JP4846868B1 - Polarized illumination device - Google Patents

Abstract

Provided is a polarization illumination device capable of not only irradiating polarized light with a uniform polarization direction but also reducing the size of a polarizing element for extracting polarized light.
A polarized illumination device includes a light emitting unit and a plurality of light source units including a reflection optical system that reflects light emitted from the light emitting unit, and light polarized from light emitted from the plurality of light source units. , A fly-eye lens 18 on which the polarized light extracted by the polarization element 16 enters, and a parallel light conversion means 20 that converts light emitted from the fly-eye lens 18 into parallel light. The reflection optical system 12 is constituted by a reflection mirror 13 having a substantially parabolic cross section. The polarizing element 16 is disposed at a position where the light emitted from the plurality of light source units 14 can directly enter.
[Selection] Figure 1

Description

  The present invention relates to a polarized light illumination device that can be used, for example, for forming an alignment film of a liquid crystal panel.

  The liquid crystal panel is configured by sandwiching liquid crystal molecules between two transparent substrates. The liquid crystal molecules are arranged in a specific direction, and the transmittance of light from the backlight can be switched by applying a voltage to the liquid crystal molecules. An alignment film for aligning liquid crystal molecules in a specific direction is formed inside the two substrates. This alignment film is formed by a thin film made of polyimide, for example.

  A rubbing method is known as a method for imparting alignment ability to an alignment film. The rubbing method is a method of rubbing the surface of the alignment film with a cloth wound around a rotating roller. Since the rubbing method causes innumerable fine scratches on the surface of the alignment film, it is considered that liquid crystal molecules are arranged in a specific direction along the scratches.

  However, since this rubbing method is a method in which the substrate is physically rubbed with a cloth, there is a problem that dust is generated and adversely affects the quality of the liquid crystal panel. Therefore, in recent years, there has been an interest in a technique for aligning liquid crystal molecules other than the rubbing method, and a photo-alignment method has been proposed as one such technique.

  The photo-alignment method is a method of imparting anisotropy, that is, an alignment ability, to the alignment film by irradiating polarized light to an alignment film such as polyimide having a property of reacting to light. As the light for irradiating the alignment film, ultraviolet light is generally used. In this photo-alignment method, a polarizing plate using a Brewster angle is used in order to extract polarized light from ultraviolet light emitted from an ultra-high pressure mercury lamp or the like. As one of polarized light illumination devices using a polarizing plate, a polarized light irradiation device described in Patent Document 1 is known.

JP-A-10-90684

  The polarizing element used in Patent Document 1 uses only the Brewster angle, requires 8 or more glass plates to increase the P / S separation ratio of polarized light, and attenuates the amount of polarized light reaching the irradiated surface. Has the disadvantage of becoming larger. In addition, since the polarizing element is disposed at approximately 45 degrees with respect to the irradiated surface, the polarizing element also has a drawback of requiring a large area.

  In order to reduce the attenuation of the amount of polarized light, a polarization illumination device 500 as shown in FIG. 11 is known. The polarized light illumination device 500 includes a light emitting unit 502 composed of an ultra-high pressure mercury lamp for emitting ultraviolet light, a reflecting mirror 504 that reflects light emitted from the light emitting unit 502 forward and having directivity, The fly-eye lens 506 to which the light reflected by the reflecting mirror 504 is incident, the concave mirror 508 that reflects the light emitted from the fly-eye lens 506 while converting it into parallel light, and the light that is reflected by the concave mirror 508 is incident. And a polarizing plate 510.

  The polarizing plate 510 is a polarizing plate having a glass plate coated with a polarizing function, and is disposed at a shallow incident angle (for example, 70 degrees). As for the light incident on the polarizing plate 510, only light having a specific polarization direction (for example, P-polarized light) is transmitted and irradiated toward the irradiation object W1. As the irradiation object W1, for example, a glass substrate on which an alignment film made of polyimide is formed is used.

  By the way, in the above-mentioned conventional polarized illumination apparatus 500, the polarizing plate 510 needs to be disposed between the concave mirror 508 and the irradiated object W1. This is because, as a characteristic of the coated polarizing plate 510, only P / S separation can be performed up to an angle of ± several degrees with respect to the incident angle of the principal ray, so that the polarizing plate 510 is provided after the concave mirror 508. This is because it must be arranged.

However, when the polarizing plate 510 is disposed between the concave mirror 508 and the irradiated object W1, the size of the polarizing plate 510 becomes extremely large. For example, when the horizontal width of the light beam incident on the polarizing plate 510 is X1 (m), the inclination of the polarizing plate 510 with respect to the optical axis is θ (degrees), and the horizontal width of the polarizing plate 510 is X2 (m), see FIG. As can be seen, the following equation holds.
X2 = X1 / cosθ

  Therefore, for example, assuming that X1 is 1.0 (m) and θ is 70 (degrees), X2 = 1 / cos70 ° = 2.9 (m). That is, the lateral width X2 of the polarizing plate 510 is close to three times the lateral width X1 of the light beam incident on the polarizing plate 510.

  Furthermore, in recent years, the liquid crystal panel has been increased in size, and the lateral width X1 of the light beam incident on the polarizing plate 510 has also increased. Therefore, the required width X2 of the polarizing plate 510 is also increasing.

  As described above, the conventional polarized illumination apparatus has a problem that an extremely large polarizing plate has to be used. When a large polarizing plate is used, not only does the procurement cost of the polarizing plate increase, but it also becomes difficult to handle the polarizing plate when irradiating the polarized light, leading to an increase in manufacturing cost of the liquid crystal panel. .

  The present invention has been made in view of the above problems, and provides a polarization illumination device that can not only irradiate polarized light with a uniform polarization direction but also can downsize a polarization element for extracting polarized light. The purpose is to do.

  A polarized light illumination device according to the present invention includes a plurality of light source units including a light emitting unit and a reflective optical system that reflects light emitted from the light emitting unit, and a polarizing element that extracts polarized light from the light emitted from the plurality of light source units. And a parallel light converting means for converting the light emitted from the fly-eye lens into parallel light, wherein the reflection is reflected by the reflective illumination device. The optical system includes a reflecting mirror having a substantially parabolic cross section, and the polarizing element is disposed at a position where light emitted from the plurality of light source units can directly enter. .

  According to the present invention, the light emitted from the plurality of light source units is reflected while being converted into parallel light by the reflecting mirror having a substantially parabolic cross section, and then enters the polarizing element. Therefore, it is possible to extract polarized light whose polarization direction is uniform.

Moreover, the polarizing element for extracting polarized light is disposed at a position where light emitted from the plurality of light source units can directly enter. Here, “directly” means that light emitted from a plurality of light source units enters the polarizing element without passing through other optical components such as a mirror and a fly-eye lens.
Therefore, according to the present invention, since the polarizing element can be arranged at a position closest to the plurality of light source units, the polarizing element can be made smaller than the case where the polarizing element is arranged after the concave mirror as in the prior art. Is possible.

In the polarized light illumination device of the present invention, it is preferable to include a rotating means that can rotate the polarizing element.
By providing such a rotating means, it becomes possible to easily rotate the polarization direction of the polarized light extracted by the polarizing element. Thereby, for example, the alignment direction of the alignment film formed by irradiating polarized light can be easily rotated by 90 degrees.

In the polarization illumination device according to the aspect of the invention, it is preferable that the polarization element includes a plurality of polarization mirrors, and light emitted from the plurality of light source units is reflected a plurality of times by the plurality of polarization mirrors.
In this way, the ratio of the S-polarized light to the P-polarized light or the ratio of the P-polarized light to the S-polarized light is made smaller than a predetermined value by reflecting the light emitted from the plurality of light source units a plurality of times by the plurality of polarizing mirrors. Is possible. As a result, it is possible to extract more purely polarized light from the light emitted from the plurality of light source units and irradiate the irradiated object.

  In the polarized light illumination device of the present invention, the irradiated object to be irradiated with polarized light is preferably a processing-oriented alignment film substrate for a liquid crystal panel. By irradiating polarized light with a uniform polarization direction by the polarized illumination device of the present invention, a liquid crystal panel substrate with a uniform alignment direction of the alignment film can be produced. As a result, a large-sized and high-quality liquid crystal panel substrate can be manufactured at low cost.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to irradiate the polarization | polarized-light with which the polarization direction was uniform, the polarized light illuminating device which can miniaturize the polarizing element for taking out polarized light can be provided.

It is a top view of the polarization illumination device concerning a 1st embodiment. It is an enlarged plan view of a polarization illumination device. It is a graph which shows the spectral characteristic when a polarizing element is installed inclining 66.5 degree | times with respect to the optical axis of incident light. It is a graph which shows a spectral characteristic when a polarizing element is installed inclining by 70.0 degree | times with respect to the optical axis of incident light. It is a graph which shows the spectral characteristic when a polarizing element is installed inclining 73.5 degree | times with respect to the optical axis of incident light. It is a top view of the polarization illumination device concerning a 2nd embodiment. It is a front view of the polarization illumination device concerning a 2nd embodiment. It is a top view of the polarization illuminating device which concerns on 2nd Embodiment, and has shown the state after rotating a polarizing plate 90 degree | times. It is a front view of the polarization illuminating device which concerns on 2nd Embodiment, and has shown the state after rotating a polarizing plate 90 degree | times. It is a partial top view of the polarization illuminating device which concerns on 3rd Embodiment. It is a top view of the conventional polarization illumination apparatus.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view of the polarization illumination device 100 according to the first embodiment. FIG. 2 is a plan view in which the polarization illumination device 100 is partially enlarged. As shown in FIGS. 1 and 2, the polarization illumination device 100 includes a plurality of light source units 14 including a light emitting unit 10 and a reflective optical system 12 that reflects light emitted from the light emitting unit 10, and a plurality of light source units 14. Polarizing element 16 for extracting polarized light from the light emitted from the light, fly-eye lens 18 on which the polarized light extracted by polarizing element 16 is incident, and parallel light converting means for converting the light emitted from fly-eye lens 18 into parallel light 20.

  The light emitting unit 10 is configured by an ultrahigh pressure mercury lamp that can emit ultraviolet light. Inside the ultrahigh pressure mercury lamp constituting the light emitting unit 10, two electrodes (not shown) including a cathode and an anode are provided. In addition, mercury of a predetermined mercury vapor pressure, for example, 30 atmospheres or more is enclosed in the ultra high pressure mercury lamp.

  The reflection optical system 12 is constituted by a reflection mirror 13 having a substantially parabolic cross section. The reflecting mirror 13 is formed of a bowl-shaped glass molded body having a parabolic surface. A reflective coating film is formed on the inner surface of the reflecting mirror 13, and the ultraviolet light emitted from the light emitting unit 10 can be reflected forward by the reflective coating film.

  The light emitting unit 10 is disposed at or near the focal point of the reflecting mirror 13. Specifically, the light emitting unit 10 is arranged so that the midpoint between the cathode and the anode of the ultrahigh pressure mercury lamp constituting the light emitting unit 10 is located at or near the focal point of the reflecting mirror 13. Accordingly, the ultraviolet light emitted from the light emitting unit 10 is reflected forward while being converted into parallel light by the reflecting mirror 13.

  The light source unit 14 includes the light emitting unit 10 and the reflective optical system 12. Five light sources 14 are arranged in the horizontal direction and five in the vertical direction, and a total of 25 light sources 14 are arranged on the same plane. Note that an ultraviolet light illuminating device using such a plurality of light source units and fly-eye lenses has already been proposed by the present inventors, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-361746.

  The polarizing element 16 includes a polarizing mirror 17 that transmits P-polarized light and reflects S-polarized light. The polarizing mirror 17 is installed on the front side of the light emitted from the plurality of light source units 14. The polarizing mirror 17 is disposed at a position where light emitted from the plurality of light source units 14 can be directly incident. Here, “directly” means that light emitted from the plurality of light source units 14 enters the polarizing element 16 without passing through other optical components such as a mirror and a fly-eye lens.

  The polarizing mirror 17 is installed to be inclined at a shallow incident angle (for example, 70 degrees) with respect to the optical axis of the light emitted from the plurality of light source units 14. For example, when the polarizing mirror 17 is made of a glass plate, it is preferably 60 degrees or more and 80 degrees or less.

  3 to 5 are graphs showing spectral characteristics (transmittance characteristics of P-polarized light and S-polarized light) when the incident angle of light incident on the polarizing mirror 17 is changed. Hereinafter, the meaning of these graphs will be described.

  Light rays that strike perpendicular to the illuminated surface are called chief rays. For example, when the polarizing mirror 17 is arranged at an angle of 70 degrees, the incident angle of the principal ray is 70 degrees. Here, referring to FIG. 1, the outer edge ray of the cone-shaped light beam reaching each part of the irradiated surface forms an angle of ± several degrees with respect to the principal ray. Therefore, the incident angle of the outer edge ray is 70 degrees ± several degrees.

  FIG. 4 is a graph showing the spectral characteristics of S-polarized light and P-polarized light when the incident angle is 70 degrees, and FIGS. 3 and 5 show the incident angles of 70 ± 3.5 degrees (66.5 degrees and 73.degrees). 5 is a graph showing spectral characteristics of S-polarized light and P-polarized light in the case of 5 degrees). 70 degrees corresponds to the incident angle of the principal ray, and 70 ± 3.5 degrees corresponds to the incident angle of the outer edge ray.

  In the spectrum of a mercury lamp that emits ultraviolet light, 313 nm is a wavelength that contributes to the formation of the alignment film. The spectral half width at a mercury vapor pressure of 70 to 80 atm is about ± 3 nm. 3 to 5, the two-dot chain line indicates the wavelength width of 313 ± 3 nm, and the three-dot chain line indicates the wavelength width of 313 ± 10 nm. As can be seen from FIGS. 3 to 5, if the wavelength width is 313 ± 3 nm, P / S separation with almost 100% light energy can be realized. When the wavelength width is expanded to 313 ± 10 nm, the separation becomes worse due to the light beam outer edge light.

  Increasing the mercury vapor pressure increases the light energy but increases the spectral width, resulting in poor P / S separation. Conversely, when the mercury vapor pressure is lowered, P / S separation is improved, but light energy is reduced. In designing and designing the polarized illumination apparatus 100 of the present invention, the selection of the light source and the coating film applied to the polarizing plate are factors that greatly change the apparatus performance.

  In the above-described embodiment, an example in which the polarizing mirror 17 that reflects polarized light is used as the polarizing element 16 is described. However, as described later, a polarizing plate that transmits polarized light may be used.

  A fly-eye lens 18 is disposed on the front side of the light reflected by the polarizing mirror 17. The fly-eye lens 18 is formed of a lens assembly in which a plurality of identical single lenses having a long and substantially rectangular parallelepiped shape are arranged vertically and horizontally, and light emitted from the plurality of light source units 14 is uniform with respect to the irradiation object W. This is one of the integrator optical systems for irradiating the light.

  The fly-eye lens 18 has an entrance surface 18a and an exit surface 18b substantially parallel to the entrance surface 18a. The ultraviolet light emitted from the plurality of light source units 14 is extracted only by P-polarized light or S-polarized light by the polarizing mirror 17, and then enters the approximate center of the incident surface 18 a of the fly-eye lens 18. The light incident on the incident surface 18 a of the fly eye lens 18 passes through the fly eye lens 18 and is emitted from the exit surface 18 b of the fly eye lens 18.

  The parallel light conversion means 20 is one of the collimator optical systems, and is constituted by a concave mirror that can reflect incident light to the irradiated object W while converting it into parallel light. The light emitted from the emission surface 18b of the fly-eye lens 18 is converted into parallel light by the parallel light conversion means 20, and then irradiated onto the surface of the irradiation object W substantially perpendicularly.

  The irradiated object W is composed of a glass substrate for a liquid crystal panel having an alignment film made of polyimide formed on the surface thereof.

The operational effects of the polarization illumination device 100 configured as described above will be described.
According to the polarization illumination device 100 of the present embodiment, the light emitted from the plurality of light source units 14 is reflected while being converted into parallel light by the reflecting mirror 13 having a substantially parabolic cross section, and then enters the polarizing element 16. To do. Accordingly, since parallel light can be incident on the polarizing element 16, it is possible to uniformly irradiate the irradiated object W with polarized light having a uniform polarization direction.

  According to the polarization illumination device 100 of the present embodiment, the polarizing element 16 for extracting polarized light is disposed at a position where light emitted from the plurality of light source units 14 can directly enter. Therefore, it is possible to arrange the polarizing element 16 at a position closest to the plurality of light source units 14, and to reduce the size of the polarizing element 16 as compared with the case where the polarizing element 16 is arranged after the concave mirror as in the prior art. Is possible.

  Moreover, according to the polarized illumination apparatus 100 of this embodiment, since the several light source part 14 is used in order to ensure the intensity | strength of ultraviolet light, rather than the case where one large light source part is used, it is per sheet. It is possible to reduce the size of the polarizing mirror 17.

  Further, according to the polarized illumination device 100 of the present embodiment, since the polarizing mirror 17 is used as the polarizing element 16, for example, a polarizing film made of an organic compound that is partially decomposed by ultraviolet light is used. In addition, it is possible to stably extract polarized light.

Second Embodiment
FIG. 6 is a plan view of the polarization illumination device 200 according to the second embodiment of the present invention. FIG. 7 is a front view of the polarization illumination device 200.
Unlike the polarization illumination device 100 that uses the reflected polarized light according to the first embodiment, the polarization illumination device 200 according to the second embodiment uses transmission polarized light by the polarizing plate 202 as a polarization element. In addition, a motor 204 for rotating the polarizing plate 202 is provided. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  As shown in FIGS. 6 and 7, the polarization illumination device 200 according to the second embodiment includes a plurality of light source units 14 and a polarizing plate 202 for extracting polarized light from the light emitted from the plurality of light source units 14. ing.

  Five light sources 14 are arranged in the horizontal direction and five in the vertical direction, and a total of 25 light sources 14 are arranged on the same plane. On the front side of the five light source units 14 arranged in the vertical direction, a louver-type polarizing plate 202 having an elongated shape in the vertical direction is installed one by one. In other words, a total of five polarizing plates 202 are installed on the front side of the total of 25 light source units 14 so as to be arranged substantially in parallel in the vertical direction.

  The five polarizing plates 202 are attached to the inside of a box-shaped frame 206 made of, for example, an aluminum alloy via a rotation shaft (not shown).

  A motor 204 is connected to the frame body 206, and the frame body 206 can be rotated by the motor 204. This motor 204 corresponds to the “rotating means” of the present invention.

  8 and 9 are a plan view and a front view of the polarization illumination apparatus 200 in a state after the polarizing plate 202 is rotated 90 degrees by the motor 204. FIG. As shown in FIGS. 8 and 9, by rotating the polarizing plate 202 by 90 degrees, the polarization direction of light transmitted through the polarizing plate 202 can be rotated by 90 degrees. Thereby, the polarization direction of the light irradiated to the irradiation object W can be rotated by 90 degrees.

  According to the polarization illumination device 200 of the second embodiment, the polarizing plate 202 can be rotated by the motor 204, and the polarization direction of the light applied to the irradiated object W can be rotated by 90 degrees. Thereby, for example, in order to widen the viewing angle of the liquid crystal panel display, “alignment division” in which the alignment direction of the alignment film is partially changed by dividing the inside of the sub-pixel of the pixel can be easily performed.

<Third Embodiment>
FIG. 10 is a partial plan view of the polarization illumination apparatus 300 according to the third embodiment of the present invention.
As illustrated in FIG. 10, the polarization illumination apparatus 300 according to the third embodiment includes a plurality of light source units 14 and two polarizing mirrors 302 for extracting polarized light from the light emitted from each of the plurality of light source units 14. , 304. The first polarizing mirror 302 is disposed on the front side of the light emitted from the plurality of light source units 14. The second polarizing mirror 304 is disposed on the front side of the light reflected by the first polarizing mirror 302. That is, the light emitted from the plurality of light source units 14 is reflected twice by the first polarizing mirror 302 and the second polarizing mirror 304 and then enters the incident surface 18 a of the fly-eye lens 18. It has become.

  According to the polarization illumination device 300 of the third embodiment, the light emitted from the plurality of light source units 14 can be reflected twice by the two polarizing mirrors 302 and 304. As a result, the ratio of S polarization to P polarization or the ratio of P polarization to S polarization can be made smaller than a predetermined value. As a result, it is possible to extract more purely polarized light from the light emitted from the plurality of light source units 14 and irradiate the irradiated object W.

  In addition, although the example which has arrange | positioned two polarizing mirrors facing each other was shown, the same effect can be acquired even when it is a case where three or more polarizing mirrors are arrange | positioned. The same effect can be obtained even when two or more polarizing plates are arranged substantially in parallel.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the above embodiment, an example in which an ultra-high pressure mercury lamp is used as the light emitting unit 10 has been described. However, other lamps can be used as long as ultraviolet rays can be irradiated.
(2) In the above embodiment, the polarization characteristic when the wavelength of the ultrahigh pressure mercury lamp is 313 nm has been described as an example. However, even when a wavelength such as 254 nm or 365 nm, which is another strong spectrum, is selected, it is applied to the polarizing plate. By changing the coating film design, a polarized illumination device having the same effect can be realized.
(3) In the above-described embodiment, an example in which a concave mirror is used as the parallel light conversion unit 20 has been described. However, other collimator lenses may be used.
(4) In the above embodiment, an example in which the motor 204 is used as the rotating means has been described. However, the polarizing plate 202 can also be rotated manually, for example.
(5) In the above-described embodiment, the example in which the object to be irradiated W is a substrate for a liquid crystal panel has been described. Can do.
(6) In the above-described embodiment, an example in which five light sources 14 in the vertical direction and five (25 in total) in the horizontal direction are arranged has been described. Good. For example, five light source sections 14 in the vertical direction and three in the horizontal direction (a total of 15) may be arranged.
(7) In the above embodiment, an example in which the louver-type polarizing mirror 17 or the polarizing plate 202 having an elongated shape in the vertical direction is installed one by one on the front side of the five light source units 14 arranged in the vertical direction. However, the present invention is not limited to such an embodiment. For example, a polarizing mirror or polarizing plate having a substantially square shape may be installed one by one on the front side of each of the plurality of light source units 14.

DESCRIPTION OF SYMBOLS 10 ... Light-emitting part 12 ... Reflective optical system 13 ... Reflective mirror 14 ... Light source part 16 ... Polarizing elements 17, 302, 304 ... Polarizing mirror 18 ... Fly eye lens 20 ... Parallel light conversion means 100, 200, 300 ... Polarized illumination apparatus 202 ... Polarizing plate 204 ... Motor (rotating means)
W: Irradiated object

Claims (4)

A plurality of light source units including a light emitting unit and a reflective optical system that reflects light emitted from the light emitting unit, a polarizing element that extracts polarized light from the light emitted from the plurality of light source units, and the polarizing element A polarization illumination device comprising: a fly-eye lens on which the polarized light is incident; and a parallel light conversion means for converting light emitted from the fly-eye lens into parallel light,
The reflective optical system comprises a reflecting mirror having a substantially parabolic cross section,
The polarizing element is composed of a polarizing plate or a polarizing mirror provided with a coating film that adds a polarizing function to a glass plate, and is disposed at a position where light emitted from the plurality of light source units can be directly incident. A polarized illuminating device characterized by that. The polarized illumination apparatus according to claim 1 , further comprising a rotating unit capable of rotating the polarizing element. The polarizing element comprises a plurality of polarizing mirrors,
Wherein the plurality of the light emitted from the light source unit, the polarization illumination device according to claim 1 or claim 2, characterized in that it is reflected multiple times by the plurality of polarizing mirror. The polarized illumination apparatus according to any one of claims 1 to 3 , wherein the irradiated object to be irradiated with polarized light is a processing target alignment film substrate for a liquid crystal panel.

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