JP6880548B2 - Liquid crystal display device - Google Patents

Description

The present invention relates to a liquid crystal display device.

LCD display devices have been widely put into practical use in mobile phones, tablet terminals, personal computers, televisions, PDAs, electronic dictionaries, car navigation systems, music players, digital cameras, digital video cameras and the like. As liquid crystal display devices become smaller and lighter, their use is no longer limited to offices and indoors, but their use is also expanding outdoors and while traveling by car or train.

Under such circumstances, the chances of visually recognizing a liquid crystal display device through a polarizing filter such as sunglasses are increasing. In relation to the use of such a liquid crystal display device, Patent Document 1 describes a screen through a polarizing plate when a polymer film having a retardation of less than 3000 nm is used on the viewing side of the polarizing plate on the viewing side of the liquid crystal display device. It has been reported that a strong interference color appears when observing. Then, in Patent Document 1, as a means for solving the above-mentioned problem, the retardation of the oriented polyester film used on the visual side from the polarizing plate on the visual side is set to 3000 to 30000 nm, and a white light source having a continuous and wide emission spectrum is backed up. It is described to be used as a light source. Focusing on the envelope shape of the interference color spectrum due to the transmitted light transmitted through the compound refracting body, it is possible to obtain a spectrum similar to the emission spectrum of the light source by controlling the retardation of the oriented polyester film, which makes it possible to obtain a spectrum similar to the emission spectrum of the light source. It became possible to suppress. Further, it is described that it is preferable that the angle formed by the absorption axis of the viewing side polarizing plate and the slow axis of the polymer film is approximately 45 ° in order to eliminate blackout.

WO2011 / 058774

As a backlight source for liquid crystal display devices, white light emitting diodes (white LEDs) consisting of light emitting elements that combine a blue light emitting diode and an yttrium aluminum garnet yellow phosphor (YAG yellow phosphor) have been widely used in the past. Has been done. The emission spectrum of this white light source has a wide spectrum in the visible light region and is also excellent in luminous efficiency, so that it is widely used as a backlight source. However, a liquid crystal display device using this white LED as a backlight source can reproduce colors only about 20% of the spectrum recognizable by the human eye.

On the other hand, due to the recent increase in the color gamut of liquid crystal display devices, the emission spectrum of the emission spectrum is divided into each wavelength region of the blue region (400 nm or more and less than 495 nm), the green region (495 nm or more and less than 600 nm), and the red region (600 nm or more and 780 nm or less). A liquid crystal display device using a backlight light source composed of a white light emitting diode having a peak top and a light emitting spectrum having a peak half-value width of less than 5 nm in a red region (600 nm or more and 780 nm or less) has been developed. However, in the liquid crystal display device having the backlight light source corresponding to the expansion of the color gamut described above, an oriented polyester film having a retardation of 3000 to 30,000 nm on the viewing side from the polarizing plate on the viewing side is used as a height with the absorption axis of the polarizing plate on the viewing side. It was discovered that when the angle formed by the slow axis of the molecular film is about 45 °, there still exists a new problem that iris spots occur.

In the present invention, the peak top is in each wavelength region of the blue region (400 nm or more and less than 495 nm), the green region (495 nm or more and less than 600 nm), and the red region (600 nm or more and 780 nm or less), and the red region (600 nm or more and 780 nm or less). In a liquid crystal display device compatible with wide color gamut using a backlight source of a white light source having an emission spectrum in which the half-value width of the peak is less than 5 nm, even when an oriented polyester film is used on the visible side of the visible plate plate. An object of the present invention is to provide a liquid crystal display device in which the occurrence of rainbow spots is suppressed.

A typical invention is as follows.
Item 1.
(1) Backlit light source,
(2) Liquid crystal cell,
A liquid crystal display device having (3) a polarizing plate arranged on the visual side of the liquid crystal cell, and (4) an oriented polyester film having a retardation of 3000 nm or more and 30,000 nm or less in this order.
The backlight source has a peak top of the emission spectrum in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and has the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. It has an emission spectrum with a peak width of less than 5 nm.
The refractive index of the oriented polyester film in the transmission axis direction of the polarizing plate is 1.53 to 1.62.
Liquid crystal display device.
Item 2.
The emission spectrum of the backlight source is
The half width of the peak with the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm is 5 nm or more.
The half width of the peak with the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is 5 nm or more.
Item 2. The liquid crystal display device according to item 1.
Item 3.
Item 3. The liquid crystal display device according to Item 1 or 2, wherein the angle formed by the transmission axis of the polarizing plate and the phase advance axis of the oriented polyester film is approximately 0 degrees.
Item 4.
Item 6. The liquid crystal display device according to any one of Items 1 to 3, wherein the oriented polyester film is a shatterproof film.
Item 5.
Item 6. The liquid crystal display device according to any one of Items 1 to 3, wherein the oriented polyester film is a base film for a touch panel.

The liquid crystal display device of the present invention has a wide color gamut, and can ensure good visibility in which the occurrence of rainbow spots is significantly suppressed at any observation angle.

It is a typical schematic diagram of the liquid crystal display device provided with a touch panel.

The liquid crystal display device typically has a liquid crystal cell and a polarizing plate. A typical schematic diagram of the liquid crystal display device is shown in FIG.

The liquid crystal display device (1) has a light source (2), a liquid crystal cell (4), and a touch panel (6) as a functional layer. Here, in this document, the side on which the image of the liquid crystal display device is displayed (the side on which a human visually recognizes the image) is referred to as the "viewing side", and the side opposite to the viewing side (that is, in the liquid crystal display device, the backlight is usually used. The side on which the light source called the light source is set) is referred to as the "light source side". In FIG. 1, the right side is the viewing side and the left side is the light source side.

Polarizing plates (light source side polarizing plate (3) and viewing side polarizing plate (5)) are provided on both the light source side and the visual viewing side of the liquid crystal cell (4), respectively. Each polarizing plate (3, 5) typically has a structure in which a polarizing element protective film (9a, 9b, 10a, 10b) is laminated on both sides of a film called a polarizing element (7, 8). The liquid crystal display device (1) of FIG. 1 is provided with a touch panel (6) as a functional layer on the viewing side of the viewing side polarizing plate (5). The touch panel shown in FIG. 1 is a resistive touch panel. The touch panel (6) has a structure in which two transparent conductive films (11, 12) are arranged via a spacer (13). The transparent conductive film (11, 12) is a laminate of a base film (11a, 12a) and a transparent conductive layer (11b, 12b). Further, on the light source side and the visual recognition side of the touch panel (6), shatterproof films (14, 15) which are transparent substrates are provided via an adhesive layer.

In FIG. 1, the touch panel (6) is described as a functional layer provided on the viewing side of the viewing side polarizing plate (5), but the touch panel (6) is not limited to the touch panel, and any layer having a film is used. It may be a layer. Further, although the resistance film type touch panel is described as the touch panel, it is also possible to use another type of touch panel such as a projection type capacitance type. The touch panel of FIG. 1 has a structure having two transparent conductive films, but the structure of the touch panel is not limited to this, and for example, the number of transparent conductive films and / or shatterproof films may be one. Good. In the liquid crystal display device (1), the shatterproof films are not necessarily arranged on both sides of the touch panel (6), and may be arranged on either side, or the shatterproof films are not arranged on both sides. It may be configured. The shatterproof film may be arranged on the touch panel via the adhesive layer, or may be arranged on the touch panel without the adhesive layer.

<Positional relationship of oriented polyester film>
Oriented polyester films can be used in liquid crystal display devices for a variety of purposes. In this document, the oriented polyester film means a polyester film having birefringence. From the viewpoint of improving visibility, the liquid crystal display device preferably has an oriented polyester film having a retardation of 3000 nm or more and 30,000 nm or less (high retardation oriented polyester film). In the liquid crystal display device of FIG. 1, the oriented polyester film is typically a film on the visual side of the polarizing plate (5) (hereinafter, referred to as “visual plate plate”) on the visual side of the liquid crystal cell (4). That is, the base film (11a) (hereinafter, referred to as "light source side base film") of the transparent conductive film (11) on the light source side of the spacer (13), and the transparent on the visual side of the spacer (13). It is between the base film (12a) of the conductive film (12) (hereinafter referred to as "visual base film"), the visible side polarizer protective film (10b), and the light source side base film (11a). Anti-scattering film (14) (hereinafter referred to as "light-emitting side anti-scattering film") and anti-scattering film (15) located on the visual side of the visible-side base film 12a (hereinafter referred to as "visual-related anti-scattering film") Can be used for.

The position where the oriented polyester film is provided is not particularly limited as long as it is on the visual side of the viewing side polarizing plate (5).

The liquid crystal display device may include two or more oriented polyester films. When the liquid crystal display device includes two or more oriented polyester films, the position where the two oriented polyester films are provided is not particularly limited. The phase-advancing axes of the two oriented polyester films are preferably close to parallel to each other. For example, the angle formed by the phase-advancing axes of the two oriented polyester films is preferably 0 degrees ± 15 degrees, preferably 0 degrees ± 10 degrees, preferably 0 degrees ± 5 degrees, preferably 0 degrees ± 3 degrees. It is preferably 0 degree ± 2 degrees, preferably 0 degree ± 1 degree, and preferably 0 degree.

The angle formed by the phase-advancing axis of the oriented polyester film and the transmission axis of the viewing-side polarizing plate (assuming that the oriented polyester film and the polarizing plate are on the same plane) is abbreviated from the viewpoint of reducing rainbow spots. It is preferably 0 degrees. For example, the angle is preferably 0 degrees ± 25 degrees or less, preferably 0 degrees ± 20 degrees or less, preferably 0 degrees ± 15 degrees or less, preferably 0 degrees ± 10 degrees or less, preferably 0 degrees ± 5 degrees or less. It is preferably 0 degrees ± 3 degrees or less, preferably 0 degrees ± 2 degrees or less, preferably 0 degrees ± 1 degrees or less, and preferably 0 degrees. In addition, in this document, the term "below" means that it applies only to the numerical value next to "±". That is, the above-mentioned "0 degree ± 15 degrees or less" means that fluctuations in the range of 15 degrees up and down around 0 degrees are allowed.

By setting the angle between the phase-advancing axis of the oriented polyester film and the transmission axis of the viewing-side polarizing plate to approximately 0 degrees, the linearly polarized light emitted from the viewing-side polarizing plate maintains the polarized state even when it passes through the oriented polyester film. It will pass as it is. Further, by controlling the birefringence of the oriented polyester film to enhance the uniaxial orientation, light incident from an oblique direction can also pass while maintaining the polarized state. When the oriented polyester film is viewed from an angle, a deviation occurs in the orientation spindle direction as compared with a case where it is viewed from directly above, but when the uniaxial orientation is high, the deviation in the orientation spindle direction when viewed from an angle becomes small. Therefore, it is considered that the deviation between the direction of linearly polarized light and the direction of the main axis of orientation is small, and the change in the polarization state is less likely to occur. By controlling the emission spectrum of the light source, the orientation state of the birefringent, and the direction of the main axis of orientation in this way, changes in the polarization state are suppressed, rainbow-shaped color spots do not occur, and visibility is significantly improved. It is thought that.

However, even when the angle formed by the phase-advancing axis of the oriented polyester film and the transmission axis of the viewing-side polarizing plate is set to approximately 0 degrees, the linearly polarized light emitted from the viewing-side polarizing plate passes through the polyester film. The polarization state may change. It was found that one of the factors may be the difference in the refractive index at the interface between the oriented polyester film and the other layers. When linearly polarized light incident from an oblique direction passes through each interface, a part of light is reflected due to the difference in refractive index between the interfaces. At this time, it is possible that the polarization state of both the emitted light and the reflected light changes, which is considered to be one of the factors that cause rainbow-shaped color spots. Therefore, by reducing the difference in refractive index between the other layers and the oriented polyester film in the polarization direction (transmission axis direction) of the incident linearly polarized light, reflection at each interface is suppressed, and iridescent color spots are formed. Is thought to be suppressed. In the liquid crystal display device, the oriented polyester film has a relatively high refractive index as compared with other members. Therefore, the refractive index of the oriented polyester film in the polarization direction (transmission axis direction) of the incident linearly polarized light should be reduced. Is preferable.

For the above reasons, the refractive index of the oriented polyester film in the direction parallel to the transmission axis direction of the viewing side polarizing plate (the direction parallel to the space) is preferably 1.53 to 1.62. Simply, the angle formed by the phase-advancing axis direction of the oriented polyester film produced by the stretching method described later and the transmission axis of the viewing-side polarizing plate (assuming that the oriented polyester film and the polarizing plate are in the same plane). The above relationship can be achieved by setting (to) to approximately 0 degrees, but the present invention is not limited to this.
Orientation in the direction parallel to the transmission axis direction of the viewing side polarizing plate When the refractive index of the polyester film is less than 1.53, the crystallization of the polyester film becomes insufficient, and the dimensional stability, mechanical strength, chemical resistance, etc. are stretched. This is not preferable because the characteristics obtained by the above are insufficient. If the refractive index exceeds 1.62, iridescent spots may occur when observed from an oblique direction. The upper limit of the refractive index of the oriented polyester film in the direction parallel to the transmission axis direction of the viewing side polarizing plate is more preferably 1.61 or less, further preferably 1.60 or less, and even more preferably 1.59. It is less than or equal to, and particularly preferably 1.58 or less. The lower limit of the refractive index of the oriented polyester film in the direction parallel to the transmission axis direction of the viewing side polarizing plate is more preferably 1.54 or more, further preferably 1.55 or more, still more preferably 1.56. It is more than that, and it is particularly preferably 1.57 or more.

<Retamination of oriented polyester film>
The retardation of the oriented polyester film is preferably 3000 nm or more and 30,000 nm or less from the viewpoint of reducing iridescent spots. The lower limit of the retardation of the oriented polyester film is preferably 4500 nm or more, preferably 6000 nm or more, preferably 8000 nm or more, and preferably 10000 nm or more. On the other hand, the upper limit of the retardation of the oriented polyester film is such that even if an oriented polyester film having a higher retardation is used, the effect of further improving visibility cannot be substantially obtained, and the orientation depends on the height of the retardation. Since the thickness of the polyester film also tends to increase, it is set to 30,000 nm from the viewpoint that it may be contrary to the demand for thinning, but it can be set to a higher value. When the liquid crystal display device has two or more oriented polyester films, their retardations may be the same or different.

From the viewpoint of more effectively suppressing rainbow spots, the ratio (Re / Rth) of the retardation (Re) to the thickness direction retardation (Rth) of the oriented polyester film is preferably 0.2 or more, which is preferable. Is 0.5 or more, preferably 0.6 or more. The thickness direction retardation means the average value of the retardation obtained by multiplying the two birefringence ΔNxz and ΔNyz when viewed from the cross section in the film thickness direction by the film thickness d, respectively. The larger the Re / Rth, the more isotropic the action of birefringence, and the more effectively the occurrence of iridescent spots on the screen can be suppressed. In addition, when it is simply described as "retamination" in this document, it means in-plane retardation (measurement wavelength 589 nm).

The maximum value of Re / Rth is 2.0 (that is, a perfect axisymmetric film), but the mechanical strength in the direction orthogonal to the orientation direction tends to decrease as the film approaches the perfect axisymmetric film. is there. Therefore, the upper limit of Re / Rth of the polyester film is preferably 1.2 or less, preferably 1.0 or less. Even if the ratio is 1.0 or less, it is possible to satisfy the viewing angle characteristics (about 180 degrees left and right, 120 degrees up and down) required for the liquid crystal display device.

The retardation of the oriented polyester film can be measured according to a known method. Specifically, it can be obtained by measuring the refractive index and the thickness in the biaxial direction. It can also be obtained using a commercially available automatic birefringence measuring device (for example, KOBRA-21ADH: manufactured by Oji Measuring Instruments Co., Ltd.).

<Manufacturing method of oriented polyester film>
The method for producing the oriented polyester film will be described below. The polyester film can be obtained by condensing an arbitrary dicarboxylic acid with a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and diphenylcarboxylic acid. Acid, diphenoxyetanedicarboxylic acid, diphenylsulfoncarboxylic acid, anthracendicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid Acids, malonic acids, dimethylmalonic acids, succinic acids, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid Examples thereof include dimer acid, sebacic acid, suberic acid, and dodecadicarboxylic acid.

Examples of the diol include ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, decamethylene glycol, 1,3-propanediol, and 1,4. Examples thereof include -butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone.

The dicarboxylic acid component and the diol component constituting the polyester film may be used alone or in combination of two or more. Specific examples of the polyester resin constituting the polyester film include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and the like, preferably polyethylene terephthalate and polyethylene terephthalate, preferably polyethylene terephthalate. .. The polyester resin may contain other copolymerization components, and the proportion of the copolymerization components is preferably 3 mol% or less, preferably 2 mol% or less, and further preferably 1.5 mol% or less from the viewpoint of mechanical strength. .. These resins are excellent in transparency as well as thermal and mechanical properties. In addition, the retardation of these resins can be easily controlled by stretching.

The polyester film can be obtained according to a general manufacturing method. Specifically, the polyester resin is melted and extruded into a sheet, and the unoriented polyester is stretched in the vertical direction at a temperature equal to or higher than the glass transition temperature by utilizing the speed difference of the rolls, and then laterally stretched by a tenter. An oriented polyester film can be mentioned by stretching and heat-treating. The polyester film may be a uniaxially stretched film or a biaxially stretched film.

The production conditions for obtaining the polyester film can be appropriately set according to a known method. For example, the longitudinal stretching temperature and the transverse stretching temperature are usually 80 to 130 ° C., preferably 90 to 120 ° C.
In one embodiment, the longitudinal stretch ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times. The lateral stretching ratio is usually 2.5 to 6.0 times, preferably 3.0 to 5.5 times.
Alternatively, in one embodiment, the longitudinal stretching ratio is usually 2.5 to 6.0 times, preferably 3.0 to 5.5 times. The lateral stretching ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times.

Controlling the retardation within a specific range can be performed by appropriately setting the stretching ratio, stretching temperature, and film thickness. For example, the higher the difference in stretching ratio between longitudinal stretching and transverse stretching, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high retardation. On the contrary, the lower the difference in stretching ratio between the longitudinal stretching and the transverse stretching, the higher the stretching temperature, and the thinner the film thickness, the easier it is to obtain lower retardation. Further, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a low ratio (Re / Rth) of retardation and retardation in the thickness direction. On the contrary, the lower the stretching temperature and the higher the total stretching ratio, the higher the ratio of retardation to thickness direction retardation (Re / Rth) can be obtained. Further, the heat treatment temperature is usually preferably 140 to 240 ° C, preferably 180 to 240 ° C.

The refractive index of the oriented polyester film in the phase-advancing axis direction is preferably 1.53 or more and 1.62 or less. If the refractive index is less than 1.53, the crystallization of the polyester film becomes insufficient, and the properties obtained by stretching such as dimensional stability, mechanical strength, and chemical resistance become insufficient, which is not preferable. The upper limit of the refractive index of the polyester film in the phase-advancing axis direction is more preferably 1.61 or less, further preferably 1.60 or less, still more preferably 1.59 or less, and particularly preferably 1. It is 58 or less. The lower limit of the refractive index of the polyester film in the phase-advancing axis direction is more preferably 1.54 or more, further preferably 1.55 or more, still more preferably 1.56 or more, and particularly preferably 1. It is 57 or more.
The refractive index of the oriented polyester film in the slow axis direction is preferably 1.67 or more and 1.78 or less. The upper limit of the refractive index of the polyester film in the slow axis direction is more preferably 1.75 or less, still more preferably 1.73 or less, and even more preferably 1.72 or less. The lower limit of the refractive index of the slow axis of the polyester film is more preferably 1.68 or more.
The above-mentioned adjustment of the refractive index can be easily adjusted by the stretching treatment in the film forming step.

In order to suppress fluctuations in retardation in the polyester film, it is preferable that the thickness unevenness of the film is small. If the longitudinal stretching ratio is lowered in order to make a difference in retardation, the value of the longitudinal thickness spot may increase. Since there is a region where the value of the vertical thickness spot becomes very high in a specific range of the draw ratio, it is desirable to set the film forming conditions so as to exclude such a range.

The thickness unevenness of the oriented polyester film is preferably 5.0% or less, further preferably 4.5% or less, further preferably 4.0% or less, and 3.0% or less. Is particularly preferred. The thickness unevenness of the film can be measured by any means. For example, a tape-shaped sample (length 3 m) continuous in the flow direction of the film is taken, and a commercially available measuring instrument (for example, an electronic micrometer Millitron 1240 manufactured by Seiko EM Co., Ltd.) is used to measure 100 at a pitch of 1 cm. The thickness of the points is measured, the maximum value (dmax), the minimum value (dmin), and the average value (d) of the thickness are obtained, and the thickness unevenness (%) can be calculated by the following formula.
Thickness spot (%) = ((dmax-dmin) / d) x 100

<Liquid crystal cell and backlight source>

As the liquid crystal cell, any liquid crystal cell that can be used in the liquid crystal display device can be appropriately selected and used, and the method and structure thereof are not particularly limited. For example, a liquid crystal cell such as a VA mode, an IPS mode, a TN mode, an STN mode, or a bend orientation (π type) can be appropriately selected and used. Therefore, as the liquid crystal cell, a liquid crystal made of a known liquid crystal material or a liquid crystal material that can be developed in the future can be appropriately selected and used. A preferred liquid crystal cell in one embodiment is a transmissive liquid crystal cell.

The configuration of the backlight may be an edge light system having a light guide plate, a reflector, or the like as a constituent member, or a direct type system, but in the present invention, the backlight source of the liquid crystal display device is used. The peak top of the emission spectrum is in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 750 nm or less, and the half-value width of the peak with the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less is A backlight source composed of a white light emitting diode having an emission spectrum of less than 5 nm is preferable. The upper limit of the half width of the peak having the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less is preferably less than 5 nm, more preferably less than 4 nm, and further preferably less than 3.5 nm. The lower limit is preferably 1 nm or more, more preferably 1.5 nm or more. When the half width of the peak is less than 5 nm, the color gamut of the liquid crystal display device is widened, which is preferable. Further, if the half width of the peak is less than 1 nm, the luminous efficiency may deteriorate, which is not preferable. The shape of the emission spectrum is designed from the balance between the required color gamut and luminous efficiency. Here, the full width at half maximum is the peak width (nm) at half the intensity of the peak intensity at the wavelength of the peak top.

The application of a backlight source having an emission spectrum having the above-mentioned characteristics to an LCD is a technique that has attracted attention due to the increasing demand for color gamut expansion in recent years. An LED that uses a conventionally used white LED (for example, a light emitting element that combines a blue light emitting diode and an yttrium / aluminum / garnet-based yellow phosphor) as a backlight source has a spectrum that can be recognized by the human eye. Only about 20% of the colors can be reproduced. On the other hand, when a backlight source having an emission spectrum having the above-mentioned characteristics is used, it is said that 60% or more of colors can be reproduced.

The wavelength region of 400 nm or more and less than 495 nm is more preferably 430 nm or more and 470 nm or less. The wavelength region of 495 nm or more and less than 600 nm is more preferably 510 nm or more and 560 nm or less. The wavelength region of 600 nm or more and 780 nm or less is more preferably 600 nm or more and 700 nm or less, and even more preferably 610 nm or more and 680 mn or less.

The peak half width at the peak top of each wavelength region of 400 nm or more and less than 495 nm (half width of the peak having the highest peak intensity in each wavelength region) of the emission spectrum is not particularly limited, but is 400 nm or more and less than 495 nm. The half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more is preferably 5 nm or more, and the half width of the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is preferably 5 nm or more. From the viewpoint of ensuring an appropriate color gamut, the upper limit of the peak half width (half width of the peak having the highest peak intensity in each wavelength region) at the peak top of each wavelength region of 400 nm or more and less than 495 nm and 495 nm or more and less than 600 nm is set. It is preferably 140 nm or less, preferably 120 nm or less, preferably 100 nm or less, more preferably 80 nm or less, still more preferably 60 nm or less, and even more preferably 50 nm or less.

Specific examples of the white light source having an emission spectrum having the above-mentioned characteristics include a phosphor-type white light emitting diode in which a blue light emitting diode and a phosphor are combined. Examples of the red phosphor among the phosphors include a fluoride phosphor (also referred to as “KSF”) having a _{composition formula of K 2} SiF ₆ : Mn ^{4+, and others.} Particularly preferably, a white light emitting diode having a blue light emitting diode and _{a fluoride phosphor having at least K 2} SiF ₆ : Mn ^{4+ as a phosphor is preferable.} For example, a commercially available product such as NSSW306FT, which is a white LED manufactured by Nichia Corporation, can be used. Among the phosphors, as the green phosphor, for example, a sialon-based phosphor having a basic composition of β-SiAlON: Eu or the like, or a silicate-based fluorescent substance having a basic composition of _{(Ba, Sr) 2} SiO _{4: Eu or the like.} , Others are exemplified.

When a plurality of peaks are present in any of the wavelength region of 400 nm or more and less than 495 nm, the wavelength region of 495 nm or more and less than 600 nm, or the wavelength region of 600 nm or more and 780 nm or less, it is considered as follows.
When the plurality of peaks are independent peaks, it is preferable that the half width of the peak having the highest peak intensity is in the above range. Further, for other peaks having an intensity of 70% or more of the highest peak intensity, it is more preferable that the half width is similarly in the above range. Here, the independent peak has an intensity region that is halved of the peak intensity on both the short wavelength side and the long wavelength side of the peak. That is, when a plurality of peaks overlap and each peak does not have a region of intensity that is 1/2 of the peak intensity, the plurality of peaks are regarded as one peak as a whole. For one peak having such a shape in which a plurality of peaks are overlapped, the width of the peak (nm) at half the intensity of the highest peak intensity among them is set as the half width.
Of the plurality of peaks, the peak with the highest peak intensity is set as the peak top.
The peak having the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm, or the wavelength region of 495 nm or more and less than 600 nm, or the wavelength region of 600 nm or more and 780 nm or less has an independent relationship with the peaks in other wavelength regions. Is preferable. In particular, the intensity is 600 nm or more and 780 nm or less in the wavelength region between the peak having the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm or the peak having the highest peak intensity in the region of 600 nm or more and 780 nm or less. In terms of color clarity, it is preferable that there is a region that is 1/3 of the peak intensity of the peak having the highest peak intensity in the wavelength region.

The emission spectrum of the backlight source can be measured by using a spectroscope such as the Hamamatsu Photonics multi-channel spectroscope PMA-12.

<Polarizer and polarizer protective film>
The polarizing plate has a structure in which both sides of a film-shaped polarizing element are sandwiched between two protective films (sometimes referred to as "polarizer protective film"). As the polarizing element, any polarizing element (or polarizing film) used in the art can be appropriately selected and used. As a typical polarizer, a polyvinyl alcohol (PVA) film or the like dyed with a dichroic material such as iodine can be mentioned, but the present invention is not limited to this, and is known and will be developed in the future. The obtained polarizer can be appropriately selected and used.

Commercially available PVA films can be used, for example, "Kuraray Vinylon (manufactured by Kuraray Co., Ltd.)", "Tosero Vinylon (manufactured by Tohcello Co., Ltd.)", "Nippon Synthetic Chemical Industry Co., Ltd." (Manufactured)] and the like. Examples of the bicolor material include iodine, a diazo compound, a polymethine dye and the like.

The polarizer can be obtained by any method. For example, a PVA film dyed with a dichroic material is uniaxially stretched in an aqueous boric acid solution, and washed and dried while maintaining the stretched state. Can be obtained by The draw ratio of uniaxial stretching is usually about 4 to 8 times, but is not particularly limited. Other manufacturing conditions and the like can be appropriately set according to a known method.

The type of protective film is arbitrary, and a film conventionally used as a protective film can be appropriately selected and used. From the viewpoint of handleability and availability, for example, triacetyl cellulose (TAC) film, acrylic film, and cyclic olefin film (for example, norbornene film), polyester film, polypropylene film, and polyolefin film (for example). It is preferable to use one or more films selected from the group consisting of TPX) and the like.

In one embodiment, the light source side protective film of the viewing side polarizer and the viewing side protective film of the light source side polarizing element are preferably optical compensation films having an optical compensation function. Such an optical compensation film can be appropriately selected according to each method of liquid crystal, for example, a liquid crystal compound (for example, a discotic liquid crystal compounding portion and / or a birefractive compound) is dispersed in triacetyl cellulose. It is selected from the group consisting of resins, cyclic olefin resins (for example, norbornene resins), propionyl acetate resins, polycarbonate film resins, acrylic resins, styrene acrylonitrile copolymer resins, lactone ring-containing resins, and imide group-containing polyolefin resins. The ones obtained from more than seeds can be mentioned.

Since the optical compensation films are commercially available, they can be appropriately selected and used. For example, "Wide View-EA" and "Wide View-T" for TN method (manufactured by Fujifilm), "Wide View-B" for VA method (manufactured by Fujifilm), VA-TAC (manufactured by Konica Minolta). (Manufactured by), "Zeonor Film" (manufactured by Nippon Zeon), "Arton" (manufactured by JSR), "X-plat" (manufactured by Nitto Denko), and "Z-TAC" for IPS system (manufactured by Fujifilm) ), "CIG" (manufactured by Nitto Denko), "P-TAC" (manufactured by Okura Kogyo Co., Ltd.) and the like.

The polarizer protective film can be laminated directly on the polarizer or via an adhesive layer. From the viewpoint of improving adhesiveness, it is preferable to laminate via an adhesive. The adhesive is not particularly limited and any adhesive can be used. From the viewpoint of thinning the adhesive layer, an aqueous type (that is, an adhesive component dissolved in water or dispersed in water) is preferable. For example, when a polyester film is used as the polarizer protective film, a polyvinyl alcohol-based resin, a urethane resin, or the like is used as the main component, and an isocyanate-based compound, an epoxy compound, or the like is blended as necessary in order to improve the adhesiveness. The composition can be used as an adhesive. The thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

When a TAC film is used as the polarizer protective film, it can be bonded using a polyvinyl alcohol-based adhesive. When a film having low moisture permeability such as an acrylic film, a cyclic olefin film, a polypropire film, or TPX is used as the polarizer protective film, it is preferable to use a photocurable adhesive as the adhesive. Examples of the photocurable resin include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

The thickness of the polarizer protective film is arbitrary, and can be appropriately set, for example, in the range of 15 to 300 μm, preferably in the range of 30 to 200 μm.

<Touch panel, transparent conductive film, base film, shatterproof film>
The liquid crystal display device may include a touch panel. The type and method of the touch panel are not particularly limited, and examples thereof include a resistive touch panel and a capacitance type touch panel. The touch panel usually has one or more transparent conductive films regardless of the method. The transparent conductive film has a structure in which a transparent conductive layer is laminated on a base film. As described above, an oriented polyester film can be used as the base film. When the oriented polyester film is not used as the base film, another film conventionally used as the base film or a rigid plate such as a glass plate can be used.

Examples of other films conventionally used as the base film include various transparent resin films. For example, polyester resin, acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth) acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylate. A film obtained from one or more kinds of resins selected from the group consisting of resins, polyphenylene sulfide resins and the like can be used. Among these, polyester resin, polycarbonate resin, and polyolefin resin are preferable, and polyester resin is preferable.

The thickness of the base film is arbitrary, but is preferably in the range of 15 to 500 μm.

The surface of the base film may be subjected to an etching treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, or an undercoating treatment in advance. This makes it possible to improve the adhesion with the transparent conductive layer or the like provided on the base film. Further, before providing the transparent conductive layer or the like, the surface of the base film may be dust-removed and cleaned by solvent cleaning, ultrasonic cleaning, or the like, if necessary.

The transparent conductive layer may be laminated directly on the base film, but can be laminated via an easy-adhesion layer and / or various other layers. Examples of other layers include a hard coat layer, an index matching (IM) layer, a low refractive index layer, and the like. The following six patterns can be mentioned as a typical laminated structure of the transparent conductive film, but the laminated structure is not limited to these.
(1) Base film / Easy-adhesion layer / Transparent conductive layer (2) Base film / Easy-adhesion layer / Hard coat layer / Transparent conductive layer (3) Base film / Easy-adhesion layer / IM (index matching) layer / Transparent conductive layer (4) Base film / Easy-adhesion layer / Hard coat layer / IM (index matching) layer / Transparent conductive layer (5) Base film / Easy-adhesion layer / Hard coat layer (also serves as IM with high refractive index ) / Transparent conductive layer (6) Base film / Easy-adhesion layer / Hard coat layer (high refractive index) / Low refractive index layer / Transparent conductive thin film

Since the IM layer itself has a laminated structure of a high refractive index layer / a low refractive index layer (the transparent conductive thin film side is a low refractive index layer), by using this, the ITO pattern is displayed when the liquid crystal display screen is viewed. Can be obscured. As described in (6) above, the high refractive index layer of the IM layer and the hard coat layer can be integrated, which is preferable from the viewpoint of thinning.

The configurations (3) to (6) above are particularly suitable for use in a capacitive touch panel. Further, the above configurations (2) to (6) are preferable from the viewpoint of preventing oligomers from depositing on the surface of the base film, and a hard coat layer may be provided on the other side of the base film. preferable.

The transparent conductive layer on the base film is formed of a conductive metal oxide. The conductive metal oxide constituting the transparent conductive layer is not particularly limited, and is composed of a group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium and tungsten. Conductive metal oxides of at least one selected metal are used. The metal oxide may further contain the metal atoms shown in the above group, if necessary. Preferred transparent conductive layers are, for example, a tin-doped indium oxide (ITO) layer and an antimony-doped tin oxide (ATO) layer, preferably an ITO layer. Further, the transparent conductive layer may be Ag nanowire, Ag ink, self-assembled conductive film of Ag ink, mesh-like electrode, CNT ink, or conductive polymer.

The thickness of the transparent conductive layer is not particularly limited, but is preferably 10 nm or more, more preferably 15 to 40 nm, and further preferably 20 to 30 nm. When the thickness of the transparent conductive layer is 15 nm or more, it is easy to obtain a good continuous coating having a surface resistance of, for example, 1 × 103 Ω / □ or less. Further, when the thickness of the transparent conductive layer is 40 nm or less, a more transparent layer can be obtained.

The transparent conductive layer can be formed according to a known procedure. For example, a vacuum vapor deposition method, a sputtering method, and an ion plating method can be exemplified. The transparent conductive layer may be amorphous or crystalline. As a method for forming the crystalline transparent conductive layer, it is preferable to form the amorphous film once on the base material and then heat and crystallize the amorphous film together with the flexible transparent base material.

The transparent conductive film of the present invention may be patterned by removing a part of the transparent conductive layer in the plane. The transparent conductive film in which the transparent conductive layer is patterned has a pattern forming portion in which the transparent conductive layer is formed on the base film and a pattern opening having no transparent conductive layer on the base film. Have. Examples of the shape of the pattern forming portion include a square shape and a striped shape.

The liquid crystal display device preferably has one or more anti-scattering films. The shatterproof film can be the oriented polyester film described above. Further, as the shatterproof film, various films conventionally used as the shatterproof film (for example, the transparent resin film described for the above-mentioned base film) can also be used. When two or more shatterproof films are provided, they may be made of the same material or may be different.

The polarizer protective film, the base film, and the shatterproof film can contain various additives as long as the effects of the present invention are not impaired. For example, UV absorbers, inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, lightfasteners, flame retardants, heat stabilizers, antioxidants, antigelling agents. , Surfactants and the like. Further, in order to obtain high transparency, it is also preferable that the polyester film contains substantially no particles. "Substantially free of particles" means, for example, in the case of inorganic particles, the content is 50 ppm or less, preferably 10 ppm or less, and particularly preferably the detection limit or less when the inorganic element is quantified by Keiko X-ray analysis. Means quantity.

The oriented polyester film may have various functional layers. Such functional layers include, for example, a hard coat layer, an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, an antireflection antiglare layer, an antistatic layer, a silicone layer, an adhesive layer, and an antifouling layer. One or more selected from the group consisting of a layer, a water-repellent layer, a blue-cut layer, and the like can be used. By providing the antiglare layer, the antireflection layer, the low reflection layer, the low reflection antiglare layer, and the antireflection antiglare layer, it is expected that the color spots when observed from an oblique direction are improved.

When providing various functional layers, it is preferable to have an easy-adhesion layer on the surface of the oriented polyester film. At that time, from the viewpoint of suppressing interference due to reflected light, it is preferable to adjust the refractive index of the easy-adhesion layer so as to be close to the geometric mean of the refractive index of the functional layer and the refractive index of the oriented polyester film. A known method can be adopted for adjusting the refractive index of the easy-adhesion layer, and for example, it can be easily adjusted by adding titanium, zirconium, or other metal species to the binder resin.

(Hard coat layer)
The hard coat layer may be a layer having hardness and transparency, and usually has various curability such as an ionizing radiation curable resin that is typically cured by ultraviolet rays or an electron beam, and a thermosetting resin that is cured by heat. What is formed as a cured resin layer of the resin is used. A thermoplastic resin or the like may be appropriately added to these curable resins in order to appropriately add flexibility and other physical properties. Among the curable resins, the ionizing radiation curable resin is preferable in that a typical and excellent hard coating film can be obtained.

As the ionizing radiation curable resin, a conventionally known resin may be appropriately used. As the ionizing radiation curable resin, a radically polymerizable compound having an ethylenic double bond, a cationically polymerizable compound such as an epoxy compound and the like are typically used, and these compounds are monomers, oligomers, prepolymers and the like. These can be used alone or in combination of two or more as appropriate. Typical compounds are various (meth) acrylate compounds which are radically polymerizable compounds. Among the (meth) acrylate-based compounds, examples of the compound used at a relatively low molecular weight include polyester (meth) acrylate, polyether (meth) acrylate, acrylic (meth) acrylate, epoxy (meth) acrylate, and urethane (meth). ) Acrylate, etc. can be mentioned.

Examples of the monomer include monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, and N-vinylpyrrolidone; or, for example, trimethylpropantri (meth) acrylate and tripropylene glycol di. (Meta) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. Polyfunctional monomers and the like are also used as appropriate. (Meta) acrylate means acrylate or methacrylate.

When the ionizing radiation curable resin is cured with an electron beam, a photopolymerization initiator is not required, but when it is cured with ultraviolet rays, a known photopolymerization initiator is used. For example, in the case of a radical polymerization system, acetophenones, benzophenones, thioxanthones, benzoins, benzoin methyl ethers and the like can be used alone or in combination as the photopolymerization initiator. In the case of a cationic polymerization system, an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metaserone compound, a benzoin sulfonic acid ester and the like can be used alone or in combination as the photopolymerization initiator.

The thickness of the hard coat layer may be an appropriate thickness, for example, 0.1 to 100 μm, but usually 1 to 30 μm. Further, the hard coat layer can be formed by appropriately adopting various known coating methods.

A thermoplastic resin, a thermosetting resin, or the like can be appropriately added to the ionizing radiation curable resin in order to adjust the physical properties as appropriate. Examples of the thermoplastic resin or the thermosetting resin include acrylic resin, urethane resin, polyester resin and the like.

It is also preferable to add an ultraviolet absorber to the ionizing radiation curable resin in order to impart light resistance to the hard coat layer and prevent discoloration, strength deterioration, crack generation and the like due to ultraviolet rays contained in sunlight and the like. When an ultraviolet absorber is added, the ionizing radiation curable resin is preferably cured by an electron beam in order to prevent the curing of the hard coat layer from being hindered by the ultraviolet absorber. Examples of the ultraviolet absorber include organic ultraviolet absorbers such as benzotriazole compounds and benzophenone compounds, and inorganic ultraviolet absorbers such as fine particle zinc oxide, titanium oxide and cerium oxide having a particle size of 0.2 μm or less. It may be selected from known substances and used. The amount of the ultraviolet absorber added is about 0.01 to 5% by mass in the ionizing radiation curable resin composition. In order to further improve the light resistance, it is preferable to add a radical scavenger such as a hindered amine radical scavenger in combination with an ultraviolet absorber. The electron beam irradiation has an acceleration voltage of 70 kV to 1 MV and an irradiation dose of about 5 to 100 kGy (0.5 to 10 Mrad).

(Anti-glare layer)
As the antiglare layer, a conventionally known one may be appropriately adopted, and is generally formed as a layer in which an antiglare agent is dispersed in a resin. As the antiglare agent, inorganic or organic fine particles are used. The shape of these fine particles is a true sphere, an ellipse, or the like. The fine particles are preferably transparent. Examples of such fine particles include silica beads as inorganic fine particles and resin beads as organic fine particles. Examples of the resin beads include styrene beads, melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, benzoguanamine-formaldehyde beads and the like. The fine particles can usually be added in an amount of 2 to 30 parts by mass, preferably about 10 to 25 parts by mass, based on 100 parts by mass of the resin content.

As with the hard coat layer, the resin that disperses and holds the antiglare agent preferably has as high hardness as possible. Therefore, as the resin, for example, a curable resin such as an ionizing radiation curable resin or a thermosetting resin described in the hard coat layer can be used.

The thickness of the antiglare layer may be an appropriate thickness, and is usually about 1 to 20 μm. The antiglare layer can be formed by appropriately adopting various known coating methods. It is preferable to appropriately add a known anti-precipitation agent such as silica to the coating liquid for forming the anti-glare layer in order to prevent the anti-glare agent from precipitating.

(Anti-reflective layer)
As the antireflection layer, a conventionally known one may be appropriately adopted. In general, the antireflection layer is composed of at least a low refractive index layer, and further, a low refractive index layer and a high refractive index layer (which has a higher refractive index than the low refractive index layer) are alternately laminated adjacent to each other, and the surface side has a low refractive index. It consists of multiple layers. The thickness of each of the low-refractive-index layer and the high-refractive-index layer may be appropriately set according to the intended use, and is about 0.1 μm each when adjacently laminated, and about 0.1 μm when the low-refractive index layer alone is used. Is preferable.

Examples of the low refractive index layer include a layer containing a low refractive index substance such as silica and magnesium fluoride in the resin, a layer of a low refractive index resin such as a fluorine-based resin, and a low refractive index substance in the low refractive index resin. A thin film formed by a thin film forming method (for example, a physical or chemical vapor phase growth method such as vapor deposition, sputtering, CVD, etc.) or oxidation of the contained layer or a layer made of a low refractive index substance such as silica or magnesium fluoride. Examples thereof include a film formed by a sol gel method for forming a silicon oxide gel film from a silicon sol solution, and a layer in which void-containing fine particles are contained in a resin as a low refractive index substance.

The void-containing fine particles are fine particles containing a gas inside, fine particles having a porous structure containing a gas, and the like. It means fine particles with an apparently reduced refractive index. Examples of such void-containing fine particles include silica fine particles disclosed in JP-A-2001-233611. In addition to inorganic substances such as silica, the void-containing fine particles include hollow polymer fine particles disclosed in JP-A-2002-805031 and the like. The particle size of the void-containing fine particles is, for example, about 5 to 300 nm.

Examples of the high refractive index layer include a layer containing a high refractive index substance such as titanium oxide, zirconium oxide, and zinc oxide in the resin, a layer of a high refractive index resin such as a fluorine-free resin, and a high refractive index substance. A thin film forming method (for example, physical or chemical vapor phase growth such as vapor deposition, sputtering, CVD, etc.) is performed by forming a layer contained in a rate resin or a layer made of a high refractive index substance such as titanium oxide, zirconium oxide, or zinc oxide. The thin film formed by the method) can be mentioned.

(Antistatic layer)
As the antistatic layer, a conventionally known one may be appropriately adopted, and is generally formed as a layer containing an antistatic layer in a resin. As the antistatic layer, an organic compound or an inorganic compound is used. For example, examples of the antistatic layer of the organic compound include a cationic antistatic agent, an anionic antistatic agent, an amphoteric antistatic agent, a nonionic antistatic agent, an organic metal antistatic agent, and the like. The inhibitor is used not only as a low molecular weight compound but also as a high molecular weight compound. Further, as the antistatic agent, a conductive polymer such as polythiophene or polyaniline is also used. Further, as an antistatic agent, for example, conductive fine particles made of a metal oxide or the like are also used. The particle size of the conductive fine particles is, for example, about 0.1 nm to 0.1 μm on average in terms of transparency. Examples of the metal oxide include ZnO, CeO ₂ , Sb ₂ O ₂ , SnO ₂ , ITO (indium-doped tin oxide), In ₂ O ₃ , Al ₂ O ₃ , ATO (antimony-doped tin oxide), and the like. AZO (aluminum-doped zinc oxide) and the like can be mentioned.

As the resin containing the antistatic layer, for example, a curable resin such as an ionizing radiation curable resin or a thermosetting resin as described in the hard coat layer is used, and an antistatic layer is used as an intermediate. When the antistatic layer itself is formed as a layer and the surface strength of the antistatic layer itself is not required, a thermoplastic resin or the like is also used. The thickness of the antistatic layer may be appropriately adjusted, and is usually about 0.01 to 5 μm. The antistatic layer can be formed by appropriately adopting various known coating methods.

(Anti-fouling layer)
As the antifouling layer, a conventionally known one may be appropriately adopted, and generally, a silicon-based compound such as silicone oil or silicone resin; a fluorine-based compound such as a fluorine-based surfactant or a fluorine-based resin is contained in the resin. It can be formed by a known coating method using a paint containing an antifouling agent such as wax. The thickness of the antifouling layer may be appropriately set, and is usually about 1 to 10 μm.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples, and is carried out with appropriate modifications to the extent that it can be adapted to the gist of the present invention. It is also possible, all of which are within the technical scope of the invention.

(1) Orientation Polyester film refractive index A molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.) is used to determine the slow axis direction of the film, and the slow axis direction is the sample length for measurement. A rectangle of 4 cm x 2 cm was cut out so as to be parallel to the side, and used as a measurement sample. For this sample, the refractive indexes of the two orthogonal axes (refractive index in the slow axis direction: Ny, refractive index in the phase advance axis (refractive index in the direction orthogonal to the slow axis direction): Nx), and the refractive index in the thickness direction ( Nz) was determined by an Abbe refractive index meter (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).
The refractive index in the direction forming an angle of 45 degrees with the slow axis was obtained as follows. Using a molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.), determine the slow axis direction of the film, and the direction forming an angle of 45 degrees with the slow axis is the long side of the sample for measurement. A rectangle of 4 cm × 2 cm was cut out so as to be parallel to each other and used as a measurement sample. For this sample, the refractive index in the direction forming an angle of 45 degrees with the slow axis was determined by an Abbe refractive index meter (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm).

(2) Reference (Re)
The retardation is a parameter defined by the product (ΔNxy × d) of the anisotropy of the refractive indexes of the two orthogonal axes on the film (ΔNxy = | Nx−Ny |) and the film thickness d (nm). Yes, it is a scale showing optical isotropic and anisotropy. The biaxial refractive index anisotropy (ΔNxy) was determined by the following method. Using a molecular orientation meter (MOA-6004 type molecular orientation meter manufactured by Oji Measuring Instruments Co., Ltd.), determine the slow-phase axial direction of the film, and make the slow-phase axial direction parallel to the long side of the measurement sample, 4 cm. A rectangle of × 2 cm was cut out and used as a measurement sample. For this sample, the refractive index of two orthogonal axes (refractive index in the slow axis direction: Ny, refractive index in the direction orthogonal to the slow axis direction: Nx), and the refractive index in the thickness direction (Nz) are abbe refraction. It was determined by a rate meter (manufactured by Atago Co., Ltd., NAR-4T, measurement wavelength 589 nm), and the absolute value (| Nx-Ny |) of the difference in refractive index between the two axes was defined as the anisotropy of the refractive index (ΔNxy). The film thickness d (nm) was measured using an electric micrometer (Millitron 1245D, manufactured by Finereuf), and the unit was converted to nm. The retardation (Re) was determined from the product (ΔNxy × d) of the anisotropy of the refractive index (ΔNxy) and the thickness d (nm) of the film.

(3) Thickness direction retardation (Rth)
The thickness direction retardation is obtained by multiplying two birefringences ΔNxz (= | Nx−Nz |) and ΔNyz (= | Ny−Nz |) when viewed from a cross section in the film thickness direction by the film thickness d, respectively. It is a parameter indicating the average of the refraction obtained. Nx, Ny, Nz and the film thickness d (nm) are obtained by the same method as the measurement of retardation, and the average value of (ΔNxz × d) and (ΔNyz × d) is calculated to calculate the thickness direction retardation (Rth). ) Was asked.

(4) Measurement of Emission Spectrum of Backlight Light Source REGZA 43J10X manufactured by Toshiba Corporation was used as the liquid crystal display device used in each example. When the emission spectrum of the backlight source of this liquid crystal display device was measured using a multi-channel spectroscope PMA-12 manufactured by Hamamatsu Photonics, emission spectra having peak tops near 450 nm, 535 nm, and 630 nm were observed. The half width of each peak top (half width of the peak having the highest peak intensity in each wavelength region) was 17 nm for the peak at 450 nm and 45 nm for the peak at 535 nm and 2 nm for the peak at 630 nm, respectively. This light source had a plurality of peaks in the wavelength region of 600 nm or more and 780 nm or less, and the half width was evaluated at the peak near 630 nm, which has the highest peak intensity in this region. The exposure time for spectrum measurement was set to 20 msec.

(5) Observation of rainbow spots A polyester film, which will be described later, is laminated on the front surface of REGZA 43J10X manufactured by Toshiba, and the obtained liquid crystal display device is visually observed in a dark place from the front and diagonal directions to observe rainbow spots. The presence or absence of the occurrence of was determined as follows.

◯: No rainbow spots are observed △: Slight rainbow spots are observed ×: Rainbow spots are observed × ×: Rainbow spots are significantly observed

(Production Example 1-Polyester A)
When the temperature of the esterification reaction can was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged, and 0.017 parts by mass of antimony trioxide was used as a catalyst while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine were charged. Then, the pressure was raised and the pressure esterification reaction was carried out under the conditions of a gauge pressure of 0.34 MPa and 240 ° C., the esterification reaction can was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260 ° C. over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Then, after 15 minutes, the dispersion treatment was carried out with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can, and the polycondensation reaction was carried out under reduced pressure at 280 ° C.

After completion of the polycondensation reaction, filtration is performed with a Naslon filter having a 95% cut diameter of 5 μm, extruded into a strand shape from a nozzle, and cooled and solidified using cooling water that has been previously filtered (pore diameter: 1 μm or less). , Cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62 dl / g, and it contained substantially no inert particles and internally precipitated particles. (Hereafter, it is abbreviated as PET (A).)

(Production Example 2-Polyester B)
10 parts by mass of dried UV absorber (2,2'-(1,4-phenylene) bis (4H-3,1-benzoxadinone-4-one), particle-free PET (A) (intrinsic viscosity) 0.62 dl / g) 90 parts by mass was mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).

(Manufacturing Example 3-Adhesive Modification Coating Liquid Adjustment)
Transesterification and polycondensation reactions were carried out by a conventional method to obtain 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 8 mol% of sodium 5-sulfonatoisophthalate as dicarboxylic acid components (relative to the entire dicarboxylic acid component). A water-dispersible metal sulfonate metal base-containing copolymer resin having a composition of 50 mol% of ethylene glycol and 50 mol% of neopentyl glycol as the glycol component was prepared. Next, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cell solution, and 0.06 parts by mass of a nonionic surfactant were mixed, and then heated and stirred. After adding 5 parts by mass of a water-dispersible metal sulfonic acid base-containing copolymerized polyester resin and continuing to stir until the resin is no longer clumped, the resin aqueous dispersion is cooled to room temperature to have a solid content concentration of 5.0% by mass. A uniform water-dispersible copolymerized polyester resin liquid was obtained. Further, after 3 parts by mass of aggregate silica particles (Syricia 310 manufactured by Fuji Silicia Co., Ltd.) are dispersed in 50 parts by mass of water, 99.46 parts by mass of the water-dispersible copolymerized polyester resin liquid is added to Syricia 310. 0.54 parts by mass of an aqueous dispersion was added, and 20 parts by mass of water was added with stirring to obtain an adhesive modification coating liquid.

(Oriented polyester film 1)
After 90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing an ultraviolet absorber were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours as raw materials for the base film intermediate layer. , It was supplied to the extruder 2 (for the intermediate layer II layer), and the PET (A) was dried by a conventional method and supplied to the extruder 1 (for the outer layer I layer and the outer layer III), respectively, and melted at 285 ° C. .. These two types of polymers are filtered through a stainless steel sintered filter medium (nominal filtration accuracy of 10 μm particles 95% cut), laminated in a two-type three-layer confluence block, extruded into a sheet from the base, and then extruded. Using the electrostatic application casting method, the film was wound around a casting drum having a surface temperature of 30 ° C. and cooled and solidified to prepare an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the I layer, the II layer, and the III layer was 10:80:10.

Next, the adhesive modification coating solution was applied to both sides of the unstretched PET film by the reverse roll method ^{so that the coating amount after drying was 0.08 g / m 2} , and then dried at 80 ° C. for 20 seconds. ..

The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and while gripping the end of the film with a clip, it was guided to a hot air zone having a temperature of 125 ° C. and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 10 seconds, and further subjected to a relaxation treatment of 3.0% in the width direction to obtain a uniaxially stretched PET film having a film thickness of about 100 μm. It was. The Re of the obtained film was 10300 nm, Rth was 12350 nm, Re / Rth was 0.83, Nx = 1.588, and Ny = 1.691. The refractive index in the direction forming an angle of 45 degrees with the slow axis was 1.635.

(Oriented polyester film 2)
A film was formed in the same manner as the oriented polyester film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 80 μm was obtained. The Re of the obtained film was 8080 nm, Rth was 9960 nm, Re / Rth was 0.81, Nx = 1.589, and Ny = 1.690.

(Oriented polyester film 3)
A film was formed in the same manner as the oriented polyester film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 60 μm was obtained. The Re of the obtained film was 6060 nm, Rth was 7470 nm, Re / Rth was 0.81, Nx = 1.589, and Ny = 1.690.

(Oriented polyester film 4)
A film was formed in the same manner as the oriented polyester film 1 except that the line speed was changed to change the thickness of the unstretched film, and a uniaxially stretched PET film having a film thickness of about 40 μm was obtained. The Re of the obtained film was 4160 nm, the Rth was 4920 nm, the Re / Rth was 0.85, Nx = 1.587, and Ny = 1.691.

(Oriented polyester film 5)
The unstretched film produced by the same method as the oriented polyester film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 1.5 times in the traveling direction in the roll group having a peripheral speed difference. After stretching, the film was guided to a hot air zone at a temperature of 130 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the oriented polyester film 1. The Re of the obtained film was 7820 nm, the Rth was 13890 nm, the Re / Rth was 0.56, Nx = 1.608, and Ny = 1.686.

(Oriented polyester film 6)
The unstretched film produced by the same method as the oriented polyester film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 2.0 times in the traveling direction in the roll group having a peripheral speed difference. After stretching, the film was guided to a hot air zone at a temperature of 135 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the oriented polyester film 1. The Re of the obtained film was 6400 nm, the Rth was 14600 nm, the Re / Rth was 0.44, Nx = 1.617, and Ny = 1.681.

(Oriented polyester film 7)
The unstretched film produced by the same method as the oriented polyester film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 2.8 times in the traveling direction in the roll group having a peripheral speed difference. After stretching, the film was guided to a hot air zone at a temperature of 140 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the oriented polyester film 1. The Re of the obtained film was 5400 nm, the Rth was 15900 nm, the Re / Rth was 0.34, Nx = 1.631, and Ny = 1.685.

(Oriented polyester film 8)
The unstretched film produced by the same method as the oriented polyester film 1 is heated to 105 ° C. using a heated roll group and an infrared heater, and then 3.3 times in the traveling direction in the roll group having a peripheral speed difference. After stretching, the film was guided to a hot air zone at a temperature of 140 ° C. and stretched 4.0 times in the width direction to obtain a biaxially stretched PET film having a film thickness of about 100 μm in the same manner as in the oriented polyester film 1. The Re of the obtained film was 4800 nm, Rth was 16700 nm, Re / Rth was 0.29, Nx = 1.640, and Ny = 1.688.

(Example 1)
A liquid crystal display device in which the oriented polyester film 1 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Example 2)
A liquid crystal display device in which the oriented polyester film 2 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Example 3)
A liquid crystal display device in which the oriented polyester film 3 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Example 4)
A liquid crystal display device in which an oriented polyester film 4 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Example 5)
A liquid crystal display device in which an oriented polyester film 5 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Example 6)
A liquid crystal display device in which an oriented polyester film 6 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Comparative Example 1)
A liquid crystal display device in which the oriented polyester film 1 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 45 degrees. Got

(Comparative Example 2)
A liquid crystal display device in which the oriented polyester film 1 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 90 degrees. Got

(Comparative Example 3)
A liquid crystal display device in which the oriented polyester film 2 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 90 degrees. Got

(Comparative Example 4)
A liquid crystal display device in which the oriented polyester film 3 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 90 degrees. Got

(Comparative Example 5)
A liquid crystal display device in which an oriented polyester film 7 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Comparative Example 6)
A liquid crystal display device in which an oriented polyester film 8 is laminated on the front surface of the REGZA 43J10X manufactured by Toshiba Corporation so that the angle between the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. Got

(Reference example 1)
The backlight source of Toshiba REGZA 43J10X was replaced with a white LED consisting of a YAG-based yellow phosphor and a blue LED. The emission spectrum of this white LED had a broad spectrum in the visible light region and did not have a clear peak top in the region of 600 nm or more and 750 nm or less. A liquid crystal display device is obtained by laminating the oriented polyester film 1 on the front surface of the liquid crystal display device on the visible side so that the angle formed by the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 0 degrees. It was.

(Reference example 2)
The backlight source of Toshiba REGZA 43J10X was replaced with a white LED consisting of a YAG-based yellow phosphor and a blue LED. The oriented polyester film 1 is laminated on the front surface of the liquid crystal display device so that the angle formed by the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 45 degrees to obtain a liquid crystal display device. It was.

(Reference example 3)
The backlight source of Toshiba REGZA 43J10X was replaced with a white LED consisting of a YAG-based yellow phosphor and a blue LED. The oriented polyester film 1 is laminated on the front surface of the liquid crystal display device so that the angle formed by the transmission axis of the viewing side polarizing plate and the phase advance axis of the oriented polyester film is 90 degrees to obtain a liquid crystal display device. It was.

The results of rainbow spot observation are shown in Table 1.

The liquid crystal display device of the present invention is extremely useful because it has a wide color gamut and can ensure good visibility in which the occurrence of rainbow spots is significantly suppressed at any observation angle.

1 Liquid crystal display device 2 Light source 3 Light source side polarizing plate 4 Liquid crystal cell 5 Visualizing side polarizing plate 6 Touch panel 7 Light source side polarizing element 8 Visualizing side polarizer 9a Polarizer protective film 9b Polarizer protective film 10a Polarizer protective film 10b Visualizing side polarizing Child protective film 11 Light source side transparent conductive film 11a Light source side base film 11b Transparent conductive layer 12 Visible side transparent conductive film 12a Visible side base film 12b Transparent conductive layer 13 Spacer 14 Light source side shatterproof film 15 Visible side shatterproof the film

Claims (4)

(1) Backlit light source,
(2) Liquid crystal cell,
A liquid crystal display device having (3) a polarizing plate arranged on the visual side of the liquid crystal cell, and (4) an oriented polyester film having a retardation of 3000 nm or more and 30,000 nm or less in this order.
The backlight source has a peak top of the emission spectrum in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more and less than 600 nm, and 600 nm or more and 780 nm or less, and has the highest peak intensity in the wavelength region of 600 nm or more and 780 nm or less. It has an emission spectrum with a peak width of less than 5 nm.
The angle formed by the transmission axis of the polarizing plate and the phase advance axis of the oriented polyester film is approximately 0 degrees.
Ri refractive index 1.53 to 1.62 der oriented polyester film of the transmission axis direction of the polarizing plate,
The oriented polyester film has a ratio (Re / Rth) of retardation (Re) to thickness direction retardation (Rth) of 0.5 or more and 2.0 or less.
The liquid crystal display equipment. The emission spectrum of the backlight source is
The half width of the peak with the highest peak intensity in the wavelength region of 400 nm or more and less than 495 nm is 5 nm or more.
The half width of the peak with the highest peak intensity in the wavelength region of 495 nm or more and less than 600 nm is 5 nm or more.
The liquid crystal display device according to claim 1. The liquid crystal display device according to claim 1 or 2, wherein the oriented polyester film is a shatterproof film. The liquid crystal display device according to claim 1 or 2, wherein the oriented polyester film is a base film for a touch panel.

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