CN114089561A

CN114089561A - Display device

Info

Publication number: CN114089561A
Application number: CN202010855892.9A
Authority: CN
Inventors: 李富琳; 张楠楠; 乔明胜
Original assignee: Hisense Visual Technology Co Ltd
Current assignee: Hisense Visual Technology Co Ltd
Priority date: 2020-08-24
Filing date: 2020-08-24
Publication date: 2022-02-25

Abstract

The invention discloses a display device, comprising: a display panel for image display; the miniature light-emitting diode lamp panel is positioned at the light incident side of the display panel; the functional layer is positioned on the light emitting side of the miniature light emitting diode lamp panel, and the reflectivity of the functional layer to incident light is reduced along with the increase of the angle of the incident light; the miniature LED lamp plate includes: the micro light-emitting diode is used as a backlight source; the light homogenizing component is positioned on the light emitting side of the micro light emitting diode and is used for homogenizing the emergent light of the micro light emitting diode. The light homogenizing component homogenizes the light emitted by the micro light-emitting diode, and reduces the energy difference between the small-angle range and the large-angle range emitted by the micro light-emitting diode. The homogenized light can be incident into the functional layer, the functional layer further homogenizes emergent light, and finally the emergent light of the backlight module is more uniform.

Description

Display device

Technical Field

The invention relates to the technical field of display, in particular to a display device.

Background

The liquid crystal display screen has the advantages of low power consumption, small volume, low radiation and the like as the current mainstream display screen. The liquid crystal display panel is a non-self-luminous panel and needs to be matched with a backlight module for use.

The existing direct type backlight module usually adopts Light Emitting Diodes (LEDs) as backlight source, and has the advantages of high backlight brightness, no reduction of brightness even after long-term use, and the like. The backlight module is usually provided with a diffusion plate for homogenizing light, and the ratio H/P of the distance H from the light source to the diffusion plate to the distance P between two adjacent light sources can usually represent the performance of the backlight module.

In order to ensure the uniformity of the light output of the backlight module, the H/P value generally needs to be above 0.6, which makes the backlight module unable to have a smaller thickness and uses a larger number of light sources, which is not favorable for realizing a thin backlight module and controlling the cost.

Disclosure of Invention

In some embodiments of the invention, the light-homogenizing part is arranged on the light-emitting side of the micro light-emitting diode to homogenize the light emitted by the micro light-emitting diode, so that the energy difference between the small-angle range and the large-angle range emitted by the micro light-emitting diode is reduced. The homogenized light can enter the functional layer, and the reflectivity of the functional layer to the incident light is reduced along with the increase of the angle of the incident light. Most of the low-angle light rays incident to the functional layer will be reflected by the functional layer, and most of the high-angle light rays incident to the functional layer will be transmitted by the functional layer. The reflected small-angle light rays enter the reflective layer again, enter the functional layer again after the diffuse reflection effect of the reflective layer, and finally are further homogenized after being reflected for multiple times between the functional layer and the reflective layer.

In some embodiments of the invention, the homogenization of the emergent light of the micro light-emitting diode by the light homogenizing component and the functional layer can enable the vertical distance from the lamp panel of the micro light-emitting diode to the diffusion layer and the distance between two adjacent micro light-emitting diodes to satisfy the following relations:

H/P≤0.2；

wherein, H represents the vertical distance of miniature emitting diode lamp plate to the diffusion layer, and P represents the interval between two adjacent miniature emitting diode.

The backlight module combines the structure of the dodging component and the functional layer, so that the H/P ratio can be controlled below 0.2, the backlight module can have smaller thickness, the design of the display device is light and thin, the use number of the micro light-emitting diodes is reduced, and the production cost is reduced.

In some embodiments of the present invention, the light uniformizing member is a lens located on the light emitting side of the micro light emitting diode, and the surface shapes of the light incident surface and the light emergent surface of the lens are reasonably designed, so that the emergent light of the light emitting diode can be firstly incident on the lens, the light field distribution of the transmitted light is adjusted, and the light intensity directly above the micro light emitting diode is relatively homogenized with the light intensity located at the junction position of the adjacent micro light emitting diode.

In some embodiments of the present invention, the light uniformizing member is a semi-transparent semi-reflective layer located at the light exit side of the micro light emitting diode, and the semi-transparent semi-reflective layer transmits part of the light rays when receiving the light rays exiting from the micro light emitting diode, and reflects the rest of the light rays, and the reflected light rays enter the reflective layer again, and exit to one side of the functional layer after being subjected to the diffuse reflection action of the reflective layer. The semi-transparent and semi-reflective layer is arranged on the light emitting side of the micro light emitting diode, so that the intensity of emergent light above the micro light emitting diode can be reduced, light can be distributed towards an area far away from the area above the micro light emitting diode, and the relative homogenization of the emergent light of the micro light emitting diode is realized.

In some embodiments of the present invention, the semi-transparent and semi-reflective layer is located on the light emitting surface of the micro light emitting diode, and the light emitted from the micro light emitting diode to the right above is subjected to the action of the semi-transparent and semi-reflective layer, so that the light intensity of the emitted light is relatively uniform after the light is reflected by the semi-transparent and semi-reflective layer and the reflective layer.

In some embodiments of the present invention, a protective layer is disposed on a surface of the micro light emitting diode, and the semi-transparent and semi-reflective layer is disposed on a surface of the protective layer facing away from a side of the micro light emitting diode. The protective layer makes a certain distance between the semi-transparent semi-reflecting layer and the micro light-emitting diode. The light emitted by the micro light-emitting diode enters the semi-transparent and semi-reflective layer after a certain distance, and when the light reflected by the semi-transparent and semi-reflective layer enters the reflective layer to be reflected again, the path of the reflected light is increased, and the light can be reflected to a farther area, so that the light emitted by the micro light-emitting diode right above can be favorably converted to the junction position of the adjacent micro light-emitting diode, and the homogenization of the light emitted by the micro light-emitting diode is realized.

In some embodiments of the present invention, the functional layer includes a plurality of film layers arranged in a stacked manner, the refractive indexes of two adjacent film layers are not equal, and the refractive indexes and thicknesses of the film layers satisfy the condition of thin film interference.

In some embodiments of the present invention, the backlight module includes a wavelength conversion layer located on a side of the functional layer and the diffusion layer away from the micro light emitting diode lamp panel, and the wavelength conversion layer is configured to emit light of other colors under excitation of excitation light emitted from the micro light emitting diode lamp panel.

In some embodiments of the present invention, the wavelength conversion layer is a quantum dot layer or a fluorescent layer.

In some embodiments of the present invention, the functional layer may be disposed on a side of the diffusion layer facing away from the wavelength conversion layer. The functional layer is arranged on one side close to the miniature light-emitting diode lamp panel, so that light emitted by the miniature light-emitting diode lamp panel can directly enter the functional layer firstly. The functional layer can further homogenize the light of the micro light-emitting diode after being diffused by the light homogenizing component, and the homogenizing effect is good.

In some embodiments of the invention, the functional layer may be disposed on a side of the diffusion layer away from the panel of the micro light emitting diode. In order to avoid the bracket from puncturing or scratching the functional layer, the functional layer can be arranged on one side of the diffusion layer deviating from the miniature light-emitting diode lamp panel. The diffusion layer may function to protect and support the functional layer.

In some embodiments of the present invention, the backlight module further comprises: the transparent substrate is positioned on one side, facing the micro light-emitting diode lamp panel, of the diffusion layer, and the functional layer is positioned between the diffusion layer and the transparent substrate. The transparent substrate is arranged between the functional layer and the support, so that the tip of the support can be prevented from directly contacting the functional layer, and the functional layer can be prevented from being damaged and scratched. Meanwhile, the transparent substrate can also play a role in supporting the functional layer and the diffusion layer, so that the two sides of the functional layer are supported by plates, and the reliability is higher.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic cross-sectional structure diagram of a display device according to an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of a backlight module according to an embodiment of the invention;

FIG. 3 is a second schematic cross-sectional view illustrating a backlight module according to an embodiment of the present invention;

fig. 4 is a third schematic cross-sectional view illustrating a backlight module according to an embodiment of the invention;

FIG. 5 is a functional layer diagram according to an embodiment of the present invention;

FIG. 6 is a fourth schematic cross-sectional view of a backlight module according to an embodiment of the present invention;

FIG. 7 is a fifth schematic cross-sectional view illustrating a backlight module according to an embodiment of the present invention;

FIG. 8 is a sixth schematic cross-sectional view of a backlight module according to an embodiment of the present invention;

FIG. 9 is a diagram illustrating the distribution effect of the light intensity of the backlight module in the prior art;

fig. 10 is a diagram illustrating an effect of light intensity distribution of the backlight module according to the embodiment of the invention.

The backlight module comprises a backlight module 100, a display panel 200, a backboard 11, a miniature light emitting diode lamp panel 12, a functional layer 13, a diffusion layer 14, an optical membrane 15, a wavelength conversion layer 16, a support 17, a transparent substrate 18, a circuit board 121, a miniature light emitting diode 122, a light reflecting layer 123, a light homogenizing component 124 and a protective layer 125.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, the present invention is further described with reference to the accompanying drawings and examples. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their repetitive description will be omitted. The words expressing the position and direction described in the present invention are illustrated in the accompanying drawings, but may be changed as required and still be within the scope of the present invention. The drawings of the present invention are for illustrative purposes only and do not represent true scale.

The liquid crystal display mainly comprises a backlight module and a liquid crystal display panel. The liquid crystal display panel does not emit light, and brightness display needs to be realized by a light source provided by the backlight module.

The display principle of the liquid crystal display is that liquid crystal is placed between two pieces of conductive glass, and the electric field effect of liquid crystal molecule distortion is caused by the driving of an electric field between two electrodes so as to control the transmission or shielding function of a backlight source, thereby displaying an image. If a color filter is added, a color image can be displayed.

Fig. 1 is a schematic cross-sectional structure diagram of a display device according to an embodiment of the present invention.

Referring to fig. 1, the display device includes: the backlight module 100 is used for providing backlight to the display panel 200, and the display panel 200 is used for displaying images.

The backlight module 100 is generally disposed at the bottom of the display device, and has a shape and size corresponding to those of the display device. When applied to the field of televisions or mobile terminals, the backlight module generally takes a rectangular shape.

The backlight module in the embodiment of the invention adopts the direct type backlight module, is used for uniformly emitting light rays in the whole light emitting surface, and provides light rays with sufficient brightness and uniform distribution for the display panel, so that the display panel can normally display images.

The display panel 200 is located at the light-emitting side of the backlight module 100, and the shape and size of the display panel are generally matched with those of the backlight module.

In general, the display panel 200 may be configured in a rectangular shape including a top side, a bottom side, a left side and a right side, wherein the top side is opposite to the bottom side, the left side is opposite to the right side, the top side is connected to one end of the left side and one side of the right side, and the bottom side is connected to the other end of the left side and the other end of the right side.

The display panel 200 is a transmissive display panel, which can modulate the transmittance of light, but does not emit light by itself.

The display panel 200 has a plurality of pixel units arranged in an array, and each pixel unit can independently control the transmittance and color of light incident to the pixel unit from the backlight module 100, so that the light transmitted by all the pixel units forms a displayed image.

Fig. 2 is a schematic cross-sectional structure view of a backlight module according to an embodiment of the invention.

Referring to fig. 2, the backlight assembly includes: the LED lamp comprises a back plate 11, a miniature LED lamp panel 12, a functional layer 13, a diffusion layer 14 and an optical diaphragm 15.

The back plate 11 is located at the bottom of the backlight module and has supporting and bearing functions.

The back plate 11 is typically a square or rectangular structure, the shape of which, when applied to a contoured display device, is adapted to the shape of the display device.

The back panel 11 includes a top side, a bottom side, a left side, and a right side. Wherein the antenna side is opposite to the ground side, the left side is opposite to the right side, the antenna side is connected with one end of the left side and one side of the right side respectively, and the ground side is connected with the other end of the left side and the other end of the right side respectively.

The material of the back plate 11 is aluminum, iron, aluminum alloy or iron alloy. The back plate 11 is used for fixing and supporting the edge positions of the optical film, the diffusion layer and other components, and the back plate 11 also plays a role in heat dissipation.

In the embodiment of the present invention, the backlight module is a direct type backlight module, and the micro led lamp panel 12 is located on the back plate 11.

The whole body of the micro light-emitting diode lamp panel 12 can be square or rectangular, the length is within the range of 200mm-800mm, and the width is within the range of 100mm-500 mm.

According to the size of the display device, a plurality of miniature light-emitting diode lamp panels 12 can be arranged, and backlight is provided between the miniature light-emitting diode lamp panels 12 in a splicing mode. In order to avoid the optical problem caused by splicing the miniature light-emitting diode lamp panels 12, the splicing seams between the adjacent miniature light-emitting diode lamp panels 12 are as small as possible, and even seamless splicing is realized.

The miniature light emitting diode is adopted as a backlight source in the miniature light emitting diode lamp panel 12, and compared with the traditional light emitting diode, the miniature light emitting diode lamp panel has a smaller size, can realize more refined dynamic control, and improves the dynamic contrast of the display device.

The functional layer 13 is located on the light emitting side of the micro led lamp panel 12, in the embodiment of the present invention, the functional layer 13 is disposed in a whole layer, and the shape of the functional layer 13 is the same as the whole shape of the micro led lamp panel 12, and may be generally set to be rectangular or in a rectangular manner. The functional layer 13 is dimensioned to the back plate 11.

The functional layer 13 is configured to reflect light rays in a first incident angle range and transmit light rays in a second incident angle range; and the incident angle value corresponding to the first incident angle range is smaller than the incident angle value corresponding to the second incident angle range.

The incident angle of the light entering the functional layer 13 is equal to the emergent angle of the light emitted from the micro light emitting diode 122, so the first incident angle range corresponds to the emergent angle range with larger emergent light intensity of the micro light emitting diode 122, and the second incident angle range corresponds to the emergent angle range with smaller emergent light intensity of the micro light emitting diode 122.

The functional layer 13 may be chosen to reflect light rays having a small angle of incidence and to transmit light rays having a large angle of incidence. Meanwhile, the light reflected by the functional layer 13 can be subjected to diffuse reflection by the reflective layer 123 on the miniature light-emitting diode lamp panel, and the reflected light enters the functional layer 13 again, so that the light at the second incident angle after diffuse reflection can be transmitted, and the light at the first incident angle continues to repeat the above reflection operation.

Through the reflection of the functional layer 13 and the reflective layer 123 on the light, the light intensity in the small angle range directly above the micro light emitting diode 122 can be finally weakened, and the light intensity in the large angle range of the micro light emitting diode 122 at the boundary position can be increased, so that the light of the micro light emitting diode 122 at each exit angle is relatively uniform, and the light-emitting uniformity of the micro light emitting diode lamp panel 12 is improved.

The diffusion layer 14 is located on the light-emitting side of the micro led lamp panel 12. The diffusion layer 14 is provided in a full layer. The diffusion layer 14 has the same shape as the functional layer 13, and may be generally provided in a rectangular or square shape. The diffusion layer 14 has the same size as the functional layer 13.

The purpose of the diffuser layer 14 is to scatter incident light, making the light passing through the diffuser layer 14 more uniform. The diffusion layer 14 is provided with scattering particle materials, and light incident to the scattering particle materials can be refracted and reflected continuously, so that the effect of scattering the light is achieved, and the effect of light homogenization is achieved.

The diffusion layer 14 may take the form of either a diffuser plate or a diffuser sheet. If the light source is applied to a large display device such as a television, a diffusion plate can be adopted; and when being applied to small-size display device such as cell-phone, intelligent bracelet, can adopt the diffusion piece.

The thickness of the diffusion plate is larger than that of the diffusion plate, and the thickness of the diffusion plate is 1.5mm-3 mm. The diffusion plate has higher haze and more uniform effect, and can be processed by an extrusion process, and the diffusion plate is made of at least one material selected from polymethyl methacrylate (PMMA), Polycarbonate (PC), polystyrene materials (PS) and polypropylene (PP).

The diffusion sheet has a thickness of 0.3mm or less, is relatively thin, and is more suitable for small and light display devices. The diffusion sheet is usually prepared by coating diffusion particles on a substrate, and the substrate may be polyethylene terephthalate (PET), glass, or the like, and the diffusion particles may be titanium dioxide, zinc oxide, calcium oxide, or the like.

The optical film 15 is located on a side of the diffusion layer 14 away from the micro led lamp panel 12. The optical film 15 may be provided in a single layer. The optical film 15 has the same shape as the diffusion layer 14 and may be generally provided in a rectangular or square shape. The optical film 15 is the same size as the diffusion layer 14.

The optical film 15 can make the backlight module suitable for various practical applications.

The optical film 15 may include a prism sheet that can change an exit angle of light, thereby changing a viewable angle of the display device.

The optical film 15 may further include a reflective polarizer, which is a brightness enhancement film, and can improve the brightness of the backlight module, improve the utilization efficiency of light, and make the emergent light have polarization property, thereby omitting the use of the polarizer under the liquid crystal display panel.

Referring to fig. 2, in the embodiment of the present invention, the miniature led lamp panel 12 specifically includes: a circuit board 121, a micro light emitting diode 122, a reflective layer 123 and a light evening component 124.

The circuit board 121 is located on the back plate 11, and the shape of the circuit board 121 is the same as the overall shape of the micro led lamp panel 12. In a general case, the circuit board 121 has a plate shape, and has a rectangular or square shape as a whole. The length of the circuit board 121 is 200mm-800mm, and the width is 100mm-500 mm.

In the embodiment of the present invention, the Circuit Board 121 may be a Printed Circuit Board (PCB), where the PCB includes an electronic Circuit and an insulating layer, and the insulating layer exposes a pad of the electronic Circuit, on which the micro light emitting diode is soldered, and covers the rest of the electronic Circuit.

Alternatively, the circuit board 121 may also be an array substrate formed by fabricating a thin film transistor driving circuit on a substrate, and the surface of the array substrate has a connection electrode connected to the thin film transistor driving circuit for soldering a micro light emitting diode.

The board material of the circuit board 121 may be aluminum substrate, BT or FR 4. Alternatively, the substrate or the substrate base plate of the circuit board 121 may be made of a flexible material to form a flexible display device.

The circuit board 121 is used for providing a driving electrical signal for the micro light emitting diode 122. The micro light emitting diode 122 and the circuit board 121 are separately manufactured, the surface of the circuit board 121 includes a plurality of bonding pads for soldering the micro light emitting diode 122, the micro light emitting diode 122 is transferred to the bonding pads after the manufacturing, and the micro light emitting diode 122 is soldered on the circuit board 121 through processes such as reflow soldering, so that the micro light emitting diode 122 can be driven to emit light by controlling an input signal of the circuit board 121.

The micro light emitting diode 122 is located on the circuit board, and an electrode of the micro light emitting diode 122 is soldered on the exposed pad of the circuit board 121, so as to realize electrical connection between the two.

The micro light emitting diode 122 is different from a general light emitting diode, and is specifically referred to as a micro light emitting diode chip. The small size of the micro-leds 122 is advantageous for controlling the dynamic light emission of the backlight module to a smaller sub-area, which is advantageous for improving the contrast of the image. In the embodiment of the present invention, the size of the micro light emitting diode 122 is below 500 μm.

The micro led lamp panel 12 may include only one color of micro leds 122, and may also include multiple colors of micro leds 122, which is not limited herein.

The reflective layer 123 is disposed on a surface of the circuit board 121 near the micro light emitting diodes 122. The reflective layer 123 has the same shape as the circuit board 121, and the reflective layer 123 includes a plurality of openings for exposing the micro light emitting diodes 122.

The reflective layer 123 is a protective layer located above the circuit board, and has functions of protecting the circuit board 121 and diffusely reflecting incident light.

In the embodiment of the present invention, the light reflecting layer 123 may be coated on the surface of the circuit board 121 by using a material with light reflecting property such as white oil, and then the position of the pad for soldering the micro light emitting diode 122 is exposed by etching or the like.

The reflective layer 123 reflects light, so that light emitted from the micro led lamp panel 122 can be reflected by the reflective layer 123 to the light emitting side again when being reflected to the back plate side by the elements in the backlight module, thereby improving the utilization efficiency of the light source.

The miniature light-emitting diode lamp panel provided by the embodiment of the invention further comprises a packaging layer which is not shown in the figure, wherein the packaging layer is positioned on the surface of the miniature light-emitting diode 122 on the side departing from the circuit board 121. The encapsulation layer has mutually discrete patterns, is dotted on the surface of the micro light-emitting diode 122, and is not arranged with patterns in other areas of the circuit board 121.

The encapsulation layer is used to protect the micro light emitting diode 122 and prevent foreign matters from entering the micro light emitting diode 122. In the embodiment of the present invention, the encapsulation layer may be made of a transparent colloid material, such as silicon gel or epoxy resin.

The light homogenizing member 124 is located on the light emitting side of the micro light emitting diodes 122, the light homogenizing member 124 is in one-to-one correspondence with the micro light emitting diodes, and one light homogenizing member 124 is disposed on the light emitting side of each micro light emitting diode 122 for homogenizing the emergent light of the micro light emitting diode 122.

Because the micro light-emitting diodes 122 are used as the backlight source in the embodiment of the invention, the energy distribution of the emergent light of the micro light-emitting diodes 122 meets lambertian distribution, the energy right above the micro light-emitting diodes 122 is stronger, and the energy at the junction position of the adjacent micro light-emitting diodes 122 is weaker.

In the embodiment of the invention, the light homogenizing part 124 is arranged on the light emitting side of the micro light emitting diode 122 to homogenize the light emitted by the micro light emitting diode 122, so that the energy difference between the small-angle range and the large-angle range emitted by the micro light emitting diode 122 is reduced.

The homogenized light enters the functional layer 13, and the reflectivity of the functional layer 13 to the incident light decreases as the angle of the incident light increases. That is, the larger the angle of the incident light is, the smaller the reflectivity of the functional layer 13 to the incident light is; the greater the angle of the incident light, the greater the transmittance of the functional layer to the incident light. A large portion of the low-angle light rays incident on the functional layer 13 will be reflected by the functional layer 13 and a large portion of the high-angle light rays incident on the functional layer 13 will be transmitted by the functional layer 13. The reflected small-angle light enters the reflective layer 123 again, enters the functional layer 13 again after the diffuse reflection effect of the reflective layer 123, and is finally homogenized after being reflected for many times between the functional layer 13 and the reflective layer 123.

In the embodiment of the invention, the light uniformizing component 124 and the functional layer 13 are used for uniformizing the light emitted by the micro light emitting diode 122, so that the vertical distance from the micro light emitting diode lamp panel 12 to the diffusion layer 14 and the distance between two adjacent micro light emitting diodes 122 can satisfy the following relationship:

H/P≤0.2；

referring to fig. 2, H represents a vertical distance from the micro led lamp panel 12 to the diffusion layer 14, and P represents a distance between two adjacent micro leds 122.

The vertical distance H between the micro light-emitting diode lamp panel 12 and the diffusion layer 14 is also called as light mixing distance (OD), the ratio H/P of the vertical distance H from the micro light-emitting diode lamp panel 12 to the diffusion layer 14 to the distance P between two adjacent micro light-emitting diodes 122 can embody the overall thickness of the backlight module, and the smaller the number H/P of the micro light-emitting diodes 122 is, the smaller the light mixing distance is, and the thinner the whole backlight module is; and the larger the distance between the adjacent micro light-emitting diodes is, the fewer the number of the micro light-emitting diodes which need to be used is, so that the cost can be reduced.

By adopting the structure of the dodging component combined with the functional layer, the H/P ratio can be controlled to be below 0.2, and compared with the structure of the H/P ratio above 0.3 in the prior art, the backlight module provided by the embodiment of the invention can have smaller thickness and is in line with the light and thin design of a display device; the number of the micro light-emitting diodes is reduced, and the production cost is reduced.

In the embodiment of the present invention, as shown in fig. 2, the light uniformizing part 124 may be configured as a lens located at the light emitting side of the micro light emitting diode 122. The lenses correspond to the micro light emitting diodes one to one, and one lens is disposed on the light emitting side of each micro light emitting diode 122.

The lens comprises a light inlet surface facing one side of the miniature light-emitting diode and a light outlet surface departing from one side of the miniature light-emitting diode, the light inlet surface protrudes towards one side departing from the miniature light-emitting diode to form a containing cavity, and the miniature light-emitting diode is positioned in the containing cavity. The surface of the micro light emitting diode is generally provided with a packaging layer, and the micro light emitting diode and the packaging layer on the surface of the micro light emitting diode are positioned in the accommodating cavity of the lens light incident surface.

The surface type of the light incident surface and the light emergent surface of the lens is reasonably designed, so that emergent light of the light diode can be firstly incident into the lens, and the light field distribution of transmitted light is adjusted. After the lens is arranged on the light emitting side of the micro light emitting diode, the light intensity right above the micro light emitting diode is relatively homogenized with the light intensity at the junction position of the adjacent micro light emitting diodes.

Fig. 3 is a second schematic cross-sectional view of a backlight module according to an embodiment of the invention.

Referring to fig. 3, in other embodiments of the present invention, the light uniforming member 124 may be disposed as a transflective layer at the light-emitting side of the micro light emitting diode.

When receiving the emergent light of the micro light-emitting diode, the semi-transparent semi-reflective layer transmits part of the light, reflects the rest of the light, and the reflected light enters the reflective layer 123 again and then exits to one side of the functional layer 13 after being subjected to the diffuse reflection effect of the reflective layer 123.

The semi-transparent and semi-reflective layer is arranged on the light emitting side of the micro light emitting diode, so that the intensity of emergent light above the micro light emitting diode can be reduced, light can be distributed towards an area far away from the area above the micro light emitting diode, and the relative homogenization of the emergent light of the micro light emitting diode is realized.

As shown in fig. 3, the micro led 122 is a micro led chip, which is usually square, and the transflective layer (124) can be directly disposed on the light-emitting surface, i.e. the upper surface, of the micro led 122. Therefore, the light emitted from the micro light emitting diode 122 directly upwards passes through the semi-transparent and semi-reflective layer, so that the light intensity of the emitted light is relatively uniform after the light is reflected by the semi-transparent and semi-reflective layer and the reflective layer 123.

Fig. 4 is a third schematic cross-sectional view of a backlight module according to an embodiment of the invention.

Referring to fig. 4, in other embodiments of the present invention, a protective layer 125 is disposed on a surface of the micro light emitting diode 122, and the transflective layer (124) is disposed on a surface of the protective layer 125 facing away from the micro light emitting diode 122.

The protection layer 125 disposed on the surface of the micro light emitting diode 122 may be the above-mentioned encapsulation layer, and the protection layer may be dot-coated on the surface of the micro light emitting diode 122 with a light-transmissive material.

The protective layer can protect the micro light emitting diodes 122, and the semi-transparent and semi-reflective layer (124) can be spaced apart from the micro light emitting diodes 122. Thus, the light emitted from the micro light emitting diode 122 passes through a certain distance and then enters the semi-transparent and semi-reflective layer, and when the light reflected by the semi-transparent and semi-reflective layer enters the reflective layer 123 to be reflected again, the path of the reflected light is increased, and the light can be reflected to a farther area, which is beneficial to converting the light emitted from the micro light emitting diode to the upper part to the junction position of the adjacent micro light emitting diodes, thereby realizing the homogenization of the light emitted from the micro light emitting diode.

In the embodiment of the invention, the homogenizing component 124 and the functional layer 13 are combined in the backlight module, so that the light-emitting uniformity of the backlight module can be improved.

In the embodiment of the present invention, the functional layer 13 includes a plurality of film layers arranged in a stacked manner, the refractive indexes of two adjacent film layers are not equal, and the refractive index and the thickness of the film layer satisfy the condition of thin film interference.

Fig. 5 is a schematic diagram of an operating principle of a functional layer provided in an embodiment of the present invention.

Referring to FIG. 5, when a light ray has an incident angle i, the refractive index n₁Is incident on a medium having a refractive index n₂On the surface of the film of (2), at n₁And n₂The interface of the two media reflects and refracts light, the reflecting angle is equal to the incident angle and is still i, and the refracting angle is gamma; when the refracted ray is incident on the lower surface of the film, the reflection and refraction of light can also occur on the lower surface, wherein the reflected ray passes through the upper surface of the film to face the n direction₁Refracts in the medium, thereby forming two reflected rays (1) and (2) on the upper and lower surfaces of the film. The optical path difference δ' between the reflected light ray (1) and the reflected light ray (2) is:

if the refractive index is n₂When the thickness of the film is d and the film has a uniform thickness, the film is formed by

And is

It is thus possible to obtain:

from the law of refraction it follows:

n₁ sini＝n₂ sinγ；

thus, it is possible to obtain:

as can be seen from the above formula, if the multilayer film structure is provided, the optical path difference of the reflected light of the light on the upper and lower surfaces of each layer of medium is only related to the refractive index, thickness and incident angle of the layer. In practical applications, light is generally incident into the film from an air medium and is reflected on the upper surface and the lower surface of the film, i.e. the refractive index n of the above formula ₁1, the above formula can therefore be simplified to:

according to the principle of film interference, when the optical path difference of the reflected light beams of the upper surface and the lower surface of the film is integral multiple of the wavelength, the two light beams are coherent and long; when the optical path difference of the reflected light rays of the upper surface and the lower surface is odd times of the half wavelength, the two light rays are coherently cancelled. According to the principle of energy conservation, if the reflected light is coherent and long, the energy of the reflected light is enhanced, and the energy of the transmitted light is weakened; if the reflected light is coherently canceled, the energy of the reflected light is diminished, and the energy of the transmitted light is increased.

When the above principle is applied to the embodiment of the present invention, the increased reflection incident angle θ is set for any one of the functional layers 13₁And anti-reflection incident angle theta₂Using the above principles, a suitable film material can be selected such that the refractive index and thickness of the film layer satisfy the angle of incidence θ₁Increase the reflection of the light ray to the incident angle theta₂The light is increased in reflection.

The functional layer 13 in the embodiment of the present invention has a reflectivity of 10% to 90% for incident light. The functional layer 13 has a reflectivity which can be reduced from 90% to 10% with increasing incidence angle for incident light with an incidence angle of 0-70 °, and a reflectivity of less than 10% for incident light with an incidence angle of 70 °. Therefore, the functional layer 13 can realize larger reflectivity for incident light with smaller incident angle; the larger the incident angle, the smaller the reflectivity. Accordingly, the functional layer 13 has a smaller transmittance for incident light having a smaller angle of incidence; the transmittance is higher for incident light rays having a higher incident angle. Since the functional layer 13 has the above properties, the functional layer is arranged on the light emitting side of the micro light emitting diode lamp panel, and can play a role in homogenizing light.

Fig. 6 and 7 are schematic cross-sectional structures of a backlight module according to an embodiment of the invention.

Referring to fig. 6 and 7, the backlight assembly further includes: a wavelength converting layer 16 and a support 17.

The wavelength conversion layer 16 is located on a side of the functional layer 13 and the diffusion layer 14 away from the micro light emitting diode lamp panel 12. The wavelength conversion layer 16 is provided in a layer having the same shape as the diffusion layer 14, and may be provided in a square or rectangular shape in general.

The wavelength conversion layer 16 is dispersed with a wavelength conversion material, and the wavelength conversion material emits light of other colors under the excitation of the excitation light emitted from the micro light emitting diode lamp panel 12.

In the embodiment of the present invention, the micro led 122 is a blue micro led, and the emergent wavelength of the blue micro led is 440nm to 450 nm.

The wavelength conversion layer 16 includes a red light conversion material that is excited to emit red light (620nm to 660nm) under irradiation of blue light and a green light conversion material that is excited to emit green light (525nm to 545nm) under irradiation of blue light. Therefore, the wavelength conversion layer 16 emits red light and green light under excitation of blue light, and the blue light, the red light, and the green light are mixed into white light to provide a backlight for the display panel.

In the embodiment of the present invention, the wavelength conversion layer 16 may be a quantum dot layer, the quantum dot layer includes a red quantum dot material and a green quantum dot material, the red quantum dot material emits red light under excitation of blue light, the green quantum dot material emits green light under excitation of blue light, and the red light and the green light emitted by excitation and the transmitted blue light are mixed to form a white light to be emitted.

In other embodiments of the present invention, the wavelength converter 16 may be a fluorescent layer including a red light conversion material and a green light conversion material, the red light conversion material emitting red light under excitation of blue light, the green light conversion material emitting green light under excitation of blue light, and the red light, the green light and the transmitted blue light emitted by the excitation are mixed to form white light to be emitted.

The support 17 is located between the back plate 11 and the diffusion layer 14 and at a position spaced apart from the micro-leds 122.

The brackets 17 are uniformly distributed on the back plate 11 and can be fixed on the back plate 11 or the micro light emitting diode lamp panel 12 through a buckle, a screw or a paste.

The bracket 17 plays a role in supporting the diffusion layer 14 and other components, and a certain distance is ensured between the micro light emitting diode lamp panel 12 and the diffusion layer 14. The support 17 is typically made of a light-transmissive material so as to avoid blocking light.

Referring to fig. 6, in the embodiment of the present invention, the functional layer 13 may be disposed on a side of the diffusion layer 14 facing away from the wavelength conversion layer 16.

The functional layer 13 is arranged on one side close to the miniature light-emitting diode lamp panel 12, so that light emitted by the miniature light-emitting diode lamp panel 12 can directly enter the functional layer 13 in advance. The functional layer 13 can further homogenize the light diffused by the micro light emitting diode 122 through the light homogenizing member 124, and has a good homogenizing effect.

Referring to fig. 7, in the embodiment of the present invention, the functional layer 13 may also be disposed on a side of the diffusion layer 14 away from the micro led lamp panel 12.

The material of support 17 can adopt hard materials such as polymethyl methacrylate (PMMA), and the one end that support 17 is close to diffusion layer 14 is more sharp, in order to avoid support 17 to stab or fish tail functional layer 13, can set up functional layer 13 in the one side that diffusion layer 14 deviates from miniature emitting diode lamp plate 12. The diffusion layer 14 may function to protect and support the functional layer 13.

Fig. 8 is a sixth schematic cross-sectional view of a backlight module according to an embodiment of the invention.

Referring to fig. 8, the backlight assembly further includes: a transparent substrate 18.

The transparent substrate 18 is located on one side of the diffusion layer 14 facing the micro light emitting diode lamp panel 12, and the functional layer 13 is located between the diffusion layer 14 and the transparent substrate 18.

The transparent substrate 18 is disposed in a layer, and the transparent substrate 18 has the same size and shape as the functional layer 13, and may be disposed in a square or rectangular shape in general.

The transparent substrate 18 may be made of a light-transmitting material having a relatively high transmittance, such as polymethyl methacrylate (PMMA) or glass.

The transparent substrate 18 is disposed between the functional layer 13 and the support 17, so that the tip of the support 17 can be prevented from directly contacting the functional layer 13, and the functional layer 13 can be prevented from being damaged and scratched. Meanwhile, the transparent substrate 18 can also play a role in supporting the functional layer 13 and the diffusion layer 14, so that the two sides of the functional layer 13 are supported by plates, and the reliability is higher.

The embodiment of the present invention further compares the light intensity distribution of the backlight module without the light homogenizing member 124 and the functional layer 13 in the prior art with the light intensity distribution of the backlight module with the light homogenizing member 124 and the functional layer 13 provided in the embodiment of the present invention.

Fig. 9 is a schematic diagram illustrating the light intensity distribution of the backlight module when the light uniformizing element 124 and the functional layer 13 are not used in the prior art, and it can be seen from fig. 9 that many discrete bright spots appear in the backlight module, and a circle of dark regions are formed around the bright spots, and the brightness distribution is not uniform.

Fig. 10 shows a schematic diagram of light intensity distribution of the backlight module after the light uniformizing element 124 and the functional layer 13 are adopted in the embodiment of the invention, and as can be seen from fig. 10, when the H/P value is reduced to 0.15, the embodiment of the invention still has better uniformity of light intensity distribution by the light uniformizing element 124 and the functional layer 13, and meets the requirement of the backlight module that the backlight module is light and thin and the number of micro light emitting diodes is small.

According to the first invention concept, the light homogenizing part is arranged on the light emitting side of the micro light emitting diode to homogenize the light emitted by the micro light emitting diode, so that the energy difference between the small-angle range and the large-angle range emitted by the micro light emitting diode is reduced. The homogenized light can enter the functional layer, and the reflectivity of the functional layer to the incident light is reduced along with the increase of the angle of the incident light. Most of the low-angle light rays incident to the functional layer will be reflected by the functional layer, and most of the high-angle light rays incident to the functional layer will be transmitted by the functional layer. The reflected small-angle light rays enter the reflective layer again, enter the functional layer again after the diffuse reflection effect of the reflective layer, and finally are further homogenized after being reflected for multiple times between the functional layer and the reflective layer.

According to the second inventive concept, the homogenization of the emergent light of the micro light-emitting diode by the light homogenizing component and the functional layer can enable the vertical distance from the lamp panel of the micro light-emitting diode to the diffusion layer and the distance between two adjacent micro light-emitting diodes to satisfy the following relations:

H/P≤0.2；

According to the third inventive concept, the light homogenizing part is a lens positioned at the light emitting side of the micro light emitting diode, the surface type of the light incident surface and the light emergent surface of the lens is reasonably designed, the emergent light of the light emitting diode can be firstly incident into the lens, the light field distribution of the transmitted light is adjusted, and the light intensity positioned right above the micro light emitting diode is relatively homogenized with the light intensity positioned at the junction position of the adjacent micro light emitting diode.

According to the fourth inventive concept, the light uniformizing part is a semi-transparent semi-reflective layer positioned at the light emitting side of the micro light emitting diode, when the semi-transparent semi-reflective layer receives the emergent light of the micro light emitting diode, part of the light is transmitted, the rest of the light is reflected, the reflected light enters the reflective layer again, and is emitted to one side of the functional layer after the diffuse reflection action of the reflective layer. The semi-transparent and semi-reflective layer is arranged on the light emitting side of the micro light emitting diode, so that the intensity of emergent light above the micro light emitting diode can be reduced, light can be distributed towards an area far away from the area above the micro light emitting diode, and the relative homogenization of the emergent light of the micro light emitting diode is realized.

According to the fifth inventive concept, the semi-transparent and semi-reflective layer is located on the light emitting surface of the micro light emitting diode, and the light emitted from the micro light emitting diode to the right above passes through the action of the semi-transparent and semi-reflective layer, so that the emergent light intensity is relatively uniform after the reflection action of the semi-transparent and semi-reflective layer and the reflective layer.

According to the sixth inventive concept, the surface of the micro light emitting diode is provided with a protective layer, and the semi-transparent semi-reflective layer is positioned on the surface of the protective layer on the side away from the micro light emitting diode. The protective layer makes a certain distance between the semi-transparent semi-reflecting layer and the micro light-emitting diode. The light emitted by the micro light-emitting diode enters the semi-transparent and semi-reflective layer after a certain distance, and when the light reflected by the semi-transparent and semi-reflective layer enters the reflective layer to be reflected again, the path of the reflected light is increased, and the light can be reflected to a farther area, so that the light emitted by the micro light-emitting diode right above can be favorably converted to the junction position of the adjacent micro light-emitting diode, and the homogenization of the light emitted by the micro light-emitting diode is realized.

According to the seventh inventive concept, the functional layer includes a plurality of film layers arranged in a stacked manner, the refractive indexes of two adjacent film layers are not equal, and the refractive indexes and the thicknesses of the film layers meet the condition of thin film interference.

According to the eighth inventive concept, the backlight module comprises a wavelength conversion layer positioned on one side of the functional layer and the diffusion layer, which is far away from the miniature light emitting diode lamp panel, and the wavelength conversion layer is used for emitting light of other colors under the excitation of excitation light emitted by the miniature light emitting diode lamp panel. The wavelength conversion layer is a quantum dot layer or a fluorescent layer.

According to the ninth inventive concept, the functional layer may be arranged on a side of the diffusion layer facing away from the wavelength conversion layer. The functional layer is arranged on one side close to the miniature light-emitting diode lamp panel, so that light emitted by the miniature light-emitting diode lamp panel can directly enter the functional layer firstly. The functional layer can further homogenize the light of the micro light-emitting diode after being diffused by the light homogenizing component, and the homogenizing effect is good.

According to the tenth inventive concept, the functional layer may be disposed on a side of the diffusion layer away from the panel of the micro light emitting diode. In order to avoid the bracket from puncturing or scratching the functional layer, the functional layer can be arranged on one side of the diffusion layer deviating from the miniature light-emitting diode lamp panel. The diffusion layer may function to protect and support the functional layer.

According to the eleventh inventive concept, the backlight module further comprises: the transparent substrate is positioned on one side, facing the micro light-emitting diode lamp panel, of the diffusion layer, and the functional layer is positioned between the diffusion layer and the transparent substrate. The transparent substrate is arranged between the functional layer and the support, so that the tip of the support can be prevented from directly contacting the functional layer, and the functional layer can be prevented from being damaged and scratched. Meanwhile, the transparent substrate can also play a role in supporting the functional layer and the diffusion layer, so that the two sides of the functional layer are supported by plates, and the reliability is higher.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A display device, comprising:

a display panel for image display;

the miniature light-emitting diode lamp panel is positioned at the light incident side of the display panel;

the functional layer is positioned on the light emitting side of the miniature light emitting diode lamp panel, and the reflectivity of the functional layer to incident light is reduced along with the increase of the angle of the incident light;

the miniature LED lamp plate includes:

the micro light-emitting diode is used as a backlight source;

and the light homogenizing part is positioned on the light emitting side of the micro light emitting diode and is used for homogenizing the emergent light of the micro light emitting diode.

2. The display device of claim 1, wherein the light unifying component is a lens located at a light exit side of the micro light emitting diode.

3. The display device as claimed in claim 1, wherein the light uniforming member is a transflective layer positioned at a light-emitting side of the micro light emitting diode.

4. The display device of claim 3, wherein the transflective layer is located on a light exit surface of the micro light emitting diode.

5. The display device according to claim 3, wherein a surface of the micro light emitting diode is provided with a protective layer, and the semi-transparent and semi-reflective layer is positioned on a surface of the protective layer on a side away from the micro light emitting diode.

6. The display device according to any one of claims 1 to 5, further comprising:

the diffusion layer is positioned on the light emitting side of the miniature light emitting diode lamp panel;

the vertical distance from the lamp panel of the miniature light-emitting diode to the diffusion layer and the distance between two adjacent miniature light-emitting diodes meet the following relationship:

H/P≤0.2；

h represents the vertical distance from the lamp panel of the micro light-emitting diode to the diffusion layer, and P represents the distance between two adjacent micro light-emitting diodes.

7. The display device of claim 6, further comprising:

the transparent substrate is positioned on one side, facing the miniature light-emitting diode lamp panel, of the diffusion layer;

the functional layer is located between the diffusion layer and the transparent substrate.

8. The display device according to claim 6, wherein the functional layer is located on a side of the diffusion layer facing the micro light emitting diode lamp panel;

or the functional layer is positioned on one side of the diffusion layer, which deviates from the miniature light-emitting diode lamp panel.

9. The display device of claim 6, further comprising:

the wavelength conversion layer is positioned on one side, away from the miniature light-emitting diode lamp panel, of the diffusion layer and the functional layer; the wavelength conversion layer emits light rays with other colors under the excitation of the excitation light emitted by the miniature light-emitting diode lamp panel.

10. The display device according to any one of claims 1 to 5, wherein the functional layer comprises a plurality of film layers arranged in a stack, the refractive indices of adjacent two of the film layers being unequal; the refractive index and the thickness of the film layer meet the condition of film interference.