JP2004151406A - Method for manufacturing optical film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a method for manufacturing an optical film formed by dispersing and distributing fine structured recesses with light reflecting slopes whose specular reflection factors are superior. <P>SOLUTION: In the method for manufacturing the optical film, the plurality of triangularly sectioned recesses with optical path converting slopes are discontinuously distributed on one surface of a high polymer film (5) through laser etching carried out through a projection mask (2) comprising one or more masks forming a laser light transmission part (21) which continuously varies an etching quantity per unit area along the depth of the formed recesses by continuously varying an integral value of laser light transmission along the short sides of the formed recesses (51) and an auxiliary laser light transmission part which controls surface roughness of the formed optical path converting slopes. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an optical film capable of forming a thin, lightweight, bright, and easy-to-view liquid crystal display device by efficiently changing the optical path of light incident from the side surface of a liquid crystal display panel in the viewing direction.
[0002]
BACKGROUND OF THE INVENTION
Conventionally, there has been known a front light type reflection type liquid crystal display device in which a side light type light guide plate having a light emitting means having a stripe prism structure is arranged on the viewing side surface of a liquid crystal display panel (Japanese Patent Laid-Open No. 11/1997). -250715). Such light emitting means is formed by a machining method in which the surface of the template is cut with a diamond tool or the like, or a dry etching method in which a triangular projection mask is scanned.
[0003]
However, the striped prism structure interferes with the pixels of the liquid crystal panel and causes moiré, which tends to degrade the display quality. In the front light type in which the light guide plate is located in front of the liquid crystal display panel, the surface reflection of external light Therefore, the contrast of the liquid crystal display tends to be lowered, defects such as scratches on the light guide plate are easily noticeable, and the use of the light guide plate makes it bulky and heavy.
[0004]
[Technical Problem of the Invention]
In view of the above, the present inventors have come up with a system using a light emitting means in which a large number of minute size recesses (grooves) are dispersed and distributed. According to this, it is possible to easily overcome the above-described moire problem, surface reflection problem, visual obstruction problem due to defects, bulkiness / heavy weight problem, and the like.
[0005]
However, it has been difficult to manufacture a light emitting means in which such minute size concave portions are distributed and distributed by a conventional method. By the way, it is extremely difficult to form an intermittent structure in which micro-sized concave portions are dispersed and distributed accurately at a predetermined position by machining, and it is extremely difficult to form an intermittent structure of concave portions having a constant cross-sectional shape even by a method using a diamond grindstone. Have difficulty. Further, even in a dry etching method in which a triangular projection mask is scanned, the surface roughness of the inclined surface serving as a light reflecting surface is large, and it is difficult to form a mirror surface with a poor specular reflectance.
[0006]
In view of the above, the present invention can form a thin, light, bright, easy-to-view liquid crystal display device by efficiently converting the light incident from the side surface or corner of the liquid crystal display panel in the viewing direction. It is an object to develop a manufacturing method capable of obtaining a thin and light optical film having a light emitting means in which a concave portion having a fine structure that is dug at an acute angle and a light reflecting slope has excellent specular reflectance is distributed with high positional accuracy. And
[0007]
[Means for solving problems]
The present invention irradiates a laser beam through a projection mask, controls the size of the laser beam transmitted from the projection mask through an optical device that creates a projection image, and changes the irradiation amount of the laser beam. While irradiating the polymer film, at least one of the projection mask or the polymer film is moved, and the polymer film forming material is partially removed by laser etching to thereby remove the polymer film. An optical path changing slope with an inclination angle of 35 to 48 degrees with respect to a plane and an elevation surface with 50 to 90 degrees, a cross section having a triangular shape, and a plurality of concave portions having rectangular openings in the polymer film surface. The light emitting means is formed on one surface of the polymer film so as to be discontinuously distributed, and the projection mask continuously calculates the integral value of the amount of laser light transmission in the short side direction of the concave portion to be formed. Change to form The surface roughness Ra of the laser beam transmitting portion that continuously changes the etching amount per unit area in the depth direction of the recessed portion and the optical path conversion slope formed through the laser beam transmitting portion is controlled to 5 to 500 nm. The present invention provides a method for producing an optical film comprising one or two or more masks forming an auxiliary laser beam transmitting portion.
[0008]
Further, the present invention is to form a metal layer by electroforming on the surface on which the light emitting means of the optical film manufactured by the above method is formed, and then obtain the mold by separating the metal layer and the optical film. A method of manufacturing a mold for forming an optical film, and a surface of the optical film forming mold having a convex portion capable of forming a light emitting means, and a radiation curable resin is adhered to the surface of the light emitting means. A method for producing an optical film, comprising forming a molded layer reflecting the shape, irradiating the molded layer with radiation and then curing the molded layer, and separating the mold from the mold, and the optical film produced by the method described above as a liquid crystal The present invention provides a liquid crystal display device which is arranged on at least one side of a cell.
[0009]
【The invention's effect】
According to the present invention, the distribution of the concave portions of the fine structure in which both end portions are dug at an acute angle is distributed with high accuracy by using a laser etching method that regulates the planar size and depth of etching through a plurality of projection masks. An optical film having a light emitting means can be obtained, and light incident from the side surface of the liquid crystal display panel is efficiently converted into a viewing direction by using the optical film to make a thin, lightweight, bright and easy-to-view liquid crystal display. A device can be formed. In particular, in a method in which a radiation curable resin is molded into a predetermined shape and cured through a die formed by electroforming, an optical film having a predetermined light emitting means can be obtained efficiently.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The manufacturing method according to the present invention irradiates a laser beam through a projection mask, controls the size of the laser beam transmitted from the projection mask through an optical device that creates a projection image, and the irradiation amount of the laser beam. By irradiating the polymer film with a change in the position, moving at least one of the projection mask or the polymer film and partially removing the polymer film forming material by laser etching, A concave portion having an optical path changing slope having an inclination angle of 35 to 48 degrees with respect to the polymer film plane and an elevation surface having a tilt angle of 50 to 90 degrees and having a triangular cross section and a rectangular opening on the polymer film surface Are formed on one surface of the polymer film to form a light emitting means which is discontinuously distributed to obtain an optical film, and the projection mask is a laser beam in the short side direction of the recess to be formed. Transmission amount A laser beam transmitting part that continuously changes the fractional value and continuously changes the etching amount per unit area in the depth direction of the recess to be formed, and an optical path conversion formed through the laser beam transmitting part. It consists of one or two or more masks that form an auxiliary laser light transmitting portion that controls the surface roughness Ra of the slope to 5 to 500 nm.
[0011]
Examples of steps of the manufacturing method described above are illustrated in FIGS. DESCRIPTION OF SYMBOLS 1 is a laser oscillator, 2 is the projection mask which formed the laser beam permeation | transmission part 21 and 22 of a predetermined shape, 4 is a lens as an optical apparatus which produces the projection images 41 and 42 of a laser beam, 5 is the high which receives irradiation of a laser beam The molecular film 51 includes an optical path changing slope with an inclination angle of 35 to 48 degrees with respect to a plane formed by the polymer film 5, and an elevation surface with 50 to 90 degrees. The opening on the film surface is a rectangular recess.
[0012]
Reference numeral 3 denotes a preliminary mask on which a laser beam transmitting portion 31 having a predetermined shape is formed, 2A and 3A are mask stages for fixing and holding the projection mask 2 or the preliminary mask 3, and 6 is a work stage for fixing and holding the polymer film 5. The mask stage 2A and the work stage 6 in the illustrated example can move independently in the respective X-axis, Y-axis, and Z-axis directions based on three-dimensional Cartesian coordinates via a driving source (not shown), and the X-axis, Y-axis Axial rotation is possible on each of the axis and the Z axis.
[0013]
Therefore, the position and the arrangement angle of the projection mask 2 can be controlled independently of the polymer film 5 through movement or / and axial rotation of the mask stage 2A in the respective axial directions. Further, the position and the arrangement angle of the polymer film 5 can be controlled independently of the projection mask 2 through movement or / and axial rotation of the work stage 6 in each axial direction.
[0014]
Further, the laser oscillator 1 and the optical device 4 can be independently moved and rotated in the respective axial directions, and the position and the arrangement angle with respect to the mask stage 2A (projection mask 2) can be controlled. . Also, the mask stage 3A can be independently moved and rotated in the respective axial directions, and the position and the arrangement angle with respect to the mask stage 2A (projection mask 2) can be controlled.
[0015]
In the illustrated example, after the laser oscillator 1, the mask stage 3A, and the optical device 4 control the position and the arrangement angle with respect to the projection mask 2, the state is maintained as a fixed system when the recess is formed. However, they can also be formed so as to be integrally movable or / and axially rotatable in conjunction with the mask stage 2A as necessary.
[0016]
As described above, the laser light based on the laser oscillator 1 is projected onto the projection mask 2 through the auxiliary mask 3 as necessary, and the projected laser light is transmitted to the laser light transmitting portions 21 and 22 and the auxiliary laser in the projection mask 2. The light is transmitted from the light transmitting portion, and the portions other than these light transmitting portions shield other laser light as unnecessary light, and the size of the laser beam image based on the transmitted light is controlled via the lens 4. The polymer film 5 is irradiated, and the polymer film forming material is etched by the laser beam to disappear and removed.
[0017]
The preliminary mask 3 arranged as necessary in the above is intended to project the laser beam based on the laser oscillator 1 into a rectangular shape and project it onto the projection mask 2 as illustrated in FIG. That is, the laser light based on the laser oscillator 1 is transmitted from the laser light transmitting portion 31 in the preliminary mask 3, and the portions other than the light transmitting portion shield other laser light from unnecessary light and block the transmission to make the laser light rectangular. The rectangular laser beam image is projected onto the projection mask 2. In the example shown in the figure, the preliminary mask 3 is formed by a single mask, but a method of forming a target laser beam transmitting portion by using two or more masks can also be adopted.
[0018]
The laser beam transmitting portion of the preliminary mask 3 is usually formed as a rectangular transmitting portion because the laser beam is formed into a rectangular shape. The rectangular laser beam transmitting portion only needs to form a rectangular laser beam image in which at least a pair of sides facing each other form a parallel relationship, and the laser beam image is projected onto the polymer film 5 via the optical device 4. In this case, it is preferable that the length in the long side direction of the projected image is equal to or longer than the length in the long side direction of the recess formed in the polymer film. Note that the rectangle and the parallel relationship thereof do not have to be exact, and deformation based on manufacturing accuracy and the like is allowed.
[0019]
Therefore, when the preliminary mask 3 is disposed, the projection mask 2 functions as a control mask for the laser beam image via the preliminary mask 3 and is formed in the short side direction of the rectangular laser beam image formed via the preliminary mask 3. The integral value of the laser beam transmission amount in the short side direction of the recess (rectangular shape) is continuously changed, and the etching amount per unit area in the depth direction of the formed recess is continuously changed. In the example shown in the figure, the projection mask 2 is also formed by a single mask, but a method of forming a target laser beam transmitting portion with two or more masks can also be adopted.
[0020]
In the example shown in FIG. 1, while the laser beam is irradiated onto the polymer film, the projection mask 2 is scanned through the mask stage 2A in the direction of the long side of the concave portion to be formed as indicated by the arrow, so that the moving distance is increased. Accordingly, the polymer film forming material can be continuously removed, and the deeper the etching is performed at the position where the integral value of the laser beam transmission amount is larger, and the target cross-sectional shape as shown in FIG. Can be formed. In this case, when the preliminary mask 3 is arranged as in the example of FIG. 2, by scanning in the long side direction of the rectangular laser beam image formed by the preliminary mask 3, the movement distance or the shape of the rectangular shape is determined. A recess is formed according to the length in the long side direction.
[0021]
On the other hand, in the example of FIG. 2, the projection mask 2 is formed on the preliminary mask 3 as shown by the arrow through the mask stage 2A while irradiating the polymer film with the laser beam, and thus is formed in the short side direction. By scanning in the short side direction of the target concave part, the polymer film forming material can be continuously removed according to the moving distance or the length of the molding rectangle in the short side direction, and the integration of laser light transmission amount The deeper the position is, the deeper the etching is performed, and the concave section (groove) 51 having a triangular target cross-sectional shape as shown in the figure can be formed. The triangle may not be strict, and deformation based on manufacturing accuracy and the like is allowed.
[0022]
Then, by moving the polymer film 5 through the work stage 6 and repeating the etching operation described above by intermittent laser irradiation, the forming material at a predetermined position of the polymer film is partially removed, and the concave portions are distributed and distributed. The light emitting means can be formed. Therefore, the movement of the polymer film 5 through the works stage is made random, and by making the moving distance different in length, it is easy to form the light emitting means in which the concave portions are randomly arranged and the distribution density changes. can do.
[0023]
As described above, at least the projection mask 2 that regulates the depth of etching removal is used, and if necessary, the plane size of laser irradiation, particularly the preliminary mask 3 that regulates the length in the long side direction, is used to make a triangular cross section. An optical film having a light emitting means that can form a micro-sized concave portion in which both ends in the long side direction are cut at acute angles, and that the concave portion is discontinuously distributed and distributed. Can be manufactured.
[0024]
In order to form the concave portion having the triangular cross section in the above, the shape of the laser light transmitting portion provided in the projection mask 2, that is, the short side direction of the concave portion to be formed, and accordingly, when the preliminary mask 3 is used, the shape is formed there Projection to continuously change the etching amount per unit area in the depth direction of the formed recess by continuously changing the integral value of the laser light transmission amount in the short side direction of the rectangular laser beam image About the shape of the laser beam transmission part in the mask 2, it can determine suitably.
[0025]
Incidentally, in the example of FIG. 1, the integrated value of the laser light transmission amount can be continuously changed based on the shape of the laser light transmission part 21 in the projection mask 2. That is, by making the shape of the laser beam transmitting portion 21 triangular as shown in FIG. 3, the integrated value of the laser beam transmission amount can be continuously increased from the apex to the base.
[0026]
Therefore, when the projection mask 2 having a triangular laser beam transmitting portion is used, the size of the laser beam image transmitted through the projection mask 2 is controlled via an optical device, and a predetermined dimension, particularly the height of the triangular beam image is adjusted. While irradiating the polymer film as a laser beam image having the same length as the short side direction of the concave portion to be formed, the projection mask 2 and / or the polymer film 5 is placed on the bottom of the triangle as indicated by the arrow in the example of FIG. By moving a predetermined distance in the parallel direction, it is possible to form a recess having a triangular cross-sectional shape and a rectangular opening on the polymer film surface.
[0027]
Further, by repeating the above operation with respect to a predetermined position of the polymer film, light emission in which a plurality of the concave portions 51 are discontinuously distributed on one surface of the polymer film 5 as illustrated in FIGS. An optical film having means can be obtained. Note that by controlling the apex angle of the triangle forming the laser beam transmitting portion, the angle of the optical path changing slope in the formed recess can be adjusted. The triangle may be an isosceles triangle as shown in the figure, or may not be an isosceles like a right triangle.
[0028]
When the projection mask 2 having a triangular laser beam transmitting portion is used, a preferable method for manufacturing an optical film is a method using a preliminary mask as necessary. That is, the length of the long side direction of the rectangular laser beam image formed (shaped) through the preliminary mask 3 is determined based on the projected image on the polymer film 5 through the optical device. The laser beam is made rectangular through the preliminary mask 3 so that the length in the short side direction of the laser beam image is equal to or longer than the length in the short side direction of the concave portion to be formed. The projection mask 2 having a triangular laser beam transmitting portion is scanned from one end to the other end in the long side direction of the rectangular laser beam image by the preliminary mask 3 under the irradiation of the rectangular laser beam image. is there.
[0029]
According to the above, the etching amount can be continuously changed in the short side direction of the rectangular laser beam image by the preliminary mask 3 via the projection mask 2, and the long side direction of the rectangular laser beam image by the preliminary mask 3 can be changed. The long side length of the concave portion to be formed can be made constant, and the short side length of the concave portion to be formed can be made constant by being regulated by the height of the triangle forming the laser light transmitting portion of the projection mask 2 Can be
[0030]
On the other hand, in the example of FIG. 2, the unit area in the depth direction of the concave portion to be formed by using the projection mask 2 having the rectangular laser light transmission portion 22 and continuously changing the integral value of the laser light transmission amount. The hit etching amount is continuously changed. In this method, a spare mask 3 is used as in the example of FIG. That is, under irradiation of a rectangular laser beam image formed through the preliminary mask 3, the laser light transmitting portion 22 of the projection mask 2 is moved in the short side direction of the rectangular laser beam image, so Based on the length of the overlapping time between the laser beam image of the shape and the laser beam transmitting portion 22 of the projection mask 2, the integrated value of the laser beam transmission amount is continuously changed.
[0031]
A preferable manufacturing method of the optical film when the projection mask 2 having the rectangular laser beam transmitting portion is used is as follows. That is, first, the length in the long side direction and the short side direction of the rectangular laser beam image formed (shaped) through the preliminary mask 3 is based on the projection image on the polymer film 5 through the optical device. The laser beam is shaped into a rectangular shape through the preliminary mask 3 so that it is equal to or longer than the lengths of the long side direction and the short side direction of the concave portion to be formed.
[0032]
Next, when the size of the rectangular laser beam image by the preliminary mask 3 is larger than the size of the concave portion to be formed, the projection mask 2 having a rectangular laser beam transmitting portion having the same size as the concave portion is provided. On the other hand, when the size of the rectangular laser beam image by the preliminary mask 3 is the same as the size of the concave portion to be formed, the projection having a rectangular laser beam transmitting portion having an arbitrary size larger than the size of the concave portion. The mask 2 is scanned in the short side direction of the rectangular shape as shown in the figure so that the laser light transmitting portion 22 passes through the irradiation of the rectangular laser beam image by the preliminary mask 3, and the short of the concave portion to be formed is shortened. This is a method in which the irradiation of the laser beam is stopped when the side length is scanned.
[0033]
The scanning in the short side direction of the rectangular shape of the projection mask 2 described above may be either in the direction in which the total etching amount per unit area increases or in the direction in which it decreases. However, in the case of scanning in the increasing direction of the former, laser irradiation is started with the laser light transmitting portion 22 of the projection mask 2 positioned within the irradiation of the rectangular laser beam image by the preliminary mask 3, and the projection mask. 2 scan is started. On the other hand, when scanning is performed in the latter direction in which the total etching amount per unit area decreases, the laser light transmitting portion 22 of the projection mask 2 is positioned outside the irradiation of the rectangular laser beam image by the preliminary mask 3. Scanning of the projection mask 2 is started. In this case, the laser irradiation can be started before the scanning of the projection mask 2 is started.
[0034]
According to the above, the superposition time between the rectangular laser beam image of the preliminary mask 3 and the laser light transmitting portion 22 of the projection mask 2 can be adjusted through the scanning of the projection mask 2, and based on the length of the superposition time, The integral value of the laser beam transmission amount in the short side direction of the rectangular laser beam image by the preliminary mask 3 can be continuously changed to change the etching amount continuously, and the rectangular laser beam image by the preliminary mask 3 can be changed. Depending on the size or the size of the laser light transmitting portion of the projection mask 2, it is possible to form a recess having a triangular cross section and a certain size.
[0035]
In the present invention, as shown in FIG. 7A, the optical path changing slope a having an inclination angle θ1 of 35 to 48 degrees with respect to the plane formed by the polymer film 5 and an inclination angle θ2 of 50 to 90 degrees are established. A light emitting means comprising a plurality of concave portions 51 each having a surface b and having a triangular cross-sectional shape and a rectangular opening in the polymer film surface on one surface of the polymer film. It is formed to obtain an optical film.
[0036]
In the above, the optical path changing slope formed through the laser light transmitting portion of the projection mask is when the optical film is disposed on the liquid crystal display panel and light is incident through the light source from the side or corner of the liquid crystal cell. An object of the present invention is to reflect the incident light or the transmitted light, change the optical path in the viewing direction of the liquid crystal display panel, and emit the light.
[0037]
In the above case, it is preferable that the light path conversion inclined surface is excellent in specular reflectance from the point of light path conversion with good directivity in the viewing direction of the liquid crystal display panel, particularly the front direction. Accordingly, the smoother the optical path conversion slope is, the better, but it is difficult to polish the recess after the etching process. Therefore, it is necessary to achieve the formation of an optical path changing slope with a smooth surface during the etching process described above.
[0038]
For the purpose of achieving the above, in the present invention, specifically, an optical path changing slope having a surface roughness Ra of 5 to 500 nm, especially 10 to 400 nm, particularly 20 to 300 nm is formed during the etching process. The projection mask is provided with an auxiliary laser light transmission part for controlling the surface roughness of the inclined surface together with the laser light transmission part described above. Examples thereof are shown in FIGS. Reference numerals 21a to 21d and 22a to 22d denote auxiliary laser light transmitting portions.
[0039]
The auxiliary laser light transmitting part is arranged with respect to the side intersecting the moving direction when forming the projection mask or the concave portion of the polymer film in the laser light transmitting parts 21 and 22 as shown in the figure. Accordingly, when the laser light transmitting portion in the projection mask is a triangle as in the example of FIG. 1, the projection mask or the polymer film is moved in parallel with the bottom of the triangle 21 as indicated by an arrow, thereby crossing the moving direction. Auxiliary laser beam transmitting portions 21a to 21d are provided for one or both of the two sides other than the bottom side.
[0040]
On the other hand, when the laser light transmitting portion in the projection mask is rectangular as in the example of FIG. 2, the movement direction is determined by moving the projection mask or the polymer film in the short side direction of the rectangle 22 as indicated by an arrow. Auxiliary laser light transmitting portions 22a to 22d are provided for one or both of the two long sides that intersect.
[0041]
The auxiliary laser beam transmitting portion may have an appropriate form that can finely adjust the amount of laser beam irradiation, but is generally a slit-shaped opening as shown in the figure. The long side length of the opening is 60 to 120%, especially 80 to 110%, particularly 90 to 100% of the length of the arrangement side in the laser light transmitting portion.
[0042]
The short side length of the opening is 1/500 to 1/5, especially 1/300, of the short side length of the concave portion to be formed based on the size of the projected image on the polymer film via the optical device. ˜1 / 10, 1/200 to 1/15. Therefore, in the case of using the laser light transmitting portion, the auxiliary laser light transmitting portion is formed of an opening having the above-mentioned ratio of the short side length based on the height of the triangle and the short side length of the rectangle.
[0043]
The number of auxiliary laser light transmitting portions arranged can be determined as appropriate. In general, it is preferable that the number of the triangular laser light transmitting portions is 4 or less, and in particular, 2 or less based on each side, and it is parallel to the arranged side at a position close to the outside of the arranged side or within 30 degrees. It is preferable to arrange at an intersection angle. On the other hand, in the case of a rectangular laser beam transmitting portion, the number of arrangement and the arrangement position can be the same as in the case of the triangle. It is possible to adjust the surface roughness of the slope formed by controlling the short side length and the number of arrangement of the openings forming the auxiliary laser light transmitting portion.
[0044]
In the above, examples of the laser oscillator include an excimer laser, a YAG laser, and CO. ₂ One type or two or more types of lasers and femtosecond lasers can be used. In particular, ablation processing using an oscillator that can obtain laser light in an ultraviolet region having a wavelength of 400 nm or less is preferable from the viewpoint of fine processing accuracy and the like.
[0045]
The shape and size of the recesses to be formed, and the distribution state of the dispersion distribution depend on the resolving power and positioning accuracy of the laser processing machine with the addition of optical equipment, etc. Therefore, it is preferable to use a high-precision processing machine.
[0046]
As the projection mask and the preliminary mask, an appropriate mask made of an ultraviolet shielding material such as metal can be used. A glass mask or the like formed by depositing an appropriate ultraviolet shielding material such as a metal or a dielectric on a glass plate made of quartz or the like and patterning the deposited layer to form a laser light transmitting portion can also be used. In this case, it is easy to form a filter type laser beam transmitting portion.
[0047]
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. Note that, as described above, two or more of the projection masks and the preliminary masks can be overlapped and used for laser light irradiation. With this superposition method, the laser light transmittance in the laser light transmitting portion can be partially changed to have a filter effect.
[0048]
When forming each concave portion as described above, and further, forming a light emitting means in which a plurality of the concave portions are distributed, at least one of the projection mask and the polymer film is moved. A method of moving both of the molecular films in synchronization can also be adopted.
[0049]
The polymer film can be made of any suitable material that exhibits electrical insulation and can be etched with laser light, and is not particularly limited. In general, a polymer film is used. In particular, from the viewpoint of workability by laser light in the ultraviolet region, an ultraviolet-absorbing material made of ultraviolet-curing resin such as acrylic, methacrylic or urethane is preferred. Moreover, the thing excellent in the transmittance | permeability of visible light region is preferable. Although the film thickness is arbitrary, it is preferably 500 μm or less, and particularly preferably 10 to 200 μm, from the viewpoints of handling properties during processing, sharpness of edge portions in formed recesses, flatness of processed surfaces, and the like.
[0050]
By the way, examples of the polymer film include polyester resin, epoxy resin, urethane resin, polystyrene resin, polyethylene resin, polyamide resin, polyimide resin, ABS resin, polycarbonate resin, silicone resin, acrylic resin. Examples thereof include a coating film and a film made of a resin, a cellulose resin, and a norbornene resin.
[0051]
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 A and B with a thermoplastic resin having an unsubstituted phenyl group and a nitrile group, and specific examples thereof include an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. Examples thereof include a coating film and a film made of a resin composition containing a coalescence. The film can be a film made of a mixed extruded product of the resin composition.
[0052]
A polymer film preferable from the viewpoints of heat resistance, chemical resistance, and laser processability is a coating film or film made of a thermosetting resin, particularly a polyimide resin. The polymer film can be held on a glass substrate or a metal plate and placed on the work stage as necessary.
[0053]
The optical film can be manufactured integrally by the above-described method. From the viewpoint of mass productivity, the preferred method for producing an optical film is to produce a mold for forming an optical film using the optical film obtained by the above method as a mother mold, and mass-produce the optical film using the mold. It is a method to do.
[0054]
In the above method, for example, a metal layer is formed by electroforming on the surface on which the light emitting means of the optical film serving as a master is formed, and then the metal layer and the optical film are separated to form a mold for forming the optical film. A radiation-curable resin is brought into close contact with the surface of the mold having a convex portion that can form the light emitting means, and a molding layer that reflects the shape of the light emitting means is formed, and radiation is applied to the molding layer. Can be carried out by a method of separating the produced optical film from the mold.
[0055]
A process example of the method is shown in FIG. The illustrated example shows from the mold formation (A to C) to the optical film formation (D, E). As shown in the figure, the optical film 8 is a light emitting means comprising a plurality of concave portions having an optical path changing slope a having an inclination angle θ1 of 35 to 48 degrees with respect to the film surface through a mold 7 having a predetermined convex portion 71. It is formed by molding.
[0056]
The mold 7 is formed by applying an electroforming method to a polymer film (optical film) 5 provided with a light emitting means composed of a plurality of predetermined concave portions 51 as shown in FIG. 7A. Thereby, as shown in FIG. 7C, the mold 7 having the convex portions 71 corresponding to the high accuracy in the concave portions 51 provided in the polymer film 5 can be formed.
[0057]
As the electrocasting method, a metal mold having a replica in which a surface of the polymer film on the side provided with the concave portion is filled with metal on the side provided with the concave portion of the polymer film is used. A conventional method can be applied. Therefore, when forming the metal layer, the conductive film is provided on the side of the polymer film where the concave portion is provided, and a method according to the related art can be applied to the formation of the conductive film.
[0058]
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.
[0059]
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 separating from the polymer film and handling properties when forming an optical film It is preferable to use a mold according to.
[0060]
The optical film 8 is formed, for example, as shown in FIG. 7D, in a state in which a radiation curable resin is applied to and supported on a transparent film or the like as necessary, and is brought into close contact with the surface of the mold 7 where the convex portions 71 are 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. This is done by separating 8 from the mold 7.
[0061]
As described above, as shown in FIG. 7E, the surface shape on the convex portion forming side of the mold has the concave portion 81 and the surface shape corresponding to the high accuracy. Therefore, the light emitting means in the matrix polymer film 5 is reproduced with high accuracy. And an optical path conversion slope a having an inclination angle θ1 of 35 to 48 degrees with respect to the film surface and a surface roughness Ra of 5 to 500 nm, and an elevation face b having an inclination angle θ2 of 50 to 90 degrees, An optical film 8 having a light emitting means in which a plurality of concave portions 81 having a triangular shape and a rectangular opening on the film surface are discontinuously distributed on one surface is obtained.
[0062]
In the above, a preferable method for producing an optical film is that a deformable mold is attached to the outer periphery of a columnar or cylindrical circular rotating body, and the mold is rotated while rotating the mold through the rotating body. Applying radiation-curable resin coating layers on a long transparent film in sequence to form a molding layer that reflects the mold surface shape, and then irradiating the molding layer with radiation through the transparent film Thus, the optical film is continuously produced.
[0063]
As described above, the method of the present invention is an optical path changer having an inclination angle of 35 to 48 degrees and a surface roughness Ra of 5 to 500 nm with respect to the plane formed by the polymer film 5 or film (8) as shown in FIGS. A plurality of concave portions 51 (81) having a slope and an elevation surface of 50 to 90 degrees, having a triangular cross-sectional shape, and having a rectangular opening in the polymer film surface or film surface on one side, are discontinuous. An optical film 5 (8) having light emitting means distributed is obtained.
[0064]
The optical film reflects light incident from the side or corner of the liquid crystal cell through a light source or its transmitted light through an optical path changing slope and reflects it on the back side (the side not having the light emitting means), and thus the liquid crystal. The light path is changed in the viewing direction of the display panel and emitted, and the emitted light can be used as illumination light (display light) for a liquid crystal display panel or the like. Therefore, the optical film is usually 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.
[0065]
In the above, the transparent film that may be used to support the radiation curable resin and form an optical film, if necessary, is made of an appropriate material that exhibits transparency according to the wavelength range of light incident through a light source or the like. It can be formed using one kind or two or more kinds. Incidentally, in the visible light region, for example, transparent resins represented by those exemplified in the above polymer film, and curable resins that can be polymerized with ultraviolet rays such as heat, ultraviolet rays, and electron beams are listed.
[0066]
From the standpoint of obtaining a liquid crystal display device that is bright and excellent in its uniformity by increasing the efficiency of incidence on the light path conversion slope, the preferable refractive index of the transparent film is equal to or higher than that of a liquid crystal cell, particularly its cell substrate. .49 or more, particularly 1.52 or more. In addition, the refractive index is preferably 1.6 or less, particularly 1.56 or less, particularly 1.54 or less, from the viewpoint of suppressing surface reflection when the front light system is used. Note that such a refractive index is generally based on D-rays in the visible light region, but is not limited to the above when there is specificity in the wavelength region of incident light, and depends on the wavelength region. (The same applies below).
[0067]
A transparent film preferable from the viewpoint of suppressing liquid crystal unevenness and color unevenness and obtaining a liquid crystal display device with less display unevenness is one that does not exhibit birefringence or has low birefringence, and in particular, an in-plane average phase difference of 50 nm. It is as follows. By using a transparent film having a small phase difference, when linearly polarized light is incident through an optical film or the like, the polarization state can be maintained well, which is advantageous for preventing deterioration in display quality.
[0068]
From the viewpoint of preventing display unevenness, the preferable in-plane average phase difference in the transparent film is 30 nm or less, especially 20 nm or less, particularly 10 nm or less, and the variation of the phase difference from place to place is as small as possible. preferable. Furthermore, the transparent film which consists of material with a small photoelastic coefficient is preferable from the point which suppresses the internal stress which generate | occur | produces in a transparent film and prevents generation | occurrence | production of the phase difference by the internal stress. In addition, the average retardation in the thickness direction of the transparent film is preferably 50 nm or less, more preferably 30 nm or less, and particularly preferably 20 nm or less from the viewpoint of preventing display unevenness.
[0069]
Such a low retardation film can be formed by an appropriate method such as a method of annealing an existing film, or a method of removing internal optical distortion. A preferable forming method is a method of forming a transparent film having a small phase difference by a casting method. The retardation in the transparent film is preferably based on visible light, particularly light having a wavelength of 550 nm.
[0070]
The in-plane average 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 film plane, ny is the average refractive index in the direction perpendicular to the nx direction in the film plane, and nz is the average refractive index in the thickness direction of the film. , D means the average thickness of the film.
[0071]
The transparent film is usually formed as a single layer, but may be formed as a laminate made of the same or different materials. The thickness of the transparent film can be appropriately determined and is not particularly limited, but is preferably 5 to 500 μm, more preferably 10 to 300 μm, and particularly preferably 20 to 100 μm from the viewpoints of reduction in thickness and weight. With such a thickness, size processing by punching or the like can be easily performed.
[0072]
The light emitting means provided on the optical film has an inclination angle of 35 to 48 degrees with respect to the plane formed by the polymer film 5 or the film 8 and a surface roughness Ra as shown in the examples of FIGS. A plurality of concave portions 51 and 81 each having an optical path changing slope of 5 to 500 nm and an elevation surface of 50 to 90 degrees and having a triangular cross-sectional shape and a rectangular opening on the polymer film surface or film surface are on one side. In addition, it is formed as a discontinuous distribution.
[0073]
The concave portion having a triangular cross section is advantageous in terms of reduction in visibility due to size reduction and manufacturing efficiency. A recessed part means that it is recessed in the polymer film or the optical film (groove). Moreover, a cross section means the cross section with respect to the optical path conversion inclined surface in a recessed part. Note that the triangle based on the cross section is not strictly defined as described above, and a change in the angle of the surface, roundness at the corner formed by the intersection of the surfaces, or the like is allowed.
[0074]
As described above, the incident light from the side surface by the light source arranged on the side surface or the like of the liquid crystal cell or the transmitted light thereof is optically path-converted to the back surface side of the optical film having no light exit means through the optical path conversion inclined surface a. It is possible to emit light having excellent directivity in the normal direction with respect to the light source light with high utilization efficiency.
[0075]
If the inclination angle of the optical path conversion slope is less than 35 degrees, the angle of the display light emitted from the liquid crystal display panel exceeds 30 degrees, which is disadvantageous for visual recognition. On the other hand, if the inclination angle of the optical path conversion slope exceeds 48 degrees, light leakage is likely to occur from the slope without being totally reflected, and the light utilization efficiency is lowered. On the other hand, when the surface roughness Ra of the optical path conversion slope exceeds 500 nm, the specular reflectivity becomes poor and the directivity of the reflected light decreases.
[0076]
In the above case, instead of the reflection method by the light path changing slope, when the scattering reflection method by the light emitting means having a roughened surface is used, it is difficult to reflect in the vertical direction, and the liquid crystal display panel is inclined in a direction inclined more than the front direction. As a result, the liquid crystal display becomes dark and the contrast becomes poor.
[0077]
Efficiently totally reflects through the light path changing slope, emits with good directivity in the normal direction of the polymer film surface or film surface from the side without the light emitting means, and efficiently illuminates the liquid crystal cell to make it bright and easy to see From the viewpoint of achieving liquid crystal display, the preferred inclination angle θ1 of the optical path changing slope is 38 to 45 degrees, and in particular 40 to 43 degrees.
[0078]
As shown in the examples of FIGS. 5 and 6, the light emitting means is formed by dispersively distributing a plurality of discontinuous intermittent recesses. The recesses may be distributed in parallel as shown in the example of FIG. 5 based on the optical path changing slope, or may be distributed irregularly. Further, as in the example of FIG. 6, it may be in a distributed state in which pits (concentric circles) are arranged with respect to the virtual center.
[0079]
By the way, the distribution of the pit-like arrangement described above assumes a virtual center on the end face of the polymer film or outside thereof when irradiating laser light, and projects in a direction perpendicular to the virtual radiation derived from the virtual center. It can be formed by moving the mask or / and the polymer film. In addition, assuming two or more virtual centers, the light emitting means may be composed of a plurality of concave portions distributed in a pit shape with respect to each virtual center.
[0080]
The arrangement state by the dispersion distribution of the plurality of recesses can be appropriately determined according to the form of the recesses. As described above, the light path conversion inclined surface a reflects the incident light from the side surface direction by the light source in the illumination mode and changes the light path, so that the concave portion having the light path conversion inclined surface transmits the entire light. It is possible to disperse and distribute discontinuously on one side of the optical film so that the rate is 75 to 92% and the haze is 4 to 20%. It is preferable from the viewpoint of obtaining a surface light source that efficiently illuminates and achieving a bright and excellent liquid crystal display.
[0081]
Such characteristics of total light transmittance and haze can be achieved by controlling the size and distribution density of the recesses. For example, the occupied area based on the projected area of the light emitting means on the surface of the optical film on which the light emitting means is formed is 1 / 100 to 1/8, especially 1/50 to 1/10, especially 1/30 to 1/15.
[0082]
More specifically, if the size of the concave portion or the optical path changing slope is large, the presence of the slope is easily recognized by the observer, and the display quality is easily lowered, and the uniformity of illumination for the liquid crystal cell is also lowered. Considering the fact that the opening on the polymer film surface is a rectangular concave portion, the long side length of the opening is not less than three times the short side length, in particular, not less than 5, particularly not less than 8. It is preferable.
[0083]
Further, it is preferable that the length of the optical path changing slope is 5 times or more, especially 8 or more, especially 10 or more of the depth of the recess. Further, it is preferable that the length of the optical path changing slope is 500 μm or less, especially 200 μm or less, especially 10 to 150 μm, and the depth and width of the recess is 2 μm to 100 μm, especially 5 to 80 μm, especially 10 to 50 μm. The length is based on the length of the optical path conversion slope in the long side direction, and the depth is based on the light emitting means forming surface of the optical film. The width is based on the length in the direction orthogonal to the long side direction and the depth direction of the optical path conversion slope.
[0084]
Note that the surface that forms the recess and does not satisfy the optical path conversion inclined surface a having a predetermined inclination angle, that is, the vertical surface b that faces the optical path conversion inclined surface a contributes to emitting incident light from the cell side surface from the back surface. It is preferable that the display quality, light transmission, and light emission are not affected as much as possible. By the way, if the angle of inclination θ2 of the vertical surface is small, the projected area on the film surface increases, and in the external light mode with the front light system in which the optical film is placed on the viewing side, the surface reflected light from the vertical surface returns to the viewing direction and is displayed It becomes easy to disturb the quality.
[0085]
Therefore, the larger the inclination angle θ2 of the vertical surface is, the more advantageous it is, so that the projected area on the film surface can be reduced and the decrease in the total light transmittance can be suppressed, and the apex angle due to the optical path conversion inclined surface and the vertical surface can also be reduced. The surface reflected light can be reduced, and the reflected light can be tilted in the film surface direction, thereby suppressing the influence on the liquid crystal display. From this point, the preferred inclination angle θ2 of the elevation is 60 degrees or more, especially 70 degrees or more, particularly 75 to 90 degrees.
[0086]
The slope forming the recess 51 (81) may be formed in an appropriate surface form such as a straight surface, a refractive surface, or a curved surface. Further, the cross-sectional shape of the recess may be a shape whose inclination angle is constant over the entire surface of the sheet, or uniform emission of light on the optical film in response to absorption loss and attenuation of transmitted light due to the previous optical path conversion. For the purpose of reducing the size, the concave portion may be enlarged as the distance from the side surface on the light incident side increases.
[0087]
In addition, the light emitting means can be a light emitting means in which the concave portions are distributed and distributed at a constant pitch. You can also Furthermore, it is possible to make the light emission uniform on the optical film 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.
[0088]
It is preferable from the viewpoint of improving the emission efficiency that the light path changing inclined surface in the recess faces the direction of the incident light from the side surface direction of the liquid crystal cell. Therefore, it is preferable that the optical path changing slope in the case of using a linear light source is directed in a certain direction. Moreover, it is preferable that the optical path changing slope in the case where a point light source such as a light emitting diode is used is directed toward the light emission center of the point light source.
[0089]
The shape of the intermittent end of the recess is not particularly limited, but it is preferable that it is dug at an acute angle from the viewpoint of suppressing the influence by reducing the incident light to that portion. The angle is preferably 60 to 90 degrees according to the surface.
[0090]
The optical film has a flat surface that is as smooth as possible on the front and back surfaces, except for the concave portions that form the light emitting means, and is an angle change of ± 2 degrees or less, particularly a flat surface of 0 degrees. It is preferable. 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, light transmitted through the liquid crystal cell can be used efficiently, and the image is not disturbed uniformly. Light emission can be achieved.
[0091]
As described above, the pit-like arrangement of the recesses is such that the point light source is arranged on the side surface of the liquid crystal display panel, and the radial incident light from the side direction by the point light source or the transmitted light passes through the optical path changing slope a. The purpose is to cause the optical film to emit light as uniformly as possible, and to emit light having excellent directivity in the normal direction with respect to the liquid crystal cell or the like from the optical film with high utilization efficiency of light source light.
[0092]
Therefore, the pit-like arrangement of the recesses is preferably performed so that a virtual center is formed on the end face of the optical film or on the outside thereof so that the arrangement of the point light source is facilitated. The virtual center can be formed at one place or two or more places on the same or different optical film end faces.
[0093]
In the above, in the case of using a transparent film for support when forming a molded cured layer of radiation curable resin, the optical film can be obtained as a transparent film and the molded cured layer fixed and integrated, It can also be obtained as comprising the molded and hardened layer in a state separated from the transparent film. Separation of the transparent film and the molded and hardened layer can be achieved by an appropriate method such as a method of surface-treating the transparent film with a release agent.
[0094]
The radiation curable resin for forming the molded cured layer is, for example, one type of suitable resin that can be cured by irradiation with ultraviolet rays such as the above-described ultraviolet curable resin, especially ultraviolet rays or / and electron beams. Or 2 or more types can be used and there is no limitation in particular about the kind. In particular, a radiation curable resin capable of forming a molded cured layer having excellent light transmittance is preferable.
[0095]
Further, in the case of the above-described fixing and integration, if the refractive index difference between the molded and hardened layer and the transparent film is large, the light emission efficiency may be greatly reduced due to interface reflection or the like. From the viewpoint of preventing this, a radiation curable resin capable of forming a molded and cured layer having a refractive index difference as small as possible with a transparent film, preferably within 0.10, particularly within 0.05 is preferable.
[0096]
Further, in the above case, it is preferable from the viewpoint of the emission efficiency that the refractive index of the molded and hardened layer to be added is higher than that of the transparent film. The thickness of the radiation curable resin coating layer formed on the transparent film is 1 to 5 times the height of the convex portion in the mold, 1.1 to 3 times, especially 1.2 to 2 times. Although preferable, it is not limited to this.
[0097]
The optical film according to the present invention changes its optical path through the light emitting means (optical path changing slope) in a direction (normal direction) excellent in perpendicularity that is advantageous for visual recognition of incident light from the side surface by the light source or its transmitted light. In addition, it can emit light efficiently, and can also exhibit good transparency to external light. For example, it is a bright and easy-to-see thin and light reflective and transmissive external light / illuminator. Various devices such as a liquid crystal display device can be formed.
[0098]
The liquid crystal display device can be formed by, for example, a method in which the optical film is disposed on at least one side of the liquid crystal cell so that the side having the light emitting means is on the outside. In that case, the illumination mechanism is formed by arranging one or two or more light sources on one or more side surfaces of the liquid crystal cell, particularly one or more side surfaces of the cell substrate on the side where the optical film is arranged. can do. Further, it is preferable that the optical film is bonded to a liquid crystal cell or the like through an adhesive layer from the viewpoint of achieving bright display.
[0099]
In the case of an optical film having a light emitting means with a pit arrangement in the formation of the illumination mechanism, the light with the pit arrangement is used in order to achieve a bright display by efficiently using the radial incident light from the point light source. It is preferable to arrange a point light source on the side surface of the liquid crystal cell on the vertical line including the virtual center of the emitting means. In such arrangement of the point light source corresponding to the virtual center, the side of the cell substrate where the point light source is arranged is protruded depending on whether the virtual center of the light emitting means is at the end face of the optical film or outside thereof. Appropriate countermeasures such as methods can be taken.
[0100]
As the light source disposed on the side surface of the liquid crystal cell, an appropriate light source can be used. For example, in addition to the above-described point light sources such as light-emitting diodes, linear light sources such as (cold, hot) cathode tubes, array bodies in which point light sources are arranged in a line or surface, or point light sources and linear light sources. A combination of light plates and converting incident light from a point light source into a linear light source via a linear light guide plate can be preferably used.
[0101]
Moreover, it is preferable from the point of radiation | emission efficiency to arrange | position a light source on the cell side surface from which the optical path conversion slope of an optical film will face. Incident light from the side surface through the light source can be efficiently converted into a surface light source by arranging the light path conversion slope so as to face the light source as perpendicularly as possible, including the case of the pit arrangement described above. Can emit light with high efficiency. In the case of the pit arrangement, the point light sources can be arranged at one place or two places or more corresponding to the virtual center of the light emitting means in the optical film.
[0102]
The light source enables visual recognition in the illumination mode by lighting, and it is not necessary to turn on when viewing in the external light mode by external light in the case of an external light / illumination type liquid crystal display device. It can be switched on and off. As the switching method, any method can be adopted, and any of the conventional methods can be adopted. The light source may be of a different color light emission type capable of switching the emission color, or may be capable of emitting different color light via different light sources.
[0103]
If necessary, the light source may be a combined body in which appropriate auxiliary means such as a reflector surrounding the diverging light is guided to guide the side surface of the liquid crystal cell. As the reflector, an appropriate reflective sheet such as a resin sheet provided with a highly reflective metal thin film, a white sheet, or a metal foil can be used. The reflector can also be used as a fixing means that also serves as an enclosure for the light source, such as by bonding its end to the end of a cell substrate or the like.
[0104]
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, and optionally assembling components such as a reflective layer and a compensation retardation plate. It is formed. In this invention, there is no limitation in particular except the point which forms an illumination mechanism using the above-mentioned optical film and light source, It can form according to the thing of the conventional front light type and a backlight type.
[0105]
Accordingly, the liquid crystal cell to be used is not particularly limited, and an appropriate reflection type or transmission type in which liquid crystal is sealed between cell substrates via a sealing material and display light is obtained through light control using the liquid crystal or the like. Things can be used.
[0106]
Incidentally, specific examples of the liquid crystal cell described above include TN type liquid crystal cell, STN type liquid crystal cell, IPS type liquid crystal cell, HAN type liquid crystal cell, OCB type liquid crystal cell and VA type liquid crystal cell, twist type, non-twist type, guest. Examples of the liquid crystal cell include a host system and a ferroelectric liquid crystal system, and a light diffusion type liquid crystal cell such as an internal diffusion type. Also, the liquid crystal driving method may be an appropriate one such as an active matrix method or a passive matrix method.
[0107]
In the front light type reflection type liquid crystal display device, the arrangement of the reflection layer is essential, but the arrangement position can be provided inside the liquid crystal cell also as an electrode, or provided outside the liquid crystal cell. You can also.
[0108]
For the reflective layer, for example, a coating layer containing a high-reflectance metal powder such as aluminum, silver, gold, copper, or chromium in a binder resin, an attachment layer of a metal thin film by a vapor deposition method, the coating layer, It can be formed as an appropriate reflective layer according to the prior art, such as a reflective sheet, a metal foil, a transparent conductive film, or a dielectric multilayer film, in which the attachment layer is supported by a base material. When the transmissive liquid crystal display device is of the external light / illumination type, the reflective layer disposed on the outer side of the optical film can also be appropriate according to the above.
[0109]
On the other hand, a transmissive liquid crystal display device can be formed by disposing an optical film as a component of a backlight on the viewing back side of a liquid crystal cell. In that case, by providing a reflective layer on the back side (outside) of the light emitting means, the light leaking from the light path changing slope etc. is reflected and returned to the direction of the liquid crystal cell, so that it can be used for cell illumination and the luminance is improved. be able to.
[0110]
In the above case, by making the reflection 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. Further, by providing the reflective layer, it can be used as a liquid crystal display device that is a transmission type as described above and that is used for both external light and illumination.
[0111]
【Example】
Example 1
An opening made of an isosceles triangle with an apex angle of 84 degrees is provided in the metal foil to form a laser light transmitting portion, and a slit-like opening having the same length as the hypotenuse and a short side length of 5 μm is formed outside both hypotenuses. An isosceles triangle is formed on a projection mask (FIG. 3) in which two auxiliary laser beam transmitting portions are formed by irradiating an excimer laser beam having a wavelength of 248 nm with a beam width of 1.5 mm and the projection mask is fixed to the projection mask. The projection mask transmitted light is reduced to 1/15 through a lens having a focal depth of 4 μm and irradiated onto a polyimide film having a thickness of 50 μm to form a recess (FIG. 1). ).
[0112]
The concave portion has a triangular cross section, and the deepest etched portion corresponds to the base of an isosceles triangle that forms the laser light transmitting portion of the projection mask, and the beginning of the optical path changing slope (the etching amount is 0). Corresponds to the apex angle of the mask. The recess has a length of about 100 μm, a width of about 10 μm, a depth of about 8 μm, an optical path conversion slope having an inclination angle of about 42 degrees with respect to the film surface and a surface roughness Ra of 50 to 150 nm, and an inclination angle facing it. It had an elevation of about 75 degrees (FIG. 7A).
[0113]
Next, the above etching process is repeated while changing the position with respect to the polyimide film by scanning each axis of XYZθ of the work stage, and a plurality of the concave portions are randomly distributed on one side of the polyimide film, and the distribution density of the film is A polymer film (an optical film as a matrix) having a larger size as the distance from one side increases (FIG. 7A) was formed. In addition, the area which the opening of a recessed part occupies on the film surface was 1/10.
[0114]
Next, the surface of the polymer film with concave portions is filled with nickel by electroforming to form a metal layer having a thickness of about 200 μm, and then the polymer film is peeled off to have a predetermined convex portion forming surface. A mold was obtained (FIGS. 7B and C). Then, a radiation-curing acrylic resin is applied to the mold forming surface of the mold in a thickness of 75 μm, and a transparent film is applied thereon to extrude excess resin and air bubbles. After forming a molding layer that was copied, the radiation was irradiated to cure the molding layer, and the formed and cured layer was peeled from the mold to obtain an optical film having a light emitting means (FIG. 7D, E).
[0115]
The light emitting means in the optical film has an optical path changing slope with an inclination angle of about 42 degrees with respect to the film surface and a surface roughness Ra of 50 to 150 nm, and an elevation surface with an inclination angle of about 75 degrees facing it. It consists of a plurality of recesses having a length of about 100 μm, a width of about 10 μm, and a depth of about 8 μm, and this corresponds to the light emitting means consisting of the recesses provided in the matrix polyimide film with high accuracy. Moreover, the both ends of the recessed part were dug into an acute angle.
[0116]
Comparative example
A light guide plate in which light emitting means composed of stripe-shaped concave portions was formed by machining was used.
[0117]
Evaluation test
A liquid crystal display device incorporating the optical film according to the example or the light guide plate according to the comparative example was formed. As a result, generation of moire was confirmed in the comparative example. In addition, interface reflection occurs in the gap between the light guide plate and the panel, resulting in a decrease in contrast, and defects in the light guide plate are very noticeable when the light guide plate is viewed directly. Furthermore, since the conventional method is laser etching, the surface roughness Ra of the optical path conversion slope is large and the luminance and visibility are poor.
[0118]
In contrast to the above, in the embodiment, the light emitting means is made of a micro size and a concave portion with sharply digging at both ends, which is randomly and densely arranged, so that moire does not occur and adhesion processing to the panel via an adhesive layer is performed. No interfacial reflection occurred. In addition, the optical films of the examples are much thinner and lighter than the light guide plate of the comparative example, and the inclination angle and linearity of the light path changing slope in the concave portion forming the light emitting means, the surface roughness Ra. In comparison with the light guide plate of the comparative example, the resolution of the liquid crystal display device was high, and the luminance and visibility were excellent.
[0119]
From the above-described embodiment, it can be seen that a concave portion in which both ends are dug at an acute angle can be formed by laser beam scanning. It can also be seen that by using a projection mask in which a triangular laser beam transmitting portion and an auxiliary laser beam transmitting portion are used, a concave portion having a triangular cross section with a small surface roughness Ra of the optical path changing slope can be formed. In that case, the inclination angle of the optical path changing slope with respect to the film surface can be controlled by the apex angle of the triangle forming the laser beam transmitting portion. Further, it can be seen that the dispersion distribution state such as irregular arrangement of the concave portions can be easily controlled.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a manufacturing method
FIG. 2 is an explanatory diagram of another manufacturing method.
FIG. 3 is an explanatory diagram of a projection mask.
FIG. 4 is an explanatory diagram of another projection mask.
FIG. 5 is an explanatory perspective view of an optical film.
FIG. 6 is an explanatory plan view of another optical film.
FIG. 7 is an explanatory diagram of still another manufacturing method.
[Explanation of symbols]
1: Laser oscillator
2: Projection mask
21 and 22: Laser beam transmission part
21a to d, 22a to d: auxiliary laser light transmission part
3: Spare mask
31: Laser light transmission part
4: Optical equipment
41, 42: Projected image
5: Polymer film (optical film)
51: Recess
a: Optical path conversion slope b: Elevation
7: Mold
8: Optical film
81: Recess
a: Optical path conversion slope b: Elevation

Claims (7)

The polymer is irradiated with laser light through a projection mask, the size of the laser light transmitted through the projection mask is controlled through an optical device that creates a projected image, and the irradiation amount of the laser light is changed. While irradiating the film, by moving at least one of the projection mask or the polymer film and partially removing the polymer film forming material by laser etching, an inclination angle with respect to the polymer film plane Is provided with an optical path conversion slope of 35 to 48 degrees and an elevation of 50 to 90 degrees, the cross-sectional shape is a triangle, and the openings on the polymer film surface are rectangular. The light emitting means is formed on one surface of the light source and is distributed discontinuously. The projection mask continuously changes the integral value of the amount of laser light transmission in the short side direction of the concave portion to be formed. , Recessed formed A laser beam transmitting portion that continuously changes the etching amount per unit area in the depth direction, and an auxiliary laser that controls the surface roughness Ra of the optical path changing slope formed through the laser beam transmitting portion to 5 to 500 nm An optical film manufacturing method comprising one or two or more masks forming a light transmitting portion. In Claim 1, it has 1 or 2 or more preliminary | backup masks which form the laser beam transmission part which shields unnecessary transmitted light, shape | molds laser beam in a rectangular shape, and supplies with respect to a projection mask, and An optical film in which the length in the long side direction of the projected image on the polymer film surface via the optical device in the rectangular laser beam by the preliminary mask is equal to or longer than the length in the long side direction of the concave portion to be formed Manufacturing method. 3. The laser light transmitting portion in the projection mask according to claim 1 or 2, wherein the laser light transmitting portion is a triangle or a rectangle, and the slit-shaped auxiliary laser light transmission is performed with respect to the side intersecting the moving direction of the projection mask or the polymer film in the laser light transmitting portion The manufacturing method of the optical film formed by arrange | positioning a part. The method for producing an optical film according to claim 1, wherein the etching process is performed with an ultraviolet laser beam having a wavelength of 400 nm or less. A metal layer is formed by electroforming on the surface on which the light emitting means of the optical film according to claim 1 is formed, and then the metal layer and the optical film are separated to obtain a mold. A method for producing a mold for forming an optical film. A radiation-curable resin is brought into close contact with a surface having a convex portion capable of forming a light emitting means in the optical film forming mold according to claim 5 to form a molding layer that reflects the shape of the light emitting means. A method for producing an optical film, wherein the molding layer is irradiated with radiation and cured, and then separated from a mold. A liquid crystal display device comprising an optical film produced by the manufacturing method according to claim 1 or 4 on at least one side of a liquid crystal cell.

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