JP5027969B2 - Manufacturing method of two-dimensional field expansion member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a two-dimensional viewing angle widening memberManufacturing methodAbout.
[0002]
[Prior art]
In a liquid crystal display device or the like, a device using a light diffusion sheet on the viewer side of a liquid crystal panel is known in order to improve the visibility of the viewer. This light diffusing sheet is, for example, a surface of a translucent film that has been subjected to uneven treatment, a resin film containing light diffusing fine particles inside, and a lenticular in which cylindrical lenses are arranged in parallel on one plane. There is a lens sheet. In addition, two or three of these sheets are used in combination. These are made visible by diffracting image light in multiple directions at the boundary using the difference in refractive index of film, air, fine particles, etc., and diffusing the image light over a wide range and emitting it to the viewer side. It is intended to improve.
[0003]
[Problems to be solved by the invention]
However, the surface of the sheet on which light diffusing fine particles and irregularities are formed causes image light to be irregularly reflected to generate a lot of stray light, resulting in a decrease in surface brightness and contrast of the display. In addition, those having diffusibility due to the surface unevenness treatment have a problem that the visibility varies depending on the angle at which the display is viewed because the diffusivity and transparency have angle dependency. On the other hand, the light diffusibility of the light diffusing sheet also leads to an increase in scattering and reflection of external light, and there is a problem in that the contrast is remarkably lowered and the image is easily blurred. When a single light diffusing sheet is used alone, there is a problem in that the viewing angle in either the horizontal or vertical direction is not sufficiently expanded.
[0004]
  Accordingly, the present invention provides a two-dimensional viewing angle widening member that does not decrease surface brightness or contrast due to stray light, has little angle dependency, and has little scattering and reflection of external light.How to manufactureThe purpose is to provide.
[0005]
[Means for Solving the Problems]
The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.
[0006]
  The invention of claim 1The first mold roll (10) has a plurality of grooves extending along the rotation axis direction on the outer peripheral surface, and the plurality of grooves extending along the rotation axis direction have shapes corresponding to the plurality of unit lenses. Filling the plurality of grooves of the first-type roll with a high-refractive-index substance before curing and curing the high-refractive-index substance; and supplying a transparent resin before curing to the outer periphery of the first-type roll; A step of superposing one surface of the base sheet on the transparent resin and then curing the transparent resin, and obtaining an intermediate product that is a laminate of a plurality of unit lenses, the transparent resin, and the base sheet. The roll (21) has a plurality of grooves extending along the circumferential direction on the outer peripheral surface, and the plurality of grooves extending along the circumferential direction have a shape corresponding to a plurality of inter-lens portions, and the second mold Low hardness before hardening with black particles mixed in multiple grooves of the roll A step of filling the refractive index material to cure the low refractive index material, a step of supplying another transparent resin before curing to the outer periphery of the second type roll, and another step supplied to the outer periphery of the second type roll After the other surface of the base sheet of the intermediate product is overlapped with the transparent resin so that the direction in which the groove of the second mold roll extends by 90 ° with respect to the direction in which the unit lens extends, it is supplied to the outer periphery of the second mold roll. Curing the other transparent resin, and in addition to the intermediate product, the intermediate product is a laminate having another transparent resin and a plurality of inter-lens portions laminated on the other surface of the base sheet of the intermediate product. A product sheet is obtained, and the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles between a plurality of unit lenses. Filling material sheet and intermediate product sheet Curing the low-refractive index material and the high-refractive index material.
[0007]
  ThisManufactured byAccording to the two-dimensional viewing angle widening member, the light diffusion sheet isThe direction in which the unit lens extends isAbout 90°Therefore, horizontal and vertical diffusion can be realized simultaneously.
[0008]
  The invention according to claim 2 is the two-dimensional visual field enlarging member according to claim 1Manufacturing methodInA step of filling a low refractive index material before curing mixed with black particles between a plurality of unit lenses of an intermediate product sheet, and a high refractive index material between portions of the intermediate product sheet between a plurality of lenses. Then, there is an intermediate between the first mirror roll (29) in which the low-refractive-index material before curing containing black particles is supplied to the surface and the second mirror roll (30) in which the high-refractive-index material is supplied to the surface. Insert the product sheet so that it is sandwiched, and the unit lens of the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles from the first mirror roll. A high refractive index material is filled between the intermediate portions from the second mirror roll.
[0009]
According to a third aspect of the present invention, the first die roll has a plurality of grooves extending along the rotation axis direction on the outer peripheral surface, and the plurality of grooves extending along the rotation axis direction correspond to a plurality of inter-lens portions. Filling a plurality of grooves of the first mold roll with a low refractive index material before curing mixed with black particles and curing the low refractive index substance; and on the outer periphery of the first mold roll A laminate of a plurality of inter-lens portions, a transparent resin, and a base sheet comprising: a step of supplying a transparent resin before curing; and a step of superposing one surface of the base sheet on the transparent resin and then curing the transparent resin. The second mold roll has a plurality of grooves extending along the circumferential direction on the outer peripheral surface, and the plurality of grooves extending along the circumferential direction correspond to a plurality of unit lenses. In the plurality of grooves of the second type roll, before curing Filling the high refractive index material and curing the high refractive index material, supplying another transparent resin before curing to the outer periphery of the second type roll, and the other supplied to the outer periphery of the second type roll On the outer periphery of the second mold roll, the other surface of the base sheet of the intermediate product is overlaid on the transparent resin so that the direction in which the groove of the second mold roll extends by 90 ° relative to the direction in which the portion between the lenses extends. Curing the supplied other transparent resin, in addition to the intermediate product, the laminate having another transparent resin and a plurality of unit lenses laminated on the other surface of the base sheet of the intermediate product An intermediate product sheet is obtained, and a low-refractive-index material before curing, in which black particles are mixed, is filled between the unit lenses of the intermediate product sheet. Step of filling refractive index material and intermediate product sheet And a step of curing the high refractive index material and the low refractive index material filled in the two-dimensional field expanding member.
[0010]
  Claim4The invention of4. The method of manufacturing a two-dimensional visual field enlarging member according to claim 3, wherein a plurality of intermediate product sheets are filled with a low refractive index material before curing mixed with black particles between a plurality of unit lenses of the intermediate product sheet. In the process of filling the high refractive index material between the lens parts, the first mirror roll in which the high refractive index material before curing is supplied to the surface and the low refractive index material in which black particles are mixed are supplied to the surface. The intermediate product sheet is inserted between the second mirror rolls, and the intermediate product sheet is filled with a high refractive index material before curing from the first mirror roll between the plurality of inter-lens portions. A plurality of unit lenses of the intermediate product sheet is filled with a low refractive index material mixed with black particles from the second mirror roll.
[0052]
Such an operation and gain of the present invention will be clarified from the embodiments described below.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on embodiments shown in the drawings. FIG. 1 shows a configuration of a display device of the present invention. In FIG. 1, the lower left direction on the front side of the paper is the observer side, and the upper right direction on the back side of the paper is the video light source side. The display device of the present invention, in order from the observer side, a functional sheet 101 having at least one function of antireflection, hard coat, polarizing filter, antistatic, antiglare treatment, antifouling treatment, touch sensor, A light diffusion sheet 102 in which unit lenses are arranged in a vertical direction, a light diffusion sheet 103 in which unit lenses are arranged in a horizontal direction, a Fresnel lens 104, and a liquid crystal display (hereinafter referred to as “LCD”) panel 105 are provided. I have. Note that the arrangement of the light diffusion sheet 102 and the light diffusion sheet 103 may be interchanged. In FIG. 1, they are shown separated from each other, but this is for the understanding of the drawings, and in fact they are in contact with each other or bonded together.
[0054]
In the present invention, the “two-dimensional viewing angle enlarging member” has a combination of two light diffusion sheets 102 and 103 as the core of the structure, but as shown in FIG. 101 or the Fresnel lens 104 or the like on the light incident side is a concept including the functional sheet 101 and the Fresnel lens 104.
[0055]
2 and 3 show horizontal sections of the light diffusion sheets S1 and S2 of the first and second embodiments constituting the two-dimensional viewing angle widening member of the present invention. In these drawings, an image light source, for example, an LCD panel is arranged on the right side of the drawing, and an observer is located on the left side of the drawing. The two-dimensional viewing angle enlarging member of the present invention may be configured by combining two light diffusing sheets S1 of the first embodiment or two of the light diffusing sheets S2 of the second embodiment with phases shifted by approximately 90 °. The light diffusing sheet S1 of the first embodiment and the light diffusing sheet S2 of the second embodiment can also be configured with a phase shifted by approximately 90 °.
[0056]
FIG. 2 shows the light diffusion sheet S1 of the first embodiment. In this light diffusion sheet S1, a sheet 1 containing a diffusing agent, a unit lens 2, and a base sheet 3 are arranged in order from the observer side in the direction of the image light source. The unit lens 2 is made of a material having a high refractive index N1. Furthermore, a transparent triangular substance having a refractive index N2 smaller than N1 (hereinafter referred to as “the inter-lens portion 7”) between the adjacent unit lenses 2 and 2 is a triangular section (hereinafter referred to as “inter-lens portion 7”). The transparent low-refractive-index substance 6 ") is filled with a material to which light-absorbing particles 5 are added.
[0057]
In the present embodiment, the ratio between the refractive index N1 of the high refractive index portion 2 and the refractive index N2 of the transparent low refractive index substance 6 is set within a predetermined range in order to obtain the optical characteristics of the light diffusion sheet S1. Yes. Further, the angle between the oblique side where the inter-lens portion 7 and the high refractive index portion 2 are in contact with the normal line of the light exit surface (parallel to the perpendicular incident light with respect to the light diffusion sheet S1) is formed at a predetermined angle θ. ing.
[0058]
The high refractive index portion 2 is usually made of a material such as an epoxy acrylate having ionizing radiation curability. Further, as the transparent low refractive index substance 6, a material such as urethane acrylate having ionizing radiation curability is usually used. Commercially available colored resin fine particles can be used as the light absorbing particles 5. Further, the diffusing agent-containing sheet 1 and the base sheet 3 are made of a material having substantially the same refractive index as that of the high refractive index portion 2. Functional layers such as an antireflection layer, a hard coat layer, a polarizing filter layer, an antistatic layer, an antiglare treatment layer, an antifouling treatment layer, and a touch sensor layer are appropriately provided on the viewer side of the sheet 1 containing the diffusing agent. Yes.
[0059]
Next, the optical path of the light entering the unit lens 2 of the light diffusion sheet S1 will be described with reference to FIG. In FIG. 2, the optical paths of the lights L1 to L4 are schematically shown. In FIG. 2, the vertical light L1 incident near the center of the unit lens 2 from the image light source side passes straight through the light diffusion sheet S1 and reaches the observer. The vertical light L2 incident on the vicinity of the end of the unit lens 2 from the image light source side is totally reflected on the hypotenuse due to the refractive index difference between the high refractive index portion 2 and the transparent low refractive index material 6, and is observed at a predetermined angle. Light emitted to the side. The light L3 incident at an angle near the end of the unit lens 2 from the image light source side is totally reflected on the hypotenuse and emitted to the observer side at a larger angle in the opposite direction to that at the time of incidence. The stray light L4a incident on the oblique side with a large angle of a predetermined value or more enters the inter-lens portion 7 without being reflected by the refractive index difference between the high refractive index portion 2 and the low refractive index material 6, It is absorbed by the absorbent particles 5 and does not reach the observer side. Moreover, since the stray light L4b that has entered the inter-lens portion 7 from the viewer side is absorbed by the light absorbing particles, it is reflected on the viewer side and is not emitted. In this way, the light diffusion sheet S1 having a wide viewing angle in the horizontal direction and high contrast and brightness can be obtained.
[0060]
FIG. 3 shows the light diffusion sheet S2 of the second embodiment. The light diffusing sheet S2 is also arranged by adhering the diffusing agent-containing sheet 1, the unit lens 2, and the base sheet 3 in order from the observer side to the image light source direction. The unit lens 2 is made of a material having a high refractive index N1. Further, a layer 4 (hereinafter referred to as “transparent low refractive index layer 4”) made of a transparent material having a refractive index N2 smaller than N1 is formed on the hypotenuse of the adjacent unit lenses 2, 2. . Further, the triangular section between the adjacent unit lenses 2 is filled with a material in which the light absorbing particles 5 are added in the substance 8 having a refractive index higher than N2. In the following description, this triangular section is referred to as “inter-lens portion 9”.
[0061]
The ratio between the refractive index N1 of the high refractive index portion 2 and the refractive index N2 of the transparent low refractive index layer 4 is set to a predetermined range in order to obtain the optical characteristics of the light diffusion sheet S2. In addition, the angle between the oblique side where the transparent low refractive index layer 4 and the high refractive index portion 2 are in contact with the normal line of the light exit surface (parallel to the perpendicular incident light with respect to the light diffusion sheet S2) is a predetermined angle θ. Is formed. These will be described in detail later.
[0062]
The high refractive index portion 2 is usually made of a material such as an epoxy acrylate having ionizing radiation curability. The transparent low refractive index layer 4 is formed of a material having a refractive index lower than that of a transparent resin such as silica. Commercially available colored resin fine particles can be used as the light absorbing particles 5. Further, the diffusing agent-containing sheet 1 and the base sheet 3 are made of a material having substantially the same refractive index as that of the high refractive index portion 2. Functional layers such as an antireflection layer, a hard coat layer, a polarizing filter layer, an antistatic layer, an antiglare treatment layer, an antifouling treatment layer, and a touch sensor layer are appropriately provided on the viewer side of the sheet 1 containing the diffusing agent. Yes.
[0063]
Next, the optical path of light entering the unit lens 2 of the light diffusion sheet S2 will be described with reference to FIG. In FIG. 3, the optical paths of the lights L1 to L4 are schematically shown. In FIG. 3, the vertical light L1 incident on the vicinity of the central portion of the unit lens 2 from the image light source side passes straight through the light diffusion sheet S2 as it is and reaches the observer.
[0064]
The vertical light L2 incident on the vicinity of the end of the unit lens 2 from the image light source side is totally reflected on the hypotenuse due to the refractive index difference between the high refractive index portion 2 and the transparent low refractive index layer 4, and is observed at a predetermined angle. Light emitted to the side. The light L3 incident at an angle near the end of the unit lens 2 from the image light source side is totally reflected on the hypotenuse and emitted to the observer side at a larger angle in the opposite direction to that at the time of incidence. The stray light L4a incident on the oblique side with a predetermined angle or more enters the inside of the transparent low refractive index layer 4 without being reflected by the refractive index difference between the high refractive index portion 2 and the transparent low refractive index layer 4. . The stray light L4a is absorbed by the light absorbing particles 5 in the inter-lens portion 9 and does not reach the observer side. Further, the stray light L4b that has entered the inter-lens portion 9 from the observer side is also absorbed by the light absorbing particles 5 and becomes reflected light on the observer side and is not emitted. In this way, the light diffusion sheet S2 having a wide viewing angle in the horizontal direction and high contrast and brightness can be obtained.
[0065]
Next, referring to FIG. 4 and FIG. 5, the light in the light diffusion sheet incident on the unit lens portion of each light diffusion sheet is totally reflected at the hypotenuse and is not totally reflected at the light exit surface. The conditions that pass through to the viewer will be described.
[0066]
FIG. 4 is a diagram illustrating an optical path when the vertical light L5 is incident on the oblique side of the light diffusion sheet S2 of the second embodiment in the light diffusion sheet. In FIG. 4, it is assumed that the image light source is located above the drawing and the observer is located below the drawing. Further, the diffusing agent-containing sheet 1 and the base sheet 3 are omitted for simplification of description (the same applies to FIGS. 5 and 6 below).
[0067]
In FIG. 4, the condition (critical condition) where the vertical light L5 incident on the hypotenuse starts to be totally reflected at the point A of the hypotenuse is Snell's law.
sin (90 ° −θ) = N2 / N1
Therefore, in order that the vertical light L5 is always totally reflected,
(Formula 1) sin (90 ° −θ)> N2 / N1
It is necessary to satisfy the condition.
[0068]
Further, the condition (critical condition) where the light L5 reflected at the point A on the oblique side starts to be totally reflected at the point B on the light exit surface is as follows: when the refractive index of the atmosphere is 1, sin 2θ = 1. / N1
Therefore, in order for the light L5 to be reliably emitted from the point B to the observer side,
(Formula 2) sin2θ <1 / N1
It is necessary to satisfy the condition.
[0069]
For reference, the optical path when light L6 in the light diffusion sheet having an inclination of 10 ° is incident on the oblique side of the light diffusion sheet S2 will be briefly described below with reference to FIG.
[0070]
In FIG. 5, the condition (critical condition) in which the light L6 having an inclination of 10 ° incident on the hypotenuse in the light diffusion sheet starts to be totally reflected at the point A of the hypotenuse is Snell's law.
sin (80 ° −θ) = N2 / N1
Therefore, in order for the light L6 having an inclination of 10 ° to be always totally reflected,
(Formula 3) sin (80 ° −θ)> N2 / N1
It is necessary to satisfy the condition.
[0071]
Further, the condition (critical condition) where the light L6 reflected at the point A on the oblique side begins to be totally reflected at the point B on the light exit surface is defined as sin (2θ + 10) according to Snell's law when the refractive index of the atmosphere is 1. °) = 1 / N1
Therefore, in order for the light L6 to be reliably emitted from the point B to the observer side,
sin (2θ + 10 °) <1 / N1
Ie
(Formula 4) N1 <1 / sin (2θ + 10 °)
It is necessary to satisfy the condition.
[0072]
Next, with reference to FIG. 6, a description will be given of conditions under which light reflected by the oblique sides of the light diffusion sheet S2 does not reach the adjacent oblique sides. In order to find this condition, the incident light L7 having the largest angle (practically 10 °) with respect to the light exit surface normal is a point C on the hypotenuse near the apex of the triangle formed by the low refractive index portion 4. When the light is totally reflected at, the relationship between the height H of the triangle and the length T of the upper base of the unit lens may be determined so that the reflected light does not reach the adjacent hypotenuse.
[0073]
In FIG. 6, if the length of the base of the triangle is 2S,
tan θ = S / H
tan (2θ + 10 °) = (S + T) / H
Therefore,
H = T / (tan (2θ + 10 °) −tan θ)
If H is smaller than the above value, the reflected light does not reach the adjacent hypotenuse. Therefore, the condition is
(Formula 5) H <T / (tan (2θ + 10 °) −tan θ)
It is represented by
[0074]
Next, assuming that θ is 5 ° to 15 °, the values of N1 and N2 will be considered more specifically in that range. In the range of 5 ° <θ <15 °,
sin (90 ° −θ) <0.996
And according to Equation 1, the value of N2 / N1 is smaller than this
(Formula 6) N2 / N1 <0.996
On the other hand, in the range of 5 ° <θ <15 °,
1 / sin2θ <5.76
Therefore, from Equation 2,
(Formula 7) N1 <5.76
Furthermore, when considering the actual material available, the minimum value of N2 is 1.30,
N2 / N1> 1.30 / 5.76 = 0.23
Therefore, from the above formula and formula 6,
(Formula 8) 0.23 <N2 / N1 <0.996
The above formulas 7 and 8 are the conditions that the values of N1 and N2 can take in the range of 5 ° <θ <15 °.
[0075]
In Equation 5, the condition for H is determined when θ = 15 °.
H <T / 0.57
It becomes.
[0076]
FIG. 7 is a diagram showing various aspects of the shape of the inter-lens portion 7 or 9 of each light diffusion sheet constituting the two-dimensional viewing angle widening member of the present invention. The inter-lens portion 7 or 9 is based on a substantially triangular shape formed by the hypotenuses of two adjacent unit lenses 2 and 2. FIG. 7A shows a case where the hypotenuse is formed by a straight line. In this case, the angle θ1 formed by the hypotenuse and the light exit surface normal is constant at any point on the hypotenuse. FIG. 7B shows a case where the hypotenuse is formed by a smooth curve. FIG. 7C shows a case where the hypotenuse is composed of two straight lines. In these cases, the angle θ2 or θ3 or θ4 formed by the hypotenuse and the light exit surface normal line varies depending on the position on the hypotenuse. In the present invention, when the angle formed between the hypotenuse and the light exit surface normal is not constant as in FIGS. 7B and 7C, the formula described above is used for 90% or more of the hypotenuse length. The effect of this invention can be acquired if each conditions of 1-8 are satisfy | filled.
[0077]
8 and 9 are diagrams showing an example of the configuration of the light diffusion sheet S2 of the second embodiment. The light diffusion sheet shown in FIG. 8 includes a unit lens 2 whose horizontal cross-sectional shape is constant in the vertical direction. Between the adjacent unit lenses 2 and 2, a resin material 8 to which light absorbing particles 5 are added is filled in the inter-lens portion 9 through the transparent low refractive index layer 4. A diffusing agent-containing sheet 1 is disposed on the light exit surface side, and a base sheet 3 is disposed on the light entrance surface side. In the drawing, these three are shown apart for the sake of understanding, but they are actually bonded together.
[0078]
On the other hand, in the light diffusion sheet shown in FIG. 9, the semi-conical unit lenses are two-dimensionally arranged on the vertical plane. The top flat surface of the semi-mounted cone of each unit lens is formed on the same surface, and the sheet 1 containing a diffusing agent is bonded to this flat surface. A gap between adjacent unit lenses 2 and 2 is filled with a resin material 8 to which light absorbing particles 5 are added in an inter-lens portion 9 through a transparent low refractive index layer 4. The effect of the two-dimensional viewing angle widening member of the present invention can be obtained by the configuration of the light diffusion sheet shown in either FIG. 8 or FIG.
[0079]
FIG. 10 is a diagram illustrating an example in which the light exit surface of the unit lens 2 (portion corresponding to the upper base of the cross-sectional shape trapezoid) is formed convex toward the viewer side in the light diffusion sheet S2 of the second embodiment. . By adopting such a configuration, in the manufacturing process, when the step of forming the portion of the unit lens 2 first and then filling the material 8 with the light absorbing particles 5 added to the inter-lens portion 9 is taken, The light absorbing particles 5 remaining on the light exit surface can be completely removed.
[0080]
Next, the manufacturing method of the two-dimensional viewing angle widening member of this embodiment is demonstrated, referring FIGS. FIG. 11 shows a method for manufacturing a two-dimensional viewing angle widening member in which two light diffusion sheets S1 of the first embodiment are combined.
[0081]
The manufacturing apparatus used in this manufacturing method includes a first mold roll 10, a second mold roll 21, a first mirror roll 29, a second mirror roll 30, a base film supply roll 16, and an auxiliary roll group 19. , 20, 27, 28, 34, 37, feeders 12, 15, 25, 31, 32 for supplying ionizing radiation curable resin, ionizing radiation irradiators 14, 18, 24, 26, 35, 36, doctors Blades 13, 23, and 33 are provided.
[0082]
In the apparatus for manufacturing a two-dimensional viewing angle widening member in FIG. 11, a female die corresponding to a trapezoidal cross-sectional portion constituting the unit lens 2 is provided on the surface of the first die roll 10 that rotates at a predetermined speed. Carved in the direction. FIG. 12A shows a vertical cross-sectional shape of the roll surface portion of the first mold roll 10.
[0083]
A high refractive index resin heated to a predetermined temperature is supplied from the resin feeder 12 onto the first mold roll 10 and filled into a trapezoidal recess. After surplus resin is scraped off by the doctor blade 13, ionizing radiation is irradiated onto the roll surface by the ionizing radiation irradiator 14, the high refractive index resin is cured, and a unit lens is formed. Next, a transparent resin is supplied from the feeder 15 over almost the entire length of the roll width, and a transparent resin layer is formed on the surface of the first mold roll 10. Further, after the base film 17 is unwound from the supply roll 16 and formed on the upper surface thereof, the ionizing radiation irradiator 18 irradiates the ionizing radiation again to cure the transparent resin. Then, it is folded by the auxiliary roll 19 and further supplied from the auxiliary roll 20 to the second mold roll 21.
[0084]
By the folding process with the auxiliary roll 19, the trapezoidal unit lens having a cross-sectional shape formed in the concave surface of the first mold roll 10 is peeled off from the roll surface. At this time, as shown in the enlarged view of point E in FIG. 13A, a transparent resin layer is formed on the base film, and a unit lens having a trapezoidal cross section is formed on the upper surface of the transparent resin layer. It is made of resin.
[0085]
On the outer peripheral surface of the roll of the second die roll 21, a female die corresponding to the triangular section of the inter-lens portion 7 is carved in the circumferential direction of the roll. FIG. 12B shows the horizontal cross-sectional shape of the roll surface portion of the second mold roll 21.
[0086]
In FIG. 11 again, a low refractive index resin heated to a predetermined temperature and mixed with black particles is supplied from the resin feeder 22 onto the second mold roll 21 and filled into a concave portion having a triangular cross-sectional shape on the roll surface. After surplus resin is scraped off by the doctor blade 23, ionizing radiation is irradiated onto the roll surface by the ionizing radiation irradiator 24 to cure the low refractive index resin mixed with black particles. Next, a transparent resin is supplied from the feeder 25 over almost the entire length of the roll width to form a transparent resin layer on the surface of the second mold roll 21.
[0087]
The transparent resin layer is sent to the rotation of the roll and is pressure-bonded to the lower surface side of the intermediate product sent from the auxiliary roll 20. Then, ionizing radiation is again irradiated by the ionizing radiation irradiator 26 to cure the transparent resin. Further, the sheet is folded by the auxiliary roll 27 and sent from the auxiliary roll 28 to the mirror rolls 29 and 30. Through the folding process with the auxiliary roll 27, the black particle-mixed low refractive index resin having a triangular cross-section formed in the concave surface of the second mold roll 21 is peeled off from the roll surface. At this point, as shown in the enlarged view of point F in FIG. 13 (b), a transparent resin layer is formed on the lower surface of the intermediate product at point E, and the lower refractive index resin mixed with black particles is cross-sectioned further below it. It is formed in a triangular shape.
[0088]
The two mirror rolls 29 and 30 are arranged so as to form a slight predetermined gap. The first mirror roll 29 is rotated counterclockwise and the second mirror roll 30 is rotated clockwise at the same predetermined speed. Has been.
[0089]
In the first mirror roll 29, the low refractive index resin mixed with black particles is supplied in advance from the feeder 31 to the roll surface, and the roll is rotated to form a layer on the surface of the mirror roll 29 in a soft state before curing. . The low refractive index resin mixed with black particles forming this layer is a valley between the high refractive index resins constituting the unit lens on the uppermost surface of the F point enlarged view shown in FIG. The part should be filled.
[0090]
On the other hand, in the second mirror roll 30, a high refractive index resin is supplied in advance from the feeder 32 to the roll surface, and a layer is formed on the surface of the mirror roll 30 in a soft state before curing by rotation of the roll. The high refractive index resin forming this layer is a section of a trapezoidal trapezoidal valley between the low refractive index resins mixed with black particles having a triangular cross section on the bottom surface of the F point enlarged view shown in FIG. Should be filled.
[0091]
These layers are pressure-bonded to both surfaces of the intermediate product sheet sent from the auxiliary roll 28 so as to be sandwiched between the mirror rolls 29 and 30. The soft black particle-mixed low refractive index resin on the first mirror roll 29 enters the gap between the valleys of the cross-sectional triangle between the cross-sectional trapezoidal unit lenses formed of the high refractive index resin without pressure. . Moreover, the soft high refractive index resin on the second mirror roll 30 enters the trapezoidal portion of the valley of the cross-sectional triangular valley formed of the black particle mixed low refractive index resin by pressure bonding without any gap. Further, the black particle mixed low refractive index resin filled between the unit lenses on the left side of the drawing is scraped off by the doctor blade 33 from the portion that should become the lens light exit surface.
[0092]
Further, ionizing radiation is irradiated by ionizing radiation irradiators 35 and 36 from both sides of the sheet until reaching the auxiliary roll 37 to cure the low refractive index resin and high refractive index resin mixed with black particles on both sides of the sheet. Let Then, the sheet passes through the auxiliary roll 37 and is wound around the winder 38. At this time, as shown in the enlarged view of point G in FIG. 13C, the two light diffusion sheets are formed so that the unit lenses are orthogonal to the upper and lower surfaces of the base film.
[0093]
In addition, although the said process forms the unit lens 2 of a cross-sectional trapezoid shape with the 1st type | mold roll 10, it forms the cross-section triangular inter-lens part 7 with the 1st type | mold roll 10, and a 2nd type | mold. A unit lens may be formed by the roll 21.
[0094]
【Example】
Epoxy acrylate as the material for the high refractive index part 2 (trapezoidal part) constituting the unit lens, urethane acrylate as the transparent low refractive index resin for the part 7 between the lenses, and “Love Collol” manufactured by Dainichi Seika Co., Ltd. (Registered trademark) was used.
[0095]
The average particle diameter of “Love Color” was 8 μm, and the amount added was 50 mass%.
[0096]
The refractive index of the high refractive index portion 2 was 1.57, and the refractive index of the inter-lens portion 7 was 1.45. The thus configured light diffusing sheet was arranged so that the lens forming directions were orthogonal, a Fresnel lens sheet was arranged between the LCD panel and a diffusing plate was arranged on the viewer side. The diffuser plate has an acrylic three-layer structure, and an intermediate layer mixed with a diffusing agent is used. The lens pitch of the high refractive index portion was 50 μm. In addition, the upper base length of the trapezoidal portion of the unit lens 2 is made equal to the length of the triangle base side of the low refractive index portion so that the so-called black stripe ratio is 50%. Further, the apex angle θ was set to 10 °.
[0097]
The thus configured two-dimensional viewing angle widening member had a transmittance of 80%, a reflectance of 5%, and a gain of 2. Further, the vertical viewing angle (half-value angle: the angle when the luminance when viewed from a certain direction is half that when viewed from the front) and the horizontal viewing angle (half-value angle) were 25 °.
[0099]
【The invention's effect】
As described above, two light diffusion sheets in which a plurality of unit lenses having a substantially trapezoidal cross-sectional shape are formed in a one-dimensional or two-dimensional direction are stacked with a phase shift of approximately 90 °, and each light diffusion sheet has a unit. According to the two-dimensional viewing angle widening member characterized in that the lens is formed with the lower base of the trapezoid as the light entrance part, the upper base as the light exit part, and the hypotenuse as the total reflection part. Therefore, the horizontal and vertical diffusion can be realized simultaneously.
[0100]
In addition, for each light diffusion sheet, the unit lens is formed of a high refractive index material, and the triangular portion between the adjacent unit lenses has a refractive index lower than the refractive index of the high refractive index material. In each light diffusing sheet, since the cross-sectional triangle portion has a lower refractive index than the unit lens portion, the incident light to the unit lens is totally reflected at the hypotenuse of the cross-sectional trapezoid shape where both contact each other. Can do.
[0101]
If light-absorbing particles are added to the low refractive index material, the entire triangular portion of the cross-sectional shape is not made a light-absorbing material in each light diffusion sheet. Since the particles are dispersed, total reflection at the hypotenuse is performed efficiently. Therefore, a two-dimensional viewing angle enlarging member with high brightness and contrast can be obtained. In addition, total reflection at the hypotenuse and light absorption at the cross-sectional triangle can be realized at a high level without being affected by the coloring density of the light absorbing material.
[0102]
If the amount of light absorbing particles added to the low refractive index substance is 10 to 60% by mass, the effect of adding light absorbing particles can be maximized. If the addition amount is smaller than this, the filling amount in the cross-sectional triangular portion is insufficient, the width of the so-called black stripe becomes narrow, and the contrast is deteriorated. Further, if it is added more than this, it becomes difficult to sufficiently mix with the medium material, and light absorbing particles remain at the bottom of the triangle at the time of production.
[0103]
Further, if the average particle diameter of the light absorbing particles is 1/30 to 2/3 of the length of the light emitting part forming the upper base of the cross-sectional shape trapezoid, the light absorbing effect is obtained in each light diffusion sheet. Can be made efficient. Moreover, it can be filled into the triangular section of the cross-sectional shape without any problem at the time of production.
[0104]
In addition, for each light diffusion sheet, the unit lens is formed of a high refractive index material, and the hypotenuse part constituting the total reflection portion is transparent and low by a low refractive index material having a refractive index lower than that of the high refractive index material. If the refractive index layer is formed, light incident on the unit lens can be totally reflected on the surface of the transparent low refractive index layer in each light diffusion sheet.
[0105]
If the thickness of the transparent low refractive index layer is 0.1 μm or more, total reflection by the transparent low refractive index layer can be ensured in each light diffusion sheet.
[0106]
In addition, when the high refractive index substance is filled in the triangular section between the transparent low refractive index layers, the external light reflectance can be reduced.
[0107]
Further, if a light absorption layer is further formed on the light exit direction side of the transparent low refractive index layer, in each light diffusion sheet, light incident with a predetermined inclination or more with respect to the light exit surface normal line. Part of the light is not totally reflected on the surface of the transparent low refractive index layer and is incident on the inside of the transparent low refractive index layer, but is absorbed by the light absorption layer. In addition, light incident on the portion other than the light exit surface from the viewer side is also absorbed by the light absorption layer. Therefore, it is possible to provide a two-dimensional viewing angle enlarging member that provides a clear screen with little stray light and reflected light.
[0108]
Furthermore, if the cross-sectional triangle portion sandwiched between the transparent low refractive index layers is filled with a colored substance, the light incident on the cross-sectional triangle portion from the observer side is colored. Since it is absorbed by the substance, the reflected light to the viewer side can be reduced. Further, even when incident light having a large angle passes through the transparent low refractive index layer from the unit lens side, it is prevented from being absorbed by the colored substance and emitted to the viewer side. Therefore, it is possible to provide a two-dimensional viewing angle enlarging member that provides a clear screen with little stray light and reflected light.
[0109]
Furthermore, the portion of the cross-sectional triangle sandwiched between the transparent low refractive index layers is filled with light absorbing particles added to a material having a refractive index higher than that of the material forming the transparent low refractive index layer. If so, in each light diffusion sheet, light incident on the cross-sectional triangular portion from the viewer side is absorbed by the light absorbing particles. Further, even when incident light having a large angle passes through the transparent low refractive index layer from the unit lens side, it is absorbed by the light absorbing particles. Therefore, it is possible to provide a two-dimensional viewing angle enlarging member that provides a clear screen with little stray light and reflected light.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a configuration of a two-dimensional viewing angle enlarging member.
FIG. 2 is a view showing a cross section of the light diffusion sheet of the first embodiment.
FIG. 3 is a view showing a cross section of a light diffusion sheet of a second embodiment.
FIG. 4 is a diagram showing an optical path when vertical light is incident on a light diffusion sheet.
FIG. 5 is a diagram showing an optical path when light having an inclination of 10 ° is incident on the light diffusive sheet.
FIG. 6 is a diagram illustrating an optical path when light having an inclination of 10 ° is incident on the light diffusing sheet near a vertex of a triangle formed by a low refractive index portion.
FIG. 7 is a diagram showing various aspects of the shape of a low refractive index portion.
FIG. 8 is a diagram illustrating an example of a configuration of a light diffusion sheet.
FIG. 9 is a diagram showing another example of the configuration of the light diffusion sheet.
FIG. 10 is a view showing a cross section of a modification of the light diffusion sheet of the second embodiment.
FIG. 11 is a diagram showing an example of a method for producing a light diffusion sheet of the first embodiment.
FIG. 12 is a view showing a first-type roll and a second-type roll.
13 is a diagram showing a cross section of the sheet at points E, F, and G in FIG.
[Explanation of symbols]
S1 Light diffusion sheet
S2 Light diffusion sheet
1 Sheet with diffusion agent
3 Base sheet (transparent substrate)
4 Transparent low refractive index layer
5 Light absorbing particles
6 Low refractive index resin
7 Inter-lens part
8 High refractive index resin
9 Inter-lens part

Claims (4)

The first-type roll has a plurality of grooves extending along the rotation axis direction on the outer peripheral surface, and the plurality of grooves extending along the rotation axis direction have shapes corresponding to a plurality of unit lenses, Filling the plurality of grooves of the one-type roll with a high refractive index material before curing, and curing the high refractive index material;
Supplying a transparent resin before curing to the outer periphery of the first mold roll;
Curing the transparent resin after superimposing one surface of the base sheet on the transparent resin;
Obtaining an intermediate product that is a laminate of the plurality of unit lenses, the transparent resin, and the base sheet,
The second mold roll has a plurality of grooves extending along the circumferential direction on the outer peripheral surface, and the plurality of grooves extending along the circumferential direction have a shape corresponding to a plurality of inter-lens portions, Filling the plurality of grooves of the mold roll with a low refractive index material before curing mixed with black particles, and curing the low refractive index material;
Supplying another transparent resin before curing to the outer periphery of the second mold roll;
The base sheet of the intermediate product so that the direction in which the groove of the second mold roll extends by 90 ° is shifted from the direction in which the unit lens extends in the other transparent resin supplied to the outer periphery of the second mold roll. Curing the other transparent resin supplied to the outer periphery of the second mold roll after overlapping the other surface of
In addition to the intermediate product, an intermediate product sheet that is a laminate having the other transparent resin and the plurality of inter-lens portions laminated on the other surface of the base sheet of the intermediate product is obtained,
  Between the plurality of unit lenses of the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles, and between the plurality of inter lens portions of the intermediate product sheet is a high refractive index material. Filling with
Curing the low-refractive index substance and the high-refractive index substance filled in the intermediate product sheet.   Between the plurality of unit lenses of the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles, and between the plurality of inter lens portions of the intermediate product sheet is a high refractive index material. In the process of filling
  The intermediate product sheet is sandwiched between a first mirror roll supplied with a low-refractive-index material before curing mixed with the black particles and a second mirror roll supplied with the high-refractive-index material on the surface. Between the plurality of unit lenses of the intermediate product sheet is filled with the low refractive index material before curing mixed with the black particles from the first mirror roll, a plurality of the intermediate product sheet The method for manufacturing a two-dimensional visual field enlarging member according to claim 1, wherein the high refractive index substance is filled from the second mirror roll between the inter-lens portions. The first mold roll has a plurality of grooves extending along the rotation axis direction on the outer peripheral surface, and the plurality of grooves extending along the rotation axis direction has a shape corresponding to a plurality of inter-lens portions, Filling the plurality of grooves of the first-type roll with a low refractive index material before curing mixed with black particles, and curing the low refractive index material;
Supplying a transparent resin before curing to the outer periphery of the first mold roll;
Curing the transparent resin after superimposing one surface of the base sheet on the transparent resin;
An intermediate product that is a laminate of the plurality of inter-lens portions, the transparent resin, and the base sheet,
The second die roll has a plurality of grooves extending along the circumferential direction on the outer peripheral surface, and the plurality of grooves extending along the circumferential direction have shapes corresponding to a plurality of unit lenses, Filling the plurality of grooves of the roll with a high refractive index material before curing, and curing the high refractive index material;
Supplying another transparent resin before curing to the outer periphery of the second mold roll;
The base of the intermediate product is arranged such that the direction in which the groove of the second mold roll extends 90 ° with respect to the direction in which the portion between the lenses extends in the other transparent resin supplied to the outer periphery of the second mold roll. Curing the other transparent resin supplied to the outer periphery of the second mold roll after overlapping the other surface of the sheet;
In addition to the intermediate product, the intermediate product sheet that is a laminate having the other transparent resin and the plurality of unit lenses laminated on the other surface of the base sheet of the intermediate product,
  Between the plurality of unit lenses of the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles, and between the plurality of inter lens portions of the intermediate product sheet is a high refractive index material. Filling with
Curing the low-refractive index substance and the high-refractive index substance filled in the intermediate product sheet.   Between the plurality of unit lenses of the intermediate product sheet is filled with a low refractive index material before curing mixed with black particles, and between the plurality of inter lens portions of the intermediate product sheet is a high refractive index material. In the process of filling
  The intermediate product sheet is placed between a first mirror roll having a high refractive index material before the curing supplied to the surface and a second mirror roll having the low refractive index material mixed with the black particles supplied to the surface. Between the plurality of inter-lens portions of the intermediate product sheet, the high refractive index material before curing is filled from the first mirror roll, and the plurality of unit lenses of the intermediate product sheet are inserted. The method for manufacturing a two-dimensional field enlarging member according to claim 3, wherein the low refractive index substance mixed with the black particles is filled from the second mirror roll.

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