JP2008170871A - Optical sheet, backlight unit using the same, display device and method for manufacturing the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet, a backlight unit using the sheet, a display device and a method for manufacturing the device for reducing irregular luminance in transmitted light. <P>SOLUTION: The optical sheet 21 comprises: a lens sheet 4 having lens portions 4b arranged in an array; a light-reflecting layer 5 having a light-shielding pattern regulating incident ranges of light, corresponding to the respective lens portions 4b; a light-scattering layer 7 for scattering the light incident to the lens sheet 4 from the light reflecting layer 5, in the front side of the light reflecting layer 5; and a light-transmitting jointing layer 6 for fixing the light scattering layer 7 to the light reflecting layer 5. The light-reflecting layer 5 comprises a transparent portion 5B for forming a light-transmitting portion of the light-shielding pattern made of a compression resistant medium having a refractive index lower than the refractive index of the lens sheet 4, and a light-reflecting portion 5A forming the light-shielding portion of the light shielding pattern. The transparent portion 5B is made to adhere tightly to the jointing layer 6 and the lens sheet 4, and penetrating the light-reflecting layer 5 in the layer thickness direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sheet, a backlight unit using the same, a display device, and a method for manufacturing the same. For example, the present invention relates to an optical sheet suitable for controlling an illumination optical path to a liquid crystal display element, a backlight unit using the same, a display device, and a manufacturing method thereof.

2. Description of the Related Art Conventionally, for example, a display device represented by a liquid crystal display device (LCD) has a backlight unit disposed on the back side of a liquid crystal display element in which ON / OFF of each pixel is controlled according to an image signal. Light from the unit is used as display light. In such an LCD, the power consumption of the liquid crystal display element is small, but the power consumption of the backlight unit is large. For example, when used in battery-powered devices such as laptop computers and mobile phones, the light of the light source It is demanded to reduce the power consumption of the apparatus by increasing the use efficiency of the apparatus.
Therefore, an optical sheet having a plurality of lenses, prisms, and the like is often disposed between the liquid crystal display element and the backlight unit in order to collect diffused light from the backlight unit to some extent.
For example, Patent Document 1 includes a liquid crystal panel and light source means for irradiating light from the back side to the liquid crystal panel, and the light source means is provided with a lens layer that guides light from the light source to the liquid crystal panel. A liquid crystal display device having a light shielding portion having an opening in the vicinity of the focal plane of the lens layer or a light shielding portion having an opening outside the focal plane of the lens layer in a positional relationship where an image is formed inside the liquid crystal layer by the lens layer is described. .
Patent Document 1 suggests that the light use efficiency can be further improved by using a light shielding portion as a reflective layer.
JP 2000-284268 A (FIGS. 1-3)

However, the above-described conventional optical sheet has the following problems.
In the technique described in Patent Document 1, a light shielding layer having an opening on the plane side of the lens layer is integrally formed. This opening provides a light transmission range of a certain size between the light source and the optical element, and forms an air layer to refract light incident at a large incident angle on the optical element to the opening. It has a function to bend the light beam to the opposite optical element side.
On the other hand, when such an optical sheet is attached to the light source unit or a light diffusion layer is disposed before entering the lens layer, a light-transmitting adhesive layer or adhesive layer is provided from the viewpoint of cost and productivity. In many cases, the adhesive layer or the adhesive layer protrudes into the opening and reaches the optical element, and part or all of the opening may be filled with the adhesive layer or the adhesive layer.
In such a case, in the buried portion, light is incident on the optical element medium from the medium of the adhesive layer or the adhesive layer, so that there is almost no difference in refractive index. For this reason, light incident on the aperture at a large incident angle travels substantially straight, causing stray light to the optical elements arranged around the optical element facing the aperture, generating luminance unevenness, or from the optical element. There is a problem in that the light is not emitted and the amount of light is reduced.
It is conceivable to apply the adhesive layer or adhesive layer with a weak force so that the adhesive layer or adhesive layer does not protrude from the opening, but there are problems that the reliability of the application cannot be obtained or that the application process takes extra time. is there.

  The present invention has been made in view of the above problems, and provides an optical sheet that can reduce luminance unevenness of transmitted light, a backlight unit using the same, a display device, and a method for manufacturing the same. For the purpose.

In order to solve the above problems, in the invention according to claim 1, an optical element sheet having a plurality of optical elements arranged in an array and a light incident range with respect to each of the plurality of optical elements are regulated. A light-reflecting layer having a light-shielding pattern; a light-scattering layer that scatters light incident on the optical element sheet from the light-reflecting layer side on the front side of the light-reflecting layer; and A light-transmitting bonding layer that fixes the light-shielding pattern with an anti-compressible medium having a refractive index lower than the refractive index of the optical element sheet. And a light reflecting portion that forms a light shielding portion of the light shielding pattern, and the transparent portion is in close contact with the bonding layer and the optical element sheet and penetrates in the layer thickness direction of the light reflecting layer. Provided And it formed.
According to this invention, the optical element sheet having a plurality of optical elements, the light reflecting layer, the bonding layer, and the light scattering layer are laminated in this order, and the light reflecting layer has a lower refractive index than the refractive index of each optical element. The transparent portion and the light reflecting portion made of the anti-compressible medium are penetrated in the layer thickness direction to form a light shielding pattern. For this reason, even if an external force is applied, for example, the bonding layer does not crush the transparent portion and reach the optical element sheet, so that light directed from the light reflecting layer side to the optical element sheet is surely transparent with a low refractive index. And is incident on the optical element sheet. By having such a transparent part, the size of each light transmitting part of the light shielding pattern and the difference in refractive index between the light transmitting part and the optical element sheet facing each other can be kept constant.
In this specification, the term “anticompressible medium” means a medium that has a remarkably large resistance to compressive force as compared with gas and occupies a substantially constant volume in use, for example, a solid, liquid, gel-like body. And so on.

According to a second aspect of the present invention, in the optical sheet according to the first aspect, the plurality of optical elements are composed of lenticular lenses in which convex cylindrical lens groups are arranged in parallel in one direction.
According to this invention, since the optical element is composed of a lenticular lens, light can be efficiently condensed in a direction orthogonal to the direction in which the convex cylindrical lens group extends.

According to a third aspect of the present invention, in the optical sheet according to the second aspect, the lenticular lens is formed by polymerizing and bonding a lens portion made of a cured product of a radiation curable resin to a sheet-like substrate. And
According to the present invention, the lens portion is formed by polymerizing and bonding the cured product of the radiation curable resin to the sheet-like base material. For example, the cross-sectional shape of the lens portion is more accurate than extrusion molding. Can be formed.

According to a fourth aspect of the present invention, in the optical sheet according to any one of the first to third aspects, the transparent portion is formed by resin molding using a thermoplastic resin or a radiation curable resin.
According to this invention, since the transparent portion is formed by resin molding, the positional accuracy with respect to the optical element can be improved.

According to a fifth aspect of the present invention, in the backlight unit, the optical sheet according to any one of the first to fourth aspects and a light source unit that makes light incident on the optical sheet from the light reflecting layer side. It is set as the structure provided.
According to this invention, since the optical sheet according to any one of claims 1 to 4 is used, the same effect as the invention according to any one of claims 1 to 4 is provided.

According to a sixth aspect of the present invention, the display device includes the backlight unit according to the fifth aspect and a liquid crystal display unit that displays an image using light from the backlight unit as display light.
According to this invention, since the backlight unit according to claim 5 using the optical sheet according to any one of claims 1 to 4 is used, the same as the invention according to any one of claims 1 to 4 is used. Provide operational effects.

In the invention according to claim 7, an optical element sheet having a plurality of optical elements arranged in an array, a light reflection layer having a light-shielding pattern that regulates an incident range of light to each of the plurality of optical elements, A light-scattering layer that scatters light incident on the optical element sheet from the light-reflecting layer side on the front side of the light-reflecting layer, and a light transmission portion of the light-shielding pattern is based on a refractive index of the optical element sheet Is a method of manufacturing an optical sheet made of an anti-compressible medium having a low refractive index, and a light-shielding portion of the light-shielding pattern made of a light-reflective material, wherein the optical element sheet after the formation of the plurality of optical elements or the plurality Any one of the light transmission part and the light-shielding part of the light-shielding pattern on the sheet surface of the optical element sheet before the optical element is formed on the sheet surface opposite to the surface on which the plurality of optical elements are formed or formed. A first pattern layer forming step of forming a first pattern layer by patterning a first pattern layer forming material for forming the first pattern layer with a certain thickness, and at least on the sheet surface on which the first pattern layer is formed A second pattern layer forming material application step of applying a second pattern layer forming material for forming either the light transmitting portion or the light shielding portion of the light shielding pattern up to a height covering the first pattern layer; and the second pattern layer A second pattern layer thickness adjusting step for leveling the second pattern layer forming material applied in the applying step to the same height as the first pattern layer; and the second pattern layer thickness adjusting step after the second pattern layer layer adjusting step. And a light scattering layer bonding step of bonding the light scattering layer to the upper surfaces of the first and second pattern layers via the bonding layer.
According to this invention, in the first pattern layer forming step, any one of the light transmission part and the light shielding part of the light shielding pattern is formed on the sheet surface opposite to the surface on which the plurality of optical elements in the optical element sheet are formed or formed. The first pattern layer forming material forming either one is patterned with a constant thickness.
Then, in the second pattern layer forming material application step, the second pattern layer forming material is applied onto the substrate on which the first pattern layer is formed to a height that at least covers the first pattern layer.
Next, in the second pattern layer layer thickness adjusting step, the second pattern layer forming material is leveled to the same height as the first pattern layer.
In the light scattering layer bonding step, the light scattering layer is bonded to the upper surfaces of the first and second pattern layers having the same height through the bonding layer.
In these steps, the material forming the light transmission portion of the light shielding pattern of the first and second pattern layer forming materials is an anti-compressible medium having a refractive index lower than the refractive index of the base material of the optical element sheet. The material for forming the light shielding portion is a light reflective material.
Thereby, the optical sheet according to claim 1 can be formed.

In the case where a plurality of optical elements are not formed on the optical element sheet in the first pattern layer forming step, the step of forming the plurality of optical elements on the optical element sheet is an appropriate step after the first pattern layer forming step. Although it can be carried out at the timing, for example, it is preferably carried out before the second pattern layer forming material coating step or between the second pattern layer layer thickness adjusting step and the light scattering layer bonding step.
Further, when the second pattern layer forming material is a curable material, the second pattern layer forming material is used by using a curing accelerating means corresponding to the curable material between the second pattern layer layer thickness adjusting step and the light scattering layer bonding step. It is preferable to provide a curing acceleration step for accelerating the curing of the two-pattern layer forming material.

According to the optical sheet of the present invention, the backlight unit using the same, the display device, and the manufacturing method thereof, the refractive index difference between the light transmitting portions of the light shielding patterns facing each other and the boundary surface between the optical element sheet is kept constant. Therefore, it is possible to reduce the luminance unevenness of the transmitted light of each light transmitting portion of the light shielding pattern.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.
The optical sheet which concerns on embodiment of this invention is demonstrated with the backlight unit and display apparatus using the same.
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a display device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram viewed from A in FIG. In addition, since each figure is a schematic diagram, the dimension ratio etc. are exaggerated (and the following are also the same).

As shown in FIG. 1, the display device 100 of the present embodiment includes a light source unit 20, an optical sheet 21, and a liquid crystal display unit 22 stacked in this order, and display control is performed by image signals from the liquid crystal display unit 22 toward the upper side in the figure. By emitting the displayed light, an image is displayed on a rectangular display screen in plan view.
The light source unit 20 and the optical sheet 21 constitute a backlight unit 23.
In the following, unless there is a risk of misunderstanding, based on such an arrangement relationship, the display screen side may be referred to when referring to the upper direction in FIG.

The light source unit 20 extends in an area that covers the range of the display screen of the liquid crystal display unit 22 and is disposed to face the optical sheet 21. Then, light with a substantially uniform light amount distribution can be emitted from the emission surface 20a toward the optical sheet 21 side.
Although the detailed configuration of the light source unit 20 is not particularly illustrated, any known configuration may be adopted as long as the light incident on the emission surface 20a from the display screen side can be reused.
For example, a configuration including a light guide plate extending in a range covering the liquid crystal display unit 22 and a light source that receives light from a side end portion of the light guide plate can be employed. In this case, the light incident on the light guide plate from the display screen side is guided by repeating internal reflection in the light guide plate according to the incident angle, and is transmitted to the display screen side when the incident angle is constant. Reused as light source light.
Further, for example, a lamp house type configuration including a light source and reflectors disposed on a side surface side and a back surface side of the light source may be employed. In this case, the light returning from the display screen side is reflected on the display screen side by being repeatedly reflected by the reflection plate, and is reused as light source light.
The degree of uniformity of the light amount distribution of the light source unit 20 can be set as appropriate according to the light scattering performance of the light scattering layer 7 described later.

The optical sheet 21 collects a part of the light emitted from the emission surface 20a of the light source unit 20 and transmits it to the display screen side, reflects the other light to the light source unit 20 side, and reenters the light source unit 20. It is something to be made.
In the present embodiment, a lens sheet 4 (optical element sheet) in which a lens portion 4b (a plurality of optical elements) is formed on one surface of a light-transmitting sheet-like base material 4a, and a lens portion of the base material 4a. 4 b, a light reflecting layer 5 formed on the surface opposite to 4 b, and a light scattering layer 7 bonded on the light reflecting layer 5 via a bonding layer 6. The light scattering layer 7 is an emission surface of the light source unit 20. It is arranged facing the 20a side.

  As the base material 4a, an appropriate plastic film having a light transmitting property with a wavelength of light emitted from the light source unit 20 can be employed. Examples of the plastic film include films of polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene (PE), and the like. Although the refractive index of these films depends on the grade or the like, typical refractive index values are shown for reference purposes as 1.54 (PET), 1.50 (PP), 1.58 (PC), 1 .49 (PMMA) and 1.52 (PE).

  In this embodiment, as shown in FIGS. 1 and 2, the light reflecting layer 5 has a light reflecting portion 5A and a transparent portion 5B, which are formed in stripes with the same layer thickness h, in the direction perpendicular to the plane of FIG. It is extended and alternately arranged in parallel at a pitch P perpendicular to the extending direction. That is, a stripe-shaped light shielding pattern is formed which includes a light shielding portion by the light reflecting portion 5A and a light transmitting portion by the transparent portion 5B. Thereby, the incident range of the light which injects into the lens part 4b through the base material 4a is controlled.

The side surfaces in the adjacent direction of the light reflecting portion 5A and the transparent portion 5B may be inclined with respect to the layer thickness direction according to the manufacturing method. Although not shown in FIGS. 1 and 2, in this embodiment, since the transparent portion 5B is formed by resin molding, the width of the transparent portion 5B is slightly reduced in the direction away from the base material 4a. Yes.
The widths of the light reflecting portion 5A and the transparent portion 5B on the surface of the substrate 4a are w and W (where w + W = P), respectively.
The width W of the transparent part 5B takes into consideration the focal position and NA of the lens part 4b, and light incident on the transparent part 5B from the back side efficiently enters the lens part 4b at a position facing the transparent part 5B. The width is set so as to make it difficult to enter the lens portion 4b other than the position facing the transparent portion 5B.

The light reflecting portion 5A can be made of an appropriate material having light reflectivity. In this embodiment, as will be described later, for example, the lipophilic white ink containing a white pigment such as TiO ₂ is dried. The reflectivity of the light reflecting portion 5A is set to an appropriate high reflectivity as required in the wavelength range of visible light used as display light in order to improve the light use efficiency of the light source unit 20. preferable. For example, it is preferable to set the reflectance so that the reflectance at a wavelength of 540 nm is 80% or more.

The transparent part 5B is composed of an anti-compressible medium having a lower refractive index than the base material 4a. In this embodiment, it forms using the ultraviolet curing molding method which forms the ultraviolet curable resin which is a radiation curable resin containing a fluorine-type polymer, and arrange | positions on the base material 4a. For this reason, the transparent portion 5B is polymerized and bonded to the base material 4a.
The refractive index of the fluorine-based polymer is generally about 1.3 to 1.43, which is a low refractive index with respect to any of the materials of the substrate 4a exemplified above. As an example of the fluorine-based polymer, Cytop (registered trademark) manufactured by Asahi Glass Co., Ltd., which is an amorphous fluororesin, can be mentioned. In this case, the refractive index is 1.34.
Examples of the resin having a low refractive index other than the fluorine-based polymer include a silicone resin having a refractive index of 1.4.

The lens portion 4b is an optical element that condenses the diffused light that is transmitted through the transparent portion 5B, is incident on the base material 4a, and is emitted to the transparent portion 5B toward the liquid crystal display portion 22 side.
In this embodiment, it is a convex cylindrical lens array, that is, a lenticular lens, arranged in parallel at a pitch P so that the focal position extends along the center of the transparent portion 5B on the base sheet 4.
The position of the focal point of the lens unit 4b in the optical axis direction is set in the vicinity of the inside of the transparent part 5B or the outside.
In the present embodiment, the lens shape of the lens portion 4b is an aspherical shape in which an elliptical surface is used as a reference surface and correction is performed using a high-order term in order to improve light collection efficiency. However, a known appropriate lens shape, for example, another aspherical surface, an elliptical surface, a spherical surface, or the like may be employed depending on the required light collecting performance.

In this embodiment, the lens portion 4b is formed of an ultraviolet curable resin containing a transparent resin polymer having the same or higher refractive index as that of the substrate 4a, and a plurality of ultraviolet curing molding methods as in the transparent portion 5B. The lens portion 4b is polymerized and bonded to the base material 4a.
Here, the arrangement pitch P of the lens part 4b and the transparent part 5B is matched with the arrangement pitch in one direction of the pixel region 22a (see FIG. 2) of the liquid crystal display part 22.

The light scattering layer 7 is for diffusing light incident on the optical sheet 21 from the light source unit 20 to prevent luminance unevenness.
As well known in the art, the light scattering layer 7 includes, for example, a high refractive index resin or fine particles (filler) that scatters light in a transparent material such as a plastic film or a plastic plate. It is possible to use a light emitting device or a material obtained by processing the emission surface 7a on the display screen side into a mat shape.
The light scattering layer 7 is bonded to the light reflecting layer 5 via a bonding layer 6 made of a light-transmitting pressure-sensitive adhesive or adhesive provided on the emission surface 7a. For this reason, the light reflecting portions 5A and the transparent portions 5B of the light reflecting layer 5 and the bonding layer 6 are closely bonded and bonded without forming an air layer or the like.
That is, the light that passes through the light scattering layer 7 and enters the base material 4a passes through only the medium of the transparent portion 5B and enters the base material 4a.

The liquid crystal display unit 22 is configured, for example, by enclosing a liquid crystal between two sealing substrates on which an alignment film and a transparent electrode are formed. Further, the liquid crystal display unit 22 is sandwiched between polarizing plates so that a pixel region 22a ( A liquid crystal shutter is formed every time (see FIG. 2).
Here, a method for manufacturing the optical sheet 21 will be described.
FIG. 3 is a schematic explanatory view illustrating a schematic configuration of an optical sheet manufacturing apparatus for performing the optical sheet manufacturing method according to the embodiment of the present invention. FIG. 4A is a front view of a mold roller used in the method of manufacturing an optical sheet according to the embodiment of the present invention. 4 (b) and 4 (c) are enlarged partial cross-sectional views of part B in FIG. 4 (a). FIG. 5 is a process explanatory diagram illustrating a molding process of the optical element of the optical sheet according to the embodiment of the present invention. FIG. 6 is a process explanatory view illustrating a first pattern layer forming process of the method for manufacturing an optical sheet according to the embodiment of the present invention. FIGS. 7A and 7B are process explanatory views illustrating the second pattern layer forming material application process of the method for manufacturing an optical sheet according to the embodiment of the present invention. Fig.8 (a) is process explanatory drawing explaining the 2nd pattern layer layer thickness adjustment process of the manufacturing method of the optical sheet which concerns on embodiment of this invention. FIG.8 (b) is CC sectional drawing of Fig.8 (a). FIG. 9 is a process explanatory diagram showing a state immediately before the light scattering layer bonding process of the method for manufacturing an optical sheet according to the embodiment of the present invention.

  As shown in FIG. 3, the optical sheet manufacturing apparatus 200 that manufactures the optical sheet 21 includes a film unwinding unit 40, an optical element forming unit 41, a first pattern layer forming unit 42, a second pattern layer forming unit 43, and an optical unit. The sheet take-up portions 44 are sequentially arranged, and the substrate 4a is continuously conveyed between them, and in the process, the optical element forming step for forming the lens portion 4b, the first pattern layer forming step, and the second pattern layer forming material applying step The second pattern layer layer thickness adjusting step, the second pattern layer hardening accelerating step, and the light scattering layer bonding step can be sequentially performed.

In the film unwinding section 40, the substrate 4 a is unwound from the film reel 70 on which the PET film original fabric used for the substrate 4 a is installed via the roller 46 and conveyed to the optical element forming section 41.
The unrolled substrate 4a may be subjected to an appropriate easy-adhesion treatment such as a surface modification treatment in order to improve the adhesion of the radiation curable resin during the conveyance process in the film unwinding section 40. .

In the optical element molding unit 41, an optical element molding process is performed using a mold roller 48.
As shown in FIGS. 4A and 4C, the mold roller 48 has grooves 48a formed on the roller surface in the circumferential direction of the roller corresponding to the lens shape of the lens portion 4b at a pitch p2 in the roller axial direction. A necessary number of strips are formed to constitute an optical element molding plate.
As shown in FIG. 4C, the groove 48a is formed in a shape represented by a groove depth d and an aspherical curvature radius R. Here, p ₂ , d, and R are set so as to obtain a necessary shape and pitch of the lens portion 4b in consideration of molding shrinkage and the like.

The substrate 4 a conveyed to the optical element molding unit 41 is wound around the outer periphery of the mold roller 48 by the winding roller 45 and is conveyed in synchronization with the rotation of the mold roller 48.
On the other hand, the radiation curable resin 60 is supplied (coated) to each groove 48 a by the radiation curable resin supply unit 50 on the mold roller 48 on the upstream side in the rotation direction of the winding roller 45. Therefore, as shown in FIG. 5, the rotation proceeds in a state where the radiation curable resin 60 is filled between each groove 48 a and one surface of the base material 4 a.
In this state, a radiation Q ₁ for curing the radiation curable resin 60 is irradiated from a radiation source 47 disposed opposite to the mold roller 48. Radiation Q ₁ is transmitted through the substrate 4a, curing the radiation-curable resin 60 in the grooves 48a.
In the present embodiment, the radiation curable resin 60 is an ultraviolet curable resin, and the radiation Q ₁ is ultraviolet light.

  Next, the base material 4 a on which the lens portion 4 b is formed on one surface is conveyed to the first pattern layer forming portion 42. In the first pattern layer forming unit 42, the first pattern layer forming step is performed using the mold roller 51. In the present embodiment, the first pattern layer is a light transmission portion of the light shielding pattern, that is, the transparent portion 5B.

As shown in FIGS. 4A and 4B, the mold roller 51 has grooves 51a formed on the roller surface over the roller circumferential direction corresponding to the convex shape of the transparent portion 5B, with a pitch p _{1 in the} roller axial direction. The necessary number of strips is formed, and constitutes a transparent part molding plate. Here, p ₁ and w are set so as to obtain a necessary shape and pitch of the transparent portion 5B in consideration of molding shrinkage and the like.
As shown in FIG. 4 (b), the groove 51a has a trapezoidal shape with a groove depth h, a groove bottom having a width w, and a groove side surface being opened radially outward at an angle θ. In this way, by providing an inclination on the groove side surface of the groove portion 51a, it is possible to ensure releasability during molding.
As for the position of the mold roller 51 in the axial direction, for example, the fixing position of the mold roller 51 is adjusted with a fine adjustment screw or the like so that the center position of the groove 51a substantially coincides with the optical axis after the lens unit 4b is cured. The position is adjusted with respect to the mold roller 48 by adjusting by means.

The substrate 4 a transported to the first pattern layer forming unit 42 is wound around the outer periphery of the mold roller 51 by the winding roller 45 and is transported in synchronization with the rotation of the mold roller 51.
On the other hand, the radiation curable resin 61 that forms the transparent portion 5B in each groove 51a is supplied (coated) to the mold roller 51 by the radiation curable resin supply unit 53 on the upstream side in the rotation direction of the winding roller 45. ing. Therefore, as shown in FIG. 6, the rotation proceeds in a state in which the radiation curable resin 61 is filled between each groove 51a and the other surface of the substrate 4a.
In this state, from the radiation source 52 disposed opposite to the mold roller 51, the radiation Q ₂ to which curing the radiation curable resin 61 is irradiated. Radiation Q ₂ are can be irradiated to the lens unit 4b, it passes through the substrate 4a, the radiation curable resin 60 in the grooves 51a located on the range to be collected by the lens unit 4b. Therefore, it can be quickly cured without causing uneven curing. Therefore, the amount of irradiation can be minimized, and distortion due to shrinkage during curing can be minimized.
In this embodiment, the radiation curable resin 61 is ultraviolet curable resin, radiation Q ₂ is an ultraviolet light. The wavelength of the radiation Q ₂ may be the same as or different from the radiation Q ₁ as necessary.

In the present process, the radiation Q ₂ is also irradiated to the lens unit 4b. Therefore, the radiation Q ₂ is, in the case where each of the radiation curable resin 60, 61 can be cured is kept to a lens portion hardening step minimum curing of the need on the transport of 4b in the optical element molding process, In the first pattern layer forming step, the radiation curable resin 60 may be cured together with the curing of the radiation curable resin 61.
In this case, molding shrinkage due to the progress of curing in the optical element molding step can be further reduced, so that a dimensional change after the optical element molding step can be suppressed, and higher-precision molding becomes possible.

The base material 4a is separated from the mold roller 51 by the separation roller 49 at the stage where the curing of the radiation curable resin 61 is completed, and as shown in FIG. The lens part 4b is released from the mold roller 51 in a state where the lens part 4b is aligned on the other side and the transparent part 5B is aligned and bonded to the other surface (the upper side in the figure).
After the mold release, the resin of the transparent portion 5B may be dried using a dryer or the like as appropriate.
Thus, the first pattern layer forming process is completed.

Next, the base material 4a on which the lens portion 4b and the transparent portion 5B are formed is conveyed to the second pattern layer forming portion 43.
In the second pattern layer forming unit 43, the coating pretreatment unit 11, the second pattern layer forming material supply unit 12, the doctor knife 13, and the curing accelerating unit 14 are arranged above the substrate 4 a to be conveyed from the upstream side in the conveyance direction. Is provided.
The application pretreatment unit 11 performs pretreatment necessary for applying the second pattern layer forming material 10 by the second pattern layer forming material supply unit 12 to the base material 4a and the transparent portion 5B. In the present embodiment, the second pattern layer forming material 10 that is an oleophilic white ink is applied so as to fill the gap between the transparent portions 5B above the base material 4a and scraped off with the doctor knife 13, but at that time, the transparent In order to prevent the lipophilic second pattern layer forming material 10 from remaining and adhering to the surface (excluding side surfaces) of the portion 5B, only the upper surface excluding the side surface of the transparent portion 5B is subjected to hydrophilic treatment. Yes.
In addition, the application | coating pre-processing part 11 can be abbreviate | omitted especially when pre-processing is not required.

In the 2nd pattern layer forming material supply part 12, as shown in FIG.7 (b), the 2nd pattern which apply | coats the 2nd pattern layer forming material 10 to the height which covers at least the transparent part 5B with respect to the base material 4a. A layer coating process is performed.
In the present embodiment, the second pattern layer forming material 10 is made of an oleophilic white ink having excellent drying properties for forming the light reflecting portion 5A.

The doctor knife 13 has an end face disposed at a height h that contacts the upper end of the transparent portion 5B with respect to the base material 4a, and is a scraping member that extends in the width direction across the transport direction of the base material 4a. It is. As a result, as shown in FIGS. 8A and 8B, when passing under the doctor knife 13, the second pattern layer forming material 10 is appropriately scraped off, and the second pattern layer forming material 10 is It passes in a state that is leveled with the transparent portion 5B. That is, the second pattern layer thickness adjusting step is performed by the doctor knife 13.
The curing promoting means 14 performs a curing accelerating step of drying the second pattern layer forming material 10 with an appropriate dryer or the like. Thereby, the light reflection layer 5 which consists of the hardened | cured light reflection part 5A and the transparent part 5B is formed on the base material 4a (refer FIG. 9).

Next, in the optical sheet take-up unit 44, as shown in FIG. 3, a light scattering film 80 is pasted on the light reflecting layer 5 formed by the second pattern layer forming unit 43.
The light scattering film 80 is obtained by forming the bonding layer 6 on one surface of the light scattering layer 7, and in this embodiment, the light scattering film 80 is unwound from the light scattering film reel 71 toward the lower surface in the drawing, By the laminating roller 54, the bonding layer 6 and the light reflecting layer 5 are bonded and integrated in synchronization with the conveyance of the base material 4 a. In this way, the light scattering layer joining step is completed, and the optical sheet 21 is wound around the take-up reel 72.

Thus, according to the optical sheet manufacturing method of the present embodiment, the optical sheet manufacturing apparatus 200 transports the base material 4a while the optical element forming step, the first pattern forming step, and the second pattern layer material applying step. The optical sheet 21 can be continuously manufactured by sequentially performing the second pattern layer layer thickness adjusting step, the curing accelerating step, and the light scattering layer bonding step.
At that time, the lens portion 4b and the transparent portion 5B of the light reflecting layer 5 are formed on the base material 4a in this order by using the aligned mold rollers 48 and 51, so that each is a separate sheet. Can be manufactured with high accuracy of positioning without taking time and effort such as manufacturing and bonding.
In this embodiment as well, the positional relationship between the mold rollers 48 and 51 needs to be adjusted. However, since the respective steps for forming the lens portion 4b and the light reflecting layer 5 are continuously performed under certain conditions, the alignment is initial. Just do it.

Next, the operation of the display device 100 will be described focusing on the operation of the optical sheet 21.
As shown in FIG. 1, the light emitted from the light source unit 20 is emitted from the emission surface 20b toward the optical sheet 21, and the back side of the optical sheet 21 is entirely illuminated.
The light emitted from the emission surface 20 b enters the light scattering layer 7 and is appropriately diffused to make the luminance unevenness substantially uniform, and enters the light reflecting layer 5 through the bonding layer 6.
In the light reflecting layer 5, the light that has reached the light reflecting portion 5 </ b> A is reflected back and returned to the light source portion 20 through the light scattering layer 7 to be reused as illumination light.
The light that has reached the transparent portion 5B is transmitted in various directions with a spread angle and is incident on the base material 4a. At this time, the width of the light flux is restricted to W by the transparent portion 5B, and light enters the base material 4a having a high refractive index from the transparent portion 5B having a low refractive index. Therefore, the spread angle of the light incident on the base material 4a is narrowed by refraction.

Since the transparent portion 5B is made of an anti-compressible medium, a stable layer thickness can be maintained even when subjected to an external force or the like. Therefore, a stable low refractive index region is formed between the bonding layer 6 and the base material 4a for each pixel region 22a.
Therefore, since the light incident on the substrate 4a is always incident from the transparent portion 5B which is a relative low refractive index region, even a light beam having a large incident angle is refracted and proceeds in a direction with a smaller emission angle. . Therefore, the transparent portion 5B advances in the direction of the lens portion 4b facing the transparent portion 5B in a state where the divergence angle in the transparent portion 5B is narrowed.

  For example, when the low refractive index region is formed by an air layer or the like, if a part or all of the high refractive index bonding layer 6 protrudes toward the base material 4a, the low refractive index region is lost due to contact with the base material 4a. It will be broken. In this case, the light incident on the transparent part 5B at a large incident angle travels substantially straight and is not emitted from the opposing lens part 4b, or enters the surrounding lens part 4b and becomes stray light. In the embodiment, such a phenomenon does not occur, and the low refractive region is ensured. For this reason, the luminance unevenness of the incident light to the liquid crystal display unit 22 can be reduced.

The light incident on the base material 4a has a narrower spread angle, and thus travels toward the lens unit 4b located at the position opposite to the transparent unit 5B, and is emitted from the lens unit 4b to the display screen side. At this time, since the focal position of the lens portion 4b is set in the vicinity of the transparent portion 5B of the base material 4a, the light emitted from the lens portion 4b through the transparent portion 5B is refracted by the lens portion 4b. The light is condensed in the direction having the right angle (the horizontal direction in FIG. 1).
For this reason, the light emitted from the lens unit 4b is substantially incident on the pixel region 22a of the liquid crystal display unit 22 at a position facing the lens unit 4b.
In the liquid crystal display unit 22, light from a predetermined pixel region 22a is transmitted as display light according to the polarization state of each pixel region 22a controlled by a drive unit (not shown) based on the image signal, and image display is performed. Is called.

  Here, if the light from the transparent portion 5B is emitted in a range larger than the NA of the lens portion 4b, it is not used as display light, and light amount loss occurs, or the light enters the other pixel region 22a to cause luminance unevenness. Or Therefore, in order to improve the light utilization efficiency and the display image quality, it is preferable that the width W of the transparent portion 5B is narrow. However, if the width W is too narrow, the parallelism of the light emitted from the lens portion 4b becomes too strong, which may cause the moire due to luminance unevenness and the viewing angle to become too narrow. Accordingly, the width W is appropriately set in consideration of these.

  Thus, the optical sheet 21 of the present embodiment forms a stable low refractive index region by the transparent portion 5B, and the light that has passed through the transparent portion 5B is incident on the lens sheet 4, so that the light scattering layer 7 is bonded to the bonding layer. Even if they are joined together, the low refractive index region is secured, so that variations in the optical characteristics of each light transmitting portion of the light shielding pattern can be reduced.

In the above description, the lens sheet 4 is described as an example of the case where the lens portion 4b is formed by polymerizing and bonding to the substrate 4a by an ultraviolet curing molding method. However, the lens sheet 4 is separately manufactured and bonded. You may join to the base material 4a by the above.
Further, the lens sheet 4 may be integrally molded by an extrusion molding method, an injection molding method, a hot press molding method, or the like well known in the technical field, without being separated from the base material 4a. . In this case, PET, PC, PMMA, cycloolefin polymer (COP), or the like can be used as the material of the lens sheet 4 in which the base material 4a is integrated.

  In the above description, the lens portion 4b and the transparent portion 5B have been described as an example of molding using an ultraviolet curable resin that is a radiation curable resin. However, an electron beam curable resin is used as the radiation curable resin. May be.

In the above description, the transparent portion 5B is described as an example in which the transparent portion 5B is molded using a fluorine polymer. However, the low refractive index material forming the transparent portion 5B is not limited to the fluorine polymer. Further, the forming means is not limited to resin molding.
For example, it may be formed by coating magnesium fluoride (refractive index 1.37) or sodium fluoride (refractive index 1.32).
Silicone resin can also be suitably employed because it has a refractive index of about 1.4 and a low refractive index. In the case of a silicone resin, either resin molding or coating is possible.

In the above description, when the light reflecting layer 5 is formed, the transparent portion 5B is patterned as the first pattern layer, and the light reflecting portion 5A is formed as the second pattern layer. Conversely, the light reflecting portion 5A may be formed as the first pattern layer, and the transparent portion 5B may be formed as the second pattern layer.
In the latter case, the positional relationship in the axial direction of the mold rollers 48 and 51 is the same as the above except that the center of the transparent portion 5B is set on the optical axis 31 of the lens portion 4b. Can be formed.
In this case, as the second pattern layer forming material 10, a low refractive index material is applied so as to cover the light reflecting portion 5A, but the second pattern layer forming material 10 is not leaked in the transport direction. In the case where the light scattering film 80 can be bonded, the second pattern layer forming portion 43 may omit the curing accelerating step and not cure the second pattern layer forming material 10.
In this case, the second pattern layer forming material 10 and an anti-compressive medium such as liquid or gel, for example, high viscosity silicone oil or gelled silicone can be employed.

  In the above description, the example in which the light reflecting layer is formed on the back side where the optical element is formed in the optical element forming step has been described. However, the optical element is formed on one surface of the sheet-like base material. In the case of forming, the timing of forming the optical element can be set as appropriate. For example, the first pattern layer may be formed on the other surface of the substrate, the light reflection layer may be formed, or the light scattering layer may be bonded to the light reflection layer.

In the above description, the optical element is described as an example of a lenticular lens formed in a stripe shape, but the optical element is a microlens in which unit lenses having an appropriate shape are two-dimensionally arranged as necessary. An array can also be employed. In this case, the transparent portions 5B may be arranged in a two-dimensional lattice shape in accordance with the arrangement of the light shielding patterns.
In addition, the optical element is not limited to a lens, and may be, for example, a prism array having a triangular prism shape or the like that regulates the emission direction of light toward the liquid crystal display unit by refraction.

In the above description, an example in which oleophilic white ink is used as the second pattern layer forming material has been described. However, a radiation curable resin may be used as in the case of the first pattern layer.
Moreover, you may form a 1st pattern layer by the transfer method by an ultraviolet curable adhesive material, for example.

It is typical sectional drawing which shows schematic structure of the display apparatus which concerns on embodiment of this invention. It is A view explanatory drawing in FIG. It is a schematic explanatory drawing explaining the schematic structure of the optical sheet manufacturing apparatus for performing the manufacturing method of the optical sheet which concerns on embodiment of this invention. It is the front view of the metal mold | die roller used for the manufacturing method of the optical sheet which concerns on embodiment of this invention, and the expanded partial sectional view of the B section. It is process explanatory drawing explaining the formation process of the optical element of the optical sheet which concerns on embodiment of this invention. It is process explanatory drawing explaining the 1st pattern layer formation process of the manufacturing method of the optical sheet which concerns on embodiment of this invention. It is process explanatory drawing explaining the 2nd pattern layer forming material application | coating process of the manufacturing method of the optical sheet which concerns on embodiment of this invention. It is process explanatory drawing explaining the 2nd pattern layer layer thickness adjustment process of the manufacturing method of the optical sheet which concerns on embodiment of this invention, and its CC sectional drawing. It is process explanatory drawing which shows the mode just before the light-scattering layer joining process of the manufacturing method of the optical sheet which concerns on embodiment of this invention.

Explanation of symbols

4 Lens sheet (Optical element sheet)
4a Base material 4b Lens part (plural optical elements)
DESCRIPTION OF SYMBOLS 5 Light reflection layer 5A Light reflection part 5B Transparent part 6 Bonding layer 7 Light scattering layer 10 2nd pattern layer formation material 12 2nd pattern layer formation material supply part 13 Doctor knife 14 Curing acceleration means 20 Light source part 21 Optical sheet 22 Liquid crystal display Unit 23 Backlight unit 41 Optical element molding unit 42 Solid pattern layer molding unit 43 Light reflection layer forming unit 47, 52 Radiation source 48, 51 Mold roller 50, 53 Radiation curable resin supply unit 54 Laminating roller 60, 61 Radiation Curable resin 80 Light scattering film 100 Display device
200 Optical sheet manufacturing apparatus

Claims (7)

An optical element sheet having a plurality of optical elements arranged in an array;
A light reflecting layer having a light shielding pattern for restricting an incident range of light to each of the plurality of optical elements;
A light scattering layer that scatters light incident on the optical element sheet from the light reflecting layer side on the front side of the light reflecting layer;
A light-transmitting bonding layer for fixing the light scattering layer to the light reflecting layer,
The light reflecting layer includes a transparent portion that forms a light transmitting portion of the light shielding pattern with an anti-compressible medium having a lower refractive index than the refractive index of the optical element sheet, and a light reflecting portion that forms the light shielding portion of the light shielding pattern. And
The transparent sheet is provided in close contact with the bonding layer and the optical element sheet, and is provided so as to penetrate in the layer thickness direction of the light reflecting layer.   The optical sheet according to claim 1, wherein the plurality of optical elements are lenticular lenses in which convex cylindrical lens groups are arranged in parallel in one direction.   The optical sheet according to claim 2, wherein the lenticular lens is formed by polymerizing and bonding a lens portion made of a cured product of a radiation curable resin to a sheet-like base material.   The optical sheet according to claim 1, wherein the transparent portion is formed by resin molding using a thermoplastic resin or a radiation curable resin. The optical sheet according to any one of claims 1 to 4,
A backlight unit comprising: a light source unit that makes light incident on the optical sheet from the light reflection layer side. The backlight unit according to claim 5;
A display device comprising a liquid crystal display unit that displays an image using light from the backlight unit as display light. An optical element sheet having a plurality of optical elements arranged in an array, a light reflection layer having a light-shielding pattern that regulates an incident range of light with respect to each of the plurality of optical elements, and the optical from the light reflection layer side A light-scattering layer that scatters light incident on the element sheet on the front side of the light-reflecting layer, and the light-transmitting portion of the light-shielding pattern has a refractive index lower than the refractive index of the optical element sheet The light shielding part of the light shielding pattern is a method for producing an optical sheet made of a light reflective material,
The light shielding is performed on the surface of the optical element sheet after the formation of the plurality of optical elements or the sheet surface opposite to the surface on which the plurality of optical elements are formed in the optical element sheet before the formation of the plurality of optical elements. A first pattern layer forming step of forming a first pattern layer by patterning a first pattern layer forming material that forms one of a light transmitting portion and a light shielding portion of a pattern with a constant thickness;
A second pattern layer forming material that forms either the light transmitting part or the light shielding part of the light shielding pattern on the sheet surface on which the first pattern layer is formed, at least to a height that covers the first pattern layer. Applying a second pattern layer forming material application step;
A second pattern layer thickness adjusting step of leveling the second pattern layer forming material applied in the second pattern layer application step to the same height as the first pattern layer;
And a light scattering layer bonding step of bonding a light scattering layer to the upper surfaces of the first and second pattern layers after the second pattern layer layer thickness adjusting step via a bonding layer. .

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