JP6874752B2 - Image display device - Google Patents

Description

The present invention relates to an image display device.

Image 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. With the progress of miniaturization and weight reduction of image display devices, 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 an image display device through a polarizing filter such as sunglasses are increasing. In relation to this point, Patent Document 1 states that 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, a strong interference color is observed when the screen is observed through the polarizing plate. Has been reported as a problem. Then, Patent Document 1 describes that, as a means for solving the above-mentioned problem, the retardation of the polymer film used on the viewing side rather than the polarizing plate on the viewing side is set to 3000 to 30,000 nm.

WO2011 / 058774

As a result of further studies on the practicality of the image display device by the above method, the present inventors have found that when using one alignment film in which the retardation value is controlled to a certain level or higher, rainbow spots are used. It has been found that, even if the color tone is not disturbed, when two such oriented films are used, the color tone such as rainbow spots is noticeably disturbed in some cases. Therefore, an object of the present invention is to solve such a problem and provide an image display device having improved visibility.

The present inventors have conducted research day and night to solve the above problems, and found that the above phenomenon is remarkable when the orientation principal axes of the two alignment films are not parallel to each other, and that the two alignment films are not parallel to each other. It has been found that it is possible to suppress color disorder such as rainbow spots even when the orientation principal axes of the two alignment films are not parallel by providing a difference in the retardation. Based on such findings, the present inventors have repeated further studies and improvements to complete the present invention.

A typical invention is as follows.
Item 1.
(1) A white light source having a continuous emission spectrum,
(2) Image display cell,
(3) A polarizing element arranged on the viewing side of the image display cell, and (4) two alignment films having a retardation of 3000 nm or more and 150,000 nm or less on the viewing side of the polarizing element.
The two alignment films have their orientation principal axes substantially parallel to each other or have different retardations, and the difference is 1800 nm or more.
Image display device.
Item 2.
Item 2. The image display device according to Item 1, wherein the difference in retardation between the two alignment films is 3500 nm or more.
Item 3.
Item 2. The image display device according to Item 1 or 2, wherein the white light source having a continuous emission spectrum is a white light emitting diode.

According to the present invention, the visibility of the image display device is improved. In particular, deterioration of image quality due to color tone disorder typified by rainbow spots that occurs when visually recognized through a polarizing filter is reduced. In this document, "rainbow spot" is a concept including "color spot", "color shift", and "interference color".

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

The image display device typically has an image display cell and a polarizing plate. A liquid crystal cell or an organic EL cell is typically used as the image display cell. FIG. 1 shows a typical schematic diagram of an image display device using a liquid crystal cell as an image display cell.

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 image 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 alignment film>
Alignment films can be used in image display devices for a variety of purposes. In this document, the alignment film means a polymer film having birefringence. From the viewpoint of improving visibility, the image display device preferably has two oriented films having retardations of 3000 nm or more and 150,000 nm or less, and the values of these retardations are different from each other. The difference between the retardation values of the two alignment films is not particularly limited, but is preferably 1800 nm or more from the viewpoint of improving visibility. Further, it is preferable that the two alignment films are arranged so that their alignment principal axes are substantially parallel to each other. In the liquid crystal display device of FIG. 1, the alignment film is typically a film on the visual side of a polarizer (8) (hereinafter, referred to as a “visual deflector”) on the visual side of the liquid crystal cell (4). That is, the polarizer protective film (10b) (hereinafter, referred to as "visually visible polarizer protective film") on the visual side of the visible side polarizer (8), and the transparent conductive film (11) on the light source side of the spacer (13). ) Base film (11a) (hereinafter referred to as "light source side base film"), base film (12a) of the transparent conductive film (12) on the visual side of the spacer (13) (hereinafter, "visual recognition"). Side base film (referred to as "side base film"), shatterproof film (14) between the visible side polarizer protective film (10b) and light source side base film (11a) (hereinafter referred to as "light source side shatterproof film"). ) And the anti-scattering film (15) on the visible side of the base film 12a on the visible side (hereinafter, referred to as “the anti-scattering film on the visible side”).

The position where the two alignment films are provided is not particularly limited as long as it is on the viewing side of the viewing side polarizing element (8) and is arbitrary. For example, in the case of the liquid crystal display device of FIG. 1, the arrangement as illustrated in Table 1 below can be adopted.

As described above, the positions of the two oriented films are not limited as long as they are both present on the viewing side of the viewing-side polarizing element, and the positional relationship with each other is not particularly limited. That is, the alignment film having a higher retardation may be arranged on the visual side of the other alignment film, and the alignment film having a higher retardation may be arranged on the light source side of the other alignment film. Therefore, in the examples of patterns 1 to 10 shown in Table 1 above, when the alignment film having a higher retardation is arranged on the visual side of the other alignment film, and the alignment film having a higher retardation is placed on the other orientation. The case where it is arranged on the light source side of the film is included. The patterns 1 to 10 shown in Table 1 are merely examples, and other combinations may be used. For example, in the above, the shatterproof film can be any other functional film that can be provided on the image display device.

In this document, when multiple oriented films (film groups) are used for a single member, they are regarded as one film. Here, the member is separate from the member from the viewpoint of functionality and / or purpose, for example, a polarizer protective film, a light source side shatterproof film, a light source side base film, a visible side base film, a visible side shatterproof film, and the like. It means what is judged to be a member.

From the viewpoint of suppressing color disorder such as rainbow spots in the image displayed by the image display device, the difference in retardation between the two oriented films is preferably 1800 nm or more, preferably 2500 nm or more, preferably 3200 nm or more, preferably 3200 nm or more. Is 3500 nm or more, preferably 4000 nm or more, preferably 5000 nm or more.

From the viewpoint of suppressing color tone disturbance such as rainbow spots in the image displayed by the image display device, it is preferable that the two alignment films are arranged so that their alignment principal axes are substantially parallel to each other. Therefore, the angle formed by the orientation principal axes of the two alignment films is preferably 0 degrees ± 20 degrees or less, preferably 0 degrees ± 15 degrees or less, preferably 0 degrees ± 10 degrees or less, preferably 0 degrees. The degree is ± 5 degrees or less, preferably 0 degrees ± 3 degrees or less, preferably 0 degrees ± 2 degrees or less, preferably 0 degrees ± 1 degree 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 "±". Therefore, the above-mentioned "0 degree ± 20 degrees or less" means that fluctuations in the range of 20 degrees up and down around 0 degrees are allowed.

As described above, it is preferable that the orientation principal axes of the two oriented films are parallel to each other, but the larger the retardation difference between the two films, the larger the allowable range of the angle. When the retardation difference between the two films is 3500 nm or more, preferably 4000 nm or more, rainbow spots can be suppressed regardless of the above angle.

From the viewpoint of suppressing rainbow spots, it is preferable that at least one of the two alignment films has an angle formed by the alignment main axis and the polarization axis of the viewing side polarizer of about 45 degrees. Specifically, the angle is 45 degrees ± 30 degrees or less, 45 degrees ± 20 degrees or less, preferably 45 degrees ± 15 degrees or less, preferably 45 degrees ± 10 degrees or less, preferably 45 degrees ± 7 degrees. Hereinafter, it is preferably 45 degrees ± 5 degrees or less, preferably 45 degrees ± 3 degrees or less, and preferably 45 degrees. Of the two alignment films, it is preferable that the alignment film having a higher retardation satisfies the above positional relationship.

Placing the high retardation oriented film so as to satisfy the above conditions is, for example, a method of arranging the cut high retardation oriented film so that the main axis of orientation is at a specific angle with the polarization axis of the polarizer. , The high retardation alignment film can be stretched diagonally and arranged at a specific angle with the polarization axis of the polarizer.

<Retamination of alignment film>
The retardation of the two alignment films is preferably 3000 nm or more and 150,000 nm or less from the viewpoint of reducing iridescent spots. The lower limit of retardation of the alignment 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 alignment film is that even if a polyester film having a retardation higher than that is used, the effect of further improving the visibility cannot be substantially obtained, and the alignment film depends on the height of the retardation. Since the thickness of the film tends to increase, it is set to 150,000 nm from the viewpoint that it may be contrary to the demand for thinning, but it can be set to a higher value.

In this document, one alignment film having a retardation of 3000 nm or more and 150,000 nm or less may be formed by combining two or more adjacent alignment films as long as the alignment principal axes are substantially parallel. .. For example, when the alignment principal axis of the alignment film having a retardation of 2000 nm and the alignment principal axis of the alignment film of 1000 nm are in a parallel state, these can be regarded as one alignment film having a retardation of 3000 nm. Here, substantially parallel means that the angle formed by the two orientation principal axes is 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 within 0 degrees ± 3 degrees, preferably 0 degrees ± 2 degrees or less, preferably 0 degrees ± 1 degrees or less, and preferably 0 degrees. In this relationship, a plurality of films can be regarded as one film as a "film group". Here, "adjacent" includes both a case where adjacent alignment films are bonded and a case where they are not bonded.

The liquid crystal display device may include an alignment film having a retardation of less than 3000 nm at an arbitrary position. The retardation of such an oriented film is, for example, 50 nm or more, 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more. Further, the upper limit of retardation of such an oriented film is, for example, less than 3000 nm, less than 2500 nm, or less than 2300 nm.

The alignment film having a retardation of less than 3000 nm may be a uniaxially stretched oriented film or a biaxially stretched oriented film, but is a biaxially stretched oriented film from the viewpoint of reducing the easiness of tearing of the film. Is preferable.

The retardation of the alignment 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.).

From the viewpoint of suppressing rainbow spots more effectively, the ratio (Re / Rth) of the retardation (Re) to the thickness direction retardation (Rth) of the alignment film is preferably 0.2 or more, preferably 0.2 or more. It 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.

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 an image display device.

The oriented film can be produced by appropriately selecting a known method. For example, the alignment film is obtained by adding a liquid crystal compound to a polyester resin, a polycarbonate resin, a polystyrene resin, a syndiotactic polystyrene resin, a polyether ether ketone resin, a polyphenylene sulfide resin, a cycloolefin resin, a liquid crystal polymer resin, and a cellulose resin. It can be produced using one or more selected from the group consisting of resins. Therefore, the alignment film is a polyester film, a polycarbonate film, a polystyrene film, a syndiotactic polystyrene film, a polyether ether ketone film, a polyphenylene sulfide film, a cycloolefin film, a liquid crystal film, or a film in which a liquid crystal compound is added to a cellulose resin. Can be.

Preferred raw material resins for the alignment film are polycarbonate and / or polyester, syndiotactic polystyrene. These resins are excellent in transparency as well as thermal and mechanical properties, and retardation can be easily controlled by stretching. Polyesters typified by polyethylene terephthalate and polyethylene naphthalate are preferable because they have a large intrinsic birefringence and a large retardation can be obtained relatively easily even if the film thickness is thin. In particular, polyethylene naphthalate has a large intrinsic birefringence among polyesters, and is therefore suitable for cases where it is desired to make the retardation particularly high or when it is desired to reduce the film thickness while keeping the retardation high. A more specific method for producing an oriented film will be described later, using a polyester resin as a typical example.

<Manufacturing method of alignment film>
Hereinafter, a method for producing an oriented film will be described using a polyester film as an example. 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 high retardation alignment film may be stretched at an angle of 45 degrees.

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. The longitudinal stretching 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.

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.

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

<Image display cell and light source>
The image display device may typically include a liquid crystal cell or an organic EL cell as the image display cell. Further, the image display device preferably has a white light source having a continuous and wide emission spectrum from the viewpoint of suppressing rainbow spots. When the image display device includes a liquid crystal cell, it is preferable that the image display device includes such a light source as a light source independent of the image display cell. On the other hand, in the case of an organic EL cell, since it itself has a function of a light source, it is preferable that the organic EL cell itself emits light having a continuous and wide emission spectrum. The method and structure of the light source having a continuous and wide emission spectrum are not particularly limited, and may be, for example, an edge light method or a direct type method. The "continuous and wide emission spectrum" means an emission spectrum in which there is no wavelength region in which the light intensity becomes zero in a wavelength region of at least 450 to 650 nm, preferably in the visible light region. The visible light region is, for example, a wavelength region of 400 to 760 nm, and may be 360 to 760 nm, 400 to 830 nm, or 360 to 830 nm.

Examples of the white light source having a continuous and wide emission spectrum include a white light emitting diode (white LED). White LEDs include phosphor type (that is, an element that emits white light by combining a phosphor with a light emitting diode that emits blue light using a compound semiconductor or ultraviolet light) and an organic light-emitting diode. : OLED) and the like. White light consisting of a blue light emitting diode using a compound semiconductor and a yttrium aluminum garnet yellow phosphor combined from the viewpoint of having a continuous and wide emission spectrum and excellent luminous efficiency. Light emitting diodes are preferred.

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.

As the organic EL cell, an organic EL cell known in the art can be appropriately selected and used. The organic EL cell is a light emitting body (organic electroluminescence light emitting body), and typically has a structure in which a transparent electrode, an organic light emitting layer, and a metal electrode are laminated in this order on a transparent base material. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, and such a laminate. Examples thereof include a laminate of an electron injection layer composed of a light emitting layer and a perylene derivative and the like. As described above, since the organic EL cell has both a function as an image display cell and a function as a light source, when the image display device includes the organic EL cell, an independent light source is unnecessary. That is, the light source and the image display device in the image display device may be independent of each other or may be in an integrated form as long as their functions are exhibited.

When an organic EL cell is used as the image display cell, a polarizing plate in the image display device is not essential. However, since the thickness of the organic light emitting layer is as thin as about 10 nm, the external light is reflected by the metal electrode and emitted to the visual recognition side again, and when visually recognized from the outside, the display surface of the organic EL display device looks like a mirror surface. May be visible. In order to shield such specular reflection of external light, it is preferable to provide a polarizing plate and a quarter wave plate on the visible side of the organic EL cell. Therefore, when the image display device has an organic EL cell and a polarizing plate, the liquid crystal cell (4) in FIG. 1 is considered as an organic EL cell, and the viewing side polarizing plate (5) is considered as a polarizing plate. The positional relationship of the alignment film in the apparatus (1) can be applied as it is.

<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 protective film on the visual side of the viewing-side polarizing element (visual-side polarizing element protective film) can be an alignment film or any film conventionally used as a polarizing element protective film, but is not limited thereto.

The type of the protective film on the light source side of the polarizing element on the viewing side and the protective film on the polarizing element on the light source side are 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, cyclic olefin film (for example, norbornene film), polypropylene film, polyolefin film (for example, TPX) and the like. It is preferable to use one or more non-polyrefractive films selected from the group consisting of.

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 image 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, as the base film, an alignment film or a rigid plate such as another film or a glass plate conventionally used as a base film 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 × 10 3 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 touch panel preferably has one or more anti-scattering films as the transparent substrate. As the shatterproof film, an alignment film or various films conventionally used as a 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 alignment 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 alignment 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 alignment 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.

An image display device equipped with a touch panel having the configuration shown in the section "Configuration of image display device" below is manufactured, and a polarizing film is arranged on the surface on the viewing side so as to be parallel to the surface on the viewing side to display a white image. It was. While maintaining the parallel state, the white image was viewed from the front through the polarizing film while rotating the polarizing axis of the polarizing film 360 degrees to confirm the presence and degree of rainbow spots, and the evaluation was made according to the following criteria.

<Evaluation criteria>
⊚: No rainbow spots are observed when observed from the front.
◯: When observed from the front, weak rainbow spots are observed.
X: When observed from the front, a strong rainbow spot is observed.

<Configuration of image display device>
(1) Backlight light source: White LED or cold cathode tube (2) Image display cell: Liquid crystal cell (3) Visualizing side polarizing plate: Polarizing plate in which TAC films are laminated on both sides of a polarizing element made of PVA and iodine (4) Light source side shatterproof film: One or two of the following alignment films A to C were used (see Table 4 below). When two alignment films were used, they were bonded so that their orientation principal axes were parallel to each other.

Orientation film A
PET resin pellets having an intrinsic viscosity of 0.62 dl / g were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours, then supplied to an extruder and dissolved at 285 ° C. This polymer is filtered through a stainless steel sintered filter medium (nominal filtration accuracy of 10 μm particles 95% cut), extruded into a sheet from the base, and then placed on a casting drum with a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and cooled and solidified to make an unstretched film.

The unstretched film 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 30 seconds, and further subjected to a relaxation treatment of 3% in the width direction to obtain a uniaxially oriented oriented film A having a film thickness of about 100 μm. It was. The retardation value was 10200 nm. The Rth was 13233 nm and the Re / Rth ratio was 0.771.

Orientation film B
By changing the thickness of the unstretched film, a uniaxially oriented oriented film B was obtained in the same manner as the oriented film A except that the film thickness was set to about 80 μm. The retardation value was 8300 nm.

Orientation film C
A uniaxially oriented oriented film C was obtained in the same manner as the oriented film A except that the thickness of the unstretched film was changed to about 50 μm. The retardation value was 5200 nm. The Rth was 6600 nm and the Re / Rth ratio was 0.788.

(5) Touch panel: A resistance film type touch panel manufactured by using ITO glass in which a transparent conductive layer made of ITO is provided on a glass base material.

(6) Visible side shatterproof film: One or two of the following alignment films 1 to 5 were used (see Table 4 below). When two alignment films were used, they were bonded so that their orientation principal axes were parallel to each other.

Orientation film 1
An oriented film 1 having a retardation value of 10200 nm was obtained in the same manner as the oriented film A. The Rth was 13233 nm and the Re / Rth ratio was 0.771.

Orientation film 2
In the same manner as the alignment film B, an alignment film 2 having a retardation value of 8300 nm was obtained.

Orientation film 3
By changing the thickness of the unstretched film, a uniaxially oriented oriented film 3 was obtained in the same manner as the oriented film A except that the film thickness was set to about 65 μm. The retardation value was 6600 nm.

Orientation film 4
An oriented film 4 having a retardation value of 5200 nm was obtained in the same manner as the oriented film C. The Rth was 6600 nm and the Re / Rth ratio was 0.788.

Orientation film 5
The unstretched film is heated to 105 ° C. using a heated roll group and an infrared heater, then stretched 2.0 times in the traveling direction by the roll group having a peripheral speed difference, and then stretched 2.0 times in the traveling direction, and then in the same manner as the alignment film A. A biaxially oriented oriented film 5 having a film thickness of about 50 μm was obtained in the same manner as the oriented film A except that the film was stretched 4.0 times in the width direction. The retardation value was 3200 nm. The Rth was 7340 nm and the Re / Rth ratio was 0.436.

The light source side shatterproof film and the visible side shatterproof film were arranged so that the angle formed by the alignment main axis of the alignment film having the higher retardation and the polarization axis of the viewing side polarizer was 45 degrees. Further, the alignment film having the lower retardation value is arranged so that the angle formed by the alignment spindle of the alignment film and the alignment spindle of the alignment film having the higher retardation is 30 degrees, and the rainbow spot evaluation (◎, ○) is performed. , ×) was performed. In addition, the test No. In No. 13, the two alignment films used as the light source side shatterproof film were arranged so that the angle formed by the alignment principal axes was 7 degrees. In addition to the above rainbow spot evaluation, the rainbow spot was evaluated while rotating the alignment film on the visual side without fixing it.

The retardation (Re) was measured as follows. That is, the orientation spindle direction of the film was determined using two polarizing plates, and a rectangle of 4 cm × 2 cm was cut out so that the orientation spindle directions were orthogonal to each other, and used as a measurement sample. For this sample, the refractive indexes (Nx, Ny) of the two axes orthogonal to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractive index meter (NAR-4T manufactured by Atago Co., Ltd.), and the refractive indexes of the two axes were obtained. The absolute value of the difference (| Nx-Ny |) was determined 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. Further, 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 perform thickness direction retardation (ΔNyz × d). Rth) was calculated.

The evaluation results are shown in Table 2 below.

As shown in Table 2 above, when two alignment films having a retardation of 3000 nm or more are provided on the viewing side of the polarizing element on the viewing side and the retardation of each alignment film is the same, clear rainbow spots occur and the visibility is visible. Was confirmed to decrease significantly. On the other hand, it was confirmed that the occurrence of iridescent spots was suppressed by making a difference of 1800 nm or more in the retardation values of the two alignment films, and the effect became remarkable by increasing the difference in retardation. Further, if the retardation difference between the two oriented films is about 3500 nm or more, particularly 4000 nm or more, the rainbow spots are not conspicuous even if the angle formed by the orientation principal axis of the two oriented films is 45 degrees, and the film further. It was confirmed that the rainbow spots were not noticeable even if the orientation angle was increased. When the retardation difference between the two oriented films was 1700 nm or less, it was confirmed that the rainbow spots were inconspicuous when the angle of the orientation principal axis of both films was 20 degrees or less, and less noticeable when the angle was 15 degrees or less.

When the angle formed by the alignment spindles of the two alignment films is 20 to 45 degrees, the rainbow spots should not be conspicuous if the formula "the angle (degree) ≤ 0.00667 x retardation difference +13" is satisfied. It was shown that rainbow spots can be suppressed more effectively by satisfying "the angle (degree) ≤ 0.00667 x retardation difference +23".

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 (8)

Image display cell,
A polarizing element arranged on the viewing side of the image display cell, and two alignment films having a retardation of 3000 nm or more and 150,000 nm or less on the viewing side of the polarizing element.
Have,
Oriented films of two above, have different retardation from each other, the difference is Ri der than 1900 nm,
The angle formed by the orientation spindles of the two alignment films is 0 degrees ± 20 degrees or less.
The image display apparatus (however, the image display equipment angular orientation main axis to form the two alignment films is not more than 0.5 degrees, and the orientation film having a retardation of more than 3000nm the viewing side of the polarizer (Excluding image display devices in which three or more sheets are stacked ). Image display cell,
A polarizing element arranged on the viewing side of the image display cell, and two alignment films having a retardation of 3000 nm or more and 150,000 nm or less on the viewing side of the polarizing element.
Have,
The two oriented films have different retardations, and the difference is 1900 nm or more.
At least one of the two alignment films, angle and its orientation main axis and the polarization axis of the viewing side polarizer formed is not more than 45 degrees ± 30 degrees,
The angle formed by the orientation spindles of the two alignment films is 0 degrees ± 20 degrees or less.
The image display apparatus (however, the image display equipment angular orientation main axis to form the two alignment films is not more than 0.5 degrees, and the orientation film having a retardation of more than 3000nm the viewing side of the polarizer (Excluding image display devices in which three or more sheets are stacked ). Image display cell,
A polarizing element arranged on the viewing side of the image display cell, and two alignment films having a retardation of 3000 nm or more and 150,000 nm or less on the viewing side of the polarizing element.
Have,
The two oriented films have different retardations, and the difference is 1900 nm or more.
Oriented films of two above, angle and its orientation main axis and the polarization axis of the viewing side polarizer formed is not more than 45 degrees ± 30 degrees,
The angle formed by the orientation spindles of the two alignment films is 0 degrees ± 20 degrees or less.
The image display apparatus (however, the image display equipment angular orientation main axis to form the two alignment films is not more than 0.5 degrees, and the orientation film having a retardation of more than 3000nm the viewing side of the polarizer (Excluding image display devices in which three or more sheets are stacked ). The image display apparatus according to claim 1 (excluding the image display equipment corner the two orientation main axis of the oriented film is formed is not more than 1 degree). The image display apparatus according to claim 1 (excluding the image display equipment angular orientation main axis to form the two alignment films is not more than 3 degrees). The image display device according to any one of claims 1 to 5 , wherein the difference in retardation between the two alignment films is 3500 nm or more. The image display device according to any one of claims 1 to 6 , wherein the image display device has a white light source having a continuous emission spectrum. The image display device according to any one of claims 1 to 6 , wherein the image display device has a white light emitting diode.

Images