JP6658758B2 - Structure, transparent display, lighting device, liquid crystal display device and information display device - Google Patents

Description

The present invention relates to a structure in which an optical element having an electro-optical function layer whose optical characteristics change according to application and non-application of a voltage and a transparent plate having a high transmittance are bonded via an optical bonding layer.
Further, the present invention relates to a transparent display having the structure, a lighting device having the structure, a liquid crystal display having the lighting device, and an information display having the structure.

2. Related Art A liquid crystal optical element (hereinafter, abbreviated as an optical element) in which an electro-optical function layer containing a liquid crystal compound and a cured resin is sandwiched between a pair of substrates with electrodes is known (see Patent Document 1).
The electro-optical element described in Patent Document 1 shows a transparent state when no voltage is applied to the electro-optical function layer, and when a voltage is applied, the major axis of the molecule of the liquid crystal compound follows the dielectric anisotropy thereof. Attempts to orient in the direction of the electric field (ie, the dielectric anisotropy is positive) and in the normal direction (ie, the dielectric anisotropy is negative). At this time, since the orientation of the liquid crystal compound is regulated by the cured product of the adjacent resin, uniaxial orientation is prevented, and a state in which light incident on the electro-optical function layer is scattered is obtained. Such an optical element is distinguished from a conventional polymer-dispersed liquid crystal in that when transmitting light incident on the electro-optical function layer, the transmittance in the oblique incidence direction is high. Therefore, it has been proposed that such an optical element is used alone as a light control glass or a display device because of its optical characteristics.

The optical element described in Patent Literature 1 functions as an optical element by transmitting and scattering environmental light incident on the element (for example, in a display device, a character is formed by contrast between transmission and scattering of environmental light incident on the element. Function to display such information.) Therefore, for example, when the intensity of ambient light incident on an element such as nighttime or a dark environment is weak, the visibility at the time of scattering is reduced, and the contrast ratio between transmission and scattering is reduced, so that it cannot function sufficiently as an optical element. .
On the other hand, Patent Document 2 proposes an image display device including an optical element and a light source that illuminates the optical element at an angle outside the non-observation surface of the optical element that cannot be directly viewed from the observation surface of the optical element. I have. With such a configuration, even if the ambient light is weak, the observer can visually recognize the display.

  Further, as a transparent display device containing no liquid crystal compound, a transparent organic LED display device is known. Since the organic LED display device is a self-luminous display, it is possible to provide a display with good visibility and high contrast of the light emitting unit.

JP 2000-119656 A JP-A-2004-157492

  However, in the image display device of Patent Document 2, since there is a physical distance between the optical element and the illumination via the air layer, the illumination light leaks to a portion other than the optical element, and the contrast cannot be increased. In the problem of leakage or in the transparent part of the optical element, the illumination light passes through the optical element and illuminates a place other than the optical element. There was a problem of low. When the light use efficiency is low, in order to obtain a bright display with good visibility, it is necessary to increase the number of light sources or to use high-intensity illumination, and to physically control the light through an air layer between the optical element and the illumination. The image display device is bulky, including securing the distance, and there are limitations on the applications to which the image display device can be applied.

  On the other hand, a transparent organic LED display device requires a transparent electrode having a low resistance value because it is driven by current. A relatively thick conductive film is required for a transparent electrode having a low resistance value, and there is a problem that the transmittance of the transparent portion is reduced. Further, the organic LED is formed from a multilayer thin film, and there is a problem that a transmission portion is colored or transmitted light is blurred due to interference of the multilayer film.

The present invention has been made in view of the above-described problems, and a transparent portion of an optical element shows high transparency without coloring or bleeding in transmitted light, and a scattering portion is good without depending on the intensity of ambient light. It is an object of the present invention to provide a structure having high display contrast by having high visibility.
Another object of the present invention is to provide a transparent display using the above-mentioned structure and light source. Still another object of the present invention is to provide a liquid crystal display device including the above-described transparent display and a transparent image display panel.

The structure according to the present invention includes a pair of transparent substrates having electrodes formed on at least one side thereof, an electro-optical function layer sandwiched between the pair of transparent substrates, and an optical junction formed on at least one of the transparent substrates. And a transparent plate laminated via a layer, wherein the electro-optical function layer can control a state of transmitting incident light and a state of scattering by applying a voltage, and in a state of transmitting incident light, When the normal direction of the transparent substrate is 0 °, the transmittance at the measurement angle of Expression 3 below is 60% or more,
Measurement angle = arcsin (refractive index of medium other than optical bonding layer adjacent to transparent plate / refractive index of transparent plate) Equation 3
The transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.
In the transparent display of the present invention, the transmittance of the transparent portion is 70% or more, and the luminance contrast ratio between the transparent portion and the scattering portion is 4 or more in a state where there is no light incident from the side facing the display surface.
In the lighting device of the present invention, the transmittance of the transparent part is 70% or more, and the luminance contrast ratio between the transparent part and the scattering part is 4 or more in a state where there is no light incident from the side facing the display surface.
A liquid crystal display device according to the present invention includes a liquid crystal panel and the lighting device.
In the information display device of the present invention, the transmittance of the transparent portion is 70% or more, and the luminance contrast ratio of the transparent portion and the scattering portion is 4 or more in a state where there is no light incident from the side facing the display surface.
In the present invention, the above-described lighting device, liquid crystal display device, and information display device are examples of specific devices for use in the above-described transparent display. In this specification, the description of the transparent display can be referred to as the description of the lighting device, the liquid crystal display device, and the information display device. The description of the liquid crystal display device can be referred to as the description of the information display device.

The structure of the present invention can provide a high-contrast display by driving the electro-optical element by having high transparency of the transparent portion and having good visibility of the scattering portion without depending on the intensity of ambient light. . High-brightness illumination is not required because the light use efficiency of the light source can be increased, and there is no need to secure a physical distance between the optical element and the illumination via an air layer. Can be reduced, and the application range is less restricted.
Further, the transparent display of the present invention can switch between a transparent state and a light emitting state by applying and not applying a voltage to an optical element without depending on the intensity of ambient light, and can provide a lighting device and a liquid crystal display device. And information display devices.
In addition, the liquid crystal display device of the present invention has a liquid crystal panel illuminating means that can change the illumination intensity by a transparent state and a scattering portion by applying and not applying a voltage to the optical element. The display contrast can be increased.
Furthermore, the information display device of the present invention has a lighting unit of an electro-optical function layer, which can change a lighting state by a transparent state and a scattering part by applying and not applying a voltage to the optical element, and The display contrast of the device can be increased.

Schematic sectional view of the structure according to the first embodiment of the present invention. Is a diagram showing the operation of the structure according to the embodiment of the present invention; Is a diagram showing the operation of the structure according to the embodiment of the present invention; Schematic sectional view of a structure according to a second embodiment of the present invention. Schematic sectional view of a structure according to a second embodiment of the present invention. A schematic top view of the structure according to the second embodiment of the present invention as viewed from the transparent substrate 5 side. Schematic sectional view of a structure according to a third embodiment of the present invention. Schematic sectional view of a structure according to a fourth embodiment of the present invention. Schematic top view of a transparent electrode of a structure according to a fourth embodiment of the present invention Schematic sectional view of a structure according to a fifth embodiment of the present invention. Schematic sectional view of a structure according to a sixth embodiment of the present invention. Schematic sectional view of a transparent display according to a seventh embodiment of the present invention. A schematic top view of a transparent display according to a seventh embodiment of the present invention as viewed from the transparent substrate 5 side. A schematic top view of a transparent display according to a seventh embodiment of the present invention as viewed from the transparent substrate 5 side. A schematic top view of a transparent display according to a seventh embodiment of the present invention as viewed from the transparent substrate 5 side. Schematic sectional view of a liquid crystal display device according to an eighth embodiment of the present invention. Schematic sectional view of a modification of the liquid crystal display device according to the eighth embodiment of the present invention. Schematic sectional view of a modification of the liquid crystal display device according to the eighth embodiment of the present invention. Schematic sectional view of a structure according to an embodiment of the present invention. Schematic sectional view of a structure according to a comparative example of the present invention

[Structure]
One embodiment of a structure according to the present invention will be described with reference to FIGS.

(First embodiment)
A first embodiment of a structure according to the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view of a structure 100 according to the present embodiment. As shown in FIG. 1, the structure 100 includes a transparent plate 1, an optical bonding layer 2, a pair of transparent substrates 3 and 5, and an electro-optical function layer 4 sandwiched between the pair of transparent substrates. The transparent plate 1 and one of the transparent substrates 3 are laminated and integrated via the optical bonding layer 2. In the present embodiment, a transparent electrode layer (not shown) is provided on the surfaces of the pair of transparent substrates 3 and 5 that are in contact with the electro-optical function layer 4. In this specification, the transparent electrode layer is also referred to as a transparent electrode or simply as an electrode.
An insulating layer or a liquid crystal alignment layer may be provided between the transparent electrode layer and the electro-optical function layer 4. Further, an ultraviolet absorbing layer, an anti-reflection layer, a reflection layer, a semi-reflection layer, a fingerprint adhesion prevention layer, and the like can be provided on a part or all of the surfaces of the transparent substrates 3 and 5 which are not in contact with the electro-optical function layer.

In the following description, a laminate of the electro-optical function layer 4 sandwiched between the pair of transparent substrates 3 and 5 and the pair of transparent substrates may be referred to as an optical element 6.
FIGS. 2A and 2B show that, when the normal direction of the transparent plate 1 is 0 °, the light traveling from the transparent plate to the medium adjacent to the transparent plate inside the transparent plate 1 is expressed by the following formula. The light 7 incident on the transparent plate 1 is structured such that the optical element transmits the incident light (A) and scatters the incident light (B) so that the angle is equal to or larger than the angle indicated by 3 ′ (referred to as a critical angle). FIG. 4 is a diagram showing a state where light is guided in a body 100.
Critical angle = arcsin (refractive index of medium other than optical bonding layer adjacent to transparent plate / refractive index of transparent plate) Equation 3 ′
In the structure 100 of the present embodiment, the optical characteristics of the electro-optical function layer 4 are controlled by driving the optical element 6.
FIG. 2A shows that the light 7 incident on the transparent plate 1 is applied to the optical element 6 such that the light traveling from the transparent plate to the medium adjacent to the transparent plate inside the transparent plate 1 is equal to or larger than the critical angle. FIG. 2B is a view showing a state where light 7 similarly incident on the transparent plate 1 is scattered in the structure 100 in the optical element 6. FIG. In the structure 100 of the present embodiment, the optical characteristics of the electro-optical function layer 4 are controlled by driving the optical element 6.

  In this embodiment, the optical element 6 transmits incident light in a state where no voltage is applied (that is, normal state), and scatters incident light in a state where a voltage is applied (hereinafter, this state is referred to as a normal transmission type). ) And a mode of scattering incident light in a normal state and transmitting the incident light in a state where a voltage is applied (hereinafter, this mode is referred to as a normal scattering type).

In FIG. 2A, reflection and scattering of light hardly occur inside the structure 100. Therefore, the light 7 incident on one end of the transparent plate 1 at an angle (critical angle) at which total reflection occurs at the main surface 1 s of the transparent plate 1 and the main surface 5 s of the transparent substrate 5 is guided through the structure 100. However, light does not leak from the main surface 5s of the transparent substrate 5 and the main surface 1s of the transparent plate 1.
In this case, for example, even if light is incident on one end of the transparent plate 1, the structure appears transparent to an observer who views the structure from the main surface 5s side of the transparent substrate 5.

In FIG. 2B, incident light is scattered in the electro-optical function layer 4 of the structure 100. Then, of the scattered light, light having a critical angle or less at the main surface 1s of the transparent plate 1 and the main surface 5s of the transparent substrate 5 is emitted from the main surface 5s of the transparent substrate 5 and the main surface 1s of the transparent plate 1. Is done.
In this case, for example, when the light 7 is incident on one end of the transparent plate 1, the observer who views the structure 100 from the main surface 5 s side of the transparent substrate 5 or the transparent plate 1 side sets the scattering unit to the light emitting unit. Can be confirmed as The light emitted from the scattering part is obtained by extracting incident light guided inside the transparent plate 1 and the optical element 6 by the optical characteristics of the electro-optical function layer (hereinafter, referred to as light-guided light emission).

In the structure 100 of the present embodiment, the design of the scattering portion can be freely designed by the shape of the electrodes provided on the transparent substrates 3 and 5 or the electric signal of a voltage control panel (not shown).
For example, when there is one display electrode, electrodes are formed on the entire surface (solid shape) of the transparent substrates 3 and 5, and a voltage is applied to the entire surface, the transparent substrate 5 is not applied in the state of FIG. An observer who looks at the structure 100 from the main surface 5s side or the transparent plate 1 side looks as if the entire surface emits light.
For example, when dot-shaped electrodes are formed on the transparent substrates 3 and 5, in the state of FIG. 2B, light is scattered only at locations where the electrodes are formed. In this case, an observer who looks at the structure 100 from the main surface 5s side of the transparent substrate 5 or the transparent plate 1 side can recognize information such as characters and figures according to the arrangement of dots and applied electric signals.

  The structure 100 of the present embodiment has a transparent plate 1, and the transparent plate 1 and the optical element 6 are laminated and integrated by an optical bonding layer 2. Therefore, in a situation where there is ambient light, the function of the optical element 6 can be exhibited using the ambient light as before. Furthermore, even in a situation where the ambient light is weak or not, the light is emitted from the edge portion of the transparent plate 1 so that the scattering portion can emit light and the display function of the optical element 6 can be exhibited. .

(Transparent plate 1)
The transparent plate 1 has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm. Since the transparent plate 1 has a high average internal transmittance, light is hardly attenuated in the transparent plate 1. The average internal transmittance is more preferably at least 85%, further preferably at least 90%.
In the present specification, the average internal transmittance refers to a certain optical path length as L (cm), an incident light intensity as I ₀ (%), and a light intensity after transmitting through a certain optical path length L (cm) as I ₁ ( %), Where R (%) is the attenuation rate of light due to reflection.
logT _in = (log (I ₁ / I ₀ ) −log R) Expression 1
The transparent plate 1 preferably has a tristimulus Y value of 90% or more in the XYZ color system according to JIS Z8701 (Appendix) when the optical path length is 5 cm. The Y value is more preferably 91% or more, further preferably 93% or more. The Y value is obtained by the following equation (2).
Y = Σ (S (λ) × y (λ)) Equation 2
Here, S (λ) is the transmittance at each wavelength, and y (λ) is a weighting coefficient for each wavelength. Therefore, Σ (S (λ) × y (λ)) is the sum of the weighted coefficients of each wavelength multiplied by the transmittance. Note that y (λ) corresponds to the M cone (G cone / green) among the retinal cells of the eye, and is most responsive to light having a wavelength of 535 nm.

  The thickness of the transparent plate 1 is preferably 0.5 to 10 mm. When the thickness of the transparent plate 1 is smaller than 0.5 mm, the number of times of light reflection on the surface of the transparent plate 1 increases, the light attenuation due to the reflection increases, and the internal transmittance in the effective optical path length decreases. On the other hand, if the thickness of the transparent plate 1 exceeds 10 mm, the structure 100 becomes thicker and handling becomes difficult. The thickness of the transparent plate 1 is more preferably 0.7 to 5 mm, and further preferably 1.0 to 2.5 mm.

  In the case of providing a transparent display, it is preferable that the main surface 1s of the transparent plate 1 that is in contact with the outside is not provided with a diffusion pattern, dot-like fine irregularities, or the like. With such a configuration, high transparency of the structure 100 is maintained in a state where the electro-optical function layer 4 transmits incident light.

  The ratio (α1 / α2) of the coefficient of thermal expansion α1 of the transparent plate 1 to the coefficient of thermal expansion α2 of one of the transparent substrates 3 in contact with the optical bonding layer 2 is preferably 5 or less, more preferably 2 or less. When the ratio of the coefficient of thermal expansion is in the above range, the structure 100 can be used in high-temperature and low-temperature environments. That is, when the difference in the coefficient of thermal expansion is in the above range, the destruction of the bonding interface due to the difference in size between the transparent plate 1 and the transparent substrate 3 is less likely to occur.

For example, when glass is used as the transparent substrate 3, the thermal expansion coefficient α2 of the glass is 0.5 to 10 ppm / ° C., and therefore the thermal expansion coefficient α1 of the transparent plate 1 is preferably at least 20 ppm / ° C. or less.
Acrylic resin or glass can be used as the material of the transparent plate 1. Glass is preferable from the viewpoint of easy production of a large structure. When the transparent substrate 3 is made of glass, it is preferable to use glass as the transparent plate 1 because the ratio of the coefficient of thermal expansion can be easily set in the above range and the difference in refractive index can be further reduced.

In the glass as the transparent plate 1, the average internal transmittance at a wavelength of 400 to 700 nm at an optical path length of 50 mm as described above has a total iron content A of 100 ppm by mass or less as Fe ₂ O _3. It is preferable to satisfy 80% or more, more preferably 40 mass ppm or less, and further preferably 20 mass ppm or less. On the other hand, the total amount A of the iron content of the glass is preferably 5 mass ppm or more, when producing a multi-component oxide glass, in order to improve the melting property of the glass, and is preferably 8 mass ppm or more. More preferably, it is more preferably at least 10 ppm by mass. In addition, the total amount A of the iron content of the glass can be adjusted by the amount of iron added at the time of glass production.

In this specification, the total amount A of the iron content of the glass is represented as the content of Fe ₂ O ₃ , but all the iron present in the glass exists as Fe ³⁺ (trivalent iron). Not necessarily. Usually, Fe ³⁺ and Fe ²⁺ (divalent iron) are simultaneously present in the glass.
Fe ²⁺ and Fe ³⁺ have absorption in the wavelength range of 400 to 700 nm, and the absorption coefficient of Fe ²⁺ (11 cm ⁻¹ Mol ⁻¹ ) is the absorption coefficient of Fe ³⁺ (0.96 cm ⁻¹ Mol ⁻¹ ). Therefore, the internal transmittance at a wavelength of 400 to 700 nm is further reduced. Therefore, it is preferable that the content of Fe ²⁺ be small in order to increase the internal transmittance at a wavelength of 400 to 700 nm.

The content B of Fe ^{2+ in} the glass is preferably 20% by mass or less, more preferably 10% by mass or less, in order to satisfy the above-mentioned average internal transmittance in the visible light region with an effective optical path length. More preferably, it is 5 ppm by mass or less. On the other hand, the content B of Fe ^{2+ in} the glass is preferably 0.01 mass ppm or more in order to improve the melting property of the glass during the production of a multi-component oxide glass, and is preferably 0.05 mass ppm. ppm or more, more preferably 0.1 ppm by mass or more.
The content of Fe ^{2+ in} the glass can be adjusted by the amount of the oxidizing agent added at the time of manufacturing the glass or the melting temperature. The specific types of oxidizing agents added during the production of glass and the amounts thereof will be described later. The content A of Fe ₂ O ₃ was determined by fluorescent X-ray measurement, a content of total iron as calculated as _Fe 2 _{O 3} (mass ppm). The Fe ²⁺ content B was measured according to ASTM C169-92. The measured content of Fe ²⁺ was expressed in terms of Fe ₂ O ₃ .

Preferred specific examples of the composition of the glass are shown below.
One configuration example (configuration example A) of the glass is, in terms of mass percentage based on oxide, 60 to 80% of SiO ₂ , 0 to 7% of Al ₂ O ₃ , 0 to 10% of MgO, and 0 to 0 of CaO. 20% 0 to 15% of SrO 0 to 15% of BaO, 3 to 20% of Na ₂ O, the _{K 2} O comprises 0-10%, including _Fe 2 _{O 3} 5 to 100 mass ppm.
Another exemplary configuration of the glass (Configuration Example B) is a mass percentage based on oxides, _{SiO 2 45~80%, Al 2 O} 3 7 percent 30 percent or _less, a B 2 _{O 3} 0 15%, the MgO 0 to 15%, Less than six% of CaO, the SrO 0 to 5%, 0 to 5% of BaO, 7 to 20% of Na ₂ O, 0% to _{K 2} O, the ZrO ₂ comprises 0-10%, including _Fe 2 _{O 3} 5 to 100 mass ppm.
Yet another exemplary configuration of the glass (Configuration Example C) is represented by mass percentage based on oxides, from 0 to SiO ₂ 45 to 70%, the _Al 2 _{O 3 10~30%,} a B 2 _{O 3} 5% to 30% in total of MgO, CaO, SrO and BaO, 0% or more and less than 3% in total of Li ₂ O, Na ₂ O and K ₂ O, and 5 to 100% of Fe ₂ O ₃ Contains ppm by mass.

(Optical bonding layer 2)
In the structure 100 of the present embodiment, a transparent plate 1 and a transparent substrate 3 are laminated and integrated via an optical bonding layer 2. In order for light to enter the optical element 6 from the transparent plate 1, it is necessary that the transparent plate 1 and the optical element 6 are optically bonded by a bonding layer having a close refractive index without passing through an air layer. . The difference in refractive index between the optical bonding layer 2 and the transparent plate 1 and between the optical bonding layer 2 and the transparent substrate 3 is preferably 0.1 or less, more preferably 0.05 or less.

  As the optical bonding layer 2, a commercially available optical adhesive sheet, optical adhesive sheet, or the like can be used. Examples of such a sheet include acrylic, silicone, urethane, and a mixture thereof.

The optical bonding layer 2 preferably has a dynamic shear storage modulus (G ′) at 35 ° C. and 1 Hz of 1.0 × 10 ⁵ Pa or less. When G ′ of the optical bonding layer 2 is in the above range, bubbles are unlikely to be generated when the transparent plate 1 and the optical element 6 (the bonding surface is the transparent substrate 3) are bonded, and the optical element Can be prevented from occurring. From the same viewpoint, G ′ is more preferably from 1.0 × 10 ² Pa to 5.0 × 10 ⁴ Pa, further preferably from 1.0 × 10 ³ Pa to 5.0 × 10 ⁴ Pa.

The optical junction layer 2 preferably has a loss tangent (tan δ) at 35 ° C. and 1 Hz of 0.1 to 1.4. When tan δ is in the above-mentioned range, the transparent plate 1 and the transparent substrate 3 are not easily separated, and the durability of the structure 100 as a product is improved. tan δ is more preferably from 0.2 to 1.0, and even more preferably from 0.2 to 0.8.
The internal transmittance of the optical bonding layer 2 is preferably 90% or more, and more preferably 98% or more. The internal transmittance indicates the transmittance excluding the surface reflection on the incidence side and the emission side of the light to the optical bonding layer in the transmittance measurement.
The haze value of the optical bonding layer 2 is preferably 1% or less, more preferably 0.5% or less.
If the optical bonding layer 2 has the above-described optical characteristics, light incident on the structure 100 is effectively guided to the optical element 6 without being scattered or absorbed by the optical bonding layer 2. Therefore, in a state where the electro-optical function layer 4 scatters incident light, light guided from the transparent plate 1 can be extracted at the scattering portion, and can be visually recognized as light emission at the scattering portion.

(Optical element 6)
The optical element 6 is configured by sandwiching the electro-optical function layer 4 between a pair of transparent substrates 3 and 5. As described above, the transparent electrodes (not shown) are provided on the surfaces of the pair of transparent substrates 3 and 5 that are in contact with the electro-optical function layer 4. An insulating layer or a liquid crystal alignment layer may be further provided between the transparent electrode layer and the electro-optical function layer 4. Further, an ultraviolet absorbing layer, an anti-reflection layer, a reflection layer, a semi-reflection layer, a fingerprint adhesion prevention layer, and the like can be provided on a part or all of the surfaces of the transparent substrates 3 and 5 which are not in contact with the electro-optical function layer.

  As described above, the optical element 6 can use a normal transmission type and a normal scattering type. When a display is formed by scattering incident light at a segment electrode portion formed by patterning a transparent electrode on a transparent background, it is necessary to always keep a wiring electrode for supplying electricity to the segment electrode in a transparent state. Therefore, it is preferable to use a normal transmission type.

  As the material of the transparent substrates 3 and 5, a material ensuring transparency can be used. For example, a resin plate such as an acrylic plate or a polyester plate, a glass plate, and the like can be given. The transparent substrates 3 and 5 are preferably glass plates from the viewpoint of enhancing the dimensional stability and rigidity of the optical element 6 and facilitating handling. Further, in terms of increasing the transparency of the structure 100, the transparent substrates 3 and 5 more preferably have optical properties close to those of the transparent plate 1.

For the transparent electrode, a metal oxide such as indium oxide-tin oxide (ITO Indium Tin Oxide), or a material made of a fine wire mesh or nanowire made of copper or silver can be used.
Although not shown, the transparent electrode is an essential component for driving the electro-optical function layer 4.

As described above, the shape of the transparent electrode may be provided on the entire surface of the transparent substrates 3 and 5 (so-called solid shape), and a portion where the electrode is provided on the surface of the transparent substrates 3 and 5 and a portion where the electrode is not provided (e. Shape or dot shape).
By providing an alignment film on the transparent substrates 3 and 5, the alignment of the liquid crystal compound can be controlled when the electro-optical function layer 4 is formed.

When a material having a positive dielectric anisotropy is used as the liquid crystal compound and the electro-optical function layer is operated by an electric field between a pair of electrodes facing each other, the alignment film having a pretilt angle of 10 ° or less is rubbed. It is preferable to use them. Thereby, the transparency of the optical element 6 can be increased.
When the electro-optical function layer is operated by an electric field between the comb-shaped electrodes formed on one of the transparent substrates 3 and 5, an alignment film having a pretilt angle of 60 ° or more is used without rubbing. Is preferred.

  When the electro-optical function layer is operated by an electric field between a pair of opposed electrodes, when a material having a negative dielectric anisotropy is used as a liquid crystal compound, the alignment film having a pretilt angle of 60 ° or more is rubbed. It is preferably used without treatment. Thereby, the transparency of the optical element 6 can be increased. Note that the pretilt angle is a value defined by setting a direction perpendicular to the transparent substrate to 90 °.

The electro-optical function layer 4 has a function of controlling transmission and scattering of incident light by applying a voltage to the transparent electrode. The transmission and scattering of incident light of the electro-optical function layer 4 by applying a voltage are often evaluated by observing the electro-optical function layer 4 from a vertical direction.
The electro-optical function layer 4 has a transmittance of 60% or more at a measurement angle (critical angle) of Expression 3 when the normal direction of the transparent substrate is 0 ° in a state of transmitting incident light. The transmittance is preferably 70% or more, more preferably 75% or more.
Measurement angle = arcsin (refractive index of medium adjacent to transparent plate 1 other than optical bonding layer / refractive index of transparent plate 1) Equation 3
Assuming that the normal direction of the transparent plate is 0 °, the light traveling from the transparent plate to the medium adjacent to the transparent plate inside the transparent plate 1 is equal to or larger than the angle (referred to as the critical angle) calculated by Expression 3 above. Light incident from the end face of the transparent plate 1 is totally reflected by the main surface 1s of the transparent plate 1. That is, light incident on the boundary surface on the side of the transparent plate 1 that is not in contact with the optical bonding layer from the inside of the transparent plate 1 at an angle equal to or larger than this angle is guided inside the structure 100 without leaking from the main surface 1s. Be lighted.

  In the state where the electro-optical function layer 4 transmits incident light, the haze value of the measurement angle of the above formula 3 is preferably 10% or less, more preferably 5% or less, and still more preferably 3% or less. In the present embodiment, if the haze value of the measurement angle of Equation 3 is 10% or less in a state where the incident light is transmitted, the light incident obliquely on the electro-optical function layer 4 is electrically transmitted. The optical function layer 4 makes scattering less likely. As a result, in the structure 100 of the present embodiment, the structure 100 can be made transparent even when light is incident on one end of the transparent plate 1 in a state where the electro-optical function layer 4 transmits light. .

  The electro-optical function layer 4 includes one or more liquid crystal compounds and an alignment regulating material for regulating the alignment of the liquid crystal compounds therein. When the alignment regulating material is formed of an aggregate of columnar resin, the columnar resin has a material whose major axis direction substantially coincides with the normal direction of the electrode and a material that is tilted. Liquid crystal domains are formed in connection with the aggregate of the columnar resins.

  The thickness of the electro-optical function layer 4 is preferably 1 to 50 μm, more preferably 3 to 30 μm. When the thickness of the electro-optical function layer 4 is 1 to 50 μm, an appropriate contrast ratio is realized, and the driving voltage can be reduced.

  Examples of the type of the liquid crystal compound included in the electro-optical function layer 4 include a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, and a ferroelectric liquid crystal. From the viewpoint of ease of manufacturing the optical element 6, it is preferable to use a nematic liquid crystal or a cholesteric liquid crystal as the type of the liquid crystal compound. In particular, a nematic liquid crystal has characteristics that a liquid crystal temperature range is wide and viscosity is low as compared with other liquid crystals.

As the liquid crystal compound, various materials used as a general display material or a material for an electric field drive type display element can be used. Specifically, biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, terphenyl, biphenylbenzoate, cyclohexylbiphenyl, phenylpyridine, cyclohexylpyrimidine, cholesterol, etc. Can be mentioned.
The liquid crystal compounds need not be used alone, as in the case where they are generally used, and two or more liquid crystal compounds may be used in combination. When a liquid crystal compound having a large absolute value of dielectric anisotropy is used, the driving voltage of the optical element 6 can be reduced. Examples of the liquid crystal compound having a large absolute value of dielectric anisotropy include a compound having a cyano group or a halogen atom such as fluorine or chlorine as a substituent.

ここで、Ａ⁵〜Ａ⁷は、それぞれ独立に、アクリロイルオキシ基、メタクリロイルオキシ基、ビニルエーテル基、ビニル基またはグリシジルエーテル基である。Ｒ⁵は、炭素原子間に一個または複数個のエーテル性酸素原子を有していてもよい直鎖又は分岐状炭素数１〜５０の１〜３価の有機基である。ｑ、ｒ、ｓは、それぞれ独立に０〜３である。但し、ｑ＋ｒ＋ｓ＝１〜３である。The orientation controlling material is a cured product of one or more curable compounds. Usually, a cured product of a curable resin composition containing a curable compound is suitably used as the alignment regulating material. As the curable compound, a compound having a high transmittance after curing and capable of aligning a liquid crystal compound is used. Examples of such a curable compound include compounds represented by Formulas 5 to 7.
A ¹ -O- (R ¹ ) _m -OZO- (R ² ) _n O-A ² Formula 5
_{^{A 3 - (OR 3) o}} -O-Z'-O- (R 4 O) p -A 4 ... Equation 6
Here, A ¹ , A ² , A ³ , and A ⁴ are each independently an acryloyl group, a methacryloyl group, a glycidyl group, or an allyl group. R ¹ , R ² , R ³ , and R ⁴ are each independently an alkylene group having 2 to 6 carbon atoms. Z and Z ′ are each independently a divalent mesogen structure. m, n, o, and p are each independently an integer of 1 to 10. Here, "independently" means that the combination is arbitrary and any combination is possible. Further, the curable compounds of the formulas 5 and 6 may have an ester bond or a carbonate bond in the molecule.

Here, A ^{5 to} A ⁷ are each independently an acryloyloxy group, a methacryloyloxy group, a vinyl ether group, a vinyl group or a glycidyl ether group. R ⁵ is a monovalent to trivalent organic group one or more may have an etheric oxygen atom linear or branched carbon atoms 1 to 50 between the carbon atoms. q, r, and s are each independently 0 to 3. However, q + r + s = 1 to 3.

The electro-optical function layer 4 may include components other than the liquid crystal compound and the alignment controlling material.
Other components include a polymerization initiator. Known polymerization catalysts can be selected as the polymerization initiator, and examples thereof include benzoin ether-based, acetophenone-based, and phosphine oxide-based.

Other components include various dichroic dyes such as anthraquinone, styryl, azomethine, and azo dyes. When these components are included, the contrast ratio of the electro-optical function layer 4 can be increased, and the stability can be improved.
Further, from the viewpoint of improving the stability and durability of the electro-optical function layer 4, other components may include an antioxidant, an ultraviolet absorber, and various plasticizers.

  The optical element 6 can be formed by curing a liquid mixture of the precursor of the electro-optical function layer 4 (hereinafter, simply referred to as a “liquid mixture”). The mixture is sandwiched between a transparent electrode, a pair of transparent substrates 3 and 5 having an insulating layer and an alignment film, and the mixture is irradiated with an ultraviolet ray or an electron beam, whereby the curable compound is cured and the liquid crystal compound is cured. The cured product can be phase-separated to form a good electro-optical functional layer 4 that can function optically.

  The mixed liquid contains one or more liquid crystal compounds described above, one or more curable compounds, and other components as necessary. Each component and its mixing ratio are determined according to the optical characteristics exhibited by the electro-optical function layer 4.

(Second embodiment)
A second embodiment of the structure according to the present invention will be described with reference to FIGS. In the description of the second embodiment, the same description as in the first embodiment will be omitted.

  FIG. 3 is a cross-sectional view of the structure 101 according to the present embodiment. As shown in FIG. 3, the structure 101 has a reflecting portion 8 at one end of the transparent plate 1, and the other configuration is the same as that of the first embodiment.

Since the structure 101 has the reflecting portion 8 at one end of the transparent plate 1, light guided inside the structure 101 is less likely to leak from a surface (side surface) perpendicular to the main surface of the transparent plate 1. Thus, the light use efficiency can be improved.
The position of the reflector 8 is not limited. Further, as shown in FIG. 4, it is more preferable that the reflecting portion 8 is provided at the end of the transparent plate 1 and the end of the optical element 6 because light leakage from the side surface of the structure 101 can be prevented. Further, when the structure 101 has the reflecting portion 8 in the modes shown in FIGS. 3 and 4, light is incident on the transparent plate 1 as shown in FIG. 5, which is a top view of the structure 101 viewed from the main surface 5s side of the transparent substrate 5. The reflecting portion 8 may be provided at all ends other than the portion (incident portion 9) to be formed.

(Reflector 8)
The reflection section 8 may be a member that reflects light itself, or may be a member in which a reflection film is attached to a resin film or the like. For example, an aluminum tape in which an aluminum film is adhered to a resin film may be used.

(Third embodiment)
A third embodiment of the structure according to the present invention will be described with reference to FIG. In the description of the third embodiment, the same description as in the first embodiment will be omitted.

  FIG. 6 is a sectional view of the structure 102 according to the present embodiment. As shown in FIG. 6, in the structure 102, transparent plates 1-1 and 1-2 are laminated and integrated on both surfaces of the optical element 6 via optical bonding layers 2-1 and 2-2, respectively. Other configurations are the same as those of the first embodiment.

  The structure of the structure 102 can utilize light guide by a transparent plate optically bonded to both surfaces of the optical element 6, so that the light emission luminance of the electro-optical function layer at the scattering portion of incident light can be increased. And visibility can be improved.

  In the case where light enters from one end of the transparent plate, the light incident side of the transparent plate 1-2 is opposed to the light incident side of the transparent plate 1-1, so that light emission at the scattering portion of the electro-optical function layer is achieved. This is preferable because uniformity in the plane of the optical element can be improved. When the optical element 6 is stacked and integrated on the upper surface or the lower surface of the structure 102 via an optical bonding layer, multiple display by the optical element can be provided.

(Fourth embodiment)
A fourth embodiment of the structure according to the present invention will be described with reference to FIGS. In the description of the fourth embodiment, the same description as in the first embodiment will be omitted.

  FIG. 7 is a cross-sectional view of the structure 103 according to the present embodiment. As shown in FIG. 7, the structure 103 has the transparent electrode 10 only on the transparent substrate 3 and does not have the transparent electrode on the transparent substrate 5. Other configurations are the same as those of the first embodiment.

  The transparent electrode 10 generates an electric field having lines of electric force in a direction parallel to the transparent substrate 3. By providing such an electrode only on the transparent substrate 3, it is possible to control the state in which the electro-optical function layer 4 transmits light and the state in which light is scattered. For example, if the areas of the transparent substrates 3 and 5 are large, it may be difficult to keep the distance between the electrodes constant, and the effective voltage applied to the electro-optical function layer due to the distance between the electrodes may be reduced. In the plane of No. 6, there is a possibility that a distribution occurs in the intensity and the contrast between transmission and scattering becomes non-uniform. This embodiment is preferable because the above-mentioned problem is solved.

  As the transparent electrode 10, for example, as shown in the plan view of FIG. The transparent electrode 10 of the present embodiment is not limited to the mode shown in FIG.

  As shown in FIG. 8, the comb-shaped electrode has a first electrode 31 and a second electrode 36, each having a linear connection portion 32, 37, and a direction of one side opposed to the connection portion 32, 37. It has a plurality of linear comb teeth 33, 38 extended. The comb portions 33 and 38 are arranged in parallel with each other and alternately. As a result, the comb-tooth portions 33 and 38 form an electrode pair with each other, and generate an electric field in the electro-optical function layer 4.

  In the structure 103 of the present embodiment, the liquid crystal compound having a positive dielectric anisotropy is formed by forming the electro-optical function layer so as to be substantially aligned in the normal direction of the transparent substrate without applying a voltage. Is preferred. Thus, when a voltage is applied to the transparent electrode 10, an electric field having lines of electric force in a direction parallel to the surface of the transparent substrate 3 is generated, and the liquid crystal compound moves so that the major axis thereof coincides with the direction of the lines of electric force. I do. At this time, the liquid crystal compound existing in the vicinity of the alignment controlling material is restricted in movement and takes an alignment different from the line of electric force. As a result, it is considered that the ordered structure is disturbed in the liquid crystal domain and the incident light is scattered.

  In the structure 103 of the present embodiment, the transparent electrode 10 is formed on one surface of the transparent substrate 3, but the transparent electrode 10 may be formed on one surface of the transparent substrate 5. Even with this configuration, the same operation as described above can be obtained.

(Fifth embodiment)
A fifth embodiment of the structure according to the present invention will be described with reference to FIG. In the description of the fifth embodiment, the same description as in the first embodiment will be omitted.

  FIG. 9 is a cross-sectional view of the structure 104 according to the present embodiment. As shown in FIG. 9, the structure 104 has a transparent plate 11 having an area larger than that of the optical element 6 instead of the transparent plate 1 of the above-described example, and other configurations are the same as those of the first embodiment. It is.

  The optical properties and materials of the transparent plate 11 are the same as those of the transparent plate 1. Since the area of the transparent plate 11 is larger than that of the optical element 6, the transparent plate 11 has a portion that does not come into contact with the optical element 6 via the optical bonding layer 2 (non-bonded portion 11 a). The non-bonding part 11a of the transparent plate 11 may be provided with a light emitting part such as a diffusion pattern or dot-like fine irregularities. With such a configuration, for example, a structure having a portion having the electro-optical function layer 4 capable of variably controlling the transmission and scattering of the incident light by applying a voltage, and a portion constantly emitting the incident light can be obtained. . When light is incident from the end of the transparent plate 11, if light is incident from a side that does not coincide with the end of the optical element 6, that is, one side on the side of the non-bonding part 11 a, light enters. Installation of necessary members is easy and preferable.

Another embodiment of the structure according to the present invention will be described with reference to FIG.
(Sixth embodiment)
A sixth embodiment of the structure according to the present invention will be described with reference to FIG. The structure according to the sixth embodiment has an electro-optical function layer sandwiched between a transparent substrate and a transparent plate, and an electrode is formed on at least one of the transparent substrate and the transparent plate. The layer can control the state where the incident light is transmitted and the state where the incident light is scattered by applying a voltage. In the state where the incident light is transmitted, the transmittance of the layer at the measurement angle of Expression 4 is 60% or more.
Measurement angle = arcsin (refractive index of medium other than electro-optical function layer adjacent to transparent plate / refractive index of transparent plate) Equation 4
The transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.

  FIG. 10 is a cross-sectional view of the structure 105 according to the present embodiment. As shown in FIG. 10, the structure 105 has a transparent plate 12, a transparent substrate 5, and the electro-optical function layer 4 sandwiched between the transparent plate 12 and the transparent substrate 5. That is, a transparent plate 12 having both functions of the transparent plate 1 and the transparent substrate 3 shown in the first to fifth embodiments without the optical bonding layer 2 in the first to fifth embodiments is provided. In the present embodiment, a transparent electrode layer (not shown) is provided on a surface of the transparent plate 12 and the transparent substrate 5 which are in contact with the electro-optical function layer 4. Further, the transparent plate 12 and the transparent plate 5 may be provided with another layer described in the first embodiment.

  The electro-optical function layer 4 has a transmittance of 60% or more at the measurement angle (critical angle) of Expression 4 in a state of transmitting incident light. The transmittance is preferably 70% or more, more preferably 75% or more.

(Modification)
In another embodiment according to the present invention, the reflecting portion 8 may be provided at one end of the transparent plate 12. The same members, positions and numbers as those of the reflecting section 8 can be the same as those in the second embodiment. This is preferable because light absorption by the transparent substrate is reduced, and loss of light amount during light guiding can be further reduced.
In another embodiment according to the present invention, the transparent substrate 5 may be the same as the transparent plate 1 (or the transparent plate 12). It is preferable that the electro-optical function layer is sandwiched between a pair of transparent plates because loss of the amount of light during light guiding due to light absorption of the transparent substrate can be reduced.
In another embodiment according to the present invention, a configuration having a transparent electrode only on at least one of the transparent plate 12 and the transparent substrate 5 may be employed. In this case, the electrode described in the fourth embodiment can be used as the transparent electrode.
In another embodiment according to the present invention, the size of the transparent plate 12 or the transparent substrate 5 may be different.

[Transparent display]
One embodiment of the transparent display according to the present invention will be described with reference to FIGS. The transmittance of the transparent display of this embodiment in the transparent state (ie, the transparent portion in the transparent state) is 70% or more, and the luminance contrast ratio between the transparent state and the light emitting state (ie, the scattering portion in the light emitting state). Is 4 or more. The transparent display of the present embodiment can function as information display or planar illumination depending on the shape of the electrodes and the like.

  In the case where the transparent display emits light over the entire surface, the transmittance and the luminance contrast ratio measure a transparent state and a light emitting state in any part of the transparent display. When the transparent display has a transparent portion and a light emitting portion, the transmittance may be measured at the transparent portion, and the luminance contrast ratio may be measured at the transparent portion and the light emitting portion.

(First embodiment)
A first embodiment of the transparent display according to the present invention will be described with reference to FIG. Further, a modified example thereof will be described with reference to FIGS. 12 (A), 12 (B) and 13.
FIG. 11 is a sectional view showing a transparent display 200 according to the present embodiment. As shown in FIG. 11, the transparent display 200 includes the structure 100 of the present invention, a control unit that applies a voltage to the electrodes of the structure 100, and a light source 13 at one end of the transparent plate 1 of the structure 100. In the following description, description of the structure 100 of the first embodiment will be omitted.

The structure of the structure of the transparent display 200 of the present embodiment is not limited, and any structure included in the technical scope of the present invention can be used.
The transparent display 200 of the present embodiment has the structure 100 and the light source 13 outside one end of the transparent plate 1. Light emitted from the light source 13 and incident on the transparent plate 1 is scattered by the optical element 6, so that the transparent display 200 can emit light without depending on the intensity of environmental light.
The transparent display 200 becomes planar illumination or partial illumination by controlling the pattern of the transparent electrode of the optical element 6 to control the in-plane effective value voltage. Further, the transparent display 200 itself can function as an information display device. .

The transparent display 200 functioning as partial illumination can also be used as an illumination device for a liquid crystal panel. By arbitrarily controlling the illuminating portion of the transparent display, it is possible to improve display contrast by local dimming in an edge-light type liquid crystal display device in which light is incident from the side surface of the display panel. When a liquid crystal panel is combined with the transparent display as a lighting device, a light guide plate lighting device, a light diffusion sheet, and a planar mirror member of a normal edge light type liquid crystal display device can be used in combination. When used together with the light diffusion sheet, when the transparent display is used as planar illumination over the entire surface, the in-plane illumination luminance distribution can be reduced, which is preferable. It is preferable to provide the planar mirror member on the back surface of the transparent display surface that illuminates the liquid crystal panel, since the illumination brightness of the liquid crystal panel can be increased.
When a transparent display is used as a lighting device for a liquid crystal panel, a light emitting surface such as a diffusion pattern or a dot-like groove may be provided on a surface of the transparent plate 1 not in contact with the optical bonding layer or on a surface of the transparent substrate 5 not in contact with the optical functional layer. A portion for illuminating the liquid crystal panel in a fixed manner may be provided.

A specific example in which the transparent display 200 functions as planar light emission, that is, an example in which the transparent display 200 functions as a lighting device is described below.
Depending on the pattern design of the transparent electrode of the optical element 6, the electrode area operated by applying a voltage to the optical functional layer near the light source 13 may be made sparse, and may be made denser away from the light source. Thereby, when illuminating the entire surface of the transparent display, the intensity of light in the plane emitted from the optical element 6 can be made uniform.

  In the case where the transparent display 200 is used for arbitrary partial illumination of the liquid crystal panel, a dot matrix configuration is preferable as the pattern of the transparent electrodes forming the optical element. Depending on the driving method of the optical element, static driving and segment driving may be required. In such a case, wiring of each dot of the dot matrix electrode may be provided in the electrode substrate surface. In this case, it is preferable to reduce the area of the wiring as long as the optical element can be driven. It is preferable to use a light diffusion sheet or the like in combination in order to suppress the unevenness of the light emission luminance in the plane of the transparent display due to the wiring portion.

Further, when the optical element is driven by a dot matrix electrode, by applying different effective voltages to the dot electrodes separated from the dot electrode adjacent to the light source 13 and controlling the degree of light scattering for each dot, Thereby, the distribution of light emission luminance in the plane can be improved, which is preferable. By making the light scattering intensity of the dots far from the light source higher than that of the dots close to the light source, the distribution of the emission luminance of each dot can be suppressed depending on the distance from the light source 13, which is preferable.
As a method of applying a different execution voltage to each dot electrode, a different voltage value is applied to each dot electrode, or a pulse width modulation method (referred to as PWM) in which the application time is periodically changed with the same voltage value. And so on. When an optical element that responds to an effective value is used, it is preferable to use a PWM drive, which makes it relatively easy to design a drive circuit.

The light source 13 includes a light bulb, an LED (Light Emittion Diode), an organic EL (Electro Luminescence), a cold-cathode tube, and the like. The light is incident on the surface of the structure 100 on which the optical bonding layer of the transparent plate 1 is not formed. Total reflection. It is preferable to use an LED because the light use efficiency of the emitted light is high and the size of the light source can be reduced.
The light source 13 may be provided other than one end of the transparent plate 1 of the structure 100. That is, it may be provided so as to surround the periphery of the transparent plate 1 or may be provided only at one end. Further, the light source 13 may be directly joined to the end of the transparent plate 1 or may be installed via a slight air layer.

  The transparent display 200 of the present embodiment emits light by extracting the light guide in the transparent plate 1 at the scattering portion of the electro-optical function layer 4 to the outside. Then, the display unit emits light, and the parts other than the display unit are transparent.

(Modification)
FIGS. 12A, 12B, and 13 are top views of modified examples of the transparent display when the arrangement method of the light source 13 is changed, as viewed from the main surface 5s side of the transparent substrate 5. FIG.
The transparent displays 201 and 202 shown in FIGS. 12A and 12B are configured to have an end where the light source 13 is provided only at the end of the transparent plate 1 and an end where the light source 13 is not provided. The transparent display 201 has the light source 13 provided at one end of the transparent plate 1 as shown in FIG. 12A, and the transparent display 202 has the light source 13 as shown in FIG. Are provided to face each other. In these configurations, as described in the structure 101, it is preferable to provide the reflecting portion 8 other than the incident portion 9 of the transparent plate 1. Thereby, the light use efficiency can be improved.
FIG. 13 shows a configuration of a transparent display 203 having light sources 13 at all peripheral ends of the transparent plate 1. With this configuration, as the number of light sources is larger, more light can be extracted in a state where the electro-optical function layer 4 of the structure 100 scatters incident light.
The color of the light source 13 is not particularly limited. A light source that emits red, blue, and green light may be used, or a monochromatic light source may be used.

When a light source whose emission color switches between red, blue, and green is used as the light source 13, the transparent displays 200 to 203 shown in FIGS. 11 to 13 can perform color display. For example, similar to the so-called field sequential color system, by controlling the frequency of the sequential lighting of red, blue, and green light emission, and controlling the transmission and scattering states of the electro-optical function layer 4 in conjunction with the lighting of the light emission color. And a single display segment electrode can emit light in a plurality of colors.
In addition, a mirror having a transparent display can be obtained by installing a mirror member such as a reflector on one surface of the transparent display. In this configuration, the light guide display is formed in the mirror, and a mirror capable of displaying information can be provided.

[Liquid crystal display]
One embodiment of a liquid crystal display device using a transparent display according to the present invention will be described with reference to FIGS. In order to explain the present embodiment, a conventional technique of a liquid crystal display device using a light guide plate will be described. A liquid crystal display device using a light guide plate includes, in order from the display surface side, a liquid crystal panel, a plurality of diffusion plates, a light guide plate, and, if necessary, a mirror member such as a mirror. The light guide plate is provided with a specific pattern such as a dot shape by printing or fine unevenness processing, and light incident from the side surface of the light guide plate is extracted by scattering or refraction at the arrangement pattern portion and emits light. The light is diffused by the diffusion plate and enters the display panel. In such a display device, the arrangement pattern of the light guide plate surface is fixed, and the light emission intensity cannot be arbitrarily partially changed within the light guide plate surface according to the display image of the liquid crystal panel.

(First embodiment)
A first embodiment of a liquid crystal display device using a transparent display according to the present invention will be described with reference to FIG.
In the liquid crystal display device of the present embodiment, the transparent display 200 that functions as an illumination device capable of planar illumination is used.

FIG. 14 is a cross-sectional view of the liquid crystal display device 300. As shown in FIG. 14, in the liquid crystal display device 300, the liquid crystal panel 14 is arranged so as to face the optical element 6 of the transparent display 200. That is, in the liquid crystal display device 300, the transparent display 200 functions as a lighting device as a backlight. In the following description, description of the transparent display 200 will be omitted.
The form of the transparent display is not limited in the liquid crystal display device of the present invention, and all the transparent displays included in the technical scope of the present invention can be used.
In the liquid crystal display device 300 of the present embodiment, the light source 13 of the transparent display 200 uses white light.

  As the liquid crystal panel 14, a known liquid crystal display panel can be used. For example, a TN (Twisted Nematic) mode liquid crystal panel, a VA (Vertical Alignment) mode liquid crystal panel, an IPS (In Plane Switching) mode liquid crystal panel, or the like can be used.

  The liquid crystal panel 14 includes a transparent substrate 15 having a TFT (Thin Film Transistor), a transparent substrate 17 having a color filter, and a liquid crystal layer 16. Polarizing plates may or may not be provided on the transparent substrates 15 and 17. If a polarizing plate is not provided, black display cannot be performed, but the transmittance of the liquid crystal panel 14 is increased, which is preferable. When color display is not required, the transmittance of the liquid crystal panel 14 can be increased by not using a color filter.

In the liquid crystal display device 300 of the present embodiment, the optical element 6 of the transparent display 200 shows a transparent state and a scattering state. When the optical element 6 is in a transparent state, since the transparent display 200 is transparent, the image display of the liquid crystal panel 14 and the background of the liquid crystal panel 14 can be seen through and superimposed on each other. When the optical element 6 is in the scattering state, the transparent display 200 takes out the light guide of the transparent plate 1 and emits light, and has the same function as the backlight of a normal liquid crystal display device. That is, by switching the optical element 6 between the transparent state and the scattering state, the liquid crystal display device 300 can be switched between a transparent liquid crystal display device and an opaque liquid crystal display device.
At this time, when the optical element 6 is scattered, a specific pattern may be provided on the electrode for applying an electric field to the electro-optical function layer 4 so that the light emission luminance distribution in the plane of the transparent display 200 can be made uniform. Alternatively, the electrode pattern is formed in a dot matrix configuration, and the effective value voltage applied to each dot is changed as described above. This makes it possible to realize a liquid crystal display device that is transparent during non-display and suppresses the luminance distribution on the display surface during display.
In addition, when the optical element 6 is scattered, a dot matrix or the like is applied to the electrode for applying an electric field to the electro-optical function layer 4 so that the emission luminance distribution in the plane of the transparent display 200 is controlled according to the display image. May be provided. This makes it possible to realize a liquid crystal display device having both a display unit for normal liquid crystal display and a transparent non-display unit. Further, by controlling the light emission luminance of the transparent display 200 in accordance with the brightness of the image projected on the display unit, it is possible to configure a liquid crystal display device in which the contrast is greatly improved by the action of local dimming.

  The liquid crystal display device 300 of this embodiment switches between light transmission and surface light emission of the transparent display 200 at high speed, displays the liquid crystal panel 14 only at the timing of surface light emission, and transmits light through the liquid crystal panel 14 when the transparent display 200 is transparent. By operating such that the ratio becomes the highest, the contrast in the transparent display can be increased.

  Also, even if the color filter is removed from the liquid crystal panel 14, the light source 13 of the transparent display 200 is sequentially turned on using the above-described LEDs that emit red, green, and blue, and the liquid crystal panel 14 is synchronized with the lighting. Is operated, color display by so-called field sequential driving can be provided. In this case, it is preferable that the liquid crystal panel 14 has no polarizing plate. Thereby, the transmittance of the transparent background can be increased, and the visibility of the background can be increased. At this time, when the LEDs of the light source 13 of the transparent display 200 are sequentially turned on, a field in which none of the LEDs emits light is appropriately provided, and the transparent display 200 is operated so as to increase the transmittance of the liquid crystal panel 14 at a transparent timing. Thus, the transparency of the background can be further increased. When the liquid crystal panel 14 is sandwiched between a pair of polarizing plates, the transparency at the time of transmission is reduced, but black display is possible.

The liquid crystal panel 14 may be a passively driven liquid crystal panel having no TFT. If a TFT is not used, transparency at the time of transmission can be increased.
When the transparent display is unnecessary, it is preferable to install a mirror member such as a reflector on a surface of the transparent display 200 that does not correspond to the liquid crystal panel 14, similarly to the conventional liquid crystal display device, so that the illumination efficiency can be increased, which is preferable. . In this case, it is preferable to dispose a light diffusion sheet or the like between the transparent display 200 and the liquid crystal panel 14, since the luminance distribution in the plane of the transparent display can be suppressed. Further, a light emitting portion such as a diffusion pattern or dot-like fine irregularities is provided on a surface of the transparent display 200 not in contact with the optical bonding layer of the transparent plate 1 or a surface of the transparent substrate 5 not in contact with the optical functional layer, and fixed. A portion for illuminating the liquid crystal panel may be provided.

(Modification)
FIG. 15 and FIG. 16 are cross-sectional views of a modification of the liquid crystal display device of the present embodiment.
In the liquid crystal display device 301 shown in FIG. 15, the liquid crystal panel 14 is arranged to face the transparent plate 1 of the transparent display 200.

In the liquid crystal display device 302 shown in FIG. 16, the liquid crystal panel 14 is arranged to face the optical element 6 of the transparent display 200, and the optical element 6 and the liquid crystal panel 14 are joined via the optical joining layer 18. Thus, the light emitted from the light source 13 can be efficiently used for display on the liquid crystal panel 14. The optical bonding layer 18 may be the same as the optical bonding layer for bonding the transparent plate 1 and the optical element 6 in the structure.
Further, by providing a mirror member such as a reflector on one surface of the liquid crystal display device, when the transparent display is made transparent, a display can be formed in the mirror, and a mirror capable of displaying information can be provided. On the other hand, when the transparent display is made to function as a lighting device, its lighting efficiency can be improved, which is preferable.

In the information display device of the present invention, the transmittance of the transparent portion is 70% or more, and the luminance contrast ratio between the transparent portion and the scattering portion is 4 or more in a state where there is no light incident from the side facing the display surface. .
In a more specific aspect of the information display device, at least one of a pair of transparent substrates having electrodes formed thereon, an electro-optical function layer sandwiched between the pair of transparent substrates, and at least one of the transparent substrates A transparent plate laminated via an optical bonding layer, wherein the electro-optical function layer can control a state where incident light is transmitted and a state where light is scattered by applying a voltage, and transmits the incident light. In the state, the transmittance at the measurement angle of the following equation 3 is 60% or more;
Measurement angle = arcsin (refractive index of medium other than optical bonding layer adjacent to transparent plate / refractive index of transparent plate) Equation 3
A structure in which the transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm;
A light source disposed on at least one end surface of the transparent plate of the structure.

Further, in a more specific aspect of the information display device, comprising an electro-optical functional layer that is between a pair of transparent plates, and electrodes are formed on at least one of the permeable Akiraban, the electrical The optical function layer can control a state where incident light is transmitted and a state where the incident light is scattered by application of a voltage. In a state where the incident light is transmitted, a transmittance at a measurement angle of the following Expression 4 is 60% or more;
Measuring angles = arcsin (refractive index / breathable Akiraban medium in the portion other than the electro-optical functional layer adjacent to the magnetic Akiraban) Equation 4
Said at least one permeable Akiraban, the optical path length is disposed and structures average internal transmittance of 80% or more in the wavelength region in the wavelength 400nm~700nm at 50 mm, at least on one end face of the transparent plate of the structure Light source.
In the description of the information display device, the description of the liquid crystal display device described above can be used.

  The present invention will be described with reference to FIGS. Example 1 is an example, and Examples 2 and 3 are comparative examples.

(Example 1)
An optical element 6 in which an electro-optical function layer 4 made of a liquid crystal compound and an alignment controlling material was sandwiched between a pair of soda lime glass substrates (transparent substrates) 3 and 5 was prepared. This optical element scatters when a voltage is applied and shows a transparent state when no voltage is applied. As the transparent plate 11, a glass substrate for a light guide plate (XCV manufactured by Asahi Glass Co., Ltd., refractive index: 1.52) was prepared. This glass substrate for a light guide plate had an average internal transmittance of 98.8% in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.
The optical element 6 and the glass substrate 11 for a light guide plate were bonded together via the optical bonding layer 2 so that the cross-sectional shape became as shown in FIG. The dynamic shear storage modulus (G ′) at 35 ° C. and 1 Hz of the optical bonding layer was 8.9 kPa. Thus, the structure of Example 1 was manufactured.

(Example 2)
The structure of Example 2 was prepared in the same manner as in Example 1, except that a commercially available electro-optical element (trade name: UMU FILM, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the optical element 6.

(Example 3)
The optical element used in Example 1 was used alone.

(Evaluation)
For Examples 1 to 3, the transmittance at 0 ° (normal direction) and 45 ° (oblique incident direction) in the transparent state of the electro-optical function layer of the optical element, and the light-guided light emission when the normal direction is transparent and when scattering. The contrast ratio determined from the luminance ratio (intensity when scattering / intensity when transparent) was measured.

(Transmission measurement)
The transmittances of the structures of Examples 1 to 3 were measured with the optical element transmitting light and not irradiating light from the light source. In Examples 1 and 3, the measurement was performed with no voltage applied to the optical element. In Example 2, the transmittance was measured with a rectangular wave of 50 Hz and a voltage of 60 V applied to the optical element. Table 1 shows the results.
The glass substrate for a light guide plate as a transparent plate used in this embodiment has a refractive index of 1.52, and the medium in a portion adjacent to the glass substrate for a light guide plate and not in contact with the optical bonding layer is air (refractive). Rate 1). Therefore, the measurement angle calculated by Expression 3 is 41.1 °. In this example, the transmittance was measured at a measurement angle of 45 ° for convenience of the measurement device. In general, the transmittance of an optical element decreases as the measurement angle increases, so that the distance of light passing through the optical element increases.

(Measurement of contrast ratio)
The measurement of the contrast ratio of the structures of Examples 1 to 3 was performed in the state where the light from the light source was irradiated. In Examples 1 and 2, the light source 13 is arranged at one end of the light guide plate glass substrate 11 so that the light of the light source 13 is incident from the light guide plate glass substrate as shown in FIG. As shown in FIG. 18, the light source 13 was arranged at one end of the optical element 6 for measurement.

In the measurement of the contrast ratio in Examples 1 to 3, the surface of the glass substrate 11 for a light guide plate not in contact with the optical element 6 and the surface of the optical element 6 not facing the detector are as shown in FIG. , A light shielding plate 19 was provided via an air layer. Thereby, the incidence of light from the surface facing the display surface of the optical element is suppressed.
The measurement was performed at each of the five locations of the structures of Examples 1 to 3, and the average value was used as the value of the contrast ratio. The measurement was performed by changing the intensity of the incident light by two levels (high intensity and low intensity). Table 1 shows the results.

表１に示すように、例１および例３の構造体は、液晶化合物と配向規制材からなる法線方向および斜入射方向の透過率が高い電気光学機能層を有する。このため、例１および例３の構造体は、市販の電気光学素子である電気光学機能層を用いた例２の構造体に比べて法線方向および斜入射方向において高い透過率を示す。特に、例１と例２とを比較すると、例１に使用している電気光学機能層は、斜入射方向の透過率が、例２のそれよりも高いため、導光板用ガラス基板から、それと隣接する媒体に向かう光が前記式３'の角度以上となるように導光板用ガラス基板の端部より入射した光は、電気光学機能層において、その入射光が散乱されにくいために例１の透明時の導光発光強度は小さくなる。光学素子が散乱時の導光発光強度は、例１、例２共に高いことから、例１の構造体のコントラスト比が高くなった。いいかえると、例２で使用した電気光学機能層のように斜入射方向の透過率が低いものは、光学素子が透明状態であっても導光板用ガラス基板から入射した光が、構造体の中を導光する際に散乱される。その結果、透明時であっても、電気光学機能層に入射する光が散乱されることによって、その導光発光強度が高くなり、そのコントラスト比が低下する。

As shown in Table 1, the structures of Examples 1 and 3 each have an electro-optical function layer composed of a liquid crystal compound and an alignment controlling material and having high transmittance in the normal direction and in the oblique incidence direction. Therefore, the structures of Examples 1 and 3 exhibit higher transmittance in the normal direction and the oblique incidence direction than the structure of Example 2 using the electro-optical functional layer which is a commercially available electro-optical element. In particular, comparing Example 1 and Example 2, the electro-optical function layer used in Example 1 has a higher transmittance in the oblique incident direction than that of Example 2, and thus the electro-optical function layer is formed from the light guide plate glass substrate. The light incident from the end of the glass substrate for a light guide plate such that the light directed to the adjacent medium is equal to or larger than the angle of the above formula 3 'is used in Example 1 because the incident light is hardly scattered in the electro-optical function layer. The light guide emission intensity when transparent is reduced. Since the light emission intensity of the light guide when the optical element was scattered was high in both Examples 1 and 2, the contrast ratio of the structure of Example 1 was high. In other words, when the transmittance in the oblique incidence direction is low, such as the electro-optical function layer used in Example 2, even if the optical element is in a transparent state, the light incident from the glass substrate for the light guide plate will Are scattered when the light is guided. As a result, even in the transparent state, the light incident on the electro-optical function layer is scattered, so that the light-guided light emission intensity increases and the contrast ratio decreases.

As described above, Example 1 and Example 3 use the electro-optical function layer having a high transmittance in the oblique incidence direction in the transparent state, so that when light is incident on the structure, the light is similarly guided in the observation surface direction. Is obtained, the light emission intensity when the optical element is transparent becomes equal.
However, in Example 3, there is no transparent plate optically bonded to the electro-optical function layer, and light is incident on the end of the soda lime glass substrate constituting the electro-optical function layer. Light guiding itself to the observation surface direction cannot be obtained due to light absorption. Therefore, the light emission luminance when the optical element is in a transparent state is low as in Example 1, but the contrast ratio is low because the light-guided light emission intensity is low even when the optical element is scattered. That is, only in the configuration of the present invention, the light guide emission intensity when the optical element is transparent can be reduced, and at the same time, a sufficient light guide emission intensity can be obtained when the optical element is scattered. And a transparent light-emitting display with high brightness can be provided.

According to the structure of the present invention, when the intensity of ambient light is sufficiently high, a high contrast ratio of transmission and scattering of an optical element using ambient light can be obtained. When there is almost no light, the light from the light source is incident on the edge of the transparent plate, whereby a good display with a contrast ratio of 5 or more due to the light-guided light emission is obtained.
Further, according to the illumination device of the present invention, it is possible to switch between the transparent state and the light emitting state by applying and not applying a voltage to the optical element without depending on the intensity of the ambient light.
The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2015-166175 filed on August 25, 2015 are incorporated herein by reference. .

1: transparent plate, 1s: main surface of transparent plate 1, 2: optical bonding layer, 3: transparent substrate, 4: electro-optical function layer, 5: transparent substrate, 5s: main surface of transparent substrate 5, 6: optical element , 7: light, 8: reflective portion, 9: incident portion, 10: transparent electrode (electrode), 11: transparent plate, 11a: non-bonded portion, 12: transparent plate, 13: light source, 14: liquid crystal panel, 15 : Transparent substrate, 16: liquid crystal layer, 17: transparent substrate, 18: optical bonding layer, 19: light shielding plate, 100 to 106: structure, 200 to 202: transparent display, 300 to 302: liquid crystal display device.

Claims (13)

A pair of transparent substrates on at least one of which electrodes are formed,
An electro-optical function layer having a thickness of 3 to 30 μm sandwiched between the pair of transparent substrates;
At least one of the transparent substrates, and a transparent plate laminated via an optical bonding layer,
The light incident from the edge of the transparent plate is guided to the electro-optical function layer, and in the electro-optical function layer, the light incident from the edge is transmitted when no voltage is applied to the electrodes. In a state where a voltage is applied to the electrode, the light incident from the edge portion is scattered,
The electro-optical functional layer includes a liquid crystal compound and an alignment controlling material that controls alignment of the liquid crystal compound,
The alignment regulating material is formed of an aggregate of columnar resins, and the columnar resins include those whose major axis directions are substantially coincident with the normal direction of the electrode and those that are tilted. It consists of a cured product of a curable resin composition,
The liquid crystal compound forms a liquid crystal domain in connection with the aggregate of the columnar resin,
In a state where incident light is transmitted, the transmittance at the measurement angle of the following Expression 3 is 60% or more,
Measuring angles = arcsin (refractive index / the transparent plate of the medium in contact with the surface opposite to the optical bonding layer side of the transparent plate) Equation 3
The transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.
Structure.   A transparent substrate,
  An electro-optical function layer having a thickness of 3 to 30 μm;
  A transparent plate disposed to face the transparent substrate via the electro-optical function layer,
  Having an electrode formed on at least one of the transparent substrate and the transparent plate,
  The light incident from the edge of the transparent plate is guided to the electro-optical function layer, and in the electro-optical function layer, the light incident from the edge is transmitted when no voltage is applied to the electrodes. In a state where a voltage is applied to the electrode, the light incident from the edge portion is scattered,
  The electro-optical functional layer includes a liquid crystal compound and an alignment controlling material that controls alignment of the liquid crystal compound,
  The alignment regulating material is formed of an aggregate of columnar resins, and the columnar resins include those whose major axis directions are substantially coincident with the normal direction of the electrode and those that are tilted. It consists of a cured product of a curable resin composition,
  The liquid crystal compound forms a liquid crystal domain in connection with the aggregate of the columnar resin,
  In a state where the incident light is transmitted, the transmittance at the measurement angle of the following Expression 4 is 60% or more;
    Measurement angle = arcsin (refractive index of medium in contact with a surface of the transparent plate opposite to the electro-optical function layer side / refractive index of the transparent plate) Expression 4
  The transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.
  Structure.   An electro-optical function layer having a thickness of 3 to 30 μm;
  A pair of transparent plates sandwiching the electro-optical function layer and having at least one electrode formed thereon,
  Light incident from an edge portion of at least one end of the pair of transparent plates is guided to the electro-optical function layer, and transmits light incident from the edge portion in a state where no voltage is applied in the electro-optical function layer. In the state where a voltage is applied, the light incident from the edge portion is scattered,
  The electro-optical functional layer includes a liquid crystal compound and an alignment controlling material that controls alignment of the liquid crystal compound,
  The alignment regulating material is formed of an aggregate of columnar resins, and the columnar resins include those whose major axis directions are substantially coincident with the normal direction of the electrode and those that are tilted. It consists of a cured product of a curable resin composition,
  The liquid crystal compound forms a liquid crystal domain in connection with the aggregate of the columnar resin,
  In a state where the incident light is transmitted, the transmittance at the measurement angle of the following Expression 4 is 60% or more;
    Measurement angle = arcsin (refractive index of medium in contact with a surface of the transparent plate opposite to the electro-optical function layer side / refractive index of the transparent plate) Expression 4
  The transparent plate has an average internal transmittance of 80% or more in a wavelength range of 400 nm to 700 nm at an optical path length of 50 mm.
  Structure.   The structure according to claim 1, wherein the transparent plate is glass. A dynamic shear storage modulus (G ′) at 35 ° C. and 1 Hz of the optical bonding layer is 1.0 × 10 ⁵ Pa or less;
The structure according to claim 1. The ratio of the coefficient of thermal expansion between the transparent substrate and the transparent plate bonded via the optical bonding layer is 5 or less,
The structure according to claim 1 . A structure according to any one of claims 1 to 6,
A light source disposed on one end surface of the transparent plate provided on the structure . The transparent display according to claim 7, wherein a transmittance of a transparent portion of the structure is 70% or more. A structure according to any one of claims 1 to 6,
A light source disposed on one end surface of the transparent plate provided on the structure . The lighting device according to claim 9, wherein the transmittance of the transparent portion of the structure is 70% or more. A structure according to any one of claims 1 to 6,
An information display device comprising: a light source disposed on one end surface of the transparent plate provided on the structure . The information display device according to claim 11, wherein the transmittance of the transparent portion of the structure is 70% or more. LCD panel,
A liquid crystal display device comprising the lighting device according to claim 9 .

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