Liquid crystal cell and liquid crystal display device

Abstract

To provide a liquid crystal cell and a liquid crystal display device exhibiting high contrast even in an ultraviolet region.SOLUTION: A liquid crystal cell includes a pair of substrates disposed to face each other, at least one of which includes a transparent electrode film, and a liquid crystal layer disposed between the pair of substrates. The liquid crystal in the liquid crystal layer has a birefringence Δn365 of 0.05 or more and 0.50 or less at 365 nm. The thickness of the liquid crystal layer is 1 μm or more and 15 μm or less. In a state where absorption axes of a pair of measurement polarization plates with a polarizing function in the ultraviolet region are disposed opposite to each other outside the liquid crystal cell, the absolute value of the difference between the transmittance when voltage is not applied and the transmittance when voltage is applied, which are calculated by measuring the transmittance at 365 nm, is 10% or more and 100% or less. The measurement polarization plate has a polarization degree of 99% or more at 365 nm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a liquid crystal cell and a liquid crystal display device, and more particularly to a liquid crystal cell capable of providing a liquid crystal display device exhibiting high contrast in the ultraviolet region, and a liquid crystal display device using the same. [Background technology]

[0002] Liquid crystal displays (LCDs), one of the most representative display devices, are becoming more and more popular every year because they are thin, lightweight, and consume little power. The basic structure of a liquid crystal display device is a light source called a backlight, two polarizing plates that allow light to pass in only one direction, and a liquid crystal cell filled with liquid crystal material that is placed between the two polarizing plates.

[0003] A liquid crystal display device having a twisted nematic (TN) type liquid crystal cell is known as one of the display modes of liquid crystal display devices. In addition to the basic structure described above, such liquid crystal display devices can also have an additional optical member disposed between the liquid crystal cell and the polarizing plate in order to improve optical characteristics such as a wider viewing angle.

[0004] Patent Document 1 discloses a liquid crystal display device including a TN type liquid crystal cell, a pair of polarizing plates arranged on the outside of the liquid crystal cell, and first and second retardation plates arranged between the liquid crystal cell and each polarizing plate. Patent Document 2 discloses a color liquid crystal display device including a birefringence effect type liquid crystal cell, a pair of polarizing plates arranged on the outside of the liquid crystal cell, and a retardation plate arranged between the pair of polarizing plates. Patent Document 3 discloses a liquid crystal display device including a TN type liquid crystal cell, a pair of polarizing plates arranged on the outside of the liquid crystal cell, and at least one optical compensation sheet arranged between the liquid crystal cell and each polarizing plate. Patent Document 4 discloses a TN type liquid crystal display device having a structure in which both sides of a liquid crystal cell are sandwiched between first and second polarizing plates from the viewing side, which are made of a polarizing film and two polarizing plate protective films sandwiching the polarizing film.

[0005] Also, among liquid crystal display devices using color filters, there are known liquid crystal display devices equipped with a liquid crystal cell having a so-called multi-gap structure in which the thickness of the liquid crystal layer differs for each color of the color filter. Patent Document 5 discloses a TN mode liquid crystal display device equipped with a liquid crystal cell including a color filter and a liquid crystal layer having a predetermined multi-gap structure, and a polarizing plate disposed on at least one side of the liquid crystal cell.

[0006] Thus, although Patent Documents 1 to 5 all disclose the design of liquid crystal display devices having TN type liquid crystal cells, the TN type liquid crystal cells are designed using liquid crystal cells that utilize light in the visible range, and no consideration is given to the design of liquid crystal cells that utilize light in the ultraviolet range.

[0007] As a liquid crystal display using ultraviolet light, a fluorescent liquid crystal display using ultraviolet light emitting diodes (LEDs) is known. As such a fluorescent liquid crystal display, Non-Patent Document 1 discloses a method of adding a fluorescent dye to a liquid crystal cell and emitting light by the alignment of the liquid crystal. Since the liquid crystal display disclosed in Non-Patent Document 1 is a display for emitting light from a fluorescent dye contained in the liquid crystal cell, there is no particular problem with the design of the liquid crystal cell as long as the fluorescent dye can be aligned. On the other hand, in recent liquid crystal display devices, higher performance is required, and it is particularly preferable that the display device has a high contrast. Non-Patent Document 1 does not mention the display contrast in the ultraviolet region. Therefore, there is a demand for the development of a liquid crystal display device that shows a high contrast by using light in the ultraviolet region. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 6-167707 [Patent Document 2] Japanese Patent Application Publication No. 6-175125 [Patent Document 3] JP 2007-171815 A [Patent Document 4] International Publication No. 2008 / 075538 [Patent Document 5] JP 2010-107941 A [Non-patent literature]

[0009] [Non-Patent Document 1] IDW98, P25-28, R.YAMAGUCHI et al. [Non-Patent Document 2] Journal of Liquid Crystal Society, Vol. 6, No. 3, 2002, p. 297 Summary of the Invention [Problem to be solved by the invention]

[0010] In view of the above circumstances, an object of the present invention is to provide a liquid crystal cell and a liquid crystal display device that exhibit high contrast even in the ultraviolet region. [Means for solving the problem]

[0011] As a result of intensive research by the present inventors to achieve this object, in a liquid crystal cell containing a liquid crystal having a predetermined birefringence at a wavelength of 365 nm, the cell gap (thickness of the liquid crystal layer), and further, the difference in transmittance at 365 nm when a voltage is applied and when no voltage is applied, measured in a state in which a pair of polarizing plates having a polarizing function in the ultraviolet region are arranged opposite each other on the outside of the liquid crystal cell, have an effect on the contrast of the liquid crystal cell in the ultraviolet region. Based on this finding, the present inventors have found that a liquid crystal cell and a liquid crystal display device exhibiting high contrast in the ultraviolet region can be obtained by controlling the thickness of the liquid crystal layer and the range of the difference in transmittance based on the presence or absence of application of a voltage at 365 nm.

[0012] That is, the gist of the present invention is as follows. [1] A liquid crystal cell comprising a pair of substrates arranged opposite each other, at least one of which has a transparent electrode film, and a liquid crystal layer disposed between the pair of substrates, The liquid crystal contained in the liquid crystal layer has a birefringence Δn of 0.05 or more and 0.50 or less at 365 nm. 365 having The thickness of the liquid crystal layer is 1 μm or more and 15 μm or less, The absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied, calculated by measuring the transmittance at 365 nm in a state in which the absorption axes of a pair of measurement polarizing plates having a polarizing function in the ultraviolet region are disposed opposite each other on the outside of the liquid crystal cell, is 10% or more and 100% or less, and A liquid crystal cell, wherein the measurement polarizing plate has a polarization degree of 99% or more at 365 nm. [2] A pair of measurement polarizing plates having a polarizing function in the ultraviolet region are arranged so that their absorption axes are perpendicular to each other on the outside of the liquid crystal cell, and the transmittance of each wavelength in the range of 300 nm to 400 nm is measured. The absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied is 10% or more and 100% or less, and The liquid crystal cell according to the above-mentioned [1], wherein the measurement polarizing plate has a polarization degree of 99% or more in the ultraviolet region. [3] The liquid crystal cell according to the above [1], wherein the absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied, calculated by measuring the transmittance at 365 nm when a voltage is applied is 4 V, is 10% or more and 100% or less. [4] The liquid crystal cell according to any one of the above [1] to [3], wherein the liquid crystal layer satisfies the following relational formula (I):

number

number

[10] The polarizing light-emitting plate has a polarizing function at 365 nm, and The liquid crystal display device according to the above [8] or [9], wherein the polarized light-emitting plate has an axis having a transmittance of 10% or more and 99% or less when polarized light of 365 nm is incident, and an axis having a transmittance of 0% or more and 5% or less.

[11] The liquid crystal display device according to the above [8], wherein the polarizing plate has a luminous efficiency-corrected single transmittance Ys of 60% or more.

[12] The liquid crystal display device according to any one of the above [8] to

[11] , wherein the polarized light-emitting plate has a luminous efficiency-corrected single transmittance Ys of 60% or more.

[13] A liquid crystal cell according to any one of the above [1] to [6], and a visible light polarizing plate having a single transmittance Ts of 50% or less in the range of 400 nm to 700 nm, The liquid crystal display device, wherein the visible region polarizing plate is disposed on at least one outer side of the liquid crystal cell.

[14] The liquid crystal display device according to the above

[13] , wherein the visible light polarizing plate has a polarization degree of 99% or more in the range of 400 nm or more and 700 nm or less.

[15] The polarizing plate has a single transmittance Ts of 20% or more at any wavelength in the range of at least 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the range of 300 to 400 nm when the two polarizing plates are arranged perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, the transmission axis of the polarizing plate and the axis along which the twisted nematic liquid crystal is oriented in one of the pair of substrates when no voltage is applied are arranged parallel to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented in the other of the pair of substrates when no voltage is applied are disposed perpendicular to each other; The liquid crystal display device according to the above item [8], wherein liquid crystal display is possible by incident light within a wavelength range of 300 to 400 nm from the polarizing plate side.

[16] The polarizing plate has a single transmittance Ts of 20% or more at any wavelength in the range of at least 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the range of 300 to 400 nm when the two polarizing plates are arranged perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, a transmission axis of the polarizing plate and an axis along which the twisted nematic liquid crystal is oriented in one of the pair of substrates when no voltage is applied are disposed perpendicular to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented when no voltage is applied on the other of the pair of substrates are arranged parallel to each other; The liquid crystal display device according to the above item [8], wherein liquid crystal display is possible by incident light within a wavelength range of 300 to 400 nm from the polarizing plate side.

[17] The polarizing plate has a single transmittance Ts of 20% or more at any wavelength in the range of at least 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the range of 300 to 400 nm when the two polarizing plates are arranged perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, the transmission axis of the polarizing plate and the axis along which the twisted nematic liquid crystal is oriented in one of the pair of substrates when no voltage is applied are arranged parallel to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented when no voltage is applied on the other of the pair of substrates are arranged parallel to each other; The liquid crystal display device according to the above item [8], wherein liquid crystal display is possible by incident light within a wavelength range of 300 to 400 nm from the polarizing plate side.

[18] A liquid crystal cell according to any one of [1] to [6] above, which can be controlled, with or without application of voltage, to a transmissive type showing a transmittance at 365 nm of 40% or more and 100% or less, or a non-transmissive type showing a transmittance at 365 nm of 0% or more and 10% or less.

[19] A liquid crystal display device comprising the liquid crystal cell according to

[18] above. Effect of the Invention

[0013] According to an aspect of the present invention, a liquid crystal cell includes a pair of substrates, at least one of which has a transparent electrode film, disposed opposite each other, and a liquid crystal layer disposed between the pair of substrates. The liquid crystal contained in the liquid crystal layer has a birefringence Δn of 0.05 to 0.50 at a wavelength of 365 nm. 365 and the thickness of the liquid crystal layer is 1 μm or more and 15 μm or less. In such a liquid crystal cell, a pair of measurement polarizers having a polarization degree of 99% or more at 365 nm as polarizers having a polarizing function in the ultraviolet region are arranged in parallel with each other on the outside of the liquid crystal cell with their absorption axes facing each other, and the absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied is calculated to be 10% or more and 100% or less. Since the transmittance of such a liquid crystal cell is significantly different between when a voltage is applied and when no voltage is applied at wavelengths in the ultraviolet region, a liquid crystal cell exhibiting high contrast in the ultraviolet region and a liquid crystal display device using the same can be provided. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of a liquid crystal cell according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing one embodiment of a liquid crystal display device according to the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing another embodiment of the liquid crystal display device according to the present invention. [Figure 4]FIG. 4 shows the spectral data of the single transmittance Ts and crossed transmittance Tc at each wavelength of the ultraviolet polarizing plates A to C produced in the examples. [Figure 5A] FIG. 5A shows the spectral data of the single transmittance Ts and crossed transmittance Tc at each wavelength of polarized light-emitting plates A to C produced in the examples. [Figure 5B] FIG. 5B shows the spectral data of the polarized light incident transmittance Ky and Kz used in calculating the parallel transmittance (Tp) at each wavelength of the polarized light emitting plates A to C produced in the examples. [Figure 6] FIG. 6 is a graph showing the degree of polarization (DOP) at each wavelength of the polarized light-emitting plates A to C produced in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The liquid crystal cell and liquid crystal display device of the present invention will be described below with reference to the drawings. Note that the following embodiments are merely representative embodiments used to specifically explain the present invention, and various embodiments may be adopted within the scope of the present invention.

[0016] In the following description, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0017] <Liquid crystal cell> As shown in FIG. 1, the liquid crystal cell according to the present embodiment includes a pair of substrates 1 arranged opposite to each other and a liquid crystal layer 5 disposed between the pair of substrates. At least one of the pair of substrates 1 has a transparent electrode film 2 such as ITO (Indium Tin Oxide), and a voltage is applied to the liquid crystal cell through the transparent electrode film 2. The transparent electrode film 2 is formed on the surfaces of both substrates 1 facing each other, that is, on the inner surfaces of the liquid crystal cell, and when both substrates 1 have the transparent electrode film 2, each transparent electrode film 2 is formed to face each other. In addition, an alignment film 3 for aligning the liquid crystal may be formed on the pair of substrates 1, or on the transparent electrode film 2 formed on one or both substrates 1. The alignment film 3 may be subjected to an alignment treatment such as a photoalignment treatment or a rubbing treatment as necessary, and such an alignment film 3 is formed using a material such as polyimide, polyamide, polysiloxane, or polyvinyl alcohol. In this way, a liquid crystal cell is produced that includes a conductive substrate 4 on which the alignment film 3 is formed on the substrate 1 having the transparent electrode film 2.

[0018] There are various driving modes of the liquid crystal cell, such as TN type, STN type, VA type, IPS type, OCB type, ECB type, etc., but the TN type liquid crystal cell is preferred. In the TN type liquid crystal cell, when no voltage is applied, the alignment direction of the liquid crystal molecules adjacent to one substrate is twisted by 90° with respect to the alignment direction of the liquid crystal molecules adjacent to the other substrate. With the application of voltage, the liquid crystal molecules gradually rise vertically, thereby changing from a bright (white) display to a dark (black) display. The TN type liquid crystal cell may be an STN type liquid crystal cell manufactured so that the twist angle of the alignment of the liquid crystal molecules when no voltage is applied is 180° to 270° between the two substrates.

[0019] [substrate] The substrate 1 is not particularly limited as long as it is transparent, and may be, for example, a glass substrate or a plastic substrate. The plastic substrate may be a film or a sheet. Examples of materials for the plastic substrate include resins such as polyethylene, polypropylene, polyester, polyethylene terephthalate, polyethylene naphthalate, polyvinyl alcohol, polyvinyl chloride, polyamide, polyimide, polyamideimide, polyethersulfone, polyphenylene sulfide, polycarbonate, and triacetyl cellulose. In particular, if the plastic substrate is a flexible substrate made of a flexible resin, the plastic substrate can be bent into any shape for use.

[0020] [Liquid crystal layer] The liquid crystal contained in the liquid crystal layer 5 has a birefringence Δn of 0.05 to 0.50 at 365 nm, preferably 0.09 to 0.20. 365 The birefringence Δn 365 Since the Δn is 0.05 or more and 0.50 or less, a liquid crystal cell with high contrast can be provided when a polarizing plate having a polarizing function at 365 nm is provided in the liquid crystal cell. In addition, as for the liquid crystal material, the liquid crystal contained in the liquid crystal cell is preferably a twisted nematic liquid crystal (TN type liquid crystal). By using the twisted nematic liquid crystal, a liquid crystal cell with high contrast can be provided at low cost. When using twisted nematic liquid crystal, it is preferable that the pair of substrates each have an alignment film arranged opposite to each other so that the alignment directions are perpendicular to each other by a rubbing treatment or the like, and the twisted nematic liquid crystal sandwiched between the alignment films is sealed with a predetermined twist angle depending on the rubbing direction of the two alignment films. Examples of such twisted nematic liquid crystal include, but are not limited to, biphenyl-based liquid crystal, phenylcyclohexane-based liquid crystal, dicyclohexane-based liquid crystal, tolan-based liquid crystal, and terphenyl-based liquid crystal. In addition, examples of commercially available products of such twisted nematic liquid crystal include, for example, ZLI-1083 (Δn 365 :0.150), ZLI-2471(Δn 365 :0.170), ZLI-4792(Δn 365:0.130), ZLI-5092(Δn 365 :0.096), MLC-2053(Δn 365 :0.321) etc.

[0021] The thickness of the liquid crystal layer (cell gap) is controlled to 1 μm or more and 15 μm or less, preferably 2 μm or more and 11 μm or less, and more preferably 4 μm or more and 10 μm or less. When the thickness of the liquid crystal layer is 1 μm or more and 15 μm or less, and the birefringence Δn 365 When the ratio is 0.05 or more and 0.50 or less, a liquid crystal cell having high transmittance in the ultraviolet region can be provided, and thus a liquid crystal cell exhibiting high contrast in the ultraviolet region, particularly at a wavelength of 365 nm, can be provided.

[0022] The thickness of the liquid crystal layer preferably satisfies the following relational expression (I), which is a modification of the Gooch-Tarry equation into a relational expression for the thickness of the liquid crystal layer in a TN-type liquid crystal cell: From the relational expression (I) below, it is possible to calculate the optimum range of the thickness of the liquid crystal layer that can provide a liquid crystal cell that exhibits high contrast at 365 nm.

[0023]

number

[0024] In the above formula (I), u is any one of √3, √15, √35, √63, or √99, and Δn 365 indicates the birefringence of the liquid crystal at 365 nm, and d indicates the thickness (m) of the liquid crystal layer. The thickness d of the liquid crystal layer is generally also called the cell gap. Non-Patent Document 2 describes an optimal design method that takes into consideration the thickness of the liquid crystal layer of a TN-type liquid crystal cell. When this design method is applied so that the optimal thickness value for a liquid crystal cell that functions at 365 nm can be calculated, formula (I) is obtained. In the above formula (I), 0.8 and 1.2 represent the calculated optimal value of the liquid crystal layer thickness (u×365×10 -9 / (2×△n 365)) represents the upper and lower limits of the thickness of the liquid crystal layer that can be used in the liquid crystal cell according to the present embodiment. In this way, when the thickness d of the liquid crystal layer calculated by the above formula (I) is within the range of 0.8 to 1.2 times the optimum value of the calculated thickness of the liquid crystal layer, a liquid crystal cell exhibiting high contrast at 365 nm can be provided. The thickness d of the liquid crystal layer calculated by the above formula (I) is preferably within the range of 0.85 to 1.15 times the optimum value of the calculated thickness of the liquid crystal layer, more preferably within the range of 0.90 to 1.10 times, and even more preferably within the range of 0.95 to 1.05 times.

[0025] The relationship between the birefringence of liquid crystal in the ultraviolet range and the birefringence of liquid crystal in the visible range is expressed as the birefringence Δn 365 It is preferable that the liquid crystal having the above formula satisfies the relational formula (II) below. By using a liquid crystal satisfying the relational formula (II) below in a liquid crystal cell of a liquid crystal display device in which a pair of polarizing plates having a polarizing function in the ultraviolet region are arranged, a liquid crystal display device with high contrast in the ultraviolet region can be obtained. In addition, by using a liquid crystal satisfying the relational formula (II) below in a liquid crystal cell of a liquid crystal display device in which a polarized light-emitting plate described below is arranged, the luminous intensity of polarized luminescence in the bright state can be increased, and further the amount of luminescence can be significantly reduced in the extinction state, so that a liquid crystal display device with high contrast between luminescence and extinction can be obtained.

[0026]

number

[0027] In the above formula (II), Δn 365 is the birefringence of the liquid crystal at 365 nm, and Δn 640 represents the birefringence of the liquid crystal at 640 nm. In the above formula (II), Δn 365 / Δn 640 The value range is preferably from 1.0 to 1.5, and more preferably from 1.1 to 1.4.

[0028] [Optical properties of liquid crystal cells] (Transmittance in the ultraviolet range) In the light transmittance of the liquid crystal cell according to the present embodiment, the greater the difference between the transmittance at high transmission and the transmittance at extinction of ultraviolet light, the higher the contrast of the liquid crystal cell can be provided. The transmittance in the ultraviolet region is measured by placing a measurement polarizing plate having a polarizing function in the ultraviolet region on the outside of the liquid crystal cell. In the liquid crystal cell according to the present embodiment, for example, the greater the difference between the transmittance at high transmission and the transmittance at extinction, the greater the difference between the transmittance at high transmission and the transmittance at extinction, which indicates that a liquid crystal cell showing high contrast can be obtained. In the liquid crystal cell according to the present embodiment, a polarizing plate having a polarizing function in the ultraviolet region and having a polarization degree of 99% or more at 365 nm is used as the measurement polarizing plate. The absolute value of the difference between the transmittance at 365 nm when no voltage is applied and the transmittance at 365 nm when a voltage is applied (for example, a voltage of 4 V), obtained by measuring in a state where each absorption axis of such a measurement polarizing plate is arranged perpendicularly facing the outside of the liquid crystal cell, is 10% or more and 100% or less, more preferably 30% or more and 95% or less, and even more preferably 60% or more and 90% or less. Since the transmittance at 365 nm when a voltage is applied and when no voltage is applied is different, a liquid crystal cell showing high contrast at a wavelength of 365 nm can be provided. Note that when no voltage is applied, it means the time of extinction, and when a voltage is applied, it means the time of high transmission, and the difference between the transmittance at 365 nm when no voltage is applied and the transmittance at 365 nm when a voltage is applied is exemplified as the contrast, but this is not limited. For example, depending on the design of the liquid crystal and the applied voltage, the transmittance at the time of extinction may be shown when a specific voltage is applied, not when no voltage is applied, and the transmittance at the time of high transmission may be shown when no voltage is applied. In any case, a high-contrast liquid crystal cell is provided by having a large difference in transmittance between specific voltages (including voltages where one side is 0 V). However, a design that exhibits extinction when no voltage is applied and high transmittance when voltage is applied is preferable because it is similar to a general liquid crystal cell and can be manufactured inexpensively.

[0029] In the liquid crystal cell according to the present embodiment, when a polarizing plate having a polarizing function in the ultraviolet region and a polarization degree of 99% or more in the ultraviolet region is used as a measurement polarizing plate, the absolute value of the difference between the transmittance in the range of 300 nm to 400 nm when no voltage is applied and the transmittance in the range of 300 nm to 400 nm when a voltage is applied (for example, a voltage of 4 V) obtained by measuring the absorption axes of a pair of measurement polarizing plates arranged perpendicularly facing each other on the outside of the liquid crystal cell is preferably 10% to 100%, more preferably 30% to 95%, and even more preferably 50% to 90%. By using a liquid crystal cell showing such a difference in transmittance, a liquid crystal cell showing high contrast in a wide region from ultraviolet to near ultraviolet visible can be provided.

[0030] (Transmittance in the visible range) The liquid crystal cell not only exhibits a predetermined light transmittance in the ultraviolet region, but also exhibits light transmittance in the visible region, thereby imparting transparency and visibility to the liquid crystal cell in the visible region. The transmittance in the visible region is measured by using a polarizing plate having a polarizing function in the ultraviolet region and a polarization degree of 99% or more in the ultraviolet region as a measurement polarizing plate and disposing this measurement polarizing plate outside the liquid crystal cell. In the liquid crystal cell according to this embodiment, the luminosity-corrected transmittance Ys in the range of 380 nm to 780 nm, which is obtained by measuring a pair of measurement polarizing plates having a polarizing function in the ultraviolet region and a polarization degree of 99% or more in the ultraviolet region, disposed opposite each other on the outside of the liquid crystal cell, is preferably 50% to 99.9%, more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. Here, the luminosity-corrected single transmittance Ys is a transmittance obtained by correcting the luminosity of the single transmittance Ts measured at a predetermined wavelength interval (dλ) in the wavelength region of 380 to 780 nm in the visible range according to JIS Z 8722:2009. Specifically, the single transmittance Ts is substituted into the following formula (III) for calculation. In the following formula (III), Pλ represents the spectral distribution of standard light (C light source), τλ represents the 2-degree visual field color matching function, and the single transmittance Ts means the transmittance obtained by measuring each transmittance in the wavelength region of 380 to 780 nm in a single polarizing plate having a polarizing function in the ultraviolet range.

[0031]

number

[0032] <Liquid crystal display device> The liquid crystal display device according to this embodiment includes the above-mentioned liquid crystal cell and two polarizing plates on the outside of the liquid crystal cell. As shown in FIG. 2, the liquid crystal display device according to this embodiment includes the above-mentioned liquid crystal cell and a pair of polarizing plates 6 having a polarizing function in the ultraviolet region, and the pair of polarizing plates 6 are arranged opposite each other on the outside of the liquid crystal cell. As in FIG. 1, the liquid crystal cell includes a pair of substrates 1 arranged opposite each other and a liquid crystal layer 5 disposed between the pair of substrates, and at least one of the pair of substrates 1 has a transparent electrode film 2 such as ITO (Indium Tin Oxide). An alignment film 3 may be formed on the pair of substrates 1 or the transparent electrode film 2 using a material such as polyimide, polyamide, polysiloxane, or polyvinyl alcohol. In this way, a liquid crystal display device is fabricated in which the polarizing plates 6 having a polarizing function in the ultraviolet region are arranged opposite each other on the outside of the liquid crystal cell including the conductive substrate 4.

[0033] The polarizing plate used in the liquid crystal display device as shown in FIG. 2 has a degree of polarization of 70% or more at 365 nm, and preferably has a specific degree of polarization and crossed transmittance at 365 nm as optical characteristics of such a polarizing plate. The degree of polarization at 365 nm is preferably 70 to 100%, more preferably 90 to 100%, even more preferably 98 to 100%, and particularly preferably 99 to 100%. The transmittance at 365 nm obtained by measuring in a state in which the transmission axes of a pair of polarizing plates are arranged perpendicular to each other, that is, the crossed transmittance (Tc), is preferably 0% or more and 10% or less, more preferably 0% or more and 1.0% or less, and even more preferably 0.0001% or more and 0.3% or less. Since the liquid crystal display device includes a pair of polarizing plates having a predetermined degree of polarization at 365 nm and exhibiting a polarizing function in the ultraviolet region, and the liquid crystal cell exhibiting the above-mentioned high contrast, a liquid crystal display device exhibiting high contrast by utilizing ultraviolet light can be provided. Here, the orthogonal transmittance Tc at 365 nm is the spectral transmittance at 365 nm measured by stacking two polarizing plates, each having a polarizing function in the ultraviolet region, so that their transmission axes are perpendicular to each other, and can be measured, for example, using a spectrophotometer.

[0034] As shown in Fig. 3, the liquid crystal display device in another embodiment includes the above-mentioned liquid crystal cell, a polarizing plate 6 having a polarizing function in the ultraviolet region, and a polarizing light-emitting plate 7 that emits polarized light in the visible region when irradiated with light in the ultraviolet to near-ultraviolet visible region, for example, light of 365 nm. The polarizing plate 6 having a polarizing function in the ultraviolet region is disposed on the outer side of one of the pair of substrates 1 in the liquid crystal cell, and the polarizing light-emitting plate 7 is disposed on the outer side of the other of the pair of substrates 1 in the liquid crystal cell. As in Fig. 1, the liquid crystal cell includes a pair of substrates 1 arranged opposite each other and a liquid crystal layer 5 disposed between the pair of substrates, and at least one of the pair of substrates 1 has a transparent electrode film 2 such as ITO (Indium Tin Oxide). An alignment film 3 may be formed on the pair of substrates 1 or the transparent electrode film 2 using a material such as polyimide, polyamide, polysiloxane, or polyvinyl alcohol. In this manner, a liquid crystal display device is produced in which a polarizing plate 6 having a polarizing function in the ultraviolet range and a polarized light-emitting plate 7 are arranged facing each other on the outside of a liquid crystal cell having a conductive substrate 4.

[0035] The liquid crystal display device as shown in Fig. 3 includes a polarizing plate that exhibits polarization performance in the ultraviolet region, a polarized light-emitting plate that exhibits polarized light emission in the visible region when irradiated with ultraviolet light, and the liquid crystal cell that exhibits the above-mentioned high contrast, and therefore can provide a self-luminous liquid crystal display device that exhibits high contrast by utilizing light in the ultraviolet to near-ultraviolet visible region. The polarization degree of the polarizing plate that has a polarization function in the ultraviolet region is preferably 70% or more, more preferably 90% or more, even more preferably 99% or more, and particularly preferably 99.9% or more. In particular, when the polarizing plate has a polarization degree of 99% or more, a self-luminous liquid crystal display device that exhibits higher contrast can be provided.

[0036] A polarizing plate having a polarizing function in the ultraviolet region preferably has a luminosity-corrected single transmittance Ys of 60% or more, more preferably a luminosity-corrected single transmittance Ys of 70% or more and 99% or less, and even more preferably a luminosity-corrected single transmittance Ys of 80% or more and 99% or less. A polarizing plate having a luminosity-corrected single transmittance Ys of 60% or more is visually transparent, so that a self-luminous liquid crystal display device having such a polarizing plate is suitable for application to a transparent display. The luminosity-corrected single transmittance Ys can be calculated using the above formula (III).

[0037] In a self-luminous liquid crystal display device, the transmittance at 365 nm obtained by measuring two polarizing light-emitting plates arranged so that their transmission axes are perpendicular to each other, i.e., the orthogonal transmittance Tc, is preferably 0% or more and 10% or less, more preferably 0% or more and 1.0% or less, even more preferably 0% or more and 0.3% or less, even more preferably 0% or more and 0.1% or less, and particularly preferably 0% or more and 0.05% or less. When the polarizing light-emitting plate has an orthogonal transmittance Tc of 0% or more and 10% or less in the ultraviolet range, it is possible to suppress the transmission of polarized light in the ultraviolet range that has passed through a polarizing plate having a polarizing function in the ultraviolet range, and it is possible to provide a liquid crystal display device with a high amount of light emission, i.e., a high contrast, by utilizing the transmitted polarized light in the ultraviolet range. Here, the orthogonal transmittance Tc at 365 nm is the spectral transmittance at 365 nm measured by overlapping two polarizing light-emitting plates so that their transmission axes are perpendicular to each other, and can be measured using, for example, a spectrophotometer.

[0038] The polarizing light-emitting plate has a polarizing function at 365 nm, and when polarized light at 365 nm is incident on the polarizing light-emitting plate, the transmittance of the axis showing the lowest transmittance is preferably 0% to 10%, more preferably 0% to 1.0%, and even more preferably 0% to 0.1%. By having the transmittance of the axis showing the lowest transmittance be 0% to 10%, a liquid crystal display device having high light-emitting properties can be provided.

[0039] In addition, it is preferable that the polarizing light-emitting plate has a polarizing function at 365 nm, and has an axis with a transmittance of 10% to 99% and an axis with a transmittance of 0% to 5% when polarized light at 365 nm is incident. This increases the difference between the axis that emits strong light and the axis that emits weak light, and a high-contrast liquid crystal display device can be realized. In order to realize a liquid crystal display device with a higher contrast, the polarizing light-emitting plate preferably has an axis with a transmittance of 60% to 99% and an axis with a transmittance of 0 to 1.0%, more preferably has an axis with a transmittance of 70% to 99% and an axis with a transmittance of 0 to 0.5%, and even more preferably has an axis with a transmittance of 80% to 99% and an axis with a transmittance of 0 to 0.1%.

[0040] The polarized light-emitting plate preferably has a luminous-corrected single transmittance Ys of 60% or more, more preferably 70% to 99%, even more preferably 80% to 99%, and particularly preferably 90% to 99%. A polarized light-emitting plate having a luminous-corrected single transmittance Ys of 60% or more is visually transparent, and thus a self-luminous liquid crystal display device including such a polarized light-emitting plate is suitable for application to a transparent display. The luminous-corrected single transmittance Ys can be calculated using the above formula (III).

[0041] In another embodiment, the liquid crystal display device includes the above-mentioned liquid crystal cell and a visible region polarizing plate having a single transmittance Ts of 50% or less in the range of 400 nm to 700 nm, and the visible region polarizing plate is disposed on at least one outer side of the liquid crystal cell. Such a visible region polarizing plate has a polarization degree of 99% or more and 100% or less in the range of 400 nm to 700 nm, for example. By providing a polarizing plate having a high polarization degree in the wavelength range of 400 nm to 700 nm in the liquid crystal display device, a liquid crystal display device showing high contrast in the visible region can be provided. In addition, when the liquid crystal display device includes a polarizing light-emitting plate on one outer side of the liquid crystal cell, the polarizing light-emitting plate emits polarized light in the visible region of 400 to 700 nm or a part thereof, so that a preferred embodiment includes a polarizing plate for the visible region on the other outer side of the liquid crystal cell as a polarizing plate for controlling the emission. The visible polarizing plate only needs to have a polarizing function in the wavelength region of 400 to 700 nm, and may also have a polarizing function at wavelengths other than the wavelength region of 400 to 700 nm.

[0042] In a self-luminous liquid crystal display device, by controlling the positional relationship between the polarizing plate and the polarizing light-emitting plate having a polarizing function in the ultraviolet region that shows a predetermined optical characteristic more strictly, a high-brightness light-emitting liquid crystal display device or a high-contrast light-emitting liquid crystal display device can be provided. In the high-brightness light-emitting liquid crystal display device according to this embodiment, the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least a region of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the region of 300 to 400 nm when two polarizing plates having a polarizing function in the ultraviolet region are arranged to be perpendicular to each other. In addition, the polarizing light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in the region of 300 to 400 nm. As the liquid crystal contained in the liquid crystal cell, a twisted nematic liquid crystal (TN type liquid crystal) is used. The transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and the axis along which the TN type liquid crystal is oriented on one of the pair of substrates when no voltage is applied are arranged parallel to each other. On the other hand, the absorption axis of the polarizing light-emitting plate and the axis along which the TN type liquid crystal is oriented on the other of the pair of substrates when no voltage is applied are arranged perpendicular to each other. In such a high brightness light-emitting type liquid crystal display device, liquid crystal display is possible by incident light in the 300 to 400 nm region from the polarizing plate side having a polarizing function in the ultraviolet region.

[0043] The high-brightness light-emitting type liquid crystal display device is configured in the order of a polarizing plate having a polarizing function in the ultraviolet region / TN type liquid crystal cell / polarizing light-emitting plate, and the transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and the absorption axis of the polarizing light-emitting plate have a predetermined positional relationship with the alignment axis of the TN type liquid crystal contained in the liquid crystal layer aligned on each substrate of the liquid crystal cell. In this configuration, the axis of the polarized light transmitted through the polarizing plate having a polarizing function in the ultraviolet region coincides with the absorption axis of the polarizing light-emitting plate. This allows the transmitted polarized light to be efficiently converted into light emission, providing a high-brightness self-luminous liquid crystal display device. The single transmittance Ts and crossed transmittance Tc are measured by the above-mentioned method.

[0044] In a liquid crystal display device according to an embodiment of a high-contrast light-emitting type, the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least a region of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the region of 300 to 400 nm in a state where two polarizing plates having a polarizing function in the ultraviolet region are arranged to be perpendicular to each other. The polarized light-emitting plate also has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in the region of 300 to 400 nm. Twisted nematic liquid crystal (TN type liquid crystal) is used as the liquid crystal contained in the liquid crystal cell. The transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and the axis along which the TN type liquid crystal is aligned when no voltage is applied on one of the pair of substrates are arranged perpendicular to each other. On the other hand, the absorption axis of the polarizing light-emitting plate and the axis along which the TN type liquid crystal is aligned when no voltage is applied on the other of the pair of substrates are arranged parallel to each other. In such a high-contrast light-emitting liquid crystal display device, liquid crystal display is possible by irradiating light in the 300 to 400 nm region from the polarizing plate side having a polarizing function in the ultraviolet region.

[0045] In another embodiment of the high-contrast light-emitting liquid crystal display device, the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least the range of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the range of 300 to 400 nm when two polarizing plates having a polarizing function in the ultraviolet region are arranged perpendicularly to each other. The polarized light-emitting plate also has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in the range of 300 to 400 nm. Twisted nematic liquid crystal (TN type liquid crystal) is used as the liquid crystal contained in the liquid crystal cell. The transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and the axis along which the TN type liquid crystal is aligned when no voltage is applied on one of the pair of substrates are arranged parallel to each other. On the other hand, the absorption axis of the polarizing light-emitting plate and the axis along which the TN type liquid crystal is aligned when no voltage is applied on the other of the pair of substrates are arranged parallel to each other. In such a high-contrast light-emitting liquid crystal display device, liquid crystal display is possible by irradiating light in the 300 to 400 nm region from the polarizing plate side having a polarizing function in the ultraviolet region.

[0046] Like the high brightness light emitting type liquid crystal display device, the high contrast light emitting type liquid crystal display device is also configured in the order of a polarizing plate having a polarizing function in the ultraviolet region / TN type liquid crystal cell / polarizing light emitting plate, and the transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and the absorption axis of the polarizing light emitting plate have a predetermined positional relationship with the alignment axis of the TN type liquid crystal contained in the liquid crystal layer aligned on each substrate of the liquid crystal cell. Even with this configuration, only the polarized light in the ultraviolet region that is transmitted from the polarizing plate having a polarizing function in the ultraviolet region and converted by 90° by the liquid crystal is absorbed by the light of the strong light emitting axis of the polarizing light emitting plate, i.e., the axis with strong absorption, so that a high contrast self-luminous type liquid crystal display device can be provided. The single transmittance Ts and crossed transmittance Tc are measured by the same method as described above.

[0047] (Transparency control structure) The liquid crystal cell may have a structure capable of controlling the transmission of ultraviolet light depending on the presence or absence of application of voltage. Such a liquid crystal cell can be controlled to a transmissive type showing a transmittance of 40% to 100% at 365 nm and a non-transmissive type showing a transmittance of 0% to 10% at 365 nm by application or absence of voltage. In the transmissive mode, the transmittance at 365 nm is preferably 60% or more, and in the non-transmissive mode, the transmittance at 365 nm is preferably 1% or less. A liquid crystal display device according to another embodiment includes such a liquid crystal cell and is capable of controlling the contrast based on application of voltage.

[0048] [Polarizing plate with polarizing function in the ultraviolet range] A polarizing plate having a polarizing function in the ultraviolet region is a polarizing plate that exhibits a polarizing function at least in the range of 300 to 400 nm, i.e., in the ultraviolet to near ultraviolet visible region or a part thereof, and may be transparent in the visible region or may have no polarization in the visible region. When the liquid crystal used in the liquid crystal cell is transparent in the visible region and the polarizing plate exhibiting a polarizing function in the ultraviolet region is transparent in the visible region, i.e., in the range of 400 to 780 nm, by using a polarizing plate having a polarizing function in the ultraviolet region, it is possible to provide a liquid crystal display device that functions as a liquid crystal display device in the ultraviolet to near ultraviolet visible region and has high transparency in appearance. Furthermore, when the liquid crystal used in the liquid crystal cell is transparent even in the visible range, satisfies the above formula (II), and the polarizing plate that exhibits polarizing function in the ultraviolet range also functions in the visible range, i.e., 400 to 780 nm, by using a polarizing plate that has polarizing function in the ultraviolet range, it is possible to provide a liquid crystal display device that functions in the entire wavelength range from the ultraviolet range to the visible range, i.e., 300 to 780 nm, or part of the wavelength range from 300 to 400 nm and part of the wavelength range from 400 to 780 nm.

[0049] (Polarizing plate for ultraviolet region) The ultraviolet polarizing plate has a function of converting ultraviolet light into polarized light, and has a high transmittance in the visible range, so that the transmitted visible light is almost not polarized or has a function of transmitting visible light with a significantly low degree of polarization. That is, the ultraviolet polarizing plate means a polarizing plate that has polarized light in the ultraviolet range and is transparent in the visible range. The ultraviolet polarizing plate is included in the polarizing plate having a polarizing function in the ultraviolet range. Such an ultraviolet polarizing plate is not particularly limited as long as it has the function, and for example, a polarizing plate having a polarizing film in which a water-soluble compound having an ultraviolet light polarizing function is stretched, for example, a polarizing film described in International Publication No. 2005 / 015275, etc. can be used. As such a water-soluble compound, for example, CI Direct Yellow 28, etc. can be mentioned. Specifically, the above-mentioned function means that when the luminosity-corrected single transmittance Ys in the visible range is 60% or more, the polarization degree in the ultraviolet range is 80% or more, preferably 90% or more, and more preferably 99% or more. In a particularly preferred embodiment, when the luminosity-corrected single transmittance Ys in the visible range is 80% or more, the degree of polarization in the ultraviolet range is 90% or more, and more preferably 99% or more.

[0050] [Polarizing plate] A polarized light-emitting plate has a function of absorbing ultraviolet light and emitting polarized light in the visible range. Such a polarized light-emitting plate is manufactured, for example, by adsorbing and orienting a polarized light-emitting dye, which is a material that emits light, on a substrate such as a film. In addition, the polarized light emitted directly from the polarized light-emitting plate can be emitted as light having polarization on a specific axis, i.e., linearly polarized light, but it can also be designed to emit light having elliptically polarized light or circularly polarized light in addition to a specific axis. The prescription can be realized by stretching a substrate impregnated with a polarized light-emitting dye not only uniaxially but also obliquely or in two or more axes, but it is preferable that the polarized light-emitting plate can emit a certain polarized light on one axis. The polarized light-emitting plate exhibits a function of emitting polarized light by converting the light energy of absorbed ultraviolet light into energy that emits light of another wavelength, i.e., light in the visible range. Therefore, cholesteric liquid crystals that reflect light of a certain wavelength as circularly polarized light at that wavelength are not included in the materials of polarized light-emitting plates that exhibit such characteristics.

[0051] (base material) The substrate of the polarized light-emitting plate contains a polarized light-emitting dye, which is a material that exhibits polarized light emission. Therefore, the substrate is preferably a film obtained by forming a film of a hydrophilic polymer capable of adsorbing the polarized light-emitting dye. Such hydrophilic polymers are not particularly limited, but examples thereof include polyvinyl alcohol resins, amylose resins, starch resins, cellulose resins, and polyacrylate resins. Among these resins, polyvinyl alcohol resins or derivatives thereof are preferable from the viewpoint of dyeability, processability, crosslinkability, and the like of the polarized light-emitting dye. Examples of polyvinyl alcohol resins or derivatives thereof include resins obtained by modifying either polyvinyl alcohol or its derivatives with olefins such as ethylene and propylene, or unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, and maleic acid. Among these, polyvinyl alcohol (PVA) films are preferable from the viewpoint of adsorption and orientation of the polarized light-emitting dye having dichroism. The substrate may be, for example, a commercially available product, or may be prepared by forming a film of a polyvinyl alcohol resin. The thickness of the substrate can be appropriately designed, but is preferably in the range of 5 μm to 150 μm, and more preferably in the range of 20 μm to 100 μm. For example, a polyvinyl alcohol resin is formed into a film as a substrate, and then a polarized light-emitting dye is added to the film as a material exhibiting polarized light emission. Thereafter, the obtained film is subjected to an orientation treatment such as stretching, and further to a boric acid treatment, a washing treatment, and a drying treatment, whereby a polarized light-emitting plate can be produced.

[0052] (Polarized luminescent dye) Next, the polarized light-emitting dye to be adsorbed and aligned on the substrate will be described. As a material for imparting polarized light-emitting properties to the polarized light-emitting plate, it is preferable to use a compound or a salt thereof that has at least one of a stilbene skeleton and a biphenyl skeleton in the molecule and does not have an azo group. If the polarized light-emitting dye has an azo group in the molecule, a high degree of polarization can be achieved like a conventional dye-based polarizing element, but the emission is absorbed by the azo group, and the amount of emitted light is significantly reduced. Therefore, it is preferable to use a compound or a salt thereof that does not have an azo group in the molecule as the polarized light-emitting dye. Such a polarized light-emitting dye exhibits fluorescence emission and has a dichroic ratio, so that polarized light emission is possible. Therefore, a polarized light-emitting dye that has at least one of a stilbene skeleton and a biphenyl skeleton in the molecule has excellent fluorescence emission properties and also has a high dichroic ratio when aligned on the substrate. These characteristics are due to the stilbene skeleton and the biphenyl skeleton, and it is possible to further introduce any substituent into each of the above skeletons to adjust various characteristics such as absorption wavelength, emission wavelength, various fastnesses such as light resistance, moisture resistance, and ozone gas resistance, solubility, etc. The introduction of this substituent can achieve a high polarization degree like a conventional dye-based polarizing plate depending on the type and position of the substituent, but the amount of emitted light may be significantly reduced. Therefore, in order to achieve excellent fluorescent emission characteristics and a high dichroic ratio, it is important to select the type and position of the substituent. The above polarized light-emitting dyes may be used alone or in combination of two or more types.

[0053] One of the compounds having a stilbene skeleton without an azo group is preferably a compound represented by formula (1) or a salt thereof. In formula (1), the groups L and M each independently represent a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amide group which may have a substituent, an ureido group which may have a substituent, an aryl group which may have a substituent, or a carbonyl group which may have a substituent, but are not limited thereto. The compound having a stilbene skeleton represented by formula (1) exhibits fluorescent emission, and can obtain dichroism by orientation. Since the luminescence characteristic is due to the stilbene skeleton, the substituent to which each group of the groups L and M can be bonded is not particularly limited as long as it does not have an azo group, and may be any substituent.

[0054] [ka]

[0055] Examples of the optionally substituted amino group include an unsubstituted amino group; alkylamino groups having 1 to 20 carbon atoms which may have a substituent, such as a methylamino group, an ethylamino group, an n-butylamino group, a tertiary butylamino group, an n-hexylamino group, a dodecylamino group, a dimethylamino group, a diethylamino group, a di-n-butylamino group, an ethylmethylamino group, or an ethylhexylamino group; an arylamino group which may have a substituent, such as a phenylamino group, a diphenylamino group, a naphthylamino group, or an N-phenyl-N-naphthylamino group; an alkylcarbonylamino group having 1 to 20 carbon atoms, which may have a substituent, such as a methylcarbonylamino group, an ethylcarbonylamino group, or an n-butylcarbonylamino group; an arylcarbonylamino group which may have a substituent, such as a phenylcarbonylamino group, a biphenylcarbonylamino group, or a naphthylcarbonylamino group; Examples of the alkylsulfonylamino group having 1 to 20 carbon atoms, such as a methylsulfonylamino group, an ethylsulfonylamino group, a propylsulfonylamino group, or an n-butylsulfonylamino group, and an arylsulfonylamino group which may have a substituent, such as a phenylsulfonylamino group or a naphthylsulfonylamino group. Among these, an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent, an arylcarbonylamino group which may have a substituent, an alkylsulfonylamino group having 1 to 20 carbon atoms, or an arylsulfonylamino group which may have a substituent are preferred.

[0056] An example of the carbonylamide group which may have a substituent is an N-methyl-carbonylamide group (-CONHCH 3 ), N-ethyl-carbonylamide group (-CONHC 2 H 5 ), N-phenyl-carbonylamide group (-CONHC 6 H 5 ) etc.

[0057] Examples of the alkyl group having 1 to 20 carbon atoms which may have a substituent include linear C alkyl groups such as a methyl group, an ethyl group, an n-butyl group, an n-hexyl group, an n-octyl group, and an n-dodecyl group. 1 -C 12 Branched chain C such as alkyl, isopropyl, sec-butyl, and tert-butyl groups 3 -C 10 Cyclic C such as alkyl, cyclohexyl, and cyclopentyl groups 3 -C 7 Among these, a linear or branched alkyl group is preferred, and a linear alkyl group is more preferred.

[0058] Examples of the vinyl group which may have a substituent include an ethenyl group, a styryl group, a vinyl group having an alkyl group, a vinyl group having an alkoxy group, a divinyl group, and a pentadiene group.

[0059] Examples of the amide group which may have a substituent include an acetamide group (-NHCOCH 3 ), benzamide group (-NHCOC 6 H 5 ) etc.

[0060] Examples of the ureido group which may have a substituent include a monoalkylureido group, a dialkylureido group, a monoarylureido group, and a diarylureido group.

[0061] Examples of the aryl group which may have a substituent include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and the like. 6 -C 12 It is an aryl group. The aryl group may be a 5- or 6-membered heterocyclic group containing 1 to 3 heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur atoms as ring-constituting atoms. Among such heterocyclic groups, a heterocyclic group containing an atom selected from a nitrogen atom and a sulfur atom as a ring-constituting atom is preferred.

[0062] Examples of the carbonyl group which may have a substituent include a methylcarbonyl group, an ethylcarbonyl group, an n-butyl-carbonyl group, and a phenylcarbonyl group.

[0063] The above-mentioned substituents are not particularly limited, but examples thereof include a nitro group, a cyano group, a hydroxyl group, a sulfonic acid group, a phosphoric acid group, a carboxyl group, a carboxyalkyl group, a halogen atom, an alkoxy group, and an aryloxy group.

[0064] Examples of the carboxyalkyl group include a methylcarboxyl group and an ethylcarboxyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Examples of the aryloxy group include a phenoxy group and a naphthoxy group.

[0065] Examples of the compound represented by formula (1) include the Kayaphor series (manufactured by Nippon Kayaku Co., Ltd.), the Whitex series such as Whitex RP (manufactured by Sumitomo Chemical Co., Ltd.), etc. Examples of the compound represented by formula (1) are shown below, but are not limited thereto.

[0066] [Compound example 1] [ka]

[0067] As another compound having a stilbene skeleton without an azo bond, a compound represented by the following formula (2) or formula (3) or a salt thereof is preferable. By using these compounds, a polarized light-emitting element that emits brighter white light can be obtained. Furthermore, the compounds represented by the following formulas (2) and (3) also exhibit fluorescence due to the stilbene skeleton, and dichroism can be obtained by orientation.

[0068] [ka]

[0069] In the above formula (2), the group X represents a nitro group or an amino group which may have a substituent. The amino group which may have a substituent is defined similarly to the amino group in the above formula (1) which may have a substituent, and is preferably an alkylcarbonylamino group having 1 to 20 carbon atoms which may have a substituent, an arylcarbonylamino group which may have a substituent, an alkylsulfonylamino group having 1 to 20 carbon atoms, or an arylsulfonylamino group which may have a substituent. Among these, the group X is preferably a nitro group.

[0070] In the above formula (2), the group R represents a hydrogen atom, a halogen atom such as a chlorine atom, a bromine atom, or a fluorine atom, a hydroxyl group, a carboxyl group, a nitro group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an amino group which may have a substituent. The alkyl group which may have a substituent is defined in the same manner as the alkyl group having 1 to 20 carbon atoms which may have a substituent in the above formula (1). The alkoxy group which may have a substituent is preferably a methoxy group, an ethoxy group, or the like. The amino group which may have a substituent is defined in the same manner as the amino group which may have a substituent in the above formula (1), and is preferably a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a phenylamino group, or the like. The group R may be bonded to any carbon atom of the naphthalene ring in the naphthotriazole ring, but is preferably bonded to the 3rd, 5th, or 8th position when the carbons condensed with the triazole ring are the 1st and 2nd positions.

[0071] In the above formula (2), n is an integer of 0 to 3, and is preferably 1. In addition, in the above formula (2), -(SO 3 H) may be bonded to any carbon atom of the naphthalene ring in the naphthotriazole ring. 3 With respect to the positions of H) on the naphthalene ring, assuming that the carbon atom condensed with the triazole ring is the 1st or 2nd position, if n=1, it is preferably the 4th, 6th, or 7th position, if n=2, it is preferably the 5th and 7th positions, and the 6th and 8th positions, if n=3, it is preferably a combination of the 3rd, 6th, and 8th positions. Among these, it is particularly preferred that the group R is a hydrogen atom and n is 1.

[0072] In formula (3), the group Y represents an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, or an aryl group which may have a substituent. Among these, an aryl group which may have a substituent is preferable, a naphthyl group which may have a substituent is more preferable, and a naphthyl group substituted with an amino group and a sulfo group as substituents is particularly preferable.

[0073] In formula (3), the group Z is defined similarly to the group X in formula (2) above, and is preferably a nitro group.

[0074] The compound having a biphenyl skeleton that does not have an azo group is preferably a compound represented by the following formula (4) or a salt thereof.

[0075] [ka]

[0076] In the above formula (4), the groups P and Q each independently represent a nitro group, an amino group which may have a substituent, a carbonylamide group which may have a substituent, a naphthotriazole group which may have a substituent, an alkyl group having 1 to 20 carbon atoms which may have a substituent, a vinyl group which may have a substituent, an amido group which may have a substituent, a ureido group which may have a substituent, an aryl group which may have a substituent, or a carbonyl group which may have a substituent, but are not limited thereto. However, when an azo group is present at the P position and / or the Q position of the biphenyl skeleton, the fluorescence emission becomes significantly small, and therefore it is not preferable.

[0077] The compound represented by the above formula (4) is preferably a compound represented by the following formula (5).

[0078] [ka]

[0079] In the above formula (5), j represents an integer of 0 to 2. In addition, -(SO 3 The position at which H) is bonded is preferably the 2nd, 4th or 6th position, particularly preferably the 4th position, when the carbon atom to which -CH=CH- is bonded is regarded as the 1st position.

[0080] In the above formula (5), the group R 1 , R 2 , R 3 and R 4are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aralkyloxy group, an alkenyloxy group, an alkylsulfonyl group having 1 to 4 carbon atoms, an arylsulfonyl group having 6 to 20 carbon atoms, a carbonamido group, a sulfonamido group, or a carboxyalkyl group. 1 ~R 4 The position at which is bonded is not particularly limited, but when the vinyl group is the 1st position, the 2nd, 4th, and 6th positions are preferred, and the 4th position is particularly preferred.

[0081] Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, and a cyclobutyl group.

[0082] Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, and a cyclobutoxy group.

[0083] Examples of the aralkyloxy group include aralkyloxy groups having 7 to 18 carbon atoms.

[0084] Examples of the alkenyloxy group include alkenyloxy groups having 1 to 18 carbon atoms.

[0085] Examples of the alkylsulfonyl group having 1 to 4 carbon atoms include a methylsulfonyl group, an ethylsulfonyl group, a propylsulfonyl group, an n-butylsulfonyl group, a sec-butylsulfonyl group, a tertiary butylsulfonyl group, and a cyclobutylsulfonyl group.

[0086] Examples of the arylsulfonyl group having 6 to 20 carbon atoms include a phenylsulfonyl group, a naphthylsulfonyl group, and a biphenylsulfonyl group.

[0087] The compound represented by the above formula (5) can be prepared by known methods, for example, by condensing 4-nitrobenzaldehyde-2-sulfonic acid with a phosphonate, followed by reducing the nitro group. Specific examples of the compound represented by formula (5) include the following compounds described in JP-A-4-226162.

[0088] [ka]

[0089] The salts of the compounds represented by the formulas (1) to (5) refer to a state in which the free acid of each compound represented by the above formula forms a salt together with an inorganic cation or an organic cation. The inorganic cation is an alkali metal cation such as lithium, sodium, potassium, or ammonium (NH 4 + Examples of the organic cation include organic ammonium represented by the following formula (6).

[0090] [ka]

[0091] In formula (6), the group Z 1 ~Z 4 each independently represents a hydrogen atom, an alkyl group, a hydroxyalkyl group, or a hydroxyalkoxyalkyl group, and Z 1 ~Z 4 At least one of these is a group other than a hydrogen atom.

[0092] Base Z 1 ~Z 4 Specific examples of the C alkyl group include methyl, ethyl, butyl, pentyl, and hexyl groups. 1 -C 6 Alkyl groups, preferably C 1 -C 4Alkyl groups: hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 3-hydroxybutyl, 2-hydroxybutyl, and other hydroxy groups. 1 -C 6 Alkyl groups, preferably hydroxy C 1 -C 4 Alkyl groups; and hydroxy C groups such as hydroxyethoxymethyl group, 2-hydroxyethoxyethyl group, 3-hydroxyethoxypropyl group, 3-hydroxyethoxybutyl group, and 2-hydroxyethoxybutyl group. 1 -C 6 Alkoxy C 1 -C 6 Alkyl groups, preferably hydroxy C 1 -C 4 Alkoxy C 1 -C 4 Examples of such groups include alkyl groups.

[0093] Among these inorganic cations or organic cations, sodium, potassium, lithium, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ammonium and other cations are more preferred, with lithium, ammonium and sodium inorganic cations being particularly preferred.

[0094] The polarized luminescent dye having the above structure does not have an azo group in the molecule, so the absorption of light caused by the azo bond is suppressed. In particular, a compound having a stilbene skeleton exhibits luminescence upon irradiation with ultraviolet light, and the presence of the strong carbon-carbon double bond in the stilbene skeleton stabilizes the molecule. Therefore, a polarizing element using a polarized luminescent dye having such a specific structure can absorb ultraviolet light and utilize the energy to exhibit polarized luminescence in the visible range.

[0095] [Polarizing plate for visible range] The visible range polarizing plate has a function of polarizing and transmitting visible light incident on the same axis as the polarization axis of the polarizing plate, but does not transmit or barely transmits visible light incident on the same axis as the absorption axis of the polarizing plate. In other words, it means a general polarizing plate that can convert visible light into linearly polarized light. The visible range polarizing plate may have a function of cutting ultraviolet light. Such a visible range polarizing plate is not particularly limited as long as it has the function, and a polarizing plate that is generally available on the market, that is, a general iodine-based polarizing plate, etc. can be used. For such a visible range polarizing plate, for example, iodine-based polarizing plates SKN series and KN series manufactured by Polatechno Co., Ltd., dye-based polarizing plates THC series and SHC series manufactured by Polatechno Co., Ltd., etc. can be used.

[0096] [light source] In each liquid crystal display device according to the present embodiment, ultraviolet light is irradiated onto one side of the polarizing plate via a light source that emits at least ultraviolet light. As such a light source, a light source that irradiates ultraviolet light, or a light source that irradiates both ultraviolet light and visible light can be used. Examples of light sources that irradiate ultraviolet light include, but are not limited to, black lights, UV lamps, UV-LEDs, etc., and various irradiation devices and irradiation equipment can be used. Examples of light sources that irradiate both ultraviolet light and visible light include, but are not limited to, ultraviolet-visible fiber light sources equipped with a deuterium lamp for the ultraviolet range and a tungsten lamp for the visible range, and various irradiation devices and irradiation equipment can be used. Such a light source may be further incorporated into the liquid crystal display device. Furthermore, external ultraviolet light can be used as a light source that irradiates both ultraviolet light and visible light.

[0097] [Other functional layers] Each liquid crystal display device according to the present embodiment may be provided with various known functional layers, such as a color filter, a hard coat layer, an antiglare layer, an antistatic layer, etc. When preparing such various functional layers, a method of coating a material having various functions on the exposed surface of a component used in each liquid crystal display device is preferred, while a layer or film having such functions may be attached to the exposed surface of the component via an adhesive or pressure sensitive adhesive. EXAMPLES

[0098] The present invention will be described in more detail below with reference to examples, which are merely illustrative and do not limit the present invention. In addition, the "%" and "parts" described below are based on mass unless otherwise specified. In addition, in each structural formula of the compound used in each example and comparative example, acidic functional groups such as sulfo groups are described in the form of free acid.

[0099] [Evaluation method] The ultraviolet polarizing plates and polarized light-emitting plates prepared in the following Examples and Comparative Examples were used as measurement samples, and the following measurements and evaluations were carried out.

[0100] (a) Measurement of transmittance at each wavelength The transmittance and absorbance of the ultraviolet polarizing plate and the polarized light emitting plate were measured using a spectrophotometer (Hitachi High-Technologies Corporation "U-4100"). A Gram-Thompson polarizer capable of irradiating light having 100% polarization in the wavelength region of 220 nm to 2600 nm (hereinafter also referred to as "absolutely polarized light") was installed on each polarizing plate (measurement sample) prepared in each Example and Comparative Example, and the transmittance of light at each wavelength when the absolute polarized light was irradiated on each measurement sample was measured. The transmittance of light measured when the absolute polarized light was irradiated from the Gram-Thompson polarizer and the light polarized in a perpendicular position to the axis showing the highest light absorption was incident on each measurement sample was defined as Ky, and the transmittance of light measured when the absolute polarized light was irradiated and the light polarized in a parallel position to the axis showing the highest light absorption was incident on each measurement sample was defined as Kz, and each transmittance was measured.

[0101] From the obtained Ky and Kz values, the single transmittance (Ts), crossed transmittance (Tc), and degree of polarization (ρ) for each wavelength of each measurement sample were calculated using the following formulas.

[0102]

number

[0103]

number

[0104]

number

[0105] (b) Visibility-corrected single transmittance Ys The luminosity-corrected single transmittance Ys of each measurement sample is calculated by substituting the Ky and Kz values ​​obtained at a predetermined wavelength interval dλ (here, 5 nm) in the wavelength range of 380 to 780 nm in the visible range into the above formula (IV) to calculate the single transmittance Ts at each wavelength, and correcting it to luminosity according to JIS Z 8722:2009. Specifically, the single transmittance Ts was calculated by substituting it into the above formula (III). In formula (III), Pλ represents the spectral distribution of the standard light (C light source), and τλ represents the 2-degree visual field color matching function.

[0106] (c) Measurement of the degree of polarization of a polarized light-emitting plate The polarized emission intensity and the degree of polarization of the emitted light of each measurement sample were measured by the Stokes parameter method using an emission spectrophotometer (Tokyo Instruments Co., Ltd., Spectroscopic Polarimeter Poxi-Spectra). The emission intensity (S 0 ), the emission intensity of the maximum emission wavelength was set as "1", and the ratio of each wavelength was calculated. 0 ) and the degree of linear polarization of emitted light (DOLP) obtained by a spectrophotometer, the degree of polarization of polarized emission (DOP) was calculated according to the following formula (VII).

[0107]

number

[0108] <Preparation of UV Polarizing Plate A> A 75 μm thick polyvinyl alcohol film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) was immersed in 40° C. warm water for 3 minutes to swell the film. The swollen film was immersed in a 45° C. aqueous solution containing 1.0 part of CI Direct Yellow 28, 1.0 part of Glauber's salt, and 1500 parts of water for 4 minutes. The film was stretched 5 times while immersed in a 3% boric acid aqueous solution at 50° C. for 5 minutes. The stretched film was washed with water at room temperature for 20 seconds while maintaining tension, and dried at 70° C. for 9 minutes to obtain an ultraviolet polarizing element. On the other hand, both sides of a triacetyl cellulose film (ZRD-60 manufactured by Fuji Film Corporation) that does not contain an ultraviolet absorber were treated with a 1.5N aqueous sodium hydroxide solution at 35°C for 10 minutes, washed with water, and dried at 70°C for 10 minutes. The resulting ultraviolet polarizing element was then laminated to both sides with an aqueous solution containing 4% polyvinyl alcohol resin (NH-26 manufactured by Nippon Vinyl Chloride Co., Ltd.) to produce ultraviolet polarizing plate A having a luminous efficiency corrected single transmittance (Ys) of 83.24%.

[0109] <Preparation of UV polarizing plate B> An ultraviolet polarizing plate B having a luminous efficiency corrected single transmittance (Ys) of 88.20% was prepared in the same manner as above, except that the 1.0 part of CI Direct Yellow 28 used in the preparation of the ultraviolet polarizing plate A was changed to 0.2 part.

[0110] <Preparation of UV polarizing plate C> An ultraviolet polarizing plate C having a luminous efficiency corrected single transmittance (Ys) of 88.83% was prepared in the same manner as above, except that the 1.0 part of CI Direct Yellow 28 used in the preparation of the ultraviolet polarizing plate A was changed to 0.1 part.

[0111] The single transmittance (Ts), crossed transmittance (Tc), degree of polarization (ρ) and luminosity-corrected single transmittance (Ys) at 365 nm and its λmax (405 nm) of the obtained ultraviolet polarizing plates A to C are shown in Table 1, and Figure 4 shows Ts and Tc at each wavelength of the obtained ultraviolet polarizing plates A to C. It can be seen from Table 1 and Figure 4 that the obtained ultraviolet polarizing plates A to C have high polarization properties in the wavelength region of 350 to 470 nm.

[0112] [Table 1]

[0113] [Synthesis of polarized luminescent dyes] (Synthesis Example 1) 41.4 parts of commercially available sodium 4,4'-diaminostilbene-2,2'-disulfonate were added to 300 parts of water and stirred, and the pH was adjusted to 0.5 using 35% hydrochloric acid. 10.9 parts of 40% aqueous sodium nitrite solution were added to the resulting solution, and the solution was stirred at 10°C for 1 hour, followed by addition of 34.4 parts of 6-aminonaphthalene-2-sulfonic acid, and the pH was adjusted to 4.0 using a 15% aqueous sodium carbonate solution, and the solution was stirred for 4 hours. 60 parts of sodium chloride were added to the resulting reaction solution, and the precipitated solid was separated by filtration, further washed with 100 parts of acetone, and the resulting wet cake was dried to obtain 83.8 parts of the compound of formula (7) which is an intermediate reactant.

[0114] [ka]

[0115] 83.8 parts of the intermediate reactant of formula (7) obtained was added to 300 parts of water and stirred, and the pH was adjusted to 10.0 using a 25% aqueous sodium hydroxide solution. 20 parts of 28% aqueous ammonia and 9.0 parts of copper sulfate pentahydrate were added to the obtained solution and stirred at 90 ° C for 2 hours. 25 parts of sodium chloride were added to the obtained reaction solution, and the precipitated solid was separated by filtration and further washed with 100 parts of acetone to obtain 40.0 parts of a wet cake. This wet cake was dried in a hot air dryer at 80 ° C to obtain 20.0 parts of a compound represented by the following formula (8).

[0116] [ka]

[0117] <Preparation of polarized light emitting element and polarized light emitting plate> (Preparation of polarized light emitting element A) A 60 μm thick polyvinyl alcohol film (VF-PE#6000 manufactured by Kuraray Co., Ltd.) was immersed in 35° C. warm water for 3 minutes to swell the film. The swollen film was immersed in a 45° C. aqueous solution containing 0.03 parts of the compound of formula (8), 1.0 parts of sodium tripolyphosphate, 1.0 parts of sodium sulfate, and 1000 parts of water for 5 minutes. The film was immersed in a 3% boric acid aqueous solution at 50° C. for 5 minutes and stretched 6.0 times. The stretched film was washed with water at room temperature for 20 seconds while maintaining tension, and dried to produce a polarized light emitting element A.

[0118] (Preparation of polarized light-emitting plate A) Both sides of a triacetyl cellulose film (ZRD-60, manufactured by Fuji Film Co., Ltd.) not containing an ultraviolet absorber were treated with a 1.5N aqueous sodium hydroxide solution at 35°C for 10 minutes, washed with water, and then dried at 70°C for 10 minutes. The sodium hydroxide-treated triacetyl cellulose film was laminated on both sides of the polarized light-emitting element A prepared above via an aqueous solution containing 4% polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinyl Polyvinyl Chloride Co., Ltd.) to prepare a polarized light-emitting plate A. The obtained polarized light-emitting plate A showed optical properties equivalent to those of the polarized light-emitting element A.

[0119] (Preparation of polarized light emitting element B) A 60 μm thick polyvinyl alcohol film (VF-PE#6000 manufactured by Kuraray Co., Ltd.) was immersed in warm water at 35° C. for 3 minutes to swell the film. The swollen film was immersed in an aqueous solution at 45° C. containing 0.03 parts of 4,4'-bis-(sulfostyryl)biphenyl disodium solution (Tinopal NFW Liquid manufactured by BASF Co., Ltd.), 1.0 parts of sodium tripolyphosphate, 1.0 parts of sodium sulfate, and 1000 parts of water for 2 minutes. The film was immersed in an aqueous solution of 3% boric acid at 50° C. for 5 minutes and stretched 6.0 times. The stretched film was washed with water at room temperature for 20 seconds while being kept in a tensed state, and dried to produce a polarized light emitting element B.

[0120] (Preparation of polarized light-emitting plate B) Both sides of a triacetyl cellulose film (ZRD-60, manufactured by Fuji Film Co., Ltd.) not containing an ultraviolet absorber were treated with a 1.5N aqueous sodium hydroxide solution at 35°C for 10 minutes, washed with water, and then dried at 70°C for 10 minutes. The sodium hydroxide-treated triacetyl cellulose film was laminated on both sides of the polarized light-emitting element B prepared above via an aqueous solution containing 4% polyvinyl alcohol resin (NH-26, manufactured by Nippon Vinyl Polyvinyl Chloride Co., Ltd.) to prepare a polarized light-emitting plate B. The obtained polarized light-emitting plate B showed optical properties equivalent to those of the polarized light-emitting element B.

[0121] (Preparation of polarized light emitting element C and polarized light emitting plate C) Polarized light-emitting element C and polarized light-emitting plate C were prepared in the same manner as in preparing polarized light-emitting element B, except that the element was immersed for 10 minutes in a 45°C aqueous solution containing 0.03 parts of 4,4'-bis-(sulfostyryl)biphenyl disodium solution, 1.0 parts of sodium tripolyphosphate, 1.0 parts of Glauber's salt, and 1,000 parts of water.

[0122] Table 2 shows the single transmittance (Ts), parallel transmittance (Tp), crossed transmittance (Tc), degree of polarization (ρ), and luminosity-corrected single transmittance (Ys) at 365 nm and 405 nm for each of the obtained polarized light-emitting plates, and Fig. 5A shows Ts and Tc at each wavelength for the obtained polarized light-emitting plates A to C. The parallel transmittance (Tp) was calculated from formula (VIII), and Fig. 5B shows the polarized light incident transmittances Ky and Kz for calculating the parallel transmittance (Tp) for each polarized light-emitting plate. It can be seen from Table 2 and Fig. 5A that the polarized light-emitting plates have high polarization properties in the wavelength range of 350 to 470 nm.

[0123]

number

[0124] [Table 2]

[0125] The degree of polarization (DOP) of polarized light at each wavelength calculated by the above formula (VII) for each of the obtained polarized light-emitting plates is shown in Figure 6. It can be seen that polarized light-emitting plate A emits light with a maximum DOP of 92.0% at 465 nm and with a wavelength range of 430 to 590 nm, while polarized light-emitting plate B and polarized light-emitting plate C emit light with a maximum DOP of 94.6% at 437 nm and with a wavelength range of 400 to 570 nm.

[0126] <Preparation of empty liquid crystal cells> When preparing the liquid crystal cell, the following evaluation cell (manufactured by EHC) was used as an empty liquid crystal cell. Empty liquid crystal cell A: KSRS-02 / B111M1NSS05, cell gap 2μm Empty liquid crystal cell B: KSRS-05 / B111M1NSS05, cell gap 5μm Empty LCD cell C: KSRS-10 / B111M1NSS05, cell gap 10μm Liquid crystal empty cell D: KCRK-03X, cell gap maximum 3μm, wedge-shaped cell

[0127] The liquid crystal cell is fabricated by arranging glass substrates, on which an ITO transparent electrode film and a polyimide alignment film are sequentially provided, facing each other, and sealing the edges of each substrate with an epoxy resin sealant so that an opening can be provided in which liquid crystal can be filled. Note that, when the rubbing direction of the alignment film on one side is set to 0°, the other side is rubbed at 90°, and the rubbing direction is orthogonal to each alignment film surface. In other words, the rubbing direction of the alignment film was adjusted so that the liquid crystal cell would be a TN type liquid crystal cell.

[0128] <Liquid crystal> As twisted nematic liquid crystals (TN type liquid crystals), Merck's ZLI-1083, ZLI-2471, ZLI-4792, ZLI-5092, and MLC-2053 were used. The birefringence (Δn) of each liquid crystal at wavelengths of 365 nm and 640 nm is shown in Table 3 below.

[0129] [Table 3]

[0130] <Examples A1 to A8> The liquid crystals of ZLI-1083, ZLI-2471, ZLI-4792, and ZLI-5092 were filled into empty liquid crystal cell C (cell gap 10 μm), the liquid crystals of ZLI-1083, ZLI-2471, and ZLI-4792 were filled into empty liquid crystal cell B (cell gap 5 μm), and the liquid crystal of ZLI-1083 was filled into empty liquid crystal cell A (cell gap 2 μm) to prepare liquid crystal cells for each example.

[0131] <Comparative Example 1> ZLI-1083 was filled into a liquid crystal empty cell D (wedge-shaped cell, maximum cell gap 3 μm), and the transmittance was measured at a cell gap of 0.9 μm.

[0132] As the light source, an LED light source (Thorlabs, LED M365L2 with mount) that irradiates ultraviolet light at a wavelength of 365 nm was used. Two ultraviolet polarizing plates A prepared above were used and placed on both outer surfaces of the liquid crystal cell in each of Examples A1 to A8 and Comparative Example 1 so that their absorption axes were parallel. The transmittance of the liquid crystal cell was measured under the following conditions, with the transmittance being 100% when ultraviolet light was irradiated from the light source and the absorption axes of the two ultraviolet polarizing plates were parallel.

[0133] One of the ultraviolet polarizing plates was placed so that the rubbing axis of the alignment film on the entrance side glass substrate surface of the liquid crystal cell was perpendicular to the absorption axis of the ultraviolet polarizing plate (parallel to the transmission axis of the polarizing plate). The other ultraviolet polarizing plate was placed so that the rubbing axis of the alignment film on the exit side glass substrate surface of the liquid crystal cell was parallel to the absorption axis of the ultraviolet polarizing plate (orthogonal to the transmission axis of the polarizing plate). In this arrangement, a voltage was applied to the liquid crystal cell to measure the transmittance. When no voltage was applied, 0V was applied, and when voltage was applied, voltages of 2V and 4V were applied, and the transmittance of each was measured.

[0134] The transmittance at 365 nm when no voltage is applied to the liquid crystal cell and when a voltage is applied to the liquid crystal cell, and the maximum contrast value of the liquid crystal cells in each of Examples A1 to A8 and Comparative Example 1 are shown in the following Table 4. In Table 4, "-" indicates that the measurement was not performed.

[0135] [Table 4]

[0136] Furthermore, two sheets of the ultraviolet polarizing plate A prepared above were used as a light source that also emits light of 400 nm, and were placed on both outer surfaces of the liquid crystal cell in each of Examples A1 to A8 and Comparative Example 1 so that their absorption axes were parallel, using an ultraviolet LED (375 nm handheld type black light "PW-UV943H-04" manufactured by Nichia Corporation) as a light source that also emits light of 400 nm. The transmittance of the liquid crystal cell was measured under the following conditions, with the transmittance being 100% when ultraviolet light was irradiated from the light source and the absorption axes of the two ultraviolet polarizing plates were parallel.

[0137] One of the ultraviolet polarizing plates was placed so that the rubbing axis of the alignment film on the entrance side glass substrate surface of the liquid crystal cell was perpendicular to the absorption axis of the ultraviolet polarizing plate (parallel to the transmission axis of the polarizing plate). The other ultraviolet polarizing plate was placed so that the rubbing axis of the alignment film on the exit side glass substrate surface of the liquid crystal cell was parallel to the absorption axis of the ultraviolet polarizing plate (orthogonal to the transmission axis of the polarizing plate). In this arrangement, a voltage was applied to the liquid crystal cell to measure the transmittance. A voltage of 0V was applied when no voltage was applied, and a voltage of 4V was applied when voltage was applied, and the transmittance of each was measured.

[0138] Table 5 below shows the transmittance at 400 nm when no voltage is applied to the liquid crystal cell and when a voltage is applied, and the contrast values ​​of the liquid crystal cells in each of Examples A1 to A8 and Comparative Example 1.

[0139] [Table 5]

[0140] Each of the ultraviolet polarizing plates A to C was attached to the liquid crystal cell shown in Example A2 so as to show the minimum transmittance at the orthogonal position, and a liquid crystal display device having a configuration of ultraviolet polarizing plate / liquid crystal cell / ultraviolet polarizing plate was produced. The maximum contrast at 365 nm and 400 nm was measured while irradiating one side of this liquid crystal display device with an ultraviolet LED (Nichia Corporation's "PW-UV943H-04": 375 nm hand light type black light). The light amount of the ultraviolet LED was set as a transmittance of 100%, and the transmittance at 365 nm and 400 nm when voltage was applied and when no voltage was applied in the liquid crystal display device having the ultraviolet polarizing plate / liquid crystal cell / ultraviolet polarizing plate configuration was measured. The transmittance and maximum contrast results of the obtained liquid crystal display device are shown in Table 6.

[0141] [Table 6]

[0142] From the results of Tables 4 to 6, the liquid crystal cells of Examples A1 to A8 have a difference in transmittance between when a voltage is applied and when no voltage is applied in the ultraviolet region (365 nm) and near ultraviolet-visible region (400 nm), and have high contrast. Therefore, in Examples A1 to A8, it was possible to provide liquid crystal cells having high contrast at wavelengths of 365 nm and 400 nm in the ultraviolet region, and liquid crystal display devices using the same.

[0143] In addition, the results of Examples B1 to B3 show that a high-contrast liquid crystal cell and liquid crystal display device can be provided by using the ultraviolet polarizing plates A to C. In Example B3, the contrast value at 365 nm was 5.1, which is lower than the contrast when other ultraviolet polarizing plates were used, but a contrast that can be recognized by machines, sensors, etc. was obtained.

[0144] <Fabrication of Polarized Light Emitting Display Device A> As the light source, an LED light source (Thorlabs, LED M365L2 with mount) that emits ultraviolet light at a wavelength of 365 nm was used. The ultraviolet polarizing plate A, liquid crystal cell, and polarized light-emitting plate prepared above were arranged in this order, and a polarized light-emitting display device A was produced in which each component was arranged under the following conditions. The ultraviolet light from the light source was irradiated from the ultraviolet polarizing plate A side of the polarized light-emitting display device A, and the emission intensity (brightness) of each of the bright state (amount of light emitted when strongly polarized) and dark state (amount of light emitted when strongly polarized) when the liquid crystal was driven was measured using a two-dimensional color luminance meter (ProMetric IC-PMI2, Konica Minolta, Inc.). For the liquid crystal cell, an empty liquid crystal cell C (cell gap: 10 μm) was used.

[0145] Polarizing plate A for the ultraviolet region was placed so that the rubbing axis of the alignment film on the glass substrate surface on the entrance side of the liquid crystal cell was perpendicular to the absorption axis of polarizing plate A for the ultraviolet region (parallel to the transmission axis of the ultraviolet polarizing plate). The polarizing luminescent plate was also placed so that the rubbing axis of the alignment film on the glass substrate surface on the exit side of the liquid crystal cell was perpendicular to the ultraviolet absorption axis of the polarizing luminescent plate (parallel to the transmission axis of the polarizing luminescent plate). In this arrangement, a voltage was applied to the liquid crystal cell to measure the transmittance. A voltage of 0V was applied when no voltage was applied, and a voltage of 4V was applied when voltage was applied, and the transmittance of each was measured.

[0146] <Fabrication of Polarized Light Emitting Display Device B> As the light source, an LED light source (Thorlabs, LED M365L2 with mount) that emits ultraviolet light at a wavelength of 365 nm was used. The ultraviolet polarizing plate A, liquid crystal cell, and polarized light-emitting plate prepared above were arranged in this order, and a polarized light-emitting display device B was produced in which each component was arranged under the following conditions. The ultraviolet light from the light source was irradiated from the ultraviolet polarizing plate A side of the polarized light-emitting display device B, and the emission intensity (brightness) of each of the bright state (amount of light emitted when strongly polarized) and dark state (amount of light emitted when strongly polarized) when the liquid crystal was driven was measured using a two-dimensional color luminance meter (Konica Minolta, ProMetric IC-PMI2). For the liquid crystal cell, an empty liquid crystal cell C (cell gap: 10 μm) was used.

[0147] Polarizing plate A for the ultraviolet region was placed so that the rubbing axis of the alignment film on the glass substrate surface on the entrance side of the liquid crystal cell was parallel to the absorption axis of polarizing plate A for the ultraviolet region (orthogonal to the transmission axis of the ultraviolet polarizing plate). The polarizing luminescent plate was also placed so that the rubbing axis of the alignment film on the glass substrate surface on the exit side of the liquid crystal cell was orthogonal to the ultraviolet absorption axis of the polarizing luminescent plate (parallel to the transmission axis of the polarizing luminescent plate). In this arrangement, a voltage was applied to the liquid crystal cell to measure the transmittance. A voltage of 0V was applied when no voltage was applied, and a voltage of 4V was applied when voltage was applied, and the transmittance of each was measured.

[0148] <Fabrication of Polarized Light Emitting Display Device C> As the light source, an LED light source (Thorlabs, LED M365L2 with mount) that emits ultraviolet light at a wavelength of 365 nm was used. The ultraviolet polarizing plate A, liquid crystal cell, and polarized light-emitting plate prepared above were arranged in this order, and a polarized light-emitting display device C was produced in which each component was arranged under the following conditions. The ultraviolet light from the light source was irradiated from the ultraviolet polarizing plate A side of the polarized light-emitting display device C, and the emission intensity (brightness) of each of the bright state (amount of light emitted when strongly polarized) and dark state (amount of light emitted when strongly polarized) when the liquid crystal was driven was measured using a two-dimensional color luminance meter (ProMetric IC-PMI2, Konica Minolta, Inc.). For the liquid crystal cell, an empty liquid crystal cell C (cell gap: 10 μm) was used.

[0149] Polarizing plate A for the ultraviolet region was placed so that the rubbing axis of the alignment film on the entrance side glass substrate surface of the liquid crystal cell was perpendicular to the absorption axis of polarizing plate A for the ultraviolet region (parallel to the transmission axis of the ultraviolet region polarizing plate). The polarizing luminescent plate was also placed so that the rubbing axis of the alignment film on the exit side glass substrate surface of the liquid crystal cell was parallel to the ultraviolet absorption axis of the polarizing luminescent plate (orthogonal to the transmission axis of the polarizing luminescent plate). In this arrangement, a voltage was applied to the liquid crystal cell to measure the transmittance. A voltage of 0V was applied when no voltage was applied, and a voltage of 4V was applied when voltage was applied, and the transmittance of each was measured.

[0150] <Examples C1 to C18> In the polarized light-emitting display devices A to C prepared above, ZLI-1083 or MLC-2053 was used as the liquid crystal to be injected into the empty liquid crystal cell, and the polarized light-emitting plates A to C obtained above were used as the polarized light-emitting plates, respectively. The contrast (CR) in the bright state and the dark state was measured for the light emitted from the liquid crystal cell when the liquid crystal was driven (when voltage was applied and when voltage was not applied) in each combination. In addition, the luminosity-corrected single transmittance Ys of the liquid crystal display device when no ultraviolet light was irradiated from the light source was measured using a spectrophotometer U-4100. The results are shown in Tables 7 and 8 below as Examples C1 to C18.

[0151] [Table 7]

[0152] [Table 8]

[0153] From the results of Examples C1 to C18, it was found that by arranging an ultraviolet polarizing plate and a polarized light-emitting plate in a predetermined positional relationship relative to a liquid crystal cell, it was possible to provide a self-luminous liquid crystal display device that not only exhibits high contrast but also has a high luminous efficiency-corrected single-unit transmittance (Ys) of 80% or more.

Claims

1. A liquid crystal display device comprising a liquid crystal cell, a polarizing plate having a polarizing function in the ultraviolet region, and a polarized light-emitting plate that emits polarized light in the visible region when irradiated with 365 nm light, The liquid crystal cell is a TN type liquid crystal cell including a pair of substrates arranged opposite each other, at least one of which has a transparent electrode film, and a liquid crystal layer disposed between the pair of substrates, The liquid crystal contained in the liquid crystal layer has a birefringence Δn of 0.05 to 0.50 at 365 nm. 365 having The thickness of the liquid crystal layer is 1 μm or more and 15 μm or less, a pair of polarizing plates for measurement, each having a polarizing function in the ultraviolet region, is disposed on the outside of the liquid crystal cell with its absorption axes perpendicular to each other, and the transmittance at 365 nm is measured. The absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied is calculated in a state in which the absolute value of the difference is 10% or more and 100% or less, and the measurement polarizing plate has a polarization degree of 99% or more at 365 nm, the polarizing plate having a polarizing function in the ultraviolet region has a polarization degree of 99% or more at 365 nm and is disposed on the outer side of one of the pair of substrates; A liquid crystal display device, characterized in that the polarizing and luminescent plate is disposed on the outer side of the other of the pair of substrates.

2. In a state where a pair of polarizing plates for measurement having a polarizing function in the ultraviolet region are disposed so that their absorption axes are perpendicularly opposed to each other on the outside of the liquid crystal cell, the transmittance of each wavelength in the range of 300 nm to 400 nm is measured, and the absolute value of the difference between the transmittance when no voltage is applied and the transmittance when a voltage of 4 V is applied, calculated for at least one wavelength among the wavelengths, is 10% or more and 100% or less, and 2. The liquid crystal display device according to claim 1, wherein the measurement polarizing plate has a polarization degree of 99% or more in the ultraviolet region of 300 nm or more and 400 nm or less.

3. 2. The liquid crystal display device according to claim 1, wherein an absolute value of a difference between the transmittance when no voltage is applied and the transmittance when a voltage is applied, calculated by measuring the transmittance at 365 nm when a voltage is applied is 4 V, satisfies 10% or more and 100% or less.

4. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal layer satisfies the following relational formula (I): [0010] (In formula (I), u is any one of √3, √15, √35, √63, or √99; Δn 365 represents the birefringence of the liquid crystal at 365 nm, and d represents the thickness (m) of the liquid crystal layer.

5. a luminosity-corrected single-unit transmittance Ys calculated by measuring the transmittance of each wavelength in the range of 380 nm or more and 780 nm or less in a state in which the absorption axes of a pair of measurement polarizing plates having a polarizing function in the ultraviolet region are disposed perpendicularly to each other on the outside of the liquid crystal cell is 50% or more, 5. The liquid crystal display device according to claim 1, wherein the measurement polarizing plate has a polarization degree of 99% or more and a luminous efficiency-corrected single transmittance Ys of 60% or more in the ultraviolet region of 300 nm or more and 400 nm or less.

6. 6. The liquid crystal display device according to claim 1, wherein the liquid crystal satisfies the following relational expression (II): [0025] (In formula (II), Δn 365 represents the birefringence of the liquid crystal at 365 nm, and Δn 640 indicates the birefringence of the liquid crystal at 640 nm.)

7. the polarized light-emitting plate has a polarizing function at 365 nm, 7. The liquid crystal display device according to claim 1, wherein when polarized light of 365 nm is incident on the polarized light-emitting plate, the transmittance of an axis showing the lowest transmittance is 0% or more and 10% or less.

8. The polarized light-emitting plate has a polarizing function at 365 nm, and 8. The liquid crystal display device according to claim 1, wherein the polarized light-emitting plate has an axis having a transmittance of 10% or more and 99% or less when polarized light of 365 nm is incident thereon, and an axis having a transmittance of 0% or more and 5% or less.

9. 7. The liquid crystal display device according to claim 1, wherein the polarizing plate having a polarizing function in the ultraviolet region has a luminosity-corrected single transmittance Ys of 60% or more.

10. 10. The liquid crystal display device according to claim 1, wherein the polarized light-emitting plate has a luminous efficiency-corrected single transmittance Ys of 60% or more.

11. the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least a region of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in a region of 300 to 400 nm in a state where two of the polarizing plates are disposed so as to be perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, a transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and an axis along which the twisted nematic liquid crystal is oriented when no voltage is applied on one of the pair of substrates are arranged parallel to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented in the other of the pair of substrates when no voltage is applied are disposed perpendicular to each other; 7. The liquid crystal display device according to claim 1, wherein liquid crystal display is possible by irradiating light in a wavelength range of 300 to 400 nm from the polarizing plate side having a polarizing function in the ultraviolet region.

12. the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least a region of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the region of 300 to 400 nm in a state where two polarizing plates having a polarizing function in the ultraviolet region are disposed so as to be perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, a transmission axis of the polarizing plate having a polarizing function in the ultraviolet region and an axis along which the twisted nematic liquid crystal is oriented in one of the pair of substrates when no voltage is applied are disposed perpendicular to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented when no voltage is applied on the other of the pair of substrates are arranged parallel to each other; 7. The liquid crystal display device according to claim 1, wherein liquid crystal display is possible by irradiating light in a wavelength range of 300 to 400 nm from the polarizing plate side having a polarizing function in the ultraviolet region.

13. the polarizing plate having a polarizing function in the ultraviolet region has a single transmittance Ts of 20% or more at any wavelength in at least a region of 300 to 400 nm, and has a transmission axis with a crossed transmittance Tc of 0 to 5%, calculated by measuring the transmittance at any wavelength in the region of 300 to 400 nm in a state where two polarizing plates having a polarizing function in the ultraviolet region are disposed so as to be perpendicular to each other, the polarized light-emitting plate has a transmission axis with a transmittance of 50 to 100% when polarized light is incident, and an absorption axis with a transmittance of 0 to 5% when polarized light is incident, at least at any wavelength in a range of 300 to 400 nm; the liquid crystal contained in the liquid crystal cell is a twisted nematic liquid crystal, the transmission axis of the polarizing plate and the axis along which the twisted nematic liquid crystal is oriented in one of the pair of substrates when no voltage is applied are arranged parallel to each other; an absorption axis of the polarized light-emitting plate and an axis along which the twisted nematic liquid crystal is oriented when no voltage is applied on the other of the pair of substrates are arranged parallel to each other; 7. The liquid crystal display device according to claim 1, wherein liquid crystal display is possible by irradiating light in a wavelength range of 300 to 400 nm from the polarizing plate side having a polarizing function in the ultraviolet region.

14. A liquid crystal display device described in any one of claims 1 to 6, wherein the liquid crystal cell has a structure that can be controlled, with or without application of voltage, to be either a transmissive type showing a transmittance of 40% or more and 100% or less at 365 nm, or a non-transmissive type showing a transmittance of 0% or more and 10% or less.

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