TWI629497B - Anti-reflection optical film - Google Patents

Abstract

The invention provides an optical film. The optical film includes a base film, a rough layer, and an anti-reflection layer. The rough layer is provided on the base film and has a rough surface; the anti-reflection layer is provided on the rough surface. A cross section of the rough surface in a predetermined direction has a cross section curve. The reference curve can be derived from the section curve. Relative to the reference datum line, a part of the cross-sectional curve will be lower than the reference datum line to form valleys, and the ratio of the maximum depth to the maximum width of some of the valleys is not greater than 0.26.

Description

Anti-reflection optical film

The present invention relates to an optical film; specifically, the present invention relates to an anti-reflection optical film used in a display module.

Flat and curved display devices have been widely used in various electronic devices, such as mobile phones, personal wearable devices, televisions, host computers for transportation, personal computers, digital cameras, handheld video games, and the like. However, in order to improve the user's visual experience, the industry is still continuously improving the optical performance of the display device.

For example, the display surface of some display devices may cause glare due to external ambient light during use. In most use conditions, glare often causes visual discomfort for some users and affects the optical performance of the displayed image. In order to solve this problem, some conventional display devices add a high-haze layer with a rough surface on the display surface to reduce the occurrence of glare. However, when the haze is high, the user is liable to feel the unclear sense of white fog on the display surface due to the setting of the high haze layer.

In order to reduce the above-mentioned unclear sense of white fog, some conventional display devices may further plate an anti-reflection layer on the outer surface of the high-haze layer. However, the anti-reflection layer tends to have an uneven thickness, which affects the surface roughness of the high-haze layer, thereby affecting the overall optical performance.

The object of the present invention is to provide an optical film, which can improve the uniformity of the distribution of the anti-reflection layer disposed on the rough layer.

Another object of the present invention is to provide an optical film that can maintain a relatively close roughness after an anti-reflection layer is disposed on the rough layer.

Another object of the present invention is to provide an optical film, which can reduce the phenomenon that the reflectance is increased due to the difference in roughness caused by the anti-reflection layer on the rough layer.

Another object of the present invention is to provide a display module, which can balance the optical effects of reducing glare and reflectance.

The display module includes an optical film and a display panel. The display panel has a display surface, and the optical film is disposed on the display surface. The optical film includes a base film, a rough layer, and an anti-reflection layer. The base film has a bearing surface, and the bearing surface is opposite to one surface of the base film facing the display surface. The rough layer is disposed on the bearing surface and has a rough surface facing away from the bearing surface. The anti-reflection layer is distributed on the rough surface.

A cross section of the rough surface in a predetermined direction has a cross section curve. A virtual reference baseline can be derived from the cross-section curve. For example, the reference datum line may be a 75% elevation line of the cross section curve. Relative to the reference datum line, part of the cross section curve will be formed as a valley part below the reference datum line, and part will be formed as a peak part above the reference datum line; the ratio of the maximum depth to the maximum width of the valley part is not greater than 0.26. Therefore, the difference between the roughness of the overall optical film and the roughness of the rough surface itself after the anti-reflection layer is provided will be smaller, thereby reducing the increase in reflectance.

10‧‧‧ Optical diaphragm

30‧‧‧Display Panel

31‧‧‧display surface

100‧‧‧ basement membrane

110‧‧‧bearing surface

200‧‧‧ default orientation

210‧‧‧ Section

300‧‧‧ rough layer

310‧‧‧ Rough

311‧‧‧ recess

313‧‧‧ convex

330‧‧‧ Rough structure

350‧‧‧ Section curve

351‧‧‧Tanibe

352‧‧‧ valley bottom

353‧‧‧Peak

370‧‧‧ Reference Baseline

380‧‧‧reference datum

500‧‧‧Anti-reflective layer

700‧‧‧ rough curve

710‧‧‧average line

FIG. 1 is a schematic diagram of an embodiment of a display module according to the present invention; FIG. 2 is an exploded view of an embodiment element of an optical film of the present invention; FIG. 3 is a schematic sectional view of the embodiment shown in FIG. 2; Fig. 5 is a schematic diagram of an embodiment of a cross-sectional curve; Fig. 6 is a schematic diagram of an embodiment of a rough layer; and Fig. 7 is a schematic diagram of an embodiment obtained from a cross-sectional curve.

The invention provides an optical film and a display module using the optical film. The display module is preferably applicable to various displays, such as computer monitors, televisions, monitors, and automotive hosts. In addition, the display module can also be applied to display modules included in other electronic devices, such as display screens of mobile phones, digital cameras, handheld gaming instruments, and the like.

As shown in FIG. 1, the display module includes an optical film 10 and a display panel 30. The display panel 30 has a display surface 31, and the optical film 10 is disposed on the display surface 31. In a preferred embodiment, the optical film 10 has the optical effect of polarized light; in addition, the optical film 10 also has the effect of reducing glare. The display panel 30 is preferably a liquid crystal display panel, and can cooperate with a backlight module (not shown) to display images. However, in different embodiments, the display panel 30 may also be a self-luminous display panel, such as an organic light emitting diode panel, or other similar display panels such as an electrophoretic display panel.

In the embodiment shown in FIGS. 2 and 3, the optical film includes a base film 100, a rough layer 300, and an anti-reflection layer 500. The base film 100 has a bearing surface 110, and the bearing surface 110 is opposite to a surface of the base film 100 facing the display surface 31. The base film 100 is preferably a polarizer; however, in different embodiments, the base film 100 may be a film with other optical effects or a transparent film without special optical effects.

As shown in FIGS. 2 and 3, the rough layer 300 is disposed on the bearing surface 110 and has a rough surface 310 facing away from the bearing surface 110. The rough layer 300 includes a rough structure 330 distributed on the bearing surface 110, wherein the rough structure 330 is formed with a plurality of protrusions and pits therebetween; and the surface of the rough structure 330 is the rough surface 310. The material of the rough layer 300 is preferably a resin material, and is preferably made by a phase inversion method, such as a thermally induced phase separation method, a vapor induced phase separation method, a dry method, and a wet method. The anti-reflection layer 500 is disposed on the rough surface 310. In a preferred embodiment, the anti-reflection layer 500 may be made of metal oxide or other compound materials. The anti-reflection layer 500 can be formed on the rough surface 310 by various coating processes, coating processes, or other processes.

As shown in FIGS. 2 and 3, the section 210 of the rough surface 310 in a predetermined direction 200 has a section curve 350. The preset direction 200 is preferably a direction parallel to the bearing surface 110; in other words, the preset direction 200 falls on the X-Y plane shown in FIG. 2, for example, it can be an extension direction of any side on the rough surface 310. The cross section 210 in the preset direction 200 is preferably perpendicular to the bearing surface 110. For example, if the preset direction 200 is set on the rough surface 310 first, the rough layer 300 can be cut in the vertical direction along the preset direction 200 to A cross section 210 is obtained. The intersection of the cross section 210 and the rough surface 310 is the cross section curve 350. However, in practice, if the cross-section curve 350 is to be measured, it is not necessary to actually cut the rough layer 300, and the cross-section curve 350 on the cross-section 210 can be obtained only by detecting with the relevant instrument in the preset direction 200.

As shown in FIGS. 3 and 4, a virtual reference reference line 370 can be obtained from the cross-sectional curve 350. In a preferred embodiment, the reference datum line 370 is a 75% elevation line of the cross section curve 350 (100% is the highest elevation). For example, if the boundary between the bearing surface 110 and the section 210 is used as a reference line with an elevation of 0, each point on the section curve 350 can obtain a relative one of the elevation heights. After statistical analysis of these elevation heights, take the third (from below) The upper quartile height is used as the elevation of the reference baseline 370. Relative to the reference datum line 370, a portion of the cross-sectional curve 350 is lower than the reference datum line 370 and is formed as a valley portion 351, and a part is higher than the reference datum line 370 and is formed as a peak portion 353. The ratio of the maximum depth D to the maximum width W of the valley portion 351 is preferably not more than 0.26. Preferably, the average ratio of the maximum depth D and the maximum width W of each valley portion 351 is not greater than 0.26. More preferably, the ratio of the maximum depth D to the maximum width W of each valley 351 is not greater than 0.26. By controlling the aspect ratio of at least part of the valley portion 351, the thickness of the anti-reflection layer 500 arranged at the bottom of the valley portion 351 can be made more even, and the undulations on the outer surface of the anti-reflection layer 500 are more conformed to the undulations of the rough surface 310. Therefore, the difference between the roughness of the entire optical film after the anti-reflection layer 500 is provided and the roughness of the rough surface 310 itself will be smaller, thereby reducing the increase in reflectivity.

In addition, in this preferred embodiment, as shown in FIG. 4, each of the valley portions 351 has a valley bottom level 352; at least part of the valley bottom level 352 has a curvature radius R of not less than 1.4 μm. With this design, the curved surface of the valley bottom portion 352 is relatively smooth without being too sharp, so the anti-reflection layer 500 can be more uniformly distributed on the valley bottom portion 352 without an abnormal thickness increase. As a result, the roughness of the rough surface 310 can be maintained, and the situation of increased reflectance can be reduced.

As shown in FIG. 5, the cross section curve 350 has a plurality of peaks 353 located above the reference reference line 370. The average peak height P (relative to the bearing surface 110) can be obtained after the peak top elevations of the peaks 353 are averaged. In this preferred embodiment, the average peak height P and the reference baseline 370 The distance d is less than 1 μm; and preferably, the average peak height P is higher than the reference reference line 370. With this design, the overall height difference between the rough surface 310 and the rough surface 310 will not be too large, and it is easier to control the uniformity of the anti-reflection layer 500 disposed on the rough surface 310.

In addition, as shown in FIG. 4 and FIG. 5, if the valley portions 351 distributed on the cross-sectional curve 350 are included, each valley portion 351 includes a portion protruding outward from the rough surface 310 and a portion concaved. The ratio of the protruding portions of each valley portion 351 to the total length of the curve of each valley portion 351 is defined as the first ratio. In terms of the peak portions 353, each peak portion 353 will include a portion protruding outward and a portion recessed relative to the rough surface 310. The portion protruding from each peak portion 353 occupies the total length of the curve of each peak portion 353. The ratio is defined as the second ratio. In this preferred embodiment, the first ratio is smaller than the second ratio; in other words, the concave curve in the valley portion 351 occupies a relatively large portion. This can reduce the possibility of generating narrow gaps in the valley portion 351 when the two protrusion curves are brought into contact in the valley portion 351, and further reduce the thickness of the anti-reflection layer 500 due to the accumulation in the narrow gap.

As shown in FIG. 6, the rough surface 310 can define a virtual reference plane 380 at an elevation of 75%; for example, if the bearing surface 110 is used as a reference surface with an elevation of 0, the points on the rough surface 310 can be obtained respectively. One of the elevation heights; after statistical analysis of these elevation heights, the third (bottom-up) quartile height is taken as the elevation of the reference datum 380. The rough surface 310 is partially formed as a convex portion 313 higher than the reference reference surface 380, and is partially formed as a concave portion 311 below the reference reference surface 380. The concave portion 311 has a first projection area on the reference reference surface 380, and the convex portion 313 has a second projection area on the reference reference surface 380. In a preferred embodiment, the haze of the anti-reflection layer 500 after being superimposed on the rough layer 300 needs to be greater than 65%, and the ratio of the first projection area to the second projection area is preferably between 16% and 78.5%. Under the requirements of taking into account the high haze, it can still maintain a certain display clarity.

In a preferred embodiment, the roughness of the rough surface 310 in the reference length L in the preset direction 200 is between 0.25 μm and 1 μm. More preferably, the roughness may be about 0.5 μm. As shown in FIG. 7, the roughness here is preferably the centerline average roughness (Ra); in other words, the roughness curve 700 is obtained after the cross-section curve is processed by filtering out the influence of the slope. Then, an average line 710, such as a center line, is defined on the rough curve 700. Then, the absolute value of the elevation of the rough curve 700 with respect to the average line 710 within the reference length L is integrated and averaged (ie, divided by the reference length L) to obtain the centerline average roughness. As shown in the simulation results in the following table, when the other design factors are the same, the original roughness of the rough surface 310 of Model 2 is about 0.5 μm, and the overall roughness after adding the anti-reflection layer will be the smallest difference from the original roughness ( 0.02 μm); relatively speaking, the lowest overall reflectance (0.99%) can also be obtained.

With this design, the roughness of the rough surface 310 after the anti-reflection layer 500 is disposed is low. In addition, in different embodiments, the plurality of valleys 351 can also be defined by the rough curve 700 and the average line 710 described above, and designed with reference to the aspect ratio recommendations in the foregoing embodiments to achieve maintaining the roughness and The purpose of reducing the increase in reflectivity.

The present invention has been described by the above related embodiments, but the above embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the invention Around. On the contrary, modifications and equal settings included in the spirit and scope of the scope of patent application are all included in the scope of the present invention.

Claims (10)

An optical film includes: a base film having a bearing surface; a rough layer disposed on the bearing surface; wherein the rough layer has a rough surface opposite to the bearing surface; the rough surface is in a predetermined direction The upper section has a section curve; a reference datum line is obtained from the section curve, and the portion of the cross section curve below the reference datum line forms a plurality of valleys, and at least part of the ratio of the maximum depth to the maximum width of the valley does not Greater than 0.26; and an anti-reflection layer disposed on the rough surface; wherein the reference reference line is a 75% elevation line of the cross-sectional curve. The optical film according to claim 1, wherein each of the valleys has a valley bottom, and at least part of the valley bottom has a curvature radius of not less than 1.4 μm. The optical film according to claim 1, wherein an average peak height distance between the reference datum line and the cross-sectional curve is less than 1 μm. The optical film according to claim 1, wherein the rough surface defines a reference datum plane at an elevation of 75%; a portion of the rough surface lower than the reference datum plane has a first projection on the reference datum plane Area, a portion of the rough surface higher than the reference datum plane has a second projection area on the reference datum plane, and a ratio of the first projection area to the second projection area is between 16% and 78.5%. The optical film according to claim 1, wherein a part of the cross-section curve higher than the reference baseline forms a plurality of peaks, and the proportion of the valleys that protrude relative to the rough surface is smaller than the proportion of the valleys The proportion of the peaks that protrude relative to the rough surface among the peaks. The optical film according to claim 1, wherein the haze of the anti-reflection laminated on the rough layer is greater than 65%. An optical film includes: a base film having a bearing surface; a rough layer disposed on the bearing surface; wherein the rough layer has a rough surface opposite to the bearing surface; the rough surface is in a predetermined direction The upper section has a rough curve; an average line is obtained from the rough curve, and a portion of the rough curve below the average line forms a plurality of valleys, and at least part of the ratio of the maximum depth to the maximum width of the valley is not greater than 0.26 And an anti-reflection layer is disposed on the rough surface. The optical film according to claim 7, wherein each of the valleys has a valley bottom, and at least part of the valley bottom has a curvature radius of not less than 1.4 μm. The optical film according to claim 7, wherein the rough surface defines a reference datum plane at an elevation of 75%; a portion of the rough surface lower than the reference datum plane has a first projection on the reference datum plane Area, a portion of the rough surface higher than the reference datum plane has a second projection area on the reference datum plane, and a ratio of the first projection area to the second projection area is between 16% and 78.5%. The optical film according to claim 7, wherein a portion of the rough curve higher than the average line forms a plurality of peaks, and a proportion of the valleys that protrudes relative to the rough surface is smaller than the proportions of the valleys The proportion of the peaks that protrude relative to the rough surface in the peaks.