JP2008176203A - Wavelength selective polarization conversion element and projector - Google Patents

Abstract

A wavelength-selective polarization conversion element and a projector capable of converting the polarization direction of predetermined color light.
A wavelength-selective polarization conversion element includes a color separation layer that transmits color light and reflects color light G and B, and a reflection layer 513 that reflects color light G and B in substantially the same direction as the color light R. A wavelength selection unit 51, a polarization separation layer 522 that transmits light R (P) having a predetermined polarization direction out of color light R, and reflects other light R (S), and light R (S) as light R ( P) a reflective layer 523A that reflects in substantially the same direction as P), a reflective layer 523B that reflects color lights G and B, and light G and B (P) having a predetermined polarization direction among the color lights G and B, and the other light G , B (S) to reflect the polarization separating layer 522, the light G, B (P) to reflect the light G, B (S) in the same direction as the light G, B (S), and the light R (P), G, B (S) and the light R (S), G, B (P) disposed on one optical path, and provided with a phase difference layer 524 that converts the polarization direction. And a converter 52.
[Selection] Figure 2

Description

  The present invention relates to a wavelength-selective polarization conversion element that converts a light beam having a predetermined wavelength and a light beam having another wavelength out of incident light beams into polarized light beams having different polarization directions, and the wavelength selection device. The present invention relates to a projector including a directional polarization conversion element.

  2. Description of the Related Art Conventionally, there is known a projector including a light source, a light modulation device that modulates a light beam emitted from the light source according to image information, and a projection optical device that projects the modulated light beam. In such a projector, the light beam modulated by the light modulation device is projected onto a screen or the like by a projection lens, whereby an image is displayed on the projection surface of the screen.

  As such a light modulation device, a transmissive liquid crystal panel that modulates a light beam incident from one surface and emits it from the other surface, or a reflective type that emits a light beam modulated from the same surface as the surface on which the light beam is incident In some cases, a liquid crystal panel is used. As a projector that employs such a reflective liquid crystal panel as a light modulation device, a light beam emitted from a light source is separated into red (R), green (G), and blue (B) color lights. There is known a projector that forms an image by making each color light incident on a reflection type liquid crystal panel provided in (see, for example, Patent Document 1).

In the projector described in Patent Document 1, light emitted from a light source is converted into unidirectional polarized light by a polarization conversion element array, and green light is separated from the polarized light by a dichroic mirror. The light is incident on the liquid crystal panel for green light through the polarization separation surface. Further, the red light and the blue light transmitted through the dichroic mirror are respectively incident on the wavelength-selective polarization rotating element to rotate the polarization direction of the red light, while rotating the polarization direction of the blue light. Color light is incident on the polarization separation surface. Then, the reflected red light is made incident on the liquid crystal panel for red light and the transmitted blue light is made incident on the liquid crystal panel for blue light by this polarization separation surface. And among the red light and blue light emitted from the liquid crystal panel, the polarization direction of the blue light is aligned with the same direction as the polarization direction of the red light by another wavelength selective polarization rotation element, and the red light and the blue light, An image is projected on the screen by combining the green light with the color combining element and projecting them with the projection lens.
Here, such a wavelength selective polarization rotation element has a configuration in which dozens of organic layers are stacked.

JP 2006-84820 A

However, the above-described wavelength selective polarization rotation element has a problem that the structure is complicated because dozens of organic layers are stacked. For this reason, there is a problem that not only the manufacturing process of the wavelength selective polarization rotation element becomes complicated, but also the manufacturing cost increases.
From such a problem, there has been a demand for a wavelength-selective polarization conversion element capable of converting the polarization direction of color light having a predetermined wavelength among incident light beams with another simple configuration.

  An object of the present invention is to provide a wavelength-selective polarization conversion element and a projector capable of converting the polarization direction of color light having a predetermined wavelength out of incident light beams with a simple configuration.

  In order to achieve the above-described object, the wavelength-selective polarization conversion element of the present invention is a wavelength-selective polarization conversion element that emits a light beam having a predetermined wavelength out of an incident incident light beam with a substantially uniform deflection direction. A wavelength selection unit that separates the first color light having the predetermined wavelength and the second color light other than the predetermined wavelength from the incident light beam, and the first color light and the second color light separated by the wavelength separation unit. A polarization conversion unit that converts the polarization direction of each of the first and second light beams, and the wavelength selection unit is arranged to be inclined with respect to the optical axis of the incident light beam, and transmits the first color light of the incident light beam, In addition, a color separation layer that reflects the second color light and at least a part of the second color light reflected by the color separation layer are arranged in substantially the same direction as the direction in which the first color light is transmitted through the color separation layer. A first reflection layer that reflects, the polarization conversion unit, The first color light, which is disposed to be inclined with respect to the optical axis of the first color light transmitted through the color separation layer, transmits light having a predetermined polarization direction and has another polarization direction. A first polarization separation layer that reflects light; and a light that is disposed along the first polarization separation layer and reflected by the first polarization separation layer; and a traveling direction of the light transmitted through the first polarization separation layer; A second reflective layer that reflects in substantially the same direction; a third reflective layer that is disposed with an inclination relative to the optical axis of the second color light reflected by the first reflective layer and reflects the second color light; Of the second color light, which is disposed along the third reflective layer and reflected by the third reflective layer, transmits light having the predetermined polarization direction and reflects light having another polarization direction. A second polarization separation layer that is disposed along the second polarization separation layer and transmits the second polarization separation layer. The reflected light in a direction substantially the same as the traveling direction of the light reflected by the second polarization separation layer, and the light transmitted through the first polarization separation layer and the second polarization separation layer. Of the incident light and the light reflected by each of the second reflection layer and the fourth reflection layer are arranged on the optical path of one light, and the polarization direction of the incident one light is changed to the other light. And a retardation layer that converts the polarization direction into a polarization direction.

According to the present invention, the first color light transmitted through the color separation layer and the second color light reflected by the wavelength selective reflection plate among the light beams incident on the wavelength selective polarization conversion element are converted by the polarization conversion unit. The light is emitted in the same polarization direction.
In other words, the first color light transmitted through the color separation layer constituting the wavelength selection unit is incident on the first polarization separation layer of the polarization conversion unit. The first polarization separation layer transmits polarized light (for example, P-polarized light) having a predetermined polarization direction among the incident first color light, and reflects polarized light (for example, S-polarized light) having other polarization directions. To do. And the 1st color light which is the polarized light which has the said other polarization direction reflected by this 1st polarization separation layer is the polarized light which has the predetermined polarization direction which permeate | transmitted the 1st polarization separation layer by the 2nd reflection layer. Is reflected in substantially the same direction as the traveling direction of the first color light.

  On the other hand, at least a part of the second color light reflected by the color separation layer of the wavelength selection unit is reflected by the first reflection layer and enters the third reflection layer of the polarization conversion unit. The second color light is further reflected by the third reflection layer and is incident on the second polarization separation layer. The second polarization separation layer has a predetermined polarization direction in the same manner as the first polarization separation layer. Transmits polarized light (for example, P-polarized light) and reflects polarized light (for example, S-polarized light) having another polarization direction. For this reason, out of the second color light incident on the second polarization separation layer, polarized light having a predetermined polarization direction (for example, P-polarized light) is transmitted through the second polarization separation layer and polarized light having the other polarization direction. (For example, S-polarized light) is reflected by the second polarization separation layer. Then, polarized light having a predetermined polarization direction (for example, P-polarized light) transmitted through the second polarization separation layer is a fourth reflection layer and polarized light having another polarization direction in the second polarization separation layer (for example, , S-polarized light) is reflected in substantially the same direction.

  At this time, the position of the retardation layer includes polarized light (for example, P-polarized light) related to the first color light transmitted through the first polarization separation layer and polarized light related to the second color light reflected by the second polarization separation layer. Each optical path (for example, S-polarized light), polarized light (for example, S-polarized light) reflected by the first color light reflected by the second reflective layer, and polarized light for the second color light reflected by the fourth reflective layer It arrange | positions on either optical path with each optical path of light (for example, P polarization | polarized-light). For this reason, for example, the first polarization separation layer and the second polarization separation layer are configured to transmit P-polarized light and reflect S-polarized light, and the retardation layer transmits light transmitted through the first polarization separation layer and When located on the optical path of the light reflected by the second polarization separation layer, the P-polarized light related to the first color light transmitted through the first polarization separation layer is converted into S-polarization by the retardation layer and emitted. On the other hand, the S-polarized light related to the first color light reflected by the first polarized light separating layer is emitted in substantially the same direction as the converted S-polarized light by the second reflective layer. Further, the S-polarized light related to the second color light reflected by the second polarization separation layer is converted into P-polarized light by the retardation layer and emitted, while P relating to the second color light transmitted through the second polarization separation layer. The polarized light is reflected by the fourth reflective layer in substantially the same direction as the converted P-polarized light.

  According to such a configuration, not only can the polarization directions of the first color light transmitted through the color separation layer of the wavelength selection unit and the second color light reflected by the color separation layer be substantially uniform. The first color light and the second color light can be polarized light having different polarization directions. Therefore, the polarization direction of desired color light can be aligned with polarized light having a polarization direction different from that of other color light by setting the color separation layer of the wavelength selection unit, that is, setting the transmission wavelength range.

In addition, in such a wavelength selective polarization conversion element of the present invention, the number of layers to be formed is not tens of layers, so that the configuration of the wavelength selective polarization conversion element can be simplified. The wavelength selective polarization conversion element can be constructed at low cost.
In addition, the first color light and the second color light having different polarization directions are emitted from the first polarization separation layer and the second reflection layer, and the second polarization separation layer and the fourth reflection layer, respectively. The first color light and the second color light can be easily distinguished from the emission position of the color light.

  In the present invention, the color separation layer, the first reflection layer, the first polarization separation layer, the second reflection layer, the third reflection layer, the second polarization separation layer, the fourth reflection layer, and the phase difference. Each of the layers is preferably made of an inorganic material.

  Here, when each of these layers is formed of an organic material, the deterioration becomes severe with the absorption of ultraviolet rays and the temperature rise, and wavelength selection and polarization separation cannot be performed appropriately. On the other hand, in this invention, such deterioration can be suppressed by forming each said layer with an inorganic material. Therefore, by forming the color separation layer, each polarization separation layer, each reflection layer, and the retardation layer from an inorganic material, it is possible to configure a wavelength-selective polarization conversion element that hardly causes secular change and suppresses functional degradation. .

  In the present invention, it is preferable that the third reflective layer is formed on the back side of the second reflective layer. That is, in the present invention, at least the first polarization separation layer, the second polarization separation layer, the second reflection layer, the third reflection layer, and the fourth reflection layer are arranged along substantially the same direction. Preferably, the third reflective layer is formed on the back side of the second reflective layer.

  Here, when the reflection direction of the polarized light having the other polarization direction described above at the first polarization separation layer is different from the reflection direction of the second color light at the third reflection layer, the second reflection layer, It is necessary to form the reflective layer separately, and a gap is generated between the first polarization separation layer and the third reflective layer. This gap is a region where light incident on the wavelength selective polarization conversion element does not pass, and the wavelength selective polarization conversion element becomes larger by this gap.

  On the other hand, in the present invention, since the third reflective layer is formed on the back surface of the second reflective layer, the first polarization separation layer reflects the polarized light having the other polarization direction described above, The reflection direction of the second color light at the three reflection layers is substantially the same. For this reason, it is possible to eliminate a gap between the first polarization separation layer and the third reflection layer, that is, a region through which light incident on the wavelength selective polarization conversion element does not pass. Therefore, it is possible to reduce the size of the wavelength selective polarization conversion element. Moreover, the number of components of the wavelength selective polarization conversion element can be reduced by configuring the second reflective layer and the third reflective layer as one reflective layer.

  In the present invention, the fourth reflective layer is the second reflective layer, the second polarization separation layer is the first polarization separation layer, the first polarization separation layer, the second reflection layer, and A plurality of the third reflective layers are alternately arranged in a direction substantially orthogonal to the optical axis of the incident light beam, and the color separation layer is configured to cause the first color light to face the second reflective layer. It is preferable that a plurality of first reflection layers are arranged at positions where the light enters the separation layer, and a plurality of the first reflection layers are arranged at positions where at least part of the second color light is incident on the third reflection layer.

According to the present invention, it is possible to emit the first color light and the second color light from substantially all of the light exit surface of the wavelength selective polarization conversion element.
That is, the first color light transmitted through the color separation layer of the wavelength selection unit is incident on one of the first polarization separation layers between the second reflection layer and the third reflection layer as described above. To do. Then, the first color light incident on the first polarization separation layer is converted into polarized light in one direction and emitted through the first polarization separation layer and the second reflection layer. Further, the first color light transmitted through another color separation layer corresponding to the other first polarization separation layer is incident on the other first polarization separation layer which is the second polarization separation layer, and the other The first color light is converted into polarized light in one direction and emitted through the first polarization separation layer and the second reflection layer which is the fourth reflection layer.

  On the other hand, at least a part of the second color light reflected by the color separation layer enters the third reflection layer via the first reflection layer, and is the second polarization separation layer via the third reflection layer. The light enters the first polarization separation layer. The first polarization separation layer is the other first polarization separation layer on which the first color light is incident, and the other first polarization separation layer and the second reflection layer that is the fourth reflection layer are interposed therebetween. At least part of the second color light is converted into polarized light in one direction (polarized light different from the polarized light related to the first color light) and emitted. Further, at least a part of the second color light separated by the other color separation layer corresponding to the one first polarization separation layer is incident on the one first polarization separation layer on which the first color light is incident. Thus, the light is converted into one polarized light (polarized light different from the polarized light related to the first color light) through the one first polarization separation layer and the second reflection layer, and emitted.

  According to this, the first color light and the second color light having different polarization directions can be emitted from the first polarization separation layer and the second reflection layer, respectively. Therefore, light beams having different wavelengths and different polarization directions can be generated as one light beam that is not substantially separated. In addition, by separating such a light beam by the above-described color separation layer or polarization separation layer, it is possible to easily separate two types of color light having substantially the same transmission area and different wavelengths and polarization directions. can do.

  Alternatively, in the present invention, the first reflective layer reflects third color light having a wavelength different from the predetermined wavelength out of the incident second color light, and emits fourth color light other than the third color light. The wavelength selection unit includes a fifth reflection layer that reflects the fourth color light transmitted through the second color separation layer and causes the light to enter the second polarization separation layer. Is preferred.

  According to the present invention, the first reflective layer functions as a second color separation layer having a color separation characteristic (wavelength selection characteristic) different from that of the above-described color separation layer, and the second color light incident on the first reflective layer. Among them, the third color light having another wavelength different from the above-mentioned predetermined wavelength is reflected by the first reflection layer, and the fourth color light which is the other color light is transmitted through the first reflection layer. Then, as described above, the third color light is reflected by the third reflection layer, reflected by the second polarization separation layer or the fourth reflection layer, and aligned with unidirectional polarized light in the process of passing through the retardation layer. It is done. On the other hand, the fourth color light is reflected by the fifth reflection layer and enters the second polarization separation layer, and among the fourth color light, the polarized light having the predetermined polarization direction passes through the second polarization separation layer. The polarized light having the other polarization direction is reflected and reflected by the fourth reflective layer. The polarized light related to the fourth color light is polarized light having a polarization direction different from the polarization direction of the polarized light related to the third color light in the process of passing through the retardation layer, that is, the polarized light related to the first color light. Are converted into polarized light having substantially the same polarization direction as that of the light and emitted.

  According to this, among the second color lights separated by the color separation layer of the wavelength selection unit, the third color light having a predetermined wavelength and the fourth color light which is another color light are polarized light having different polarization directions. It can be emitted as light. Therefore, it is possible to emit the light with the polarization direction aligned in one direction for each color light separated by the wavelength selection unit.

  The projector of the present invention is a projector including a light source, a light modulation device that modulates a light beam emitted from the light source according to image information, and a projection optical device that projects the modulated light beam. The wavelength-selective polarization conversion element described above is provided.

  Here, as a light source used in such a projector, a discharge light source lamp such as a high-pressure mercury lamp or a metal halide lamp can be employed, and a light emitting element such as an LED (Light Emitting Diode) can be employed. In addition, as the light modulation device, a liquid crystal panel that modulates incident light flux by adopting a liquid crystal sealed between a pair of substrates and changing an alignment state according to an applied voltage can be employed.

According to the present invention, the same effects as those of the wavelength selective polarization conversion element described above can be obtained, and the following effects can be obtained.
Since the polarization direction of color light having a predetermined wavelength can be converted by the wavelength selective polarization conversion element, a light modulation device that needs to allow only polarized light having a predetermined polarization direction to enter is provided for each predetermined color light. In this case, each color light can be easily incident on each light modulation device. That is, the above-described color separation layer or polarization separation layer is used to convert the first color light aligned in a predetermined polarization direction by the wavelength selective polarization conversion element and the second color light aligned in a polarization direction different from the first color light. Or from the emission position of the first color light and the second color light. Therefore, each color light can be easily and appropriately incident on the light modulation device provided for each color light.

  When the wavelength-selective polarization conversion element of the present invention is provided in the projector described in Patent Document 1, not only one wavelength-selective polarization rotation element can be omitted, but the wavelength selection In the case where each layer of the directional polarization conversion element is formed of an inorganic material, it is difficult for the secular change to occur, so that the lifetime of the projector can be extended. In particular, when the wavelength-selective polarization conversion element of the present invention is provided in the front stage of the light modulation device, the light intensity of the incident light beam is high in the front stage of the light modulation device, which is more effective.

In the present invention, it is preferable that a light beam splitting optical element that splits the light beam emitted from the light source into a plurality of partial light beams is provided, and the partial light beam split by the light beam splitting optical element is incident on the color separation layer. .
As such a light beam splitting optical element, a plurality of small lenses are arranged in at least one direction orthogonal to the optical axis of the incident light beam, and each small lens allows a plurality of incident light beams incident on the light beam splitting optical element. An example of the lens array is a fly-eye lens that divides the light beam into partial light beams.

According to the present invention, when a plurality of color separation layers of a wavelength selective polarization conversion element are provided, and a plurality of polarization separation layers, reflection layers, and retardation layers are provided according to the color separation layer, By making each partial light beam divided by the light beam splitting optical element enter each color separation layer of the wavelength selection unit, the light beam emitted from the light source can be incident on the wavelength selective polarization conversion element without waste. Therefore, the loss of light quantity can be suppressed, and thereby the brightness of the image formed by the light modulation device can be increased.
Further, by superimposing each partial light beam on an image forming area where an image is formed by the light modulation device, the image forming area can be illuminated uniformly. Therefore, an image with reduced illuminance unevenness can be formed.

[1. First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
[Overall configuration of projector 1]
FIG. 1 is a schematic diagram illustrating a configuration of a projector 1 according to the present embodiment.
The projector 1 of the present embodiment modulates a light beam emitted from a light source according to image information to form image light according to a display image, and projects the image light on a projection surface such as a screen, thereby A display image is displayed.
As shown in FIG. 1, the projector 1 includes an exterior housing 2, a projection lens 3, an optical unit 4, and the like.
Although not shown in FIG. 1, in the exterior housing 2, in a space other than the projection lens 3 and the optical unit 4, a cooling unit configured by a cooling fan or the like that cools the inside of the projector 1, It is assumed that a power supply unit that supplies power to each of the components and a control device that controls the entire projector 1 are disposed.

The exterior housing 2 is made of synthetic resin or the like, and is formed in a substantially rectangular parallelepiped shape that accommodates and arranges the projection lens 3 and the optical unit 4 inside as shown in FIG. Although not shown, the exterior housing 2 is composed of an upper case that constitutes the top, front, back, and left and right sides of the projector 1, and a lower case that constitutes the bottom, front, and back of the projector 1, respectively. The upper case and the lower case are fixed to each other with screws or the like.
The exterior casing 2 is not limited to a synthetic resin, but may be formed of other materials, for example, a metal or the like.

  The projection lens 3 is a projection optical device that enlarges and projects an optical image (color image) formed by the optical unit 4 onto a screen (not shown). The projection lens 3 is configured as a combined lens in which a plurality of lenses are housed in a cylindrical lens barrel.

[Configuration of Optical Unit 4]
The optical unit 4 is a unit that forms an optical image (color image) corresponding to image information by optically processing the light beam emitted from the light source under the control of the control device. The optical unit 4 houses therein an illumination optical device 41, a color separation optical device 42, a phase difference plate 43, a polarization separation device 44, a light modulation device 45, a color synthesis optical device 46, and these optical components 41 to 46. And an optical component casing (not shown) for supporting and fixing the projection lens 3 at a predetermined position.

  The illumination optical device 41 is a uniform illumination optical system for illuminating an image forming area of a light modulation device 45 described later almost uniformly. As shown in FIG. 1, the illumination optical device 41 includes a light source device 411, a first lens array 412, a second lens array 413, and a superimposing lens 414. In addition to these, wavelength selective polarization conversion is provided. An element 5 is provided.

The light source device 411 includes a light source lamp 416 that emits a radial light beam, a reflector 417 that reflects the emitted light emitted from the light source lamp 416 and converges it at a predetermined position, and a light beam converged by the reflector 417. A collimating concave lens 418 that is parallel to the illumination optical axis.
As such a light source lamp 416, various light source lamps that emit light with high luminance can be employed, and examples thereof include discharge light source lamps such as metal halide lamps, high-pressure mercury lamps, and ultrahigh-pressure mercury lamps. Moreover, not only a discharge light source lamp but light emitting elements, such as LED, can also be adopted. In the present embodiment, the reflector 417 is composed of an ellipsoidal reflector having a rotational ellipsoid, but may be composed of a parabolic reflector having a rotational paraboloid. In this case, the collimating concave lens 418 is omitted. Further, the reflector 417 may be a free-form surface reflector.

The first lens array 412 and the second lens array 413 correspond to the light beam splitting optical element of the present invention.
Among these, the first lens array 412 has a configuration in which a plurality of small lenses are arranged in a matrix in a plane substantially orthogonal to a predetermined illumination optical axis, and a plurality of light beams emitted from the light source device 411 are emitted. Is divided into partial luminous fluxes.
The second lens array 413 has substantially the same configuration as the first lens array 412, and has a configuration in which small lenses corresponding to the small lenses of the first lens array 412 are arranged in a matrix. The second lens array 413 has a function of forming the image of the first lens array 412 in the image forming area of the light modulation device 45 together with the superimposing lens 414. Each small lens of the second lens array 413 is set so that the partial light beam divided by the small lens enters a color separation layer 512 (to be described later) of the wavelength selective polarization conversion element 5.

  The wavelength-selective polarization conversion element 5 is disposed between the second lens array 413 and the superimposing lens 414, and the second lens is provided on each of the plurality of light incident surfaces 515 formed on the wavelength-selective polarization conversion element 5. Each partial light beam emitted from the array 413 enters. The wavelength-selective polarization conversion element 5 aligns the polarization direction of the colored light having a predetermined wavelength in the incident light flux in a predetermined direction, and sets the polarization direction of the colored light having other wavelengths to a direction different from the predetermined direction. In alignment, each color light is emitted from the light exit surface. The configuration of the wavelength selective polarization conversion element 5 will be described in detail later.

  The color separation optical device 42 includes a dichroic mirror that transmits red light R and green light G and reflects blue light B of incident light beams. The blue light B reflected by the color separation optical device 42 enters the phase difference plate 43 (431), and the red light R and the green light G transmitted through the color separation optical device 42 are the phase difference plate 43. Incident at (432).

  The phase difference plate 43 (431, 432) rotates the polarization direction of the incident polarized light by 90 °. Specifically, the phase difference plate 431 is provided at a position where the blue light B reflected by the color separation optical device 42 is incident, and the blue light B aligned with the S-polarized light by the wavelength-selective polarization conversion element 5 described later. Converts to P-polarized blue light B. In addition, the phase difference plate 432 transmits the red light R that is transmitted through the color separation optical device 42 and aligned with the P-polarized light by the wavelength selective polarization conversion element 5 to be described later, to the S-polarized red light R. The green light G aligned with the S-polarized light by the wavelength selective polarization conversion element 5 is converted into the green light G of the P-polarized light.

  Two polarization separation devices 44 are provided in the optical unit 4, the polarization separation device 441 is on the optical path of the blue light B, and the polarization separation device 442 is on the optical paths of the red light R and the green light G, respectively. Is provided. Each of these polarization beam splitters 441 and 442 is configured as a prism having polarization beam separation layers 4411 and 4421 arranged to be inclined with respect to the optical axis of the incident light beam, and the polarization beam separation layers 4411 and 4421 transmit P-polarized light. And reflects S-polarized light.

  Specifically, the polarization separation device 441 includes a polarization separation layer 4411 that is inclined with respect to the light beam incident surface 441 </ b> A facing the phase difference plate 431. Then, the blue light B converted into P-polarized light by the retardation plate 431 passes through the polarization separation layer 4411 and is emitted from the surface 441B facing the light beam incident surface 441A toward the light modulator 45 (45B). The Then, the blue light B is reflected while being modulated by the light modulation device 45, and is incident on the polarization separation layer 4411 again via the surface 441B. Of the blue light B incident on the polarization separation layer 4411, the modulated S-polarized light is reflected by the polarization separation layer 4411, faces the polarization separation layer 4411, and intersects the light incident surface 441A and the surface 441B. The light is emitted from the light exit surface 441C toward the color synthesis optical device 46.

  In addition, the polarization separation device 442 includes a polarization separation layer 4421 that is inclined with respect to the light beam incident surface 442A facing the phase difference plate 432. Then, the red light R converted into S-polarized light by the retardation plate 432 enters the polarization separation layer 4421 from the light beam incident surface 442A and is reflected by the polarization separation layer 4421. The red light R is emitted from a surface 442B that faces the polarization separation layer 4421 and intersects the light beam incident surface 442A, and enters the light modulation device 45 (45R). The red light R incident on the light modulation device 45R is reflected while being modulated by the light modulation device 45R, and is incident on the polarization separation layer 4421 again via the surface 442B. Of the red light R incident on the polarization separation layer 4421, the modulated P-polarized light is transmitted through the polarization separation layer 4421 and travels from the light exit surface 442D facing the surface 442B toward the color synthesis optical device 46. It is injected.

  Further, the green light G converted into P-polarized light by the phase difference plate 432 enters the polarization separation device 442 from the light beam incident surface 442A and passes through the polarization separation layer 4421. The green light G is emitted from the surface 442C facing the light beam incident surface 442A toward the light modulation device 45 (45G). The green light G incident on the light modulation device 45G is reflected while being modulated by the light modulation device 45G, and is incident on the polarization separation layer 4421 again via the surface 442C. Of the green light G that has entered the polarization separation layer 4421, the modulated S-polarized light is reflected by the polarization separation layer 4421 and emitted from the light exit surface 442D toward the color synthesis optical device 46.

  The light modulation device 45 (the light modulation device for red light is 45R, the light modulation device for green light is 45G, and the light modulation device for blue light is 45B) includes a color separation optical device 42 and a polarization separation device. Provided for each of the color lights separated at 442, the incident color light is modulated in accordance with image information input from the above-described control device, and a monochromatic image corresponding to the color light is formed. Each of these light modulation devices 45 is configured as a reflective liquid crystal panel, and detailed illustration is omitted, but a liquid crystal element as an electro-optical material is hermetically sealed between a pair of transparent glass substrates, and the control The alignment state of the liquid crystal element is controlled in accordance with the drive signal from the apparatus, and the polarization direction of the incident light beam is modulated. For example, when the incident light beam is P-polarized light, the light beam that is modulated by the liquid crystal panel and becomes image light is S-polarized light, and when the incident light beam is S-polarized light, the light beam that is modulated and becomes image light is P-polarized light. It becomes. Since these light modulators 45 are configured as reflective liquid crystal panels, as described above, the light beam incident from the polarization separation device 44 (441, 442) is emitted from the same surface as the surface on which the light beam is incident. Then, the light again enters the polarization beam splitter 44 (441, 442).

The color combining optical device 46 combines the red light R and green light G incident from the polarization separation device 442 and the blue light B incident from the polarization separation device 441 to form an optical image (color image).
The color synthesizing optical device 46 includes two prisms that are columnar bodies each having a substantially isosceles right triangle shape in plan view, and has an overall substantially rectangular parallelepiped shape in which surfaces corresponding to oblique sides are bonded together. A wavelength-selective reflection layer 461 that transmits red light R and green light G and reflects blue light B is formed at the interfaces of these prisms. Therefore, the red light R and the green light G incident through the light beam incident surface 46B facing the polarization separation device 442 are transmitted through the reflection layer 461 and emitted from the light beam emission surface 46C facing the light beam incident surface 46B. The Further, the blue light B incident through the light beam incident surface 46A facing the polarization beam splitting device 441 is reflected by the reflection layer 461 and emitted from the light beam emission surface 46C. In this manner, the color combining optical device 46 matches the optical paths of the red light R, the green light G, and the blue light B, and the color image light is combined to form a color image.
Each color light emitted from the light beam exit surface 46C is incident on the projection lens 3 located in the latter stage of the optical path of the color synthesis optical device 46, and is projected onto the screen or the like by the projection lens 3.

[Configuration of Wavelength Selective Polarization Conversion Element 5]
Hereinafter, the configuration of the wavelength selective polarization conversion element 5 will be described.
FIG. 2 is a schematic diagram showing the configuration of the wavelength selective polarization conversion element 5.
As described above, the wavelength-selective polarization conversion element (hereinafter may be simply abbreviated as “polarization conversion element”) 5 generates color light having a predetermined wavelength among the partial light beams incident from the second lens array 413. Is converted into polarized light having a polarization direction of, and other color light is converted into polarized light having another polarization direction and emitted. Specifically, the wavelength-selective polarization conversion element 5 of the present embodiment emits red light R aligned with P-polarized light and green light G and blue light B aligned with S-polarized light.
Such a wavelength-selective polarization conversion element 5 includes a wavelength selection unit 51 and a polarization conversion unit 52, as shown in FIG.
In the following description, the wavelength selective polarization conversion element 5 may be simply referred to as “polarization conversion element 5”.

[Configuration of Wavelength Selection Unit 51]
The wavelength selection unit 51 is provided on the previous stage side, that is, the second lens array 413 side in the polarization conversion element 5, and each partial light beam emitted from the second lens array 413 is incident thereon. In the wavelength selection unit 51, a plurality of translucent members 511 that are substantially parallelogram-shaped columnar bodies having a narrow angle of about 45 ° are orthogonal to the optical axis of the partial light beam incident from the second lens array 413. It is arranged in parallel in the direction and is configured in a substantially rectangular parallelepiped shape as a whole. These translucent members 511 are formed of a translucent material such as glass and have a short direction in the arrangement direction of the translucent members 511 and long in a direction perpendicular to the arrangement direction when viewed from the incident direction of the light beam. Has a direction. The arrangement direction of the translucent members 511 corresponds to one arrangement direction of the small lenses of the second lens array 413.

  In addition, color separation layers 512 and reflection layers 513 are alternately formed at interfaces where these light transmitting members 511 are adjacent to each other. That is, a color separation layer 512 is formed at the interface between two adjacent light transmitting members 511, and one of the two light transmitting members 511 is adjacent to the one light transmitting member 511 and the one light transmitting member 511. A reflective layer 513 is formed at an interface with another light transmissive member 511 (a light transmissive member 511 different from the two light transmissive members 511). The color separation layer 512 and the reflection layer 513 are inclined in the same direction at an angle of 45 ° with respect to the optical axis of the partial light beam incident from the second lens array 413.

  The color separation layer 512 transmits color light having a predetermined wavelength among incident light beams and reflects other color light, and is formed of an inorganic material. In this embodiment, the color separation layer 512 is formed so as to transmit red light R and reflect other color light (for example, green light G and blue light B) regardless of the polarization direction. The red light R transmitted through the color separation layer 512 is incident on the polarization separation layer 522 of the polarization conversion unit 52. That is, in the present embodiment, the red light R transmitted through the color separation layer 512 corresponds to the first color light of the present invention, and the other color lights (green light G and blue light B) reflected by the color separation layer 512. Corresponds to the second color light of the present invention.

  The reflection layer 513 corresponds to the first reflection layer of the present invention, and the color light reflected by the color separation layer 512 is arranged on the rear stage side, that is, the polarization conversion unit 52 along the optical axis of the partial light beam incident on the polarization conversion element 5. This is a total reflection layer that reflects to the side. The reflective layer 513 is composed of a reflective film formed of a single metal material or an alloy. Then, the color light reflected by the reflective layer 513 enters the reflective layer 523B of the polarization conversion unit 52.

  Further, among the surfaces facing the second lens array 413 in the wavelength selection unit 51, the region not corresponding to the color separation layer 512, that is, the surface on the light beam incident side of the light transmitting member 511 corresponding to the reflection layer 513 is made of stainless steel. Alternatively, a light shielding layer 514 formed by vapor deposition of aluminum or the like is formed. That is, on the surface of the wavelength selection unit 51 that faces the second lens array 413, the surface on the light beam incident side of the translucent member 511 corresponding to the color separation layer 512 out of the region where the light shielding layer 514 is not formed. Surface 515. Such a light shielding layer 514 prevents a part of the partial light beams emitted from the second lens array 413 from directly entering the reflection layer 513, so that the partial light beams can be reliably transmitted to the color separation layer 512. It is comprised so that it may inject into.

[Configuration of Polarization Conversion Unit 52]
The polarization conversion unit 52 converts each color light separated by the wavelength selection unit 51 into polarized light having different polarization directions. As in the wavelength selection unit 51 described above, the polarization conversion unit 52 includes a translucent member 521 that is a substantially parallelogram-shaped columnar body in plan view having a narrow angle of about 45 °. A plurality of 511 are arranged in parallel along the same direction as the arrangement direction, and are formed in a substantially rectangular parallelepiped shape as a whole. The light incident surface of one light transmissive member 521 is connected to the light beam emission surface of the light transmissive member 511 of the wavelength selection unit 51, and each of the light transmissive members 511 and 521 has a parallelogram in plan view. It is comprised so that it may become.

At the interface between the light transmitting members 521 adjacent to each other, the polarization separation layer 522 and the reflection layer 523 are inclined by approximately 45 ° with respect to the optical axis of the color light incident from the wavelength selection unit 51, and each is in the same direction. It is formed alternately so as to be along. In addition, a phase difference layer 524 is formed in a region corresponding to the reflective layer 523 on the surface on the light beam exit side of the polarization conversion unit 52.
The polarization separation layer 522 is formed of a dielectric multilayer film that transmits polarized light having a predetermined polarization direction and reflects polarized light having another polarization direction. The polarization separation layer 522 corresponds to the first polarization separation layer and the second polarization separation layer of the present invention. In this embodiment, the polarization separation layer 522 transmits P-polarized light and reflects S-polarized light. It is good also as a structure which permeate | transmits and reflects P polarized light.

  The reflective layer 523 is formed of a reflective film formed of a single metal material or an alloy, as with the above-described reflective layer 513, and has a front surface (surface on the second lens array 413 side) and a back surface (superimposed lens 414 side). And the incident light fluxes can be reflected by each other. The reflective layer 523A on the back side corresponds to the second reflective layer and the fourth reflective layer of the present invention, and polarized light having another polarization direction reflected by the polarization separation layer 522 (in this embodiment, S (Polarized light) is emitted toward the rear stage of the polarization conversion element 5, which is the same as the traveling direction of the polarized light transmitted through the polarization separation layer 522. The reflective layer 523B on the front side corresponds to the third reflective layer of the present invention, and reflects the colored light reflected by the reflective layer 513 of the wavelength selection unit 51 toward the polarization separation layer 522.

The retardation layer 524 rotates the polarization direction of the incident polarized light by 90 °. That is, the retardation layer 524 converts the incident P-polarized light into S-polarized light, and converts the incident S-polarized light into P-polarized light.
In this way, the polarized light transmitted through the color separation layer 512 of the wavelength selection unit 51 and transmitted through the polarization separation layer 522 is reflected by the color separation layer 512 and is reflected by the reflection layer 513 and the polarization conversion unit 52. The polarized light reflected by the polarization separation layer 522 via the reflective layer 523B of the light, and after being reflected by the color separation layer 512 and the reflection layer 523B, are transmitted through the polarization separation layer 522 and are reflected via the reflection layer 523A. The polarized light transmitted through the phase difference layer 524 is emitted to the outside of the polarization conversion element 5.

[Separation of luminous flux by wavelength selective polarization conversion element 5]
Hereinafter, the separation state of the incident light beam by the wavelength selective polarization conversion element 5 will be described.
Each partial light beam emitted from the second lens array 413 enters each light beam incident surface 515 of the polarization conversion element 5 corresponding to each color separation layer 512. Since the white light that is a partial light beam incident on the light beam incident surface 515 is not polarized and separated, the white light includes P-polarized light and S-polarized light. When the white light passes through the light transmitting member 511 and enters the color separation layer 512, the color separation layer 512 causes the red light R (P, S) and other color light, that is, green light and blue light G, B, to be emitted. (P, S).

Among these, the red light R (P, S) transmitted through the color separation layer 512 is transmitted through the light transmitting members 511 and 521 and is incident on the polarization separation layer 522 of the polarization conversion unit 52. Since this polarization separation layer 522 transmits P polarization and reflects S polarization, P polarization R (P) out of red light R (P, S) incident on the polarization separation layer 522 is polarization separation layer 522. Transparent.
Further, the S-polarized light R (S) related to the red light reflected by the polarization separation layer 522 is incident on the reflection layer 523A and is the same as the P-polarized light R (P) transmitted through the polarization separation layer 522 by the reflection layer 523A. It is reflected in the direction and enters the retardation layer 524. Then, due to the retardation plate 524, the polarization direction of the S-polarized light R (S) is rotated to become the P-polarized light R (P).
Then, the P-polarized light R (P) related to the red light is emitted toward the superimposing lens 414 located at the rear stage of the polarization conversion element 5.

  On the other hand, the green light and the blue light G, B (P, S) reflected by the color separation layer 512 and transmitted through the light transmitting member 511 along the arrangement direction of the light transmitting members 511 enter the reflective layer 513. . Then, the green light and the blue light G, B (P, S) travel along the same direction as the red light R (P, S) transmitted through the color separation layer 512 by the reflection layer 513, and on the rear side. The light enters the reflection layer 523B of the polarization conversion unit 52 that is positioned. Thereafter, the green light and the blue light G, B (P, S) are reflected by the reflective layer 523B in the arrangement direction of the light transmitting members 521, that is, the S-polarized light R (related to the red light reflected by the polarization separation layer 522). The light passes through the translucent member 521 in the same direction as the traveling direction of S) and enters the polarization separation layer 522.

Of the green light and blue light G, B (P, S) incident on the polarization separation layer 522, green light and blue light G, B (S), which are S-polarized light, are reflected by the polarization separation layer 522. . Then, the green light and the blue light G, B (S) are emitted toward the superimposing lens 414 located at the rear stage of the polarization conversion element 5.
Further, green light and blue light G, B (P) which are P-polarized light are transmitted through the polarization separation layer 522 and incident on the reflection layer 523A. Then, the green light and the blue light G, B (P) are reflected by the reflective layer 523A and enter the retardation layer 524 located on the rear side, similarly to the red light R (S) described above. The green light and the blue light G, B (P) are rotated in the polarization direction by the retardation layer 524 to become green light and blue light G, B (S) as S-polarized light, toward the superimposing lens 414. It is injected.

As described above, the polarization separation layer 522 and the reflection layer 523A constituting the polarization conversion unit 52 of the polarization conversion element 5 are incident on one light incident surface 515 formed in the wavelength selection unit 51, and the color separation layer. Red light R transmitted through 512 is incident. In addition, the polarization separation layer 522 and the reflection layer 523A are adjacent to the one light incident surface 515 and are arranged on the base end side in the arrangement direction of the light transmitting member 511 (green light and blue light G by the color separation layer 512, Green light and blue light G which are incident on the other light incident surface 515 opposite to the reflection direction of B and reflected by the color separation layer 512 corresponding to the light incident surface 515. , B are incident.
On the contrary, the one light flux is incident on the polarization separation layer 522 and the reflection layer 523A where the green light and the blue light G and B incident from one light flux incident surface 515 and separated by the corresponding color separation layer 512 are incident. Another light flux incident surface adjacent to the incident surface 515 and on the front end side in the arrangement direction of the light transmitting member 511 (on the reflection direction side of the green light and blue light G and B by the color separation layer 512 and on the right side in FIG. 2) The red light R that is incident on 515 and transmitted through the corresponding color separation layer 512 is incident.
For this reason, red light R (P) that is P-polarized light, green light that is S-polarized light, and blue light G and B (S) are emitted from almost the entire light emission surface of the polarization conversion element 5, and each color light is emitted. Enters the superimposing lens 414.

According to the projector 1 of the present embodiment described above, the following effects can be obtained.
(1) Of the red light R, green light G, and blue light B separated by the color separation layer 512 constituting the wavelength selection unit 51 of the wavelength selective polarization conversion element 5, the red light R is converted into the polarization separation layer. 522, the reflective layer 523A, and the retardation layer 524 can be emitted in alignment with the P-polarized light, and the green light G and the blue light B can be emitted from the reflective layer 523B, the polarization separation layer 522, the reflective layer 523A, and the retardation layer. By 524, it is possible to emit in alignment with S-polarized light. Since such color separation (wavelength selection) is performed based on the characteristics set in the color separation layer 512 of the wavelength selection section 51, that is, the color separation characteristics (wavelength transmission characteristics), the characteristics of the wavelength selection section 51 are concerned. By setting, desired color light can be aligned with polarized light having a polarization direction different from that of other color light. The polarization direction of the emitted polarized light is determined by the polarization separation characteristics of the polarization separation layer 522, the polarization conversion characteristics of the retardation layer 524, and the arrangement position. For this reason, it can align with the polarized light which has a desired polarization direction by setting these suitably. Therefore, polarized light having a desired wavelength and polarization direction can be easily extracted.

(2) The wavelength selective polarization conversion element 5 does not have a structure in which dozens of organic layers are stacked.
That is, in the manufacture of the wavelength selective polarization conversion element 5, for example, the wavelength selection unit 51 and the polarization conversion unit 52 are individually manufactured, the surface of the wavelength selection unit 51 on the light beam exit side, and the polarization conversion unit 52. Affix to the light incident surface. Among these, in the wavelength selection unit 51, a plurality of flat plate-like light transmitting members 511 are stacked while alternately forming the color separation layers 512 and the reflective layers 513 at the interfaces of the light transmitting members 511, Each layer 512, 513 is cut at approximately 45 °. And the wavelength selection part 51 is formed by forming the light shielding layer 514 in the position corresponding to each reflection layer 513. FIG. Further, in the polarization conversion unit 52, a flat plate-like light transmitting member 521 having substantially the same thickness as the light transmitting member 511 is formed, and a polarization separation layer 522 and a reflective layer 523 are alternately formed at the interface of the light transmitting member 521. In the same manner, the laminate is cut at about 45 ° with respect to each of the layers 522 and 523. Then, the polarization conversion unit 52 is formed by forming the retardation layer 524 at a position corresponding to the reflective layer 523.
Thus, the wavelength-selective polarization conversion element 5 is not configured to stack dozens of organic layers, so that the configuration can be simplified and the manufacturing process can be simplified. The polarization conversion element 5 can be configured at low cost.

  (3) The color separation layer 512, the reflection layers 513, 523A, and 523B, the polarization separation layer 522, the retardation layer 524, and the light shielding layer 514 of the wavelength selective polarization conversion element 5 are formed of an inorganic material. According to this, each layer 512, 513, 514, 522, 523, 524 can suppress deterioration due to absorption of ultraviolet rays and temperature rise. Therefore, it is possible to configure the wavelength-selective polarization conversion element 5 that hardly changes over time and can suppress a decrease in function.

  (4) The reflective layer 523 is formed with a reflective layer 523A on which the colored light transmitted through the polarization separation layer 522 is incident on the surface on the rear stage side that is the superimposing lens 414 side, and the front stage on the second lens array 413 side. On the side surface, a reflective layer 523B is formed, on which the color light reflected by the reflective layer 513 of the wavelength selection unit 51 enters. According to this, the traveling direction of the S-polarized light R (S) of the red light reflected by the polarization separation layer 522, and the P-polarized light G of the green light and the blue light reflected by the reflection layer 523B and transmitted through the polarization separation layer 522. , B (P) can coincide with the traveling direction. For this reason, the translucent members 511 and 521 can be arranged without a gap, and the region where the light incident on the polarization conversion element 5 is not transmitted can be eliminated in the polarization conversion unit 52. Therefore, the polarization conversion element 5 can be downsized. Further, since the reflective layers 523A and 523B are formed on the front and back surfaces of one reflective layer 523, an increase in the number of parts of the wavelength selective polarization conversion element 5 can be suppressed.

  (5) Among the partial light beams incident on one light beam incident surface 515 in the wavelength selection unit 51 of the wavelength selective polarization conversion element 5, the polarization separation layer 522 on which the red light R (P, S) is incident has the 1 Green light and blue light G, B (P, S) incident on and separated from the light incident surface 515 adjacent to the two light incident surfaces 515 and located on the proximal side in the arrangement direction of the light transmitting members 511 are incident. To do. According to this, each color light having a different wavelength and polarization direction, that is, P-polarized light R (S) of red light and S-polarized light G and B (S) of green light and blue light are converted into wavelength selective polarization conversion elements. 5 can be respectively emitted from substantially the entire surface of the light beam emission region. Therefore, light beams having different wavelengths and different polarization directions can be generated as one light beam that is not substantially separated. In addition, the areas of the transmission regions of the respective color lights, that is, the red light R (P), the green light, and the blue light G and B (S) can be made substantially the same. The image forming area can be appropriately illuminated.

  (6) Since the projector 1 has such a wavelength-selective polarization conversion element 5, color light having a wavelength and polarization direction corresponding to the light modulation device 45 on which each color light is incident is converted into an image forming area of each light modulation device 45. Can be made incident. Therefore, it is possible to improve the degree of freedom in designing the arrangement of optical components constituting the optical unit 4 and the optical characteristics.

  (7) The wavelength-selective polarization conversion element 5 includes a translucent member 511 in which the color separation layer 512 and the reflection layer 513 are formed, and a translucent member 521 in which the polarization separation layer 522 and the reflection layer 523 are formed. A plurality of light beams are arranged along one direction orthogonal to the optical axis of each partial light beam incident from the two-lens array 413. For this reason, since the color separation layer 512 is formed at a plurality of positions, a plurality of light beam incident surfaces 515 of the polarization conversion element 5 exist. On the other hand, since the partial light beams divided by the second lens array 413 are incident on each light beam incident surface 515, the light beams emitted from the light source device 411 are incident on the wavelength selective polarization conversion element 5 without waste. Can be made. Therefore, the light use efficiency can be improved, and thereby the brightness of the image formed by the optical unit 4 can be increased.

  (8) Since the wavelength-selective polarization conversion element 5 is configured by arranging a plurality of light-transmitting members 511 and 521 in parallel, the wavelength-selective polarization conversion element has a pair sandwiching the color separation layer 512 and the polarization separation layer 522, respectively. Compared with the case where only the translucent members 511 and 521 are configured, the depth direction of the wavelength-selective polarization conversion element 5 (the traveling direction of each partial light beam emitted from the second lens array 413 and the illumination optical axis direction) ) Can be made smaller. Therefore, the size of the wavelength selective polarization conversion element 5 can be further reduced.

[2. Second Embodiment]
The projector 1A according to the second embodiment of the present invention will be described below.
The projector 1A of the present embodiment has the same configuration as the projector 1 described above, but the wavelength-selective polarization conversion element 5 of the projector 1 uses the same green light and blue light reflected by the color separation layer 512, respectively. The wavelength-selective polarization conversion element 6 provided in the projector 1A converts the green light and the blue light into polarized light having different polarization directions. The projector 1A of the present embodiment is different from the projector 1 described above. In the following description, parts that are the same as or substantially the same as those already described are assigned the same reference numerals and description thereof is omitted.

FIG. 3 is a schematic diagram showing the configuration of the projector 1A of the present embodiment.
The projector 1A includes the exterior casing 2, the projection lens 3, the optical unit 4A, and the like, similar to the projector 1 described above.
As shown in FIG. 3, the optical unit 4A includes an illumination optical device 41A, a color separation optical device 42, a polarization separation device 44, a light modulation device 45, a color synthesis optical device 46, and an optical component casing (not shown). ing. In addition, the optical unit 4A includes a retardation plate 43 (433).

Among them, the illumination optical device 41A includes a light source device 411, a first lens array 412, a second lens array 413, and a superimposing lens 414, as with the illumination optical device 41, and the illumination optical device 41A has a wavelength selectivity. Instead of the polarization conversion element 5, a wavelength selective polarization conversion element 6 is provided.
The wavelength selective polarization conversion element 6 emits red light R and blue light B aligned with S-polarized light and green light G aligned with P-polarized light among the light beams incident from the second lens array 413. The configuration of such a wavelength selective polarization conversion element 6 will be described in detail later.
Of each color light emitted from the wavelength selective polarization conversion element 6, S-polarized red light R (S) and P-polarized green light G are polarized and separated via the superimposing lens 414 and the color separation optical device 42. Incident on device 442. The S-polarized blue light B (S) enters the polarization separation device 441 via the superimposing lens 414 and the color separation optical device 42.

  In the optical unit 4A, the arrangement position of the light modulation device 45B that modulates the blue light B is different from that of the optical unit 4 described above. Specifically, the light modulation device 45B is not disposed on the surface 441B side facing the light beam incident surface 441A of the polarization separation device 441 but on the surface 441D side facing the light beam emission surface 441C. This is because the wavelength-selective polarization conversion element 6 emits the blue light B aligned with the S-polarized light, so that the blue light B that is S-polarized light reflected by the color separation optical device 42 and incident on the polarization separation device 441 is obtained. This is because the light is reflected toward the surface 441D. In the light modulation device 45B of the present embodiment, since the incident blue light B is S-polarized light, the blue light B that is modulated and becomes image light is P-polarized light.

A phase difference plate 43 (433) is provided on the optical path of the blue light B. The retardation plate 433 rotates the polarization direction of the blue light B emitted from the polarization separation device 441. As a result, the blue light B transmitted through the phase difference plate 433 is converted into S-polarized light with good reflection efficiency and is incident on the color combining optical device 46.
The optical paths of the respective color lights after the color synthesizing optical device 46 are the same as those of the optical unit 4 described above, and thus description thereof is omitted.

[Configuration of Wavelength Selective Polarization Conversion Element 6]
FIG. 4 is a schematic diagram showing the configuration of the wavelength selective polarization conversion element 6.
Similarly to the polarization conversion element 5 described above, the wavelength-selective polarization conversion element 6 converts color light having a predetermined wavelength out of the partial light beams incident from the second lens array 413 from a polarization direction of other color light. It converts to a kind of polarized light. Specifically, the wavelength-selective polarization conversion element 6 of the present embodiment aligns red light and blue light with S-polarized light, aligns green light with P-polarized light, and emits red light with blue light and green light. Is emitted from a different area.
As shown in FIG. 4, the wavelength selective polarization conversion element 6 includes a wavelength selection unit 61 and a polarization conversion unit 52.
In the following description, the wavelength selective polarization conversion element 6 may be simply referred to as “polarization conversion element 6”.

The wavelength selection unit 61 includes a plurality of translucent members 511 and 611 that are each formed of glass or the like and are substantially parallelogram-shaped columnar bodies in plan view having a narrow angle of about 45 °. The two-lens array 413 is arranged in a direction orthogonal to the optical axis of the partial light beam emitted from the two-lens array 413, and has a substantially rectangular parallelepiped shape as a whole. The arrangement direction of the translucent members 511 and 611 coincides with the arrangement direction of the small lenses of the second lens array 413 and coincides with the arrangement direction of the translucent members 521 of the polarization conversion unit 52.
Specifically, the wavelength selection unit 61 has a configuration in which two light transmissive members 511 and one light transmissive member 611 are alternately arranged, and the width dimension of the light transmissive member 611 (the light transmissive member 511). , 611 in the arrangement direction) is approximately twice the width of one translucent member 511.

The translucent member 611 located on the base end side in the arrangement direction of these translucent members 511 and 611 (the base end side in the reflection direction of the reflection layer 523B of the polarization conversion unit 52, and the left side in FIG. 4), and the front end side in the arrangement direction A color separation layer 512 is formed at the interface with the translucent member 511 located at the front end side in the reflection direction of the reflection layer 523B of the polarization conversion unit 52 and on the right side in FIG.
In addition, a color separation layer 613 corresponding to the second color separation layer, which is the first reflection layer of the present invention, is formed at the interface between the two adjacent light transmitting members 511.
Further, a reflective layer 614 is formed at the interface between the above-described translucent member 511 located on the base end side in the arrangement direction and the translucent member 611 located on the front end side in the arrangement direction.
The color separation layer 613 and the reflection layer 614 are aligned with the color separation layer 512 and are inclined by approximately 45 ° with respect to the optical axis of the partial light beam incident from the second lens array 413, similarly to the color separation layer 512. Formed and disposed along the polarization separation layer 522 of the polarization converter 52.

Among these, the color separation layer 613 reflects the green light G (P, S) out of the green light and the blue light G, B (P, S) reflected by the color separation layer 512, and the polarization conversion unit 52. While making it enter into the reflective layer 523B, it transmits blue light B (P, S). Such a color separation layer 613 can be formed of an inorganic material.
The reflection layer 614 is formed as a total reflection layer, and the blue light B (P, S) transmitted through the color separation layer 613 is converted into the polarization separation layer 522 of the polarization conversion unit 52 (the polarization separation layer 522 on which the red light R is incident). Are incident on different polarization separation layers 522). The reflection layer 614 is formed of a reflection film formed of a single metal material or an alloy, as with the reflection layer 513 described above.

  Further, on the surface on the light beam incident side of the wavelength selection unit 61, that is, on the surface facing the second lens array 413, there is no region other than the light beam incident side surface of the translucent member 511 corresponding to the color separation layer 512. A light shielding layer 514 is formed by vapor deposition of stainless steel or aluminum. For this reason, in the polarization conversion element 6, the surface facing the second lens array 413 of the translucent member 511 having the interface on which the color separation layer 512 is formed is formed as the light flux incident surface 515.

As described above, the polarization conversion unit 52 has a configuration in which a plurality of light transmissive members 521 are arranged, and a polarization separation layer 522 and a reflection layer 523 are alternately arranged at the interface between two adjacent light transmissive members 521. Is formed.
Of these, the polarization separation layer 522 is configured to reflect S-polarized light and transmit P-polarized light in the present embodiment. The polarization separation layer 522 disposed at a position corresponding to the color separation layer 512 corresponds to the first polarization separation layer of the present invention, and the polarization separation layer 522 has a color light (red color) transmitted through the color separation layer 512. Light R) enters. In addition, the polarization separation layer 522 disposed at a position corresponding to the reflection layer 614 corresponds to the second polarization separation layer of the present invention, and the polarized light separated by the color separation layer 613 (green light) is reflected on the polarization separation layer 522. The light G) is directly incident on the color light (blue light B) reflected by the reflective layer 614 through the reflective layer 523B.

Of the front and back surfaces of the reflective layer 523, a reflective layer 523A as the second reflective layer and the fourth reflective layer of the present invention is formed on the surface on the superimposing lens 414 side, and a surface on the second lens array 413 side is formed on the surface on the second lens array 413 side. A reflective layer 523B as the third reflective layer of the present invention is formed. These reflection layers 523A and 523B are each formed as a total reflection layer as described above.
In addition, a phase difference layer 524 that rotates the polarization direction of the incident light beam by approximately 90 ° is formed on the light emission surface of the light transmitting member 521 corresponding to the polarization separation layer 522 out of the light emission surface of the polarization conversion unit 52. ing.

[Separation of luminous flux by wavelength selective polarization conversion element 6]
Hereinafter, the separation state of the incident light beam by the wavelength selective polarization conversion element 6 will be described.
Each partial light beam emitted from the second lens array 413 enters the color separation layer 512 corresponding to the light beam incident surface 515 via the light beam incident surface 515 of the polarization conversion element 6.
Of the partial light beams incident on the color separation layer 512, the red light R (P, S) is transmitted through the color separation layer 512 and the polarization separation layer 522 of the polarization conversion unit 52 corresponding to the color separation layer 512. Is incident on.

Of the red light R (P, S) incident on the polarization separation layer 522, P-polarized light R (P) is transmitted through the polarization separation layer 522 and incident on the retardation layer 524. The polarization direction of the P-polarized light R (P) is rotated by the retardation layer 524 to become S-polarized light R (S), which is emitted from the polarization conversion element 6.
The S-polarized light R (S) related to the red light incident on the polarization separation layer 522 is reflected by the polarization separation layer 522, travels toward the front end side in the arrangement direction, and enters the reflection layer 523A. The S-polarized light R (S) is reflected by the reflective layer 523A, and is emitted in parallel with the traveling direction of the red light R (S) via the polarization separation layer 522 and the retardation layer 524.
Thus, among the partial light beams incident on the light beam incident surface 515, the red light R (P, S) is aligned with the S-polarized light R (S) by the polarization conversion element 6 and is along the optical axis of the incident partial light beam. Is emitted in the direction and enters the superimposing lens 414.

  On the other hand, among the partial light beams incident on the color separation layer 512, green light and blue light G, B (P, S) are reflected by the color separation layer 512 and transmitted toward the front end side in the arrangement direction. The light passes through the member 511 and enters the color separation layer 613. In the color separation layer 613, the incident green light G (P, S) is reflected, and the green light G (P, S) is incident on the reflection layer 523B of the polarization conversion unit 52 located on the rear stage side. The green light G (P, S) is transmitted through the translucent member 521 toward the front end side in the arrangement direction by the reflective layer 523B, and the polarized light separating layer 522 into which the red light R (P, S) is incident. Are incident on different polarization separation layers 522.

Of the green light G (P, S) incident on the polarization separation layer 522, the S polarization G (S) is reflected to the subsequent stage side by the polarization separation layer 522, and the S polarization G (S) is the retardation layer. It is converted into P-polarized light G (P) via 524 and emitted. Further, the P-polarized light G (P) related to the green light is transmitted through the polarization separation layer 522 and is incident on the reflection layer 523A. The P-polarized light G (P) is reflected by the reflective layer 523A, is parallel to the P-polarized light G (P) converted by the retardation layer 524, and is the same as the P-polarized light G (P). Injected in the direction.
Thus, among the partial light beams incident on the light beam incident surface 515, the green light G (P, S) is aligned with the P-polarized light G (P) by the polarization conversion element 6 and is along the optical axis of the incident partial light beam. Is emitted in the direction and enters the superimposing lens 414.

Further, the blue light B (P, S) transmitted through the color separation layer 613 is reflected by the reflection layer 614 and is the same as the polarization separation layer 522 into which the green light G (P, S) is incident, and the reflection. The light enters the polarization splitting layer 522 corresponding to the layer 614. Of the blue light B (P, S) incident on the polarization separation layer 522, the P polarization B (P) is transmitted through the polarization separation layer 522, and the S polarization B (S) is transmitted through the retardation layer 524. It is converted into and injected. In addition, the S-polarized light B (S) relating to the blue light incident on the polarization separation layer 522 is reflected by the polarization separation layer 522, travels toward the front end side in the arrangement direction, and is reflected by the reflection layer 523A. Is emitted in parallel to the converted S-polarized light B (S) and in the same direction as the S-polarized light B (S).
In this way, among the partial light beams incident on the light beam incident surface 515, the blue light B (P, S) is aligned with the S-polarized light B (S) by the polarization conversion element 6 and is along the optical axis of the incident partial light beam. Is emitted in the direction and enters the superimposing lens 414.

Here, in the polarization conversion element 6, a region where S-polarized red light R (S) is emitted, and a region where P-polarized green light G (P) and S-polarized blue light B (S) are emitted. Is different.
Specifically, the red light R (S) aligned with the S-polarized light is a surface (superimposed) on the light beam emission side of the two translucent members 521 having an interface on which the polarization separation layer 522 corresponding to the color separation layer 512 is formed. The light is emitted from a surface facing the lens 414.
Further, the green light G (P) aligned with the P-polarized light and the blue light B (S) aligned with the S-polarized light each have two transmission layers each having an interface on which the polarization separation layer 522 corresponding to the reflective layer 614 is formed. The light is emitted from the surface on the light beam exit side of the optical member 521.

According to the projector 1A of the present embodiment described above, the same effects as the effects (1), (3) to (4) and (6) to (8) that can be achieved by the projector 1 described above can be achieved. In addition, the following effects can be achieved.
(9) The wavelength selection unit 61 of the wavelength selective polarization conversion element 6 has a configuration in which the color separation layers 512 and 613 and the reflection layer 614 are interposed between the plate-like light transmitting members 511 and 611. . According to this, like the structure of the wavelength selection part 51 and the polarization conversion part 52 mentioned above, it is not the structure which laminates | stacks dozens of organic layers. Therefore, the configuration of the wavelength selective polarization conversion element 6 can be simplified as compared with the conventional wavelength selective polarization rotation element.

(10) Of the green light and the blue light G, B (P, S) reflected by the color separation layer 512, the wavelength selective polarization conversion element 6 reflects and reflects the green light G (P, S). The color separation layer 613 that transmits the blue light B (P, S) and the blue light B (P, S) transmitted through the color separation layer 613 are reflected to enter the layer 523B, and the red light R (P , S) is formed as a reflection layer 614 that is incident on a polarization separation layer 522 different from the polarization separation layer 522 on which the light is incident.
According to this, not only red light R can be aligned with S-polarized light R (S), but also green light G and blue light B can be converted into P-polarized light G (P) and S-polarized light B (S) having different polarization directions, respectively. Can be aligned. Therefore, approximately one type of polarized light can be provided for each wavelength, and the versatility of the wavelength selective polarization conversion element 6 can be improved.

  (11) In the wavelength selective polarization conversion element 6, red light R (S) aligned with S-polarized light, green light G (P) aligned with P-polarized light, and blue light B (S) aligned with S-polarized light. ) And the injection area is different. According to this, the red light R, the green light G, and the blue light B can be easily separated by disposing the reflecting member that separates the optical paths according to the emission positions of the respective color lights. Accordingly, it is possible to easily separate colored light having the same polarization direction.

[3. Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the first embodiment, the traveling direction of the green light and blue light G, B (P, S) reflected by the color separation layer 512 of the wavelength selective polarization conversion element 5, and the green color reflected by the reflective layer 523B. The traveling direction of the light and the blue light G, B (P, S) and the traveling direction of the red light R (S) reflected by the polarization separation layer 522 are assumed to be the same direction. In the second embodiment, the traveling direction of the green light and blue light G, B (P, S) reflected by the color separation layer 512 and the green light G (P, S reflected by the reflection layer 523B). ) And the traveling direction of the red light R (S) reflected by the polarization separation layer 522 are the same, but the present invention is not limited to these. That is, of the color light transmitted through the color separation layer 512, the reflection direction of the polarized light having a predetermined polarization direction at the polarization separation layer 522, and the reflection direction of the color light at the color separation layer 512 and the reflection layer 523B, respectively. It may be in a different direction.

  In each of the embodiments, the wavelength selection units 51 and 61 and the polarization conversion unit 52 include a plurality of color separation layers 512 and 613, reflection layers 513 and 614, a polarization separation layer 522, and a reflection layer 523 (523A and 523B). However, the present invention is not limited to this. Specifically, the wavelength selection unit 51 only needs to have at least one color separation layer 512 and a reflection layer 513, respectively. Similarly, the wavelength selector 61 only needs to have at least one color separation layer 512, 613 and a reflection layer 614, respectively. Further, the polarization conversion unit 52 includes a polarization separation layer 522 where the color light transmitted through the color separation layer 512 is incident, a polarization separation layer 522 where the color light reflected by the color separation layer 512 and the reflection layer 513 is incident, and a reflection There may be a reflection layer 523B that causes the color light reflected by the layer 513 to enter the polarization separation layer 522, and two reflection layers 523A that reflect each color light that is the polarization light reflected by each polarization separation layer 522. That is, the number of layers of the wavelength selectors 51 and 61 and the polarization converter 52 may be set as appropriate.

In each of the embodiments, the color separation layer 512 transmits the red light R and reflects the green light G and the blue light B. In the second embodiment, the color separation layer 613 reflects the green light G. Although the blue light B is transmitted, the present invention is not limited to this. That is, the color separation characteristics (wavelength selection characteristics) of these color separation layers 512 and 613 may be set as appropriate.
In each of the above embodiments, the polarization separation layer 522 transmits P-polarized light and reflects S-polarized light. However, the present invention is not limited to this, and is configured to transmit S-polarized light and reflect P-polarized light. May be.

  In the first embodiment, the retardation layer 524 is the light transmitting member 521 located on the front end side in the arrangement direction of the light transmitting member 521 out of the two light transmitting members 521 having the interface on which the polarization separation layer 522 is formed. In the second embodiment, the retardation layer 524 is disposed on the light beam exit side of the light transmitting member 521 located on the base end side in the arrangement direction of the light transmitting member 521. However, the present invention is not limited to this. In other words, the phase difference layer 524 is disposed on the light emission side of one of the two light transmitting members 521 (either the light transmitting member 521 on the arrangement direction base end side or the light transmitting member 521 on the distal end side). Any configuration may be used.

  In each of the above embodiments, the pair of first lens array 412 and second lens array 413 is exemplified as the light beam splitting optical element, but the present invention is not limited to this. That is, other configurations may be used as long as the light beams incident from the light source are divided to form partial light beams and the partial light beams can be incident on the light beam incident surfaces 515 of the wavelength selective polarization conversion elements 5 and 6.

  In each of the embodiments, the wavelength-selective polarization conversion elements 5 and 6 are disposed between the second lens array 413 and the superimposing lens 414, respectively. Although the partial light beam emitted from the lens array 413 is incident, the present invention is not limited to this. For example, the wavelength-selective polarization conversion elements 5 and 6 are arranged between the first lens array 412 and the second lens array 413 and arranged so that the partial light beams divided by the first lens array 412 enter. May be.

  In each of the embodiments, the color separation layers 512 and 613 and the reflection layers 513 and 614 formed in the wavelength selection units 51 and 61, and the polarization separation layer 522 and the reflection layer 523 (523A, 523A, formed in the polarization conversion unit 52). 523B) and the retardation layer 524 are each made of an inorganic material, but the present invention is not limited to this. For example, each of these layers may be made of an organic material.

In each of the above-described embodiments, a reflection type liquid crystal panel having the same light incident surface and light exit surface is used as the light modulator 45, but a transmissive liquid crystal panel having a different light entrance surface and light exit surface. May be used.
In each of the above-described embodiments, the light modulation device 45 is configured by a liquid crystal panel. However, a light modulation device having another configuration is adopted as long as the light modulation device forms an optical image by modulating incident light according to image information. May be. For example, the present invention can be applied to a projector using a light modulation device other than the liquid crystal layer, such as a device using a micromirror.

  In each of the above embodiments, the front type projectors 1 and 1A that perform image projection from the direction of observing the screen are exemplified. However, the present invention is a rear type projector that performs image projection from the side opposite to the direction of observing the screen. It is also applicable to.

  The present invention can be suitably used particularly for a projector.

1 is a schematic diagram illustrating a configuration of a projector according to a first embodiment of the invention. The schematic diagram which shows the structure of the wavelength selective polarization conversion element in the said embodiment. The schematic diagram which shows the structure of the projector which concerns on 2nd Embodiment of this invention. The schematic diagram which shows the structure of the wavelength selective polarization conversion element in the said embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,1A ... Projector, 3 ... Projection lens (projection optical apparatus), 5, 6 ... Wavelength selective polarization conversion element, 45 (45R, 45G, 45B) ... Light modulator, 51, 61 ... Wavelength selection part, 52 ... Polarization conversion unit, 411... Light source device (light source), 412... First lens array (beam splitting optical element), 413... Second lens array (beam splitting optical element), 512. 522... Polarization separation layer (first polarization separation layer, second polarization separation layer) 523... Reflection layer 523 A... Reflection layer (second reflection layer, fourth reflection layer) 523 B .. reflection layer (third reflection layer) , Other reflective layers), 613 ... color separation layer (second color separation layer), 614 ... reflection layer (fifth reflection layer), B (P, S) ... fourth color light, G (P, S) ... first Three-color light, G, B (P, S) ... second color light, R (P, S) ... first color light, B (P), G ( ), R (P) ... P-polarized light (light transmitted through the polarized light separation layer), B (S), G (S), R (S) ... S-polarized light (light reflected by the polarized light separation layer).

Claims (7)

A wavelength-selective polarization conversion element that emits a light beam having a predetermined wavelength out of an incident light beam that is aligned with a substantially uniform direction.
A wavelength selection unit that separates the first color light having the predetermined wavelength from the incident light beam and the second color light having a wavelength other than the predetermined wavelength;
A polarization conversion unit that converts the polarization directions of the first color light and the second color light separated by the wavelength separation unit,
The wavelength selector is
A color separation layer that is disposed to be inclined with respect to the optical axis of the incident light beam, transmits the first color light, and reflects the second color light of the incident light beam;
A first reflective layer that reflects at least a portion of the second color light reflected by the color separation layer in a direction substantially the same as a direction in which the first color light is transmitted through the color separation layer;
The polarization converter is
The first color light, which is disposed to be inclined with respect to the optical axis of the first color light transmitted through the color separation layer, transmits light having a predetermined polarization direction and has another polarization direction. A first polarization separation layer that reflects light;
A second reflection layer disposed along the first polarization separation layer and reflecting light reflected by the first polarization separation layer in a direction substantially the same as a traveling direction of the light transmitted through the first polarization separation layer; ,
A third reflective layer arranged to be inclined with respect to the optical axis of the second color light reflected by the first reflective layer and reflecting the second color light;
Of the second color light, which is disposed along the third reflective layer and reflected by the third reflective layer, transmits light having the predetermined polarization direction and reflects light having another polarization direction. A second polarization separation layer
A fourth reflection layer disposed along the second polarization separation layer and reflecting light transmitted through the second polarization separation layer in a direction substantially the same as the traveling direction of the light reflected by the second polarization separation layer; ,
One of the light transmitted through the first polarization separation layer, the light reflected by the second polarization separation layer, and the light reflected by each of the second reflection layer and the fourth reflection layer. A wavelength-selective polarization conversion element comprising: a retardation layer that is disposed on the optical path and converts the polarization direction of the incident one light into the polarization direction of the other light. In the wavelength selective polarization conversion element according to claim 1,
The color separation layer, the first reflection layer, the first polarization separation layer, the second reflection layer, the third reflection layer, the second polarization separation layer, the fourth reflection layer, and the retardation layer are respectively A wavelength-selective polarization conversion element comprising an inorganic material. In the wavelength selective polarization conversion element according to claim 1 or 2,
The wavelength selective polarization conversion element, wherein the third reflective layer is formed on a back surface side of the second reflective layer. In the wavelength selective polarization conversion element according to claim 3,
The fourth reflective layer is the second reflective layer;
The second polarization separation layer is the first polarization separation layer,
A plurality of the first polarization separation layers, the second reflection layer, and the third reflection layer are alternately arranged in a direction substantially orthogonal to the optical axis of the incident light beam,
A plurality of the color separation layers are arranged at positions where the first color light is incident on the first polarization separation layer facing the second reflection layer,
The wavelength selective polarization conversion element, wherein a plurality of the first reflective layers are arranged at positions where at least a part of the second color light is incident on the third reflective layer. In the wavelength selective polarization conversion element according to any one of claims 1 to 3,
The first reflective layer reflects a third color light having a wavelength different from the predetermined wavelength among the incident second color light, and transmits a fourth color light other than the third color light. Composed of layers,
The wavelength selector is
A wavelength-selective polarization conversion element, comprising: a fifth reflective layer that reflects the fourth color light transmitted through the second color separation layer and causes the fourth color light to enter the second polarization separation layer. A projector comprising: a light source; a light modulation device that modulates a light beam emitted from the light source according to image information; and a projection optical device that projects the modulated light beam,
A projector comprising the wavelength selective polarization conversion element according to claim 1. The projector according to claim 6, wherein
A light beam splitting optical element that splits a light beam emitted from the light source into a plurality of partial light beams,
A partial light beam split by the light beam splitting optical element is incident on the color separation layer.

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