JP5370601B1 - Image display device - Google Patents

Abstract

An image display device with improved visibility is provided.
(1) A white light source 2 having a continuous emission spectrum, (2) an image display cell 4, (3) a polarizer 5 disposed on the viewing side from the image display cell 4, and (4) the above And at least two alignment films disposed on the viewer side of the polarizer 5, and one of the at least two alignment films is a film (high retardation alignment film) having a retardation of 3000 nm to 150,000 nm. The high retardation oriented film is an image display device arranged on the light source side from at least one of the remaining oriented films.
[Selection] Figure 1

Description

  The present invention relates to an image display device.

  Image display devices are widely used 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 image display devices become smaller and lighter, their use is no longer limited to offices and indoors, but is also being used outdoors and while moving by car or train.

  Under such circumstances, the opportunity to visually recognize the image display device through a polarizing filter such as sunglasses is increasing. In connection with the use of such a layer display device, Patent Document 1 discloses that when a polymer film having a retardation of less than 3000 nm is used on the viewing side from the viewing side polarizing plate of the liquid crystal display device, the polarizing plate is passed through. It has been reported that a strong interference color appears when the screen is observed. Patent Document 1 describes, as means for solving the above-described problem, that the retardation of the polymer film used on the viewing side from the viewing side polarizing plate is 3000 to 30000 nm.

WO2011 / 058774

  As described above, in Patent Document 1, when the liquid crystal display device is viewed with sunglasses by controlling the retardation of the polymer film used on the viewing side from the polarizing plate on the viewing side of the liquid crystal display device to 3000 to 30000 nm. It is described to eliminate the appearance of interference colors. That is, Patent Document 1 describes that the appearance of the interference color is eliminated by replacing the viewing-side oriented film with the oriented film having a specific retardation from the viewing-side polarizing plate. However, many of the films currently in circulation are films having a retardation value of less than 3000 nm, and there is a problem that such a film cannot be used for an image display device. Therefore, the present invention makes it possible to use a general-purpose oriented film having a retardation value of less than 3000 nm, and visibility due to interference colors (ie, rainbow spots) when viewed through a polarizing film such as sunglasses. It aims to improve the decline of

  The inventors of the present invention have conducted research day and night in order to solve the above problems, and by combining an alignment film in which the retardation is not particularly controlled and an alignment film in which the retardation is controlled to 3000 nm or more and 150,000 nm or less, It was found that a solution is possible. The present inventors have made further studies and improvements based on such knowledge, and have completed the present invention.

The representative present invention is as follows.
Item 1.
(1) a white light source having a continuous emission spectrum;
(2) Image display cell,
(3) A polarizer disposed on the viewer side from the image display cell, and (4) At least two alignment films disposed on the viewer side from the polarizer,
Have
One of the at least two oriented films is a film having a retardation of 3000 nm to 150,000 nm (high retardation oriented film),
The high retardation alignment film is disposed on the light source side from at least one of the remaining alignment films.
Image display device.
Item 2.
Item 2. The image display device according to Item 1, wherein the high retardation alignment film is disposed such that an alignment principal axis is 45 degrees with respect to a polarization axis of the polarizer.
Item 3.
Item 3. The image display device according to Item 1 or 2, wherein the white light source having the 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, a reduction in image quality typified by rainbow spots that occur when viewed 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 apparatus provided with the touch panel. It is a chart which shows the visibility measured about the case where the angle which the polarization axis of a visual recognition side polarizer and the polarization axis of a polarizing filter form is 0 degree. In FIG. 2, (I) to (V) are as follows: (I) No iris is seen regardless of the viewing angle, (II) When viewed from the front, the iris is not noticeable There is no, but a thin rainbow appears when viewed from an oblique direction. (III) A thin rainbow appears when viewed from the front. (IV) A remarkable rainbow appears when viewed from the front. (V) Luminance. The screen appears dark due to a drop in the. It is a chart which shows the visibility measured about the case where the angle which the polarization axis of a visual recognition side polarizer and the polarization axis of a polarizing filter form is 45 degrees. In FIG. 3, (I) to (V) are as follows: (I) No iris is seen regardless of the viewing angle, (II) When viewed from the front, the iris is not noticeable There is no, but a thin rainbow appears when viewed from an oblique direction. (III) A thin rainbow appears when viewed from the front. (IV) A remarkable rainbow appears when viewed from the front. (V) Luminance. The screen appears dark due to a drop in the. It is a chart which shows the visibility measured about the case where the angle which the polarization axis of a visual recognition side polarizer and the polarization axis of a polarizing filter form is 90 degrees. In FIG. 4, (I) to (V) are as follows: (I) No iris is seen regardless of the viewing angle, (II) When viewed from the front, the iris is not noticeable There is no, but a thin rainbow appears when viewed from an oblique direction. (III) A thin rainbow appears when viewed from the front. (IV) A remarkable rainbow appears when viewed from the front. (V) Luminance. The screen appears dark due to a drop in the.

  An image display device typically includes 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. A typical schematic diagram of an image display apparatus using a liquid crystal cell as an image display cell is shown in FIG.

  The liquid crystal display device (1) includes 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 the human visually recognizes the image) is referred to as the “viewing side”, and the side opposite to the viewing side (that is, normally in the liquid crystal display device, the backlight The side on which the light source called the light source is set) is called the “light source side”. In FIG. 1, the right side is the viewer side, and the left side is the light source side.

  A polarizing plate (a light source side polarizing plate (3) and a viewing side polarizing plate (5)) is provided on both the light source side and the viewing side of the liquid crystal cell (4). Each polarizing plate (3, 5) typically has a structure in which polarizer protective films (9a, 9b, 10a, 10b) are laminated on both sides of a film called a polarizer (7, 8). In the image display device (1) of FIG. 1, a touch panel (6) is provided as a functional layer on the viewing side from the viewing side polarizing plate (5). The touch panel shown in FIG. 1 is a resistive film type 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). Moreover, the scattering prevention film (14, 15) which is a transparent base | substrate is provided in the light source side and visual recognition side of the touchscreen (6) through the contact bonding layer.

  In addition, in FIG. 1, although the touch panel (6) was described as a functional layer provided in the visual recognition side of a visual recognition side polarizing plate (5), it is not limited to a touch panel, What is a layer which has a film? It may be a layer. In addition, although a resistive film type touch panel has been described as the touch panel, other types of touch panels such as a projected capacitance type can be used. The touch panel in FIG. 1 has a structure having two transparent conductive films, but the structure of the touch panel is not limited to this. For example, even if the number of transparent conductive films and / or anti-scattering films is one. Good. In the liquid crystal display device (1), the anti-scattering film does not necessarily have to be arranged on both sides of the touch panel (6), and may be arranged on either side, or the anti-scattering film is not arranged on both sides. It may be configured. The scattering prevention film may be disposed on the touch panel via the adhesive layer, or may be disposed on the touch panel without the adhesive layer.

<Position relationship of oriented film>
In the image display device, an oriented film can be used for various purposes. In this document, the oriented film means a polymer film having birefringence. From the viewpoint of improving visibility, the image display device includes at least two oriented films, and at least one of the oriented films is preferably a film having a retardation of 3000 nm or more and 150,000 nm or less (high retardation oriented film). . Moreover, the retardation of the remaining oriented film is not particularly limited, but at least one oriented film is preferably a film having a retardation of less than 3000 nm (low retardation oriented film). In the liquid crystal display device of FIG. 1, the alignment film is typically a film on the viewing side of a polarizer (8) (hereinafter referred to as “viewing side polarizer”) on the viewing side from the liquid crystal cell (4). That is, the polarizer protective film (10b) (hereinafter referred to as "viewing side polarizer protective film") on the viewing side from the viewing side polarizer (8), and the transparent conductive film (11 on the light source side from the spacer (13). ) Base film (11a) (hereinafter referred to as “light source side base film”), base film (12a) of transparent conductive film (12) located on the viewer side from the spacer (13) (hereinafter referred to as “visual check”). A side-side base film ”, a scattering prevention film (14) between the viewing-side polarizer protective film (10b) and the light source-side base film (11a) (hereinafter referred to as“ light source-side scattering prevention film ”). And shatterproof film (15) on the viewing side from the visible side substrate film 12a (hereinafter, referred to as "viewing side shatterproof film") may be used.

  The position where the high retardation alignment film and the low retardation alignment film are provided is not particularly limited as long as it is on the viewing side from the viewing side polarizer (8), but the high retardation orientation film is provided on the light source side from the low retardation orientation film. Is preferred. When the high retardation alignment film is provided on the light source side from the low retardation alignment film, the positions of both films are not particularly limited as long as this relationship is maintained. For example, as shown in Table 1 below in the liquid crystal display device of FIG. Can be arranged.

  As above-mentioned, when a high retardation oriented film exists in a light source side from a low retardation oriented film, the specific position of a mutual film is not restrict | limited. Further, the above is merely an example, and other combinations may be used. For example, in the above, the scattering prevention film may be any other functional film that can be provided in the image display device. In this document, when a plurality of oriented films (film groups) are used for a single member, they are regarded as one film. Here, the member is different from the functional and / or objective viewpoints of a polarizer protective film, a light source side scattering prevention film, a light source side base film, a visual recognition side base film, a visual recognition side scattering prevention film, and the like. It means what is judged as a member.

  Assume that the angle formed by the orientation axis of the low retardation oriented film and the polarization axis of the viewing side polarizer (axis parallel to the oscillation direction of the outgoing polarized light) (the low retardation oriented film and the polarizer are in the same plane) ) Is optional. In the case where the low retardation alignment film is disposed on the light source side from the high retardation alignment film, it is desirable from the viewpoint of suppressing rainbow spots that the alignment principal axis of the low retardation alignment film is substantially parallel to the polarization axis of the viewing side polarizer, As the angle formed by the alignment main axis and the polarization axis deviates from substantially parallel or substantially perpendicular, rainbow spots tend to occur. However, when the low retardation alignment film is arranged on the viewer side from the high retardation alignment film, the problem of the occurrence of rainbow spots depending on the relationship between the orientation main axis of the low retardation alignment film and the polarization axis of the viewer side polarizer. There is virtually no. From such a viewpoint, it is preferable to arrange the low retardation oriented film on the viewer side from the high retardation oriented film.

  The angle formed by the alignment axis of the high retardation alignment film and the polarization axis of the viewing side polarizer (assuming that the high retardation alignment film and the polarizer are in the same plane) is not particularly limited, but reduces rainbow spots. From the viewpoint of making it, it is preferably close to 45 degrees. For example, the angle is preferably 45 ° ± 25 ° or less, and preferably 45 ° ± 20 ° or less. In particular, the angle is preferably 45 ° ± 15 from the viewpoint of reducing rainbow spots when the image display device is observed from an oblique direction through a polarizing film such as sunglasses, and making the angle dependency of the low retardation alignment film smaller. Or less, preferably 45 ° ± 10 ° or less, preferably 45 ° ± 5 ° or less, preferably 45 ° ± 3 ° or less, 45 ° ± 2 ° or less, 45 ° ± 1 ° or less, 45 °. In this document, the term “below” means that only the value following “±” is applied. That is, “45 degrees ± 15 degrees or less” means that a fluctuation in the range of 15 degrees above and below 45 degrees is allowed.

  Arranging the high retardation alignment film so as to satisfy the above conditions is, for example, a method of arranging the cut high retardation alignment film such that the alignment main axis is at a specific angle with the polarizer, or high retardation. It can be performed by a method of arranging the alignment film so as to be at a specific angle with the polarizer by obliquely stretching.

  In particular, a polarizing plate used in a liquid crystal display device such as a personal computer is often arranged such that its polarization axis is at an angle of 45 degrees rather than a position parallel to the vertical or horizontal direction of the screen. In a general mode in which the image display device is viewed from obliquely laterally, it is preferable that the orientation axis of the high retardation oriented film is arranged in a 45 ° relationship with the polarization axis so that it is parallel to the vertical direction of the screen. Modes in which the image display device is often viewed from a vertical direction (for example, a mode in which the screen is viewed by looking up at the display, and a mode in which a screen installed horizontally on the ground at a waist level is viewed from a diagonally upper position) Then, it is preferable to arrange | position with a 45-degree relationship with a polarizing axis so that the orientation main axis | shaft of a highly retardation oriented film may become parallel to the horizontal direction of a screen. By doing so, it is possible to further reduce rainbow spots when the image display device is observed from an oblique direction through a polarizing film such as sunglasses.

  The image display device may include two or more high retardation alignment films. When the image display device includes two or more high retardation alignment films, the position at which the two high retardation alignment films are provided is not particularly limited. When both of the two high retardation alignment films are provided on the light source side from the low retardation alignment film, the alignment main axes of the two high retardation alignment films are preferably close to each other. For example, the angle formed by the orientation main axes of the two high retardation oriented films is preferably 0 ° ± 15 °, preferably 0 ° ± 10 °, preferably 0 ° ± 5 °, preferably 0 ° ± 3 °, It is preferably 0 ° ± 2 °, preferably 0 ° ± 1 °, preferably 0 °. When deviating from the substantially parallel relationship, the retardation difference between the two high retardation oriented films is preferably 1800 nm or more, preferably 2500 nm or more, preferably 3500 nm or more, preferably 4000 nm or more, preferably 5000 nm or more.

  The image display device may include two or more low retardation alignment films. When the image display device includes two or more low retardation alignment films, the position at which the two retardation films are provided is not particularly limited. Particularly preferred is the case where the orientation principal axes of two or more low retardation oriented films are substantially parallel and the orientation principal axes of the high retardation oriented films are substantially parallel.

<Retardation of oriented film>
The retardation of the high retardation oriented film is preferably 3000 nm or more and 150,000 nm or less from the viewpoint of reducing rainbow spots. The lower limit value of the retardation of the high retardation oriented film is preferably 4500 nm or more, preferably 6000 nm or more, preferably 8000 nm or more, preferably 10,000 nm or more. On the other hand, the upper limit of the retardation of the high retardation oriented film is that even if an oriented film having a retardation higher than that is used, the effect of improving the visibility is not substantially obtained, and the orientation depends on the height of the retardation. Since the thickness of the film also 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 also be higher. When the image display device has two or more high retardation alignment films, the retardations may be the same or different.

  From the standpoint of more effectively suppressing rainbow spots, the high retardation oriented film has a ratio (Re / Rth) of the retardation (Re) and thickness direction retardation (Rth) of preferably 0.2 or more, Preferably it is 0.5 or more, preferably 0.6 or more. Thickness direction retardation means an average value of retardation obtained by multiplying two birefringences ΔNxz and ΔNyz by film thickness d when viewed from a cross section in the film thickness direction. As Re / Rth is larger, the birefringence action is more isotropic, and the generation of rainbow spots on the screen can be more effectively suppressed. In this document, when simply described as “retardation”, it means in-plane retardation.

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

  The retardation of the low retardation oriented film is not particularly limited as long as it is less than 3000 nm. The lower limit of the retardation of the low retardation oriented film is 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 from the viewpoint that rainbow spots may occur when used alone. In addition, the upper limit of the retardation of the low retardation oriented film is less than 3000 nm, less than 2500 nm, or less than 2300 nm from the viewpoint that the iris can be suppressed in combination with the high retardation oriented film. When the image display device has two or more low retardation oriented films, the retardations may be the same or different. When the retardation of the low retardation oriented film is 2500 nm or more, the difference in retardation value from the high retardation oriented film is preferably 1800 nm or more.

  The retardation of the oriented film can be measured according to a known method. Specifically, it can be determined by measuring the refractive index and thickness in the biaxial direction. Moreover, it can also obtain | require using the commercially available automatic birefringence measuring apparatus (For example, KOBRA-21ADH: Oji Scientific Instruments Co., Ltd. make).

  The low retardation oriented film may be a uniaxially oriented film or a biaxially oriented film, but is preferably a biaxially oriented film from the viewpoint of reducing the ease of tearing of the film.

  The high retardation alignment film can be produced by appropriately selecting a known method. For example, high retardation alignment films include polyester resins, polycarbonate resins, polystyrene resins, syndiotactic polystyrene resins, polyether ether ketone resins, polyphenylene sulfide resins, cycloolefin resins, liquid crystalline polymer resins, and cellulosic resins. It can be produced using one or more selected from the group consisting of added resins. Therefore, high retardation alignment film is a polyester film, polycarbonate film, polystyrene film, syndiotactic polystyrene film, polyetheretherketone film, polyphenylene sulfide film, cycloolefin film, liquid crystalline film, and liquid crystal compound added to cellulose resin. Film.

  A preferred raw material resin for the high retardation oriented film is polycarbonate and / or polyester and syndiotactic polystyrene. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the 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 relatively large retardation can be obtained even when the film thickness is thin. In particular, polyethylene naphthalate has a large intrinsic birefringence among polyesters, and therefore is suitable for a case where it is desired to make the retardation particularly high or a case where it is desired to reduce the film thickness while keeping the retardation high. A more specific method for producing a high retardation oriented film will be described later using a polyester resin as a representative example.

  The low retardation alignment film can be produced by appropriately selecting a known method. For example, low retardation alignment films include polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin (polyethylene resin, polypropylene resin, cyclic polyolefin, etc.), (meth) acrylic resin, polychlorinated resin. A resin selected from the group consisting of a vinyl resin, a polyvinylidene chloride resin, a polystyrene resin, a polyvinyl alcohol resin, a polyarylate resin, a polyphenylene sulfide resin, a cellulose acetate resin (such as triacetyl cellulose) and the like can be obtained as a raw material. Among these, polyester resins and polyolefin resins are preferable, polyester resins are preferable, and polyethylene terephthalate and / or polypropylene resins are more preferable.

<Method for producing oriented film>
Below, the manufacturing method of the oriented film containing a high retardation oriented film and a low retardation oriented film is demonstrated to a polyester film as an example. The polyester film can be obtained by condensing an arbitrary dicarboxylic acid and 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, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalate Acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, Dimer , It may be mentioned sebacic acid, suberic acid, dodecamethylene dicarboxylic 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, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone and the like can be mentioned.

  Each of the dicarboxylic acid component and the diol component constituting the polyester film may be used alone or in combination of two or more. Specific polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., preferably polyethylene terephthalate and polyethylene naphthalate, preferably polyethylene terephthalate. . The polyester resin may contain other copolymer components. From the viewpoint of mechanical strength, the proportion of the copolymer components is preferably 3 mol% or less, preferably 2 mol% or less, more preferably 1.5 mol% or less. . These resins are excellent in transparency and excellent in thermal and mechanical properties. Moreover, retardation of these resins can be easily controlled by stretching.

  The polyester film can be obtained according to a general production method. Specifically, the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then in the transverse direction by a tenter. An oriented polyester film is mentioned by extending | stretching and heat-processing. The polyester film may be a uniaxially stretched film or a biaxially stretched film. The high retardation oriented film may be stretched at an angle of 45 degrees.

  Manufacturing conditions for obtaining a 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 draw ratio is usually 1.0 to 3.5 times, preferably 1.0 to 3.0 times. The transverse draw 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, it becomes easier to obtain a higher retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is higher, the stretching temperature is lower, and the film is thicker. On the contrary, it becomes easier to obtain a lower retardation as the stretching ratio between the longitudinal stretching and the lateral stretching is lower, the stretching temperature is higher, and the film thickness is thinner. Moreover, the higher the stretching temperature and the lower the total stretching ratio, the easier it is to obtain a film having a lower ratio of retardation to thickness direction (Re / Rth). Conversely, a film having a higher ratio of retardation to thickness direction retardation (Re / Rth) can be obtained as the stretching temperature is lower and the total stretching ratio is higher. Furthermore, the heat treatment temperature is usually preferably 140 to 240 ° C, and preferably 180 to 240 ° C.

  In order to suppress the fluctuation of the retardation in the polyester film, it is preferable that the thickness unevenness of the film is small. If the longitudinal stretching ratio is lowered to make a retardation difference, the value of the longitudinal thickness unevenness may be increased. Since there is a region where the value of the vertical thickness unevenness 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, more preferably 4.5% or less, still more preferably 4.0% or less, and 3.0% or less. It is particularly preferred. The thickness unevenness of the film can be measured by any means. For example, a tape-like sample (length: 3 m) continuous in the film flow direction is collected and 100 cm at a 1 cm pitch using a commercially available measuring instrument (for example, an electronic micrometer, Millitron 1240 manufactured by Seiko EM Co., Ltd.). The thickness of the point 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 unevenness (%) = ((dmax−dmin) / d) × 100

<Image display cell and light source>
An image display device may typically include a liquid crystal cell or an organic EL cell as an image display cell. Moreover, it is preferable that an image display apparatus has a white light source which has a continuous and wide light emission spectrum from a viewpoint of suppressing a rainbow spot. When the image display device includes a liquid crystal cell, the image display device preferably 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 the organic EL cell itself has a function of a light source, it is preferable that the organic EL cell itself emits light having a continuous and broad emission spectrum. The method and structure of the light source having a continuous and broad emission spectrum are not particularly limited, and may be, for example, an edge light method or a direct type. “Continuous and broad emission spectrum” means an emission spectrum in which there is no wavelength region where the light intensity becomes zero in the 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.

  As a white light source having a continuous and broad emission spectrum, for example, a white light emitting diode (white LED) can be exemplified. White LEDs include phosphor-type LEDs (that is, elements that emit white light by combining a light emitting diode that emits blue light or ultraviolet light using a compound semiconductor and a phosphor) and organic light emitting diodes (Organic light-emitting diodes). : OLED). A white light-emitting element that combines a blue light-emitting diode using a compound semiconductor with a yttrium, aluminum, and garnet-based yellow phosphor from the viewpoint of having a continuous and broad 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 a 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 alignment (π type) can be appropriately selected and used. Therefore, the liquid crystal cell can be used by appropriately selecting a known liquid crystal material and a liquid crystal made of a liquid crystal material that can be developed in the future. In one embodiment, a preferred liquid crystal cell is a transmissive liquid crystal cell.

  As the organic EL cell, an organic EL cell known in the technical field can be appropriately selected and used. An organic EL cell is a light emitter (organic electroluminescence light emitter), 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 substrate. 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 of an electron injection layer composed of a light emitting layer and a perylene derivative or the like can be given. Thus, since an organic EL cell has a function as an image display cell and a function as a light source, when the image display device includes an 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 from each other or may be integrated as long as their functions are exhibited.

  When an organic EL cell is used as the image display cell, the 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, external light is reflected by the metal electrode and emitted again to the viewing side. When viewed 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 viewing 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 oriented film in the device (1) can be applied as it is.

<Polarizing plate and polarizer protective film>
The polarizing plate has a structure in which both sides of a film-like polarizer are sandwiched between two protective films (sometimes referred to as “polarizer protective film”). As the polarizer, any polarizer (or polarizing film) used in the technical field can be appropriately selected and used. Representative polarizers include those obtained by dyeing a dichroic material such as iodine on a polyvinyl alcohol (PVA) film or the like, but are not limited to this, and are known and will be developed in the future. A polarizer to be obtained can be appropriately selected and used.

  Commercially available products can be used as the PVA film. For example, “Kuraray Vinylon (manufactured by Kuraray Co., Ltd.)”, “Toselo Vinylon (manufactured by Toh Cello Co., Ltd.)”, “Nichigo Vinylon (Nippon Synthetic Chemical Co., Ltd.) The dichroic material includes 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. The stretching 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 known methods.

  As described above, the viewing-side protective film (viewing-side polarizer protective film) of the viewing-side polarizer is an arbitrary film conventionally used as a high retardation oriented film, a low retardation oriented film, or a polarizer protective film. However, it is not limited to these.

  The type of the protective film on the light source side of the viewing side polarizer and the protective film of the light source side polarizer is arbitrary, and a film conventionally used as a protective film can be appropriately selected and used. From the viewpoint of handling and availability, for example, a triacetyl cellulose (TAC) film, an acrylic film, a cyclic olefin-based film (for example, a norbornene-based film), a polypropylene film, a polyolefin-based film (for example, TPX), etc. It is preferable to use one or more films selected from the group consisting of:

  In one embodiment, the light source side protective film of the viewer side polarizer and the viewer side protective film of the light source side polarizer are preferably optical compensation films having an optical compensation function. Such an optical compensation film can be appropriately selected according to each type of liquid crystal. For example, a liquid crystal compound (for example, a discotic liquid crystal compound and / or a birefringent compound) is dispersed in triacetyl cellulose. 1 selected from the group consisting of resin, cyclic olefin resin (for example, norbornene resin), propionyl acetate resin, polycarbonate film resin, acrylic resin, styrene acrylonitrile copolymer resin, lactone ring-containing resin, and imide group-containing polyolefin resin. What can be obtained from more than a seed can be mentioned.

  Since the optical compensation film is commercially available, they can be appropriately selected and used. For example, “Wideview-EA” and “Wideview-T” (made by Fujifilm) for TN system, “Wideview-B” (made by Fujifilm) for VA system, VA-TAC (Konica Minolta, Inc.) ), “ZEONOR FILM” (manufactured by ZEON CORPORATION), “ARTON” (manufactured by JSR), “X-plate” (manufactured by Nitto Denko), and “Z-TAC” (manufactured by FUJIFILM Corporation) for the IPS system ), “CIG” (manufactured by Nitto Denko Corporation), “P-TAC” (manufactured by Okura Kogyo Co., Ltd.), and the like.

  The polarizer protective film can be laminated on the polarizer directly 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 one (that is, an adhesive component dissolved in water or dispersed in water) is preferable. For example, when using a polyester film as a polarizer protective film, a polyvinyl alcohol resin, a urethane resin, or the like is used as a main component, and an isocyanate compound, an epoxy compound, or the like is blended as necessary in order to improve 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 using a film with low moisture permeability such as an acrylic film, a cyclic olefin film, a polypropylene film, or TPX 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, anti-scattering film>
The image display device may include a touch panel. The type and method of the touch panel are not particularly limited, and examples include a resistive touch panel and a capacitive 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, a high retardation oriented film or a low retardation oriented film can be used as the base film. Moreover, when not using these films as a base film, rigid boards, such as another film conventionally used as a base film, or a glass plate, can be used.

  Examples of other films conventionally used as the base film include various resin films having transparency. 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 and polyphenylene sulfide resins can be used. Among these, polyester resins, polycarbonate resins, and polyolefin resins are preferable, and polyester resins are preferable.

  Although the thickness of a base film is arbitrary, the range of 15-500 micrometers is preferable.

  The base film may be subjected to etching treatment or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on the surface in advance. Thereby, adhesiveness with the transparent conductive layer etc. which are provided on a base film can be improved. Moreover, before providing a transparent conductive layer etc., you may remove and clean the surface of a base film by solvent washing | cleaning, ultrasonic washing | cleaning, etc. as needed.

The transparent conductive layer may be directly laminated on the base film, but can be laminated via an easy adhesion layer and / or various other layers. Examples of the other layer include a hard coat layer, an index matching (IM) layer, and a low refractive index layer. As a typical laminated structure of the transparent conductive film, the following 6 patterns can be exemplified, but the invention is not limited thereto.
(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 / Easily adhesive layer / Hard coat layer / IM (Index matching) layer / Transparent conductive layer (5) Base film / Easily adhesive layer / Hard coat layer (High refractive index doubles as IM ) / Transparent conductive layer (6) Base film / Easily adhesive 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 / low refractive index layer (the transparent conductive thin film side is a low refractive index layer), the ITO layer is used when the liquid crystal display screen is viewed. Can be difficult to see. 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 thickness reduction.

  The configurations (3) to (6) are particularly suitable for use in a capacitive touch panel. Moreover, the structure of said (2)-(6) is preferable from a viewpoint that an oligomer can prevent depositing on the surface of a base film, and providing a hard-coat layer also on the other one side of a 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 selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten. A conductive metal oxide of at least one selected metal is used. The metal oxide may further contain a metal atom 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. The transparent conductive layer may be Ag nanowire, Ag ink, a self-organized conductive film of Ag ink, a mesh electrode, CNT ink, or a 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 even more preferably 20 to 30 nm. When the thickness of the transparent conductive layer is 15 nm or more, a good continuous film having a surface resistance of 1 × 10 ³ Ω / □ or less is easily obtained. Moreover, it can be set as a layer with higher transparency as the thickness of a transparent conductive layer is 40 nm or less.

  The transparent conductive layer can be formed according to a known procedure. For example, a vacuum 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 a crystalline transparent conductive layer, it is preferable to form an amorphous film once on a substrate and then heat and crystallize the amorphous film together with a flexible transparent substrate.

  The transparent conductive film of the present invention may be patterned by removing a part of the surface of the transparent conductive layer. The transparent conductive film in which the transparent conductive layer is patterned has a pattern forming part 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 stripe shape, a square shape, and the like.

  The touch panel preferably has one or more scattering prevention films as the transparent substrate. The scattering prevention film may be the above-described high retardation oriented film or low retardation oriented film. Moreover, various films (for example, the transparent resin film described about the said base film) conventionally used as a scattering prevention film can also be used for a scattering prevention film. When two or more anti-scattering films are provided, they may be formed of the same material or different.

  The polarizer protective film, the base film, and the scattering prevention film can contain various additives as long as the effects of the present invention are not hindered. For example, ultraviolet absorbers, inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light proofing agents, flame retardants, thermal stabilizers, antioxidants, anti-gelling agents And surfactants. Moreover, in order to show high transparency, it is also preferable that a polyester film does not contain a particle | grain substantially. “Substantially free of particles” means, for example, in the case of inorganic particles, when the inorganic element is quantified by fluorescent X-ray analysis, the content is 50 ppm or less, preferably 10 ppm or less, particularly preferably the detection limit or less. Means quantity.

  The oriented film may have various functional layers. Examples of such a functional layer include 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 an antiglare layer, an antireflection layer, a low reflection layer, a low reflection antiglare layer, and an antireflection antiglare layer, an effect of improving color spots when observed from an oblique direction can be expected.

  When providing various functional layers, it is preferable to have an easy-adhesion layer on the surface of the oriented 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 that it is close to the geometric mean of the refractive index of the functional layer and the refractive index of the alignment film. The refractive index of the easy-adhesion layer can be adjusted by a known method. For example, the refractive index of the easy-adhesion layer can be easily adjusted by adding titanium, zirconium, or other metal species to the binder resin.

(Hard coat layer)
The hard coat layer only needs to be a layer having hardness and transparency. Usually, various curable properties such as an ionizing radiation curable resin typically cured by ultraviolet rays or an electron beam, and a thermosetting resin cured by heat. What was formed as a cured resin layer of resin is used. In order to appropriately add flexibility and other physical properties to these curable resins, thermoplastic resins and the like may be added as appropriate. Among the curable resins, ionizing radiation curable resins are preferable because they are representative and an excellent hard coating film can be obtained.

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

  Examples of the monomer include monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone; or, for example, trimethylolpropane tri (meth) acrylate, tripropylene glycol di (Meth) 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. These polyfunctional monomers are also used as appropriate. (Meth) acrylate means acrylate or methacrylate.

  When the ionizing radiation curable resin is cured with an electron beam, a photopolymerization initiator is unnecessary, 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, benzoin, benzoin methyl ether, or the like can be used alone or in combination as a photopolymerization initiator. In the case of a cationic polymerization system, an aromatic diazonium salt, aromatic sulfonium salt, aromatic iodonium salt, metatheron compound, benzoin sulfonate, or the like can be used alone or in combination as a 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. 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 for the purpose of adjusting the physical properties as appropriate. Examples of the thermoplastic resin or thermosetting resin include an acrylic resin, a urethane resin, and a polyester resin, respectively.

  In order to impart light resistance to the hard coat layer and prevent discoloration, strength deterioration, cracking, and the like due to ultraviolet rays contained in sunlight, it is also preferable to add an ultraviolet absorber in the ionizing radiation curable resin. When an ultraviolet absorber is added, the ionizing radiation curable resin is preferably cured with an electron beam in order to reliably prevent the ultraviolet coater from inhibiting the curing of the hard coat layer. Examples of the ultraviolet absorber include organic ultraviolet absorbers such as benzotriazole compounds and benzophenone compounds, or inorganic ultraviolet absorbers such as fine particles of zinc oxide, titanium oxide, and cerium oxide having a particle size of 0.2 μm or less, What is necessary is just to select and use from well-known things. The addition amount of the ultraviolet absorber 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. In addition, 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 layer may be appropriately employed, and it 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. These fine particles have a spherical shape, an elliptical shape, 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, and benzoguanamine-formaldehyde beads. The fine particles are usually added in an amount of 2 to 30 parts by mass, preferably about 10 to 25 parts by mass with respect to 100 parts by mass of the resin.

  The above resin for dispersing and holding the antiglare agent is preferably as hard as possible as in the hard coat layer. 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. In addition, it is preferable to add well-known anti-settling agents such as silica to the coating liquid for forming the anti-glare layer in order to prevent precipitation of the anti-glare agent.

(Antireflection layer)
As the antireflection layer, a conventionally known layer may be appropriately employed. In general, the antireflection layer is composed of at least a low refractive index layer, and a low refractive index layer and a high refractive index layer (having a higher refractive index than the low refractive index layer) are alternately laminated adjacently and the surface side has a low refractive index. It consists of multiple layers. Each thickness of the low-refractive index layer and the high-refractive index layer may be an appropriate thickness according to the application, and is about 0.1 μm when adjacent layers are stacked, and about 0.1 to 1 μm when the low-refractive index layer is alone. It is preferable.

  As a low refractive index layer, a layer containing a low refractive index material such as silica or magnesium fluoride in a resin, a layer of a low refractive index resin such as a fluorine-based resin, or a low refractive index material in a low refractive index resin A thin film formed by a thin film forming method (for example, physical or chemical vapor deposition such as vapor deposition, sputtering, CVD, or the like), an oxidation layer, or a layer made of a low refractive index material such as silica or magnesium fluoride. Examples thereof include a film formed by a sol-gel method in which a silicon oxide gel film is formed from a silicon sol solution, or 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 gas inside, fine particles having a porous structure containing gas, etc., and with respect to the original refractive index of the fine particle solid portion, It means fine particles whose refractive index is apparently lowered. Examples of such void-containing fine particles include silica fine particles disclosed in JP-A No. 2001-233611. Examples of the void-containing fine particles include hollow polymer fine particles disclosed in JP-A No. 2002-805031, in addition to inorganic substances such as silica. The particle diameter of the void-containing fine particles is, for example, about 5 to 300 nm.

  As the high refractive index layer, a layer containing a high refractive index material such as titanium oxide, zirconium oxide or zinc oxide in a resin, a layer of a high refractive index resin such as a fluorine-free resin, or a high refractive index material is highly refracted. A layer formed of a high-refractive-index material such as titanium oxide, zirconium oxide, or zinc oxide in a thin film forming method (for example, vapor deposition, sputtering, CVD, etc., physical or chemical vapor deposition) Method).

(Antistatic layer)
As the antistatic layer, a conventionally known layer may be employed as appropriate, and it is generally formed as a layer containing an antistatic layer in a resin. As the antistatic layer, an organic or inorganic compound is used. For example, examples of the antistatic layer of an organic compound include a cationic antistatic agent, an anionic antistatic agent, an amphoteric antistatic agent, a nonionic antistatic agent, and an organometallic antistatic agent. The inhibitor is used not only as a low molecular compound but also as a high molecular compound. As the antistatic agent, conductive polymers such as polythiophene and polyaniline are also used. Further, as the antistatic agent, for example, conductive fine particles made of a metal oxide are used. The particle diameter of the conductive fine particles is, for example, about 0.1 nm to 0.1 μm in average particle diameter 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), AZO (aluminum doped zinc oxide) etc. are mentioned.

  Examples of the resin containing the antistatic layer include curable resins such as ionizing radiation curable resins and thermosetting resins as described in the hard coat layer. When the layer is formed as a layer and the surface strength of the antistatic layer itself is unnecessary, a thermoplastic resin or the like is also used. The thickness of the antistatic layer may be set appropriately, 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 layer may be appropriately employed. Generally, in the resin, a silicon compound such as silicone oil or silicone resin; a fluorine compound such as fluorine surfactant or fluorine resin. It can be formed by a known coating method using a paint containing a stain-proofing agent such as wax. The thickness of the antifouling layer may be set appropriately, and can usually be about 1 to 10 μm.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and is implemented with appropriate modifications within a range that can be adapted to the gist of the present invention. These are all included in the technical scope of the present invention.

Test Example 1: Evaluation of rainbow spots An image display device having a touch panel having the following configuration was produced according to a conventional method, and a polarizing film was placed on the viewing side surface in parallel with the viewing side surface to display a white image. It was. While maintaining the parallel state, change the position of the polarizing film so that the angle formed by the polarizing axis of the polarizing film and the polarizing axis of the viewing side polarizer of the image display device is 0 °, 45 °, or 90 °, At each point, a white image was viewed through a polarizing film to confirm the presence or absence and the extent of rainbow spots, and evaluated according to the following criteria. In addition, the visual side scattering prevention film to be described later was not adhered to the touch panel, and the orientation main axis was rotated 360 degrees while observing the presence or absence of rainbow spots, and it was confirmed whether rainbow spots were observed at all angles. .

<Evaluation criteria>
A: When observed from the front, no rainbow spots are observed.
○: When observed from the front, thin rainbow spots are observed, but there is no problem in visibility.
X: When observed from the front, rainbow spots are observed.

<Configuration of image display device>
(1) Backlight light source: White LED or cold cathode tube (2) Image display cell: Liquid crystal cell (3) Polarizing plate: A polarizing plate using a TAC film as a polarizer protective film for a polarizer composed of PVA and iodine.
(4) Touch panel: Transparent conductive film (viewing side) prepared by providing a transparent conductive layer made of ITO on any of the following oriented films 1 to 5, and a transparent conductive layer made of ITO on a glass substrate A resistive film type touch panel having a structure in which ITO glass (light source side) provided with an electrode is disposed via a spacer.

Oriented film 1
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 with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

  The unstretched film was guided to a tenter stretching machine, and the film was guided to a hot air zone at a temperature of 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film is 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 film 1 having a film thickness of about 100 μm. It was. The retardation value was 10200 nm. Rth was 13233 nm and Re / Rth ratio was 0.771.

Oriented film 2
By changing the thickness of the unstretched film, a uniaxially oriented oriented film 2 was obtained in the same manner as the oriented film 1 except that the thickness of the film was about 80 μm. The retardation value was 8300 nm.

Oriented film 3
By changing the thickness of the unstretched film, a uniaxially oriented alignment film 3 was obtained in the same manner as the alignment film 1 except that the thickness of the film was about 50 μm. The retardation value was 5200 nm. Rth was 6600 nm and Re / Rth ratio was 0.788.

Oriented film 4
The unstretched film is heated to 105 ° C. using a heated roll group and an infrared heater, and then stretched 2.0 times in the running direction by a roll group having a difference in peripheral speed, and then in the same manner as the oriented film 1. A biaxially oriented oriented film 4 having a film thickness of about 50 μm was obtained in the same manner as the oriented film 1 except that the film was stretched 4.0 times in the width direction. The retardation value was 3200 nm. Rth was 7340 nm and Re / Rth ratio was 0.436.

Oriented film 5
In the same manner as in the following oriented film D, an oriented film 5 having a retardation of 1500 nm was obtained.

(5) Anti-scattering film: Any of the following oriented films A to F was used as the visual-side anti-scattering film.

Oriented 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 with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

  The unstretched film was heated to 100 ° C. with a heated roll group and an infrared heater, and then stretched 3.6 times in the longitudinal direction with a roll group having a peripheral speed difference to obtain a uniaxially oriented polyethylene terephthalate film. The uniaxially stretched film was guided to a tenter stretching machine, and the end of the film was held by a clip while being guided to a hot air zone at a temperature of 125 ° C. and stretched 3.8 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. Got. The retardation value was 700 nm.

Oriented film B
Except that the film thickness was about 45 μm, film formation was performed in the same manner as for the alignment film A, whereby an alignment film B was obtained. The retardation value was 1000 nm.

Oriented film C
An oriented film C was obtained by carrying out film formation in the same manner as the oriented film A except that the film thickness was about 60 μm. The retardation value was 1400 nm.

Oriented film D
Except that the film thickness was about 65 μm, film formation was performed in the same manner as for the alignment film A, and an alignment film D was obtained. The retardation value was 1500 nm.

Oriented film E
Except that the film thickness was about 100 μm, film formation was performed in the same manner as for the alignment film A, whereby an alignment film E was obtained. The retardation value was 2300 nm.

Oriented film F
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 with a filter material of stainless sintered body (nominal filtration accuracy 10 μm particles 95% cut), extruded into a sheet form from the die, and then applied to a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method. It was wound and solidified by cooling to make an unstretched film.

  The unstretched film was guided to a tenter stretching machine, and the film was guided to a hot air zone at a temperature of 125 ° C. while being gripped by a clip, and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, the film is processed 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 film F having a film thickness of about 100 μm. It was. The retardation value was 10200 nm. Rth was 13233 nm and Re / Rth ratio was 0.771.

  The retardation (Re) was measured as follows. That is, using two polarizing plates, the orientation principal axis direction of the film was obtained, and a 4 cm × 2 cm rectangle was cut out so that the orientation principal axis directions were orthogonal to each other, and used as a measurement sample. For this sample, the biaxial refractive index (Nx, Ny) perpendicular to each other and the refractive index (Nz) in the thickness direction were determined by an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.). The absolute value of the difference (| Nx−Ny |) was determined as the anisotropy (ΔNxy) of the refractive index. The thickness d (nm) of the film was measured using an electric micrometer (manufactured by Fine Reef, Millitron 1245D), and the unit was converted to nm. Retardation (Re) was determined from the product (ΔNxy × d) of refractive index anisotropy (ΔNxy) and film thickness d (nm).

  Further, Nx, Ny, Nz and 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 obtain a thickness direction retardation ( Rth) was determined.

The evaluation results are shown in Table 2 below. In the image display device, among the oriented films used as the viewing-side base film and the viewing-side scattering prevention film, the film having the higher retardation value has the orientation main axis and the polarizing axis of the viewing-side polarizer. The angle formed was arranged to be 45 degrees (however, in Test No. 4, the angle was set to 40 degrees).
Test No. For No. 12, the film having the higher retardation is arranged so that the angle formed by the orientation main axis and the polarization axis of the viewing side polarizer is 45 degrees, and the orientation axis of the base film is rotated 360 degrees. It was confirmed whether rainbow spots were observed at all angles.

  As shown in Table 2 above, it was confirmed that the formation of rainbow spots was suppressed by providing a high retardation oriented film on the light source side from the low retardation oriented film and using a light source having a continuous emission spectrum. . Further, in the case of taking the above-described configuration, when the low retardation oriented film is disposed on the light source side from the high retardation oriented film, it is caused by the angle formed by the orientation main axis of the low retardation oriented film and the polarization axis of the viewing side polarizer. It was confirmed that the occurrence of rainbow spots can also be suppressed.

  In addition, even when rainbow spots are observed when observing the screen from an oblique direction along the orientation direction of the high retardation oriented film, the screen is seen from an oblique direction along the direction perpendicular to the orientation direction of the orientation axis of the high retardation orientation film. When observed, it was found that the generation of rainbow spots could be suppressed.

Test Example 2: Visibility depending on the angle between the polarization axes of the polarizer and the polarizing filter A high retardation alignment film, a low retardation alignment film, and a polarizing filter are arranged in this order on the viewing side surface of a liquid crystal display device using a white LED as a light source. The angle formed by the polarization axis of the viewing side polarizer and the polarization axis of the polarizing filter (polarization axis-polarization axis angle) was fixed at 0 degree, 45 degrees, or 90 degrees. Then, at each polarization axis-polarization axis angle, an angle formed by the orientation main axis of each orientation film and the polarization axis of the viewing side polarizer while rotating the high retardation orientation film and / or the low retardation orientation film clockwise. The relationship between the orientation main axis-polarization axis angle) and the appearance of rainbow spots was evaluated. The evaluation was performed in the following five stages: (I) No rainbow spots are seen regardless of the viewing angle. (II) When viewed from the front, rainbow spots are not noticeable, but when viewed from an oblique direction. A thin rainbow is visible, (III) a thin rainbow is visible when viewed from the front, (IV) a significant rainbow is visible when viewed from the front, and (V) the screen appears dark due to reduced brightness. . Charts showing the results when the polarization axis-polarization axis angles are 0 degrees, 45 degrees, and 90 degrees are shown in FIGS. 2, 3, and 4, respectively.

  As shown in FIGS. 2 to 4, when the polarization axis-polarization axis angle is 0 degree, 45 degrees, and 90 degrees, the orientation main axis-polarization axis angle for the high retardation oriented film is 45 degrees. In addition, it was confirmed that the iris was suppressed and excellent visibility was obtained regardless of the orientation main axis-polarization axis angle of the low retardation oriented film. In particular, when the orientation main axis-polarization axis angle for the high retardation orientation film is about 30 to 60 degrees, the iris is suppressed and excellent visibility regardless of the orientation principal axis-polarization axis angle for the low retardation orientation film. It was confirmed that When the polarization axis-polarization axis angle is 90 degrees, the orientation main axis-polarization axis angle for the high retardation oriented film is 0 degree or near 90 degrees, and the orientation principal axis-polarization axis angle for the low retardation orientation film. It was confirmed that the screen becomes dark when the angle is around 0 degree or 90 degrees.

  In Test Example 2, even in the region where clear rainbow spots were confirmed, the degree of rainbow spots was significantly reduced as compared with the case where only the low retardation alignment film was used.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Light source 3 Light source side polarizing plate 4 Liquid crystal cell 5 Viewing side polarizing plate 6 Touch panel 7 Light source side polarizer 8 Viewing side polarizer 9a Polarizer protection film 9b Polarizer protection film 10a Polarizer protection film 10b Viewing side polarization Child protective film 11 Light source side transparent conductive film 11a Light source side base film 11b Transparent conductive layer 12 Viewing side transparent conductive film 12a Viewing side base film 12b Transparent conductive layer 13 Spacer 14 Light source side scattering prevention film 15 Viewing side scattering prevention the film

Claims (3)

(1) a white light source having a continuous emission spectrum;
(2) Image display cell,
(3) A polarizer disposed on the viewer side from the image display cell, and (4) At least two alignment films disposed on the viewer side from the polarizer,
Have
One of the at least two oriented films is a film having a retardation of 3000 nm to 150,000 nm (high retardation oriented film),
The high retardation alignment film is disposed on the light source side from at least one of the remaining alignment films ,
At least one oriented film remains, that having a retardation of less than 3000 nm,
Image display device. The image display device according to claim 1, wherein the high retardation alignment film is disposed such that an alignment main axis is 45 degrees with respect to a polarization axis of the polarizer. The image display device according to claim 1, wherein the white light source having the continuous emission spectrum is a white light emitting diode.

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