monitor

Abstract

The present invention discloses a display, which includes a display panel and a light redirecting film, wherein the light redirecting film is arranged on the light output side of the display panel. The light redirecting film includes a light redistribution layer and a light guiding layer, wherein the light guiding layer is arranged on the light redistribution layer. The light redistribution layer of the light redirecting film includes a plurality of strip microprisms extending along a first direction and arranged at intervals, and a plurality of diffraction gratings arranged at the interval bottoms of adjacent strip microprisms, wherein each strip microprism has at least one side as a light guiding inclined surface, each interval bottom has at least one set of diffraction gratings, and the light guiding layer is connected to the strip microprisms and the plurality of diffraction gratings. When the light redirecting film is arranged on the display side of the display panel, the problem of light loss at the viewing angle of the display side can be improved, and the brightness distribution at different viewing angles can be made more uniform.

Description

Technical Field

[0001] The invention relates to a display comprising a light redirecting film to homogenize the brightness difference of the display at each viewing angle, thereby avoiding the problem of excessive viewing angle dependence. Background Art

[0002] As displays are developing towards larger sizes, especially for large TVs or spliced ​​display walls, even if users are viewing these displays at a straight angle, the contrast and brightness of the edge images of large-size displays are still inconsistent with the central image, not to mention that when users are viewing at a side angle, the color deviation and saturation reduction caused by the overall side brightness deficiency will be more serious. Although today's displays, whether passively emitting liquid crystal displays (LCDs), or actively emitting organic light-emitting diode displays (OLED displays), small-pitch LED displays, sub-millimeter light-emitting diode displays (mini LED displays), micron light-emitting diode displays (micro LED displays, the same below) and other electroluminescent displays, have excellent contrast characteristics at all viewing angles, allowing users to view displayed images at all viewing angles. The so-called contrast value is actually the ratio of the bright image to the dark black screen. For the contrast value of the display at the side viewing angle, such as in the liquid crystal display, it often has a certain contrast value because the light at the side viewing angle has been greatly attenuated and the light leakage in the dark state has become extremely low. For another example, in the electroluminescent display, because it does not emit light in the dark state, the contrast value is also higher, but it does not represent the uniformity and image quality of the bright image that the user can actually feel. Therefore, now users are not only satisfied with the minimum requirement that the displayed image can be viewed at the side viewing angle but the actual image brightness is weak, but they expect the displayed image to have consistent and uniform image light and image quality at all viewing angles. In addition, current displays, whether passive or active, generally use electroluminescent bodies as image light sources, such as liquid crystal displays using light-emitting diode (LED) backlights, or self-luminous organic light-emitting diode displays. Because electroluminescent bodies are point light sources with extremely high single-point brightness, good light guidance is required to form a uniform overall display screen without flickering. Please refer to Figure 1A , Figure 1ATaking a general liquid crystal display as an example, the distribution diagram of bright light at a horizontal viewing angle. It can be clearly seen from the diagram that the intensity of light emitted by the liquid crystal display decreases significantly as the viewing angle increases. This is because the liquid crystal display is a non-active light-emitting display and the pixel light transmittance of the display panel is low. In order to increase the backlight intensity and efficiency of the light-emitting diode, a brightness enhancement film, a focusing prism sheet and other structures must often be used in the backlight module for brightness enhancement, but these methods can often only increase the peak brightness of the front view, and when the light emitted by the backlight source passes through the display panel, it is limited by the aperture ratio of the pixels and will further attenuate as the viewing angle increases. In addition, for an electroluminescent display that uses its own light source as a display pixel directly, due to the lack of optical structure films in the backlight module such as a diffuser and a light guide plate on the display side, it is also easy to cause light loss and uneven light distribution when viewed from a larger side viewing angle, and it is difficult to form an ideal surface light source with similar brightness at each viewing angle. Therefore, the image viewed from the side cannot have the better image quality as the one viewed from the front, and is particularly prone to insufficient brightness due to light loss, resulting in the image having a lower contrast or abnormal color performance.

[0003] In addition, by Figure 1A The spectrum also shows the distribution characteristics of the brightness of conventional displays. The intensity is higher in the front viewing angle range (e.g., within ±30° viewing angle), while the intensity is greatly reduced in the side viewing angle range (e.g., outside ±30° viewing angle). This does not conform to the ideal normal distribution of brightness, and the brightness has a large tangent slope change to the viewing angle spectrum. In the conventional technology, the half-width (FWHM) of the spectrum curve is increased by strengthening the front-view incident intensity of the backlight source, but the overall distribution characteristics of the display brightness cannot be changed. Therefore, the conventional method of observing whether the brightness distribution at each viewing angle is uniform and wide by using the half-width (FWHM) is not representative.

[0004] Please refer to Figure 1B , Figure 1B The evaluation method is to use a method that can actually reflect the brightness of the front viewing angle and the side viewing angle. For example, 75% or more of the maximum brightness of the display at the vertical viewing angle represents the front viewing angle range, and 40% or more of the maximum brightness represents the side viewing angle range. When the front viewing angle range is not excessively reduced, the side viewing angle range can be extended and increased, so that the tangent slope of the brightness to the viewing angle spectrum changes smaller and more slowly, thereby presenting a more ideal normal distribution curve. The brightness of the display is better uniform at each viewing angle, and the human eye can feel a more uniform brightness when watching.

[0005] Among the conventional methods for improving the image quality of a display at a side viewing angle, for example, Taiwan Patent TWI645218 discloses using a light redirecting film with a double-layer grating surface to improve the color washout or gray-scale inversion phenomenon of a liquid crystal display at a wide viewing angle. However, actual tests have shown that although the light redirecting film has the effect of improving the color washout and gray-scale inversion phenomenon, the double-layer grating structure has a greater reduction in light brightness. In actual measurements, the grating structure still has relatively high zero-order diffraction and first-order diffraction intensities due to the diffraction effect. Although enhanced interference has a better light deflection efficiency than refraction or scattering, the angle it affects is still within the range of the normal viewing angle, and the gain in improving the side viewing brightness is limited. For another example, Taiwan Patent TWI731590 discloses a liquid crystal display, which includes a color improvement film with a stripe microprism layer to improve the color shift and saturation reduction problems of the liquid crystal display at side views. However, without excessive refraction of the microprisms to cause a decrease in display resolution, the light guide angle relying solely on the stripe microprism layer is still insufficient, so it still cannot solve the problems of light loss and uneven light distribution at side views. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a display that changes the display light brightness distribution pattern without affecting the original display front view brightness perception, extends the side viewing range and improves the image light quality and uniformity viewed from all angles.

[0007] In order to achieve the above-mentioned object, the present invention provides a display, which includes a display panel and a light redirecting film, wherein the light redirecting film is arranged on the light output side of the display panel, the light redirecting film includes a light redistribution layer and a light guide layer, the light redistribution layer has a plurality of strip microprisms extending along a first direction and arranged at intervals, and a plurality of diffraction gratings arranged at the interval bottoms of adjacent strip microprisms, wherein each strip microprism has at least one side as a light guiding inclined surface, and each interval bottom has at least one set of diffraction gratings; the light guide layer is arranged on the light redistribution layer and connected to the strip microprisms and the plurality of diffraction gratings; wherein, relative to the maximum brightness after normalization of the vertical viewing angle of the display, the viewing angle of 75% of the maximum brightness is defined as a 75% positive viewing angle range (VW75), the viewing angle of 40% of the maximum brightness is defined as a 40% side viewing angle range (VW40), and the 75% positive viewing angle range (VW75) of the maximum brightness of the display is different from the original 75% positive viewing angle range (VW75) without using the light redirecting film. origin ) has a viewing angle extension ratio of >1.0, and the 40% side viewing angle range (VW40) of maximum brightness is comparable to the original 40% side viewing angle range (VW40) without this light redirecting film. origin ) has a viewing angle extension ratio of >1.3, i.e. VW75 / VW75 origin>1.0, and VW40 / VW40 origin >1.3.

[0008] In another embodiment of the display of the present invention, the absolute value of the maximum tangent slope of the spectrum of the maximum brightness after normalization of the display with respect to the viewing angle is less than 4.0x10 -2 .

[0009] In another embodiment of the display of the present invention, the display panel may be a liquid crystal display panel or an electroluminescent display panel. In one embodiment of the present invention, the display panel is an electroluminescent display panel, wherein the electroluminescent display panel may be an organic light emitting diode display panel, a small pitch light emitting diode display panel, a sub-millimeter light emitting diode display panel or a micrometer light emitting diode display panel.

[0010] In another embodiment of the display of the present invention, the display further comprises a polarizing plate, and the polarizing plate is disposed on one side of the light redirecting film. The polarizing plate can be disposed on the light emitting side or the light incident side of the light redirecting film.

[0011] In another embodiment of the display of the present invention, the polarizing plate is a linear polarizing plate or a circular polarizing plate.

[0012] In an embodiment of the display of the present invention, the light redistribution layer has a first refractive index n1, the light guiding layer has a second refractive index n2, the first refractive index n1 and the second refractive index n2 are between 1.4 and 1.7, and the difference between n1 and n2 is not less than 0.05.

[0013] In another embodiment of the display of the present invention, the maximum width of the bottom of each stripe-shaped microprism of the light redistribution layer is between 3 μm and 15 μm.

[0014] In another embodiment of the display of the present invention, the height of each stripe-shaped microprism of the light redistribution layer is between 5 μm and 15 μm.

[0015] In another embodiment of the display of the present invention, the width of the bottom intervals between adjacent stripe-shaped microprisms of the light redistribution layer is between 3 μm and 15 μm.

[0016] In another embodiment of the display of the present invention, the tops of the strip-shaped micro-prisms of the light redistribution layer are flat, pointed or curved.

[0017] In another embodiment of the display of the present invention, each light-guiding slope of the multiple strip microprisms of the light redistribution layer forms an angle θ with the normal direction of the light redirecting film surface in a cross section perpendicular to the first direction, and the angle θ is not less than 5° and not more than 15°.

[0018] In another embodiment of the display of the present invention, the period of the diffraction grating disposed at the bottom of the interval between adjacent strip-shaped micro-prisms is between 0.5 μm and 3.0 μm.

[0019] In another embodiment of the display of the present invention, the height of each diffraction grating disposed at the bottom of the interval between adjacent strip-shaped micro-prisms is between 0.4 μm and 1.0 μm.

[0020] In another embodiment of the display of the present invention, the display further includes a functional layer formed on the light-emitting surface of the light redirecting film, wherein the functional layer can be selected from one of the groups consisting of a hard coating layer, an anti-reflection layer, and an anti-glare layer, or a combination thereof.

[0021] The above invention content is intended to provide a simplified summary of the content of this patent so that readers can have a basic understanding of the content of this patent. This invention content is not a complete overview of the content of this patent, and its intention is not to point out the important / key elements of the embodiments of the present invention or to define the scope of the present invention. After referring to the following implementation methods, those with ordinary knowledge in the technical field to which the present invention belongs can easily understand the basic spirit of the present invention and the technical means and implementation forms adopted by the present invention.

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but is not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A , Figure 1B The diagram shown is a schematic diagram of bright light distribution of a liquid crystal display at a horizontal viewing angle.

[0024] Figure 2A FIG. 1 is a perspective view of a display according to an embodiment of the present invention.

[0025] Figure 2B Depicted is a cross-sectional view of a display disclosed according to an embodiment of the present invention.

[0026] Figure 3 FIG. 2 is a schematic diagram of the light guiding effect of a conventional color improvement film having only a strip-shaped micro-prism layer.

[0027] Figure 4 Schematic diagram of the light guiding effect of the light redirecting film of a display according to an embodiment of the present invention

[0028] Figure 5A and 5B A schematic diagram of a display according to another embodiment of the present invention is shown.

[0029] Figure 6 A schematic diagram of a display disclosed in yet another embodiment of the present invention is shown.

[0030] Figure 7 The diagram depicts a normalized spectrum diagram of the maximum brightness of the display as it changes with viewing angle. DETAILED DESCRIPTION

[0031] In order to make the description of the content of the present invention more detailed and complete, the following is an illustrative description of the implementation and specific embodiments of the present invention; however, this is not the only form of implementing or using the specific embodiments of the present invention. The embodiments disclosed below can be combined or replaced with each other under beneficial circumstances, and other embodiments can be added to one embodiment without further recording or explanation.

[0032] In the following description, many specific details will be described in detail to enable the reader to fully understand the following embodiments. However, embodiments of the present invention can be practiced without these specific details. In other cases, well-known structures and devices are only schematically depicted in the figures to simplify the drawings.

[0033] First, please refer to Figure 2A as well as Figure 2B , Figure 2A What is shown is a three-dimensional perspective schematic diagram of a display disclosed according to an embodiment of the present invention. Figure 2B The cross-sectional view of a display according to an embodiment of the present invention along a cross section perpendicular to the Y-axis direction is shown. The display 10 of the present invention includes a display panel 11 and a light redirecting film 20, wherein the light redirecting film 20 is disposed on the light-emitting side (not shown) of the display panel 11. The light redirecting film 20 includes a light redistribution layer 30 and a light guide layer 40. The light redistribution layer 30 is used to receive image light from the display panel 11, and the light redistribution layer 30 has a plurality of strip microprisms 31 extending along a first direction D1 and arranged at intervals, and a plurality of diffraction gratings 32 disposed at the interval bottoms of adjacent strip microprisms 31, wherein at least one side of each strip microprism 31 is a light guiding inclined surface 31a, and each interval bottom has at least one set of diffraction gratings 32. The light guide layer 40 is disposed on the light redistribution layer 30, and is connected to the strip microprisms 31 and the diffraction gratings 32. The viewing angle extension ratio of the display 10 at a maximum brightness of 75% is greater than 1.0, and the viewing angle extension ratio at a maximum brightness of 40% is greater than 1.3. In actual operation, the first direction D1 can be the length direction or the width direction of the light redirecting film 10 .

[0034] In this article, the maximum brightness 75% front viewing angle range (VW75) refers to the viewing angle range covered by the brightness of the display being 75% or more relative to the maximum brightness of the vertical viewing angle after brightness normalization; the maximum brightness 40% side viewing angle range (VW40) refers to the side viewing angle range covered by the brightness being 40% or more relative to the maximum brightness of the vertical viewing angle. The original 75% front viewing angle range and the original 40% side viewing angle range of the conventional display that does not include the light redirecting film 20 are represented by VW75 and VW40, respectively. origin With VW40 origin The viewing angle extension ratio is the original viewing angle ratio of the display 10 of the present invention with the light redirecting film 20 relative to the conventional display without the light redirecting film 20. In the display 10 of the present invention, when the image light of the display panel 11 is perpendicularly incident on the light redirecting film 20, the light can be efficiently transmitted laterally to extend the front viewing angle and the side viewing angle range, so that the viewing angle extension ratio of the front viewing angle range represented by the maximum brightness of 75% is greater than 1.0 (VW75 / VW75 origin >1.0), and the viewing angle extension ratio of the side viewing angle range represented by the maximum brightness of 40% is greater than 1.3 (VW40 / VW40 origin >1.3) without compromising or limiting the brightness at normal viewing angles.

[0035] In another embodiment of the display of the present invention, the absolute value of the maximum tangent slope of the spectrum of the maximum brightness after normalization of the display 10 with respect to the viewing angle is less than 4.0x10 -2 When the absolute value of the tangent slope is small, it means that the brightness changes more gently with the viewing angle and is not easily detected by the human eye and affects the visual experience.

[0036] In the embodiment of the display of the present invention, the display panel that can be used is not limited to the light emitting mechanism of the display panel. The display panel can improve the light distribution of the bright image of the display by using a light redirecting film, especially for display panels with large difference in maximum brightness between the front viewing angle and the side viewing angle or with rapid brightness decay with viewing angle. In a preferred embodiment of the display of the present invention, the display panel 11 can be a liquid crystal display panel or an electroluminescent display panel. In the embodiment of the present invention using an electroluminescent display panel, the display panel can be an organic light emitting diode display panel, a small pitch light emitting diode display panel, a sub-millimeter light emitting diode display panel or a micrometer light emitting diode display panel (or micro light emitting diode display panel).

[0037] like Figure 2BAs shown, in the light redirecting film 20 included in the preferred embodiment of the display of the present invention, the maximum bottom width W1 of the strip microprisms 31 of the light redistribution layer 30 is between 3μm and 15μm, the height H1 is between 5μm and 15μm, and the bottom spacing width W2 of adjacent strip microprisms 31 is between 3μm and 15μm. In the embodiment of the light redirecting film 20 of the present invention, the height H1 of the strip microprisms 31 is sufficient to provide the light deflected by the diffraction grating 32 to pass obliquely, and the maximum bottom width W1 of the strip microprisms 31 and the bottom spacing width W2 of adjacent strip microprisms 31 can be adjusted according to the lateral light source intensity required by the display panel 11 of the actual application to guide the light in a proportion.

[0038] In another embodiment of the display of the present invention, the top of the strip microprism 31 of the light redirecting film 20 is not limited to a plane, a sharp angle or an arc, so as not to cause the bright state image of the display to produce a flickering feeling. In a preferred embodiment of the present invention, the top of the strip microprism 31 of the light redirecting film 20 is a plane.

[0039] In a display of another embodiment of the present invention, each light guiding inclined surface 31a of the strip microprism 31 of the light redirecting film 20 forms an angle θ with the normal direction of the film surface of the light redirecting film 20 in a cross section perpendicular to the first direction D1, and the angle θ is preferably not less than 5° and not greater than 15°. By designing that the angle θ is not less than 5°, the light guiding inclined surface 31a can provide a sufficient light guiding incident surface to receive the light after passing through the diffraction gratings 32; by designing that the angle θ is not greater than 15°, a substantially linear light guiding effect can be achieved.

[0040] In a display of another embodiment of the present invention, the strip microprisms 31 of the light redirecting film 20 can be independently set to have the bottom maximum width W1, height H1, bottom spacing width W2 and angle θ to be completely or partially the same depending on the pixel arrangement, pixel size, overall requirements or product design requirements of different display panels 11. Therefore, adjacent light-guiding inclined surfaces 31a in the light redirecting film 20 can be symmetrical or asymmetrical.

[0041] In a display of another embodiment of the present invention, the period P of the diffraction grating 32 of the light redirecting film 20 is preferably between 0.5 μm and 3.0 μm. The height H2 of each diffraction grating 32 is between 0.4 μm and 1.0 μm. When the period P of the diffraction gratings 32 is smaller than the width of the strip microprism 31, and the height H2 of the diffraction grating 32 is smaller than the height of the strip microprism 31, the diffraction gratings 32 can produce relatively more diffraction effects without affecting the image resolution. Moreover, the size of the diffraction gratings 32 is not less than the wavelength of visible light, so that the sub-wavelength effect will not be generated, thereby not affecting the reflection and penetration of visible light at the interface of the diffraction grating 32, and will not cause unexpected design variables due to the discontinuity of the diffraction effect.

[0042] The light redirecting film 20 of the present invention is formed of a light redistribution layer 30 and a light guiding layer 40 with a curable resin having different refractive indices. In the interface between the light redistribution layer 30 and the light guiding layer 40, a diffraction grating 32 is formed which has a strong diffraction effect and performs the first light splitting of the incoming light. The light splitting effect of the diffraction grating 32 is related to the grating period, height, etc., and does not change significantly due to the light path passing through a high refractive index resin layer first and then a low refractive index resin layer, or passing through a low refractive index resin layer first and then a high refractive index resin layer, but there must be a refractive index difference between the two. Therefore, the first refractive index n1 of the light redistribution layer 30 can be selected to be greater than or less than the second refractive index n2 of the light guiding layer 40. In one embodiment of the present invention, the first refractive index n1 and the second refractive index n2 are between 1.4 and 1.7, and the difference between the first refractive index n1 and the second refractive index n2 is not less than 0.05 and not more than 0.3.

[0043] Please refer to Figure 3 , Figure 3 FIG. 5 is a schematic diagram of the light guiding effect of a conventional color improvement film 50 having only a stripe microprism layer 60. The conventional color improvement film 50 deflects the light L incident on the stripe microprism layer 60 by using the refractive index difference between the stripe microprism layer 60 and the fill layer 70 and the light guiding inclined surfaces 61a of the plurality of stripe microprisms 61, so as to improve the color deviation problem when viewed from the side. However, since the light L can only be deflected when passing through the light-guiding inclined surfaces 61a when it is incident from the front, as the display is developing towards thinner, the only way is to increase the angle θ between the light-guiding inclined surfaces 61a and the normal line of the film surface to change the proportion of light that can pass through the light-guiding inclined surfaces 61a; or to increase the refractive index difference between the strip microprism layer 60 and the filling layer 70 to increase the degree of deflection of the incident light. However, special optical materials with extremely high or extremely low refractive indices are difficult to obtain. Therefore, it is impossible to significantly guide light to the side viewing angle to improve the brightness distribution difference between the side viewing angle range and the front viewing angle range.

[0044] Figure 4FIG. 1 is a schematic diagram of the light guiding effect of the light redirecting film 20 included in the display 10 of the present invention. In one embodiment, the light redistribution layer 30 of the light redirecting film 20 is disposed on the light incident side of the light L, and the light guiding layer 40 is on the light exiting side. The light redistribution layer 30 of the light redirecting film 20 includes not only a plurality of strip-shaped microprisms 31, but also a plurality of diffraction gratings 32 disposed at the bottom of the intervals between adjacent strip-shaped microprisms 31. Under the premise of not increasing the overall thickness of the light redirecting film 20, these diffraction gratings 32 can allow the incident light L to not only directly pass through the light-guiding bevels 31a, but also allow the light L that originally passed through the flat portion of the bottom of the interval without being deflected to be diffracted and deflected first, and then obliquely enter the light-guiding bevels 31a in the light-guiding layer 40, so as to increase the light-guiding path without increasing the overall thickness of the light redirecting film 20, and again pass through multiple refractions, diffractions or reflections of adjacent light-guiding bevels 31a and diffraction gratings 32 to a larger angle, so that the light intensity naturally decreases with the number of deflections at the lateral viewing angle, thereby reducing the difference in brightness distribution between the lateral viewing angle range and the front viewing angle range, thereby achieving a stronger lateral light guiding and homogenizing effect.

[0045] like Figure 5A to Figure 5B As shown, in another embodiment of the display of the present invention, the display 100, 100' further includes a polarizing plate 80, and the polarizing plate 80 is disposed on one side of the light redirecting film 20. The polarizing plate 80 can be selectively adjacent to the light redistribution layer 30 or the light guide layer 40 of the light redirecting film 20. Figure 5A When the polarizer 80 is adjacent to the light redistribution layer 30, the total in-plane phase difference (Re) of the light redirecting film 20 is preferably less than 10 nm or greater than 3000 nm. Figure 5B When the polarizing plate 80 is adjacent to the light guiding layer 40, the total in-plane phase difference (Re) of the light redirecting film 20 should preferably be less than 10 nm or close to 0, so as to avoid deviations in the contrast and other characteristics of the display 100' or unevenness such as rainbow patterns due to the addition of the light redirecting film 20 when the polarizing plate 80 itself needs to have a specific phase difference value.

[0046] In another embodiment of the display of the present invention, the polarizing plate 80 may be a linear polarizing plate or a circular polarizing plate. If the polarizing plate 80 is a linear polarizing plate, the polarizing plate 80 is preferably adjacent to the light redistribution layer 30, and the polarizing plate 80 may also be used as a substrate used in the first curable resin molding process of the light redistribution layer 30, and the light redirecting film 20 may be used as a protective layer of the polarizing plate 80, and the first direction D1 (Y-axis direction) along which the strip microprisms 31 and the diffraction gratings 32 extend intersects with the absorption axis 80a of the polarizing plate 80 at an angle, and the angle is between 90°±25°, so as to enhance the brightness of the horizontal side viewing angle and the brightness equalization effect of each horizontal viewing angle. If the polarizing plate 80 is a circular polarizing plate, regardless of whether the polarizing plate 80 is adjacent to the light redistribution layer 30 or the light guiding layer 40, the polarizing plate 80 can also reduce the degree of reflection of the external ambient light on the display panel 11 of the display 100 or 100', especially for the electroluminescent display panel or semi-transmissive liquid crystal display with more serious electrode reflection.

[0047] Figure 6 is a schematic diagram of another embodiment of the display of the present invention, which Figure 5A A further variation of display 100 is shown in which light redirecting film 220 is adjacent to polarizer 80 with light redistribution layer 30 . Figure 6 The light redirecting film 220 of the disclosed display 100A further includes a functional layer 90 formed on the surface of the light guiding layer 40 of the light redirecting film 220 (i.e., the functional layer 90 is formed on the surface of the light emitting side of the light redirecting film 220, or the light emitting surface), wherein the functional layer 90 can be selected from one of a hard coating layer, an anti-reflection layer, an anti-glare layer, or any combination thereof according to the actual needs of the display. In a preferred embodiment of the present invention, the functional layer 90 is a substrate used in the second curable resin molding process of the light guiding layer 40 and other surface treatment functions are appropriately added to the surface as required. In another embodiment of the present invention, the functional layer 90 can be a protective layer on the outside of the light redirecting film 220.

[0048] The manufacturing method of the light redirecting film 20 included in the display 10 of the present invention is not particularly limited. In one embodiment of the present invention, the light redirecting film 20 can be formed into strip microprisms 31 and diffraction gratings 32 by a mold, an engraving roller, etc. For example, a first curable resin (not shown) having a first refractive index n1 is first printed to form a plurality of strip microprisms 31 and a plurality of diffraction gratings 32 extending in the same direction. After being cured to form the light redistribution layer 30, a second curable resin (not shown) having a second refractive index n2 is filled on the surface of the light redistribution layer 30 and flattened to form the light guide layer 40. In another embodiment of the present invention, the second curable resin (not shown) with the second refractive index n2 used as the light guide layer 40 can be firstly embossed by a mold with a reverse structure, an engraving roller, etc., to form the strip microprisms 31 and a plurality of diffraction gratings 32 extending in the same direction and corresponding to the reverse direction, and then the first curable resin (not shown) with the first refractive index n1 is filled in the embossed surface of the light guide layer 40 and flattened to form the light redistribution layer 30 after curing. The interface where the light redistribution layer 30 contacts the light guide layer 40 has the microstructure of the strip microprisms 31 and the diffraction gratings 32. The first curable resin and the second curable resin can be light curable resins or heat curable resins, such as acrylic resins, silicone resins, polyurethane resins, epoxy resins or combinations thereof.

[0049] The manufacturing method of the stripe-shaped microprisms 31 and the diffraction gratings 32 of the light redirecting film 20 included in the display 10 of the present invention can also be to coat a first curable resin having a first refractive index n1 on a substrate, and then emboss by a mold, an engraving roller, etc. to form a plurality of stripe-shaped microprisms 31 and a plurality of diffraction gratings 32 extending in the same direction. After curing to form the light redistribution layer 30, a second curable resin having a second refractive index n2 is then coated and the surface of the light redistribution layer 30 is flattened to form the light guide layer 40. In another embodiment of the present invention, the second curable resin having a second refractive index n2 used as the light guide layer 40 can also be coated on a substrate with a reverse structure mold, an engraving roller, etc., and then embossed to form the stripe-shaped microprisms 31 and a plurality of diffraction gratings 32 extending in the same direction in the opposite direction. After curing, the first curable resin having a first refractive index n1 is filled in the embossed surface of the light guide layer 40 and flattened to form the light redistribution layer 30. After the light redistribution layer 30 and the light guiding layer 40 are fabricated, the substrate may be retained or removed. In the embodiment where a substrate is used to fabricate the light redirecting film 20, the substrate may be a transparent substrate commonly used in the art, such as polyethylene terephthalate film (PET), triacetyl cellulose film (TAC), polymethyl methacrylate film (PMMA), etc.

[0050] The following examples are used to further illustrate the present invention, but the present invention is not limited thereto.

[0051] Example

[0052] Example 1, Example 2 and Example 3

[0053] In the display of the present embodiment 1 to embodiment 3, different light redirecting films are attached to the same polarizing plate by using adhesive layers, and then the light redirecting films are respectively attached to the light-emitting surface of the same liquid crystal display panel (brand model: AUO, VP229DA) to eliminate the influence of the air layer interface. The size, material refractive index and light guiding inclined angle of the strip microprism and diffraction grating of the light redistribution layer of the light redirecting film used in each embodiment are listed in Table 1. The absorption axis of the polarizing plate is the horizontal viewing direction, and the first direction in which the strip microprisms of the light redirecting film are arranged and the angle between the absorption axis of the polarizing plate is 105°, so as to generate sufficient horizontal lateral light guide, and appropriately avoid the microstructure in the light redirecting film and the pixel period of the liquid crystal display panel to generate diffraction lines or abnormal light spots.

[0054] Comparative Example

[0055] Comparative Example 1

[0056] In the display of Comparative Example 1, the liquid crystal display panel and polarizing plate used are the same as those of Examples 1 to 3, but the polarizing plate itself is not laminated with any optical film with light-guiding structures such as strip microprisms or diffraction gratings.

[0057] Comparative Examples 2 and 3

[0058] The displays of Comparative Examples 2 and 3 also use the same external attachment method and the same absorption axis angle with the polarizing plate as in Examples 1 to 3. Figure 3 The color improvement film with stripe-shaped microprisms is laminated on the polarizing plate and liquid crystal display panel of the same embodiment. The size, refractive index and light guide slope angle of the stripe-shaped microprisms of the color improvement film of Comparative Examples 2 and 3 are shown in Table 1.

[0059] Comparative Example 4

[0060] Comparative Example 4 uses the same external bonding method as in Example to laminate an optical film having a diffraction grating structure on the same polarizing plate and liquid crystal display panel as in Example. The structural dimensions of the diffraction grating are shown in Table 1.

[0061] Table 1

[0062]

[0063] The maximum brightness of the L255 tone in the horizontal viewing angle direction of the displays of the above-mentioned embodiments and comparative examples was measured by a panel measuring instrument Autronic Melchers GmbH Mechanics, ConoScope 80. The normalized spectrum is shown in Figure 7 The test results are shown in Table 2.

[0064] Table 2

[0065]

[0066] It is obvious from the data in Table 2 that when the display uses the color improvement films of Comparative Examples 2 and 3 with only strip microprism structures, and Comparative Example 4 with only diffraction grating light redirecting films, it is difficult for the display panel to simultaneously achieve the effect of increasing the angle range of the side viewing angle and reducing the maximum slope of the brightness curve, compared with Comparative Example 1 without any light-guiding structure film. In particular, in Comparative Example 3 with only strip microprism structures, even though the height of the strip microprisms has been greatly increased and the ability of its light-guiding slope to receive lateral light guidance has been increased, its side viewing angle coverage of more than 40% brightness still has its limit, which can only reach 78°. Although the maximum slope of the curve of brightness changing with viewing angle can also be reduced, the positive viewing angle coverage of more than 75% brightness has been slightly reduced, and it is difficult to expect that the side light guiding effect can be improved by repeatedly increasing the thickness of the structure. For Comparative Example 4 with only diffraction grating structure, although it does not affect the positive viewing angle range, the effect of diffracting light to the side viewing angle is also not good. From the measured values ​​in Table 2 and Figure 7 From the spectrum of maximum brightness changing with viewing angle, the comparative example 1 without any light guide structure film is used as a control, and its maximum brightness of 40% represents the original 40% side viewing angle range (VW40 origin ) and maximum brightness 75% represents the original 75% positive viewing angle range (VW75 origin ), Examples 1 to 3 can all effectively extend the viewing angle, especially in the side viewing angle coverage range (VW40) above the maximum brightness of 40%, the efficiency is extremely good, and the 40% viewing angle extension ratio is VW40 / VW40 origin All are above 1.3. For the front viewing angle range with brightness above 75%, it is still greater than 1.0 and better than the original viewing angle. It will not limit the original front viewing angle range, but only reduce the peak value of the maximum brightness and effectively distribute the light evenly to the side viewing angle. Therefore, the maximum tangent slope of the brightness changing with the viewing angle can be maintained at a low level of less than 4.0x10 -2 , making the bright-state spectrum of the display close to the ideal normal distribution curve.

[0067] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A display, characterized in that include: Display panel; as well as A light redirecting film is disposed on the light emitting side of the display panel, and the light redirecting film comprises: A light redistribution layer having a plurality of strip-shaped micro-prisms extending along a first direction and arranged at intervals, and a plurality of diffraction gratings disposed at the bottom of the intervals between adjacent strip-shaped micro-prisms, wherein each strip-shaped micro-prism has at least one side as a light guiding inclined surface, and each interval bottom has at least one set of diffraction gratings; and A light guide layer is disposed on the light redistribution layer and connected to the plurality of strip-shaped micro-prisms and the plurality of diffraction gratings; Among them, the viewing angle extension ratio of the display at the normalized maximum brightness of 75% is greater than 1.0, and the viewing angle extension ratio at the maximum brightness of 40% is greater than 1.3; the light redistribution layer has a first refractive index n1, the light guiding layer has a second refractive index n2, the first refractive index n1 and the second refractive index n2 are between 1.4 and 1.7, and the difference between the first refractive index n1 and the second refractive index n2 is not less than 0.

05.

2. The display according to claim 1, characterized in that The absolute value of the maximum tangent slope of the normalized maximum brightness spectrum with viewing angle is less than 4.0x10 -2 .

3. The display according to claim 1, characterized in that The display panel is a liquid crystal display panel or an electroluminescent display panel.

4. The display according to claim 3, characterized in that: The electroluminescent display panel is an organic light emitting diode display panel, a small pitch light emitting diode display panel, a sub-millimeter light emitting diode display panel or a micrometer light emitting diode display panel.

5. The display according to claim 1, characterized in that: The display further includes a polarizing plate disposed on one side of the light redirecting film.

6. The display according to claim 5, characterized in that: The polarizing plate is a linear polarizing plate or a circular polarizing plate.

7. The display according to claim 1, characterized in that: The maximum width of the bottom of each stripe-shaped microprism of the light redistribution layer is between 3 μm and 15 μm.

8. The display according to claim 1, characterized in that: The height of each stripe-shaped microprism of the light redistribution layer is between 5 μm and 15 μm.

9. The display according to claim 1, characterized in that: The width of the bottom intervals between adjacent strip-shaped microprisms of the light redistribution layer is between 3 μm and 15 μm.

10. The display according to claim 1, characterized in that The tops of the plurality of strip-shaped micro-prisms of the light redistribution layer are flat, pointed or arc-shaped.

11. The display according to claim 1, characterized in that: Each light guiding inclined surface of the plurality of strip-shaped microprisms of the light redistribution layer forms an angle θ with the normal direction of the light redirecting film surface in a cross section perpendicular to the first direction, and the angle θ is not less than 5° and not more than 15°.

12. The display according to claim 1, characterized in that: The periods of the plurality of diffraction gratings of the light redistribution layer are between 0.5 μm and 3.0 μm.

13. The display according to claim 1, characterized in that: The height of each diffraction grating of the light redistribution layer is between 0.4 μm and 1.0 μm.

14. The display according to claim 1, characterized in that: The display further comprises a functional layer formed on the light-emitting surface of the light redirecting film, wherein the functional layer is selected from one of the group consisting of a hard coating layer, an anti-reflection layer and an anti-glare layer or any combination thereof.

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