JP2011523102A - Optical element, backlight unit including the same, and liquid crystal display device - Google Patents

Abstract

The present invention relates to an optical element that enhances a condensing effect and has a wide viewing angle while maintaining luminance characteristics to the maximum in a liquid crystal display device, and a backlight unit including such an optical element and a liquid crystal display device It is. For this purpose, an embodiment of the optical element according to the present invention includes: a base film having optical transparency; a plurality of protrusions formed on at least one surface of the base film; and a plurality of peaks on a part of the protrusions. A fine optical pattern in which valleys are continuously formed. Meanwhile, another embodiment of the optical element according to the present invention includes: a base film having optical transparency; and a plurality of third fine optical patterns formed on at least one surface of the base film. The optical pattern is formed with a figure having a major axis and a minor axis at a portion in contact with the surface of the base film, and the height of the crest provided in the third fine optical pattern is along the major axis direction of the figure. It is formed so as to become lower from the center to both ends.

Description

  The present invention relates to an optical element used in a liquid crystal display device (LCD), and in particular, enhances a light collecting effect and has a wide viewing angle while maintaining high luminance characteristics to the maximum in the liquid crystal display device. The present invention relates to an optical element, a backlight unit including the optical element, and a liquid crystal display device.

  In general, optical elements widely used in a liquid crystal display (LCD) include a light guide plate, a diffusion plate, a prism sheet, and a liquid crystal panel. Such an optical element or the like is usually used for light diffusion, light collection, luminance improvement and the like of a liquid crystal display device. For example, in a backlight unit used in a liquid crystal display device, a light beam incident from a light source is converted into a surface light source through a light guide plate, diffused by a diffusion plate, and then incident below a prism sheet. At this time, the prism sheet can improve the brightness of the liquid crystal display device by collecting the incident light on the light exit surface.

  FIG. 1 is a schematic cross-sectional view of a conventional general liquid crystal display device.

  As shown in FIG. 1, the liquid crystal display device 10 is largely composed of a backlight unit (A) and a panel unit (B). The backlight unit (A) includes a light guide plate 12 and a diffusion plate 13 that diffusely emit light incident from the light source 10, and one or more prism sheets 14 that collect and emit light incident from the diffusion plate 13. A reflection polarizing film 15 that selectively reflects light incident from the prism sheet 14 and a phase delay layer 16 that converts circularly polarized light transmitted through the reflection polarizing film 15 into linearly polarized light are included. The panel unit (B) transmits the linearly polarized light out of the light emitted from the backlight unit (A), transmits the circularly polarized light through 50%, and absorbs the rest. A liquid crystal panel 18 for displaying a screen is included. Reference numeral 11 described is a reflector.

  In the case of various optical elements used in such a liquid crystal display device, technological development has been focused on improving the light collecting function for high luminance. This is because the LCD device is mainly used for personal electronic devices such as mobile and notebook computers. Therefore, in the case of such a personal electronic device, the viewing angle did not appear as a big problem. However, recently, LCD TVs have become larger, and many viewers can watch at the same time while becoming popular due to price cuts. In particular, vehicle navigation devices are used simultaneously in the driver's seat and auxiliary seat. A wide viewing angle is required for confirmation.

  On the other hand, conventionally, as an optical element having a wide viewing angle, a method of laminating a large number of diffusion sheets and a method of using a reflective polarizing film are used. The method of using a large number of the diffusion sheets has a limitation in increasing the brightness, and there is a disadvantage that the thickness of the product is increased by laminating a large number of sheets. The method of using the latter reflective polarizing film is a reflection Since the polarizing film is still a market-exclusive product, its price is high and the competitiveness of the product is reduced.

  Therefore, in the corresponding technical field, there has been a continuous demand for technological development for an optical element that has a wide viewing angle in a liquid crystal display device.

  The present invention has been proposed in order to solve the above-described problems of the prior art. In a liquid crystal display device, while maintaining high luminance characteristics to the maximum, it is slim, but at a low cost. The object is to provide an optical element that enhances the light effect and has a wide viewing angle.

  Another object of the present invention is to provide a backlight unit and a liquid crystal display device including such an optical element.

  In order to achieve the above object, an optical element according to an embodiment of the present invention includes a base film having light transmittance; a plurality of protrusions formed on at least one surface of the base film to diffuse incident light; A first fine optical pattern formed on the portion for collecting and emitting incident light.

  Here, the first fine optical pattern may have peaks and valleys continuously formed on a part of the convex portion.

  In one embodiment of the present invention, it may further include a second fine optical pattern that is formed on the other surface of the base film and collects and / or diffuses incident light. And valleys can be formed continuously.

  In one embodiment of the present invention, the first micro optical pattern and the second micro optical pattern may have their crests and valleys arranged in parallel to each other.

  In one embodiment of the present invention, the first fine optical pattern and the second fine optical pattern may be arranged such that respective peaks and valleys constitute a predetermined inclination angle.

  In one embodiment of the present invention, it is desirable that the convex portion has a diameter of 50 to 100 μm.

  In one embodiment of the present invention, the convex part is formed in a figure having a major axis and a minor axis, the major axis has a length of 50 to 100 μm, and the minor axis has a length of 1 to 100 μm. Can be configured.

  In one embodiment of the present invention, it is preferable that the height of the convex portion is 10 to 40 μm.

  In one embodiment of the present invention, the distance between the convex portions is preferably 50 to 150 μm.

  In one embodiment of the present invention, at least some of the plurality of convex portions may have different heights.

  In one embodiment of the present invention, it is preferable that the height of the peak of the first fine optical pattern is 5 to 30 μm.

  In one embodiment of the present invention, it is preferable that the first fine optical pattern has a peak width of 10 to 30 μm.

  In one embodiment of the present invention, the first micro optical pattern may be formed such that the heights of the peaks are different from each other.

  In one embodiment of the present invention, the first micro optical pattern may be formed at a central portion of each convex portion.

  In one embodiment of the present invention, the remaining portion of the convex portion where the first fine optical pattern is not formed may be formed in a shape curved with a constant curvature.

  Meanwhile, an optical element according to another embodiment of the present invention for achieving the above object includes a base film having optical transparency; and a plurality of optical elements that are formed on at least one surface of the base film to collect and diffuse incident light. Each of the third micro optical patterns is formed in a figure having a major axis and a minor axis at a portion in contact with the surface of the base film, and is provided in the third micro optical pattern. The height of the mountain is formed so as to decrease from the center to both ends along the long axis direction of the figure.

  Here, a plurality of third micro optical patterns are formed on one surface of the base film, and a fourth micro optical pattern is formed on the other surface of the base film so as to collect or / and diffuse incident light. Can be formed.

  In one embodiment of the present invention, the fourth fine optical pattern may have peaks and valleys continuously formed.

  In one embodiment of the present invention, the third micro optical pattern and the fourth micro optical pattern may be arranged such that each mountain forms a predetermined inclination angle.

  In one embodiment of the present invention, the crest of the third fine optical pattern may be configured to be curved to a constant radius of curvature along the elliptical long axis.

  In one embodiment of the present invention, it is desirable that the height of the central portion of the third fine optical pattern is 0.2 to 200 μm.

  In one embodiment of the present invention, it is preferable that the major axis and the minor axis of the figure forming the third fine optical pattern have a length of 1 to 5000 μm and 1 to 100 μm, respectively.

  In one embodiment of the present invention, the distance between the third fine optical patterns is preferably 1 to 5000 μm.

  In one embodiment of the present invention, the third micro optical pattern may be arranged in a matrix form.

  In one embodiment of the present invention, the third micro optical patterns may be arranged crossing each other.

  On the other hand, the present invention provides a backlight unit configured to include the optical element described in the above-described embodiments and the like, and a liquid crystal display device configured to include such a backlight unit.

  According to the present invention, a liquid crystal display device can realize a wide viewing angle by increasing the light condensing effect at a low cost.

  Further, according to the present invention, not only the luminance at the front but also the luminance at the side can be improved, and uniform luminance can be maintained over the entire screen of the liquid crystal display device.

It is a schematic sectional drawing of the conventional common liquid crystal display device. It is a top view which shows the optical element by 1st Example of this invention. It is the sectional view on the AA line of FIG. FIG. 4 is an enlarged view showing an essential part of FIG. 3 in an enlarged manner. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is sectional drawing which showed the other Example of the 1st micro optical pattern by this invention. It is the illustration which showed the modification of the optical element by 1st Example of this invention. It is a perspective view of the optical element by 2nd Example of this invention. It is a perspective view which shows CC of FIG. 1 is a schematic view illustrating a part of a liquid crystal display device including an optical element according to an embodiment of the present invention. 1 is a schematic view illustrating a part of a liquid crystal display device including an optical element according to an embodiment of the present invention. 1 is a schematic view illustrating a part of a liquid crystal display device including an optical element according to an embodiment of the present invention. It is a schematic perspective view of the optical element by 3rd Example of this invention. It is a schematic perspective view of the optical element by 3rd Example of this invention. It is sectional drawing and perspective view which show FF of FIG. It is sectional drawing which shows GG of FIG. It is a schematic perspective view of the optical element by 4th Example of this invention. It is a perspective view which shows HH of FIG. 6 is a diagram showing a result of simulating light paths in a conventional optical element and an optical element of the present invention. 6 is a diagram showing a result of simulating light paths in a conventional optical element and an optical element of the present invention. 1 is a schematic view illustrating a part of a liquid crystal display device including an optical element according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the optical element according to the present invention, the technical idea of the present invention can be widely applied to any structure normally used in a liquid crystal display device. Therefore, the optical element described below is provided as an example for explaining the present invention as a basic structure of an element used in a liquid crystal display device.

  By extension, in the following description of the present invention, if it is determined that a specific description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be given. Explanation may be omitted.

  FIG. 2 is a plan view showing an optical element according to the first embodiment of the present invention.

  Referring to FIG. 2, the optical element 100 according to the first embodiment of the present invention includes a base film 110 having light transmittance, a plurality of protrusions 120 formed on at least one surface of the base film 110, and the protrusions. A portion of the portion 120 includes a first fine optical pattern 130 in which a plurality of peaks 131 and valleys 132 are continuously formed.

  The base film 110 according to the present invention is selected from, for example, PC (Polycarbonate), PET (Polyester), PE (Polyethylene), PP (Polypropylene), and PMMA (Polymethly Methacrylate) as a material that transmits incident light. Including one.

  A plurality of convex portions 120 are formed on at least one surface of the base film 110. The protrusions 120 may be regularly formed over the entire surface of the base film 110 or in a partial section, or may be formed over the entire surface or irregularly in a partial section to form newton rings and wetouts ( Prevents the occurrence of wet-out). As shown in FIG. 2, the convex portion is a plane of the base film 110, and can have various shapes of cross sections such as a circle, an ellipse, a quadrangle, a triangle, and a rhombus when projected. Each of the convex portions 120 diffuses light incident on the base film 110 to induce a wide viewing angle.

  A first fine optical pattern 130 in which a plurality of peaks 131 and valleys 132 are continuously formed is formed on a part of each convex portion 120. In particular, the first fine optical pattern 130 is desirably formed in the central portion on the convex portion 120. Each of the first micro optical patterns 130 has a function of collecting and emitting light so that light incident on the base film 110 is substantially perpendicular to an upper liquid crystal panel (not shown).

  3 is a cross-sectional view taken along the line AA in FIG. 2, FIG. 4 is an enlarged view showing an essential part of FIG. 3, and FIG. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a sectional view showing another embodiment of the first micro optical pattern according to the present invention.

  Referring to FIG. 3, the protrusion 120 of the optical element 100 according to the first embodiment of the present invention has a protruding shape having a predetermined curvature, for example, a hemispherical shape on the base film 110. It is desirable to protrude. In other words, it is desirable that the convex portion 120 is a side surface of the base film 110 and has a semicircular or anti-elliptical shape during projection (see FIG. 3). The first fine optical pattern 130 includes a plurality of crests 131 and valleys 132 that are continuously formed, and is formed on a part of the convex part 120, and is preferably formed at the center of the convex part 120. Therefore, the remaining portion of the convex portion 120 where the first micro optical pattern 130 is not formed, that is, the side surface portion 121 shown in FIG. 3 can maintain the curved shape with a constant curvature. As shown in FIG. 4, the incident light incident from the lower part is collected by the first fine optical pattern 130 and emitted vertically at the upper part (N direction), and the side surface of the convex part 120. By being diffused and emitted by the unit 121 (R direction), the side luminance of the liquid crystal display device is improved. As a result, not only a sufficient viewing angle is secured, but also the function of the diffusion film is made parallel in the backlight unit.

  As shown in FIG. 3, the distance (A) between the convex portions 120 is preferably 50 to 150 μm, and the diameter (B) of the convex portion 120 is 50 to 100 μm. Is desirable. Here, the convex part 120 may be formed in a figure having a major axis and a minor axis when the base film 110 is projected on a plane, and the major axis is composed of 50 to 100 μm. It is desirable that the length is 1 to 100 μm. At the same time, it is desirable that the lengths of the major axis and the minor axis or each diagonal line be 50 to 100 μm even when each convex part 120 has an elliptical shape, a square shape, or a rhombus shape. Further, the height (C) of each convex portion 120 is desirably 10 to 40 μm. At least some of the plurality of convex portions 120 may have different sizes. Here, it is preferable that the size, height, spacing, and the like of the protrusions 120 are determined in consideration of the overall density, brightness, ease of manufacture, and the like. For example, in the case of the diameter and height of the convex part 120, if it is less than 50 μm, it is difficult to form the first fine optical pattern 130 on the upper part, and if it exceeds 100 μm, the overall luminance is rather lowered. Further, if the interval between the convex portions 120 is less than 50 μm, the side luminance characteristics are not improved, and if it exceeds 150 μm, the density is lowered and the luminance characteristics are deteriorated. However, the convex part 120 and the first micro optical pattern 130 are preferable examples, and can be designed by changing the numerical values according to the brightness and manufacturing characteristics of the product to be implemented. is there.

  As a result, the width (D) of the peak 131 of the first fine optical pattern 130 is preferably 10 to 30 μm, and the height (E) of the peak 131 is preferably 5 to 30 μm. Here, the height of the peak 131 of the first fine optical pattern 130 is preferably smaller than the height of the convex portion 120. In addition, each first fine optical pattern 130 may include a different number of peaks and valleys.

  At the same time, another fine optical pattern (not shown) can be formed on each mountain. That is, like the first fine optical pattern 130 mentioned above, the peak and valley are formed to be continuously repeated, and the light collection efficiency with respect to the incident light incident on the base film 110 is maximized. is there.

  Referring to FIG. 5, the optical device according to the first embodiment of the present invention has a peak of the first micro optical pattern 130 formed on a part of each convex portion 120 as shown in FIG. 5 as an example. 131 can be curved with a constant curvature to form an arc. That is, the peak 131 of the first micro optical pattern 130 can be formed so that the height decreases from the center to both ends. However, the present invention is not limited to such a structure, and as another example, as shown in FIG. 5, the peaks 131 of the first fine optical pattern 130 can maintain the same height. In other words, as shown in FIGS. 3 and 5, substantially triangles may be formed in a continuously arranged shape in any one direction, and at this time, the first micro optical pattern 130 may be formed. As shown in FIG. 5, it is preferable that the peak 131 is formed so as not to take off the circular arc.

  Meanwhile, the optical element 100 according to the first embodiment of the present invention can be used in a backlight unit and a liquid crystal display device. In this case, it is desirable that the plurality of convex portions 120 be formed on the upper surface of the base film 110. Thus, if the light generated by the lower light source (not shown) passes through the base film 110 and enters the plurality of convex portions 120 and the first micro optical pattern 130, the convex portion 120 The incident light is diffused to make the luminance uniform over the entire screen of the liquid crystal display device, and the first micro optical pattern 130 condenses the incident light and emits it almost vertically to obtain the luminance and viewing angle of the screen. To increase. Thus, in the case of the present invention, it is possible to realize a wide viewing angle on the screen while maintaining the maximum luminance in the liquid crystal display device. At this time, in the liquid crystal display device, the size and density of the first micro optical pattern 130, the radius of curvature of the mountain, and the like can be appropriately adjusted in consideration of luminance characteristics on the front and side surfaces.

  Here, the embodiment of the present invention is not limited to the above structure, and the plurality of convex portions 120 and the first fine optical pattern 130 may be simultaneously formed on the upper surface and the lower surface of the base film 110. In this case, the light condensed and diffused by the first micro optical pattern 130 on the lower surface passes through the base film 110 and is then condensed and diffused again by the convex portion 120 and the first micro optical pattern 130 on the upper surface. As described above, when the optical element 100 according to the first embodiment of the present invention is applied to the backlight unit of the liquid crystal display device, it may be applied not only to the structure shown in the drawing but also to a vertically symmetrical structure. it can.

  The optical element 100 according to the first embodiment of the present invention can be used as a diffusion plate in a backlight unit of a liquid crystal display device. For example, when such an optical element 100 is used as a diffusion plate, the base film 110 can be a PET film.

  FIG. 7 shows a modification of the optical element according to the first embodiment of the present invention.

  Referring to FIG. 7, the peaks 131 of the first fine optical pattern 130 formed on a part or all of the convex part 120 of the optical device according to the first embodiment of the present invention have different heights. A first mountain 131a and a second mountain 131b can be formed. In this way, by forming the first mountain 131a and the second mountain 131b so as to be different from each other, the light collection efficiency is higher than in the case of the first fine optical pattern 130 having the same mountain 131. Thus, light can be efficiently supplied to the liquid crystal display device.

  FIG. 8 is a schematic perspective view of an optical element according to a second embodiment of the present invention.

  Referring to FIG. 8, the optical element 200 according to the second embodiment of the present invention includes a base film 210 having light transmittance, a plurality of protrusions 220 formed on one surface of the base film 210, and the protrusions 220. A first fine optical pattern 230 in which a plurality of peaks 231 and valleys 232 are continuously formed in part, and a second minute in which a plurality of peaks 241 and valleys 242 are continuously formed on the other surface of the base film 210. An optical pattern 240 is included.

  The base film 210 according to the present invention is a material that transmits incident light, and is selected from, for example, PC (Polycarbonate), PET (Polyester), PE (Polyethylene), PP (Polypropylene), and PMMA (Polymethly Methacrylate). One included.

  A plurality of convex portions 220 are formed on one surface of the base film 210. The convex portion 220 at the time of projecting the upper cross section can have various shapes of cross sections such as an elliptical shape, a circular shape, a quadrangular shape, a triangular shape, and a rhombus shape. A first fine optical pattern 230 is formed on a part of each convex portion 220, and the first fine optical pattern 230 includes a plurality of peaks 231 and valleys 232. At this time, it is desirable that the first fine optical pattern 230 is formed in the central portion on the convex portion 220. The convex part 220 allows the light incident on the base film 210 to be diffused and emitted by an upper liquid crystal panel (not shown), so that the first micro optical pattern 230 is incident on the base film 210. The emitted light is condensed and emitted so as to be substantially perpendicular to the upper liquid crystal panel.

  The base film 210, the convex portion 220, and the first micro optical pattern 230 according to the second embodiment of the present invention are the base film 110, the convex portion 120, and the first microscopic pattern 230 according to the first embodiment of the present invention described with reference to FIGS. Since the configuration and operation are the same as those of the fine optical pattern 130, redundant description thereof will be omitted.

  The second micro optical pattern 240 according to the present invention is formed on the other surface of the base film 210 where the convex portions 220 are formed. As an example of the present invention, the second fine optical pattern 240 is preferably a prism pattern in which a plurality of peaks 241 and valleys 242 are continuously formed. That is, for example, the second fine optical pattern 240 has a substantially triangular shape continuously arranged along the length direction of the base film 210 such that the plurality of peaks 241 and valleys 242 are adjacent to each other. The prism pattern may be continuously arranged. Preferably, the second fine optical pattern 240 performs a function of collecting or / and diffusing light incident on the lower portion and emitting the light to the upper portion. This has the function of improving the luminance over the entire visible surface of the upper liquid crystal panel (not shown). Each of the prisms constituting the second fine optical pattern 240 has any one of a triangular shape, an arc shape, and a polygonal shape when the cross-section is projected.

  9 is a cross-sectional view taken along the line CC of FIG.

  Referring to FIG. 9, the first micro optical pattern 230 and the second micro optical pattern 240 according to the second embodiment of the present invention preferably have a triangular cross section when projected. However, in another example of the present invention, it may have an arc shape or a trapezoidal cross section. Since the first micro optical pattern 230 is formed on a part of the convex part 220, the remaining part 221 of the convex part 220 where the first micro optical pattern 230 is not formed is desirably curved to have a constant curvature. Formation-formed so as to draw an arc, and the light incident by this portion 221 diffuses to the periphery.

  In the drawing, the peaks 231 and 241 of the first micro optical pattern 230 and the second micro optical pattern 240 are exemplarily shown as being formed in parallel to each other. 231 and 241 are arranged so as to intersect each other while forming a predetermined inclination angle, and it can be expected to prevent moire. Here, the predetermined inclination angle includes the concept that the peaks 231 and 241 are arranged so as to be orthogonal to each other, and the predetermined inclination angle is preferably configured to be 45 ° to 90 °. In order to increase the luminance at the side surfaces (left and right) and secure a wide viewing angle in the liquid crystal display device, it is desirable that the peaks 231 of the first fine optical pattern 230 are arranged vertically in the liquid crystal display device.

  Meanwhile, the optical element 200 according to the second embodiment of the present invention can be applied to a backlight unit and a liquid crystal display device. In this case, it is desirable that the convex portion 220 and the first fine optical pattern 230 are formed on the lower surface of the base film 210 and the second fine optical pattern 240 is formed on the upper surface. When incident light generated and incident from a lower light source (not shown) is incident on the convex portion 220 and the first micro optical pattern 230 on the lower surface, the incident light is condensed and diffused to form a base. When the light is emitted to the film 210 and then passes through the base film 210 and is incident on the second fine optical pattern 240, the incident light is condensed and emitted upward. Thus, a wide viewing angle can be realized while maintaining the luminance characteristics. In the liquid crystal display device, the size, density, peak radius of curvature, and the like of the first micro optical pattern 230 can be appropriately adjusted in consideration of the luminance characteristics of the front and side surfaces.

  Here, the embodiment of the present invention is not limited to the above structure, and the plurality of convex portions 220 and the first fine optical pattern 230 are formed on the upper surface with the base film 210 as a reference, and the second minute is formed on the lower surface. An optical pattern 240 may be formed. In this case, the incident light incident from the lower part is collected by the second micro optical pattern 240 and emitted to the base film 210, and the light emitted through the base film 210 is again the convex portion 220 and The light is diffused and condensed by the first fine optical pattern 230 and emitted. A wide viewing angle on the side surface can be secured through such light diffusion.

  The optical element 200 according to the second embodiment of the present invention can be used as a normal prism sheet in a backlight unit of a liquid crystal display device. In this case, the base film 210 can use a PET film.

  10 to 12 are schematic views showing a part of a liquid crystal display device including an optical element according to an embodiment of the present invention.

  As shown in FIG. 10, the liquid crystal display device 800 according to the present invention includes a backlight unit (A) and a panel unit (B). In such a liquid crystal display device 800, light incident from the light source 810 and light reflected from the reflector 811 are diffused and emitted, and the incident light incident from the diffuser 830 is collected. One or more prism sheets 840, a reflective polarizing film 850 that selectively reflects light incident from the prism sheet 840, a phase retardation layer 860 that converts circularly polarized light transmitted through the reflective polarizing film 850 into linearly polarized light, and a phase retardation layer 860 Of the transmitted light, linearly polarized light is transmitted, circularly polarized light is transmitted through 50%, and the rest is absorbed, and an absorption polarizing film 870 and a liquid crystal panel 880 that displays a screen are included.

  At this time, when the diffusion plate 830 or the prism sheet 840 is implemented using the optical element according to the embodiment of the present invention, at least one surface (eg, the lower surface) of the diffusion plate 830 and the prism sheet 840 is finely formed. By forming a plurality of convex portions 831, 843 a, and 843 b on which an optical pattern is formed, light is condensed and diffused. In the embodiment of the present invention, the prism sheet 840 may have a structure in which the upper prism sheet 842 is stacked on the lower prism sheet 841.

  As described above, in the present invention, the optical element can be implemented in various forms by the backlight unit, and in particular, the incident light is condensed and diffused by the fine optical pattern, so that the luminance characteristics can be maintained to the maximum. However, it is possible to ensure a wide viewing angle on the side.

  11 and 12 show another example in which the optical elements 830 and 840 according to the embodiments of the present invention are applied to a liquid crystal display device.

  In FIG. 11, the optical element 830 of the present invention has a plurality of convex portions 832 on which the fine optical pattern is formed on the upper surface of the light transmissive base film 831, and can be used, for example, as a diffusion plate. . In FIG. 11, the optical element 830 of the present invention has a plurality of convex portions 832 each having a fine optical pattern formed on both surfaces, that is, an upper surface and a lower surface of the light transmissive base film 831. Can be used. At this time, the protrusions formed on the upper and lower surfaces of the base film 831 can be arranged while forming a predetermined inclination angle. In FIG. 12, in the other optical element 840, a plurality of convex portions 842 formed with the first fine optical pattern are formed on the upper surface of the base film 841, and peaks and valleys are continuously formed on the lower surface. In addition, the second micro optical pattern 843 may be formed and used in the prism sheet.

  As described above, in the present invention, the optical element can be embodied in various forms by the backlight unit.

  13 and 14 are perspective views of an optical element according to a third embodiment of the present invention.

  Referring to FIGS. 13 and 14, an optical device 300 according to a third embodiment of the present invention includes a light-transmitting base film 310 and a plurality of third micro optical patterns 320 formed on at least one surface of the base film 310. It is comprised including.

  The base film 310 according to the present invention is a material that transmits incident light, and is selected from, for example, PC (Polycarbonate), PET (Polyester), PE (Polyethylene), PP (Polypropylene), and PMMA (Polymethly Methacrylate). One included.

  The plurality of third micro optical patterns 320 according to the present invention are formed on at least one surface of the base film 310 so as to have a peak 321 having a predetermined height, and collect and diffuse the light incident on the base film 310. The third fine optical pattern 320 is desirably formed integrally with at least one surface of the base film 310.

  In addition, the plurality of third micro optical patterns 320 according to the present invention are formed in a figure having a major axis and a minor axis, that is, an elliptical shape 322 or a leaf shape, when projected on the upper surface. In other words, each third fine optical pattern 320 according to the present invention has an elliptical shape 322 at a portion in contact with at least one surface of the base film 310. At this time, desirably, the crest 321 of the third micro optical pattern 320 decreases in height from the center to both ends along the major axis of the elliptical shape 322. More preferably, the crest 321 of the third fine optical pattern is configured to be curved with a constant curvature radius along the major axis of the elliptical shape 322.

  In the embodiment of the present invention, the length of the major axis 21 is preferably 1 to 5000 μm and the length of the minor axis 22 is preferably 1 to 100 μm. At this time, the ratio of the length of the short axis and the long axis of such an elliptical shape is preferably more than 1: 1 and 1: 50000 or less. More desirably, it is desirably 1: 1000 or less. Further, the distance between the third fine optical patterns is preferably 1 to 5000 μm. In the embodiment of the present invention, the length ratio of the major axis to the minor axis, the distance between the third micro optical patterns, the height of each peak, the repetition and distribution of the pattern, etc. It can be determined by the diffusion efficiency, and as a result, can be determined by the luminance at the side surface of the liquid crystal display device.

  Meanwhile, the plurality of third micro optical patterns according to the present invention may be arranged at a constant interval. As an example of the present invention, as shown in FIG. 13, a plurality of third micro optical patterns may be arranged in a matrix form arranged vertically and horizontally. As another example, as shown in FIG. 14, a plurality of third micro optical patterns may be arranged so as to cross each other.

  15 is a cross-sectional view and a perspective view showing FF in FIG. 2, and FIG. 16 is a cross-sectional view showing GG in FIG.

  Referring to FIG. 15, the third micro optical pattern according to the third embodiment of the present invention has a triangular cross-section substantially protruding from the upper surface of the base film 310 when the short-axis cross-section is projected. Such a triangular central portion 321a becomes a part of the peak 321 in the third fine optical pattern. At this time, the side line (A, B) from the central portion 321a to the surface 322a of the base film 310 along the short axis 22 of the elliptical shape 322 is preferably a curved line. This is because when such side surface lines (A, B) are curved, incident light is not only condensed but also diffused on the side surface. However, the present invention is not limited to this, and can be implemented in the form of a straight line. In this case, condensing occurs more strongly than the diffusion of incident light. Thus, the third micro optical pattern can implement not only the condensing of incident light but also a function of diffusing to the side surface. In addition, the third fine optical pattern has a peak 321 having a predetermined height according to the major axis 21 of the elliptical shape 322. At this time, the height of the mountain 321 preferably varies along the long axis 21 of the elliptical shape 322. This is specifically illustrated in FIG. In the drawing, the cross section of the third fine optical pattern is shown as being formed in a triangular shape. However, the present invention is not limited to this, and the present invention is not limited thereto. It can be implemented in various shapes. In addition, it is desirable that the peaks 321 of the third fine optical pattern are arranged vertically in order to increase the luminance at the side surface and ensure a wide viewing angle in the liquid crystal display device.

  Referring to FIG. 16, each third micro optical pattern according to the third embodiment of the present invention has a third micro optical pattern along the long axis 21 of an elliptical shape 322 that is a portion in contact with at least one surface of the base film 310. The height decreases as the mountain 321 goes from the center 321a to both ends 321b. In other words, the height of the peak 321 from the center portion 321a is the highest in the third fine optical pattern, and the height decreases toward both end portions 321b. In particular, preferably, the crest 321 of the third fine optical pattern is curved with a constant radius of curvature along the major axis 21 of such an elliptical shape 322. At this time, the height of the peak 321 in the central portion 321a is preferably 0.2 to 200 μm. If the height of the mountain 321 is smaller than or larger than the above range, the processing becomes difficult, the light collection efficiency is lowered, and it becomes impossible to have a significant value.

  In FIG. 16, as a preferred embodiment of the present invention, when viewed from the side end face of the third fine optical pattern, the peak 321 is shown as being curved with a constant radius of curvature. It is not limited. As another example, it can be curved to a different radius of curvature from the center portion 321a to both end portions 321b, or can be embodied in a straight line. However, when applied to a liquid crystal display device, in order to provide uniform brightness over the entire visible surface, the shapes of the peaks 321 connected to both ends 321b along the long axis 21 at the center 321a are symmetrical to each other. Desirably, more desirably, it is curved to a constant radius of curvature.

  Meanwhile, the optical element 300 according to the third embodiment of the present invention can be used in a backlight unit and a liquid crystal display device. In this case, the third fine optical pattern is desirably formed on the upper surface of the base film 310. Thus, light generated by a lower light source (not shown) passes through the base film 310 and is incident on the third fine optical pattern, and the incident light is condensed and diffused on the side surface. Thus, a wide viewing angle can be realized while maintaining the luminance characteristics. At this time, the size and density of the third fine optical pattern, the radius of curvature of the mountain, the repetitive pattern and the density can be appropriately adjusted in consideration of the luminance characteristics on the front and side surfaces of the liquid crystal display device.

  Here, the embodiment of the present invention is not limited to the above structure, and the third fine optical pattern may be simultaneously formed on the upper surface and the lower surface of the base film 310. In this case, after the light condensed and diffused by the third micro optical pattern on the lower surface passes through the base film 310, it is condensed and diffused again by the third micro optical pattern on the upper surface. As described above, when the optical element 300 according to the third embodiment of the present invention is applied to the backlight unit of the liquid crystal display device, it can be applied not only to the structure shown in the drawing but also to a vertically symmetric structure. .

  The optical element 300 according to the third embodiment of the present invention can be used as a diffusion plate in a backlight unit of a liquid crystal display device. For example, when such an optical element 300 is used as a diffusion plate, the base film 310 can be a PET film.

  FIG. 17 is a schematic perspective view of an optical element according to a fourth embodiment of the present invention.

  Referring to FIG. 17, the optical element 400 according to the fourth embodiment of the present invention includes a light-transmitting base film 410, a third fine optical pattern 420 formed on one surface of the base film 410, and the base film 410. A fourth fine optical pattern 430 formed on the other surface is included.

  The base film 410 according to the present invention is selected from, for example, PC (Polycarbonate), PET (Polyester), PE (Polyethylene), PP (Polypropylene), and PMMA (PolymethlyMethacrylate) as a material that transmits incident light. Including one.

  The plurality of third micro optical patterns 420 according to the present invention are formed on one surface of the base film 410 so as to have a peak 421 having a predetermined height, and collect and diffuse the light incident on the base film 410. The third fine optical pattern 420 is preferably formed integrally with one surface of the base film 410.

  The base film 410 and the third micro optical pattern 420 according to the fourth embodiment of the present invention are the same as those of the base film 310 and the third micro optical pattern according to the third embodiment of the present invention described with reference to FIGS. Since they are the same, duplicate explanations thereof are omitted.

  The fourth micro optical pattern 430 according to the present invention is formed on the opposite surface of the base film 410 where the third micro optical pattern 420 is formed. As an example of the present invention, the fourth fine optical pattern 430 is preferably a prism pattern in which a plurality of peaks 431 and valleys 432 are continuously formed. That is, for example, the fourth fine optical pattern 430 is substantially continuously arranged in a triangular shape according to the length direction of the base film 410, and continuously arranged so that a plurality of peaks 431 and valleys 432 are adjacent to each other. It can be composed of prism patterns. Preferably, the fourth micro optical pattern 430 performs a function of collecting light incident on the lower portion and emitting it to the upper portion. This has the function of improving the luminance over the entire visible surface of the upper liquid crystal panel (not shown). Each prism constituting the fourth fine optical pattern 430 has a cross section of any one of a triangular shape, an arc shape, and a polygonal shape when the cross section is projected.

  18 is a perspective view showing HH in FIG. 17.

  Referring to FIG. 18, the third micro optical pattern 420 and the fourth micro optical pattern 430 according to the fourth embodiment of the present invention have a substantially triangular cross section when the cross section is projected. At this time, in the case of the third fine optical pattern 420 having such a triangular cross section, the lines (A, B) from the peak 411 to the elliptical shape 422 are desirably curved, and the fourth fine optical pattern 430 In this case, the line from the peak 431 to the valley 432 is preferably a straight line. In the drawing, as an example, the crests 421 and 431 of the third micro optical pattern 420 and the fourth micro optical pattern 430 are formed in parallel, but as another example, the crests 421 and 431 intersect each other. It can also be formed. Here, in order to increase the luminance at the side portions (left and right) and secure a wide viewing angle in the liquid crystal display device, it is desirable that the peaks 421 of the third micro optical pattern 420 are arranged vertically in the liquid crystal display device.

  Meanwhile, the optical element 400 according to the fourth embodiment of the present invention can be applied to a backlight unit and a liquid crystal display device. In this case, it is preferable that the third micro optical pattern 420 is formed on the lower surface of the base film 410 and the fourth micro optical pattern 430 is formed on the upper surface. When light generated by a lower light source (not shown) is incident on the third micro optical pattern 420 on the lower surface, the incident light is condensed and diffused and emitted to the base film 410. Thereafter, When the light passes through the base film 410 and enters the fourth micro optical pattern 430, the incident light is condensed and emitted upward. Thus, a wide viewing angle can be realized while maintaining the luminance characteristics. In the liquid crystal display device, the size and density of the third fine optical pattern 420, the radius of curvature of the mountain, and the like can be appropriately adjusted in consideration of the luminance characteristics of the front and side surfaces.

  Here, the embodiment of the present invention is not limited to the above structure, and the third fine optical pattern 420 may be formed on the upper surface and the fourth fine optical pattern 430 may be formed on the lower surface with reference to the base film 410. In this case, the incident light incident from the lower part is collected by the fourth micro optical pattern 430, emitted to the base film 410, and the light emitted through the base film 410 is again the third micro optical pattern. The pattern 420 causes light collection and diffusion to occur. A wide viewing angle on the side surface can be secured through such light diffusion.

  The optical element 400 according to the fourth embodiment of the present invention is a backlight unit of a liquid crystal display device and can be used as a normal prism sheet. In this case, the base film 410 can use a PET film.

  19 and 20 are diagrams showing simulation results for comparing paths of light emitted from a conventional optical element and an optical element according to the present invention.

  FIG. 19A is a simulation result showing the light path on the side surface of the conventional optical element, and FIG. 19B is a simulation result showing the light path on the side surface of the optical element according to the embodiment of the present invention. is there. As shown in the drawings, the conventional optical element has a side end surface formed in a straight line and has almost no light diffusion or condensing power. The optical element of the present invention has a side end surface in the form of a lens, that is, constant. It can be seen that the light is diffused and collected by being curved to have a large curvature.

  FIG. 20A is a simulation result showing a light path in a perspective view of a conventional optical element, and FIG. 20B is a perspective view of the optical element according to the embodiment of the present invention. It is a simulation result which shows. As shown in the drawing, in the case of the conventional optical element, it is understood that the triangular prism generates only the light collecting power, and in the case of the optical element of the present invention, not only the light collecting power but also the diffusing power to the side surface together. It can be seen that it occurs.

  Through the simulation results, it can be seen that the optical element of the present invention can realize both the upward focusing and the diffusion to the side, so that a wide viewing angle can be secured in the liquid crystal display device. Become.

  FIG. 21 is a view schematically showing a part of a liquid crystal display device including an optical element according to an embodiment of the present invention.

  As shown in FIG. 21, the liquid crystal display device 700 according to the present invention includes a backlight unit (A) and a panel unit (B). In such a liquid crystal display device 700, the light incident on the light guide plate 720 and the diffusion plate 730 for diffusing and emitting the light incident on the light source 710 and the light reflected on the reflection plate 711, and the incident light incident on the diffusion plate 730 are condensed. One or more prism sheets 740, a reflective polarizing film 750 that selectively reflects light incident from the prism sheet 740, a phase delay layer 760 that converts circularly polarized light transmitted through the reflective polarizing film 750 into linearly polarized light, and a phase delay layer 760 Among the transmitted light, linearly polarized light is transmitted, circularly polarized light is transmitted through 50%, and the rest is absorbed, and an absorption polarizing film 770 that includes a liquid crystal panel 780 that displays a screen is included.

  At this time, when the diffusion plate 730 or the prism sheet 740 is implemented using the optical element according to the embodiment of the present invention, at least one of the diffusion plate 730 and the prism sheet 740 (for example, the lower surface) is provided. A plurality of fine optical patterns 731, 743 a, and 743 b are formed to collect and diffuse light. In the embodiment of the present invention, the prism sheet 740 may have a structure in which the upper prism sheet 742 is laminated on the lower prism sheet 741.

  FIG. 21 shows an example of a liquid crystal display device, and the diffusion plate 730 and the prism sheet 740 may be variously implemented in other embodiments of the present invention. For example, in FIG. 21, the diffusion plate 730 and the prism sheet 740 may be configured to condense and diffuse light by forming a plurality of micro optical patterns 731, 743 a, and 743 b on the upper surface or both surfaces of the base film, respectively. it can.

  As described above, in the present invention, the optical element can be implemented in various forms by the backlight unit, and in particular, the incident light is condensed and diffused by the fine optical pattern, and the side surface is maintained while maximizing the luminance characteristics. A wide viewing angle can be secured.

  The foregoing drawings and detailed description of the invention are merely exemplary of the invention, which is used merely for the purpose of illustrating the invention and is intended to limit the meaning and scope of the claimed invention. It is not used to limit the scope of the invention. Thus, those having ordinary skill in the art will appreciate that various modifications and other equivalent embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be determined by the technical idea of the appended claims.

  Recently, liquid crystal display devices (LCDs) are display devices such as mobile phones, TVs, navigation systems, and various monitors, and the range of their use is expanding. It is expected that this will continue in the future. Is done. In particular, as the display device is increased in size, not only the luminance on the front side but also the luminance on the side surface is an important factor. Therefore, technical development for a wide viewing angle is actively advanced in various optical elements used in liquid crystal display devices.

  When viewed from such an aspect, the optical element used in the liquid crystal display device according to the present invention can realize a wide viewing angle by enhancing the light collecting function at a low cost while maintaining high luminance characteristics. Ultimately, it can contribute to the improvement of product quality. For these reasons, it is judged that the optical element of the present invention can be widely used in future display devices.

Claims (30)

A base film having optical transparency;
A plurality of convex portions formed on at least one surface of the base film for diffusing incident light; and a first fine optical pattern formed on the respective convex portions for collecting and emitting incident light;
An optical element comprising: 2. The optical element according to claim 1, wherein the first fine optical pattern has peaks and valleys continuously formed in at least a part of a convex portion. The optical element according to claim 1, further comprising a second fine optical pattern formed on the other surface of the base film to collect or / and diffuse incident light. 4. The optical element according to claim 3, wherein the second fine optical pattern has peaks and valleys formed continuously. 5. 5. The optical element according to claim 4, wherein each of the first micro optical pattern and the second micro optical pattern has peaks and valleys arranged in parallel to each other. The optical element according to claim 4, wherein the first fine optical pattern and the second fine optical pattern are arranged such that respective peaks and valleys form a predetermined inclination angle. The diameter of the said convex part is comprised by 50-100 micrometers. The optical element of Claim 1 or 3 characterized by the above-mentioned. The convex part is formed in a figure having a major axis and a minor axis, the major axis is composed of 50 to 100 μm, and the minor axis is composed of 1 to 100 μm. The optical element according to claim 1. The optical element according to claim 1 or 3, wherein the height of the convex portion is 10 to 40 µm. The optical element according to claim 1, wherein a distance between the convex portions is 50 to 150 μm. The optical element according to claim 1, wherein at least some of the plurality of convex portions have different heights. 4. The optical element according to claim 1, wherein a height of a peak of the first fine optical pattern is 5 to 30 μm. 4. The optical element according to claim 1, wherein a width of a peak of the first fine optical pattern is 10 to 30 μm. 4. The optical element according to claim 1, wherein the first fine optical pattern is formed such that the heights of the peaks are different from each other. 4. The optical element according to claim 1, wherein the first fine optical pattern is formed in a central portion of each convex portion. The optical element according to claim 1, wherein a remaining portion of the convex portion where the first fine optical pattern is not formed is formed in a curved shape with a constant curvature.   A backlight unit comprising any one of the optical elements according to claim 1.   A liquid crystal display device comprising the backlight unit according to claim 17. A base film having optical transparency; and a plurality of third fine optical patterns formed on at least one surface of the base film to collect and diffuse incident light;
Including
Each of the third fine optical patterns is
A portion in contact with the surface of the base film is formed into a figure having a major axis and a minor axis, and the height of a mountain provided in the third fine optical pattern is from the center along the major axis direction of the figure. An optical element characterized by being lowered toward both ends. A plurality of third fine optical patterns are formed on one surface of the base film, and a fourth fine optical pattern is formed on the other surface of the base film so as to collect or / and diffuse incident light. The optical element according to claim 19. 21. The optical element according to claim 20, wherein the fourth fine optical pattern has peaks and valleys formed continuously. The optical element according to claim 21, wherein the third micro optical pattern and the fourth micro optical pattern are arranged such that each mountain has a predetermined inclination angle. 21. The optical element according to claim 19, wherein the crest of the third fine optical pattern is configured to be curved with a constant radius of curvature along the elliptical long axis. 21. The optical element according to claim 19, wherein a height of a central portion of the third fine optical pattern is 0.2 to 200 [mu] m. 21. The optical element according to claim 19 or 20, wherein the major axis and the minor axis of the figure forming the third fine optical pattern have a length of 1 to 5000 [mu] m and 1 to 100 [mu] m, respectively. The optical element according to claim 19 or 20, wherein a distance between the third fine optical patterns is 1 to 5000 µm. The optical element according to claim 19 or 20, wherein the third fine optical patterns are arranged in a matrix form. The optical element according to claim 19 or 20, wherein the third fine optical patterns are arranged so as to intersect each other.   A backlight unit comprising any one of the optical elements according to claim 19.   A liquid crystal display device comprising the backlight unit according to claim 29.

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