JP2014038178A - Photo-alignment exposure apparatus - Google Patents

Abstract

When applying an alignment exposure method to a multi-domain method, alignment disturbance near a boundary in a divided region of a unit image region is eliminated.
A photo-alignment exposure apparatus that divides each unit image area of a liquid crystal display element into a plurality of divided areas and photo-aligns alignment material films in the divided areas in different directions, and emits exposure light. A light source unit 11; a mask pattern M corresponding to one divided region of the plurality of divided regions; and an optical system that irradiates the exposed surface Bs with light emitted from the light source unit 11 through the mask pattern M. The system uses the light exit surface Ms of the mask pattern M as the first image plane F1 and the exposed surface Bs as the second image plane F2, and reflects between the first image plane F1 and the second image plane F2. An imaging optical system 13 is provided.
[Selection] Figure 3

Description

  The present invention relates to a photo-alignment exposure apparatus for forming an alignment film of a liquid crystal display element.

  As a method for forming an alignment film of a liquid crystal display element, a photo-alignment exposure method in which ultraviolet rays are obliquely irradiated to a photosensitive polymer film serving as an alignment film is known in order to determine the size of the pretilt angle of liquid crystal and the alignment direction. It has been.

  On the other hand, by dividing one unit image region (pixel or sub-pixel, or a collection region thereof) of the liquid crystal display element into two or more and changing the alignment direction of the liquid crystal for each divided region, a liquid crystal panel The viewing angle is improved, and this method is called a pixel division method or a multi-domain method.

  When the above-described photo-alignment exposure method is applied to the multi-domain method, a plurality of ultraviolet exposure light irradiated at different angles with respect to the surface to be exposed on the alignment material film is formed, and through one opening of the mask One region obtained by dividing the unit image region is irradiated with ultraviolet rays from one direction, and the other region obtained by dividing the unit image region through other openings of the mask is irradiated with ultraviolet rays from the other direction. Accordingly, it is possible to perform a photo-alignment process in which the pretilt angle and the alignment direction are different for each of the plurality of regions obtained by dividing the unit image region.

  At this time, in the prior art described in Patent Document 1 below, each of a plurality of unit image areas arranged linearly is divided into two areas by dividing lines along the arrangement direction, and the exposed surface is divided into unit images. The plurality of unit image areas are scanned and exposed by moving along the arrangement direction of the areas, so that the plurality of unit image areas are continuously subjected to photo-alignment processing. In this prior art, two mask patterns having an opening pattern corresponding to one divided area and an opening pattern corresponding to another area adjacent thereto are used. And, by irradiating each opening pattern with exposure light along the scanning direction and ultraviolet exposure light at different angles with respect to the exposed surface, the mask pattern is projected and exposed on the exposed surface (proximity exposure). The two divided areas are subjected to photo-alignment processing in different directions along the scanning direction.

JP 2012-63652 A

  As shown in FIG. 1A, an exposure apparatus used in the prior art includes a light source 1 that emits ultraviolet rays, and a condenser lens that irradiates a mask pattern M by making ultraviolet exposure light emitted from the light sources 1 into parallel light. 2, a fly-eye lens (lens array in which a plurality of unit lenses are arranged in a matrix) 3 that is disposed between the light source 1 and the condenser lens 2 and uniformizes the intensity distribution of the light applied to the mask pattern M The fly-eye lenses 3 are arranged in a direction crossing the scanning direction S of the exposed surface Bs.

  In such an exposure apparatus, as shown in FIG. 1B, a light ray L1 that obliquely passes through the opening Ma of the mask pattern M is generated by the condensing action of the fly-eye lens. After passing through the opening Ma, it is spread by the collimation half angle θ to irradiate the exposed surface Bs. As a result, the exposed surface Bs is irradiated not only with the region Me immediately below the opening pattern of the mask pattern M but also with the exposure light that protrudes from the region Me.

  In order to perform photo-alignment exposure by the multi-domain method using such an exposure apparatus, a photo-alignment exposure apparatus as shown in FIG. 2A is used. According to this, the first mask pattern M1 having an opening pattern for exposing one divided area of the unit image area and the second mask pattern M2 having an opening pattern for exposing the other divided area are provided. A first exposure apparatus Ex1 and a second exposure apparatus Ex2 are provided that are arranged apart from each other on the exposed surface Bs and expose the exposed surface Bs of the exposed substrate B through the mask patterns M1 and M2, respectively. . The first exposure apparatus Ex1 irradiates the exposure light along the scanning direction S and the ultraviolet exposure light with the irradiation angle θe (for example, 40 °) to the exposure surface Bs of the exposure substrate B. The exposure apparatus Ex2 irradiates the exposure light along the scanning direction S with ultraviolet exposure light having an irradiation angle of −θe (for example, −40 °) to the exposed surface Bs of the exposed substrate B.

  According to this, the exposure of the divided areas Da1 and Da2 in one unit image area Pa is sequentially performed with the exposure intensity shown in FIG. 2B, and the overexposure exposure by the collimation half angle shown in FIG. Thus, double exposure is performed in the range a near the boundary between the divided areas Da1 and Da2.

  At this time, due to the reversibility of the photoisomerization reaction in the alignment material, an appropriate photo-alignment can be obtained on the divided region Da2 side in the range a, but in the region a1 on the divided region Da1 side in the range a, the photo-alignment in a desired direction is obtained. Problems that cannot be obtained arise. The alignment disorder in the region a1 is caused by double exposure with insufficient intensity due to the above-described half-angle collimation exposure, and its width is about 10 to 15 μm, but it is narrower due to high definition of the liquid crystal display panel. Under a situation where the width of the unit image area Pa is required, the width cannot be ignored in order to secure a sufficient effective image area.

  This invention makes it an example of a subject to cope with such a problem. That is, when the photo-alignment exposure method is applied to the multi-domain method, the effective image area sufficient for eliminating the alignment disturbance near the boundary in the divided area obtained by dividing the unit image area and narrowing the unit image area It is an object of the present invention to ensure the above.

  In order to achieve such an object, the photo-alignment exposure apparatus according to the present invention has at least the following features.

  A light alignment exposure apparatus that divides each unit image region of a liquid crystal display element into a plurality of divided regions, and photo-aligns alignment material films in the divided regions in different directions, and a light source unit that emits exposure light; A mask pattern corresponding to one divided region of a plurality of divided regions; and an optical system that irradiates the surface to be exposed with light emitted from the light source unit via the mask pattern, the optical system including the mask pattern And a reflection imaging optical system between the first imaging surface and the second imaging surface, wherein the light emitting surface is a first imaging surface and the exposed surface is a second imaging surface. And

  According to such a feature, an image of the light emission surface of the mask pattern is formed on the exposed surface, so that the mask pattern is projected onto the exposed surface at the same magnification. Accordingly, the corresponding divided area can be exposed by the light intensity on the light exit surface of the mask pattern. Therefore, it is possible to prevent the adjacent divided areas from being exposed when one divided area is exposed, and it is possible to eliminate the double exposure near the boundary of the divided areas.

  As described above, according to the photo-alignment exposure apparatus of the present invention, when the photo-alignment exposure method is applied to the multi-domain method, the alignment disturbance near the boundary in the divided region obtained by dividing the unit image region can be eliminated, and the unit image It is possible to secure a sufficient effective image area for narrowing the area.

It is explanatory drawing which showed the exposure apparatus used for a prior art. It is explanatory drawing which showed the conventional photo-alignment exposure apparatus. It is explanatory drawing which showed the photo-alignment exposure apparatus which concerns on one Embodiment of this invention. It is explanatory drawing explaining the photo-alignment exposure method using the photo-alignment exposure apparatus which concerns on embodiment of this invention. It is explanatory drawing which showed the example of the mask pattern used for the photo-alignment exposure apparatus which concerns on embodiment of this invention. It is explanatory drawing which showed the photo-alignment state on the to-be-exposed surface by the photo-alignment exposure method using the photo-alignment exposure apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is an explanatory view showing a photo-alignment exposure apparatus according to an embodiment of the present invention.

  The photo-alignment exposure apparatus 10 receives a light source unit 11 that emits exposure light, a mask pattern M corresponding to one divided region of a plurality of divided regions, and light emitted from the light source unit 11 via the mask pattern M. An optical system for irradiating the exposure surface is provided. In the optical system from the light source unit 11 to the mask pattern M, the condenser lens 2 and the fly-eye lens 3 shown in FIG.

  The optical system from the mask pattern M to the exposed surface Bs has the first imaging surface F1 with the light emitting surface Ms of the mask pattern M as the first imaging surface F1 and the exposed surface Bs as the second imaging surface F2. A reflective imaging optical system 13 is provided between the second imaging surface F2. The reflective imaging optical system 13 includes a concentric spherical concave mirror 13A and a convex mirror 13B. A first reflective surface R1 and a third reflective surface R3 from the first imaging surface F1 are formed on the concave mirror 13A, and the first imaging surface. A second reflecting surface R2 from F1 is formed on the convex mirror 13B.

  In the illustrated example, the light emission surface Ms of the mask pattern M, the exposed surface Bs, and the reflection surface of the mirror 12 are arranged in parallel to each other. The irradiation angle (angle with respect to the vertical axis) θt of the light emitted from the light source unit 11 coincides with the irradiation angle (angle with respect to the vertical axis) θt of the light irradiated on the exposed surface Bs. The reflective imaging optical system 13 is a double-sided telecentric optical system that is formed entirely of a reflecting surface and is capable of imaging at the same magnification without any chromatic aberration in principle.

  According to this, even if the light emitted from the mask pattern M includes light having a spread angle with respect to the irradiation angle θt (spread light), the light irradiated onto the exposed surface Bs at the irradiation angle θt. Can be condensed at the irradiation position. As a result, even if the light emitted from the mask pattern M includes spreading light due to a collimation half angle or the like, the spreading light can be condensed in the divided region corresponding to the mask pattern M, and the protruding light is projected. Exposure can be suppressed.

  As described above, according to the photo-alignment exposure apparatus 10, the image of the light emission surface Ms of the mask pattern M is formed on the exposed surface Bs, so that the mask pattern M is projected onto the exposed surface Bs at the same magnification, and the mask pattern M The corresponding divided area can be exposed with the light intensity at the light exit surface Ms. Therefore, it is possible to prevent the adjacent divided areas from being exposed when one divided area is exposed, and it is possible to eliminate the double exposure near the boundary of the divided areas.

  A photo-alignment exposure method using the photo-alignment exposure apparatus will be described with reference to FIGS. FIG. 4A shows an arrangement configuration of the photo-alignment exposure apparatus, and FIG. 4B shows an arrangement example of unit image areas on the substrate to be exposed. In order to perform photo-alignment exposure, exposure units 100A and 100B constituted by the above-described photo-alignment exposure apparatus 10 and substrate scanning means (not shown) are used, and an exposed substrate B having an exposed surface Bs is formed by the substrate scanning means. It moves along the scanning direction S. About the structure of exposure unit 100A, 100B, the same code | symbol as FIG. 3 is attached | subjected and duplication description is abbreviate | omitted. The scanning direction S here is an arrangement direction of the plurality of unit image areas Pa and a direction along the dividing line DL that divides the unit image area. The exposure unit 100A includes a first mask pattern M1, and the exposure unit 100B includes a second mask pattern M2. The exposure units 100A and 100B are arranged along the scanning direction S and irradiate the exposure light along the scanning direction S and the ultraviolet exposure light at different angles (θ1, −θ1) with respect to the exposed surface Bs. is there.

  With respect to the exposed surface Bs moving along the scanning direction S, first, in the first exposure, the exposure unit 100A exposes the first divided area Da1 alone via the first mask pattern M1, and then the first exposure area Bs. In the exposure of 2, the exposure unit 100B exposes the second divided region Da2 alone via the second mask pattern M2.

  FIG. 5 is an explanatory view showing an example of a mask pattern used in the photo-alignment exposure apparatus according to the embodiment of the present invention. FIG. 5 (a) shows an example of the first mask pattern, and FIG. Shows an example of the second mask pattern.

  As shown in FIG. 4B, when the unit image areas Pa are arranged in a dot matrix, the first mask pattern M1 corresponding to the unit image area Pa has a plurality of pieces as shown in FIG. A slit-shaped opening pattern is formed. In this example, each opening Ma1 is arranged corresponding to the first divided area Da1 on the exposed surface Bs, and has an opening width W1 substantially equal to the first divided area Da1. In the slit-shaped opening pattern, the plurality of openings Ma1 are parallel to each other and are arranged in parallel in a direction intersecting the scanning direction S.

  On the other hand, as shown in FIG. 5B, the second mask pattern M2 is formed with a plurality of slit-like opening patterns at positions that are slid by the opening width W1 with respect to the first mask pattern M1. . Each opening Ma2 is arranged corresponding to the second divided region Da2 on the exposed surface Bs, and the opening Ma2 has an opening width W2 that is substantially equal to the second divided region Da2. In the slit-shaped opening pattern, the plurality of openings Ma2 are parallel to each other and are arranged in parallel in a direction intersecting the scanning direction S.

  FIG. 6 is an explanatory view showing the photo-alignment state on the exposed surface Bs by the photo-alignment exposure method using the photo-alignment exposure apparatus according to the embodiment of the present invention. FIG. 6A shows the photo-alignment state by the first exposure, and FIG. 6B shows the photo-alignment state by the second exposure. In the example shown in the drawing, a sub pixel obtained by dividing one pixel P1 for each color of RGB is set as a unit image area Pa, and each sub pixel is divided into a first divided area Da1 and a second divided area Da2.

  In the first exposure using the first mask pattern M1, as shown in FIG. 6 (a), each first divided region Da1 is independently subjected to photo-alignment in the same direction as the scanning direction S. Next, in the second exposure using the second mask pattern M2, as shown in FIG. 6 (b), each second divided region Da2 is independently subjected to photo-alignment in the direction opposite to the scanning direction S. . At this time, in the first exposure and the second exposure, the entire areas of the first divided area Da1 and the second divided area Da2 are exposed. However, the first mask pattern M1 and the second mask pattern M2 have the same magnification on the exposed surface. Since the projection is performed, no overexposure that reaches the adjacent divided areas occurs. Thereby, double exposure near the boundary between the first divided area Da1 and the second divided area Da2 is eliminated, and it is possible to avoid alignment disturbance near the boundary.

  According to the photo-alignment exposure method having such a feature, the alignment disorder is suppressed in the entire area of the unit image area Pa, and the area where the unit image area Pa is photo-aligned in one direction and the area photo-aligned in the other direction. Therefore, when the photo-alignment exposure method is applied to the multi-domain method, it is possible to secure a sufficient effective image area for narrowing the unit image area Pa.

  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 particular, the embodiment shown in FIG. 4A shows a mode in which the substrate to be exposed B is moved (scanned). However, the present invention is not limited to this, and the first exposure is performed on the fixed substrate B to be exposed. And the second exposure may be performed. In the example shown in FIG. 4, the unit image area Pa is divided into two. However, the photo-alignment exposure apparatus and the photo-alignment exposure method using the same according to the embodiment of the present invention are not limited thereto. The present invention can be applied to those in which the unit image area Pa is divided into three or more.

  In the example shown in FIG. 4, the exposure unit using the photo-alignment exposure apparatus 10 according to the embodiment of the present invention is applied to both the first exposure and the second exposure. When the material film exhibits a reversible photoisomerization reaction, the photo-alignment exposure apparatus 10 according to the embodiment of the present invention is applied only to the second exposure, and the first exposure is the conventional exposure shown in FIG. A proximity exposure method can be adopted.

1: light source, 2: condenser lens, 3: fly-eye lens,
10: photo-alignment exposure apparatus, 11: light source unit, 12: mirror,
13: reflection imaging optical system, 13A: concave mirror, 13B: convex mirror,
100A, 100B: exposure unit,
R1: first reflecting surface, R2: second reflecting surface, R3: third reflecting surface,
F1: first imaging plane, F2: second imaging plane,
M: mask pattern, Ma, Ma1, Ma2: aperture, Ms: light exit surface,
M1: first mask pattern, M2: second mask pattern,
B: substrate to be exposed, Bs: surface to be exposed, S: scanning direction,
Pa: unit image area, Da1: first divided area, Da2: second divided area

Claims (3)

A photo-alignment exposure apparatus that divides each unit image area of a liquid crystal display element into a plurality of divided areas, and photo-aligns alignment material films in the divided areas in different directions,
A light source unit that emits exposure light;
A mask pattern corresponding to one divided region of the plurality of divided regions;
An optical system for irradiating the surface to be exposed with the light emitted from the light source unit through the mask pattern;
The optical system includes a light exit surface of the mask pattern as a first image forming surface and the exposed surface as a second image forming surface, and a reflective connection between the first image forming surface and the second image forming surface. An optical alignment exposure apparatus comprising an image optical system.   The reflective imaging optical system includes a concentric spherical concave mirror and a convex mirror, and a first reflecting surface and a third reflecting surface from the first imaging surface are formed on the concave mirror, and a first reflecting surface from the first imaging surface is formed. 2. The photo-alignment exposure apparatus according to claim 1, wherein two reflecting surfaces are formed on the convex mirror.   The photo-alignment exposure apparatus according to claim 1, wherein an emission surface of the mask pattern and the exposed surface are arranged in parallel.

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