Light guide plate, backlight module and display device

A backlight module includes a light guide plate and a plurality of light-emitting units. The plurality of light-emitting units emit light toward a light incident surface of the light guide plate. The plurality of light-emitting units are attached to the light incident surface of the light guide plate and arranged along a target direction in manner of spacing between two adjacent light-emitting units. A plurality of light-converging portions are arranged along the target direction in an end portion of the light guide plate where the light incident surface is located, and the plurality of light-converging portions are disposed at locations of the light guide each of which is corresponding to the spacing. The plurality of light-converging portions are configured to converge light incident into the light-converging portions through the light incident surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 201820333763.1, filed on Mar. 12, 2018, titled “A LIGHT GUIDE PLATE, BACKLIGHT MODULE AND DISPLAY DEVICE”, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, in particular, to a light guide plate, a backlight module and a display device.

BACKGROUND

As an important component of liquid crystal display devices, backlight modules are used for providing light sources for display panels in the liquid crystal display devices. Since a light-emitting effect of the backlight module directly affects a display quality of the liquid crystal display device, it has always been the goal to obtain a backlight module capable of providing a uniform and bright light source.

SUMMARY

In a first aspect, some embodiments of the present disclosure provide a backlight module. The backlight module includes a light guide plate and a plurality of light-emitting units. The plurality of light-emitting units emit light toward a light incident surface of the light guide plate. The plurality of light-emitting units are attached to the light incident surface of the light guide plate and arranged along a target direction in manner of spacing between two adjacent light-emitting units. A plurality of light-converging portions are arranged along the target direction in an end portion of the light guide plate where the light incident surface is located; the plurality of light-converging portions are disposed at locations of the light guide each of which is corresponding to the spacing. The plurality of light-converging portions are configured to converge light incident into the light-converging portions through the light incident surface. The target direction is an extending direction of an edge of a light emitting surface of the light guide plate which is in connection with the light incident surface.

In some embodiments, the plurality of light-emitting units have a determinate light-emitting range respectively, each of the plurality of light-converging portions is disposed at an area which is outside of respective light-emitting ranges of two adjacent light-emitting units.

In some embodiments, each of the plurality of light-converging portion includes a first light-converging cavity that is hollow, and the first light-converging cavity comprises at least one light-converging cavity unit; in the target direction, a width of a middle region of the at least one light-converging cavity unit is less than a width of an edge region of the at least one light-converging cavity unit.

In some embodiments, the first light-converging cavity includes a single light-converging cavity unit of the at least one light-converging cavity unit; in a direction perpendicular to the light incident surface, the first light-converging cavity comprises a first surface and a second surface that are opposite to each other; the first surface is a concave curved surface, and the second surface is a flat surface, a concave curved surface or a convex curved surface.

In some embodiments, in a case where the second surface is a convex curved surface, a degree of concavity of the concave curved surface is greater than a degree of convexity of the convex curved surface.

In some embodiments, the first light-converging cavity includes at least two light-converging cavity units of the at least one light-converging cavity units; in a direction perpendicular to the light incident surface, each of the at least two light-converging cavity units comprises a third surface and a fourth surface that are opposite to each other; the third surface is a concave curved surface, and the fourth surface is a flat surface; alternatively, the fourth surface is symmetrical with the third surface relative to a central surface of the first light-converging cavity, and the central surface is parallel to the light incident surface; wherein two adjacent light-converging cavity units of the at least two light-converging cavity units are directly connected; alternatively, the two adjacent light-converging cavity units are connected by a rectangular cavity unit.

In some embodiments, each of the plurality of light-converging portion includes a second light-converging cavity and a filling portion located in the second light-converging cavity; and in the target direction, a width of a middle region of the second light-converging cavity is greater than a width of an edge region of the second light-converging cavity; wherein a refractive index of a material constituting the filling portion is greater than a refractive index of a material constituting the light guide plate.

In some embodiments, in a direction perpendicular to the light incident surface, the second light-converging cavity includes a fifth surface and a sixth surface that are opposite to each other; the fifth surface is a convex curved surface, and the sixth surface is a flat surface, a convex curved surface or a concave curved surface.

In some embodiments, in a case where the sixth surface is a concave curved surface, a degree of convexity of the convex curved surface is greater than a degree of concavity of the concave curved surface

In some embodiments, the plurality of light-emitting units are light-emitting diodes.

In a second aspect, some embodiments of the present disclosure provide a light guide plate used for the backlight module as described above. An end portion of the light guide plate where a light incident surface thereof is located has a plurality of light-converging portions that are spaced apart along the target direction. The light guide plate is configured to attach to the plurality of the light-emitting units in the backlight module in such a manner that the plurality of light-converging portions each correspond to the spacing between two adjacent light-emitting units.

In a third aspect, some embodiments of the present disclosure provide a display device, which includes the backlight module according to the second aspect.

DETAILED DESCRIPTION

The technical solutions in embodiments of the present disclosure will be described clearly and completely in conjunction with the accompanying drawings in embodiments of the present disclosure. Obviously, the described embodiments are merely some but not all of embodiments of the present disclosure. All other embodiments made on the basis of the embodiments of the present disclosure by a person of ordinary skill in the art without paying any creative effort shall be included in the protection scope of the present disclosure.

Backlight modules usually include a light guide plate and a plurality of light-emitting diodes (LEDs) that are disposed on one side of the light guide plate. Light emitted by the plurality of LEDs are guided by the light guide plate to form a surface light source. In areas within light-emitting ranges of the LEDs, intensity of light exiting the light guide plate is high, and thus these areas of the backlight module appear bright. However, in areas outside the light-emitting ranges of the LEDs, due to a low intensity of light exiting the light guide plate, these areas of the backlight module appear dim. For the above reasons, a dim area may be easily formed in a region between two LEDs in a light incident end of the light guide plate, which will cause hot spots (very bright areas that make other areas look dim) and seriously affect a display quality of a liquid crystal display device. Furthermore, in order to reduce power consumption of the backlight module and lower cost, a number of the LEDs in the backlight module is reduced. As a result, a distance between two adjacent LEDs is increased, which makes it even easier for dim areas to be formed in the light incident end of the light guide plate. In order to solve this dim area problem, one method commonly used in the related art is to improve the design of optical dots at the light incident end of the light guide plate. A term “dots” refers to protuberances that are on two surfaces of the light guide plate which are in a thickness direction of the light guide plate. Therefore, the light guide plate has a plurality of protuberances, i.e., a plurality of dots. The plurality of dots may enable light that is incident into the dots to generate diffuse reflection, thereby homogenizing the light. However, since a size and density of the optical dots are not easy to control, it is necessary to repeatedly modify design parameters of the optical dots for each time of production to remove the dim areas. This operation is very complicated.

Some embodiments of the present disclosure provide a backlight module. As shown inFIG. 2, the backlight module includes a light guide plate01and a plurality of light-emitting units40that emit light toward a light incident surface of the light guide plate01. The plurality of light-emitting units40are attached to the light incident surface of the light guide plate. The plurality of light-emitting units40are arranged along a target direction in manner of spacing between two adjacent light-emitting units, and each light-emitting unit40has a light-emitting angle. As shown inFIGS. 1aand 1b, a plurality of light-converging portions20are arranged along the target direction in an end portion A of the light guide plate01where the light incident surface10is located; the plurality of light-converging portions20are disposed in locations I (also referring to as areas I), i.e., dim areas, of the light guide plate each of which is corresponding to the spacing between two adjacent light-emitting units40. The light-converging portions20are used for converging light incident into the light-converging portions20through the light incident surface10. A term “light-emitting angle” refers to a angle at which most of the light emitted by the light-emitting unit is distributed, and is one of basic parameters of the light-emitting unit. Generally, for example, a light-emitting angle of an LED lamp is described in a product specification thereof.

The target direction is an extending direction of an edge E of a light emitting surface11of the light guide plate01that is in connection with the light incident surface10(i.e., direction X inFIG. 1aor1b). A term “light emitting surface” refers to a surface of the light guide plate which is provided with the light-converging portions20.

It will be noted that the above statement that “the plurality of light-converging portions20are disposed in areas I of the light guide plate each of which is corresponding to the spacing between two adjacent light-emitting units40” may be interpreted as follows: the light guide plate01has a plurality of areas I, and the plurality of the light-converging portions20are disposed in some of the plurality of areas I, i.e., the plurality of areas I also have some areas in which the light-converging portions20are not disposed. The statement may also be interpreted as follows: each of the plurality of areas I has at least one light-converging portion20. In some embodiments, as shown inFIG. 2, the statement that “the plurality of light-converging portions20are disposed in areas I of the light guide plate each of which is corresponding to the spacing between two adjacent light-emitting units40” is interpreted as follows: the number of the light-converging portions20is equal to the number of the areas I, the plurality of light-converging portions20are in one-to-one correspondence with the plurality of areas I, and each light-converging portion20is disposed in an area I corresponding to the light-converging portion20.

It will be noted that, as shown inFIG. 1a, in a direction perpendicular to the light incident surface10, the light guide plate01has an end portion A and an end portion B, and the light-converging portions20are located in the end portion A where the light incident surface10is located. This embodiment does not limit a structure of the light-converging portions20, as long as the light-converging portions20can converge the light incident into the light-converging portions20through the light incident surface10. The structure of the light-converging portions20inFIGS. 1aand 1bis only an example, and is not intended to limit the structure of the light-converging portion20.

Embodiments of the present disclosure provide backlight module that includes a light guide plate01and a plurality of light-emitting units40. The backlight module includes the plurality of light-emitting units40that emit light toward the light incident surface of the light guide plate01. And the plurality of light-emitting units40are sequentially arranged along the target direction. A plurality of light-converging portions20are arranged in the end portion A of the light guide plate01where the light incident surface10is located; the plurality of light-converging portions20are disposed in locations of the light guide plate each of which is corresponding to the spacing, i.e., area I between two adjacent light-emitting units40. The light-converging portions20are used for converging the light incident into the light-converging portions20through the light incident surface10. In this way, the light-converging portions20may converge a part of the light to the area I (that is, the above-mentioned dim area). Thus, it is unnecessary to repeatedly modify the design parameters of the optical dots of the light guide plate01to enhance brightness of the dim areas and remove the dim areas. Therefore, the operation becomes less complicated.

In some embodiments, as shown inFIG. 2, the plurality of light-emitting units40have a determinate light-emitting range respectively, each of the plurality of light-converging portions is disposed at an area which is outside of respective light-emitting ranges of two adjacent light-emitting units. An area D is an area within a light emitting range of the light-emitting unit40, and the area I is an area outside of respective light-emitting ranges of two adjacent light-emitting units40. As such, the plurality of the light-converging portions may converge a part of the light to the areas I each of which is outside of respective light-emitting ranges of two adjacent light-emitting units40in the backlight module, and thereby further enhancing brightness of the dim areas and remove the dim areas.

In some embodiments, as shown inFIG. 3, the light-converging portion20includes a first light-converging cavity201that is hollow, and the first light-converging cavity201includes a single light-converging cavity unit210. In the target direction, a width of a middle region of the light-converging cavity unit210(i.e., the first light-converging cavity201) is less than a width of an edge region of the light-converging cavity unit210. Since the width of the middle region of the light-converging cavity unit210is less than the width of the edge region of the first light-converging cavity201, a shape of the first light-converging cavity201is similar to a shape of a concave lens; moreover, since the first light-converging cavity201is hollow, i.e., a medium in the first light-converging cavity201is air, the first light-converging cavity201is equivalent to an “air concave lens”. As shown inFIG. 3, in this embodiment, the “air concave lens” is disposed in the light guide plate01. It is known to those skilled in the art that the light guide plate01is an optically denser medium as compared with the air, and the air is an optically rarer medium. The light is incident into the air from the light guide plate01, and is then incident into the light guide plate01from the air. According to a light-converging principle of the “air concave lens”, the light will be converged after two refractions. In this way, the first light-converging cavity201may be able to converge the light incident into the first light-converging cavity201.

It is known to those skilled in the art that depending on shapes of a light incident surface and a light emitting surface, the “air concave lens” may be classified into “air plano-concave lens”, “air biconcave lens” and “air meniscus lens”. The above three types of “air concave lenses” are all able to converge the light incident into the first light-converging cavity201. Hereinafter, the light-converging principle of the “air concave lens” will be described by taking the “air plano-concave lens” as an example. As shown inFIG. 4, the light L1is incident into the first light-converging cavity201(i.e., the air) from the light guide plate01; an angle of incidence is θ1, and an angle of refraction is θ2. The refracted light L2is incident into the light guide plate01from the air; an angle of incidence is θ3, and an angle of refraction is θ4; and then the light L3is obtained after two refractions. According to the refraction law n1×sin θ1=n2×sin θ2, wherein n1represents a refractive index of the light guide plate01, and n2represents a refractive index of the air, it may be known that θ2>θ1and θ3>θ4. According toFIG. 4, θ2>θ3, and then θ2>θ4. Therefore, since the angle of refraction θ2of the light incident on a light incident surface of the first light-converging cavity201is greater than the angle of refraction θ4of light exiting a light emitting surface of the first light-converging cavity201, the light L3converges toward a central region of the first light-converging cavity201relative to the light L1.

In order to make the width of the middle region of the first light-converging cavity201less than the width of the edge region of the first light-converging cavity201, in some embodiments, it is arranged that in a direction perpendicular to the light incident surface10, the first light-converging cavity201includes a first surface2011and a second surface2012that are opposite to each other, wherein the first surface2011is a concave curved surface, and the second surface2012is a flat surface, a concave curved surface or a convex curved surface. This embodiment does not limit a positional relationship between the first surface2011and the second surface2012in the direction perpendicular to the light incident surface10. That is, the first surface2011may be the light emitting surface of the first light-converging cavity201and the second surface2012may be the light incident surface of the first light-converging cavity201; alternatively, the second surface2012may be the light emitting surface of the first light-converging cavity201, and the first surface2011may be the light incident surface of the first light-converging cavity201.

For example, as shown inFIG. 3, the first surface2011is a concave curved surface, and the second surface2012is a flat surface. In this case, the shape of the first light-converging cavity201is similar to the shape of a plano-concave lens. At this time, the light-converging portion20is equivalent to an “air plano-concave lens”, and is able to converge the light incident into the first light-converging cavity201.

For another example, as shown inFIG. 5, the first surface2011is a concave curved surface, and the second surface2012is also a concave curved surface. In this case, the shape of the first light-converging cavity201is similar to the shape of a biconcave lens. At this time, the first light-converging cavity201is equivalent to an “air biconcave lens”, and is able to converge the light incident into the first light-converging cavity201, as shown inFIG. 5.

For yet another example, as shown inFIG. 6, the first surface2011is a concave curved surface, and the second surface2012is a convex curved surface. A degree of concavity of the concave curved surface is greater than a degree of convexity of the convex curved surface. In this case, the shape of the first light-converging cavity201is similar to the shape of a meniscus lens. At this time, the shape of the first light-converging cavity201is equivalent to the shape of an “air meniscus lens”. As shown inFIG. 6, the first light-converging cavity201is able to converge the light incident into the first light-converging cavity201.

It will be noted that in embodiments of the present disclosure, optionally, the concave curved surface may be a concave arc surface, and the convex curved surface may be a convex arc surface. Furthermore, inFIGS. 3, 5 and 6, two sides of the first light-converging cavity201arranged in the direction perpendicular to the light incident surface10indicate the first surface2011and the second surface2012. This embodiment does not limit shapes of another two surfaces constituting the first light-converging cavity201. For example, as shown inFIGS. 3, 5 and 6, the another two surfaces may both be flat surfaces, in which case another two sides of the first light-converging cavity201in a plan view thereof are straight lines.

It is known to those skilled in the art that a direction in which light travels through a lens is reversible. Therefore, inFIGS. 3, 5 and 6, in a case where the first surface2011of the light-converging cavity unit210is used as a light incident surface, and the second surface2012of the light-converging cavity unit210is used as a light emitting surface, the first light-converging cavity201is also able to converge the light incident into the first light-converging cavity201. Taking an example in which the first light-converging cavity201is in the shape of a plano-concave lens, for example, as shown inFIG. 7, the light emitting surface of the first light-converging cavity201is a flat surface, and the light incident surface of the first light-converging cavity201is a concave surface, the “air plano-concave lens” is still able to converge the light incident into the first light-converging cavity201.

In some other embodiments, as shown inFIG. 8, the light-converging portion20includes a first light-converging cavity201that is hollow, the first light-converging cavity201includes at least two light-converging cavity units210, and in the target direction, the width of the middle region of the light-converging cavity unit210is less than the width of the edge region of the light-converging cavity unit210. In this way, each light-converging cavity unit210is equivalent to an “air concave lens”. Thereby, the first light-converging cavity201constituted by the at least two light-converging cavity units210may be used to converge light.

In the above embodiment, the light-converging cavity units210may be directly connected, as shown inFIG. 8; alternatively, two adjacent light-converging cavity units210may be connected by a rectangular cavity unit211, as shown inFIG. 9, which is not specifically limited herein. It will be noted that the rectangular cavity unit211is a cavity unit two surfaces of which arranged in a direction perpendicular to the light incident surface10are both flat surfaces.

In order to make the width of the middle region of the light-converging cavity unit210less than the width of the edge region of the light-converging cavity unit210, in some embodiments, it is arranged that in the direction perpendicular to the light incident surface10, each light-converging cavity unit210includes a third surface2013and a fourth surface2014that are opposite to each other. The third surface2013is a concave curved surface, and the fourth surface2014is a flat surface; alternatively, the fourth surface2014is symmetrical with the third surface2013relative to a central surface30of the first light-converging cavity201, and the central surface30is parallel to the light incident surface10. This embodiment does not limit a positional relationship between the third surface2013and the fourth surface2014in the direction perpendicular to the light incident surface10. That is, the third surface2013may be the light emitting surface of the light-converging cavity unit210, and the fourth surface2014may be the light incident surface of the light-converging cavity unit210; alternatively, the fourth surface2014may be the light emitting surface of the light-converging cavity unit210, and the third surface2013may be the light incident surface of the light-converging cavity unit210.

For example, as shown inFIGS. 8 and 9, the third surface2013is a concave curved surface, and the fourth surface2014is a flat surface.

For another example, as shown inFIGS. 10 and 11, the third surface2013is a concave curved surface, the fourth surface2014is symmetrical with the third surface2013relative to the central surface30of the first light-converging cavity201, and the central surface30is parallel to the light incident surface10.

In some embodiments, as shown inFIG. 12, the light-converging portion20includes a second light-converging cavity202and a filling portion203located in the second light-converging cavity202; and in the target direction, a width of a middle region of the second light-converging cavity202is greater than a width of an edge region of the second light-converging cavity202. A refractive index of a material constituting the filling portion203is greater than a refractive index of a material constituting the light guide plate01. Since the width of the middle region of the second light-converging cavity202is greater than the width of the edge region of the second light-converging cavity202, a shape of the second light-converging cavity202is similar to a shape of a convex lens. Moreover, since a filling portion203is provided in the second light-converging cavity202, and the refractive index of the material constituting the filling portion203is greater than the refractive index of the material constituting the light guide plate01, the light-converging portion20is equivalent to a “convex lens”. It is known to those skilled in the art that a convex lens can converge light incident into the convex lens, and thus it will not be described in this embodiment. As shown inFIG. 12, in this embodiment, the “convex lens” is disposed in the light guide plate01; the filling portion203is an optically denser medium as compared with the light guide plate01, and the light guide plate01is an optically rarer medium in this case. The light is incident into the filling portion203from the light guide plate01, and is then incident into the light guide plate01from the filling portion203. The light will be converged after two refractions. In this way, according to a light-converging principle of the “convex lens”, the light-converging portion20may be able to converge the light incident into the second light-converging cavity202.

In order to make the width of the middle region of the second light-converging cavity202greater than the width of the edge region of the second light-converging cavity202, in some embodiments, as shown inFIG. 12, it is arranged that in the direction perpendicular to the light incident surface10, the second light-converging cavity202includes a fifth surface2015and a sixth surface2016that are opposite to each other. The fifth surface2015is a convex curved surface, and the sixth surface2016is a flat surface, a convex curved surface or a concave curved surface. This embodiment does not limit a positional relationship between the fifth surface2015and the sixth surface2016in the direction perpendicular to the light incident surface10. That is, the fifth surface2015may be the light emitting surface of the second light-converging cavity202, and the sixth surface2016may be the light incident surface of the second light-converging cavity202; alternatively, the sixth surface2016may be the light emitting surface of the second light-converging cavity202, and the fifth surface2015may be the light incident surface of the second light-converging cavity202. A description is given in embodiments of the present disclosure by only taking an example in which the fifth surface2015is the light emitting surface of the second light-converging cavity202.

For example, as shown inFIG. 12, the fifth surface2015is a convex curved surface, and the sixth surface2016is a flat surface. In this way, the shape of the second light-converging cavity202is similar to a shape of a plano-convex lens. At this time, the light-converging portion20is equivalent to a plano-convex lens, which is able to converge the light incident into the second light-converging cavity202.

For another example, as shown inFIG. 13, the fifth surface2015is a convex curved surface, and the sixth surface2016is also a convex curved surface. In this way, the shape of the second light-converging cavity202is similar to a shape of a biconvex lens. At this time, the light-converging portion20is equivalent to a biconvex lens, which is able to converge the light incident into the second light-converging cavity202.

For yet another example, as shown inFIG. 14, the fifth surface2015is a convex curved surface, and the sixth surface2016is a concave curved surface. A degree of convexity of the convex curved surface is greater than a degree of concavity of the concave curved surface. In this way, the shape of the second light-converging cavity202is similar to the shape of a meniscus lens. At this time, the light-converging portion20is equivalent to a meniscus lens, which is able to converge the light incident into the second light-converging cavity202.

It will be noted that in embodiments of the present disclosure, optionally, the concave curved surface may be a concave arc surface, and the convex curved surface may be a convex arc surface. Furthermore, inFIGS. 12, 13 and 14, two sides of the second light-converging cavity202arranged in the direction perpendicular to the light incident surface10indicate the fifth surface2015and the sixth surface2016. This embodiment does not limit shapes of another two surfaces constituting the second light-converging cavity202. For example, as shown inFIGS. 12, 13 and 14, the another two surfaces may both be flat surfaces, in which case another two sides in a plan view of the second light-converging cavity202are straight lines.

Since the direction in which light travels through a lens is reversible, in a case where the fifth surface2015of the second light-converging cavity202is used as a light incident surface, and the sixth surface2016of the second light-converging cavity202is used as a light emitting surface, the second light-converging cavity202is also able to converge the light incident into the second light-converging cavity202.

The backlight module provided in embodiments of the present disclosure may also include a plastic frame. A part of light emitted by the light-emitting units40is incident on the plastic frame after an action of the optical dots in the light guide plate01. The plastic frame will reflect the part of light to make the part of light re-enter the light guide plate01.

Embodiments of the present disclosure do not limit a structure of the light-emitting units40, as long as the light-emitting units40are able to emit light and the light is able to enter the light guide plate01. Considering that the cost of LEDs is low and the manufacturing process of LEDs is mature, in some embodiments, the light-emitting units40may be LEDs.

Some embodiments of the present disclosure further provide a light guide plate, which is used for the backlight module as described above. An end portion of the light guide plate where the light incident surface is located has the plurality of light-converging portions spaced apart along the target direction. The light guide plate is configured to attach to the plurality of the light-emitting units in the backlight module in such a manner that the plurality of light-converging portions each correspond to the spacing between two adjacent light-emitting units. Exemplarily, the light guide plate of embodiments of the present disclosure may include the structure as described above.

Some embodiments of the present disclosure further provide a display device, which includes the backlight module as described above, and has a same structure and advantageous effects as the backlight module provided in the preceding embodiments. Since the structure and advantageous effects of the backlight module have been described in detail in the above embodiments, they will not be described herein again.

The display device provided in embodiments of the present disclosure may be any product or component having a display function, such as a mobile phone, a tablet computer, a TV set, a display, a laptop, a digital photo frame, and a navigator.

In the above description of the embodiments, specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples.