TW201520661A - Polarization light irradiation device for photo alignment - Google Patents

Abstract

A polarization light irradiation device for photo alignment is provided, which is capable of obtaining a polarized light with a good extinction ratio even if its wavelength is less than 300nm. Further, within the above wavelength range, even if angles of light entering into a polarization unit are different, the transmittance would not be changed, and a polarization axis would not be rotated either. The present invention comprises the following means : a work-piece (4) is conveyed along an arrow direction as shown in figures; and light from a light irradiating part (6) is polarized by a wire grid type polarizing element (1) for being irradiated onto the work-piece (4) conveyed on the light irradiating part (6) to perform a photo alignment process. The grid of the wire grid type polarizing element is formed with titanium oxide (TiOx). Within the wavelength range of 240nm ~ 300nm, a polarized light with a 15:1 or more extinction ratio can be obtained. If the wavelength is less than 300nm, the transmittance would not be changed even if angles of light entering into the polarization unit are different, and the polarization axis would not be rotated either even if angles of light entering into the wire grid type polarizing element are different.

Description

Polarized light irradiation device for light alignment

The present invention relates to an alignment film for a liquid crystal panel, or a polarized light irradiation device for aligning light having a predetermined wavelength of polarized light applied to an alignment layer of a viewing angle compensation film, and more particularly, relating to a combined linear light source. A polarized light irradiation device for light alignment of a rod-shaped lamp and a linear lattice-type polarizing element.

In recent years, an alignment film of a liquid crystal panel or an alignment treatment of a viewing angle compensation film has been used, and a technique of aligning polarized light having a predetermined wavelength on an alignment film is referred to as photoalignment.

Hereinafter, a film in which an alignment film provided by the above-described light is aligned as an alignment layer is collectively referred to as a photo-alignment film. In the light-aligning film, the size of the liquid crystal panel is increased (for example, a square shape of 2 m or more), and the polarized light irradiation device that irradiates the polarized light to the photo-alignment film is also increased in size.

In recent years, in order to perform light alignment of such a large-area light alignment film, a light irradiation device that combines a rod-shaped lamp and a polarizing element having a linear lattice-like lattice (hereinafter referred to as a linear lattice-type polarizing element) has been proposed. (E.g Refer to Patent Document 1 or Patent Document 2).

In the polarized light irradiation device for a light alignment film, when the rod-shaped lamp is used, it is possible to produce a longer light emission. Therefore, by using a rod-shaped lamp having a long light emission in response to the width of the alignment film, when the light from the lamp is irradiated while moving the alignment film in a direction orthogonal to the longitudinal direction of the lamp, a wide area can be aligned. The film was subjected to photoalignment treatment in a short time.

Fig. 8 shows an example of the configuration of a polarized light irradiation device that combines a rod-shaped lamp of a linear light source and a linear lattice-type polarizing element.

In the same figure, the workpiece 40 of the optical alignment film is, for example, a strip-shaped workpiece having a viewing angle compensation film, which is sent by the delivery roller R1 and conveyed in the direction of the arrow in the figure, and is irradiated by the polarized light as follows. The take-up roll R2 is taken up.

The light-irradiating portion 20 of the polarized light irradiation device is a rod-shaped lamp 21 including light of a wavelength (ultraviolet light) necessary for the radiation-aligning process, for example, a high-pressure mercury lamp or a metal halide lamp in which mercury is added to other metals, and The ultraviolet ray of the rod-shaped lamp 21 is reflected toward the workpiece 40 to condense the condensing mirror 22. As described above, the length of the rod-shaped lamp 21 is a length in which the light-emitting portion has a width corresponding to a direction orthogonal to the conveyance direction of the workpiece 40. The light irradiation unit 20 is disposed such that the longitudinal direction of the lamp 21 is in the width direction of the workpiece 40 (the direction orthogonal to the conveyance direction).

A linear lattice-type polarizing element 10 having a polarizing element is provided on the light emitting side of the light-irradiating portion 20. The light from the light-irradiating portion 20 is polarized by the linear lattice-type polarizing element 10, and is irradiated onto the workpiece 40 conveyed under the light-irradiating portion 20, and is subjected to a light alignment process.

The linear lattice-type polarizing element is shown in detail in, for example, Patent Document 3 or Patent Document 4.

Fig. 9 is a view showing a schematic structure of a linear lattice-type polarizing element.

The linear lattice-type polarizing element 10 is a surface of a substrate (for example, quartz) 10b that transmits a wavelength of light to be polarized (a wavelength of ultraviolet light necessary for optical alignment when light is aligned), and is parallel at equal intervals of a pitch P. A plurality of linear electric conductors (for example, metal wires such as chrome or aluminum, hereinafter referred to as gate 10a) having a length longer than the width are disposed.

Further, basically, when the pitch P of the gate electrode 10a is narrowed, the wavelength of the polarized light is shortened.

When the polarizing element is inserted into the optical path, the polarization component parallel to the longitudinal direction of the gate is mostly reflected, and the orthogonal polarization component passes. Therefore, the light that has passed through the linear lattice-type polarizing element is polarized light having a polarization axis that is orthogonal to the longitudinal direction of the lattice of the polarizing element.

Further, for the improvement of the manufacturing method or material for forming the lattice, for example, Patent Document 5 is proposed.

Conventionally, as a light-aligning polarizing light irradiation device, a linear lamp-type linear lattice-type polarizing element in which a linear light source is used is based on the following reasons.

The light from the rod-shaped lamp is divergent light, and even if a polarizing element is disposed on the light-emitting side and the polarized light is to be obtained, light of various angles is incident on the polarizing element.

As the polarizing element, there are known a vapor deposition film or a Brewster angle (Brek, ster's angle).

However, such polarizing elements cannot be polarized only by polarizing elements. The light that is incident on the corner, and the light that is incident only outside of it, passes through almost no polarized light. Therefore, when the light source is divergent light, if a vapor deposition film or a polarizing element using a Brewster angle is used, the obtained polarized light is compared with a case where the light incident on the polarizing element is made to be parallel light and the incident angles are matched. The extinction ratio is getting worse.

Further, there is a polarizing element using an organic film. However, since light having a long-term exposure to ultraviolet light used for light alignment is deteriorated, the characteristics are deteriorated, and thus it is industrially used.

On the other hand, the linear lattice-type polarizing element has a small dependence on the extinction ratio of the polarized light that is incident on the polarizing element, and therefore, even if the light is emitted from the rod-shaped lamp, the light is emitted. When the angle is within the range of ±45°, the field in which the light is irradiated is comprehensive, and the polarized light having an excellent extinction ratio can be obtained.

Therefore, the length of the rod-shaped lamp is set corresponding to the width of the film of the photo-alignment film, and the photo-alignment film is relatively moved in one direction for the polarized light irradiation device, and in principle, one lamp can be used for a wide area of light alignment. Orientation treatment of the membrane.

When a linear lattice-type polarizing element is combined with a rod-shaped lamp, it is not necessary to make the light from the light source an optical element for parallel light, and the entire apparatus can be manufactured at low cost.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-163881

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-144884

Patent Document 3: Japanese Laid-Open Patent Publication No. 2002-328234

Patent Document 4: Japanese Patent Publication No. 2003-508813

Patent Document 5: Japanese Laid-Open Patent Publication No. 2007-178763

Non-Patent Document 1: H. Shitomi. et al. "Optically Controlled Alignment of Liquid Crystal on Polyimide Films Exposed to Undulator Radiation" Proc. Int. Conf. SRMS-2 Jpn. J. Appl. Phys. Vol. 38 (1999) .pp. 176-179

In many cases, a light alignment film which is aligned with polarized light having a wavelength of 300 nm to 500 nm is known. Recently, an optical alignment film which is aligned with polarized light having a wavelength of 300 nm or less (200 nm to 300 nm) can be produced (see Non-Patent Document 1). ).

Therefore, as a polarized light irradiation device, it is required to emit polarized light having a wavelength of 300 nm or less (200 nm to 300 nm), and in particular, an extinction ratio of 15 in a wavelength range of 260 nm ± 10 nm (preferably 260 nm ± 20 nm) is obtained: A device of polarized light of 1 or more.

However, in order to fabricate such a device by combining a rod-shaped lamp and a linear lattice-type polarizing element, there are the following problems.

The lattice of the linear lattice-type polarizing element is formed by etching. Therefore, as a material of the lattice, aluminum which is easy to process is conventionally used, but when the lattice is formed of aluminum, the inventors have found that the following three problems occur.

(1): In the field of wavelengths of 300 nm or less, the extinction ratio of polarized light is lowered, and in the wavelength range of about 250 nm or less, the extinction ratio becomes 1:1 (becomes unpolarized).

(2): In a field having a wavelength of 340 nm or less, the transmittance changes due to the angle of light incident on the linear lattice-type polarizing element. As described above, the light from the rod lamp is divergent light. Therefore, the angle of the light incident on the polarizing element is different depending on the place (the light is directly below the center of the polarizing element, and the light having a small incident angle is large, and the peripheral portion has a large angle of incidence. More light components). Therefore, when the transmittance changes due to the angle of the light incident on the polarizing element, the illuminance unevenness is generated in the emitted polarized light (the illuminance distribution in the field of the polarized light irradiation becomes large).

(3): When the angle of light incident on the linear lattice-type polarizing element increases, the direction of the polarized light emitted from the polarizing element changes. In other words, as the angle of incidence of the polarizing element increases, the angle of rotation of the polarization axis of the emitted polarized light increases.

As described above, the angle of the light incident on the polarizing element is such that in the central portion of the polarizing element, the amount of light having a small incident angle is large, and in the peripheral portion, the amount of light having a large incident angle is large. . Therefore, in the central portion of the irradiation region of the irradiation to which the polarized light is irradiated, even if the direction of the polarization axis of the polarized light is in a desired direction, the direction of the polarization axis of the polarized light is rotationally deviated from the desired direction in the peripheral portion. That is, in the field of irradiation of polarized light, a direction deviation occurs in the polarization axis.

In the field of irradiation of polarized light, when the illuminance of the polarized light is not uniform or the direction of the polarizing axis is deviated, the alignment film is in a portion where the desired alignment characteristics are not obtained.

The present invention has been made in view of the above-mentioned matters, and combines a linear light source and a linear lattice-type polarizing element to illuminate a light-aligning film with polarized light. The light irradiation device provides polarized light which can obtain a good extinction ratio even in a wavelength region of 300 nm or less. Further, in the field of the wavelength of 300 nm or less, even if the angle of the light incident on the polarizing element is not the same, the transmittance does not change, and even if the angle of the light incident on the linear lattice-type polarizing element is not the same, It is an object of the polarized light irradiation device which does not change the direction of the emitted polarized light (the polarization axis rotates).

As a result of intensive review, the present inventors have solved the above problems by forming a lattice of a linear lattice-type polarizing element using titanium oxide (TiOx).

In other words, when a polarizing element having a lattice formed of titanium oxide (TiOx) is used, a polarized light having a good extinction ratio can be obtained in a wavelength region of 300 nm or less, even if the sensitivity of the photoalignment film is in the range of 200 to 300 nm. The workpiece can also be optically aligned for effect.

According to the present invention, in the polarized light irradiation device for light alignment, the light-irradiating portion that emits light from the linear light source by polarizing the linear lattice-type polarizing element and emits the polarized light of the light-emitting portion The polarized light irradiation device for light alignment which is irradiated to the alignment film is characterized in that the lattice of the linear lattice-type polarizing element is formed of titanium oxide (TiOx).

In the present invention, the following effects can be obtained.

(1) The lattice of the linear lattice-type polarizing element is formed by using titanium oxide (TiOx), whereby a polarized light having a good extinction ratio can be obtained even in a wavelength region of 300 nm or less.

Specifically, an extinction ratio of 15:1 or more can be obtained in the range of 260 nm ± 20 nm.

Therefore, by using the linear lattice-type polarizing element and the linear light source to form the light-irradiating portion of the light-aligning polarizing light irradiation device, the workpiece having the sensitivity of the optical alignment film of 200 to 300 nm can be effectively produced. Light alignment.

(2) By using the above-described linear lattice-type polarizing element, in the field of wavelength 300 nm or less, even if the angle of light incident on the polarizing element is not the same, the transmittance hardly changes.

(3) Further, by using the linear lattice-type polarizing element, even if the angle of the light incident on the linear lattice-type polarizing element is different, the direction of the emitted polarized light (rotation of the polarization axis) hardly changes.

1‧‧‧Linear lattice type polarizing element

1a‧‧‧Linear lattice

1b‧‧‧Substrate

1c‧‧‧ box

2‧‧‧ rod lights

3‧‧‧Mirror

4‧‧‧Workpiece

4a‧‧‧Light alignment film

5‧‧‧Workpiece platform

6‧‧‧Lighting Department

Fig. 1 is a view showing a configuration example of a polarized light irradiation device according to an embodiment of the present invention.

2(a) and 2(b) are diagrams showing a configuration example of a linear lattice-type polarizing element according to an embodiment of the present invention.

3(a) and 3(b) are diagrams showing a configuration example of a linear lattice-type polarizing element in which a plurality of polarizing elements are arranged in alignment.

Fig. 4 is a view showing the relationship between the wavelength of the non-polarized light incident on the linear lattice-type polarizing element and the extinction ratio of the emitted polarized light.

FIGS. 5( a ) and 5 ( b ) are diagrams showing the angles of the non-polarized light incident on the linear lattice-type polarizing element and the spectral transmittance of the light incident at the angle.

Fig. 6 is a view showing the non-polarized light incident on the linear lattice type polarizing element The angle of the relationship with the amount of rotation of the polarization axis of the emitted polarized light.

Fig. 7 is a view showing another configuration example of the polarized light irradiation device of the present invention.

Fig. 8 is a view showing a configuration example of a polarized light irradiation device that combines a rod-shaped lamp and a linear lattice-type polarizing element.

Figs. 9(a) and 9(b) are diagrams showing a schematic structure of a linear lattice-type polarizing element.

Fig. 1 shows an example of the configuration of a polarized light irradiation device according to an embodiment of the present invention.

Similarly to the eighth embodiment, a high-pressure mercury lamp in which a linear light source is provided in the light-irradiating portion 6, a rod-shaped lamp 2 such as a metal halide lamp in which metal is added to mercury, and a groove-shaped reflection reflecting light from the lamp 2 are provided. Mirror 3. Further, a linear lattice-type polarizing element 1 is provided on the light-emitting side. Here, a rod-shaped high-pressure mercury lamp or a metal halide lamp is known as a light source that emits light having a wavelength of 300 nm or less.

Further, unlike FIG. 8, in the first drawing, the workpiece 4 on which the photo-alignment film is formed is not a strip-shaped workpiece but a panel substrate on which the photo-alignment film 4a is formed on the light-transmissive substrate, and is loaded. On the workpiece platform 5. The sensitivity of the photo-alignment film 4a is, for example, in the range of 200 to 300 nm.

In the case of the panel substrate, as in the case of the strip-shaped workpiece, a lamp having a light-emitting length corresponding to the width of the panel substrate is used, and the polarized light is irradiated. In the field, the workpiece 4 is relatively moved in the longitudinal direction of the lamp 2 in the orthogonal direction to perform optical alignment processing.

In other words, the workpiece 4 is conveyed in the direction of the arrow in the figure, and the light from the light-irradiating portion 6 is polarized by the linear lattice-type polarizing element 1 and is irradiated onto the workpiece 4 under the light-emitting portion 6 to be carried. Light alignment treatment.

Hereinafter, a linear light source will be described as an example of a rod-shaped light source. However, in recent years, LEDs or LDs that emit ultraviolet light have been put into practical use, and such LEDs or LDs may be arranged in a line in a line to form a linear light source. At this time, the direction in which the LEDs or LDs are arranged corresponds to the length direction of the lamps.

Fig. 2 shows the configuration of a linear lattice-type polarizing element according to an embodiment of the present invention.

As shown in the figure, a lattice of a linear lattice-type polarizing element is formed by titanium oxide (TiOx).

The lattice 1a of titanium oxide is a surface of a substrate (for example, quartz or magnesium fluoride) 1b which is formed to transmit light having a wavelength of 200 nm to 300 nm. The pitch of the grid is 150 nm. Further, the height of the lattice 1a is 10 nm or more.

In addition, since the linear lattice-type polarizing element cannot be made large, it is actually disposed on the light-emitting side of the light-irradiating portion 6, and as shown in Fig. 3, the same type of complex linear lattice-type polarized light is used. The elements 1 are arranged in a frame 1c. The number of the polarizing elements is appropriately selected in accordance with the size of the field in which the polarized light is irradiated.

Fig. 4 shows the relationship between the wavelength of the non-polarized light incident on the linear lattice-type polarizing element and the sliding ratio of the emitted polarized light. In the same figure, the horizontal axis represents the wavelength (nm) of light, and the vertical axis represents the extinction in the logarithm. Than.

In Fig. 4, A (diamond lattice) is a case where a lattice is formed of titanium oxide, and B (triangular indication) is a case where a lattice is formed of aluminum. Also, the pitch of the grid is both 150 nm.

As shown in the figure, when a lattice is formed of aluminum, a good extinction ratio of 50:1 or more can be obtained in a region having a wavelength of 300 nm or more. However, in the field of wavelengths of 300 nm or less, the extinction ratio is lowered, and at a wavelength of about 270 nm, the extinction ratio is about 10:1, and at a wavelength of about 250 nm, the extinction ratio is about 1:1, and polarized light cannot be obtained.

In this case, when the lattice is formed of titanium oxide, the extinction ratio in the region of wavelength 300 nm or less is better than that in the case of aluminum, and in the range of wavelengths of 240 nm to 300 nm, the extinction ratio can obtain polarized light of 15:1 or more. . Further, a broken line of 240 nm or less is an estimated value.

As described above, it is now required to obtain a polarized light having a wavelength range of 260 nm ± 10 nm (preferably 260 nm ± 20 nm) and an extinction ratio of 15:1 or more, but using a linear lattice-type polarized light in which lattices are formed by using titanium oxide. Components can be reimbursed for this requirement.

Further, in theory, even if the lattice is formed of aluminum, if the pitch is narrowed, it is of course possible to polarize the short-wavelength light. However, in actuality, the pitch is narrowed, the lattice is lacking, or the quality of the emitted polarized light is reduced by meandering, and as a result, polarized light having an extinction ratio of 15:1 or more cannot be obtained. In the current situation, linear lattice-type polarizing elements which are narrower than 150 nm are difficult to manufacture industrially.

In Fig. 5, the non-polarized light incident on the linear lattice type polarizing element is shown. The angle of light and the spectral transmittance of light incident at that angle. Fig. 5(a) is an experimental result showing a lattice formed of titanium oxide, and Fig. 5(b) is an experimental result when a lattice is formed of aluminum.

In the drawings, the horizontal axis represents the wavelength (nm) of light incident on the linear lattice-type polarizing element, and the vertical axis represents the transmittance (%) of light. When the angle (injection angle) of the light incident on the linear lattice-type polarizing element is 0° (vertical incident), it is measured at 30° and 45°, respectively.

When a lattice is formed of titanium oxide or a lattice is formed of aluminum, in a field having a wavelength of 340 nm or more, even if the angle of light incident on the polarizing element changes, the transmittance does not change.

However, when the lattice is formed of aluminum as shown in Fig. 5(b), in the field of wavelength 340 nm or less, when the incident angle is increased, the transmittance is lowered in the specific wavelength region.

For example, the transmittance of light incident on the polarizing element at an angle of 30° is a case where the transmittance is reduced by about 10% in the field of the wavelength of 270 nm to 300 nm as compared with the light having an incident angle of 0°. Further, the transmittance of light incident on the polarizing element at an angle of 45° is a case where the transmittance is reduced by about 15% in the field of the wavelength of 280 nm to 340 nm as compared with the light having an incident angle of 0°.

As described above, when a rod-shaped lamp is used as the light source, the light from the rod-shaped lamp is divergent light, and the light incident on the center of the polarizing element directly under the lamp has a large amount of light having a small angle of incidence. In the peripheral portion, there are many components of light having a large angle of incidence.

Therefore, as described above, when the incident angle of light becomes larger, the light penetration is reduced. At the incident rate, the illuminance of the polarized light becomes small at the peripheral portion of the field irradiated by the polarized light. Therefore, in the peripheral portion of the field of the polarized light irradiation, the photoalignment treatment of the photoalignment film cannot be sufficiently performed.

In this case, when the lattice is formed of titanium oxide as shown in Fig. 5(a), in the wavelength range of 200 nm to 300 nm, the incident angle is 0°, 30°, or 45°. The transmittance is almost no difference. Therefore, in the irradiation field in which the polarized light is irradiated, the illuminance in which the illuminance is not uniform (the illuminance uniformity is high) without the polarized light can be performed. Therefore, the light alignment treatment of the photoalignment film can be sufficiently performed in all fields irradiated with the polarized light.

Fig. 6 shows the relationship between the angle of the non-polarized light incident on the linear lattice-type polarizing element and the amount of rotation of the polarization axis of the emitted polarized light. The horizontal axis represents the angle (°) of the light incident on the linear lattice-type polarizing element, and the vertical axis represents the rotation amount (°) of the polarization axis of the emitted polarized light.

The amount of rotation of the polarization axis is based on the direction of the polarization axis when the incident angle is 0°, and indicates the rotation angle from the position.

In addition, the wavelength of light incident on the linear lattice-type polarizing element was 254 nm when the polarizing element of the lattice was formed of titanium oxide, and 365 nm when the polarizing element of the lattice was formed of aluminum.

As shown in the figure, when the lattice is formed of aluminum, as the angle of incidence of the light becomes larger, the amount of rotation of the polarization axis of the emitted polarized light becomes larger, and when the incident angle is 45°, the polarization axis is rotated by about 6°. .

As described above, since a large amount of light having a small angle is incident in the central portion of the polarizing element, and a large amount of light having a large angle of incidence in the peripheral portion is formed, the incident angle of the light is increased, and the polarized light is large. When the amount of rotation of the polarizing axis becomes large, In the peripheral portion of the field irradiated by the polarized light, the direction of the polarization axis of the polarized light is greatly rotated (deviated) from the desired direction. Therefore, in the peripheral portion of the field of the polarized light irradiation, the optical alignment film cannot be subjected to the photoalignment treatment in a desired direction.

In this case, when the lattice is formed of titanium oxide, even if the incident angle of light changes, the polarization axis of the emitted polarized light hardly rotates.

Therefore, since the field in which the polarized light is irradiated is comprehensive and the irradiation without the deviation of the polarization axis can be performed, the light alignment film can be subjected to the photoalignment process in a desired direction in all areas irradiated with the polarized light.

Fig. 7 shows another configuration example of the polarized light irradiation device of the present invention.

In the same figure, the light-irradiating portion 6 including the rod-shaped lamp 2, the condensing mirror 3, and the linear lattice-type polarizing element 1 in which lattices are formed of titanium oxide is arranged in a plurality of directions in which the workpiece 4 is transported. The workpiece 4 formed by the optical alignment film 4a is placed on the workpiece stage 5 and conveyed in the direction of the arrow in the same figure.

By providing the plurality of light irradiation units 6, the amount of irradiation of the polarized light of the light alignment film 4a irradiated on the workpiece 4 can be increased, so that the conveyance speed of the workpiece 4 can be made faster. Therefore, the production capacity of the light alignment (the number of processes per unit) can be improved.

1‧‧‧Linear lattice type polarizing element

2‧‧‧ rod lights

3‧‧‧Mirror

4‧‧‧Workpiece

4a‧‧‧Light alignment film

5‧‧‧Workpiece platform

6‧‧‧Lighting Department

Claims (1)

A polarized light irradiation device for light alignment is a linear lattice-type polarizing element in which a continuous wavelength light having a wavelength of 300 nm or less from a linear light source is formed on a substrate having a wavelength of 200 nm to 300 nm. The light-irradiating portion that emits the polarized light and irradiates the polarized light of the light-irradiating portion to the light-aligning polarized light irradiation device of the alignment film, wherein the lattice of the linear lattice-type polarizing element directly forms titanium oxide It is formed on the surface of the aforementioned substrate.