JP6206944B2 - Polarized light irradiation device for photo-alignment - Google Patents

Description

  The present invention relates to a polarized light irradiation apparatus for photo-alignment used for photo-alignment processing.

  In recent years, photo-alignment treatment has been used to form films and layers having the function of aligning liquid crystal molecules (hereinafter collectively referred to as alignment films), such as alignment films for liquid crystal elements and alignment layers for optical films using ultraviolet curable liquid crystals. Is adopted. In order to perform the photo-alignment treatment, light having a selected wavelength (for example, ultraviolet light) is irradiated on the photosensitive resin film serving as the alignment film in a polarization state (for example, a linearly polarized state) specified by the polarization axis.

  In order to continuously form an alignment film having a predetermined width, a polarized light irradiation apparatus for photo-alignment processing arranges a rod-shaped light source (long arc lamp) along the width direction of the alignment film, and this light source and polarized light There is known a technique in which polarized light having a selected wavelength is irradiated along a width direction of an alignment film and scanned in a direction crossing the width direction of the alignment film (see Patent Document 1 below).

JP 2006-133498 A

  The long arc lamp is also suitable as a light source for a polarized light irradiation apparatus for photo-alignment by efficiently emitting short-wavelength ultraviolet light (for example, 254 nm wavelength light) necessary for photo-alignment processing. When a long arc lamp is used as a light source, light is irradiated radially in a direction intersecting the longitudinal direction, and therefore a wire grid polarizer with little incident angle dependency is used for the polarizer.

  A wire grid polarizer forms a grid pattern of a conductor grid on a transparent substrate such as quartz glass, and makes the pitch of the conductor grid equal to or less than the wavelength of the incident light, thereby polarizing components parallel to the longitudinal direction of the grid. Is reflected, and a polarized light component orthogonal thereto is allowed to pass through.

  A polarized light irradiation device for photo-alignment using such a wire grid polarizer causes short-wavelength ultraviolet light incident on a conductor grid formed of a metal such as aluminum to undergo oxidation or thermal change, and the wire grid There was a problem that the performance of the polarizer deteriorated. In general, the performance of a polarizer can be expressed by the extinction ratio ER (= Ip / Is, Ip is P-polarized light intensity, Is is S-polarized light intensity) of transmitted polarized light, but for photo-alignment using a wire grid polarizer. When the polarized light irradiation device is used for a long time, there arises a problem that a desired extinction ratio cannot be obtained due to the above-described oxidation of the conductor grid.

  In addition, in order to obtain a desired irradiation light wavelength, a polarized light irradiation device for photo-alignment may have a filter that transmits a specific wavelength between a light source and a polarizer. As a result, the wavelength selectivity may be lowered, and this also causes a problem that performance deteriorates due to long-term use.

  Further, in the conventional polarized light irradiation device for photo-alignment, since the conductor grid of the wire grid polarizer is directly facing the alignment film, the exposed conductor grid is only exposed to a state where it is easily oxidized. In addition, there is a concern that performance deterioration may occur even when a vaporized component from the alignment film adheres to the conductor grid.

  This invention makes it an example of a subject to cope with such a problem. That is, the object of the present invention is to suppress the performance deterioration of the wire grid polarizer and the specific wavelength selection filter even for long-term use and to obtain a highly durable polarized light irradiation device for photo-alignment. .

  In order to achieve such an object, the polarized light irradiation apparatus for photo-alignment according to the present invention has at least the following configuration.

A light irradiation unit including a light source, a specific wavelength selection filter, and a wire grid polarizer is extended in the width direction of the substrate on which the alignment film is formed, and the substrate or the light irradiation unit intersects the width direction of the substrate. A polarization irradiation device for photo-alignment that irradiates polarized light of a specific wavelength on the substrate while scanning along a scanning direction, wherein the light irradiation unit is an antioxidant that covers a conductor grid of the wire grid polarizer A film, and air cooling means for cooling the wire grid polarizer , wherein the light irradiation unit includes a plurality of light irradiation units including a light source, a specific wavelength selection filter, and a wire grid polarizer arranged in parallel in the width direction of the substrate. And the light source is arranged with the longitudinal direction of the light source along the scanning direction .

  According to the polarized light irradiation device for photo-alignment having such characteristics, it is possible to suppress the performance deterioration of the wire grid polarizer and the specific wavelength selection filter with long-term use, and to obtain a highly durable polarized light irradiation device for photo-alignment. Can do.

It is explanatory drawing which showed the whole structure of the polarized light irradiation apparatus for photo-alignment which concerns on one Embodiment of this invention. It is explanatory drawing which showed the whole structure of the polarized light irradiation apparatus for photo-alignment which concerns on one Embodiment of this invention. It is explanatory drawing which showed the whole structure of the polarized light irradiation apparatus for photo-alignment which concerns on other embodiment of this invention. It is explanatory drawing which showed the whole structure of the polarized light irradiation apparatus for photo-alignment which concerns on other embodiment of this invention. It is explanatory drawing which showed the whole structure of the polarized light irradiation apparatus for photo-alignment which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the scanning direction is the Y direction, the vertical upward direction is the Z direction, the scanning direction and the vertical upward direction are orthogonal, and the width direction of the substrate is the X direction. FIG. 1 and FIG. 2 are explanatory views showing the overall configuration of a photo-alignment polarized light irradiation apparatus according to an embodiment of the present invention. FIG. 1A is an explanatory diagram viewed from above the polarized light irradiation device for photo-alignment, and FIG. 1B is an explanatory diagram viewed from the front. 2A is an explanatory view of the polarized light irradiation device for photo-alignment as viewed from the side, and FIG. 2B is an enlarged view of a portion A in FIG.

  The polarized light irradiation apparatus 1 for photo-alignment includes a light irradiation unit 2, a substrate stage 3, and a scanning unit 4. In the illustrated example, the substrate stage 3 is moved along the scanning direction S (Y direction in the drawing). However, the present invention is not limited to this, and the light irradiation unit 2 is moved in the direction opposite to the Y direction in the drawing. There may be. A substrate W on which an alignment film is formed is placed on the substrate stage 3. The light irradiation unit 2 includes a light source 20, a specific wavelength selection filter 21, and a wire grid polarizer 22, and extends in the width direction (X direction in the drawing) of the substrate W. The polarized light irradiation device 1 for photo-alignment irradiates polarized light of a specific wavelength onto the substrate W while scanning the substrate W or the light irradiation unit 2 along a direction intersecting the width direction of the substrate W.

  The light irradiation unit 2 shown in FIGS. 1 and 2 includes a plurality of light irradiation units 2U each including a light source 20, a specific wavelength selection filter 21, and a wire grid polarizer 22 in the width direction (X direction in the drawing) of the substrate W. Arranged and configured. The light source 20 is a long arc lamp whose longitudinal direction is arranged along the scanning direction S. Long arc lamps having a length shorter than the width of the substrate W are arranged in parallel along the width direction of the substrate W.

  The light irradiation unit 2 includes an antioxidant film 22 </ b> C that covers the conductor grid 22 </ b> B of the wire grid polarizer 22. That is, as shown in FIG. 2B, the wire grid polarizer 22 includes a transparent base material 22A made of quartz glass or the like, and a conductor grid 22B made of aluminum or the like formed in a lattice shape, and transmits light. A conductor grid 22B arranged at an interval narrower than the wavelength of is coated with an antioxidant film 22C.

The antioxidant film 22C can be formed by atomic layer deposition (ALD) such as SiO ₂ and HfO ₂ . In the wire grid polarizer 22, for example, the thickness of the base material 22A is about 1.0 mm, the height of the conductor grid 22B is about 150 to 200 nm , and the arrangement pitch of the conductor grid 22B is about 120 nm. On the other hand, the film thickness of the antioxidant film 22C is about 0.1 to 10 nm.

  In addition, the light irradiation unit 2 includes air cooling means 23 for cooling the wire grid polarizer 22. This air cooling means 23 may cool the wire grid polarizer 22 independently, or may cool the wire grid polarizer 22 and the specific wavelength selection filter 21 simultaneously. In the example shown in FIG. 2A, the air cooling means 23 blows the cooling air C between the specific wavelength selection filter 21 and the wire grid polarizer 22, so that the wire grid polarizer 22 and the specific wavelength selection filter are blown. 21 is being cooled at the same time.

  In the illustrated example, the cooling air C is sent between the wire grid polarizer 22 and the specific wavelength selection filter 21 along the scanning direction S in which the substrate W is scanned. By forming such a flow of the cooling air C, the wire grid polarizer 22 and the specific wavelength selection filter 21 are uniformly cooled in the width direction of the substrate W, and the temperature in the direction orthogonal to the scanning direction S. The conditions are the same, and a high-quality alignment film can be formed.

  FIG. 3 is an explanatory view showing the overall configuration of a polarized light irradiation apparatus for photo-alignment according to another embodiment of the present invention. FIG. 3A is an explanatory view in which the polarized light irradiation device for photo-alignment is viewed from the side, and FIG. 3B is an enlarged view of part A in FIG.

  In this example, in addition to the configuration of the above-described polarized light irradiation apparatus 1 for photo-alignment, the light irradiation unit 2 includes gas filling means 24 that covers the conductor grid 22B of the wire grid polarizer 22 with an inert gas G atmosphere. ing. As the inert gas G, nitrogen or argon can be used.

  In the illustrated example, the gas filling means 24 is configured by a sealing frame 24A that seals the inert gas G around the conductor grid 22B. The sealing frame 24A hermetically surrounds the surface on which the conductor grid 22B of the wire grid polarizer 22 is formed by the transparent facing plate 24A1 and the side portion 24A2, and an inert gas such as nitrogen or argon is contained therein. G is filled. By adopting such a configuration, it is possible to prevent vaporized components from the alignment film generated at the time of exposure from adhering to the conductor grid, to suppress deterioration of the characteristics of the wire grid polarizer 22, and to facilitate cleaning because maintenance is facilitated. Can improve sex.

  The gas filling means 24 is not limited to such a configuration of the sealing frame 24A, and may be any configuration as long as the periphery of the conductor grid 22B can be always covered with the inert gas G. . For example, the inert gas G may be circulated around the conductor grid 22B, or the inert gas G may be retained around the conductor grid 22B. Moreover, the filling of the inert gas G can also serve as cooling of the wire grid polarizer 22.

  FIG. 4 is an explanatory view showing the overall configuration of a photo-alignment polarized light irradiation apparatus according to another embodiment of the present invention, and shows another configuration example of the air cooling means. The air cooling means shown in FIG. 4 sends the cooling air C to the filter layer 21F on the wire grid polarizer 22 that forms the specific wavelength selection filter 21 so that the wire grid polarizer 22 and the specific wavelength selection filter 21 simultaneously. It is cooling. Here, the specific wavelength selection filter 21 is provided by forming the filter layer 21F on the surface of the base material 22A of the wire grid polarizer 22 (surface opposite to the surface on which the conductor grid 22B is formed) The cooling air C passes through it. The filter layer 21F can be formed of, for example, a dielectric multilayer film.

  FIG. 5 is an explanatory view showing the overall configuration of a polarized light irradiation apparatus for photo-alignment according to another embodiment of the present invention, and shows another configuration example of the light irradiation unit. The light irradiation units 2U of the light irradiation unit 2 shown in FIG. 5 are arranged in multiple stages along the scanning direction S, and the positions of the light irradiation units 2U in one stage and the light irradiation units 2U in the adjacent stage. The position is shifted. Also in this configuration, the air cooling means 23 described above is provided, and the air cooling means 23 blows the cooling air C along the scanning direction S. By blowing the cooling air C in this way, the wire grid polarizer 22 and the specific wavelength selection filter 21 can be cooled uniformly along the width direction of the substrate W. As a result, the temperature conditions in the direction orthogonal to the scanning direction S are the same, and a high-quality alignment film can be formed.

  As described above, the polarized light irradiation device 1 for photo-alignment according to the embodiment of the present invention includes the antioxidant film 22C that covers the conductor grid 22B of the wire grid polarizer 22, and cools the wire grid polarizer 22. In addition to providing the air cooling means 23, in addition, a gas filling means 24 for simultaneously cooling the wire grid polarizer 22 and the specific wavelength selection filter 21 and covering the conductor grid 22B of the wire grid polarizer 22 with an inert gas atmosphere. By providing, the performance degradation of the wire grid polarizer 22 and the specific wavelength selection filter 21 that occurs during long-term use can be suppressed. Thereby, the durability of the polarized light irradiation device 1 for photo-alignment can be effectively improved.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. In addition, the above-described embodiments can be combined by utilizing each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1: polarized light irradiation device for photo-alignment, 2: light irradiation unit, 3: substrate stage, 4: scanning means,
20: Light source, 21: Specific wavelength selection filter, 22: Wire grid polarizer,
22A: Base material, 22B: Conductor grid, 22C: Antioxidation film,
23: Air cooling means, 24: Gas filling means, 24A: Sealing frame,
2U: Light irradiation unit,
W: substrate, S: scanning direction, C: cooling air, G: inert gas

Claims (7)

A light irradiation unit including a light source, a specific wavelength selection filter, and a wire grid polarizer is extended in the width direction of the substrate on which the alignment film is formed, and the substrate or the light irradiation unit intersects the width direction of the substrate. A polarized light irradiation device for photo-alignment that irradiates polarized light of a specific wavelength on the substrate while scanning along a scanning direction,
The light irradiator is
An antioxidant film covering the conductor grid of the wire grid polarizer;
Air cooling means for cooling the wire grid polarizer ,
The light irradiator is
A plurality of light irradiation units including a light source, a specific wavelength selection filter, and a wire grid polarizer are arranged in parallel in the width direction of the substrate,
The polarized light irradiation apparatus for photo-alignment , wherein the light source has a longitudinal direction of the light source arranged along the scanning direction .   The polarized light irradiation apparatus for photo-alignment according to claim 1, wherein the air cooling unit blows cooling air between the specific wavelength selection filter and the wire grid polarizer.   2. The polarized light irradiation apparatus for photo-alignment according to claim 1, wherein the air cooling unit blows cooling air to a filter layer on the wire grid polarizer forming the specific wavelength selection filter.   The polarized light irradiation apparatus for photo-alignment according to claim 1, wherein the air-cooling unit blows cooling air along the scanning direction. The light irradiator is
The polarized light irradiation apparatus for photo-alignment according to any one of claims 1 to 4, further comprising gas filling means for covering the conductor grid of the wire grid polarizer with an inert gas atmosphere.   6. The polarized light irradiation apparatus for photo-alignment according to claim 5, wherein the gas filling means is a sealing frame that seals an inert gas around the conductor grid. The light irradiation units are arranged in multiple stages along the scanning direction, and the positions of the light irradiation units in one stage and the positions of the light irradiation units in stages adjacent thereto are shifted. The polarized light irradiation device for photo-alignment according to any one of claims 1 to 6 .

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