JP2015114529A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device that can perform bright image display during transmission display using an internal light source as well as during reflection display using external light, and can provide image display with high contrast.SOLUTION: There is provided a reflection type liquid crystal display device sequentially including an absorption type polarization element, a liquid crystal element, a light diffusion element, a reflection type polarization element, and an internal light source, where the light diffusion element is a light diffusion film made of photo-cured material derived from a composition for a light diffusion element, and a light diffusion film that includes an internal refractive index distribution structure having an area with a relatively low refractive index and an area with relatively high refractive index distributed therein.

Description

  The present invention relates to a reflective liquid crystal display device, and more particularly to a reflective display using a predetermined light diffusing element, not only during transmissive display by an internal light source at night, but also during reflective display by external light in the daytime. The present invention relates to a reflective liquid crystal display device capable of displaying a bright image and displaying an image with high contrast.

Conventionally, characters and images are printed on light-diffusing surfaces and specular reflective surfaces, or transparent or translucent films with characters or images printed on these surfaces are bonded. An external light utilizing display body (hereinafter referred to as an external light utilizing display body) is used as a signboard or a sign.
Such an external light-use display body uses external light as a light source such as direct sunlight, diffuse sky light, or secondary scattered light from buildings, road surfaces, trees, etc., and scatters desired display light. It is characterized by reflection.

In addition, as such an external light utilizing display body, a signboard is proposed in which a light diffusion film in which fine particles are dispersed in a resin is laminated on the front surface of a decorative layer on which a desired pattern or the like is printed. (For example, refer to Patent Document 1).
More specifically, as shown in FIGS. 14 (a) to (b), at least one of the surfaces has irregularities, the total light transmittance is 90% or more, and the haze value is 20% or less. An external light utilization type display body (signboard) 300 including a signboard front plate 301 including a transparent substrate 302 and a light diffusion layer 303 laminated thereon.
And the center line average roughness (Ra) of the uneven surface on the surface of the light diffusion layer 303 is a value within the range of 0.2 to 0.7 μm, and the 10-point average roughness (Rz) is within the range of 1 to 7 μm. The display body 320 is arranged on the back side of the sign front plate 301, and the surrounding area is covered with a protective frame 321. It is a body (signboard) 300.

On the other hand, a reflection type liquid crystal display device that uses both external light and light emitted from an internal light source (sometimes referred to as a transflective liquid crystal display device) has been proposed as a display unit using external light. (For example, refer to Patent Document 2).
More specifically, as shown in FIG. 15, from the upper side to the lower side, an upper polarizing plate (absorption polarizing plate) 401, an upper glass substrate 402, a liquid crystal element 410, a lower glass substrate 404, A reflective liquid crystal display device 400 in which a reflective polarizing plate 406, a transflective light absorption layer (light diffusion layer) 407, and an internal light source 408 are sequentially stacked, and the change characteristic of the transmission polarization axis is expressed as a light source. Drive characteristic switching means (not shown) that switches according to whether the light is turned on or off.
In FIG. 15, lines A and A ′ represent a visual recognition state at the time of reflective display using external light, and lines B and B ′ represent a visual recognition state at the time of transmissive display using an internal light source. Yes.

JP 2001-109414 A (Claims) Japanese Patent No. 3627246 (Claims)

However, in the case of a signboard using the signboard front plate described in Patent Document 1, it is assumed because it does not consider adjusting the observation angle of the signboard with respect to the assumed incident angle of external light. Depending on the incident angle of the outside light, there is a problem that the installation angle of the signboard itself must be adjusted in order to obtain sufficient visibility.
In addition, in the case of such a signboard, since the emission angle of the display light simply depends on the incident angle of the external light, when the incident angle of the external light changes, a certain display characteristic is stably maintained. There was a problem that it was difficult to do.
Furthermore, the light diffusing characteristic of the light diffusing layer in such a signboard is a Gaussian distribution type light diffusing characteristic, so that the uniformity of the brightness of the display light within the viewing angle becomes low, especially when the display body has a large area. Has a problem that the luminance unevenness of the display light becomes remarkable.

On the other hand, the reflection type liquid crystal display device described in Patent Document 2 has a problem that the light use efficiency is low, and the display screen becomes dark and the contrast tends to be lowered particularly in the reflective display using outside light. It was.
In addition, in the case of such a reflective liquid crystal display device, a phenomenon called “positive / negative reversal” occurs, and when color display is performed via a colored layer, the display color at the time of negative display is far from the actual color. A new problem was seen.
For this reason, there has been a problem that a drive characteristic switching unit that switches the change characteristic of the transmission polarization axis with respect to image data depending on whether the internal light source is turned on or off is required.

In view of the above circumstances, the present inventors have made diligent efforts. As a result, in a reflective liquid crystal display device using a reflective polarizing element / light diffusing element in sequence, the basic characteristics of polarization are used as the light diffusing element. By using a light diffusing film with an internal refractive index distribution structure that does not change optically, bright images can be displayed not only during transmissive display but also during reflective display, and contrast The present invention has been completed by finding that a high image display can be obtained.
That is, an object of the present invention is a reflective liquid crystal display that can be used effectively without impairing the polarization of not only the light emitted from the internal light source but also the external light even with a simple configuration. To provide an apparatus.

  According to the present invention, there is provided a reflective liquid crystal display device that includes an absorptive polarizing element, a liquid crystal element, a light diffusing element, a reflective polarizing element, and an internal light source, and the light diffusing element comprises: A light diffusing film comprising a photocured material derived from the composition for a light diffusing element, and having an internal refraction in which a region having a relatively low refractive index and a region having a relatively high refractive index are distributed. A reflective liquid crystal display device characterized by being a light diffusing film having a rate distribution structure is provided, and the above-described problems can be solved.

That is, if it is a reflection type liquid crystal display device of the present invention, even if it is a simple configuration, by using a predetermined light diffusing element, not only at the time of transmission type display but also at the time of reflection type display, Bright image display is possible and image display with high contrast can be obtained.
In addition, even when the incident angle of outside light changes due to a predetermined light diffusing element / reflective polarizing element combination or the like, a constant display characteristic can be stably maintained, and the viewing angle can be maintained. The reflective liquid crystal display device in which the brightness of the display light is uniform can be obtained.
Note that if the stacking order of the reflective polarizing element / light diffusing element is changed from the internal light source side to the light diffusing element / reflective polarizing element, the external light is reflected without diffusing, particularly in the reflective display. It has been separately found that the display characteristics are deteriorated.

Further, according to the reflective liquid crystal display device of the present invention, in the light diffusion film, the plurality of columnar objects are formed in the film thickness direction of the film as a region having a relatively high refractive index in the region having a relatively low refractive index. It is preferable to have a column structure that is formed in a forest.
By adopting a structure with a column structure in this way, external light incident from the surroundings is efficiently diffused in the viewer direction, and the same optical characteristics are obtained even if the external light incident light changes within a predetermined range. Therefore, a reflective liquid crystal display device with high utilization efficiency of external light or the like can be obtained.
That is, as a light diffusion film having an internal refractive index distribution structure, the above-described column structure, or a louver in which a plurality of plate-like regions having different refractive indexes are alternately arranged along one arbitrary direction along the film surface Although a structure etc. are mentioned, even if it is a case where light is entered from which direction, since predetermined diffused light is obtained stably, it can be said that it is more preferable to provide the column structure mentioned above.

Moreover, according to the reflective liquid crystal display device of the present invention, it is preferable that the diameter of the columnar object increases or the shape of the columnar object changes from one surface of the light diffusion film to the opposite surface.
By configuring the columnar body as a so-called deformed columnar body in this way, it is possible to more stably control the refraction direction of the light incident on and transmitted through the light diffusing film as the light diffusing element. It is possible to obtain a reflective liquid crystal display device with higher utilization efficiency.
In addition, if such a light diffusion film is used, even if the front and back sides are interchanged, the same light diffusion effect can be obtained. Therefore, one surface of the light diffusion film described above is disposed so as to face the liquid crystal element side. It can also be used, or it can be used by arranging one surface of the above-mentioned light diffusion film so as to face the light diffusion element side.

Moreover, according to the reflective liquid crystal display device of the present invention, the composition for a light diffusing element includes (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) and urethane as the component (B). It is preferable to contain (meth) acrylate and a photopolymerization initiator as the component (C).
By comprising in this way, the light-diffusion film which has a predetermined internal refractive index distribution structure and has little influence on a polarization characteristic can be formed rapidly and stably.
That is, since the component (A) and the component (B) can be photocured while efficiently phase-separating to form a light diffusing film, the surface has excellent surface smoothness and an internal refractive index that constitutes a columnar object or the like. The control of the distribution structure becomes more stable, and as a result, a reflective liquid crystal display device with high utilization efficiency of outside light or the like can be easily obtained.

Further, according to the reflective liquid crystal display device of the present invention, a variable 1 / 4λ plate or a variable 1 / 2λ plate for rotating the transmission axis of the light (polarized light) transmitted through the absorptive polarizing element by 90 ° is further provided. It is preferable.
In this way, by further including a variable 1 / 4λ plate or a variable 1 / 2λ plate as a phase plate at a predetermined location, so-called black and white inversion display is possible, and monochrome display by external light, The black and white display by the light source can be matched.

Further, according to the reflective liquid crystal display device of the present invention, when the absorbing polarizing element is the first absorbing polarizing element, the second absorbing type is interposed between the reflective polarizing element and the internal light source. As the polarizing element, an absorptive polarizing element having the same transmission axis as that of the reflective polarizing element is preferably provided.
With this configuration, even when a part of the light reflected toward the liquid crystal element is disturbed by the polarization state in the vicinity of the internal light source during external light display, the second absorption polarizing element , Such reflected light can be reliably blocked. Therefore, the contrast in image display can be significantly increased.

According to the reflection type liquid crystal display device of the present invention, the third absorption type polarization element having a transmission axis different from that of the reflection type polarization element is provided on the side opposite to the side facing the reflection type polarization element in the internal light source. Is preferred.
With this configuration, even when there is light that goes out to the outside toward the lower side of the internal light source, the light is efficiently absorbed and the white display by the external light becomes blackish. The phenomenon can be effectively prevented.

Moreover, according to the reflection type liquid crystal display device of the present invention, it is preferable that the internal light source is a light guide plate or an organic luminescence element including an LED at an end.
With this configuration, it is possible to reduce the disturbance of the polarization state due to the internal light source itself, and it is possible to display a brighter image not only during transmissive display but also during reflective display. In addition, an image display with high contrast can be obtained.

FIG. 1 is a diagram for explaining a visual recognition state at the time of reflective display in the reflective display device (first embodiment) of the present invention. FIG. 2 is a diagram for explaining a visual recognition state during transmissive display in the reflective display device (first embodiment) of the present invention. FIG. 3A is a diagram for explaining a visual state at the time of reflective display in the reflective display device (first embodiment) of the present invention, and FIG. FIG. 3C is a diagram provided for explaining the visual recognition state in a state in which the monochrome display during the transmissive display is reversed, similarly. FIG. 4 is a diagram for explaining the relationship between the incident angle θ1 of external light in the light diffusing element and the luminance in front of the light diffusing element. FIGS. 5A to 5B are views used to explain the principle of light diffusion characteristics in the light diffusing element (part 1). FIGS. 6A and 6B are diagrams for explaining the principle of light diffusion characteristics in the light diffusing element (part 2). FIGS. 7A and 7B are diagrams provided to explain a modification of the columnar object in the light diffusing element. FIGS. 8A to 8B are other diagrams provided for explaining a manufacturing example of the light diffusing element. FIG. 9A to FIG. 9D are other views provided for explaining a manufacturing example of the light diffusing element. FIG. 10 is a diagram for explaining a visual recognition state during reflective display in the reflective display device (second embodiment) of the present invention. FIG. 11 is a diagram for explaining a visual recognition state during transmissive display in the reflective display device (second embodiment) of the present invention. FIG. 12 is a diagram for explaining a visual recognition state at the time of reflective display in the reflective display device (third embodiment) of the present invention. FIG. 13 is a diagram for explaining a visual recognition state during transmissive display in the reflective display device (third embodiment) of the present invention. FIGS. 14A to 14B are views provided for explaining an external light utilization type display body (signboard) using a conventional light diffusion film. FIG. 15 is a diagram for explaining a conventional reflective liquid crystal display device using a reflective polarizing plate and a transflective light absorption layer.

[First embodiment]
As illustrated in FIGS. 1 and 2, the first embodiment of the present invention includes an absorptive polarizing element 12, a liquid crystal element 20 (TFT substrate 14, liquid crystal layer 16, counter substrate 18), light diffusing element 22, and the like. , A reflective liquid crystal display device 10 that sequentially includes a reflective polarizing element 24 and an internal light source 26, wherein the light diffusing element 22 is a light diffusing material made of a photocured material derived from the light diffusing element composition. A light diffusing film having an internal refractive index distribution structure in which a region having a relatively low refractive index and a region having a relatively high refractive index are distributed. This is a reflective liquid crystal display device 10.
Hereinafter, the reflective liquid crystal display device of the first embodiment will be specifically described with reference to the drawings as appropriate.

1. Basic Configuration and Operation of Reflective Liquid Crystal Display Device First, the basic configuration of the reflective liquid crystal display device of the present invention will be described. As shown in FIGS. 1 and 2, the upper side (viewer side) to the lower side (internal light source side). ), The reflective liquid crystal display device 10 includes an absorptive polarizing element 12, a liquid crystal element 20, a light diffusing element 22, a reflective polarizing element 24, and an internal light source 26 in order. And a reflective liquid crystal display device 10 capable of both transmissive display and display.

For example, in the case of daytime when the illuminance exceeds 100 Lux and is about 1000 Lux, as shown in FIG. 1, liquid crystal is used by using external light (A, B) incident from the upper image display surface side. Using the switching of the element 20 (rotation of polarized light by 90 °), it is possible to display a predetermined image in a reflective manner by combining white display and black display (sometimes referred to as external light display).
That is, in the case where white display is performed using external light, a predetermined voltage is not applied to the liquid crystal element 20 (shown as voltage O in the figure), and the polarized light transmitted through the absorption polarizing element 12 is used. After the 90 ° rotation of the polarization axis by the liquid crystal layer 16, a part of polarized light is completely reflected by the reflective polarizing element 24, so that a white display image can be viewed from the outside.
Assuming that the incident light from the outside is 100%, it is assumed that about 50% of the light is absorbed by the absorptive polarizing element 12 and is hardly absorbed by other members (A ′). The amount of light is an example, but it is 50%, so it is shown in the figure.

On the other hand, in the case of displaying black using external light, by applying a predetermined voltage to a predetermined portion of the liquid crystal element 20 (indicated as voltage + in the figure), a part of incident light is The 90 ° rotation of polarized light by the liquid crystal layer 16 may not be performed.
Accordingly, although external light (B) is transmitted through the light diffusing element 22 and the reflective polarizing element 24 so as to reach the internal light source 26, black light is displayed from the outside by not reflecting the light to the outside. As visible.
In consideration of the arrangement direction of the absorptive polarizing element 12, the polarization axis is changed by 90 °, as described later, a retardation plate is provided below the absorptive polarizing element 12, or the voltage wiring state In contrast to the above, the 90 ° rotation of the polarized light by the liquid crystal layer 16 can be performed only when a predetermined voltage is applied to a predetermined location by changing the above (the same applies hereinafter). .)

In addition, the external light (B) that reaches the internal light source 26 from the outside may be partially disturbed in polarization inside the internal light source 26.
Then, as shown in FIG. 1, the light whose polarization is disturbed passes through the liquid crystal element 20 through the reflective polarizing element 24 and the light diffusing element 22 from below, and further passes through the absorption polarizing element 12. It may be visually recognized from the outside as a grayish black display (B ′).
Therefore, when the amount of incident light is 100%, the light amount of black display light (B ′) is an example, but is indicated as 25% in the drawing.
In any case, in the case of daytime, by using outside light (A, B) and combining the switching of the liquid crystal element 20 (90 ° rotation of polarized light by the liquid crystal layer), etc., as shown in FIG. In addition, white display and black display are partially possible, and as a result, a predetermined image can be reflected and displayed by combining them.

On the other hand, for example, at night when the illuminance is less than 100 Lux, as shown in FIG. 2, the internal light source 26 provided on the back side is used, and the light (A ″, B ″) emitted therefrom is used. ), A predetermined image is transmitted and displayed by combining white display and black display by switching the liquid crystal element 20 (rotation of polarized light by 90 ° by the liquid crystal layer) or the like (sometimes referred to as internal light source display). .)Is possible.
That is, when black display is performed using the internal light source 26, a predetermined voltage is not applied to the liquid crystal element 20 (shown as voltage O in the figure), and the polarized light by the liquid crystal layer 16 is rotated by 90 °. For this reason, some of the emitted light (A) is visually recognized as black display from the outside because the polarization axis is not aligned and cannot be transmitted through the absorptive polarizing element 12 and is blocked (X display) on the way. be able to.
When the light emitted from the internal light source is assumed to be 100%, if the 90 ° rotation of the polarized light by the liquid crystal layer 16 is not performed, it is estimated that the light is completely absorbed by the absorptive polarizing element 12. The light quantity of the display light (A ″) is an example, but it is indicated as 0% in the figure.

In addition, when white display is performed using the internal light source 26, a predetermined voltage is applied to a predetermined portion of the liquid crystal element 20 (indicated as voltage + in the figure), and light emitted from the internal light source 26 (B Since “′) is not rotated by 90 °, the liquid crystal element 20 and the absorptive polarizing element 12 can be transmitted, and as a result, a white display can be visually recognized from the outside.
Note that when the light emitted from the internal light source 26 is 100%, the amount of light transmitted through the absorptive polarizing element 12 is estimated to be about 50%. For this reason, the amount of white display light (B ″) is an example, but it is 50%, and is thus shown in the figure.
Therefore, in the case of nighttime, by using the internal light source 26 and combining the switching of the liquid crystal element 20 (90 ° rotation of polarized light), etc., as shown in FIG. Black display is possible, and as a result, a combination of these can display a predetermined image in a transparent manner.

2. Absorption-type Polarizing Element Next, the absorption-type polarizing element 12 shown in FIGS. 1 and 2 will be described. The absorption-type polarizing element 12 transmits a linearly polarized light component along a desired polarization axis, while other different linearly polarized light. It has a function of absorbing components, that is, converting outside light mixed with various polarized light into only predetermined linearly polarized light.
Although there is no particular limitation on the aspect of such an absorption polarizing element, for example, a TAC obtained by stretching a polymer film of PVA (polyvinyl alcohol) adsorbed with a halogen substance such as iodine or a dichroic dye is used. By sandwiching with (triacetylcellulose), it can be suitably configured as an absorptive polarizing element.

3. Liquid Crystal Element Next, a liquid crystal element (sometimes referred to as a display panel) 20 that is a main component of the reflective liquid crystal display device 10 will be described.
As shown in FIG. 1, the liquid crystal element 20 is basically opposed to a glass substrate with a circuit (hereinafter referred to as a TFT substrate) 14 provided with TFTs (thin film transistors) via a predetermined gap. And a liquid crystal layer 16 sandwiched between the TFT substrate 14 and the counter substrate 18.
Therefore, the liquid crystal element 20 is combined with the action of the other absorption polarizing element 12 and the like, and the predetermined voltage in the liquid crystal layer 16 is applied / non-applied by turning on / off the electrical switch corresponding to each pixel, Since 90 ° polarization of light at an arbitrary location is possible, as a result, a predetermined image can be displayed at high speed.
Various aspects of the liquid crystal element 20 have been proposed and publicized. However, the reflective liquid crystal display device 10 can be configured by applying any aspect.

4). Light Diffusing Element (1) Internal Refractive Index Distribution Structure The light diffusing element 22 basically has a function of making the obtained light a diffused light, and is a light diffusing film made of a photocured material derived from the composition for the light diffusing element. The light diffusion film has an internal refractive index distribution structure in which a region having a relatively low refractive index and a region having a relatively high refractive index are distributed.
That is, if the light diffusion film having such an internal refractive index distribution structure has a simple configuration, the incident angle of outside light changes due to a predetermined light diffusion element / reflective polarizing element combination or the like. Even so, it is possible to obtain a reflective liquid crystal display device that can stably maintain a certain display characteristic and that has uniform brightness of display light within a viewing angle.

By providing such a light diffusing element between the liquid crystal element and the reflective polarizing element, the reflection direction can be limited to a specific direction, particularly in reflective display. Can be further enhanced.
Therefore, as shown in FIG. 3B, a bright image display is possible not only during transmission display by the internal light source 26 but also during reflection display by external light as shown in FIG. And an image display with high contrast can be obtained.

  However, as shown in FIG. 3 (a), in the case of reflective display by external light, the reason why the black display is slightly white is that the internal light source 26 has been reached from the outside as described above in part. A part of the outside light (B) is disturbed in polarization inside the internal light source 26, and the light is transmitted from below through the liquid crystal element 20 through the reflective polarizing element 24 and the light diffusing element 22, and further absorbed. This indicates that the light is transmitted through the polarizing element 12 and viewed from the outside as a grayish black display (B ′).

  On the other hand, as a light diffusing film having an internal refractive index distribution structure, a plurality of columnar objects are formed in the film thickness direction of the film surface as a region having a relatively high refractive index in a region having a relatively low refractive index. Column structure, or a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged along any one direction along the film surface in a region having a relatively low refractive index. Although it can be mentioned, it can be said that it is more preferable to provide a column structure because predetermined diffused light can be stably obtained even when light is incident from any direction.

That is, as will be described in more detail later, if the light diffusing film has a column structure, for example, depending on the incident angle of external light, as shown in FIG. It has been found that a relationship between (θ1) and the luminance in front of the light diffusing element can be obtained.
Therefore, by using a light diffusing film having a predetermined column structure as the light diffusing element 22, there is a problem of an incident angle of external light. It is understood that excellent brightness can be obtained.
In contrast, conventional particle-dispersed light diffusing elements are known to inhibit polarization characteristics as compared to light diffusing films made of a photocured material derived from such a composition for light diffusing elements. In other words, it can be said that a bright image with excellent contrast cannot be displayed as shown in FIGS.

(2) Diffusion Principle Next, with reference to FIGS. 5 to 6, a light diffusing element 22 having a column structure or a louver structure (in FIGS. 5 to 6, the light diffusing element 22 is referred to as a light diffusing film 100 for convenience). The diffusion principle will be described taking the light diffusion element 22 having a column structure as an example.
First, FIG. 5A shows a top view (plan view) of the light diffusion film 100, and FIG. 5B shows the light diffusion film 100 shown in FIG. A cross-sectional view of the light diffusion film 100 when cut in the vertical direction along A and viewing the cut surface in the arrow direction is shown.
6A shows an overall view of the light diffusion film 100, and FIG. 6B shows a cross-sectional view of the light diffusion film 100 of FIG. 6A viewed from the X direction. Is shown.

As shown in the plan view of FIG. 5A, the light diffusion film 100 includes a columnar body 112 having a relatively high refractive index and a region (low refractive index region) 114 having a relatively low refractive index. The column structure 113 is as follows.
Further, as shown in the cross-sectional view of FIG. 5B, in the vertical direction of the light diffusion film 100, the columnar body 112 having a relatively high refractive index and the low refractive index region 114 each have a predetermined width. Thus, they are arranged alternately.

Accordingly, as shown in FIG. 6A, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused in a predetermined direction by the light diffusion film 100.
That is, as shown in FIG. 5B, the incident angle of the incident light with respect to the light diffusion film 100 is a value in a predetermined angle range from parallel to the boundary surface 113a of the column structure 113, that is, a light diffusion incident angle region. The incident light 152, 154 passes through the inside of the columnar body 112 having a relatively high refractive index in the column structure along the film thickness direction while changing the direction. It is estimated that the traveling direction of light on the surface side is not uniform.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the light diffusion film 100 and becomes diffused light (152 ′, 154 ′).
On the other hand, when the incident angle of the incident light with respect to the light diffusion film 100 deviates from the light diffusion incident angle region, the incident light 156 is not diffused by the light diffusion film as shown in FIG. It is presumed that it passes through the light diffusion film 100 as it is and becomes transmitted light 156 ′.
Therefore, for example, as shown in FIG. 6A, the light diffusion film 100 provided with the column structure 113 can exhibit incident angle dependency in light transmission and diffusion.

And the light-diffusion film 100 which has the column structure 113 shown in FIGS. 5-6 normally has "isotropic" in a spreading | diffusion.
Here, in the present invention, “isotropic” means that, as shown in FIG. 6A, when incident light is diffused by a light diffusion film, the direction of the diffused outgoing light along the film surface. This means that the degree of diffusion of the light (the shape of the spread of the diffused light) does not change depending on the direction in the same plane.
More specifically, as shown in FIG. 6A, when the incident light is diffused as “isotropic” by the light diffusion film 100, the diffused outgoing light is in a direction along the film surface, That is, it is diffused uniformly and circularly in a plane parallel to the film.
Note that the diffused emitted light is diffused non-uniformly and non-circularly (in the case of having an elliptical shape, a linear shape, a square shape, a diamond shape, a plurality of diffusion regions, etc.) against “isotropic” diffusion. It will be referred to as having diffusion “anisotropic”.

(3) Column structure Also, as shown in FIGS. 5A to 5B and FIGS. 6A to 6B, the refractive index is relatively high in the region 114 having a relatively low refractive index. As a region, it is preferable to include a column structure 113 in which a plurality of columnar objects 112 are forested in the film thickness direction of the film surface.
The reason for this is that the column structure 113 in which a plurality of pillars 112 are erected in the film thickness direction in this way makes the light refracted by being incident on the light diffusion film 100 and transmitted while diffusing. This is because the direction can be controlled more stably, and the reflection type liquid crystal display device 10 with higher utilization efficiency of outside light or the like can be obtained.
In addition, if the light diffusing film having the column structure is used, light having a louver structure can be obtained stably even if light is incident from any direction. It is easier to use than the diffusion film, and can be said to be more preferable when applied to the reflective liquid crystal display device 10.

In addition, as shown in FIGS. 6A to 6B, in the light diffusion film 100 having a column structure, from the surface (first surface 115) as the main surface to the back surface (second surface 116). It is preferable that the diameter of the columnar object 112 increases or the shape of the columnar object changes.
The reason for this is that by configuring the columnar body as a deformed columnar body in this way, the refraction direction of the light incident on and transmitted through the light diffusion film can be controlled more stably, and the utilization efficiency of external light and the like can be further increased. This is because a highly reflective liquid crystal display device can be obtained.

Further, as shown in FIG. 7 (a), in the light diffusion film 100 ′ provided with the column structure 113 ′, in the photocured material having a low refractive index, from the predetermined columnar material 112 ′ having two inclination angles. As configured, it is also preferable to provide a bent portion 112a ′ whose inclination angle changes in the middle of the predetermined columnar object 112 ′, for example, at an intermediate position.
In that case, the bending angle in the predetermined columnar body 112 ′ is preferably set to a value in the range of 100 to 175 °, more preferably set to a value in the range of 120 to 170 °, and 130 to 160 °. More preferably, the value is within the range.

Further, as shown in FIG. 7B, a plurality of (two types) columnar objects (second columnar 112a ″ and first columnar 112b ″) having different inclination angles are combined in the vertical direction. It is also preferable that the column structure 113 ″ includes a predetermined columnar body 112 ″.
In that case, it is preferable to set the inclination angle of the second columnar body 112a ″ to a value within a range of 5 to 45 ° with respect to the vertical direction, while the first columnar body 112b ″ The inclination angle is preferably set to a value in the range of 0 to 4 ° with respect to the vertical direction.
In any case, as the predetermined columnar bodies 112 ′ and 112 ″ included in the column structures 113 ′ and 113 ″, a predetermined bent portion 112a ′ is provided, or plural (two types) columnar bodies having different inclination angles are provided. By combining 112a ″ and 112b ″, the light diffusion films 100 ′ and 100 ″ having such column structures 113 ″ and 113 ″ can be more stably and have good light diffusion characteristics. It can be demonstrated.

(4) Composition for light diffusing element Moreover, the composition for light diffusing elements which forms a light diffusing element is (meth) acrylic acid ester which contains several aromatic rings as (A) component, and (B) component It is preferable to contain a urethane (meth) acrylate as a photopolymerization initiator as a component (C).
This is because the light diffusing film having a predetermined internal refractive index distribution structure can be formed quickly and stably by configuring in this way.
That is, since the light diffusing film can be formed by photo-curing the component (A) and the component (B) efficiently, the control of the internal refractive index distribution structure constituting the columnar object is more stable. As a result, it is possible to easily obtain a reflective liquid crystal display device with high utilization efficiency of external light or the like.
Hereinafter, (A) component, (B) component, and other components ((C) component, (D) component, etc.) which are the components of the composition for light diffusing elements will be described in more detail.

(4) -1 (A) component The composition for light diffusing elements contains a plurality of aromatic rings (biphenyl rings, etc.) having a weight average molecular weight of 200 to 2,500 as a component (A) (meta). It is preferable to contain an acrylic ester.
The reason for this is that by including such a specific (meth) acrylic acid ester, the polymerization rate of the component (A) is made faster than the polymerization rate of the component (B), and the polymerization rate between these components is predetermined. This is because it is presumed that a difference is produced and the copolymerizability of both components can be effectively reduced.
As a result, when photocured, a plurality of columnar objects having a relatively high refractive index derived from the component (A) are forested in a region where the refractive index derived from the component (B) is relatively low. The column structure can be formed efficiently.

  Examples of the (meth) acrylic acid ester containing a plurality of aromatic rings as the component (A) include, for example, biphenyl (meth) acrylate, naphthyl (meth) acrylate, anthracyl (meth) acrylate, (meth ) Benzylphenyl acrylate, biphenyloxyalkyl (meth) acrylate, naphthyloxyalkyl (meth) acrylate, anthracyloxyalkyl (meth) acrylate, benzylphenyloxyalkyl (meth) acrylate, or on aromatic ring One kind of hydrogen atom or a combination of two or more kinds such as those in which a part of hydrogen atoms are substituted by halogen, alkyl, alkoxy, halogenated alkyl or the like can be mentioned.

Moreover, it is preferable to make the refractive index of (A) component (before hardening) into the value within the range of 1.5-1.65.
This is because the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) is obtained by setting the refractive index of the component (A) within the range. This is because the light diffusing film having the column structure can be adjusted more easily and more efficiently.
That is, when the refractive index of the component (A) is less than 1.5, the difference from the refractive index of the component (B) becomes too small, and it may be difficult to obtain an effective light diffusion angle region. Because there is.
On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference with the refractive index of the component (B) increases, but even an apparent compatibility state with the component (B) is formed. This is because it may be difficult to do.
Therefore, the refractive index of the component (A) is more preferably set to a value within the range of 1.52 to 1.62, and further preferably set to a value within the range of 1.56 to 1.6.
The refractive index of the component (A) can be measured, for example, according to JIS K0062 (hereinafter the same).

Moreover, it is preferable to make content of (A) component into the value within the range of 25-400 weight part with respect to 100 weight part of (B) component mentioned later.
The reason for this is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) decreases, and the columnar material derived from the component (A) in the column structure This is because it may become difficult to obtain a column structure having a good incident angle dependency. Moreover, it is because the length of the columnar thing in the film thickness direction of a light-diffusion film may become inadequate, and may not show a predetermined light-diffusion characteristic.
On the other hand, when the content of the component (A) exceeds 400 parts by weight, the ratio of the component (A) to the component (B) increases, and the width of the columnar material derived from the component (A) is excessive. This is because, on the contrary, it may be difficult to obtain a column structure having a good incident angle dependency. Moreover, it is because the length of the columnar thing in the film thickness direction of a light-diffusion film may become inadequate, and may not show a predetermined light-diffusion characteristic.
Accordingly, the content of the component (A) is more preferably set to a value in the range of 40 to 300 parts by weight, and a value in the range of 50 to 200 parts by weight with respect to 100 parts by weight of the component (B). More preferably.

(4) -2 (B) component Moreover, it is preferable that the composition for light-diffusion elements contains the urethane (meth) acrylate whose weight average molecular weight is the range of 3,000-20,000 as (B) component. .
The reason for this is that if it is urethane (meth) acrylate, the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) can be adjusted more easily. (B) It is because the dispersion | distribution of the refractive index of the area | region derived from a component can be suppressed effectively, and the light-diffusion film provided with the column structure can be obtained more efficiently.

In addition, by setting the weight average molecular weight of the component (B) within a predetermined range, a predetermined difference is caused in the polymerization rate of the component (A) and the component (B), and the copolymerizability of both components is effectively reduced. It is because it can be made.
As a result, when photocured, a plurality of columnar objects having a relatively high refractive index derived from the component (A) are forested in a region where the refractive index derived from the component (B) is relatively low. The column structure can be formed efficiently.

Here, as such urethane (meth) acrylate, for example, (B1) a compound containing at least two isocyanate groups, (B2) a polyol compound, preferably a diol compound, particularly preferably a polyalkylene glycol, and ( B3) A reaction product composed of one kind of hydroxyalkyl (meth) acrylate or a combination of two or more kinds can be mentioned.
Moreover, the synthesis | combination of the urethane (meth) acrylate by (B1)-(B3) component can be implemented in accordance with a conventional method.
At this time, the blending ratio of the components (B1) to (B3) is preferably set to a ratio of (B1) component: (B2) component: (B3) component = 1-5: 1: 1-5 in molar ratio. .
The reason for this is that by setting such a blending ratio, one isocyanate group of the component (B1) reacts and binds to the two hydroxyl groups of the component (B2), and two more components (B1) This is because the urethane (meth) acrylate in which the hydroxyl group of the component (B3) reacts with and bonds to the other isocyanate group possessed by each can be synthesized efficiently.

Moreover, it is preferable to make the refractive index (before hardening) of (B) component into the value within the range of 1.4-1.55.
This is because the difference between the refractive index of the region derived from the component (A) and the refractive index of the region derived from the component (B) is obtained by setting the refractive index of the component (B) within the range. This is because the light diffusing film having the column structure can be adjusted more easily and more efficiently.
That is, when the refractive index of the component (B) is less than 1.4, the difference from the refractive index of the component (A) increases, but the compatibility with the component (A) is extremely deteriorated, and the column structure It is because there exists a possibility that it cannot form. On the other hand, when the refractive index of the component (B) exceeds 1.55, the difference from the refractive index of the component (A) becomes too small, making it difficult to obtain the desired incident angle dependency. Because there is.
Therefore, the refractive index of the component (B) is more preferably set to a value within the range of 1.45 to 1.54, and further preferably set to a value within the range of 1.46 to 1.52.
In addition, the refractive index of (B) component can be measured according to JISK0062, for example.

In addition, the difference between the refractive index of the component (A) and the refractive index of the component (B) is preferably set to a value of 0.01 or more.
The reason for this is that a light diffusion film having a better incident angle dependency in light transmission and diffusion and a wider light diffusion incident angle region is obtained by setting the difference in refractive index to a value within a predetermined range. Because it can.
That is, when the difference in refractive index is less than 0.01, the angle range in which incident light is totally reflected in the column structure is narrowed, so that the opening angle in light diffusion may be excessively narrowed. is there.
On the other hand, if the difference in refractive index is an excessively large value, the compatibility between the component (A) and the component (B) is excessively deteriorated and the column structure may not be formed.
Therefore, the difference between the refractive index of the component (A) and the refractive index of the component (B) is more preferably set to a value in the range of 0.05 to 0.5, More preferably, the value is within the range.
In addition, the refractive index of (A) component and (B) component here means the refractive index of (A) component and (B) component before hardening by light irradiation.

Moreover, it is preferable to make content of (B) component in the composition for light diffusing elements into the value within the range of 10-75 weight part with respect to 100 weight part of whole quantity of the composition for light diffusing elements.
The reason for this is that when the content of the component (B) is less than 10 parts by weight, the ratio of the component (B) to the component (A) decreases, and the region derived from the component (B) becomes (A This is because it may be too small compared with the region derived from the component, and it may be difficult to obtain a column structure having good incident angle dependency.
On the other hand, when the content of the component (B) exceeds 75 parts by weight, the ratio of the component (B) to the component (A) increases, and the region derived from the component (B) becomes (A) This is because it becomes excessively large as compared with the region derived from the components, and conversely, it may be difficult to obtain a column structure having good incident angle dependency.
Therefore, the content of the component (B) is more preferably set to a value within the range of 20 to 70 parts by weight with respect to 100 parts by weight of the total amount of the light diffusing element composition, More preferably, the value is within the range.

(4) -3 (C) component Moreover, it is preferable that the composition for light-diffusion elements contains a photoinitiator as (C) component.
This is because when the active energy ray is irradiated to the composition for a light diffusing element, the refractive index derived from the component (B) is efficiently derived from the component (A). This is because it is possible to form a column structure in which a plurality of pillars having a relatively high refractive index are forested.

Here, the photopolymerization initiator as the component (C) refers to a compound that generates radical species by irradiation with active energy rays such as ultraviolet rays.
Accordingly, the type of the photopolymerization initiator is not particularly limited, and examples thereof include an α-hydroxyacetophenone type photopolymerization initiator, an α-aminoacetophenone type photopolymerization initiator, and an acyl phosphine oxide type polymerization initiator. It is preferably at least one selected from the group consisting of
The reason for this is that these photopolymerization initiators can bend the column structure more clearly, so that the spread angle of diffused light in the resulting light diffusion film can be more effectively expanded. It is because it can do.
That is, with these photopolymerization initiators, when forming a bent column structure, the separation of these components is promoted so that the difference in refractive index between the regions derived from the components (A) and (B) becomes larger. This is because it is presumed to contribute to curing.

  Specific examples of the photopolymerization initiator include, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2. -Phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio ) Phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4- Ethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane], etc. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator as the component (C) is a value within the range of 0.2 to 20 parts by weight with respect to the total amount (100 parts by weight) of the component (A) and the component (B). It is preferable that
The reason for this is that when the content of the component (C) is less than 0.2 parts by weight, not only is it difficult to obtain a light diffusion film having sufficient incident angle dependency, but the polymerization initiation point is excessive. This is because it may become difficult to sufficiently cure the film.
On the other hand, when the content of the component (C) exceeds 20 parts by weight, the ultraviolet absorption in the surface layer of the coating layer becomes excessively strong, and on the contrary, the photocuring of the film is inhibited or the odor becomes excessively strong. This is because the initial yellowness of the film may become strong.

(4) -4 (D) component Moreover, as shown to Fig.7 (a)-(b), let the composition for light diffusing elements be a deformation | transformation columnar object which has a bending part in the middle of predetermined columnar object 113 '. In this case, as the component (D), at least one ultraviolet absorber selected from the group consisting of a hydroxyphenyltriazine-based UV absorber, a benzotriazole-based UV absorber, a benzophenone-based UV absorber, and a hydroxybenzoate-based UV absorber Is preferably contained so as to be less than 2 parts by weight (excluding 0 part by weight) with respect to the total amount (100 parts by weight) of the component (A) and the component (B).
This is because, by containing a relatively small amount of such an ultraviolet absorber, active energy rays having a predetermined wavelength can be selectively absorbed within a predetermined range when active energy rays are irradiated.
As a result, the column structure formed in the film can be bent without hindering the curing of the composition for light diffusing elements, whereby the light diffusing film obtained can be more stably determined. The light diffusing property can be imparted.

(4) -5 Other Additives Additives other than the above-described compounds can be appropriately added to the composition for a light diffusing element as long as the effects of the present invention are not impaired.
Examples of such additives include hindered amine light stabilizers, antioxidants, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluent solvents, and leveling agents. .
In addition, generally content of such an additive shall be a value within the range of 0.01-5 weight part with respect to the total amount (100 weight part) of (A) component and (B) component. Is preferable, it is more preferable to set it as the value within the range of 0.02-3 weight part, and it is further more preferable to set it as the value within the range of 0.05-2 weight part.

(5) Film thickness Although the film thickness of the light diffusing element (light diffusing film) is not particularly limited, it is usually preferably set to a value in the range of 20 to 1,500 μm.
The reason for this is that when the thickness of the light diffusing element is less than 20 μm, the mechanical strength and durability are lowered, or the form of the columnar material formed inside is excessively reduced, and is stable. This is because it may be difficult to manufacture automatically.
On the other hand, when the film thickness of such a light diffusing element exceeds 1,500 μm, it becomes difficult to handle, and again, it becomes difficult to control the form of the columnar material formed therein, and it is stably manufactured. Therefore, it is more preferable to set the film thickness of the light diffusing element (light diffusing film) to a value within the range of 50 to 1,000 μm, and within the range of 100 to 800 μm. More preferably, the value of

On the other hand, for a plurality of columnar objects formed inside the light diffusing element (light diffusing film), the length (L) in the vertical direction along the film thickness is usually set to a value in the range of 50 to 700 μm. Is more preferable, and a value in the range of 100 to 400 μm is more preferable.
The reason for this is that the length (L) in the vertical direction of the column structure is set to a value within a predetermined range, so that the length of the pillars standing in the film thickness direction can be stably secured and incident in the column structure. This is because the light can be reflected more stably and the uniformity of the intensity of the diffused light within the light diffusion angle region derived from the column structure can be further improved.
Furthermore, for a plurality of columnar objects formed inside the light diffusing element (light diffusing film), it is usually preferable that the diameter (equivalent circle diameter) is a value within the range of 0.1 to 15 μm. More preferably, the value is in the range of 5 to 10 μm.
The reason for this is that, by setting the diameter of the columnar material to a value within a predetermined range, manufacturing stability can be obtained, and incident light can be reflected more stably in the column structure, and the incident angle dependence can be derived from the column structure. This is because the property can be improved more effectively.
In addition, about the some columnar object formed in the inside of a light-diffusion element (light-diffusion film), the center distance (CTC) in an adjacent columnar object is made into the value within the range of 0.2-30 micrometers normally. It is preferable that the value be in the range of 1 to 20 μm.
The length, diameter, and center-to-center distance for a plurality of columnar objects formed inside the light diffusing element (light diffusing film) can be measured from, for example, an electron micrograph.

(6) Manufacturing method As a light diffusing element, it is a light-diffusion film which consists of a photocured material derived from the composition for light diffusing elements, Comprising: The area | region where a refractive index is relatively low, and a refractive index are relatively high The light diffusing film having an internal refractive index distribution structure in which the region is distributed is an example, but preferably formed by combining the application step and the irradiation step as follows. Can do.

(6) -1 Application Step As the application step, as shown in FIG. 8A, the composition for light diffusing elements is applied to a process sheet 102 such as a polyethylene terephthalate film subjected to a release treatment, and the application layer 101 is applied. Form.
That is, the light diffusing element composition is applied onto the process sheet by a conventionally known method such as a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, or a gravure coating method. Can do.

(6) -2 Irradiation Step As shown in FIG. 8B, the irradiation step is performed by irradiating the formed coating layer 101 with active energy rays (ultraviolet irradiation) to form a light diffusing element composition. For example, a column structure, a louver structure, or a combination thereof is formed inside the layer 101 to form a light diffusion film.

More specifically, in order to stably form the column structure, in the active energy ray irradiation step, parallel light having a high degree of parallelism of light rays with respect to the coating layer 101 formed on the step sheet 102. Is preferably irradiated.
Next, an ultraviolet irradiation device (for example, ECS-4011GX manufactured by Eye Graphics Co., Ltd.) in which a condensing cold mirror is attached to a linear high-pressure mercury lamp (diameter 25 mm) as a commercial product is prepared.
More specifically, as shown in FIG. 9 (b), a heat ray cut filter (not shown) and a light shielding plate (not shown) are arranged at predetermined positions of the linear ultraviolet lamp 125, and the linear shape is changed. The irradiation light collimating member 200a configured by arranging a plurality of plate-like members 210a in parallel is disposed between the ultraviolet lamp 125 and the coating layer 101, and in that state, the collimated ultraviolet rays 50 are emitted. A light diffusing element having a column structure can be obtained by irradiating the coating layer 101 formed on the process sheet 102 and moving on a conveyor (not shown).

On the other hand, when forming a louver structure, the upper surface of the coating layer formed on the process sheet can be stably formed simply by irradiating ultraviolet rays linearly using a linear light source. it can.
More specifically, as an ultraviolet irradiation apparatus in which a condensing cold mirror is provided on a linear ultraviolet lamp, an example is ECS-4011GX (manufactured by Eye Graphics Co., Ltd.) which is a commercial product. By placing a heat ray cut filter and a light-shielding plate at the place, ultraviolet rays consisting only of direct light whose irradiation angle is controlled are taken out and irradiated to the coating layer formed on the process sheet, and louvers A light diffusing element having a structure can be obtained.

Here, the parallel light means substantially parallel light that does not spread even when the direction of emitted light is viewed from any direction.
More specifically, for example, as shown in FIG. 9A, it is preferable to irradiate the coating layer 101 after the irradiation light 50 from the point light source 202 is converted into parallel light 60 by the lens 204.
Further, as shown in FIG. 9B, the irradiation light 50 from the linear light source 125 is collimated by the irradiation light collimating member 200 (200a) composed of a plurality of slit-shaped light shielding members (plate members) 210a. After setting to 60, the coating layer 101 is preferably irradiated.
Further, as shown in FIG. 9 (c), the irradiation light 50 from the linear light source 125 is converted into the parallel light 60 by the irradiation light collimating member 200 (200b) including the grid-shaped light shielding member (tubular member) 210b. After that, it is also preferable to irradiate the coating layer 101.

More specifically, the parallelism of the irradiation light as parallel light is preferably set to a value of 10 ° or less.
This is because the column structure can be formed efficiently and stably by setting the parallelism of the irradiation light to a value within this range.
Therefore, the parallelism of the irradiation light is more preferably set to a value of 5 ° or less, and further preferably set to a value within a range of 0 to 2 °.

Further, as the irradiation angle of the irradiation light, the irradiation angle (θ3) when the angle of the normal to the surface of the coating layer is 0 ° is usually preferably set to a value in the range of −80 to 80 °. .
The reason for this is that if the irradiation angle is outside the range of -80 to 80 °, the influence of reflection on the surface of the coating layer increases, and it may be difficult to form a sufficient column structure. Because.

Moreover, as irradiation light, an ultraviolet-ray, an electron beam, etc. are mentioned, However, It is more preferable to use an ultraviolet-ray.
The reason for this is that, in the case of electron beams, the polymerization rate is very fast, so the (A) component and the (B) component cannot be sufficiently separated in the polymerization process, making it difficult to form a column structure. Because. On the other hand, when compared with visible light or the like, ultraviolet rays are more abundant in ultraviolet curing resins that can be cured by irradiation and usable photopolymerization initiators. This is because the range of choices can be expanded.

Further, as the ultraviolet irradiation condition, it is preferable to set the peak illuminance on the surface of the coating layer to a value within the range of 0.1 to 10 mW / cm ² .
This is because when the peak illuminance is less than 0.1 mW / cm ² , it may be difficult to clearly form the column structure. On the other hand, when the peak illuminance exceeds 10 mW / cm ² , it hardens before the phase separation of the component (A) and the component (B) proceeds, and conversely, the column structure can be clearly formed. This is because it may be difficult.
Therefore, it is more preferably set to a value within the range of the peak irradiance 0.3~8mW / cm ² of the coating layer surface in the ultraviolet irradiation, further to a value within the range of 0.5~6mW / cm ² preferable.

Moreover, it is preferable to make the integrated light quantity in the coating layer surface in ultraviolet irradiation into the value within the range of 5-200 mJ / cm < ² >.
This is because when the integrated light quantity is less than 5 mJ / cm ² , it may be difficult to sufficiently extend the column structure from above to below. On the other hand, when the integrated light quantity exceeds 200 mJ / cm ² , the resulting light diffusion film may be colored.
Therefore, it is more preferably set to a value within the range of accumulated light amount of 7~150mJ / cm ² in the coating layer surface of the ultraviolet radiation, more preferably to a value within the range of 10 to 100 mJ / cm ^2.

In addition, in the light-diffusion film 100 '' shown in FIG.7 (b), 2nd pillar-shaped object 112a '' located in the 1st surface (front surface) 115 '' side, and 2nd surface (back surface) 116. In the case of forming the column structure 113 ″ including the deformed columnar body 112 ″ which is a combination with the first columnar body 112b ″ located on the “″ side, the ultraviolet irradiation is divided into two stages. Preferably it is done.
The reason for this is that a plurality of forested first pillars 112b ″ are formed in the low-refractive index photo-curing resin by the first-stage ultraviolet irradiation, and then an unformed region remains. In addition, it is because a plurality of second pillars 112a ″ standing in a low refractive index photocurable resin can be formed by the second stage ultraviolet irradiation.

(7) Haze value The incident angle of the incident light with respect to the normal of the diffusion film surface is determined along the moving direction of the coating layer when the coating layer formed by coating the composition for a light diffusing element into a film is photocured. When changing in the range of -70 to 70 °, the haze value for each incident angle is preferably 70% or more.
More specifically, the haze value (%) for each incident angle θ1 is changed according to ASTM while changing the incident angle θ1 with respect to the normal line of the diffusion film surface in the range of −70 to 70 ° along the moving direction of the coating layer. Measured according to D 1003.
For example, the haze value is measured by using a haze measuring device manufactured by BYK Co., Ltd., usually separating the integrated stage and the integrating sphere, and the interval between the stage and integrating sphere is 62 mm. The stage was rotated in a state of being arranged so as to be.
As a result, when the haze value with respect to each incident angle is a value of 70% or more when changed in the range of −70 to 70 °, external light incident from a wide range of angles is efficiently converted into image display light. As a result, it was found that the light can be diffusely emitted to the front of the display device.

  In the case of the measured diffusion film (equivalent to Example 1), the incident angle (θ1) = − 2 to 34 ° corresponds to the light diffusion incident angle region, and thus circular isotropic light diffusion occurs. The incident angle (θ1) = − 70 to −18 °, −18 to −2 °, 34 to 44 °, and 44 to 70 ° falls outside the light diffusion incident angle region. It has been found that crescent-shaped light diffusion occurs without diffusion.

5. Reflective Polarizing Element The reflective polarizing element is a member that has a function of reflecting a polarizing plate that transmits only polarized light that matches a predetermined polarization axis and light having other polarization axes.
Therefore, a linearly polarized reflective polarizing element that transmits one of orthogonal linearly polarized light and selectively reflects the other can be suitably used.
More specifically, as such a reflective polarizing element, a commercially available reflective polarizing film such as SHC-115R, SHC-125M, SHC-215M, EHC-125R (all manufactured by Polatechno Co., Ltd.) Wire grid Asahikasei WGF (manufactured by Asahi Kasei E-Materials Co., Ltd.), DBEF (manufactured by Sumitomo 3M Co., Ltd.) and the like can be suitably used.

6). Internal Light Source In the reflective liquid crystal display device 10 shown in FIG. 1, it is preferable that the internal light source 26 includes a light guide plate or an organic luminescence element provided with an LED at an end.
Such an internal light source 26 can reduce the disturbance of the polarization state caused by the internal light source itself, and can be used particularly suitably in the second and third embodiments described later.

7). Others In the reflective liquid crystal display device 10 of the present invention, it is preferable to further provide a retardation plate (not shown) for adjusting the transmission axis of the light (polarized light) transmitted through the absorptive polarizing element 12.
That is, according to the reflective liquid crystal display device 10 shown in FIG. 1, a retardation plate (a variable λ / 4 plate or a variable λ) for rotating the transmission axis of light (polarized light) transmitted through the absorption polarizing element 12 by 90 °. / 2 plate) is further provided on the back surface side (liquid crystal cell side) of the absorptive polarizing element 12, so-called black and white inversion display is possible.
Therefore, this makes it possible to easily match the monochrome display by the external light and the monochrome display by the internal light source.
That is, for example, by applying a variable λ / 4 plate to a predetermined location of the reflective liquid crystal display device 10, for example, the liquid crystal cell side located below the absorption polarizing element 12 shown in FIG. 3B, the image display shown in FIG. 3B can be reversed, as shown in FIG. 3C, that the voltage application portion is black display and the voltage non-application portion is white display. .

Here, it is preferable to use, for example, a uniaxially stretched film made of a cycloolefin resin, a polycarbonate resin, or the like as the variable λ / 4 plate that is a retardation plate. The retardation is, for example, in the range of 0.1 to 0.2 μm, and preferably corresponds to about ¼ of the wavelength of green light having the highest visibility with visible light.
The variable λ / 2 plate, which is another retardation plate, is preferably a uniaxially stretched film made of polycarbonate resin, for example. The retardation is preferably in the range of 0.2 to 0.3 μm, for example, and preferably corresponds to about ½ of the green light wavelength having the highest visibility with visible light.

[Second Embodiment]
As shown in FIGS. 10 and 11, the second embodiment of the present invention is similar to the first embodiment in that the absorptive polarizing element 12, the liquid crystal element 20 (14, 16, 18), and the light diffusing element 22. And a reflective polarizing element 24 and an internal light source 26 in order, wherein the light diffusing element 22 is made of a photocured material derived from the light diffusing element composition. A reflective liquid crystal which is a light diffusing film and has an internal refractive index distribution structure in which a region having a relatively low refractive index and a region having a relatively high refractive index are distributed. This is the display device 10 '.
In the second embodiment, as shown in FIGS. 10 and 11, when the absorptive polarizing element 12 is the first absorptive polarizing element, the light diffusing element 22 and the internal light source 26 are interposed. The reflective liquid crystal display device 10 ′ is characterized in that an absorption polarizing element 12b having the same transmission axis as that of the reflective polarizing element is provided as the second absorbing polarizing element.
Hereinafter, the reflective liquid crystal display device 10 ′ of the second embodiment will be described in detail with reference to the drawings with a focus on differences from the first embodiment.

1. Basic Configuration The basic configuration of the reflective liquid crystal display device 10 ′ of the second embodiment is the same as that of the first embodiment. However, when the absorptive polarizing element 12 is the first absorptive polarizing element, In addition to the first absorptive polarizing element 12, an absorptive polarizing element 12b having the same transmission axis as that of the reflective polarizing element is used as the second absorptive polarizing element. It is characterized by providing it in between.

2. In the case of the reflective liquid crystal display device 10 ′ according to the second embodiment, for example, in the daytime (measured value by a digital illuminometer) with an illuminance exceeding 100 Lux and about 1000 Lux, it is incident from above as shown in FIG. By using the external light (A, B), the reflective polarizing element 24 efficiently recognizes the reflected light (A ′) from the outside by switching the liquid crystal element 20 or the like, and white display can be performed.
When the external light is assumed to be 100%, in the white display, since the polarization of the liquid crystal element 20 is rotated by 90 °, only about 50% is absorbed by the absorptive polarizing element 12, and the reflective polarizing element 24. Therefore, the amount of white display light (A) is 50% as an example.

On the other hand, when black display is performed using external light, a predetermined voltage is applied to the liquid crystal layer 16 and the 90 ° rotation of the polarized light in the liquid crystal element 20 is not performed. By only transmitting through the absorptive polarizing element 12b, it is not transmitted through the second absorptive polarizing element 12b in relation to the polarization axis, and cannot be reflected, and is finally visible outside. It will not be possible.
That is, in the case of reflective display and black display, the second absorption polarizing element 12b prevents the generation of reflected light, which can be said to contribute to the improvement of the brightness of image display. .

On the other hand, for example, at night when the illuminance is less than 10 Lux, as shown in FIG. 11, the internal light source 26 provided on the back side is used, and the light (A ″, B ″) emitted therefrom is used. Utilizing the liquid crystal element 20 or the like, a part of the liquid crystal element 20 is completely cut off (X display) and displayed black while a part of the liquid crystal element 20 is transmitted (B ″) to display white. These can be combined to display a predetermined image.
That is, when using the internal light source 26 and displaying black, a part of the light (A ″) emitted from the internal light source 26 is transmitted through the second absorption polarizing element 12b as polarized light. The liquid crystal element 20 rotates the polarized light by 90 ° and does not pass through the first absorption-type polarizing element 12 in relation to the polarization axis, thereby enabling black display.

Conversely, when the internal light source 26 is used and white display is performed, at least part of the light (B ″) emitted from the internal light source 26 is transmitted through the second absorption polarization element 12b as polarized light. Next, the 90 ° rotation of the polarized light in the liquid crystal element 20 is not performed, and the first absorptive polarizing element 12 is transmitted in relation to the polarization axis, so that it can be visually recognized from the outside and white display is possible.
Therefore, in the reflective liquid crystal display device 10 ′ of the second embodiment, even in the case of image display using the internal light source 26, high brightness and good contrast can be obtained.

[Third embodiment]
As shown in FIGS. 12 and 13, the third embodiment of the present invention is similar to the first embodiment and the second embodiment in that the absorptive polarizing element 12 and the liquid crystal element 20 ( 14, 16, 18), a light diffusing element 22, a reflective polarizing element 24, and an internal light source 26, which sequentially includes a reflective liquid crystal display device 10 ″, A light diffusing film made of a photocured material derived from a composition for a diffusing element, and having an internal refractive index in which a region having a relatively low refractive index and a region having a relatively high refractive index are distributed This is a reflective liquid crystal display device 10 ″ which is a light diffusion film having a distribution structure.
In the third embodiment, as shown in FIGS. 12 and 13, when the absorptive polarizing element 12 is the first absorptive polarizing element, the third light source is disposed below (on the back side) the internal light source 26. This is a reflective liquid crystal display device 10 ″ provided with an absorptive polarizing element 12c having a transmission axis different from that of the reflective polarizing element 24 as an absorptive polarizing element.
Hereinafter, the reflective liquid crystal display device 10 ″ of the third embodiment will be described in detail with reference to the drawings with a focus on differences from the first embodiment and the second embodiment.

1. Basic Configuration The basic configuration of the reflective liquid crystal display device 10 ″ of the third embodiment is the same as that of the first embodiment and the second embodiment, but the absorption polarizing element 12 is replaced with the first absorption polarizing element. In addition to the first absorptive polarizing element, an absorptive polarizing element 12c having a transmission axis different from that of the reflective polarizing element is provided below the internal light source 26 (rear surface) as the third absorptive polarizing element. Side).

2. In the case of the reflective liquid crystal display device 10 ″ of the third embodiment, for example, in the case of daytime with illuminance of about 100 Lux, as shown in FIG. 12, external light (A, B) incident from above is applied. By utilizing the switching of the liquid crystal element 20 or the like, the reflective polarizing element 24 can efficiently visually recognize the reflected light (A ′) and display white.
That is, when white light is displayed using external light, the external light (B) is transmitted as polarized light while being partially absorbed by the first absorption polarizing element 12, but the polarized light in the liquid crystal element 20 is transmitted. Since the 90 ° rotation is performed, the polarization axis changes, and after passing through the light diffusing element 22, it is reflected by the reflective polarizing element 24, so that it can be visually recognized as white display.

On the other hand, when black light is displayed using external light, the external light (B) is transmitted as polarized light while being partially absorbed by the first absorptive polarizing element 12, but the polarized light in the liquid crystal element 20 is transmitted. Since the 90 ° rotation is not performed, the polarization axis does not change, and most of the external light (B) is transmitted through the light diffusing element 22 and the reflective polarizing element 24 and cannot be reflected. Eventually, the light is completely absorbed by the internal light source 26 and by extension, the third absorptive polarizing element 12c, and black is displayed without being visually recognized outside.
Therefore, in the reflective liquid crystal display device 10 ″ of the third embodiment, in the case of image display using outside light, high contrast and good contrast can be obtained.
In the case of image display using external light and black display, the third absorptive polarizing element 12c effectively prevents the generation of reflected light, and the brightness of the image display It can be said that it contributes to improvement.

On the other hand, for example, at night when the illuminance is less than 10 Lux, as shown in FIG. 13, the internal light source 26 provided on the back side is used, and the light (A ″, B ″) emitted therefrom is used. By using the liquid crystal element 20 and the like, the reflection type polarizing element 24 and the liquid crystal element 20 completely cut off (X display) and display black without being visually recognized. Part of the light (B ″) passes through the reflective polarizing element 24, the light diffusing element 22, and the liquid crystal element 20, is visually recognized outside, and can be displayed in white.
That is, when white display is performed using the internal light source 26, the reflected light is transmitted as polarized light while being partially reflected by the reflective polarizing element 24, but the polarized light is not rotated by 90 ° in the liquid crystal element 20. The axis does not change, and the first absorptive polarizing element 12 is transmitted and can be visually recognized as white display.

Further, when black display is performed using the internal light source 26, the reflected light is transmitted as polarized light while being partially reflected by the reflective polarizing element 24, but polarized light is rotated by 90 ° in the liquid crystal element 20. The axis changes, and finally, the first absorptive polarizing element 12 cannot be transmitted, and black display is possible without being visually recognized from the outside.
That is, in the reflective liquid crystal display device 10 ″ of the third embodiment, a predetermined image display with high brightness and good contrast can be performed even in the case of transmissive display using an internal light source.

As described above in detail, according to the reflective liquid crystal display device of the present invention, not only transmissive display using an internal light source but also reflective display using external light, in particular, external light incident from a wide range of angles. Light can be used as reflected light for efficient image display, and can be diffused and emitted to the front of the reflective liquid crystal display device without changing the polarization characteristics.
Therefore, the reflective liquid crystal display device of the present invention can be suitably applied to liquid crystal products used outdoors, such as smartphones, outdoor televisions, digital signage, and the like, and can contribute significantly to improving the quality of these. Be expected.

10: reflection type liquid crystal display device, 12, 12b, 12c: absorption type polarizing element, 20: liquid crystal element (14, 16, 18), 22: light diffusion element, 24: reflection type polarizing element, 26: internal light source, 50 : Irradiation light from light source, 60: parallel light, 100: light diffusion film, 101: coating layer, 102: process sheet, 112, 112 ′: columnar material, 112a ′: bent portion, 112a ″: second columnar shape 112b ″: first columnar body 113, 113 ′, 113 ″: column structure, 113a: boundary surface of the column structure, 114: low refractive index region, 115: first surface, 116: second 200: irradiation light collimating member, 202: point light source, 204: lens, 210: light shielding member, 210a: plate member, 210b: cylindrical member

Claims (8)

A reflective liquid crystal display device comprising an absorption polarizing element, a liquid crystal element, a light diffusing element, a reflective polarizing element, and an internal light source,
The light diffusing element is a light diffusing film made of a photocured material derived from the composition for a light diffusing element, and a region having a relatively low refractive index and a region having a relatively high refractive index are A reflection type liquid crystal display device comprising a light diffusion film having a distributed internal refractive index distribution structure.   In the light diffusing film, the region having a relatively low refractive index, the region having a relatively high refractive index, and having a column structure in which a plurality of pillars are erected in the film thickness direction of the film. The reflective liquid crystal display device according to claim 1, wherein   The reflective liquid crystal according to claim 2, wherein the diameter of the columnar object increases or the shape of the columnar object changes from one surface of the light diffusion film toward the opposite surface of the light diffusion film. Display device.   The composition for light diffusing elements comprises (meth) acrylic acid ester containing a plurality of aromatic rings as component (A), urethane (meth) acrylate as component (B), and light as component (C). The reflective liquid crystal display device according to claim 1, further comprising a polymerization initiator.   The reflection type according to any one of claims 1 to 4, further comprising a variable 1 / 4λ plate or a variable 1 / 2λ plate for rotating the transmission axis of the absorptive polarizing element by 90 °. Liquid crystal display device.   When the absorptive polarizing element is the first absorptive polarizing element, the second absorptive polarizing element is the same as the reflective polarizing element between the reflective polarizing element and the internal light source. 6. The reflective liquid crystal display device according to claim 1, further comprising: an absorptive polarizing element having a transmission axis of 1 to 5.   6. The third absorptive polarizing element having a transmission axis different from that of the reflective polarizing element is provided on a side opposite to the side facing the reflective polarizing element in the internal light source. The reflective liquid crystal display device according to one item.   The reflective liquid crystal display device according to any one of claims 1 to 7, wherein the internal light source is a light guide plate or an organic luminescence element including an LED at an end.

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