JP2900896B2 - Polarizing element and lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing element useful for various displays, optical switches, optical isolators, optical filters, various optical measuring devices, etc., and more particularly to a polarization separating / combining element.

[0002]

2. Description of the Related Art Conventionally, when linearly polarized light is obtained from natural light emitted from an ordinary light source, a birefringent prism such as a Wollaston type or a lotion type or a unidirectionally stretched oriented film utilizing dichroism of light absorption is used. Has been used.

[0003]

However, birefringent prisms are not only very expensive due to the necessity of precision machining of a large single crystal, but also have a desirable shape or arrangement required for a specific application. Cannot be easily formed. In addition, the size of the obtained single crystal body is limited, which also has a problem that the range of use is significantly limited. On the other hand, the stretch-oriented film is made of an organic polymer material, so it is excellent in mass productivity and inexpensive, but because it utilizes dichroism of light absorption, the film itself absorbs a part of incident light. That is, the light transmittance is low.
Further, the film has a drawback that the film itself may cause self-destruction with respect to strong light due to a heat generation effect accompanying light absorption.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a compact and inexpensive polarizing element having essentially no light absorption.

[0005]

In order to solve the above-mentioned problems, a polarizing element according to the present invention is a polarizing element that converts incident light into light having a uniform polarization plane and emits the light. Separated into two types of polarized light components whose planes are orthogonal to each other,
Polarization separation means for emitting light in different directions, a phase difference layer for rotating the polarization plane, polarization conversion means selectively formed at a plurality of locations in the same plane, and an emission surface side of the polarization conversion means are arranged. Polarizing plate, and of the two types of polarized light components emitted from the polarization separating means, one light is guided to a portion where the phase difference layer is formed, and the other light is directed to the phase difference layer. Light-collecting means for guiding the light to the non-formed portion, wherein the light-collecting means forms one of the two types of polarized light components incident from different directions on the phase difference layer. A plurality of lens bodies that guide the other light to a portion where the phase difference layer is not formed, wherein the one light is emitted through the phase difference layer, and the other light is the other light. Emitted through the part where the retardation layer is not formed And wherein the door. Further, the lighting device of the present invention is a lighting device that converts incident light into light having a uniform polarization plane and irradiates the light, and separates the incident light into two kinds of polarization component lights whose polarization planes are orthogonal to each other. Then, polarization separating means for emitting light in different directions from each other, a phase difference layer for rotating the polarization plane, polarization converting means selectively formed at a plurality of locations in the same plane, and an emission surface side of the polarization converting means And one of the two kinds of polarized light components emitted from the polarization splitting means is guided to a portion where the retardation layer is formed, and the other light is directed to the polarized light component. Light condensing means for guiding the light to the portion where the retardation layer is not formed, wherein the light condensing means converts one of the two types of polarized light components incident from different directions from each other to the phase difference. To the portion where the layer is formed and direct the other light to the phase difference layer Comprising a plurality of lens body leading to made that is not part,
The one light is emitted through the phase difference layer, and the other light is emitted through a portion where the phase difference layer is not formed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on several embodiments (examples). However, the present invention is not limited to the following embodiments.

[0007] When natural light, which emits light normally, is incident on an optically anisotropic medium such as calcite or uniaxially oriented polymer, it has a vibrating surface corresponding to the optically anisotropic axis in the medium.
It is split into two light beams (ordinary light and extraordinary light). This phenomenon occurs because the refractive power of the medium differs between the two light axes.

FIG. 1 is a sectional view showing the structure of an embodiment of the polarizing element of the present invention. The operation of the following embodiment will be described with reference to FIG.

First, an incident light beam is separated into an ordinary light beam 103 and an extraordinary light beam 104 by a birefringent layer 102 made of an optically anisotropic material, and the light beams are temporarily shifted to different positions so as not to spatially overlap each other. The light is condensed using the lens 105. In this case, the polarization direction of the ordinary ray is parallel to the page, and the polarization direction of the extraordinary ray is perpendicular to the page. Next, if the polarization plane of one of the ordinary ray and the extraordinary ray is rotated (the extraordinary ray in FIG. 1) and the polarization plane of the other ray (the ordinary ray in FIG. 1) is used, the incident ray is absorbed. Instead, the light beam can be converted into a light beam 108 having a specific polarization direction (in FIG. 1, the vibration direction is the same as the ordinary ray in the plane of the paper).

(Example 1) Light incident on a birefringent layer 102 made of an optically anisotropic material is separated into a pair of linearly polarized light components (ordinary ray 103 and extraordinary ray 104) having mutually orthogonal polarization planes. . The separation angle of the two polarization components by the birefringent layer is determined by the birefringence ability of the material forming the birefringent layer and the shape of the birefringent layer (the angle of the taper provided below the layer). Therefore, it is important to select a material and determine the taper angle. To give an example, the birefringent layer is formed of a birefringent material having a refractive index of 1.5 and 2.0 for ordinary light and extraordinary light, respectively. The separation angle between the ordinary ray and the extraordinary ray is about 5.2 °. In this embodiment, this value is adopted.

As a material for forming the birefringent layer, any material can be used as long as it is a transparent material having birefringence such as an inorganic single crystal such as calcite or quartz, or a uniaxially oriented organic polymer.
When considering workability, the latter is superior. The organic polymer material can be formed or formed into various forms such as films, sheets, coatings, fibers and the like. An example of such a polymer substance is poly [2,2'-bis (trifluoromethyl)-, which is a kind of polyimide compound.
4,4'-biphenylene] -2 ", 2" -dimethoxy-
4,4 "-biphenylenedicarboxamide can be used.

The birefringent layer was obtained by unidirectionally stretching and orienting a sheet-like polymer substance and then press-molding. The ordinary light and the extraordinary light, whose polarization planes are orthogonal to each other, separated by the birefringent layer are respectively condensed by the lens body 105 and form focal points at different positions. This lens body may be formed using a usual optically isotropic material. Although there are various molding methods, a pressure molding method and an injection molding method are typical examples. Next, at the focal position of the extraordinary light kneading (or the focal position of the ordinary ray), a phase difference layer 106 of 2 is formed, and the extraordinary ray passes through the retardation layer, so that the polarization plane of the ray becomes 90 °. It was configured to turn. That is, at the output end of the polarizing element, the polarization directions of all the light beams are aligned in one direction.

The light transmittance of the conventional method using a polarizing plate is about 50% at the maximum, whereas the light transmittance of the method using the polarizing element of the present invention is almost 100%. The light passing through the focal point spreads at the same angle as that at the time of focusing. However, if the above configuration is realized with a small size to some extent (in this embodiment, the diameter of the focusing lens is 100 μm), the divergence of the light ray is not so significant. Rather, almost all of the incident light can be converted into outgoing light with a uniform polarization plane without light absorption.

Embodiment 2 FIG. 2 shows an application example of the polarizing element of Embodiment 1.
FIG. 3 is a configuration sectional view illustrating a polarization element configured by combining a polarization element and a polarization plate. Even if the polarizing element of the present invention is used alone, a light beam having a considerably uniform polarization plane can be obtained. However, as shown in FIG. By arranging the polarizing plates 201 in the same direction, it is possible to obtain emitted light with a very uniform polarization direction. When the polarizing element of the present invention is incorporated in an optical measuring instrument or the like, it is desirable to adopt the above configuration.

(Embodiment 3) FIG. 3 shows a schematic configuration in a case where a plurality of polarizing elements of Embodiment 2 are arranged in a plane perpendicular to the incident light beam. In this case, a lens array in which circular lenses are arranged on a plane in the same manner as in the second embodiment may be used. However, from the viewpoint of high light-collecting efficiency and ease of manufacture, lenticular lenses are arranged in a plane to form a lens array. Easy to use. By arranging a large number of polarizing elements in a two-dimensional plane, it can be applied to various displays having a large area (for example, a liquid crystal display) or various lighting devices.

[0016]

As described above, according to the polarizing element and the illuminating device of the present invention, almost all of the incident light can be converted into outgoing light having a uniform polarization plane with high efficiency. Unlike the conventional polarizing plate used for the same purpose, the polarizing element of the present invention has essentially no light absorption, so that even when a strong light is incident, it is stable without causing self-destruction due to heat generation. To work.

The polarizing element and the illuminating device of the present invention make use of the above-mentioned characteristics to make use of various displays requiring polarization, in particular, liquid crystal displays, optical isolators, optical switches, optical filters, and various components comprising them. A wide range of applications such as optical measurement equipment is possible.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of a polarizing element according to a first embodiment. FIG. 2 is a cross-sectional view illustrating a configuration of a polarizing element according to a second embodiment. FIG. 3 is a schematic configuration diagram of a polarizing element according to a third embodiment.

[Explanation of symbols]

101 ... incident light beam 102 ... birefringent layer 103 ... ordinary ray 104 ... extraordinary ray 105 ... lens layer 106 ... λ / 2 retardation layer 107 ... transparent aperture 108 ..Outgoing light flux 109 ・ ・ ・ Polarization direction of ordinary ray (parallel to paper) 110 ・ ・ ・ Polarization direction of extraordinary ray (perpendicular to paper) 111 ・ ・ ・ After passing through λ / 2 retardation layer Polarization direction of the light beam (parallel to the paper surface) 201: polarizing plate 202: polarization direction of the polarization plate (parallel to the paper surface) 301: birefringent layer 302: lens array layer 303 ・ ・ ・ λ / 2 retardation layer section 304 ・ ・ ・ Polarizer layer section

Continuation of the front page (56) References JP-A-1-265206 (JP, A) JP-A-60-63503 (JP, A) JP-A-61-90584 (JP, A) JP-A-58-36707 (JP) , U) Patent 2718057 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 5/30 G02B 19/00 G02B 27/28

Claims (2)

(57) [Claims] 1. A polarizing element that converts incident light into light having a uniform polarization plane and emits the light, wherein the incident light is separated into two types of polarization components whose polarization planes are orthogonal to each other. Polarization separation means for emitting light in different directions, a phase difference layer for rotating the polarization plane, polarization conversion means selectively formed at a plurality of locations in the same plane, and disposed on the emission surface side of the polarization conversion means A polarizing plate, of the two types of polarized light components emitted from the polarized light separating means, guides one light to a portion where the phase difference layer is formed, and directs the other light to the portion where the phase difference layer is formed. Light collecting means for guiding light to a portion that is not formed, wherein the light collecting means is configured such that one of the two types of polarized light components incident from different directions is formed on the phase difference layer. To the part where the other light is formed on the retardation layer A plurality of lens bodies for guiding to the non-existing portion, wherein the one light is emitted through the phase difference layer, and the other light is emitted through a portion where the phase difference layer is not formed. Polarizing element. 2. An illumination device for converting incident light into light having a uniform polarization plane and irradiating the light, wherein the incident light is separated into two kinds of polarization components of light whose polarization planes are orthogonal to each other. Polarization separation means for emitting light in different directions, a phase difference layer for rotating the polarization plane, polarization conversion means selectively formed at a plurality of locations in the same plane, and disposed on the emission surface side of the polarization conversion means A polarizing plate, of the two types of polarized light components emitted from the polarized light separating means, guides one light to a portion where the phase difference layer is formed, and directs the other light to the portion where the phase difference layer is formed. Light collecting means for guiding light to a portion that is not formed, wherein the light collecting means is configured such that one of the two types of polarized light components incident from different directions is formed on the phase difference layer. To the part where the other light is formed on the retardation layer A plurality of lens bodies for guiding to the non-existing portion, wherein the one light is emitted through the phase difference layer, and the other light is irradiated through a portion where the phase difference layer is not formed. Lighting equipment.