KR200473436Y1 - Wire grid polarizer, polarizing beam splitter and projection apparatus - Google Patents

Abstract

It is an object of the present invention to provide a polarizing beam splitter capable of realizing a compact projection apparatus having high utilization efficiency of light and a projection apparatus using the polarizing beam splitter. A polarization beam splitter (14) having a polarization splitting surface (141) that transmits a polarization component in a predetermined direction and reflects a polarization component in a direction substantially orthogonal to the predetermined direction, wherein the polarization splitting surface The polarized light separating surface 141 includes a curved surface. Further, the projection apparatus 1 is constituted by using the polarization beam splitter 14.

Description

TECHNICAL FIELD [0001] The present invention relates to a wire grid polarizer, a polarizing beam splitter,

The present invention relates to a wire grid polarizer, a polarizing beam splitter and a projection apparatus using the same.

In recent years, it is expected to mount a projection type image display apparatus (hereinafter referred to as a projection apparatus) in a portable apparatus using a liquid crystal display element, a DMD, or the like as a light bulb, and accordingly, the miniaturization of the optical module used in the projection apparatus Is required. The projection apparatus includes a light source such as an LED, a display device such as a light guide (for example, a light guide) for guiding light generated from a light source, a lens, a polarization beam splitter (hereinafter referred to as PBS) , Reflective liquid crystal display), a projection lens, and the like.

In the above-described projection apparatus for a portable apparatus, the display apparatus to be mounted is also required to be miniaturized. For example, a small display device may be employed with a diagonal length of 0.21 inches = about 5.3 mm. However, even if light emitted from a light source such as an LED is condensed by using a Fresnel lens, a light guide, a lens having a small F number (for example, a substantially hemispherical lens), or the like, . The light not incident on the display device is not used for projecting the image, so that there is a problem that the utilization efficiency of the light is greatly lowered.

There is known a method of efficiently collecting diffused light generated from an LED by using a light guide, a hemispherical lens or the like, and shaping light of a desired shape (see, for example, Patent Document 1). However, the illumination device composed of the light guide and the hemispherical lens has a plurality of light-converging points on the optical path from the hemispherical lens to the projection plane, and there is a problem that the unevenness of illumination is large and the uniformity of illumination is insufficient. Therefore, even if the projection apparatus is constructed using this illumination apparatus, irregularities in illumination occur in the projected image. By combining an aspherical lens with a hemispherical lens, it is possible to improve the unevenness of illumination, but the optical system becomes larger due to an increase in the number of lenses. In addition, such an optical system has a problem that the lens design is not easy.

Japanese Patent Application Laid-Open No. 2007-88377

The object of the present invention is to provide a polarizing beam splitter capable of realizing a compact projection apparatus having high utilization efficiency of light and a projection apparatus using the polarizing beam splitter.

The polarization beam splitter of the present invention is a polarization beam splitter having a polarization splitting surface that transmits a polarization component in a predetermined direction and reflects a polarization component in a direction substantially orthogonal to the predetermined direction, And the polarized light separating surface includes a curved surface so that light is condensed.

According to this configuration, since the polarization splitting surface of the polarizing beam splitter includes a curved surface, the polarized light separated light can be condensed. When such a polarizing beam splitter is used in a projection apparatus, it is possible to maintain the utilization efficiency of light at a high level, and at the same time to reduce the number of optical elements such as a lens and to reduce the size. Thus, the above-described configuration provides a polarizing beam splitter capable of realizing a compact projection apparatus having high utilization efficiency of light.

In the polarizing beam splitter of the present invention, the polarized light separating surface may have diffuse reflectivity.

In the polarizing beam splitter of the present invention, the polarized light separating surface may be constituted by a wire grid polarizer. According to this configuration, since a wire grid polarizer which is less prone to deteriorate in optical characteristics even in a curved surface is used, a polarizing beam splitter of good optical characteristics can be obtained.

In the polarizing beam splitter of the present invention, the thickness of the wire grid polarizer may be 50 탆 or less.

The projection apparatus of the present invention includes a light source, a light guide for guiding light from the light source to form a light beam, a polarizing element for correcting the shape of the light beam from the light guide, And a reflection type display device in which the polarized beam reflected by the polarized beam splitter and the condensed polarized beam is incident thereon.

According to this configuration, since the polarization splitting surface of the polarizing beam splitter includes a curved surface, the polarized light separated light can be condensed. Thus, by using such a polarizing beam splitter in a projection apparatus, a projection apparatus in which the utilization efficiency of light is kept high and the number of optical elements such as lenses is reduced is provided. As a result, even if an element for correcting the shape of the light beam is disposed so as to avoid unevenness in illumination, it can be sufficiently miniaturized.

In the projection apparatus of the present invention, a light guide may be provided between the polarizing beam splitter and the reflective display device to form a light beam having a shape substantially approximate to the light incidence plane of the reflective display device. According to this configuration, a projection apparatus having a higher utilization efficiency of light is provided.

In the projection apparatus of the present invention, a lens for correcting the shape of the light beam may be provided between the light guide and the reflective display device.

In the projection apparatus of the present invention, the polarizing element may be a wire grid polarizer having diffuse reflectivity and positive transparency. Further, in the projection apparatus of the present invention, the polarizing element may be a wire grid polarizer having diffuse reflectivity and diffuse permeability. Further, in the projection apparatus of the present invention, the polarizing element may be a resin multilayer birefringent polymer polarizer having diffuse reflectivity and diffusive permeability.

In the projection apparatus of the present invention, the polarizing element may be the polarizing beam splitter.

According to the present invention, it is possible to provide a polarizing beam splitter capable of realizing a small projection apparatus having high utilization efficiency of light and a projection apparatus using the polarizing beam splitter.

1 is a schematic diagram showing a configuration of a projection apparatus according to a first embodiment;
2A and 2B are schematic diagrams showing the configuration of a polarization beam splitter used in a projection apparatus.
3 is a schematic diagram showing a configuration of a projection apparatus according to a comparative example.
4 is a schematic diagram showing a configuration of a projection apparatus according to a second embodiment;
5 is a schematic diagram showing a configuration of a projection apparatus according to a third embodiment;
6 is a schematic diagram showing a configuration of a projection apparatus according to a fourth embodiment;
7A and 7B are diagrams showing a simulation model and a simulation result for confirming the distribution of the irradiance distribution of light emitted to the reflective display device in the projection apparatus.
8A to 8C are diagrams showing simulation models and simulation results for confirming the effect of the polarizing film having diffusibility.

The inventors have found that by configuring the polarization splitting surface of a polarization beam splitter to include a curved surface, the polarization beam splitter can be given the function of a concave mirror (or a convex mirror). Further, by using such a polarizing beam splitter, it has been found that a compact projection apparatus with high utilization efficiency of light can be realized. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(First Embodiment)

1 is a schematic diagram showing the configuration and optical path of a projection apparatus using a polarization beam splitter according to the present embodiment. The projection apparatus 1 shown in Fig. 1 includes a light source 11 for emitting light used for projection, a light guide (light guide) 12 for guiding light from the light source 11 to form a light beam, A polarizing film (polarizing element) 13 showing diffusing property (scattering property) for correcting the shape of the light beam from the light guide 12, and a polarization separating surface 13 for polarizing and separating the light beam from the polarizing film 13 A polarizing beam splitter 14 composed of this curved surface, a light guide 15 for shaping the polarized beam separated by the PBS 14, and a polarizing beam splitter And a projection lens 17 which is reflected by the reflection type display device 16 and projects a polarized beam transmitted through the PBS 14. [

The light source 11 has a substantially rectangular parallelepiped shape and its light emitting surface is disposed so as to be close to the light incoming surface of the light guide 12. [ By thus bringing the light emitting surface of the light source 11 and the light incoming surface of the light guide 12 close to each other, the light emission in the light source 11 can be efficiently used. The light source 11 is, for example, an LED capable of emitting monochromatic light. An LED that emits white light and a filter may be used in combination. The light source 11 may be in close contact with the light guide 12 by adhesion or the like. The shape of the light source 11 may be a columnar shape or the like.

The light guide 12 is disposed on the light emitting surface side of the light source 11 in order to form light from the light source 11 and irradiate the light in the forward direction (the right direction in FIG. 1). The diffusing angle of light emission from the high-luminance type LED is about 120 degrees (one side of 60 degrees). When the light source 11 having such a wide diffusion angle is used, the light emitted from the light source is diffused in a conical shape, and can not be used effectively in this state. Therefore, the light guide 12 is used to condense the diffused light and irradiate it forward. The light incident on the light guide 12 from the light source 11 propagates the inner surface of the light guide 12 by the total reflection, so that the diffusion loss of light can be reduced.

It is preferable that the side surface of the light guide 12 be inclined so that the area of the light exiting surface becomes larger from the area of the light incidence surface in order to reduce the angle of diffusion of the light emitted from the light exiting surface of the light guide 12. [ When the light guide 12 is a hexahedron, it is preferable that at least two surfaces are inclined surfaces, and it is more preferable that the four surfaces are inclined surfaces (that is, the light guide 12 is a quadrangular prism). The angle (inclination angle) of the inclined plane may be set for each inclined plane, or may have a curvature such that the inclined plane is curved. The light guide 12 is not limited to a hexahedron, but may be a truncated cone or the like. Thus, the shape of the light guide 12 can be set in accordance with the illuminance distribution of the light to be projected.

It is preferable that a reflective surface composed of a metal such as aluminum having light reflectivity is provided on the side surface of the light guide 12. [ By providing such a reflecting surface, light leaked outside the light guide 12 beyond the critical angle of total reflection can be emitted from the light exit surface of the light guide 12 again. As a result, the utilization efficiency of light can be improved. As such a reflection surface, a material formed on a birefringent base material such as PET resin may be used.

The parameters of the light guide 12 such as the length of the light guide 12, the inclination angle of the side surface, the area of the light incidence surface, and the area of the light exiting surface can be set in accordance with the size of the projection device 1 or the like. For example, when the projection apparatus 1 is small, the light emitting surface of the LED used as the light source 11 has an area of 1 to 2 mm 2, so that the size of the light entrance surface of the light guide 12 is 1 to 2 ≪ / RTI > In consideration of utilization efficiency of light, it is preferable that the length of the light guide 12 is at least twice the length of the short side of the light incidence surface, and the inclination angle is 3 to 15 degrees (the reference is an axis perpendicular to the light incidence surface). The area of the light exit surface of the light guide 12 is determined by the inclination angle of the length or side surface of the light guide 12. [ The material of the light guide 12 is not particularly limited as long as it is a material having high transparency such as glass or resin, and can be selected in consideration of workability and cost.

The polarizing film 13 is disposed on the light output surface side of the light guide 12 so that the degree of polarization of the light emitted from the light guide 12 can be matched to a predetermined degree and the shape of the light beam can be corrected. When the light emitted from the light guide 12 is used as it is, or when the light is condensed by a lens or the like, a large unevenness may occur in the illuminance distribution of the projected image. In order to solve this problem, a polarizing film 13 having diffusibility (scattering) is used. The polarizing film 13 may not be a film insofar as it is a polarizing element having diffusibility, and may be, for example, PBS or the like.

As the polarizing film 13 having diffusibility, a wire grid polarizer in which fine concavities and convexities of several micrometers to several hundreds of micrometers are provided on the surface of a resin substrate on which a metal wire grid is formed can be used. The wire grid polarizer having such a structure has diffuse transmittance and diffuse reflectivity. It is possible to impart an arbitrary fine pattern by a heating press or the like in a manufacturing process, and it is possible to easily control the diffusion permeability, the diffuse reflectivity, and the directivity. For example, as a wire grid polarizer, fine irregularities having a pitch of 80 to 130 nm are formed on a transparent resin film base material by UV resin or the like, and a metal such as aluminum is deposited on one surface of the irregular shape do. It is also possible to use a wire grid polarizer in which desired stretching is performed in advance on the resin substrate and concavo-convex is formed by shrinkage by heating the resin substrate. This wire grid polarizer can freely set the diffusibility by controlling the uneven shape by controlling the heating temperature, the draw ratio, and the like.

The diffusivity of the wire grid polarizer can be set by controlling the concavo-convex shape. It is also possible to have a directivity so as to be efficiently illuminated on the reflective display device 16. In order to reduce the diffusion loss to the outside of the optical path, it is preferable that the diffusibility is not too high (has non-diffusion property). For example, the diffusion angle is preferably 30 degrees or less, more preferably 20 degrees or less, and still more preferably 5 to 10 degrees. The following table shows the relationship between the diffusion angle and the characteristics of the illumination light. Further, the diffusivity may be either an even diffusion or an anisotropic diffusion, and it can be designed from the required illumination efficiency, degree of accuracy, and the like. Further, by controlling the diffusibility in the vertical direction and the horizontal direction in accordance with the shape (aspect ratio) of the reflective display device 16 or the like, it is possible to provide the reflective display device 16 with a high degree of uniformity, have. Such control is preferably performed by, for example, increasing (decreasing) the diffusing angle on the longer side when the aspect ratio of the reflective display device 16 is 10: 7. As described above, the diffusion angle of the wire grid polarizer can be set in accordance with the optical design of the projection apparatus 1.

Instead of the wire grid polarizer having the above-described diffusion transmittance and diffuse reflectivity, a polarizing element having diffuse reflectivity and positive transparency (transmissivity with no diffusivity) may be used. Such a polarizing element is obtained by bonding both sides of a wire grid polarizer having diffusion transmittance and diffuse reflectivity to a rectangular prism or a resin film and integrating them. Adhesion with a rectangular prism or a resin film can be performed using an adhesive or the like. When the wire grid polarizer is adhered to a right angle prism or the like by an adhesive or the like, the reflecting surface exhibits diffusibility, but since the wire grid polarizer is sufficiently thin, the diffusibility of the transmitted light is extremely low. That is, substantially no transmitted light is diffused. As a result, the transmitted light is not diffused and the reflected light is diffused. The diffusion angle of the transmitted light is preferably 10 degrees or less, more preferably 0 to 5 degrees, and the diffusion angle of the reflected light is preferably 30 degrees or less, more preferably 30 degrees or less, Is 20 degrees or less, more preferably 5 to 15 degrees.

The position of the polarizing film 13 is not particularly limited as long as it is the optical path from the light source 11 to the PBS 14. [ Also, as the polarizing film 13, a reflection type polarizer in which a resin layer having a different refractive index is multilayered, for example, DBEF manufactured by 3M, may be used. In addition, when sufficient polarizability and sufficient diffusibility can be obtained by the PBS 14, the polarizing film 13 may be omitted.

The PBS 14 is disposed on the back surface side (opposite to the light guide 12) of the polarizing film so that the light from the polarizing film 13 can be polarized and separated. The PBS 14 is configured such that the polarization splitting surface 141 includes a curved surface, and splits the incident light and condenses the light reflected on the polarization splitting surface 141. [ By using the PBS 14 in the projection apparatus 1, it becomes possible to keep the utilization efficiency of light high and reduce the number of optical elements such as lenses. That is, by using the PBS 14, it is possible to realize a compact projection apparatus having a high utilization efficiency of light.

2A and 2B are schematic diagrams showing the configuration of the PBS 14 and optical paths. As shown in Fig. 2A, in the PBS 14a, the polarization splitting surface 141a is formed in a substantially circular arc shape, and one surface A on the reflection side constitutes a concave mirror. Thus, the light of one polarized light reflected by the polarized light separating surface 141a is condensed on the light-exiting surface 142a side of the reflected light. The other polarized light passes through the polarized light separating surface 141a and is not substantially diffused but exits from the light exiting surface 143a of the transmitted light. The degree of condensation of the reflected light can be changed by the radius of curvature of the polarization splitting surface 141a. For example, by reducing the radius of curvature to some extent, it is possible to increase the degree of condensation of reflected light.

Like the PBS 14b shown in Fig. 2B, the polarization splitting surface may be composed of the curved surface 141b and the flat surface 141c. In Fig. 2B, a curved surface 141b is arranged at a central portion of the plane 141c, and the light reflected by the curved surface 141b is condensed. 2B, the light of one polarized light reflected on the polarized light separating surface is condensed on the light output surface 142b side of the reflected light and the light of the other polarized light transmitted through the polarized light separating surface 141b is substantially And is emitted from the light exiting surface 143b of the transmitted light. Since the light reflected on the curved surface 141b is condensed and the light reflected on the plane 141c is not condensed, the degree of condensation can be changed by controlling the areas of the curved surface 141b and the flat surface 141c.

The shape of the light exiting surface 142 of the reflected light of the PBS 14 is preferably similar to the shape of the light incidence surface of the reflective display device 16. [ It is also preferable that the PBS 14 is sufficiently small. Thus, by reducing the size of the PBS 14 and making its shape correspond to the shape of the reflective display device 16, the utilization efficiency of light in the projection apparatus 1 can be increased and the illuminance can be increased.

As the PBS 14, a material having high transparency such as glass is used. For example, as the PBS 14, two orthogonal prisms may be used. As the polarization separation surface 141 of the PBS 14, for example, the wire grid polarizer described above can be used. Since the wire grid polarizer is constituted by using a resin base material, it is easy to form a curved surface. Further, since the wire grid polarizer is not likely to deteriorate in optical characteristics even when it is bonded to a curved surface, the PBS 14 having good optical characteristics can be obtained by using this. From the viewpoint of shape conformability to the curved surface, the thickness of the wire grid polarizer is preferably 50 占 퐉 or less, more preferably 40 占 퐉 or less.

It is preferable that the PBS 14 has diffuse (scattering) reflectivity. In this case, since the polarizing film 13 can be omitted, the projection apparatus 1 can be further downsized and the cost of parts can be reduced. The use of the PBS 14 allows sufficient condensation of the polarized light reflected by the polarized light separating surface 141 so that the light guide 15 disposed on the light exiting surface 142 side of the reflected light of the PBS 14, Can be omitted.

The light guide 15 is disposed on the light-exiting surface 142 side of the reflected light of the PBS 14 so that light can be formed in accordance with the shape of the light-entering surface of the reflective display device 16. For example, when the diameter of the light beam on the light incidence surface of the PBS 14 is about 6 mm to 8 mm, it is necessary to be large enough to accommodate illumination light of at least 6 mm in diameter as the PBS 14. When the PBS 14 is formed into a cube shape having a length of approximately 6 mm, the area of the light output surface 142 of the reflected light is 36 mm 2. When the reflective display device 16 having a diagonal 0.21 inches and an aspect ratio of 10: 7 is used, the size of the light incidence surface is about 4.3 mm in width and 3.2 mm in length, and therefore the area thereof is about 14 mm 2. In this case, the light utilization efficiency is about 38.8% (14/36 = 0.388). Even in such a case, by using the light guide 15, the utilization efficiency of light is greatly improved and the reflective display device 14 can be illuminated with almost no loss. Since the light guide 15 can be configured similarly to the light guide 12, the details thereof will be omitted.

The reflective display device 16 is disposed on the light-outgoing surface side of the light guide 15. [ As the reflective display device 16, a reflective liquid crystal display device (LCD, LCOS) is typically used. The light reflected by the reflection type display device 16 is transmitted through the polarized light separation surface 141 of the PBS 14 to be opposite to the light exit surface 142 of the PBS 14 And is projected by the projection lens 17 arranged on the surface side. The projection lens 17 may be composed of a single lens or a combination of a plurality of lenses.

In the projection apparatus 1 configured as described above, the light from the light source 11 is formed into a beam shape through the light guide 12. After the beam shape is corrected in the polarizing film 13, the PBS 14 ). In the PBS 14, one polarized component of the beam is reflected by the polarization splitting surface 141 and exits from the light exiting surface 142 to be condensed. And the other polarization component passes through the polarization splitting surface 141. One of the beams of polarized light emerging from the light exiting surface 142 is arranged in the shape of the reflective display device 16 by the light guide 15 and enters the reflective display device 16. The beam incident on the reflection type display device 16 is reflected by the display image of the reflection type display device 16 and is projected onto a screen or the like not shown via the polarization separation surface 14 and the projection lens 17. [

In the projection apparatus 1 having such a configuration, since the polarization splitting surface 141 of the PBS 14 includes a curved surface, it is possible to condense the polarized light separated light. The projection apparatus 1 using the PBS 14 can maintain the utilization efficiency of light at a high level without adding additional optical elements. 3) (the light source 31, the light guide 32, the condenser lens 33, the polarizing film 34, and the polarizing film 34) shown in Fig. Sufficient performance can be obtained without using the condenser lens 33 like the PBS 35, the light guide 36, the reflective display device 37, and the projection lens 38). In other words, the number of optical elements such as a lens, a light guide, and a polarizing element can be reduced by the PBS 14 to be miniaturized. As a result, even if an optical element such as a polarizing film 13 for correcting the shape of the light beam is arranged so as to avoid unevenness in illumination, it can be sufficiently miniaturized. As described above, according to the present embodiment, it is possible to realize a compact projection apparatus 1 that has no illuminance unevenness and high light utilization efficiency.

The present embodiment can be implemented by appropriately combining with the configuration shown in the other embodiments.

(Second Embodiment)

In the present embodiment, a modified example of the projection apparatus shown in Fig. 1 will be described. 4 is a schematic diagram showing the configuration and optical path of the projection apparatus according to the present embodiment. 4 includes a light source 11 that emits light used for projection, a Fresnel lens (light guide) 21 that forms a light beam from the light of the light source 11, A polarizing film (polarizing element) 13 which exhibits diffusibility for correcting the shape of the light beam from the Nell lens 21; and a polarization separating surface for polarizing light beams from the polarizing film 13, A light guide 15 for shaping a polarized beam separated in the PBS 14 and a reflection type display apparatus in which a polarized beam from the light guide 15 is incident (a polarized beam splitter) And a projection lens 17 that is reflected by the reflective display device 16 and projects a polarized beam transmitted through the PBS 14. The projection lens 17 is a projection type display device. In other words, the light guide 12 of the projection apparatus 1 is changed to the Fresnel lens 21. Hereinafter, differences from the first embodiment will be mainly described, and repeated description will be omitted. The same reference numerals are used for the same components as those of the first embodiment described above.

Like the light guide 12, the Fresnel lens 21 forms light from the light source 11 and irradiates the light in a forward direction (right direction in FIG. 1). For this reason, the Fresnel lens 12 is disposed on the light-emitting surface side of the light source 11. Further, the Fresnel lens 21 is arranged close to the light source so that light from the LED is sufficiently incident. The diffused light generated from the light source 11 by the Fresnel lens 21 is incident on the polarizing film 13 in substantially parallel light. The Fresnel lens 21 can be downsized as compared with the light guide 12 and the ordinary lens and the like. Therefore, the projection apparatus 1a using the Fresnel lens 21 according to the present embodiment is provided with the light guide 12, It is possible to further reduce the size as compared with the projection apparatus 1 using the projection optical system.

The light from the light source 11 becomes substantially parallel light through the Fresnel lens 21 and the beam shape is corrected in the polarizing film 13, I will join. In the PBS 14, one polarized component of the beam is reflected by the polarization splitting surface 141 and exits from the light exiting surface 142 to be condensed. And the other polarization component passes through the polarization splitting surface 141. One of the beams of polarized light emerging from the light exiting surface 142 is arranged in the shape of the reflective display device 16 by the light guide 15 and enters the reflective display device 16. The beam incident on the reflective display device 16 is reflected by the display image of the reflective display device 16 and passes through the light guide 15, the polarization separation surface 14 and the projection lens 17 Screen or the like.

The present embodiment can be implemented by appropriately combining with the configuration shown in the other embodiments.

(Third Embodiment)

In this embodiment, another modification of the projection apparatus shown in Fig. 1 will be described. 5 is a schematic diagram showing the configuration and optical path of the projection apparatus according to the present embodiment. 5 includes a light source 11 for emitting light used for projection, a light guide (light guide) 12 for guiding light from the light source 11 to form a light beam, A PBS (polarizing element) 22 showing diffusibility (scattering) for correcting the shape of the light beam from the light guide 12, a condenser lens 23 for condensing the light beam from the PBS 22, A PBS (polarized beam splitter) 14 having a polarized light separation surface for polarizing and separating the light beam from the condenser lens 23 and including a curved surface, a light guide (not shown) for shaping the polarized beam separated in the PBS 14, A reflection type display device 16 in which a polarized beam from the light guide 15 is incident and a projection type optical system 15 which is reflected by the reflection type display device 16 and projects a polarized beam transmitted through the PBS 14, And a lens 17. That is, the polarizing film 13 of the projection apparatus 1 is changed to the PBS 22, and a condenser lens 23 is added between the PBS 22 and the PBS 14. [ Hereinafter, differences from the first embodiment will be mainly described, and repeated description will be omitted. The same reference numerals are used for the same components as those of the first embodiment described above.

The PBS 22 is disposed such that the light incidence surface faces the light exiting surface of the light guide 12 in order to match the degree of polarization of the light emitted from the light guide 12 to a predetermined degree and correct the shape of the light. Further, in order to correct the shape of the light, the PBS 22 has diffusibility. The polarized light separating surface 221 of the PBS 22 preferably includes a curved surface so that the polarized light is collected, but the polarized light separating surface 221 may not include a curved surface. As the PBS 22, for example, a structure similar to that of the PBS 14 can be used. It is preferable that the light that is transmitted without reflecting the polarization splitting surface 221 of the PBS 22 is absorbed on the light emission surface side of the transmitted light of the PBS 221. By this, unnecessary light in the optical path can be reduced, and the contrast of the projection apparatus 1b can be improved.

The condensing lens 23 is disposed such that the light incidence surface faces the light exiting surface of the reflected light of the PBS 22 in order to condense the light beam from the PBS 22. [ The condenser lens 23 is, for example, a hemispherical convex lens. Further, when the PBS 22 is configured to be capable of focusing, the focusing lens 23 can be omitted.

In the projection apparatus 1b, the light from the light source 11 is made into a beam shape through the light guide 12, and enters the PBS 22. In the PBS 22, one polarized component of the beam is reflected on the polarization splitting surface 221 and is output. And the other polarization component passes through the polarization separation surface 221. The light reflected by the PBS 22 is condensed by the condenser lens 23, and is then incident on the PBS 14. In the PBS 14, one polarized component of the beam is reflected by the polarization splitting surface 141 and exits from the light exiting surface 142 to be condensed. And the other polarization component passes through the polarization splitting surface 141. One of the beams of polarized light emerging from the light exiting surface 142 is arranged in the shape of the reflective display device 16 by the light guide 15 and enters the reflective display device 16. The beam incident on the reflective display device 16 is reflected by the display image of the reflective display device 16 and passes through the light guide 15, the polarization separation surface 14 and the projection lens 17 Screen or the like.

The present embodiment can be implemented by appropriately combining with the configuration shown in the other embodiments.

(Fourth Embodiment)

In this embodiment, another modification of the projection apparatus shown in Fig. 1 will be described. Fig. 6 is a schematic diagram showing the configuration and optical path of the projection apparatus according to the present embodiment. The projection apparatus 1c shown in Fig. 6 includes a light source 11 for emitting light used for projection, a light guide (light guide) 12 for guiding light from the light source 11 to form a light beam, A PBS (polarizing element) 24 for diffusing (scattering) and condensing properties for correcting the shape of the light beam from the light guide 12, a polarizing beam splitter 24 for splitting the light beam from the PBS 24, A polarizing beam splitter 14 composed of this curved surface, a light guide 15 for shaping the polarized beam separated in the PBS 14, and a polarizing beam splitter 15 for correcting the polarized beam from the light guide 15 A reflection type display device 16 on which the light from the correction lens 25 is incident and a polarized beam reflected on the reflection type display device 16 and projected through the PBS 14 are projected And a projection lens 17. That is, the polarizing film 13 of the projection apparatus 1 is changed to the PBS 24, and the correction lens 25 is added between the light guide 15 and the reflective display device 16. Hereinafter, differences from the first embodiment will be mainly described, and repeated description will be omitted. The same reference numerals are used for the same components as those of the first embodiment described above.

The PBS 24 is disposed so that the light incidence surface faces the light exiting surface of the light guide 12 in order to adjust the degree of polarization of the light emitted from the light guide 12 to a predetermined degree and to correct the shape of the light and concentrate the light . In order to correct the shape of the light, the PBS 24 has diffusibility. In order to condense the polarized light, the polarization separation surface 241 of the PBS 24 includes a curved surface. As described above, the PBS 24 has a condensing function, so that the condenser lens can be omitted. It is preferable that the PBS 24 is arranged close to the PBS 14. The PBS 24 may be bonded to the PBS 14. As the PBS 24, a structure similar to that of the PBS 14 can be used. It is preferable that the polarized light that is transmitted without reflecting the polarized light separation surface 241 of the PBS 24 is absorbed on the light output surface side of the transmitted light of the PBS 241. Thus, unnecessary light in the optical path can be reduced, and the contrast of the projection apparatus 1c can be improved.

The correction lens 25 is provided so as to face the light exit surface of the reflected light of the PBS 22 so as to correct the light beam from the light guide 15 and to enter the reflection type display device 16, And the light surface is disposed so as to face the light incidence surface of the reflective display device 16.

In the projection apparatus 1c, the light from the light source 11 is made into a beam shape through the light guide 12, and is incident on the PBS 24. In the PBS 24, one polarized light component of the beam is reflected on the polarization splitting surface 241 and is output and condensed. And the other polarization component passes through the polarization splitting surface 241. The light reflected by the PBS 24 enters the PBS 14. In the PBS 14, one polarized component of the beam is reflected by the polarization splitting surface 141 and exits from the light exiting surface 142 to be condensed. And the other polarization component passes through the polarization splitting surface 141. The beam of one polarization direction emitted from the light exiting surface 142 is aligned in the shape of the reflective display device 16 by the light guide 15 and the correction lens 25 and is incident on the reflective display device 16 do. The beam incident on the reflection type display device 16 is reflected by the display image of the reflection type display device 16 and is reflected by the correction lens 25, the light guide 15, the polarization separation surface 14, and the projection lens 17 To a screen (not shown) or the like.

Since the projection device 1c having such a configuration can integrate the light guide 12, the PBS 24, the PBS 14, the light guide 15, the correction lens 25, and the like, It is possible to reduce the interface reflection of the light and the diffusion loss between the light and the light, and to further improve the utilization efficiency of light.

The present embodiment can be implemented by appropriately combining with the configuration shown in the other embodiments.

Next, a simulation result for confirming the effect of the design will be described.

Figs. 7A and 7B are diagrams showing simulation models and simulation results for confirming the distribution of the radiation intensity of light emitted to the reflective display device in the projection apparatus. Fig. 7A is a view showing a simulation model (which corresponds to a part of the optical system of the projection apparatus 1c in Fig. 6) composed of the light source 501, the light guide 502, the PBS 503, the PBS 504 and the light guide 505 FIG. 7B shows the distribution of radiation intensity on the light-outgoing surface 506 of the light guide 505. FIG. In Fig. 7A, the polarized light separation surface of the PBS 503 is a curved surface with a curvature radius of 20 mm, and has diffusion (scattering) reflectivity. The polarized light separation surface of the PBS 504 has a curved surface with a radius of curvature of 22 mm. From FIG. 7B, it can be seen that a radiation intensity distribution with high homogeneity can be realized by the projection apparatus according to the embodiment.

8A to 8C are diagrams showing a simulation model and a simulation result for confirming the effect of the polarizing film (corresponding to the polarizing film 13 in the embodiment) having diffusibility (scattering). 8A shows a simulation model composed of a light source 511, a light guide 512, a condenser lens 513, a polarizing film 514 and a screen 515. Fig. 8B shows a simulation model composed of a polarizing film 514 FIG. 8C shows the distribution of the irradiance distribution on the screen 515 when the polarizing film 514 has no diffusibility. FIG. 8B and 8C, it can be seen that when the polarizing film 514 is provided with diffusibility, the unevenness of the radiation illuminance can be largely reduced.

As described above, according to the present invention, since the polarized light separation surface of the PBS includes a curved surface, the polarized light separated light can be condensed. Such a projection apparatus using PBS can maintain the utilization efficiency of light at a high level without adding any other optical element. In addition, sufficient performance can be obtained without using a condenser lens due to the light converging property of the PBS. That is, the number of optical elements such as a lens, a light guide, and a polarizing element can be reduced by the PBS, and the projection apparatus can be downsized. As a result, even if a polarizing element for correcting the shape of the light beam is disposed so as to avoid unevenness in illumination, it can be sufficiently miniaturized. As described above, according to the present invention, it is possible to provide a PBS capable of realizing a compact projection apparatus having high utilization efficiency of light. Further, it is possible to provide a compact projection apparatus which has no illuminance unevenness and high light utilization efficiency.

Note that the present invention is not limited to the description of the above embodiment, but can be appropriately changed in a form in which the effect is exhibited. For example, DMD, DLP, or the like may be applied to the reflective display device in addition to the liquid crystal display device.

It is also possible to appropriately change the size, shape, and the like of the structure shown in the accompanying drawings within the scope of exhibiting the design effect. Other modifications may be made without departing from the scope of the present invention.

The polarizing beam splitter and the projection apparatus of the present invention are suitably used for a small portable apparatus such as a portable computer or a portable telephone.

1, 1a, 1b, 1c, 3: projection device
11, 31: Light source
12, 15, 32, 36: Light guide
13: polarizing film
14, 14a, 14b, 22, 24, 35: PBS
16, 37: reflective display device
17, 38: projection lens
21: Fresnel lens
23, 33: condensing lens
25: Correction lens

Claims (8)

A prism or a resin film is bonded to both surfaces of a polarizing element having diffuse reflectivity and diffuse angle of reflection light of 5 to 30 degrees and diffusion angle of transmitted light of 0 to 5 degrees and having positive transmissivity,
Wherein the polarizing element is formed by a wire grid polarizer in which fine irregularities are provided on a surface of a resin substrate on which a metal wire grid is formed. And a polarized light separating surface that transmits a polarized component in a predetermined direction and reflects a polarized component in a direction substantially orthogonal to the predetermined direction,
Characterized in that the polarized light separating surface is constituted by the wire grid polarizer according to claim 1, wherein the polarized light separating surface includes a curved surface so that light reflected on the polarized light separating surface is condensed. The polarizing beam splitter according to claim 2, wherein the thickness of the wire grid polarizer is 50 탆 or less. A light source,
A light guide for guiding light from the light source to form a light beam,
A polarizing element for correcting the shape of the light beam from the light guide,
A polarizing beam splitter according to claim 2 for polarization-splitting a light beam from the polarizing element;
And a reflection type display device which is reflected by the polarization beam splitter and into which the condensed polarized beam is incident. 5. The projection display apparatus according to claim 4, further comprising a light guide for forming a light beam between the polarizing beam splitter and the reflective display device, the light guide having a shape substantially approximate to the light entrance surface of the reflective display device . The projection apparatus according to claim 5, further comprising a lens between the light guide and the reflective display device for correcting the shape of the light beam. delete delete

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