surface513b. As shown inFIG. 1, the first inclined surface512ahas a first top edge512cand a first bottom edge512d, the second inclined surface512bhas a second top edge512eand a second bottom edge512f. In the present embodiment, the light incident surface511is connected to the first top edge512cand the second top edge512e, and the first optical surface513ais connected to the first bottom edge512dof the first inclined surface512a, and the second optical surface513bis connected to second bottom edge512fof the second inclined surface512b.

Simultaneously referring toFIG. 1,FIG. 2andFIG. 3, in whichFIG. 2andFIG. 3illustrate a top view and a bottom view of the light guide plate500in accordance with a first embodiment of the present invention. An extending direction of each of the first strip structures520and the second strip structures530is vertical to the light incident surface511. In one embodiment, at least one portion of each first strip structure520is disposed on the first optical surface513a, and at least one portion of each second strip structure530is disposed on the second optical surface513b. In the present embodiment, as shown inFIG. 1, one end of each first strip structure520is connected to the first bottom edge512dof the first inclined surface512a, and the other end of each first strip structure520is located between the incidence surface511and the side surface514. One end of each second strip structure530is connected to the second bottom edge512fof the second inclined surface512b, and the other end of each second strip structure530is located between the incidence surface511and the side surface514. In one embodiment, each of the first strip structures520and the second strip structures530extends along a direction away from the light incident surface511of the main body510. For example, the extending direction of each of the first strip structures520and the second strip structures530is vertical to the light incident surface511of the main body510(as shown in the present embodiment), or each of the first strip structures520and the second strip structures530can be inclined relative to the light incident surface511of the main body510(as shown inFIG. 10).

In the present embodiment, as shown inFIG. 1, the backlight module400further includes a reflecting film420disposed at a side of the second optical surface513bof the light guide plate500. The reflecting film420is used to reflect light which emitted from the second inclined surface512bor second optical surface513bback to the light guide plate500. Without disposing the first strip structures520and second strip structures530on the main body510, light provided by the light source410is likely leaked from a connection portion between the end portion512and the light guide portion513, thus leading to the problem of bright bands or a non-uniform brightness phenomenon. Therefore, by disposing the first strip structures520and second strip structures530on the main body510, light leaked from the connection portion between the end portion512and the light guide portion513can be mixed, so as to solve the problem of the bright bands or non-uniform brightness on the light guide plate500.

Referring toFIG. 1, a propagation path of light directly emitted from the first inclined surface512aor the first optical surface513ais different from a propagation path of light emitted from the second inclined surface512bor the second optical surface513b, reflected back to the main body510by the reflecting film420, and then emitted from the first inclined surface512aor the first optical surface513a. Therefore, an inherent type, an arrangement manner or an arrangement position of the first strip structures520is different from an inherent type, an arrangement manner or an arrangement position of the second strip structures530. It is noted that, the “inherent type” used herein means lengths, heights, depths or widths of the first strip structures520and the second strip structures530.

In the present embodiment, a feature of each of the second strip structures530is more significant than a feature of each of the first strip structures520. For example, as shown inFIG. 2andFIG. 3, a length L2of each of the second strip structures530is greater than a length L1of each of the first strip structures520. In the present embodiment, the first optical surface513ais a light-emitting surface of the backlight module400. Simultaneously referring toFIG. 13, the display panel910is disposed on the backlight module400. A black edge of the display panel910which is not used to display images can be defined as a non-display area, and a central region of the display panel910which can display images can be defined as an active area. In the present embodiment, the first strip structures520, the second strip structures530and the end portion512of the light guide plate500are disposed in the non-display area so as to avoid affecting the light-emitting quality of the active area. On the other hand, in order to comply with the requirements of narrow border backlight module and maximization of display area, the non-display area itself as well as the first strip structures520and second strip structures530have to be designed to be very small, and therefore second strip structures530located on the second optical surface513bwhich have more significant feature can effectively improve light-emitting effect of the active area of the light guide plate500.

In other embodiments, features of the first strip structures and the second strip structures can be varied. Referring toFIG. 4,FIG. 4illustrates a side view of a light guide plate610in accordance with a second embodiment of the present invention. The structure of the light guide plate610inFIG. 4is similar to that of the light guide plate500inFIG. 1, and the main difference therebetween is that first strip structures612and second strip structures614of the light guide plate610have different heights. As shown inFIG. 4, each of the first strip structures612and second strip structures614is a convex structure. Each of the first strip structures612has a height H1, and each of the second strip structures614has a height H2. In one embodiment, the height H1is different from the height H2. In the present embodiment, the height H1of each first strip structure612is smaller than the height H2of each second strip structure614. In other words, the feature of each second strip structure614is more significant than that of each first strip structure612. Therefore, when the first strip structures612and the second strip structures614are designed to be very small, the second strip structures614located on the second optical surface513bwhich have more significant feature can effectively improve light-emitting effect of an active area of the light guide plate610. In the present embodiment, a length of the first strip structures612is equal to a length of the second strip structures614. In other embodiments, the length of the first strip structures612can be designed to be different from the length of the second strip structures614according to different requirements.

Referring toFIG. 5,FIG. 5illustrates a side view of a light guide plate620in accordance with a third embodiment of the present invention. The structure of the light guide plate620inFIG. 5is similar to that of the light guide plate610inFIG. 4, and the main difference therebetween is that each of first strip structures622and second strip structures624of the light guide plate620is a concave structure, and the first strip structures622and second strip structures624have different depths. As shown inFIG. 5, each of the first strip structures622has a depth D1and each of the second strip structures624has a depth D2. In one embodiment, the depth D1is different from the depth D2. In the present embodiment, the depth D1of each first strip structure622is smaller than the depth D2of each second strip structure624. In other words, the feature of each second strip structure624is more significant than that of each first strip structure622. Therefore, when the first strip structures622and the second strip structures624are designed to be very small, the second strip structures624located on the second optical surface513bwhich have more significant feature can effectively improve light-emitting effect of an active area of the light guide plate620. In addition, in the present embodiment, a length of the first strip structures622is equal to a length of the second strip structures624. In other embodiments, the length of the first strip structures622can be designed to be different from the length of the second strip structures624according to different requirements.

In some embodiments, the arrangement densities of the first strip structures and the second strip structures can be varied according to different requirements. Simultaneously referring toFIG. 6andFIG. 7,FIG. 6andFIG. 7illustrate a top view and a bottom view of a light guide plate630in accordance with a fourth embodiment of the present invention. The structure of the light guide plate630inFIG. 6andFIG. 7is similar to that of the light guide plate500inFIG. 1, and the main difference therebetween is that an arrangement distance between each first strip structure632is different from an arrangement distance between each second strip structure634. As shown inFIG. 6, there is a first distance W1between any two adjacent first strip structures632. As shown inFIG. 7, there is a second distance W2between any two adjacent second strip structures634. In one embodiment, the first distance W1is different from the second distance W2. In the present embodiment, the second distance W2is smaller than the first distance W1. In other words, the second strip structures634are arranged more densely than the first strip structures632. Therefore, the second strip structures634located on a back surface of the light guide plate630(i.e. the second optical surface513bwhich is not used as a light-emitting surface) which have greater arrangement density can effectively improve light-emitting effect of an active area of the light guide plate630. In addition, a length of the first strip structures632is equal to a length of the second strip structures634. In other embodiments, the length of the first strip structures632can be designed to be different from the length of the second strip structures634according to different requirements. In addition, a height (or depth) of each first strip structure632and a height (or depth) of each second strip structure634can be designed to be equal or unequal according to different requirements. It is noted that, in the aforementioned embodiments, the first strip structures520,612,622and632of the light guide plate500,610,620and630which are connected to the first bottom edge512dof the first inclined surface512a, and the second strip structures530,614,624and634which are connected to the second bottom edge512fof the second inclined surface512bare merely used as an example for explanation, and embodiments of the present invention are not limited thereto. In other embodiments, the first strip structures can be not connected to the first bottom edge512d, and the second strip structures can be not connected to the second bottom edge512f. In other words, the first strip structures can be spaced from the first bottom edge at a distance, and the second strip structures can be spaced from the second bottom edge at a distance.

Referring toFIG. 8andFIG. 9,FIG. 8andFIG. 9illustrate a top view and a bottom view of a light guide plate640in accordance with a fifth embodiment of the present invention. The structure of the light guide plate640inFIG. 8andFIG. 9is similar to that of the light guide plate500inFIG. 1, and the main difference therebetween is that a first distance L3between first strip structures642of the light guide plate640and the first bottom edge512dis different from a second distance L4between second strip structures644of the light guide plate640and the second bottom edge512f. In the present embodiment, the second distance L4is greater than the first distance L3. Therefore, the second strip structures644located on a middle region of a back surface (i.e. the second optical surface513bwhich is not used as a light-emitting surface) of the light guide plate640can effectively improve light-emitting effect of the active area of the light guide plate640. In one embodiment, an extending direction of a portion of each first strip structure642located on the first optical surface513aand an extending direction of a portion of each second strip structure644located on the second optical surface513bare parallel to a normal line vertical to the light incident surface511. Moreover, lengths of the first strip structures642and the second strip structures644are smaller than a length of the main body510of the light guide plate640. In one embodiment, the length of the first strip structures642is equal to the length of the second strip structures644. In other embodiments, the length of the first strip structures642can be designed to be different from the length of the second strip structures644according to different requirements. In addition, a height (or depth) of each first strip structure642and a height (or depth) of each second strip structure644can be designed to be equal or unequal according to different requirements.

It is noted that, one end of each first strip structure520ofFIG. 1which is connected to the first bottom edge512dof the first inclined surface512a, the other end of each first strip structure520which is located between the light incident surface511and the side surface514, and one end of each second strip structure530is connected to the second bottom edge512fof the second inclined surface512b, the other end of each second strip structure530which is located between the light incident surface511and the side surface514are merely used as an example for explanation, and embodiments of the present invention are not limited thereto. In other embodiments, one end of each first strip structure near the light incident surface511can be extended onto the first inclined surface512a, and one end of each second strip structure530near the light incident surface511can be extended onto the second inclined surface512b. Referring toFIG. 10,FIG. 10illustrates a side view of a light guide plate650in accordance with a sixth embodiment of the present invention. The structure of the light guide plate650inFIG. 10is similar to that of the light guide plate500inFIG. 1, and the main difference therebetween is that first strip structures652and second strip structures654of the light guide plate650have different designs.

As shown inFIG. 10, one end of the first strip structure652near the light incident surface511is located on the first inclined surface512a, the other end of the first strip structure652away from the light incident surface511is located on the first optical surface513abetween the light incident surface511and the side surface514. One end of the second strip structure654near the light incident surface511is located on the second inclined surface512b, the other end of the second strip structure654away from the light incident surface511is located on the second optical surface513bbetween the light incident surface511and the side surface514. It is noted that, the designs, the arrangement manners and the effects of the first strip structures652and second strip structures654are similar to those of the first strip structures520,612,622,632and642and the second strip structures530,614,624,634and644shown inFIG. 1-FIG. 9, and therefore will not be described again herein.

In the present invention, the main body of the light guide plate may have different structural designs. Referring toFIG. 11,FIG. 11illustrates a side view of a light guide plate700in accordance with a seventh embodiment of the present invention. The light guide plate700of the present embodiment mainly includes a main body710, plural first strip structures720and plural second strip structures730. The main body710mainly includes a light incident surface711, an end portion712, a light guide portion713and a side surface714. In the present embodiment, the end portion712is a tapered structure and has one end with greater thickness and the other end with smaller thickness. As shown inFIG. 26, the end portion712includes a first platform surface712a, a second platform surface712b, a first inclined surface712cand a second inclined surface712d. The light incident surface711is located at a the end of the end portion712which has greater thickness, and the light incident surface711is connected to the first platform surface712aand the second platform surface712b. The light guide portion713is connected to the end of the end portion712which has smaller thickness, and the light guide portion713is a flat plate with a uniform thickness. The light guide portion713includes a first optical surface713aand a second optical surface713bopposite to each other.

Referring toFIG. 11, the first inclined surface712cof the end portion712has a first top edge712eand a first bottom edge712f. The first top edge712eis connected to the first platform surface712a, and the first bottom edge712fis connected to the first optical surface713a. Similarly, the second inclined surface712dhas a second top edge712gand a second bottom edge712h. The second top edge712gis connected to the second platform surface712b, and the second bottom edge712his connected to the second optical surface713b. It is noted that, the designs, the arrangement manners and the effects of the first strip structures720and second strip structures730are similar to those of the first strip structures520,612,622,632,642and652and the second strip structures530,614,624,634,644and654shown inFIG. 1-FIG. 10, and therefore will not be described again herein.

In the present invention, the main body of the light guide plate may have different structural designs. Referring toFIG. 12,FIG. 12illustrates a side view of a light guide plate800in accordance with an eighth embodiment of the present invention. The light guide plate800of the present embodiment mainly includes a main body810, plural first strip structures820and plural second strip structures830. The main body810mainly includes a light incident surface811, an end portion812and a light guide portion813. In the present embodiment, the end portion812is a tapered structure and has one end with greater thickness and the other end with smaller thickness. Moreover, the end portion812has an inclined surface812aat one side and a flat surface812bat the other side. As shown inFIG. 12, the light incident surface811is located on the end of the end portion812which has greater thickness, and the light guide portion813is connected to the end of the end portion812which has smaller thickness. The light guide portion813is a flat plate with a uniform thickness. In the present embodiment, the light guide portion813has a first optical surface813aand a second optical surface813bopposite to each other.

Referring toFIG. 12, in the present embodiment, the first strip structures820and the second strip structures830are respectively disposed on the first optical surface813aand the second optical surface813b. It is noted that, the designs, the arrangement manners and the effects of the first strip structures820and second strip structures830are similar to those of the first strip structures520,612,622,632,642,652and720and the second strip structures530,614,624,634,644,654and730shown inFIG. 1-FIG. 11, and therefore will not be described again herein.

Referring toFIG. 13,FIG. 13illustrates a perspective view of a display device900in accordance with an embodiment of the present invention. The display device900of the present embodiment includes a backlight module400shown inFIG. 1and a display panel910. As shown inFIG. 13, the display panel910is disposed in front of the first optical surface513aof the light guide plate500in the backlight module400. The first strip structures520of the light guide plate500is disposed corresponding to the non-display area of the display panel, and the first strip structures520can be used to cooperate with the second strip structures530so as to achieve the objectives of adjusting light as described above and will not be described therein. It is noted that, the backlight module400having the light guide plate500shown inFIG. 1is merely used as an example applied to the display device800for explanation, and embodiments of the present invention are not limited thereto. In other embodiments, other backlight modules, such as the backlight modules having the light guide plate500,610,620,630,640,650and700also can be applied to a display device, so as to achieve the same effect.

It can be known from the aforementioned embodiments of the present invention that, the light guide plate has different first strip structures and second strip structures respectively disposed on first optical surface and the second optical surface. Therefore, the first strip structures can effectively mix light leaked from the first optical surface near the connection portion between the end portion and the light guide portion, and the second strip structures can effectively mix light leaked from the second optical surface near the connection portion between the end portion and the light guide portion, thereby solving the problems of bright band or non-uniform brightness.