JP2009086025A - Projector and lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector and a lighting device improving projection of a display shadow onto the projection surface while attaining miniaturization of the whole device, and improving image quality. <P>SOLUTION: This projector includes light sources 11R, 11G, 11B which emit laser beams containing a plurality of types of color light, a plurality of diffraction optical elements 12R, 12G, 12B which generate illuminating light, reflection type light modulation elements 20R, 20G, 20B, a color synthesizing part 30 which has a first polarization separation membrane 41 and a second polarization separation membrane 42 and synthesizes light modulated by the plurality of reflection type light modulation elements 20R, 20G, 20B, and projection means 50. The first polarization separation membrane 41 and the second polarization separation membrane 42 are crossed. The diffraction optical elements 12R, 12G, 12B emit a plurality of light fluxes onto the color synthesis part 30 so that the light emitted from the light sources 11R, 11G, 11B does not enter the polarization separation membrane which is different from the polarization separation membrane where the emitted light is polarized and separated of the first polarization separation membrane 41 and the second polarization separation membrane 42. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projector and a lighting device.

2. Description of the Related Art In recent years, as a projection display apparatus, an apparatus that combines a plurality of types of color light with a cross dichroic prism and projects it onto a screen has been proposed in order to reduce the size. In this cross dichroic prism, four right-angled triangular prisms are joined in an X shape, for example, a first wavelength selection film that can selectively reflect red light and a first wavelength that can selectively reflect blue light. A two-wavelength selective film is arranged to cross.
In such a cross dichroic prism, one side of the four right-angled triangular prisms is aligned, so that there is a problem that a boundary surface where the four sides overlap is projected onto the screen and reflected in the center of the image. In view of this, there has been proposed a composite prism that performs color synthesis by forming the first polarization separation film and the second polarization separation film without intersecting in an X shape (see, for example, Patent Document 1).

As shown in FIG. 9, the composite prism described in Patent Document 1 is a prism in which four prisms 101, 102, 103, and 104 are joined. The prism is perpendicular to the XY plane and is relative to the XZ plane and the YZ plane. A first polarization separation film 106 forming 45 ° is formed, and a second polarization separation film 107 perpendicular to the YZ plane and 45 ° to the XY plane and the XZ plane intersects the first polarization separation film 106. Is formed. That is, in such a composite prism, there is no boundary surface where the four sides generated when the cross dichroic prism is formed overlap.
International Publication No. 2004/068197 Pamphlet

  In the display device using the composite prism described in Patent Document 1, rectangular light L is incident from one end surface 111 of the ZY plane, and light L is emitted from the other end surface 112 opposite to the one end surface 111. A liquid crystal light valve 115 is disposed to face the end face 112. At this time, since the first polarization separation film 106 and the second polarization separation film 107 are provided so as to cross each other, the illumination light passes through the second polarization separation film 107 serving as a boundary surface and enters the liquid crystal light valve 115. As a result, the second polarization separation film 107 is projected as a display shadow K onto the projection surface. As a result, the entire apparatus can be reduced in size, but the image quality is degraded.

  The present invention has been made in order to solve the above-described problems, and can suppress the projection of a display shadow on a projection surface and improve the image quality while reducing the size of the entire apparatus. An object is to provide a projector and a lighting device.

In order to achieve the above object, the present invention provides the following means.
The projector of the present invention is provided on a light source that emits laser light including a plurality of types of color light, and on each optical path of the plurality of types of color light, and diffracts the light emitted from the light source to generate illumination light. A plurality of diffractive optical elements, a plurality of reflective light modulation elements that modulate and reflect illumination light generated by the plurality of diffractive optical elements, and light emitted from the diffractive optical elements and the reflective light modulation elements A first polarization separation film and a second polarization separation film that transmit at least one type of colored light, transmit polarized light that vibrates in one direction, and reflect polarized light that vibrates in the other direction. And a color combining unit that combines light modulated by the plurality of reflective light modulation elements, and a projection unit that projects the light combined by the color combining unit onto a projection surface, the first polarization Separation membrane and said The light is emitted from the light source by the diffractive optical element different from the polarization separation film that is polarized and separated from the first polarization separation film and the second polarization separation film. A plurality of light beams are incident on the color composition unit so as not to enter the polarization separation film.

In the projector according to the present invention, the plurality of types of color light emitted from the light source are each diffracted by the diffractive optical element, and are incident on the first polarization separation film, separated by polarization, and incident on the reflective light modulation element. The incident illumination light is modulated by the reflection type light modulation element and enters the color synthesis unit. The light synthesized in the color synthesis unit is projected onto the projection surface by the projection means.
At this time, a plurality of light beams are generated by the diffractive optical element so that light emitted from the light source does not enter the second polarization separation film. In addition, light that is incident on the second polarization separation film and separated by polarization is generated by a diffractive optical element so that the light is not incident on the first polarization separation film, and is combined by the reflection type light modulation element. Illuminate the modulation element.
That is, in the present invention, even if the first polarization separation film and the second polarization separation film intersect, the second polarization separation film is applied to the light that is polarized and separated by the first polarization separation film and incident on the reflective light modulation element. It can suppress the projection as a shadow. In addition, it is possible to prevent the first polarization separation film from being reflected as a shadow on the light that is separated by the second polarization separation film and incident on the reflective light modulation element. Therefore, since it is possible to suppress the display shadow from being projected onto the projection surface, it is possible to improve the image quality.
In addition, since a plurality of types of color light are synthesized by the color synthesis unit, the entire apparatus can be reduced in size.

  In the projector according to the aspect of the invention, one diffractive optical element is provided for one type of color light, and the light emitted from the light source is divided into a plurality of light beams by the diffractive optical element, and the color combining unit It is preferable to make it enter into.

  In the projector according to the present invention, the light emitted from the light source is divided into a plurality of light beams by the diffractive optical element provided for one type of color light, and the reflective light modulation element is illuminated. That is, since the number of parts can be reduced as compared with the case where a plurality of light beams are generated using a plurality of diffractive optical elements, the entire apparatus can be reduced in size.

  In the projector according to the aspect of the invention, a plurality of the diffractive optical elements are provided for one type of color light, and the light emitted from the light source is incident on each of the plurality of diffractive optical elements. It is preferable that a plurality of light beams diffracted and generated in each of the elements are incident on the color composition unit.

  In the projector according to the present invention, the light emitted from the light source enters each of the plurality of diffractive optical elements. A plurality of light beams diffracted and generated by each of the plurality of diffractive optical elements are incident on the color synthesis unit. Accordingly, it is easier to generate a plurality of light beams by providing a plurality of diffractive optical elements than when a plurality of light beams are generated by one diffractive optical element. Therefore, the design of the diffraction pattern of the diffractive optical element is facilitated.

  In the projector according to the aspect of the invention, it is preferable that the projector includes a color separation unit that emits white light including a plurality of types of color light and separates the white light emitted from the light source for each of the plurality of types of color light.

  In the projector according to the present invention, the white light emitted from the light source is separated into a plurality of types of color light by the color separation unit. Each separated color light is diffracted by the diffractive optical element. That is, by using a light source that emits white light, it is not necessary to provide a light source that emits each color light, so that the cost can be reduced.

  In the projector according to the aspect of the invention, it is preferable that the diffractive optical element generates illumination light so that regions that illuminate the reflective light modulation element overlap.

  In the projector according to the aspect of the invention, when a plurality of light beams illuminate the reflective light modulation element, the diffractive optical element generates illumination light so that regions where the reflective light modulation element is illuminated overlap. Thereby, it is possible to ensure that no gap is generated between the plurality of light beams.

  In the projector according to the aspect of the invention, it is preferable to adjust a modulation amount in the reflection type light modulation element based on an illuminance distribution of illumination light incident on the reflection type light modulation element.

  In the projector according to the present invention, since a plurality of light beams are incident on the color synthesis unit, when the plurality of light beams illuminate the reflective light modulation element, they are overlapped so as to ensure that no gap is generated between the plurality of light beams. There is. For example, in such a case, since the overlapping part becomes bright, it is necessary to reduce the brightness of this part. Therefore, the modulation amount in the reflective light modulation element is adjusted based on the illuminance distribution of the illumination light incident on the reflective light modulation element. Thereby, since the overlapping part does not become excessively bright, it becomes possible to project a clear image on the projection surface.

  In the projector according to the aspect of the invention, it is preferable that the diffractive optical element is a hologram element.

In the projector according to the present invention, for example, a computer generated hologram (CGH) in which a concavo-convex structure artificially created by calculation with a computer is formed on a glass substrate can be used. This CGH is a wavefront conversion element that converts the wavefront of incident light using a diffraction phenomenon. In particular, the phase modulation type CGH can perform wavefront conversion with almost no loss of incident light wave energy. Thus, since CGH can generate a uniform intensity distribution or a simple intensity distribution, it can be suitably used for irradiating a reflective light modulation element. Furthermore, CGH is preferable because it allows a free setting of the divided region of the diffraction grating and does not cause aberration problems.
Further, the hologram element can be suitably used because it easily divides one light beam into a plurality of light beams and matches them on the reflection type light modulation element or generates illumination light to be superimposed.

  The illuminating device of the present invention is provided on a light source that emits laser light including a plurality of types of color light and each light path of the plurality of types of color light, and diffracts the light emitted from the light source to generate illumination light. A plurality of diffractive optical elements, and at least one color light of the illumination light generated by the plurality of diffractive optical elements is incident, and the polarized light that vibrates in one direction among the incident light is transmitted, and the other direction And a polarization separation section having a first polarization separation film and a second polarization separation film for reflecting polarized light that vibrates in the direction, and the light emitted from the light source by the diffractive optical element causes the first polarization separation film and the A plurality of light beams are incident on the polarization separation unit so as not to be incident on a polarization separation film different from the polarization separation film to be separated by polarization in the second polarization separation film.

  In the illumination device according to the present invention, the plurality of types of color light emitted from the light source are each diffracted by the diffractive optical element and incident on the first polarization separation film, for example, and polarized and separated. At this time, illumination light is generated by the diffractive optical element so that light emitted from the light source does not enter the second polarization separation film. In addition, illumination light is generated by the diffractive optical element so that light incident on the second polarization separation film and separated by polarization does not enter the first polarization separation film. Then, the light is separated by the first polarization separation film and the second polarization separation film of the polarization separation unit. Therefore, it is possible to suppress the display shadow from appearing in the light emitted from the polarization separation unit.

Embodiments of a projector and an illumination device according to the present invention will be described below with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.
FIG. 1 is a perspective view showing the overall configuration of the projector according to the present embodiment, FIG. 2 is a perspective view of a color synthesis prism, and FIG. 3A shows light that is transmitted through and reflected by the first polarization separation film. FIG. 3B is a diagram illustrating an optical path of light transmitted through the second polarization separation film, and FIG. 4 is a schematic diagram illustrating an example of a diffractive optical element. 4 (a) is a plan view, FIG. 4 (b) is a cross-sectional view taken along line AA in FIG. 4 (a), and FIG. 5 is a perspective view showing illumination light generated by the diffractive optical element. The polarizing prism and the first polarization separation film are omitted.

[One Embodiment]
An embodiment of a projector according to the present invention will be described with reference to FIGS.
In this embodiment, a front-type projection projector that projects color light including image information generated by a spatial light modulator as a projector on a screen (projected surface) through a projection system will be described as an example. .

As shown in FIG. 1, the projector 1 according to the present embodiment uses a reflective screen 55 and projects light including image information onto the screen 55 from the front side of the screen 55.
As shown in FIG. 1, the projector 1 includes an illumination device 10, a light modulation device 20, a cubic color synthesis prism (color synthesis unit, polarization separation unit) 30, and a projection lens (projection unit) 50. ing.

  The illumination device 10 is a device that illuminates the light modulation device 20, and includes a red illumination device 10R, a green illumination device 10G, and a blue illumination device 10B. The red illumination device 10R includes a laser light emitting unit (light source) 11R that emits red laser light and a diffractive optical element 12R that diffracts the light emitted from the laser light emitting unit 11R. Similarly, the green illumination device 10G includes a laser light emitting unit (light source) 11G that emits green laser light and a diffractive optical element 12G, and the blue illumination device 10B emits a blue laser light (laser light emitting unit (light source) (G). Light source) 11B and a diffractive optical element 12B. In this embodiment, the light emitted from the red illumination device 10R is P-polarized light, the light emitted from the green illumination device 10G is S-polarized light, and the light emitted from the blue illumination device 10B is P. Polarized light.

In addition, the light modulation device 20 is a two-dimensional reflective red liquid crystal light valve 20R for red light that modulates light emitted from the red illumination device 10R according to image information, and light emitted from the green illumination device 10G. A two-dimensional reflective green liquid crystal light valve 20G that modulates light according to image information, and a two-dimensional reflective blue liquid crystal light that modulates light emitted from the blue illumination device 10B according to image information. It consists of a valve 20B.
Each of the liquid crystal light valves 20R, 20G, and 20B has a reflective pixel electrode (not shown) that reflects incident light. Accordingly, the liquid crystal light valves 20R, 20G, and 20B modulate the light emitted from the diffractive optical elements 12R, 12G, and 12B and reflect the light toward the color synthesis prism 30.

The green illumination device 10G is arranged so that the optical path of the emitted light is perpendicular to the optical path of the red light emitted from the red illumination device 10R. A polarizing prism 14 is arranged on the optical path of the red light emitted from the red illumination device 10R, and the optical path of the light emitted from the green illumination device 10G is the same as the optical path of the red light by the polarizing prism 14. Follow the light path. In the present embodiment, the polarizing prism 14 transmits P-polarized light and reflects S-polarized light. A field lens 13 a is disposed between the polarizing prism 14 and the color combining prism 30. The light emitted from the laser light emitting units 11R and 11G of the red illumination device 10R and the green illumination device 10G is vertically incident on the red liquid crystal light valve 20R and the green liquid crystal light valve 20G by the field lens 13a.
Further, a field lens 13b is disposed between the diffractive optical element 12B of the blue illumination device 10B and the color synthesis prism 30. By this field lens 13b, the light emitted from the laser light emitting unit 11B of the blue illumination device 10B is perpendicularly incident on the blue liquid crystal light valve 20B.

The color synthesis prism (color synthesis unit) 30 is a prism that synthesizes red light, green light, and blue light emitted from the red illumination device 10R, the green illumination device 10G, and the blue illumination device 10B. The color synthesizing prism 30 includes a first polarization separation film 41 and a second polarization separation film 42 provided to intersect the first polarization separation film 41.
The first polarization separation film 41 and the second polarization separation film 42 are films that transmit P-polarized light (polarized light that vibrates in one direction) and reflect S-polarized light (polarized light that vibrates in the other direction).
The projection lens 50 is a device that projects the light combined by the color combining prism 30 onto the screen 55.

Next, details of the color combining prism 30 will be described with reference to FIG.
As shown in FIG. 2, the color combining prism 30 has a cubic shape formed by joining two triangular pyramid-shaped prisms 30a and 30c and two quadrangular pyramid-shaped prisms 30b and 30d. When expressed using the XYZ coordinate axes with one corner 31 of the color synthesis prism 30 as a reference, each corner of the color synthesis prism 30 has a first corner (x0, y0, z0) 31 and a second corner. (X1, y0, z0) 32, third corner (x1, y1, z0) 33, fourth corner (x0, y1, z0) 34, fifth corner (x0, y0, z1) 35, sixth A corner (x1, y0, z1) 36, a seventh corner (x1, y1, z1) 37, and an eighth corner (x0, y1, z1) 38 are obtained.
The first polarization separation film 41 is a surface that is perpendicular to the XY plane and forms approximately 45 ° with respect to the XZ plane and the YZ plane, that is, a fifth corner portion 35, a sixth corner portion 37, and a third corner portion 33. , Formed on the surface constituted by the fourth corner 31. The second polarization separation film 42 is a plane perpendicular to the YZ plane and forming an angle of about 45 ° with respect to the XY plane and the XZ plane, that is, the fifth corner portion 35, the sixth corner portion 36, and the third corner. It is formed on the surface constituted by the portion 33 and the fourth corner portion 34.

As shown in FIG. 3A, the red illumination device 10 </ b> R includes a first corner portion 35, a first corner portion 31, a fourth corner portion 34, and an eighth corner portion 38 of the color combining prism 30. It is arranged to face the surface 39a. The light emitted from the laser light emitting unit 11R and the laser light emitting unit 11G is incident on the first polarization separation film 41 at an angle of 45 °, and the red light (P-polarized light) is the first light. The green light (S-polarized light) passes through the polarization separation film 41 and reflects from the first polarization separation film 41.
As illustrated in FIG. 3B, the blue illumination device 10 </ b> B includes a second corner portion 35, a sixth corner portion 36, a seventh corner portion 37, and an eighth corner portion 38 of the color synthesis prism 30. It is arranged to face the surface 39b. The light is incident on the second polarization separation film 42 at 45 °, and blue light (P-polarized light) is transmitted through the second polarization separation film 42.

As shown in FIG. 1, the red liquid crystal light valve 20 </ b> R is disposed to face a third surface 39 c opposite to the first surface 39 a of the color combining prism 30. The green liquid crystal light valve 20G is disposed to face the fourth surface 39d formed by the eighth corner portion 38, the seventh corner portion 37, the third corner portion 33, and the fourth corner portion 34 of the color combining prism 30. ing. The blue liquid crystal light valve 20B is disposed to face the fifth surface 39e formed by the first corner portion 31, the second corner portion 32, the third corner portion 33, and the fourth corner portion 34 of the color combining prism 30. ing.
The projection lens 50 is disposed so as to face the sixth surface 39f opposite to the fourth surface 39d of the color synthesis prism 30.

Details of the diffractive optical elements 12R, 12G, and 12B will be described with reference to FIG.
The diffractive optical elements 12R, 12G, and 12B are formed of a material that can transmit laser light, such as quartz (glass), a transparent synthetic resin, and the like. The diffractive optical elements 12R, 12G, and 12B of the present embodiment are computer generated holograms (CGH).
The diffractive optical elements (hologram elements) 12R, 12G, and 12B have an illumination area setting function, a diffused light generation function (illuminance equalization function), and an enlarged illumination function. The diffractive optical elements 12R, 12G, and 12B having the illumination area setting function diffract the incident light and generate irradiation light that illuminates the incident end face of the liquid crystal light valve 20. In addition, the diffractive optical elements 12R, 12G, and 12B having a diffused light generation function make the illuminance at least part of a predetermined region uniform.

In FIG. 4, the diffractive optical elements 12R, 12G, and 12B have a plurality of rectangular recesses (uneven structure) 12M on the surface. The recesses 12M have different depths. Also, the plurality of convex portions between the concave portions 12M have different heights.
Then, by appropriately adjusting the surface conditions of the diffractive optical elements 12R, 12G, and 12B including the pitch d between the concave parts 12M and the depth (height of the convex part) t of the concave parts 12M, the diffractive optical elements 12R, 12G, and 12B are appropriately adjusted. Can have predetermined functions (an illumination area setting function, a diffused light generation function, and an enlarged illumination function). As a design method for optimizing the surface condition, a predetermined calculation method (simulation method) such as an iterative Fourier method is exemplified.

  Note that the diffractive optical elements 12R, 12G, and 12B are not limited to those having the rectangular recesses 12M, and may have surfaces that combine planes that face different directions. For example, the diffractive optical elements 12R, 12G, and 12B may be so-called blazed types having triangular concave portions having inclined surfaces. Further, the diffractive optical elements 12R, 12G, and 12B may each have a region having a rectangular recess 12M as shown in FIG. 4 and a region having a triangular recess. Then, by optimizing the surface conditions, diffractive optical elements 12R, 12G, and 12B having a desired function can be formed.

In the present embodiment, the light emitted from the laser light emitting units 11R, 11G, and 11B is divided into two triangular illumination lights by the diffractive optical elements 12R, 12G, and 12B. Here, the red liquid crystal light valve 20R illuminated by the red illumination device 10R will be described as an example.
As shown in FIG. 5, the diffractive optical element 12 </ b> R of the red illumination device 10 </ b> R generates illumination light that does not enter the second polarization separation film 42. As a result, the illumination light generated by the diffractive optical element 12R is smaller than the two regions B1 and B2 divided by the second polarization separation film 42 on the first surface 39a of the color synthesis prism 30. The light emitted from the diffractive optical element 12R, passing through the region B1, and transmitted through the first polarization separation film 41 illuminates the region A1 divided by the diagonal line of the incident end face 20a of the red liquid crystal light valve 20R. Further, the light emitted from the diffractive optical element 12R, passing through the region B2, and transmitted through the first polarization separation film 41 illuminates the region A2 divided by the diagonal line of the incident end surface 20a of the red liquid crystal light valve 20R. The illumination area of the illumination light divided into two comes into contact with the diagonal line of the incident end face 20a of the red liquid crystal light valve 20R. FIG. 5 shows only illumination light that is diffracted by the diffractive optical element 12R, passes through the region B1, and illuminates the region A1 of the red liquid crystal light valve 20R.
The same applies to the illumination light divided into two emitted from the diffractive optical element 12G of the green illumination device 10G, and the illumination area of the illumination light reflected from the first polarization separation film 41 is the green liquid crystal light valve. Contact is made on the diagonal line of the 20G incident end face 20a. Further, the optical path can be controlled by the above-described field lens 13a so that the light generated by each of the diffractive optical elements 12R and 12G does not enter the second polarization separation film 42.

As shown in FIG. 1, the diffractive optical element 12 </ b> R of the blue illumination device 10 </ b> B generates illumination light that does not enter the first polarization separation film 42. As a result, the illumination light generated by the diffractive optical element 12B is smaller than the two regions C1 and C2 divided by the first polarization separation film 41 on the second surface 39b of the color combining prism 30. Thus, the illumination light generated by the diffractive optical element 12B does not enter the first polarization separation film 41. Then, the illumination area of the illumination light divided into two that is emitted from the diffractive optical element 12B and transmitted through the second polarization separation film 42 is also illuminated with the blue liquid crystal light valve 20B in the same manner as when the red liquid crystal light valve 20R is illuminated. It contacts on the diagonal of the incident end face 20a. Further, the optical path can be controlled so that the light generated by each diffractive optical element 12B does not enter the first polarization separation film 41 by the field lens 13b described above.
In this way, the two illuminating lights diffracted and divided by the diffractive optical elements 12R, 12G, and 12B are combined on the incident end faces 20a of the liquid crystal light valves 20R, 20G, and 20B to form rectangular illumination lights. . This illumination light is light that illuminates the entire image forming area of the liquid crystal light valves 20R, 20G, and 20B. In addition, the concave portions 12M of the diffractive optical elements 12R, 12G, and 12B are formed so that the light divided into two does not overlap.

Next, a method for projecting an image on the screen 55 using the projector 1 of the present embodiment having the above configuration will be described.
The P-polarized red light emitted from the red illumination device 10 </ b> R is divided into two lights by the diffractive optical element 12 </ b> R and passes through the polarizing prism 14. Then, the red light does not enter the second polarization separation film 42 of the color synthesis prism 30, but passes through the first polarization separation film 41 and is emitted from the third surface 39c as shown in FIG. (Dotted line shown in FIG. 3A), the red liquid crystal light valve 20R is illuminated. The light incident on the red liquid crystal light valve 20R is modulated in accordance with the image information. The light of the component incident on the color combining prism 30 again, modulated by the red liquid crystal light valve 20R and converted into S-polarized light is the first. The light is reflected by the polarization separation film 41 and emitted from the sixth surface 39 f of the color synthesis prism 30.

The S-polarized green light emitted from the green illumination device 10G is divided into two lights by the diffractive optical element 12G and reflected by the polarizing prism 14. Then, the green light does not enter the second polarization separation film 42 of the color synthesis prism 30, but is reflected from the first polarization separation film 41 and emitted from the fourth surface 39d as shown in FIG. (The two-dot chain line shown in FIG. 3A) illuminates the green liquid crystal light valve 20G. The light incident on the green liquid crystal light valve 20G is modulated in accordance with the image information. The light of the component incident on the color combining prism 30 again, modulated by the green liquid crystal light valve 20G and converted into P-polarized light is the first. The light passes through the polarization separation film 41 and is emitted from the sixth surface 39 f of the color synthesis prism 30.
The P-polarized blue light emitted from the blue illumination device 10B is divided into two lights by the diffractive optical element 12B and enters the color synthesis prism 30. Then, the blue light does not enter the first polarization separation film 41 of the color synthesis prism 30, but passes through the second polarization separation film 42 and is emitted from the fifth surface 39e as shown in FIG. 3B. The blue liquid crystal light valve 20B is illuminated. The light incident on the blue liquid crystal light valve 20B is modulated in accordance with the image information. The light of the component incident on the color combining prism 30 again, modulated by the blue liquid crystal light valve 20B and converted into S-polarized light is the second. The light is reflected by the polarization separation film 42 and emitted from the sixth surface 39 f of the color synthesis prism 30.
In this way, red light, green light, and blue light are combined in the color combining prism 30 and enlarged and projected onto the screen 55 by the projection lens 50.

  As described above, in the projector 1 according to this embodiment, the diffractive optical elements 12R and 12G prevent the red light and the green light emitted from the red illumination device 10R and the green illumination device 10G from entering the second polarization separation film 42. Generate illumination light. Thereby, it is possible to suppress the second polarization separation film 42 from being projected as a shadow on each of the liquid crystal light valves 20R and 20G. In addition, the diffractive optical element 12B generates illumination light so that light emitted from the blue illumination device 10B does not enter the first polarization separation film 41. Thereby, it is possible to suppress the first polarization separation film 41 from being projected as a shadow on the blue liquid crystal light valve 20B. Therefore, color composition by the color composition prism 30 and projection of a display shadow on the screen 55 can be suppressed, so that image quality can be improved.

  Further, the light emitted from the laser light emitting units 11R, 11G, and 11B is divided into two light beams by the diffractive optical elements 12R, 12G, and 12B provided for one type of color light, and the liquid crystal light valves 20R, 20G, and Since the configuration illuminates 20B, the overall size of the apparatus can be reduced as compared with the case where two light beams are generated using a plurality of diffractive optical elements.

In the present embodiment, illumination light is generated by the diffractive optical elements 12R, 12G, and 12B so that the areas A1 and A2 of the liquid crystal light valves 20R, 20G, and 20B do not overlap with each other, as shown in FIG. The illumination light may be generated so as to overlap. That is, the two illumination lights are overlapped so as not to cause a gap between the areas A1 and A2 illuminated by the two lights. In this case, since the intensity of the overlapping region A3 is increased, the modulation amount of the pixels of the liquid crystal light valves 20R, 20G, and 20B corresponding to the region A3 may be adjusted based on the illuminance distribution of the incident light. Thereby, since the overlapping portion does not become excessively bright, it is possible to project a clear image on the screen 55. In addition, the amount of modulation in the liquid crystal light valves 20R, 20G, and 20B is adjusted based on the illuminance distribution of the illumination light incident on the liquid crystal light valves 20R, 20G, and 20B, not only when the illuminated areas overlap. May be.
In addition, the red illumination device 10R, the green illumination device 10G, and the blue illumination device 10B are used as the light source, but color separation is performed by a dichroic mirror (color separation means) using an illumination device that emits white laser light. It is also possible to have a configuration.
The polarization prism 14 may be a polarization separation element having a wire grid structure.
Further, although the laser light emitting units 11R, 11G, and 11B that emit light that vibrates in one direction are used, the illumination devices 20R, 20G, and 20B have polarization conversion elements, and light that vibrates in one direction by the polarization conversion elements. May be converted to

[Modification of Embodiment]
In the embodiment shown in FIG. 1, one diffractive optical element 12R, 12G, 12B is provided for one type of color light, but a plurality of diffractive optical elements 62a, 62b may be provided. Such a modification will be described with reference to FIG. In this modification, the red illumination device 60R will be described as an example.
As shown in FIG. 7, the red illumination device 60R of the present modification includes two laser light emitting units (light sources) 61a and 61b, and diffractive optical elements 62a and 62b provided corresponding to the laser light emitting units 61a and 61b. It has. The light diffracted by the diffractive optical elements 62a and 62b is triangular illumination light. That is, the illumination light generated by each diffractive optical element 62a, 62b is smaller than the two regions B1, B2 divided by the second polarization separation film 42 on the first surface 39a. Thereby, similarly to the embodiment, the light emitted from each of the diffractive optical elements 62a and 62b illuminates the red liquid crystal light valve 20R without entering the second polarization separation film 42.
A field lens 63 is disposed between the diffractive optical elements 62 a and 62 b and the color synthesis prism 30. The effective diameter of the field lens 63 is large enough to capture light diffracted by each of the diffractive optical elements 62a and 62b.

  As described above, in this modification, the light diffracted by each of the two diffractive optical elements 62 a and 62 b enters the color combining prism 30. Accordingly, it is easier to generate a plurality of light beams by providing the two diffractive optical elements 62a and 62b than when a plurality of light beams are generated by one diffractive optical element. Therefore, the design of the pattern shape of the diffractive optical elements 62a and 62b is facilitated.

  In addition, although the two laser light emission parts 61a and 61b were provided, the structure provided with the one laser light emission part 71 may be sufficient as shown in FIG. In this configuration, the diffractive optical element 62a is provided on the optical path of the red light emitted from the laser light emitting unit 71, the red light emitted from the laser light emitting unit 71 is separated using the beam splitter 72 and the reflection mirror 73, and Red light is incident on the diffractive optical element 62b. As a result, the number of the laser light emitting units 71 can be reduced as compared with the above-described modification example, so that the size and cost of the apparatus can be reduced.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the illumination device using the light source and the color synthesis prism described above is not limited to a projector, but can be applied to all optical systems using laser light such as a laser processing machine and an exposure device.
Further, for example, the above-described implementation is applied to a so-called slide projector that does not include a liquid crystal light valve and illuminates the surface of a slide (positive film) including image information with a lighting device and projects light including image information on a screen. It is also possible to apply a lighting device of the form.
In the above embodiment, the front projection type projector (image display device) has been described as an example, but a rear projection type projector (rear projector) may be used.

1 is a schematic configuration diagram of a projector according to an embodiment of the present invention. It is a perspective view which shows the color synthesis prism of FIG. It is a perspective view which shows the optical path for every color which passes the color synthetic | combination prism of FIG. It is principal part sectional drawing which shows the structure of the diffractive optical element of FIG. It is a perspective view which shows the illumination area | region of the light inject | emitted from the illuminating device of FIG. It is a top view which shows the modification of the projector which concerns on one Embodiment of this invention. It is a top view which shows the modification of the projector which concerns on one Embodiment of this invention. It is a top view which shows the other modification of the projector which concerns on one Embodiment of this invention. It is a perspective view which shows the color synthetic | combination prism illuminated with the conventional illuminating device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Illuminating device, 11R, 11G, 11B, 61a, 61b, 71 ... Laser light emission part (light source), 12R, 12G, 12B, 62a, 62b ... Diffractive optical element, 20R ... Light modulator for red ( Reflective light modulation element), 20G... Green light modulation device (reflection light modulation element), 20B... Blue light modulation device (reflection light modulation element), 30... Color synthesis prism (color synthesis unit), 41. First polarization separation film, 42 ... second polarization separation film, 50 ... projection lens (projection means), 55 ... screen (projection surface),

Claims (8)

A light source that emits laser light including multiple types of color light;
A plurality of diffractive optical elements provided on respective optical paths of the plurality of types of color light, diffracting light emitted from the light source, and generating illumination light;
A plurality of reflective light modulation elements that modulate and reflect illumination light generated by the plurality of diffractive optical elements;
Polarized light that enters at least one color light out of the light emitted from the diffractive optical element and the reflective light modulation element, transmits polarized light that vibrates in one direction, and vibrates in the other direction. A color synthesizing unit that has a first polarization separation film and a second polarization separation film for reflecting light, and synthesizes light modulated by the plurality of reflective light modulation elements;
Projecting means for projecting the light synthesized by the color synthesis unit onto the projection surface;
The first polarization separation film and the second polarization separation film are provided to intersect with each other;
The color synthesis is performed so that the diffractive optical element does not enter the polarization separation film different from the polarization separation film from which the light emitted from the light source out of the first polarization separation film and the second polarization separation film is separated. A projector characterized by causing a plurality of light beams to enter the part. One diffractive optical element is provided for one type of color light,
The projector according to claim 1, wherein the light emitted from the light source is divided into a plurality of light beams by the diffractive optical element and is incident on the color composition unit. A plurality of the diffractive optical elements are provided for one type of color light,
The light emitted from the light source is incident on each of the plurality of diffractive optical elements;
The projector according to claim 1, wherein a plurality of light beams diffracted and generated by each of the plurality of diffractive optical elements are incident on the color combining unit. The light source emits white light including a plurality of types of colored light,
4. The projector according to claim 1, further comprising a color separation unit that separates white light emitted from the light source for each of the plurality of types of color light. 5.   5. The projector according to claim 1, wherein the diffractive optical element generates illumination light such that regions that illuminate the reflective light modulation element overlap. 6.   6. The modulation amount in the reflection type light modulation element is adjusted based on an illuminance distribution of illumination light incident on the reflection type light modulation element. 6. Projector.   The projector according to claim 1, wherein the diffractive optical element is a hologram element. A light source that emits laser light including multiple types of color light;
A plurality of diffractive optical elements provided on respective optical paths of the plurality of types of color light, diffracting light emitted from the light source, and generating illumination light;
At least one type of color light is incident among the illumination light generated by the plurality of diffractive optical elements, and the polarized light that vibrates in one direction is transmitted among the incident light, and the polarized light that vibrates in the other direction is reflected. A polarization separation section having a first polarization separation film and a second polarization separation film,
The polarization separation so that the light emitted from the light source does not enter the polarization separation film different from the polarization separation film of the first polarization separation film and the second polarization separation film by the diffractive optical element. A lighting device characterized by causing a plurality of light beams to enter the part.

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