JP2014134771A - Optical film, image display unit, exposure member, and exposure mask holding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film capable of reducing streaks caused by exposure range deviation.SOLUTION: An optical film includes: a transparent film base material 1; an optical alignment layer 2 formed on the transparent film base material 1; and a retardation layer 3 formed on the optical alignment layer 2 and aligned by alignment regulatory force of the optical alignment layer 2. The optical alignment layer 2 has an alignment region A and a region B with different alignment directions. A width of the border between the region A and the region B is 4.7-8.0 μm. A deviation σ of the width is 0.7 μm or smaller.

Description

  The present invention relates to a pattern retardation film, an image display device, an exposure member, and an exposure mask holding member.

  In recent years, flat panel displays capable of three-dimensional display have been provided. Here, in order to perform three-dimensional display on a flat panel display, it is usually necessary to selectively provide a right-eye image and a left-eye image to the viewer's right eye and left eye in some manner. . As a method for selectively providing a right-eye image and a left-eye image, for example, a passive method is known. This passive three-dimensional display method will be described with reference to the drawings.

  FIG. 7 is a schematic diagram showing an example of a passive three-dimensional display using a liquid crystal display panel. In the example of FIG. 7, pixels that are consecutive in the vertical direction of the liquid crystal display panel are sequentially and alternately assigned to a right-eye pixel that displays a right-eye image and a left-eye pixel that displays a left-eye image. And 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. As a result, the screen of the liquid crystal display panel is alternately switched into a region for displaying an image for the right eye and a region for displaying an image for the left eye, for example, by a band-shaped region in which the short side is vertical and the long side is horizontal. It is divided.

  Furthermore, in the passive method, a pattern retardation film is placed on the panel surface of the liquid crystal display panel, and light emitted from the linearly polarized light from the right-eye and left-eye pixels is converted into circularly polarized light with different rotation directions for the right-eye and left-eye. 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 maximum) are orthogonal to each other are sequentially formed corresponding to the setting of the region 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 strip region, a combination of +45 degrees and −45 degrees or a combination of 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 a liquid crystal display device with a slow response speed, and can also display three-dimensionally with a simple configuration using a pattern retardation film and circularly polarized glasses.

  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 alignment regulating force and patterning the alignment of liquid crystals with this photo-alignment layer. Is disclosed. Further, in Patent Document 2, a photo-alignment layer is prepared by exposing the entire surface and then exposing using an exposure mask, and aligning and curing the liquid crystal layer by the alignment regulating force of the photo-alignment layer. Discloses a method for producing a patterned retardation film.

  In this pattern retardation film, the photo-alignment layer is a region having a corresponding alignment regulating force, a region that gives an image for the right eye to the right eye of the viewer (hereinafter referred to as “region A”), a region A region oriented in a direction different from A and giving a left-eye image to the viewer's left eye (hereinafter, referred to as “region B”) needs to be alternately and closely formed. . These regions A and B are formed by irradiating the photo-alignment layer material with ultraviolet rays, which is one of active energy rays, through an exposure mask having a plurality of slits.

  FIG. 8 and FIG. 9 are diagrams for explaining the exposure performed to form the region A and the region B. FIG. FIG. 8 shows an ultraviolet light source 71 used for exposure, and FIG. 9 schematically shows a positional relationship among the light source 71, the exposure mask 72, the transparent film substrate 74, and the roll 73 during exposure. In the exposure process, the transparent film substrate 74 (triacetate cellulose (TAC), acrylic, etc.) coated with the photo-alignment film material by the roll 73 is conveyed through an exposure mask 72 arranged to face the roll 73. Ultraviolet rays are emitted from the light source 71. The light source 71 is provided with a plurality of light source units 71a each provided with an ultraviolet irradiation lamp in order to secure the amount of ultraviolet light necessary for the exposure processing. In the example of FIG. 8, the plurality of light source units 71a are arranged in the horizontal direction. Provided in a two-row staggered arrangement.

JP 2005-49865 A JP 2012-42530 A

  As shown in FIG. 8, in this type of exposure apparatus, the light beam emitted from the light source unit has a collimation angle, and in the slit irradiated with the light beam from a plurality of light source units, the collimation angles of the respective light beams are used. The range (exposure range) in which the light alignment material film on the transparent film substrate 74 is irradiated with the light beam passing through the slit is shifted in each light source unit.

  FIG. 10 is a diagram for explaining the positional deviation of the exposure range. Δ2 shown in FIG. 10 is a deviation caused by a plurality of rows of light source units 71a arranged in the horizontal direction (TD direction shown in FIG. 9). Further, Δ1 shown in FIG. 10 is a shift caused by arranging a plurality of light source units 71a in the vertical direction (MD direction orthogonal to the TD direction shown in FIG. 9).

  In the image display device using the pattern retardation film, a stripe extending in the horizontal direction, which is the extending direction of the regions A and B, may be observed. More specifically, this streak is observed by a gradation in which the luminance level of the display screen gradually changes in the vertical direction, which is a direction orthogonal to the extension direction of the streak, and is thereby observed by a streak extending in the horizontal direction. . As a result of various investigations, this streak is caused by the above-described shift in the exposure range changing in the repeating direction of the regions A and B, so that the boundary width of the regions A and B changes in the repeating direction of the regions A and B. Was found to occur. Note that the boundary between such regions A and B is a region where the alignment layer is not exposed with a sufficient amount of light, and the alignment layer is a region where the alignment regulating force is not sufficiently provided. Layer) is an unoriented region.

  The positional deviation of the exposure range shown in FIG. 10 can be reduced by bringing the exposure mask 72 and the roll 73 close to each other. Therefore, it can be considered that the occurrence of streaks due to the deviation of the exposure range can be reduced in this way. However, it is known that in the ultraviolet exposure process, the holding member that holds the exposure mask 72 is heated and bent during the exposure process, and the distance between the exposure mask 72 and the roll 73 cannot be kept constant. For this reason, at present, the distance between the exposure mask 72 and the roll 73 is restricted, and streaks caused by such a shift in the exposure range cannot be sufficiently suppressed.

  The present invention has been made in view of the above points, and is used for the production of an optical film capable of reducing streaks caused by a shift in an exposure range, an image display device including the optical film, and an optical film. It is an object of the present invention to provide an exposure member and an exposure mask holding member.

  The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems, and have come to the idea of suppressing the deflection of the exposure mask for forming the photo-alignment layer, thereby completing the present invention. .

(1) a film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer is
A first region formed by irradiation with active energy rays linearly polarized in the first polarization direction; and formed by irradiation with active energy rays linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region, and the first region and the second region have a band-like shape in plan view, and are alternately arranged.
The optical film, wherein a width of a boundary between the first region and the second region is 4.7 μm or more and 8.0 μm or less, and a deviation σ of the width is 0.7 μm or less. .
According to (1), it is possible to provide an optical film that suppresses streaks generated by a change in the boundary width between the first region and the second region.
(2) An image display device comprising the optical film according to (1) disposed on a surface of an image display panel.
According to (2), it is possible to provide an image display device including an optical film that suppresses streaks generated by a change in the boundary width between the first region and the second region.
(3) An exposure member used for production of an optical film,
The optical film is
A film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer includes a first region formed by irradiation of active energy rays linearly polarized in a first polarization direction, and an active energy linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region formed by irradiation of a line, and the first region and the second region have a belt-like shape in plan view, and are alternately arranged.
The exposure member is:
An exposure mask used for irradiation with the active energy ray, and an exposure mask holding member for holding the exposure mask,
The holding member is
A frame for fixing the exposure mask;
When the frame with the exposure mask fixed is heated at 65 ° C. for 120 minutes, the surface of the film base and the side of the exposure mask facing the film base before and after the heating An exposure member characterized in that a change in the amount of warpage represented by the difference between the minimum value and the maximum value of the distance between the two is kept within 40 μm.
According to (3), the change in the amount of warp of the exposure mask in the exposure process can be reduced, and the distance between the exposure mask surface and the film substrate surface can be kept constant. As a result, the distance can be reduced to reduce the deviation of the exposure range. As a result, the change in the boundary width between the first area and the second area is reduced, and the streak caused by the change in the boundary width is reduced. Can be reduced. In addition, by reducing the distance in this way, light scattering at the slit end can be suppressed, which also reduces the change in the boundary width between the first region and the second region, and reduces the streak generated by the change in the boundary width. Can be reduced.
(4) An exposure mask holding member used for production of an optical film,
The optical film is
A film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer includes a first region formed by irradiation of active energy rays linearly polarized in a first polarization direction, and an active energy linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region formed by irradiation of a line, and the first region and the second region have a belt-like shape in plan view, and are alternately arranged.
The exposure mask is
An exposure mask for irradiation with the active energy ray,
The holding member is
A frame for fixing the exposure mask;
When the frame with the exposure mask fixed is heated at 65 ° C. for 120 minutes, the surface of the film base and the side of the exposure mask facing the film base before and after the heating A holding member for an exposure mask, characterized in that a change in the amount of warpage represented by a difference between a minimum value and a maximum value of the distance to the distance is held within 40 μm.
According to (4), the change in the amount of warp of the exposure mask in the exposure process can be reduced, and the distance between the exposure mask surface and the film substrate surface can be kept constant. As a result, the exposure mask can be exposed sufficiently close to the film substrate, the deviation of the exposure range can be reduced, the change in the boundary width between the first area and the second area can be reduced, and this boundary width can be reduced. It is possible to reduce the streak caused by the change. In addition, by exposing the exposure mask sufficiently close to the film substrate in this way, light scattering at the slit end can be suppressed, and this also reduces the change in the boundary width between the first region and the second region. It is possible to reduce streaks caused by changes in the boundary width.
(5) The exposure mask holding member according to (4), wherein the frame is made of a material having a linear expansion coefficient of 0 to 12.4 × 10 ⁻⁶ / ° C. or less.
According to (5), the change in the amount of curvature of the exposure mask in the exposure process is reduced by using a material of the frame body having a linear expansion coefficient of 0 to 12.4 × 10 ⁻⁶ / ° C. or less, and the exposure mask The distance between the surface and the film substrate surface can be kept constant.
(6) The exposure mask holding member according to (5), wherein the material of the frame is any one of granite, invar, super invar, cobalt, quartz glass, ceramic, and ultra-low thermal expansion cast iron.
According to (6), the change in the amount of warpage of the exposure mask in the exposure process can be achieved by the fact that the material of the frame is any one of microgranite, invar, superinvar, cobalt, quartz glass, ceramic, and ultra-low thermal expansion cast iron. The distance between the exposure mask surface and the film substrate surface can be kept constant.

  INDUSTRIAL APPLICABILITY The present invention can provide an optical film that can reduce streaks caused by deviations in the exposure range, an image display device that includes the optical film, an exposure mask holding member that is used to create the optical film, and an exposure mask. .

It is a figure for demonstrating the pattern phase difference film formed with the optical film of 1st Embodiment of this invention. It is a flowchart for demonstrating the manufacturing process of the pattern phase difference film of 1st Embodiment of this invention. FIG. 3 is a schematic diagram for explaining the process of step S202 shown in the flowchart shown in FIG. It is a figure for demonstrating the holding member for hold | maintaining the exposure mask shown in FIG. It is a figure for demonstrating the effect of 1st Embodiment. It is the figure which showed the boundary width at the time of holding and exposing an exposure mask with the holding member made from a microgranite shown in FIG. It is the schematic which shows an example of the three-dimensional display of a passive system using a liquid crystal display panel. It is a figure for demonstrating the exposure performed in order to form the area | region A and the area | region B. FIG. It is the figure which showed the light source used for the exposure for forming an alignment layer. It is a figure where it uses for description of the position shift of exposure.

Hereinafter, the first to third embodiments of the present invention will be described.
[First Embodiment]
FIG. 1 is a diagram for explaining a patterned retardation film 10 formed as an optical film according to the first embodiment of the present invention. In FIG. 1, the image display device 100 is held by attaching a pattern retardation film 10 to a panel surface (viewer side surface) of a liquid crystal display panel 11 with an adhesive (not shown).

  In the image display device 100, the pixels of the liquid crystal display panel 11 that are continuous in the vertical direction (the left and right directions are the corresponding directions in FIG. 1) are alternately displayed. Are distributed to the left-eye pixels for displaying the image, and are 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 the image display device 100, the pattern phase difference film 10 is disposed on the panel surface of the liquid crystal display panel 11, and the pattern phase difference film 10 gives a phase difference corresponding to light emitted from the right eye pixel and the left eye pixel, respectively. Thereby, the image display apparatus 100 displays a desired stereoscopic image by a passive method.

  Here, the pattern retardation film 10 has a photo-alignment layer 2, a retardation layer 3, and an adhesive layer (on the one surface of a transparent film substrate 1 made of a transparent film such as TAC (triacetyl cellulose) and acrylic. (Not shown) are sequentially formed and held on the panel surface of the image display panel by this adhesive or the like. In the pattern retardation film 10, the retardation layer 3 is formed of a liquid crystal material that is solidified (cured) while maintaining the refractive index anisotropy, and the alignment of the liquid crystal material is patterned by the alignment regulating force of the photo-alignment layer 2. Ning. In FIG. 1, the orientation of the liquid crystal molecules is exaggerated by an elongated ellipse. By patterning by the alignment regulating force of the alignment layer 2, the pattern retardation film 10 has a right width region A and a left eye region B with a certain width corresponding to the pixel assignment in the liquid crystal display panel. It is formed in a strip shape alternately and sequentially, and gives a phase difference corresponding to light emitted from the right-eye and left-eye pixels.

  In the pattern retardation film 10, after the photo-alignment material film is formed of the photo-alignment material, the photo-alignment layer 2 is formed by irradiating the photo-alignment material film with ultraviolet rays by linearly polarized light by a so-called photo-alignment technique . Here, the ultraviolet light applied to the photo-alignment material film is set so that the direction of polarization differs between the right-eye region A and the left-eye region B by 90 degrees, whereby the liquid crystal material provided in the retardation layer 3 , 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.

  For this light dimerization type material, see “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) "and the like, and already marketed under the trade name" ROP-103 ", for example.

  Further, as the liquid crystal material related to the retardation layer 3, a conventionally known retardation layer material can be used. An example of such a material is a liquid crystal material that exhibits a nematic liquid crystal phase. As a liquid crystal material that exhibits a nematic liquid crystal phase, a conventionally known liquid crystal material may be used, and examples thereof include rod-like liquid crystal molecules, polymer liquid crystals, and polymerizable liquid crystal compounds.

[Manufacturing process of optical film]
FIG. 2 is a flowchart for explaining the manufacturing process of the pattern retardation film of the first embodiment. In the manufacturing process of the pattern retardation film, the transparent film substrate 1 is sequentially drawn from the roll, and the photo-alignment material film is sequentially formed (step S201). Various manufacturing methods can be applied to the photo-alignment material film. In the first embodiment, a film-forming liquid in which a photo-alignment material is dispersed in a solvent such as benzene is applied by a die and then dried.

Subsequently, in the manufacturing process of the first embodiment, the region A or the region B (referred to as the region A in FIG. 2) is irradiated with polarized ultraviolet rays, and the region A or the region B is exposed (step S202). Next, the entire surface of the photo-alignment material film including the regions A and B is exposed (step S203). The photo-alignment layer 2 is created by steps S202 and S203. The polarized ultraviolet rays irradiated in step S202 and the polarized ultraviolet rays irradiated in step S203 are linearly polarized ultraviolet rays whose polarization directions, which are the first polarization direction and the second polarization direction, differ from each other by 90 degrees. In some cases, the pattern retardation film is first exposed with polarized ultraviolet rays after the entire surface is exposed to a photo-alignment material, and then exposed using a mask. In this case, the order of step S202 and step S203 is switched.
Subsequently, in the first embodiment, after a liquid crystal material is applied on the photo-alignment layer 2 by a die or the like (step S204), the liquid crystal material is dried by heating (step S205). Further, after drying, the liquid crystal material is cured by ultraviolet irradiation (step S206), and the retardation layer 3 made of liquid crystal is formed. The film subjected to the above-described processing is subjected to an antireflection film forming process or the like as necessary, and then cut into a desired size in the cutting step to become the pattern retardation film 10.

  FIG. 3 is a schematic diagram for explaining the process of step S202 shown in the flowchart shown in FIG. In this process, the exposure mask 16 is disposed so as to face the roll 17 so as to be wound around the roll 17 having a large diameter and transport the transparent film substrate 1, and ultraviolet rays due to linearly polarized light pass through the exposure mask 16. The region A shown in FIG. In the exposure mask 16, slits S extending in the MD direction, which is the transport direction of the transparent film substrate 1, are repeatedly formed at a constant pitch in the TD direction orthogonal to the extending direction. The material 1 is irradiated with ultraviolet rays. The exposure mask 16 is made of synthetic quartz having a light shielding film made of a chromium film on one side, and a slit S is formed in this light shielding film. The length of the slit S in the extending direction is 5 to 100 mm.

  The exposure mask 16 is arranged so that the vertical line from the surface of the exposure mask 16 substantially intersects with the rotation axis of the roll 17 at substantially the center in the longitudinal direction of the slit S. In the first embodiment, before the start of the process of step S202, the distance between the exposure mask 16 and the surface of the roll 17 related to this vertical line (the surface of the roll 17 and the exposure at the part where the surface of the roll 17 is closest to the exposure mask 16). The exposure mask 16 is held by a holding member at a position where the distance from the surface of the mask 16 is approximately 150 μm. The distance between the exposure mask 16 and the surface of the roll 17 can be set to 100 μm or more and 200 μm or less, and exposure processing can be performed with practically sufficient accuracy. Here, the state before the start of this step is a state in which the irradiation of ultraviolet rays has not started, and each member is kept at room temperature (about 20 degrees).

4A and 4B are views for explaining the holding member 20 for holding the exposure mask 16 shown in FIG. 4A is a top view of the holding member 20, and FIG. 4B is an end view of the holding member 20 along the arrow AA ′ shown in FIG. 4A.
The holding member 20 is a holding member for the exposure mask 16 for holding the exposure mask 16 used for exposure of the photo-alignment layer material formed on the transparent film substrate 1. The holding member 20 includes a frame body 21 that fixes the exposure mask 16.
The frame 21 has a member 21a that contacts the surface of the exposure mask 16 facing the roll 17, and a member 21b that contacts the back surface of the exposure mask 16. A transparent film is formed on the upper and lower ends of the exposure mask 16 by these members 21a and 21b. A concave groove extending in a direction corresponding to the width direction of the substrate 1 is formed, and the exposure mask 16 is held on the front and back by the concave groove.

  By the way, it is known that when exposure is performed while holding the exposure mask 16 on the frame body 21, the frame body 21 is heated by the irradiation of ultraviolet rays and the temperature rises. The temperature rise due to this heating increases as the exposure time increases. At this time, the frame body 21 bends the exposure mask 16 in a direction in which the central portion moves away from the surface of the roll 17, and the distance between the exposure mask 16 and the surface of the roll 17 changes. More specifically, the distance between the exposure mask 16 and the surface of the roll 17 is the smallest at both ends in the continuous direction of the slit (150 μm described above), and this distance is the largest in the central portion in the continuous direction of the slit. growing.

In the first embodiment, when the frame body 21 with the exposure mask 16 fixed is heated at 65 degrees for 120 minutes, the exposure mask 16 before and after this heating (hereinafter referred to as “preheating”). The distance between the surface of the transparent film substrate 1 (hereinafter referred to as “exposure mask surface”) and the surface of the transparent film substrate 1 facing the transparent film substrate 1 (which is the same as the surface of the roll 17 in the first embodiment). The difference between the maximum value and the minimum value (hereinafter referred to as “warping amount”) was set within 22%.
Specifically, 1st Embodiment comprised the frame 21 with the microgranite which is a material whose linear expansion coefficient is 0-12.4 * 10 < ^-6 > / degrees C or less.

FIG. 5 is a diagram for explaining the effect of the first embodiment, and shows that the warpage amounts of the frame body 21 and the exposure mask 16 change before and after the preheating. The data shown in the graph of FIG. 5 is obtained by fixing an exposure mask 16 made of quartz glass to a frame body 21 of microgranite. The vertical axis in FIG. 5 indicates the distance (gap) between the surface of the exposure mask 16 and the surface of the roll 17, and the horizontal axis indicates the length in the width direction of the exposure mask 16 with reference to one end of the exposure mask 16. It shows.
Among the plots shown in FIG. 5, the black rhombus plot indicates data before the preheating of the exposure mask 16, and the black square plot indicates data after the preheating of the exposure mask 16.

  In addition, among the plots shown in FIG. 5, the white circle plot and the X-shaped plot indicate data of the existing technology for comparison with the first embodiment. In the existing technology, exposure is performed by holding the exposure mask 16 using a holding member made of extra super duralumin (JIS standard “A7075”). The white circle plot is preheated, and the x-shaped plot is preheated. The latter data is shown.

As shown in FIG. 5, the warp amount before preheating of the exposure mask 16 of the first embodiment is 232 μm, whereas the warp amount after preheating is 272 μm. That is, the holding member 20 of the first embodiment is a member having a linear expansion coefficient of 8.3 × 10 ⁻⁶ / ° C., and the change in the warpage amount before and after the preheating is 40 μm. For this reason, 1st Embodiment satisfy | fills the conditions that the change of the curvature amount will be less than 40 micrometers before and after preheating for 65 degree | times and 120 minutes.
On the other hand, when the exposure mask 16 is held using a holding member made of ultra-geraldine as in the existing technology, the amount of warp of the exposure mask is 214 μm as in the first embodiment before the preheating. After preheating, the thickness is 494 μm. Therefore, it can be seen that the holding member of the existing technology changes the amount of warp of the exposure mask 16 by 280 μm before and after the preheating.

  As described above, the holding member 20 according to the first embodiment can reduce the warpage of the exposure mask that occurs during the exposure process as compared with the existing technology. For this reason, since the change in the distance between the exposure mask 16 and the surface of the roll 17 during the exposure process is small, the exposure mask 16 can be arranged close to the roll 17. Then, by bringing the exposure mask 16 close to the roll 17, the deviation of the exposure range described above with reference to FIG. 10 can be reduced, and the change in the boundary width between the area A and the area B can be reduced. It is possible to reduce streaks caused by the change in the boundary width. Moreover, by making it approach in this way, the light scattering of a slit edge part can be suppressed, and also by this, the change of a boundary width can be reduced and a streak can be suppressed.

FIG. 6 is a diagram showing the width of the boundary appearing at the boundary between the region A and the region B of the photo-alignment layer 2 exposed by holding the exposure mask 16 with the holding member 20 made of microgranite shown in FIG. The width of this boundary is determined by arranging the pattern retardation film between the orthogonal polarizing plates in the orthogonal Nicol arrangement and rotating the pattern retardation film so that the regions A and B are in the extinction position. The peak value of the transmitted light amount to be measured is measured, and the distance between the parts where the light amount of 5% of the peak value is detected is measured. The vertical axis in FIG. 6 is the length obtained by actually measuring the width of the boundary, and the horizontal axis indicates the length in the width direction of the transparent film substrate 1 with reference to the pattern end.
The data shown in FIG. 6 was obtained by holding the exposure mask 16 by the holding member 20 so that the minimum distance between the exposure mask 16 and the surface of the roll 17 was 150 μm, as shown in FIG. Is. As shown in the figure, according to the first embodiment, the boundary width can be in the range of 4.7 μm or more and 8 μm or less. As a result, the change in the boundary width is reduced, and the generation of streaks is sufficiently achieved. I was able to suppress it.
Specifically, σ = 0.7 μm was obtained by substituting the data shown in FIG. 6 into the equation (1) representing the standard deviation σ. Therefore, when the standard deviation σ is large, the boundary width varies widely, and the standard deviation σ is 0.7 μm or less, so that streaks can be reliably prevented.
In equation (1), “n” is the number of data, “x” is the value of each data, and the bar of “x” is the average value.

In addition, as a material having a linear expansion coefficient of 0 to 12.4 × 10 ⁻⁶ / ° C. or lower, invar, super invar, cobalt, quartz glass, and ceramics can be applied in addition to microgranite. The linear expansion coefficients of Invar, Super Invar, Cobalt, Quartz Glass, Ceramics, and Ultra Low Thermal Expansion Cast Iron are as follows.
・ Invar 1.2 × 10 ^-6 / ℃
・ Super Invar 0.0 × 10 ^-6 / ℃
・ Cobalt 12.4 × 10 ^-6 / ℃
・ Quartz glass 0.56 × 10 ^-6 / ℃
・ Ceramics 7.1 × 10 ^-6 / ℃
・ Ultra low thermal expansion cast iron 0-3.5 × 10 ^-6 / ℃
In addition, the holding member can be made of any material other than the above materials as long as the linear expansion coefficient is 0 to 12.4 × 10 ⁻⁶ / ° C.

[Other Embodiments]
Note that the embodiment of the present invention is not limited to the configuration described above. For example, in the first embodiment, the photo-alignment layer and the retardation layer are formed by irradiating ultraviolet rays, but the present embodiment is not limited to such a configuration. For example, the photo-alignment layer or the retardation layer may be formed using a material that uses an electron beam as the active energy ray and is cured by irradiation with the electron beam.

  Alternatively, after selectively exposing the region A or B using an exposure mask, instead of exposing the entire surface, after exposing the entire surface, the region A or B is selectively exposed using the exposure mask. The present invention can also be widely applied when the regions A and B are sequentially exposed using an exposure mask.

1: Transparent film substrate 2: Photo-alignment layer 3: Retardation layer 3a: Liquid crystal material 10: Pattern retardation film 11: Liquid crystal display panel 16: Exposure mask 17: Roll 20: Holding member 21: Frame body 21a, 21b: Member 100: Image display device

Claims (6)

A film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer is
A first region formed by irradiation with active energy rays linearly polarized in the first polarization direction; and formed by irradiation with active energy rays linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region, and the first region and the second region have a band-like shape in plan view, and are alternately arranged.
An optical film, wherein a width of a boundary between the first region and the second region is 4.7 μm or more and 8.0 μm or less, and a deviation σ of the width is 0.7 μm or less. . An image display device comprising the optical film according to claim 1 disposed on a surface of an image display panel. An exposure member used for production of an optical film,
The optical film is
A film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer includes a first region formed by irradiation of active energy rays linearly polarized in a first polarization direction, and an active energy linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region formed by irradiation of a line, and the first region and the second region have a belt-like shape in plan view, and are alternately arranged.
The exposure member is:
An exposure mask used for irradiation with the active energy ray, and an exposure mask holding member for holding the exposure mask,
The holding member is
A frame for fixing the exposure mask;
When the frame with the exposure mask fixed is heated at 65 ° C. for 120 minutes, the surface of the film base and the side of the exposure mask facing the film base before and after the heating An exposure member characterized in that a change in the amount of warpage represented by the difference between the minimum value and the maximum value of the distance between the two is kept within 40 μm. An exposure mask holding member used for production of an optical film,
The optical film is
A film substrate;
A photo-alignment layer formed on the film substrate;
A retardation layer formed on the photo-alignment layer and oriented by an orientation regulating force of the photo-alignment layer,
The photo-alignment layer includes a first region formed by irradiation of active energy rays linearly polarized in a first polarization direction, and an active energy linearly polarized in a second polarization direction that is 90 degrees different from the first polarization direction. A second region formed by irradiation of a line, and the first region and the second region have a belt-like shape in plan view, and are alternately arranged.
The exposure mask is
An exposure mask for irradiation with the active energy ray,
The holding member is
A frame for fixing the exposure mask;
When the frame with the exposure mask fixed is heated at 65 ° C. for 120 minutes, the surface of the film base and the side of the exposure mask facing the film base before and after the heating A holding member for an exposure mask, characterized in that a change in the amount of warpage represented by a difference between a minimum value and a maximum value of the distance to the distance is held within 40 μm. 5. The exposure mask holding member according to claim 4, wherein the frame is made of a material having a linear expansion coefficient of 0 to 12.4 × 10 ⁻⁶ / ° C. or less.   6. The exposure mask holding member according to claim 5, wherein the material of the frame is any one of granite, invar, super invar, cobalt, quartz glass, ceramic, and ultra-low thermal expansion cast iron.