JP2005274676A - Reflection coating and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide reflection coating capable of efficiently reflecting irradiated light without unevenness and a liquid crystal display device using the same. <P>SOLUTION: The reflection coating 12 is laminated on the surface of organic film 11. A recessed part 31 is formed on the reflection coating 12 by a recessed part formed on the surface of the organic film 11. As for the recessed part 31, for example, an opening surface 31a is circularly formed and recessed in the thickness direction. The recessed part 31 is formed between the adjacent recessed parts 31 at an interval of t1. In a gap formed between the mutually adjacent recessed parts 31, a rough surface 32 on the surface of which fine irregularity is formed is formed. Such rough surface 32 for filling the openings 31a of the recessed part 31 is constituted of irregularity extremely smaller than depth (gap) and width of the recessed part 31. Such rough surface 32 irregularly reflects light made incident on the rough surface 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflective film having a large number of fine concave portions or convex portions formed on the surface, and a liquid crystal display device including the same.

For example, a reflective liquid crystal display device includes a reflective film that reflects incident external light toward a liquid crystal display panel. Such a reflective film is formed of a highly reflective material such as an Al thin film, and further has a surface in which fine concave portions and convex portions are formed in order to diffusely reflect incident external light without unevenness. (For example, refer to Patent Document 1).
JP 2003-14912 A

  FIG. 8 shows a reflective film having fine concave portions formed on the surface. The reflective film 101 is entirely formed of a highly reflective material such as an Al thin film, and a large number of fine concave portions 102 are formed on the surface. In the recess 102, the opening surface 102a has a hexagonal shape, for example, and the recesses 102 adjacent to each other are densely formed without a gap. By providing such a fine recess 102, the light incident on the reflective film 101 can be diffusely reflected without unevenness.

  However, as shown in FIG. 9, the conventional reflective film 101 as described above is formed so that the recesses 102 adjacent to each other are densely formed without gaps, so that the top portions 102b of the adjacent recesses 102 become extremely narrow, When the concave portion 102 was formed, the top portion 102b easily collapsed. For this reason, as compared with the cross section of the designed concave portion indicated by the dotted line R in FIG. 9, the shape of the actually formed concave portion 102 is broken, and it is difficult to obtain the desired reflection characteristics.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reflective film capable of efficiently reflecting incident light without unevenness and a liquid crystal display device including the same. .

  In order to achieve the above object, according to the present invention, there is provided a reflective film in which a large number of fine concave portions or convex portions are formed on the surface of a light reflective material, and the concave portions or convex portions are adjacent concave portions or convex portions. There is provided a reflective film characterized in that it is formed with a certain interval between the convex portions and a rough surface is formed between the concave portions or the convex portions adjacent to each other.

  The rough surface may be a minute uneven surface on which unevenness smaller than the gap between the recesses or the protrusions is formed. It is preferable to set the gap between the concave portion or the convex portion in a range of 0 to 1/3 of the average longest diameter of the concave portion or the convex portion. You may set the maximum inclination angle of the said rough surface so that it may become the same as the maximum inclination angle of the said recessed part or a convex part. And according to the liquid crystal display device provided with such a reflective film and a liquid crystal display panel, a liquid crystal display device capable of high-intensity and clear display can be provided.

  According to such a reflective film, when the concave portions formed in the reflective film are spaced apart from each other, when the concave portions are formed in the reflective film, the adjacent concave portions are connected to each other and the top portion collapses. Is prevented. Therefore, the recess can be formed with the accuracy as designed, and the desired reflection characteristics can be obtained.

  In addition, by forming a rough surface in the gap formed between the adjacent recesses, the gap between the adjacent recesses 31 becomes a mirror surface, and the incident light is strongly reflected in one direction. This prevents the visibility of the liquid crystal display device from being lowered. A rough surface formed in a gap between adjacent concave portions diffuses incident light to keep the luminance of the liquid crystal display device uniform.

  Furthermore, the rough surface of the small unevenness formed in the gap between the adjacent recesses is a predetermined range after processing the surface of the master blank with a roughness corresponding to this rough surface in advance when forming the master block. By forming a minute concave portion (convex portion) having a depth, the surface of the master blank can be filled without leaving a mirror surface, so that the time for forming the concave and convex portions can be shortened.

  Hereinafter, an example in which the reflective film of the present invention is applied to a transflective liquid crystal display device will be described as an embodiment of the present invention, but the present invention is not limited to the following embodiment. FIG. 1 is a diagram schematically showing a partial cross-sectional structure including an end portion of a transflective liquid crystal display device provided with a reflective film of the present invention. In FIG. 1, a liquid crystal display panel 2 constituting a liquid crystal display device 1 includes a first substrate 10 and a second substrate 20 made of transparent glass that are opposed to each other with a liquid crystal layer 30 interposed therebetween. In this configuration, the peripheral portions of the substrates 10 and 20 are bonded and integrated with a sealing material 40 provided in an annular shape.

  On the liquid crystal layer 30 side of the first substrate 10, in order, an organic film 11 for giving a fine recess 31 to the reflective film 12, a reflective film 12 for reflecting light incident on the liquid crystal display device 1, and a color The color filter 13 for displaying, the organic film 12 and the reflective film 13 are covered and protected, the overcoat film 14 for flattening the unevenness due to the organic film 11 and the color filter, and the liquid crystal layer 30 are driven. An electrode layer 15 for forming the liquid crystal layer 30 and an alignment film 16 for controlling the alignment of the liquid crystal molecules constituting the liquid crystal layer 30 are laminated. In addition, an electrode layer 25, an overcoat film 24, and an alignment film 26 are sequentially stacked on the liquid crystal layer 30 side of the second substrate 20.

  A polarizing plate 18 is provided on the side opposite to the liquid crystal layer 30 side of the first substrate 10 (the outer surface side of the first substrate 10), and the side opposite to the liquid crystal layer 30 side of the second substrate 20 (second side). The phase difference plate 27 and the polarizing plate 28 are laminated in this order on the outer surface side of the substrate 20. In addition, a backlight 5 as a light source for performing transmissive display in the liquid crystal display device 1 is disposed outside the polarizing plate 18 of the first substrate 10.

  The organic film 11 is provided in order to efficiently scatter reflected light by forming a recess 31 in the reflective film 12 formed thereon. By forming the concave portion 31 in the reflective film 12 in this manner, light incident on the liquid crystal display device 1 can be efficiently reflected, so that bright display in the reflection mode can be realized.

  FIG. 2 is a partially enlarged perspective view showing the detailed structure of the reflective film of the present invention, and FIG. 3 is an enlarged sectional view thereof. A reflective film 12 is laminated on the surface of the organic film 11. A recess 31 is formed in the reflective film 12 by the recess formed on the surface of the organic film 11. For example, the recess 31 has a circular opening surface 31a and is recessed in the thickness direction. Such an opening surface 31a may be, for example, hexagonal or rectangular other than circular. The recess 31 is formed with an interval t1 between the adjacent recesses 31. The interval t1 between the recesses 31 is preferably set to about 0 to 1/3 of the average longest diameter of the recesses 31, for example.

  The gap formed between the recesses 31 adjacent to each other forms a rough surface 32 having fine irregularities formed on the surface. The average depth (height) of the rough surface 32 is 0.1 to 1 μm, and the area ratio relative to the entire surface is set to 0.4 to 49%. Such a rough surface 32 diffusely reflects light incident on the rough surface 32.

  In this way, by forming the recesses 31 formed in the reflection film 12 by the interval t1, when forming the recesses 31 in the reflection film 12, the adjacent recesses 31 are connected to each other, and the top portion may collapse. Is prevented. However, since the unevenness depth of the rough surface 32 formed in the portion t1 is small, the degree of influence on the reflection characteristics can be reduced. Accordingly, the recess 31 can be formed with the accuracy as designed, and the desired reflection characteristics can be obtained.

  In addition, by opening the recesses 31 by a distance t1 and forming a rough surface 32 in this gap, the gap between adjacent recesses 31 becomes a mirror surface, and the incident light is strongly reflected in one direction. The visibility of the liquid crystal display device 1 is prevented from being lowered. The rough surface 32 formed in the gap between the adjacent recesses 31 diffuses the incident light to keep the luminance of the liquid crystal display device 1 uniform.

  For example, the recesses 31 are randomly formed with a depth in the range of 0.1 μm to 3 μm, the pitches of the adjacent recesses 31 are randomly arranged in the range of 5 μm to 50 μm, and the inclination angle of the inner surface of the recess 31 is −30 degrees to It is desirable to set in the range of +30 degrees. In particular, it is particularly important that the inclination angle distribution of the inner surface of the recess 31 is set in a range of −30 degrees to +30 degrees and that the pitch of the adjacent recesses 31 is randomly arranged in all directions in the plane. This is because, if the pitch between the adjacent recesses 31 is regular, there is a problem that the interference color of light is emitted and the reflected light is colored.

  On the other hand, if the inclination angle distribution on the inner surface of the recess 31 exceeds the range of -30 degrees to 30 degrees, the diffusion angle of the reflected light is excessively widened, the reflection intensity is lowered, and a bright display cannot be obtained (the diffusion angle of the reflected light). This is because it becomes 36 degrees or more in the air, the reflection intensity peak inside the liquid crystal display device decreases, and the total reflection loss increases. Furthermore, when the depth of the concave portion 31 exceeds 3 μm, when the concave portion 31 is planarized in a subsequent process, the top of the convex portion cannot be filled with the planarizing film (overcoat film 14), and a desired flatness can be obtained. This will cause display unevenness.

  When the pitch of the adjacent recesses 31 is less than 5 μm, there is a restriction on the production of a transfer mold used for forming the organic film 11, and the processing time is extremely long, and a shape capable of obtaining desired reflection characteristics is formed. Inability to generate interference light occurs. In practice, when a diamond indenter having a diameter of 30 μm to 100 μm that can be used for manufacturing the transfer mold is used, it is desirable that the pitch of the adjacent recesses 31 be 5 μm to 50 μm.

  FIG. 4 is an example of a concavo-convex shape showing good reflection characteristics. The inner surface shape of the concave portion 31 formed in the reflective film 12 in the specific longitudinal section X includes a first curve A from one peripheral portion S1 of the concave portion 31 to the deepest point D, and the concave portion 31 continuously to the first curve A. It is a curve shape consisting of the second curve B extending from the deepest point D to the other peripheral portion S2. These curves A and B are connected to each other at the deepest point D of the recess 31 so that the inclination angle with respect to the flat surface S is zero.

  The inclination angle of the first curve A with respect to the flat surface S is steeper than the inclination angle of the second curve B, and the deepest point D is at a position shifted from the center O of the recess 31 in the x direction. That is, the average value of the absolute value of the inclination angle of the first curve A with respect to the flat surface S is larger than the average value of the absolute value of the inclination angle of the second curve B with respect to the flat surface S. Also in this embodiment, it is preferable that the average value of the absolute values of the inclination angles of the first curve A constituting each of the plurality of formed recesses 31 varies irregularly within a range of 1 to 89 °. Moreover, it is preferable that the average value of the absolute value of the inclination angle of the second curve B of each recess 31 also varies irregularly within a range of 0.5 to 88 °.

  Since the inclination angles of both the curves A and B change gently from the periphery of the recess 31 to the deepest point D, the maximum inclination angle δa of the first curve A shown in FIGS. ) Is larger than the maximum inclination angle δb of the second curve B. Moreover, the inclination angle with respect to the flat surface S of the deepest point D where the first curve A and the second curve B are in contact with each other is zero, and the curves A and B having different inclination angles at the deepest point D are gentle. It is continuous.

  For example, the maximum inclination angle δa of each recess 31 varies irregularly within a range of 2 to 90 °. However, many of the recesses 31 vary irregularly within a range of the maximum inclination angle δa of 4 to 35 °. 4 and 5 has a single minimal point (a point on the curved surface where the inclination angle is zero) D. The distance between the local minimum point D and the flat surface S forms the depth d of the recess 31. The depth d varies irregularly within a range of 1 to 3 μm for each of the formed recesses 31. .

  The first curves A of the plurality of recesses 31 are preferably oriented in a single direction. By setting it as such a structure, the direction of the reflected light reflected by the reflecting film 12 can also be shifted to the specific direction from the direction of regular reflection. As a result, the overall reflection characteristic of the specific longitudinal section is one in which the reflectance in the direction reflected by the surface around the second curve B is increased, and the reflection characteristic is obtained by concentrating the reflected light in the specific direction. You can also. In FIG. 6, the semi-transmissive reflective film in which the first curve A of the concave portion 31 is oriented in a single direction is irradiated with external light at an incident angle of 30 °, and the light receiving angle is the direction of regular reflection with respect to the flat surface S. The relationship between the light receiving angle (θ °) and the brightness (reflectance) when swung from the perpendicular position (0 °) to 60 ° of the transflective film around 30 ° is shown.

  As is clear from FIG. 6, in the transflective film in which the first curve A is oriented in a single direction, the reflection characteristic is high in a wide range of 20 ° to 50 °, and the angle of regular reflection with respect to the flat surface S The integrated value of the reflectance at the light receiving angle smaller than 30 ° is larger than the integrated value of the reflectance at the light receiving angle larger than the regular reflection angle. That is, a larger reflection intensity can be obtained in the vicinity of a light receiving angle of 20 °.

  In the embodiment described above, the concave portion is formed in the reflective film. However, in addition to this, for example, as shown in FIG. 7, a fine convex portion 72 is formed on the surface of the reflective film 71 with a certain gap t2. The rough surface 73 may be formed in a gap between the convex portions 72.

  The present applicant verified the effect of the reflective film of the present invention. In the verification, a reflective film in which a large number of dimples K shown in the schematic diagram of FIG. 10 was formed was used. The dimple K has a radius of curvature of 25 μm, a depth of 15 μm, and a maximum inclination angle of 17.5 °. Then, using a plurality of samples in which the distance d between adjacent dimples K was set to 0, 5, and 10 μm, the relationship between the light receiving angle and the relative reflection intensity was measured. Such verification results are shown in FIG.

  According to the verification result shown in FIG. 11, by setting the distance d between the dimples K to 5 μm or less, it is possible to make the relative reflection intensity almost 90% or more in the light receiving angle range of 10 ° to 50 °. It was confirmed.

  Table 1 shows the relationship between the distance d and the relative reflection intensity. Also from Table 1, it was confirmed that the relative reflection intensity could be in the range of 100 to 90% if the distance d was kept in the range of 0 to 5 μm.

FIG. 1 is a perspective view showing a liquid crystal display device provided with the reflective film of the present invention. FIG. 2 is a partially enlarged perspective view of the reflective film shown in FIG. FIG. 3 is a partially enlarged cross-sectional view of the reflective film shown in FIG. FIG. 4 is a perspective view schematically showing a recess formed in the reflective film. FIG. 5 is a cross-sectional view showing the inner surface shape in the vertical cross section X of the recess shown in FIG. FIG. 6 is a graph showing an example of the reflection characteristics of the transflective film. FIG. 7 is a partially enlarged cross-sectional view showing another embodiment of the present invention. FIG. 8 is a partially enlarged perspective view showing a conventional reflective film. FIG. 9 is an explanatory view showing a conventional reflective film. FIG. 10 is a schematic diagram showing a reflective film used for verification of the present invention. FIG. 11 is a graph showing the verification results of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display panel 12 Reflective film 31 Concave part 32 Rough surface 72 Convex part

Claims (5)

A reflective film in which a number of fine recesses or protrusions are formed on the surface of the light reflective material,
The concave portion or the convex portion is formed with a certain interval between the adjacent concave portion or convex portion, and a rough surface is formed between the adjacent concave portions or convex portions. .   2. The reflective film according to claim 1, wherein the rough surface is a minute uneven surface on which unevenness smaller than a gap between the concave portion or the convex portion is formed.   The reflective film according to claim 1 or 2, wherein a gap between the concave portion or the convex portion is set in a range of 0 to 1/3 of an average longest diameter of the concave portion or the convex portion.   The reflective film according to claim 1, wherein a maximum inclination angle of the rough surface is set to be the same as a maximum inclination angle of the concave portion or the convex portion. A liquid crystal display device comprising the reflective film according to claim 1 and a liquid crystal display panel.

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