KR20240161120A - Lens and laminated film - Google Patents

Abstract

The present invention provides a lens unit capable of realizing weight reduction and improving visibility of VR goggles. A lens unit according to an embodiment of the present invention is a lens unit used in a display system that displays an image to a user, comprising: a reflective polarizing member that reflects light emitted forward from a display surface of a display element that displays an image and that has passed through a polarizing member and a first λ/4 member; a first lens unit that is arranged on an optical path between the display element and the reflective polarizing member; a half mirror that is arranged between the display element and the first lens unit and transmits light emitted from the display element and reflects light reflected by the reflective polarizing member toward the reflective polarizing member; a second lens unit that is arranged in front of the reflective polarizing member; a second λ/4 member that is arranged on an optical path between the half mirror and the reflective polarizing member; and a first protective member and a second protective member that are arranged on an optical path between the half mirror and the reflective polarizing member, wherein the first protective member and the second protective member are arranged to face each other with a space therebetween, and the first protective member and the second protective member are arranged to face each other with a space therebetween. The absence is, respectively, a maximum value of the 30° specular reflectance spectrum in the range of wavelengths 420 nm to 680 nm of 1.4% or less.

Description

Lens and laminated film

The present invention relates to a lens unit and a laminated film.

Image display devices, such as liquid crystal display devices and electroluminescent (EL) display devices (e.g., organic EL display devices), are rapidly becoming widespread. In image display devices, optical members such as polarizing members and phase difference members are generally used to realize image display and improve image display performance (e.g., see Patent Document 1).

Recently, new uses for image display devices are being developed. For example, display-attached goggles (VR goggles) for realizing Virtual Reality (VR) are beginning to be commercialized. Since the use of VR goggles in various scenes is being considered, their weight reduction and improved visibility are being demanded. Weight reduction can be achieved, for example, by making the lenses used in VR goggles thinner. Meanwhile, the development of optical members suitable for display systems using thin lenses is also being demanded. For example, in order to improve visibility, an optical member that can solve the reflection problem that may occur inside VR goggles is being demanded.

Japanese Patent Publication No. 2021-103286

In consideration of the above, the main purpose of the present invention is to provide a lens unit that can realize weight reduction and improved visibility of VR goggles.

1. A lens unit according to an embodiment of the present invention is a lens unit used in a display system that displays an image to a user, comprising: a reflective polarizing member that reflects light that is emitted forward from a display surface of a display element that displays an image and has passed through a polarizing member and a first λ/4 member; a first lens unit that is arranged on an optical path between the display element and the reflective polarizing member; a half mirror that is arranged between the display element and the first lens unit and transmits light emitted from the display element and reflects light reflected by the reflective polarizing member toward the reflective polarizing member; a second lens unit that is arranged in front of the reflective polarizing member; a second λ/4 member that is arranged on an optical path between the half mirror and the reflective polarizing member; and a first protective member and a second protective member that are arranged on an optical path between the half mirror and the reflective polarizing member, wherein the first protective member and the second protective member are arranged to face each other with a space therebetween, and the first protective member and the second protective member are arranged to face each other with a space therebetween. The absence is, respectively, a maximum value of the 30° specular reflectance spectrum in the range of wavelengths 420 nm to 680 nm of 1.4% or less.

2. In the lens portion described in 1 above, the first protective member and the second protective member may each have a 30° regular reflectivity of 0.5% or less at a wavelength of 450 nm.

3. In the lens portion described in 1 or 2 above, the first protective member and the second protective member may each have a 30° regular reflectivity of 0.5% or less at a wavelength of 600 nm.

4. In any of the lens portions described in 1 to 3 above, the first protective member and the second protective member may each have a surface smoothness of 0.5 arcmin or less.

5. In any of the lens sections described in 1 to 4 above, the second λ/4 member may satisfy Re(450)<Re(550).

6. The lens portion described in any one of 1 to 5 above may have a first laminated portion including the second λ/4 member and the first protective member, and a second laminated portion including the reflective polarizing member and the second protective member.

7. In the lens portion described in 6 above, the second laminated portion may include an absorptive polarizing member arranged between the reflective polarizing member and the second lens portion.

8. In the lens unit described in 6 or 7 above, the second laminated unit may include a third λ/4 member arranged between the reflective polarizing member and the second lens unit.

9. In the lens section described in 8 above, the third λ/4 member may satisfy Re(450)<Re(550).

10. A laminated film according to an embodiment of the present invention is used in a display method, including a step of allowing light representing an image emitted through a polarizing member and a first λ/4 member to pass through a half mirror and a first lens unit, a step of allowing the light passing through the half mirror and the first lens unit to pass through a second λ/4 member, a step of reflecting the light passing through the second λ/4 member toward the half mirror from a reflective polarizing member, a step of allowing the light reflected by the reflective polarizing member and the half mirror to pass through the reflective polarizing member by the second λ/4 member, and a step of allowing the light passing through the reflective polarizing member to pass through the second lens unit, the laminated film being arranged on an optical path between the half mirror and the reflective polarizing member and in contact with a space formed between the first lens unit and the second lens unit, the maximum value of a 30° regular reflectance spectrum in a range of wavelengths from 420 nm to 680 nm being 1.4%. Below is the information.

According to the lens unit according to the embodiment of the present invention, it is possible to realize weight reduction and improved visibility of VR goggles.

FIG. 1 is a schematic diagram showing the schematic configuration of a display system according to one embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing an example of details of a lens portion of the display system shown in Fig. 1.
FIG. 3 is a schematic cross-sectional view showing the outline configuration of a laminated film according to one embodiment of the present invention.
Figure 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film.
FIG. 5 is a graph showing the 30° reflectance spectra of the laminated films of Example 1, Comparative Example 1, and Comparative Example 2.
Figures 6 (a), (b), and (c) are photographs showing the results of the appearance evaluation.
Figures 7 (a), (b), (c), and (d) are photographs showing the results of the appearance evaluation.

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 clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the embodiments, but they are only examples and do not limit the interpretation of the present invention. In addition, in the drawings, the same or equivalent elements are given the same reference numerals, and redundant descriptions are sometimes omitted.

(Definition of terms and symbols)

The definitions of terms and symbols in this specification are as follows.

(1) Refractive index (nx, ny, nz)

'nx' is the refractive index in the direction in which the refractive index within the plane is maximum (i.e., along the ground axis), 'ny' is the refractive index in the direction perpendicular to the ground axis within the plane (i.e., along the true axis), and 'nz' is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light of wavelength λ㎚ at 23℃. For example, 'Re(550)' is the in-plane phase difference measured with light of wavelength 550㎚ at 23℃. Re(λ) can be obtained by the formula: Re(λ) = (nx-ny)×d, where d(㎚) is the thickness of the layer (film).

(3) Phase difference in thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction measured with light of wavelength λ㎚ at 23℃. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light of wavelength 550㎚ at 23℃. Rth(λ) can be obtained by the formula: Rth(λ) = (nx-nz) × d, when the thickness of the layer (film) is d(㎚).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) Angle

When referring to an angle in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, '45°' means ±45°.

FIG. 1 is a schematic diagram showing a general configuration of a display system according to one embodiment of the present invention. FIG. 1 schematically illustrates the arrangement and shape of each component of the display system (2). The display system (2) includes a display element (12), a reflective polarizing member (14), a first lens unit (16), a half mirror (18), a first phase difference member (20), a second phase difference member (22), and a second lens unit (24). The reflective polarizing member (14) is arranged in front of the display surface (12a) of the display element (12) and can reflect light emitted from the display element (12). The first lens unit (16) is arranged on an optical path between the display element (12) and the reflective polarizing member (14), and the half mirror (18) is arranged between the display element (12) and the first lens unit (16). The first phase difference member (20) is arranged on the optical path between the display element (12) and the half mirror (18), and the second phase difference member (22) is arranged on the optical path between the half mirror (18) and the reflective polarizing member (14).

The components arranged in front of the half mirror (in the illustrated example, the half mirror (18), the first lens unit (16), the second phase difference member (22), the reflective polarizing member (14), and the second lens unit (24)) are sometimes collectively referred to as a lens unit (lens unit (4)).

The display element (12) is, for example, a liquid crystal display or an organic EL display, and includes a display surface (12a) for displaying an image. Light emitted from the display surface (12a) passes through, for example, 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 phase difference member (20) includes a first λ/4 member capable of converting the first linearly polarized light incident on the first phase difference member (20) into the first circularly polarized light. When the first phase difference member does not include any member other than the first λ/4 member, the first phase difference member may correspond to the first λ/4 member. The first phase difference member (20) may be provided integrally with the display element (12).

The half mirror (18) transmits light emitted from the display element (12) and reflects light reflected from the reflective polarizing member (14) toward the reflective polarizing member (14). The half mirror (18) is provided integrally with the first lens unit (16).

The second phase difference member (22) includes a second λ/4 member that can transmit light reflected by the reflective polarizing member (14) and the half mirror (18) through the reflective polarizing member (14). When the second phase difference member does not include members other than the second λ/4 member, the second phase difference member may correspond to the second λ/4 member. The second phase difference member (22) may be provided integrally with the first lens unit (16).

The first circularly polarized light emitted from the first λ/4 member included in the first phase difference 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 included in the second phase difference member (22). The second linearly polarized light emitted from the second λ/4 member is reflected toward the half mirror (18) without passing through the reflective polarizing member (14). At this time, the polarization direction of the second linearly polarized light incident on the reflective polarizing member (14) is the same direction as the reflection axis of the reflective polarizing member (14). Therefore, the second linearly polarized light incident on the reflective polarizing member (14) is reflected by the reflective polarizing member (14).

The second linearly polarized light reflected from the reflective polarizing member (14) is converted into the second circularly polarized light by the second λ/4 member included in the second phase difference member (22), and the second circularly polarized light emitted from the second λ/4 member passes through the first lens unit (16) and is reflected by the half mirror (18). The second circularly polarized light reflected from the half mirror (18) passes through the first lens unit (16) and is converted into the third linearly polarized light by the second λ/4 member included in the second phase difference member (22). The third linearly polarized light transmits through the reflective polarizing member (14). At this time, the polarization direction of the third linearly polarized light incident on the reflective polarizing member (14) is the same direction as the transmission axis of the reflective polarizing member (14). Therefore, the third linearly polarized light incident on the reflective polarizing member (14) transmits through the reflective polarizing member (14).

Light transmitted through the reflective polarizing element (14) passes through the second lens unit (24) and enters the user's eye (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 (14) may be arranged approximately parallel to each other, or may be arranged approximately orthogonally. The angle formed by the absorption axis of the polarizing member included in the display element (12) and the ground axis of the first λ/4 member included in the first phase difference member (20) is, for example, 40° to 50°, may be 42° to 48°, or may be approximately 45°. The angle formed by the absorption axis of the polarizing member included in the display element (12) and the ground axis of the second λ/4 member included in the second phase difference member (22) is, for example, 40° to 50°, may be 42° to 48°, or may be approximately 45°.

The in-plane phase difference Re(550) of the first λ/4 member 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 λ/4 member preferably exhibits reverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light. Re(450)/Re(550) of the first λ/4 member is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

The in-plane phase difference Re(550) of the second λ/4 member 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 λ/4 member preferably exhibits reverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light. Re(450)/Re(550) of the second λ/4 member is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less.

In the lens portion (4), a space may be formed between the first lens portion (16) and the second lens portion (24). In this case, it is preferable that the member arranged between the first lens portion (16) and the second lens portion (24) be integrally provided with either the first lens portion (16) or the second lens portion (24). For example, it is preferable that the member arranged between the first lens portion (16) and the second lens portion (24) be integrally formed with either the first lens portion (16) or the second lens portion (24) via an adhesive layer. According to this form, for example, the handleability of each member can be excellent. The adhesive layer may be formed with an adhesive or an adhesive agent. Specifically, the adhesive layer may be an adhesive layer or an adhesive layer. The thickness of the adhesive layer is, for example, 0.05 µm to 30 µm.

Fig. 2 is a schematic cross-sectional view showing an example of details of a lens portion of the display system shown in Fig. 1. Specifically, Fig. 2 shows a first lens portion, a second lens portion, and a member arranged therebetween. The lens portion (4) includes a first lens portion (16), a first laminated portion (100) provided adjacent to the first lens portion (16), a second lens portion (24), and a second laminated portion (200) provided adjacent to the second lens portion (24). In the example shown in Fig. 2, the first laminated portion (100) and the second laminated portion (200) are arranged spaced apart from each other. Although not shown, the half mirror may be provided integrally with the first lens portion (16).

The first laminated portion (100) includes a second phase difference member (22) and an adhesive layer (e.g., an adhesive layer) (41) arranged between the first lens portion (16) and the second phase difference member (22), and is integrally provided with the first lens portion (16) by the adhesive layer (41). The first laminated portion (100) further includes a first protective member (31) arranged in front of the second phase difference member (22). The first protective member (31) is laminated to the second phase difference member (22) with the adhesive layer (e.g., an adhesive layer) (42) interposed therebetween. The first protective member (31) may be positioned on the outermost surface of the first laminated portion (100).

In the example shown in Fig. 2, the second phase difference member (22) includes, in addition to the second λ/4 member (22a), a member (so-called positive C plate) (22b) whose refractive index characteristics can exhibit the relationship nz>nx=ny. The second phase difference member (22) has a laminated structure of the second λ/4 member (22a) and the positive C plate (22b). By using the positive C plate, light leakage (e.g., light leakage in an oblique direction) can be prevented. As shown in Fig. 2, in the second phase difference member (22), the second λ/4 member (22a) is preferably positioned in front of the positive C plate (22b). The second λ/4 member (22a) and the positive C plate (22b) are laminated, for example, via an adhesive layer (not shown).

The second λ/4 member preferably exhibits a refractive index characteristic of nx>ny≥nz. Here, 'ny=nz' includes not only the case where ny and nz are completely the same but also the case where they are substantially the same. 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 λ/4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

The second λ/4 member is formed of any suitable material capable of satisfying the above characteristics. The second λ/4 member may be, for example, a stretched film of a resin film or an alignment solidification layer of a liquid crystal compound.

Examples of the resin included in the above resin film include polycarbonate-based resins, polyester carbonate-based resins, polyester-based resins, polyvinyl acetal-based resins, polyarylate-based resins, cyclic olefin-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic resins. These resins may be used alone or in combination. Examples of methods for combining include blending and copolymerization. When the second λ/4 member exhibits reverse dispersion wavelength characteristics, a resin film including a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, sometimes simply referred to as a polycarbonate-based resin) can be suitably used.

As the polycarbonate-based resin, any suitable polycarbonate-based resin can be used. For example, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, a structural unit derived from an alicyclic dimethanol, and/or a structural unit derived from di, tri or polyethylene glycol; More preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri or polyethylene glycol. The polycarbonate-based resin may include a structural unit derived from other dihydroxy compounds as necessary. In addition, details of a polycarbonate-based resin suitably usable for the second λ/4 member and a method for forming the second λ/4 member are described in, for example, Japanese Patent Application Laid-Open No. 2014-10291, Japanese Patent Application Laid-Open No. 2014-26266, Japanese Patent Application Laid-Open No. 2015-212816, Japanese Patent Application Laid-Open No. 2015-212817, and Japanese Patent Application Laid-Open No. 2015-212818, and the descriptions of these publications are incorporated herein by reference.

The thickness of the second λ/4 member composed of a stretched film of a resin film is, for example, 10 µm to 100 µm, preferably 10 µm to 70 µm, and more preferably 20 µm to 60 µm.

The alignment solidification layer of the above liquid crystal compound 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 solidification layer' is a concept including an alignment hardening layer obtained by curing a liquid crystal monomer as described below. In the second λ/4 member, a rod-shaped liquid crystal compound is typically aligned in a state of being aligned in the ground axis direction of the second λ/4 member (homogeneous alignment). As the rod-shaped liquid crystal compound, for example, a liquid crystal polymer and a liquid crystal monomer can be mentioned. 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 polymerizing the liquid crystal compound after orienting it.

The alignment solidification layer (liquid crystal alignment solidification layer) of the above liquid crystal compound can be formed by performing an alignment treatment on the surface of a predetermined substrate, coating the surface with a coating solution containing a liquid crystal compound to align the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. Any appropriate alignment treatment can be adopted as the alignment treatment. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be given. Specific examples of the mechanical alignment treatment include a rubbing treatment and a stretching treatment. Specific examples of the physical alignment treatment include a magnetic field alignment treatment and an electric field alignment treatment. Specific examples of the chemical alignment treatment include a diagonal deposition method and an optical alignment treatment. Any appropriate conditions can be adopted as the processing conditions for the various alignment treatments depending on the purpose.

The alignment of the liquid crystal compound is carried out by treating it at a temperature at which it exhibits a liquid crystal phase, depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound aligns along the alignment treatment direction of the substrate surface.

Fixation of the orientation state is, in one embodiment, carried out by cooling the liquid crystal compound oriented as described above. When the liquid crystal compound is polymerizable or crosslinkable, fixation of the orientation state is carried out by polymerizing or crosslinking the liquid crystal compound oriented as described above.

As the liquid crystal compound, any suitable liquid crystal polymer and/or liquid crystal monomer is used. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of the liquid crystal compound and the method for producing the liquid crystal alignment layer are described in, for example, Japanese Patent Application Laid-Open No. 2006-163343, Japanese Patent Application Laid-Open No. 2006-178389, and International Publication No. 2018/123551. The descriptions of these publications are incorporated herein by reference.

The thickness of the second λ/4 member composed of the liquid crystal alignment solidification 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 thickness direction phase difference Rth(550) of the above positive C plate is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly equal to each other but also the case where nx and ny are substantially equal to each other. The in-plane phase difference Re(550) of the positive C plate is, for example, less than 10 nm.

The positive C plate can be formed of any suitable material, but the positive C plate is preferably composed of a film including a liquid crystal material fixed in a homeotropic alignment. The liquid crystal material (liquid crystal compound) capable of being homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of such a liquid crystal compound and a method for forming the positive C plate include the liquid crystal compounds and the method for forming the phase difference layer described in [0020] to [0028] of Japanese Patent Laid-Open No. 2002-333642. In this case, the thickness of the positive C plate is preferably 0.5 µm to 5 µm.

The first protective member may be, for example, a laminated film including a substrate and a surface treatment layer. The first protective member including the surface treatment layer may be arranged such that the surface treatment layer is positioned on the front side. Specifically, the surface treatment layer may be positioned on the outermost surface of the first laminated portion.

The first protective member has a maximum value of a 30° regular reflectance spectrum in a wavelength range of 420 nm to 680 nm of 0% or more and 1.4% or less, preferably 1.2% or less, and more preferably 1.0% or less. By positioning a protective member having such reflection characteristics on the outermost surface of the laminated portion, visibility can be significantly improved. Specifically, since the protective member in contact with the space formed between the first lens portion (16) and the second lens portion (24) satisfies the above reflection characteristics, light loss due to reflection at the interface between the air and the protective member can be suppressed extremely well. Specifically, in the display system (2), light may be diffused, and the diffused light may be incident from an oblique direction with respect to the protective member. Such light loss can be suppressed extremely well. In a display system (2) that utilizes a large number of members, the required amount of light is large, and the effect of suppressing light loss can be significantly obtained. As described above, in the display system (2) shown in Fig. 1, since light can pass through the member arranged between the half mirror (18) and the reflective polarizing member (14) three times, the effect of suppressing light loss can be significantly obtained. In addition, since the protective member satisfies the above reflection characteristics, it is possible to suppress the visibility of afterimages (ghosts) caused by reflection.

As described above, when the amount of light used is large, color management may become important. For example, the balance of reflectivity in the visible light region may become important. The 30° regular reflectance at a wavelength of 450 nm of the first protective member is, for example, 0.01% or more and 0.6% or less, preferably 0.5% or less, more preferably 0.4% or less, and even more preferably 0.3% or less. The 30° regular reflectance at a wavelength of 600 nm of the first protective member is, for example, 0.01% or more and 0.6% or less, preferably 0.5% or less, more preferably 0.4% or less, and even more preferably 0.3% or less.

The 30° regular reflectance spectrum in the wavelength range of 420 nm to 680 nm of the first protective member may have local minima in the wavelength range of 430 nm to 470 nm and in the wavelength range of 550 nm to 590 nm. For example, a ratio of the average value Ave(430-470 nm) of the 30° regular reflectance in the wavelength range of 430 nm to 470 nm to the average value Ave(480-510 nm) of the 30° regular reflectance in the wavelength range of 480 nm to 510 nm is preferably 0.10 or more and less than 1.0, and may be 0.80 or less. And, the ratio of the average value Ave(580-620nm) of the 30° specular reflectance in the range of wavelengths 580 nm to 620 nm to the average value Ave(480-510nm) of the 30° specular reflectance in the range of wavelengths 480 nm to 510 nm is preferably 0.10 or more and less than 1.0, and may be 0.80 or less. In addition, the average value of the 30° specular reflectance can be obtained, for example, by extracting measurement values every 5 nm in each wavelength range and dividing the sum of these by the number of extracted wavelengths.

The surface smoothness of the first protective member is preferably 0.5 arcmin or less, more preferably 0.4 arcmin or less. By using a protective member satisfying such smoothness, the occurrence of diffused light can be suppressed, and the image can be suppressed from becoming unclear. In practice, the surface smoothness of the first protective member is, for example, 0.1 arcmin or more. The thickness of the first protective member is preferably 10 µm to 80 µm, more preferably 15 µm to 60 µm, and even more preferably 20 µm to 45 µm.

FIG. 3 is a schematic cross-sectional view showing the schematic configuration of a laminated film according to one embodiment of the present invention. The laminated film (34) includes a substrate (36) and a surface treatment layer (38) arranged above the substrate (36). The thickness of the substrate (36) is preferably 5 µm to 80 µm, more preferably 10 µm to 50 µm, and even more preferably 15 µm to 40 µm. The surface smoothness of the substrate (36) is preferably 0.7 arcmin or less, more preferably 0.6 arcmin or less, and even more preferably 0.5 arcmin or less. In addition, the surface smoothness can be measured by focusing irradiation light onto the surface of an object.

The substrate (36) may be composed of any suitable film. As a material that is a main component of the film constituting the substrate (36), for example, a cellulose-based resin such as triacetyl cellulose (TAC), a polyester-based resin, a polyvinyl alcohol-based resin, a polycarbonate-based resin, a polyamide-based resin, a polyimide-based resin, a polyethersulfone-based resin, a polysulfone-based resin, a polystyrene-based resin, a cycloolefin-based resin such as polynorbornene, a polyolefin-based resin, a (meth)acrylic-based resin, an acetate-based resin, etc. Here, (meth)acrylic refers to acrylic and/or methacrylic. In one embodiment, the substrate (36) is preferably composed of a (meth)acrylic-based resin. By employing a (meth)acrylic-based resin, the surface smoothness can be satisfactorily satisfied. Specifically, by employing a (meth)acrylic-based resin, a substrate having excellent surface smoothness can be formed into a film by extrusion molding.

The thickness of the surface treatment layer (38) is preferably 0.5 µm to 10 µm, more preferably 1 µm to 7 µm, and even more preferably 2 µm to 5 µm. The surface treatment layer (38) includes, for example, a hard coat layer (38a) and a functional layer (38b) having an anti-reflection function.

The hard coat layer (38a) is typically formed by applying a hard coat layer-forming material to the substrate (36) and curing the applied layer. The hard coat layer-forming material typically includes a curable compound as a layer-forming component. As a curing mechanism of the curable compound, for example, a thermosetting type or a photocuring type can be mentioned. As the curable compound, for example, a monomer, an oligomer, or a prepolymer can be mentioned. Preferably, a polyfunctional monomer or oligomer is used as the curable compound. As the polyfunctional monomer or oligomer, for example, a monomer or oligomer containing two or more (meth)acryloyl groups, urethane (meth)acrylate or an oligomer of urethane (meth)acrylate, an epoxy-based monomer or oligomer, or a silicone-based monomer or oligomer can be mentioned.

The thickness of the hard coat layer (38a) is preferably 0.5 µm to 10 µm, more preferably 1 µm to 7 µm, and even more preferably 2 µm to 5 µm.

It is preferable that the functional layer (38b) has a laminated structure including a high refractive index layer and a low refractive index layer. It is preferable that the functional layer (38b) includes a high refractive index layer and a low refractive index layer in this order from the base material (36) side. By having such a laminated structure, the above reflection characteristics can be satisfactorily satisfied.

For example, the high refractive index layer can be formed by a high refractive index resin (for example, a refractive index of 1.55 or higher measured under conditions of a wavelength of 550 nm). In this case, the high refractive index layer can be, for example, a coating layer. Also, for example, the high refractive index layer can be formed by an inorganic film. In this case, the high refractive index layer can be formed by, for example, physical vapor deposition such as vacuum deposition or sputtering, or chemical vapor deposition.

The thickness of the high refractive index layer is preferably 10 nm to 200 nm, and more preferably 20 nm to 150 nm.

The thickness of the low refractive index layer is preferably 10 nm to 200 nm, and more preferably 20 nm to 150 nm.

The above low-refractive-index layer (anti-reflection layer) can be obtained, for example, by coating a coating solution for forming a low-refractive-index layer (anti-reflection layer), drying it, and curing the resulting coating film. The coating solution for forming an anti-reflection layer may contain, for example, a resin component (curable compound), a fluorine-containing additive, hollow particles, solid particles, and a solvent, and can be obtained, for example, by mixing these.

As a curing mechanism of the resin component (curable compound) included in the coating solution for forming an antireflection layer, for example, a thermosetting type or a photocuring type can be mentioned. As the resin component, for example, a curable compound containing at least one of an acrylate group and a methacrylate group is used, and examples thereof include oligomers or prepolymers such as acrylates or methacrylates of multifunctional compounds such as silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiolpolyene resins, and polyhydric alcohols. One type of these may be used alone, or two or more types may be used in combination.

For the above resin component, a reactive diluent containing at least one of an acrylate group and a methacrylate group can be used, for example. As the reactive diluent, for example, the reactive diluent described in Japanese Patent Laid-Open No. 2008-88309 can be used, and includes, for example, a monofunctional acrylate, a monofunctional methacrylate, a polyfunctional acrylate, a polyfunctional methacrylate, and the like. As the reactive diluent, from the viewpoint of obtaining excellent hardness, a trifunctional or higher acrylate or a trifunctional or higher methacrylate is preferably used. As the reactive diluent, for example, butanediol glycerin ether diacrylate, an isocyanuric acid acrylate, an isocyanuric acid methacrylate, and the like can be mentioned. One type of these may be used alone, or two or more types may be used in combination. For curing the resin component, for example, a curing agent may be used. As a curing agent, for example, a known polymerization initiator (e.g., a thermal polymerization initiator, a photopolymerization initiator, etc.) can be used.

The above fluorine-containing additive may be, for example, an organic compound containing fluorine, or an inorganic compound containing fluorine. Examples of the organic compound containing fluorine include a fluorine-containing antifouling coating agent, a fluorine-containing acrylic compound, and a fluorine/silicon-containing acrylic compound. A commercial product can be used as the organic compound containing fluorine. Specific examples of the commercial product include the product name 'KY-1203' manufactured by Shin-Etsu Chemical Co., Ltd., and the product name 'Megapack' manufactured by DIC Co., Ltd. The content of the fluorine-containing additive may be, for example, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, 0.20 parts by weight or more, or 0.25 parts by weight or more, or 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less, relative to 100 parts by weight of the resin component.

As the hollow particles, for example, silica particles, acrylic particles, and acrylic-styrene copolymer particles can be used. The hollow silica particles can be commercially available products (for example, trade names 'Sururia 5320' and 'Sururia 4320' manufactured by Nikki Shokubai Kasei Kogyo Co., Ltd.). The weight average particle diameter of the hollow particles may be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, and 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. The shape of the hollow particles is not particularly limited, but is preferably approximately spherical. Specifically, the aspect ratio of the hollow particles is preferably 1.5 or less. The content of the hollow particles may be, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or more, or 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less, relative to 100 parts by weight of the resin component.

As the solid particles, for example, silica particles, zirconia particles, and titania particles can be used. The solid silica particles can be commercially available products (for example, product names 'MEK-2140Z-AC', 'MIBK-ST', and 'IPA-ST' manufactured by Nissan Chemical Industries, Ltd.). The weight average particle circumference of the solid particles may be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, and 330 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The shape of the hollow particles is not particularly limited, but is preferably approximately spherical. Specifically, the aspect ratio of the hollow particles is preferably 1.5 or less. The content of the solid particles may be, for example, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more, or 150 parts by weight or less, 120 parts by weight or less, 100 parts by weight or less, or 80 parts by weight or less, relative to 100 parts by weight of the resin component.

As the solvent, any appropriate solvent can be used. Examples of the solvent include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, TBA (tert-butyl alcohol), and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, MIBK (methyl isobutyl ketone), and cyclopentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, and PMA (propylene glycol monomethyl ether acetate); ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolves such as ethyl cellosolve and butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. These may be used alone or in combination of two or more. The content of the solvent may be, for example, such that the weight of the solid content relative to the total weight of the coating solution for forming the anti-reflection layer is, for example, 0.1 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 1.0 wt% or more, or 1.5 wt% or more, or 20 wt% or less, 15 wt% or less, 10 wt% or less, 5 wt% or less, or 3 wt% or less.

As a coating method of the coating solution for forming the above-mentioned anti-reflection layer, a known coating method such as a fountain coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, and a bar coating method can be used, for example. The drying temperature of the above-mentioned coating film is, for example, 30 to 200°C, and the drying time is, for example, 30 to 90 seconds. The curing of the above-mentioned coating film can be performed, for example, by heating or light irradiation (typically, ultraviolet irradiation). As a light source for the light irradiation, for example, a high-pressure mercury lamp is used. The irradiation dose of the ultraviolet irradiation is preferably 50 to 500 mJ/cm2 as an integrated exposure dose at an ultraviolet wavelength of 365 nm.

The second laminated portion (200) includes a reflective polarizing member (14) and an adhesive layer (e.g., an adhesive layer) disposed between the reflective polarizing member (14) and the second lens portion (24). The second laminated portion (200) further includes an absorbent polarizing member (28) disposed between the reflective polarizing member (14) and the second lens portion (24), for example, from the viewpoint of improving visibility. The absorbent polarizing member (28) is laminated in front of the reflective polarizing member (14) with an adhesive layer (e.g., an adhesive layer) (44) interposed therebetween. The reflection axis of the reflective polarizing member (14) and the absorption axis of the absorbent polarizing member (28) may be disposed to be approximately parallel to each other, and the transmission axis of the reflective polarizing member (14) and the transmission axis of the absorbent polarizing member (28) may be disposed to be approximately parallel to each other. By laminating with an adhesive layer interposed between them, the reflective polarizing member (14) and the absorbing polarizing member (28) are fixed, and thus misalignment of the axis arrangements of the reflective axis and the absorbing axis (the transmission axis and the transmission axis) can be prevented. In addition, adverse effects caused by an air layer that may be formed between the reflective polarizing member (14) and the absorbing polarizing member (28) can be suppressed.

The second laminated portion (200) further includes a second protective member (32) arranged at the rear of the reflective polarizing member (14). The second protective member (32) is laminated on the reflective polarizing member (14) with an adhesive layer (e.g., an adhesive layer) (43) interposed therebetween. The second protective member (32) can be positioned on the outermost surface of the second laminated portion (200). The first protective member (31) and the second protective member (32) are arranged opposite each other with a space interposed therebetween. The second protective member, like the first protective member, can be, typically, a laminated film including a substrate and a surface treatment layer. In this case, the surface treatment layer can be positioned on the outermost surface of the second laminated portion. With respect to the details of the second protective member, the same description as for the first protective member can be applied. Specifically, the same description as for the first protective member can be applied to the reflective characteristics of the second protective member and its effect, smoothness, composition, thickness and constituent materials.

In the example shown in Fig. 2, the second laminated portion (200) further includes a third phase difference member (30) arranged between the absorbing polarizing member (28) and the second lens portion (24). The third phase difference member (30) is laminated to the absorbing polarizing member (28) with an adhesive layer (e.g., an adhesive layer) (45) interposed therebetween. In addition, the third phase difference member (30) is laminated to the second lens portion (24) with an adhesive layer (e.g., an adhesive layer) (46) interposed therebetween, and the second laminated portion (200) is integrally provided with the second lens portion (24). The third phase difference member (30) includes, for example, a third λ/4 member. The angle formed by the absorption axis of the absorptive polarizing member (28) and the ground axis of the third λ/4 member included in the third phase difference member (30) is, for example, 40° to 50°, may be 42° to 48°, or may be approximately 45°. By providing such a member, it is possible to prevent reflection of external light from the second lens unit (16) side, for example. In a case where the third phase difference member does not include members other than the third λ/4 member, the third phase difference member may correspond to the third λ/4 member.

The above reflective polarizing member can transmit light polarized parallel to its transmission axis (typically linear polarization) while maintaining its polarization state, and reflect light of a polarization state other than that. The reflective polarizing member is typically composed of a film having a multilayer structure (sometimes referred to as a reflective polarizing film). In this case, the thickness of the reflective polarizing member is, for example, 10 µm to 150 µm, preferably 20 µm to 100 µm, and more preferably 30 µm to 60 µm.

Fig. 4 is a schematic perspective view showing an example of a multilayer structure included in a reflective polarizing film. The multilayer structure (14a) alternately has layers A having birefringence and layers B having substantially no birefringence. The total number of layers constituting the multilayer structure may be 50 to 1000. For example, the refractive index nx of the A layer in the x-axis direction is larger than the refractive index ny of the B layer in the x-axis direction and the refractive index ny of the B layer in the y-axis direction are substantially the same, and the refractive index difference between the A layer and the B layer is large in the x-axis direction and substantially zero in the y-axis direction. As a result, the x-axis direction can become the reflection axis and the y-axis direction can become the transmission axis. The refractive index difference between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3.

The above A layer is typically composed of a material that exhibits birefringence by stretching. Examples of such materials include naphthalene dicarboxylic acid polyester (e.g., polyethylene naphthalate), polycarbonate, and acrylic resin (e.g., polymethyl methacrylate). The above B layer is typically composed of a material that does not substantially exhibit birefringence even when stretched. Examples of such materials include copolyesters of naphthalene dicarboxylic acid and terephthalic acid. The above multilayer structure can be formed by combining coextrusion and stretching. For example, the materials constituting the A layer and the materials constituting the B layer are extruded, and then multilayered (e.g., using a multiplier). The obtained multilayer laminate is then stretched. The x-axis direction in the illustrated example can correspond to the stretching direction.

Examples of commercially available reflective polarizing films include 3M's product names 'DBEF' and 'APF', and Nitto Denko's product name 'APCF'.

The orthogonal transmittance (Tc) of the reflective polarizing member (reflective polarizing film) can be, for example, 0.01% to 3%. The group transmittance (Ts) of the reflective polarizing member (reflective polarizing film) can be, for example, 43% to 49%, and preferably 45% to 47%. The polarization degree (P) of the reflective polarizing member (reflective polarizing film) can be, for example, 92% to 99.99%.

The above orthogonal transmittance, group transmittance and polarization degree can be measured using, for example, an ultraviolet-visible spectrophotometer. The polarization degree P can be obtained by measuring the group transmittance Ts, the parallel transmittance Tp and the orthogonal transmittance Tc using an ultraviolet-visible spectrophotometer, and from the obtained Tp and Tc, by the following formula. In addition, Ts, Tp and Tc are Y values measured by a 2-degree field of view (C light source) of JIS Z8701 and subjected to visibility correction.

Polarization P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

The above-mentioned absorption-type polarizing member may include, for example, a resin film including a dichroic material (sometimes referred to as an absorption-type polarizing film). The thickness of the absorption-type polarizing film may be, for example, 1 µm or more and 20 µm or less, or 2 µm or more and 15 µm or less, or 12 µm or less, or 10 µm or less, or 8 µm or less, or 5 µm or less.

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

When producing from a single-layer resin film, for example, by performing dyeing treatment with a dichroic substance such as iodine or a dichroic dye, stretching treatment, etc. on a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, a partially formalized PVA film, or an ethylene-vinyl acetate copolymer-based partially saponified film, an absorption-type polarizing film can be obtained. Among these, an absorption-type polarizing film obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferable.

The above dyeing with iodine is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio of the above uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. In addition, dyeing may be carried out after stretching. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc.

When manufacturing using the laminate of the above two or more layers, examples of the laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. An absorption-type polarizing film obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be manufactured by, for example, applying a PVA-based resin solution to a resin substrate and drying to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to form the PVA-based resin layer as an absorption-type polarizing film. In the present embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. The stretching typically includes immersing the laminate in a boric acid aqueous solution and stretching it. In addition, the stretching may further include stretching the laminate in the 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, preferably, the laminate is provided with a dry shrinkage treatment in which the laminate shrinks by 2% or more in the width direction by heating while returning in the longitudinal direction. Typically, the manufacturing method of the present embodiment includes performing an air auxiliary stretching treatment, a dyeing treatment, an underwater stretching treatment, and a dry shrinkage treatment on the laminate in this order. By introducing the auxiliary stretching, even when PVA is applied on a thermoplastic resin, it becomes possible to increase the crystallinity of the PVA, thereby achieving high optical properties. In addition, by simultaneously increasing the orientation of the PVA in advance, it is possible to prevent problems such as a decrease in the orientation of the PVA or dissolution when immersed in water in a subsequent dyeing process or stretching process, thereby achieving high optical properties. In addition, when the PVA-based resin layer is immersed in a liquid, the alignment disorder of polyvinyl alcohol molecules and the deterioration of the alignment can be suppressed compared to when the PVA-based resin layer does not contain a halide. Accordingly, the optical characteristics of an absorption-type polarizing film obtained through a treatment process in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment, can be improved. In addition, the optical characteristics can be improved by shrinking the laminate in the width direction by a dry shrinkage treatment. The obtained resin substrate/absorptive polarizing film laminate may be used as it is (i.e., the resin substrate may be used as a protective layer of the absorption-type polarizing film), or any appropriate protective layer may be laminated on the peeling surface from which the resin substrate is peeled from the resin substrate/absorptive polarizing film laminate, or on the surface opposite to the peeling surface, depending on the purpose, and used. Details of the method for manufacturing such an absorbent polarizing film are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent Application Laid-Open No. 6470455. These publications are incorporated herein by reference in their entirety.

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

The in-plane phase difference Re(550) of the third λ/4 member 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 third λ/4 member preferably exhibits a reverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light. Re(450)/Re(550) of the third λ/4 member is, for example, 0.75 or more and less than 1, and may be 0.8 or more and 0.95 or less. The third λ/4 member preferably exhibits a refractive index characteristic of the relationship nx>ny≥nz. The Nz coefficient of the third λ/4 member is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3.

The third λ/4 member is formed of any appropriate material capable of satisfying the above characteristics. The third λ/4 member may be, for example, a stretched film of a resin film or an alignment-solidifying layer of a liquid crystal compound. The same description as that of the second λ/4 member may be applied to the third λ/4 member composed of a stretched film of a resin film or an alignment-solidifying layer of a liquid crystal compound. The second λ/4 member and the third λ/4 member may be members having the same configuration (for example, forming material, thickness, optical characteristics, etc.), or may be members having different configurations.

[Example]

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited to these examples. In addition, the thickness and surface smoothness are values measured by the following measurement method. In addition, unless specifically stated, 'part' and '%' are based on weight.

<Thickness>

Thicknesses less than 10 ㎛ were measured using a scanning electron microscope (manufactured by Nippon Electronics, product name 'JSM-7100F'). Thicknesses exceeding 10 ㎛ were measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

<Surface smoothness>

The surface smoothness was measured using a scanning white light interferometer (product name: 'NewView9000' manufactured by Zygo). Specifically, a measurement sample was placed on a measurement stage with an isolator attached, interference fringes were generated using a single white LED light, and by scanning an interference objective lens (1.4x) having a reference plane in the Z direction (thickness direction), the smoothness (surface smoothness) of the outermost surface of the measurement target in a field of view of 12.4 mm□ was selectively obtained. A 5 ㎛ thick, low-uneven acrylic adhesive layer was formed on a microslide glass (product name: 'S200200' manufactured by Matsunami Glass Kogyo Co., Ltd.), and a film to be measured was laminated onto this adhesive surface so that foreign matter, bubbles, or fringes due to deformation would not enter, and the smoothness of the surface on the opposite side to the adhesive layer was measured.

For interpretation, the value that is twice the angle index 'Slope magnitude RMS' (equivalent to 2σ) was defined as surface smoothness (unit: arcmin).

[Example 1]

(Preparation of hard coat layer forming material)

A hard coat layer-forming material was prepared by mixing 50 parts of a urethane acrylic oligomer ('NK Oligo UA-53H' manufactured by Shin-Nakamura Chemical Co., Ltd.), 30 parts of a multifunctional acrylate containing pentaerythritol triacrylate as a main component ('Viscote #300' manufactured by Osaka Yuki Chemical Co., Ltd.), 20 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Yuki Chemical Co., Ltd.), 1 part of a leveling agent ('GRANDIC PC4100' manufactured by DIC Co., Ltd.), and 3 parts of a photopolymerization initiator ('Irgacure 907' manufactured by Chiba Japan Co., Ltd.), and diluting the mixture with methyl isobutyl ketone so that the solid concentration became 50%.

(Preparation of coating solution for forming high refractive index layer)

100 parts by weight of a multifunctional acrylate (manufactured by Arakawa Chemical Industries, Ltd., trade name 'Opstar KZ6728', solid content 20 wt%), 3 parts by weight of a leveling agent (manufactured by DIC Corporation, 'GRANDIC PC4100'), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF Corporation, trade name 'OMNIRAD907', solid content 100 wt%) were mixed. The mixture was stirred so that the solid content became 12 wt% using butyl acetate as a diluting solvent, and a coating solution for forming a high refractive index layer was prepared.

(Preparation of coating solution A for forming a low refractive index layer)

100 parts by weight of a multifunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by Osaka Yuki Chemical Industry Co., Ltd., trade name 'Viscote #300', solid content 100 wt%), 150 parts by weight of hollow nano-silica particles (manufactured by Nikki Shokubai Kasei Industry Co., Ltd., trade name 'Sururia 5320', solid content 20 wt%, weight average particle diameter 75 nm), 50 parts by weight of solid nano-silica particles (manufactured by Nissan Chemical Industry Co., Ltd., trade name 'MEK-2140Z-AC', solid content 30 wt%, weight average particle diameter 10 nm), 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name 'KY-1203', solid content 20 wt%), and photopolymerization. 3 parts by weight of an initiator (manufactured by BASF, trade name 'OMNIRAD907', solid content 100 wt%) was mixed. To this mixture, a mixed solvent of TBA (tertiary butyl alcohol), MIBK (methyl isobutyl ketone), and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15 was added so that the total solid content became 4 wt%, and the mixture was stirred to prepare a coating solution for forming a low refractive index layer.

The hard coat layer forming material was applied to an acrylic film (thickness 40 ㎛, surface smoothness 0.45 arcmin) containing a lactone ring structure, heated at 90°C for 1 minute, and the applied layer after heating was irradiated with ultraviolet rays at an accumulated light amount of 300 mJ/cm2 using a high-pressure mercury lamp to harden the applied layer, thereby producing an acrylic film (thickness 44 ㎛, surface smoothness on the hard coat layer side 0.4 arcmin) having a hard coat layer having a thickness of 4 ㎛ formed thereon.

Next, the coating solution for forming the high refractive index layer was applied onto the hard coat layer using a wire bar, the applied coating solution was heated at 80°C for 1 minute, and dried to form a coating film. After drying, the coating film was irradiated with ultraviolet rays at an accumulated light amount of 300 mJ/cm2 using a high-pressure mercury lamp to harden the coating film, thereby forming a high refractive index layer having a thickness of 140 nm.

Next, the coating solution for forming the low-refractive-index layer was applied onto the high-refractive-index layer using a wire bar, the applied coating solution was heated at 80°C for 1 minute, and dried to form a coating film. After drying, the coating film was irradiated with ultraviolet rays at an accumulated light amount of 300 mJ/cm2 from a high-pressure mercury lamp to harden the coating film, and a low-refractive-index layer having a thickness of 105 nm was formed.

As a result, a laminated film having a thickness of 44 μm and a surface smoothness of 0.4 arcmin was obtained.

[Comparative Example 1]

A laminated film having a thickness of 44 μm and a surface smoothness of 0.4 arcmin was obtained in the same manner as Example 1, except that a high refractive index layer was not formed and a low refractive index layer having a thickness of 100 nm was formed using the coating solution B described below as a coating solution for forming a low refractive index layer.

(Preparation of coating solution B for forming a low refractive index layer)

100 parts by weight of a multifunctional acrylate containing pentaerythritol triacrylate as a main component (manufactured by Osaka Yuki Chemical Industries, Ltd., trade name 'Viscote #300', solid content 100 wt%), 100 parts by weight of hollow nano-silica particles (manufactured by Nikki Shokubai Kasei Industries, Ltd., trade name 'Sururia 5320', solid content 20 wt%, weight average particle diameter 75 nm), 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Industries, Ltd., trade name 'KY-1203', solid content 20 wt%), and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name 'OMNIRAD 907', solid content 100 wt%) were mixed. To this mixture, a mixed solvent of TBA (tertiary butyl alcohol), MIBK (methyl isobutyl ketone), and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15 was added so that the total solid content became 4 wt%, and stirred to prepare a coating solution B for forming an antireflection low-refractive-index layer.

[Comparative Example 2]

A laminated film having a thickness of 44 μm and a surface smoothness of 0.4 arcmin was obtained in the same manner as Example 1, except that the high refractive index layer and the low refractive index layer were not formed.

<Evaluation>

(1) 30° reflectivity

From the laminated films of Example 1, Comparative Example 1, and Comparative Example 2, test pieces measuring 50 mm × 50 mm were cut, and these were attached to a black acrylic plate using an adhesive to obtain measurement samples. As a measuring device, a spectrophotometer (manufactured by Hitachi High-Technologies, product name 'U-4100') was used to measure the reflectance spectrum. The measurement wavelength was set to be in the range of 420 nm to 680 nm, and the incident angle of light to the measurement sample was set to 30°.

The 30° specular reflectance spectra of the laminated films of Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIG. 5. As shown in FIG. 5, the maximum value of the 30° specular reflectance spectrum in the range of wavelengths 420 nm to 680 nm of the laminated film of Example 1 was 0.85%. In addition, the 30° specular reflectance at a wavelength of 450 nm was 0.15%, and the 30° specular reflectance at a wavelength of 600 nm was 0.13%. In addition, the results of Comparative Example 1 and Comparative Example 2 are as follows.

[Table 1]

(2) Appearance 1

The laminated films of Example 1, Comparative Examples 1 and 2 were attached to a black acrylic plate using an adhesive to obtain a measuring plate. In a darkroom, when light was irradiated with dimming volume 1 from a surface light-emitting unit (LED lighting box 'LLBK1' manufactured by AItec) installed facing the measuring plate at a distance of 18 cm from the measuring plate, the appearance (reflection view) of the measuring plate was confirmed with the naked eye. The reflection views are shown in Fig. 6 (a), Fig. 6 (b) and Fig. 6 (c). Specifically, Fig. 6 (a) shows the result when irradiated with white display light, Fig. 6 (b) shows the result when irradiated with blue light (wavelength 450 nm ± 30 nm), and Fig. 6 (c) shows the result when irradiated with red light (wavelength 630 nm ± 30 nm).

(3) Appearance 2

The laminated films of Example 1, Comparative Example 1, and Comparative Example 2 were attached to a transparent glass plate using an adhesive to obtain a measuring plate. A surface emitting unit (LED lighting box 'LLBK1' manufactured by AItec) was installed in a darkroom, and the measuring plate was placed on the light-emitting surface thereof. When light was irradiated from the surface emitting unit with dimming volume 1, the appearance (transparent view) of the measuring plate was confirmed with the naked eye. The transparent views are shown in Fig. 7 (a), Fig. 7 (b), Fig. 7 (c), and Fig. 7 (d). Fig. 7 (a) shows the result when irradiated with white light, Fig. 7 (b) shows the result when irradiated with blue light (wavelength 450 nm ± 30 nm), Fig. 7 (c) shows the result when irradiated with red light (wavelength 630 nm ± 30 nm), and Fig. 7 (d) shows the result when irradiated with green light (wavelength 530 nm ± 30 nm).

As shown in Fig. 6(a), Fig. 6(b), and Fig. 6(c), Example 1 is significantly superior to Comparative Example 1 and Comparative Example 2 in terms of the reflection view. In the above evaluation, a black acrylic plate was used assuming a combination with an absorption-type polarizing member, but the difference in the reflection view could also be confirmed using a transparent glass plate. According to Example 1, it is thought that the problem of ghosting that may occur due to reflected light in the display system according to the embodiment of the present invention can be solved extremely well. In addition, as shown in Fig. 7(a), Fig. 7(b), Fig. 7(c), and Fig. 7(d), Example 1, Comparative Example 1, and Comparative Example 2 do not change significantly in the transmission view.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configuration shown in the above-described embodiment may be replaced with a configuration substantially identical to the configuration shown in the above-described embodiment, a configuration exhibiting the same operational effect, or a configuration capable of achieving the same purpose.

Industrial applicability

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

2: Display System
4: Lens section
12: Display element
14: Absence of reflective polarization
16: 1st lens section
18: Half Mirror
20: Absence of first phase difference
22: Absence of second phase difference
24: Second lens section
28: Absorptive polarization absence
30: Absence of third phase difference
31: Absence of first protection
32: Absence of second protection
34: Laminated film
36: Description
38: Surface treatment layer
41: Adhesive layer
42: Adhesive layer
43: Adhesive layer
44: Adhesive layer
45: Adhesive layer
46: Adhesive layer
100: 1st layer
200: 2nd layer

Claims (10)

As a lens unit used in a display system that displays an image to a user,
A reflective polarizing member that reflects light emitted forward from the display surface of a display element that displays an image and that has passed through the polarizing member and the first λ/4 member,
A first lens unit disposed on the optical path between the display element and the reflective polarizing member;
A half mirror arranged between the display element and the first lens unit, transmitting light emitted from the display element and reflecting light reflected from the reflective polarizing member toward the reflective polarizing member;
A second lens unit arranged in front of the above reflective polarizing member,
A second λ/4 element disposed on the optical path between the half mirror and the reflective polarizing element,
A first protective member and a second protective member arranged on the optical path between the half mirror and the reflective polarizing member
Equipped with,
The above first protective member and the above second protective member are arranged opposite each other with a space between them,
The first protective member and the second protective member each have a maximum value of a 30° reflectance spectrum of 1.4% or less in a wavelength range of 420 nm to 680 nm.
Lens section. In the first paragraph,
The above first protective member and the above second protective member are lens parts, each of which has a 30° regular reflectivity of 0.5% or less at a wavelength of 450 nm. In the first paragraph,
The above first protective member and the above second protective member are lens parts, each of which has a 30° regular reflectivity of 0.5% or less at a wavelength of 600 nm. In the first paragraph,
The above first protective member and the above second protective member are lens parts, each having a surface smoothness of 0.5 arcmin or less. In the first paragraph,
The above second λ/4 element is a lens part satisfying Re(450)<Re(550). In the first paragraph,
A first laminate including the second λ/4 member and the first protective member,
A second laminated portion including the above reflective polarizing member and the second protective member,
Equipped with a lens section. In Article 6,
A lens unit, wherein the second laminated portion includes an absorptive polarizing member arranged between the reflective polarizing member and the second lens unit. In Article 6,
A lens unit, wherein the second laminated portion includes a third λ/4 member disposed between the reflective polarizing member and the second lens unit. In Article 8,
The third λ/4 element is a lens part satisfying Re(450)<Re(550). A step of passing light representing an image emitted through a polarizing member and a first λ/4 member through a half mirror and a first lens unit,
A step of passing light that has passed through the above half mirror and the first lens unit through a second λ/4 member,
A step of reflecting light passing through the second λ/4 member toward the half mirror from a reflective polarizing member,
A step of allowing light reflected from the reflective polarizing member and the half mirror to be transmitted through the reflective polarizing member by the second λ/4 member,
A step of passing light transmitted through the above reflective polarizing member through a second lens unit.
Used in a display method including,
A laminated film that is placed on the optical path between the half mirror and the reflective polarizing member and is in contact with the space formed between the first lens unit and the second lens unit,
The maximum value of the 30° reflectance spectrum in the wavelength range of 420 nm to 680 nm is 1.4% or less.
Laminated film.

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