JP2010197783A - Screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost, simply constituted screen which can be easily made large in size, and is configured to obtain bright, high-contrast images. <P>SOLUTION: The screen includes: a plurality of structures 13; a light-transmissive transmission layer 14; and a light-reflective reflection part 15. The structure 13 is constituted of an isorefractive material in which a refractive index with respect to first polarized light having a first polarizing direction is nearly equal to that of second polarized light having a second polarization direction vertical to the first polarization direction. The transmission layer 14 is constituted of a birefringent material in which a refractive index with respect to the first polarized light and a refractive index with respect to the second polarized light are different from each other. The refractive index of the structure 13 with respect to the first polarized light is made smaller than that of the transmission layer 14 with respect to the first polarized light, and a difference between the refractive index of the transmission layer 14 with respect to the first polarized light and the refractive index of the structure 13 with respect to the first polarized light is made larger than a difference between the refractive index of the transmission layer 14 with respect to the second polarized light and the refractive index of the structure 13 with respect to the second polarized light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technology for a screen, and more particularly, a screen that displays an image by reflecting light according to an image signal.

  A so-called front projection type projector is used in combination with a reflection type screen that reflects projection light. In an environment where external light such as illumination light from room lighting exists, the external light reflected by the screen together with the projection light travels in the direction of the observer, which may reduce the contrast of the image. For example, Patent Document 1 proposes a technique using a light absorbing layer for absorbing external light and improving image contrast. Patent Document 2 proposes a technique for improving the contrast of an image by providing a pattern of a reflection layer and a light absorption layer, ensuring white image luminance by the reflection layer, and ensuring black image luminance by the light absorption layer. ing. Patent Document 3 proposes a technique for improving brightness and contrast by selectively reflecting light in a specific wavelength region possessed by projection light and utilizing a difference in light beam angle between external light and projection light. Has been. Patent Document 4 proposes a technique for improving contrast by using a polarizing plate that transmits a specific polarization component projected from a liquid crystal projector.

JP-A-6-75302 JP 2005-121964 A JP 2005-115243 A Japanese Patent Laid-Open No. 10-3125

  When the reflectance is suppressed by the light absorption layer, the reflectance of not only the external light but also the projected light is lowered, and the luminance of the image is lowered. In the conventional technique using the difference in the light beam angle on the screen, a fine structure such as a louver or a prism is provided. It is difficult to form a fine structure for the entire screen, and the structure becomes complicated, resulting in high costs and an increase in the size of the screen. Also, in the case of using a polarizing plate, it is very difficult to form a polarizing plate having an area corresponding to the entire screen, and a plurality of polarizing plates are bonded together, which increases the cost. is there. It is an object of the present invention to provide a screen for obtaining a bright and high-contrast image with a simple configuration, low cost, easy enlargement of the screen.

  In order to solve the above-described problems and achieve the object, a screen according to the present invention includes a plurality of structures arranged in parallel on a plane, a transmission layer that transmits light incident on the structure, a transmission layer, and a structure. A reflector that reflects light traveling through the interface of the body, and the structure has a refractive index of the first polarization in the first polarization direction and a second polarization perpendicular to the first polarization direction. The birefringence is configured using an isorefractive material having substantially the same refractive index for the second polarized light in the direction, and the transmission layer has different refractive indexes for the first polarized light and the second polarized light. The refractive index for the first polarization of the structure is smaller than the refractive index for the first polarization of the transmission layer, and the refractive index of the transmission layer for the first polarization The difference from the refractive index for the first polarization is related to the second polarization of the transmission layer. The refractive index of, being greater than the difference between the refractive index for the second polarization of the structure.

  Of the light incident on the interface between the transmission layer and the structure at an incident angle greater than the critical angle, the first polarized light component is totally reflected at the interface. By separating the first polarized light component and the second polarized light component using total reflection at the interface, the projection light that is polarized light in a specific polarization direction is converted into a polarized light component different from the projection light in the external light. Separate from. Light incident on the interface at an incident angle less than the critical angle passes through the interface. By separating light of different incident angles using total reflection at the interface, projection light traveling in a predetermined angle range is separated from external light traveling in an angle range different from the projection light Let By making both polarization selection and angle selection compatible with a plurality of structures and transmission layers, it is possible to efficiently reflect projection light and reduce external light reflection with a simple configuration. As a result, it is possible to obtain a screen for obtaining a bright and high-contrast image, with a simple structure and at a low cost, easily increasing the size of the screen.

  Moreover, as a preferable aspect of the present invention, it is desirable that the reflecting portion reflects the component of the first polarized light that is totally reflected at the interface. Thereby, the projection light from the projector which inject | emits 1st polarized light can be reflected efficiently.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a light absorbing portion that absorbs the component of the second polarized light that has passed through the interface. Thereby, reflection of the component of the 2nd polarization | polarized-light component which is a polarization component different from projection light among external light can be reduced.

  Moreover, as a preferable aspect of the present invention, it is desirable that the reflecting portion reflects the component of the second polarized light that has passed through the interface. Accordingly, it is possible to efficiently reflect the projection light from the projector that emits the second polarized light.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a light absorption part that absorbs the component of the first polarized light totally reflected at the interface. Thereby, reflection of the component of the 1st polarization | polarized-light component which is a polarization component different from projection light among external light can be reduced.

  Moreover, as a preferable aspect of the present invention, it is desirable that the reflecting portion is configured using a metal member. As a result, rotation of the polarization direction due to reflection can be suppressed, and the projection light reflected by the reflecting portion can be efficiently emitted from the screen.

  Moreover, as a preferable aspect of the present invention, it is desirable that the reflecting portion has a scattering structure that scatters the light to be reflected. An image can be displayed on the screen by scattering the projection light reflected by the reflecting portion.

  Furthermore, the screen according to the present invention includes a plurality of structures arranged in parallel on a plane, a transmission layer that transmits light incident on the structure, and scattering that scatters light traveling through the interface between the transmission layer and the structure. A structure and a light absorption part that absorbs light transmitted through the structure, the structure having a refractive index for the first polarization in the first polarization direction and a second perpendicular to the first polarization direction. The refractive index of the second polarized light in the polarization direction is substantially the same, and the transmission layer has a refractive index different from the refractive index of the first polarized light and the refractive index of the second polarized light. A birefringent material is used, the refractive index for the first polarization of the structure is smaller than the refractive index for the first polarization of the transmission layer, and the refractive index for the first polarization of the transmission layer and the structure The difference from the refractive index for the first polarization of the body is the second polarization of the transmission layer. The refractive index of about, being greater than the difference between the refractive index for the second polarization of the structure. As a result, it is possible to obtain a screen for obtaining a bright and high-contrast image, with a simple structure and at a low cost, easily increasing the size of the screen.

  As a preferred embodiment of the present invention, it is desirable that the interface has substantially the same shape as the quadratic curve in a cross section perpendicular to the plane, and the scattering structure is formed with the focal position of the quadratic curve as a substantial center. Thereby, the projection light totally reflected at the interface can be efficiently scattered.

  As a preferred embodiment of the present invention, it is desirable that the refractive index of the transmissive layer for the second polarized light and the refractive index of the structure for the second polarized light are substantially the same. The component of the second polarized light incident on the interface between the transmission layer and the structure travels straight through the interface and proceeds to the structure. As a result, the first polarized light component and the second polarized light component that are totally reflected at the interface can be separated.

  As a preferred embodiment of the present invention, it is desirable that the plurality of structures are arranged in an array in a two-dimensional direction on a plane. Thereby, it is possible to select the polarization and angle in the two-dimensional direction, and to obtain a higher contrast.

  Furthermore, the screen according to the present invention includes a plurality of structures arranged in parallel on a plane, a transmission layer that transmits light incident on the structure, and reflection that reflects light traveling through the interface between the transmission layer and the structure. And the structure has a refractive index for the first polarized light in the first polarization direction and a refractive index for the second polarized light in the second polarization direction perpendicular to the first polarization direction. The transmission layer is configured using different birefringent materials, the transmission layer is configured using an isorefractive material in which the refractive index for the first polarized light and the refractive index for the second polarized light are substantially the same, and The refractive index for one polarization is smaller than the refractive index for the first polarization of the transmissive layer, and the difference between the refractive index for the first polarization of the transmissive layer and the refractive index for the first polarization of the structure is: The refractive index for the second polarization of the transmission layer and the second polarization of the structure. Wherein the greater than the difference between the refractive index. As a result, it is possible to obtain a screen for obtaining a bright and high-contrast image, with a simple structure and at a low cost, easily increasing the size of the screen.

It is sectional drawing which represented typically the screen which concerns on Example 1 of this invention. It is a perspective view showing a plurality of structures typically. It is sectional drawing explaining the behavior of the light which advanced substantially parallel to the Z-axis. It is sectional drawing explaining the behavior of the light which advanced diagonally with respect to the Z-axis. It is sectional drawing of the screen which provided the scattering structure in the reflection part. It is sectional drawing which represented typically the screen which concerns on Example 2 of this invention. It is a perspective view showing a plurality of structures typically. 6 is a cross-sectional view illustrating a comparative example of Example 2. FIG. It is sectional drawing explaining the behavior of the light which advanced substantially parallel to the Z-axis. It is sectional drawing explaining the behavior of the light which advanced diagonally with respect to the Z-axis. It is a perspective view showing a plurality of structures concerning a modification typically. It is sectional drawing which represented typically the screen which concerns on Example 3 of this invention. It is a figure explaining the preferable magnitude | size of a scattering structure. It is sectional drawing which represented typically the screen which concerns on Example 4 of this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a screen 10 according to the first embodiment of the present invention. The screen 10 is a reflective screen that reflects projection light from a projector (not shown). The base material 11 is a plate-like member that supports each configuration of the screen 10. The light absorption unit 12 is provided on the entire substrate 11. The light absorption unit 12 absorbs incident light. The light absorption part 12 is comprised using light absorption material, for example, light absorption resin. The structure 13 has a mountain-shaped cross-sectional shape. The structure 13 is made of an isorefractive material.

  FIG. 2 is a perspective view schematically showing the plurality of structures 13. The plurality of structures 13 are arranged in parallel in a specific direction. Here, the direction in which the plurality of structures 13 are arranged in parallel is defined as the X-axis direction. A direction perpendicular to the X-axis direction on the plane on which the plurality of structures 13 are arranged is defined as a Y-axis direction. A direction perpendicular to the X-axis direction and the Y-axis direction is taken as a Z-axis direction. Each structure 13 has a long column shape in the Y-axis direction. The cross section of the screen 10 shown in FIG. 1 is an XZ cross section. The width of the structure 13 in the X-axis direction is preferably smaller than the width of one pixel displayed on the screen 10, for example, about several tens to several hundreds μm.

  The transmissive layer 14 is provided on the light incident side with respect to the plurality of structures 13. The transmissive layer 14 transmits light incident on the structure 13. The transmission layer 14 is made of a birefringent material. The reflection part 15 is a valley between adjacent structures 13 and is provided on the light absorption part 12. The reflector 15 reflects incident light. The reflector 15 is made of a highly reflective material. On the light absorbing portion 12, a layer 16 made of the same member as the structural body 13 is provided in a portion other than the portion where the reflecting portion 15 is provided. In addition, it is desirable for the reflection part 15 to be able to suppress the rotation of the polarization direction due to reflection, and it is desirable to use, for example, a metal member as the highly reflective member. As a result, the projection light reflected by the reflecting portion 15 can be efficiently emitted from the screen 10.

Here, it is assumed that the first polarization in the first polarization direction is s-polarization and the second polarization in the second polarization direction perpendicular to the first polarization direction is p-polarization. Transmitting layer 14 is formed of a birefringent material, the refractive index _{n e1} for s-polarized light, and a refractive index _{n o1} for p-polarized light different _{(n e1} ≠ _n o1). The structure 13 is made of an isorefractive material, and the refractive index n _e2 for s-polarized light is the same as the refractive index n _o2 for p-polarized light (n _e2 = n _o2 ). In addition, the refractive index n _e2 for the s-polarized light of the structure 13 is smaller than the refractive index n _e1 for the s-polarized light of the transmission layer 14 (n _e2 <n _e1 ). The refractive index _{n o1} for p-polarized light transmission layer 14, the refractive index _{n o2} for p-polarized light of the structure 13, is substantially the same _{(n o1} ≒ _{n o2).}

As the birefringent material, for example, a Liquid Crystalline Polymer film (refractive index n _e = 1.66 for extraordinary light, refractive index n _o = 1.51 for ordinary light) manufactured by Dejima Optical Films is used. The equal refractive material, _{e.g., TAC (Tri-Acetyl Cellulose,} n o = 1.52) is used. As the birefringent material, for example, a film made of a polymerizable liquid crystal may be used. Incidentally, the refractive index n _o1 for p-polarized light transmission layer 14, the refractive index n _o2 for p-polarized light of the structure 13, if the difference there is for example the degree 0.01, can be regarded as substantially the same.

  FIG. 3 is a cross-sectional view for explaining the behavior of the projection light and the external light that have traveled substantially parallel to the Z axis and entered the screen 10. It is assumed that projection light L2 that is s-polarized light is projected from the projector. Since the difference in refraction angle between s-polarized light and p-polarized light due to incidence on the transmissive layer 14 is very small, the separation of light rays between s-polarized light and p-polarized light caused by refraction is not shown.

  For s-polarized light, a difference in refractive index occurs between the structure 13 and the transmission layer 14. The projection light L2 that travels substantially parallel to the Z-axis and enters the interface between the transmission layer 14 and the structure 13 at an incident angle greater than the critical angle is totally reflected at the interface due to the difference in refractive index. The reflection unit 15 reflects the projection light L2 that is totally reflected once or a plurality of times at the interface, in addition to the light directly incident on the reflection unit 15 from the transmission layer 14. Thereby, the screen 10 reflects the projection light L2 efficiently. By making the polarization axis of the projection light L2 coincide with the delay axis of the transmission layer 14, the projection light L2 is transmitted to the transmission layer 14 without changing the polarization state, and the projection light L2 is efficiently emitted from the screen 10. Can do.

  For p-polarized light, there is almost no difference in refractive index between the structure 13 and the transmission layer 14. The p-polarized light component L1 out of the external light traveling substantially parallel to the Z axis travels straight through the interface between the transmission layer 14 and the structure 13. The p-polarized component L1 that has passed through the interface and transmitted through the structure 13 and the layer 16 is absorbed by the light absorption unit 12. Thereby, the screen 10 can reduce reflection of the p-polarized light component L1, which is a polarized light component different from the projection light L2. The screen 10 uses the total reflection of s-polarized light at the interface to separate projection light that is polarized light in a specific polarization direction from polarized light components different from the projection light in the external light. By reducing the reflection of the polarized light component different from the projection light in the external light, the contrast can be improved up to twice as much.

  FIG. 4 is a cross-sectional view for explaining the behavior of external light that travels in a direction that is greatly inclined obliquely with respect to the Z axis and enters the screen 10. The external light L3 that has entered the interface between the transmission layer 14 and the structure 13 at an incident angle equal to or less than the critical angle passes through both the p-polarized component and the s-polarized component. The external light L3 that has passed through the interface and transmitted through the structure 13 and the layer 16 is absorbed by the light absorption unit 12. The screen 10 separates light in different angle ranges using total reflection at the interface, so that the projection light that has traveled in an angle range near to the screen 10 is different from the projection light. Separates external light traveling in an angular range.

  The screen 10 enables both the selection of polarization and the angle selection by the plurality of structures 13 and the transmission layer 14 to efficiently reflect the projection light with a simple configuration and reduce the reflection of external light. Is possible. The screen 10 can be easily enlarged by eliminating the need for a polarizing plate. Thereby, it is easy to increase the size of the screen 10 at a low cost with a simple configuration, and it is possible to obtain a bright and high-contrast image.

The screen 10 is not limited to the case where the refractive index _no1 for the p-polarized light of the transmission layer 14 and the refractive index _no2 for the p-polarized light of the structure 13 are substantially the same. Screen 10, at least, a refractive index _{n e1} for s-polarized light transmitting layer 14, the difference between the refractive index _{n e2} for s-polarized light of the structure 13, the refractive index _{n o1} for p-polarized light transmitting layer 14 The difference between the structure 13 and the refractive index _no2 for the p-polarized light is _sufficient .

  The screen 10 may be configured such that the first polarization in the first polarization direction is p-polarization and the second polarization in the second polarization direction is s-polarization. In this case, projection light that is p-polarized light is projected from the projector. The screen 10 is not limited to being able to efficiently reflect projection light in an angle range near to the screen 10, but may be any configuration as long as it can efficiently reflect projection light in a certain angle range. You may do it.

  As shown in the sectional view of FIG. 5, the screen 10 may be provided with a scattering structure 17 on the surface of the reflecting portion 15. The scattering structure 17 scatters the light to be reflected. The scattering structure 17 is formed by providing fine irregularities on the surface of the reflecting portion 15. An image can be displayed on the screen 10 by scattering the projection light reflected by the reflecting portion 15.

  FIG. 6 is a cross-sectional view schematically showing the screen 20 according to the second embodiment of the present invention. FIG. 7 is a perspective view schematically showing a plurality of structures 22. The screen 20 according to the present embodiment is characterized in that it reflects light that has passed through the interface and absorbs light that has been totally reflected at the interface. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The reflecting portion 21 is provided on the entire base material 11. The structure 22 has an isosceles triangular cross-sectional shape. The structure 22 is made of an isorefractive material. The plurality of structures 22 are arranged in parallel in the X-axis direction. Each structure 22 has a triangular prism shape that is long in the Y-axis direction.

  The transmissive layer 23 is provided on the light incident side with respect to the plurality of structures 22. The transmission layer 23 is made of a birefringent material. The light absorbing portion 24 is provided by being filled in the valleys between the adjacent structures 22. A layer 25 made of the same member as that of the structure 22 is provided between the plurality of structures 22 and the reflection portion 21.

  FIG. 8 is a cross-sectional view in the case where the structure 22 and the transmissive layer 23 described in the present embodiment are applied to the screen 10 of the first embodiment (see FIG. 1) as a comparative example of the present embodiment. When the structure 22 having an isosceles triangular cross-sectional shape is used, the incident angle of the projection light with respect to the interface gradually decreases as the total reflection at the interface between the structure 22 and the transmission layer 23 is repeated. When the incident angle with respect to the interface becomes equal to or smaller than the critical angle, the projection light passes through the interface. A part of the projection light passes through the structure 22 and the layer 16 and is then absorbed by the light absorption unit 12. For this reason, the luminance of the image may be reduced.

  FIG. 9 is a cross-sectional view for explaining the behavior of projection light and external light that have traveled substantially parallel to the Z axis and entered the screen 20 according to the present embodiment. Assume that the refractive index of the structure 22 and the refractive index of the transmission layer 23 are set in the same manner as in the first embodiment. In the screen 20 of the present embodiment, the projection light L4 from the projector is p-polarized light that is the second polarized light. The projection light L4 that travels substantially parallel to the Z axis and enters the interface between the transmission layer 23 and the structure 22 passes through the interface. The reflection unit 21 reflects the projection light L4 that has passed through the interface and transmitted through the structure 22 and the layer 25.

  Of the external light that has traveled substantially parallel to the Z axis, the s-polarized light component L5 that is the first polarized light component is totally reflected at the interface between the transmission layer 23 and the structure 22. A part of the s-polarized component L5 is totally reflected at a position close to the light absorption unit 24 in the interface and then absorbed by the light absorption unit 24. Further, a part of the s-polarized component L5 passes through the interface because the incident angle with respect to the interface becomes a critical angle or less due to one or more total reflections at the interface. A part of the s-polarized component L5 that has passed through the structure 22 and the layer 25 is reflected by the reflection unit 21 and then absorbed by the light absorption unit 24. Thereby, the screen 20 can reduce the reflection of the s-polarized component L5, which is a polarized component different from the projection light L4. The screen 20 uses the total reflection of s-polarized light at the interface to separate projection light that is polarized light in a specific polarization direction from polarized light components different from the projection light in the external light.

  FIG. 10 is a cross-sectional view for explaining the behavior of external light that travels in a direction that is greatly inclined obliquely with respect to the Z axis and enters the screen 20. The external light L6 incident on the interface between the transmission layer 23 and the structure 22 at an incident angle less than the critical angle passes through both the p-polarized component and the s-polarized component. A part of the external light L6 that has passed through the interface and transmitted through the structure 22 and the layer 25 is reflected by the reflection unit 21 and then absorbed by the light absorption unit 24. Note that some of the external lights L5 and L6 are reflected by the reflection unit 21 and then enter the light absorption unit 24 and exit from the screen 20. In this case, since the external lights L5 and L6 emitted from the screen 20 travel in a direction different from the projection light L4, the influence on the contrast reduction of the image can be reduced.

  The screen 20 separates the light beams having different angle ranges from each other, thereby separating the projection light that has traveled in an angle range that is nearly perpendicular to the screen 20 and the external light that travels in an angle range different from the projection light. Let In the case of this embodiment as well, it is possible to obtain a bright and high-contrast image with a simple configuration at a low cost and easily increasing the size of the screen 20.

  The screen 20 may be configured such that the first polarized light in the first polarization direction is p-polarized light and the second polarized light in the second polarization direction is s-polarized light. In this case, projection light that is s-polarized light is projected from the projector. The screen 20 is not limited to being able to efficiently reflect projection light in an angular range near to the screen 20, but may be any configuration as long as it can efficiently reflect projection light in a certain angle range. You may do it. Also in the case of the present embodiment, the reflecting portion 21 may be provided with a scattering structure. The structure is not limited to the case where the cross-sectional shape is described in the first and second embodiments, and may be appropriately modified.

  FIG. 11 is a perspective view schematically showing a plurality of structures 30 according to the modification. The plurality of structures 30 are applied to the screen 20 according to the present embodiment. The plurality of structures 30 of the present modification are arranged in an array in the X-axis direction and the Y-axis direction, which are two-dimensional directions on a plane. Each structure 30 has a quadrangular pyramid shape. By arranging the structures 30 in the two-dimensional direction, it is possible to select the polarization and the angle in the two-dimensional direction, and to obtain a higher contrast. Note that the structures to be juxtaposed in the two-dimensional direction are not limited to a quadrangular pyramid shape, and may have any shape.

  FIG. 12 is a cross-sectional view schematically showing the screen 40 according to the third embodiment of the present invention. The screen 40 according to the present embodiment is characterized in that the interface between the transmission layer 42 and the structure 41 has substantially the same shape as the quadratic curve in the XZ section. The same parts as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. The quadratic curve at the interface between the transmission layer 42 and the structure 41 is convex on the light absorption unit 12 side. In the XZ cross section, the structure 41 is a portion surrounded by the adjacent quadratic curve and the light absorbing portion 12. The transmissive layer 42 is a portion surrounded by one quadratic curve and the XY plane. The structure 41 is made of an isorefractive material. The plurality of structures 41 are arranged in an array in the X-axis direction and the Y-axis direction, which are two-dimensional directions on a plane. The transmission layer 42 is made of a birefringent material.

  The scattering structure 43 is provided around the focal position of the quadratic curve in the transmission layer 42. The scattering structure 43 scatters incident light. The scattering structure 43 is configured by dispersing particles made of a member having a refractive index different from that of the member constituting the transmission layer 42.

  Assume that the refractive index of the structure 41 and the refractive index of the transmission layer 42 are set in the same manner as in the first embodiment. In the screen 40 of the present embodiment, the projection light L7 from the projector is s-polarized light that is the first polarization. The projection light L7 that travels substantially parallel to the Z axis and enters the interface between the transmission layer 42 and the structure 41 at an incident angle greater than the critical angle is totally reflected at the interface and travels toward the scattering structure 43. Of the projection light L 7, the component totally reflected at the interface and the component transmitted through the transmission layer 42 and proceeding directly toward the scattering structure 43 are scattered by the scattering structure 43. An image can be displayed on the screen 40 by scattering the projection light L 7 by the scattering structure 43.

  Of the external light that has traveled substantially parallel to the Z-axis, the p-polarized component L8 passes through the interface between the transmission layer 42 and the structure 41 and enters the light absorption unit 12. Thereby, the screen 40 can reduce reflection of the p-polarized light component L8, which is a polarized light component different from the projection light L7. External light that travels in a direction greatly inclined with respect to the Z axis and enters the screen 40 passes through the interface of both the p-polarized component and the s-polarized component, and is absorbed by the light absorbing unit 12. As described above, also in this embodiment, it is possible to achieve both polarization selection and angle selection by the plurality of structures 41 and the transmission layer 42.

FIG. 13 illustrates a preferred size of the scattering structure 43. It is assumed that the quadratic curve at the interface between the transmissive layer 42 and the structure 41 is y = ax ² . Projection light L9 incident on the interface at an incident angle greater than the critical angle travels in the direction of the focal position of the quadratic curve due to total reflection at the interface. In order to improve the brightness of the image, not only the projection light L9 incident on the interface at a position greater than the critical angle, but also the projection light L10 traveling to a position less than the critical angle relative to the interface is incident on the scattering structure 43. It is desirable to be possible.

Of the quadratic curve of y = ax ^2, the angle θ _x formed by the normal line at the position x and the straight line parallel to the y-axis is arctan (1 / 2ax). The critical angle θ _c at the interface where the refractive index of the incident side medium is n ₁ and the refractive index of the emission side medium is n ₂ is arcsin (n ₂ / n ₁ ). When the scattering structure 43 has a circular shape with a radius r, the radius r that occupies the position where the projection light L10 that travels to a position that is less than the critical angle with respect to the interface enters x satisfying θ _x = θ _c. As given. Therefore, it is desirable that the scattering structure 43 has a radius r that satisfies arcsin (n ₂ / n ₁ ) = arctan (1/2 ar).

  In the case of this embodiment as well, it is possible to obtain a bright and high-contrast image with a simple configuration at low cost and easily increasing the size of the screen 40. The scattering structure 43 may be a dispersion of a reflecting material that reflects incident light, instead of a dispersion of a scattering agent.

  FIG. 14 is a cross-sectional view schematically showing a screen 50 according to the fourth embodiment of the present invention. The screen 50 according to the present embodiment includes a structure 51 made of a birefringent material and a transmissive layer 52 made of an isorefractive material. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The layer 53 is composed of the same member as the structure 51. The screen 50 according to the present embodiment is configured in the same manner as the screen 10 according to the first embodiment except that the material of the structure 51, the transmission layer 52, and the layer 53 is different from the screen 10 according to the first embodiment.

Transmitting layer 52 is formed of a constant refractive material, the refractive index _{n e1} for s-polarized light, is the same as the refractive index _{n o1} for p-polarized light _{(n e1 =} n o1). The structure 51 is made of a birefringent material, and has a refractive index n _e2 for s-polarized light and a refractive index n _o2 for p-polarized light ( _{ne 2} ≠ no ₂ ). In addition, the refractive index n _e2 for the s-polarized light of the structure 51 is smaller than the refractive index n _e1 for the s-polarized light of the transmission layer 52 (n _e2 <n _e1 ). The refractive index _{n o1} for p-polarized light transmission layer 52, the refractive index _{n o2} for p-polarized light of the structure 51, is substantially the same _{(n o1} ≒ _{n o2).}

The behavior of the projection light and the external light incident on the screen 50 is the same as in the case of FIG. In the case of this embodiment as well, it is possible to obtain a bright and high-contrast image with a simple configuration at low cost and easily increasing the size of the screen 50. The screen 50 is not limited to the case where the refractive index _no1 for the p-polarized light of the transmission layer 52 and the refractive index _no2 of the structure 51 for the p-polarized light are substantially the same. Screen 50 includes at least a refractive index _{n e1} for s-polarized light transmitting layer 52, the difference between the refractive index _{n e2} for s-polarized light of the structure 51, the refractive index _{n o1} for p-polarized light transmitting layer 52 The difference between the structure 51 and the refractive index _no2 for the p-polarized light is _sufficient . Also in the case of the screen 20 according to the second embodiment, similarly to the screen 50 according to the present embodiment, the structure includes a structure formed of a birefringent material and a transmission layer formed of an isotropic material. It may be deformed.

  As described above, the screen according to the present invention is suitable for displaying an image using projection light from a front projection type projector.

  10 screen, 11 base material, 12 light absorption part, 13 structure, 14 transmission layer, 15 reflection part, 16 layer, 17 scattering structure, 20 screen, 21 reflection part, 22 structure, 23 transmission layer, 24 light absorption part , 25 layers, 30 structures, 40 screens, 41 structures, 42 transmission layers, 43 scattering structures, 50 screens, 51 structures, 52 transmission layers, 53 layers

Claims (12)

A plurality of structures arranged in parallel on a plane;
A transmission layer that transmits light incident on the structure;
A reflection part that reflects light traveling through the interface between the transmission layer and the structure,
The structure has an equal refractive index in which the refractive index for the first polarized light in the first polarization direction and the refractive index for the second polarized light in the second polarization direction perpendicular to the first polarization direction are substantially the same. It is composed using a sex material,
The transmission layer is configured by using birefringent materials having different refractive indices for the first polarized light and the second polarized light,
The refractive index of the structure for the first polarization is smaller than the refractive index of the transmission layer for the first polarization, and the refractive index of the transmission layer for the first polarization, and the structure of the structure The difference between the refractive index for the first polarized light and the refractive index for the second polarized light of the structure is larger than the difference between the refractive index for the second polarized light of the structure and the screen. .   The screen according to claim 1, wherein the reflection unit reflects the component of the first polarized light that is totally reflected at the interface.   The screen according to claim 2, further comprising a light absorbing portion that absorbs the component of the second polarized light that has passed through the interface.   The screen according to claim 1, wherein the reflection unit reflects the component of the second polarized light that has passed through the interface.   The screen according to claim 4, further comprising a light absorbing portion that absorbs the component of the first polarized light that is totally reflected at the interface.   The screen according to claim 1, wherein the reflection portion is configured using a metal member.   The screen according to claim 1, wherein the reflection unit includes a scattering structure that scatters light to be reflected. A plurality of structures arranged in parallel on a plane;
A transmission layer that transmits light incident on the structure;
A scattering structure that scatters light traveling through the interface between the transmission layer and the structure;
A light absorption part that absorbs light transmitted through the structure,
The structure has an equal refractive index in which the refractive index for the first polarized light in the first polarization direction and the refractive index for the second polarized light in the second polarization direction perpendicular to the first polarization direction are substantially the same. It is composed using a sex material,
The transmission layer is configured by using birefringent materials having different refractive indices for the first polarized light and the second polarized light,
The refractive index of the structure for the first polarization is smaller than the refractive index of the transmission layer for the first polarization, and the refractive index of the transmission layer for the first polarization, and the structure of the structure The difference between the refractive index for the first polarized light and the refractive index for the second polarized light of the structure is larger than the difference between the refractive index for the second polarized light of the structure and the screen. . The interface has substantially the same shape as a quadratic curve in a cross section perpendicular to the plane,
The screen according to claim 8, wherein the scattering structure is formed with a focal position of the quadratic curve as a substantial center.   The refractive index of the transmissive layer for the second polarized light and the refractive index of the structure for the second polarized light are substantially the same. screen.   The screen according to claim 1, wherein the plurality of structures are arranged in an array in a two-dimensional direction on the plane. A plurality of structures arranged in parallel on a plane;
A transmission layer that transmits light incident on the structure;
A reflection part that reflects light traveling through the interface between the transmission layer and the structure,
The structure includes a birefringent material having a refractive index for the first polarized light in the first polarization direction and a refractive index for the second polarized light in the second polarization direction perpendicular to the first polarization direction. Configured with
The transmission layer is configured using an isorefractive material in which a refractive index for the first polarized light and a refractive index for the second polarized light are substantially the same,
The refractive index of the structure for the first polarization is smaller than the refractive index of the transmission layer for the first polarization, and the refractive index of the transmission layer for the first polarization, and the structure of the structure The difference between the refractive index for the first polarized light and the refractive index for the second polarized light of the structure is larger than the difference between the refractive index for the second polarized light of the structure and the screen. .

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