WO2021057750A1

WO2021057750A1 - Backlight module and display device

Info

Publication number: WO2021057750A1
Application number: PCT/CN2020/116956
Authority: WO
Inventors: 刘欣; 尤君平
Original assignee: 深圳创维－Rgb电子有限公司
Priority date: 2019-09-24
Filing date: 2020-09-23
Publication date: 2021-04-01
Also published as: CN110609418A

Abstract

Provided in the present disclosure are a backlight module and a display device. The backlight module comprises a Mini LED lamp board and a light guiding body provided above the Mini LED lamp board; the light guiding body has an inverted trapezoidal cross section, a microstructure array is provided on a side wall of the light guiding body and/or the bottom surface of the light guiding body, and a reflective film is adhered to the surface of the side wall of the light guiding body. The backlight module of the present disclosure uses a light guiding body having an inverted trapezoidal cross section to guide light, the inverted trapezoidal light guiding body can convert a point light source emitted by the Mini LED into a surface light source, the microstructure array is arranged on the bottom surface and/or the side wall of the light guiding body, and the microstructure array can enhance the scattering of light inside the light guiding body, so that the light inside the light guiding body is mostly emitted from the top surface. A backlight assembly of the present disclosure can form a whole large-size light exiting surface by assembling a plurality of light guiding bodies, thereby having a uniform light emission and a good backlight effect.

Description

Backlight module and display equipment

Technical field

The present disclosure relates to the technical field of display devices, for example, to a backlight module and a display device.

Background technique

Mini LED chip is an LED chip with a chip size of about 100μm×100μm. It has the advantages of high color saturation, local dimming, high brightness, and energy saving. It can be applied to backlight displays and has become a recent research hotspot.

Referring to Fig. 1, an existing Mini LED backlight display structure includes a backplane frame 10, a plurality of Mini LED light panels 20 are arranged side by side inside the backplane frame, and a support frame 30 is provided above the Mini LED light panels. The diffuser 40 and the diaphragm 50, the existing Mini LED backlight display structure has the following defects: (1) There are splicing gaps between the Mini LED lamp panels, and grid patterns are prone to appear in visual effects; (2) due to light mixing The distance is small, the support frame will have a serious support shadow on the diffuser; (3) There is light energy crosstalk between the Mini LED lamp panels, the existing Mini LED backlight display structure design is unreasonable, and the backlight display effect is not good.

Therefore, the existing technology needs to be improved.

Summary of the invention

In view of the above-mentioned shortcomings of the prior art, the purpose of the present disclosure is to provide a backlight module and a display device, which aims to solve the technical problems of unreasonable design of the existing Mini LED backlight display structure and poor backlight display effect.

The technical solutions of the present disclosure are as follows:

A backlight module, which includes a Mini LED light board, and a light guide body arranged above the Mini LED light board, the cross section of the light guide body is an inverted trapezoid, and the side walls of the light guide body and/ Or the bottom surface of the light guide body is provided with a microstructure array, and the side wall surface of the light guide body is pasted with a reflective film.

Optionally, the microstructure array is composed of a number of pits, and the shape of the pits is any one of a cone shape, a hemispherical shape, and a quadric shape.

Optionally, the backlight module, wherein the microstructure array includes a plurality of hemispherical pits, and on the sidewall of the light guide, the arrangement density of the pits varies from bottom to top. The Gaussian curve changes from small to large.

Optionally, the backlight module, wherein the top surface of the light guide body is a rough surface or the top surface of the light guide body is sprayed with PMMA particles.

Optionally, in the backlight module, each of the plurality of pits is arranged in a hexagonal shape with the surrounding pits.

Optionally, the backlight module, wherein the density of the pits is

among them,

Is the diameter of the pit, and x and y are the distance between adjacent horizontal rows and the distance between adjacent vertical rows, respectively.

Optionally, in the backlight module, the Mini LED lamp board includes a PCB board and a number of LED lamp beads arranged on the PCB board, and a number of circuit loops are printed on the PCB board. Each of the LED lamp beads is connected to one of the circuit loops.

Optionally, the backlight module, wherein a spacer block is provided on the PCB board, the height of the spacer block is higher than the height of the LED lamp bead, and the bottom surface of the light guide is connected to the spacer The top of the block is glued together.

Optionally, in the backlight module, the Mini LED light board is packaged with flip-chip Mini LED chips.

Optionally, in the backlight module, the top of the side wall of the light guide is provided with a vertical surface that facilitates the mutual splicing of a plurality of the light guides.

Optionally, in the backlight module, the light guide is an optical resin light guide.

Optionally, in the backlight module, the light guide body is in the shape of a prism frustum or a truncated frustum.

Optionally, in the backlight module, the light guide body has a quadrangular pyramid shape.

Optionally, in the backlight module, the reflective film is a silver reflective film.

A display device, which includes the aforementioned backlight module.

Beneficial effects: The present disclosure provides a backlight module and a display device, wherein the backlight module includes a Mini LED light board, and a light guide body arranged above the Mini LED light board. The cross section is an inverted trapezoid, the side wall of the light guide body and/or the bottom surface of the light guide body is provided with a microstructure array, and the side wall surface of the light guide body is pasted with a reflective film. Since the backlight module of the present disclosure adopts a light guide with an inverted trapezoidal cross-section to guide light, the inverted trapezoidal light guide can convert the point light source emitted by the Mini LED into a surface light source, and the light guide is on the bottom surface and/or The sidewall is provided with a microstructure array. The microstructure array can enhance the scattering of light inside the light guide, so that more light inside the light guide is emitted from the top surface. The backlight assembly of the present disclosure can be formed by splicing multiple light guides. The entire large-size light-emitting surface provides more uniform light output and better backlight effect.

Description of the drawings

FIG. 1 is a schematic diagram of the structure of a conventional backlight module;

2 is a schematic diagram of the structure of a backlight module of the present disclosure;

FIG. 3 is a schematic diagram of the change of a Gaussian curve of the disclosure;

4 is a schematic diagram of the definition of the density of pits (light guide dots) in the present disclosure;

FIG. 5 is a schematic diagram of a usage scenario of a backlight module of the present disclosure.

detailed description

The present disclosure provides a backlight module and a display device. In order to make the objectives, technical solutions, and effects of the present disclosure clearer and clearer, the present disclosure will be described in further detail below. It should be understood that the specific embodiments described here are only used to explain the present disclosure, but not used to limit the present disclosure.

Example 1

Referring to FIG. 2, the present disclosure provides a backlight module, including a Mini LED light board 60, and a light guide 70 disposed above the Mini LED light board. The light guide has an inverted trapezoid in cross section. The side wall of the light body and/or the bottom surface of the light guide body is provided with a microstructure array 80, and the surface of the side wall of the light guide body is pasted with a reflective film 90. Specifically, the purpose of the technical solution of the present disclosure is to provide a Mini LED backlight module structure that is different from the prior art. The Mini LED backlight module structure can realize ultra-high brightness and ultra-high color gamut display backlights, and solve the traditional Mini LED backlight module is a technical problem with poor backlight display effect.

In one case, the inverted trapezoidal light guide in the technical solution of the present disclosure can be cut into an isosceles trapezoid or a right-angled trapezoid from any light guide plate (acrylic board, PC board or PS board) in the prior art. The light guide plate has a very high refractive index (refractive index can be selected 1.5), and a microstructure array is arranged on the bottom surface of the light guide. The microstructure array is mainly composed of a number of light guide dots (pits), and the shape of the light guide dots is cone Shape, hemispherical or quadric shape, etc., and can be made by processing methods such as hot pressing, laser engraving or screen printing. The light emitted by the Mini LED lamp is in contact with the light guide mesh points in the microstructure array on the bottom surface of the light guide. Then it can diffuse to all angles. The microstructure array improves the absorption rate of the light emitted from the Mini LED lamp on the bottom of the light guide. In addition, due to the total reflection on the top surface of the light guide, in order to allow more internal light to emerge, The side wall of the light guide can also be provided with a microstructure array to enhance the scattering of light by the side wall of the light guide, and a reflective film is attached to the surface of the side wall of the light guide to prevent light leakage.

In a specific embodiment, the microstructure array includes a plurality of hemispherical pits, and on the sidewall of the light guide, the arrangement density of the pits increases from the bottom to the top according to the Gaussian curve. To a big change.

In the technical solution of the present disclosure, the arrangement of the microstructure arrays on the sidewall of the light guide and the bottom surface of the light guide may be different. Specifically, the specifications of the pits (light guide dots) on the bottom surface (light incident surface) of the light guide are the same, and Evenly arranged, for example, the diameter of the light guide dots can be 50μm, and the spacing between the light guide dots can be set to 60μm. The specific function of the light guide dots on the bottom surface of the light guide is to scatter the incident light and diverge the incident light from the Mini LED. The angle is expanded from 120° to about 150°, and the light that is totally reflected by the top surface of the light guide body and returned to the light incident surface is reflected and scattered.

The density of pits at the top of the side wall of the light guide should be higher than the density of pits at the bottom of the side wall of the light guide, because the light density inside the light guide will be lower along the side wall, in order to prevent obvious light and shade. Change, balance the difference of light and darkness by controlling the density of pits from the top to the bottom of the side wall to affect the scattering intensity of light. Specifically, the density of the pits on the side wall of the light guide body from the bottom of the side wall to the top of the side wall is as shown in the figure The Gaussian curve (normal distribution) of 3 changes from small to large, and the overall trend law of the change of pit density conforms to the formula ρ=M*X^A, where M and A are constants, which together affect the curvature value of the dot density distribution curve. The values of M and A can be adjusted according to the actual optical performance that needs to be achieved. Under this kind of Gaussian curve change trend, the light emitted from the surface of the light guide can be more uniform. See Figure 4, where each pit is equal to The surrounding pits are arranged in a hexagonal shape, and the pit density can be defined as

Is the diameter of the pit, the minimum diameter of the pit on the side wall is 100μm, x, y are the distance between adjacent horizontal rows and the distance between adjacent vertical rows, in one case, x, The size of y can also be equal. In addition, because the end of the side wall is prone to excessive or weak energy, the end density distribution can also be adjusted locally. The overall function of the microstructure array provided on the light guide of the present disclosure is The secondary light distribution is carried out for the total reflected light inside the light guide, so that the light energy can reach the corner area and exit from the top light emitting surface, and make its divergence more uniform.

In a specific embodiment, the top surface of the light guide is a rough surface or the top surface of the light guide is sprayed with PMMA particles. In order to enhance the scattering of the emitted light from the top surface of the light guide and improve the efficiency of light emission, the top surface of the light guide can be roughened. For example, a suede structure can be formed on the top surface of the light guide to improve light scattering. In one case, a scattering layer can be sprayed on the surface of the light guide. The scattering layer is mainly composed of PMMA particles and OCA optical glue. The thickness of the scattering layer should be uniform. For example, the thickness of the scattering layer can be set to 0.1mm to achieve Very good light scattering effect.

Example 2

1, in a specific embodiment, the Mini LED light board includes a PCB board 100 and a number of LED lamp beads 110 arranged on the PCB board, and a number of circuit circuits are printed on the PCB board. , Each of the LED lamp beads is connected to one of the circuit loops.

Specifically, in this technical solution, each LED lamp bead is controlled by a separate circuit loop, that is, the Mini LED backlight of the present disclosure can be combined with Local Dimming technology to control in real time according to the bright and dark fields of the screen in the TV signal. The switch and brightness adjustment corresponding to the backlight area can make the black blacker, whiter whiter, and more natural and beautiful in the picture. The visual fidelity brings the best immersive experience. In the specific setting, all circuit loops can be used. It is connected to a power management chip or the pins of multiple power management chips in groups to realize the individual control of each LED lamp bead. The power management chip can use HIP6301, IS6537 or RT9237 power management chips.

More specifically, the Mini LED package of the technical solution of the present disclosure can also use flip-chip Mini LED chips to achieve uniform light mixing. Since the flip-chip Mini LED chip itself has a small structure, it is beneficial to make the local dimming zones more detailed. , So as to achieve a higher dynamic range (HDR) and achieve a higher contrast effect. On the other hand, it can also shorten the optical mixing distance (OD) to reduce the thickness of the whole machine to achieve the purpose of ultra-thinness.

In addition, the backlight module adopting the Mini LED light board of the present disclosure can be used for AIOT screen display. The specific application scenarios are: when R, G, B LEDs are all on and Mini LED light boards are all running, the backlight only provides full White field, the display terminal is in the normal viewing mode. The R, G, and B three-color lights on the Mini LED light board can be designed as single-channel control, and each Mini LED light board can achieve single-channel control, which can be achieved through power control. Multiple combined screen display modes with multiple colors and multiple partitions. This mode can be used to respond to multiple AIOT intelligent commands and display AIOT functions on the screen.

1, in a specific embodiment, the PCB board is provided with a spacer block 120, the height of the spacer block is higher than the height of the LED lamp beads, the bottom surface of the light guide and the The top of the spacer is glued together. Specifically, the spacer is fixed on the PCB by means of a patch. The material of the spacer can be PC or metal. The height of the spacer should be 0.2-0.4mm higher than the height of the LED lamp bead during the specific setting. The function of the spacer is mainly Isolate the light guide and the Mini LED to avoid direct contact and extrusion between the two. At the same time, the gap between the light guide and the Mini LED facilitates the heat dissipation of the Mini LED, thereby prolonging the service life of the Mini LED.

Referring to FIG. 1, in a specific embodiment, the top of the side wall of the light guide is provided with a vertical surface 130 that facilitates the mutual splicing of a plurality of the light guides. Specifically, referring to FIG. 5, when the backlight module of the present disclosure is applied to a large-area backlight display, a large light-emitting surface can be formed by splicing. The vertical surface is provided, and the vertical surface can facilitate the splicing and contact between the side walls of the light guides, reduce the gap between the light guides after splicing, and make the light guides more compact and the light output more uniform. The R, G, and B three-color light emitted by the LED light board is mixed into white light in the light guide body, and is emitted from the top light emitting surface under the action of the light guide dots on the side wall to form a uniform light output. Several light guide bodies are spliced to form one With a complete direct-lit backlight light-emitting surface, the technical solution of the present disclosure can effectively solve the problems of splicing seams and bracket shadows in traditional Mini LED backlights, and can achieve ultra-high color gamut indicators, ultra-high brightness indicators and precise regional dimming functions , And can save the cost of diffuser and diaphragm, optimize the backlight structure, and highlight the cost-reducing effect.

In a specific embodiment, the light guide is an optical resin material light guide. Optical resin materials are optical resins made of high molecular organic compounds by compression molding or injection molding. Commonly used optical resin materials are propylene diethylene glycol carbonate (CR-39), polymethyl methacrylate (PMMA) and Polycarbonate (PC), the role of the light guide in the technical solution of the present disclosure is to expand the point light source into a surface light source. Specifically, the light guide of the present disclosure can be made of polymethyl methacrylate (PMMA) material , The refractive index of polymethyl methacrylate is 1.49, the light can be totally reflected inside the light guide, and its light transmittance can reach 92%. It is light in weight and high in hardness. It is very suitable for use as a light guide. material.

In a specific embodiment, the light guide has a prism frustum shape or a truncated frustum shape. The light guide used in the technical solution of the present disclosure includes, but is not limited to, a prism frustum shape or a truncated frustum shape. When the light guide body is a prism frustum shape, it can be specifically selected as a quadrangular prism frustum shape, and the cross section of the quadrangular prism frustum is an isosceles trapezoid. The four sides of the mesa are flat, which reduces the difficulty of processing. In addition, the inclination angle of the hypotenuse of the isosceles trapezoid with respect to the bottom surface can be selected to be 30°. At this time, the interior of the isosceles trapezoid has sufficient light mixing distance. At the same time, The thickness of the isosceles trapezoid can be made thinner, which indirectly makes display devices such as televisions thinner, and significantly improves the appearance design of the display device.

In a specific embodiment, the reflective film is a silver reflective film. The silver reflective film can reflect most of the light emitted from the side of the light guide, thereby increasing the luminous flux emitted from the top of the light guide, reducing light leakage from the side, and improving the brightness of the entire backlight assembly. In specific implementation, the reflective film in the present disclosure can be any metal reflective film. The metal reflective film is used because generally metals have a large extinction coefficient. When the light beam is incident on the metal surface from the air, it enters the metal. The light amplitude inside the metal decays rapidly, so that the light energy entering the metal decreases correspondingly, while the reflected light energy increases. The greater the extinction coefficient, the faster the light amplitude decays, the less light energy entering the metal, the higher the reflectivity, and the metal The reflective film also has the advantages of simple preparation process and wide working wavelength range.

Example 3

In addition, the present disclosure also provides a display device including the above-mentioned backlight module. What this disclosure actually discloses is a Mini LED backlight module suitable for AIOT screen display. This module is suitable for the ultra-thin direct backlight design of LCD screens and TV display devices. The light source uses R, G, Mini LED light board with B three-color LED, R, G, B three-color LED can realize single-channel control through circuit design, and Mini LED adopts single-channel control, which can realize multi-color, multi-partition combined screen display mode , The point light source of Mini LED is converted into a uniform surface light source through the light guide body, and then multiple light guide bodies are seamlessly spliced to achieve high image quality and multi-zone light emitting surface. This backlight design solution can support the viewing function of ordinary flat-screen TVs, and It can realize AIOT intelligent command screen display and diversification, highlighting the advanced nature.

In summary, the present disclosure provides a backlight module and a display device, wherein the backlight module includes a Mini LED light board, and a light guide body arranged above the Mini LED light board, and the light guide The cross section of the body is an inverted trapezoid, the side wall of the light guide body and/or the bottom surface of the light guide body is provided with a microstructure array, and the side wall surface of the light guide body is pasted with a reflective film. Since the backlight module of the present disclosure uses a light guide with an inverted trapezoidal cross-section to guide light, the inverted trapezoidal light guide can convert the point light source emitted by the Mini LED into a surface light source. The wall is arranged with a microstructure array, which can enhance the scattering of light inside the light guide, so that more light inside the light guide is emitted from the top surface. The backlight assembly of the present disclosure can be formed by splicing the light guide to form a whole The large-sized light-emitting surface makes the light output more uniform and the backlight effect is better.

It should be understood that the application of the present disclosure is not limited to the above examples, and those of ordinary skill in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present disclosure.

Claims

A backlight module, characterized in that it comprises a Mini LED light board and a light guide body arranged above the Mini LED light board, the cross section of the light guide body is inverted trapezoid, and the side walls of the light guide body And/or the bottom surface of the light guide is provided with a microstructure array, and the sidewall surface of the light guide is pasted with a reflective film.
The backlight module of claim 1, wherein the microstructure array is composed of a plurality of pits, and the shape of the pits is any one of a cone shape, a hemispherical shape, and a quadric shape.
The backlight module according to claim 2, wherein the microstructure array comprises a plurality of hemispherical pits, and on the sidewall of the light guide, the arrangement density of the pits is from the bottom to The top changes from small to large according to the Gaussian curve.
3. The backlight module of claim 2, wherein each of the plurality of pits is arranged in a hexagonal shape with the surrounding pits.
The backlight module of claim 4, wherein the density of the pits is

among them,
Is the diameter of the pit, and x and y are the distance between adjacent horizontal rows and the distance between adjacent vertical rows, respectively.
The backlight module of claim 1 or 3, wherein the top surface of the light guide is a rough surface or the top surface of the light guide is sprayed with PMMA particles.
The backlight module according to claim 1, wherein the Mini LED lamp board comprises a PCB board and a number of LED lamp beads arranged on the PCB board, and a number of circuit circuits are printed on the PCB board , Each of the LED lamp beads is connected to one of the circuit loops.
The backlight module according to claim 7, wherein the PCB board is provided with a spacer block, the height of the spacer block is higher than the height of the LED lamp bead, and the bottom surface of the light guide body is The top end of the spacer block is glued together.
The backlight module of claim 7, wherein the Mini LED lamp panel is packaged with flip-chip Mini LED chips.
The backlight module according to claim 1, wherein the top of the side wall of the light guide is provided with a vertical surface that facilitates the mutual splicing of a plurality of the light guides.
The backlight module of claim 1, wherein the light guide is an optical resin light guide.
11. The backlight module of claim 11, wherein the light guide body is in the shape of a prism frustum or a truncated frustum.
The backlight module of claim 12, wherein the light guide body is in the shape of a quadrangular pyramid.
The backlight module of claim 1, wherein the reflective film is a silver reflective film.
A display device, characterized by comprising the backlight module of any one of claims 1-14.