WO2023176693A1 - Display system, display method, display body, and method for manufacturing display body - Google Patents

Abstract

The present invention provides a display system that makes it possible to realize VR goggles having higher definition. A display system according to an embodiment of the present invention displays an image for a user, and comprises: a display element having a display surface for emitting, in a forward direction through a polarization member, light representing an image; a reflecting unit that is arranged in front of the display element, includes a reflective polarization member, and reflects the light emitted from the display element; a first lens unit arranged on the optical path between the display element and the reflecting unit; a half mirror that is arranged between display element and the first lens unit, transmits the light emitted from the display element, and reflects, toward the reflecting unit, the light reflected by the reflecting unit; a first λ/4 member arranged on the optical path between the display element and the half mirror; and a second λ/4 member arranged on the optical path between the half mirror and the reflecting unit. When linearly polarized light the polarization direction of which forms an angle of 45° with respect to the slow axis is incident to the first λ/4 member, the ellipticity of transmitted light having a wavelength of 380-700 nm is 0.72 or greater, and when linearly polarized light the polarization direction of which forms an angle of 45° with respect to the slow axis is incident to the second λ/4 member, the ellipticity of transmitted light having a wavelength of 380-700 nm is 0.72 or greater.

Description

Display system, display method, display body and display body manufacturing method

The present invention relates to a display system, a display method, a display body, and a method for manufacturing a display body.

Image display devices represented by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices) are rapidly becoming popular. In image display devices, optical members such as polarizing members and retardation members are generally used to realize image display and improve image display performance (see, for example, Patent Document 1).

In recent years, new uses for image display devices have been developed. For example, goggles with a display (VR goggles) for realizing Virtual Reality (VR) are beginning to be commercialized. Since VR goggles are being considered for use in a variety of situations, it is desired that they be lighter and have higher definition. Weight reduction can be achieved, for example, by making the lenses used in VR goggles thinner. On the other hand, there is also a desire for the development of optical members suitable for display systems using thin lenses.

JP2021-103286A

In view of the above, the main purpose of the present invention is to provide a display system that can reduce the weight and increase the definition of VR goggles.

[1] According to one aspect of the present invention, there is provided a display system for displaying an image to a user, comprising: a display element having a display surface that forwardly emits light representing an image via a polarizing member; a reflecting section that is disposed in front of the display element, includes a reflective polarizing member, and reflects light emitted from the display element; and a first lens that is disposed on the optical path between the display element and the reflective section. and a half mirror disposed between the display element and the first lens part, which transmits the light emitted from the display element and reflects the light reflected by the reflection part toward the reflection part. a first λ/4 member disposed on the optical path between the display element and the half mirror; and a second λ/4 member disposed on the optical path between the half mirror and the reflection section. 4 member, and the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm when linearly polarized light whose polarization direction makes an angle of 45° with respect to the slow axis is incident on the first λ/4 member. is 0.72 or more, and when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the transmitted light with a wavelength of 380 nm to 700 nm is A display system is provided having an ellipticity of 0.72 or greater.
[2] In the display system according to [1] above, when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, a wavelength of 550 nm is obtained. The ellipticity of the transmitted light may be 0.9 or more, and the wavelength when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member. The ellipticity of transmitted light at 550 nm may be 0.9 or more.
[3] In the display system according to [1] or [2] above, when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member. The ellipticity of transmitted light with a wavelength of 450 nm may be larger than that of transmitted light with a wavelength of 650 nm, and the polarization direction of the second λ/4 member makes an angle of 45° with respect to its slow axis. When linearly polarized light is incident, the ellipticity of transmitted light with a wavelength of 450 nm may be larger than the ellipticity of transmitted light with a wavelength of 650 nm.
[4] In the display system according to any one of [1] to [3] above, the first λ/4 member has a polarization direction of 45° with respect to its slow axis in the wavelength range of 380 nm to 700 nm. When linearly polarized light forming an angle of When linearly polarized light whose polarization direction makes an angle of 45° with respect to the slow axis is incident on a λ/4 member, the proportion of the wavelength range in which the ellipticity of transmitted light is 0.85 or more is 70% or more. It may be.
[5] In the display system according to any one of [1] to [4] above, linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member. The wavelength range of 380 nm to 600 nm may account for 70% or more of the wavelength range in which transmitted light exhibits an ellipticity of 0.85 or more when the polarization direction is set to the second λ/4 member. The wavelength region of 380 nm to 600 nm may account for 70% or more of the wavelength region in which transmitted light exhibits an ellipticity of 0.85 or more when linearly polarized light is incident at an angle of 45° with respect to the axis.
[6] In the display system according to any one of [1] to [5] above, the polarization direction of the light emitted through the polarizing member and the reflection axis of the reflective polarizing member are substantially orthogonal to each other. It's fine.
[7] In the display system according to any one of [1] to [5] above, the polarization direction of the light emitted through the polarizing member and the reflection axis of the reflective polarizing member are substantially parallel to each other. It's fine.
[8] According to another aspect of the present invention, a display body including the display system according to any one of [1] to [7] above is provided.
[9] According to another aspect of the present invention, there is provided a method for manufacturing a display body including the display system according to any one of [1] to [7] above.
[10] According to another aspect of the present invention, the step of passing the light representing the image emitted through the polarizing member through the first λ/4 member; and passing the light representing the image through the first λ/4 member. passing the light that has passed through the half mirror and the first lens section; passing the light that has passed through the half mirror and the first lens section through a second λ/4 member; a step of reflecting the light that has passed through the /4 member toward the half mirror by a reflecting section including a reflective polarizing member; the step of allowing the reflective portion to pass through the member; The ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more, and linearly polarized light whose polarization direction forms an angle of 45° with respect to its slow axis is incident on the second λ/4 member. A display method is provided in which the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more.

In VR goggles, the image displayed on the display is magnified by a lens and viewed by the viewer, so slight fluctuations in the characteristics of each component can greatly affect the display characteristics. On the other hand, according to the display system according to the embodiment of the present invention, high definition of VR goggles can be realized by using constituent members having predetermined optical characteristics.

1 is a schematic diagram showing a general configuration of a display system according to one embodiment of the present invention. 2 is a schematic diagram illustrating an example of the progress of light and changes in polarization state in one embodiment of the display system shown in FIG. 1. FIG. 2 is a schematic diagram illustrating an example of the progress of light and changes in polarization state in one embodiment of the display system shown in FIG. 1. FIG. FIG. 3 is a diagram for explaining a method of measuring thickness variations. It is a figure for explaining the measuring method of an ISC value. It is a figure which shows the ellipticity spectrum of the retardation film produced in the manufacturing example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In order to make the explanation more clear, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the embodiment, but this is just an example and does not limit the interpretation of the present invention. It's not a thing. Further, in the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping explanations may be omitted.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the direction perpendicular to the slow axis in the plane (i.e., fast axis direction) "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" is an in-plane retardation measured with light having a wavelength of λnm at 23°C. For example, "Re(550)" is an in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is determined by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in thickness direction (Rth)
"Rth (λ)" is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth (550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is determined by the formula: Rth(λ)=(nx−nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is determined by Nz=Rth/Re.
(5) Angle When an angle is referred to in this specification, unless otherwise specified, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°. Furthermore, in this specification, "substantially parallel" includes a range of 0°±10°, preferably within a range of 0°±5°, and more preferably within a range of 0°±3°. , more preferably within the range of 0°±1°. "Substantially orthogonal" includes a range of 90°±10°, preferably within a range of 90°±5°, more preferably within a range of 90°±3°, and even more preferably 90°±3°. It is within a range of 1°.

FIG. 1 is a schematic diagram showing the general configuration of a display system according to one embodiment of the present invention. FIG. 1 schematically shows the arrangement, shape, etc. of each component of the display system 2. As shown in FIG. The display system 2 includes a display element 12, a reflection section 14 including a reflective polarizing member, a first lens section 16, a half mirror 18, a first retardation member 20, a second retardation member 22, and a second retardation member 22. It is equipped with two lens parts 24. The reflecting section 14 is arranged at the front of the display element 12 on the display surface 12a side, and can reflect the light emitted from the display element 12. The first lens section 16 is arranged on the optical path between the display element 12 and the reflection section 14, and the half mirror 18 is arranged between the display element 12 and the first lens section 16. The first retardation member 20 is arranged on the optical path between the display element 12 and the half mirror 18, and the second retardation member 22 is arranged on the optical path between the half mirror 18 and the reflection section 14.

The display element 12 is, for example, a liquid crystal display or an organic EL display, and has a display surface 12a for displaying images. The light emitted from the display surface 12a passes through a polarizing member (typically, a polarizing film) that may be included in the display element 12, and is emitted as first linearly polarized light.

The first retardation member 20 is a λ/4 member that can convert the first linearly polarized light incident on the first retardation member 20 into first circularly polarized light (hereinafter, the first retardation member is referred to as the first (sometimes referred to as a λ/4 member). Note that the first retardation member 20 may be provided integrally with the display element 12.

The half mirror 18 transmits the light emitted from the display element 12 and reflects the light reflected by the reflection section 14 toward the reflection section 14 . The half mirror 18 is provided integrally with the first lens section 16.

The second retardation member 22 is a λ/4 member that can transmit the light reflected by the reflection part 14 and the half mirror 18 through the reflection part 14 including a reflective polarizing member (hereinafter referred to as the second retardation member). (sometimes referred to as the second λ/4 member). Note that the second retardation member 22 may be provided integrally with the first lens portion 16.

The first circularly polarized light emitted from the first λ/4 member 20 passes through the half mirror 18 and the first lens section 16, and is converted into second linearly polarized light by the second λ/4 member 22. . The second linearly polarized light emitted from the second λ/4 member 22 is reflected toward the half mirror 18 without passing through the reflective polarizing member included in the reflecting section 14 . At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member included in the reflecting section 14 is the same direction as the reflection axis of the reflective polarizing member. Therefore, the second linearly polarized light incident on the reflection section 14 is reflected by the reflective polarizing member.

The second linearly polarized light reflected by the reflection section 14 is converted into second circularly polarized light by the second λ/4 member 22, and the second circularly polarized light emitted from the second λ/4 member 22 is converted into second circularly polarized light by the second λ/4 member 22. The light passes through one lens section 16 and is reflected by a half mirror 18. The circularly polarized light reflected by the half mirror 18 passes through the first lens section 16 and is converted into third linearly polarized light by the second λ/4 member 22. The third linearly polarized light passes through the reflective polarizing member included in the reflecting section 14. At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member included in the reflecting section 14 is the same direction as the transmission axis of the reflective polarizing member. Therefore, the third linearly polarized light that has entered the reflecting section 14 is transmitted through the reflective polarizing member.

The light that has passed through the reflection section 14 passes through the second lens section 24 and enters the user's eyes 26 .

For example, the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member included in the reflecting section 14 may be arranged substantially parallel to each other, or may be arranged substantially perpendicular to each other. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first retardation member 20 is, for example, 40° to 50°, may be 42° to 48°, and is about 45°. It may be °. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the second retardation member 22 is, for example, 40° to 50°, may be 42° to 48°, and is about 45°. It may be °.

The in-plane retardation Re (550) of the first retardation member 20 is, for example, 100 nm to 190 nm, may be 110 nm to 180 nm, may be 130 nm to 160 nm, or may be 135 nm to 155 nm. .

The first retardation member 20 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases depending on the wavelength of the measurement light. Re(450)/Re(550) of the first retardation member 20 is, for example, less than 1 and may be 0.95 or less, further less than 0.90, and even 0.85 or less. good. Re(450)/Re(550) of the first retardation member 20 is, for example, 0.75 or more.

In one embodiment, the first retardation member 20 has Re(400)/Re(550)<0.85, Re(650)/Re(550)>1.03, and Re(750)/Re( 550)>1.05. The first retardation member 20 has 0.65<Re(400)/Re(550)<0.80 (preferably 0.7<Re(400)/Re(550)<0.75), 1. 0<Re(650)/Re(550)<1.25 (preferably 1.05<Re(650)/Re(550)<1.20) and 1.05<Re(750)/Re( 550)<1.40 (preferably 1.08<Re(750)/Re(550)<1.36), more preferably at least two. More preferably, all of them are satisfied.

The first retardation member 20 preferably exhibits a refractive index characteristic of nx>ny≧nz. Here, "ny=nz" includes not only the case where ny and nz are completely equal, but also the case where ny and nz are substantially equal. Therefore, there may be a case where ny<nz within a range that does not impair the effects of the present invention. The Nz coefficient of the first retardation member 20 is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, particularly preferably 0.9 to 1. It is 3.

When linearly polarized light whose polarization direction makes an angle of 45° with respect to the slow axis of the first retardation member 20 is incident on the first retardation member 20, the transmitted light is transmitted over a wavelength range of 380 nm to 700 nm, for example. It exhibits an ellipticity of 0.72 or more, preferably 0.75 or more, more preferably 0.78 or more. The upper limit of the ellipticity of the transmitted light is 1. In this specification, the ellipticity of transmitted light when linearly polarized light whose polarization direction forms an angle of 45° with respect to the slow axis of the first retardation member is incident on the first retardation member is defined as “ The ellipticity of the first retardation member may be referred to as "the ellipticity of the first retardation member". Therefore, for example, "the ellipticity of the first retardation member at the wavelength λnm" means the ellipticity of the transmitted light with the wavelength λnm, and "the first retardation member exhibits an ellipticity of X or more" means , means that the ellipticity of the transmitted light is X or more. The same applies to the second retardation member described later. By using the first retardation member having a high ellipticity of the transmitted light over a wide wavelength range of visible light, display unevenness, ghosts, etc. can be suppressed.

In the wavelength range of 380 nm to 700 nm, the proportion of the wavelength range in which the first retardation member 20 exhibits an ellipticity of 0.85 or more is, for example, 70% or more, preferably 75% or more, and more preferably 80% or more. It is. The ratio may be, for example, 100% or less. By using such a first retardation member 20, the effect of suppressing display unevenness, ghosting, etc. can be more suitably obtained.

In one embodiment, for example, 70% or more, preferably 71% to 75%, more preferably 76% to 80% of the wavelength range in which the first retardation member 20 exhibits an ellipticity of 0.85 or more is 380 nm to 600 nm. The wavelength range is occupied by Since most of the wavelength range in which the first retardation member 20 exhibits an ellipticity of 0.85 or more is in the wavelength range of 380 nm to 600 nm, the effect of suppressing display unevenness, ghosting, etc. can be more preferably obtained.

The ellipticity (ellipticity (550)) of the first retardation member 20 at a wavelength of 550 nm is, for example, 0.9 or more, preferably 0.93 or more, and more preferably 0.95 to 1. By satisfying such an ellipticity (550), a decrease in light efficiency can be suppressed.

In one embodiment, the ellipticity (ellipticity (450)) of the first retardation member 20 at a wavelength of 450 nm is larger than the ellipticity (ellipticity (650)) at a wavelength of 650 nm. Ellipticity (450)/ellipticity (650) is, for example, greater than 1, preferably 1.01 to 1.08. By using the first retardation member 20 having such an ellipticity (450) and an ellipticity (650), short wavelength light leakage (for example, blue bleeding) can be suppressed.

The ISC value of the first retardation member 20 is, for example, 50 or less, preferably 40 or less, more preferably 30 or less, and still more preferably 20 or less. When the first retardation member 20 satisfies such an ISC value, a display system with excellent visibility can be realized. For example, by satisfying such an ISC value, the uniformity of in-plane retardation can be improved, and as a result, a display system with excellent display characteristics can be obtained. The ISC value can be an indicator of smoothness or unevenness.

The variation in the thickness of the first retardation member 20 is preferably 1 μm or less, more preferably 0.8 μm or less, still more preferably 0.6 μm or less, and even more preferably 0.4 μm or less. With such thickness variations, for example, the above ISC value can be achieved satisfactorily. Here, the thickness variation is defined as the thickness of the first part located in the plane of the retardation member and the predetermined thickness in any direction from the first part (for example, upward, downward, leftward, and rightward). It can be determined by measuring the thickness at positions spaced apart (for example, 5 mm to 15 mm).

The ISC value per unit thickness of the first retardation member 20 is preferably 1 or less, more preferably 0.7 or less, and still more preferably 0.5 or less. The ISC value per unit thickness can be determined, for example, by dividing the ISC value by the thickness (unit: μm).

The first retardation member 20 is formed of any suitable material that can satisfy the above characteristics. The first retardation member 20 may be, for example, a stretched resin film or an oriented solidified layer of a liquid crystal compound. Note that the stretched film of the resin film is sometimes referred to as a retardation film.

The resins contained in the above resin film include polycarbonate resin, polyester carbonate resin, polyester resin, polyvinyl acetal resin, polyarylate resin, cyclic olefin resin, cellulose resin, polyvinyl alcohol resin, and polyamide resin. , polyimide resin, polyether resin, polystyrene resin, acrylic resin, and the like. These resins may be used alone or in combination (for example, blended or copolymerized). When the first retardation member 20 exhibits reverse dispersion wavelength characteristics, a resin film containing a polycarbonate resin or a polyester carbonate resin (hereinafter sometimes simply referred to as a polycarbonate resin) may be suitably used.

Any suitable polycarbonate resin can be used as the polycarbonate resin as long as the effects of the present invention can be obtained. For example, polycarbonate resins contain structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene-based dihydroxy compounds. a structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol or spiroglycol. Preferably, the polycarbonate resin contains a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and/or a di, tri, or polyethylene glycol. More preferably, it contains a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, and a structural unit derived from di, tri or polyethylene glycol. . The polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. Note that details of the polycarbonate-based resin that can be suitably used for the first retardation member and the method for forming the first retardation member can be found, for example, in JP-A No. 2014-10291, JP-A No. 2014-26266, and JP-A No. 2015-2015. It is described in JP-A-212816, JP-A-2015-212817, and JP-A-2015-212818, and the descriptions of these publications are incorporated herein by reference.

The liquid crystal compound alignment and solidification layer is a layer in which the liquid crystal compound is aligned in a predetermined direction within the layer, and the alignment state is fixed. In addition, the "alignment hardened layer" is a concept that includes an orientation hardened layer obtained by curing a liquid crystal monomer as described below. In the first retardation member, rod-shaped liquid crystal compounds are typically aligned in the slow axis direction of the first retardation member (homogeneous alignment). Examples of rod-shaped liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it.

The liquid crystal compound alignment and solidification layer (liquid crystal alignment solidification layer) is produced by subjecting the surface of a predetermined base material to an alignment treatment, applying a coating liquid containing the liquid crystal compound to the surface, and subjecting the liquid crystal compound to the alignment treatment. It can be formed by orienting it in a corresponding direction and fixing the orientation state. Any suitable orientation treatment may be employed as the orientation treatment. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo alignment treatment. As the treatment conditions for various orientation treatments, any appropriate conditions may be adopted depending on the purpose.

The alignment of the liquid crystal compound is carried out by treatment at a temperature that exhibits a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is oriented in accordance with the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is polymerizable or crosslinkable, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to polymerization treatment or crosslinking treatment.

Any suitable liquid crystal polymer and/or liquid crystal monomer can be used as the liquid crystal compound. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of liquid crystal compounds and methods for producing liquid crystal alignment solidified layers are described in, for example, JP 2006-163343A, JP 2006-178389A, and WO 2018/123551A. The descriptions of these publications are incorporated herein by reference.

The thickness of the first retardation member 20 is preferably 100 μm or less. Specifically, the thickness of the first retardation member 20 made of a stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and still more preferably 20 μm to 50 μm. It is. Further, the thickness of the first retardation member 20 composed of the liquid crystal alignment solidified layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and even more preferably 1 μm to 4 μm.

The in-plane retardation Re (550) of the second retardation member 22 is, for example, 100 nm to 190 nm, may be 110 nm to 180 nm, may be 130 nm to 160 nm, or may be 135 nm to 155 nm. .

The second retardation member 22 preferably exhibits inverse dispersion wavelength characteristics in which the retardation value increases depending on the wavelength of the measurement light. Re(450)/Re(550) of the second retardation member 22 is, for example, less than 1 and may be 0.95 or less, further less than 0.90, and even 0.85 or less. good. Re(450)/Re(550) of the second retardation member 22 is, for example, 0.75 or more.

In one embodiment, the second retardation member 22 has Re(400)/Re(550)<0.85, Re(650)/Re(550)>1.03, and Re(750)/Re( 550)>1.05. The second retardation member 22 has 0.65<Re(400)/Re(550)<0.80 (preferably 0.7<Re(400)/Re(550)<0.75), 1. 0<Re(650)/Re(550)<1.25 (preferably 1.05<Re(650)/Re(550)<1.20) and 1.05<Re(750)/Re( 550)<1.40 (preferably 1.08<Re(750)/Re(550)<1.36), more preferably at least two. More preferably, all of them are satisfied.

The second retardation member 22 preferably exhibits a refractive index characteristic of nx>ny≧nz. Here, "ny=nz" includes not only the case where ny and nz are completely equal, but also the case where ny and nz are substantially equal. Therefore, there may be a case where ny<nz within a range that does not impair the effects of the present invention. The Nz coefficient of the second retardation member 22 is preferably 0.9 to 3, more preferably 0.9 to 2.5, even more preferably 0.9 to 1.5, particularly preferably 0.9 to 1. It is 3.

When linearly polarized light whose polarization direction makes an angle of 45° with respect to the slow axis of the first retardation member 20 is incident on the second retardation member 22, the transmitted light is transmitted over a wavelength range of 380 nm to 700 nm, for example. It exhibits an ellipticity of 0.72 or more, preferably 0.75 or more, more preferably 0.78 or more. The upper limit of the ellipticity of the transmitted light is 1. By using the second retardation member 22 having a high ellipticity of the transmitted light over a wide wavelength range of visible light, display unevenness, ghosts, etc. can be suppressed.

In the wavelength region of 380 nm to 700 nm, the proportion of the wavelength region in which the second retardation member 22 exhibits an ellipticity of 0.85 or more is, for example, 70% or more, preferably 75% or more, more preferably 80% or more. It is. The ratio may be 100%. By using such a second retardation member 22, the effect of suppressing display unevenness, ghosting, etc. can be more suitably obtained.

In one embodiment, for example, 70% or more, preferably 71% to 75%, more preferably 76% to 80% of the wavelength range in which the second retardation member 22 exhibits an ellipticity of 0.85 or more is 380 nm to 600 nm. The wavelength range is occupied by Since most of the wavelength range in which the second retardation member 22 exhibits an ellipticity of 0.85 or more is in the wavelength range of 380 nm to 600 nm, the effect of suppressing display unevenness, ghosting, etc. can be more preferably obtained.

The ellipticity (550) of the second retardation member 22 is, for example, 0.9 or more, preferably 0.93 or more, and more preferably 0.95 to 1. By satisfying such an ellipticity (550), a decrease in light efficiency can be suppressed.

In one embodiment, the ellipticity (450) of the second retardation member 22 is larger than the ellipticity (650). Ellipticity (450)/ellipticity (650) is, for example, greater than 1, preferably 1.01 to 1.08. By using such a second retardation member 22, short wavelength light leakage (for example, blue light leakage) can be suppressed.

The ISC value of the second retardation member 22 is, for example, 50 or less, preferably 40 or less, more preferably 30 or less, and still more preferably 20 or less. When the second retardation member 22 satisfies such an ISC value, a display system with excellent visibility can be realized. For example, by satisfying such an ISC value, the uniformity of in-plane retardation can be improved, and as a result, a display system with excellent display characteristics can be obtained. The ISC value can be an indicator of smoothness or unevenness.

The variation in the thickness of the second retardation member 22 is preferably 1 μm or less, more preferably 0.8 μm or less, still more preferably 0.6 μm or less, and even more preferably 0.4 μm or less. With such thickness variations, for example, the above ISC value can be achieved satisfactorily.

The ISC value per unit thickness of the second retardation member 22 is preferably 1 or less, more preferably 0.7 or less, and even more preferably 0.5 or less.

The second retardation member 22 is formed of any suitable material that can satisfy the above characteristics. The second retardation member 22 may be, for example, a stretched resin film or an oriented solidified layer of a liquid crystal compound. The same explanation as for the first retardation member 20 can be applied to the second retardation member 22 made of a stretched resin film or an oriented solidified layer of a liquid crystal compound. The first retardation member 20 and the second retardation member 22 may have the same configuration (forming material, thickness, optical properties, etc.), or may have different configurations.

The thickness of the second retardation member 22 is preferably 100 μm or less. Specifically, the thickness of the second retardation member 22 made of a stretched resin film is, for example, 10 μm to 100 μm, preferably 10 μm to 70 μm, more preferably 10 μm to 60 μm, and still more preferably 20 μm to 50 μm. It is. Further, the thickness of the second retardation member 22 composed of the liquid crystal alignment solidified layer is, for example, 1 μm to 10 μm, preferably 1 μm to 8 μm, more preferably 1 μm to 6 μm, and still more preferably 1 μm to 4 μm.

The absolute value of the difference between the in-plane retardation (a) of the first retardation member and the in-plane retardation (b) of the second retardation member is, for example, 3.5 nm or less, preferably 3.0 nm or less. It is more preferably 2.5 nm or less, still more preferably 2.0 nm or less, particularly preferably 1.5 nm or less, and most preferably 1.0 nm or less. In one embodiment, (a) and (b) are values of Re(590). When (a) and (b) satisfy the above relationship, a display system having excellent display characteristics can be obtained.

It is preferable that the in-plane retardation (a) of the first retardation member and the in-plane retardation (b) of the second retardation member satisfy the following formula (I).
((a)-(b))/((a)+(b)/2)≦0.02...(I)
More preferably ((a)-(b))/((a)+(b)/2)≦0.015, even more preferably ((a)-(b))/((a)+( b)/2)≦0.01.

In addition to the reflective polarizing member, the reflecting section 14 may include an absorbing polarizing member. The absorptive polarizing member may be placed in front of the reflective polarizing member. The reflection axis of the reflective polarizing member and the absorption axis of the absorptive polarizing member may be arranged substantially parallel to each other, and the transmission axis of the reflective polarizing member and the transmission axis of the absorptive polarizing member may be arranged substantially parallel to each other. When the reflecting section 14 includes an absorption type polarizing member, the reflecting section 14 may include a laminate having a reflective polarizing member and an absorbing polarizing member.

The reflective polarizing member can transmit polarized light parallel to its transmission axis (typically, linearly polarized light) while maintaining its polarized state, and can reflect light in other polarized states. The cross transmittance (Tc) of the reflective polarizing member may be, for example, 0.01% to 3%. The single transmittance (Ts) of the reflective polarizing member may be, for example, 43% to 49%, preferably 45% to 47%. The degree of polarization (P) of the reflective polarizing member may be, for example, 92% to 99.99%. The reflective polarizing member is typically composed of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). Commercially available reflective polarizing films include, for example, 3M's product names "DBEF" and "APF" and Nitto Denko's product name "APCF".

The absorption type polarizing member may typically include a resin film (sometimes referred to as an absorption type polarizing film) containing a dichroic substance. The thickness of the absorption type polarizing film is, for example, 1 μm or more and 20 μm or less, may be 2 μm or more and 15 μm or less, may be 12 μm or less, may be 10 μm or less, or may be 8 μm or less, It may be 5 μm or less.

The above-mentioned absorption type polarizing film may be produced from a single layer resin film, or may be produced using a laminate of two or more layers.

When manufacturing from a single-layer resin film, for example, a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or a partially saponified ethylene/vinyl acetate copolymer film is coated with iodine or dichloromethane. An absorption type polarizing film can be obtained by performing a dyeing treatment with a dichroic substance such as a color dye, a stretching treatment, and the like. Among these, an absorption type polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred.

The above-mentioned staining with iodine is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing process or may be performed while dyeing. Alternatively, it may be dyed after being stretched. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc.

The laminate produced using the above-mentioned laminate of two or more layers is a laminate of a resin base material and a PVA resin layer (PVA resin film) laminated on the resin base material, or a laminate of a resin base material and a PVA resin layer (PVA resin film) laminated on the resin base material, or Examples include a laminate of a material and a PVA-based resin layer formed by coating on the resin base material. An absorption type polarizing film obtained by using a laminate of a resin base material and a PVA resin layer coated on the resin base material can be obtained by, for example, applying a PVA resin solution to the resin base material, drying it, and applying the resin. Forming a PVA-based resin layer on a base material to obtain a laminate of the resin base material and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer an absorption type polarizing film. can be produced by; In this embodiment, preferably, a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin is formed on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, the stretching may further include stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the boric acid aqueous solution, if necessary. In addition, in the present embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process in this order. By introducing auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it becomes possible to improve the crystallinity of PVA and achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when it is immersed in water during the subsequent dyeing and stretching processes, resulting in high optical properties. becomes possible to achieve. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance in the orientation of polyvinyl alcohol molecules and deterioration of orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. Thereby, the optical properties of an absorption polarizing film obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Furthermore, optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin base material/absorption type polarizing film laminate may be used as is (that is, the resin base material may be used as a protective layer of the absorption type polarizing film), or the resin base material/absorption type polarizing film laminate may be used as is. Any suitable protective layer depending on the purpose may be laminated on the peeled surface from which the resin base material is peeled off, or on the surface opposite to the peeled surface. Details of the manufacturing method of such an absorption type polarizing film are described in, for example, Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

The orthogonal transmittance (Tc) of the absorption type polarizing member (absorption type polarizing film) is preferably 0.5% or less, more preferably 0.1% or less, and still more preferably 0.05% or less. be. The single transmittance (Ts) of the absorption type polarizing member (absorption type polarizing film) is, for example, 41.0% to 45.0%, preferably 42.0% or more. The degree of polarization (P) of the absorption type polarizing member (absorption type polarizing film) is, for example, 99.0% to 99.997%, preferably 99.9% or more.

FIG. 2 shows an embodiment in which the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14a included in the reflecting section 14 are arranged substantially perpendicular to each other in the display system shown in FIG. FIG. 2 is a schematic diagram illustrating the progression of light and changes in polarization state in FIG. Specifically, FIG. 2(a) is a schematic diagram illustrating an example of the progression of light in this embodiment, and FIG. 2(b) is a schematic diagram illustrating how light passes through each member or is reflected by each member in this embodiment. FIG. 2 is a schematic diagram illustrating an example of a change in the polarization state of light due to the change in the polarization state of light. In FIG. 2, the solid line arrow attached to the display element 12 indicates the absorption axis direction of the polarizing member included in the display element 12. The solid arrows attached to the reflective polarizing member 14a included in the reflecting section 14 indicate the reflection axis direction, and the broken arrows indicate the transmission axis direction of each polarizing member. In this embodiment, the angle between the polarization direction of the first linearly polarized light emitted forward via the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14a is substantially parallel. The angle between the absorption axis of the polarizing member included in the display element 12 and the slow axis of the first λ/4 member 20 is, for example, 40° to 50°. The slow axis of the first λ/4 member 20 and the slow axis of the second λ/4 member 22 are arranged substantially perpendicular to each other.

The light L emitted from the display element 12 as first linearly polarized light via the polarizing member is converted into first circularly polarized light by the first λ/4 member 20. The first circularly polarized light passes through the half mirror 18 and the first lens section 16 (not shown in FIG. 2), and is passed through the second λ/4 member 22 to form the first circularly polarized light whose polarization direction is parallel to that of the first linearly polarized light. It is converted into linearly polarized light of 2. The polarization direction of the second linearly polarized light is in the same direction (substantially parallel) as the reflection axis of the reflective polarizing member 14a included in the reflection section 14. Therefore, the second linearly polarized light incident on the reflection section 14 is reflected toward the half mirror 18 by the reflective polarizing member 14a.

The second linearly polarized light reflected by the reflecting section 14 is converted into second circularly polarized light by the second λ/4 member 22. The rotation direction of the second circularly polarized light is the same as the rotation direction of the first circularly polarized light. The second circularly polarized light emitted from the second λ/4 member 22 passes through the first lens section 16 and is reflected by the half mirror 18, forming a third circle that rotates in the opposite direction to the second circularly polarized light. converted into polarized light. The third circularly polarized light reflected by the half mirror 18 passes through the first lens section 16 and is converted into third linearly polarized light by the second λ/4 member 22. The polarization direction of the third linearly polarized light is orthogonal to the polarization direction of the second linearly polarized light, and is in the same direction (substantially parallel) as the transmission axis of the reflective polarizing member 14a. Therefore, the third linearly polarized light can be transmitted through the reflective polarizing member 14a. Further, although not shown, when the reflective section includes an absorption type polarizing member, the absorption axis thereof is arranged to be approximately parallel to the reflection axis of the reflective polarizing member 14a, so that the light transmitted through the reflective polarizing member 14a is The third linearly polarized light can pass through the absorptive polarizing member as it is. The light that has passed through the reflection section 14 passes through the second lens section 24 and enters the user's eyes 26 .

In the example shown in FIG. 2, when viewed from the display element 12 side, the slow axes of the first λ/4 member and the second λ/4 member are the absorption axis of the polarizing member included in the display element 12, respectively. are arranged so as to form a predetermined angle (for example, 40° to 50°) counterclockwise and clockwise with respect to the The same explanation as above can also be applied when In an embodiment in which the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14a are arranged substantially perpendicular to each other, the first λ/4 member and the second λ/4 member The members are members whose slow axes make an angle of, for example, 83° to 97°, preferably 84° to 96°, more preferably 85° to 95°, still more preferably 86° to 94°, and even more preferably are arranged so that the angle is between 87° and 93°. When the slow axis of the first λ/4 member and the slow axis of the second λ/4 member satisfy such a relationship, a display system having excellent display characteristics can be obtained.

In the example shown in FIG. 2, the slow axis of the first λ/4 member 20 and the slow axis of the second λ/4 member 22 are arranged substantially perpendicular to each other, but as shown in FIG. They may be arranged substantially in parallel. For example, both the slow axis of the first λ/4 member 20 and the slow axis of the second λ/4 member 22 are rotated clockwise or counterclockwise with respect to the absorption axis of the polarizing member included in the display element 12. They may be arranged so as to form a predetermined angle (for example, 40° to 50°). In this case, unlike the example shown in FIG. 2, the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14a included in the reflecting section 14 may be arranged substantially parallel to each other. Therefore, the angle between the polarization direction of the first linearly polarized light emitted forward via the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 may be substantially orthogonal. In an embodiment in which the absorption axis of the polarizing member included in the display element 12 and the reflection axis of the reflective polarizing member 14 are arranged substantially parallel to each other, the first λ/4 member and the second λ/4 member is arranged so that the angle between their slow axes is, for example, 7° or less, preferably 6° or less, more preferably 5° or less, still more preferably 4° or less, and even more preferably 3° or less. be done. When the slow axis of the first λ/4 member and the slow axis of the second λ/4 member satisfy such a relationship, a display system having excellent display characteristics can be obtained.

As described above, in the display system according to the embodiment of the present invention, the first linearly polarized light emitted from the display element 12 via the polarizing member passes through the first λ/4 member 20 and then becomes the second λ/4 member. After passing through the four members 22 three times in total, the light passes through the reflective polarizing member 14a. In such a display system, by using λ/4 members each having an ellipticity of a predetermined value or more over a wide range of visible light region as the first λ/4 member 20 and the second λ/4 member 22, , hue change of transmitted light, light leakage, etc. can be suppressed. Specifically, by reducing the difference in transmittance between wavelengths of light transmitted through the reflective polarizing member 14a, hue change from the light emitted from the display element is suppressed, and as a result, display unevenness is suppressed. can be done. In addition, by suppressing the collapse of polarization over a wide range of visible light region, light leakage in the reflective polarizing member 14a is suppressed, and as a result, the light that should be reflected by the reflective polarizing member 14a becomes an afterimage (so-called ghost). It is possible to suitably prevent the user from being visually recognized as such.

Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, the test and evaluation methods in Examples and the like are as follows. In addition, when it is written as "parts", it means "parts by weight" unless there are special notes, and when it is written as "%", it means "wt%" unless there are special notes.

(1) Thickness The thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by JEOL Ltd., product name “JSM-7100F”). Thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name “KC-351C”).
(2) In-plane phase difference Re(λ)
In-plane retardation at each wavelength at 23° C. was measured using a Mueller matrix polarimeter (manufactured by Axometrics, product name “Axoscan”).
(3) Single transmittance and polarization degree of polarizing film Measure the single transmittance Ts, parallel transmittance Tp, and cross transmittance Tc of the polarizing film using a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., "LPF-200") did. These Ts, Tp, and Tc are Y values measured using a 2-degree visual field (C light source) according to JIS Z8701 and subjected to visibility correction. From the obtained Tp and Tc, the degree of polarization of the polarizing film was determined using the following formula.
Degree of polarization (%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 ×100
(4) Variation in Thickness The retardation film was cut into a size of 100 mm x 100 mm and used as a measurement sample. As shown in FIG. 4, the thickness was measured at a total of 5 points, including the center of the measurement sample and 4 points 10 mm away from the center in the upper, lower, left, and right directions, and the difference between the maximum value and the minimum value was defined as the thickness variation.
(5) ISC value The ISC value of the retardation film was measured using EyeScale-4W manufactured by Eye System Co., Ltd. Specifically, based on the specifications of the measuring device, the in-plane unevenness was calculated as an ISC value in the ISC measurement mode of the 3CCD image sensor.
FIG. 5 is a diagram for explaining a method for measuring an ISC value, and is a schematic diagram of the arrangement of a light source, a retardation film, a screen, and a CCD camera viewed from above. As shown in FIG. 5, a light source L, a retardation film M, and a screen S were arranged in this order, and a transmitted image projected onto the screen S was measured by a CCD camera C. Note that the retardation film M was attached to a non-alkali glass plate (manufactured by Corning, Inc., 1737), and the measurement was conducted with the glass plate placed on the light source L side.
The arrangement was such that the distance from the light source L to the retardation film M in the X-axis direction was 10 to 60 cm. The arrangement was such that the distance from the light source L to the screen S in the X-axis direction was 70 to 130 cm. The arrangement was such that the distance from the CCD camera C to the retardation film M in the Y-axis direction was 3 to 30 cm. The arrangement was such that the distance from the CCD camera C to the screen S in the X-axis direction was 70 to 130 cm.

[Production Example 1-1: Production of retardation film 1]
29.60 weight of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane was added to a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100°C. part (0.046 mol), isosorbide (ISB) 29.21 parts by weight (0.200 mol), spiroglycol (SPG) 42.28 parts by weight (0.139 mol), diphenyl carbonate (DPC) 63.77 parts by weight (0 .298 mol) and 1.19×10 ⁻² parts by weight (6.78×10 ⁻⁵ mol) of calcium acetate monohydrate as a catalyst were charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, it was heated with a heating medium, and when the internal temperature reached 100°C, stirring was started. 40 minutes after the start of temperature rise, the internal temperature was controlled to reach 220°C, and at the same time, pressure reduction was started to maintain this temperature, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 220°C. Phenol vapor produced as a by-product during the polymerization reaction was led to a reflux condenser at 100°C, a small amount of monomer component contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was led to a condenser at 45°C for recovery. After nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240° C. and the pressure was 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.
After vacuum drying the obtained polyester carbonate resin (pellets) at 80°C for 5 hours, a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder temperature setting: 250°C) and a T-die (width 200mm, setting temperature: 250°C) were used. A long resin film with a thickness of 130 μm was produced using a film forming apparatus equipped with a chill roll (temperature setting: 120 to 130° C.), a winder and a winder. The obtained long resin film was stretched in the width direction at a stretching temperature of 140° C. and a stretching ratio of 2.7 times.
In this way, a retardation film 1 having a thickness of 47 μm, a Re (590) of 143 nm, and an Nz coefficient of 1.2 was obtained. Re(450)/Re(550) of the obtained retardation film 1 was 0.856. Table 1 shows the ISC value and thickness variation of the retardation film 1.

[Production Example 1-2: Production of retardation film 2]
A commercially available retardation film (manufactured by Kaneka Corporation, product name: "Zeonor #140COP QWP") composed of a cycloolefin resin film was used as the retardation film 2. The thickness of the retardation film 2 was 33 μm, the Re(590) was 140 nm, and the Nz coefficient was 1.0. Moreover, Re(450)/Re(550) of the retardation film 2 was 1.01.

[Production Example 2: Production of polarizing film 1]
As the thermoplastic resin base material, a long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of approximately 75° C. was used, and one side of the resin base material was subjected to corona treatment.
Iodine was added to 100 parts by weight of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Mitsubishi Chemical Corporation, product name "Gosenex Z410") in a ratio of 9:1. A PVA aqueous solution (coating liquid) was prepared by dissolving 13 parts by weight of potassium chloride in water.
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.
The obtained laminate was uniaxially stretched 2.4 times in the vertical direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed for 30 seconds in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. (insolubilization treatment).
Next, the finally obtained absorption type polarized light was added to a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C. The membrane was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the membrane became a desired value (staining treatment).
Next, it was immersed for 30 seconds in a crosslinking bath (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C. (Crosslinking treatment).
Thereafter, while immersing the laminate in a boric acid aqueous solution (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, the laminate was completely rolled in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven kept at about 90°C, it was brought into contact with a SUS heating roll whose surface temperature was kept at about 75°C (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment was 5.2%.
In this way, an absorption type polarizing film with a thickness of about 5 μm was formed on the resin base material.
An acrylic resin film ("RV-20", thickness 20 μm) as a protective layer was applied to the surface of the obtained absorption type polarizing film (the surface opposite to the resin base material), and a water-based adhesive (thickness after curing) was applied as a protective layer. 0.1 μm). Then, the resin base material was peeled off.
As a result, a polarizing film 1 having a structure of [acrylic resin film/absorption type polarizing film] was obtained. As the water-based adhesive, a water-based adhesive containing a PVA-based resin having an acetoacetyl group, methylolmelamine, and a positively charged alumina colloid (average particle size: 15 nm) was used.
The single transmittance (Ts) of the polarizing film 1 was 43.0%, and the degree of polarization was 99.989%.

The ellipticity of the above-mentioned retardation film 1 and retardation film 2 was measured as follows. The results are shown in Table 2 and FIG. 6.
<How to measure ellipticity>
Measurement with a configuration of [retardation film/polarizing film 1] by laminating a retardation film on the absorbing polarizing film side surface of the polarizing film 1 via an acrylic adhesive layer (manufactured by Nitto Denko Corporation, thickness 5 μm) A sample was obtained. In the measurement sample, the angle between the slow axis of the retardation film and the absorption axis of the polarizing film 1 was 45°.
Using a Mueller matrix polarimeter (manufactured by Axometrics, product name "Axoscan"), light was irradiated from the normal direction to the polarizing film 1 side surface of the measurement sample at 23 ° C., and in the wavelength range of 400 nm to 700 nm. The ellipticity of transmitted light was measured every 10 nm.

[Example 1]
Four retardation films 1 obtained in Production Example 1-1 were stacked, and then the polarizing film 1 obtained in Production Example 2 was stacked to obtain a laminate. Adjacent films were bonded together via an acrylic adhesive layer (manufactured by Nitto Denko Corporation, thickness 5 μm). The four retardation films 1 were stacked in order from one side as λ/4 member 1, λ/4 member 2, λ/4 member 3, and λ/4 member 4 in the axial relationship shown in Table 3. Then, the polarizing film 1 was placed on the λ/4 member 4. The angles shown in Table 3 are the axis angles of each member based on the absorption axis direction of the absorption type polarizing film of the polarizing film when the laminate is viewed from the λ/4 member 1 side, and "+" indicates Clockwise, "-" means counterclockwise.

[Comparative example 1]
A laminate was obtained in the same manner as in Example 1 except that retardation film 2 was used as λ/4 members 1 to 4.

<Evaluation>
Using a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., "LPF-200"), the parallel transmittance and initial hue (a ^* value, b ^* value) of polarizing film 1 and the laminates of Example 1 and Comparative Example 1 were measured. Parallel transmittance and parallel hue (a ^* value, b ^* value) were measured. The parallel transmittance is a Y value measured using a 2-degree field of view (C light source) according to JIS Z8701 and subjected to visibility correction. The initial hue of the polarizing film is the hue of light that is emitted from the other side when light is incident on one side of the polarizing film 1. The parallel hue of the laminate is the hue of light that is emitted from the polarizing film 1 side when linearly polarized light whose polarization direction is perpendicular to the absorption axis of the polarizing film 1 is incident from the λ/4 member 1 side of the laminate. .

Table 4 shows the parallel transmittance and initial hue of the polarizing film 1, and the difference between these and the parallel transmittance and parallel hue of the laminate. Note that the laminates produced in Examples and Comparative Examples are simple evaluation models of display systems according to embodiments of the present invention. Specifically, in the display system according to the embodiment of the present invention, light that enters the laminate from the λ/4 member 1 side and exits from the polarizing film 1 side is emitted forward from the display element via the polarizing member. After the first linearly polarized light passes through the first λ/4 member and the second λ/4 member in this order, it is reflected by the reflective polarizing member and the half mirror to further pass through the second λ/4 member. It can be evaluated as light that is transmitted twice, then transmitted through a reflective polarizing member, and emitted forward. Therefore, the difference between the parallel transmittance of the polarizing film 1 and the parallel transmittance of the laminate (ΔTp=Tp of the laminate−Tp of the polarizing film 1) can reflect the degree of reduction in light efficiency in the display system. Further, the difference (Δa ^* b ^* ) between the initial hue of the polarizing film 1 and the parallel hue of the laminate can reflect the degree of change in hue between the emitted light and the transmitted light in the display system.

The change in hue of the light transmitted through the laminate of Example 1 was suppressed compared to the light transmitted through the laminate of Comparative Example 1. Also, the decrease in light efficiency is suppressed.

The present invention is not limited to the above embodiments, and various modifications are possible. For example, it can be replaced with a configuration that is substantially the same as the configuration shown in the above embodiment, a configuration that has the same effect, or a configuration that can achieve the same purpose.

The display system according to the embodiment of the present invention can be used for a display body such as VR goggles, for example.

2 Display system 12 Display element 14 Reflection section 14a Reflective polarizing member 16 First lens section 18 Half mirror 20 First retardation member 22 Second retardation member 24 Second lens section

Claims (10)

1. A display system for displaying images to a user, the display system comprising:
   a display element having a display surface that emits light representing an image forward through a polarizing member;
   a reflecting section disposed in front of the display element, including a reflective polarizing member, and reflecting light emitted from the display element;
   a first lens section disposed on an optical path between the display element and the reflection section;
   a half mirror disposed between the display element and the first lens part, which transmits the light emitted from the display element and reflects the light reflected by the reflection part toward the reflection part;
   a first λ/4 member disposed on an optical path between the display element and the half mirror;
   a second λ/4 member disposed on the optical path between the half mirror and the reflection section,
   When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more. can be,
   When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more. be,
   display system.
2. When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, the ellipticity of transmitted light with a wavelength of 550 nm is 0.9 or more,
   When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the ellipticity of transmitted light with a wavelength of 550 nm is 0.9 or more. The display system according to claim 1.
3. When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, the ellipticity of transmitted light with a wavelength of 450 nm is the ellipticity of transmitted light with a wavelength of 650 nm. greater than the rate;
   When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the ellipticity of transmitted light with a wavelength of 450 nm is the ellipticity of transmitted light with a wavelength of 650 nm. 2. The display system of claim 1, wherein the display system is greater than the percentage.
4. In the wavelength range of 380 nm to 700 nm, when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, the ellipticity of transmitted light is 0.85. The ratio of the wavelength range that is above is 70% or more,
   In the wavelength range of 380 nm to 700 nm, when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the ellipticity of transmitted light is 0.85. 2. The display system according to claim 1, wherein the proportion of the above wavelength range is 70% or more.
5. 70% of the wavelength range in which transmitted light exhibits an ellipticity of 0.85 or more when linearly polarized light whose polarization direction makes an angle of 45° with respect to the slow axis is incident on the first λ/4 member. The above is occupied by the wavelength region of 380 nm to 600 nm,
   70% of the wavelength range in which transmitted light exhibits an ellipticity of 0.85 or more when linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member. The display system according to claim 1, wherein the wavelength range from 380 nm to 600 nm occupies the above range.
6. The display system according to claim 1, wherein the polarization direction of the light emitted through the polarizing member and the reflection axis of the reflective polarizing member are substantially orthogonal to each other.
7. The display system according to claim 1, wherein the polarization direction of the light emitted through the polarizing member and the reflection axis of the reflective polarizing member are substantially parallel to each other.
8. A display body comprising the display system according to any one of claims 1 to 7.
9. A method for manufacturing a display body comprising the display system according to any one of claims 1 to 7.
10. passing the light representing the image emitted through the polarizing member through the first λ/4 member;
    a step of causing the light that has passed through the first λ/4 member to pass through a half mirror and a first lens portion;
    passing the light that has passed through the half mirror and the first lens section through a second λ/4 member;
    reflecting the light that has passed through the second λ/4 member toward the half mirror by a reflecting section including a reflective polarizing member;
    a step of allowing the light reflected by the reflection part and the half mirror to pass through the reflection part by the second λ/4 member;
    When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the first λ/4 member, the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more. can be,
    When linearly polarized light whose polarization direction makes an angle of 45° with respect to its slow axis is incident on the second λ/4 member, the ellipticity of transmitted light with a wavelength of 380 nm to 700 nm is 0.72 or more. be,
    Display method.
    
    

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