JP2017015766A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-reflection high-luminance image display device using an MEMS shutter device, which can achieve both of high front luminance and improved visibility by suppressing reflection of external light, and particularly, which gives high front luminance in a wide angle range while suppressing reflection of external light and can suppress color irregularity in a displayed image.SOLUTION: An image display device 10 includes a backlight 20 and an MEMS shutter device 34 having an opening 26 for transmitting light emitted from the backlight 20 and controlling the quantity of transmitted light by opening and closing the opening 26. The device has an absorption type polarizer 12 and a quarter-wave plate 14 successively disposed from a viewing side on the viewing side of the MEMS shutter device and has a reflection type polarizer 18 disposed on the backlight 20 side away from the quarter-wave plate 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image display apparatus using MEMS (Micro Electro Mechanical Systems), and more particularly, to an image display apparatus with low reflection and high brightness using a MEMS shutter device. In the present invention, MEMS is defined to refer to a microelectromechanical system.

In recent years, an image display device using a MEMS shutter device (hereinafter referred to as a MEMS display device) that does not use a color filter has been proposed for a liquid crystal display device using a color filter (Patent Document 1, Patent Document 2).
The conventional MEMS display device disclosed in Patent Literature 1 and Patent Literature 2 includes, for each pixel, a MEMS shutter device having an opening that transmits light emitted from a backlight and a MEMS shutter that opens and closes the opening. The MEMS shutter is opened and closed at high speed using a transistor, and the ratio of the opening and closing time is adjusted, so that the amount of transmitted light per minute unit is controlled, and thus the luminance value of each pixel is adjusted. The
Thus, an image can be displayed on the MEMS display device.
In this MEMS display device, for example, RGB light is emitted from the backlight in a time-sharing manner, and each color is transmitted through the opening by opening and closing each color with the MEMS shutter of the MEMS shutter device for each pixel. A color image can be displayed by controlling the amount of light and adjusting the color of the pixel.

Further, in this MEMS display device, by providing the opening of the MEMS shutter device in the reflecting plate, the light emitted from the backlight and not directly directed to the opening is bounced between the reflecting plate and the backlight. Since the opening can be transmitted through the opening, the use efficiency of the light emitted from the backlight is higher than that of the liquid crystal display device.
In addition, since this MEMS display device does not use a color filter, the use efficiency of light emitted from the backlight is higher than that of a liquid crystal display device that separates white light using the color filter.

Special table 2008-533510 gazette JP 2014-182221 A

By the way, as the display (display) screen of an image display device is becoming higher definition, the MEMS display device is also required to have a higher definition display screen.
For this reason, also in the conventional MEMS display devices disclosed in Patent Document 1 and Patent Document 2 described above, the aperture ratio of the opening portion of the MEMS shutter device has decreased with the increase in the definition of the display screen. For this reason, even in the conventional MEMS display device, the area ratio of the reflector metal forming the opening and the shutter metal part such as the MEMS shutter has increased, so that external light reflection on the metal surface on the viewing side of the shutter metal part is prevented. There has been a problem that visibility has deteriorated due to the increased reflected light from outside light.

In the conventional MEMS display device, particularly, the reflection of oblique light in which the reflected light is conspicuous particularly deteriorates the visibility of the display image.
Furthermore, when the MEMS shutter device is made high definition, the slit of the opening becomes on the order of microns (μ), and the influence of diffraction of reflected light and transmitted light cannot be ignored. As a result, the conventional MEMS display device has a problem that rainbow unevenness occurs in the display image.

The object of the present invention is to solve the above-mentioned problems of the prior art and to suppress the reflection of outside light greatly while maintaining high front luminance and maintaining high light use efficiency even if the display screen is made high definition. Visibility can be improved, and both high front luminance and improved visibility by suppressing external light reflection can be achieved, and in particular, high front luminance can be obtained in a wide angle range while keeping external light reflection low. An object of the present invention is to provide an image display device having a low reflection and a high luminance using a MEMS shutter device that can be used.
In addition to the above object, another object of the present invention is to provide an image display device using a MEMS shutter device that can suppress or eliminate uneven color of a displayed image even if the display screen is further refined. Is to provide.

  In order to achieve the above object, an image display device of the present invention includes a backlight that emits light, and an opening that transmits light emitted from the backlight, and opens and closes the opening to transmit the opening. An image display apparatus having a MEMS (micro electro mechanical system) shutter device for controlling the amount of light, wherein an absorption polarizer and a quarter-wave plate are sequentially arranged on the viewing side of the MEMS shutter device from the viewing side And a reflective polarizer disposed on the backlight side of the quarter-wave plate.

Here, the reflective polarizer is preferably disposed between the MEMS shutter device and the backlight.
Alternatively, the reflective polarizer is preferably disposed between the MEMS shutter device and the quarter wave plate.

The reflective polarizer is composed of a cholesteric liquid crystal layer, or is composed of a multilayer laminated polymer film or a wire grid polarizer and a second quarter-wave plate that are sequentially arranged from the backlight side. It is preferable.
The cholesteric liquid crystal layer is preferably a single layer or multiple layers.
The opening width of the opening of the MEMS shutter device preferably varies along the longitudinal direction of the opening, and the opening width continuously narrows in one direction along the longitudinal direction of the opening. It is preferable to change to.

  Furthermore, it is preferable to have a diffusion film disposed on the viewing side of the reflective polarizer and the MEMS shutter device and on the backlight side of the quarter-wave plate. It is preferable that the wave plate, the diffusion film, the MEMS shutter device, and the reflective polarizer are sequentially arranged from the viewing side toward the backlight.

  The MEMS shutter device includes a first position that covers the opening and blocks light emitted from the backlight, and a second position that opens the opening and transmits light emitted from the backlight. It is preferable to have a MEMS shutter that moves between them.

Advantageous Effects of Invention According to the present invention, even when the display screen is made high-definition, the MEMS shutter device can increase visibility by largely suppressing external light reflection while maintaining high light use efficiency and maintaining high front luminance. It is possible to provide a low-reflection and high-brightness image display device using the above-mentioned.
Further, according to the present invention, it is possible to achieve both high front luminance and improved visibility by suppressing external light reflection.
In addition, according to the present invention, high front luminance can be obtained in a wide angle range while keeping external light reflection low.
Furthermore, according to the present invention, even if the display screen is further refined, the uneven color of the display image can be suppressed or eliminated.

It is sectional drawing which shows typically an example of a structure of the image display apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows typically the structure of the MEMS display apparatus which consists of the MEMS shutter device and backlight of the image display apparatus shown in FIG. (A) And (B) is sectional drawing which shows typically the different operation state of the MEMS shutter device of the MEMS display apparatus shown in FIG. 2, respectively. (A) is sectional drawing which shows typically an example of the image display apparatus which concerns on Embodiment 1 of this invention, (B) is opening of the reflecting plate of the MEMS shutter device of the image display apparatus shown to (A). It is a top view which shows the shape of a part. It is sectional drawing which shows typically an example of the image display apparatus which concerns on Embodiment 2 of this invention. (A) is sectional drawing which shows typically an example of the image display apparatus which concerns on Embodiment 3 of this invention, (B) is opening of the reflecting plate of the MEMS shutter device of the image display apparatus shown to (A). It is a top view which shows the shape of a part. It is sectional drawing which shows typically an example of the image display apparatus which concerns on Embodiment 4 of this invention. It is sectional drawing which shows typically the image display apparatus of a comparative example.

  Hereinafter, an image display device and a method for manufacturing the image display device according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

First, an image display device according to the present invention will be described.
FIG. 1 is a cross-sectional view schematically showing an example of the configuration of an image display apparatus according to an embodiment of the present invention.
The image display apparatus 10 shown in the figure includes an absorption polarizer 12, a quarter-wave plate 14, a MEMS shutter device 16, a reflection polarizer 18, and a backlight 20 that are sequentially arranged from the viewing side. Have.

(MEMS display device)
First, a MEMS display device including the MEMS shutter device 16 and the backlight 20 will be described.
FIG. 2 schematically shows the configuration of the MEMS display device. 3A and 3B schematically show different operation states of the MEMS shutter device of the MEMS display device shown in FIG.
In FIG. 2, the MEMS shutter device 16 and the backlight 20 are shown corresponding to one pixel, but the MEMS shutter device 16 is provided for each pixel with respect to a large number of pixels. The light 20 is provided in common for many pixels.
The MEMS display device 22 has a configuration disclosed in Patent Documents 1 and 2 and the like, and includes a MEMS shutter device 16 and a backlight 20.

(Backlight)
The backlight 20 in the illustrated example includes, for example, LEDs (light emitting diodes, the same applies hereinafter) 24 (24R, 24G, and 24B) that emit light of three colors of R (red), G (green), and B (blue). And is configured to emit light of each color of RGB in a time division manner and radiate toward the opening 26 of the MEMS shutter device 16 of each pixel.
In the illustrated example, the LEDs 24 (24R, 24G, and 24B) are provided on the side surface of the backlight 20, and each color light of RGB incident from the side surface propagates in parallel to reach all the pixel regions, and in each pixel. In the orthogonal direction, the light is emitted from the upper surface of the backlight 20 toward the MEMS display device 22 for each pixel.

(MEMS shutter device)
The MEMS shutter device 16 in the illustrated example includes a transparent substrate 30 to which a reflection plate 28 including an opening 26 that transmits light emitted from the backlight 20 is attached for each pixel, and a predetermined number of times from a metal reflection plate 28. A metallic MEMS shutter 34 that is supported by a transparent substrate 30 via a metal spring 32 so as to be spaced apart from each other. Here, the reflecting plate 28, the spring 32, and the MEMS shutter 34 form a shutter portion 35, and transistors and wirings (not shown) for driving the shutter portion 35 and the MEMS shutter 34 of each pixel are made of metal.
The MEMS shutter 34 moves on the opening 26 of the reflector 28 in the direction of the arrow in the figure by displacing the spring 32 by a driving transistor (not shown) to which an electrical signal corresponding to the pixel signal of each color is applied. The part 26 is opened and closed at high speed.
In the illustrated example, the MEMS shutter 34 is configured by a metal plate-like member having two opening windows 36, and each opening window 36 has the same opening shape as the opening 26, and the shutter between the opening windows 36. The region 38 and the shutter region 38 outside each opening window 36 have a shape that covers and covers the opening 26.

As a result, as shown in FIG. 3A, when the shutter region 38 of the MEMS shutter 34 is at the first position (shutter closed position) immediately above the opening 26 of the reflector 28, the opening 26 is not spaced. Cover and block the light emitted from the backlight 20.
On the other hand, as shown in FIG. 3 (B), the MEMS shutter 34 moves from the first position shown in FIG. 3 (A) to the left side in the drawing, and one opening window 36 of the MEMS shutter 34 opens the reflector 28. When in the second position (shutter open position) immediately above the portion 26, the opening portion 26 is completely opened, and the light emitted from the backlight 20 is transmitted.
In the MEMS shutter device 16, the MEMS shutter 34 is opened and closed at a high speed, and the opening and closing time is controlled to control the amount of transmitted light, thereby adjusting the luminance value of each color. A color image can be displayed by controlling the luminance value of each color in each pixel of the MEMS display device 22.

The MEMS shutter device 16 of the MEMS display device 22 may be manufactured according to a conventionally known manufacturing process, for example, a manufacturing process disclosed in Patent Documents 1 and 2, and the manufacturing process is not particularly limited.
For example, a reflection plate 28 having an opening 26 of the shutter portion 35, a spring 32, and a photoresist serving as a MEMS shutter 34 are formed on the transparent substrate 30, a metal film is formed on the photoresist, and dry etching is performed. By applying this, the metal film is scraped off according to the shape of the reflector 28 having the opening 26, the spring 32, and the MEMS shutter 34, and thereafter, the entire surface thereof is covered with an insulating film, thereby completing the MEMS. The shutter device 16 is completed. At this time, it goes without saying that drive transistors, wirings, and the like (not shown) are also formed.

Although there is no restriction | limiting in particular as a photoresist used for MEMS formation used here, A conventionally well-known photoresist can be used. For example, the resist for forming MEMS disclosed in JP 2012-98557 A, 2012-181488, and JP 2012-208200 A related to the application of the present applicant can be given.
For example, as a resist for forming MEMS, (Component A) a monomer unit (a1) having a residue in which a carboxy group or a phenolic hydroxyl group is protected with an acid-decomposable group, and a monomer unit having an epoxy group and / or an oxetanyl group (A2) or the monomer unit (a1) and (a2) is further selected from the group consisting of an amino group, an amide group, an imide group, a sulfonimide group, a sulfonamide group, an imino group, a urethane bond and a ureido bond. A photosensitive resin composition comprising a polymer having a monomer unit (a3) having the above structure, (Component B) a photoacid generator, and (Component C) a solvent. These photosensitive resin compositions can be used as a photosensitive resin composition for MEMS structural members or as a photosensitive resin composition for etching resists, respectively. The photosensitive resin composition is preferably a positive photosensitive resin composition, particularly preferably a chemically amplified positive photosensitive resin composition (chemically amplified positive photosensitive resin composition).

For the MEMS structural members such as the reflector 28 having the opening 26 using the resist for the MEMS structural member, the spring 32, and the MEMS shutter 34, refer to the manufacturing method of the MEMS structural member disclosed in these publications. Can be produced.
For example, a film forming process for removing the solvent from the positive photosensitive resin composition to form a film, an exposure process for exposing the film to a pattern with actinic rays, and developing the exposed film with an aqueous developer to form a pattern A step of producing a structure using a pattern produced by a pattern production method including a developing step and a baking step of heating the pattern as a sacrificial layer at the time of stacking the structure, and the sacrificial layer for plasma treatment It is sufficient to manufacture the MEMS structure according to the method for manufacturing the MEMS structure including the removing step.

(Absorptive polarizer)
Next, in the present invention, as shown in FIG. 1, the absorption polarizer 12 is a member arranged on the most visible side. The absorptive polarizer 12 transmits a specific linearly polarized light component. The absorption polarizer 12 may be a member having such a function.
There is no restriction | limiting in particular in the kind of absorption type polarizer 12, The normal thing by which the protective film was bonded on both surfaces of the polarizing film can be used. A polarizing film can be used. For example, any of an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film can be used. The iodine-based polarizing film and the dye-based polarizing film are generally produced by adsorbing iodine or a dichroic dye to polyvinyl alcohol and stretching it.

(¼ wavelength plate)
In the present invention, the quarter-wave plate 14 is also called a λ / 4 plate, and is disposed on the backlight 20 side of the absorption polarizer 12 and integrated with the absorption polarizer 12 as shown in FIG. It is preferable to be used. At this time, it is preferable to use a reflective circularly polarizing plate as the reflective polarizer. The quarter-wave plate 14 is a birefringent element that generates a phase difference π / 2 (90 degrees) between orthogonally polarized components of incident light, and does not absorb light but changes only the phase. It is a kind of what is also called a phase plate or a phase difference plate.
The quarter-wave plate 14 is a member used for converting linearly polarized light into circularly polarized light, or conversely, converting circularly polarized light into linearly polarized light.

In the present invention, the quarter wavelength plate 14 forms a circularly polarizing plate in combination with the absorption polarizer 12.
Such a circularly polarizing plate composed of the absorption polarizer 12 and the quarter-wave plate 14 transmits the reflected light that is reflected from the viewing-side metal surface of the metallic reflector 28 by the external light incident on the display screen from the viewing side. And has a function of transmitting light emitted from the backlight 20 and transmitted through the opening 26 of the MEMS shutter device 16.
In particular, it is preferable to use a circularly polarizing plate having an oblique retardation Rth close to 0 (wide viewing angle) and having reverse dispersion characteristics. The reason is that by using such a circularly polarizing plate, the reflected light is not colored even with oblique light.

By the way, as shown in FIG. 8, in the conventional image display apparatus 60 which consists of the absorption type polarizer 12 and the quarter wavelength plate 14, and is a comparative example which does not have a reflection type polarizer, it is a display screen from a visual recognition side. When the external light is incident, the incident external light is specularly reflected by the metal surface on the viewing side of the reflector 28 having the opening 26 of the MEMS shutter device 16 and is emitted from the display screen as reflected light. For this reason, the deterioration of visibility is as described above as a problem of the prior art.
On the other hand, in the image display device 10 of the present invention shown in FIG. 1, when external light enters the display screen from the viewing side, the external light first enters the absorption polarizer 12 and is converted to linearly polarized light. Is done. Next, the converted linearly polarized light is incident on the quarter-wave plate 14, acts so as to generate a phase difference of π / 2 (90 degrees), and is converted into circularly polarized light. The converted circularly polarized light is specularly reflected by the metal surface on the viewing side of the reflection plate 28 of the MEMS shutter device 16 as in the case of the image display device 60 shown in FIG. This reflected light is incident on the quarter-wave plate 14 again, and the quarter-wave plate 14 acts so as to generate a phase difference π / 2 (90 degrees), and is converted into linearly polarized light.

Since circularly polarized light has the property that the direction of rotation does not change due to specular reflection, the phase difference for two round trips of the quarter-wave plate 14 is added, resulting in a total phase difference of π (180 degrees). It will be. The polarization direction of the linearly polarized reflected light having the phase difference π (180 degrees) that has been removed from the quarter wavelength plate 14 is the incident polarization direction of the external light incident on the quarter wavelength plate 14 from the viewing side, that is, , It is rotated by π / 2 (90 degrees) with respect to the polarization direction of the linearly polarized light converted by the absorption polarizer 12.
As a result, when the reflected light is incident on the absorbing polarizer 12, the reflected light cannot pass through the absorbing polarizer 12.
Thus, the circularly polarizing plate including the absorbing polarizer 12 and the quarter-wave plate 14 functions as an optical isolator for external light, and can greatly suppress external light reflection.

  The quarter-wave plate 14 used in the present invention can generate a phase difference of π / 2 (90 degrees) between orthogonal polarization components of incident light, and is combined with the absorption polarizer 12. As long as the function described above can be exhibited, any quarter wave plate may be used.

(Reflective polarizer)
The reflective polarizer 18 used in the present invention will be described.
The reflective polarizer 18 transmits a part of the incident light from the backlight and reflects a part thereof to increase the light utilization efficiency. From the quarter-wave plate 14 and the absorption polarizer 12, It is arranged on the backlight 20 side. The reflective polarizer 18 may be disposed on the viewing side from the MEMS shutter device 16, that is, between the quarter-wave plate 14 and the MEMS shutter device 16, or on the backlight 20 side from the MEMS shutter device 16. That is, it may be disposed between the backlight 20 and the MEMS shutter device 16.
In the present invention, the reflective polarizer 18 is preferably disposed on the backlight 20 side, that is, between the backlight 20 and the MEMS shutter device 16.
The reflective polarizer 18 used in the present invention is not particularly limited as long as it has the above-described function, and may be any reflective polarizer and may be composed of a single member. It may consist of members. Examples of the reflective polarizer 18 include a reflective circularly polarizing plate made of a cholesteric liquid crystal layer, a reflective linearly polarizing plate made of a multilayer laminated polymer film (for example, DBEF (Dual Brightness Enhancement Film)), and a quarter wavelength plate. And a combination of a wire grid polarizer and a quarter-wave plate.

  The reflective polarizer 18 has a function of converting light emitted from the backlight 20 into polarized light (circularly polarized light) that can be transmitted through the quarter-wave plate 14 and the absorption polarizer 12 arranged on the viewing side. It is what you have. In other words, the reflective polarizer 18 is linearly polarized so that the circularly polarized light itself emitted enters the quarter-wave plate 14 and a π / 2 (90 degree) phase difference is generated in the quarter-wave plate 14. When the light emitted from the backlight 20 incident on the right is converted so that the direction of polarization of the linearly polarized light coincides with the direction of polarization of the linearly polarized light converted by the absorption polarizer 12. Alternatively, the light is converted into circularly polarized light in a specific rotation direction on the left, for example, in the right rotation direction, and emitted.

The reflective polarizer 18 also transmits circularly polarized light in a rotational direction different from the specific rotational direction that could not pass through it, such as left rotational direction, and circularly polarized light in the specific rotational direction, such as right rotational direction. It is preferable to have a function of converting into light so that it can be emitted.
In other words, the reflective polarizer 18 converts half or approximately half of the incident light emitted from the backlight 20 into circularly polarized light in the specific rotation direction and emits the light. The remaining half or about half of the incident light is converted into circularly polarized light having a rotation direction opposite to the specific rotation direction and reflected, and the light is emitted between the exit surface of the backlight 20 and the incident surface of the reflective polarizer 18. In the reflection of the incident surface of the reflective polarizer 18, the light is repeatedly converted into circularly polarized light in the reverse rotation direction. Finally, the reflection in the specific rotation direction is performed. It is preferable that the light is converted into circularly polarized light and emitted.
By such light recycling by the reflective polarizer 18, the utilization efficiency of the emitted light from the backlight 20 can be further increased, and the display screen can be made brighter.

Hereinafter, embodiments using these reflective polarizers will be described.
(Embodiment 1)
4A is a cross-sectional view schematically showing an example of the image display apparatus according to Embodiment 1 of the present invention, and FIG. 4B is a MEMS shutter of the image display apparatus shown in FIG. It is a top view which shows the shape of the opening part of the reflecting plate of a device.
As shown in FIG. 4A, the image display device 10a includes a reflective circularly polarizing plate 40 made of a cholesteric liquid crystal layer as the reflective polarizer 18. As shown in FIG. 4B, the opening width of the opening 26 of the reflecting plate 28 of the MEMS shutter device 16 of the image display device 10a is constant.
In the present invention, the opening width of the opening 26 of the MEMS shutter device 16 is preferably 1 μm to 20 μm, and more preferably 5 μm to 15 μm.

Here, the image display device 10a shown in FIG. 4A uses a reflective circularly polarizing plate 40 as the reflective polarizer 18 of the image display device 10 shown in FIG. Since the MEMS shutter 34 of the omitted MEMS shutter device 16 has the same configuration, the same components are denoted by the same reference numerals and description thereof is omitted.
(Reflective type circularly polarizing plate)
The reflective circularly polarizing plate 40 composed of a cholesteric liquid crystal layer may have a single cholesteric liquid crystal layer that emits circularly polarized light, but is a laminate of two or more cholesteric liquid crystal layers. Also good. The single-layer cholesteric liquid crystal layer is preferably a cholesteric liquid crystal layer corresponding to the visible light region, and the corresponding visible light region is preferably as wide as possible. As the liquid crystal compound for forming the cholesteric liquid crystal layer, an appropriate one may be used, and there is no particular limitation, but a polymerizable liquid crystal compound is preferably used.

As the multi-layered cholesteric liquid crystal layer, a three-layer stacked cholesteric liquid crystal layer in which three cholesteric liquid crystal layers corresponding to RGB color lights are stacked can be used.
The reflective circularly polarizing plate 40 composed of such a three-layer laminated cholesteric liquid crystal layer has a reflection center wavelength in a wavelength band of 430 to 480 nm corresponding to the wavelength band of B (blue) light, and has a half width of 150 nm or less. A first light reflection layer having a peak of reflectivity and fixing a cholesteric liquid crystal phase emitting circularly polarized light, and a reflection center in a wavelength band of 500 to 600 nm corresponding to a wavelength band of G (green) light A second light-reflecting layer having a wavelength, having a reflectance peak with a half-width of 150 nm or less, and fixing a cholesteric liquid crystal phase emitting circularly polarized light; and a wavelength band of R (red) light A third light reflection layer having a reflection center wavelength in a corresponding wavelength band of 600 to 650 nm, a peak of reflectance having a half width of 150 nm or less, and a fixed cholesteric liquid crystal phase emitting circularly polarized light The It is preferably formed by a layer reflection type circular polarizing plate.

In the reflective circularly polarizing plate 40 composed of a three-layer laminated cholesteric liquid crystal layer, the light reflecting layer formed by fixing the cholesteric liquid crystal phase has at least one of right circularly polarized light and left circularly polarized light in a wavelength band near the reflection center wavelength. Can be reflected. Further, light in the first polarization state (for example, right circular polarization) is substantially reflected by the reflective circularly polarizing plate 40, while light in the second polarization state (for example, left circular polarization) is substantially reflected. Light in the second polarization state (for example, left circularly polarized light) that has passed through the reflective circularly polarizing plate 40 and has passed through the reflective circularly polarizing plate 40 is converted into linearly polarized light by the quarter-wave plate 14 and is an absorbing polarizer. 12 can be substantially transparent.
Here, the reflective circularly polarizing plate 40 preferably has a first light reflecting layer, a second light reflecting layer, and a third light reflecting layer. From the viewpoint of reducing the film thickness, the reflective circularly polarizing plate 40 has only the first light reflecting layer, the second light reflecting layer, and the third light reflecting layer as a layer formed by fixing the cholesteric liquid crystal phase. In other words, it is preferable not to have a layer formed by fixing other cholesteric liquid crystal phases.

The reflection center wavelength of the first light reflection layer is preferably in the wavelength band of 430 to 470 nm.
The full width at half maximum of the reflectivity peak of the first light reflecting layer is preferably 120 nm or less, more preferably the full width at half maximum of this reflectivity peak is 110 nm or less, and the full width at half maximum of this reflectivity peak is The thickness is particularly preferably 100 nm or less.

The reflection center wavelength of the second light reflection layer is preferably in the wavelength band of 520 to 560 nm.
The half width of the reflectance peak of the second light reflecting layer is preferably 120 nm or less, more preferably the half width of the reflectance peak is 110 nm or less, and the half width of the reflectance peak is The thickness is particularly preferably 100 nm or less.

The reflection center wavelength of the third light reflection layer is preferably in the wavelength band of 610 to 640 nm.
The full width at half maximum of the reflectivity peak of the third light reflecting layer is preferably 120 nm or less, more preferably the full width at half maximum of this reflectivity peak is 110 nm or less, and the full width at half maximum of this reflectivity peak is The thickness is particularly preferably 100 nm or less.
The wavelength that gives the peak (ie, the reflection center wavelength) can be adjusted by changing the pitch or refractive index of the cholesteric liquid crystal layer, but changing the pitch can be easily adjusted by changing the amount of chiral agent added. is there. Specifically, Fujifilm research report No. 50 (2005) pp. There is a detailed description in 60-63.

  The order of stacking the first, second, and third light reflecting layers will be described. Front brightness can be improved in any order. However, in the oblique orientation, coloring occurs due to the influence of the first, second, and third light reflecting layers. There are two reasons for this. The first reason is that the peak wavelength of the reflectance of the light reflecting layer shifts to the short wave side with respect to the front peak wavelength in the oblique direction. For example, a light reflection layer having a reflection center wavelength in the wavelength band of 500 to 600 nm shifts the center wavelength to the wavelength band from 400 to 500 nm in an oblique direction. Another reason is that the light reflecting layer acts as a negative C plate (positive retardation plate in Rth) in a wavelength region where the light reflecting layer does not reflect, so that coloring occurs due to retardation in an oblique direction. As a result of detailed examination of the reasons for these colorings in the configuration of the present invention, the present inventors have the most preferable arrangement order for suppressing coloring depending on the stacking order of the first, second, and third light reflecting layers. I found. That is, when viewed from the backlight unit (light source) side, the first light reflecting layer having the smallest wavelength is positioned on the light source side (Blue layer: B), and the third light reflecting layer having the next largest wavelength is positioned. (Red layer: R), and then the second light reflecting layer (Green layer: G) having an intermediate wavelength is most preferable. That is, in order from the backlight unit (light source) side, the order is BRG (first light reflecting layer, third light reflecting layer, second light reflecting layer).

The stacking order of the first, second, and third light reflecting layers is BRG (first light reflecting layer, third light reflecting layer, second light reflecting layer), BGR (first light reflecting layer) in order from the backlight unit side. One light reflecting layer, second light reflecting layer, third light reflecting layer), GBR (second light reflecting layer, first light reflecting layer, third light reflecting layer), GRB (second light reflecting layer) Light reflecting layer, third light reflecting layer, first light reflecting layer), RBG (third light reflecting layer, first light reflecting layer, second light reflecting layer) or RGB (third light reflecting layer) Layer, second light reflecting layer, first light reflecting layer);
BRG (first light reflecting layer, third light reflecting layer, second light reflecting layer), BGR (first light reflecting layer, second light reflecting layer, third light in order from the backlight unit side) The order of arrangement is preferably “reflective layer) or GBR (second light reflective layer, first light reflective layer, third light reflective layer);
More preferably, the arrangement order is BRG (first light reflecting layer, third light reflecting layer, second light reflecting layer) in order from the backlight unit side.

There is no particular limitation on the method for producing the light reflecting layer formed by fixing the cholesteric liquid crystal phase used in the reflective circularly polarizing plate 40. For example, JP-A-1-133003, JP-A-3416302, JP-A-3363565, The methods described in Kaihei 8-271731 can be used, and the contents of these publications are incorporated in the present invention.
The method described in JP-A-8-271731 will be described below.
In superimposing the cholesteric liquid crystal layers, it is preferable to use a combination that reflects circularly polarized light in the same direction. Thereby, it is possible to align the phase states of the circularly polarized light reflected by the respective layers and prevent different polarization states in the respective wavelength ranges, thereby increasing the light use efficiency.

(Polymerizable liquid crystal composition)
The polymerizable liquid crystal composition for forming the light reflection layer may contain other components such as a chiral agent, an alignment controller, a polymerization initiator, and an alignment aid in addition to the liquid crystal compound.
The light reflection layer can be obtained by applying the polymerizable liquid crystal composition to another layer such as a λ / 4 plate, another light reflection layer, a temporary support, or an alignment layer, and then curing the coating film.

(Liquid crystal compound)
Examples of the liquid crystal compound include a rod-like liquid crystal compound and a disk-like liquid crystal compound.
Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used.

  It is more preferable to fix the orientation of the rod-like liquid crystal compound by polymerization, and examples of the polymerizable rod-like liquid crystal compound include those described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, WO 95/22586, 95/24455. Publication No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469, No. 11-80081 The compounds described in the gazette and Japanese Patent Application No. 2001-64627 can be used. Further, as the rod-like liquid crystal compound, for example, those described in JP-T-11-513019 and JP-A-2007-279688 can be preferably used.

  As the discotic liquid crystal compound, for example, those described in JP-A-2007-108732 and JP-A-2010-244038 can be preferably used, but are not limited thereto.

<Preparation of broadband light reflection layer>
Examples of a method for widening the reflection band of the light reflection layer to make it a wide band include use of a high Δn liquid crystal compound and a pitch gradient method.
Δn is the birefringence of the liquid crystal compound. For example, in the case of a rod-like liquid crystal compound, it is the difference in refractive index between the minor axis and the major axis of the compound.
The liquid crystal compound used in the light reflecting layer formed by fixing the cholesteric liquid crystal phase is practically about 0.06 ≦ Δn ≦ 0.5 (the high Δn liquid crystal material described in JP 2011-510915 A can be used). Yes, corresponding to 15 to 150 nm in half width. Further, examples of the high Δn liquid crystal compound include compounds described in Japanese Patent No. 3999400, Japanese Patent No. 4053782, Japanese Patent No. 4947676, and the like, but are not limited thereto. The method of paragraph [0112] of Japanese Patent No. 40537882 and paragraph [0142] of Japanese Patent No. 4947676 can be referred to for the method of measuring Δn.
When manufacturing by controlling the half-value width of 200 nm or less, a pitch gradient method that can realize a wide half-value width can be used by gradually changing the number of pitches in the cholesteric spiral direction instead of a single pitch. The pitch is the pitch length P of the helical structure in the cholesteric liquid crystal phase, and means the thickness of the molecular layer when the orientation direction of the molecular layer of the liquid crystal compound is rotated 360 degrees.

From the viewpoints of half-width expansion and film thickness reduction (thinning) with a pitch gradient, Δn is preferably 0.16 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and particularly preferably the present situation. The upper limit of Δn of the industrialized liquid crystal is about 0.5. However, if further high Δn liquid crystal compounds are developed in the future, they can be applied to the present invention in principle and can be made thinner.
In the case of using a liquid crystal compound having a Δn of 0.156 from the viewpoint of luminance performance, and having at least a pitch gradient band of 400 to 600 nm, the film thickness of the wideband pitch gradient layer is preferably 6 μm or more, and 8 μm or more. More preferably, 10 μm or more is even more preferable. In the case of using a liquid crystal compound having Δn of 0.3 and having at least a pitch gradient band of 400 to 600 nm, the film thickness is preferably 2 μm or more, more preferably 3 μm or more, further preferably 4 μm or more, and 5 μm or more. Is particularly preferred.

  It is known that it is preferable that the Δn dispersion of the liquid crystal has a small dispersion at each wavelength. Preferably Δn (450/550 ratio) ≦ 1.6, more preferably Δn (450/550 ratio) ≦ 1.4, more preferably Δn (450/550 ratio) ≦ 1.2, particularly preferably Δn. (450/550 ratio) ≦ 1.1.

In the pitch gradient method, a wide half-value width can be realized by gradually changing the pitch in the spiral direction (normal film thickness direction) of the cholesteric liquid crystal phase. In the light reflection layer to which the pitch gradient method is applied, it is preferable that the pitch continuously changes in the film thickness direction. Moreover, in the light reflection layer to which the pitch gradient method is applied, it is preferable that the pitch continuously increases or decreases continuously from one surface of the layer to the other surface. In the pitch gradient method, the concentration of a compound that does not form a spiral in the thickness direction of the liquid crystal layer is continuously changed in the thickness direction of the liquid crystal layer, or the concentration of the chiral agent is continuously changed in the thickness direction of the liquid crystal layer. Alternatively, use a chiral agent with a photoisomerization moiety, and change the HTP (helical twisting power) of the chiral agent by isomerizing the photoisomerization part of the chiral agent with UV irradiation etc. when forming the light reflection layer. To achieve this. As this photoisomerization moiety, a vinylene group, an azo group, or the like is preferable.
As the pitch gradient method, those described in (Nature 378, 467-469 1995), Japanese Patent No. 4990426, Japanese Patent Application Laid-Open No. 2005-265896, and the like can be applied. Moreover, the compound which does not form a helix and has a fluorinated alkyl group as described in Japanese Patent No. 4570377 can also be used.
As the reflection-type circularly polarizing plate 40 composed of the laminated type cholesteric liquid crystal layer as described above, the one described in the specification of PCT / JP2015 / 053904 according to the applicant's application can also be used.

(Embodiment 2)
FIG. 5 is a cross-sectional view schematically showing an example of an image display apparatus according to Embodiment 2 of the present invention.
An image display device 10b according to the second embodiment illustrated in FIG. 5 includes a quarter-wave plate 42 and a linearly polarized multilayer multilayer polymer film (DBEF) 44 as the reflective polarizer 18 of the image display device 10 illustrated in FIG. The other configuration is the same including the opening width of the opening portion 26 of the MEMS shutter device 16 and the reflecting plate 28 of the MEMS shutter device 16 (not shown). The description is omitted.
The quarter-wave plate 42 of the reflective polarizer 18 has basically the same structure and function as the quarter-wave plate 12.

  The multilayer laminated polymer film 44 is made of a birefringent interference polarizer that reflects and polarizes a part of incident light incident on the surface thereof and transmits the remainder of the incident light. The birefringent interference polarizer includes first and second polymers in a first plane different from the refractive index mismatch between the first and second polymer materials in a second plane perpendicular to the first plane. It includes multiple alternating orientation layers of first and second polymeric materials each having a non-zero stress optical coefficient that are sufficiently different to produce a refractive index mismatch between the materials. As such a birefringence interference polarizer, the one disclosed in JP-A-4-268505 can be used.

Here, the light emitted from the backlight 20 enters the multilayer laminated polymer film 44, and half or approximately half of the light is converted into linearly polarized light (P-polarized light: P-wave) and transmitted, and the remaining half. Alternatively, about half of the light is reflected as different linearly polarized light (S-polarized light: S-wave). The S-polarized light reflected by the incident surface of the multilayer laminated polymer film 44 is reflected by the exit surface of the backlight 20 and enters the multilayer laminated polymer film 44 again. It is reflected again. The reflected P-polarized light is reflected again from the emission surface of the backlight 20, enters the multilayer laminated polymer film 44 again, and passes through the multilayer laminated polymer film 44. As described above, the multilayer laminated polymer film 44 can be repeatedly recycled by reflecting the reflected linearly polarized light and finally transmitted to improve the light utilization efficiency and increase the display luminance.
On the other hand, the P-polarized light transmitted through the multilayer laminated polymer film 44 enters the quarter-wave plate 42 and is converted into circularly-polarized light that can be transmitted through the quarter-wave plate 14 and the absorption polarizer 12. , Is incident on the quarter-wave plate 14, is converted back to linearly polarized light having a polarization orientation that matches the polarization orientation of the absorption polarizer 12, enters the absorption polarizer 12, and passes through the absorption polarizer 12. .
Thus, the reflective polarizer 18 comprising the combination of the multilayer laminated polymer film 44 and the quarter wavelength plate 42 is maintained without impeding the low diplomatic reflection due to the combination of the quarter wavelength plate 14 and the absorbing polarizer 12. Thus, high luminance can be obtained in a wide angle range.

In the image display device 10b of the second embodiment, a linearly polarized wire grid polarizer may be used instead of the multilayer laminated polymer film 44 of the reflective polarizer 18.
When the arrangement period of the wires is shorter than the wavelength, the wire grid polarizer reflects light polarized so as to be parallel to the wire grid (for example, S-polarized light; S-wave), and is polarized so as to be orthogonal ( For example, S polarized light (electromagnetic wave) can be transmitted.
As such a wire grid type polarizer, the wire grid type polarizer disclosed in JP 2001-330728 A and JP 2006-84776 A can be used.

For example, it has a substrate that does not transmit light in a specific wavelength range and a photoresist layer provided on both the front and back sides of the substrate, and the photoresist layer has a parallel relationship with each other on both the front and back sides of the substrate. A parallel line pattern is formed by multiple irregularities, and a metal such as aluminum is vapor-deposited only on and near the tops of the convex portions of the parallel line pattern formed on the front and back surfaces of the substrate, and the wires are formed on both surfaces of the substrate. The wire grit type | mold polarizer in which the grit is formed can be mentioned.
Such a wire grid polarizer uses light in a wavelength range that does not transmit through a plurality of parallel substrates, and after exposing a plurality of parallel line patterns on one surface of the substrate by light interference, A plurality of parallel line patterns are exposed and developed by light interference on the other surface so as to be parallel to the parallel line pattern provided on the surface, and a parallel line pattern with a plurality of irregularities is formed on both front and back surfaces of the substrate, It can be manufactured by forming a wire grit by depositing a metal only on and near the top of the convex portion of the parallel line pattern formed by the unevenness formed on both the front and back surfaces of the substrate.

In addition, the periodicity of the metal lattice formed on the substrate and on the substrate is made of a material type such as silicon (Si), SiO2, quartz glass, nickel (Ni), platinum (Pt), chromium (Cr), or a polymer material. A wire grid type polarizer including a metal lattice pattern having a thickness of 120 nm or less can be given.
In such a wire grid polarizer, first, a mold is manufactured, a metal thin film and a polymer are formed on a substrate in a predetermined order, and then the polymer is molded using the mold, and the molded polymer is formed. After forming the metal lattice pattern by etching the metal thin film using the polymer, the polymer can be removed to manufacture a wire grid polarizer.

(Embodiment 3)
6A is a cross-sectional view schematically showing an example of an image display device according to Embodiment 3 of the present invention, and FIG. 6B is a MEMS shutter of the image display device shown in FIG. 6A. It is a top view which shows the shape of the opening part of the reflecting plate of a device.
As shown in FIGS. 6A and 6B, the image display device 10c includes the image display device 10a shown in FIGS. 4A and 4B and the reflection of the MEMS shutter device 16 shown in FIG. 6B. Since the shape of the opening 46 of the plate 48 is the same as that of the opening 26 of the reflecting plate 28 shown in FIG. 4B, it has the same configuration. The description is omitted.

As shown in FIG. 6B, the opening width of the opening 46 of the reflector 48 of the MEMS shutter device 16 of the image display device 10a is not constant, but continuously in one direction along the longitudinal direction of the opening 46. It is changing to become narrower.
In the illustrated example, the opening shape of the opening 46 of the reflecting plate 48 is trapezoidal, and the opening width of the opening 46 is changed so that both sides continuously narrow in one direction along the longitudinal direction. It may change only on one side, or at least one of them may change in stages, change in a curve, narrow or wide Or may change at random, but it is preferable to change continuously.

In the present invention, the opening width of the opening 46 of the reflecting plate 48 is preferably 1 μm to 20 μm, and more preferably 2 μm to 15 μm.
Further, the difference between the maximum width and the minimum width of the opening width of the opening 46 is preferably set according to the wavelength width of the visible light region, preferably 1 μm to 10 μm, and more preferably 1 μm to 5 μm. preferable.
In the present invention, by changing the opening width of the opening 46 of the reflecting plate 48 instead of being constant, the wavelength dependence of the diffraction angle due to the opening width of the opening 46 is alleviated and color unevenness such as rainbow unevenness is suppressed. be able to.

(Embodiment 4)
FIG. 7 is a cross-sectional view schematically showing an example of an image display apparatus according to Embodiment 3 of the present invention.
As shown in FIG. 7, in the image display device 10d, the diffusion film 50 is disposed between the image display device 10a shown in FIG. 4A, the quarter-wave plate 14 and the MEMS shutter device 16. Other than the above, since they have the same configuration, the same components are given the same numbers, and the description thereof is omitted.
The diffusion film 50 needs to be arranged on the viewing side from the reflective circularly polarizing plate 40 (18) and the MEMS shutter device 16 and on the backlight 20 side from the quarter-wave plate 14. For example, when the reflective circularly polarizing plate 40 is disposed on the viewing side from the MEMS shutter device 16, it is necessary to be disposed between the reflective circularly polarizing plate 40 and the quarter wavelength plate 14.

The diffusion film 50 is not particularly limited as long as color unevenness such as rainbow unevenness due to the opening width of the opening 46 can be alleviated. Those that do not solve the problem are preferred.
For example, since it can be said that the degree of depolarization and the turbidity of the film are related, when the degree of depolarization of 50 of the diffusion film is converted into a haze value representing the turbidity of the film, The haze value of 50 is preferably 30% to 95%.
Strictly speaking, the depolarization degree and the haze value of 50 of the diffusion film are good. In this case, the degree of depolarization 50 of the diffusion film is preferably 0.4 or less, more preferably 0.2 or less.
The degree of depolarization is also called Depolarization Index, and can be measured with Axoscan from Axometrics.
The image display device of the present invention is basically configured as described above.

The image display apparatus of the present invention will be specifically described based on examples.
Example 1
As Example 1, prior to manufacturing the image display device 10a having the configuration of Embodiment 1 shown in FIGS. 4A and 4B, each component of the image display device 10a was manufactured as follows.

(Production of MEMS shutter device 16)
First, in accordance with the method described in Examples of Japanese Patent Application Laid-Open No. 2012-208200, the photosensitive resin composition obtained in Example 1 was used as a sacrificial layer, and the MEMS shutter was manufactured by the method described in Japanese Translation of PCT International Publication No. 2008-533510. Device 16 was fabricated. The width of the opening 26 was made to be 15 μm.
(Preparation of backlight 20)
After disassembling a commercially available liquid crystal television (REGZA (registered trademark) 50Z9X manufactured by Toshiba), taking out the backlight unit and assembling it in the order of the reflector, light source, and diffuser toward the light output side, Light 20 was used.

(Preparation of absorption polarizer 12)
Next, the absorptive polarizer 12 was manufactured in the same manner as [0219] to [0220] of JP-A-2006-293275.
(Preparation of λ / 4 plate 14)
A broadband λ / 4 plate 14 was prepared in the same manner as [0020] to [0033] of JP-A-2003-262727. The broadband λ / 4 plate 14 was obtained by applying two layers of liquid crystal material on a base material and peeling it from the base material after polymerization.
The obtained broadband λ / 4 plate 14 had Re (450) of 110 nm, Re (550) of 135 nm, Re (630) of 140 nm, and a film thickness of 1.6 μm.
The obtained broadband λ / 4 plate 14 and the absorptive polarizer 12 produced above were bonded together using an acrylic adhesive having a refractive index of 1.47.

(Preparation of reflective circularly polarizing plate 40 (18) comprising a single layer cholesteric liquid crystal layer)
First, a terminal fluorinated alkyl group-containing polymer (compound A) having an optically active site was obtained by the procedure described in Japanese Patent No. 4570377 [0065]. Specifically, Compound A was obtained as follows.
To a four-necked flask equipped with a condenser, a thermometer, a stirrer, and a dropping funnel, a fluorinated solvent AK-225 (Asahi Glass Co., Ltd., 1,1,1,2,2-pentafluoro-3,3-dichloropropane: 1 , 1,2,2,3-pentafluoro-1,3-dichloropropane = 1: 1.35 (molar ratio) mixed solvent)) 50 parts by mass, a reactive chiral agent (compound) having optical activity of the following structure 7. In the formula, * indicates an optically active site) 5.22 parts by mass are charged, the reaction vessel is heated to 45 ° C., and then 10 mass of diperfluoro-2-methyl-3-oxahexanoyl peroxide / AK225 6.58 parts by mass of a% solution was added dropwise over 5 minutes. After completion of dropping, the reaction is carried out in a nitrogen stream at 45 ° C. for 5 hours, and then the product is concentrated to 5 ml, reprecipitated with hexane, and dried to contain a terminal fluorinated alkyl group-containing polymer. (Compound A) 3.5 parts by mass (yield 60%) was obtained.
When the molecular weight of the obtained polymer was measured using GPC and THF (tetrahydrofuran) as a developing solvent, Mn = 4,000 (Mw / Mn = 1.77), and the fluorine content was measured to determine the fluorine content. Was 5.89% by mass.

<Composition for forming cholesteric liquid crystal layer (A)>
Compound 8 8.2 parts by mass of Compound 9 0.3 parts by mass of a terminal fluorinated alkyl group-containing polymer having an optically active site prepared earlier (Compound A)
1.9 parts by mass Methyl ethyl ketone 24.0 parts by mass

Compound 7

When the cross section of the cholesteric liquid crystal layer (A) was observed with a scanning electron microscope, it had a structure having a helical axis in the normal direction of the layer and a continuously changing cholesteric pitch. Here, regarding the cholesteric pitch, when the cross section of the cholesteric liquid crystal layer is observed with a scanning electron microscope, the width in the layer normal direction of the light portion and the dark portion repeated twice (brightness, darkness, and darkness) is counted as one pitch.
If the surface side with a small cholesteric pitch is defined as the x plane and the surface with the large surface is defined as the y plane, the result calculated from the measured cholesteric pitch is that the cholesteric reflection wavelength near the x plane is 410 nm, and the cholesteric near the y plane is The reflection wavelength of was 700 nm.

(Production of MEMS display)
The backlight 20 thus prepared, the reflective circularly polarizing plate 40 (18) composed of a single-layer cholesteric liquid crystal layer, the MEMS shutter device 16, the λ / 4 wavelength plate 14, and the absorptive polarizer 12 are assembled in this order. An image display device 10a having the configuration shown in FIGS. 4A and 4B was manufactured as one MEMS display. Table 1 shows the configuration of the manufactured image display device 10a.

Evaluation of the image display device 10a of Example 1 manufactured in this way was performed for the following three items. The results are shown in Table 1.
(External light reflection)
As a characteristic for evaluating external light reflection, three researchers conducted a sensory evaluation of character visibility in a light place (under 900 lux environment) with reference to the method described in JP-A-2010-8475 [0040]. If the evaluations of the three researchers did not agree, a majority decision was made.
A: There is no blur of characters due to external light reflection, and there is no problem in visibility.
B: Character blurring level (acceptable).
C: A level in which characters are blurred due to external light reflection and there is a problem in visibility.

(Front brightness)
The front luminance during white display was measured using a luminance meter (SR3 manufactured by TOPCON). The relative luminance when the luminance of the comparative example was 100% was used as an evaluation index.
A: 95% or more: Excellent B: 90% or more and less than 95%: Slightly inferior (allowable)
C: Less than 90% :: Inferior (rainbow unevenness)
Three researchers visually evaluated the rainbow-like unevenness (rainbow unevenness) observed when the viewing angle was swung during white display. If the evaluations of the three researchers did not agree, a majority decision was made.
A: Rainbow unevenness is not observed.
B: A level at which rainbow unevenness is slightly observed but not worrisome (acceptable).
C: Level at which rainbow unevenness becomes a conspicuous problem.

(Comparative Example 1)
As Comparative Example 1, the backlight 20 and the MEMS shutter device 16 prepared when the image display device 10a of Example 1 was manufactured were assembled, and the image display device 60 having the configuration shown in FIG. 8 was manufactured. The configuration is shown in Table 1.
The image display device 60 of Comparative Example 1 was evaluated for the above three items in the same manner as in Example 1. The results are shown in Table 1.

(Example 2)
As Example 2, as a reflective circularly polarizing plate 40 (18) of the image display device 10a having the configuration of Embodiment 1 shown in FIG. 4A, a multilayer laminated cholesteric instead of the single-layer cholesteric liquid crystal layer of Example 1 is used. An optical sheet having a liquid crystal layer was prepared and used.
(Preparation of optical sheet consisting of multilayer cholesteric liquid crystal layer)

<Production of support (production of cellulose acylate dope)>
The following composition was put into a mixing tank and stirred to dissolve each component, and a cellulose acetate solution was prepared to prepare a cellulose acylate dope.
――――――――――――――――――――――――――――――――
Cellulose acetate solution composition ――――――――――――――――――――――――――――――――
Cellulose acetate (substitution degree 2.88) 100 parts by mass P-1 12 parts by mass UV absorber (UV-1) 1.8 parts by mass UV absorber (UV-2) 0.8 parts by mass L-1 3 parts by mass Methylene chloride 501.1 parts by mass Methanol 74.9 parts by mass ――――――――――――――――――――――――――――――――
P-1 is a mixture of triphenyl phosphate (TPP) / biphenyl diphenyl phosphate (BDP) = 2/1 (mass ratio).

Furthermore, 3.6 parts by mass of the following matting agent dispersion was added to 100 parts by mass of the cellulose acylate dope.
(Matting agent dispersion)
Silica particle dispersion (average particle size 16 nm) 0.7 parts by mass Methylene chloride (first solvent) 75.5 parts by mass Methanol (second solvent) 6.5 parts by mass The above dope 17.3 parts by mass

(Preparation of cellulose acylate film)
The cellulose acylate dope was cast on a drum at 20 ° C. from the casting port. It peeled off in the state of solvent content rate of about 20 mass%, and it dried, fixing the both ends of the width direction of a film with a tenter clip. Then, it dried further by conveying between the rolls of a heat processing apparatus, and produced the cellulose acylate film (CTA1) which has a film thickness of 15 micrometers.

The surface of the CTA1 support was subjected to alkali saponification treatment according to the following procedure.
(Alkaline saponification treatment)
The film was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. Thereafter, an alkali solution having the composition shown below was applied to one side of the film using a bar coater at a coating amount of 10 ml / m ² and heated to 105 ° C. The heated film was conveyed for 10 seconds under a steam far-infrared heater manufactured by Noritake Company Limited. Subsequently, 3 ml / m ^{2 of} pure water was applied using the same bar coater. Further, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was transported to a drying zone at 70 ° C. for 10 seconds and dried to produce an alkali saponified film.

──────────────────────────────────
Alkaline solution composition ──────────────────────────────────
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight Isopropanol 63.7 parts by weight Surfactant SF-1: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H 1.0 part by weight Propylene glycol 14. 8 parts by mass ──────────────────────────────────

(Formation of alignment film)
On the surface opposite to the coating type polarizer surface of TGH1 produced as described above, an alignment film coating solution having the following composition was continuously applied with a # 12 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The obtained coating film was continuously rubbed to obtain a TGH-Y film. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.
──────────────────────────────────
Composition of alignment film coating solution ──────────────────────────────────
Modified polyvinyl alcohol 1 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.3 parts by weight ───────── ────────────────────────

<Formation of λ / 4 plate using discotic liquid crystal compound>
A coating liquid A1 containing a discotic liquid crystal compound having the following composition was continuously applied on TGH-Y on which an alignment film was formed, with a wire bar of # 3.2. The conveyance speed (V) of the film was 40 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the discotic liquid crystal compound, it was heated with hot air at 60 ° C. for 80 seconds. Subsequently, UV irradiation was performed at 60 ° C. to fix the orientation of the liquid crystal compound and form an optically anisotropic layer. At this time, the UV irradiation amount was 300 mJ / cm ² . This film was designated as TGH-ZA.
──────────────────────────────────
Coating liquid A1 containing discotic liquid crystal compound
――――――――――――――――――――――――――――――――――
Discotic liquid crystal compound (Compound 101) 80 parts by mass Discotic liquid crystal compound (Compound 102) 20 parts by mass Alignment aid 1 0.9 parts by mass Alignment aid 2 0.1 parts by mass Megafac F444 (manufactured by DIC) 0. 12 parts by weight polymerization initiator 1 3 parts by weight methyl ethyl ketone 301 parts by weight ──────────────────────────────────

<Formation of cholesteric liquid crystal layer using discotic liquid crystal compound>
A first light reflecting layer as a light reflecting layer obtained by fixing a cholesteric liquid crystal phase using a discotic liquid crystal compound as a liquid crystal compound by the following method on the surface of a λ / 4 plate of TGH-ZA produced by the above method Formed. The conveyance speed (V) of the film was 30 m / min.
A coating liquid B1 containing a discotic liquid crystal compound having the following composition was adjusted to a thickness of 3.05 μm on the surface of the prepared alignment film and continuously applied.
Subsequently, heat aging was performed at 113 ° C. for 2 minutes to obtain a uniform alignment state.
A light reflection layer was formed by irradiating with ultraviolet rays in a nitrogen atmosphere using a metal halide lamp manufactured by Aigra. At this time, the UV irradiation amount was 200 mJ / cm 2. The produced film was designated as TGH-ZB.

──────────────────────────────────
Composition of coating liquid (B1) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――
Discotic liquid crystal compound (Compound 101) 80 parts by mass Discotic liquid crystal compound (Compound 102) 20 parts by mass Polymerizable monomer 1 2 parts by mass Megafac F444 (manufactured by DIC) 0.15 parts by mass Polymerization initiator 1 3 parts by mass chiral Agent 1 5 parts by weight methyl ethyl ketone 214 parts by weight cyclohexanone 66 parts by weight tert butyl alcohol 50 parts by weight ――――――――――――――――――――――――――――――― ―――

Chiral agent 1

<Formation of Pitch Gradient Cholesteric Liquid Crystal Layer Using High Δn Rod-shaped Liquid Crystal Compound>
On the cholesteric liquid crystal layer composed of the TGH-ZB disc-like liquid crystal produced by the above method, the coating liquid B4 containing a rod-like liquid crystal compound having the following composition is adjusted to a film thickness of 5 μm and continuously applied. did. The conveyance speed (V) of the film was 20 m / min.
In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, it was heated with a warm air of 110 ° C. for 120 seconds. Subsequently, UV irradiation was performed at 100 ° C. with an irradiation amount of 20 mJ / cm 2. Thereafter, as orientation ripening, heating was performed with warm air at 80 ° C. for 120 seconds. Subsequently, UV irradiation was performed at 70 ° C. with an irradiation amount of 350 mJ / cm 2 to form a light reflection layer.

――――――――――――――――――――――――――――――――――
Coating liquid B4 containing a rod-like liquid crystal compound
――――――――――――――――――――――――――――――――――
Rod-shaped liquid crystal compound 204 100 parts by mass polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd. 1 part by weight polymerization initiator 1 4 parts by weight surfactant 2 0.05 parts by weight surfactant 3 0.01 parts by weight Part chiral agent 2 3.5 parts by weight methyl ethyl ketone 200 parts by weight cyclohexanone 20 parts by weight ――――――――――――――――――――――――――――――――― -

Rod-shaped liquid crystal compound 204

Chiral agent 2

  By the above procedure, a pitch gradient cholesteric liquid crystal layer (5 μm), a cholesteric liquid crystal layer using a discotic liquid crystal compound (3 μm), a λ / 4 layer (1 μm), a PVA alignment film (0.5 μm), TAC (15 μm), An optical sheet used in Example 2 having a PVA alignment film (0.5 μm) and a coating type polarizer (0.2 μm) in this order was obtained.

The optical sheet having the multilayered cholesteric liquid crystal layer thus obtained was used as the reflective circularly polarizing plate 40 (18) instead of the single-layer cholesteric liquid crystal layer of Example 1, and the same as in Example 1 was used. An image display device 10a was produced. The configuration is shown in Table 1.
The image display device 10a of Example 2 was evaluated for three items as in Example 1. The results are shown in Table 1.

(Example 3)
As Example 3, a combination of a quarter-wave plate 42 and a multilayer laminated polymer film (DBEF) 44 constituting the reflective polarizer 18 of the image display device 10b having the configuration of Embodiment 2 shown in FIG. 5 was prepared. As the quarter-wave plate 42, the same one as the quarter-wave plate 14 prepared in Example 1 was used.
As the reflective polarizer 18, a laminate of DBEF, which is a multilayer laminated polymer film 44, and a λ / 4 wavelength plate 42 was used.
Using the reflective polarizer 18 thus obtained, an image display device 10b of Example 3 shown in FIG. The configuration is shown in Table 1.
The image display device 10b of Example 3 was evaluated for the above three items in the same manner as in Example 1. The results are shown in Table 1.

Example 4
As Example 4, as a reflective polarizer 40 (18) of the image display device 10b having the configuration of Embodiment 2 shown in FIG. 5, a wire grid polarizer instead of the multilayer laminated polymer film (DBEF) 44 of Example 3 is used. Was prepared and used.
As the reflective polarizer 18, a laminate of a wire grid polarizer (trade name: wire grid polarization filter 50 × 50, manufactured by Edmund Optics) and the aforementioned λ / 4 wavelength plate 42 was used.
Using the reflective polarizer 18 in which the wire grid polarizer thus obtained and the λ / 4 wavelength plate 42 were laminated, the image display device 10b of Example 4 shown in FIG. . The configuration is shown in Table 1.
The image display device 10b of Example 4 was evaluated for the above three items in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
As Example 5, the image display device 10c having the configuration of the third embodiment shown in FIGS. 6A and 6B has a trapezoidal opening 46 that continuously changes in one direction at 14 to 16 μm. A MEMS shutter device 16 having a reflector 48 was prepared.
Using the MEMS shutter device 16 thus obtained, an image display device 10c of Example 5 shown in FIGS. 6A and 6B was produced in the same manner as Example 1. The configuration is shown in Table 1.
The image display device 10c of Example 5 was evaluated for the above three items as in Example 1. The results are shown in Table 1.

(Example 6)
As Example 6, the diffusion film 50 of the image display device 10d having the configuration of Embodiment 4 shown in FIG. 7 was prepared and used.
(Preparation of diffusion film 50)
As the scattering film 50, FUJIFILM Corporation CV-UA03 was used. When the haze of the film was measured with a haze meter NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS-K7136, it was 75%.
Using the diffusion film 50 thus obtained, an image display device 10d of Example 6 shown in FIG. The configuration is shown in Table 1.
The image display device 10d of Example 6 was evaluated for the above three items in the same manner as in Example 1. The results are shown in Table 1.

As is clear from Table 1, in Comparative Example 1, the front luminance evaluation is A, but the external light reflection evaluation is C, whereas in Examples 1-3, 5 and 6, the external light reflection is In all of the examples, the evaluation of front luminance is A, and in Example 4, the evaluation of front luminance is B, but the evaluation of external light reflection is A. In any of these examples, the visibility due to the suppression of external light reflection is It can be seen that the improvement is achieved by balancing the improvement of the brightness and the front luminance.
In Examples 5 and 6, the evaluation of rainbow unevenness is also A, indicating that the visibility is further improved.
From the above results, the effect of the present invention is clear.

  As described above, various embodiments and examples of the image display device of the present invention have been described in detail. However, the present invention is not limited to these embodiments and examples, and does not depart from the gist of the present invention. Of course, various improvements or changes may be made.

10, 10a, 10b, 10c, 10d Image display device 12 Absorption-type polarizer 14, 42 1/4 wavelength plate 16 MEMS shutter device 18 Reflection-type polarizer 20 Backlight 22 MEMS display devices 24, 24R, 24G, 24B LED
26, 46 Openings 28, 48 Reflector 30 Transparent substrate 32 Spring 34 MEMS shutter 35 Shutter 36 Open window 38 Shutter region 40 Reflective circularly polarizing plate 44 Multilayer laminated polymer film (DBEF)
50 diffusion film

Claims (10)

An image display having a backlight that emits light, and a MEMS shutter device that includes an opening that transmits light emitted from the backlight, and that controls the amount of light that opens and closes the opening and transmits the light. A device,
An absorptive polarizer and a quarter-wave plate sequentially arranged from the viewing side on the viewing side of the MEMS shutter device;
And a reflective polarizer disposed on the backlight side of the quarter-wave plate.   The image display apparatus according to claim 1, wherein the reflective polarizer is disposed between the MEMS shutter device and the backlight.   The image display apparatus according to claim 1, wherein the reflective polarizer is disposed between the MEMS shutter device and the quarter-wave plate.   The reflective polarizer is composed of a cholesteric liquid crystal layer, or is composed of a multilayer laminated polymer film sequentially arranged from the backlight side, or from a wire grid polarizer and a second quarter-wave plate. The image display device according to claim 1, wherein the image display device is configured.   The image display device according to claim 4, wherein the cholesteric liquid crystal layer is a single layer or a multilayer.   The image display apparatus according to claim 1, wherein an opening width of the opening of the MEMS shutter device changes along a longitudinal direction of the opening.   The image display device according to claim 6, wherein the opening width changes so as to continuously narrow in one direction along a longitudinal direction of the opening.   Furthermore, it has the diffusion film arrange | positioned at the said visual recognition side from the said reflection type polarizer and the said MEMS shutter device, and the said backlight side from the said quarter wave plate. The image display device described.   The said absorption type polarizer, the said 1/4 wavelength plate, the said diffuser film, the said MEMS shutter device, and the said reflection type polarizer are sequentially arrange | positioned toward the said backlight from the said visual recognition side. Image display device.   The MEMS shutter device has a first position that covers the opening and blocks light emitted from the backlight, and a second position that opens the opening and transmits light emitted from the backlight. The image display device according to claim 1, further comprising a MEMS shutter that moves between positions.