JP6488964B2 - UV irradiation equipment - Google Patents

Description

  Embodiments described herein relate generally to an ultraviolet irradiation device.

  At present, attention is focused on a photo-alignment technique (see, for example, Patent Document 1 and Patent Document 2) as a technique that replaces a rubbing process that is an alignment process of an alignment film of a liquid crystal panel. The ultraviolet irradiation device used in the photo-alignment technique includes a rod-shaped lamp that is a light source and a polarizing element. This type of ultraviolet irradiation apparatus performs alignment processing of the alignment film by causing the polarizing element to pass ultraviolet light having a polarization axis in a predetermined direction out of ultraviolet light irradiated by the rod-shaped lamp, and irradiating the passed ultraviolet light to the workpiece.

JP 2009-265290 A JP 2011-145382 A

  However, in order to obtain polarized light having a good extinction ratio using a polarizing element, it is necessary to use a plurality of polarizing elements in a stacked manner. If a plurality of polarizing elements are stacked, the transmittance is lowered, which is not preferable.

  An object of this invention is to provide the ultraviolet irradiation device which suppresses the fall of the transmittance | permeability of a polarizing element, and the deterioration of an extinction ratio.

  The ultraviolet irradiation device of the embodiment includes a light source and a polarizing element. The light source emits ultraviolet light. The polarizing element is irradiated with light emitted from a light source, emits a polarization component of the irradiated light, and an antireflection film is formed on the side where the light source is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the ultraviolet irradiation device which suppresses the fall of the transmittance | permeability of a polarizing element and the deterioration of an extinction ratio can be provided.

FIG. 1 is a perspective view showing a schematic configuration of the ultraviolet irradiation apparatus according to the first embodiment. FIG. 2 is a view of the polarizing element 20 used in the ultraviolet irradiation apparatus according to the first embodiment as seen from the Y-axis direction. FIG. 3 is a diagram showing a result of comparing the transmittance and the extinction ratio in the ultraviolet irradiation apparatus according to the first embodiment. FIG. 4 is a perspective view illustrating a schematic configuration of a modified example of the ultraviolet irradiation apparatus according to the first embodiment. FIG. 5 is a view of the polarizing element 25 used in the ultraviolet irradiation apparatus according to the second embodiment when viewed from the Y-axis direction.

  The ultraviolet irradiation devices 1, 1-1 according to the embodiments described below are irradiated with a light source 10 that emits ultraviolet U, and light emitted from the light source 10, and emits polarized light UA out of the emitted light. And polarizing elements 20 and 25 having an antireflection film 23 formed on the side where the light source 10 is provided.

  Moreover, in the ultraviolet irradiation device 1, 1-1 which concerns on embodiment described below, the film thickness of the antireflection film 23 is 45-90 micrometers.

  Moreover, in the ultraviolet irradiation devices 1 and 1-1 according to the embodiments described below, the polarizing element 20 is a wire grid polarizing element in which a wire grid 22 is formed on one side of the substrate 21, and the antireflection film is a substrate. 21 is formed on the other side.

  Moreover, in the ultraviolet irradiation devices 1 and 1-1 according to the embodiments described below, the polarizing element 25 is an absorptive polarizing element.

(First embodiment)

  Next, the ultraviolet irradiation apparatus 1 which concerns on the 1st Embodiment of this invention is demonstrated based on drawing. FIG. 1 is a perspective view showing a schematic configuration of an ultraviolet irradiation apparatus according to the embodiment, and FIG. 2 is a view of the polarizing element 20 of the ultraviolet irradiation apparatus 1 according to the embodiment as viewed from the Y-axis direction.

  The ultraviolet irradiation apparatus 1 according to the embodiment shown in FIG. 1 has a polarization axis PA (indicated by an arrow in FIG. 1 and indicated by a vibration direction) parallel to a predetermined reference direction on the surface of a workpiece W as an object of alignment treatment. (Also referred to as ultraviolet) UA. The ultraviolet irradiation device 1 of the embodiment is used for manufacturing, for example, an alignment film of a liquid crystal panel, an alignment film of a viewing angle compensation film, a polarizing film, and the like. The ultraviolet irradiation device 1 mainly irradiates the surface of the workpiece W with ultraviolet UA having a wavelength of 365 (nm) as a desired wavelength. The “ultraviolet rays” referred to in the present embodiment refers to light in a wavelength band from 240 (nm) to 450 (nm), for example.

  Note that the polarization axis PA of the ultraviolet light UA irradiated on the surface of the workpiece W is appropriately set according to the structure, use, or required specifications of the workpiece W. Hereinafter, the width direction of the workpiece W is referred to as the X-axis direction, the longitudinal direction of the workpiece W is referred to as the Y-axis direction, and the direction orthogonal to the Y-axis direction and the X-axis direction is referred to as the Z-axis direction. . Regarding the direction parallel to the Z axis, the direction toward the tip of the arrow indicating the direction of the Z axis is referred to as upward, and the direction facing the direction toward the tip of the arrow indicating the direction of the Z axis is referred to as downward.

  As shown in FIG. 1, the ultraviolet irradiation device 1 includes a light source 10 that uniformly oscillates in all directions and emits ultraviolet U having a wavelength of about 365 (nm), and a polarizing element 20.

  As the light source 10, a discharge lamp 11 is used. The ultraviolet light U emitted from the light source 10 is so-called non-polarized light including ultraviolet light having a wavelength of 254, 365 (nm) or the like and having various polarization axis components. In the present embodiment, one light source 10 is provided and disposed above the polarizing element 20 and the workpiece W.

  In the ultraviolet irradiation device 1 according to the first embodiment, the light source 10 includes a discharge lamp 11.

  The discharge lamp 11 emits ultraviolet rays U. The discharge lamp 11 emits at least ultraviolet rays U. The discharge lamp 11 may emit visible light or infrared light in addition to the ultraviolet light U. The discharge lamp 11 is formed extending in a cylindrical shape. The discharge lamp 11 is a so-called high-pressure mercury lamp having a light emission length of 100 mm to 1000 mm, in which a light emitting material such as mercury or a rare gas is sealed in a discharge space (not shown) and a discharge electrode (not shown) is sealed at both ends. The discharge lamp 11 is not limited to a high pressure mercury lamp. The discharge lamp 11 may be a so-called metal halide lamp in which a metal halide is enclosed in a high-pressure mercury lamp.

  The light source 10 may have a reflecting mirror 12 above the discharge lamp 11. The reflecting mirror 12 efficiently irradiates the work W with the ultraviolet rays U emitted from the discharge lamp 11. The reflecting mirror 12 has a bowl shape formed along the direction in which the discharge lamp 11 extends. The shape of the reflecting mirror 12 when viewed in a cross section perpendicular to the extending direction of the discharge lamp 11 may be, for example, an elliptical shape or a part of a parabolic shape, or may be a linear shape. For example, the reflecting mirror 12 is provided with a coating that reflects, for example, ultraviolet rays U toward the workpiece W on the side of the discharge lamp 11 of the reflecting mirror 12 on glass as a base material. The reflecting mirror 12 may be a so-called cold mirror that reflects only the ultraviolet light U and transmits visible light or infrared light. The reflecting mirror 12 has a linear shape that approximates a metal material that reflects the ultraviolet light U so as to be a part of an elliptical shape or a parabolic shape when viewed in a cross section perpendicular to the direction in which the discharge lamp 11 extends. It may be configured.

  The polarizing element 20 is irradiated with ultraviolet rays U emitted from the light source 10. The polarizing element 20 transmits polarized light (ultraviolet light UA) having a polarization axis PA parallel to the reference direction in the ultraviolet light U toward the workpiece W. That is, the polarizing element 20 extracts the ultraviolet ray UA having the polarization axis PA that has oscillated only in the reference direction from the ultraviolet ray U having the polarization axis PA. The ultraviolet ray UA having the polarization axis PA that oscillates only in the reference direction is generally referred to as linearly polarized light. The polarization axis PA of the ultraviolet UA is the vibration direction of the electric field and magnetic field of the ultraviolet UA.

  In the present embodiment, the polarizing element 20 is provided below the light source 10 and above the surface of the workpiece W. The polarizing element 20 forms a wire grid arranged in a certain direction included in a glass plate, and absorbs ultraviolet rays having a polarization axis that intersects the reference direction among the ultraviolet rays U emitted from the light source 10. It is a polarizing element that transmits ultraviolet light UA having a polarization axis PA parallel to the direction.

  Here, the polarizing element 20 will be described in more detail with reference to FIG.

  The polarizing element 20 is, for example, a so-called wire grid polarizing element in which a wire grid 22 is formed on one surface of the substrate 21. An antireflection film 23 is formed on the surface of the substrate 21 opposite to the side on which the wire grid 22 is formed.

  The wire grid 22 is formed on one surface of the substrate 21 with a width of 25 nm to 50 nm and adjacent wire grids 22 extending in one direction with an interval of 50 nm to 150 nm. The wire grid 22 is formed of, for example, chromium (Cr), an aluminum alloy (Al), a molybdenum silicon alloy (MoSix), and silicon (Si).

  The antireflection film 23 suppresses the reflection of the ultraviolet ray U incident on the polarizing element 20 to a reflectance of 10% or less, preferably a reflectance of 2% or less. The “reflectance” referred to here is 100% reflectivity when all the ultraviolet rays U incident on the polarizing element 20 are reflected by the surface of the polarizing element 20. In other words, when the reflectance is 0%, all the ultraviolet rays U incident on the polarizing element 20 are incident on the polarizing element 20. That is, the smaller the reflectance, the better.

The antireflection film 23 is formed on the other surface of the polarizing element 20, and specifically, the surface of the polarizing element 20, specifically, the surface facing the light source 10 of the polarizing element 20, that is, the air present in the ultraviolet irradiation device 1. Reflection of the ultraviolet rays U is suppressed at the interface between the polarizing element 20 (not shown). The antireflection film 23 has a film thickness of 45 to 90 μm on the surface of the substrate 21 opposite to the side on which the wire grid 22 is formed, and is formed by, for example, a vacuum deposition method, a sputtering method, a CVD method, or the like. The antireflection film 23 is made of a dielectric material such as silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), magnesium fluoride (MgF ₂ ), for example. The antireflection film 23 is formed by, for example, a UV multi-coat manufactured by Edmund Optics. If the film thickness of the antireflection film 23 is smaller than 45 μm, a loss due to reflection at 254 nm occurs and the effect of the antireflection film cannot be obtained, which is not preferable. On the other hand, if the film thickness of the antireflection film 23 is larger than 90 μm, a loss due to reflection at 365 nm occurs, and the effect of the antireflection film cannot be obtained.

  Next, the operation of the ultraviolet irradiation device 1 according to the embodiment will be described. The ultraviolet irradiation device 1 according to the embodiment having the above-described configuration positions the workpiece W below the polarizing element 20 and emits ultraviolet rays U from the light source 10. Then, the ultraviolet ray U emitted from the light source 10 is emitted directly toward the polarizing element 20. Further, in the ultraviolet irradiation device 1, the polarizing element 20 transmits the ultraviolet light UA having a polarization axis PA parallel to the reference direction of the ultraviolet light U toward the light irradiation region on the surface of the work W and is oriented on the surface of the work W. Apply processing.

  In the ultraviolet irradiation device 1 according to the embodiment having the above-described configuration, in the case where the polarizing element 20 in which the antireflection film 23 is formed is used, compared to the case in which the polarizing element 20 in which the antireflection film 23 is not formed is used. The deterioration of the extinction ratio can be suppressed without lowering the transmittance. Although the mechanism regarding the influence on the transmittance and extinction ratio due to the presence or absence of the antireflection film 23 is unknown, it is desirable that the polarizing element 20 has the antireflection film 23 formed thereon. Therefore, by forming the antireflection film 23 on the polarizing element 20, it is possible to suppress a decrease in the transmittance of the polarizing element 20 and a deterioration in the extinction ratio.

  Further, in the ultraviolet irradiation device 1, since the antireflection film 23 is formed on the polarizing element 20, a decrease in the transmittance of the polarizing element 20 can be suppressed, so that it is not necessary to increase the output of the light source 10, for example. In order to further increase the amount of the ultraviolet light UA with respect to the workpiece W, it is conceivable to increase the transmittance of the polarizing element 20 or increase the output of the light source 10. However, if the output of the light source 10 is increased, the antireflection film 23 is increased. This is because more ultraviolet rays U are irradiated. The degree of deterioration of the antireflection film 23 can be estimated by the accumulated light amount of the ultraviolet ray U. Therefore, there is a concern that the antireflection film 23 formed on, for example, the polarizing element 20 is deteriorated by the ultraviolet light U by increasing the output of the light source 10. Further, it is desirable to increase the transmittance of the polarizing element 20 because the amount of the ultraviolet light UA can be increased with respect to the workpiece W without increasing the output of the light source 10.

  Therefore, it is possible to provide an ultraviolet irradiation device that suppresses the decrease in the transmittance of the polarizing element and the deterioration of the extinction ratio.

  Here, the extinction ratio and the transmittance with and without the antireflection film 23 with respect to the polarizing element 20 were evaluated. The transmittance is, for example, an ORC UV illuminance meter UV-M03A as an illuminance meter, an ORC sensor UV-35N as a sensor, a wire grid 22 as a polarization element 20, and a polarization element 20 without an antireflection film 23. The illuminance measured using this was normalized to 100%. The extinction ratio ER is a numerical value representing the quality of polarization, and is expressed by ER = Ip / Is using the P polarization intensity Ip and the S polarization intensity Is, and the P polarization intensity Ip and the S polarization intensity Is are expressed as illuminometers. As an ORC ultraviolet illuminance meter UV-M03A, and as a sensor using an ORC sensor UV-35N.

  The conditions of the polarizing element 20 are as follows. In the present invention, the polarizing element 20 is provided with the antireflection film 23 provided on the surface opposite to the side on which the wire grid 22 is formed. Further, as a conventional product, a polarizing element 20 not provided with the antireflection film 23 was used. Further, as Comparative Example 1, the polarizing element 20 provided with the antireflection film 23 on the surface side on which the wire grid 22 was formed was used. Further, as Comparative Example 2, a polarizing element 20 provided with an antireflection film 23 on both the surface side where the wire grid 22 was formed and the surface opposite to the side where the wire grid 22 was formed was used.

  The results for transmittance and extinction ratio are shown in FIG. As is clear from FIG. 3, as the present invention shows, the polarizing element 20 provided with the antireflection film 23 on the surface opposite to the side on which the wire grid 22 is formed has a change in transmittance as compared with the conventional product. However, the extinction ratio is improved by 30%. On the other hand, Comparative Example 1 shows no change in the transmittance and extinction ratio from the conventional product. Further, in all of Comparative Examples 2, the transmittance is 10% and the extinction ratio is 40% worse. Therefore, by providing the antireflection film 23 on the surface opposite to the surface on which the wire grid 22 is formed on the polarizing element 20, it is possible to suppress the deterioration of the transmittance and the extinction ratio.

  The antireflection film 23 is desirably formed on the side facing the light source 10. This is because even if the antireflection film 23 is provided on the surface opposite to the side facing the light source 10, it does not affect the improvement of the extinction ratio. In the polarizing element 20, the wire grid 22 is desirably provided on the side opposite to the side facing the light source 10. By providing the wire grid 22 on the side opposite to the side facing the light source 10, the wire grid 22 can be prevented from being directly exposed to the ultraviolet light U on the light source 10 side, and the wire grid 22 is deteriorated by the ultraviolet light U. It is because it can suppress.

In the present embodiment, an optical element other than the polarizing element 20 is not provided, but the present invention is not limited to the above configuration. For example, a filter that cuts visible light or infrared light longer than desired ultraviolet light may be provided between the light source 10 and the polarizing element 20. In addition, a filter that cuts visible light or infrared light longer than desired ultraviolet light may be provided between the polarizing element 20 and the workpiece W. Further, a polarizing element 20 may be further provided between the polarizing element 20 and the workpiece W.
(Modification)

  FIG. 4 is a perspective view illustrating a schematic configuration of a modified example of the ultraviolet irradiation apparatus according to the first embodiment.

  In the present embodiment, an ultraviolet irradiation device 1-1 having a plurality of light emitting elements 14 as the light source 10 is shown.

  The light source 10 is configured by providing a plurality of light emitting elements 14 on a base 13. The base 13 holds a plurality of light emitting elements 14. Moreover, the base | substrate 13 suppresses the temperature rise of the several light emitting element 14 by conveying the heat | fever emitted from the several light emitting element 14 to the exterior of the ultraviolet irradiation device 1-1. The base 13 may be made of a metal such as aluminum or a material with good heat dissipation such as a ceramic substrate. Further, the base 13 may have a heat dissipation medium flow path through which a heat dissipation medium (not shown) for quickly transferring heat emitted from the plurality of light emitting elements 14 flows. Moreover, you may have a heat dissipation medium supply port which supplies the heat dissipation medium which is not shown in figure, and a heat dissipation medium discharge port which discharge | releases a heat dissipation medium. Further, the heat dissipation medium may be circulated by a circulation mechanism (not shown).

  The light emitting element 14 is provided on the base 13 and emits ultraviolet rays U. The light emitting element 14 emits at least ultraviolet rays U, and is composed of a semiconductor such as an LED (Light Emitting Diode) or an LD (Laser Diode). The light-emitting element 14 includes a first light-emitting element (not shown) that emits ultraviolet light having a first peak wavelength, and a second light-emitting element (not shown) that emits ultraviolet light having a second peak wavelength different from the first peak wavelength. Not). The light emitting element 14 emits ultraviolet light U by mixing ultraviolet light having a first peak wavelength emitted from the first light emitting element and ultraviolet light having a second peak wavelength emitted from the second light emitting element. Note that the arrangement mode of the first light-emitting element and the second light-emitting element is not limited. For example, the first light-emitting element and the second light-emitting element may be disposed on one surface of the base 13 so as to extend in one direction, or the second light-emitting element may surround the four sides of the first light-emitting element. You may arrange | position with what is called a checkered pattern in which the light emitting element is arrange | positioned.

  Even in such a configuration, similarly to the first embodiment, it is possible to suppress the deterioration of the transmittance and the extinction ratio in the ultraviolet irradiation device.

(Second Embodiment)

  FIG. 5 is a view of the polarizing element 25 used in the modified example of the ultraviolet irradiation apparatus according to the second embodiment as seen from the Y-axis direction.

  In the present embodiment, a polarizing element 25 that is an absorptive polarizing element is shown.

  The polarizing element 25 is provided below the light source 10 and above the surface of the workpiece W. The polarizing element 25 is called an absorptive polarizing element, and is formed of metal nanoparticles aligned in a certain direction contained in a glass plate. The polarizing element 25 has a reference direction of the ultraviolet rays U emitted from the light source 10 and It is a polarizing element that absorbs ultraviolet rays having intersecting polarization axes and transmits ultraviolet rays UA having a polarization axis PA parallel to the reference direction. As the absorption polarizing element 25, for example, colorpol (registered trademark) UV375BC5 manufactured by CODIXX can be used.

  Even with such a configuration, it is possible to suppress the deterioration of the transmittance and the extinction ratio, as in the first embodiment.

  In the polarizing element 25, the antireflection film 23 is desirably formed on the side facing the light source 10. This is because even if the antireflection film 23 is provided on the surface opposite to the side facing the light source 10, it does not affect the improvement of the extinction ratio.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment is included in the invention described in the scope of claims and its equivalent scope as well as included in the scope and spirit of the invention.

DESCRIPTION OF SYMBOLS 1, 1-1 Ultraviolet irradiation device 10 Light source 11 Discharge lamp 12 Reflector 13 Base 14 Light emitting element 20, 25 Polarizing element 21 Base 22 Wire grid 23 Antireflection film 26 Base U Light UA Ultraviolet (light)
PA Polarization axis W Workpiece (object)

Claims (3)

A light source that emits ultraviolet light;
A polarizing element that is irradiated with light emitted from the light source, emits polarized light of the irradiated light, and has an antireflection film formed on the side where the light source is provided;
I have a,
The polarizing element is a wire grid polarizing element in which a wire grid is formed on one side of a substrate, and the antireflection film is an ultraviolet irradiation device formed on the other side of the substrate .   The ultraviolet irradiation apparatus according to claim 1, wherein the antireflection film has a thickness of 45 to 90 μm.   The ultraviolet irradiation apparatus according to claim 1, wherein the polarizing element is an absorptive polarizing element.

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