JP2014219596A - Production method of optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an optical film such as a patterned retardation film or the like relating to three-dimensional image display employing a passive system, with high appearance qualities even when a photo-alignment layer is made by repeating an exposure process using a mask.SOLUTION: A production method of an optical film includes: a first exposure step of exposing a photo-alignment material film by using a first mask 16A having a plurality of slits S corresponding to a first region; and a second exposure step of exposing the photo-alignment material film by using a second mask 16B having a plurality of slits S corresponding to a second region. The exposure steps are set in such a way that an area exposed to light passing through the slits of the first mask 16A partially overlaps an area exposed to light passing through the slits of the second mask 16B.

Description

  The present invention relates to a pattern retardation film applied to a passive three-dimensional image display, and relates to a manufacturing method in the case of forming an alignment film by a photo-alignment technique.

  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. 8 is a schematic diagram showing an example of a passive three-dimensional display using a liquid crystal display panel. In the example of FIG. 8, 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 will be 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 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. 8, 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 for forming a retardation layer by forming a photo-alignment film with controlled alignment regulating force on a glass substrate and patterning the alignment of liquid crystals with this photo-alignment film. Is disclosed. Further, in Patent Document 2, a photo-alignment film is prepared by performing an exposure process using the mask after the entire surface is exposed, and aligning and curing the liquid crystal layer by the alignment regulating force of the photo-alignment film. A method for producing a pattern retardation film is disclosed.

By the way, in the case where a photo-alignment film is produced by performing an exposure process using a mask after the entire surface is exposed, the photo-alignment film material aligned in a specific direction by the exposure process on the entire surface is exposed using the mask. It is necessary to reorient locally by processing. As a result, in the exposure process using the mask, it is necessary to irradiate an excessive amount of light (for example, about twice to three times the amount of light when the entire surface is exposed).
Depending on the material of the photo-alignment film, there may be a method in which the entire surface is exposed in the second exposure after exposure using a mask in the first exposure. In this case, it is necessary to expose the first exposure side with an excessive amount of light so that rewriting does not occur in the second exposure.
Incidentally, when irradiating an excessive amount of light in this way, the configuration of the light source becomes large and the thermal stress of the irradiation target becomes excessive.

  For this reason, it is desirable to produce an alignment film by repeating exposure processing using a mask. Further, in the case of a patterned retardation film, it is required to produce it with high appearance quality even when the alignment film is produced by repeating the exposure process using a mask.

JP 2005-49865 A JP 2012-042530 A

  The present invention has been made in view of such a situation, and for an optical film such as a patterned retardation film related to passive three-dimensional image display, a photo-alignment film is produced by repeating exposure processing using a mask. Even in such a case, the object is to enable creation with high quality.

  The present inventor has made extensive studies to solve the above problems, and in a mask to be subjected to repeated exposure processing, when the slit width is made wide so that the slits related to the two masks overlap at the slit width direction end. As a result, the present invention has been completed.

    Specifically, the present invention provides the following.

(1) An optical system in which an alignment film and a retardation layer are sequentially provided on a substrate made of a transparent film material, and first and second regions having different retardations to be transmitted to the retardation layer are sequentially provided alternately. In the film manufacturing method,
A photo-alignment material film production step of producing a photo-alignment material film on the substrate;
An alignment film preparation step of exposing the photo-alignment material film to prepare the alignment film by a photo-alignment film; and
A retardation layer production step of producing the retardation layer on the alignment film,
The alignment film manufacturing step includes
A first exposure step of exposing the photo-alignment material film using a first mask having a plurality of slits corresponding to the first region;
A second exposure step of exposing the photo-alignment material film using a second mask having a plurality of slits corresponding to the second region,
The area exposed by the light passing through the slit of the first mask and the area exposed by the light passing through the slit of the second mask were set to partially overlap.

  According to (1), even when the alignment of the mask varies, the occurrence of unoriented regions can be prevented, thereby ensuring high appearance quality.

(2) In (1),
The first mask and the second mask have different slit widths.

  According to (2), the slit width of the first or second mask is made narrow according to the characteristics of the material related to the alignment film, and the first and second region widths are set to the same width. be able to.

(3) In (1) or (2),
The substrate is provided by a roll;
The alignment film manufacturing step includes
Producing the alignment film sequentially while transporting the substrate,
The first and second masks are
The first and second masks were made of common members.

  According to (3), the thermal deformation in the first and second masks can be made equal, and an optical film can be produced with high accuracy.

  According to the present invention, an optical film such as a pattern retardation film relating to a passive three-dimensional image display can be produced with high appearance quality even when a photo-alignment film is produced by repeating exposure processing using a mask. Can be.

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 manufacturing process of the pattern phase difference film of FIG. It is a figure where it uses for description of the repeating exposure process. It is a figure where it uses for description of an exposure process. It is a figure where it uses for description of a mask. It is a figure where it uses for description of the superimposition of a mask. It is a figure where it uses for description of the manufacturing process which concerns on 2nd Embodiment of this invention. It is a figure where it uses for description of a pattern phase difference film.

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

[First Embodiment]
FIG. 1 is a diagram showing a pattern retardation film applied to the image display device according to the first embodiment of the present invention. In the image display device according to the first embodiment, the pixels of the liquid crystal display panel that are continuous in the vertical direction (the left-right direction is the corresponding direction in FIG. 1) sequentially and alternately display the right-eye image. The pixels are assigned to the left-eye pixels for displaying the left-eye image and the left-eye image, and are driven by the right-eye and 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. Display at the same time. In this image display device, a pattern phase difference film 1 is disposed on the panel surface (viewer side surface) of the liquid crystal display panel, and the pattern phase difference film 1 corresponds to light emitted from right-eye and left-eye pixels, respectively. To give the phase difference. Thereby, this image display apparatus displays a desired three-dimensional image by a passive method.

  Here, in the pattern retardation film 1, an alignment film 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), acrylic, and COP. In the phase retardation film 1, a retardation layer 4 is formed of a liquid crystal material that is solidified (cured) while maintaining refractive index anisotropy, and the alignment of the liquid crystal material is patterned by the alignment regulating force of the alignment film 3. To do. In FIG. 1, the orientation of the liquid crystal molecules is exaggerated by an elongated ellipse. By this patterning, the pattern phase difference film 1 has a right width region (first region) A and a left eye region (second region) with a certain width corresponding to the pixel assignment in the liquid crystal display panel. ) 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.

  After the photo-alignment material film is made of the photo-alignment material, the pattern retardation film 1 is irradiated with ultraviolet rays by linearly polarized light by a so-called photo-alignment technique, and thereby the alignment film 3 is formed by the photo-alignment film. Is formed. Here, the ultraviolet rays applied to the photo-alignment material film are set so that the direction of polarization is different by 90 degrees between the right-eye region A and the left-eye region B, whereby 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. As the photo-alignment material, various materials to which a photo-alignment technique can be applied can be applied.

  FIG. 2 is a flowchart showing manufacturing steps of the pattern retardation film 1. In the manufacturing process of the pattern retardation film 1, the base material 2 is provided by a long film wound around a roll, and the photo-alignment material film is sequentially produced by feeding the base material 2 out of the roll (steps SP1-SP2). . Here, although various manufacturing methods can be applied to the photo-alignment material film, in this embodiment, a film-forming liquid in which the photo-alignment material is dispersed in a solvent such as benzene is applied by a die or the like, Made by drying.

  Subsequently, in this manufacturing process, a photo-alignment film is produced by irradiating ultraviolet rays in the exposure process (step SP3). Subsequently, in this manufacturing process, after the liquid crystal material is applied by a die or the like in the retardation layer manufacturing process, the liquid crystal material is cured by irradiation with ultraviolet rays, and the retardation layer 4 is manufactured (step SP4). Subsequently, in this manufacturing process, after performing an antireflection film manufacturing process or the like as necessary, in the cutting process, the pattern phase difference film 1 is manufactured by cutting out to a desired size (steps SP5 to SP6).

  FIG. 3 shows the details of this exposure process. This manufacturing process is performed by irradiating ultraviolet rays (polarized ultraviolet rays) by linearly polarized light through a mask 16A that shields a portion corresponding to the region A for the right eye or the region B for the light eye. In the left eye region B or the right eye region A, the photo-alignment material film is oriented in a desired direction (FIG. 3A). Thereby, this manufacturing process executes the first exposure process. Subsequently, this manufacturing process is opposite to the first exposure process, and the polarization direction of the first exposure process is 90 through the mask 16B that shields the part corresponding to the left eye region B or the right eye region A. The right-eye region A or the left-eye region B is subjected to an exposure process with different linearly polarized light, and the photo-alignment material film is oriented in a desired direction in the right-eye region A or the light-eye region B (FIG. 4B )). Thus, in this manufacturing process, the alignment film 3 is produced by sequentially exposing the region A for the right eye and the region B for the left eye by two exposure processes each using a mask. Thus, in this embodiment, the alignment film 3 is produced by two exposure processes using a mask.

  FIG. 4 is a diagram showing equipment used for the exposure process using the first mask. In this manufacturing process, a mask 16A used for the first exposure process is disposed so as to face the roll 17 so as to be wound around a roll 17 having a large diameter and to face the roll 17, and ultraviolet rays due to linearly polarized light are masked. Irradiated via 16A. In the mask 16 </ b> A, slits S extending in the conveyance direction of the base material 2 are repeatedly formed at a constant pitch in a direction orthogonal to the extension direction, and the base material 2 is irradiated with ultraviolet rays through the slits S. On the other hand, the second exposure process is the same as the first exposure process except that instead of the first mask 16A, a mask 16B to be used for the second exposure process is arranged and the exposure process is performed. Composed.

  Thereby, in this manufacturing process, the alignment film 3 is produced by performing the exposure process with the excessive light quantity which concerns on the exposure process of the whole surface by two exposure processes using a mask. However, when the alignment film 3 is produced by repeating the exposure process using such a mask, the second exposure process is completely positioned with respect to the first exposure process due to the positioning accuracy of the mask, the thermal expansion of the mask, and the like. Cannot be executed together. As a result, unexposed areas may occur in the two exposure processes.

  That is, as shown in FIG. 5, the mask 16A used for the first exposure process and the mask 16B used for the second exposure process do not overlap the slits S and the light shielding regions between the slits S do not overlap. In this way, the exposure is performed. In this case, in the mask 16A used for the first exposure process, the width WBA of the light shielding portion between the slits S is equal to the width WB of the slit S in the mask 16B used for the second exposure process, and the first and second times. The widths WA and WB of the slits S related to the exposure are equal. In this case, when the two masks 16A and 16B are positioned without misalignment and thermal expansion or the like is not generated in the mask, the alignment film 3 is a region exposed by one exposure process and a second exposure process. In this case, the exposed areas are alternately and alternately produced.

  However, due to the fact that the mask cannot be completely aligned by two exposure processes, the photo-alignment material film has (1) an area that is exposed only by the first exposure process, and (2) the second exposure process. An area that is exposed only by the exposure process, (3) an area that is exposed in both the first and second exposure processes, and (4) an area that is not exposed in both the first and second exposure processes. .

  Of these four regions, the region that is exposed only by the first exposure processing and the region that is exposed only by the second exposure processing are each oriented in the corresponding direction of the photo-alignment material film. In addition, the region subjected to the exposure process in both the first exposure process and the second exposure process corresponds to the first exposure process according to the constituent material of the photo-alignment material film, the amount of light irradiated in the first exposure process, and the second exposure process. This is set to either the orientation direction or the orientation direction related to the second exposure process. Therefore, in the phase difference layer 4 related to these regions, the phase difference related to the right eye region A or the left eye region B is given to the light emitted from the liquid crystal display panel.

  On the other hand, in the region that is not exposed in both the first exposure process and the second exposure process, the photo-alignment film 3 cannot generate any alignment regulating force, and thus in the corresponding part of the retardation layer 4, The liquid crystal material is applied and kept in an unoriented state. As a result, in the pattern phase difference film 1, an unoriented region is formed between the right eye region A and the left eye region B. When the width of the unoriented region is increased, the appearance quality is significantly deteriorated. become.

  Therefore, in this embodiment, as shown in FIG. 6 in comparison with FIG. 5, in the masks 16A and 16B subjected to repeated exposure processing, the slit width is made wide so that the slits overlap at the end in the width direction. In FIG. 6, this overlapping portion is indicated by a symbol SW. More specifically, the width WB of the slit S of the mask 16B related to the second exposure process is made wider than the width WBA of the light shielding part between the slits S of the mask 16A related to the first exposure process. As a result, when the masks 16A and 16B used for the first and second exposure processes are overlapped, an area that is not shielded from light like a slit is generated at the boundary between the right-eye area A and the left-eye area B. Thereby, in this embodiment, the slit widths of the masks 16A and 16B are made wide so that an area subjected to the exposure process in both of the two exposure processes is generated.

  As a result, in this embodiment, even when the positioning of the masks 16A and 16B varies, even when the mask thermally expands, etc., it is possible to reduce the occurrence of unaligned regions, and thus the exposure processing using the mask can be performed. When producing a photo-alignment film by repetition, a pattern retardation film can be produced with high appearance quality.

  Furthermore, in this embodiment, the mask 16A used for the first exposure process and the mask 16B used for the second exposure process are produced with different slit widths WA and WB. Here, in an exposure apparatus used for this type of exposure processing, the light used for exposure cannot be set to completely parallel light, and the light used for exposure is supplied by divergent light having a certain extent. In addition, when exposure processing is performed by continuous processing of a long film, it is necessary to provide a gap between the mask and the photo-alignment material film. As a result, in the pattern retardation film, a wider area is exposed than the slit width.

  On the other hand, materials having various properties are provided for photo-alignment materials. For example, dimerization-type materials are materials whose orientation does not change by ultraviolet irradiation after orientation. is there. By the way, regarding this light dimerization type material, “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., for example, already marketed under the trade name “ROP-103”. After such alignment, when the photo-alignment material film is made of a material whose alignment does not change by irradiation with ultraviolet rays, the region width exposed by the first exposure process and the unexposed region width are the patterns. The continuous first and second region widths in the retardation film 1 are obtained. Accordingly, in this embodiment, in this case, the slit width WA of the mask 16A used for the first exposure process is set narrower than the area width of the area A or B used for the first exposure process, As a result, the area width exposed in the first exposure process is set to be the area width of the area A or B used in the first exposure process.

  Further, the width WBA + 2SW obtained by adding the width 2SW of the overlapping portion to the width WBA of the light shielding portion between the first slits S that remains after setting the slit width WA in this way is used for the second exposure process. Set to slit width WB.

  On the other hand, as the material of the photo-alignment material film, there is a material whose orientation direction changes each time by repeated exposure processing. Such materials are reported, for example, in “W.M. Gibbons, P.J.Shannon, S.T. Sun and B.J. Swetlin: Nature, 351, 49 (1991)”.

  In the case of this material, the area width exposed by the second exposure process and the unexposed area width are the first and second continuous area widths in the pattern retardation film 1. Accordingly, in this embodiment, in this case, the slit width WB of the mask 16B used for the second exposure process is set narrower than the area width of the area B or A used for the second exposure process, Thus, the area width exposed in the second exposure process is set to be the area width of the area B or A used in the second exposure process.

  Further, the width WBB + 2SW obtained by adding the width 2SW of the overlapping portion to the width WBB of the light shielding portion between the second slits S that remains after setting the slit width WB is used for the first exposure process. Set to slit width WA.

  In the above description, the photo-alignment material film related to the first and second exposure processes is simply divided into an exposed area and an unexposed area. However, in actual exposure processing, the amount of light for exposure gradually decreases from the end of the slit S toward the light-shielding portion, and depending on the characteristics such as the sensitivity of the material applied to the photo-alignment material film, the region to be exposed and the exposure The region that is not changed will change. In particular, in the case of using a material that is oriented at each exposure, the exposed area and the unexposed area change depending not only on the amount of light at the time of the second exposure but also on the amount of light at the time of the first exposure. As a result, the width of the portion subjected to the exposure described above is appropriately set according to the characteristics of the material applied to the photo-alignment material film as long as the slit width is made narrow.

  According to the above configuration, it is possible to perform repeated exposure by making the slit width of the mask related to the second exposure process wider than the width of the light shielding portion between the slits of the mask related to the first exposure process. In the mask to be processed, slits related to the two masks are overlapped at the end in the width direction, so that even when the photo-alignment film is manufactured by repeating the exposure process using the mask, it can be manufactured with high quality. .

  Specifically, a pattern retardation film was produced under the following conditions, and such an unoriented region could not be seen practically. Here, the photo-alignment material film was prepared by applying a 1% solution of the photo-alignment material to the substrate 2 and then drying with hot air at 100 ° C. for 60 seconds, and the film thickness was 0.1 μm. In the exposure process, the base material 2 on which the photo-alignment material film is thus manufactured is transported at a transport speed of 10 m / min, and the first exposure process is executed by the first mask 16A using polarized ultraviolet rays of 1000 mW / cm 2. did. Further, the second exposure process was executed using the first mask 16B under the same conditions as the first exposure process.

  Subsequently, a coating liquid for preparing a retardation layer was applied, and then heated at a film surface temperature of 80 ° C. for 1 minute, and the liquid crystal material of the applied composition was cured in a state of being aligned by the alignment regulating force of the alignment film.

[Second Embodiment]
FIG. 7 is a diagram for explaining an exposure process according to the second embodiment of the present invention. In this exposure step, the masks 16A and 16B used for the first and second exposure processes are formed on members common to the two masks 16A and 16B.

  Specifically, in this embodiment, a mask is manufactured by manufacturing a light-shielding film made of a metal film such as chromium on one glass substrate. In this embodiment, a slit relating to the first mask 16A is formed on the entry side of the base material 2 from the position closest to the roll 17 in this mask. In addition, a slit relating to the second mask 16B is formed on the carry-out side of the base material 2 from the closest position. Corresponding to the configuration of the masks 16A and 16B, the ultraviolet rays L1 and L2 used for exposure incident on the mask 16A side and the mask 16B side are sufficiently optically separated so as not to be mixed into the other side. The polarization direction is set to be different by 90 degrees.

  In this embodiment, the masks 16A and 16B to be used for the first and second exposure processes are formed on a member common to the two masks 16A and 16B, so that the influence of thermal expansion is affected by the first and second masks. It is possible to equalize with a mask, thereby preventing deterioration of accuracy due to heat.

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 combined with the above-described embodiments in various ways without departing from the gist of the present invention. The configuration can be changed variously.

  That is, in the above-described embodiment, the case where the mask slits are partially overlapped on the assumption that the transmitted light of the mask is substantially parallel light is described. However, the present invention is not limited to this, and the main point is twice. In this exposure process, the areas to be exposed may be set so as to partially overlap. For example, in the case where the exposure process is performed by diverging light, the slits may not overlap with the two masks. .

That is, in the first and second embodiments described above, the case where the right eye region and the left eye region are formed in a band shape has been described. However, the present invention is not limited to this, and the right eye region and the left eye region are arranged in a staggered arrangement in pixel units. The present invention can be widely applied when setting an area.

  Moreover, although the case where an optical film was produced with a roll plate was described in the above-described embodiment, the present invention is not limited to this and can be widely applied to the case where an optical film is produced with a flat plate.

  In the above-described embodiment, the case where the use of the liquid crystal display panel is assumed has been described. However, the present invention is not limited to this, and the present invention can be widely applied to the case where the use of an organic EL panel or a plasma display panel is assumed. In addition, the present invention can be widely applied to the case where the polarizing filter is provided integrally.

DESCRIPTION OF SYMBOLS 1 Pattern retardation film 2 Base material 3 Orientation film 4 Phase difference layer 16A, 16B Mask 17 Roll

Claims (3)

Manufacture of an optical film in which an alignment film and a retardation layer are sequentially provided on a substrate made of a transparent film material, and first and second regions having different retardations to be transmitted to the retardation layer are sequentially provided. In the method
A photo-alignment material film production step of producing a photo-alignment material film on the substrate;
An alignment film preparation step of exposing the photo-alignment material film to prepare the alignment film by a photo-alignment film; and
A retardation layer production step of producing the retardation layer on the alignment film,
The alignment film manufacturing step includes
A first exposure step of exposing the photo-alignment material film using a first mask having a plurality of slits corresponding to the first region;
A second exposure step of exposing the photo-alignment material film using a second mask having a plurality of slits corresponding to the second region,
The method for producing an optical film, wherein the area exposed by the light passing through the slit of the first mask and the area exposed by the light passing through the slit of the second mask are partially overlapped. The method for producing an optical film according to claim 1, wherein the first mask and the second mask have different slit widths. The substrate is provided by a roll;
The alignment film manufacturing step includes
Producing the alignment film sequentially while transporting the substrate,
The first and second masks are
The method for producing an optical film according to claim 1, wherein the optical film is produced on a member common to the first and second masks.

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