WO2018214611A1

WO2018214611A1 - Backlight module and liquid crystal display device

Info

Publication number: WO2018214611A1
Application number: PCT/CN2018/078158
Authority: WO
Inventors: 李富琳; 宋志成; 刘卫东
Original assignee: 青岛海信电器股份有限公司
Priority date: 2017-05-22
Filing date: 2018-03-06
Publication date: 2018-11-29
Also published as: CN107329318A; CN107329318B

Abstract

A backlight module, comprising: multiple light emitting modules (100), each light emitting module (100) comprising a backlight element (200) and a light ray collimation structure (300); the backlight element (200) comprises at least one backlight source (210); the light ray collimation structure (300) comprises a convergence and turning component (310) and reflection components (320); the convergence and turning component (310) comprises a component body (311), the component body (311) comprises a reflection surface (313), said reflection surface (313) being used to reflect at least part of the light ray emitted by the backlight source (210) toward the plane in which the backlight element (200) is; the reflection components (320) are provided at the periphery of the convergence and turning component (310), each reflection component (320) comprises a curved surface (321), and said curved surface (321) is used for reflecting the light ray reflected from the reflection surface (313).

Description

Backlight module and liquid crystal display device

The present application claims priority to Chinese Patent Application No. 200910361475.7, entitled "Backlight Module and Liquid Crystal Display Device", filed on May 22, 2017, the entire contents of which is incorporated herein by reference. In the application.

Technical field

The present disclosure relates to the field of liquid crystal display, and in particular, to a backlight module and a liquid crystal display device.

Background technique

The liquid crystal display usually includes a backlight module and a liquid crystal panel which are sequentially disposed. The liquid crystal panel is a passive light-emitting component, which does not emit light by itself, and requires a backlight module to provide a backlight with sufficient brightness to realize the display function of the liquid crystal display device.

Summary of the invention

In a first aspect, the present disclosure provides a backlight module, the backlight module includes: a plurality of light emitting modules, each of the plurality of light emitting modules includes a backlight component and a corresponding one of the backlight components Light collimation structure. The backlight element includes at least one backlight source. The light collimating structure includes a converging turning member and a reflecting member. The converging steering member includes a light transmissive component body, and a surface of the body remote from the at least one backlight source includes a reflective surface, the reflective surface is configured to direct at least a portion of the light emitted by the at least one backlight source The plane reflection of the backlight element. The reflective member is disposed around the converging steering member, and the reflective member includes a curved surface for reflecting light reflected by the reflective surface.

In a second aspect, the present disclosure provides a liquid crystal display device including the above-described backlight module and liquid crystal panel. The liquid crystal panel includes a liquid crystal layer and a quantum dot color conversion layer, and the liquid crystal layer is disposed between the backlight module and the quantum dot color conversion layer. The liquid crystal layer includes a plurality of liquid crystal cells, and the quantum dot color conversion layer includes a plurality of quantum dot units, and the plurality of quantum dot units are disposed corresponding to the plurality of liquid crystal cells.

DRAWINGS

In order to more clearly illustrate the technical solutions of the present application, the drawings used in the embodiments will be briefly described below. Obviously, for those skilled in the art, without any creative labor, Other drawings can also be obtained from these figures.

1 is a schematic structural view of a liquid crystal display;

2 is a schematic diagram showing a distribution of backlight light emitted by a backlight source;

3 is a schematic structural diagram of a backlight module according to some embodiments of the present disclosure;

FIG. 4 is a schematic structural diagram of a light emitting module according to some embodiments of the present disclosure;

FIG. 5 is a schematic diagram of a parabolic reflection principle provided by some embodiments of the present disclosure; FIG.

FIG. 6 is a schematic diagram of an optical path of a backlight according to some embodiments of the present disclosure;

FIG. 7 is a schematic structural diagram of another light emitting module according to some embodiments of the present disclosure;

FIG. 8 is a schematic diagram of an optical path of another backlight according to some embodiments of the present disclosure; FIG.

FIG. 9 is a schematic structural diagram of a liquid crystal display device according to some embodiments of the present disclosure.

detailed description

1 is a schematic structural view of a liquid crystal display. As shown in FIG. 1, the liquid crystal display includes a backlight module 10 and a liquid crystal panel 20. The backlight module includes a plurality of LED blue backlights 11 that are evenly distributed. The liquid crystal panel 20 includes a liquid crystal layer 21 and a quantum dot color conversion layer 22. The liquid crystal layer 21 includes a plurality of liquid crystal cells 211 arranged in order. The quantum dot color conversion layer 22 includes a plurality of quantum dot conversion groups 221 arranged in order, each quantum dot conversion group 221 being composed of a red quantum dot unit, a green quantum dot unit, and a blank quantum dot unit arranged in order. Each of the quantum dot conversion units is disposed corresponding to one liquid crystal cell 211. When the liquid crystal display displays an image, the blue backlight enters the liquid crystal layer 21, and the liquid crystals in the respective liquid crystal cells 211 in the liquid crystal layer 21 can be rearranged according to display requirements, thereby changing the luminous flux of the blue backlight through the respective liquid crystal cells 211. The blue backlight passing through the liquid crystal layer 21 enters the quantum dot color conversion layer 22, and each of the quantum dot conversion groups 221 can emit three primary color backlights corresponding to the respective quantum dot conversion units. The backlights of the three primary colors with different luminous fluxes can be reconciled to obtain the color of a corresponding pixel. Displaying pixels of different colors on the screen together can form an image to be displayed.

The emission angle of the LED backlight is usually large, and the inventors have found that the backlight passing through the liquid crystal cell easily enters into other quantum dot conversion units other than the corresponding quantum dot conversion unit. For example, when the liquid crystal cell corresponding to a green quantum dot unit in FIG. 1 is turned on, a large angle blue backlight can enter the adjacent red quantum dot unit and the blank quantum dot unit through the liquid crystal cell, which is correspondingly obtained. A small amount of red backlight and blue backlight cause the color purity of the green backlight corresponding to the green quantum dot unit to decrease, and the color crosstalk between the three primary color backlights affects the display effect of the liquid crystal display.

FIG. 2 is a schematic diagram showing the distribution of backlight light emitted by a backlight source used in the research process. As can be seen from Fig. 2, the exit angle of the backlight light is usually distributed in a wide range, and backlight light is emitted between ±90° centered on the center line of the backlight source.

FIG. 3 is a schematic structural diagram of a backlight module according to some embodiments of the present disclosure. FIG. 4 is a schematic structural diagram of a light emitting module according to some embodiments of the present disclosure. Referring to FIG. 3 and FIG. 4 , the backlight module of the present disclosure includes: a plurality of light emitting modules 100 , each of the plurality of light emitting modules 100 includes a backlight component 200 , and a light collimating structure corresponding to the backlight component 200 . 300. The backlight element 200 includes at least one backlight source 210. In some embodiments, only one backlight source 210 is typically included within backlight element 200. The backlight element 200 is for providing a backlight having sufficient brightness to realize a display function of the liquid crystal display device. The same arrangement direction means that the light-emitting surfaces of the plurality of light-emitting modules 100 all face the same direction.

In some embodiments, the backlight source may be an LED or a light-emitting chip. The LED may refer to LEDs in the related art, and generally includes a light-emitting chip, a phosphor, and a package housing.

The optical collimating structure 300 is disposed in the light emitting direction of the backlight element 200 in some embodiments.

In some embodiments, the backlight module is a direct-lit backlight module, and the direct-lit backlight module includes a back plate, a diffusion plate, and an optical film. The light-emitting module is disposed on the back plate, and the light-emitting surface of the light-emitting module faces the diffusion. The plate, the optical film is disposed on a side of the diffuser plate away from the back plate.

In some embodiments disclosed herein, each of the light collimating structures 300 includes a converging turning member 310 and a reflecting member 320 that are symmetrically disposed about the converging turning member 310. The entire light collimating structure 300 may be a circumferentially symmetrical structure or a square structure.

In some embodiments, the convergence steering member 310 includes a lens having a tapered surface disposed thereon for reflecting at least a portion of the light emitted by the backlight element 200 toward a plane in which the backlight element 200 is located, and the backlight element All of the light from the light emitted by 200 is reflected toward the plane of the backlight element 200. The reflective member 320 includes at least one curved reflecting surface that receives the conical reflecting surface reflection at the top of the converging turning member 310. Light rays and reflect the light they receive away from the backplane.

In some embodiments, the generatrix of the tapered face is a straight line in a cross-sectional view along an axis of symmetry passing through the apex of the tapered face, and in some embodiments, the straight line is symmetrical with the apex of the tapered face The angle of the shaft is greater than 30°.

In some embodiments, the generatrix of the tapered face is a curve that projects toward the axis of symmetry passing through the apex of the tapered face in a cross-sectional view along the axis of symmetry passing through the apex of the tapered face.

In some embodiments, the convergence steering component 310 includes a tapered reflective surface for reflecting light emitted by the backlight element 200 toward a plane in which the backlight element 200 is located, the reflective component 320 including at least one curved reflective surface. The curved reflecting surface receives the light reflected by the tapered reflecting surface and reflects the received light toward the direction away from the back plate. The tapered reflecting surface may be formed after coating a reflective layer on the tapered surface of the lens.

In some embodiments, the light-emitting angle of the reflective member 320 is smaller than the light-emitting angle of the backlight element 200, and the light-emitting angle of the reflective member refers to a maximum angle formed by the light reflected by the reflective member.

In some embodiments disclosed herein, the convergence steering component 310 includes a component body 311 of a highly transmissive material. A surface of the light-transmitting component body 311 is provided with a recess 312, and the backlight element 200 is located in the recess 312. In the present disclosure, the surface on which the groove 312 is provided is set to converge the bottom surface of the steering member 310, and the upper and lower positional relationships of the other members are based on this. The bottom surface may be a plane in which the backlight element 200 is located. Another face (top face) of the component body 311 opposite the recess 312 includes a reflective surface for reflecting the backlight to the reflective component. Illustratively, the reflective surface includes an inverted tapered surface, i.e., the other surface of the component body 311 opposite the recess 312 has a cross-section like a V-like structure 313 for reflecting the backlight. In some embodiments disclosed herein, the component body 311 is a regular body such as a straight quadrangular cylinder or a cylinder to facilitate the arrangement of the groove 312 and the V-like structure reflecting surface and the stabilization of the converging steering member 310. Of course, the component body 311 may also be an irregular body as long as the groove 312 and the V-shaped structure reflecting surface can be respectively disposed on opposite sides of the component body 311. In some embodiments, the backlight element 200 and the bottom surface of the body 311 are disposed on the backplane of the backlight module, and in some embodiments, further include a PCB board on which the backlight component 200 is mounted, the PCB board is fixed. On the backplane of the backlight module, the PCB board and the backlight element 200 together form a light bar, and the bottom surface of the body 311 is disposed on a side of the PCB board on which the backlight element 200 is disposed.

In some embodiments disclosed in the present application, the cross-sectional shape of the cavity formed by the recess 312 is not limited, and may be a vertical surface, or a bevel or an irregular curved surface; the bottom surface of the recess 312 (ie, when After the backlight element is placed in the recess, the surface of the recess opposite to the backlight element is a smooth convex surface 314, and the convex surface 314 is the plane of the bottom surface of the recess 312 from the bottom surface of the body 311. The distance is smaller than the distance between the surrounding area of the bottom surface of the groove 312 and the plane of the bottom surface of the body 311. The open line segments formed by connecting any two points on the convex surface 314 are all inside the body 311. According to the principle of the convex lens, the convex surface 314 has a converging effect on the backlight light emitted from the backlight element 200, and the backlight light having a larger emission angle can be concentrated near the apex of the V-shaped structure 313.

In some embodiments disclosed herein, the reflective surface of the component body 311 is comprised of an inverted tapered surface to which a reflective coating 315 is adhered. The backlight light emitted from the V-shaped structure through the convex surface 314 faces the tapered surface of the reflecting surface of the component body 311, and is reflected on the tapered surface to reach the reflecting member 320. The reflective coating 315 is coated with a reflective coating, which typically consists of a binder, a heat reflective pigment, a filler, and an adjuvant. In the present embodiment, the type and nature of the reflective coating are not specifically limited, and any of the existing coatings capable of efficiently reflecting sunlight may be used. In addition, in some embodiments, the centers of symmetry of the two planes are the same as the center of symmetry of the reflecting members, that is, both are centered on the center plane of the converging turning member 310 in the vertical direction. In some embodiments, the axis of symmetry of the tapered face, the axis of symmetry of the convex face, the axis of symmetry of the body, and the axis of symmetry of the converging steering member are the same axis that is perpendicular to the bottom surface.

In some embodiments disclosed herein, the reflective component 320 further includes a paraboloid 321 for reflecting the backlight, the paraboloid 321 may be formed of a white reflective material, such as a PC (polycarbonate) material; or a PMMA having a reflective coating on its surface. (polymethyl methacrylate) material. Taking the vertex of the paraboloid as the origin, the paraboloid satisfies the following relationship:

x ² =2py (1-1)

In the formula (1-1), p>0, the parabola focus position is: y=1/2p. The larger the p value, the larger the opening of the paraboloid and the higher the position of the focus. In some embodiments disclosed herein, the parabolic apex position may be set to coincide with the light exit surface 2100 (ie, the upper surface) of the backlight source 210, then u+v=1/2p.

In some embodiments disclosed herein, the focus of the paraboloid 321 may coincide with the apex of a V-like structure 313 (ie, a tapered surface). As shown in FIG. 4, the position of the focus of the paraboloid 321 satisfies the following relationship:

y=u+v (1-2)

In the formula (1-2), u is the distance from the surface of the backlight source 210 near the convex surface 314 to the apex of the convex surface 314, v is the distance from the vertex of the convex surface 314 to the apex of the V-like structure 313, and y is the parabola 321 focus is in the vertical direction. s position.

FIG. 5 is a schematic diagram of a parabolic reflection principle provided by some embodiments of the present disclosure. As shown in Fig. 5, according to the principle of collimation of the paraboloid, the light incident on the parallel axis is concentrated by the parabolic surface and then concentrated on the focal point of the paraboloid. According to the reversible principle of the optical path, after the light emitted by the parabolic focus is reflected on the paraboloid, the light will be emitted parallel to the axis.

FIG. 6 is a schematic diagram of an optical path of a backlight according to some embodiments of the present disclosure. As shown in Fig. 6, the backlight light emitted from the backlight element 200 can be concentrated near the apex of the V-shaped structure 313 after being concentrated by the convex surface 314 (as indicated by a broken circle in the figure). Since in some embodiments of the present disclosure, the focus of the paraboloid 321 coincides with the apex of the V-like structure 313, that is, the backlight light can be concentrated near the focus of the paraboloid 321 under the convergence of the convex surface 314. The backlight light near the focus is emitted to the reflective member 320 under the reflection of the V-like structure 313. According to the collimation principle of the above paraboloid, the backlight light emitted near the focus of the paraboloid 321 can be emitted at a small emission angle after being reflected by the reflection member 320. The backlight having a smaller emission angle can completely enter the corresponding quantum dot unit, thereby solving the problem of color purity degradation of the backlight and color crosstalk between the three primary color backlights.

It can be seen from the principle of collimation of the above paraboloid and the reversible principle of the optical path that the closer the backlight light is to the focus of the parabolic surface 321 , the closer the backlight light is to the parallel light after the reflection of the parabolic surface 321 , the more the collimation requirement is satisfied. Therefore, in some embodiments of the present disclosure, the convex surface 314 is set to be a spherical surface, and the radius of curvature of the convex surface 314 satisfies the single spherical refraction law, and the relationship is as follows:

In the formula (1-3), u is the distance from the surface of the backlight source 210 near the convex surface 314 to the apex of the convex surface 314, n is the refractive index of the convergence steering member 310, and v is the distance from the vertex of the convex surface 314 to the apex of the V-like structure 313. r is the radius of curvature of the convex surface 314.

By setting the above parameters according to the single spherical refraction law, the convergence effect of the convex surface 314 on the backlight light can be improved, so that the backlight light passing through the convex surface 314 is closest to the focus of the parabolic surface 321 to obtain a higher collimation backlight light.

FIG. 7 is a schematic structural diagram of another light emitting module according to some embodiments of the present disclosure. It can be seen from FIG. 7 that the difference from the above-mentioned light-emitting module shown in FIG. 4 is that the V-shaped structure 313 in the light-emitting module shown in FIG. 7 has two convex surfaces symmetrically disposed, and the surface of the V-like structure 313 does not need to be adhered. A reflective coating is attached, and the open line segments formed by any two points on the convex surface are inside, that is, outside the body. The remaining structure of the light-emitting module shown in FIG. 7 is similar to the light-emitting module shown in FIG. 4, and details are not described herein again.

Since the convex surface 314 has a converging effect on the backlight light, the backlight light passing through the convex surface 314 is concentrated near the apex of the V-like structure 313. In this case, if the emission angle of the backlight light is the same, the convex structure in the light-emitting module shown in FIG. 7 is easier to obtain a larger incident angle than the planar structure in the light-emitting module shown in FIG. 4, so that the illumination is in the V-like type. Most of the backlight light on the structure 313 is emitted in the form of reflections, so that it is not necessary to adhere the reflective coating on the surface of the V-like structure 313 to achieve reflection of backlight light. In addition, the stronger the convergence of the convex surface 314 to the backlight light, the closer the backlight light is to the apex of the V-like structure, and the greater the slope of the V-like structure, the more the backlight light is more likely to reflect and reach the reflective member 320. Therefore, parameters such as the distance, the refractive index of the convergence steering member 310, and the radius of curvature of the convex surface 314 can be set according to the above single spherical refractive law to maximize the convergence of the convex surface 314 to the backlight.

FIG. 8 is a schematic diagram of an optical path of a backlight according to some embodiments of the present disclosure. As shown in FIG. 8, the backlight light emitted from the backlight element 200 can be concentrated near the apex of the V-shaped structure 313 after being concentrated by the convex surface 314 (shown by a broken circle in the figure). In some embodiments of the present disclosure, since the focus of the paraboloid 321 coincides with the apex of the V-like structure 313, that is, the backlight light can be concentrated near the focus of the paraboloid 321 under the convergence of the convex surface 314. The backlight light near the focus is emitted to the reflective member 320 under the reflection of the V-like structure 313. According to the collimation principle of the above paraboloid, the backlight light emitted near the focus of the paraboloid 321 can be emitted at a small emission angle after being reflected by the reflection member 320. Thus, the backlighting light passing through the light collimating structure 300 can achieve the desired collimation requirements, thereby avoiding the pixel color purity degradation and the color crosstalk between the three primary color backlights.

In some embodiments of the present disclosure, in order to improve the utilization of the backlight, the backlight light incident on the V-like structure 313 should be emitted as much as possible in the form of emission. Therefore, in some embodiments of the present disclosure, the V can be adjusted. The slope of the tangent of the pattern 313 changes the angle of incidence of the backlight light on the V-like structure 313 such that the angle of incidence satisfies the following relationship:

In the formula (2-1), θ is the incident angle of the backlight light on the V-like structure, and n is the refractive index of the convergence steering member. The backlight light that satisfies the above incident angle can be totally reflected on the V-like structure 313, so that the backlight received by the V-like structure 313 is totally reflected to the reflective member 320, thereby obtaining maximum light energy utilization.

The present disclosure also provides a liquid crystal display device. FIG. 9 is a schematic structural diagram of a liquid crystal display device according to an embodiment of the present disclosure. As can be seen from FIG. 9, the device includes a liquid crystal panel 500 and a backlight module 400 of any of the above. The liquid crystal panel 500 includes a liquid crystal layer 510 and a quantum dot color conversion layer 520 disposed between the backlight module 400 and the quantum dot color conversion layer 520. The liquid crystal layer 510 includes a plurality of liquid crystal cells 511 arranged in order. The quantum dot color conversion layer 520 includes a plurality of quantum dot conversion groups 521 arranged in order, and the quantum dot conversion group 521 includes quantum dot units 5211 that can convert the backlight correspondingly into three primary colors, and the quantum dot cells 5211 are disposed corresponding to the liquid crystal cells 511.

The present disclosure provides a backlight module and a corresponding liquid crystal display device. The backlight module is provided with a light collimating structure, and the light collimating structure comprises a converging steering component and a reflecting component disposed around the converging steering component. The two opposite faces of the convergence steering member are respectively disposed as a convex structure and a reflective surface. The reflective component includes a paraboloid for reflecting the backlight. The backlight light emitted by the backlight element can be concentrated near the focus of the paraboloid by the convergence of the convex structure, and is emitted to the reflective member under the reflection of the reflective surface. According to the principle of collimation of the paraboloid and the principle of reversibility of the optical path, the backlight light emitted near the focus of the paraboloid can be emitted at a small emission angle after being reflected by the reflecting member. A backlight with a smaller emission angle can completely enter the corresponding quantum dot unit, which can solve the problem of color purity degradation of the backlight and color crosstalk between the three primary color backlights.

The same and similar parts between the various embodiments in this specification can be referred to each other. The embodiments of the present disclosure described above are not intended to limit the scope of the disclosure.

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

The above is only the specific embodiment of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the disclosure. It should be covered within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be determined by the scope of the claims.

Claims

A backlight module includes: a plurality of light emitting modules, each of the plurality of light emitting modules includes a backlight element and a light collimating structure corresponding to the backlight element, the backlight element including at least one backlight a light source, the light collimating structure comprising a convergence steering member and a reflective member, wherein

The converging steering member includes a light transmissive component body, and a surface of the body remote from the at least one backlight source includes a reflective surface, the reflective surface is configured to direct at least a portion of the light emitted by the at least one backlight source The plane reflection of the backlight element;

The reflective member is disposed around the converging steering member, and the reflective member includes a curved surface for reflecting light reflected by the reflective surface.
The backlight module of claim 1 , wherein the reflective surface is disposed on a top surface of the component body, and a bottom surface of the component body is a surface of the component body opposite to the top surface, A groove is provided on the bottom surface, the backlight element is located in the groove, and the bottom surface of the groove includes a convex surface.
The backlight module of claim 1, wherein the curved surface on the reflective member is a paraboloid.
The backlight module of claim 1 , wherein the light emitting surfaces of the plurality of light emitting modules face in the same direction.
The backlight module of claim 1, wherein the reflective surface of the component body comprises an inverted tapered surface to which a reflective coating is adhered.
The backlight module of claim 1 , wherein the reflective surface is a free curved surface, and the free curved surface is centrally symmetrical, and when the slope of the surface tangent on one side of the free curved surface is a negative value, the free curved surface The slope of the surface tangent to the other side of the free-form surface that is symmetrical on one side is a positive value.
The backlight module of claim 2, wherein the convex surface of the component body is a part of a spherical surface.
The backlight module of claim 7, wherein a radius of curvature of the convex surface of the component body satisfies the following relationship:

Where u is the distance from the surface of the convex light source close to the convex surface of the component body to the apex of the convex surface, n is the refractive index of the convergence steering member, and v is the convex vertex of the component body to the component body The distance from the apex of the reflecting surface, r is the radius of curvature of the convex surface.
The backlight module of claim 1, wherein an incident angle of the backlight light on the reflective surface of the component body satisfies the following relationship:

Where θ is the incident angle of the backlight light on the reflecting surface of the component body, and n is the refractive index of the converging turning component.
The backlight module of claim 1, wherein the at least one backlight source comprises a backlight source.
The backlight module of claim 1, wherein the light collimating structure is a circumferentially symmetrical structure or a square structure.
The backlight module of claim 3, wherein the apex of the paraboloid is located on a light exit surface of the at least one backlight source.
The backlight module of claim 3, wherein the position of the focus of the paraboloid satisfies the following relationship:

y=u+v

Where u is the distance from the surface of the backlight source close to the convex surface to the apex of the convex surface, v is the distance from the vertex of the convex surface to the apex of the tapered surface, and y is the focal point of the paraboloid is vertical a position in the direction of the backlight module.
The backlight module according to any one of claims 1 to 12, wherein if the vertex of the paraboloid is taken as a coordinate origin, the paraboloid satisfies the following relationship:

x 2 =2py

Where p>0.
A liquid crystal display device comprising the backlight module and the liquid crystal panel according to any one of claims 1 to 14, wherein

The liquid crystal panel includes a liquid crystal layer and a quantum dot color conversion layer, and the liquid crystal layer is disposed between the backlight module and the quantum dot color conversion layer;

The liquid crystal layer includes a plurality of liquid crystal cells, and the quantum dot color conversion layer includes a plurality of quantum dot units, and the plurality of quantum dot units are disposed corresponding to the plurality of liquid crystal cells.