JP2014174363A - Pattern phase difference film and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stripes corresponding to a region setting on a pattern phase difference film when viewing a two-dimensional image in an image display device of a passive type.SOLUTION: A pattern phase difference film 1 includes: a phase difference layer 4 on a transparent base material 2; and a first and second regions A and B providing different phase difference to transmitted light formed alternately and sequentially. The phase difference layer 4 is manufactured by reverse dispersion property.

Description

The present invention relates to a three-dimensional image display by a passive method.

  In recent years, an image display device that displays a three-dimensional image by a passive method has been provided. Here, FIG. 7 is a schematic view showing a passive type image display apparatus using a liquid crystal display panel. The passive-type image display apparatus sequentially assigns pixels of the liquid crystal display panel that are continuous in the vertical direction or the horizontal direction (vertical direction in the example of FIG. 7) to the right eye and the left eye, respectively. Driving with the image data for the left eye, thereby displaying the image for the right eye and the image for the left eye simultaneously. In addition, a pattern retardation film is arranged on the panel surface (viewer side) of the liquid crystal display panel so that the light emitted from the right-eye pixel and the left-eye pixel is linearly polarized light having different directions for the right-eye and left-eye. Convert to As a result, in the passive method, glasses equipped with corresponding polarizing filters are worn, and a right-eye image and a left-eye image are selectively provided to the viewer's right and left eyes, respectively, and a three-dimensional image is displayed. To do.

  Therefore, in the pattern retardation film, two types of band-like regions in which the slow axis direction (direction in which the refractive index is maximized) are orthogonal to each other are sequentially formed corresponding to the setting of the pixels in the liquid crystal display panel. Thus, in the passive method, glasses equipped with corresponding polarizing filters are worn, and a right-eye image and a left-eye image are selectively provided to the viewer's right eye and left eye, respectively. Here, as the slow axis direction of the adjacent band-like region, a combination of +45 degrees and −45 degrees, or 0 degrees and +90 degrees with respect to the horizontal direction is usually employed. In the example of FIG. 7, the long side direction of the screen is shown as the horizontal direction in accordance with the name in the normal image display apparatus.

  This passive method can also be applied to an image display device having a slow response speed, and can display three-dimensionally with a simple configuration using a pattern retardation film and circularly polarized glasses. In the passive type image display device, a method of sequentially assigning pixels continuous in the horizontal direction to the right eye and the left eye in place of the vertical direction in the example of FIG. 7 is also employed.

  The pattern phase difference film according to this passive method requires a pattern-like phase difference layer that gives a phase difference to transmitted light corresponding to the allocation of pixels. With respect to this pattern retardation film, Patent Document 1 discloses a method of forming a retardation layer by forming a photo-alignment layer on a glass substrate with controlled orientation regulating force and patterning the alignment of liquid crystals with this photo-alignment layer. Is disclosed. Patent Document 2 discloses a method of forming a photo-alignment layer in which a fine uneven shape is formed on the peripheral side surface of a roll plate by laser irradiation, and the uneven shape is transferred to control the alignment regulating force in a pattern shape. Has been.

  Liquid crystal materials applicable to the retardation layer of this optical film generally have positive wavelength dispersion characteristics, but in recent years, those having reverse dispersion characteristics have been proposed (Patent Documents 3, 4, and 5). . Here, the reverse dispersion characteristic is a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller as the wavelength is shorter, and more specifically, retardation at a wavelength of 450 nm (R450) and retardation at a wavelength of 550 nm (R550). Is a characteristic in which R450 <R550. On the contrary, the positive chromatic dispersion characteristic is a chromatic dispersion characteristic in which the phase difference in the transmitted light is smaller toward the longer wavelength side, and more specifically, R450> R550.

  Patent Document 6 discloses a film having reverse dispersion characteristics with respect to a transparent film applicable to this type of pattern retardation film.

  By the way, when viewing a two-dimensional image in an image display device that displays a three-dimensional image by a passive method, streaks may be seen on the display screen. In order to view a two-dimensional image related to the streak, the image display panel is driven by image data for displaying a two-dimensional image to display the two-dimensional image, and this display is not worn with circularly polarized glasses for displaying the three-dimensional image. This is the case of viewing with In the pattern retardation film, this streak is a region corresponding to the light output from the pixel for the right eye (hereinafter referred to as the region for the right eye) and the light output from the pixel for the left eye. In a region to which a phase difference is applied (hereinafter referred to as a left eye region), the screen is observed with different colors and different brightness. It is desirable to reduce as much as possible in the streaks relating to such color and brightness.

  In the passive type image display device, generation of various stripes including the stripes related to the color and light and dark is widely known. Specifically, when displaying a three-dimensional image, even lines and odd lines are assigned to the right eye and the left eye, respectively, so that in principle, streaks relating to the right eye region and the left eye region can be seen. However, the above-described color and light / dark lines are generated when viewing a two-dimensional image, which is different from the basic lines in the passive image display apparatus.

JP 2005-49865 A JP 2010-152296 A U.S. Pat. No. 8,119,026 JP 2009-179563 A Special table 2010-52892 Japanese Patent No. 4187594

  The present invention has been made in view of such circumstances, and in a passive image display device, it is possible to reduce streaks corresponding to setting of regions in a pattern retardation film when viewing a two-dimensional image. An object of the present invention is to provide a pattern retardation film and an image display device.

  The present inventor has conducted extensive research to solve the above-mentioned problems, paying attention to the point that Heidinger's brush cannot be seen with perfect circularly polarized light, and has come up with the idea of making the emitted light close to perfect circularly polarized light. The invention has been completed.

(1) In a pattern retardation film in which first and second regions different in retardation given to transmitted light are alternately provided in a retardation layer on a transparent substrate,
The retardation layer is produced with reverse dispersion characteristics.

  According to (1), since the retardation layer has reverse dispersion characteristics, when viewed in the wavelength direction, the transmitted light can be made closer to circularly polarized light, thereby corresponding to the setting of the region in the patterned retardation film. It is possible to reduce streaking.

(2) In (1),
The retardation layer is formed of a liquid crystal material having reverse dispersion characteristics.

  According to (2), the stripe corresponding to the setting of the area | region in a pattern phase difference film can be reduced by more specific structure.

  (3) The pattern retardation film of (1) or (2) is disposed on the panel surface of the image display panel.

  According to (3), it is possible to obtain an image display device in which streaks corresponding to the setting of regions in the pattern retardation film are reduced.

  In the passive image display device, it is possible to reduce streaks corresponding to the setting of the region in the pattern retardation film when viewing a two-dimensional image.

It is a figure which shows the confirmation result of the stripe in the image display apparatus by a passive system. It is a characteristic curve figure with which it uses for description of chromatic dispersion. It is a characteristic curve figure which shows the change of the ellipticity with a wavelength. It is a figure where it uses for description of ellipticity. It is a figure which shows the pattern phase difference film which concerns on 1st Embodiment of this invention. It is a figure which shows the pattern phase difference film which concerns on 2nd Embodiment of this invention. It is a figure where it uses for description of the three-dimensional image display by a passive system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Principle prevention principle]
FIG. 1 shows a two-dimensional image displayed in a passive type image display device, the display is photographed with a camera in front of the screen, and visually observed, and the color corresponding to the setting of the area in the pattern retardation film, It is the result of confirming streaks related to light and dark. Here, FPR indicates the slow axis direction in the right-eye region and the left-eye region in the pattern retardation film, and is an angle based on the extension direction of the right-eye region and the left-eye region. The polarizing plate indicates the transmission axis direction of the linear polarizing plate provided on the image display panel on the incident surface side of the pattern retardation film corresponding to the setting of the pattern retardation film.

  In this confirmation result, when the transmission axis direction of the polarizing plate is set to 0 degree or 90 degrees, the result (still image) photographed by the camera cannot detect the streak, but it is yellow in visual observation. Streaks were visible. In addition, when the transmission axis direction of the polarizing plate is set to 45 degrees, although light and dark streaks are confirmed by the camera and by visual observation, the light and dark streaks confirmed by visual observation indicate that the transmission axis direction of the polarizing plate is 0. When it was set at a degree or 90 degrees, it was of the same order as yellow streaks visually observed. Among these dark and light stripes, the dark stripe is apparently due to a change in the amount of light from the pattern retardation film by being confirmed by both the camera and the visual observation. However, a yellow streak is determined to be dependent on the human eye by being detected only by visual inspection.

  That is, the right-eye region and the left-eye region have different polarization states although the amount of light emitted from the pattern retardation film is the same. As a result, it is determined that the yellow stripe is caused by the fact that the human eye can perceive the polarized light even slightly. It should be noted that the endoscopic phenomenon in which human eyes perceive polarized light in this way is known as Heidinger's brush and has individual differences.

  Various investigations have revealed that Heidinger's brush is perceived in linearly polarized light and elliptically polarized light, but gradually disappears when elliptical polarized light approaches perfect circularly polarized light. It was found that no brush could be perceived. Therefore, in this embodiment, the streak corresponding to the setting of the region in the pattern retardation film is reduced by bringing the emitted light from the pattern retardation film close to ideal circularly polarized light.

  Here, in the pattern phase difference film, a phase difference is imparted to the transmitted light by a phase difference layer made of a liquid crystal material, and light emitted by linearly polarized light from the image display panel is converted into circularly polarized light having different rotation directions in the right eye region and the left eye region Is emitted. Here, the liquid crystal material applied to the retardation layer generally has a positive wavelength dispersion characteristic. As a result, in the pattern retardation film, incident light from the image display panel is completely circularly polarized at a specific wavelength. However, incident light cannot be emitted by perfect circular polarization except for this specific wavelength, and incident light can be emitted by elliptically polarized light except for this specific wavelength.

  Therefore, in this embodiment, by forming a retardation layer with inverse dispersion characteristics, the outgoing light when viewed in the wavelength direction is brought close to circularly polarized light, and streaks corresponding to the setting of regions in the pattern retardation film are reduced.

  FIG. 2 is a chart showing the amount of retardation when a retardation layer for a quarter-wave plate is produced with a constant thickness. In FIG. 2, symbol L1 indicates an ideal characteristic in which the phase difference increases in proportion to the increase in wavelength. Reference symbol L2 indicates characteristics of a liquid crystal material having a general positive dispersion characteristic, and reference numeral L3 indicates characteristics of a liquid crystal material having reverse dispersion characteristics. The liquid crystal material denoted by reference symbol L3 uses a mixture of compound (1), RM (1), and RM (3) described in JP-T-2010-522892 in a mixing ratio of 5: 3: 2, and a film thickness of 2.6 μm. It was produced by. Moreover, the characteristic of the code | symbol L4 is the film material by the cellulose acetate disclosed by patent 4187594 gazette.

  FIG. 3 is a diagram showing the ellipticity according to the characteristic of FIG. As shown in FIG. 4, the ellipticity is a ratio D = b / a of the major axis length a and minor axis length b in circularly polarized light, D = 0 is linearly polarized light, and D = 1. Is completely circularly polarized. Therefore, for elliptically polarized light, 1> D> 0. According to the characteristic curve of FIG. 4, the case of using a liquid crystal material having a reverse dispersion characteristic (reference L3) and the case of using a film material having a reverse dispersion characteristic compared to the case of using a positive dispersion characteristic (reference L2). In the case of L4), the ellipticity can be made closer to the value 1 in a wider wavelength band, thereby reducing the stripes corresponding to the setting of the region in the pattern retardation film.

  When the wavelength dispersion characteristic of the pattern retardation film is set to the inverse dispersion characteristic in this way, the wavelength dispersion characteristic is also set to the wavelength dispersion characteristic of the pattern retardation film even in glasses worn when viewing a three-dimensional image. By making it as close as possible, crosstalk can be suppressed and image quality deterioration can be prevented. In addition, color unevenness (color shift) can be suppressed by making the phase difference wavelength dispersion characteristics of the pattern phase difference film and the glasses reverse dispersion.

[First Embodiment]
FIG. 5 is a diagram showing a pattern retardation film applied to the image display device according to the first embodiment of the present invention. The image display apparatus according to the first embodiment includes a two-dimensional image display mode and a three-dimensional image display mode, and provides a three-dimensional image by a passive method in the three-dimensional image display mode. That is, in this three-dimensional image display mode, the image display device displays the image for the right eye alternately in succession with pixels that are continuous in the vertical direction of the image display panel (the horizontal direction in FIG. 5 is the corresponding direction). The right-eye pixels and the left-eye pixels that display the left-eye image are sorted and driven by the right-eye image data and the left-eye image data, respectively. As a result, the image display device alternately divides the display screen into a band-like region for displaying an image for the right eye and a band-like region for displaying an image for the left eye, so that the image for the right eye and the image for the left eye are divided. Display at the same time. In this image display device, the pattern phase difference film 1 shown in FIG. 5 is disposed on the panel surface of the liquid crystal display panel, and the pattern phase difference film 1 corresponds to light emitted from pixels for the right eye and the left eye, respectively. To give the phase difference. Thereby, this image display apparatus displays a desired three-dimensional image by a passive method.

  In contrast, in the two-dimensional image display mode, the image display panel is driven by continuous image data to display a two-dimensional image.

  Here, in the pattern retardation film 1, an orientation layer 3 and a retardation layer 4 are sequentially formed on one surface of a base material 2 made of a transparent film such as TAC (triacetyl cellulose). The pattern retardation film 1 is formed of a liquid crystal material that is solidified (cured) in a state in which the retardation layer 4 maintains refractive index anisotropy, and the alignment of the liquid crystal material is patterned by the alignment regulating force of the alignment layer 3. To do. Note that the orientation of the liquid crystal molecules is exaggerated by an elongated ellipse in FIG. By this patterning, the pattern phase difference film 1 has a certain width corresponding to the pixel assignment in the liquid crystal display panel, and the right eye region (first region) A and the left eye region (second region). ) B and B are sequentially formed in a band shape, and give phase differences corresponding to light emitted from the right-eye and left-eye pixels, respectively.

  In this embodiment, the retardation layer 4 is made of the liquid crystal material having the reverse dispersion characteristic described above with reference to the symbol L3, thereby reducing streaks corresponding to the region setting in the pattern retardation film 1.

  In the pattern retardation film 1, after the photo-alignment material layer is formed of the photo-alignment material, the photo-alignment material layer is irradiated with ultraviolet rays by linearly polarized light, and thereby the alignment layer 3 is formed by applying the photo-alignment technique. The Here, the ultraviolet light applied to the photo-alignment material layer is set so that the direction of polarization differs between the right-eye region A and the left-eye region B by 90 degrees, and thereby the liquid crystal material provided in the retardation layer 4 , Liquid crystal molecules are aligned in the corresponding directions in the right-eye region A and the left-eye region B, and a phase difference corresponding to transmitted light is given. In addition, although various materials to which the photo-alignment technique can be applied can be applied as the photo-alignment material, in this embodiment, the alignment is not changed by ultraviolet irradiation after the alignment, for example, a light dimerization type. Use materials. The light dimerization type material is described in “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H. Seiberle and A. Schuster: Nature, 381, 212 (1996), etc., and is already commercially available, for example, under the trade name “ROP-103” (Rolic technologies Ltd.).

  Instead of selectively exposing the right eye region or the left eye region in this way and then exposing the entire surface to produce an alignment layer, on the contrary, after the entire surface exposure processing, the right eye region or The alignment layer may be produced by selectively exposing the left eye region, or after selectively exposing the right eye region or the left eye region, the unexposed left eye region or the right eye region is selectively used. The alignment layer may be prepared by performing an exposure treatment. Further, instead of preparing the alignment layer by a photo-alignment technique, the alignment layer may be manufactured by forming a fine uneven shape by a rubbing process trace by a forming process.

  In this embodiment, the streaks corresponding to the region setting in the pattern retardation film 1 can be reduced by producing the retardation layer 4 from a liquid crystal material having reverse dispersion characteristics.

[Second Embodiment]
FIG. 6 is a view showing a patterned retardation film according to the second embodiment of the present invention. In the pattern retardation film 11 of this embodiment, a transparent film having reverse dispersion characteristics cut into a strip shape is disposed on one surface of a substrate 2 made of a transparent film such as TAC (triacetyl cellulose). Layer 14 is created. The transparent film having the reverse dispersion characteristic is the transparent film described above with reference to symbol L4. This transparent film is cut out and arranged so that directions extending 90 degrees in the right-eye area A and the left-eye area B are extended directions, so that the right-eye area A and the left-eye area B respectively correspond to transmitted light. Add phase difference.

  In this embodiment, even if the retardation layer is made of a transparent film having reverse dispersion characteristics, the same effect as that of the first embodiment can be obtained. Further, in such a transparent film, the reverse dispersion characteristic can be made closer to an ideal characteristic, so that the streak corresponding to the setting of the region can be further reduced as compared with the first embodiment.

Other Embodiment
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously combined or modified with the configuration of the above-described embodiment without departing from the spirit of the present invention. Can do.

  Moreover, although the case where it arrange | positions to the image display panel by a liquid crystal display panel was described in the above-mentioned embodiment, this invention is not restricted to this, When arrange | positioning to the image display panel by an organic EL element, the image display panel by a plasma display, etc. Can also be widely applied.

  In the above-described embodiment, the case of preventing yellow streaks based on polarized light has been described. However, the present invention is not limited to this, and in combination with a configuration for preventing dark streaks, both yellow and light streaks are perceived. It may not be possible.

DESCRIPTION OF SYMBOLS 1, 11 Pattern retardation film 2 Base material 3 Orientation layer 4, 14 Retardation layer

Claims (3)

In the phase difference film on the phase difference layer on the transparent substrate, the first and second regions having different phase differences given to the transmitted light are alternately provided in sequence,
A patterned retardation film in which the retardation layer is produced by reverse dispersion characteristics. The pattern retardation film according to claim 1, wherein the retardation layer is formed of a liquid crystal material having reverse dispersion characteristics. An image display device in which the pattern retardation film according to claim 1 or 2 is disposed on a panel surface of an image display panel.

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