TWI807368B - Viewing angle compensation film and display device using the same - Google Patents

Abstract

A viewing angle compensation film and a display device using the same are provided. The viewing angle compensation film includes a micro-structure layer and a protecting layer. The micro-structure layer has a first surface and a second surface opposite to each other and includes a plurality of first grooves and a plurality of second grooves. The plurality of first grooves concave inwardly from the first surface and have a first deep. The plurality of second grooves concave inwardly from the first surface and have a second deep. The plurality of first grooves and the plurality of second grooves are mixed with each other. The first deep and the second deep is different. The protecting layer covers the first surface and fills plurality of first grooves and the plurality of second grooves. The refractive index of the protecting layer is larger than the refractive index of the micro-structure layer. The display device includes a display panel having a display face and the viewing angle compensation film. The viewing angle compensation film is disposed on the display face, wherein the micro-structure layer is between the display face and the protecting layer.

Description

View angle compensation film and display device using same

The invention relates to a viewing angle compensation film and a display device using the film.

In recent years, liquid crystal displays (Liquid Crystal Displays) have become the mainstream of various display devices. For example, household TVs, personal computers, laptop computers, monitors, mobile phones, and digital cameras are all products that use liquid crystal display devices in large quantities. As the use expands, the place and location to put it also become diverse. However, when viewed from a direction other than the front of the liquid crystal display device, that is, outside the viewing angle, the clarity of the image is reduced. Therefore, there is a problem of using a viewing angle compensation film to improve the viewing angle.

Conventional viewing angle compensation films utilize single or random microstructures to increase viewing angles. However, as shown in FIG. 1A , compared with the light type without the conventional viewing angle compensation film, the light field with the conventional viewing angle compensation film is more obviously inhomogeneous than the light type as shown in FIG. 1A . In addition, as shown in the light-type dark state simulation results shown in FIG. 1B , the dimensionless brightness with conventional viewing angle compensation film (indicated by the solid line) is significantly greater than that without the viewing angle compensation film (indicated by the dotted line), that is, the light leakage in the dark state is more obvious, which easily leads to poorer contrast.

The purpose of the present invention is to provide a viewing angle compensation film, which can widen the viewing angle and has better light field uniformity.

The viewing angle compensation film of the present invention includes a microstructure layer and a protective layer. The microstructure layer has a first surface and a second surface on opposite sides, including a plurality of first grooves and a plurality of second grooves. A plurality of first grooves are recessed from the first surface and have a first depth, and a plurality of second grooves are recessed from the first surface and have a second depth. Wherein, the first groove and the second groove are mixedly distributed, and the first depth and the second depth are not equal. The protective layer covers the first surface and fills the first groove and the second groove, and the refractive index of the protective layer is greater than that of the microstructure layer.

The display device of the present invention includes a display panel having a display surface and a viewing angle compensation film. The viewing angle compensation film is arranged on the display surface, and the microstructure layer is interposed between the display surface and the protection layer.

The implementation of the connection assembly disclosed in the present invention will be described below through specific specific embodiments and accompanying drawings. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. However, the content disclosed below is not intended to limit the protection scope of the present invention. Those skilled in the art can implement the present invention in other different embodiments based on different viewpoints and applications without departing from the spirit of the present invention. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Throughout the specification, the same reference numerals denote the same elements. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” or “connected to” another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected" may refer to physical and/or electrical connection. Furthermore, "electrically connected" or "coupled" means that other elements exist between two elements.

It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a "first element," "component," "region," "layer" or "section" discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.

Additionally, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe one element's relationship to another element as shown in the figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. Thus, the exemplary term "below" can encompass both an orientation of "below" and "upper," depending on the particular orientation of the drawing. Similarly, if the device in one of the figures is turned over, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "below" or "under" can encompass both an orientation of above and below.

As used herein, "about," "approximately," or "substantially" includes stated values and averages within acceptable deviations from the particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and the particular amount of error associated with the measurement (i.e., limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, "about", "approximately" or "substantially" used herein may select a more acceptable deviation range or standard deviation according to optical properties, etching properties or other properties, and one standard deviation may not be applicable to all properties.

As shown in the embodiment shown in FIG. 2 , the viewing angle compensation film 800 of the present invention includes a microstructure layer 100 and a protective layer 200, which can be made of organic or inorganic materials such as glass, optically transparent substrates such as acrylic, resin, etc., and is used as a viewing angle compensation film for a display device 900. Furthermore, the display panel 300 has a display surface 310 facing the user. The display surface 310 is located in an area of the display panel 300 capable of displaying images, which is commonly referred to as an active area (AA) in the art. The viewing angle compensation film 800 is disposed on the display surface 310 and can redistribute the light field, which helps to improve the viewing angle (Viewing Angle), thereby enhancing the user's viewing comfort of the display panel 300 . In terms of the type of display medium, in this embodiment, the display panel 300 may be a liquid crystal display panel (liquid crystal display, LCD); however, the present invention is not limited thereto, and in other embodiments, the display panel 300 may also be an organic light emitting diode display panel (organic light emitting diode, OLED), a micro light emitting diode display panel (micro-LED display) or other appropriate types of display panels. In terms of flexibility, in this embodiment, the display panel 300 may be a rigid display panel; however, the present invention is not limited thereto, and in other embodiments, the display panel 300 may also be a flexible display panel.

More specifically, as shown in FIG. 3A , the viewing angle compensation film 800 of the present invention includes a microstructure layer 100 and a protective layer 200 . The microstructure layer 100 has a first surface 101 and a second surface 102 on opposite sides, and the second surface 102 (that is, the side that is in contact with the display surface 310 shown in FIG. 2 ) is the light incident side. The microstructure layer 100 includes a plurality of first grooves 110 and a plurality of second grooves 120 distributed in a mixed manner. The plurality of first grooves 110 are recessed from the first surface 101 and have a first depth H1, and the plurality of second grooves 120 are recessed from the first surface 101 and have a second depth H2. Further, in this embodiment, the sidewalls of the first groove 110 and the second groove 120 are straight planes, and turn into curved surfaces when approaching the bottom. The first depth H1 and the second depth H2 respectively refer to the depths from the first surface 101 inwardly recessed to the junction of the straight plane sidewalls and the curved surface, that is, the depths excluding the curved portion of the bottom. The first depth H1 and the second depth H2 are not equal. In one embodiment, the first depth H1 is smaller than the second depth H2, that is, .

The first groove 110 and the second groove 120 can be formed simultaneously when the microstructure layer 100 is formed by injection molding technology, or can be formed separately after the formation of the microstructure layer 100, for example, using chemical vapor deposition to deposit the same material as the microstructure layer 100, or removing part of the microstructure layer 100 by etching, machining, sandblasting, laser engraving, etc. Wherein, in the embodiment shown in FIG. 3B , the first grooves 110 and the second grooves 120 may be parallel to each other and not intersect each other, so that a strip structure is formed between the grooves. In different embodiments as shown in FIG. 3C , the first grooves 110 and the second grooves 120 can be further staggered, so that an island structure is formed between the grooves. In addition, the staggered manner between grooves is not limited to vertical staggered. On the other hand, the arrangement of the grooves may be a regular pattern in which the first grooves 110 and the second grooves 120 are alternately and continuously repeated as shown in FIG. 3B , or an irregular pattern as shown in FIG. 3D . Furthermore, in a specific area, at least one first groove 110 and one second groove 120 are respectively provided, that is, two groups of grooves with different depths are provided. Wherein, the specific region may be any region whose length and width are greater than 0.8 μm.

In the embodiment shown in FIG. 3A , the protection layer 200 covers the first surface 101 and fills up the first groove 110 and the second groove 120 . Wherein, the protective layer 200 may be provided by, for example, spin coating, brushing, spraying and the like. Viewed from different angles, the protection layer 200 extends from the outside of the first surface 101 into the first groove 110 and the second groove 120 of the microstructured layer 100 . The refractive index of the protection layer 200 is greater than that of the microstructure layer 100 .

On the other hand, in the embodiment shown in FIG. 3A , there is a first included angle θ1 between the sidewall of the first groove 110 and the normal direction of the second surface 102 , and there is a second included angle θ2 between the sidewall of the second groove 120 and the normal direction of the second surface 102 . More specifically, the first angle θ1 is the angle between the straight sidewall of the first groove 110 and the normal direction of the second surface 102 , and the second angle θ2 is the angle between the straight sidewall of the second groove 120 and the normal direction of the second surface 102 . Wherein, the first included angle θ1≦the second included angle θ2. In one embodiment, 65°≦the first included angle θ1≦the second included angle θ2≦86°, so as to obtain a better light-diffusing effect. More specifically, in the embodiment shown in Figure 4A, an optical viewing angle detector (EZContrast XL88, Eldim, France) is used to detect the light intensity distribution of a bright panel without a viewing angle compensation film. It can be found that the dimensionless brightness within the viewing angle range of about ±35° is above 0.5, that is, the light intensity in this area is relatively strong. 65°≦the first included angle≦the second included angle≦86° can further refract the light in this region to a region with a larger viewing angle range (for example, to about ±45°), that is, to obtain a better light-diffusing effect. Wherein, the viewing angle is the included angle between the user's eyes 400 and the normal direction of the display surface 310 (see FIG. 2 ) of the display panel 300 . For example, when the user is facing the display surface 310, the angle between the eyes 400 and the normal direction of the display surface 310 is 0, and the viewing angle is 0; when the user is on both sides of the display surface 310, the angle between the eyes 400 and the normal direction of the display surface 310 is 90°, and the viewing angle is ±90°.

In addition, in one embodiment, 70°≦the first included angle θ1≦the second included angle θ2, so as to avoid the increase of the light leakage caused by the front view. More specifically, in the embodiment shown in FIG. 4B , the light intensity distribution of the dark-state panel without viewing angle compensation film is detected, and it can be found that the dark-state light leakage between the viewing angle ranges of about -70° to -40° and 40° to 70° is relatively large. 70°≦the first included angle θ1≦the second included angle θ2 can avoid further refraction of the light in the range of -70° to -40° and 40° to 70° to within the range of viewing angle to about ±20°, so as to avoid the increase of light leakage in frontal view and the decrease of contrast.

The light intensity distributions of the panels in the bright state and dark state without the viewing angle compensation film and with the viewing angle compensation film of the present invention were tested respectively, and the results are shown in FIGS. 5A and 5B . Among them, the specification of the viewing angle compensation film of the present invention is that the refractive index of the protective layer is 1.61, the refractive index of the microstructure layer is 1.51, the first included angle θ1=81°, θ2=86°, the first depth H1=3 μm, and the second depth H2=5 μm. As shown in Figure 5A, from the perspective of the light pattern without the viewing angle compensation film (shown by the dotted line), the viewing angle range of the non-dimensionalized lightness above 0.5 (that is, the brightness above 50%) is within ±35°. On the contrary, judging from the light type provided with the viewing angle compensation film of the present invention (indicated by the solid line), the viewing angle range of the non-dimensionalized lightness above 0.5 can be expanded to within about ±45°. Accordingly, the viewing angle compensation film of the present invention can achieve the effect of widening the viewing angle. In addition, since the light pattern provided with the viewing angle compensation film of the present invention presents a smooth curve, it can be seen that the uniformity of the light field is better. As shown in the results of Figure 5B, in terms of light leakage in the dark state in the range of viewing angles between -70° to -40° and 40° to 70°, the dimensionless brightness without the viewing angle compensation film (indicated by the dotted line) is significantly greater than that with the viewing angle compensation film of the present invention (indicated by the solid line). Accordingly, the viewing angle compensation film of the present invention can achieve the effects of reducing dark state light leakage and improving contrast.

On the other hand, the top or bottom of the first groove 110 and the second groove 120 may have a curved design, thereby making the light curve smoother, that is, the uniformity of the light field is better. The possible reason is that the curved surface can refract the light to different angles, so it is not easy to refract only to a single direction, which can make the light field more uniform. More specifically, in the embodiment shown in FIG. 3A , the bottoms of the first groove 110 and the second groove 120 are concave curved surfaces, and there is a plane interval between the first groove 110 and the second groove 120 , that is, the bottom has a curved surface design. In the embodiment shown in FIG. 6A , the bottoms of the first groove 110 and the second groove 120 are concave curved surfaces, and the space between the first groove 110 and the second groove 120 has a convex curved surface, that is, both the top and the bottom have curved surface designs. In the embodiment shown in FIG. 6B , the bottoms of the first groove 110 and the second groove 120 are flat, and the gap 120 between the first groove 110 and the second groove has a convex curved surface, that is, the top has a curved surface design. In the embodiment shown in FIG. 6C , the bottoms of the first groove 110 and the second groove 120 are flat, and the distance 120 between the first groove 110 and the second groove has a plane interval, that is, there is no curved surface design. Among them, in terms of making the light curve smoother and making the uniformity of the light field better, the embodiment shown in FIG. 3A is better than or equal to the embodiment shown in FIG. 6A , better than the embodiment shown in FIG. 6B , and better than the embodiment shown in FIG. 6C . Furthermore, the curved surface can refract the light at different angles to make the light field more uniform, but the flat top design is conducive to the direct penetration of the light from the front view, which helps to improve the penetration rate.

The present invention has been described by the above-mentioned related embodiments, but the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and equivalent arrangements included in the spirit and scope of the patent claims are included in the scope of the present invention.

100: microstructure layer 101: First Surface 102: second surface 110: the first groove 120: second groove 200: protective layer 300: display panel 310: display surface 800: viewing angle compensation film 900: display device H1: first depth H2: second depth θ1: the first included angle θ2: second included angle

FIG. 1A is a diagram showing simulation results of light-type bright states with and without a conventional viewing angle compensation film.

FIG. 1B is a graph showing simulation results of light-type dark states with and without a conventional viewing angle compensation film.

FIG. 2 is a schematic diagram of an embodiment of the viewing angle compensation film of the present invention disposed on a display panel.

FIG. 3A is a schematic diagram of an embodiment of the viewing angle compensation film of the present invention.

3B to 3D are schematic perspective views of embodiments of the microstructure layer in the viewing angle compensation film of the present invention.

FIG. 4A is a graph showing the detection results of the light intensity distribution of the bright panel without the viewing angle compensation film of the present invention.

FIG. 4B is a graph showing the detection results of light intensity distribution of a panel in a dark state without the viewing angle compensation film of the present invention.

FIG. 5A is a graph showing the detection results of light intensity distribution of a bright panel with a viewing angle compensation film of the present invention.

FIG. 5B is a graph showing the detection results of light intensity distribution of a panel in a dark state provided with a viewing angle compensation film of the present invention.

6A to 6C are schematic diagrams of different embodiments of the viewing angle compensation film of the present invention.

100: microstructure layer

101: First Surface

102: second surface

110: the first groove

120: second groove

200: protective layer

800: viewing angle compensation film

H1: first depth

H2: second depth

θ1: the first included angle

θ2: second included angle

Claims (10)

A viewing angle compensation film comprising: a microstructure layer having a first surface and a second surface located on opposite sides, the microstructure layer comprising: a plurality of first grooves, concave from the first surface and having a first depth; The refractive index is greater than the refractive index of the microstructure layer, wherein the bottoms of the first grooves and the second grooves are concave curved surfaces, the tops of the intervals between the first grooves and the second grooves are planes, and the side walls connecting the tops and bottoms of the intervals between the first grooves and the second grooves are straight planes. The viewing angle compensation film as claimed in claim 1, wherein the first grooves and the second grooves are parallel to each other. The viewing angle compensation film as described in Claim 1, wherein 0<

<1, there is a first included angle between the sidewalls of the first grooves and the normal direction of the second surface, a second included angle between the sidewalls of the second grooves and the normal direction of the first surface, and the first included angle≦the second included angle. The viewing angle compensation film according to claim 3, wherein 65°≦the first included angle≦the second included angle≦86°. The viewing angle compensation film according to claim 4, wherein 70°≦the first included angle≦the second included angle≦86°. The viewing angle compensation film according to claim 1, wherein the bottom of at least one of the first grooves and the second grooves is a concave curved surface. The viewing angle compensation film according to claim 6, wherein there is an interval between the openings of the first grooves and the second grooves. The viewing angle compensation film according to claim 1, wherein the second surface is a light incident side. The viewing angle compensation film according to claim 1, wherein the first groove and the second groove are arranged continuously and repeatedly. A display device, comprising: a display panel having a display surface; and the viewing angle compensation film according to any one of claim 1 to claim 9, which is disposed on the display surface, and the microstructure layer is interposed between the display surface and the protective layer.

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