Patent Application
20190294009
The present invention relates to a polarized light radiation device and a polarized light radiation method.
Patent Document 1 discloses a liquid crystal display apparatus including: a vertical alignment liquid crystal layer; a first substrate and a second substrate each of which has a light blocking member; a first electrode provided on a liquid crystal layer side of the first substrate and a second electrode provided on a liquid crystal layer side of the second substrate; and at least one alignment film in contact with the liquid crystal layer.
Patent Document 1: JP 2011-53721 A
However, the alignment of the liquid crystal molecules is disturbed at the boundary portion of the liquid crystal domain. The regions where the alignment of the liquid crystal molecules becomes discontinuous are visually recognized as dark lines because they do not transmit light. In the pixel region 100, dark lines (domain lines DL1, DL2, DL3, and DL4) along the edge portion are formed respectively in the liquid crystal domains A, B, C, and D.
The pixel region of the lower substrate is divided into two, and the pre-tilt directions PA1 and PA2 that are antiparallel to the vertical alignment film are given. In addition, the pixel region of the upper substrate is divided into two, and a pre-tilt directions PB1 and PB2 that are antiparallel to the vertical alignment film are given. By affixing the lower substrate and the upper substrate together, an alignment split structure of the pixel area 100 is obtained.
Patent Document 1 describes that a photoalignment process is performed by obliquely irradiating ultraviolet light from the direction indicated by the arrow in
However, Patent Document 1 discloses no specific method for reducing the pre-tilt angle in a case where the photoalignment process is used to define the pre-tilt direction of the liquid crystal molecules in the alignment film.
One or more embodiments of the present invention provide a polarized light radiation device and a polarized light radiation method capable of generating an alignment film having a small pre-tilt angle of liquid crystal molecules by a photoalignment process.
In one or more embodiments of the present invention, a polarized light radiation device includes, for example: a light source configured to emit polarized light; a mask where a light transmission region allowing polarized light having been emitted from the light source to pass therethrough is formed; and a stage on which an exposure target object to be irradiated with polarized light having passed through the light transmission region is placed. In the polarized light radiation device, the light source radiates polarized light onto the exposure target object from a direction inclined by approximately 50° to approximately 70° in relation to a direction that is substantially orthogonal to a top surface of the stage.
The polarized light radiation device according to one or more embodiments of the present invention radiates polarized light to the exposure target object from a direction inclined approximately 50° to approximately 70° in relation to a direction substantially orthogonal to a top surface of the stage. As a result, the alignment film can be produced by the photoalignment process so that the pre-tilt angle of the liquid crystal molecules becomes smaller. By generating a liquid crystal display apparatus using the alignment film generated in this manner, the dark lines that appear in the pixel region become narrower and a higher display quality is obtained.
The above-described polarized light radiation device may further include a drive unit configured to move the stage in a transport direction and rotate the stage by approximately 180°. In the polarized light radiation device, the light source may include a first light source and a second light source that are arranged along the transport direction. The drive unit may be configured to rotate the stage by approximately 180° between the first light source and the second light source. The mask may include: a first mask having a first light transmission region formed therein, the first light transmission region allowing exposure light having been emitted from the first light source to pass therethrough; and a second mask having a second light transmission region formed therein, the second light transmission region allowing exposure light having been emitted from the second light source to pass therethrough. The second light transmission region may be formed at a position to allow light to be radiated onto a region in the exposure target object, the region being not irradiated with any light having passed through the first light transmission region. The above-described configuration allows polarized light to be radiated to different positions of the same exposure target object from different directions.
One or more embodiments of the present invention provides a polarized light radiation method. The method includes the step of, for example, emitting light from a direction inclined by approximately 50° to approximately 70° in relation to a direction that is substantially orthogonal to a top surface of a stage on which an exposure target object is placed, the light being emitted while the stage being transported in a transport direction.
One or more embodiments of the present invention provides a polarized light radiation method. The method includes the steps of: transporting, in a transport direction, a stage on which an exposure target object is placed; with the stage having been transported to a first position, emitting light from a direction inclined by approximately 50° to approximately 70° in relation to a direction that is substantially orthogonal to a top surface of the stage and radiating the light onto a first region of the exposure target object while the stage is being transported in the transport direction; transporting the stage in the transport direction to a second position; with the stage having been transported to the second position, rotating the stage by approximately 180°; transporting the stage in the transport direction to a third position; and with the stage having been transported to the third position, emitting light from a direction inclined by approximately 50° to approximately 70° in relation to a direction that is substantially orthogonal to the top surface of the stage and radiating the light onto a second region of the exposure target object while the stage is being transported in the transport direction, the second region being different from the first region.
According to one or more embodiments of the present invention, an alignment film can be produced by the photoalignment process so that the pre-tilt angle of the liquid crystal molecules becomes smaller.
Below, detailed description of embodiments of the present invention will be given with reference to drawings.
Hereinafter, a transport direction (i.e., the scanning direction) F of the substrate W is referred to as the x direction, a direction orthogonal to the transport direction F is referred to as the y direction, and the vertical direction is referred to as the z direction.
The polarized light radiation device 1 includes mainly a transport unit 10 configured to transport the substrate W, a light radiation unit 20 configured to emit exposure light, and a mask unit 30.
The transport unit 10 mainly includes a stage 11, a drive unit 12 configured to drive the stage 11 (see
The substrate W is placed on a top surface 11a of the stage 11. In the present embodiment, three substrates W (i.e., the substrate W is a concept including substrates W1, W2, and W3) are disposed in a staggered manner.
The drive unit 12 includes a horizontal drive unit 12a configured to move the stage 11 in the horizontal direction (see
The position detection unit 13 is, for example, a sensor or a camera. When the stage 11 moves in the transport direction F, the position of the stage 11 is detected by the position detection unit 13.
The light radiation unit 20 is configured to radiate light onto the substrate W. The light radiation unit 20 mainly includes two light radiation units 21 and 22 provided along the x direction.
The light radiation unit 21 mainly includes a light source 211, mirrors 212 and 213, a fly-eye lens 214, a condenser lens 215, and a polarizing beam splitter (PBS) 216.
The light source 211 mainly includes a lamp 211a and a reflective mirror 211b provided on a back side of the lamp 211a. The lamp 211a is, for example, a mercury lamp, and is configured to emit unpolarized light (e.g., ultraviolet light). Note that a xenon lamp, an excimer lamp, an ultraviolet LED, or the like may also be used as the lamp 211a. The reflective mirror 211b is, for example, an elliptical reflective mirror, and is configured to reflect light of the lamp 211a forward.
The light emitted from the lamp 211a is reflected by the reflective mirror 211b and is redirected by the mirrors 212 and 213. Consequently, the resultant light is led to the fly-eye lens 214. The two-dot chain lines in
The fly-eye lens 214 is a lens in which a plurality of small lenses are disposed in a staggered manner, and makes the irradiation surface have a uniform illuminance distribution.
The condenser lens 215 is formed by assembling a plurality of lenses, and is a lens configured to concentrate light. Light passed through the fly-eye lens 214 is concentrated by the condenser lens 215 and is led to PBS 216.
PBS 216 is an optical element configured to split incident light into S-polarized light and P-polarized light by reflecting the S-polarized light (see dotted-line arrow in
The light radiation unit 21 is configured to radiate the polarized light onto the substrate W from a direction inclined by approximately 50° to approximately 70° in relation to a direction substantially orthogonal to the top surface 11a of the stage 11 (i.e., substantially orthogonal to the z direction). To put it differently, the light radiation unit 21 (in particular, the mirror 213, the fly-eye lens 214, the condenser lens 215, and the PBS 216) are provided so that the incident angle of the P-polarized light θ1 (the angle formed by the central axis Ax of the light and the line H extending along the z direction) ranges from approximately 50° to approximately 70°. The incident angle θ1 will be described in detail later.
The mask unit 30 is provided on an optical path of the polarized light radiated from the light radiation units 21 and 22 to the substrate W. When the polarized light is radiated from the light radiation units 21 and 22 to the substrate W, the mask unit 30 and the top surface 11a are adjacent to each other.
The mask unit 30 mainly includes a mask 32 and a mask holding unit 35. The mask 32 is a substantially plate-like member, and has a substantially rectangular shape in plan view. The mask 32 is held substantially parallel to the top surface 11a by the mask holding unit 35. In addition, the mask 32 is driven in the x direction, the y direction, the z direction, and the θ direction by the mask holding unit 35.
The control unit 101 is a program control device such as a Central Processing Unit (CPU), which is an arithmetic unit. The control unit 101 is configured to operate in accordance with a program stored in the storage unit 102. In the present embodiment, the control unit 101 is configured to function as: a light source control unit 101a configured to control the lighting up and off of the lamp 211a; a drive control unit 101b configured to control the drive unit 12 to move or rotate the stage 11; a position determination unit 101c configured to acquire measurement results from the position detection unit 13 and thus to determine the position of the stage 11 and the position of the substrate W placed on the stage 11. Note that the techniques for moving and positioning the stage 11 are already publicly known techniques, and thus descriptions thereof will be omitted. Details of the operation of the control unit 101 will be described in detail later.
The storage unit 102 is a volatile memory, a non-volatile memory, or the like. The storage unit 102 holds, among other things, programs to be executed by the control unit 101, and operates as a working memory for the control unit 101.
The input section 103 includes an input device such as a keyboard or a mouse. The output section 104 is a display or the like.
Next, the operations of the polarized light radiation device 1 configured as described above will be described with reference to
When the position determination unit 101c determines that the substrate W1 is about to enter a region to be irradiated with the P-polarized light from the light radiation unit 21 (i.e., light-irradiated region EA1), the light source control unit 101a turns on the lamp 211a of the light radiation unit 21. Then, with the lamp 211a kept in that state, the drive control unit 101b moves the stage 11 in the transport direction F. As a result, the light radiated by the light radiation unit 21 is continuously radiated onto the substrate W. Of the P-polarized light from the light radiation unit 21, the light that has passed through the light transmission region 32a is first radiated onto the substrate W1, and is then radiated onto the substrates W2 and W3.
The polarized light that has passed through the light transmission region 32a is radiated onto regions I (shaded by upward diagonal lines in
The description will now return to
When the position determining unit 101c determines that the current position of the stage 11 is between the light radiation unit 21 and the light radiation unit 22, the drive control unit 101b makes the rotary drive unit 12b rotate the stage 11 by approximately 180° (see arrows R in
After the stage 11 has been rotated, the drive control unit 101b moves the stage 11 in the transport direction F. When the position determination unit 101c determines that the substrate W2 and W3 are about to enter a region to be irradiated with the P-polarized light from the light radiation unit 22 (i.e., light-irradiated region EA2), the light source control unit 101a turns on the lamp 211a of the light radiation unit 22. Then, with the lamp 211a kept in that state, the drive control unit 101b moves the stage 11 in the transport direction F. As a result, the light radiated by the light radiation unit 22 is continuously radiated onto the substrate W. Of the P-polarized light from the light radiation unit 22, the light that has passed through the light transmission region 32a is first radiated onto the substrates W2 and W3, and is then radiated onto the substrate W1.
The polarized light that has passed through the light transmission region 32a is radiated onto regions II (shaded by downward diagonal lines in
Now, the point in which the incident angle θ1 of the P-polarized light having passed through the PBS 216 is made to range from approximately 50° to approximately 70° will be described in detail.
The dark lines generated to extend along the edge portions in the pixel region 100 (see
An excessively large incident angle θ1, however, results in a large reflectivity of the P-polarized light. Even in a case where the substrate W is irradiated with P-polarized light, a large reflectivity makes the absorption of light by the substrate W more difficult.
Hence, it is desirable that the incident angle θ1 be as large as possible as long as the reflectivity can be kept low enough.
With a refractive index of 1.7, an incident angle (Brewster's angle) of approximately 59.5° results in an approximately zero reflectivity for the P-polarized light at the interface between the air and the substrate W. Hence, to satisfy the conditions that the incident angle θ1 needs to be as large as possible but that the reflectivity is kept low enough, the incident angle θ1 ranges from approximately 50° to approximately 70° (see the hatched portion in
According to the present embodiment, setting the incident angle θ1 to an angle from approximately 50° to approximately 70° allows an alignment film to be produced through a photoalignment process so that the liquid crystal molecules have a small pre-tilt angle.
In addition, according to the present embodiment, polarized light radiation twice is performed during a single processing and the stage 11 is rotated by approximately 180° between the two events of the polarized light radiation. Hence, a single substrate can be irradiated with the polarized light at different positions thereof from different directions.
Note that in the present embodiment, the incident angle θ1 ranges from approximately 50° to approximately 70°, but the incident angle θ1 may be within a range from approximately 53° to approximately 65° though such an incident angle θ1 results in reflectivity within a lower range (the reflectivity being within a range from 0.01 or lower for a refractive index of 1.7).
In addition, in the present embodiment, a small pre-tilt angle of the liquid crystal molecules is achieved by setting the incident angle θ1 to an angle from approximately 50° to approximately 70°. A small pre-tilt angle of the liquid crystal molecules, however, can also be achieved by increasing the integral of the light with which the substrate W is irradiated. Hence, setting the incident angle θ1 to a value ranging from approximately 50° to approximately 70° and increasing the integral of the light by, for example, extending the output time of the lamp 211a and/or extending the exposure time (by transporting the stage 11 at a slower speed) can be another effective way of achieving a small pre-tilt angle of the liquid crystal molecules.
In addition, in the present embodiment, the regions I and II formed in the substrate W are contiguous to one other, but the regions I and II does not have to be contiguous to one another. For example, there may be a gap between one region I and a neighboring region II. In addition, in the present embodiment, both the polarized light emitted from the light radiation unit 21 and the polarized light emitted from the light radiation unit 22 pass through the light transmission region 32a formed in the mask 32. However, a different configuration is possible in some forms of the regions I and II. Specifically, the polarized light emitted from the light radiation unit 21 passes through a light transmission region formed at a position in the mask while the polarized light emitted from the light radiation unit 22 passes through the light transmission region formed at a different position in the mask.
In the first embodiment, the regions I and II having different pre-tilt directions from each other are formed on the substrate W by rotating the stage 11 between the events of exposure, but this is not the only method of forming the regions I and II on the substrate W.
The second embodiment is an embodiment where the stage 11 is not rotated and where the regions I and II are formed substantially simultaneously on the substrate W. Now, a polarized light radiation device 2 according to the second embodiment will be described. Note that the same components as those of the polarized light radiation device 1 according to the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.
The transport unit 10A mainly includes a stage 11, a horizontal drive unit 12a configured to move the stage 11 in the horizontal direction (see
The light radiation unit 20A is configured to radiate light onto the substrate W, and includes two light radiation units 21 and 23. The light radiation unit 23 has an identical configuration to the configuration of the light radiation unit 21, and is provided so as to face the light radiation unit 21.
The P-polarized light having transmitted through the PBS 216 of the light radiation unit 21 enters at an incident angle θ1 that ranges from approximately 50° to approximately 70°. The P-polarized light having transmitted through the PBS 216 of the light radiation unit 23 enters at an incident angle θ2 that also ranges from approximately 50° to approximately 70°. The incident angle θ1 and the incident angle θ2 are surface symmetrical with respect to a plane that includes the line H and that is substantially orthogonal to the x direction.
The mask unit 30A is provided on the optical paths of the light radiated onto the substrate W from the light radiation units 21 and 23. When polarized light is radiated onto the substrate W from the light radiation units 21 and 23, the mask unit 30A and the top surface 11a are contiguous to each other.
The mask unit 30A mainly includes a mask 33 and a mask holding unit 35. The mask 33 is a substantially plate-like member having a substantially rectangular shape in plan view. The mask 33 is held substantially parallel to the top surface 11a by the mask holding unit 35. In addition, the mask 33 is driven in the x direction, the y direction, the z direction, and the θ direction by the mask holding unit 35.
A plurality of light transmission regions 33a are arranged in line along the y direction and so are a plurality of light transmission regions 33b. In addition, the light transmission regions 33a and the light transmission regions 33b are disposed in a staggered manner so that none of the light transmission regions 33a is disposed at a position that overlaps the position of any of the light transmission regions 33 in the x direction or in the y direction.
Next, the operations of the polarized light radiation device 2 configured as described above will be described with reference to
Of the P-polarized light from the light radiation unit 21, the light that has passed through the light transmission region 33a is first radiated onto the substrate W1, and is then radiated onto the substrates W2 and W3. Likewise, of the P-polarized light from the light radiation unit 23, the light that has passed through the light transmission region 33b is first radiated onto the substrate W1, and is then radiated onto the substrates W2 and W3.
The regions irradiated with the polarized light that has passed through the light transmission region 33a (i.e., regions III, not illustrated) and the regions irradiated with the polarized light that has passed through the light transmission region 33b (i.e., regions IV, not illustrated) are band-like regions each of which extends along the transport direction F. The regions III correspond to the regions I, and the regions IV correspond to regions II. The regions III and IV are formed alternately along the y direction and contiguously to each other.
When the position determination unit 101c determines that the substrates W2 and W3 have traveled past the light-irradiated region EA3, the light source control unit 101a turns off the lamps 211a of the light radiation units 21 and 23. Then, with the lamps 211a kept in that state, the drive control unit 101b moves the stage 11 in the transport direction F. Thereafter, the control unit 101 terminates the series of processes.
According to the present embodiment, polarized light can be radiated from different directions in a single exposure process. Thus, the regions III and IV may be formed simultaneously in a single exposure process. In addition, because each of the incident angles θ1 and 02 ranges from approximately 50° to approximately 70°, an alignment film can be produced through the photoalignment process so that the liquid crystal molecules have a small pre-tilt angle.
Embodiments of the invention have been described in detail with reference to the drawings. However, specific configurations are not limited to the embodiments, and changes in the design or the like are also included within a scope which does not depart from the gist of the invention.
Further, the term “substantially” in the present invention is not to be understood as merely being strictly the same, and is a concept that includes variations and modifications to an extent that does not result in loss in identity. For example, a term “substantially parallel” and a term “substantially orthogonal” are not limited to “strictly parallel” and “strictly orthogonal”. In addition, for example, terms such as “parallel”, “orthogonal”, and the like include “substantially parallel”, “substantially orthogonal”, and the like, respectively. To put it differently, those terms are not strictly limited to the parallel state, orthogonal state, and the like, respectively. In addition, the term “proximity” is used in the present invention to mean a concept where, for example, a place in the proximity of a certain point A may include the point A or otherwise as long as the place is near the point A.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-011797 | Jan 2017 | JP | national |
This application is a continuation application of International Patent Application No. PCT/JP2018/001071 filed on Jan. 16, 2018, which claims priority to Japanese Patent Application No. 2017-011797 filed on Jan. 26, 2017, the entire contents of which are incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2018/001071 | Jan 2018 | US |
| Child | 16435443 | US |
