JP2008065279A - Polarized light converting element and polarized light converting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarized light converting element and a polarized light converting member which have small number of parts and can reduce the complexities of manufacturing processes. <P>SOLUTION: Since a reflection type polarized light converting film 27 has the function of converting a polarization direction of at least a part of s-polarized light emitted from a polarized light separation film 26 to a polarization direction of p-polarized light (a function of retardation plate) and a function of emitting the p-polarized light with a converted polarization direction, from the polarized light converting element 23 after reflection (a function of a reflecting film), the retardaing plate and the reflecting film in conventional constitution can be constituted as one member to dispense with individual provision. As a result, the number of parts of the polarized light conversion element 23 can be reduced and complicatedness of the manufacturing processes can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polarization conversion element and a polarization conversion member.

  In general, a projection display device such as a projector is mainly composed of a light source, a light modulation element, and a projection lens. Light emitted from the light source is modulated by a light modulation element, and the modulated light is projected onto a screen or the like by a projection lens, thereby displaying an image such as a still image or a moving image.

  For example, a transmissive liquid crystal device is often used as a light modulation element of a projection display device. A polarizing plate is usually provided on the incident surface of the liquid crystal device. Of the light incident on the liquid crystal device, the light component polarized in the same direction as the polarization direction of the polarizing plate is transmitted through this polarizing plate, and the light component polarized in a direction different from the polarization direction of the polarizing plate is blocked by this polarizing plate. It has come to be.

  In recent years, there has been a demand for a projection display device that displays a bright and high-contrast image. In response to this requirement, by aligning the polarization direction of the light emitted from the light source to be the same as the polarization direction of the polarizing plate, a large amount of light components can be transmitted through the polarizing plate and emitted from the light source. A technique for utilizing as much light as possible for display has been disclosed (for example, see Patent Document 1).

The projector described in Patent Document 1 has a configuration in which a polarization conversion prism array capable of aligning the polarization direction of light in one direction is provided between a light source and a light modulation element (a liquid crystal device with a polarizing plate). . The polarization conversion prism array has a configuration in which a polarization separation film and a reflection film are provided in a substrate, and a retardation plate is attached to the surface of the substrate. The light emitted from the light source includes a light component polarized in the same direction as the polarization direction of the polarizing plate (s-polarized light) and a light component polarized in a direction different from the polarization direction of the polarizing plate (p-polarized light). Separated. The s-polarized light is reflected by the reflecting film and emitted as it is. The polarization direction of the p-polarized light is converted by the phase difference plate and emitted as s-polarized light.
Japanese Patent Laid-Open No. 2002-23106

In the configuration described in Patent Document 1, since three types of members having different functions from the polarization separation film, the reflection film, and the phase difference plate are attached to the polarization conversion element, the number of components of the polarization conversion element increases. The manufacturing process of the polarization conversion element becomes complicated.
In view of the circumstances as described above, an object of the present invention is to provide a polarization conversion element and a polarization conversion member that have a small number of parts and can reduce the complexity of the manufacturing process.

In order to achieve the above object, a polarization conversion element according to the present invention includes a first light component having a predetermined polarization direction and a second light component having a polarization direction different from the predetermined polarization direction. A polarization separation member that emits the first light component in a first direction and emits the second light component in a second direction different from the first direction, and the second direction of the polarization separation member The second light component that is provided on the second light component that is converted from the second light component emitted from the polarization separation member into the predetermined polarization direction component and converts the polarization direction is converted into the second light component. And a polarization conversion member that emits light in the first direction.
According to the present invention, the polarization conversion member has a function of converting at least a portion of the polarization direction component of the second light component emitted from the polarization separation member into a predetermined polarization direction component (function as a retardation plate). Since it has a function of emitting the second light component whose polarization direction is changed in the first direction (function as a reflection film), for example, the retardation plate and the reflection film in the conventional configuration are used as one member. It can be configured, and these need not be provided separately. Thereby, the number of parts of the polarization conversion element can be reduced, and the complexity of the manufacturing process can be reduced.

The polarization conversion element is characterized in that the polarization separation member and the polarization conversion member are provided inside a base material capable of transmitting light.
According to the present invention, since the polarization separation member and the polarization conversion member are provided inside the base material capable of transmitting light, the positions of the polarization separation member and the polarization conversion member can be fixed by the base material. it can. Thereby, the position shift between a polarization separation member and a polarization conversion member can be avoided.

The polarization conversion element is characterized in that one polarization separation member and one polarization conversion member make a pair, and a plurality of pairs of the polarization separation member and the polarization conversion member are provided. To do.
According to the present invention, one polarization separation member and one polarization conversion member make a pair, and a plurality of pairs of the polarization separation member and the polarization conversion member are provided. When the conversion element is mounted on a liquid crystal projector, the arrangement and number of the pair of polarization separation members and polarization conversion members can be selected according to the arrangement of the pixels of the liquid crystal light valve. This enables a wide range of designs.

In the above-described polarization conversion element, the polarization conversion member is provided in the second direction, and is formed of a flat layer made of a light-reflective material, and a surface of the flat layer, made of a light-reflective material. And a grid layer having a grid portion extending in one direction at a predetermined pitch and a predetermined depth.
According to the present invention, since the polarization conversion member has a flat layer made of a material that is provided in the second direction and is capable of reflecting light, the desired direction can be obtained by adjusting the direction of the surface of the flat layer. The light can be reflected and emitted. In addition, since it has a grid layer provided on the surface of the flat layer and made of a light-reflective material and extending in one direction at a predetermined pitch and a predetermined depth, the second light component The polarization direction can be converted into a predetermined direction. As described above, since the polarization direction conversion by the grid layer and the emission in the first direction by the flat layer can be performed with one member, for example, it is necessary to separately provide the retardation plate and the reflection film in the conventional configuration. However, the number of parts of the polarization conversion element can be reduced, and the complexity of the manufacturing process can be reduced.
In the conventional polarization conversion element, the phase difference plate is configured to transmit the light whose polarization direction has been converted, and is often composed mainly of an organic material having a high light transmittance. For this reason, for example, when mounted on a projector or the like, burn-in may occur due to light emitted from the light source, which causes a problem in light resistance of the polarization conversion element. In contrast, in the present invention, the polarization conversion member is configured to reflect the light whose polarization direction has been converted. Since the grid layer and the flat layer of the polarization conversion member are made of a light-reflective material, they can be made of an inorganic material such as metal. Thereby, burn-in can be avoided and the light resistance can be improved.

In the polarization conversion element, the flat layer and the grid layer are mainly composed of silver, gold, or aluminum.
Silver, gold, and aluminum are metals with high light reflectivity. According to the present invention, since the flat layer and the grid layer are mainly composed of silver, gold, or aluminum, the second light component incident on the polarization conversion element can be used with high efficiency. In addition, since these materials have high light resistance, when this polarization conversion element is mounted on, for example, a projector, burn-in due to light emitted from the light source can be avoided.

In the polarization conversion element, the predetermined pitch is a value smaller than the wavelength of incident light,
The predetermined depth is in a range of 60 nm or more and 160 nm or less, a direction at an elevation angle of 45 ° with respect to a vertical plane with respect to the second direction of the polarization conversion member, and a direction orthogonal to the one direction on the vertical plane The polarization conversion member is arranged such that the second light component is incident from a direction that forms an angle in a range larger than 30 ° and smaller than 75 °.
The inventor has found that the light use efficiency varies depending on the material of the flat layer and the grid layer, the predetermined pitch, and the predetermined depth. Here, the light use efficiency is represented by the ratio between the intensity of incident light incident on the polarization conversion member and the intensity of exit light emitted from the polarization conversion member.
In the present invention, based on this point, the predetermined pitch is a value smaller than the wavelength of incident light, the predetermined depth is in the range of 60 nm to 160 nm, and the plane perpendicular to the second direction of the polarization conversion member So that the second light component is incident from a direction that forms an angle in the range of an elevation angle of 45 ° and an angle that is greater than 30 ° and less than 75 ° with respect to a direction orthogonal to one direction on the vertical plane. Since the polarization conversion member is arranged, the light use efficiency can be optimized. In addition, the inventors of the present invention determine the optimum value of the predetermined depth and the second light component with respect to the direction orthogonal to one direction on the vertical plane, depending on the wavelength of the second light component and the main components of the flat layer and the grid layer. It was found that the optimum value of the incident angle is different. Based on this, in the present invention, the predetermined depth is in the range of 60 nm or more and 160 nm or less, and the optimum value of the incident angle is in the range of more than 30 ° and less than 75 °. These values can be selected as appropriate according to the wavelength of each.

The polarization conversion element is characterized in that the polarization separation member is a wire grid polarizing plate.
According to the present invention, since the polarization separation member is a wire grid polarizing plate, incident light can be reliably separated. In the configuration in which the polarization conversion member has a grid part, there is an advantage that the grid part of the polarization conversion member and the wire grid part of the wire grid polarizing plate can be manufactured in the same manufacturing process.

The polarization conversion member according to the present invention is a flat layer made of a light-reflective material, and is provided on the surface of the flat layer, is made of a light-reflective material, and extends in one direction at a predetermined pitch and a predetermined depth. And a grid layer having an existing grid portion.
According to the present invention, the polarization conversion member includes a flat layer made of a light-reflective material and a light-reflective material provided on the surface of the flat layer and extending in one direction at a predetermined pitch and a predetermined depth. Therefore, by adjusting the orientation of the surface of the flat layer, light can be reflected and emitted in a desired direction, and the polarization direction of the second light component can be set to a predetermined value. Can be converted into directions. As described above, since the polarization direction conversion by the grid layer and the emission in the first direction by the flat layer can be performed with one member, for example, it is necessary to separately provide the retardation plate and the reflection film in the conventional configuration. However, the number of parts of the polarization conversion element can be reduced, and the complexity of the manufacturing process can be reduced.
In addition, in the present invention, the polarization conversion member is configured to reflect the light whose polarization direction is changed, and the grid layer and the flat layer of the polarization conversion member are made of a light-reflective material. It can comprise with inorganic materials, such as. Thereby, it is possible to avoid the polarization conversion member from being seized and to improve the light resistance.

[First Embodiment]
A first embodiment of the present invention will be described with reference to the drawings.
(Overall configuration of projector)
First, the overall configuration of the projector according to the present embodiment will be described. FIG. 1 is a diagram schematically showing the overall configuration of the projector PJ1.
The projector PJ1 is mainly composed of an image display device 2 and a projection lens 3.

The image display device 2 includes a light source 10, a uniform illumination system 20, and a color modulation unit 30.
The light source 10 includes a lamp 11 that emits white light, such as a metal halide lamp, an ultra-high pressure mercury lamp, or a xenon lamp, and a reflector 12 that reflects and collects the white light emitted from the lamp 11. As the reflector 12, a parabolic mirror is preferably used.

  The uniform illumination system 20 is an optical system that uniformizes the luminance distribution of white light from the light source 10, and includes a first lens array 21, a second lens array 22, a polarization conversion element 23, and a condenser lens 24. Have. The first lens array 21 and the second lens array 22 are arranged on the light emission side of the light source 10. The first lens array 21 and the second lens array 22 are optical members made of, for example, fly-eye lenses and the like, and uniformize the light luminance distribution. The polarization conversion element 23 is disposed on the light exit side of the second lens array 22 and is an optical element that aligns the polarization direction of light in one direction. The condenser lens 24 is a lens disposed on the light exit side of the polarization conversion element 23.

  The color modulation unit 30 is a part that modulates the luminances of the three primary colors of red (R), green (G), and blue (B) in the wavelength region of white light incident from the uniform illumination system 20. Dichroic mirrors 31a, 31b, three mirrors 32a, 32b, 32c, five field lenses (lens 33, relay lens 34, collimating lenses 35R, 35G, 35B), and three liquid crystal light valves 36R, 36G, 36B And a cross dichroic prism 37.

  The dichroic mirrors 31a and 31b are optical members for separating (spectralizing) white light into RGB three primary color lights. The dichroic mirror 31a is disposed on the light exit side of the condenser lens 24 so as to be inclined by 45 ° with respect to the light traveling direction. The dichroic mirror 31a includes a dichroic film that reflects blue light and green light and transmits red light. It is configured to be attached to a light transmissive substrate such as a glass plate. The dichroic mirror 31b is disposed on the light reflection side of the dichroic mirror 31a so as to be inclined by 45 ° with respect to the light traveling direction. The dichroic mirror 31b reflects green light and transmits blue light. The structure is affixed to a light transmissive substrate.

  The lens 33 and the relay lens 34 are optical members that transmit the light transmitted through the dichroic mirror 31b to the collimating lens 35B. The lens 33 is disposed on the light transmission side of the dichroic mirror 31b, and is provided to allow light to enter the relay lens 34 efficiently.

  The collimating lenses 35R, 35G, and 35B are arranged on the light incident side of the corresponding liquid crystal light valves 36R, 36G, and 36B, and are convex lenses that substantially collimate the respective color lights incident on the liquid crystal light valves 36R, 36G, and 36B. is there.

  The liquid crystal light valves 36R, 36G, and 36B are active matrix type liquid crystal display elements, and polarizing plates are attached to the light incident surface and the light emission surface, respectively. A polarizing plate attached to the light incident surface transmits p-polarized light. The liquid crystal light valves 36R, 36G, and 36B have a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and a black / dark (non-transmission) state when a voltage is applied, or vice versa. The gradation between light and dark is analog controlled according to the given control value.

  The cross dichroic prism 37 has a structure in which four right angle prisms are bonded together. A dielectric multilayer film (blue light reflecting dichroic film 37a) that reflects blue light is formed on the bonding surface of the right angle prisms, and a red color. A dielectric multilayer film (red light reflecting dichroic film 37b) that reflects light is formed.

(Configuration of uniform illumination system)
Next, the configuration of the uniform illumination system 20 described above will be described. FIG. 2 is a diagram showing the configuration of the light source 10 and the uniform illumination system 20 of the projector PJ1 shown in FIG.
As shown in the figure, the first lens array 21 and the second lens array 22 of the uniform illumination system 20 are arranged so that the convex surfaces 21a and 22a of the fly-eye lens face each other. The individual convex surfaces 21a and 22a have substantially the same size, the same number and the same arrangement, and are arranged so that the positions of the convex surfaces 21a and 22a overlap each other when viewed in the traveling direction of the light emitted from the light source 10. ing.

  The polarization conversion element 23 is mainly composed of a base material 25, a polarization separation film (polarization separation member) 26, and a reflective polarization conversion film (polarization conversion member) 27, and has a second lens on the light incident surface 23a. It is affixed to the back surface 22 b of the array 22. The polarization conversion element 23 is provided integrally with the second lens array 22.

FIG. 3 is a cross-sectional view showing the configuration of the polarization conversion element 23 in detail.
The base material 25 is a rectangular substrate made of a light transmissive material such as glass or quartz. In the base material 25, a polarization separation film 26 and a reflective polarization conversion film 27 are alternately provided in the vertical direction in the figure. One polarization separation film 26 and one reflection type polarization conversion film 27 make a pair, and a plurality of pairs of the polarization separation film 26 and the reflection type polarization conversion film 27 are provided in the substrate. It has become.

  The polarization separation film 26 is a dielectric film provided inside the base material 25. The polarization separation film 26 is disposed so as to be inclined at an angle α (for example, α = 45 °) with respect to the light incident surface 23 a of the polarization conversion element 23, for example, p-polarized light (for example, p-polarized light (white light) emitted from the light source 10. The first light component and the s-polarized light (second light component) are separated. The polarization separation film 26 transmits the separated p-polarized light and emits it in the same direction as the incident direction (first direction), and directs the separated s-polarized light toward the reflective polarization conversion film 27 (second direction). It is designed to reflect.

  The reflective polarization conversion film 27 is disposed in the reflection direction of the polarization separation film 26 and is provided so as to be inclined at an angle β (for example, β = 45 °) with respect to the light incident surface 23 a of the polarization conversion element 23. FIG. 4 is a perspective view showing the configuration of the reflective polarization conversion film 27. As shown in FIG. 4, the reflective polarization conversion film 27 is a rectangular member in plan view, and is mainly composed of a flat layer 27b and a grid layer 27c.

  The flat layer 27b is a layer that is provided inside the base material 25 and is mainly composed of a metal material having a high light reflectance such as silver, gold, or aluminum. The flat layer 27b has a thickness sufficient to reflect light without transmitting it.

  The grid layer 27c is a layer provided on the surface of the flat layer 27b on the side facing the light incident surface of the polarization separation film 26, and is mainly composed of a plurality of convex portions 27d. Each protrusion 27d is provided on the flat layer 27b so as to extend in the same direction, and is arranged with a predetermined interval d1 (for example, d1 = 70 nm) (gap 27e). The flat layer 27b is exposed in the gap 27e. A grid portion is formed by the convex portion 27d and the gap 27e. The extending direction of the grid portion is inclined with respect to the side direction of the reflective polarization conversion film 27 provided in a rectangular shape in plan view.

  The width of the convex portion 27d (the dimension in the direction orthogonal to the extending direction) is d2 (for example, d2 = 70 nm), and here, d1 = d2 = 70 nm. Therefore, the convex portions 27d are arranged at a pitch of 140 nm. The convex portion 27d is formed so that the height (dimension in the protruding direction) h from the flat layer 27b is in the range of, for example, 60 nm or more and 160 nm or less, and the height h is a predetermined depth of the grid portion. .

  The reflection-type polarization conversion film 27 is in a direction having an elevation angle of 45 ° with respect to the surface of the flat layer 27b and is larger than 30 ° with respect to a direction orthogonal to the extending direction of the grid portion on the surface of the flat layer 27b. It is arranged so that light enters from a direction forming an angle φ (see FIG. 5) in a range smaller than °.

(Projector operation)
Next, the operation of projector PJ1 configured as described above will be described. White light emitted from the lamp 11 of the light source 10 and white light collected by the reflector 12 enter the uniform illumination system 20. The brightness distribution of the white light incident on the uniform illumination system 20 is made uniform by the first lens array 21 and the second lens array 22. White light with a uniform luminance distribution enters the polarization conversion element 23. The white light incident on the polarization conversion element 23 is separated into a p-polarized light component and an s-polarized light component by the polarization separation film 26, and the p-polarized light component is transmitted through the polarization separation film 26. The s-polarized light component is reflected toward the reflective polarization conversion film 27.

  FIG. 5 is a diagram schematically showing how the polarization direction of the s-polarized light component is converted by the reflective polarization conversion film 27. 5, the XY plane is the surface of the flat layer 27b (surface on which the grid layer 27c is provided), and the X-axis direction is a direction orthogonal to the extending direction (grid direction) of the convex portion 27d. The Y-axis direction is the grid direction. The Z-axis direction is a direction perpendicular to the surface of the flat layer 27b.

  As shown in the figure, the s-polarized light separated by the polarization separation film 26 and incident on the reflection-type polarization conversion film 27 is incident from a direction with a depression angle of 45 ° with respect to the surface of the flat layer 27b and is orthogonal to the grid direction. The incident light is inclined at the angle φ with respect to the (X-axis direction in the figure). The polarization direction of the incident s-polarized light is the direction of the vector E in the figure.

  The incident s-polarized light is reflected by the grid layer 27c and the flat layer 27b, and at least a part thereof is converted to p-polarized light. In FIG. 5, the traveling direction of reflected light is the X′-axis direction, and the same direction as the vector E is the direction orthogonal to the vector E (the polarization direction of p-polarized light) is the Z′-axis direction. The (s-polarized light polarization direction) is the Y′-axis direction, and the reflected light is emitted from the polarization conversion element 23 as p-polarized light having a polarization direction in the Z′-axis direction. The white light having the polarization direction of P-polarized light by the polarization conversion element 23 is collected by the condenser lens 24 and enters the color modulation unit 30.

  Of the white light incident on the color modulation unit 30, red light is transmitted through the dichroic mirror 31a, and green light and blue light are reflected by the dichroic mirror 31a. The red light that has passed through the dichroic mirror 31a is reflected by the reflecting mirror 32a, is approximately collimated by the collimating lens 35R, and enters the liquid crystal light valve 36R. The green light and the blue light reflected by the dichroic mirror 31a enter the dichroic mirror 31b. Of these, blue light is transmitted through the dichroic mirror 31b, and green light is reflected by the dichroic mirror 31b. The green light reflected by the dichroic mirror 31b is substantially collimated by the collimating lens 35G and enters the liquid crystal light valve 36G. The blue light transmitted through the dichroic mirror 31b passes through the lens 33, the reflection mirror 32b, the relay lens 34, and the reflection mirror 32c, and enters the collimating lens 35B, and is substantially collimated and enters the liquid crystal light valve 36B.

  Since the polarizing plates on the incident surface side of the liquid crystal light valves 36R, 36G, and 36B transmit p-polarized light, the p-polarized red light, green light, and blue light incident on the liquid crystal light valves 36R, 36G, and 36B are polarized. The light passes through the plate and is modulated and emitted by the liquid crystal light valves 36R, 36G, and 36B. The modulated red light, green light, and blue light are mixed by the cross dichroic prism 37 and are again emitted as white light. This emitted light becomes image light from the image display device 2. The image light emitted from the image display device 2 is projected onto the screen 4 by the projection lens 3, and an image is displayed on the screen 4.

(Method for manufacturing polarization conversion element)
Next, a method for manufacturing the polarization conversion element 23 configured as described above will be described. 6-8 is process drawing which shows the manufacturing process of the polarization conversion element 23. FIG.
As shown in FIG. 6, the base material 25 is formed in a parallelepiped prism shape, for example, by a light transmissive material such as glass. The surface 25a and the surface 25b of the base material 25 are formed flat.

  Next, as shown in FIG. 7, the reflective polarization conversion film 27 is formed on the surface 25 a of the substrate 25, and the polarization separation film 26 is formed on the surface 25 b of the substrate 25. The polarization separation film 26 is formed by stacking a plurality of layers made of a dielectric. Regarding the formation of the reflective polarization conversion film 27, the flat layer 27b is first formed on the surface 25a, and the grid layer 27c is formed on the flat layer 27b. For the grid layer 27c, a metal thin film is formed on the flat layer 27b to a predetermined thickness, and the metal thin film is patterned to form the convex portions 27d and the gaps 27e.

  Next, as shown in FIG. 8, the base structure 25 having the same shape and dimensions as the prism-shaped base material 25 described above is pasted onto the polarization separation film 26 to form the unit structure 40 of the polarization conversion element 23. . In the unit structure 40, the polarization separation film 26 and the reflective polarization conversion film 27 are formed so as to form a pair. A plurality of the unit structures 40 are bonded together to complete the polarization conversion element 23.

  According to the present embodiment, the reflection-type polarization conversion film 27 functions to convert at least a part of the polarization direction of the s-polarized light emitted from the polarization separation film 26 into the polarization direction of the p-polarization (function as a retardation plate). ) And the function of reflecting the p-polarized light whose polarization direction has been changed and emitting it from the polarization conversion element 23 (function as a reflection film), for example, a retardation plate and a reflection film in a conventional configuration, for example. It can be configured as a single member, and these need not be provided separately. Thereby, the number of parts of the polarization conversion element 23 can be reduced, and the complexity of the manufacturing process can be reduced. As a result, the complexity of the manufacturing process of the projector PJ1 is reduced.

  In addition, according to the present embodiment, the polarization separation film 26 and the reflective polarization conversion film 27 are provided inside the base material 25 that can transmit light. The position with the mold polarization conversion film 27 can be fixed. Thereby, it is possible to avoid a positional deviation between the polarization separation film 26 and the reflective polarization conversion film 27.

  In addition, one polarization separation film 26 and one reflection type polarization conversion film 27 make a pair, and a plurality of pairs of the polarization separation film 26 and the reflection type polarization conversion film 27 are provided. The number of pairs of the polarization separation film 26 and the reflective polarization conversion film 27 can be selected according to the cross-sectional area and density of light. This enables a wide range of designs.

  In the present embodiment, in particular, the reflective polarization conversion film 27 has a flat layer 27b made of a light-reflective material provided at least on the incident surface side of s-polarized light. By adjusting the direction, light can be reflected and emitted in a desired direction. In addition, the grid layer 27c is provided on the surface of the flat layer 27b and is made of a light-reflective material. The grid layer 27c has convex portions 27d extending in one direction at a predetermined pitch and a predetermined depth. In 27c, the polarization direction of s-polarized light can be converted to p-polarized light. As described above, the polarization direction conversion by the grid layer 27c and the light reflection / emission by the flat layer 27b can be performed by one member. For example, it is necessary to separately provide a retardation plate and a reflection film in the conventional configuration. Therefore, the number of parts of the polarization conversion element 23 can be reduced, and the complexity of the manufacturing process can be reduced.

  Further, in the conventional polarization conversion element, the retardation plate is configured to transmit the light whose polarization direction has been converted, and is often composed mainly of an organic material having a high light transmittance. For this reason, for example, when mounted on a projector or the like, burn-in may occur due to light emitted from the light source, which causes a problem in light resistance of the polarization conversion element. On the other hand, in the present embodiment, the reflective polarization conversion film 27 is configured to reflect the light whose polarization direction has been converted. Since the grid layer 27c and the flat layer 27b of the reflective polarization conversion film 27 are made of a light-reflective material, they can be made of an inorganic material such as metal. Thereby, burn-in can be avoided and the light resistance can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Similar to the first embodiment, in the following drawings, the scale is appropriately changed to make each member a recognizable size.
(Overall configuration of projector)
FIG. 9 is a schematic diagram showing the configuration of the projector PJ2 according to the present embodiment.
As shown in the figure, the projector PJ2 is a three-plate projector, and includes a light source 121 (121R, 121G, 121B), a uniform illumination system 122 (122R, 122G, 122B), and a liquid crystal light valve 124 (124R, 124G). , 124B), a dichroic prism 126, and a projection lens 127.

The light source 121 includes three different color light sources: a red LED (Light Emitting Diode) light source 121R that emits red light, a green LED light source 121G that emits green light, and a blue LED light source 121B that emits blue light. ing.
The uniform illumination system 122 uniformizes the illuminance distribution of the LED light emitted from the LED light sources 121R, 121G, and 121B.
The liquid crystal light valve 124 has a plurality of pixels and modulates the LED light emitted from the LED light sources 121R, 121G, and 121B in accordance with an image signal. Polarizers are attached to the light incident surface and the light exit surface of each of the liquid crystal light valves 124R, 124G, and 124B. A polarizing plate attached to the light incident surface transmits p-polarized light. Of the light beams from the LED light sources 121R, 121G, and 121B, only linearly polarized light in a predetermined direction passes through the incident side polarizing plate and enters the liquid crystal light valves 124R, 124G, and 124B.
The dichroic prism 126 is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine three color lights to form light representing a color image.
The projection lens 127 enlarges and projects the LED light synthesized by the cross dichroic prism 126.

(Configuration of uniform illumination system)
FIG. 10 is a diagram showing a detailed configuration of the uniform illumination system 122 (122R, 122G, 122B) described above.
As shown in the figure, the uniform illumination system 122 (122R, 122G, 122B) includes a lenticular lens array 131 (131R, 131G, 131B) and a polarization conversion element 132 (for deflecting light emitted from the lenticular lens array 131). 132R, 132G, 132B).

  The lenticular lens array 131 is an optical member that condenses the light emitted from the LED light source 121. The entrance surface 131a of the lenticular lens array 131 is flat, and a plurality of curved surfaces are formed on the exit surface 131b. Each curved surface is focused as a plurality of line-shaped light beams.

  The polarization conversion element 132 includes a base material 135 (131R, 131G, 131B), a polarization separation film 136 (136R, 136G, 136B) that is a polarization separation member, and a reflective polarization conversion film 137 (137R, which is a polarization conversion member). 137G, 137B). The polarization separation film 136 and the reflective polarization conversion film 137 are provided inside the base material 135, and the polarization separation film 136 and the reflective polarization conversion film 137 are 45 ° with respect to the light incident surface of the polarization conversion element 132. The tilted point is the same as that of the polarization conversion element of the first embodiment. In the present embodiment, the configuration of the reflective polarization conversion film 137 is different from that of the first embodiment, and the configurations of the other members are the same as those of the first embodiment.

  FIGS. 11A to 11C are diagrams showing the configuration of the reflective polarization conversion film 137 (137R, 137G, 137B) according to this embodiment. 11A shows the configuration of the reflective polarization conversion film 137R, FIG. 11B shows the configuration of the reflective polarization conversion film 137G, and FIG. 11C shows the configuration of the reflective polarization conversion film 137B. ing.

  The reflective polarization conversion films 137R, 137G, and 137B are mainly composed of lower flat layers 139R, 139G, and 139B and upper grid layers 140R, 140G, and 140B. The flat layers 139R, 139G, and 139B and the grid layers 140R, 140G, and 140B are layers mainly composed of a metal material having a high light reflectance such as silver, gold, and aluminum. In the grid layers 140R, 140G, and 140B, a plurality of convex portions 141R, 141G, and 141B provided on the side facing the light incident surface of the polarization separation film 136 extend in one direction, and the convex portions 141R, 141G, 141B, gaps 142R, 142G, 142B are provided. A grid portion is formed by the convex portions 141R, 141G, and 141B and the gaps 142R, 142G, and 142B. The extending direction of the grid portion is inclined with respect to the side direction of the reflective polarization conversion films 137R, 137G, and 137B provided in a rectangular shape in plan view.

  The widths (dimensions in the direction orthogonal to the extending direction) of the convex portions 141R, 141G, and 141B are d2 (for example, d2 = 70 nm), and here, d1 = d2 = 70 nm. Therefore, the convex portions 141R, 141G, and 141B are arranged at a pitch of 140 nm as in the first embodiment.

  As shown in FIG. 11A, the grid layer 140R of the reflective polarization conversion film 137R has a height (predetermined depth of the grid portion: grid depth) h1 of about 120 nm to 140 nm from the flat layer 139R. It is formed as follows. As shown in FIG. 11B, the grid layer 140G of the reflective polarization conversion film 137G is formed so that the height (grid depth) h2 from the flat layer 139G is about 90 nm to 110 nm. As shown in FIG. 11C, the grid layer 140B of the reflective polarization conversion film 137B is formed so that the height (grid depth) h3 from the flat layer 139B is about 60 nm to 75 nm.

  Similar to the first embodiment, the reflective polarization conversion films 137R, 137G, and 137B are oriented at an elevation angle of 45 ° with respect to the surfaces of the flat layers 139R, 139G, and 139B, and are formed on the flat layers 139R, 139G, and 139B. The light is arranged so that light is incident on the surface from the direction of about 50 ° to 60 ° with respect to the direction orthogonal to the extending direction of the grid portion. In the present embodiment, the flat layer 139 and the grid layer 140 of the reflective polarization conversion film 137 have silver as a main component. However, when gold, aluminum, or the like is a main component, the optimum value of this angle differs. . This will be described in detail in [Example].

(Projector operation)
Next, the operation of projector PJ2 configured as described above will be described.
The red light emitted from the light source 121R of the projector PJ2, the green light emitted from 121G, and the blue light emitted from 121B are mixed with a p-polarized light component and an s-polarized light component. This colored light enters the uniform illumination systems 122R, 122G, 122B from the respective light sources 121R, 121G, 121G. Each color light incident on the uniform illumination systems 122R, 122G, and 122B has a uniform luminance distribution by the lenticular lens array 131, and the polarization direction is the same as that of the first embodiment by the polarization conversion elements 132R, 132G, and 132B (see FIG. 5). Is converted to p-polarized light and enters the liquid crystal light valves 124R, 124G, and 124B.

  Since the polarizing plate on the incident surface side of the liquid crystal light valves 124R, 124G, and 124B transmits p-polarized light, the incident red light, green light, and blue light are modulated by the liquid crystal light valves 124R, 124G, and 124B. It is injected. The modulated red light, green light, and blue light are mixed by the cross dichroic prism 126 and emitted as white light. The emitted light is projected onto the screen 110 by the projection lens 127, and an image is displayed on the screen 110.

  According to this embodiment, the reflective polarization conversion films 137R, 137G, and 137B convert at least a part of the polarization directions of the s-polarized light emitted from the polarization separation films 136R, 136G, and 136B to the polarization direction of p-polarization. Since it has both a function (function as a retardation plate) and a function of reflecting p-polarized light whose polarization direction has been converted and emitting it from the polarization conversion element 132 (function as a reflective film), for example, in the conventional configuration The retardation plate and the reflective film can be configured as one member, and it is not necessary to provide them separately. Thereby, the number of parts of the polarization conversion elements 132R, 132G, and 132B can be reduced, and the complexity of the manufacturing process can be reduced. As a result, the complexity of the manufacturing process of the projector PJ2 is reduced.

  Further, the present inventors determine the optimum value of a predetermined depth and the extension of the grid portion on the incident surface according to the material of the reflective polarization conversion film 137 and the wavelength of the s-polarized light incident on the reflective polarization conversion film 137. It was found that the optimum value of the incident angle of s-polarized light with respect to the direction orthogonal to the direction is different. Based on this, in this embodiment, the reflective polarization conversion film 137 is made of silver, and the grid depth h2 of the grid layer 140G is set so that the grid depth h1 of the grid layer 140R is in the range of 120 nm to 140 nm. The grid layers 140R, 140G, and 140B are designed so that the grid depth h3 of the grid layer 140B is in the range of 60 nm to 75 nm so that the grid depth 140 is in the range of 90 nm to 110 nm. Since the optimum value of the incident angle of the s-polarized light with respect to the direction orthogonal to the extending direction of the portion is about 50 ° to 60 °, these values can be appropriately selected according to the wavelength of the colored light, and the light utilization efficiency Can be increased as much as possible.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. Similar to the first embodiment, in the following drawings, the scale is appropriately changed to make each member a recognizable size.
(Overall configuration of projector)
FIG. 12 is a schematic diagram showing the configuration of the projector PJ3 according to the present embodiment.
As shown in the figure, the projector PJ3 includes a light source 210, a uniform illumination system 220, a color modulation unit 230, and a projection lens 240.
The light source 210 includes a lamp 211 that emits white light, such as an ultra-high pressure mercury lamp or a xenon lamp, and a reflector 212 that reflects and collects the white light emitted from the lamp 211.
The uniform illumination system 220 is an optical system that makes the luminance distribution of white light from the light source 210 uniform, and includes a polarization conversion element 221, a reflection mirror 222, an aspheric lens 223, a first lens array 224, and a second lens array 224. A lens array 225 and a condenser lens 226 are provided.

  The polarization conversion element 221 is disposed between the light source 210 and the reflection mirror 222, and is an optical element that converts the polarization direction of white light from the light source 210 and aligns it in one direction. The first lens array 224 and the second lens array 225 are disposed on the light exit side of the reflection mirror 222. The first lens array 224 and the second lens array 225 are optical members that are made of, for example, fly-eye lenses and the like, and uniformize the light luminance distribution. The condenser lens 226 is a lens arranged on the light exit side of the second lens array 225.

  The color modulation unit 230 is a part that modulates the luminances of the three primary colors red (R), green (G), and blue (B) in the wavelength region of white light emitted from the uniform illumination system 220. Two dichroic mirrors 231a, 231b, three mirrors 232a, 232b, 232c, five field lenses (lens 233, relay lens 234, collimating lenses 235R, 235G, 235B), three liquid crystal light valves 236R, 236G, 236B and a cross dichroic prism 237.

  The dichroic mirrors 231a and 231b are optical members for separating (spectrancing) white light into RGB three primary color lights. The dichroic mirror 231a is disposed on the light emission side of the condenser lens 226 so as to be inclined by 45 ° with respect to the light traveling direction, and a dichroic film having a property of reflecting blue light and green light and transmitting red light. It is configured to be attached to a light transmissive substrate such as a glass plate. The dichroic mirror 231b is provided on the light reflection side of the dichroic mirror 231a and is inclined by 45 ° with respect to the light traveling direction. The dichroic film having a property of reflecting green light and transmitting blue light is a glass plate. It is configured to be attached to a light transmissive substrate such as.

  The lens 233 and the relay lens 234 are optical members that transmit light transmitted through the dichroic mirror 231b to the collimating lens 235B. The lens 233 is disposed on the light transmission side of the dichroic mirror 231b, and is provided to allow light to enter the relay lens 234 efficiently.

  The collimating lenses 235R, 235G, and 235B are arranged on the light incident side of the corresponding liquid crystal light valves 236R, 236G, and 236B, and are convex lenses that substantially collimate the color lights incident on the liquid crystal light valves 236R, 236G, and 236B. is there.

  The liquid crystal light valves 236R, 236G, and 236B are active matrix type liquid crystal display elements, and polarizing plates are attached to the light incident surface and the light emission surface, respectively. The polarizing plate attached to the light incident surface transmits p-polarized light. The liquid crystal light valves 236R, 236G, and 236B have a normally white mode in which a white / bright (transmission) state is applied when no voltage is applied, and a black / dark (non-transmission) state when a voltage is applied, or vice versa. The gradation between light and dark is analog controlled according to the given control value.

  The cross dichroic prism 237 has a configuration in which four right-angle prisms are bonded together. A dielectric multilayer film (blue light reflection dichroic film 237a) that reflects blue light is formed on the bonding surface of the right-angle prisms, and a red color. A dielectric multilayer film (red light reflecting dichroic film 237b) that reflects light is formed.

(Configuration of polarization conversion element)
Next, the configuration of the polarization conversion element 221 described above will be described. FIG. 13 is a diagram showing the configuration of the light source 210 and the polarization conversion element 221 of the projector PJ3 shown in FIG.
As shown in the figure, the polarization conversion element 221 is mainly composed of a polarization separation member 227 and a reflective polarization conversion film (polarization conversion member) 228. One polarization separation member 227 and one reflection type polarization conversion film 228 are provided, and the pair of polarization separation member 227 and reflection type polarization conversion film 228 constitute a polarization conversion element 221.

  The polarization separation film 227 is disposed so as to be inclined at an angle α (for example, α = 45 °) with respect to the light incident surface of the polarization conversion element 221. For example, p-polarized light (first light component) and s-polarized light among white light. (Second light component). The polarization separation film 227 transmits the separated p-polarized light and emits it in the same direction as the incident direction (first direction), and directs the separated s-polarized light in the direction of the reflective polarization conversion film 228 (second direction). To reflect.

  The reflection-type polarization conversion film 228 is disposed in the reflection direction of the polarization separation film 227 and is provided to be inclined at an angle β (for example, β = 45 °) with respect to the traveling direction of white light from the polarization separation member 227. Yes. FIG. 14 is a cross-sectional view showing the configuration of the reflective polarization conversion film 228. As shown in FIG. 14, the reflective polarization conversion film 228 is mainly composed of a base material 228a, a flat layer 228b, and a grid layer 228c.

The base material 228a is a member made of a material having a certain rigidity, such as glass, quartz, or plastic.
The flat layer 27b is provided on the surface of the base material 228a, and is a layer mainly composed of a metal material having a high light reflectance, here silver. The flat layer 228b has a thickness sufficient to reflect light without transmitting it.

  The grid layer 228c is a layer provided on the surface of the flat layer 228b on the side facing the polarization separation film 227, and is mainly composed of a plurality of convex portions 228d. Each convex portion 228d is provided on the flat layer 228b so as to extend in the same direction, and is arranged with a predetermined interval d3 (for example, d1 = 70 nm) (gap 228e). The flat layer 228b is exposed in the gap 228e. A grid is formed by the convex portion 228d and the gap 228e.

  The width of the convex portion 228d (dimension in the direction orthogonal to the extending direction) is d4 (for example, d2 = 70 nm), and here, d3 = d4 = 70 nm. Therefore, the convex portions 228d are arranged at a pitch of 140 nm. The convex portion 228d is formed so that the height (dimension in the protruding direction: grid depth) h4 from the flat layer 228b is in the range of 60 nm to 140 nm, for example.

  The reflection-type polarization conversion film 228 is disposed with an inclination of 45 ° with respect to the incident direction of the s-polarized light, and the grid extends in a direction inclined with respect to the optical axis of the s-polarized light incident on itself. It is arranged to exist.

(Projector operation)
The white light emitted from the lamp 211 of the projector PJ3 configured as described above and the white light collected by the reflector 212 enter the uniform illumination system 220 from the light source 210. The white light incident on the uniform illumination system 220 is converted into p-polarized light by the polarization conversion element 221 as in the first embodiment (see FIG. 5) and is incident on the first lens array 224. The white light has a uniform luminance distribution by the first lens array 224 and the second lens array 225, is condensed by the condenser lens 226, and is emitted to the color modulator 230.

  Of the white light incident on the color modulator 230, red light is transmitted through the dichroic mirror 231a, and green light and blue light are reflected by the dichroic mirror 231a. The red light that has passed through the dichroic mirror 231a is reflected by the reflection mirror 232a, is approximately collimated by the collimating lens 235R, and enters the liquid crystal light valve 236R. The green light and blue light reflected by the dichroic mirror 231a enter the dichroic mirror 231b. Of these, blue light passes through the dichroic mirror 231b, and green light is reflected by the dichroic mirror 231b. The green light reflected by the dichroic mirror 231b is substantially collimated by the collimating lens 235G and enters the liquid crystal light valve 236G. The blue light transmitted through the dichroic mirror 231b is incident on the collimating lens 235B via the lens 233, the reflecting mirror 232b, the relay lens 234, and the reflecting mirror 232c, and is substantially collimated and enters the liquid crystal light valve 236B.

  Since the polarizing plates on the incident surface side of the liquid crystal light valves 236R, 236G, and 236B transmit p-polarized light, the red light, green light, and blue light incident on the liquid crystal light valves 236R, 236G, and 236B are the liquid crystal light valves. 236R, 236G, and 236B are modulated and emitted. The modulated red light, green light, and blue light are mixed by the cross dichroic prism 237 and emitted again as white light. The emitted light is projected onto the screen 250 by the projection lens 240, and an image is displayed on the screen 250.

  According to this embodiment, one polarization separation member 227 and one reflection type polarization conversion film 228 are provided, and the pair of polarization separation member 227 and reflection type polarization conversion film 228 constitute a polarization conversion element 221. Therefore, the number of parts of the polarization conversion element 221 can be extremely reduced.

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
For example, in each of the above embodiments, the polarization separation film (polarization separation member) has been described as being configured by a dielectric layer. However, the present invention is not limited to this, and for example, a wire grid polarizer may be used. By using the wire grid polarizing plate, the wire grid of the polarization separation film can be formed in the process of forming the reflective polarization conversion film, and therefore the number of processes can be reduced. Thereby, manufacture of a polarization conversion element can be made easy.

  In the said embodiment, although the material was made common in the flat layer and a grid layer, it is also possible to combine a different material. In the second embodiment, the materials of the reflective polarization conversion films used for red light, green light, and blue light may be different from each other.

  In this example, in the case of using the polarization conversion element in the above embodiment, the light intensity of the light incident on the reflective polarization conversion film (incident light) and the light reflected by the reflective polarization conversion film (reflected light) is shown. The ratio (light intensity of reflected light / light intensity of incident light) was obtained by simulation. In this simulation, the pitch of the convex portions of the reflective polarization conversion film is 140 nm (convex width 70 nm, convex spacing 70 nm), and the main components, grid depth, and angle of the reflective polarization conversion film (flat layer and grid layer). Of the reflected light (blue light, green light, red light) when φ is changed, the component in the Y′-axis direction (main component of s-polarized light) and the component in the Z′-axis direction (p-polarized light) in the above embodiment. The light intensity of the main component was measured by simulation. Here, light having a wavelength of 440 nm is used as blue light, light having a wavelength of 532 nm is used as green light, and light having a wavelength of 660 nm is used as red light. 15 to 20 are graphs showing the results of this simulation. The vertical axis of each graph represents the light intensity (relative value when the incident light is 1), and the horizontal axis represents the grid depth (unit: nm).

1. In the case of silver (Ag)
15 and 16 show the results when the main component of the reflective polarization conversion film is silver.
<In the case of blue light>
FIGS. 15A to 15C and FIGS. 16A to 16C are graphs showing measurement results for blue light (wavelength 440 nm). 15A shows an angle φ = 30 °, FIG. 15B shows an angle φ = 45 °, FIG. 15C shows an angle φ = 50 °, and FIG. 16A shows an angle φ. = 55 °, FIG. 16B shows the case where the angle φ = 60 °, and FIG. 16C shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 60 to 75 nm. This maximum value is about 0.40 (when the grid depth is about 65 nm). On the other hand, the intensity ratio of s-polarized light shows the minimum value when the grid depth is about 60 to 75 nm, contrary to the intensity ratio of p-polarized light. This minimum value is about 0.40 (when the grid depth is about 65 nm).

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 60 to 75 nm. This maximum value is about 0.63 (when the grid depth is about 65 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.09 when the grid depth is about 65 nm. From this graph, it can be seen that in the case of φ = 45 °, the degree of polarization is higher in each stage than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 60 to 75 nm. This maximum value is about 0.65 (when the grid depth is about 65 nm), which is slightly increased compared to the case of φ = 45 °. The minimum value of the intensity ratio of s-polarized light is about 0.02 when the grid depth is about 65 nm. From this graph, it can be seen that the degree of polarization is higher when φ = 50 ° than when φ = 30 ° and 45 °.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 60 to 75 nm. This maximum value is about 0.61 (when the grid depth is about 65 nm), which is larger than φ = 30 ° and 45 °, but smaller than φ = 50 °. . The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 65 nm. From this graph, when φ = 55 °, almost all of the s-polarized light is converted to p-polarized light, and the degree of polarization is larger than when φ = 30 °, 45 °, and 50 °. It can be seen that the light intensity of the p-polarized light is slightly smaller than when φ = 50 °.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 60 to 75 nm. This maximum value is about 0.54 (when the grid depth is about 65 nm), which is larger than the case of φ = 30 ° and 45 °, but smaller than that of φ = 50 ° and 55 °. It has become. The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 65 nm. From this graph, when φ = 60 °, almost all of the s-polarized light is converted to p-polarized light, and the degree of polarization is larger than when φ = 30 ° and 45 °. It can be seen that the light intensity of the p-polarized light is smaller than the cases of 50 ° and 55 °.

  At φ = 75 °, the intensity ratio of p-polarized light is greatly reduced as compared with the above cases, and it can be seen that the light intensity of p-polarized light is reduced.

  From these facts, it can be said that for blue light, the value of φ is preferably larger than 30 ° and smaller than 75 °. For example, it can be said that φ = 50 ° to 60 ° and the grid depth is preferably about 60 nm to 75 nm.

<For green light>
FIGS. 15D to 15F and FIGS. 16D to 16F are graphs showing measurement results for green light (wavelength 532 nm). 15 (d) shows an angle φ = 30 °, FIG. 15 (e) shows an angle φ = 45 °, FIG. 15 (f) shows an angle φ = 50 °, and FIG. 16 (d) shows an angle φ. FIG. 16E shows the case where the angle φ = 60 °, and FIG. 16F shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 nm to 110 nm. This maximum value is about 0.45 (when the grid depth is about 100 nm). The intensity ratio of s-polarized light shows the minimum value when the grid depth is about 100 nm. This minimum value is about 0.40.

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 nm to 110 nm. This maximum value is about 0.78 (when the grid depth is about 100 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.09 when the grid depth is about 100 nm. From this graph, it can be seen that in the case of φ = 45 °, the degree of polarization is higher in each stage than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 nm to 110 nm. This maximum value is about 0.84 (when the grid depth is about 100 nm), which is slightly increased as compared with the cases of φ = 30 ° and 45 °. The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 65 nm. From this graph, it can be seen that the degree of polarization is higher when φ = 50 ° than when φ = 30 ° and 45 °.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 nm to 110 nm. This maximum value is about 0.82 (when the grid depth is about 100 nm), which is larger than when φ = 30 ° and 45 °, but smaller than when φ = 50 °. . The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 100 nm. From this graph, when φ = 55 °, almost all of the s-polarized light is converted to p-polarized light, and the degree of polarization is larger than when φ = 30 ° and 45 °. It can be seen that the light intensity of p-polarized light is smaller than that at 50 °.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 nm to 110 nm. This maximum value is about 0.78 (when the grid depth is about 100 nm), which is larger than the case of φ = 30 ° and 45 °, but smaller than the case of φ = 50 ° and 55 °. It has become. The minimum value of the intensity ratio of s-polarized light is about 0.04 when the grid depth is about 100 nm. From this graph, in the case of φ = 60 °, the degree of polarization is larger than that in the case of φ = 30 ° and 45 °, but the degree of polarization is larger than that in the case of φ = 50 ° and 55 °. It can be seen that the light intensity of p-polarized light is small.

  At φ = 75 °, the intensity ratio of p-polarized light is significantly reduced compared to the above cases, and it can be seen that the light intensity of p-polarized light is reduced.

  From these facts, it can be said that for green light, the value of φ is preferably larger than 30 ° and smaller than 75 °. For example, it can be said that it is more preferable that φ = 50 ° to 60 ° and the grid depth be about 90 nm to 110 nm.

<In the case of red light>
FIGS. 15G to 15I and FIGS. 16G to 16I are graphs showing measurement results for red light (wavelength 660 nm). 15 (g) shows an angle φ = 30 °, FIG. 15 (h) shows an angle φ = 45 °, FIG. 15 (i) shows an angle φ = 50 °, and FIG. 16 (g) shows an angle φ. In the case of = 55 °, FIG. 16 (h) shows the case of angle φ = 60 °, and FIG. 16 (i) shows the case of angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm and about 390 nm to 410 nm. This maximum value is about 0.48 (when the grid depth is about 120 nm) at the maximum. Contrary to the intensity ratio of p-polarized light, the intensity ratio of s-polarized light shows a minimum value when the grid depth is about 110 nm to 130 nm and about 390 nm to 410 nm. This minimum value is a minimum of 0.45 (when the grid depth is about 120 nm).

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm and about 400 nm to 420 nm. This maximum value is about 0.82 at the maximum (when the grid depth is about 120 nm), which is a large value compared to the case where φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.09 when the grid depth is about 120 nm. From this graph, it can be seen that the degree of polarization is higher in the case of φ = 45 ° than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 120 nm to 140 nm and about 410 nm to 430 nm. This maximum value is about 0.88 at the maximum (when the grid depth is about 130 nm), which is slightly increased compared to the case of φ = 30 ° and 45 °. The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 130 nm. From this graph, it can be seen that the degree of polarization is higher when φ = 50 ° than when φ = 30 ° and 45 °.

  At φ = 55 °, the intensity ratio of p-polarized light has the maximum value when the grid depth is about 120 nm to 140 nm and about 420 nm to 440 nm. The maximum value is about 0.88 (when the grid depth is about 130 nm), which is almost the same as when φ = 50 °. The minimum value of the intensity ratio of s-polarized light is almost zero when the grid depth is about 130 nm. From this graph, it can be seen that in the case of φ = 55 °, almost all of the s-polarized light is converted to p-polarized light, and the light intensity of the p-polarized light is equivalent to that in the case of φ = 50 °.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 120 nm to 150 nm and about 440 nm to 460 nm. This maximum value is about 0.82 (when the grid depth is about 130 nm), which is larger than the case of φ = 30 °, which is equivalent to the case of φ = 45 °, and φ = 50 °. , It is smaller than the case of 55 °. The minimum value of the intensity ratio of s-polarized light is about 0.04 when the grid depth is about 130 nm. From this graph, in the case of φ = 60 °, the degree of polarization is larger than in the case of φ = 30 ° and 45 °, but compared to the case of φ = 45 °, 50 °, and 55 °, It can be seen that the degree of polarization is small and the light intensity of p-polarized light is small.

  At φ = 75 °, the intensity ratio of p-polarized light is significantly reduced compared to the above cases, and it can be seen that the light intensity of p-polarized light is reduced.

  From these facts, it can be said that it is preferable that the value of φ is larger than 30 ° and smaller than 75 ° for red light. For example, it can be said that φ = 50 ° to 60 ° and the grid depth is preferably about 120 nm to 140 nm.

2. For aluminum (Al)
17 and 18 show the results when the main component of the reflective polarization conversion film is aluminum.
<In the case of blue light>
FIGS. 17A to 17C and FIGS. 18A to 18C are graphs showing measurement results for blue light (wavelength 440 nm). 17A shows an angle φ = 30 °, FIG. 17B shows an angle φ = 45 °, FIG. 17C shows an angle φ = 50 °, and FIG. 18A shows an angle φ. 18B, FIG. 18B shows a case where the angle φ = 60 °, and FIG. 18C shows a case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 100 to 120 nm. This maximum value is about 0.38 (when the grid depth is about 110 nm). Contrary to the intensity ratio of p-polarized light, the intensity ratio of s-polarized light shows a minimum value when the grid depth is about 100 to 120 nm. This minimum value is about 0.48 (when the grid depth is about 110 nm). From this graph, it can be seen that at φ = 30 °, the intensity ratio of p-polarized light is low and the degree of conversion of s-polarized light to p-polarized light (polarization degree) is low.

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 90 to 110 nm. This maximum value is about 0.65 (when the grid depth is about 100 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.14 when the grid depth is about 100 nm. From this graph, it can be seen that in the case of φ = 45 °, the degree of polarization is higher in each stage than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 95 to 115 nm. This maximum value is about 0.63 (when the grid depth is about 105 nm), which is slightly smaller than the case of φ = 45 °. The minimum value of the intensity ratio of s-polarized light is about 0.06 when the grid depth is about 105 nm. From this graph, when φ = 50 °, the degree of polarization is higher than that when φ = 30 ° and 45 °, but the intensity ratio of p-polarized light is higher than that when φ = 45 °. You can see that it is getting smaller.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 100 to 120 nm. This maximum value is about 0.56 (when the grid depth is about 110 nm), which is larger than when φ = 30 °, but smaller than when φ = 45 ° and 50 °. . The minimum value of the intensity ratio of s-polarized light is about 0.04 when the grid depth is about 110 nm. From this graph, in the case of φ = 55 °, the degree of polarization is larger than in the case of φ = 30 °, 45 °, and 50 °, but p is higher than that in the case of φ = 45 ° and 50 °. It can be seen that the light intensity of polarized light is small.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 100 to 120 nm. This maximum value is about 0.44 (when the grid depth is about 110 nm). The minimum value of the intensity ratio of s-polarized light is about 0.02 when the grid depth is about 110 nm. From this graph, when φ = 60 °, the degree of polarization is larger than when φ = 30 °, 45 °, 50 °, and 55 °, but φ = 45 °, 50 °, and 55 °. It can be seen that the light intensity of p-polarized light is smaller than in the case of.

  At φ = 75 °, the intensity ratio of p-polarized light is greatly reduced as compared with the above cases, and it can be seen that the light intensity of p-polarized light is reduced. When the grid depth is 100 nm, the minimum value of the light intensity of s-polarized light is almost 0, and it can be seen that the degree of polarization is large.

  From these facts, it can be said that for blue light, the value of φ is preferably larger than 30 ° and smaller than 75 °. For example, it can be said that φ = 45 ° to 60 ° and the grid depth is preferably about 90 nm to 120 nm.

<For green light>
FIGS. 17D to 17F and FIGS. 18D to 18F are graphs showing measurement results for green light (wavelength 532 nm). 17D shows an angle φ = 30 °, FIG. 17E shows an angle φ = 45 °, FIG. 17F shows an angle φ = 50 °, and FIG. 18D shows an angle φ. FIG. 18E shows the case where the angle φ = 60 °, and FIG. 18F shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 100 nm to 120 nm. This maximum value is about 0.38 (when the grid depth is about 110 nm). The intensity ratio of s-polarized light shows a minimum value when the grid depth is about 110 nm. This minimum value is about 0.49.

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.44 (when the grid depth is about 120 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.22 when the grid depth is about 120 nm. From this graph, it can be seen that in the case of φ = 45 °, the degree of polarization is higher in each stage than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 120 nm to 130 nm. This maximum value is about 0.42 (when the grid depth is about 125 nm), which is slightly increased compared to the case of φ = 30 °, but decreased compared to the case of φ = 45 °. Yes. The intensity ratio of s-polarized light is about 0.16 when the grid depth is about 120 nm. From this graph, it can be seen that when φ = 50 °, the degree of polarization is higher than when φ = 30 ° and 45 °, but the intensity ratio of p-polarized light is reduced.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 100 nm to 130 nm. This maximum value is about 0.45 (when the grid depth is about 115 nm), which is larger than that when φ = 30 °, 45 °, and 50 °. The minimum value of the intensity ratio of s-polarized light is about 0.06 when the grid depth is about 110 nm. From this graph, it can be seen that in the case of φ = 55 °, the degree of polarization is higher than in the above case, and the light intensity of p-polarized light is increased.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.42 (when the grid depth is about 120 nm). The minimum value of the intensity ratio of s-polarized light is about 0.02 when the grid depth is about 110 nm. From this graph, in the case of φ = 60 °, the degree of polarization is larger than in any of the above cases, but the light intensity of p-polarized light is smaller than in the case of φ = 50 ° and 55 °. I can read that

  It can be seen that at φ = 75 °, the intensity ratio of p-polarized light is greatly reduced as compared with the above cases.

  From these facts, it can be said that for green light, the value of φ is preferably larger than 30 ° and smaller than 75 °. For example, it can be said that φ = 45 ° to 60 ° and a grid depth of about 100 nm to 130 nm are more preferable.

<In the case of red light>
17 (g) to (i) and FIGS. 18 (g) to (i) are graphs showing measurement results for red light (wavelength 660 nm). 17 (g) shows an angle φ = 30 °, FIG. 17 (h) shows an angle φ = 45 °, FIG. 17 (i) shows an angle φ = 50 °, and FIG. 18 (g) shows an angle φ. = 55 °, FIG. 18 (h) shows the case where the angle φ = 60 °, and FIG. 18 (i) shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 150 nm to 160 nm. This maximum value is about 0.31 (when the grid depth is about 155 nm). The intensity ratio of s-polarized light shows a minimum value when the grid depth is about 150 nm to 160 nm. This minimum value is about 0.49 (when the grid depth is about 155 nm).

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 140 nm to 160 nm. This maximum value is about 0.42 (when the grid depth is about 150 nm), which is a larger value than that when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.22 when the grid depth is about 150 nm. From this graph, it can be seen that the degree of polarization is higher in the case of φ = 45 ° than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 140 nm to 150 nm. This maximum value is about 0.49 (when the grid depth is about 145 nm), which is slightly increased as compared with φ = 30 ° and 45 °. The intensity ratio of s-polarized light is about 0.15 when the grid depth is about 145 nm. From this graph, it can be seen that the degree of polarization is higher when φ = 50 ° than when φ = 30 ° and 45 °.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 130 nm to 150 nm. The maximum value is about 0.48 (when the grid depth is about 140 nm), which is larger than the case where φ = 50 °. The intensity ratio of s-polarized light is about 0.06 when the grid depth is about 140 nm. From this graph, it can be seen that in the case of φ = 55 °, the degree of polarization is higher and the light intensity of p-polarized light is higher than in the above case.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 130 nm to 150 nm. The maximum value is about 0.48 (when the grid depth is about 140 nm). The intensity ratio of s-polarized light is almost 0 when the grid depth is about 140 nm. From this graph, in the case of φ = 60 °, the degree of polarization is larger than in the above case, but the light intensity of p-polarized light is slightly smaller than in the case of φ = 55 °. I can read.

  It can be seen that at φ = 75 °, the intensity ratio of p-polarized light is reduced compared to the above cases, and the light intensity of p-polarized light is significantly reduced.

  From these facts, it can be said that it is preferable that the value of φ is larger than 30 ° and smaller than 75 ° for red light. For example, it can be said that it is more preferable that φ = 45 ° to 60 ° and the grid depth be about 130 nm to 160 nm.

3. For gold (Au)
19 and 20 show results when the main component of the reflective polarization conversion film is gold.
<In the case of blue light>
FIGS. 19A to 19C and FIGS. 20A to 20C are graphs showing measurement results for blue light (wavelength 440 nm). 19A shows an angle φ = 30 °, FIG. 19B shows an angle φ = 45 °, FIG. 19C shows an angle φ = 50 °, and FIG. 20A shows an angle φ. = 55 °, FIG. 20B shows the case where the angle φ = 60 °, and FIG. 20C shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  The intensity ratio of s-polarized light gradually decreases from φ = 30 ° to 75 °, whereas the intensity ratio of p-polarized light is less than 0.1. From these graphs, it can be seen that the degree of polarization increases as the value of φ increases, but the intensity of p-polarized light decreases.

<For green light>
FIGS. 19D to 19F and FIGS. 20D to 20F are graphs showing measurement results for green light (wavelength 532 nm). 15D shows an angle φ = 30 °, FIG. 19E shows an angle φ = 45 °, FIG. 19F shows an angle φ = 50 °, and FIG. 20D shows an angle φ. = 55 °, FIG. 20 (e) shows the case where the angle φ = 60 °, and FIG. 20 (f) shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 75 nm to 115 nm. This maximum value is about 0.28 (when the grid depth is about 90 nm). The intensity ratio of s-polarized light shows a minimum value when the grid depth is about 90 nm. This minimum value is about 0.41.

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 75 nm to 115 nm. This maximum value is about 0.42 (when the grid depth is about 90 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.13 when the grid depth is about 90 nm. From this graph, it can be seen that in the case of φ = 45 °, the degree of polarization is higher in each stage than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 75 nm to 105 nm. This maximum value is about 0.42 (when the grid depth is about 85 nm). The intensity ratio of s-polarized light is about 0.06 when the grid depth is about 85 nm. From this graph, when φ = 50 °, the degree of polarization is higher than when φ = 30 ° and 45 °, and the intensity of p-polarized light is almost the same as when φ = 45 °. Can be read.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 75 nm to 105 nm. This maximum value is about 0.40 (when the grid depth is about 80 nm). The intensity ratio of s-polarized light is about 0.02 when the grid depth is about 80 nm. From this graph, in the case of φ = 55 °, the degree of polarization is higher than in the above case, but the light intensity of p-polarized light is lower than in the case of φ = 45 ° and 50 °. I can read.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 75 nm to 105 nm. This maximum value is about 0.35 (when the grid depth is about 85 nm). The intensity ratio of s-polarized light is almost 0 when the grid depth is about 85 nm. From this graph, in the case of φ = 60 °, the degree of polarization is higher than in any of the above cases, but the light intensity of p-polarized light is smaller than in the case of φ = 50 ° and 55 °. I can read that

  It can be seen that at φ = 75 °, the intensity ratio of p-polarized light is greatly reduced as compared with the above cases.

  From these facts, it can be said that for green light, the value of φ is preferably larger than 30 ° and smaller than 75 °. For example, it can be said that φ = 50 ° to 60 ° and a grid depth of about 75 nm to 105 nm are more preferable.

<In the case of red light>
19 (g) to (i) and FIGS. 20 (g) to (i) are graphs showing measurement results for red light (wavelength 660 nm). 19 (g) shows an angle φ = 30 °, FIG. 19 (h) shows an angle φ = 45 °, FIG. 19 (i) shows an angle φ = 50 °, and FIG. 20 (g) shows an angle φ. = 55 °, FIG. 20 (h) shows the case where the angle φ = 60 °, and FIG. 20 (i) shows the case where the angle φ = 75 °. In each figure, the solid line is the intensity ratio of p-polarized light (Z′-axis direction), and the broken line is the intensity ratio of s-polarized light (Y′-axis direction).

  At φ = 30 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.45 (when the grid depth is about 120 nm). The intensity ratio of s-polarized light is about 0.45 when the grid depth is about 120 nm.

  At φ = 45 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.76 (when the grid depth is about 120 nm), which is a larger value than when φ = 30 °. The minimum value of the intensity ratio of s-polarized light is about 0.10 when the grid depth is about 120 nm. From this graph, it can be seen that the degree of polarization is higher in the case of φ = 45 ° than in the case of φ = 30 °.

  At φ = 50 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.82 (when the grid depth is about 120 nm), which is an increase compared to the case where φ = 30 ° and 45 °. The intensity ratio of s-polarized light is about 0.01 when the grid depth is about 120 nm. From this graph, it can be seen that the degree of polarization is higher when φ = 50 ° than when φ = 30 ° and 45 °.

  At φ = 55 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.81 at the maximum (when the grid depth is about 120 nm), which is slightly smaller than when φ = 50 °. The intensity ratio of s-polarized light is almost 0 when the grid depth is about 120 nm. From this graph, it can be seen that the degree of polarization is higher in the case of φ = 55 ° than in the above case.

  At φ = 60 °, the intensity ratio of p-polarized light has a maximum value when the grid depth is about 110 nm to 130 nm. This maximum value is about 0.76 (when the grid depth is about 120 nm). The intensity ratio of s-polarized light is about 0.03 when the grid depth is about 120 nm. From this graph, when φ = 60 °, the degree of polarization and the intensity ratio of p-polarized light are larger than when φ = 30 ° and 45 °, but when φ = 50 ° and 55 °. In comparison, it can be seen that the degree of polarization and the intensity ratio of p-polarized light are small.

  It can be seen that at φ = 75 °, the intensity ratio of p-polarized light is reduced compared to the above cases, and the light intensity of p-polarized light is significantly reduced.

  From these facts, it can be said that it is preferable that the value of φ is larger than 30 ° and smaller than 75 ° for red light. For example, it can be said that it is more preferable that φ = 50 ° to 60 ° and the grid depth be about 110 nm to 130 nm.

1 is a diagram showing a configuration of a projector according to a first embodiment of the invention. The figure which shows the structure of the light source and uniform illumination system of a projector. The figure which shows the structure of a polarization conversion element. The figure which shows the structure of a reflection type polarization converting film. The figure which shows the mode of the polarization conversion in a reflection type polarization converting film. The figure which shows the mode of the manufacturing process of a polarization converting element. The process drawing. The process drawing. The figure which shows the structure of the projector which concerns on 2nd Embodiment of this invention. The figure which shows the structure of the light source and uniform illumination system of a projector. The figure which shows the structure of a reflection type polarization converting film. The figure which shows the structure of the projector which concerns on 3rd Embodiment of this invention. The figure which shows the structure of a light source and a polarization conversion element. The figure which shows the structure of a reflection type polarization converting film. The graph which shows the characteristic of a reflection type polarization converting film. Same graph. Same graph. Same graph. Same graph. Same graph.

Explanation of symbols

PJ1, PJ2, PJ3 ... Projector 10 ... Light source 20 ... Uniform illumination system 23 ... Polarization conversion element 26 ... Polarization separation film 27 ... Reflection type polarization conversion film 27b ... Flat layer 27c ... Grid layer 27d ... Protrusion 27e ... Gap 30 ... Color Modulator 31a, 31b ... Dichroic mirror 37 ... Cross dichroic prism 110 ... Screen 121 (121R, 121G, 121B) ... Light source 122 (122R, 122G, 122B) ... Uniform illumination system 132 (132R, 132G, 132B) ... Polarization conversion element 135: Base material 136: Polarization separation film 137 (137R, 137G, 137B) ... Reflective polarization conversion film 139 (139R, 139G, 139B) ... Flat layer 140 (140R, 140G, 139B) ... Grid layer 141 (141R, 141G) 141 ) ... Projection 142 (142R, 142G, 142B) ... Gap 210 ... Light source 220 ... Uniform illumination system 221 ... Polarization conversion element 227 ... Polarization separation member 228 ... Reflective polarization conversion film 228a ... Base material 228b ... Flat layer 228c ... Grid Layer 228d ... convex part 228e ... gap 230 ... color modulation part 240 ... projection lens 250 ... screen

Claims (8)

The light incident on itself is separated into a first light component having a predetermined polarization direction and a second light component having a polarization direction different from the predetermined polarization direction, and the first light component is emitted in the first direction. A polarization separation member that emits the second light component in a second direction different from the first direction;
A polarization direction component provided on the second direction of the polarization separation member and converting at least a part of the second light component emitted from the polarization separation member into the predetermined polarization direction component and the polarization direction. A polarization conversion member that emits the second light component obtained by converting the first light component in the first direction. The polarization conversion element according to claim 1, wherein the polarization separation member and the polarization conversion member are provided inside a base material capable of transmitting light. One polarization separation member and one polarization conversion member make a pair,
The polarization conversion element according to claim 1, wherein a plurality of pairs of the polarization separation member and the polarization conversion member are provided. The polarization conversion member is
A flat layer made of a material capable of reflecting light provided in the second direction;
A grid layer provided on a surface of the flat layer and made of a light-reflective material and having a grid portion extending in one direction at a predetermined pitch and a predetermined depth. The polarization conversion element according to claim 3. The polarization conversion element according to claim 4, wherein the flat layer and the grid layer are mainly composed of silver, gold, or aluminum. The predetermined pitch is a value smaller than the wavelength of incident light;
The predetermined depth is in a range of 60 nm to 160 nm;
An angle in a range of an elevation angle of 45 ° with respect to a vertical plane with respect to the second direction of the polarization conversion member and a range of greater than 30 ° and less than 75 ° with respect to a direction perpendicular to the one direction on the vertical plane. The polarization conversion element according to claim 4 or 5, wherein the polarization conversion member is arranged so that the second light component is incident from a direction that forms the following. The polarization conversion element according to claim 1, wherein the polarization separation unit is a wire grid polarizing plate. A flat layer made of a light-reflective material;
A polarization conversion member comprising: a grid layer provided on a surface of the flat layer, made of a light-reflective material, and having a grid portion extending in one direction at a predetermined pitch and a predetermined depth. .

Images