WO2020057298A1 - Led display screen - Google Patents

Abstract

An LED display screen, comprising: an LED array layer, consisting of multiple LED chips and being used for emitting light; and an optical diffusion film provided on the light emitting side of the LED array layer, wherein the light emitted by the LED array layer is diffused to the viewer side through the optical diffusion film.

Description

LED display screen Technical field

The invention relates to the technical field of LED displays, and in particular to an LED display screen.

Background technique

Traditional film projection equipment uses a combination of a projector and a projection screen. Due to the design defect of the lens in the projector and the reflective characteristics of the LED display screen, the traditional projection projection equipment using this method has the disadvantages of poor picture uniformity, low brightness, poor picture contrast and high energy consumption.

As the audience's requirements for movie visual effects continue to increase, more and more theater shows use 4K resolution sources. In order to reduce costs and improve the contrast of the screen, LED display screens using LED chips generally use one pixel for one LED chip to display. Alternatively, as shown in Figure 1, three pixels, red, green, and blue, are used to form a pixel. .

The size of the LED display screen is usually in the range of 10 meters × 5 meters to 20 meters × 10 meters or larger. When the resolution of the picture in the LED display screen is fixed, the pitch p of the LED chips included in it is adjusted accordingly. For example, when the width of the LED display screen is 10 meters, the distance between adjacent LED chips is 2.5 mm, and when the width of the LED display screen is 20 meters, the distance between adjacent LEDs is 5 mm. The ratio of the pitch of the LED chip to the size of the LED chip is usually greater than 5: 1, which makes the pixel filling rate of the LED chip not high, which causes the problem that the picture on the LED display screen is not soft due to the strong graininess. Although the pixel filling rate of LED chips can be increased by increasing the number of LED chips included in the LED display screen, thereby improving the softness, this method will significantly increase the number of chips and drive power consumption, which will result in projection costs and projections. Increased power consumption.

Summary of the Invention

In order to solve the above-mentioned problem of strong and not soft due to graininess, the present invention discloses an LED display screen, which is composed of an LED array layer and an optical diffusion film, which can be used without significantly increasing cost and power consumption. The pixel filling rate of the LED chip is significantly improved, so that a softer picture is displayed on the LED display screen.

According to a first aspect of the present invention, an LED display screen is provided, which includes: an LED array layer composed of a plurality of LED chips and used to emit light; and an optical diffusion film disposed on the LED array layer to emit light Side, wherein the light emitted from the LED array layer is diffused to the audience side through the optical diffusion film.

The LED display screen according to the present invention can effectively increase the application range of the screen using the LED chip and the optical diffusion film, improve the display effect of the LED display screen, and improve the visual enjoyment and experience of the audience.

The LED display screen in the present invention is not only applicable to movie screens, but also to large outdoor advertising screens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a corresponding display manner of pixels and LED chips in a conventional LED display screen.

FIG. 2a shows the light distribution of a single LED chip in a cross-sectional view of an LED display screen in the present invention.

FIG. 2b shows the light distribution of a single LED chip in the front view of the LED display screen in the present invention.

FIG. 3 is a cross-sectional view of the structure of an LED display screen in the present invention.

Figures 4a-4d illustrate the effect of the pitch p of the LED chip and the distance h between the optical diffusion film and the LED array layer on the area of overlapping crosstalk.

FIG. 5 is a schematic diagram of an angle θ between an emitted light and a normal line after passing through the optical diffusion film.

FIG. 6 is a relationship curve between the intensity I (θ) of the incident parallel light and the angle θ after being diffused by the optical diffusion film in _parallel .

7a-7d are brightness distribution diagrams of adjacent LED chips under different diffusion angles.

Fig. 8a is a circular light distribution when the optical diffusion film is an isotropic diffusion film.

Fig. 8b is an elliptical light distribution when the optical diffusion film is an anisotropic diffusion film.

FIG. 9 is a schematic diagram of splicing optical films to form an LED display screen in a longitudinal adjacency manner.

FIG. 10 is a schematic diagram of splicing optical films to form an LED display screen in a lateral adjacency manner.

FIG. 11 is a splicing method of splicing two adjacent optical film materials together using adhesive tape.

FIG. 12 is a splicing method of splicing two adjacent optical film materials together using thermal welding or ultrasonic welding.

FIG. 13a is a splicing method for aligning the seam of the thin film material with the seam of the LED module.

FIG. 13b is a splicing method in which the seam of the thin film material is not aligned with the seam of the LED module.

FIG. 14 is a mechanical protrusion positioning structure used in the LED display screen of the present invention.

detailed description

Hereinafter, specific embodiments according to the present invention will be described in detail with reference to the accompanying drawings. It should be emphasized that all dimensions in the drawings are only schematic and are not necessarily illustrated in true scale, and thus are not restrictive. For example, it should be understood that the dimensions, proportions, and other parameters of components such as microstructures and reflective films in the illustrations are not shown according to the actual dimensions and proportions, and are only for convenience of illustration, but are not intended to limit the specifics of the present invention. range.

2a-2b show the light distribution of a single LED chip in the LED display screen of the present invention, wherein FIG. 2a is a cross-sectional view of the light distribution of the single LED chip, and FIG. 2b is a top view of the light distribution of the single LED chip.

The up-down direction in FIG. 2a is the direction perpendicular to the LED display screen, and the upper side is the audience side. Fig. 2b is a top view as viewed from the audience side.

In Fig. 2a, h is the distance between the optical diffusion film (not shown in Fig. 2a) and the LED chip in a direction perpendicular to the surface of the LED display screen, and D is the spot diameter of the single LED chip on the optical diffusion film. , Θ _{stop is} the light emitting angle of the light emitted by the single LED chip.

In FIG. 2b, p is the distance between adjacent LED chips in the LED array layer, and r is the spot diameter of the single LED chip on the optical diffusion film, that is, r = D / 2.

According to Fig. 2a, the diameter D of the light spot can be defined by the corresponding light emission angle θ _stop .

When the distance between the optical diffusion film and the LED array layer is h, the illumination distribution E (θ _stop ) of the light spot on the surface of the optical diffusion film can be calculated according to the following formula (1)

When the illuminance distribution E (θ _stop ) decays to a certain ratio a of the central illuminance E (0) (0 <a <0.5), the corresponding light angle θ _stop is:

When a = 0.1, the value of θ _stop is about 56 degrees, and the ratio D / h of the corresponding spot diameter D and distance h is 2tan (θ _stop ) ≈3, that is, D = 2htan (θ _stop ). When the value of a is increased, the corresponding spot diameter D is reduced. In practical applications, the spot diameter D defined by the light angle θ _stop can be used as the distance p between the LED chips.

In practical applications, when the pixel filling rate is constant, the spot diameter D can be used as the distance p between the LED chips, and D = 2htan (θ _stop ), then the distance p can be calculated by the following formula (3)

p = 2h tan (θ _stop ) (3)

The different corresponding values of a, θ _stop and 2tan (θ _stop ) are listed in Table 1 below:

Table 1

a	θ stop	2tan (θ stop )
0.05	61.77	3.72
0.1	55.78	2.94
0.2	48	2.22
0.3	42.3	1.82

It can be seen from the above table that as the value of a gradually increases, the corresponding spot diameter D (that is, the distance p between the LED chips) gradually decreases.

The light distribution of a single LED chip can be approximated as a Lambertian distribution, and its light intensity I (θ _stop ) can be calculated according to the following formula (4)

I (θ _stop ) = Icos (θ _stop ) (4)

Among them, θ _stop is the light emitting angle of the light emitted by a single LED chip, and I is the intensity of the light emitted when θ _stop is 0.

FIG. 3 is a cross-sectional view of the structure of an LED display screen in the present invention. The position and size of the light spot formed by the LED in the LED display screen are also explained.

As shown in FIG. 3, the LED display screen in the present invention includes an LED array layer and an optical diffusion film. The optical diffusion film is placed at a position closer to the viewer side than the LED array layer according to a certain distance h, that is, it is disposed on the light emitting side of the LED array layer. Thereby, the light emitted from the LED array layer is scattered to the viewer side by the optical diffusion film.

Although FIG. 3 illustrates by way of example that the LED array layer includes three LED chips, namely LED1, LED2, and LED3, those skilled in the art should understand that the LED array layer may include any number of LED chips as required. As shown in FIG. 3, the light spots formed by the chips LED1, LED2, and LED3 are respectively the light spot light intensity 1 (or the spatial distribution of light spot illumination 1), the light spot light intensity 2 (or the spatial distribution of light spot illumination 2), and the light spot light intensity 3 (Or spatial distribution of spot illumination 3).

The pixel fill ratio of an LED chip is defined as the ratio of the light emitting area and the pixel area of the LED chip. When the surface of the LED chip is covered with an optical diffusion film, since the illuminated area on the surface of the optical diffusion film is defined by the spot diameter D (or spot radius r), the pixel fill ratio can be defined as the ratio of the spot area to the pixel area:

In FIG. 3, the horizontal direction indicates the position of the light spot, and the vertical direction indicates the spatial distribution of the light intensity or the light intensity of the light spot. The positions of an optical diffusion film (referred to as an optical diffusion film 1) indicated by a solid line and an optical diffusion film (referred to as an optical diffusion film 2) indicated by a broken line are shown in FIG. 3. It can be seen from FIG. 3 that when the diffusion film is set to a certain distance, the light spots formed by adjacent LED chips overlap on the diffusion film, which can fill the black areas between adjacent LED chips, improve the pixel filling rate, and eliminate the screen. Graininess, but when h is reduced, the light spots formed on the optical diffusion film 2 become smaller, and the black area between adjacent LED chips cannot be completely filled, and the graininess cannot be eliminated.

Based on the above comparison results, it can be known that as the distance h between the optical diffusion film and the LED array layer gradually increases, the spot of the LED chip gradually increases on the surface of the optical diffusion film, so that the black area between adjacent LED chips can be filled. And increase the pixel fill rate of the LED chip.

Therefore, the LED display screen in the present invention can effectively shield the gaps between the LED chips through the optical diffusion film, thereby improving the pixel filling rate of the LED chip, and making the pixel filling rate of the LED chip reach 70% or more.

However, when the distance h between the optical diffusion film and the LED array layer is increased to a certain extent, the light emitted by adjacent LED chips will crosstalk with each other, which affects the clarity of the screen.

In order to solve the above-mentioned problem that the picture is not clear due to light crosstalk and improve the pixel filling rate, in the present invention, the distance p between adjacent LED chips and the distance h between the optical diffusion film and the LED array layer are made The relationship satisfies the following conditions: h <p <5h, preferably 2h <p <4h.

Figures 4a-4d illustrate the effect of the pitch p of the LED chip and the distance h between the optical diffusion film and the LED array layer on the area of overlapping crosstalk. It can be seen in conjunction with Figs. 4a-4d that as the ratio between p and h gradually becomes smaller, the area between overlapping crosstalk becomes smaller. After repeated studies by the inventor of the present invention, it is found that the relationship between the distance p between adjacent LED chips and the distance h between the optical diffusion film and the LED array layer satisfies h <p <5h, preferably 2h <p < The relationship of 4h can effectively avoid light crosstalk.

Therefore, in the present invention, by setting the relationship between the distance p between the diffusion film adjacent to the LED chip and the distance h between the optical diffusion film and the LED array layer, the pixel filling rate of the LED chip can be improved, and particles on the screen can be eliminated. And prevent blurring caused by light crosstalk.

The diffusion angle of the optical diffusion film is explained below with reference to FIGS. 5-7d.

FIG. 5 is a schematic diagram of the angle θ between the emitted light and the normal after passing through the optical diffusion film, where the intensity of the parallel light is I _parallel , and the intensity of the emitted light after passing through the optical diffusion film is I (θ) , I ₀ is the intensity of the emitted light when θ is 0.

FIG. 6 is a relationship curve between the incident parallel light intensity I and the outgoing light intensity I (θ) after being diffused by the optical diffusion film in _parallel with the angle θ, and thereby defining the diffusion angle of the optical diffusion film.

In FIG. 6, the horizontal axis represents the angle θ, and the vertical axis represents the emitted light intensity I (θ). It can be seen from FIG. 6 that the light intensity I (θ) of the outgoing light after the parallel light passes through the optical diffusion film changes with the angle θ.

When θ = 0, the light intensity I (θ) reaches a maximum value I ₀ . The light intensity I (θ) gradually decreases as θ gradually increases. When the light intensity I (θ) is reduced to a half of the central light intensity I ₀ (that is, the light intensity when the value of θ is 0), the corresponding full angle 2θ is defined as the diffusion angle of the optical diffusion film.

The optical diffusion film used in the present invention generally uses transparent PC or PET as a substrate, and may include a bulk diffusion film or a surface diffusion film.

The bulk diffusion film is provided with bulk scattering particles, and a bulk diffusion film having diffusion particles can be obtained using a precision optical coating device. The bulk diffusion particles are, for example, inorganic particles such as silica and titanium dioxide particles, or organic particles such as acrylic resin and epoxy resin particles.

The surface of the surface diffusion film has a rough structure and can be obtained by a roll-to-roll embossing process.

7a-7d illustrate the brightness distribution diagrams of adjacent LED chips under different diffusion angles. Among them, FIG. 7a illustrates the brightness distribution of a diffusion film with a diffusion angle of 5 degrees, FIG. 7b illustrates the brightness distribution of a diffusion film with a diffusion angle of 10 degrees, and FIG. 7c illustrates the brightness of a diffusion film with a diffusion angle of 40 degrees. Fig. 7d illustrates the brightness distribution of a diffusion film with a diffusion angle of 60 degrees.

According to the brightness distribution diagrams of Figs. 7a-7d, it can be known that when the distance p between adjacent LED chips is constant, when the diffusion angle is larger, there are more areas where the brightness distribution of adjacent LED chips overlaps, correspondingly forming a diffusion film. The corresponding LED spot area is larger, and the more black areas between adjacent LED chips that can be filled, the better the shielding effect of the optical diffusion film on the spaces between the LED chips. Therefore, the diffusion angle of the optical diffusion film in the present invention should be greater than 10 degrees, and more preferably greater than 40 degrees.

According to different needs, the isotropic diffusion film can be selected as the optical diffusion film. As shown in FIG. 8a, when an isotropic diffusion film is used, it can be seen from the viewer side that the diffusion angle of the diffusion film in all directions is the same.

However, the optical diffusion film can also choose an anisotropic diffusion film. In practical applications, viewers generally view the LED display screen in a relatively large horizontal field of view and a relatively small vertical field of view. Therefore, horizontal and Diffusion films with elliptical Gaussian distributions with different vertical diffusion angles. For example, when an anisotropic diffusion film as shown in FIG. 8b is used, it can be seen from the viewer that the diffusion angle of the diffusion film in the horizontal direction is greater than The diffusion angle in the vertical direction, so that the field of view in the horizontal direction is increased.

Of course, in other practical application scenarios, when the movie theater is divided into two floors, the viewing angle of the upper floor for the vertical field of view is relatively large, so the anisotropic diffusion film is set to have a vertical angle of diffusion greater than the horizontal direction. Of course, according to other specific practical requirements, the diffusion angle in any direction can be set to be greater than the diffusion angle in other directions.

Next, a method for forming an LED display screen in the present invention is described below.

First, multiple LED chips are integrated into one LED sub-module, which has an independent driving unit. Then, a plurality of sub-modules are spliced into an array form into an LED module having a medium size. If the size of the LED display screen is large, multiple medium-sized LED modules need to be spliced again.

The LED array layer is formed by the above-mentioned splicing LED sub-module or LED module.

The LED display screen is formed by using the module splicing method. When a problem occurs in one or more sub-module areas of the LED display screen and the picture quality is reduced or damaged, only the sub-module or module in question can be replaced without replacing. The entire LED display screen can save maintenance costs.

However, in the above-mentioned module splicing method, since the flatness and gap of the splicing boundary between each module or between sub-modules cannot be ideally controlled according to the prior art, there may be patchy seams with undulations at the splicing boundary, or even The patchwork is visible to the naked eye. This situation is not ideal because it may affect the visual effects of the product.

However, in the present invention, since the optical diffusion film is formed above the LED array layer closer to the audience side than in the LED display screen, the above-mentioned undesired patchwork can be covered by the optical diffusion film, thereby improving the visual effect of the product. Make the LED display screen surface look more flat and beautiful.

The optical film is usually formed as a roll having a width of 1.5 meters to 1.6 meters, and the optical diffusion film can be formed by splicing multiple optical films. For example, in the vertical abutment method shown in FIG. 9, if the width of the LED display screen to be manufactured is 10 meters and the height is 5 meters, the optical film roll can be cut into 7 pieces with a width of about 1.5 meters and a height of It is 5 meters long. Then the 7 pieces of strips are spliced in order, so that the spliced optical film appears to form a whole.

Because the width of the optical film roll is large, when forming a screen with a width of 10 meters as shown in FIG. 9, only the appearance of the six seams in the films 1-7 can be processed, which can reduce the The stitching process of forming an optical diffusion film on the entire LED display screen is difficult.

In addition, when forming the LED display screen in the present invention, for example, a horizontal splicing method may also be adopted. For example, in the horizontal splicing method shown in FIG. 10, the film material can be cut into four strips with a height of 1.25 meters and a width of 10 meters, and then the four strips are spliced together in sequence. Utilizing a frame structure such as a metal frame, the spliced optical diffusion film can be wrapped in a front surface or a back surface with a certain tension, so as to be stretched into a flat surface.

When forming a screen with a width of 10 meters as shown in FIG. 10, it is only necessary to handle the appearance of the three seams in the films 1-4, thereby further reducing the formation of an optical diffusion film on the entire LED display screen. Difficulty of stitching processing.

It should be noted that FIG. 9 and FIG. 10 only give an exemplary description of the size of the LED display screen and the cutting of the optical film roll. Those skilled in the art should easily understand that the LED display screen can adopt any desired size, and the optical film roll can also be appropriately cut and spliced according to actual needs, and is not limited to the specific splicing methods provided in FIGS. 9 and 10.

In order to make the audience hardly feel the seam between the optical diffusion films on the LED display screen, it is hoped that the seam will be as invisible as possible even under the condition of the LED chip light. Specifically, for a transparent optical diffusion film, it is desirable that the seam width between adjacent optical diffusion films is less than 100 microns.

Specifically, the method as shown in FIGS. 11 and 12 can be used to splice the optical diffusion film.

As shown in FIG. 11, two pieces of optical film material can be spliced together by a method of splicing tape. Specifically, two pieces of optical film material (film material 1 and film material 2) are placed in parallel along the long side direction, and the distance between the optical film materials is observed through a movable microscope and adjusted so that between the two long sides The spacing is within 100 microns. Then use the same diffusion tape and adhesive glue on the back to bond the two film materials together.

In addition, the method shown in FIG. 12 can also be used to overlap the optical film materials, and the two film materials can be connected together by thermal welding or ultrasonic welding.

In the LED display screen of the present invention, the seam of the thin film material can be aligned with the seam of the LED module as shown in FIG. 13a, or the seam of the thin film material can be made to be not as shown in FIG. 13b. The seams of the LED modules are aligned.

After the LED array layer is formed by the module splicing method and the optical diffusion film is spliced, the spliced optical diffusion film is fixed on the LED display screen frame by means of a spring or a rope, thereby ensuring that the surface of the optical diffusion film has a uniform distribution. Tension, so that the entire optical diffusion film and the LED array layer are stretched and flattened.

For example, a certain distance h can be maintained between the LED sub-module or the LED module and the optical diffusion film through the positioning structure. The LED array layer is arranged on a positioning structure. The positioning structure is set for each LED sub-module or LED module, and can have a plurality of heights. The positioning structure can be cooperatively connected by setting grooves and protrusions. In order to ensure accurate adjustment, a certain distance h is maintained between the LED sub-module or the LED module and the optical diffusion film.

Alternatively, a positioning structure is provided for the entire LED array layer, that is, the positioning structure is integrated, and the entire LED array layer is provided on the positioning structure, so as to maintain a distance h from the optical diffusion film. The positioning structure may use, for example, a mechanical protrusion positioning structure, a groove is provided on the optical diffusion film for coordinated positioning with the positioning structure, or a protrusion is provided on the optical diffusion film, and a groove is provided on the positioning structure for and Optical diffusion film.

As shown in FIG. 14, the LED sub-module or LED module is disposed on the surface of the mechanical protrusion positioning structure away from the audience side, and the optical diffusion film is disposed in the mechanical protrusion positioning structure on the same side as the LED sub-module or module but at a distance of h. At the location, the optical diffusion film is closer to the viewer side than the LED sub-module or module.

When assembling the optical diffusion film and the LED sub-module or module, it is necessary to control the contact force between the screen and the LED module, so that the contact force is small enough to prevent protrusions and discontinuities that cause the appearance of the screen.

According to the above-mentioned LED display screen in the present invention, the application range of the LED display screen can be effectively improved through the combination of the LED array layer and the optical diffusion film, and the pixel filling rate of the LED chip can be improved, thereby reducing the effect of graininess on the screen The problem of non-softness improves the display effect of the LED display screen, thereby improving the visual enjoyment and experience of the audience.

In addition, because the splicing technology of the optical diffusion film is used, the LED sub-modules or the joints between the LED modules can be shielded, and the visual effect of the product is improved. For example, when forming an LED display screen with a width of 10 meters and a height of 5 meters, only 6 patchwork needs to be processed in the vertical stitching method, and only 3 patchwork can be processed in the horizontal stitching method. The horizontal or vertical seam may be aligned with the seam between the LED sub-modules or modules, or may not be aligned with the seam of the LED sub-modules or modules, so that the seam between the LED sub-modules or the LED modules can be further covered .

In addition, the splicing technology of the optical film can greatly reduce the seam area of the entire screen surface. The seam can be controlled within 100 microns by using adhesive tape or welding methods, so that the audience will not see the seam under the LED chip lighting conditions. Seam.

In addition, the relationship between the distance p between adjacent LED chips and the distance h between the optical diffusion film and the LED array layer satisfies the following condition: h <p <5h, preferably 2h <p <4h, so that it can be prevented The light emitted by adjacent LED chips will crosstalk with each other, which can improve the sharpness of the picture.

In addition, the diffusion angle of the optical diffusion film in the present invention should be greater than 10 degrees, preferably greater than 40 degrees. When the diffusion angle is larger, the shielding effect of the optical diffusion film on the spaces between the LED chips is better.

In addition, as the size of the LED chip decreases and the fill rate of the pixel decreases, the light-emitting area per unit pixel becomes smaller and smaller. The brightness value in the light-emitting area of the LED chip is very high, and the brightness value in the non-LED chip light-emitting area is very low. To evaluate the brightness of a unit pixel, a test device needs to perform a weighted average of the entire pixel area in the later period. After adding the diffusion film, the light spot of the LED chip has a size close to that of the pixel, that is, it has a higher pixel fill rate, and the brightness of the unit pixel is more uniform. The test equipment does not need to be calibrated and the areas with and without light are averaged. Test accuracy will be higher.

Those skilled in the art should understand that, according to design requirements and other factors, various modifications, combinations, sub-combinations, and changes can be made within the scope of the claims appended to the present invention or their equivalents.

Claims (16)

1. An LED display screen includes:

   LED array layer, which is composed of a plurality of LED chips and is used to emit light; and

   An optical diffusion film is disposed on a light emitting side of the LED array layer, and light emitted from the LED array layer is diffused to a viewer side through the optical diffusion film.
2. The LED display screen according to claim 1, wherein a distance between the LED array layer and the optical diffusion film in a direction perpendicular to the optical diffusion film is h, and the LED array layer is adjacent to the The distance between the LED chips is p, and the values of p and h satisfy the following conditions: h <p <5h, preferably 2h <p <4h.
3. The LED display screen according to claim 1 or 2, wherein the LED array layer is formed by splicing a plurality of LED sub-modules or LED modules, and each of the LED sub-modules integrates a plurality of the LED chips, A plurality of the LED sub-modules are integrated in each of the LED modules.
4. The LED display screen according to claim 3, wherein the optical diffusion film shields a plurality of the LED sub-modules or a seam between the LED modules.
5. The LED display screen according to claim 3, wherein the optical diffusion film is composed of a plurality of optical film splicing, and the width of the seam between adjacent optical films is less than 100 microns.
6. The LED display screen according to claim 5, wherein the plurality of optical films are spliced in a vertical splicing manner or a horizontal splicing manner.
7. The LED display screen according to claim 5, wherein the seam between the plurality of optical films is aligned with or does not align with a plurality of the LED sub-modules or the seam between the LED modules. The LED sub-modules or the seams between the LED modules are aligned.
8. The LED display screen according to claim 5, comprising: an adhesive tape having a diffusing function, and the adhesive tape is used to splice adjacent optical films.
9. The LED display screen according to claim 5, wherein the adjacent optical films are spliced by thermal welding or ultrasonic welding.
10. The LED display screen according to claim 1 or 2, wherein the optical diffusion film is a bulk diffusion film or a surface diffusion film.
11. The LED display screen according to claim 10, wherein a surface of the surface diffusion film has a rough structure.
12. The LED display screen according to claim 1 or 2, wherein a diffusion angle of the optical diffusion film is greater than 10 degrees, and preferably greater than 40 degrees.
13. The LED display screen according to claim 1 or 2, wherein the optical diffusion film is an isotropic diffusion film or an anisotropic diffusion film.
14. The LED display screen according to claim 1 or 2, further comprising: a positioning structure, wherein the LED array layer is disposed on the positioning structure, so that the LED array layer and the optical diffusion film maintain a space between them. Mentioned distance h.
15. The LED display screen according to claim 14, wherein the positioning structure is integrally provided.
16. The LED display screen according to claim 14, comprising a plurality of positioning structures, and the plurality of positioning structures are cooperatively connected by providing grooves and protrusions.

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