JP4191498B2 - Optical element, manufacturing method thereof, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop an optical element having a light emitting means which prevents transmission light from being scattered by a recessed side surface, has excellent front directional characteristics by effectively converting an optical path of lateral incident light into a vertical direction, and is hard to generate scattered light or moire. <P>SOLUTION: The optical element comprises a light emitting means having a plurality of recesses discontinuously distributed on one side of a transparent base substrate. Each recess has an optical path converting slant surface and an opposing surface smaller in area than the optical pass converting slant surface. A manufacturing method of the optical element comprises a step for forming the light emitting means by repeating a step of forming a recess on the transparent substrate by laser etching. A manufacturing method of the optical element comprises a step for using the optical element as a mold to form an electroformed flask and transferring the shape of the flask to the substrate. A liquid crystal display device arranges the optical device on at least one side of a liquid crystal cell on a liquid crystal display panel. <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

なお正面輝度の単位は、cd／ｍ^２である。
【０１４６】
例１〜４、８、１０は、例５と比べて明るさの点に加えてその均一性の点でも優れていた。例５では光源と反対側の方向に大角度で光が出射し、液晶表示装置の照明には実質的に寄与せず画面が暗かった。また例６、７では正面近傍で実施例よりも暗い画面であった。
【０１４７】
フロントライトの状態で光出射面、すなわち光出射手段を有しない面から導光板を観察したところ、例１〜４では正面方向近傍に光が強く出射しているのに対し、例６、７ではむしろ正面方向近傍で暗かった。また例９では特に光源側に向けた出射が強く、正面方向では出射の強さが大きく低下した。
【０１４８】
例８では例１〜４より明るさが若干低く、光源から遠離るにつれて暗くなる傾向が例１〜４よりも強く、かつ例１〜４と比べて散乱による白ボケが大きくて表示が見にくかった。また例１０では明るさが例１〜４に相当したが、明確なモアレが観察された。
【０１４９】
一方、光源を消灯した外光モードによる視認においては、例１０でモアレが観察されたほかは、他の例において良好であった。
【０１５０】
他方、例１〜４において、サイドライト型導光板の表裏を逆転させて光出射手段側に反射板を配置し、導光板の光出射面上に透過型液晶表示パネルを配置してバックライトとして使用したところ、明るくて見やすい透過型の液晶表示装置を実現することができた。この液晶表示装置は、明るい環境下でバックライトを消灯しても外光モードで見ることができ、良好な外光・照明両用型の（透過型）液晶表示装置であった。
【０１５１】
また視認側のセル基板の内側に屈折率が１．３８の低屈折率層を設けた反射型液晶表示パネルの視認側に例１〜４で得た透明フィルムを貼付け、その光路変換斜面が対面するパネル側面に冷陰極管を配置したところ、導光板を用いない形態で明るい照明を実現することができた。
【０１５２】
以上より本発明にては、凹部側面による伝送光の散乱を防止し、横方向の入射光を縦方向に効率よく光路変換して出射光の正面指向性に優れ、散乱光やモアレの生じにくい光出射手段を有する、透明フィルムタイプと導光板タイプの光学素子を形成できることが判る。
【０１５３】
また前記の透明フィルムタイプの光学素子は、それを透明板に貼付けて明るい面発光のクリアな導光板を形成できること、また液晶表示パネルに貼付けパネル側面等に照明装置を設けてパネルの照明機構を形成できること、一方、導光板タイプのものも明るい面発光のクリアな導光板を形成できること、さらにそれらの導光板や照明機構にて、モアレが生じにくくて明るくて見やすい表示品位の良好な反射型や透過型、外光・照明両用型等の液晶表示装置などを形成できることが判る。
【図面の簡単な説明】
【図１】光学素子の断面図
【図２】他の光学素子の断面図
【図３】凹部の説明断面図
【図４】他の凹部の説明断面図
【図５】凹部の説明平面図
【図６】光出射手段の説明図
【図７】他の光出射手段の説明図
【図８】さらに他の光学素子の断面図
【図９】さらに他の光学素子の断面図
【図１０】液晶表示装置の断面図
【図１１】他の液晶表示装置の断面図
【符号の説明】
１、２：光学素子
１０Ａ：透明基材
Ａ：凹部
ａ：光路変換斜面
ｂ：対向面
ｘ、ｙ：凹部側面
２０：透明板
３：照明装置
１００、２００：液晶表示装置
１０１、２０１：液晶表示パネル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical element suitable for forming a non-light-emitting display device and a method for manufacturing the same, which is less likely to generate scattered light by efficiently changing the optical path of incident light in the horizontal direction in the vertical direction.
[0002]
BACKGROUND OF THE INVENTION
In a non-light-emitting display device such as a liquid crystal display device or an electrochromic display, an illumination mechanism capable of surface light emission is provided in order to achieve a display purpose. Conventionally, as the illumination mechanism, a sidelight type light guide plate having a light emitting means formed by printing white scattering dots has been known. However, the light scattering efficiency of side incident light is poor and the display is dark, and when it is arranged on the viewing side surface of a liquid crystal display panel to make a front light type reflective liquid crystal display device, the display image is displayed with white scattering dots. There was a problem that it was scattered and became invisible.
[0003]
In view of the above, a side light type light guide plate having a light emitting means having a stripe prism structure has also been proposed (Japanese Patent Laid-Open No. 11-250715). However, the stripe-shaped prism structure interferes with the pixels of the liquid crystal display panel and moire is generated, so that the display quality is liable to deteriorate, defects such as scratches on the light guide plate are easily noticeable, and if the thickness of the light guide plate is reduced, the prism There is a problem that the interval becomes wider and the light becomes rough streak and the unevenness of light and dark becomes large.
[0004]
[Technical Problem of the Invention]
In view of the above, the present inventors have conceived a method using a light emitting means in which a large number of minute-sized recesses (grooves) having a triangular or quadrangular cross section and having an optical path changing slope are dispersed and distributed. According to this, it is possible to easily overcome the moire problem, the visual obstruction problem due to defects, the brightness unevenness problem, and the like. Moreover, the problem that the light emission function is impaired due to the damage caused by friction or the like when the convex portion is formed due to the concave portion can be overcome. Furthermore, the front directivity can be improved by forming the outgoing light by reflection through the optical path changing slope, and the problem that the outgoing light is poor in the front directivity due to scattering of the reflected light when the cross section is a bowl-shaped recess can be overcome.
[0005]
However, in the light emitting means having a triangular or quadrangular concave portion as described above, the light incident on the side surface of the concave portion formed between the optical path changing slope and its opposing surface is scattered in the horizontal direction. Inconvenience that the front directivity of the outgoing light is reduced due to scattering of the transmission light inside the light guide plate, thereby reducing the display brightness in the front when the front light system is used, the increase of the scattered outgoing light, the light guide plate There has been a problem that the display is blurred due to an increase in light emitted from the back surface.
[0006]
In view of the above, the present invention prevents scattering of the transmission light by the side surface of the concave portion, efficiently converts the incident light in the horizontal direction in the vertical direction, and has excellent front directivity of the emitted light, and hardly generates scattered light or moire. An object is to develop an optical element having a light emitting means.
[0007]
[Means for solving problems]
The present invention comprises a light emitting means in which a plurality of recesses are discontinuously distributed on one surface of a transparent base material, the recess has an optical path conversion slope and its opposing surface, and the transparent base of the recess The length of the optical path conversion slope forming side at the opening on the material surface is at least three times the depth of the recess, and the projected area of the optical path conversion slope with respect to the vertical plane is larger than that of the opposing surface. An optical element and a liquid crystal display device comprising the optical element arranged on at least one side of a liquid crystal cell in a liquid crystal display panel are provided.
[0008]
Further, the present invention is characterized in that the light emitting means is formed by repeating the operation of forming a recess by laser etching that irradiates the irradiated film made of a transparent substrate with laser light to partially remove the irradiated film. A method of manufacturing the optical element, and a form of a surface on which a light emitting means is formed by forming a metal layer by electroforming on the surface on which the light emitting means of the optical element is formed, and separating the metal layer from the optical element. A step of obtaining a transferred mold, and a step of transferring the form of a surface having a convex portion capable of forming light emitting means in the mold to a transparent substrate and then separating it from the mold. The manufacturing method of the said optical element is provided.
[0009]
【The invention's effect】
According to the present invention, the area ratio of the side surface of the recess formed between the optical path conversion slope and the opposing surface can be reduced by setting the depth of the recess to 1/3 or less of the length of the optical path conversion slope forming side. At the same time, the light path conversion slope is controlled by the shadow effect based on the size of the light, and the transmission light in the lateral direction from the light source is prevented from being incident on the side surface and the opposite surface of the recess, and the transmitted light is incident on the side surface of the recess and scattered Accordingly, it is possible to obtain an optical element having a light emitting means that is excellent in front directivity of outgoing light and hardly generates scattered light and moire by efficiently changing the optical path of the incident light in the vertical direction in the vertical direction.
[0010]
In addition, by using the above-mentioned optical element, the light incident from the side or corner of the liquid crystal display panel is efficiently optically changed in the viewing direction, so that the liquid crystal display is bright and easy to see with little white blurring or disturbance of the display image. A device can be formed, and an optical element made of a transparent film can be easily reduced in thickness and weight.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The optical element according to the present invention has a light emitting means in which a plurality of concave portions are discontinuously distributed on one surface of a transparent substrate, and the concave portion includes an optical path changing slope and its opposing surface, and the concave portion The length of the optical path conversion slope forming side at the opening on the transparent substrate surface is at least three times the depth of the recess, and the projected area of the optical path conversion slope with respect to the vertical plane is larger than that of the opposing surface. is there. Examples thereof are shown in FIGS. 1 is an optical element, 10A is a transparent base material, A is a recessed part, a is an optical path conversion slope, and b is an opposing surface. In addition, 10B is a support base material, 11 is an adhesion | attachment means, 12 is a peeling sheet, The arrow is the incident direction of light (the following is the same).
[0012]
As a transparent base material, what consists of a suitable material which shows transparency according to the wavelength range of the light which enters through an illuminating device etc. can be used, and what consists of a polymer is generally used. By the way, examples of the polymer when making visible light incident include polyester resins, cellulose resins, urethane resins, polystyrene resins, polyethylene resins, polyamide resins, polyimide resins, acrylic resins, polycarbonate resins. And thermoplastic resins such as polyether resins, vinyl chloride resins, polyether sulfone resins, norbornene resins and polyphenylene sulfide resins.
[0013]
Further, polymers described in JP-A No. 2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted or / and unsubstituted imide group in the side chain, and (B) a substituted or / and substituted side chain. And a resin composition containing the above A and B with a thermoplastic resin having an unsubstituted phenyl group and a nitrile group, or heat or light of acrylic, urethane, acrylic urethane, epoxy, silicone, or the like, or A curable resin that can be polymerized by radiation such as ultraviolet rays or electron beams can also be used to form the transparent substrate.
[0014]
Specific examples of the resin composition containing A and B include those containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The transparent substrate can be formed using one kind of polymer or a mixture of two or more kinds of polymers.
[0015]
The transparent substrate can be formed by an appropriate method such as a casting method or an extrusion molding method, and preferably has a small phase difference due to birefringence. Reducing the retardation of the transparent substrate as necessary can be performed by a method of removing internal optical distortion by, for example, a method of annealing a film or a plate. Therefore, a polymer having no birefringence or a small birefringence can be preferably used for forming the transparent substrate.
[0016]
The optical element can be formed as a transparent film or a transparent plate based on the thickness of the transparent substrate 10A as in the examples of FIGS. About the thickness of a transparent base material, it can determine suitably and there is no limitation in particular. In general, a thickness of 10 mm or less, especially 5 μm to 5 mm, particularly 10 μm to 2 mm is preferable. In particular, in the case of a transparent film, a thickness of 5 to 300 μm, especially 10 to 200 μm, particularly 20 to 100 μm is preferable from the viewpoint of thinning and weight reduction. With such a thickness, sizing by punching or cutting can be easily performed.
[0017]
The optical element may be formed as a single layer or may be formed as a laminated body made of the same or different materials. As shown in FIGS. 8 and 9, the light guide plate 2 may be formed by adhering the optical element 1 made of the transparent film 10A having the supporting base 10B to the transparent plate 20 through the bonding means 11 as necessary as shown in FIGS. it can. The light guide plate can also be formed as the optical element 1 composed of the above-described transparent plate 10A as in the example of FIG. When the optical element is laminated with another member as necessary through an adhesive layer or the like, the other member is usually laminated on the side of the optical element that does not have the light emitting means A as shown in the figure.
[0018]
As shown in FIGS. 10 and 11, the optical element is a light emitting means (light path changing slope a) for light incident on the light guide plate 2, the liquid crystal cell, or the like through the illumination device 3 from the side surfaces or corners or the transmitted light. Is reflected on the back side (the side not having the light emitting means), and thus the light path is changed in the viewing direction of the liquid crystal display panels 101 and 102 and emitted, and the emitted light is emitted from the non-light emitting display such as the liquid crystal display panel. It aims at utilizing as illumination light (display light) of an element. In that case, the optical element 1 is generally arranged so that the surface on which the light emitting means is formed is in the direction along the plane of the liquid crystal cell or the like.
[0019]
In the above, the transparent substrate or the optical element has a refractive index of 1.49 or more from the viewpoint that it is possible to achieve a display that is bright and excellent in uniformity by increasing the incident efficiency on the light path conversion slope. preferable. The refractive index is generally based on D-rays in the visible light range, but is not limited to the above when the wavelength range of incident light has specificity, etc., and may depend on the wavelength range. Yes (the same applies below).
[0020]
Incidentally, the range of the transmission angle of the light incident from the side surface of the transparent base material is ± 42.9 degrees when the refractive index of the transparent base material is 1.47, whereas it is ± 42 when the refractive index is 1.49. When the refractive index is 1.51, it is ± 41.5 degrees. Therefore, the higher the refractive index of the transparent substrate, the more concentrated the transmitted light can be in a narrow angle range.
[0021]
Also, assuming an optical path conversion slope with an inclination angle of 45 degrees, the angle range in which the transmitted light is directly incident on the slope and totally reflected is 2.1 degrees when the refractive index of the transparent substrate is 1.47. On the other hand, when the refractive index is 1.49, the refractive index is 2.8 degrees, and when the refractive index is 1.51, it is 3.5 degrees. Therefore, the higher the refractive index of the transparent base material, the more the transmitted light is directly incident on the optical path changing slope. Thus, the probability of emission by one reflection increases, and the emission efficiency of incident light from the side surface or the like is improved. Incidentally, when the refractive index is 1.51, the outgoing light rate is about twice that when the refractive index is 1.27.
[0022]
The preferable refractive index of the transparent base material is 1.50 or more, especially 1.51 or more, particularly 1.52 or more in terms of the above-described transmission light condensing and emission light ratio. Higher is preferable. On the other hand, since there is a problem of surface reflection of external light in the front light system, the refractive index is preferably 1.6 or less, particularly 1.56 or less, particularly 1.54 or less from the viewpoint of suppressing the surface reflection. .
[0023]
The cell substrate of the liquid crystal cell is mainly made of optical glass. In the case of non-alkali glass, the refractive index is about 1.51 to 1.52, and the incident transmission light from the side surface of the cell substrate is the cell substrate. When the refractive index of the other member adjacent to the cell substrate is lower than the refractive index of the cell substrate, it is easy to be totally reflected. It is more preferable than the rate.
[0024]
Therefore, by setting the refractive index of the transparent base material forming the optical element such as the light guide plate and the adhesive means attached to the base material as necessary to the above range, the angle at which the transmitted light is totally reflected is within the allowable range. It is possible to suppress the decrease in light utilization efficiency due to the fact that the transmission light cannot be emitted due to total reflection, and it is also possible to improve the uniformity of the luminance distribution of light emitted by the emitted light.
[0025]
In some cases, such as when the cell substrate is made of plastic, the refractive index is about 1.50. In that case, it is preferable that the refractive index of the transparent base material or the adhering means attached thereto is a similar refractive index such as about 1.50.
[0026]
As described above, the phase difference due to the birefringence of the optical element forming member such as a transparent substrate is as small as possible, particularly in the case of the front light system, and the display device with less display unevenness by suppressing uneven brightness and color unevenness. It is preferable from the point which obtains. The fact that the phase difference due to birefringence is small is advantageous in preventing deterioration of display quality because the polarization state can be maintained well when linearly polarized light is incident through a polarizing plate or the like.
[0027]
In terms of prevention of display unevenness and the like, the preferable in-plane average phase difference in the transparent base material or optical element is 50 nm or less, especially 30 nm or less, particularly 20 nm or less. Smaller ones are more preferable. Furthermore, a transparent substrate or an optical element made of a material having a small photoelastic coefficient is preferable from the viewpoint of suppressing the internal stress generated in the optical element and preventing the occurrence of the phase difference due to the internal stress. In addition, the average retardation in the thickness direction of the transparent substrate or optical element is preferably 50 nm or less, more preferably 30 nm or less, particularly 20 nm or less from the viewpoint of preventing display unevenness.
[0028]
The phase difference is preferably based on visible light, particularly light having a wavelength of 550 nm. The average in-plane phase difference is defined by (nx−ny) × d, and the average phase difference in the thickness direction is defined by {(nx + ny) / 2−nz} × d. Where nx is the average refractive index in the direction showing the maximum refractive index in the plane of the forming member such as a transparent substrate, ny is the average refractive index in the direction perpendicular to the nx direction in the plane, and nz is the thickness of the forming member. The average refractive index in the vertical direction, d, means the average thickness of the forming member.
[0029]
The light emitting means provided in the optical element is formed as a plurality of predetermined concave portions A distributed discontinuously on one side of the transparent substrate 10A as in the examples of FIGS. 6 and 7 for the purpose of preventing moire or the like. Such light emitting means is advantageous in terms of reduction in visibility and manufacturing efficiency due to the reduction in the size of the recess. In addition, a recessed part means that it is recessed in the transparent base material (groove).
[0030]
The concave portion forming the light emitting means is formed to have an optical path changing inclined surface a and its facing surface b as illustrated in FIGS. 3-5, the length L1 of the optical path conversion slope forming side at the opening on the surface of the transparent substrate 10A is three times or more the depth h of the recess, and the optical path conversion slope a The projected area with respect to the vertical surface is formed to be larger than the projected area with respect to the vertical surface of the facing surface b. Accordingly, as illustrated in FIG. 5, the length L1 of the optical path changing slope forming side at the opening of the concave portion on the surface of the transparent substrate is formed to be larger than the length L2 of the opposing surface forming side.
[0031]
As described above, the side surface of the concave portion formed between the optical path conversion inclined surface a and the opposing surface b as illustrated in FIG. 5 is formed by forming the concave portion having the length L1 of the optical path converting slope forming side being three times or more the depth h. The area ratio of x and y can be reduced, and the probability that transmitted light is incident on the side surface of the recess can be reduced. A recess that is more preferable than such a point is such that the length L1 of the optical path conversion slope forming side is 5 times or more, especially 8 times or more, especially 10 times or more of the depth h.
[0032]
Further, as described above, the light path conversion inclined surface a is made larger than the opposing surface b based on the projected area with respect to the vertical surface, so that the transmitted light is shaded by the side effect of the light path conversion inclined surface a as shown by the arrow in FIG. It becomes difficult to enter x, y and the opposing surface b, and it is possible to suppress the generation of scattered light due to the transmission light entering the side surface of the recess together with the effect of reducing the area ratio of the side surface of the recess.
[0033]
As shown in FIG. 5, the preferred recess has a trapezoidal opening shape on the surface of the transparent substrate, and one of the parallel sides thereof is an optical path conversion slope forming side L1 and the other is a facing surface forming side L2, and a cross section The shape is a triangle or a trapezoid as illustrated in FIGS. In addition, a cross section means the cross section with respect to the optical path conversion inclined surface of a recessed part.
[0034]
According to the concave portion of the above form, the concave side surfaces x and y are usually surfaces having a shape similar to a cone, and are surfaces arranged at an angle between the optical path conversion inclined surface a and the opposing surface b. In this case, even if transmission light having an angle that can be incident on the side surface of the concave portion is incident on the side surface of the concave portion and reflected (scattered), the transmission angle becomes small due to the angle effect on the side surface of the concave portion, and the scattered and emitted light is condensed. As a result, the light use efficiency is improved. Accordingly, the side surface of the concave portion exhibits a light collecting effect and functions conveniently.
[0035]
In the above, the angle of the side surface of the concave portion, that is, the angle with respect to the normal line of the optical path conversion slope forming side L1 is not particularly limited, but as described above, for example, the maximum value of the refraction angle of transmitted light when the refractive index is 1.49 is ± Since the angle is 42.2 degrees, setting the angle on the side surface of the concave portion to 42 degrees or more can almost prevent transmission light from entering the side surface of the concave portion, and greatly reduce light scattering due to incidence of the transmitted light on the side surface of the concave portion. Can be reduced.
[0036]
In the above case, since there is no incidence on the side surface of the concave portion, it means that there is no opportunity to exhibit the light collecting effect due to the side surface of the concave portion. From the point, it is preferable that the angle of the side surface of the concave portion is more than 0 degree and less than 42 degrees, especially 30 degrees or less, particularly 20 degrees or less. In particular, by setting it to 30 degrees or less, the amount of light incident on the side surface of the recess can be improved, and the effect of collimation can be increased. The angles and the like of the side surfaces formed on the left and right sides of the recess may be the same or different, and therefore the recess may have a left-right symmetric shape or a left-right asymmetric shape. Good.
[0037]
The cross-sectional shape of the concave portion is preferably a triangular shape in which the intersecting line between the optical path converting slope a and the facing surface b is a ridge line as in the example of FIG. 3, but as in the example of FIG. A trapezoidal shape in which the ridge portion is flattened is advantageous. In the case of a trapezoid, the length (width) of the upper side by the flattening is 1/5 or less, particularly 1/7 or less, especially the distance (width) between parallel sides in the opening trapezoid of the concave portion of the transparent base material surface. It is preferably 1/10 or less from the viewpoint of preventing the occurrence of white blur caused by the light emitting means and reducing the visibility.
[0038]
Further, it is preferable that each of the surfaces such as the optical path changing slope a, the facing surface b, and the side surfaces x and y forming the concave portion is a straight and smooth flat surface, but there is a slight change in the inclination angle or the like based on a manufacturing error or the like. It is acceptable and the range is preferably within 10 degrees, and more preferably within 5 degrees. Furthermore, the intersection line between the surfaces forming the recesses preferably has a clear ridgeline, but may have a slight roundness. The roundness is preferably as small as possible from the viewpoint of non-visibility and light scattering prevention. In particular, it is preferably 1 μm or less, particularly 0.5 μm or less based on the radius of curvature. Therefore, the above-described triangles and trapezoids are not strictly meant and can be deformed based on processing accuracy or manufacturing error.
[0039]
If the size of the concave portion is large, the presence of the light path changing slope and the like is easily seen by the observer, and the display quality is liable to be lowered, and the uniformity of illumination for the liquid crystal cell and the like is also liable to be lowered. On the other hand, if the size is too small, light scattering due to diffraction or the like increases, or rounding is likely to occur at the intersections between the surfaces.
[0040]
From the above points, the size of the recess is based on the opening size of the recess on the surface of the transparent substrate, the distance between the sides of the trapezoid parallel side (width) or the distance between the sides of the optical path conversion slope forming side and the opposing surface forming side (width). And the depth h of the recess is preferably 1 to 100 μm, especially 3 to 50 μm, particularly 5 to 20 μm.
[0041]
Moreover, it is preferable that the length L1 of the optical path conversion slope forming side is 3 to 500 μm, especially 10 to 200 μm, and particularly 15 to 150 μm. Further, the length L2 of the opposing surface forming side is a length that achieves the above-mentioned angle of the side surface of the concave portion based on the length L1 of the optical path conversion slope forming side, and is generally 50 to 99% of the L1, and particularly 70 to 98%, particularly 80 to 97%.
[0042]
As shown in FIGS. 10 and 11, the optical path changing slope provided in the concave portion reflects the incident light from the side surface direction by the illuminating device 3 arranged on the side surface of the light guide plate 20 or the liquid crystal cell or the like, and the transmitted light thereof. The object of the present invention is to change the optical path to the back surface side that does not have one light emitting means A and to emit it as illumination light of the display device.
[0043]
The transparent substrate 10A has a preferable inclination angle θ1 of the light path conversion inclined surface a from the point that the illumination light excellent in normal direction directivity with respect to a display device such as a light guide plate or a liquid crystal cell is emitted efficiently by the use of light by the lighting device. It is 35 to 48 degrees with respect to the plane to be formed. If the tilt angle θ1 is less than 35 degrees, the angle of the display light emitted from the display device may exceed 30 degrees, which may be disadvantageous for visual recognition. On the other hand, if the inclination angle θ1 exceeds 48 degrees, light leakage is likely to occur from the optical path conversion slope, and the light utilization efficiency may decrease.
[0044]
In the above case, instead of the reflection method using the light path changing slope, if the scattering reflection method using the light emitting means having a roughened surface is used, the light is not reflected in the vertical direction and is emitted from the display device in a direction inclined more than the front direction. As a result, the liquid crystal display becomes dark and the contrast becomes poor.
[0045]
The lateral light incident from the side surface is efficiently totally reflected through the optical path conversion slope, and is emitted with good directivity in the normal direction of the optical element plane from the side having no light emitting means, thereby efficiently displaying the display device. In view of achieving a bright and easy-to-view display by illuminating, the preferable inclination angle θ1 of the light path conversion slope is 38 to 45 degrees, and in particular 40 to 43 degrees.
[0046]
On the other hand, there is no particular limitation on the inclination angle θ2 of the facing surface b provided in the recess. Generally, it is set to 35 degrees or more. Therefore, it may be an opposing surface that satisfies the inclination angle as the optical path conversion inclined surface. In the case of an opposing surface that does not satisfy the inclination angle as an optical path conversion slope, it does not contribute to emitting incident light from the lateral direction such as the side surface from the back surface, but it is possible for display quality, light transmission or light emission as much as possible. It is preferable not to affect. Incidentally, if the inclination angle θ2 of the facing surface is small, the projected area on the optical element surface becomes large, and in the external light mode by the front light system in which the optical element is arranged on the viewing side, the surface reflected light from the facing surface returns to the observation direction. Display quality tends to be hindered.
[0047]
Therefore, in the above case, the larger the inclination angle θ2 of the opposing surface, the more advantageous, so that the projected area with respect to the optical element surface can be reduced, the decrease in the total light transmittance can be suppressed, and the surface reflected light can be reduced. The reflected light can be tilted in the direction of the optical element surface, and the influence on the liquid crystal display or the like can be suppressed. Further, it is more advantageous that the angle of inclination θ2 of the facing surface is larger than the point at which the light transmitted through the light path changing slope is taken into the light guide plate or the like again from the facing surface. From this point, the preferable inclination angle θ2 of the facing surface is 60 degrees or more, especially 70 degrees or more, and particularly 75 to 90 degrees.
[0048]
The arrangement of the plurality of concave portions forming the light emitting means may be distributed in parallel as shown in the example of FIG. 6 based on the optical path changing slope, or may be irregularly distributed. Further, as shown in the example of FIG. 7, it may be in a distributed state in which pits (concentric circles) are arranged with respect to the virtual center. The irregular arrangement of the recesses is advantageous for prevention of moire, that is, prevention of occurrence of moire due to interference with regular arrangements such as pixels.
[0049]
When the linear light source is disposed on the side surface of the optical element, it is preferable that the concave portion is disposed so that the optical path changing slope is perpendicular to the transmission direction of the side incident light from the viewpoint of achieving efficient light emission. In general, in the case of a linear light source such as a cathode ray tube, transmitted light in a direction perpendicular to the incident side surface shows the maximum intensity. Therefore, in such a case, as shown in the example of FIG. 6, it is efficient to distribute the recesses A in parallel to the end surface (side surface) of the transparent base material on which the linear light source is to be arranged based on the optical path changing slope. This is advantageous from the point of achieving emission.
[0050]
On the other hand, for example, when the linear light source is composed of a combination of a point light source and a linear light guide plate, the transmitted light with the maximum intensity may be inclined with respect to the normal direction of the incident side surface. In the side-parallel arrangement, light is emitted with an inclination. Therefore, in such a case, it is preferable to arrange the recess so that the light path conversion inclined surface is perpendicular to the transmission direction of the maximum intensity, and the angle is usually 3 with respect to the end face (light incident side face) of the transparent substrate. It is an angle inclined at an angle of 5 to 10 degrees.
[0051]
On the other hand, the pit-like arrangement of the recesses described above is a distribution form that can be preferably applied when a point light source such as a light emitting diode is arranged at the virtual center. In this case, since the transmitted light is transmitted so as to spread from the virtual center, the transmitted light is efficiently incident on the optical path conversion slope located so as to face the virtual center, and effective light emission is achieved. The virtual center may be at the corners or between corners of the side (end face) in the transparent substrate, or outside the sides or corners. Further, the virtual center may be one place, or may be two or more places at different positions.
[0052]
The discontinuous arrangement state of the plurality of recesses can be appropriately determined according to the form of the recesses. As described above, the light path changing slope a is for emitting incident light from the side surface direction by the illuminating device or its transmitted light in the illumination mode by changing the light path in the back direction by reflection. Accordingly, the surface emission state such as luminance can be controlled by the number and arrangement of the recesses.
[0053]
In the above-described front light optical element, the arrangement state of the concave portion relates to the disturbance of the display image due to light scattering or the like and the incident efficiency of the external light in the external light mode. 1/5 or less, especially 3-18%, especially 5-15%, based on the area based on the concave opening of the light emitting means on one side of the material, that is, the area occupied by the projected area of the light emitting means on the substrate surface It is preferable to do.
[0054]
On the other hand, in the optical element for backlight, since the above-described disturbance of the display image and the incident efficiency of external light are not related, the concave portions can be placed in an arbitrary arrangement state. Generally, the arrangement state is 1 to 90%, especially 10 to 70%, particularly 20 to 50% based on the occupied area.
[0055]
It is preferable that the surface on which the concave portion is formed, particularly the optical path conversion slope, is a straight surface with as few irregularities and bends as possible. The cross-sectional shape of the recess may be a shape in which the inclination angle of the surface is constant over the entire surface of the optical element, or light emission on the optical element in response to absorption loss or attenuation of transmitted light due to the previous optical path conversion. For the purpose of achieving uniformity, the concave portion may be enlarged as the distance from the side surface or the virtual center on the light incident side increases.
[0056]
It is also possible to use light emitting means in which the concave portions are distributed and distributed at a constant pitch, or light in which the concave portion is gradually narrowed as the distance from the side surface or virtual center on which light is incident is increased to increase the distribution density of the concave portions. It can also be an emitting means. Furthermore, it is possible to make the light emission uniform on the optical element by light emitting means with a random pitch with irregular distribution density and arrangement position of the recesses. The random pitch is particularly advantageous for preventing moire due to interference with pixels. Therefore, the light emitting means may be composed of a combination of recesses having different shapes and the like in addition to the pitch.
[0057]
Optical elements, particularly those made of transparent films, must have flat surfaces that are as smooth as possible except for the concave portions that form the light emitting means, and in particular an angle change of ± 2 degrees or less, especially 0 It is preferable that the surface has a flat surface. The angle change is preferably within 1 degree per 5 mm length. By adopting such a flat surface, most of the film surface can be made a smooth surface with an angle change of 2 degrees or less, and light transmitted through the inside of an optical transmission body such as a liquid crystal cell can be used efficiently, and an image can be displayed. Uniform light emission without disturbance can be achieved.
[0058]
The optical element can be manufactured by an appropriate method. By the way, as an example, a method of forming a light emitting means by repeating the operation of forming a recess by laser etching that irradiates the irradiated film made of a transparent substrate with laser light to partially remove the irradiated film, etc. Is given.
[0059]
That is, for example, while irradiating a laser beam through a projection mask and irradiating the irradiated film made of a transparent substrate with the laser beam transmitted through the projection mask reduced in size through an optical device that creates a projection image By subjecting the irradiated film to laser etching by changing the irradiation amount of the laser beam through the movement of the projection mask, etc., it is possible to form a fine recess with a triangular cross section with excellent shape accuracy, and the recess forming operation is irradiated. By repeating it at a predetermined position on the film, it is possible to form a light emitting means in which the concave portions are distributed and distributed with high positional accuracy. In addition, a concave portion having a trapezoidal cross section can be formed by performing laser etching penetrating the film by using a thin film to be irradiated in the above.
[0060]
Further, the laser beam is irradiated through a projection mask having a trapezoidal opening having a predetermined size, and the opening on the surface of the irradiated film is trapezoidal by opening and closing the opening through a separate projection mask or the like. Can be formed. In that case, the opening / closing operation of the opening can continuously remove the material for forming the film to be irradiated according to the movement distance of the mask, and the position where the irradiation time of the laser beam is longer is closer to the closing position of the mask opening. The recess (groove) A is formed by being etched so deeply.
[0061]
In addition, the formation of the concave portion A including the optical path converting slope a having an inclination angle θ1 of 35 to 48 degrees and the facing surface b having the angle θ2 of 35 to 90 degrees with respect to the plane formed by the irradiated film is performed by, for example, etching. Laser etching is performed at a rate (etching amount per shot) of 0.01 to 5 μm / pulse, and at that time, one side of the parallel side and the other side of the trapezoidal opening of the projection mask are 1.1 to 150 times larger It can be performed by a method of opening and closing at a speed ratio.
[0062]
The distribution of the pit-like arrangement described above assumes, for example, a virtual center on the end face of the film to be irradiated or the outside thereof when irradiating laser light, and in a direction orthogonal to the virtual radiation derived from the virtual center. It can be formed by providing a recess so that an opening / closing line of a trapezoidal opening in the projection mask is formed.
[0063]
In the above, examples of laser light include excimer laser, YAG laser, titanium / sapphire laser, and CO. ₂ One type or two or more types that can be dry-etched, such as laser and femtosecond laser, can be used. In particular, ablation processing using an oscillator capable of obtaining laser light in the ultraviolet region with a wavelength of 400 nm or less is preferable from the viewpoint of fine processing accuracy and the like. Laser light can be irradiated to the film to be irradiated as a harmonic of the second order, the third order, the fourth order or the like.
[0064]
On the other hand, an appropriate mask made of a laser light shielding material such as metal can be used as the projection mask. A glass mask in which an appropriate laser light shielding material such as metal or dielectric is vapor-deposited on a glass plate made of quartz or the like, and the vapor deposition layer is patterned as necessary to form a laser light transmitting portion instead of the opening. Etc. can also be used. The vapor deposition material for the glass mask is not limited, but chromium, aluminum, molybdenum, a dielectric multilayer film, and the like are preferable from the viewpoint of durability against laser light and resolution.
[0065]
The optical element can be manufactured integrally by using the transparent base material on the irradiated film by the above-described method. From the viewpoint of mass productivity, a preferable method for manufacturing an optical element is to manufacture a mold for forming an optical element using the optical element obtained by the above method as a mother mold, and mass-produce the optical element using the mold. It is a method to do.
[0066]
Incidentally, the mold can be formed by transferring the shape of the surface on which the light emitting means of the optical element is formed to a mold forming material. In addition, the optical element can be formed by transferring the form of the surface having the convex portion that can form the light emitting means in the obtained mold to the transparent substrate and then separating it from the mold. In this case, the irradiated film used for the mother mold is formed with a concave portion having a rectangular opening on the surface, and the side surface of the convex portion in the mold is cut to form a transparent substrate. The above-mentioned trapezoidal concave portion intended for the opening on the surface can be formed when transferred to the surface. Therefore, the shape of the concave portion or the light emitting means formed by the shape transfer can be adjusted through the processing on the convex portion formed in the mold.
[0067]
The method of forming the optical element by transferring the form of the light emitting means to the mold as described above can be applied even when the material having the form of the light emitting means is not an optical element, and light provided on the material that is not the optical element. An optical element can also be formed by a method in which a form corresponding to the emitting means is transferred to a mold, and the surface form transferred to the mold is transferred to a transparent substrate. Therefore, in that case, a film other than the transparent substrate can be used as the irradiated film.
[0068]
In the manufacture of a mold for forming an optical element using an irradiated film having a plurality of predetermined concave portions as a matrix, for example, an electroforming method is applied to the irradiated film provided with a light emitting means or a form corresponding thereto. Can be performed. As a result, it is possible to form a mold having convex portions corresponding to high precision in the concave portions forming the light emitting means provided on the irradiated film.
[0069]
As the electroforming method, a metal mold having a replica filled with a metal from the laser-treated side of the irradiated film and having a replica of the surface shape of the irradiated film having the light emitting means, etc. It is possible to apply a conventional method for forming In that case, the irradiated film can be supported on a substrate made of glass or metal. Note that a conductive film is provided on the irradiated film when the metal layer is formed, and a method according to the related art can be applied to the formation of the conductive film.
[0070]
There are no particular limitations on the type of metal that forms the mold. Generally, for example, gold, silver, copper, iron, nickel, cobalt, or alloys thereof are used, and nitrides, phosphorus, etc. are added. It may be. The metal species to be used may be one or two or more, and a mold formed by laminating different metals can also be formed.
[0071]
The thickness of the metal layer formed as a mold may be determined as appropriate. Metal foil or metal plate made of a metal layer having a thickness of about 0.02 to 3 mm in thickness of the portion not having a convex portion from the viewpoint of preventing breakage when separated from the film to be irradiated and handling properties when forming an optical element It is preferable to use a mold according to.
[0072]
The optical element is formed through the mold by, for example, applying a radiation curable resin to a transparent film, a transparent plate, or the like, if necessary, in close contact with the surface on which the convex portion of the mold is formed. The surface shape of the convex portion forming side of the mold is copied to the radiation curable resin layer, thereby forming a molded layer that reflects the surface shape, and the molded layer is irradiated with radiation to cure the molded cured layer. Can be separated from the mold.
[0073]
When forming the optical element, the transparent substrate or the transparent substrate made of a transparent plate with respect to the radiation-curable resin molding layer is placed in close contact with the above-described prior coating method, for example, the molding layer on the mold. It is possible to adopt an appropriate method that can cure the molding layer by irradiating radiation from the transparent substrate side in a state where the transparent substrate is in close contact with the molding layer, such as a posterior method of arranging the transparent substrate on the top. it can.
[0074]
As the radiation curable resin, for example, one or two or more kinds of appropriate resins that can be cured by irradiation with ultraviolet rays such as the above-described ultraviolet curable resin, in particular, irradiation with ultraviolet rays or / and electron beams are used. There is no particular limitation on the type. In particular, a radiation curable resin capable of forming a molded cured layer having excellent light transmittance is preferable.
[0075]
In addition, a transparent film or a transparent plate that may be used for supporting a radiation curable resin to form an optical element, if necessary, has an appropriate transparency depending on the wavelength range of light incident through an illumination device or the like. It can be formed using one or more of the materials. Incidentally, in the visible light region, for example, transparent resins represented by those exemplified for the above-mentioned transparent substrate, and curable resins that can be polymerized by heat, ultraviolet rays, electron beams, and the like can be mentioned.
[0076]
When a transparent transparent substrate is used for forming the molded cured layer of the radiation curable resin, the optical element can be obtained as the transparent substrate and the molded cured layer fixed and integrated. Further, it can also be obtained as comprising the molded and hardened layer in a state separated from the transparent substrate. Separation of the transparent substrate and the molded cured layer can be achieved by an appropriate method such as a method of surface-treating the transparent substrate with a release agent.
[0077]
In the case of the fixed integration described above, if the refractive index difference between the molded and hardened layer and the transparent substrate is large, the light emission efficiency may be greatly reduced due to interface reflection or the like. Radiation that can form a molded hardened layer having a refractive index difference of -0.02 to 0.04, especially -0.01 to 0.03, especially 0 to 0.02, from the point of preventing it. A curable resin is preferred. Moreover, in that case, it is preferable from the point of the emission efficiency to raise the refractive index of the shaping | molding hardening layer added rather than a transparent base material.
[0078]
The thickness of the radiation-curable resin coating layer formed on the mold or on the transparent substrate is 1 to 5 times, especially 1.1 to 3 times, especially 1. Although 2 to 2 times is preferable, it is not limited to this.
[0079]
As a method of forming an optical element through the above-mentioned mold, a shape is transferred to a thermoplastic resin by a thermosetting treatment using a thermosetting resin instead of a radiation curable resin or a hot press method. There are also ways to do this. Another example is a method in which a mold formed by the electrocasting method is installed in an injection mold or a casting mold, and an optical element is molded by an injection molding method or a casting method. Such a molding method is particularly suitable when, for example, an optical element made of a plate-like transparent substrate that can be used as a light guide plate or the like is formed.
[0080]
Therefore, the optical element is formed by transferring the form of the surface having the convex portion that can form the light emitting means in the mold through an appropriate material such as a thermoplastic resin or a curable resin that is in a fluidized state as necessary. It can be formed by an appropriate method capable of forming a transparent substrate.
[0081]
The light emitting means forming surface of the optical element is subjected to non-glare treatment or antireflection treatment for the purpose of preventing visual obstruction due to surface reflection of external light, and hard coat treatment for the purpose of preventing scratches as necessary. Can do. The optical element subjected to such treatment can be preferably used particularly for the front light system.
[0082]
The above-mentioned non-glare treatment is performed by making the surface into a fine concavo-convex structure by various methods such as a roughening method such as a sand blasting method or an embossing method, or a resin coating method in which the transparent particles such as silica are mixed. Can be applied. The antireflection treatment can be performed by a method of forming an interfering vapor deposition film. Further, the hard coat treatment can be performed by a method of applying a hard resin such as a curable resin. The non-glare treatment, the antireflection treatment and the hard coat treatment can be applied to a film adhesion method or the like subjected to one or more treatments.
[0083]
The optical element may have an adhesive means 11 on the side not having the light emitting means as in the example of FIG. As described above, an optical element made of a transparent film is disposed on a substrate such as a light guide plate or a cell substrate that transmits incident light from side surfaces and corners. In that case, the optical element is brought into close contact with the substrate through the bonding means, thereby improving the reflection efficiency through the light path changing slope of the light emitting means, and consequently the luminance by effective use of incident light from the direction of the side surface or the like. Can do.
[0084]
For the formation of the adhesive layer as the adhesive means, for example, an appropriate material such as an adhesive that is cured by irradiation with ultraviolet rays or radiation or heating can be used, and there is no particular limitation. In particular, those having excellent transparency and small refractive index difference from the adherend are preferable. In addition, an adhesive layer can be preferably used in terms of handling properties such as simple adhesiveness and stress relaxation properties that suppress the generation of internal stress.
[0085]
The refractive index of the adhering means is 1.49 or more, especially 1.50 or more, especially 1.51 or more, more preferably 1.52 or more from the viewpoint of the light emission efficiency and the like, similar to the transparent substrate described above. preferable. In particular, from the viewpoint of light transmission efficiency, it is preferable that the refractive index of the optical element made of an adhesive means or a transparent film is higher than or at least the same as the refractive index of the substrate that mainly transmits side incident light. When the refractive index is low, when the angle of the transmitted light is small with respect to the substrate surface of the transmission main body, the transmitted light is easily confined in the substrate by total reflection, and the light emission efficiency is likely to be lowered.
[0086]
Even when the refractive index difference at the interface is large, transmission light is easily confined by the interface reflection. Therefore, from the viewpoint of reducing the total reflection and interface reflection, the difference in refractive index between the transmission main substrate and the bonding means is preferably as small as possible, preferably 0.05 or less, especially 0.03 or less, In particular, it is preferably 0.02 or less, more preferably 0.01 or less.
[0087]
For the formation of the above-mentioned adhesive layer, for example, an adhesive based on an appropriate polymer such as rubber-based, acrylic-based, vinyl alkyl ether-based, silicone-based, polyester-based, polyurethane-based, polyether-based, polyamide-based, or styrene-based polymer. An agent or the like can be used. Among them, those having excellent transparency, weather resistance, heat resistance and the like, such as an acrylic pressure-sensitive adhesive mainly composed of a polymer mainly composed of alkyl ester of acrylic acid or methacrylic acid, are preferably used.
[0088]
In addition, the adhesive layer includes inorganic particles having conductivity such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and nonmony oxide, and organic particles such as a crosslinked or uncrosslinked polymer. One kind or two or more kinds of appropriate transparent particles may be contained to obtain a light diffusion type.
[0089]
An optical element, particularly an optical element made of a transparent film, can also be used as a transparent protective layer of a polarizing plate. That is, the optical element can be laminated on the polarizing plate through the side not having the light emitting means. In that case, the optical element and the polarizing plate are bonded and laminated via the bonding means, so that the reflection efficiency through the light path changing slope of the light emitting means, and the effective use of incident light from the side and corner directions This is preferable from the viewpoint of improving the luminance.
[0090]
The above-described polarizing plate-integrated optical element can be applied to a liquid crystal display panel or the like as it is. In that case, a method of arranging the optical elements so that the light emitting means is located outside is usually used. By using an optical element that does not easily generate a phase difference due to birefringence, when the linearly polarized light enters through the polarizing plate, the polarization state can be maintained well, and the absorption and display when the light enters the polarizing plate again. Degradation can be effectively prevented.
[0091]
As a polarizing plate, a suitable thing can be used and there is no limitation in particular. Higher hydrophilicity such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, ethylene / vinyl acetate copolymer partially saponified film, etc. A polarizing plate having a high degree of polarization can be preferably used, such as an absorption-type polarizing film formed by stretching a molecular film by adsorbing a dichroic substance such as iodine or a dichroic dye.
[0092]
The polarizing plate may have a transparent protective layer on one side or both sides of the polarizing film. The transparent protective layer can be applied by a film adhesion method or a coating method such as a polymer solution, and the formation thereof is exemplified by the resin exemplified in the above transparent base material, especially transparency and mechanical strength such as triacetyl cellulose, Resins excellent in thermal stability and moisture shielding properties are preferably used. The above-described polarizing plate-integrated optical element may be laminated with the optical element serving also as the transparent protective layer for the purpose of thinning, or may be laminated in a state of being added to the outside of the transparent protective layer. Good.
[0093]
The polarizing plate-integrated optical element can be provided with an adhesive means such as a transparent adhesive layer for adhering to other members such as a liquid crystal cell, if necessary. The adhesive layer can conform to the above. The adhesive layer provided on the optical element is temporarily covered with a release sheet 12 for the purpose of preventing foreign matters from being mixed until it is put to practical use as shown in FIG. Is preferred. The optical element can be covered with a surface protective film to suppress the adhesion of scratches and dirt.
[0094]
The optical element has a vertical direction (normal direction) that is advantageous for visual recognition of incident light or transmitted light from the direction of the side surface or corner by the illuminating device via its light emitting means (optical path changing slope). It is possible to change the optical path to emit light with high light utilization efficiency and to exhibit good transparency to external light.
[0095]
Therefore, for example, it is applied to various liquid crystal display panels such as a conventional transmissive type, a reflective type or a semi-transmissive type having a reflective layer or a semi-transmissive reflective layer, and is bright and easy to see, or for both external light and illumination. Various devices such as a non-light-emitting display device such as a liquid crystal display device can be formed. In the case of an optical element made of a transparent film, a thin and light weight liquid crystal display device can also be achieved.
[0096]
Examples of the liquid crystal display device described above are shown in FIGS. 10 shows an optical element 1 bonded to a transparent plate 20 and an illuminating device 3 arranged on the side surface to form a sidelight type light guide plate 2, which is arranged on the back side of a conventional transmissive liquid crystal display panel 101, An example of a light-type liquid crystal display device 100 is shown.
[0097]
FIG. 11 also shows the front light type external light / illumination type liquid crystal display device 200 by arranging the side light type light guide plate 2 on the viewing side of a conventional reflective liquid crystal display panel 201 having a reflective layer. An example is shown. 111, 116, and 211 are polarizing plates, 112 and 212 are light diffusion plates, 113, 115, and 213 are retardation plates, and 114 and 214 are liquid crystal cells that include a transparent electrode, a reflective layer, or an alignment film. Reference numeral 225 denotes a reflective layer.
[0098]
As shown in the figure, the liquid crystal display device can be formed by disposing the optical element 1 on at least one side of the liquid crystal cells 114 and 214 in the liquid crystal display panels 101 and 201. In that case, the optical element is generally arranged on at least one of the viewing side or the back side of the liquid crystal display panel so that the side having the light emitting means is the outside.
[0099]
As described above, the optical element can be formed as a transparent film type or a light guide plate type, and any of them can be used as a front light or a backlight. In general, a light guide plate type optical element is preferably used as a backlight. . An optical element, particularly a transparent film type, is preferably bonded to a liquid crystal cell or the like through an adhesive layer from the viewpoint of achieving bright display.
[0100]
Further, in an optical element, particularly a transparent film type optical element, it is disposed on at least one of the viewing side or the back side of the liquid crystal display panel, and one or more side surfaces or / and corners of the liquid crystal display panel, particularly optical It is also possible to form a panel illumination mechanism by arranging one or more lighting devices on one or more side surfaces and / or corners of the cell substrate on which the element 1 is arranged.
[0101]
In the case of the optical element having the light emitting means having the pit-like arrangement as in the example of FIG. 7, the pit-like arrangement is achieved from the point that the radial incident light from the point-like illumination device is efficiently used to achieve bright display. It is preferable to arrange a point-like illumination device on the side surface or / and the corner of the liquid crystal display panel on the vertical line including the virtual center of the light emitting means. The figure shows an optical element having light emitting means arranged in a pit shape, in which the illumination device is arranged at the corner of the liquid crystal display panel.
[0102]
As a lighting device disposed on the side surface of the light guide plate or the liquid crystal display panel, an appropriate device can be used. For example, in addition to a point light source such as a light emitting diode, a linear light source such as a (cold, heat) cathode tube, an array body in which point light sources are arranged in a line or surface, or a point light source and a linear light guide plate A combination of the incident light from the point light source and the linear illumination device via the linear light guide plate in combination can be preferably used.
[0103]
In addition, it is preferable that the illumination device is disposed on the light guide plate, the side surface of the liquid crystal display panel, or the like on which the optical path conversion slope of the optical element faces, from the viewpoint of emission efficiency. Including the above-mentioned pit arrangement, the incident light from the side surface and the corner through the illumination device is efficiently arranged by arranging the light path changing slope so as to face the illumination device as vertically as possible. It can be converted into a planar shape and can emit surface light with high efficiency.
[0104]
Therefore, in the case of an optical element having a light emitting means with a concave portion having a concave portion having a two-side optical path changing slope, and having a facing surface satisfying an inclination angle as an optical path changing slope, facing the light guide plate, cell substrate, etc. It is also possible to arrange a number of lighting devices corresponding to both the side surfaces and the corners. In the case of a pit arrangement, a point-like illumination device can be arranged at one place or two or more places corresponding to the virtual center of the light emitting means in the optical element.
[0105]
The illumination device enables visual recognition in the illumination mode by lighting, and in the case of an external light / illumination type liquid crystal display device, it is not necessary to be lit when visually confirming in the external light mode by external light. Therefore, it can be switched on / off. As the switching method, any method can be adopted, and any of the conventional methods can be adopted. Note that the illumination device may be of a different color light emission type capable of switching the emission color, or may be capable of emitting different color light through different types of illumination devices.
[0106]
For the lighting device, a combination body in which appropriate auxiliary means such as a reflector surrounding the light guide plate and the side surface of the liquid crystal cell, etc., are arranged as necessary to guide the divergent light to the side surface of the light guide plate or the liquid crystal cell. As the reflector, an appropriate reflection sheet such as a resin sheet, a white sheet, or a metal foil provided with a highly reflective metal thin film can be used. The reflector can also be used as a fixing means that also serves as an enclosure of the lighting device, for example, by bonding the end of the reflector to an end of a liquid crystal cell substrate or the like.
[0107]
In general, a liquid crystal display device includes a liquid crystal cell that functions as a liquid crystal shutter, an accompanying driving device, a front light or a backlight (optical element), and components such as a reflective layer and a compensation retardation plate as necessary. It is formed by assembling. In the present invention, there is no particular limitation except that an illumination mechanism is formed using an optical element and an illumination device, and the illumination mechanism can be formed according to a conventional front light type or backlight type.
[0108]
Accordingly, the liquid crystal cell to be used is not particularly limited. As shown in the figure, liquid crystal is sealed between cell substrates via a sealing material, and display light is obtained through light control by the liquid crystal or the like. A transflective type using a transflective reflective layer that transmits and reflects light such as a mold, a reflective type, or a half mirror can be used.
[0109]
Incidentally, specific examples of the liquid crystal cell include a TN type, STN type, IPS type, HAN type, OCB type, VA type twist type, non-twist type, guest host type, ferroelectric liquid crystal type liquid crystal cell, or Examples thereof include a light diffusion type liquid crystal cell such as an internal diffusion type. The liquid crystal driving method may be an appropriate one such as an active matrix method or a passive matrix method.
[0110]
In the reflective or transflective liquid crystal display device, the arrangement of the reflective layer or transflective layer is essential, but the arrangement position can be provided inside the liquid crystal cell as illustrated in FIG. It can also be provided outside the cell. Therefore, in the example of FIG. 11, the reflective layer 215 also serves as an electrode.
[0111]
For the reflective layer, for example, a coating layer containing a powder of high reflectivity metal such as aluminum, silver, gold, copper, or chromium in a binder resin, or a metal thin film attached layer by a vapor deposition method, the coating layer or the attached layer It can be formed as an appropriate reflective layer according to the prior art, such as a reflective sheet having a layer supported by a substrate, a metal foil, a transparent conductive film, or a dielectric multilayer film. The semi-transmissive reflective layer can also be formed as an appropriate semi-transmissive reflective layer according to the prior art, such as a half mirror, a reflective material-containing sheet, or a plurality of holes provided in the reflective layer.
[0112]
On the other hand, the transmissive liquid crystal display device can be manufactured by forming a backlight mechanism by arranging optical elements on the back side of the liquid crystal display panel as in the example of FIG. In that case, by providing a reflective layer on the back side (outside) of the light emitting means, it can be used for panel lighting by reflecting the light leaking from the light path changing slope and returning it to the direction of the liquid crystal cell, improving the brightness. Can be planned. Moreover, by making the reflective layer a diffuse reflection surface, the reflected light can be diffused and directed in the front direction, and can be directed in an effective direction by visual recognition.
[0113]
Furthermore, it is possible to form a transmissive and external light / illumination type liquid crystal display device by arranging the reflective layer. In that case, a transparent film type optical element can be particularly preferably used. The reflective layer disposed in the transmissive liquid crystal display device can conform to the reflective layer exemplified in the above reflective liquid crystal display device. In a reflective liquid crystal display device having a liquid crystal layer that modulates light by an electric field, a front light type in which an optical element is arranged on the viewing side of a liquid crystal cell as in the example of FIG. 11 is common.
[0114]
On the other hand, in the case of a transflective liquid crystal display device using a transflective reflective layer, the illumination mechanism can be formed by either the above-described front light system or backlight system. Accordingly, an optical element is arranged on both the viewing side and the back side of the liquid crystal display panel to form an external light / illumination type transflective liquid crystal display device provided with both front light and backlight illumination mechanisms. You can also
[0115]
In the above transmission type, when the reflective layer is disposed outside the liquid crystal cell, the cell substrate or electrode needs to be formed as a transparent substrate or transparent electrode in order to enable liquid crystal display. On the other hand, when a reflective layer is provided inside the liquid crystal cell as in the example of FIG. 11, the cell substrate or electrode on the viewing side must be formed as a transparent substrate or transparent electrode in order to enable liquid crystal display. However, the cell substrate on the back side does not need to be transparent like the reflective layer 215, and may be formed of an opaque body. In the case of a transflective type, it can conform to the above transmissive type or reflective type.
[0116]
When the cell substrate is used as the light transmission main body, the thickness can be appropriately determined according to the sealing strength of the liquid crystal, the size of the lighting device to be arranged, and the like. In general, the thickness is 10 μm to 5 mm, especially 50 μm to 2 mm, especially 100 μm to 1 mm, in view of the balance between light transmission efficiency and thin and light weight. In addition, the thickness of the cell substrate may be different between the side where the lighting device is disposed and the side where the lighting device is not disposed, or may be the same thickness. In the case of a transparent film type optical element, it is advantageous to increase the thickness of the cell substrate on the side where the illumination device is arranged in order to improve the luminance.
[0117]
When forming a liquid crystal display panel, an alignment film such as a rubbing film for aligning liquid crystals, a color filter, a low refractive index layer, a polarizing plate, a retardation plate, etc. for realizing color display are provided as necessary. Can do. In general, the alignment film is disposed adjacent to the liquid crystal layer, and the color filter is disposed between the cell substrate and the electrode. Note that a polarizing plate for the purpose of controlling display light via linearly polarized light can be disposed at one or both appropriate positions on the viewing side and the back side of the liquid crystal cell.
[0118]
The low refractive index layer described above reflects the incident light from the direction of the side surface and the corner through the lighting device, and efficiently transmits it to the rear in the direction far away from the lighting device. The purpose is to improve the uniformity of the brightness over the entire surface of the panel display surface. Therefore, the low refractive index layer can be advantageously applied in the case of a transparent film type optical element. The low refractive index layer can be formed as a transparent layer or an adhesive layer made of an appropriate low refractive index material made of an inorganic material or an organic material such as a fluorine compound depending on the arrangement position.
[0119]
The arrangement position of the low refractive index layer is preferably the inner side of the cell substrate on which the illumination device is arranged, that is, the surface opposite to the optical element mounting side of the substrate from the viewpoint of improving the brightness of the liquid crystal display. Further, a low refractive index layer having a refractive index of 0.01 or more, especially 0.02 to 0.15, particularly 0.05 to 0.10, is preferable from the viewpoint of improving the brightness of the liquid crystal display.
[0120]
When forming a liquid crystal display device, if necessary, a liquid crystal display panel having one or more appropriate optical layers such as a light diffusing layer and a retardation plate in addition to the above-described non-glare layer may be used. . The purpose of the light diffusing layer is to expand the display range by diffusing display light, to make the luminance uniform by leveling light emission, and to increase the amount of light incident on the optical element by diffusing transmitted light in the liquid crystal cell. The optical layer to be added can be applied to a liquid crystal cell by being laminated and integrated with an optical element via an adhesive layer or the like, if necessary.
[0121]
The light diffusing layer can be provided by an appropriate method using a coating layer or a diffusing sheet having a surface fine concavo-convex structure according to the non-glare layer. The light diffusing layer can also be arranged as a layer that also serves as an adhesive layer by blending transparent particles in the adhesive layer, whereby the liquid crystal display device can be thinned. One layer or two or more layers of the light diffusion layer can be disposed at an appropriate position such as between the optical element and the liquid crystal cell substrate on the viewing side.
[0122]
The retardation plate described above is usually disposed between the polarizing plate on the viewing side or / and the back side and the cell substrate as shown in the figure for the purpose of expanding the viewing angle by optical compensation and preventing coloring. As the retardation plate for compensation, an appropriate one can be used in accordance with the wavelength region or the like, and it may be formed as an overlapping layer of one or more retardation layers.
[0123]
The retardation plate is a birefringent film obtained by stretching a film made of an appropriate transparent polymer by an appropriate method such as uniaxial or biaxial, an appropriate liquid crystal polymer alignment film such as a nematic or discotic type, and the like. The alignment layer may be obtained by supporting it with a transparent substrate, or may be one in which the refractive index in the thickness direction is controlled under the action of the heat shrinkage force of the heat shrinkable film.
[0124]
In the reflection type liquid crystal display device of FIG. 11 described above, the visual recognition by both external light and illumination is such that the light emitted from the side having no optical element of the light guide plate passes through the liquid crystal cell in the illumination mode by lighting of the illumination device 3. After being reflected by the reflective layer 215, the light reaches the optical element via the liquid crystal cell in the reverse direction, and the display light transmitted from the portion other than the light emitting means A is visually recognized.
[0125]
On the other hand, in the external light mode by turning off the lighting device, light incident from a portion other than the light emitting means on the light emitting means forming surface of the optical element 1 passes through the reflective layer 215 and reversely passes through the liquid crystal cell according to the above. Thus, the display light transmitted through the portion other than the light emitting means is visually recognized.
[0126]
On the other hand, in the transmissive liquid crystal display device, the external light and the illumination are both visually recognized. In the illumination mode in which the illumination device is turned on, the light emitted from the optical element arranged on the back side enters the liquid crystal cell and is transmitted through the polarizing plate. Display light is visually recognized. In the external light mode by turning off the lighting device, the external light incident from the viewing surface passes through the liquid crystal cell and reaches the optical element, and the light incident from the portion other than the light emitting means on the light emitting means forming surface is the back surface. Display light that is inverted through the reflective layer provided on the liquid crystal cell and transmitted through the liquid crystal cell in the reverse direction is visually recognized. In the transflective liquid crystal display device, visual recognition is performed for both external light and illumination according to the reflection type and the transmission type.
[0127]
In the present invention, the components forming the non-light emitting display device such as the above-described liquid crystal display device may be wholly or partially stacked and integrated and fixed, or arranged in an easily separated state. May be. It is preferable to be in a fixed state from the viewpoint of preventing a decrease in contrast due to suppression of interface reflection. Moreover, it is preferable that the transparent film type optical element is in a fixed adhesion state. For the fixing treatment, an appropriate transparent adhesive such as a pressure-sensitive adhesive can be used, and the transparent adhesive layer can contain transparent particles or the like to form an adhesive layer exhibiting a diffusion function.
[0128]
In addition, the above-mentioned formed parts, particularly those on the viewer side, absorb ultraviolet rays by treating with ultraviolet absorbers such as salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, etc. It can also have a function.
[0129]
【Example】
Example 1
A UV-curable acrylic resin is dropped onto an unstretched PC (polycarbonate) film with a thickness of 60 μm with a dropper, spreads to a thickness of 25 μm with an applicator, and the coating layer is processed into a predetermined shape with a rubber roller in advance. After sticking to the mold and extruding excess resin and air bubbles, 300 mJ / cm of UV light is emitted from the metal halide lamp. ² The transparent film having a refractive index of 1.522 having light emitting means formed by irradiation was cured from the mold and cut into a predetermined size, and then separated from the unstretched PC film.
[0130]
Next, an acrylic adhesive layer having a refractive index of 1.520 is provided on the surface of the transparent film having a width of 20 mm and a length of 30 mm which does not have the light emitting means, and the transparent film is 25 mm in width and length through the adhesive layer. It was bonded to an acrylic resin plate having a thickness of 37 mm, a thickness of 1 mm, and a refractive index of 1.50 to obtain a light guide plate type optical element.
[0131]
The concave portion forming the light emitting means has a triangular cross section, a trapezoidal opening on the film surface, an optical path conversion slope forming side length of 100 μm, an opposing surface forming side length of 90 μm, and a width of It is about 10 μm, and has an optical path changing slope with an inclination angle of about 41 degrees with respect to the film surface and an opposing surface with about 72 degrees.
[0132]
Further, the light emitting means in the transparent film has a plurality of the concave portions arranged in a random arrangement position in parallel with the width direction of the film and with an even distribution density so that the light path changing slope faces the end surface in the width direction of the film. The film surface between the recesses is flat, and the area occupied by the openings of all the recesses on the film surface is about 1/15.
[0133]
In addition, manufacture of the metal mold | die used for formation of an above described transparent film is based on the following method. In other words, excimer laser light with a wavelength of 248 nm is irradiated with a beam width of 1.5 mm through a projection mask in which a metal foil is provided with a trapezoidal or rectangular opening of a predetermined shape, and the transmitted light of the projection mask is reduced to 1/15 through a lens. Then, in the method of irradiating the polyimide film fixed on the glass substrate, the aperture is opened from a 150 μm width while irradiating the laser beam at an etching rate of 0.26 μm / pulse, and two projection masks for shielding the aperture. Were moved at a constant speed in the width direction at different speed ratios of 30: 4 to form a closed state, and a concave portion having a triangular cross section formed by deep etching in the polyimide film toward the closing direction of the opening was formed.
[0134]
Next, after determining the basic arrangement of the recesses so as to have a predetermined density, the position of the etching process is changed with respect to the polyimide film based on the coordinate data generated by generating a restricted random number and randomizing the arrangement. While being repeatedly cleaned, an irradiated film (matrix) having a light emitting means is formed to make the surface with the recess conductive, and nickel-phosphorous is filled on the surface by electrocasting to a thickness of about 200 μm. After the metal layer is formed, the irradiated film is peeled off to obtain a mold having a convex portion forming surface corresponding to a predetermined light emitting means.
[0135]
Example 2
An optical element was obtained according to Example 1 except that the transparent film and the acrylic resin plate were bonded via an acrylic adhesive layer having a refractive index of 1.505.
[0136]
Example 3
An optical element was obtained according to Example 1, except that the transparent film and the acrylic resin plate were bonded via an acrylic ultraviolet curable adhesive layer having a refractive index of 1.52.
[0137]
Example 4
An optical element was obtained according to Example 1 except that an acrylic resin plate was used instead of the unstretched PC film, and a transparent film was directly formed and fixed on the resin plate.
[0138]
Example 5
A transparent film was produced in the same manner as in Example 1 except that a mold having a roughened surface by sandblasting was used, and an optical element was obtained in accordance with Example 1 using the transparent film. When the shape of the uneven surface as the light emitting means in the transparent film was evaluated using a Talysurf manufactured by Taylor Hobson, the maximum value of the inclination angle was about 15 degrees, and almost random unevenness was formed.
[0139]
Example 6
An optical element was obtained according to Example 1, except that the transparent film and the acrylic resin plate were bonded via an acrylic adhesive layer having a refractive index of 1.47.
[0140]
Example 7
A transparent film having a refractive index of 1.46 was formed in the same manner as in Example 1 except that a different ultraviolet curable resin was used, and an optical element was obtained according to Example 1 by using the transparent film.
[0141]
Example 8
A transparent film was formed in the same manner as in Example 1 except that a different mold was used, and an optical element was obtained according to Example 1 using the transparent film. The light emitting means has a concave portion forming a triangular cross section and a rectangular opening on the film surface, the length of the optical path conversion slope forming side and the length of the opposing surface forming side is about 30 μm, and the width is also about 30 μm. This is different from Example 1 only in that point. Accordingly, the inclination angle of the optical path changing slope is about 41 degrees, and that of the opposite surface is about 72 degrees.
[0142]
Example 9
A transparent film was formed in the same manner as in Example 1 except that a different mold was used, and an optical element was obtained according to Example 1 using the transparent film. The light emitting means has a concave section forming a triangular cross section and a rectangular opening on the film surface, the length of the optical path conversion slope forming side and the length of the opposing surface forming side is about 100 μm, and the width is about 10 μm. And differs from Example 1 only in that the inclination angle of the optical path changing slope is about 60 degrees. Therefore, the inclination angle of the facing surface is about 72 degrees.
[0143]
Example 10
A transparent film was formed in the same manner as in Example 1 except that a different mold was used, and an optical element was obtained according to Example 1 using the transparent film. The light emitting means has an opening on the film surface having a width of about 10 μm and a continuous groove having a triangular cross section continuous from one end to the other end at a pitch of 180 μm, and the inclination angle of the optical path conversion slope is about 41 degrees. The angle of inclination of the facing surface is about 72 degrees. The film surface between the continuous grooves is flat, and the area occupied by the openings of all the continuous grooves on the film surface is about 1/15.
[0144]
Evaluation test
A cold-cathode tube is arranged on the side surface of the optical element obtained in Examples 1 to 10 facing the optical path conversion slope, and is surrounded and held by a silver-deposited polyester film to form a sidelight-type light guide plate. A reflective liquid crystal display device of the front light type was manufactured by arranging on the upper surface of the reflective liquid crystal display panel so as to be on the viewing side. Next, the cold cathode tube was turned on in the dark room without applying a voltage to the liquid crystal cell, and the front luminance (BM7, manufactured by Topcon Corporation) at a position 10 mm (center of the screen) from the incident side surface was examined. Moreover, the light emission state and the state of moire were observed. The results are shown in the following table.
[0145]

The unit of front luminance is cd / m. ² It is.
[0146]
Examples 1-4, 8, and 10 were superior to Example 5 in terms of uniformity in addition to brightness. In Example 5, light was emitted at a large angle in the direction opposite to the light source, and the screen was dark without substantially contributing to the illumination of the liquid crystal display device. In Examples 6 and 7, the screen was darker than the example in the vicinity of the front.
[0147]
When the light guide plate was observed from the light emitting surface in the front light state, that is, the surface having no light emitting means, in Examples 1 to 4, light was emitted strongly in the vicinity of the front direction, whereas in Examples 6 and 7, Rather it was dark near the front. In Example 9, the emission toward the light source side was particularly strong, and the intensity of the emission was greatly reduced in the front direction.
[0148]
In Example 8, the brightness was slightly lower than in Examples 1 to 4, the tendency to become darker as the distance from the light source was stronger than in Examples 1 to 4, and white blurring due to scattering was larger than in Examples 1 to 4, making it difficult to see the display. . In Example 10, the brightness corresponded to Examples 1 to 4, but clear moire was observed.
[0149]
On the other hand, the visual recognition in the external light mode with the light source turned off was good in the other examples except that the moire was observed in the example 10.
[0150]
On the other hand, in Examples 1 to 4, the front and back sides of the sidelight type light guide plate are reversed, a reflective plate is arranged on the light emitting means side, and a transmissive liquid crystal display panel is arranged on the light emitting surface of the light guide plate to serve as a backlight. As a result, it was possible to realize a bright and easy-to-see transmission type liquid crystal display device. This liquid crystal display device can be seen in the external light mode even when the backlight is turned off in a bright environment, and is a good external light / illumination type (transmission type) liquid crystal display device.
[0151]
In addition, the transparent film obtained in Examples 1 to 4 is pasted on the viewing side of a reflective liquid crystal display panel in which a low refractive index layer having a refractive index of 1.38 is provided inside the cell substrate on the viewing side. When a cold cathode tube was arranged on the side of the panel, bright illumination could be realized without using a light guide plate.
[0152]
As described above, in the present invention, scattering of the transmission light by the side surface of the concave portion is prevented, the incident light in the horizontal direction is efficiently converted into the optical direction in the vertical direction, and the front directivity of the outgoing light is excellent, and scattered light and moiré are not easily generated. It can be seen that a transparent film type and a light guide plate type optical element having light emitting means can be formed.
[0153]
In addition, the transparent film type optical element can be pasted on a transparent plate to form a bright light-emitting clear light guide plate, and an illumination device is provided on the side of the panel pasted on a liquid crystal display panel, etc. On the other hand, the light guide plate type can also form a bright light-emitting clear light guide plate, and the light guide plate and illumination mechanism are less reflective and have a good display quality that is less likely to cause moire. It can be seen that a liquid crystal display device such as a transmission type, an external light / illumination type, etc. can be formed.
[Brief description of the drawings]
FIG. 1 is a sectional view of an optical element.
FIG. 2 is a sectional view of another optical element.
FIG. 3 is an explanatory sectional view of a recess.
FIG. 4 is an explanatory sectional view of another recess.
FIG. 5 is an explanatory plan view of a recess.
FIG. 6 is an explanatory diagram of light emitting means.
FIG. 7 is an explanatory diagram of other light emitting means.
FIG. 8 is a sectional view of still another optical element.
FIG. 9 is a sectional view of still another optical element.
FIG. 10 is a cross-sectional view of a liquid crystal display device
FIG. 11 is a cross-sectional view of another liquid crystal display device.
[Explanation of symbols]
1: Optical element
10A: transparent substrate
A: Recess
a: Optical path conversion slope
b: Opposing surface
x, y: concave side surface
20: Transparent plate
3: Lighting device
100, 200: Liquid crystal display device
101, 201: Liquid crystal display panel

Claims (20)

It has a light emitting means in which a plurality of recesses are discontinuously distributed on one side of the transparent substrate, and the recess has an optical path conversion slope and its opposing surface, and the recess has a surface on the transparent substrate surface. An optical element characterized in that the length of the optical path conversion slope forming side in the opening is at least three times the depth of the recess, and the projected area of the optical path conversion slope with respect to the vertical plane is larger than that of the opposing surface. 2. The optical element according to claim 1, wherein the transparent substrate is a film or plate having a refractive index of 1.49 or more. 3. The optical element according to claim 1, wherein the opening shape of the concave portion on the surface of the transparent substrate is a trapezoid, one of the parallel sides is an optical path conversion slope forming side, and the cross sectional shape of the concave portion is a triangle or a trapezoid. In Claim 3, the distance between the parallel sides in the opening trapezoid of the concave portion on the surface of the transparent substrate is 1 to 100 µm, the length of the optical path conversion slope forming side is 3 to 500 µm, and the depth of the concave portion is 1 to 100 µm. An optical element. 5. The optical element according to claim 1, wherein the inclination angle of the optical path conversion slope with respect to the plane formed by the transparent base material is 35 to 48 degrees and that of the opposing surface is 60 to 90 degrees. 6. The optical element according to claim 1, wherein the recesses are distributed in parallel to the end face of the transparent substrate or at an inclination angle of 3 to 10 degrees based on the optical path conversion slope. 6. The optical system according to claim 1, wherein the concave portion is distributed in a pit shape with respect to one or two or more virtual centers set on the end face or corner portion of the transparent base material or on the outside thereof based on the optical path conversion slope. element. The optical element according to claim 1, wherein an inclination angle of the optical path conversion slope with respect to a plane formed by the transparent substrate is 38 to 45 degrees. 9. The optical element according to claim 1, wherein the area based on the concave opening of the light emitting means occupying one side of the transparent substrate is 1/5 or less. 10. The optical element according to claim 1, wherein the arrangement of the concave portions forming the light emitting means is irregular. 11. The optical element according to claim 1, wherein the concave portions forming the light emitting means are arranged densely with distance from the end face or the virtual center of the transparent substrate. The optical element according to claim 1, wherein the transparent substrate has a transparent adhesive means on a side not having the light emitting means. 13. The optical element according to claim 12, wherein the adhesive means is an adhesive layer having a refractive index of 1.49 or more. The optical element according to claim 1, wherein a polarizing plate or a transparent plate is laminated on the side of the transparent substrate made of a film that does not have the light emitting means. 14. The optical element according to claim 12, wherein a release sheet is provided on the surface of the adhesive means. 2. The light emitting means is formed by repeating the operation of forming recesses by laser etching for irradiating a film to be irradiated made of a transparent substrate with laser light to partially remove the film to be irradiated. The manufacturing method of the optical element of ~ 11. A metal layer is formed by electroforming on the surface on which the light emitting means of the optical element is formed by the manufacturing method according to claim 16, and the form of the surface on which the light emitting means is formed by separating it from the optical element is transferred. The method of obtaining a mold, comprising: transferring a form of a surface having a convex portion capable of forming light emitting means in the mold to a transparent substrate, and then separating the mold from the mold. The manufacturing method of the optical element of 1-11. In Claim 17, transfer of the form of the surface which has a convex part which can form the light-projection means in a metal mold | die was made to stick the radiation-curable resin to the surface which has the said convex part, and the shape of the light-projection means was copied The manufacturing method of the optical element of Claims 1-11 performed by forming a shaping | molding layer and irradiating the radiation to the shaping | molding layer and making it harden | cure. The method for producing an optical element according to claim 1, wherein the molded layer is cured by irradiating radiation from the transparent substrate side in a state where the transparent substrate is in close contact with the molded layer. A liquid crystal display device comprising the optical element according to claim 1 or the optical element according to the method according to claim 16 arranged on at least one side of a liquid crystal cell in a liquid crystal display panel.

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