Transmission display mirror and use of transmission display mirror

Abstract

To increase reflectance in a front side of a half mirror in an optical structure in which the half mirror and a selection reflection film are combined.SOLUTION: An optical structure 10 has a half mirror 40 and a selection reflection film 16. The half mirror 40 has a first support 15 and a partial reflection film 11. The partial reflection film 11 presents a mirror image to a front side of the first support 15. The selection reflection film 16 opposes the partial reflection film 11. The selection reflection film 16 transmits one of left circularly polarized light and right circularly polarized light, namely F polarization, much more than the other, namely R polarization. Reflectance of the selection reflection film 16 relative to R polarization is higher than reflectance of the partial reflection film 11 relative to F polarization. A gap layer 19 is provided between the selection reflection film 16 and the partial reflection film 11. The optical structure 10 further has a second support 20. The selection reflection film 16 is laminated on the front of the second support 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical structure formed by combining a half mirror and a selective reflection film.

Background Art

[0002] Patent Document 1 discloses a light reflection and transmission member which is a kind of half-silvered mirror. This light reflection and transmission member includes a support and an optical thin film laminated on the back surface of the support. The optical thin film reflects a part of light and transmits the remaining part. The optical thin film transmits the image light irradiated from the back side. Therefore, the light reflection and transmission member exhibits display characteristics. The optical thin film reflects the external light irradiated from the front. Therefore, the light reflection and transmission member exhibits mirror characteristics.

[0003] A selective reflection film is further laminated on the optical thin film. The selective reflection film selectively transmits one of the left and right circularly polarized lights and selectively reflects the other. For example, image light composed of left circularly polarized light is incident on the back surface of the light reflection and transmission member, that is, the selective reflection film. The selective reflection film transmits the left circularly polarized light and reflects the right circularly polarized light. The left circularly polarized light transmitted through the selective reflection film undergoes multiple reflections between the optical thin film and the selective reflection film. At this time, the turning direction of the image light is switched every time it is reflected. The transmittance of the left circularly polarized light in the optical thin film is higher than the transmittance of the right circularly polarized light in the selective reflection film. Therefore, the image light is preferentially emitted from the optical thin film side while repeating multiple reflections. Therefore, the selective reflection film brightens the image displayed on the light reflection and transmission member.

[0004] By appropriately designing the optical structure formed by combining the optical thin film and the selective reflection film, the sum of the transmittance of the image light and the reflectance of the external light exceeds 100% as seen from an observer observing the front surface thereof.

[0005] Paragraph

[0057] of Patent Document 2 discloses that the interface of the selective reflection film facing the half mirror similar to the above is formed of resin or air. Paragraph

[0060] discloses that the interface on the side of the reflection film of the half mirror facing the selective reflection film is formed of resin or air. Paragraph

[0059] discloses that when air is interposed between the reflection film and the selective reflection film, it is difficult to keep the distance between the reflection film and the selective reflection film constant. The same paragraph further discloses that air may be removed by interposing a transparent resin with uniform thickness.

[0006] Patent Documents 3 and 4 disclose a mirror with an image display function and a half mirror including a circularly polarized light reflection layer.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a means suitable for further increasing the reflectance on the front side of a half mirror in an optical structure formed by combining a half mirror and a selective reflection film.

Means for Solving the Problems

[0009] [1] An optical structure formed by combining a half mirror and a selective reflection film, The half mirror includes a first support and a partial reflection film laminated on the back surface of the first support. By reflecting external light incident from the front side of the first support, the partial reflection film presents a mirror image on the front side of the first support. The selective reflection film is further provided on the back side of the half mirror so as to face the partial reflection film. The selective reflection film transmits one of left-circularly polarized light and right-circularly polarized light, hereinafter referred to as F-polarized light, better than the other, hereinafter referred to as R-polarized light, throughout the visible light band, and reflects R-polarized light better than F-polarized light. The reflectance of the selective reflection film with respect to R-polarized light is higher than the reflectance of the partial reflection film with respect to F-polarized light throughout the visible light band. An air gap layer is provided between the selective reflection film and the partial reflection film. It further includes a second support facing the first support. The selective reflection film is laminated on the front surface of the second support. Optical structure. [2] The selective reflection film is made of either nematic liquid crystal or smectic liquid crystal. The liquid crystal consists of a chiral phase. The phase consists of a liquid crystal molecule added with a chiral dopant or consists of chiral liquid crystal molecules. The optical structure according to [1]. [3] The selective reflection film is made of cholesteric liquid crystal. The optical structure according to [1]. [4] A protective film is further formed on the front surface of the selective reflection film. The optical structure according to [2] or [3]. [5] The air gap layer consists of a space filled with air or a gas other than air. The partial reflection film consists of either a dielectric multilayer film or a single-layer film of metal oxide and is exposed to the space. The optical structure according to any one of [1] to [4]. [6] An antireflection film is further formed on the front surface of the selective reflection film. [1] The optical structure according to any one of [1] to [5]. [7] An antireflection film is further formed on the back surface of the second support. [1] The optical structure according to any one of [1] to [6]. [8] In the half mirror, its reflectance is greater than its transmittance. [1] The optical structure according to any one of [1] to [7]. [9] A quarter-wave plate is further laminated between the selective reflection film and the second support. [1] The optical structure according to any one of [1] to [8].

[10] Use of the optical structure according to [9], By irradiating the image light composed of linearly polarized light or elliptically polarized light to the back side of the second support, converting it into image light composed of F-polarized light by the quarter-wave plate, By emitting the image light composed of F-polarized light from the front surface of the first support, presenting an image brighter than the mirror image on the front surface of the first support superimposed on the mirror image, By dimming the image light irradiated to the back side of the second support, restoring the mirror image buried in the image on the front surface of the first support. Use.

[11] A mirror for superimposing and displaying an image on a mirror image, hereinafter referred to as a transmissive display mirror, Comprising the optical structure according to [9] and a display panel for irradiating the back surface of the second support with image light composed of linearly polarized light, The display panel faces the back surface of the second support and has a display surface for emitting the image light composed of linearly polarized light. The fast axis and the slow axis of the quarter-wave plate are inclined by 45° with respect to the polarization axis of the linearly polarized light in the direction of converting the linearly polarized light into polarized light Fp. A gap layer is provided between the second support and the display panel. Transmissive display mirror.

[12] A mirror that superimposes and displays an image with respect to a mirror image, hereinafter referred to as a transmissive display mirror, comprising: an optical structure according to [9], and a display panel that irradiates image light composed of linearly polarized light onto the back surface of the quarter-wave plate; the second support is integrated with the display panel; the front surface of the second support is the display surface of the display panel; the display surface emits the image light composed of linearly polarized light; the fast axis and the slow axis of the quarter-wave plate are inclined by 45° with respect to the polarization axis of the linearly polarized light in a direction that converts the linearly polarized light into polarized light Fp; Transmissive display mirror.

[13] Further comprising a light-shielding plate; the display panel covers the center of the back surface of the half mirror, and the light-shielding plate covers the outer edge of the back surface of the half mirror, so that the entire back surface of the half mirror is covered; The transmissive display mirror according to

[11] or

[12] .

[14] Use of the optical structure according to any one of [1] to [8], irradiating image light composed of F-polarized light from the back side of the second support, and emitting the image light composed of F-polarized light from the front of the first support, thereby presenting an image brighter than the mirror image on the front of the first support superimposed on the mirror image; by dimming the image light, restoring the mirror image that was buried in the image on the front of the first support; Use.

[15] Use of the optical structure according to any one of [1] to [8], irradiating first image light composed of F-polarized light from the back side of the second support at an angle with respect to the optical structure, and emitting the first image light composed of F-polarized light from the front of the first support, thereby presenting a first image on the front of the first support; Furthermore, by irradiating the second image light as the external light from the front side of the first support body while tilting it with respect to the optical structure, a second image is presented as the mirror image on the front surface of the second support body. On the front surface of the first support body, the bright part of the second image is presented in the dark part of the first image, and the bright part of the first image is presented in the dark part of the second image. Use.

[16] By irradiating image light composed of linearly polarized light or elliptically polarized light from the further back side of a quarter-wave plate provided on the back side of the selective reflection film, this is converted into image light composed of F-polarized light.

[14] Or the use according to

[15] .

[17] A method for manufacturing the optical structure according to any one of [1] to [8], By attaching a protective film laminated with the selective reflection film to the front surface of the second support body, a filter is formed. Here, in the filter, the protective film, the selective reflection film, and the second support body are arranged in this order from the front surface to the back surface. A gas is sandwiched between the front surface of the filter and the back surface of the half mirror, and these are overlapped. The half mirror and the filter are fixed to each other with a fixture so that they do not separate. Method.

Effect of the Invention

[0010] According to the present invention, in an optical structure formed by combining a half mirror and a selective reflection film, it is possible to provide a means suitable for further increasing the reflectance on the front side of the half mirror.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0012] <Optical Structure>

[0013] FIG. 1 shows an optical structure 10 formed by combining a half mirror 40 and a selective reflection film 16. For convenience of explanation, the side of the half mirror 40 is defined as the front of the optical structure 10, and the side of the selective reflection film 16 is defined as the back of the optical structure 10. The front and back of the components within the optical structure 10 and the elements combined therewith are uniformly defined. Observer Ob observes the optical structure 10 from its front.

[0014] <Half Mirror>

[0015] As shown in FIG. 1, the half mirror 40 includes a partial reflection film 11 and a transparent first support 15. The partial reflection film 11 is laminated on the back of the first support 15. The first support 15 is in contact with the partial reflection film 11. The first support 15, together with the partial reflection film 11, exhibits the function of a half mirror.

[0016] In one aspect shown in FIG. 1, the entire first support 15 is transparent. In other aspects, the first support 15 has a transparent region and an opaque region. Circularly polarized light passes through the transparent region. In one aspect, the first support 15 is flat. In other aspects, the first support 15 is curved. In one aspect, at least one of the front and back of the first support 15 is flat. In other aspects, at least one of the front and back of the first support 15 is curved.

[0017] In one aspect shown in FIG. 1, the first support 15 is a plate made of a transparent base material. The base material has a transmittance of 20% or more and 100% or less across the entire visible light band. In an optical material, light is reflected at its surface, i.e., the so-called interface. Therefore, the transmittance of the optical material itself may be referred to as the internal transmittance. Also, the overall transmittance including the interface may be referred to as the external transmittance. In this embodiment, unless otherwise specified, the transmittance refers to the external transmittance. The transmittance is interpreted in the same way for other elements made of a transparent base material in this specification.

[0018] In one aspect, the transmittance of the first support 15 is 30% or more and less than 100%. In one aspect, the transmittance is any one of 30, 40, 50, 60, 70, 80, and 90%. The base material is colorless or colored. The surface of the base material is smooth. In one aspect, the base material is made of inorganic glass. In one aspect, the inorganic glass is laminated glass. In other aspects, the base material is made of plastic. In one aspect, the plastic is either acrylic or polycarbonate. In other aspects, the first support 15 is made of inorganic glass and other members. In such an aspect, light passes through the region made of inorganic glass. In that one aspect, the other member is plastic. In that one aspect, the plastic is acrylic, polycarbonate, and other plastics.

[0019] The partial reflection film 11 shown in FIG. 1 partially transmits light. The partial reflection film 11 partially reflects light. In one aspect, the partial reflection film 11 is a thin film made of a metal, a metal oxide, and other dielectrics. In one aspect, the metal is aluminum. In one aspect, the metal oxide contains either titanium oxide or niobium oxide. In one aspect, the partial reflection film 11 is a single-layer film of a metal oxide. In another aspect, the partial reflection film 11 is a dielectric multilayer film. In one aspect, the dielectric multilayer film contains a layer of either a metal oxide or a metal fluoride. The ratio of the reflectance to the transmittance of a single-layer film of a metal oxide or a dielectric multilayer film is easier to adjust than that of other thin films.

[0020] In another aspect shown in FIG. 1, the partial reflection film 11 is a metal thin film. In one aspect, a transparent protective film is formed on the upper layer of the metal thin film to protect it. In one aspect, the transparent protective film is an organic thin film. The thickness of the metal thin film may be appropriately designed according to the desired transmittance. When a touch panel is installed on the first support 15, the metal thin film provided on the partial reflection film 11 may be used as a sensor electrode or a part of the sensor electrode.

[0021] In one aspect shown in FIG. 1, the partial reflection film 11 is directly formed on the back surface of the first support 15. In other aspects, a thin film is formed on another transparent substrate and then attached to the support to form the partial reflection film 11. In one aspect, a transparent adhesive layer is used for the attachment.

[0022] In one aspect, the transparent adhesive layer is made of OCA (Optical Clear Adhesive). In one aspect, OCA is an adhesive sheet in the form of a film itself, which is used for bonding films together. Hereinafter, unless otherwise specified, the term "transparent adhesive layer" refers to a similar transparent adhesive layer.

[0023] In FIG. 1, the half mirror 40 transmits a part of the light and reflects the remaining part of the light. In one aspect, the reflectance of the half mirror 40 is higher than the transmittance over the entire visible light band. This reflectance is when no other devices such as a filter 50 or a display panel are installed on the back side of the half mirror 40.

[0024] In one aspect, the reflectance of the half mirror 40 for light with a wavelength of 550 nm is higher than the transmittance. Such reflectance is for the light incident on the front surface of the half mirror 40. In one aspect, the half mirror 40 has a reflectance of 30% or more and less than 100% for light with a wavelength of 550 nm. In one aspect, the reflectance is any one of 35, 40, 45, 50, 52, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 75, 80, 85, 90, and 95%.

[0025] In another aspect of the half mirror 40 shown in FIG. 1, across the entire visible light band, its transmittance is higher than its reflectance. In another aspect, the transmittance of the half mirror 40 for light with a wavelength of 550 nm is higher than its reflectance. In another aspect, across the entire visible light band, the reflectance of the half mirror 40 is equal to its transmittance. In another aspect, the reflectance of the half mirror 40 for light with a wavelength of 550 nm is equal to its transmittance. In this specification, the term "half mirror" is not limited to those in which the transmittance and reflectance are identical.

[0026] In one aspect shown in FIG. 1, there is an interface 14 between the partial reflection film 11 and the first support 15. The interface 14 reflects the external light Ex incident on the front surface of the first support 15. In one aspect, the interior of the partial reflection film 11 reflects the external light Ex incident on the front surface of the first support 15. The interface 14 and the partial reflection film 11 present a mirror image on the front side of the first support 15. The observer Ob observes the mirror image from the front side of the first support 15. Unless otherwise specified, the "mirror image" in this embodiment is the mirror image observed from the front side of the first support 15.

[0027] In one aspect shown in FIG. 1, the interior of the interface 14 and the partial reflection film 11 reflect the external light Ex evenly across the entire visible light band. In one aspect, the dielectric multilayer film or its interface 14 reflects the external light Ex evenly across the entire visible light band.

[0028] <Void layer>

[0029] As shown in FIG. 1, a void layer 19 is provided between the selective reflection film 16 and the partial reflection film 11. In one aspect, the void layer 19 consists of a space filled with air. In another aspect, the void layer 19 consists of a space filled with a gas other than air. In one aspect, the void layer 19 is a vacuum.

[0030] In one aspect shown in FIG. 1, the mirror image generated by reflecting the external light Ex with the partial reflection film 11 is defined as the zero-order image (zero). The external light Ex is reflected at the front interface of the half mirror 40, generating a mirror image, that is, a first-order ghost (1st). Also, the external light Ex is reflected at the front of the filter 50, generating a mirror image, that is, a second-order ghost (2nd). Both the first-order ghost and the second-order ghost are darker than the zero-order image. When the air gap layer 19 is equal to half the thickness of the support 15, the first-order ghost and the second-order ghost overlap and become brighter. Therefore, it is preferable that the thickness of the air gap layer 19 is greater than 0 mm and less than half the thickness of the support 15. In one aspect, the thickness is greater than 0 mm and less than 2.5 mm. In one aspect, the thickness is either 1 mm or 0.1 mm. In one aspect, by reducing the thickness of the air gap layer 19, the generation of ghosts is suppressed. Also, the image displayed on the front of the optical structure 10, for example, an image consisting of characters, is prevented from being blurred by ghosts.

[0031] As shown in FIG. 1, the partial reflection film 11 is exposed to the space constituting the air gap layer 19. In one aspect, the partial reflection film 11 is made of a dielectric multilayer film or a metal film. In this case, even if the partial reflection film 11 is not covered with a protective film, it is unlikely that the material constituting the partial reflection film 11 peels off and falls toward the space constituting the air gap layer 19. Also, the external light Ex is reflected at the interface between the partial reflection film 11 and the air gap layer 19. The greater the difference between the refractive index of the partial reflection film 11 and the refractive index of the air gap layer 19, the higher the reflectivity.

[0032] <Filter and Second Support>

[0033] As shown in FIG. 1, the optical structure 10 includes a filter 50. The filter 50 includes a selective reflection film 16 and a transparent second support 20. The second support 20 faces the first support 15. The selective reflection film 16 is laminated on the front surface of the second support 20. The selective reflection film 16 faces the partial reflection film 11 on the back side of the half mirror 40. The second support 20 may be connected to the first support 15. The second support 20 may form an integral structure with the first support 15.

[0034] In one aspect shown in FIG. 1, the entire second support 20 is transparent. In other aspects, the second support 20 has transparent regions and opaque regions. Circularly polarized light passes through the transparent regions. In one aspect, the second support 20 is flat. In other aspects, the second support 20 is curved. In one aspect, at least one of the front and back surfaces of the second support 20 is flat. In other aspects, at least one of the front and back surfaces of the second support 20 is curved.

[0035] In one aspect shown in FIG. 1, the second support 20 is a plate made of a transparent substrate. In one aspect, the transmittance of the second support 20 is 30% or more and less than 100%. In one aspect, the transmittance is any one of 30, 40, 50, 60, 70, 80, and 90%. The substrate is colorless or colored. The surface of the substrate is smooth.

[0036] In one aspect, the substrate is made of inorganic glass. In one aspect, the inorganic glass is alkali-free glass. In one aspect, the inorganic glass is soda-lime glass with a small Fe component. Alkali-free glass is more rigid than soda glass. In one aspect, the inorganic glass is laminated glass. In other aspects, the substrate is made of plastic. In one aspect, the plastic is either acrylic or polycarbonate.

[0037] In another aspect shown in FIG. 1, the second support 20 is composed of inorganic glass and other members. In such an aspect, light passes through the region made of inorganic glass. In one aspect, the other member is plastic. In one aspect, the plastic is acrylic, polycarbonate, and other plastics.

[0038] In one aspect shown in FIG. 1, the thickness of the second support 20 is 0.3 to 3 mm. The second support 20 thinner than 3 mm makes the thickness of the void layer 19 uniform throughout. The second support 20 thicker than 0.3 mm helps to stably attach the selective reflection film 16 on the second support 20. In one aspect, the thickness of the second support 20 is 0.5 to 2 mm.

[0039] <Selectivity of Transmission and Reflection>

[0040] In one aspect shown in FIG. 1, the filter 50 controls the transmission and reflection of circularly polarized light. In this embodiment, particularly due to the reflection at the half mirror 40 and the filter 50, the left and right rotation directions of the circularly polarized light are interchanged. In this embodiment, both left circularly polarized light and right circularly polarized light can be used. In this case, it is preferable to use a substrate with low birefringence and optically isotropic, such as inorganic glass, for the second support 20.

[0041] Hereinafter, for convenience of explanation, one of left circularly polarized light and right circularly polarized light is referred to as F polarized light, and the other is referred to as R polarized light. If the F polarized light is left circularly polarized light, the R polarized light is right polarized light. Left circularly polarized light is circularly polarized light that forms a right-handed helix with respect to the direction of light propagation. Right circularly polarized light is circularly polarized light that forms a left-handed helix with respect to the direction of light propagation.

[0042] As shown in FIG. 1, polarized light Fp is incident on the back surface of the second support 20. The polarized light Fp is F polarized light. The polarized light Fp in the figure is left circularly polarized light. Also, the polarized light Fp is reflected at the back surface of the partial reflection film 11 and becomes polarized light Rp. The polarized light Rp is R polarized light. The polarized light Rp in the figure is right circularly polarized light. In another aspect, the polarized light Fp is right circularly polarized light, and the polarized light Rp is left circularly polarized light.

[0043] In one aspect shown in FIG. 1, the selective reflection film 16 transmits polarized light Fp better than polarized light Rp in a broad band in the visible light band. In one aspect, the broad band refers to a band width of at least 150 nm or more and less than the entire visible light band in the visible light band. In one aspect, the broad band refers to band widths of 200, 250, 300, 350, 400, and 450 nm. The same shall apply hereinafter. In one aspect, whether the transmission or reflection of the selective reflection film 16 and other optical elements is in a broad band is determined by the full width at half maximum of the spectrum of the transmitted light or the reflected light.

[0044] In another aspect shown in FIG. 1, the selective reflection film 16 transmits polarized light Fp better than polarized light Rp throughout the visible light band. In one aspect, the entire visible light band is from a wavelength of 400 to 750 nm. In another aspect, the lower bound of the wavelength of visible light is from 360 to 400 nm. The upper bound is from 760 to 830 nm. The same shall apply hereinafter. In one aspect, whether the transmission or reflection of the selective reflection film 16 and other optical elements is throughout the visible light band is determined by the full width at half maximum of the spectrum of the transmitted light or the reflected light.

[0045] In one aspect shown in FIG. 1, the selective reflection film 16 selectively transmits polarized light Fp and selectively reflects polarized light Rp in a broad band in the visible light band. In another aspect, the selective reflection film 16 selectively transmits polarized light Fp and selectively reflects polarized light Rp throughout the visible light band. Such a selective reflection film 16 suppresses the coloring of light.

[0046] In one aspect shown in FIG. 1, the reflectivity of the selective reflection film 16 with respect to polarized light Rp is higher than the reflectivity of the partial reflection film 11 with respect to polarized light Fp in a broad band in the visible light band. In another aspect, the reflectivity of the selective reflection film 16 with respect to polarized light Rp is higher than the reflectivity of the partial reflection film 11 with respect to polarized light Fp throughout the visible light band.

[0047] In one aspect shown in FIG. 1, the transmittance of the partial reflection film 11 with respect to the polarized light Fp is higher than the transmittance of the selective reflection film 16 with respect to the polarized light Rp in a wide band in the visible light band. In other aspects, the transmittance of the partial reflection film 11 with respect to the polarized light Fp is higher than the transmittance of the selective reflection film 16 with respect to the polarized light Rp over the entire visible light band.

[0048] <Configuration of the selective reflection film>

[0049] In one aspect shown in FIG. 1, the selective reflection film 16 is made of either nematic liquid crystal or smectic liquid crystal. The liquid crystal consists of a phase having chirality. In one aspect, such a phase consists of a liquid crystal molecule to which a chiral dopant is added. In other aspects, such a phase consists of chiral liquid crystal molecules. In one aspect, the selective reflection film 16 is made of cholesteric liquid crystal. In other aspects, the selective reflection film 16 is made of other liquid crystals having cholesteric regularity.

[0050] In one aspect, cholesteric regularity refers to a state in which molecules aligned in one direction form layers, and the alignment direction shifts slightly for each adjacent molecular layer, and the molecular layers form a helical structure. Cholesteric regularity can also be seen in liquid crystals other than cholesteric liquid crystals. In one aspect, in order to fix the cholesteric regularity, the phase of the liquid crystal having cholesteric regularity is fixed. In one aspect, the selective reflection film is a polymer film obtained by curing a film of cholesteric liquid crystal.

[0051] In other aspects, the liquid crystal is a discotic liquid crystal having a helical axis. In one aspect, a discotic liquid crystal having a helical axis is obtained by adding a chiral dopant to discotic liquid crystal molecules having no helical axis. In one aspect, the discotic liquid crystal having a helical axis has cholesteric regularity.

[0052] The chiral dopant introduced into the liquid crystal molecules induces twist in the liquid crystal molecules, thereby imparting optical activity thereto. In one aspect, by adjusting the concentration of the chiral dopant, the helical pitch of the chiral structure of the liquid crystal molecules can be varied in various ways. In other aspects, the helical pitch can be varied in various ways by changing the types of liquid crystal molecules and chiral dopants.

[0053] In one aspect, the phase of the liquid crystal having cholesteric regularity has a helical axis parallel to the normal direction to the selective reflection film. In one aspect, the direction of the helical axis of all phases of the liquid crystal having cholesteric regularity is parallel to the normal direction to the selective reflection film. In one aspect, the average of the direction of the helical axis of the phase of the liquid crystal having cholesteric regularity is parallel to the normal direction to the selective reflection film.

[0054] The liquid crystal having cholesteric regularity has a predetermined helical structure. In such a helical structure, circularly polarized light incident from a direction parallel to the helical axis and in the same direction as the turning direction of the helical structure is reflected. A right-handed helical structure reflects right circularly polarized light, that is, left-handed circularly polarized light. A left-handed helical structure reflects left circularly polarized light, that is, right-handed circularly polarized light. The circularly polarized light reflected by the helical structure is the above-described R polarized light. Selective reflection means selectively reflecting R polarized light.

[0055] Circularly polarized light incident from a direction parallel to the helical axis and in the opposite direction to the turning direction of the helical structure is transmitted. A left-handed helical structure transmits right circularly polarized light, that is, left-handed circularly polarized light. A right-handed helical structure reflects left circularly polarized light, that is, right-handed circularly polarized light. The circularly polarized light transmitted by the helical structure is the above-described F polarized light. The selective reflection film selectively reflects R polarized light and, conversely, selectively transmits F polarized light. In one aspect, the selective reflection film transmits light other than circularly polarized light.

[0056] In selective reflection, the central wavelength λ of the circularly polarized light to be reflected is represented by the product of the pitch p (μm) of the helical structure and the average refractive index n[av] of the liquid crystal in a plane orthogonal to the helical axis, as shown in the following formula (1).

[0057] λ = p × n[av] (Equation (1))

[0058] The bandwidth W of the wavelength of the reflection is represented by the product of the birefringence anisotropy Δn of the liquid crystal and p, as shown in the following Equation (2).

[0059] W = p × Δn (Equation (2))

[0060] In one aspect shown in FIG. 1, the selective reflection film 16 is a single-layer film. In other aspects, the selective reflection film 16 is a multi-layer film.

[0061] In one aspect, the selective reflection film is formed by laminating a plurality of films with different helical pitches. In one aspect, these are laminated in the order of the magnitude of the helical pitch. The films with different helical pitches have different selective reflection bands from each other. The bandwidth W of such a multi-layer selective reflection film is larger than that of a single-layer film. In one aspect, the bandwidth W is broadband. In other aspects, the bandwidth W covers the entire visible light band.

[0062] In other aspects, the selective reflection film is a single-layer film. The magnitude of the helical pitch continuously changes within the single-layer film. Or, the orientation of the helical axis continuously changes within the single-layer film. In other aspects, the selective reflection film is formed by laminating a plurality of the above single-layer films.

[0063] <Manufacture of the Selective Reflection Film>

[0064] In one aspect, the above single-layer film is produced using a liquid crystal composition that can be cured after coating. The single-layer film is produced by curing the liquid crystal composition multiple times while changing the light irradiation conditions for the liquid crystal composition. In other aspects, the single-layer film is produced by curing the liquid crystal composition multiple times while changing the alignment conditions of the liquid crystal by heating. In other aspects, the coating of the liquid crystal composition and the curing of the liquid crystal composition are combined and carried out separately multiple times.

[0065] In one aspect, the liquid crystal composition contains liquid crystal molecules of nematic liquid crystal or smectic liquid crystal having a polymerizable functional group, and a chiral dopant having another polymerizable functional group that polymerizes with such a polymerizable functional group. In another aspect, the liquid crystal composition contains liquid crystal molecules of discotic liquid crystal having a polymerizable functional group, and a chiral dopant having another polymerizable functional group that polymerizes with such a polymerizable functional group. In another aspect, the liquid crystal composition contains liquid crystal molecules having a polymerizable functional group and liquid crystal molecules having no polymerizable functional group. In one aspect, the liquid crystal molecules before polymerization with the chiral dopant are low molecular weight compounds or monomers. In another aspect, the liquid crystal molecules before polymerization with the chiral dopant are polymers.

[0066] In one aspect, the chiral dopant does not have a polymerizable functional group necessary for polymerization with the liquid crystal molecules. In one aspect, a molecule that is neither a liquid crystal molecule nor a chiral dopant polymerizes with the liquid crystal molecules. In another aspect, the liquid crystal composition contains a chiral dopant having a polymerizable functional group necessary for polymerization with the liquid crystal molecules and a chiral dopant not having the same.

[0067] In one aspect, the liquid crystal composition contains at least one of a solvent, a polymerization initiator, a polymerization inhibitor, an ultraviolet light absorber, an antioxidant, a light stabilizer, a horizontal alignment agent, a non-uniformity preventing agent, a peeling preventing agent, a plasticizer, and other additives. The strength of the selective reflection film can be increased by adding a plasticizer. In one aspect, these additives do not harm the formation of the phase of the liquid crystal having cholesteric regularity.

[0068] Examples of the light stabilizer include hindered amines, as well as nickel bis(octylphenyl) sulfide, nickel complex-3,5-di-tert-butyl-4-hydroxybenzyl phosphate monoethylate, nickel dibutyldithiocarbamate, and other nickel complexes. Two or more of these may be used in combination. The content of the light stabilizer in the liquid crystal composition is preferably 0.01 to 1 part by mass, particularly preferably 0.1 to 0.3 part by mass, based on 100 parts by mass of the total amount of the liquid crystal molecules.

[0069] In one aspect, the polymerization initiator is a photoinitiator or a thermal polymerization initiator. Examples of the photoinitiator include acetophenones, benzophenones, benzoins, benzyls, Michler's ketones, benzoin alkyl ethers, benzyldimethyl ketals, phosphine oxides, thioxanthones, and other photoinitiators. Examples of the thermal polymerization initiator include azobis-based, peroxide-based, and other thermal polymerization initiators. These may be used in combination of two or more. The content of the polymerization initiator in the liquid crystal composition is preferably 0.01 to 5% by mass, particularly preferably 0.03 to 2% by mass, based on the total amount of the liquid crystal composition.

[0070] In one aspect, a chiral dopant is added to the liquid crystal molecule having a polymerizable functional group. The chiral dopant and the liquid crystal molecule form a liquid crystal phase having a helical axis. The polymerization of the chiral dopant and the liquid crystal molecule fixes the liquid crystal phase having a helical axis. It selectively reflects R-polarized light over the entire visible light band.

[0071] In the filter 50 shown in FIG. 1, an example of a method for forming a selective reflection film 16 on the second support 20 is shown below. First, a liquid crystal composition containing liquid crystal molecules having polymerizable functional groups and a chiral dopant having polymerizable functional groups is applied onto the second support 20. In one aspect, the chiral dopant is 1 to 30 moles per 100 moles of liquid crystal molecules. The solvent in the liquid crystal composition is removed by drying the coating film. By changing the temperature conditions during drying, a phase of a liquid crystal having cholesteric regularity is formed. A polymerization reaction is carried out while maintaining the cholesteric regularity in the liquid crystal phase. The polymerization is initiated by applying light or heat to the liquid crystal composition. In one aspect, the temperature during polymerization is 10 °C or more lower than the phase transition temperature (Tc) between the phase of the liquid crystal having cholesteric regularity and the isotropic phase. Thereby, a phase of a liquid crystal having cholesteric regularity can be stably formed. In one aspect, the polymerization is radical polymerization. In other aspects, the polymerization is polycondensation. In one aspect of polycondensation, water and other volatile components are generated during polymerization. In other aspects, by-products are generated during polymerization. In one aspect, a polymerization is selected in which these volatile components and by-products do not adversely affect the liquid crystal properties including cholesteric regularity.

[0072] In other aspects, the liquid crystal molecules of discotic liquid crystals are polymerized. For example, it is carried out by the method described in JP-A-8-27284.

[0073] The light source used for light irradiation of the liquid crystal composition is not particularly limited. For example, a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, and other light sources can be used.

[0074] The liquid crystal composition preferably contains 75% by mass or more, more preferably 90% by mass or more, in total, of liquid crystal molecules having polymerizable functional groups and a chiral dopant having polymerizable functional groups that polymerizes with the former. The liquid crystal composition preferably contains 75% by mass or more, particularly 85% by mass or more, of liquid crystal molecules having polymerizable functional groups.

[0075] In one aspect, the selective reflection film 16 is manufactured using the liquid crystal composition and manufacturing method described above. In other aspects, the selective reflection film is manufactured using the liquid crystal molecules and manufacturing methods described in International Publication No. WO2010 / 143683, Japanese Patent Application Laid-Open No. 2010-61119, and Japanese Patent Application Laid-Open No. 2011-203426.

[0076] <Multiple reflection>

[0077] In FIG. 1, the selective reflection film 16 transmits most of the polarized light Fp. The partial reflection film 11 reflects a part of the polarized light Fp as polarized light Rp. The circular polarization rotation direction of the polarized light Rp is reversed with respect to the polarized light Fp. The partial reflection film 11 transmits the remaining part of the polarized light Fp. The selective reflection film 16 reflects most of the polarized light Rp as polarized light Fp. The circular polarization rotation direction of the polarized light Fp is reversed with respect to the polarized light Rp. Thereafter, multiple reflection occurs between the partial reflection film 11 and the selective reflection film 16.

[0078] In the multiple reflection shown in FIG. 1, the circular polarization direction is switched every time it is reflected. The polarized light incident on the back surface of the partial reflection film 11 is the polarized light Fp. The polarized light incident on the front surface of the selective reflection film 16 is the polarized light Rp. As described above, the transmittance of the polarized light Fp in the partial reflection film 11 is higher than the transmittance of the polarized light Rp in the selective reflection film 16. Therefore, the circular polarization preferentially exits from the side of the partial reflection film 11 while repeating multiple reflection. The selective reflection film 16 converts the polarized light Rp returned by the partial reflection film 11 to the back side into polarized light Fp and reflects it, thereby pushing it back to the front side. Therefore, the selective reflection film 16 enhances the light emitted to the front side.

[0079] In one aspect shown in FIG. 1, the transmittance of the polarized light Fp in the partial reflection film 11 and the transmittance of the polarized light Rp in the selective reflection film 16 are appropriately designed. In this case, when observed from an observer observing the optical structure 10 from the front, the sum of the transmittance of the polarized light Fp in the optical structure 10 and the reflectance of the external light Ex exceeds 100%.

[0080] In one aspect shown in FIG. 1, the partial reflection film 11 has poor selectivity with respect to the direction of rotation of circularly polarized light. In one aspect, the partial reflection film 11 is a film having the property of not selectively reflecting either the polarized light Fp or the polarized light Rp. In one aspect, the partial reflection film 11 is a film having the property of reflecting both the polarized light Fp and the polarized light Rp with the same reflectance. In one aspect, the partial reflection film 11 is a film having the property of transmitting both the polarized light Fp and the polarized light Rp with the same transmittance.

[0081] In one aspect shown in FIG. 1, more polarized light Fp than polarized light Rp is incident on the back surface of the partial reflection film 11 having such poor selectivity. In one aspect, the bias in the direction of rotation of the circularly polarized light incident on the partial reflection film 11 is generated by the selective reflection film 16. In one aspect, the bias in the direction of rotation of the circularly polarized light incident on the partial reflection film 11 is generated by the light source. In one aspect, the light source emits circularly polarized light that passes through the selective reflection film 16.

[0082] <The second support and the air gap layer>

[0083] In FIG. 1, the selective reflection film 16 made of liquid crystal molecules is brittle by itself. Such a selective reflection film 16 is difficult to stand on its own against gravity. The optical structure 10 requires a support for supporting the selective reflection film 16. Here, there is an air gap layer 19 between the first support 15 and the selective reflection film 16. Therefore, the first support 15 cannot effectively support the selective reflection film 16 from its front side. Therefore, instead of the first support 15, the second support 20 supports the selective reflection film 16 from its back side.

[0084] As shown in FIG. 1, the first support 15 and the second support 20 stably maintain the distance between the partial reflection film 11 and the selective reflection film. Therefore, these supports prevent the air gap layer 19 from being crushed. In one aspect, the partial reflection film 11 and the selective reflection film 16 are parallel over the entire area where they face each other. These supports can suppress the generation of interference fringes by bringing the partial reflection film 11 and the selective reflection film 16 closer to parallel.

[0085] As described above, in FIG. 1, the second support 20 assists the void layer 19 in further increasing the reflectance on the front side of the half mirror 40. The second support 20 assists the void layer 19 in brightening the mirror image observed from the front side of the half mirror 40.

[0086] <Transmissive display mirror>

[0087] FIG. 2 is used to show an example of the use of the optical structure 10. The figure shows a transmissive display mirror 60 including the optical structure 10 and a display panel 30. The transmissive display mirror 60 is a mirror that superimposes and displays an image on its front side with respect to the mirror image. In one aspect, the image includes at least one of a moving image and a still image. In one aspect, the transmissive display mirror 60 is a mirror display that realizes mirror characteristics and display characteristics in the same region.

[0088] As shown in FIG. 2, the display panel 30 is disposed on the back side of the optical structure 10. The display panel 30 has a display surface 31 on its front side. The display surface 31 faces the back side of the second support 20. In one aspect, the optical structure 10 covers the entire display surface 31. The display surface 31 emits image light Im composed of linearly polarized light. The display surface 31 irradiates the image light Im onto the back side of the second support 20. The image included in the image light Im is observed from the front side of the optical structure 10 as a transmissive image.

[0089] <Protection of the selective reflection film and laminate>

[0090] In one aspect shown in FIG. 2, a laminate 55 is laminated on the second support 20. The laminate 55 includes a protective film 17 and a selective reflection film 16. The selective reflection film 16 is laminated on the protective film 17. In one aspect, the selective reflection film 16 is bonded to the back side of the protective film 17 via a transparent adhesive layer (not shown). In that aspect, the transparent adhesive layer contains an ultraviolet absorber. The ultraviolet absorber protects the selective reflection film 16 from ultraviolet rays included in external light.

[0091] In one aspect shown in FIG. 2, the selective reflection film 16 is located on the back surface of the protective film 17. The protective film 17 covers the front surface of the selective reflection film 16. In an aspect different from the aspect shown in the figure, the selective reflection film 16 is located on the front surface of the protective film 17. Inside the filter 50, the protective film 17, the selective reflection film 16, and the second support 20 are arranged in this order from the front surface to the back surface.

[0092] In one aspect shown in FIG. 2, the protective film 17 is located between the selective reflection film 16 and the partial reflection film 11. In one aspect, the protective film 17 acts as a protective layer for the selective reflection film 16. In one aspect, the protective film 17 is made of a material with low birefringence. In one aspect, the protective film 17 is made of a material with birefringence smaller than that of PET (polyethylene terephthalate). In one aspect, the protective film 17 is a TAC (triacetyl cellulose) film. In one aspect, the thickness of the protective film 17 is 20 to 100 μm. In one aspect, the thickness of the protective film 17 is any one of 30, 40, 50, 60, 70, and 80 μm.

[0093] In one aspect shown in FIG. 2, the filter 50 is formed by attaching the laminate 55 to the front surface of the second support 20. In one aspect, a transparent adhesive layer is used for the attachment. In the figure, a quarter-wave plate 25 is provided on the front surface of the second support 20. Therefore, the filter 50 is formed by attaching the laminate 55 on the quarter-wave plate 25. The quarter-wave plate 25 will be described later.

[0094] An air gap layer 19 is formed by sandwiching a gas between the front surface of the filter 50 and the back surface of the half mirror 40 and overlapping them. In one aspect, the half mirror 40 and the filter 50 are fixed to each other with a fixture (not shown) so that they do not separate. In one aspect, the fixture is attached to the peripheries of the half mirror 40 and the filter 50.

[0095] In one aspect shown in FIG. 2, an antireflection film 21 is further provided on the protective film 17. The antireflection film 21 is located on the front side of the protective film 17. The antireflection film 21 is exposed in the space that constitutes the air gap layer 19. The antireflection film 21 promotes the transmission of the polarized light Fp and the polarized light Rp through the interface between the laminate 55 and the air gap layer 19. In a preferred aspect, the transmittance of the polarized light is improved by 1.5 to 2.0 points. Also, the antireflection film 21 suppresses the reflection of the polarized light Fp and the polarized light Rp at the interface between the laminate 55 and the air gap layer 19. In other aspects, no antireflection film is provided on the front side of the protective film 17. When no antireflection film is provided, the reflectance of the external light Ex on the front side of the optical structure 10 is improved compared to the case where an antireflection film is provided. In a preferred aspect, the reflectance is improved by 0.5 point.

[0096] <Introduction of a quarter-wave plate>

[0097] As shown in FIG. 2, a quarter-wave plate 25 is provided on the second support 20. The quarter-wave plate 25 is located on the front side of the second support 20. In one aspect, the quarter-wave plate 25 is attached to the second support 20 with a transparent adhesive layer.

[0098] As shown in FIG. 2, the quarter-wave plate 25 is located on the back side of the laminate 55. In one aspect, the laminate 55 is attached to the quarter-wave plate 25 with a transparent adhesive layer. The quarter-wave plate 25 is located between the selective reflection film 16 and the second support 20. The selective reflection film 16 is located between the air gap layer 19 and the quarter-wave plate 25.

[0099] As shown in FIG. 2, the image light Im composed of linearly polarized light is irradiated from the further back side of the quarter-wave plate 25 provided on the back side of the selective reflection film 16. In one aspect, the fast axis or the slow axis of the quarter-wave plate 25 is inclined by 45° with respect to the polarization axis of the image light Im composed of linearly polarized light. The direction of the inclination is the direction that converts the image light Im composed of linearly polarized light into the image light Im composed of the polarized light Fp.

[0100] The display panel 30 shown in FIG. 2 is any one of a liquid crystal display, an organic EL (Electro Luminescence) display, and other displays. In one aspect, the display panel 30 is a flat display panel. The liquid crystal display has any one of a TN (Twisted Nematic) mode, an IPS (In Plane Switching) mode, a VA (Vertical Alignment) mode, and other display modes.

[0101] In one aspect shown in FIG. 2, the display panel 30 is a TN type liquid crystal display. In that aspect, the polarization axis of its linearly polarized light is inclined 45 degrees with respect to the vertical direction of the screen. Therefore, the fast axis of the quarter-wave plate 25 is either not inclined with respect to the vertical direction of the screen, that is, the inclination is 0 degrees, or inclined 90 degrees.

[0102] In another aspect shown in FIG. 2, the display panel 30 is an IPS type or VA type liquid crystal display. In that aspect, the polarization axis of its linearly polarized light is either not inclined with respect to the vertical direction of the screen, that is, the inclination is 0 degrees, or inclined 90 degrees. Therefore, the fast axis of the quarter-wave plate 25 is inclined 45 degrees with respect to the vertical direction of the screen.

[0103] In an aspect different from the aspect shown in FIG. 2, the display surface 31 emits image light Im composed of elliptical polarization. The fast axis or slow axis of the quarter-wave plate 25 is inclined at a predetermined angle with respect to the polarization axis of the image light Im composed of elliptical polarization. The direction of the inclination is the direction of converting the image light Im composed of elliptical polarization into the image light Im composed of polarization Fp. The magnitude of the inclination is the angle of converting the image light Im composed of elliptical polarization into the image light Im composed of polarization Fp.

[0104] <Void layer on the display panel side>

[0105] In one aspect shown in FIG. 2, an air gap layer 29 is provided between the display surface 31 and the back surface of the second support 20. In one aspect, the air gap layer 29 consists of a space filled with air. In one aspect, water vapor is removed from the air. In other aspects, the air gap layer 29 consists of a space filled with a gas other than air. In one aspect, the air gap layer 29 is a vacuum. In another aspect, the filter 50 and the display panel 30 are joined via a transparent adhesive layer.

[0106] In one aspect shown in FIG. 2, the bezel 32 of the display panel 30 is located at the periphery of the display surface 31. The bezel 32 is higher towards the front side than the display surface 31. By placing the filter 50 on the bezel, an air gap layer 29 having a thickness equal to the height of the bezel is obtained. In one aspect, the thickness of the air gap layer 29 is from 0.01 mm to 10 mm. In one aspect, the thickness of the air gap layer 29 is from 0.1 to 6 mm. In one aspect, the thickness of the air gap layer 29 is made 10 mm or less in order to make the transmissive display mirror 60 thinner.

[0107] <Anti-reflection on the back surface of the filter>

[0108] In one aspect shown in FIG. 2, an anti-reflection film 23 is provided on the second support 20. The anti-reflection film 23 is located on the back surface of the second support 20. The anti-reflection film 23 is exposed in the space constituting the air gap layer 29. The anti-reflection film 23 promotes the transmission of the image light Im through the interface between the filter 50 and the air gap layer 29 and suppresses reflection at that interface. The anti-reflection film 23 increases the luminance of the image light Im observed on the front side of the transmissive display mirror 60.

[0109] In one aspect shown in FIG. 2, a base film formed with an antireflection film 23 is attached to the back surface of the second support 20. The back surface of the antireflection film 23 is in contact with the air gap layer 29. The antireflection film 23 is provided on the back surface of the base film. The back surface of the second support 20 is located on the front surface of the base film. In one aspect, the antireflection layer 23 is a thin film formed on the back surface of the filter 50. In one aspect, the antireflection layer 23 is a thin film formed on the back surface of the support 20, that is, on the interface with the air layer 29.

[0110] <Light shielding of the outer edge of the back surface of the half mirror 40>

[0111] In one aspect shown in FIG. 2, a light shielding plate 18 is disposed between the filter 50 and the display panel 30. In one aspect, the light shielding plate 18 surrounds the outer edge of the air gap layer 29. In one aspect, the display panel 30 covers the center of the optical structure 10. In one aspect, the display panel 30 covers the center of the half mirror 40.

[0112] In one aspect shown in FIG. 2, the display panel 30 covers the center of the filter 50. In one aspect, the light shielding plate 18 covers the outer edge of the optical structure 10. In one aspect, the light shielding plate 18 covers the outer edge of the half mirror 40. In one aspect, the light shielding plate 18 covers the outer edge of the filter 50.

[0113] In one aspect shown in FIG. 2, the light shielding plate 18, together with the display panel 30, covers the entire back surface of the optical structure 10. In one aspect, the light shielding plate 18, together with the display panel 30, covers the entire back surface of the half mirror 40. In one aspect, the light shielding plate 18, together with the display panel 30, covers the entire back surface of the filter 50.

[0114] In one aspect shown in FIG. 2, the light-shielding plate 18 makes the color tone of the mirror image at the outer edge of the half mirror 40 approach the color tone of the mirror image at the center of the half mirror 40 covered by the display panel 30. The mirror image referred to here is the mirror image when observed from the front of the half mirror. In one aspect, as the light-shielding plate 18, a plate whose front or back is painted black is used. In other aspects, as the light-shielding plate 18, a plate with a black film attached to its front or back is used. In other aspects, the thin plate is metal, glass, or resin. In other aspects, the light-shielding plate 18 is entirely made of black resin. In one aspect, instead of using the light-shielding plate 18, the periphery of the back surface of the filter 50 is painted to block light. In one aspect, the back surface of the support 20, that is, the interface with the air layer 29, is painted to block light. In one aspect, the painting is performed in black.

[0115] <Anti-reflection on the front side of the first support>

[0116] In one aspect shown in FIG. 2, an anti-reflection film 12 may be further provided on the first support 15. The anti-reflection film 12 is located on the front of the first support 15. The anti-reflection film 12 is exposed in the space in front of the first support 15. The anti-reflection film 12 promotes the transmission of the external light Ex through the front interface of the first support 15 and suppresses the reflection at that interface. The anti-reflection film 12 suppresses the generation of double mirror images at the interface 14 and the front interface of the first support 15.

[0117] <Use of transmissive display mirror>

[0118] The transmissive display mirror 60 shown in FIG. 2 is used as follows. First, the display panel 30 irradiates the back side of the second support 20 with the image light Im. Next, the quarter-wave plate 25 converts the image light Im into image light composed of polarized light Fp. The partial reflection film 11 transmits the image light Im irradiated from its back side. The image light Im composed of polarized light Fp exits from the front of the first support 15. Therefore, the half mirror 40 exhibits display characteristics.

[0119] In FIG. 2, the partial reflection film 11 reflects the external light Ex irradiated from the front. Therefore, the half mirror 40 exhibits mirror characteristics. In one aspect, the ones that reflect the external light Ex are the interface 14, the inside of the partial reflection film 11, and the interface between the partial reflection film 11 and the air gap layer 19. In another aspect, the selective reflection film 16 further reflects the external light Ex.

[0120] In one aspect shown in FIG. 2, the reflectance of the transmissive display mirror 60 with respect to light having a wavelength of 550 nm is 30% or more and less than 100%. Such reflectance is for the light incident on the front surface of the transmissive display mirror 60. Such reflectance takes into account each element located on the back surface of the half mirror 40. In one aspect, the reflectance is any one of 35, 40, 45, 50, 52, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 75, 80, 85, 90, and 95%.

[0121] In FIG. 2, when the observer observes from the front of the first support 15, the image light Im is brighter than the external light Ex. The transmissive display mirror 60 superimposes and presents an image brighter than the mirror image on the front of the first support 15 with respect to the mirror image. The transmissive display mirror 60 makes the image float on the mirror like the "magic mirror" of "Snow White". The transmissive display mirror 60 further darkens the image light Im irradiated to the back side of the second support 20, thereby restoring the mirror image buried in the image presented on the front of the first support 15.

[0122] <Modified Example of Filter>

[0123] In one aspect of the filter 50 shown in FIG. 2, the quarter-wave plate 25 is located between the selective reflection film 16 and the second support 20. FIG. 3 shows a cross-section of the filter 51, which is a modified example of the filter 50 shown in FIG. 2. In the filter 51, the quarter-wave plate 25 is located on the back surface of the second support 20. In one aspect, the quarter-wave plate 25 is attached to the second support 20. In one aspect, the attachment is performed with a transparent adhesive layer.

[0124] In one aspect shown in FIG. 3, the laminate 55 is located in front of the second support 20. In one aspect, the laminate 55 is attached to the second support 20 with a transparent adhesive layer. The second support 20 is located between the selective reflection film 16 and the quarter-wave plate 25. That is, with the second support 20 interposed therebetween, the quarter-wave plate 25 is located on the opposite side of the selective reflection film 16. Also, the quarter-wave plate 25 is located between the second support 20 and the air gap layer 29.

[0125] In one aspect shown in FIG. 3, the antireflection film 23 is located on the back surface of the quarter-wave plate 25. The antireflection film 23 is exposed in the space that constitutes the air gap layer 29. The antireflection film 23 promotes the transmission of the image light Im through the interface between the filter 50 and the air gap layer 29, and also suppresses the reflection at that interface.

[0126] In one aspect shown in FIG. 3, a base film on which the antireflection film 23 is formed is attached to the back surface of the quarter-wave plate 25. The antireflection film 23 is located on the back surface of the base film. The back surface of the quarter-wave plate 25 is located on the front surface of the base film.

[0127] In an aspect different from the aspect shown in FIG. 3, the quarter-wave plate 25 is disposed at a distant position on the back side of the second support 20. In another aspect, the quarter-wave plate 25 is provided on the display surface 31. In one such aspect, the quarter-wave plate 25 is attached to the display surface 31.

[0128] <Modification Example of Transmissive Display Mirror>

[0129] In one aspect of the transmissive display mirror 60 shown in FIG. 2, the filter 50 includes the second support 20. Also, the second support 20 supports the quarter-wave plate 25. FIG. 4 shows a cross section of a transmissive display mirror 61, which is a modification example of the transmissive display mirror 60 shown in FIG. 2. The transmissive display mirror 61 includes a filter 52, which is a modification example of the filter 50 shown in FIG. 2. The transmissive display mirror 61 includes an optical structure 35, which is a modification example of the optical structure 10 shown in FIG. 2.

[0130] In one aspect shown in FIG. 4, within the filter 52, the protective film 17, the selective reflection film 16, and the quarter-wave plate 25 are arranged in this order from the front to the back. In one aspect, the back surface of the filter 52 is attached to the display surface 31. In one aspect, the quarter-wave plate 25 is attached to the display surface 31, and then the laminate 55 is attached to form the filter 52. In one aspect, a transparent adhesive layer is used for these attachments.

[0131] In one aspect shown in FIG. 4, the filter 52 does not have a second support. From another perspective, the display panel 30 supports the filter 52 instead of the second support. From another perspective, the second support is integrated with the display panel 30, and further, the display surface 31 is the front surface of the second support.

[0132] In one aspect shown in FIG. 4, the display surface 31 emits the image light Im. The display panel 30 irradiates the image light Im onto the back surface of the quarter-wave plate 25. The fast axis and the slow axis of the quarter-wave plate 25 are inclined at 45° with respect to the polarization axis of the image light Im composed of linearly polarized light in the direction of converting the image light Im composed of linearly polarized light into the polarized light Fp.

[0133] In an aspect different from the aspect shown in FIG. 4, the quarter-wave plate 25 is built into the display panel 30. Such a quarter-wave plate generates the image light Im composed of the polarized light Fp from the image light composed of linearly polarized light. In such an aspect, the display surface 31 emits the image light Im composed of the polarized light Fp instead of linearly polarized light. In that one aspect, no quarter-wave plate is provided between the display surface 31 and the selective reflection film 16.

[0134] <Example 1: Transmissive Display Mirror with a Second Support>

[0135] While referring back to FIG. 2, a manufacturing example of the transmissive display mirror 60 is shown below. Refer to Table 1 below. The first support 15 was a glass plate with a thickness of 3 mm. Its reflectivity when observed from the front of the half mirror 40 was 64%. At this time, no other devices such as the filter 50 and the display panel 30 were installed.

[0136] In the filter 50 shown in FIG. 2, the protective film 17 was a TAC film with a thickness of 80 μm. The second support 20 was a glass plate with a thickness of 3 mm. The selective reflection film 16 was formed by laminating, on the back surface of the protective film 17, a film in which liquid crystal molecules have a helical structure arrangement, hereinafter referred to as a liquid crystal film. The liquid crystal film was initially formed on a base film made of PET with a thickness of 100 μm. This liquid crystal film was bonded to a quarter-wave plate with a transparent adhesive layer. The transparent adhesive layer may be formed on a release film. The thickness of the transparent adhesive layer may be 25 μm. The same shall apply hereinafter. A laminate composed of the liquid crystal film and the quarter-wave plate was bonded to the glass plate with another transparent adhesive layer. Further, the TAC film was bonded to the laminate composed of the liquid crystal film, the quarter-wave plate, and the support with another transparent adhesive layer. In this way, a filter 50 including the protective film 17, the selective reflection film 16, the quarter-wave plate 25, and the second support 20 was obtained from the front side.

[0137] In the filter 50 shown in FIG. 2, an antireflection film 23 made of an inorganic thin film was further formed on the back side of the second support 20. The antireflection film 23 became the outermost layer of the filter 50 on the back side. In this example, the antireflection film 21 shown in FIG. 2 was not used. The front surface of the protective film 17 and the back surface of the partial reflection film 11 directly faced each other with the air gap layer 19 interposed therebetween.

[0138] In another aspect for providing the selective reflection film 16 made of a liquid crystal film in the filter 50, first, a transparent adhesive layer is laminated on the TAC film. Next, the liquid crystal film together with the base film is bonded onto the transparent adhesive layer. The base film is peeled off to expose the liquid crystal film on the TAC film. A transparent adhesive layer is laminated on the liquid crystal film. A quarter-wave plate is bonded onto another transparent adhesive layer. Another transparent adhesive layer is further laminated on the quarter-wave plate. A laminate composed of the TAC film, the liquid crystal film, and the quarter-wave plate is bonded to the front surface of the support 20 with such a transparent adhesive layer.

[0139] An optical structure 10 was obtained by overlaying a filter 50 on the back side of the half mirror 40 shown in Fig. 2. A transmissive display mirror 60 was obtained by overlaying a display panel 30 on the back side of the optical structure 10. The air gap layer 29 was made an air layer. Image light Im consisting of linearly polarized light was irradiated onto the back of the optical structure 10 from the display surface 31 of the display panel 30. An image consisting of white characters on a black background was displayed by the image light Im. The visibility of the characters from the front side of the transmissive display mirror 60 was good.

[0140] Next, the image light Im shown in Fig. 2 was darkened so that the display surface 31 displayed only the black background. The reflectance when observed from the front of the transmissive display mirror 60 was 70%. It was suggested that in the transmissive display mirror 60, the filter 50 does not impair the mirror characteristics of the half mirror 40, but rather improves them.

[0141] <Example 2: Addition of an antireflection layer and a light-shielding plate>

[0142] In Fig. 2, an antireflection layer 21 was provided on the protective film 17. A light-shielding plate 18 was provided on the transmissive display mirror 60. Otherwise, it was the same as in Example 1. Refer to Table 1 below. The brightness of the displayed image increased slightly, and good mirror characteristics were obtained over the entire surface of the half mirror 40. When the light-shielding plate 18 was not provided, the mirror characteristics deteriorated at the outer edge of the half mirror 40.

[0143] <Example 3: Transmissive display mirror without an antireflection film>

[0144] As the half mirror 40 shown in Fig. 2, a half mirror with a lower reflectance than in Example 1 and Example 2 was used to fabricate the transmissive display mirror 60 of this example. The first support 15 was a glass plate with a thickness of 4 mm. The second support 20 was a glass plate with a thickness of 1.3 mm. For other configurations, refer to Table 1 below. The reflectance of the half mirror alone when observed from the front was 50%. Antireflection films 21 and 23 were not provided on the front and back of the filter 50. The display panel 30 was overlaid on the back side of the filter 50.

[0145] As shown in Fig. 2, the image light Im was irradiated on the back surface of the transmissive display mirror 60. An image consisting of white characters on a black background was displayed on the front surface of the transmissive display mirror 60. The visibility of the characters from the front side of the transmissive display mirror 60 was good. The characters were brighter than those observed in Example 1.

[0146] Only the black background was displayed on the display surface 31 shown in Fig. 2. When observing the transmissive display mirror 60 from the front, the reflectance was 62%. In the transmissive display mirror 60 of this example, it was suggested that the filter 50 did not impair the mirror characteristics of the half mirror 40, but rather improved them.

[0147] <Example 4: Transmissive display mirror without a second support>

[0148] As shown in Fig. 5, the light reflection and transmission member 41 was fabricated. Refer to Table 1 below. The partial reflection film 11 was laminated on the back surface of the first support 15 made of a glass plate with a thickness of 5 mm. In the same manner as in Example 1, the liquid crystal film was bonded to the quarter-wave plate by the transparent adhesive layer. Further, the laminate composed of the liquid crystal film and the quarter-wave plate was bonded to the back surface of the partial reflection film 11 by the transparent adhesive layer. Thus, the light reflection and transmission member 41 including the first support 15, the partial reflection film 11, the selective reflection film 16, and the quarter-wave plate 25 in this order from the front side was obtained. The light reflection and transmission member 41 does not include a second support.

[0149] As shown in Fig. 5, a transmissive display mirror was obtained by superimposing the display panel 30 via the air layer void layer 29 on the back surface of the light reflection and transmission member 41. By irradiating the back surface of the light reflection and transmission member 41 with the image light Im, the same image as the above-mentioned image was displayed on the transmissive display mirror. The visibility of the characters in the image was good.

[0150] Next, the image light Im was darkened so that only the black background was displayed on the display surface 31. The reflectance when observing the transmissive display mirror from the front was 63%. In the transmissive display mirror of this example, it was suggested that the selective reflection film 16 alone, which was not laminated on the second support, did not contribute to the improvement of the mirror characteristics of the light reflection and transmission member 41.

[0151] <Example 5: Transmissive display mirror without a selective reflection film>

[0152] As shown in FIG. 6, a transmissive display mirror was fabricated using only the half mirror 40 used in Example 1 above. Refer to Table 1 below. The partial reflection film 11 of the half mirror 40 was opposed to the display surface 31. By irradiating the back surface of the half mirror 40 with the image light Im, the same image as the above image was displayed on the transmissive display mirror. The luminance of the characters in the image was lower compared to Example 1, Example 2, and Example 4. Also, the visibility of the characters was lower compared to Example 1, Example 2, and Example 4.

[0153] Next, the image light Im shown in FIG. 6 was darkened so that the display surface 31 only displayed a black background. The reflectance of the transmissive display mirror when observed from the front was 64%. Therefore, it was suggested that the high reflectance obtained in the transmissive display mirror of Example 1 was due to the lamination of the selective reflection film on the second support.

[0154] <Example 6: Half mirror with an antireflection film>

[0155] The half mirror 40 of Example 5 shown in FIG. 6 was processed. Refer to Table 1 below. An antireflection film 13 was further provided on the back surface of the partial display film 11. An antireflection film formed on a base film was used. The surface on the opposite side of the antireflection film across the base film was attached to the back surface of the partial display film 11. The attachment was performed via a transparent adhesive layer. In this example, no display panel was provided on the back side of the half mirror 40. The reflectance when observing this from the front of the half mirror 40 was 53%. This reflectance is the reflectance of the half mirror alone and also the overall reflectance.

[0156] <Comparison of color tones>

[0157] Refer to Table 1 below. The color tone of the mirror image of the half mirror in Example 6 was different from the color tone of the mirror image of the half mirror 40 in Example 5, which served as the reference. Therefore, it was suggested that the color tone of the mirror image of the half mirror 40 would change by attaching another film to the back surface of the half mirror 40 via a transparent adhesive. The color tone of the mirror image obtained with the transmissive display mirror in Example 4 was different from the color tone of the mirror image of the transmissive display mirror using only the half mirror 40 in Example 5. In contrast, the color tone of the mirror image obtained with the transmissive display mirror in Example 1 was almost the same as the color tone of the mirror image in Example 5. The color tone of the mirror image in Example 3 was almost the same as the color tone of the mirror image of the half mirror alone. Therefore, the optical structures used in the transmissive display mirrors of Example 1 and Example 3 are suitable for increasing the transmittance of the half mirror without changing the color tone of the mirror image of the half mirror.

[0158] The configurations and evaluations of the transmissive display mirrors and half mirrors from Example 1 to Example 6 are summarized in Table 1 below. In the table, for the item of image visibility, the more "+", the better the visibility. Also, for the item of image brightness, the more "+", the brighter the image. The transmittance in Examples 1 to 3 was measured by irradiating linearly polarized light to the optical structure. The transmittance in Example 4 was measured by irradiating linearly polarized light to the light reflection and transmission member. The transmittance in Examples 5 to 6 was measured by irradiating linearly polarized light to the half mirror. Among the optical structure and the light reflection and transmission member, linearly polarized light is converted into circularly polarized light by a quarter-wave plate and then transmitted through the selective reflection film. Among the half mirrors, linearly polarized light is transmitted without being converted. Each measurement result is the measured value obtained in one trial, and sample individual differences and measurement variations are not considered.

[0159]

Table 1

[0160] <Use of the transmissive display mirror>

[0161] In one aspect, the transmissive display mirror is a mirror that reflects the figures of humans and objects. In such a mirror, an observer observes, with their eyes, the mirror image reflected on the front surface of the transmissive display mirror. In such a mirror, an observer observes, with their eyes, an image superimposed on the mirror image. In one aspect, the mirror is any one of a dressing table mirror, a full-length mirror, a wall-mounted mirror, and a tabletop standing mirror. In one aspect, the dressing table mirror is used by customers to view their figures when trying on clothes or testing cosmetics. In another aspect, the mirror is used on any one of a wall, a window, a partition, a pillar, and a ceiling. The mirror is used on the surface of these building materials.

[0162] In one aspect, these mirrors display an image that is superimposed on the mirror image and brighter than the mirror image. The images are advertisements related to sales and others, as well as wayfinding around the mirror. In one aspect, the displayed image has a design quality. In another aspect, the image is symbolic. In one aspect, these mirrors restore the mirror image that was buried in the image by darkening the image.

[0163] In one aspect, the transmissive display mirror further includes a sensor. In one aspect, the sensor reads a tag attached to an object. In one aspect, the tag is a QR code (registered trademark) and other matrix codes and barcodes. In another aspect, the tag is an RFID and other hard tags. In one aspect, the transmissive display mirror displays an image of the information of the object superimposed on the mirror image.

[0164] <Mirror Display>

[0165] In one aspect, the transmissive display mirror is a display device. In such a display device, an observer observes, with their eyes, the image and the mirror image reflected on the front surface of the transmissive display mirror. In one aspect, the display device is a mirror display or a mirror TV.

[0166] <Method of Reflecting an Image on a Mirror Image>

[0167] In one aspect of the use of the optical structure 10 shown in FIG. 1, a display device is provided that also treats the mirror image reflected on the front as an image. In one aspect, such a display device is obtained by replacing the half mirror in the display device described in Patent Document 2 with the optical structure of the above embodiment.

[0168] In one aspect shown in FIG. 1, the display panel 30 irradiates the first image light composed of polarized light Fp from the back side of the second support 20. The optical structure 10 emits the first image light from the front of the first support 15. As a result, the optical structure 10 presents the first image on the front of the first support 15. At this time, the traveling direction of the first image light is tilted with respect to the optical structure 10.

[0169] Furthermore, in one aspect shown in FIG. 1, a second display panel (not shown) irradiates the front of the first support 15 with the second image light as external light Ex. The optical structure 10 reflects the second image light composed of external light Ex at the half mirror 40. The optical structure 10 presents the second image as a mirror image on the front of the first support 15. At this time, the traveling direction of the second image light composed of external light Ex is tilted with respect to the optical structure 10. The traveling direction of the second image light after reflection follows the traveling direction of the first image light. In one aspect, the traveling direction of the second image light after reflection is parallel to the traveling direction of the first image light. The bright part of the second image is presented in the dark part of the first image. Also, the bright part of the first image is presented in the dark part of the second image. Since the optical path of the second image is longer than the optical path of the first image light, a pseudo-stereoscopic display can be obtained in which the first image appears to float in the second image.

[0170] The present invention is not limited to the above, and can be appropriately changed without departing from the gist.

Explanation of Reference Numerals

[0171] 10 Optical structure, 11 Partial reflection film, 12 Anti-reflection film, 13 Anti-reflection film, 14 Interface, 15 First support, 16 Selective reflection film, 17 Protective film, 19 Air gap layer, 20 Second support, 21 Anti-reflection film, 23 Anti-reflection film, 25 Quarter-wave plate, 29 Air gap layer, 30 Display panel, 31 Display surface, 32 Bezel, 35 Optical structure, 40 Half mirror, 41 Light reflection and transmission member, 50 Filter, 51 Filter, 52 Filter, 55 Laminate, 60 Transmissive display mirror, 61 Transmissive display mirror, Ex External light, Fp Polarization, Im Image light, Ob Observer, Rp Polarization

Claims

1. A mirror that superimposes and displays an image with respect to its mirror image, hereinafter referred to as a transmissive display mirror, comprising: an optical structure and a display panel that irradiates image light composed of linearly polarized light onto the back surface of the optical structure; the optical structure is formed by combining a half mirror and a selective reflection film; the half mirror includes a first support and a partial reflection film laminated on the back surface of the first support; the partial reflection film reflects external light incident from the front side of the first support, thereby presenting a mirror image on the front side of the first support; the selective reflection film is further provided on the back side of the half mirror so as to face the partial reflection film; the selective reflection film transmits one of left circularly polarized light and right circularly polarized light, hereinafter referred to as F polarized light, better than the other, hereinafter referred to as R polarized light, throughout the visible light band, and reflects R polarized light better than F polarized light; the reflectivity of the selective reflection film with respect to R polarized light is higher than the reflectivity of the partial reflection film with respect to F polarized light throughout the visible light band; a first air gap layer is provided between the selective reflection film and the partial reflection film; further comprising a second support facing the first support; the selective reflection film is laminated on the front surface of the second support; a protective film is further formed on the front surface of the selective reflection film; a quarter-wave plate is further laminated between the selective reflection film and the second support; the first air gap layer consists of a space filled with air or a gas other than air; the partial reflection film is exposed to the space; the thickness of the second support is 0.5 to 3 mm; A transmissive display mirror.

2. a second air gap layer is provided between the second support and the display panel; the second air gap layer consists of a space filled with air or a gas other than air; The transmissive display mirror according to Claim 1.

3. the partial reflection film and the selective reflection film are substantially parallel over the entire area where they face each other; The transmissive display mirror according to Claim 1 or 2.

4. the thickness of the first air gap layer is greater than 0 mm and less than half of the thickness of the first support; The transmissive display mirror according to any one of Claims 1 to 3.

5. the selective reflection film is made of a liquid crystal selected from nematic liquid crystal and smectic liquid crystal; the liquid crystal consists of a chiral phase; The phase consists of a liquid crystal molecule to which a chiral dopant is added, or consists of a liquid crystal molecule having chirality. The transmissive display mirror according to any one of claims 1 to 4.

6. The selective reflection film consists of a cholesteric liquid crystal. The transmissive display mirror according to any one of claims 1 to 4.

7. The partial reflection film consists of either a dielectric multilayer film or a single-layer film of a metal oxide. The transmissive display mirror according to any one of claims 1 to 6.

8. An antireflection film is further formed on the front surface of the selective reflection film. The transmissive display mirror according to any one of claims 1 to 7.

9. An antireflection film is further formed on the back surface of the second support. The transmissive display mirror according to any one of claims 1 to 8.

10. In the half mirror, its reflectance is greater than its transmittance. The transmissive display mirror according to any one of claims 1 to 9.

11. Use of the transmissive display mirror according to claim 10, By irradiating image light composed of linearly polarized light or elliptically polarized light to the back side of the second support, this is converted into image light composed of F-polarized light by the quarter-wave plate, By emitting the image light composed of F-polarized light from the front surface of the first support, an image brighter than the mirror image is superimposed on the mirror image in front of the first support, By darkening the image light irradiated to the back side of the second support, the mirror image buried in the image in front of the first support is restored. Use.

12. The display panel faces the back surface of the second support and has a display surface that emits the image light composed of linearly polarized light. The fast axis and slow axis of the quarter-wave plate are inclined by 45° with respect to the polarization axis of the linearly polarized light in the direction of converting the linearly polarized light into polarized light Fp. The transmissive display mirror according to any one of claims 1 to 10.

13. Further provided with a light-shielding plate, The display panel covers the center of the back surface of the half mirror, and the light-shielding plate covers the outer edge of the back surface of the half mirror, so that the entire back surface of the half mirror is covered. The transmissive display mirror according to claim 12.

14. Use of the transmissive display mirror according to any one of claims 1 to 10, 12. Irradiate the image light composed of F-polarized light from the back side of the second support, and emit the image light composed of F-polarized light from the front of the first support, so as to superimpose and present an image brighter than the mirror image on the front of the first support with respect to the mirror image. By darkening the image light, the mirror image buried in the image on the front of the first support is restored. Use.

15. Use of the transmissive display mirror according to any one of Claims 1 to 10 and 12, Irradiate the first image light composed of F-polarized light from the back side of the second support at an angle with respect to the optical structure, and emit the first image light composed of F-polarized light from the front of the first support, so as to present a first image on the front of the first support. Furthermore, irradiate the second image light as the external light from the front side of the first support at an angle with respect to the optical structure, so as to present a second image as the mirror image on the front of the second support. On the front of the first support, present the bright part of the second image in the dark part of the first image, and present the bright part of the first image in the dark part of the second image. Use.

16. By irradiating the image light composed of linearly polarized light or elliptically polarized light from the further back side of the quarter-wave plate provided on the back side of the selective reflection film, convert it into the image light composed of F-polarized light. Use according to Claim 14 or 15.

Images