JP5509566B2 - Optical component and liquid crystal display unit - Google Patents

Description

  The present invention relates to a method for manufacturing an optical component, a microlens array and a prism array manufactured by this method, an optical sheet for backlight using the same, an optical component such as a projection screen, or an optical sheet having an optical waveguide and a light guide And a liquid crystal display unit including such an optical component.

  A display typified by a liquid crystal display device (LCD) incorporates a light source (backlight) necessary for recognizing provided information. The power consumed by this light source occupies a considerable portion of the power consumed by the entire apparatus. For this reason, it is essential to improve the efficiency of the light source in these days when reduction of the total power is strongly demanded.

  For improving the efficiency, there are a method of increasing the light emission conversion efficiency itself, adjusting the light according to the brightness of the surroundings, and a method of increasing the utilization efficiency of the emitted light.

  As a means for increasing the utilization efficiency of light, an optical film including a brightness enhancement film (BEF, a registered trademark of 3M USA) is widely used between a light source or a light guide plate and a liquid crystal panel. BEF has a repetitive array structure of prisms.

  If the repetitive array structure of the BEF prisms is arranged in one direction, only redirection or recycling of the light beam in that arrangement direction is possible. Therefore, in order to control the luminance of the display light in the horizontal and vertical directions, two sheets are overlapped and combined so that the arrangement directions of the prism groups are orthogonal to each other. The adoption of BEF allows display designers to achieve the desired on-axis brightness while reducing power consumption.

  Many patent documents disclose that a brightness control member having a repetitive array structure of prisms represented by BEF is used in a display (see, for example, Patent Documents 1 to 3).

  An optical film having a repetitive array structure of unit lenses (also called a lenticular lens) instead of a prism has been proposed (see, for example, Patent Document 4). The surface of the optical film on the liquid crystal panel side has an array structure in which a plurality of unit lenses are repeatedly formed so as to guide light emitted from a light source and traveling through the optical film to the liquid crystal panel.

  The other surface of the optical film is provided with a reflective layer patterned in a stripe shape so that the vicinity of the focal plane of the lens is an opening. When the unit lens is a semi-cylindrical convex cylindrical lens, the white reflective layer is formed in a stripe shape by printing or transferring so that an opening is formed corresponding to each unit lens 1: 1. .

  When this optical film is incorporated into a backlight unit of a liquid crystal display, only the light emitted from the diffusion film that has passed through the opening between the reflective layers is incident on the lens and is condensed in a certain direction by the lens. Emitted. Furthermore, the light emitted from the optical film enters the polarizing plate, and only the light having a predetermined polarization component is guided to the liquid crystal panel.

  On the other hand, the light that has not passed through the opening is reflected by the reflection layer, returned to the diffusion film side, and guided to the reflection plate. Then, the light is incident on the diffusion film again by being reflected by the reflecting plate, and after being diffused again on the diffusion film, the incident light is incident on the lens through the opening after the incident angle is reduced. Is squeezed within a predetermined angle and emitted from the optical film.

  In the backlight unit using such an optical film, by adjusting the size and position of the opening between the reflective layers, the ratio of light emitted from the lens in the front direction is increased while increasing the light utilization efficiency. Can be controlled.

  In a large display, a direct backlight unit must be adopted from the viewpoint of its size and total light quantity. In this case, it is necessary for the brightness enhancement film used for improving the light utilization efficiency and the brightness of the display to provide a space in the optical path by separating it or installing an air layer.

  When the brightness enhancement film is integrated, light absorption reflection occurs at the contact portion. However, in order to reduce the influence, if the contact area is reduced, sufficient adhesive strength cannot be obtained.

When the film is supplied as a separate film such as BEF, an increase in the number of parts and a problem in terms of cost arise.
Japanese Patent Publication No. 1-378001 JP-A-6-102506 Japanese National Patent Publication No. 10-506500 JP 2000-284268 A

  The conventional lens sheet used in combination with the diffuser plate of the backlight unit is difficult to obtain sufficient brightness, that is, front luminance, and is composed of a plurality of lens sheets including the diffuser plate used in the set. It is common. When adopting this multiple lens sheet configuration, it is necessary to hold the lens sheet so as not to bend, and in order to obtain sheet rigidity, the sheet is thickened or integrated with the diffusion plate. This is a factor that increases costs. Although it is desirable to reduce the number of lens sheets from the viewpoint of the holding mechanism that prevents bending, it is difficult to achieve compatibility with optical characteristics.

  In addition, when a striped structure such as a lenticular lens shape is provided, moire tends to occur due to the structure, and care must be taken when using it. In order to avoid the occurrence of moiré, there are a method of disturbing the regularity of the pattern by random arrangement and a method of making the structure itself sufficiently small (approximately 1/10) compared to the structure of the liquid crystal panel. Due to the above limitations, it is not always the best solution.

  An object of the present invention is to provide an optical component that has sufficient optical characteristics with a single sheet, has good productivity, and provides cost merit.

The invention according to claim 1 of the present invention has a plurality of convex portions in which convex portions having a circular bottom surface having a diameter D (μm) are arranged in a delta arrangement on the surface, and a period of arrangement of adjacent convex portions. Is random in a range of L ± L / 10 (μm) with the period L (μm) as a reference, and the distribution of the diameter D of the bottom surfaces of the plurality of convex portions is a normal distribution in a plane including the bottom surface. such to the diameter D is 40 to 100 [mu] m, the period L is an optical component, which is a 43 to 105 .mu.m.

The invention according to claim 2 of the present invention is a liquid crystal display unit including the optical component according to claim 1 .

  According to the present invention, it is possible to provide an optical component that has sufficient optical characteristics with a single sheet, has excellent productivity, and provides cost merit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view of an optical component according to an embodiment of the present invention. 2A to 2C are cross-sectional views of the optical component according to the embodiment of the present invention.

  As shown in FIG. 1, in the optical component of the present invention, a plurality of circular convex portions 11 are formed in a substantially delta arrangement. In FIG. 1, 10 indicates a regular arrangement position when the convex portions are arranged in a delta arrangement. The actually formed protrusions 11 are randomly arranged in a range of L ± L / 10 with a certain period L as a reference. Here, for example, when the optical component of the present invention is used in a liquid crystal display unit, the period L is set to the distance between display cells.

  As shown in FIG. 2A, the optical component is formed by applying a radiation curable resin, for example, a UV curable resin 22 on the base film 21, transferring the shape of the mold to the UV curable resin 22, and then UV curable. The resin 22 may be cured. As shown in FIG. 2B, the optical component may be one obtained by transferring the shape of a mold to a thermoplastic resin 23.

  By arranging the convex portions 11 in a substantially delta arrangement as described above, it becomes easy to maximize the area ratio of the circular convex portions 11, and the optical effects in the convex portions 11, such as light collection, diffusion, and scattering, are efficiently obtained. Can get well.

  Further, by arranging the protrusions by randomly setting the period of the arrangement of the adjacent protrusions at a range of L ± L / 10 with a certain period L (for example, the distance between display cells of the liquid crystal display) as a reference, Moire generated when used in proximity to a member having a lattice structure such as a liquid crystal panel is less likely to be generated, and even when moire occurs, it can be kept thin. By forming the plurality of convex portions in two or more types having different sizes or shapes, moire can be made more difficult to occur. In addition, when forming the some convex part from which a magnitude | size differs, it is preferable that the diameter distribution of a some convex part makes a substantially normal distribution.

  Furthermore, even when an optical component is manufactured using a relatively inexpensive processing device with insufficient processing accuracy, the convex portions 11 are aligned not only in the vertical and horizontal directions but also in the oblique direction. There is an advantage that it is difficult to detect even if a deviation occurs between the cell and the cell arrangement.

  Further, when the cross section of the optical component includes a curved portion and a straight portion, it is possible to achieve both the optical characteristics obtained by controlling the refraction or reflection direction of the light beam and the processing accuracy. This is because it is generally difficult to obtain a desired curved surface shape (spherical surface or aspherical surface) by etching, and a method of using a combination of etching shapes obtained under certain conditions is desirable from the economical viewpoint. In that case, in order to obtain desired optical characteristics, it is possible to achieve both optical characteristics and processing accuracy (productivity) by adjusting the shape and characteristics of the straight portion that can be easily processed.

  Furthermore, if a protrusion is formed on the top of the protrusion 11 and an inflection point is provided on the slope of the protrusion 11, the optical characteristics can be adjusted by adjusting the shape of the protrusion.

  When the optical component of the present invention is used in, for example, a liquid crystal display unit, desired optical characteristics can be obtained with a minimum number of optical components, and the number of components can be reduced. Therefore, an inexpensive liquid crystal display unit with a low failure rate can be provided.

  With reference to FIG. 3 (a)-(d), the method to produce the shaping | molding die used for manufacture of the optical component which concerns on embodiment of this invention is demonstrated.

  As shown in FIG. 3A, an etching resistant layer 32 is formed on the base material 31 by a method such as coating or transfer.

  As the base material 31, it is preferable to use a metal layer formed on an appropriate base material. As the base material, iron, SUS, aluminum or the like is used in consideration of durability and handling. The material of the base material 31 is not particularly limited as long as the shape can be transferred to an optical material made of a resin or the like. However, since a certain level of smoothness is required for use in optical applications, copper or copper formed by plating may be used. It is common to use brass.

  The shapes of the base material and the base material 31 are not particularly limited, and may be, for example, cylindrical or flat. If the base material has a cylindrical shape and a continuous pattern without a seam is formed, a film-like optical component can be continuously formed. A film-like optical component has a high productivity because it can cope with many screen sizes by simply adjusting the cut-out dimension. If the shape of the base material is a flat plate, a sheet or a sheet can be easily formed by a press or the like, which is suitable for small lot multi-product production.

  The etching resistant layer 32 is desirably formed with a uniform thickness on the substrate 31 using a coating method. As the coating method, a spray method, a transfer method, dip coating, or the like is preferable from the viewpoint of cost effectiveness.

  The etching resistant layer 32 contains a substance that is strong against corrosion by the etching solution and absorbs a laser beam having a predetermined wavelength to be irradiated. As a light-absorbing substance, carbon black that exhibits absorption in almost all wavelength regions is particularly preferable because it is cost-effective.

  As shown in FIG. 3B, the etching resistant layer 32 is irradiated with a laser beam L, and an opening is formed in the etching resistant layer 32 by ablation occurring in the laser beam irradiated portion. The etching resistant layer 32 absorbs energy by laser beam irradiation to remove the vicinity of the irradiated portion (ablation), and as a result, an opening is formed. The openings are also formed in a delta arrangement so as to correspond to the delta arrangement of the convex portions of the optical component to be manufactured. Further, the arrangement period of the adjacent openings is adjusted to be random within a range of L ± L / 10 with a certain period L as a reference.

  As shown in FIG. 3C, the base material 31 is etched through the opening formed in the etching resistant layer 32 to form a recess in the base material 31.

  As the etching solution, one that can satisfactorily etch the base material 31 and does not etch the base material is used. For example, when a copper plating layer is used as the base material 31, a second iron chloride solution is used as an etching solution. In this case, a better smooth surface can be obtained by adding sulfuric acid or hydrochloric acid to the etching solution.

  To adjust the cross-sectional shape of the recess, the corrosion rate during etching is controlled. In normal etching, the base material 31 is continuously corroded, so that the cross-sectional shape of the recesses also changes continuously. However, by controlling the flow of the etching solution by spraying the etching solution, the cross-sectional shape of the concave portion having the curved portion and the straight portion can be obtained.

  Further, after the first etching is performed to form a recess in the base material 31, an etching resistant layer is formed again, and an opening is formed so as to correspond to the bottom of the recess by irradiating a laser beam. Etching may be performed to form a recess in the bottom of the recess.

  As shown in FIG. 3D, after etching, the mold 41 having the recesses 33 can be obtained by removing the etching-resistant layer 32 with a solvent or the like.

  As shown in FIG. 4, the recess 33 formed in the mold 41 has a diameter D and a depth h. These dimensions correspond to the dimensions of the convex portions of the optical component to be manufactured.

  In addition, after etching the base material 31 and forming the recessed part 33, Cr plating and Ni plating may be given to the surface of the base material 31 in consideration of abrasion resistance.

  Next, a method for manufacturing an optical component having a convex portion by transferring the shape of a mold to an optical material will be described. As the optical material, a radiation curable resin such as a UV curable resin or a thermoplastic resin can be used. As thermoplastic resins, polycarbonate resins, acrylic resins, fluorine acrylic resins, silicone acrylic resins, epoxy acrylate resins, polystyrene resins, cycloolefin polymers, methylstyrene resins, fluorene resins, polyester resins (polyethylene terephthalate: PET, etc.) , Polypropylene, acrylonitrile styrene copolymer, acrylonitrile polystyrene copolymer, and the like.

  For example, as shown in FIG. 5A, an example in which an optical component is manufactured using a mold 41 formed on the surface of a printing cylinder 40 will be described. As shown in FIG. 5B in which the portion B in FIG. 5A is enlarged, the recesses 33 are formed in the mold 41 so as to form a delta arrangement.

  FIG. 6 shows an example of an apparatus for producing a film-like optical component. The base film 21 is supplied from the supply roll 51, is wound around the plurality of rollers, the mold 41 on the surface of the printing cylinder 40, and the plurality of rollers, and is wound around the winding roll 52. An uncured UV curable resin 22 is applied on the base film 21 before the mold 41, the mold 41 is pressure-bonded to the UV curable resin 22 to transfer the shape of the mold 41, and then the UV curable resin 22 is applied. The UV lamp 53 is irradiated with UV light and cured. The cured UV curable resin is transparent.

  Thus, as shown in FIG. 1 and FIG. 2A, a film-like optical device in which a plurality of circular convex portions 11 are formed in a substantially delta arrangement on the UV curable resin 22 on the base film 21. Parts can be obtained.

  FIG. 7 shows another example of an apparatus for manufacturing a film-like optical component. The thermoplastic resin 23 is extruded between the mold 41 on the surface of the printing cylinder 40 and the opposing roll 61, and is embossed by the mold 41 to form a film-like optical component. The film-like optical component is stretched around a plurality of rollers and wound on a winding roll 62.

  Thus, as shown in FIG. 1 and FIG. 2B, a film-like optical component in which a plurality of circular convex portions 11 are formed in a substantially delta arrangement on the thermoplastic resin 23 can be obtained. .

  In addition, as described above, by using a mold in which a recess is formed at the bottom of the recess by performing etching twice, a protrusion is formed on the top of the protrusion 11 and changed to an inclined portion of the protrusion 11. An optical component having a bend can also be obtained.

  The shape of the convex portion 11 can be arbitrarily adjusted according to the use of the optical component, and optical characteristics that can be applied to a wide range of products can be realized.

  By using the method of the present invention, it is possible to easily produce a mold for molding which has been difficult to obtain by utilizing existing techniques such as etching. can get.

Example 1
An example in which an optical component in which convex portions having a diameter of 100 μm are formed in a substantially delta arrangement will be described. In this embodiment, the arrangement period L is 105 μm, that is, the convex portions are randomly shifted in a range of ± 2.5 μm with respect to the original regular arrangement positions with reference to a delta arrangement with an interval of 5 μm. Is formed.

  A SUS printing cylinder having a circumference of 600 mm and an effective surface length of 1100 mm was plated with copper and used as a substrate. A black ink containing a carbon black pigment was prepared as a material for the etching resistant layer. While rotating the printing cylinder at about 1000 rpm, black ink was sprayed and applied to a thickness of about 20 μm to form an etching resistant layer.

  Patterning was performed using a laser engraving machine. The wavelength of the laser beam is 1060 nm and the output is about 100 W. A laser beam was condensed and irradiated on the etching resistant layer to a beam diameter of about 5 μm, and ablation was caused by scanning at a pitch of 2 μm to form circular openings with a diameter of 50 μm in a substantially delta arrangement.

  Through the opening formed in the etching-resistant layer, the copper plating on the printing cylinder was etched using a second iron chloride solution as an etching solution to form a recess having a diameter of 100 μm on the surface of the copper plating. The remaining etching resistant layer was removed with a solvent.

  In the same manner as described above, an etching resistant layer was again applied to the printing cylinder on the copper plating. In the same manner as described above, a circular opening having a diameter of 15 μm was formed in the etching resistant layer so as to correspond to the bottom of the recess having a diameter of 100 μm. Through the opening formed in the etching resistant layer, the copper plating on the printing cylinder was etched using a second iron chloride solution to form a recess at the bottom of the recess having a diameter of 100 μm. The etching resistant layer was removed after the second etching.

  The printing cylinder was degreased with caustic soda, neutralized with hydrochloric acid, washed with water, and the like, and the copper plating surface was chrome plated to obtain a desired mold.

  An optical component was manufactured using the manufacturing apparatus of FIG. A PET film having a thickness of 188 μm is supplied from a supply roll 51, and is wound around a plurality of rollers, a mold (printing cylinder), and a plurality of rollers, and wound around a winding roll 52. In the middle of the process, a UV curable resin is applied onto the PET film, the mold is pressure-bonded to the UV curable resin to transfer the shape of the mold, and then the UV lamp (high pressure mercury lamp) 53 to 1. It is cured by irradiating with UV light at an output of 5 kW. The cured UV curable resin is transparent. The molding speed was 2.0 m / min. In the UV curable resin on the obtained PET film, convex portions having a diameter of 100 μm are formed in a delta arrangement, a projecting portion is formed on the top of the convex portion, and an inflection point is present on the inclined portion of the convex portion. Thereafter, the film is cut into a desired size and shape to produce an optical component.

  According to this embodiment, a film-like optical component can be continuously produced by roll forming.

(Example 2)
An example in which an optical component in which convex portions having a diameter of 40 μm are formed in a substantially delta arrangement will be described. In this embodiment, the arrangement period L is 43 μm, that is, the protrusions are randomly shifted in a range of ± 3.0 μm from the original regular arrangement position with reference to a delta arrangement with an interval of 3 μm. Is formed.

  A SUS printing cylinder having a circumference of 780 mm and an effective surface length of 800 mm was plated with copper and used as a substrate. A black ink containing a carbon black pigment was prepared as a material for the etching resistant layer. While rotating the printing cylinder at about 1000 rpm, black ink was sprayed and applied to a thickness of about 20 μm to form an etching resistant layer.

  Patterning was performed using a laser engraving machine. The wavelength of the laser beam is 1060 nm and the output is about 100 W. The etching resistant layer was focused and irradiated with a laser beam with a beam diameter of about 5 μm, and ablation was caused by scanning at a pitch of 1 μm to form circular openings with a diameter of 20 μm in a substantially delta arrangement.

  Through the opening formed in the etching resistant layer, the copper plating on the printing cylinder was etched using a second iron chloride solution as an etching solution to form a recess having a diameter of 40 μm on the surface of the copper plating. The remaining etching resistant layer was removed with a solvent.

  The printing cylinder was degreased with caustic soda, neutralized with hydrochloric acid, washed with water, and the like, and the copper plating surface was chrome plated to obtain a desired mold.

  The shape of the mold was transferred to a UV curable resin on a 75 μm-thick PET film using the manufacturing apparatus of FIG. 6 to form convex portions having a diameter of 40 μm in a delta arrangement. Thereafter, the film was cut into a desired size and shape to produce an optical component.

  The visual unevenness of the obtained film-like optical component was reduced as compared with an optical component that requires the convex portions to be randomly arranged. The obtained film-like optical component was placed in a liquid crystal TV. As a result, it was confirmed that the brightness was improved by the light collimation on the front of the screen and the light distribution angle distribution was improved. In addition, the film-like optical components were arranged in any direction on the 32-inch, 37-inch, and 46-inch liquid crystal TVs (Sharp AQUAS series).

(Example 3)
An example in which an optical component in which convex portions having a diameter of 40 μm are formed in a substantially delta arrangement will be described. In this embodiment, the arrangement period L is set to 55 μm, and the convex portion is set to have a diameter of about ± 10 μm centered on 40 μm. That is, when the convex portion has a diameter of 50 μm, the convex portion is formed by randomly shifting the position within a range of ± 2.5 μm with respect to the original regular arrangement position on the basis of the delta arrangement with an interval of 5 μm.

  A SUS printing cylinder having a circumference of 800 mm and an effective surface length of 300 mm was subjected to copper plating, and further peelable ballad copper plating was applied, which was used as a substrate. A black ink containing a carbon black pigment was prepared as a material for the etching resistant layer. While rotating the printing cylinder at about 1000 rpm, black ink was sprayed and applied to a thickness of about 20 μm to form an etching resistant layer.

  Patterning was performed using a laser engraving machine. The wavelength of the laser beam is 530 nm, and the output is about 1 kW. The etching-resistant layer was focused and irradiated with a laser beam with a beam diameter of about 5 μm, and ablation was caused by scanning at a pitch of 1 μm to form circular openings with a diameter of 20 μm in a delta arrangement.

  Through the opening formed in the etching resistant layer, the ballad copper plating on the printing cylinder was etched using a second ferric chloride solution as an etching solution to form a recess having a diameter of 40 μm in the ballad copper plating. The remaining etching resistant layer was removed with a solvent.

  The printing cylinder was degreased with caustic soda, neutralized with hydrochloric acid, washed with water, etc., and the copper plating surface was chrome plated. The ballad copper plating layer (and the chromium plating layer thereon) was peeled off from the printing cylinder. This plating layer was bonded to an aluminum plate having a thickness of 3 mm with an adhesive tape to obtain a flat mold.

A UV curable resin is applied on the obtained flat mold, a transparent MS plate having a thickness of 2 mm is adhered by a laminator, and a curing process is performed with an integrated light quantity of 1000 mJ / cm ² by an exposure device on a conveyor. An optical component was obtained.

  The obtained optical component had a natural matte feeling without feeling the regularity of the pattern. When the obtained optical component was put into a liquid crystal TV, optical characteristics equivalent to those of the film could be obtained without causing moire. In addition, since the optical component of the present example is thick, wrinkles and sagging did not occur even when heated for a long time, and a very stable screen could be maintained.

The top view of the optical component which concerns on embodiment of this invention. Sectional drawing of the optical component which concerns on embodiment of this invention. Sectional drawing which shows the production method of the type | mold for shaping | molding which concerns on embodiment of this invention. Sectional drawing which shows the recessed part formed in the type | mold for shaping | molding which concerns on embodiment of this invention. The perspective view which shows the type | mold of the cylinder surface which concerns on embodiment of this invention, and the top view which shows the recessed part formed in the type | mold. The block diagram which shows an example of the manufacturing apparatus of the optical component which concerns on embodiment of this invention. The block diagram which shows the other example of the manufacturing apparatus of the optical component which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Convex part, 12 ... Protrusion part, 21 ... Base film, 22 ... UV curable resin, 23 ... Thermoplastic resin, 31 ... Base material, 32 ... Etching-resistant layer, 33 ... Concave part, 40 ... Printing cylinder, 41 ... Mold, 51 ... Supply roll, 52 ... Winding roll, 53 ... UV lamp, 61 ... Counter roll, 62 ... Winding roll.

Claims (2)

A convex portion having a circular bottom surface with a diameter D (μm) on the surface has a plurality of convex portions arranged in a delta arrangement, and the period of arrangement of adjacent convex portions is L with reference to the cycle L (μm). ± L / 10 have become random in the range of ([mu] m), to the distribution of the diameter D of the bottom surface of the plurality of protrusions name a normal distribution in a plane including said bottom surface,
The diameter D is 40 to 100 μm, and the period L is 43 to 105 μm .   A liquid crystal display unit comprising the optical component according to claim 1.

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