JP2012022148A - Stereoscopic image display retardation plate, stereoscopic image display polarization element and stereoscopic image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stereoscopic image display device in which the difference in color between the image for right eyes and the image for left eyes is small even in the case in which the images are seen from the oblique direction and to provide a retardation plate and a polarization element used for the device.SOLUTION: In a retardation plate 10 for stereoscopic image formation according to the present invention, a first retardation member 1 having a retardation of 1/2 wavelength only at a first retardation region 11 and a second retardation member 2 having retardation of 1/4 wavelength in the first retardation region and a second retardation region are laminated. In the first retardation region 11, the retardation axis direction of the first retardation member 1 is orthogonal to the retardation axis direction of the second retardation member 2. The first retardation region of the first retardation member and the second retardation member are A plates provided with different symbols.

Description

  The present invention relates to a phase difference plate suitable for displaying a stereoscopic image, and a polarizing element. The present invention also relates to a stereoscopic image display apparatus using the retardation plate and polarizing element.

  As a method for displaying a stereoscopic image, a method has been proposed in which a right-eye image and a left-eye image are made to appear in different polarization states, and this is viewed through stereoscopic glasses consisting of a right-eye lens and a left-eye lens. ing. According to such a method, only the right-eye image is visually recognized by the right eye and only the left-eye image is visually recognized by the left eye, so that the viewer recalls a stereoscopic effect due to binocular parallax. More specifically, a right-eye image having a first polarization state and a left-eye image having a second polarization state are caused to appear from the image display device, and this light is transmitted through the first polarization state. A right-eye lens including a first polarizing plate that blocks (absorbs or reflects) light in the second polarization state; and a second lens that blocks light in the first polarization state and transmits light in the second polarization state. A three-dimensional display becomes possible by visually recognizing through a pair of left-eye lenses equipped with a polarizing plate.

  As a method for causing two types of images having different polarization states to appear from one image display device, for example, in Patent Document 1, the first region and the second region in which the transmission axis directions are orthogonal to each other are used. There has been proposed a method in which a polarizing plate having a close contact with the front surface of a display device.

  Further, a transmission axis of an image appearing in the first region and the second region is obtained by combining a retardation plate having a first region and a second region and a polarizing plate having a uniform transmission axis. A method has been proposed in which the directions are orthogonal to each other. For example, in Patent Document 2, a retardation plate patterned into a first region having a half-wavelength (λ / 2) retardation and a second region having no retardation, and a uniform transmission axis are disclosed. The polarizing plane of the first region and the transmission axis direction of the polarizing plate are arranged at 45 ° by using the polarizing plate having the polarization region of the first region and the polarization direction of the second region. A method has been proposed in which the vibration planes are orthogonal. In Patent Document 3, a retardation plate and a polarizing plate are used, each of which includes a first region in which an optical rotatory element that rotates a vibration plane of polarized light by 90 ° is disposed and a second region in which the optical rotatory element is removed. A method has been proposed.

  According to such a method, for example, a right-eye image is displayed from the first region, and a left-eye image is displayed from the second region, and the polarized light in the first region is transmitted and the light in the second polarization state is blocked. By visually recognizing through the polarizing glasses for stereoscopic vision composed of the left-eye lens including the second polarizing plate whose transmission axis direction is orthogonal to the right-eye lens including the first polarizing plate, Three-dimensional display is possible. However, when two types of orthogonal polarized light appear as the right-eye image and the left-eye image, the transmission axis direction of the right-eye image and the left-eye image and the transmission axis direction of the polarizing plate of the polarizing glasses worn by the viewer are determined. It needs to match exactly. Therefore, if the viewer's position, face angle, or wearing state of polarized glasses are different, the right-eye video and the left-eye video are both viewed and mixed, and the stereoscopic image becomes unclear (such as The phenomenon is called “crosstalk”).

  From this point of view, a method has been proposed in which circularly polarized light (right circularly polarized light and left circularly polarized light) having different polarities in the first region and the second region appears. For example, in Patent Document 4, a first retardation member patterned into a first region having a retardation of half wavelength (λ / 2) and a second region having no retardation, and 4 minutes A laminated retardation plate has been proposed in which a second retardation member having a retardation of one wavelength (λ / 4) is arranged so that both slow axes thereof are orthogonal to each other. In such a laminated retardation plate, the retardation of the first region is + λ / 4, and the retardation of the second region is −λ / 4. Therefore, by laminating the laminated retardation plate and the polarizing plate so that the angle formed by the optical axis direction is 45 °, circularly polarized light having different polarities appears in the first region and the second region. Is done.

JP 58-184929 A JP 2001-59948 A Japanese Patent Laid-Open No. 2002-14301 JP-A-10-227998

  As disclosed in Patent Document 4, when a stereoscopic image is displayed by circularly polarized light having different polarities, it is not necessary to match the axial directions of the image display device and the stereoscopic polarizing glasses. Therefore, crosstalk is suppressed even when the angle of the viewer's face changes or the wearing state of polarized glasses changes.

  On the other hand, stereoscopic video display devices used for applications such as movies, games, and medical monitors are viewed from various angles by a plurality of viewers. However, when a combination of a λ / 4 plate and a patterned λ / 2 plate as described in Patent Document 4 is used, a right-eye image and a left-eye image are obtained when the screen is viewed obliquely. It turned out that there was a difference in the color of the video, leading to fatigue of viewers and screen sickness.

  In view of the above, it is an object of the present invention to provide a phase difference plate and a polarizing element for stereoscopic video display that can suppress the occurrence of a left-right parallax, particularly a color difference, even when the stereoscopic video display device is viewed from an oblique direction. And

  As a result of examination in view of the above problems, in the conventional technique described in Patent Document 4, since the positive A plate is used for both the λ / 4 plate and the λ / 2 plate, the image for the right eye and the left eye are used. It has been found that there is a big difference in the colors of the video for use. That is, in this configuration, when the screen is viewed from an oblique direction, the polarization state deviates from the circularly polarized light, but the deviation from the circularly polarized light becomes large between the right eye image and the left eye image. It was found that a color difference occurred.

  As a result of further investigation based on such knowledge, when a combination of a positive A plate and a negative A plate is used as the λ / 4 plate and the λ / 2 plate, even if the screen is viewed from an oblique direction, λ / 4 It has been found that the difference in color between the right-eye image and the left-eye image is suppressed because the apparent orthogonality of the slow axis direction between the plate and the λ / 2 plate is maintained.

  The present invention has been made based on this finding, and the stereoscopic image forming phase difference plate of the present invention has a plurality of first phase difference regions and a plurality of second phase difference regions. . Both the first retardation region and the second retardation region have a quarter-wave front retardation, and the slow axis direction of the first retardation region and the slow axis direction of the second retardation region And are orthogonal.

  The stereoscopic image forming retardation plate 10 of the present invention has a configuration in which a first retardation member 1 and a second retardation member 2 are laminated. The first retardation member 1 is patterned into a region 1 a having a phase difference and a region 1 b having no phase difference, and the region 1 a corresponds to the first phase difference region 11 of the phase difference plate 10. , Region 1 b corresponds to second retardation region 12 of retardation plate 10. The first retardation member 1 has a half-wave retardation only in the region 1a. The second retardation member 2 has a quarter wavelength retardation in the first retardation region and the second retardation region. In the first phase difference region, the slow axis direction of the first phase difference member and the slow axis direction of the second phase difference member are orthogonal to each other.

  Hereinafter, in the present specification, the first phase difference member position such as “the first phase difference member has a retardation of λ / 2” or “the first phase difference member is a negative A plate” is used. Although there are cases where reference is made to the phase difference characteristics, these are descriptions of the phase difference characteristics of the region 1a having the phase difference of the first phase difference member, unless otherwise specified.

  The first retardation member and the second retardation member are A plates having different signs. That is, one of the first retardation member and the second retardation member is a positive A plate and the other is a negative A plate.

  In the first embodiment of the present invention, the first retardation member is a positive A plate, and the second retardation member 2 is a negative A plate. In the second embodiment of the present invention, the first retardation member is a negative A plate, and the second retardation member is a positive A plate. In any of these forms, in the first retardation region 11 of the retardation plate 10, the positive A plate and the negative A plate are arranged so that the slow axis directions thereof are orthogonal to each other. In the phase difference region 12, only one positive A plate or negative A plate is disposed.

  In the retardation plate of the present invention, it is preferable that the first retardation region 11 and the second retardation region 12 are arranged in a stripe shape.

  The present invention also relates to a stereoscopic image display polarizing element 50 in which the retardation plate 10 and the polarizing plate 20 are laminated. In the polarizing element of the present invention, the angle formed by the slow axis direction 111 in the first retardation region 11 of the retardation plate 10 and the transmission axis direction 201 of the polarizing plate 20 is preferably 45 °.

  Furthermore, the present invention relates to a stereoscopic image display device 80 including the retardation plate 10 or the polarizing element 50. The stereoscopic video display device of the present invention includes the retardation plate 10, the polarizing plate 20, and the video display cell 30. In the stereoscopic video display device of the present invention, the polarizing plate 20 is disposed on the viewing side of the video display cell 30, and the retardation film 10 is disposed on the viewing side of the polarizing plate 20. The angle formed by the slow axis direction of the retardation plate 10 and the transmission axis direction of the polarizing plate is 45 °. The video display cell has a first video display area and a second video display area, and the phase difference plate has a first phase difference area and a second phase difference area that are the first video display of the video display cell. The area and the second video display area are arranged to correspond to each other.

  In the retardation plate of the present invention, both the first retardation region and the second retardation region have a quarter-wave front retardation, and the slow axis directions of both are orthogonal. Therefore, when the polarizing plate is laminated, circularly polarized light having different polarities appears in the first region and the second region, and can be used for stereoscopic image display. Further, in the first phase difference region, the positive A plate and the negative A plate are arranged so that the slow axis directions of both are orthogonal to each other. The orthogonal relationship in the phase axis direction is maintained. Therefore, when the polarizing element in which the retardation plate and the polarizing plate are laminated is viewed from an oblique direction, the polarization state of the first retardation region is prevented from greatly deviating from the circularly polarized light. In a stereoscopic image display device to which such a retardation plate or a polarizing element is applied, the difference in color between the right-eye image and the left-eye image when the screen is viewed from an oblique direction is suppressed.

It is a top view which represents typically the phase difference plate by one Embodiment of this invention. It is typical sectional drawing of the phase difference plate of FIG. 1A. It is sectional drawing which represents typically the polarizing element by one Embodiment of this invention. It is sectional drawing which represents typically the polarizing element by one Embodiment of this invention. It is a perspective view which represents notionally the arrangement | positioning of the polarizing element by one Embodiment of this invention. 1 is a perspective view conceptually showing an arrangement of a stereoscopic video display device according to an embodiment of the present invention. 1 is a cross-sectional view schematically illustrating a stereoscopic image display device according to an embodiment of the present invention. 1 is a cross-sectional view schematically illustrating a stereoscopic image display device according to an embodiment of the present invention. It is a perspective view which represents typically the structure of the polarizing glasses for stereoscopic vision for visually recognizing a stereoscopic image table | surface. It is a figure showing the evaluation result of the hue of white luminance in an example. It is a figure showing the evaluation result of the hue of white luminance in a comparative example. In an Example, it is a figure which represents typically the mode of the change of a polarization state when visually recognizing from the diagonal direction as a locus | trajectory on a Poincare sphere. In a comparative example, it is a figure showing typically a mode of change of a polarization state when visually recognizing from an oblique direction as a locus on a Poincare sphere.

  The present invention will be described below with reference to the drawings. FIG. 1A is a plan view schematically illustrating an embodiment of the retardation plate of the present invention, and FIG. 1B is a schematic cross-sectional view taken along the line IB-IB in FIG. 1A. The retardation plate 10 of the present invention has a plurality of first retardation regions 11 and a plurality of second retardation regions 12.

  As shown in FIG. 1B, the retardation plate 10 of the present invention has a configuration in which a first retardation member 1 and a second retardation member 2 are laminated. The first phase difference member 1 is patterned into a region 1a having a phase difference and a region 1b having no phase difference, and the region 1a and the region 1b are respectively a first phase difference region 11 and a second phase difference region 2b. This corresponds to the area 12. The second retardation member 2 has the same retardation in both the first retardation region 11 and the second retardation region 12.

  The first retardation member has a front retardation of ½ wavelength (λ / 2), and the second retardation member has a front retardation of ¼ wavelength (λ / 4). The slow axis direction of the first phase difference member 1 and the slow axis direction of the second phase difference member 2 are orthogonal to each other. In the first retardation region 11 of the retardation plate 10, the half-wave plate and the quarter-wave plate are arranged so that their slow axes are orthogonal to each other. Have Further, in the second retardation region of the retardation plate 10, a region 1b that does not have a retardation of the first retardation member 1 and a second retardation member having a front retardation of λ / 4 are arranged. Therefore, it has a quarter-wave front retardation. The slow axis direction 111 of the first phase difference region 11 and the slow axis direction 121 of the second phase difference region are orthogonal to each other.

  Here, in the present specification, the term “orthogonal” is not limited to the angle between the two being strictly 90 °, and may be within a range that can achieve the object of the present invention, for example, 90 ± 5 °. , Preferably 90 ± 3 °. Similarly, the term “parallel” is not limited to the angle between the two being strictly 0 °, and may be within a range that can achieve the object of the present invention, for example, 0 ± 5 °, preferably 0 ±. 3 °. Further, “45 °” is not limited to exactly 45 °, and may be a range in which linearly polarized light can be converted into substantially circularly polarized light, for example, 45 ± 5 °, preferably 45 ± 3 °. is there. Unless otherwise specified, the sign of the angle is not limited, and may be counterclockwise (+) or clockwise (−).

  In addition, the description that the retardation is “¼ wavelength” or “λ / 4” does not require the retardation to be exactly ¼ times the wavelength λ, and converts linearly polarized light into substantially circularly polarized light. Any range is acceptable. The “substantially circularly polarized light” may include not only perfect circularly polarized light but also elliptically polarized light that is close to perfect circularly polarized light, that is, whose ellipticity is close to 1. For example, a range where the retardation at the wavelength λ = 550 nm is 137.5 ± 30 nm is included in the “¼ wavelength”. The retardation at the wavelength λ = 550 nm is preferably 137.5 ± 20 nm, and more preferably 137.5 ± 10 nm. Similarly, the description of “1/2 wavelength” or “λ / 2” does not have to be exactly ½ times the wavelength λ. For example, the retardation at the wavelength λ = 550 nm is in the range of 275 ± 60 nm. Are included in “½ wavelength”. The retardation at the wavelength λ = 550 nm is preferably 275 ± 40 nm, and more preferably 275 ± 20 nm.

  2A and 2B are cross-sectional views schematically showing a polarizing element 50 in which the retardation plate 10 and the polarizing plate 20 are laminated. The polarizing plate 20 may be laminated on the first retardation member 1 side of the retardation plate 10 as shown in FIG. 2A, or laminated on the second retardation member 2 side as shown in FIG. 2B. May be. FIG. 3 is a perspective view conceptually showing the polarizing element 50. The angle formed by the transmission axis direction 201 of the polarizing plate 20 and the slow axis directions 111 and 121 of the retardation plate 10 is ± 45 °.

  FIG. 4 is a perspective view conceptually showing the stereoscopic image display apparatus of the present invention. In FIG. 4, for the sake of brevity, one each of the first phase difference region 11 and the second phase difference region are illustrated, but in the actual configuration, the first phase difference region 11 and There are a plurality of second retardation regions 12.

  In the stereoscopic video display device 80, the polarizing plate 20 is disposed on the viewing side of the video display cell 30, and the retardation plate 10 is disposed on the viewing side of the polarizing plate 20. The video display cell 30 has a plurality of first video display areas 31 and second video display areas 32 in a plane. As shown in FIG. 4, the first phase difference region 11 and the second phase difference region 12 of the phase difference plate 10 are respectively a first video display region 31 and a second video display region 32 of the video display cell 30. It arrange | positions corresponding to.

  The principle of displaying a stereoscopic image with the above configuration will be described with reference to FIG. From the first video display area 31 of the video display cell, light r31 having natural polarization or a predetermined polarization state is emitted. When the light r31 passes through the polarizing plate 20, only the polarization component r21 having vibration in the transmission axis direction 201 of the polarizing plate 20 is transmitted to the phase difference plate 10 side, and the polarization component having vibration in the direction orthogonal to the transmission axis direction 201. Is shielded.

  The light r21 that has passed through the polarizing plate 20 reaches the first retardation region 11 of the retardation plate 10. Here, the angle formed by the vibration direction of the light r21 and the slow axis direction 111 of the retardation plate is + 45 °, and the front retardation is ¼ of the wavelength λ. Therefore, the light r11 transmitted through the first retardation region 11 of the retardation plate 10 becomes circularly polarized light.

  On the other hand, light r32 having natural polarization or a predetermined polarization state is emitted from the second video display area 32 of the video display cell. When the light r32 passes through the polarizing plate 20, only the polarization component r22 having vibration in the transmission axis direction 201 of the polarizing plate 20 is transmitted to the phase difference plate 10 side, and the polarization component having vibration in the direction orthogonal to the transmission axis direction 201. Is shielded.

  The light r <b> 22 that has passed through the polarizing plate 20 reaches the second retardation region 12 of the retardation plate 10. Here, the angle formed by the vibration surface of the light r22 and the slow axis direction 111 of the retardation plate is −45 °, and the front retardation is ¼ of the wavelength λ. Therefore, the light r12 that has passed through the second retardation region 12 of the retardation plate 10 is also circularly polarized.

  Here, since the slow axis direction 111 of the first retardation region 11 of the retardation plate 10 and the slow axis direction 121 of the second retardation region 12 are orthogonal, the first retardation region is The phases of the circularly polarized light r11 that has passed through and the circularly polarized light r12 that has passed through the second retardation region are shifted by π. Therefore, r11 and r12 appear as circularly polarized light having different polarities.

  For example, when a right-eye image is emitted from the first image display area 31 of the image display cell and a left-eye image is emitted from the second image display area 32, the action of the polarizing plate 20 and the retardation plate 10 is used. The right-eye image in the first image display area appears as right circularly polarized light r11, and the left-eye image in the second image display area appears as left circularly polarized light r12. The viewer visually recognizes the image by wearing stereoscopic glasses for stereoscopic viewing. The polarized glasses include, for example, a right-eye lens that includes a first circularly polarizing plate that transmits right circularly polarized light and shields left circularly polarized light, and a second circularly polarizing plate that transmits left circularly polarized light and blocks right circularly polarized light. A right-eye lens.

  According to such a configuration, only the right-eye video is visually recognized by the viewer's right eye, and only the left-eye video is visually recognized by the left eye. For this reason, the viewer recognizes the stereoscopic image by recalling the sense of depth by the difference between the right-eye video and the left-eye video, that is, binocular parallax.

  Note that the above is a description when the video display device is viewed from the front. On the other hand, when the video display device is viewed from an oblique direction, the apparent slow axis direction and the apparent retardation value are different from those in the front view. Therefore, the polarization state of the light r11 that has passed through the first retardation region and the light r12 that has passed through the second retardation region has some deviation from the circularly polarized light. Due to such a deviation from circularly polarized light at the time of strabismus, crosstalk of the image and a color difference between the right-eye video and the left-eye video may occur. In particular, when the deviation from the circularly polarized light in the first phase difference region and the deviation from the circularly polarized light in the second phase difference region are significantly different, the color difference between the right-eye image and the left-eye image tends to increase.

  In the second phase difference region 12, the first phase difference member 1 has no phase difference. Therefore, when viewed from the oblique direction, the phase difference characteristic from the front view in the second retardation region 12 is shifted in the oblique direction by the second retardation member 2 having a front retardation of λ / 4. It is equal to the deviation of the phase difference characteristic from the front view when viewed from above. On the other hand, when the first phase difference region 11 is viewed from an oblique direction, the phase difference characteristic deviation from the front view is different from the deviation of the first phase difference member 1 having the front retardation of λ / 2. The deviation of the second retardation member 2 having a front retardation of / 4 is combined.

  Here, a case where two A plates having the same reference numerals are stacked so that the slow axis directions are orthogonal to each other will be described. A laminated phase difference plate in which a first positive A plate having a slow axis in the azimuth angle + 45 ° direction and a second positive A plate having a slow axis in the azimuth angle −45 ° direction is laminated. When viewed from an oblique direction of 0 °, the apparent slow axis direction of the first positive A plate is on the + side of + 45 °, and the apparent slow axis direction of the second positive A plate is −45. It changes on the minus side from °. On the other hand, a laminated phase difference plate in which a first negative A plate having a slow axis in the azimuth angle + 45 ° direction and a second negative A plate having a slow axis in the azimuth angle −45 ° direction are laminated, When viewed from an oblique direction with an azimuth angle of 0 °, the apparent slow axis direction of the first negative A plate is more negative than + 45 °, and the apparent slow axis direction of the second negative A plate is It changes to + side from -45 ° respectively.

  Thus, when two A plates having the same code are used, the apparent slow axis directions of the two A plates appear to change in different directions when viewed from an oblique direction. Therefore, when both the first phase difference member and the second phase difference member are positive A plates, or when both are negative A plates, the phase difference members have the same three-dimensional refractive index characteristics. Is used, the apparent slow axis direction of the first retardation member and the apparent slow axis direction of the second retardation member deviate from the orthogonal state. In such a configuration, when the video display device is viewed from an oblique direction, the first retardation region 11 in which two retardation layers are stacked and the second retardation having only one retardation layer. Since the difference in polarization state from the region tends to increase, a color difference tends to occur between the right-eye image and the left-eye image.

  On the other hand, in this invention, A plate from which a code | symbol differs is used for the 1st phase difference member and the 2nd phase difference member. That is, in the first embodiment of the present invention, the first retardation member 1 is a positive A plate, and the second retardation member 2 is a negative A plate. In the second embodiment of the present invention, the first retardation member 1 is a negative A plate, and the second retardation member 2 is a positive A plate.

  More specifically, in the first embodiment of the present invention, the first retardation member 1 has a positive A plate having a half-wave front retardation in the region 1a corresponding to the first retardation region. The region 1b corresponding to the second phase difference region has no phase difference. In the first embodiment, the second retardation member 2 is a negative A plate having a quarter-wave front retardation. On the other hand, in the second embodiment of the present invention, the first retardation member 1 is formed with a negative A plate having a half-wave front retardation in the region 1a corresponding to the first retardation region. The region 1b corresponding to the second phase difference region has no phase difference. In the second embodiment, the second retardation member 2 is a positive A plate having a quarter-wave front retardation.

  That is, in the first retardation region 11 of the retardation film 10 of the present invention, the positive A plate and the negative A plate are laminated so that the slow axis directions thereof are orthogonal to each other. . In such a configuration in which two A plates having different signs are laminated so that their slow axis directions are orthogonal to each other, even when viewed from an oblique direction, the apparent slow phase of the positive A plate The change in the axial direction and the change in the apparent slow axis direction of the negative A plate are the same direction, and the orthogonality of the apparent slow axis direction of both is maintained. That is, when the positive A plate is viewed from an oblique direction, the slow axis direction of the positive A plate changes in a direction away from the viewer, whereas the slow axis direction of the negative A plate approaches the viewer. Since the direction changes, the orthogonal relationship between the two is maintained.

  Here, when the refractive indexes in the slow axis direction and the fast axis direction in the film plane are nx and ny, respectively, and the refractive index in the thickness direction is nz, in general, a three-dimensional refractive index characteristic of nx> ny = nz is obtained. Those having “positive A plate” are referred to as “positive A plate”, but in the present invention, those having nx> ny≈nz are also included in “positive A plate”. Similarly, a material having a three-dimensional refractive index characteristic of nx = nz> ny is generally referred to as a “negative A plate”. In the present invention, a material having nx≈nz> ny is also referred to as a “positive A plate”. Is included. Specifically, those having an Nz coefficient defined by Nz = (nx−nz) / (nx−ny) in the range of 0.9 to 3 are included in the positive A plate, and the Nz coefficient is −2 to 0. Those in the range of 1 are also included in the “negative A plate”.

  Hereinafter, the manufacturing method of the phase difference plate of this invention is demonstrated.

[Positive A plate]
The positive A plate can be produced, for example, by stretching and orienting a polymer film having positive birefringence. “Having positive birefringence” means that when the polymer is oriented by stretching or the like, the refractive index in the orientation direction becomes relatively large, and many polymers fall under this category. Examples of the polymer having positive birefringence include polycarbonate resins, polyvinyl alcohol resins, cellulose fatty acid esters such as triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, and dipropionyl cellulose, and cellulose resins such as cellulose ether. Polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyarylate resins, polyimide resins, cyclic polyolefin (polynorbornene) resins, polysulfone resins, polyethersulfone resins, polyamide resins, polyethylene and polypropylene Examples include polyolefin resins. These polymers can be used alone or in a combination of two or more. These can also be used after being modified by copolymerization, branching, crosslinking, molecular end modification (or sealing), stereoregular modification, or the like.

  In general, a positive A plate can be obtained by longitudinally uniaxially stretching a polymer film having positive birefringence (free end uniaxial stretching), but the stretching method, stretching conditions (for example, stretching temperature, stretching ratio, stretching direction), etc. Depending on the type of resin forming the polymer film, the desired retardation, and the value of the Nz coefficient, the polymer film can be appropriately selected.

  Further, as the positive A plate, an alignment layer of liquid crystal molecules having positive birefringence can be used. As the liquid crystal molecule, a rod-like liquid crystal material whose liquid crystal phase is a nematic phase is preferably used. As such a liquid crystal material, for example, a liquid crystal polymer or a liquid crystal monomer can be used. From the viewpoint of obtaining a positive A plate, the alignment state of the liquid crystal is preferably homogeneous alignment. In the present specification, “homogeneous alignment” refers to a state in which liquid crystal compounds are arranged in parallel and in the same direction with respect to the film surface. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

  When the liquid crystal material is a liquid crystal monomer, for example, a polymerizable monomer and / or a crosslinkable monomer is preferable. After aligning the liquid crystalline monomers, for example, if the liquid crystalline monomers are polymerized or crosslinked, the alignment state can be fixed thereby. A polymer is formed by polymerizing liquid crystal monomers, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the formed positive A plate, for example, transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change unique to the liquid crystal compound does not occur. As a result, the alignment layer of liquid crystalline molecules is hardly affected by temperature change and can be a retardation member having excellent stability.

  Any appropriate liquid crystal monomer can be adopted as the liquid crystal monomer. For example, Japanese translations of PCT publication No. 2002-533742 (WO00 / 37585 international publication pamphlet), European patent 358208 (US Pat. No. 5,211,877), European patent 66137 (US Pat. No. 4,388,453), WO93 / 22397 international publication. Polymerizable mesogenic compounds described in pamphlets, European Patent No. 0261712, German Patent No. 19504224, German Patent No. 4408171 and British Patent No. 2280445 can be used. Specific examples of such a polymerizable mesogenic compound include, for example, the trade name LC242 from BASF, the trade name E7 from Merck, and the trade name LC-Silicon-CC3767 from Wacker-Chem.

[Negative A plate]
The negative A plate can be produced, for example, by stretching and aligning a polymer film having negative birefringence. “Having negative birefringence” means that when a polymer is oriented by stretching or the like, the refractive index in the orientation direction becomes relatively small, in other words, the refractive index in the direction orthogonal to the orientation direction becomes large. Say things. Examples of such a polymer include those in which a chemical bond or a functional group having a large polarization anisotropy such as an aromatic group or a carbonyl group is introduced into the side chain of the polymer. Specific examples include acrylic resins, styrene resins, maleimide resins, and the like.

  The acrylic resin, styrene resin, and maleimide resin can be obtained by, for example, addition polymerization of an acrylic monomer, a styrene monomer, a maleimide monomer, or the like. Further, after polymerization, the birefringence characteristics can be controlled by substituting side chains, performing maleimidation or grafting reaction, and the like. Moreover, as a polymer which shows a negative birefringence, the cyclic olefin type copolymer etc. which are disclosed by Unexamined-Japanese-Patent No. 2005-350544 etc. can also be used, for example. Furthermore, a composition of a polymer and inorganic fine particles as disclosed in Japanese Patent Application Laid-Open No. 2005-156862, Japanese Patent Application Laid-Open No. 2005-227427, and the like can be suitably used. Moreover, the polymer which shows negative birefringence can also be used individually by 1 type, and may mix and use 2 or more types. Further, they can be used after being modified by copolymerization, branching, crosslinking, molecular end modification (or sealing), stereoregular modification, or the like.

  In general, a negative A plate can be obtained by longitudinally uniaxially stretching (free end uniaxial stretching) a polymer film having negative birefringence, but the stretching method, stretching conditions (for example, stretching temperature, stretching ratio, stretching direction), etc. Depending on the type of resin forming the polymer film, the desired retardation, and the value of the Nz coefficient, the polymer film can be appropriately selected.

  The negative A plate can also be produced using a polymer having positive birefringence. Examples of a method for obtaining a negative A plate using a polymer having positive birefringence are disclosed in Japanese Patent Application Laid-Open Nos. 2000-2331016, 2000-206328, and 2002-207123. Such a stretching method that increases the refractive index in the thickness direction can be used. That is, a film having a polymer having a positive birefringence under the action of the shrinkage force of the heat-shrinkable film by heat treatment by adhering a heat-shrinkable film to one or both sides of a film having a polymer having a positive birefringence Is also contracted in the width direction and, if necessary, in the longitudinal direction, the refractive index in the thickness direction is increased, and a negative A plate having the characteristics of nx≈nz> ny is obtained.

  Since a polymer having negative birefringence has fewer types of polymers that can be used than a polymer having positive birefringence, the positive birefringence as described above is satisfied from the viewpoint of satisfying desired optical properties, heat resistance, and the like. A method of obtaining a negative A plate with a polymer having refraction can be useful.

  Further, as the negative A plate, an alignment layer of liquid crystalline molecules having negative birefringence can be used. As the liquid crystalline molecule, a discotic liquid crystal material whose liquid crystal phase is a nematic phase is preferably used. From the viewpoint of obtaining a negative A plate, the alignment state of the liquid crystal is preferably such that the disc surface of the discotic liquid crystal compound molecules is perpendicular to the film surface and the optical axis is parallel to the film surface.

  Preferably, the discotic liquid crystal compound has at least one polymerizable functional group and / or crosslinkable functional group in a part of the molecular structure. If such a liquid crystal compound is used, the mechanical strength of the retardation member is increased by polymerizing or crosslinking these functional groups by polymerization reaction or crosslinking reaction, and the retardation member is excellent in durability and dimensional stability. Can be obtained. Any appropriate functional group may be selected as the polymerizable functional group or the crosslinkable functional group, but an acryloyl group, a methacryloyl group, an epoxy group, a vinyl ether group, or the like is preferably used.

  Such a negative A plate comprising a solidified layer or a hardened layer of a discotic liquid crystal compound can be obtained, for example, by the method described in JP-A No. 2001-56411.

  A negative A plate is also obtained by aligning a discotic liquid crystal compound exhibiting a lyotropic liquid crystal phase so that the disk surface of the molecule is perpendicular to the film surface and the optical axis is parallel to the film surface. Can be used as The “lyotropic liquid crystal compound” refers to a liquid crystal compound that exhibits a liquid crystal phase depending on the concentration of a solute in a solution state.

  Any appropriate lyotropic liquid crystal compound may be used. Specific examples of the lyotropic liquid crystal compound include an amphiphilic compound having a hydrophilic group and a hydrophobic group at both ends of the molecule, and a chromonic compound having an aromatic ring imparted with water solubility.

  The negative A plate comprising a solidified layer or a cured layer of a liquid crystalline composition containing the substantially vertically aligned lyotropic liquid crystal compound is described in, for example, JP-A-10-333154 and JP-T-2004-519014. It can be obtained by the method.

[Patterning of first retardation member]
Next, a patterning method for the first retardation member will be described. In the first embodiment of the present invention, the region 1a having the phase difference of the first phase difference member 1 is a positive A plate, and the second phase difference member 2 is a negative A plate. In this case, a positive A plate having a front retardation of λ / 2 is patterned into a region 1a having a phase difference and a region 1b having no phase difference. In the second embodiment of the present invention, the region 1a having the phase difference of the first phase difference member 1 is a negative A plate, and the second phase difference member 2 is a positive A plate. In this case, the negative A plate having a front retardation of λ / 2 is patterned into a region 1a having a phase difference and a region 1b having no phase difference.

  The method of patterning the first retardation member 1 is not particularly limited, and a method of patterning after forming a polymer film having a front retardation of λ / 2 or a liquid crystal alignment layer, and formation of a λ / 2 plate Any of the methods of patterning can be employed at times.

  As a method of patterning after forming a polymer film having a front retardation of λ / 2 or a liquid crystal alignment layer, a portion corresponding to the region 1a having a phase difference is covered with a resist material, and a wet etching method or a dry etching method is used. The method of patterning is mentioned. Moreover, you may use the photosensitive film which has birefringence described in Unexamined-Japanese-Patent No. 9-68699. In this case, since the polymer film itself has photosensitivity, only light corresponding to the region 1a may be irradiated through the photomask. In addition, a method of removing a portion corresponding to the region 1b having no phase difference from the λ / 2 plate by laser irradiation or sandblasting may be employed.

  As a method of patterning at the time of forming the λ / 2 plate, for example, a method of patterning an alignment layer for aligning a liquid crystal layer, or irradiation with ultraviolet rays for polymerizing or crosslinking a liquid crystalline monomer, etc. A method of irradiating only the region 1a using a mask or the like can be used.

  The region 1b having no phase difference after patterning may be a cavity or may be filled with an appropriate material. In addition, a planarization layer (not shown) may be formed on the surface of the first retardation member in order to stack with other members.

  In FIG. 1, regions 1 a (regions having a phase difference) corresponding to the first phase difference region 11 and regions 1 b (regions having no phase difference) corresponding to the second phase difference region 12 are alternately arranged. Although an embodiment in which stripes are arranged is shown, the present invention is not limited to such an embodiment. For example, even if the first retardation region 11 and the second retardation region 12 are arranged in a lattice pattern. Good.

  When the first phase difference region and the second phase difference region are arranged in a stripe shape, the width of each stripe column is equal to the width of the right-eye video display column and the left-eye video display column of the video display cell. It is preferable to correspond. In such a case, the width of each phase difference region is preferably small, and specifically, it is preferable to correspond to the length of one side (pixel width) of the pixel of the video display device. In addition, when the first phase difference region 11 and the second phase difference region 12 are arranged in a lattice shape, it is preferable that each phase difference region corresponds to a pixel of the video display device.

  Note that the boundary portion between the first phase difference region and the second phase difference region may not be used for video display. From this point of view, it is preferable that the first phase difference regions and the second phase difference regions are alternately arranged in a stripe shape to reduce the area of the boundary portion of the phase difference regions.

[Polarizing element]
The polarizing element 50 of the present invention has a configuration in which the retardation plate 10 and the polarizing plate 20 are laminated. The polarizing element 50 has a configuration in which the first retardation member 1 side of the retardation plate 10 is laminated on the polarizing plate 20 side, and the second retardation member 2 side of the retardation plate 10 is laminated on the polarizing plate 20 side. Any of the configurations may be used.

  As shown in FIG. 3, the transmission axis direction 201 of the polarizing plate 20 forms an angle of 45 ° with the slow axis direction 121 of the second retardation region 12 of the retardation film 10. The angle formed between the transmission axis direction 201 of the polarizing plate 20 and the slow axis direction 111 of the first retardation region 11 of the retardation plate 10 is also 45 °, but the sign (±) of the angle is the second. This is opposite to the case of the slow axis direction of the phase difference region. With this configuration, the linearly polarized light transmitted through the polarizing plate 20 is converted by the retardation plate 10 into circularly polarized light (right circularly polarized light and left circularly polarized light) having different polarities in the first region and the second region.

  The polarizing plate 20 is not particularly limited as long as it converts light having an arbitrary polarization state into linearly polarized light, and various types can be used. As such a polarizing plate, what laminated | stacked the transparent protective film as needed on one or both main surfaces of a polarizer is used, for example. Polarizers include hydrophilic polymers such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, ethylene / vinyl acetate copolymer partially saponified films, and dichroic substances such as iodine and dichroic dyes. And polyene-based oriented films such as a uniaxially stretched product and a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. Further, a guest / host type O-type polarizing plate in which a liquid crystalline composition containing a dichroic substance and a liquid crystalline compound disclosed in US Pat. No. 5,523,863 is aligned in a certain direction, US Pat. An E-type polarizing plate or the like in which lyotropic liquid crystals disclosed in US Pat. No. 6,049,428 are aligned in a certain direction can also be used.

  As a transparent protective film laminated | stacked on the one or both main surfaces of a polarizer, what is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property etc. is used suitably, for example. In addition, the retardation plate of the present invention may be laminated on a polarizer so that the function as a polarizing plate protective film and the function as a stereoscopic image display retardation plate are combined.

  The polarizing plate 20 and the retardation plate 10 may be simply overlapped, or may be bonded via an adhesive or the like. Further, between the polarizing plate 20 and the retardation plate 10, a polarizing plate protective film or other film, or a glass substrate for forming a video display cell may be interposed.

[3D image display device]
A stereoscopic image display device is formed by arranging the phase difference plate 10 or the polarizing element 50 on the viewing side of the image display cell 30. In addition, the expression “viewing side of the video display cell” is not limited to the form of being arranged on the viewing side with respect to all the members that form the video display cell. It is not always necessary to arrange the liquid crystal cell closer to the viewing side than the glass substrate on the viewing side.

  As shown in FIG. 4, the retardation plate 10 of the present invention is disposed on the viewing side with respect to the polarizing plate 20. Further, the first phase difference region 11 and the second phase difference region 12 of the phase difference plate correspond to the first video display region 31 and the second video display region 32 of the video display cell 30, respectively. It is arranged on the normal direction viewing side of the screen. One of the first video display area 31 and the second video display area 32 corresponds to a right-eye video display area and the other corresponds to a left-eye video image display area. With this configuration, since the light emitted from the first video display area and the second video display area of the video display cell is emitted as circularly polarized light having different polarities by the polarizing plate 20 and the phase difference plate 10, three-dimensional display Is realized.

  The video display cell 30 is not particularly limited. For example, a display cell that adjusts the amount of light transmitted from a light source, such as an organic EL cell, a plasma display cell, a self-luminous display cell such as a cathode ray tube, or a liquid crystal cell. Can be used. A screen of a projection display device such as a rear projection system can also be applied.

  Among them, the liquid crystal display device has a polarizing plate disposed on the viewing side of the liquid crystal cell for video display. Therefore, the stereoscopic image display device can be obtained by adding the retardation plate of the present invention without providing a separate polarizing plate. It can be formed. Another polarizing plate may be provided separately from the viewing side polarizing plate. In the case of an organic EL display device, a circularly polarizing plate in which a quarter wave plate and a polarizing plate are laminated is arranged on the viewing side of the organic light emitting layer in order to shield the specular reflection of external light by the metal electrode. However, a stereoscopic image display device may be provided by disposing the retardation plate of the present invention on the viewing side of the circularly polarizing plate.

  A liquid crystal display device employing a liquid crystal cell as the video display cell 30 of the stereoscopic video display device will be described. Liquid crystal cells include reflective liquid crystal cells that use external light, transmissive liquid crystal cells that use light from a light source such as a backlight, and semi-transmissive and semi-reflective types that use both external light and light from the light source. Any liquid crystal cell may be used. As a driving method of the liquid crystal cell, any type such as VA mode, IPS mode, TN mode, STN mode, bend alignment (π type), etc. can be used.

  Referring to FIG. 5, the liquid crystal cell 30 includes a pair of substrates 301 and 302 and a liquid crystal layer 303 as a display medium sandwiched between the substrates. In a general configuration, a color filter layer 306 is provided on one substrate 301 side, a switching element 307 for controlling the electro-optical characteristics of liquid crystal is provided on the other substrate 302, and a gate signal is supplied to this switching element. A scanning line for supplying a signal line, a signal line for supplying a source signal, a pixel electrode, and a counter electrode are provided. The distance (cell gap) between the substrates 301 and 302 can be controlled by a spacer or the like. On the side of the substrate in contact with the liquid crystal layer 303, for example, an alignment film made of polyimide or the like can be provided. The color filter layer 306 includes, for example, a color filter and a black matrix corresponding to each color of red (R), green (G), and blue (B).

  The polarizing plate 20 and the retardation plate 10 are disposed on the substrate 301 side on the viewing side. The phase difference plate 10 is arranged so that the first phase difference region 11 and the second phase difference region 12 correspond to the first video display region 31 and the second video display region 32 of the video display cell 30, respectively. Is done.

  It is preferable that the phase difference plate 10 and the polarizing plate 20 are bonded to the substrate 301 of the liquid crystal cell via an adhesive or an adhesive. When a transmissive liquid crystal cell or a transflective liquid crystal cell is adopted as the liquid crystal cell 30, it is preferable that the polarizing plate 40 and the light source 60 are disposed on the substrate 302 side of the liquid crystal cell.

  In addition, as shown in FIG. 6, the polarizing plate 20 and the retardation plate 10 can be disposed on the inner side (the liquid crystal layer 303 side) of the glass substrate 301 constituting the liquid crystal cell 30. According to this embodiment, since the phase difference plate 10 is disposed at the time of forming the liquid crystal cell, it is easy to align the image display areas 31 and 32 of the liquid crystal cell 30 and the phase difference areas 11 and 12 of the phase difference plate 10. You can get none. In addition, since the distance between the liquid crystal layer 303, which is a pixel formation region of the liquid crystal cell, and the retardation plate 10 is small, even when the image display device is viewed from an oblique direction, the phase difference between the image display region of the liquid crystal cell and the retardation plate. The correspondence relationship with the area can be maintained, and mixing of the right-eye video and the left-eye video (crosstalk) can be suppressed.

  In FIG. 6, the polarizing plate 20 and the retardation plate 10 are provided on the viewing side (substrate 301 side) of the color filter layer 306, but the color filter layer 306 is disposed between the polarizing plate 20 and the retardation plate 10. Also, it can be disposed between the phase difference plate 10 and the substrate 301.

  Even when a cell other than a liquid crystal cell, such as an organic EL cell, a plasma display cell, or a cathode ray tube, is used as the video display cell, the first retardation region 11 and the second retardation region 10 of the retardation plate 10 are used. By arranging the phase difference region 12 so as to correspond to the first video display region 31 and the second video display region 32 of the video display cell 30, respectively, a stereoscopic video display device is formed.

  A stereoscopic image appearing from the stereoscopic image display device of the present invention is visually recognized by wearing stereoscopic polarizing glasses including two circularly polarizing plates having different polarities as a right-eye lens and a left-eye lens. The person recalls the stereoscopic display.

  The stereoscopic polarizing glasses 70 include a first circularly polarizing plate 71 on one of the right-eye lens and the left-eye lens, and a second circularly polarizing plate 72 on the other side. As schematically shown in FIG. 7, the first circularly polarizing plate 71 transmits the first circularly polarized light r11 that is transmitted from the first video display region 31 through the first retardation region 11 and appears. Then, the second circularly polarized light r121 that is transmitted from the second video display region 32 through the second phase difference region 12 and appears is blocked. On the other hand, the second circularly polarizing plate 72 shields the first circularly polarized light r112 that is transmitted from the first video display region 31 through the first phase difference region 11 and appears, and thereby the second video display region. 32 transmits the second circularly polarized light r122 which is transmitted through the second retardation region 12 and appears. The first circularly polarized light and the second circularly polarized light have opposite polarities. That is, one of the first circularly polarized light and the second circularly polarized light is right circularly polarized light, and the other is left circularly polarized light.

  As such a first circularly polarizing plate 71 and a second circularly polarizing plate 72, a combination of two circularly polarizing plates that transmit circularly polarized light having different polarities is used. As such two circularly polarizing plates, a combination of a first reflective circularly polarizing plate and a second reflective circularly polarizing plate using cholesteric liquid crystals having different twist directions, or a polarizing plate and a quarter-wave plate are laminated. First circularly polarizing plate, a combination of a second circularly polarizing plate in which a polarizing plate and a quarter-wave plate are laminated, a first circularly polarizing plate in which a polarizing plate and a quarter-wave plate are laminated, and a polarizing plate A combination of a second circularly polarizing plate in which the axial arrangement of the quarter-wave plate and the first circularly polarizing plate are mirror images can be employed.

  According to the present invention, since two A plates having different signs are arranged in the first region of the phase difference plate 10, the viewer can be viewed even when the stereoscopic image display device is viewed from an oblique direction. In both the right-eye video and the left-eye video that arrive at γ, the polarization state is suppressed from greatly deviating from the circularly polarized light. Therefore, the difference in color between the right-eye video and the left-eye video viewed through the stereoscopic polarizing glasses is small, and the viewer's feeling of fatigue and screen sickness are suppressed.

  In the following examples, the effect of the present invention was confirmed by evaluating the polarization state of the light transmitted through the first region and the second region of the retardation plate.

(Polarizer)
A commercially available iodine polarizing plate in which a polarizer protective film was laminated on both surfaces of a polarizer made of a polyvinyl alcohol film uniaxially stretched by adsorbing iodine was used.

(Positive A plate)
Using a commercially available polymer film (trade name “ZEONOR FILM ZF14-100” manufactured by Optes, Inc.) mainly composed of a cyclic polyolefin polymer, the film is uniaxially stretched by a roll stretching machine, and λ / 4 plate and λ / Two plates were obtained. Both the λ / 4 plate and the λ / 2 plate were positive A plates with NZ = 1.0, and the front retardation at a wavelength of 550 nm was 137.5 nm and 275 nm, respectively.

(Negative A plate)
Styrene-maleic anhydride copolymer (manufactured by Nova Chemical Japan Co., Ltd., product name “Dylark D232”) is extruded at 270 ° C. using a single screw extruder and a T die, and melted in a sheet form. The resin was cooled with a cooling drum to obtain a film. This film was uniaxially stretched by a roll stretching machine to obtain a λ / 4 plate and a λ / 2 plate. Both the λ / 4 plate and the λ / 2 plate were negative A plates with NZ = 0.0, and the front retardation at a wavelength of 550 nm was 137.5 nm and 275 nm, respectively.

[Example 1]
When the first retardation member whose phase difference region 1a is a positive A plate having a front retardation λ / 2 and the second retardation member being a negative A plate having a front retardation λ / 4 is used The polarization states in the first retardation region and the second retardation region were confirmed.

(Example 1-1)
A positive A plate having a front retardation of λ / 2 in a half region of one main surface of the polarizing plate, the slow axis direction of the positive A plate is + 45 ° with respect to the transmission axis direction of the polarizing plate (polarizing plate (When viewed from the side). A negative A plate having a front retardation of λ / 4 was laminated on the entire surface of the polarizing plate so that the slow axis direction of the positive A plate and the slow axis direction of the negative A plate were orthogonal to each other. That is, Example 1-1 corresponds to the stacked form of FIG. 2A.

(Example 1-2)
A negative A plate having a front retardation of λ / 4 is formed on the entire surface of one main surface of the polarizing plate, and the slow axis direction of the negative A plate is + 45 ° (from the polarizing plate side) with respect to the transmission axis direction of the polarizing plate. (When viewed). A positive A plate having a front retardation of λ / 2 in the upper half region was laminated so that the slow axis direction of the negative A plate and the slow axis direction of the positive A plate were orthogonal to each other. That is, Example 1-2 is corresponded to the lamination | stacking form of FIG. 2B.

(Evaluation of coloring of white image)
On the light source (luminance of about 10000 cd / m ² ), the first retardation region (region where the positive A plate and the negative A plate are arranged) and the second retardation region (only the negative A plate are on the polarizing plate) The polarizing element on which the retardation plate having the disposed region) is formed is disposed so that the polarizing plate is on the light source side.

Luminance meter (Topcon product name “BM-5” lens with a circularly polarizing plate (Nitto Denko product name “NZD-VEGQ”), light source turned on in a dark room at 23 ° C., 60 minutes later, A luminance meter was placed at a position 50 cm from the panel, and X, Y, and Z of the XYZ color system in the front direction (normal direction of the phase difference plate), azimuth angle 40 °, and polar angle 60 ° direction were measured. From the obtained X, Y, and Z values, an x value (X / (X + Y + Z)) and a y value (Y / (X + Y + Z)) were calculated.
The reference for the azimuth angle was 0 ° for the absorption axis direction of the polarizing plate, and + for counterclockwise when viewed from the viewing side (luminance meter side). In addition, the circularly polarizing plate attached to the lens has a polarity that allows circularly polarized light appearing from the phase difference region to be measured to pass therethrough.

(Evaluation of polarization characteristics)
Sample pieces are cut out from each of the first region and the second region of the polarizing element, and are elliptically polarized in the front direction, the azimuth angle 40 °, and the polar angle 60 ° direction at a wavelength of 550 nm by KOBRA-WPR manufactured by Oji Scientific Instruments. The characteristics were measured and the respective Stokes parameters were calculated. As a reference for calculating the Stokes parameter, the Stokes parameter of linearly polarized light in the transmission axis direction of the polarizing plate is (S1, S2, S3) = (0, 1, 0), and the northern hemisphere of S3> 0 is right elliptically polarized light. The southern hemisphere with S3 <0 was defined as left circularly polarized light.

[Example 2]
When the first retardation member in which the phase difference region 1a is a negative A plate having a front retardation λ / 2 and the second retardation member being a positive A plate having a front retardation λ / 4 are used. The polarization states in the first retardation region and the second retardation region were confirmed.

(Example 2-1)
A negative A plate having a front retardation of λ / 2 in a half region of one main surface of the polarizing plate, the slow axis direction of the negative A plate is + 45 ° with respect to the transmission axis direction of the polarizing plate (polarizing plate (When viewed from the side). A negative A plate having a front retardation of λ / 4 was laminated on the entire surface of the polarizing plate so that the slow axis direction of the positive A plate and the slow axis direction of the negative A plate were orthogonal to each other. That is, Example 2-1 corresponds to the stacked form of FIG. 2A.

(Example 2-2)
A negative A plate having a front retardation of λ / 4 is formed on the entire surface of one main surface of the polarizing plate, and the slow axis direction of the negative A plate is + 45 ° (from the polarizing plate side) with respect to the transmission axis direction of the polarizing plate. (If you see it). A positive A plate having a front retardation of λ / 2 in the upper half region was laminated so that the slow axis direction of the negative A plate and the slow axis direction of the positive A plate were orthogonal to each other. That is, Example 2-2 corresponds to the stacked form of FIG. 2B.

  The polarizing element thus obtained was evaluated for optical characteristics in the same manner as in Example 1.

[Comparative Example 1]
In Comparative Example 1, instead of using the positive A plate as the first retardation member in Example 1, a negative A plate was used. That is, in the retardation plate of Comparative Example 1, negative A plates were used for both the first retardation member and the second retardation member. Otherwise, a polarizing element was produced in the same manner as in Example 1, and the optical characteristics were evaluated.

[Comparative Example 2]
In Comparative Example 2, instead of using the negative A plate as the first retardation member in Example 2, a positive A plate was used. That is, in the retardation plate of Comparative Example 2, positive A plates were used for both the first retardation member and the second retardation member. Otherwise, a polarizing element was prepared in the same manner as in Example 2, and the optical characteristics were evaluated.

  Table 1 shows the configuration of the retardation plate in each of the above Examples and Comparative Examples, and Table 2 shows the evaluation results (Stokes parameters) of the polarization characteristics. FIG. 8 shows the evaluation results of the hue of white display in each example, and FIG. 9 shows the evaluation results of the hue of white display in each comparative example.

  As shown in Table 1, in any of the examples and comparative examples, when viewed from the front direction (azimuth angle 0 °, polar angle 0 °), the Stokes parameter S3 of the regions 1 and 2 becomes ± 1. Thus, circularly polarized light with different polarities is obtained. When viewed from an oblique direction (azimuth angle 40 °, polar angle 60 °), the absolute value of the Stokes parameter S3 in any of the examples and comparative examples in the second phase difference region where only the λ / 4 plate is disposed. The value is 0.9 or more, and it can be said that the circularly polarized state is maintained. On the other hand, in the first phase difference region where the λ / 4 plate and the λ / 2 plate are arranged, a clear difference was observed between the example and the comparative example. That is, in each example in which two A plates having different signs are used, the absolute value of the Stokes parameter S3 is 0.9 or more and the circular polarization state is maintained even in the first phase difference region. On the other hand, in each comparative example in which two A plates having the same sign are used, the absolute value of S3 is significantly lower than in the example, and the deviation from circularly polarized light is large. I understand.

  FIG. 10 and FIG. 11 show, as the locus on the Poincare sphere (projection on the S1-S2 plane), the polarization state conversion by the phase difference plate when viewed from an oblique direction in each of the examples and the comparative examples, respectively. This is a schematic representation. According to FIG. 10, in any embodiment, the locus on the Poincare sphere in the first phase difference region and the second phase difference region exists on the same straight line. This is because the apparent slow axis direction orthogonal state between the first retardation plate and the second retardation plate is maintained. On the other hand, according to FIG. 11, in any of the comparative examples, the locus on the Poincare sphere in the first area where the two retardation plates are arranged does not exist within the same straight line. This is because the apparent slow axis directions of the first retardation plate and the second retardation plate are deviated from the orthogonal state.

  Thus, when two A plates having the same code are used, the amount of deviation from circularly polarized light differs greatly between the first region and the second region when viewed from an oblique direction. . Therefore, as shown in FIG. 9, in the first and second comparative examples, the difference in hue between the regions 1 and 2 when viewed from an oblique direction is larger than that in the front view. On the other hand, in each embodiment in which two A plates having different signs are used, as shown in FIG. 8, the difference in hue between the first area and the second area when viewed from an oblique direction. It can be seen that the color difference is suppressed.

  In addition, since said example was made in order to evaluate a polarization state, each phase difference area | region is not patterned finely. However, based on the disclosure of the present specification and the like, it is understood that the desired effect can be obtained by the configuration of the present invention if a finely patterned retardation plate is used.

1, 2 Retardation member 10 Retardation plate 20 Polarizing plate 30 Video display cell (liquid crystal cell)
DESCRIPTION OF SYMBOLS 40 Polarizing plate 50 Polarizing element 60 Light source 70 Polarized glasses 71, 72 Circular polarizing plate 80 Video display device 301, 302 Substrate 303 Liquid crystal layer 306 Color filter layer 307 Switching element
11,12 Phase difference area 31,32 Video display area 111,112 Slow axis direction 201 Transmission axis direction

Claims (6)

A plurality of first retardation regions and a plurality of second retardation regions, wherein both the first retardation region and the second retardation region have a quarter-wave front retardation; and A stereoscopic image forming phase difference plate in which a slow axis direction of a first retardation region and a slow axis direction of a second retardation region are orthogonal to each other,
A first retardation member having a retardation of ½ wavelength only in the first retardation region, and a second having a retardation of ¼ wavelength in the first retardation region and the second retardation region. Of the phase difference member,
In the first retardation region, the slow axis direction of the first retardation member and the slow axis direction of the second retardation member are orthogonal to each other,
The first phase difference region of the first phase difference member and the second phase difference member are three-dimensional image forming phase difference plates, which are A plates having different signs.   2. The stereoscopic image forming phase difference plate according to claim 1, wherein the first phase difference region of the first phase difference member is a positive A plate and the second phase difference member is a negative A plate.   The three-dimensional image formation phase difference plate according to claim 1, wherein the first phase difference region of the first phase difference member is a negative A plate, and the second phase difference member is a positive A plate.   The phase difference plate for three-dimensional image formation according to any one of claims 1 to 3, wherein the first phase difference region and the second phase difference region are arranged in a stripe shape.   The phase difference plate for stereoscopic image formation according to any one of claims 1 to 4 and a polarizing plate are laminated, and a slow axis direction in a second retardation region of the phase difference plate and the polarizing plate A polarizing element for forming a stereoscopic image, wherein the angle formed by the transmission axis direction is 45 °. The phase difference plate according to claim 1, a polarizing plate, and a video display cell.
A polarizing plate is disposed on the viewing side of the video display cell, and the retardation plate is disposed on the viewing side of the polarizing plate,
The angle formed by the slow axis direction in the second retardation region of the retardation plate and the transmission axis direction of the polarizing plate is 45 °,
The video display cell has a first video display area and a second video display area,
3D image display in which the first phase difference area and the second phase difference area of the phase difference plate are arranged so as to correspond to the first video display area and the second video display area of the video display cell, respectively. apparatus.

Images