JP2000056105A - Directional light diffusing film, its manufacture and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an image from blurring in a light diffusing film without deteriorating a light diffusing function. SOLUTION: A directional light diffusing film 10 is constructed by arranging fine transparent regions 14 for transmitting a light beam and fine light diffusing regions 16 for diffusing an emitting light beam alternately in one- or two-dimensional directions along a film surface on the surface of a transparent substrate film 12. An emitting light beam passing through the light diffusing regions 16 is diffused, and an emitting light passing through the transparent regions 14 advances straight as it is. In the case the film is attached to a light-emitting surface of a liquid crystal display or the like, quantity of an emitting light beam the front direction to reach to eyes without being diffused is increased to prevent an image from blurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device,
A directional light diffusion film attached to the display surface of a plasma display device or the like to prevent a reduction in front luminance and parallax,
The present invention relates to a method for manufacturing the same and a display device using the directional light diffusion film.

[0002]

2. Description of the Related Art Conventionally, in a display device such as the above, for example, a reflection type liquid crystal display device, a light diffusing film is mounted on the display surface in order to prevent a reduction in excessive luminance in a front direction and a parallax. I have.

The light diffusing film is made of, for example, a resin sheet (film) containing a light diffusing agent and having irregularities on the surface, or a resin sheet provided with a light diffusing layer containing a light diffusing agent and having irregularities on the surface. The light emitted from the display surface is diffused.

Among the light diffusion films, those having a light diffusion layer containing a light diffusion agent on a resin sheet and having irregularities on the surface have very small surface irregularities, and are mainly diffused by internal diffusion in the light diffusion layer. There is also a light diffusion film utilizing the action.

[0005] Further, since a lens film has the same function as a light diffusion film, it may be used for a light diffusion film.

A louver film is similar to the lens film and the light diffusion film.
This louver film absorbs oblique external light and is effective in improving the contrast in the front direction.

[0007]

The light diffusion film and the lens film as described above can improve the front luminance and the parallax by diffusing the transmitted light, but the light diffusion effect also reduces the scattering and reflection of external light. There is a problem that the contrast is remarkably reduced due to an increase, and an image formed by pixels on the display surface is easily blurred.

A light diffusion film mainly using internal diffusion can reduce the degree of external light reflection as compared with a normal light diffusion film. On the other hand, there is a problem that the diffusion of the image light becomes large and the blur of the image becomes larger than that of a normal light diffusion film.

On the other hand, the louver film as described above absorbs oblique external light and is effective in improving the contrast in the front direction, but has no effect of diffusing transmitted light, so that front luminance and parallax are improved. There is a problem that can not be.

The present invention has been made in view of the above-mentioned conventional problems, and is capable of improving image blur without lowering excessive front luminance due to light diffusion and impairing a parallax preventing function. It is an object of the present invention to provide a directional light diffusion film, a method for manufacturing the same, and a display device using the directional light diffusion film.

[0011]

SUMMARY OF THE INVENTION The present invention provides a transparent base film having a fine transparent region transmitting light in the thickness direction and a fine light diffusion region diffusing light transmitting in the thickness direction. The above object is achieved by forming a directional light diffusing film by alternately arranging it in one-dimensional or two-dimensional directions without gaps along at least one of the front surface and the back surface.

[0012] The light diffusion region may have a polygonal cross section orthogonal to the front surface or the back surface.

[0013] In the directional light diffusion film,
The light diffusion region and the transparent region may be configured in a parallel linear band shape alternately arranged.

Further, the light diffusion region may be formed by including a light diffusing agent in a translucent resin.

Further, a boundary between the light diffusion region and the transparent region may be an uneven surface on which fine unevenness is formed.

In the above directional light diffusion film,
The surface of the transparent region may have one of a convex lens shape and a concave lens shape.

Further, in the directional light diffusion film, an anti-reflection layer may be provided so as to cover the outside of the light diffusion region and the transparent region.

Further, in the directional light diffusion film,
An adhesive layer may be further laminated on at least one of the front surface and the back surface.

Further, in the directional light diffusion film,
The polarizing plate may be a polarizing plate on the front side in a liquid crystal display device.

In the above directional light diffusion film,
A polarizing plate may be further laminated on at least one of the front surface and the back surface.

Further, in the directional light diffusing film, the transparent region may be made of a translucent resin.

In the above directional light diffusion film,
The transparent area may be a space.

According to the present invention, there is provided a display device comprising: a display panel for displaying an image by pixels; and a directional light diffusing film as described above laminated on a display surface of the display panel. The purpose is achieved.

In the display device, the directional light diffusion film may be attached to a display surface of the display panel via a light-transmitting adhesive layer.

In the display device, the display panel is a liquid crystal display panel, and the directional light diffusing film is attached to a polarizing plate on a front surface side of the liquid crystal display panel via the light transmitting adhesive layer. You may.

Further, the invention of the method for producing a directional light diffusing film is characterized in that a fine transparent region transmitting light in the thickness direction and a light transmitting light transmitting in the thickness direction are formed on one surface of the transparent substrate film. In a method for manufacturing a directional light diffusion film, in which a plurality of minute light diffusion regions are alternately arranged in a one-dimensional or two-dimensional direction along the surface without gaps, a plurality of shaping recesses are intermittently arranged in a circumferential direction. While applying a resin in a fluid state to the shaping recesses of the roll plate formed in an intended manner, and wrapping a transparent base film around the outer periphery of the roll plate, the resin in the shaping recesses is A step of rotating the roll plate while contacting, and during rotation of the roll plate, the resin in the shaping recess is brought into close contact with the transparent substrate film and cured, and one of the light diffusion region or the light transmission region And a transparent substrate film together with the cured resin Constructed from a step of peeling from the roll plate is intended to achieve the above object.

In the method for manufacturing a directional light diffusing film, after the peeling step, a gap between the cured resin constituting one of the light diffusing region and the light transmitting region is provided in a gap between the light diffusing region and the light transmitting region. A step of filling and curing the other constituent resin may be provided.

In the present invention, since the front surface or the back surface of the transparent base film is covered with the fine transparent regions and light diffusion regions which are alternately arranged, a reduction in the front luminance and the parallax are prevented by a predetermined light diffusion effect. Can be prevented,
The image blur is prevented by increasing the amount of light emitted in the front direction without being diffused from the transparent region between the adjacent light diffusion regions.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a directional light diffusing film 10 according to a first embodiment of the present invention.

The directional light diffusing film 10 has a fine transparent region 14 on the surface of the transparent base film 12 that transmits light in the thickness direction and a fine light region that diffuses light to be transmitted in the thickness direction. The diffusion regions 16 are alternately arranged without gaps.

The transparent substrate film 12 is made of a transparent resin film, for example, polyethylene terephthalate (PE).
T) a film, the light diffusion region 16 is made of an ultraviolet curable transparent resin containing a light diffusing agent 15 such as an acrylic bead, and the transparent region 14 is made of a transparent resin such as a space or ionizing radiation curable resin. It is composed of

The transparent area 14 and the light diffusion area 16
It is formed in a linear band shape extending in parallel to a direction perpendicular to the paper surface of FIG. These dimensions are, for example, PET
When the thickness of the transparent base film 12 is 125 μm, the height of the transparent region 14 and the light diffusion region 16 in the film thickness direction is about 50 to 150 μm, and the width is about 50 to 120 μm.

When the directional light diffusing film 10 configured as described above is attached to, for example, the display surface of a reflective liquid crystal display device, the emitted light is diffused by the light diffusing region 16 and excessive light in the front direction. Since the brightness can be reduced and the parallax can be prevented, the display light is emitted in the front direction without being diffused through the transparent region 14 between the adjacent light diffusion regions 16, 16, so that the image blur is improved. You.

The light diffusion region 16 has a light diffusion effect by containing a light diffusion agent 15 such as an acrylic bead. However, the present invention is not limited to this. The light diffusion effect may be obtained by means.

For example, like the directional light diffusion film 20 according to the second embodiment of the present invention shown in FIG.
The boundary surface between the transparent region 14 and the light diffusion region 22 may be formed as an uneven surface 24 having fine unevenness to obtain a light diffusion effect. Note that a light diffusing agent may be used in combination.

In the directional light diffusing film 20 according to the second example of the above embodiment, not only light trying to pass through the light diffusing area 22 but also a part of the light trying to pass through the transparent area 14. The light that is reflected by the uneven surface 24 becomes diffused light, and the light that travels straight through the light diffusion region 22 is the uneven surface 2 if no light diffusing agent is contained therein.
As long as the light is not reflected at 4, the light is emitted as straight light.

Further, the transparent regions 14 and the light diffusion regions 16 and 22 in the directional light diffusion films 10 and 20 according to the first and second examples of the above-described embodiment are all arranged in a direction orthogonal to the plane of the drawing. Although constituted by a group of fine straight lines extending linearly, the present invention is not limited to this,
What is necessary is that the transparent region and the light diffusion region are alternately provided in the one-dimensional direction or the two-dimensional direction along the front surface or the back surface of the transparent substrate film.

Therefore, the transparent region 32 and the light diffusion region 34 are formed on the surface of the transparent base film 12 like the directional light diffusion film 30 according to the third embodiment of the present invention shown in FIG. It may be arranged alternately in a grid pattern.

The directional light diffusing films 10, 20, and 30 of the first to third examples of the above embodiment have transparent regions 14, 32 and a light diffusing region 1 in a cross section orthogonal to the surface.
Although the sectional shapes of 6, 22, and 34 are all quadrangular, the present invention is not limited to this, and other polygons may be used.

For example, like the directional light diffusion film 40 according to the fourth embodiment of the present invention shown in FIG.
The cross-sectional shape of the light diffusion region 42 is a trapezoid whose bottom side on the transparent substrate film 12 side is wider than the upper side on the outside, and the transparent region 4
4 may have a trapezoidal shape opposite to the light diffusion region 42.

Next, a directional light diffusing film 50 according to a fifth embodiment of the present invention shown in FIG. 5 will be described.

This directional light diffusing film 50 is obtained by laminating an antireflection layer 56 so as to further cover the transparent region 52 and the light diffusing region 54 in any of the first to fourth examples of the above embodiment. It is.

The anti-reflection layer 56 is made of a material which is compatible with resin, for example, a single-layer or multi-layer cured film of titanium oxide, zirconium oxide or silicon oxide. In the case of a multilayer, it is common to alternately stack titanium oxide and zirconium oxide having a high refractive index and silicon oxide having a low refractive index alternately.

When the anti-reflection layer 56 is provided, the transparent region 52 is made of a light-transmitting resin having the same thickness as the light diffusion region 54, and the anti-reflection layer 56 is formed on the both surfaces.
To form

As described above, when the directional light diffusing film 50 provided with the antireflection layer 56 is attached to the display surface of a liquid crystal display device, the amount of reflected light due to external light is small, so that image blur can be suppressed. .

Next, a directional light diffusing film 60 according to a sixth embodiment of the present invention will be described with reference to FIG.

The directional light diffusion film 60 is formed by the transparent region 52 and the light diffusion region 54 of the transparent base film 12 in the directional light diffusion film 50 shown in FIG.
The adhesive layer 62 is formed on the back surface on the opposite side to the above.

The adhesive layer 62 uses a light-transmitting adhesive.

As described above, when the adhesive layer 62 is provided, the directional light diffusing film 60 can be easily attached to a display surface of a liquid crystal display device, for example.

Next, a directional light diffusion film 70 according to a seventh embodiment of the present invention shown in FIG. 7 will be described.

The directional light diffusion film 70 is formed by the adhesive layer 62 of the directional light diffusion film 60 shown in FIG.
And a polarizing plate 72 is adhered thereto.

The polarizing plate 72 is, for example, a polymer film made of polyvinyl alcohol or the like having dichroism, and is usually one of a pair of polarizing plates sandwiching a liquid crystal element in a liquid crystal panel. Is equivalent to

The directional light diffusing film 70 can be easily formed by attaching the polarizing plate 72 to the liquid crystal element.
It can be a part of a liquid crystal display device.

As the transparent material for forming the transparent substrate film 12, besides polyethylene terephthalate,
A polyester resin such as polybutylene terephthalate, an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, a polystyrene resin, a polymethyl pentene resin, or the like having good permeability is used. Transparent area 1
As the resin constituting 4, 32, 44 or 54, an ionizing radiation curable resin composed of an oligomer such as polyester acrylate, urethane acrylate or epoxy acrylate and / or an acrylate monomer, or an electromagnetic radiation such as ultraviolet ray or electron beam A resin with good transparency, such as a resin cured in step (1), is used. In the case of such a resin, a resin having a refractive index of about 1.4 to 1.6 is usually used.

The beads as the light diffusing agent 15 are made of polymethyl methacrylate (acryl) having a diameter of 1 to 10 μm.
Beads, polybutyl methacrylate beads, polycarbonate beads, polyurethane beads, calcium carbonate beads, silica beads and the like are used.

The light diffusing region 16 is formed by dispersing and fixing the light diffusing agent 15 with a binder resin. As the binder resin, a transparent material such as acryl, polystyrene, polyester, and vinyl polymer is used.

Next, an embodiment of a display device using the above-described directional light diffusion film 10, 20, 30, 40, 50, 60 or 70 will be described.

As shown in FIG. 8, the display device 80 has a directional light diffusing film 70 including the polarizing plate 72 attached to the light emitting surface of a liquid crystal display panel 82. In FIG. 8, reference numeral 84 denotes a liquid crystal display element, and 86 denotes a polarizing plate that sandwiches the liquid crystal display element 84 from the opposite side of the polarizing plate 72.

In the display device 80, as described above, the fine transparent regions 52 and the light diffusion regions 54 are alternately formed on the surface of the directional light diffusion film 84, so that the front luminance due to the light diffusion effect is reduced. In addition to preventing reduction and parallax, the amount of light emitted from the front without being diffused through the transparent region 52 can be increased to prevent image blur.

Each of the transparent areas 14, 32, 44,
52 has a flat surface, but the surface of these transparent regions is not limited to a flat shape.
As shown in the figure, the transparent area 88A may be formed in a convex lens shape, and as shown by a two-dot chain line, the transparent area 88B may be formed in a concave lens shape. Although the shape of the lens is curved in FIG. 9, the shape is not limited to this and may be any shape.

Next, a method of manufacturing the above-described directional light diffusing film will be described with reference to FIG.

The light diffusion film manufacturing apparatus 90 for carrying out this manufacturing method includes the light diffusion regions 16, 22, and 3.
4, 42 or 54 or the transparent areas 14, 32, 4
Roll plate 94 in which shaping recesses 92 having a cross-sectional shape corresponding to 4 or 52 are formed at equal angular intervals in the circumferential direction.
Is applied to the surface of the transparent substrate film 12 wound around the roll plate 94, and a resin 96 to be a light diffusion region or a transparent region is applied and cured.

More specifically, the shaping recess 92 has
A liquid ultraviolet curing resin 96 is continuously supplied (applied) to the shaping recess 92 from a coating device 98 disposed below the roll plate 94 in contact with the outer periphery of the roll plate 94.
The roll plate 94 is provided with the inlet and outlet guide rolls 1.
02A and 102B, the resin 9 in the shaping recess 92 is formed on the inner surface of the transparent base film 12.
6, a predetermined amount of ultraviolet light is applied to the ultraviolet curing resin 96 in the shaping concave portion 92 through the transparent base film 12 by the ultraviolet irradiation device 100 and adheres to the transparent base film 12. And cured.

With the resin 96 adhered to the transparent base film 12, when the transparent base film 12 is separated from the roll plate 94 along the exit guide roll 102B, the cured resin 96 is removed from the shaping recess 92. Get out of.

Thereafter, if necessary, the resin 96, 9
The resin forming the transparent region or the light diffusion region is filled in the gap between 6, and if necessary, the antireflection layer 56, the adhesive layer 62, or the polarizing plate 72 is laminated as described above.

According to this manufacturing method, a directional light diffusing film can be manufactured continuously and at low cost.

When the transparent region and the light diffusion region are arranged in a two-dimensional direction, for example, as shown in FIG. 3, the shaping recesses 92 are also formed in the axial direction and the circumferential direction of the roll plate 94. Are arranged two-dimensionally.

[0069]

EXAMPLES Examples of the present invention will be described below with reference to comparative examples.

In each of Examples 1 to 4, PET film A4300 manufactured by Toyobo as a transparent base film and acrylic beads MX-500H manufactured by Soken Chemicals as a light diffusing agent were weighed into UV curable resin RC17-236 manufactured by Dainippon Ink. The mixture was mixed at a ratio of 20 g / l, and a light diffusion region was formed by the directional light diffusion film manufacturing method of the present invention shown in FIG.
In addition, the transparent region was a space (air) without using a resin.

In the fifth embodiment, a light diffusion region is formed in the same manner as in the first embodiment. Further, a transparent region, which is a space, is filled with a UV curable resin RC17-236 manufactured by Dainippon Ink, and then a UV light is applied. A directional light diffusing film which had been cured and had a transparent region made of resin was obtained.

These were adjusted to the physical properties indicated by the haze value and the total light transmittance as shown in Table 1, and
Four types of directional light diffusion films having a cross-sectional shape and dimensions as shown in FIG. Also in Comparative Examples 1 to 3, the light diffusion was performed using the same material as in Examples 1 to 5 above, without providing a transparent region, so that the coating thickness was 20 μm after curing on a transparent substrate film. An ultraviolet curable resin containing an agent was applied and cured.

[0073]

[Table 1]

The haze value was measured by a haze meter manufactured by Toyo Seiki, as shown in FIG.
No. 03, the transmitted light was received by the light receiving unit 104 from the front and measured. Similarly, the total light transmittance was also measured.

These were obtained from Sharp Electronic Notebook PI-65.
The effect was visually confirmed as shown in FIG. 13 when mounted on the screen 106 of No. 00, and the results were as shown in Table 2.

As shown in Table 2, in each of Examples 1 to 5 of the present invention, the image blur in the front direction was considerably improved as compared with the comparative example. In addition, the reduction of the light diffusion effect was small.

[0077]

[Table 2]

Further, when an anti-reflection layer was provided on the directional light diffusing films of Examples 1 to 4 as described above, the respective reflectances were as shown in Table 3.

[0079]

[Table 3]

[0080]

Since the present invention is constructed as described above, it is possible to prevent a decrease in front luminance and a parallax due to the light diffusion function, and it is possible to prevent the image blur by increasing the amount of light output in the front direction. Has an effect.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a part of a directional light diffusion film according to a first example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view similar to FIG. 1, showing a directional light diffusing film according to a second example of the embodiment.

FIG. 3 is an enlarged plan view showing a part of a directional light diffusion film according to a third embodiment of the present invention;

FIG. 4 is an enlarged cross-sectional view showing a part of a directional light diffusion film according to a fourth example of the embodiment.

FIG. 5 is an enlarged cross-sectional view showing a part of a directional light diffusion film according to a fifth example of the embodiment.

FIG. 6 is an enlarged sectional view showing a part of a directional light diffusion film according to a sixth example of the embodiment.

FIG. 7 is an enlarged sectional view showing a part of a directional light diffusion film according to a seventh example of the embodiment.

FIG. 8 is an enlarged sectional view showing a part of a liquid crystal display according to an eighth example of the embodiment.

FIG. 9 is an enlarged sectional view showing a part of another practical form of the transparent region in the directional light diffusion film of the present invention.

FIG. 10 is a schematic sectional view showing a manufacturing process of the directional light diffusing film.

FIG. 11 is an optical arrangement diagram showing a method for measuring haze value and total light transmittance of Examples and Comparative Examples of the directional light diffusing film of the present invention.

FIG. 12 is an enlarged sectional view showing the directional light diffusing film of the above embodiment.

FIG. 13 is a cross-sectional view showing a process of confirming display light in the example and the comparative example.

[Explanation of symbols]

10, 20, 30, 40, 50, 60, 70 directional light diffusion film 12 transparent substrate film 14, 32, 44, 52, 88A, 88B transparent region 16, 22, 34, 42, 54 light Diffusion region 24 ... Concave surface 56 ... Anti-reflective layer 62 ... Adhesive layer 72 ... Polarizing plate 80 ... Display device 82 ... Liquid crystal display panel 92 ... Shaping concave portion 94 ... Roll plate 96 ... Resin 98 ... Coating device 100 ... Ultraviolet irradiation device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29L 11:00

Claims (17)

[Claims] A fine transparent region for transmitting light in the thickness direction and a fine light diffusion region for diffusing light transmitted in the thickness direction are formed along at least one of the front surface and the back surface of the transparent substrate film. A directional light-diffusing film, which is alternately arranged without gaps in the one-dimensional direction or the two-dimensional direction. 2. The directional light diffusion film according to claim 1, wherein the light diffusion region has a polygonal cross section orthogonal to the front surface or the back surface. 3. The directional light diffusing film according to claim 1, wherein the light diffusing region and the transparent region are formed in parallel linear bands alternately arranged. 4. The directional light diffusion film according to claim 1, wherein the light diffusion region is formed by adding a light diffusion agent to a light transmitting resin. 5. The directional light diffusion film according to claim 1, wherein a boundary between the light diffusion region and the transparent region is an uneven surface on which fine unevenness is formed. 6. The directional light diffusing film according to claim 1, wherein the surface of the transparent region has one of a convex lens shape and a concave lens shape. 7. The directional light diffusion film according to claim 1, wherein an anti-reflection layer is provided so as to cover the outside of the light diffusion region and the transparent region. 8. The directional light diffusing film according to claim 1, further comprising a light-transmitting adhesive layer laminated on at least one of the front surface and the back surface. 9. The directional light diffusion film according to claim 1, further comprising a polarizing plate laminated on at least one of the front surface and the back surface. 10. The directional light diffusing film according to claim 9, wherein said polarizing plate is a polarizing plate on a front side of a liquid crystal display device. 11. The method according to claim 1, wherein
A directional light diffusing film, wherein the transparent region is made of a translucent resin. 12. The method according to claim 1, wherein
A directional light diffusion film, wherein the transparent region is a space. 13. A display panel for displaying an image by pixels,
A directional light diffusion film laminated on the display surface of the display panel, and the directional light diffusion film
A fine transparent region that transmits light in the thickness direction and a fine light diffusion region that diffuses light that transmits in the thickness direction are formed in one dimension along at least one of the front surface and the back surface of the transparent substrate film. A display device characterized by being arranged in a direction or a two-dimensional direction alternately without a gap. 14. The display device according to claim 13, wherein the directional light diffusion film is attached to a display surface of the display panel via a light-transmitting adhesive layer. 15. The display panel according to claim 14, wherein the display panel is a liquid crystal display panel, and the directional light diffusion film is
A display device, wherein the display device is attached to a polarizing plate on a surface side of the liquid crystal display panel via the light transmitting adhesive layer. 16. A fine transparent region for transmitting light in the thickness direction and a fine light diffusion region for diffusing light transmitting in the thickness direction are provided on one surface of the transparent base material film. In a method for manufacturing a directional light diffusing film, which is arranged without gaps in one-dimensional or two-dimensional directions along a surface, a roll plate in which a plurality of shaping recesses are formed intermittently in a circumferential direction.
While applying the resin in a fluid state to the shaping recess, and
Wrap a transparent substrate film around the outer periphery of the roll plate,
A step of rotating the roll plate while being in contact with the resin in the shaping recess, and during rotation of the roll plate, the resin in the shaping recess is brought into close contact with the transparent base film and cured, A method for producing a directional light diffusion film, comprising: a step of forming one of a light diffusion area and a light transmission area; and a step of peeling a transparent substrate film from a roll plate together with a cured resin. 17. The light-diffusing region or the light-transmitting region according to claim 16, wherein, after the peeling step, the other of the light-diffusing region and the light-transmitting region is formed in a gap between the cured resins forming one of the light-diffusing region and the light-transmitting region. A method for producing a directional light diffusing film, comprising a step of filling and curing a resin.