JP2005189295A - Color separation/synthesis optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an adhesive layer in a polarization separation element such as a polarization beam splitter from being deteriorated due to transmission of luminous flux, and to prevent the degradation of optical characteristics which is caused by the transmission of the luminous flux through the adhesive layer, in a color separation/synthesis optical system. <P>SOLUTION: Blue component light does not pass through an adhesive layer 2b in a first polarization beam splitter 2 but is reflected by a polarization separation film 2a. Then, the blue component light does not pass through the adhesive layer 7b in a third polarization beam splitter 7 but is reflected by a polarization separation film 7a and is made incident on a reflection type spatial optical modulation element 8 for blue. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color separation / combination optical system that splits an incident light beam into three primary colors, recombines and emits the same, and an image display device configured using such a color separation / combination optical system.

  Conventionally, an image display apparatus using a reflective spatial light modulator has been proposed. In such an image display device, as described in Patent Document 1 and Patent Document 2, a color separation / synthesis optical system configured using a polarization beam splitter is used. This color separation / synthesis optical system separates an incident light beam from a light source into three primary colors, illuminates a reflective spatial light modulation element for each color with these three primary color lights, and reflects the reflected light beam from these reflective spatial light modulation elements. It is an optical system that combines again and emits it toward the imaging system.

  FIG. 6 is a plan view showing a configuration of a conventional color separation / synthesis optical system used in the image display apparatus.

  In this color separation / synthesis optical system, a light beam emitted from a light source (not shown) is made into a substantially parallel light beam, and is made into linearly polarized light and incident. This incident light beam includes red component light R, green component light G, and blue component light B, the component light of each color is linearly polarized, and the polarization plane of each color component light is in the same direction. Yes.

  This incident light beam is incident on the first laminated phase difference filter 101. This laminated phase difference filter 101 is an optical element configured by laminating phase difference plates, and is a filter that rotates the direction of the polarization plane of only a specific wavelength band by 90 °. In the light flux that has passed through the first laminated phase difference filter 101, the polarization plane of the green component light G is orthogonal to the polarization planes of the red component light R and the blue component light B.

  The light beam that has passed through the first laminated phase difference filter 101 is incident on the first polarization beam splitter 102. In the first polarization beam splitter 102, the green component light G is P-polarized, the red component light R, and the blue component light B are S-polarized with respect to the polarization separation film 102a. Accordingly, in the first polarization beam splitter 102, the red component light R and the blue component light B are reflected by the polarization separation film 102a, and the green component light G is transmitted through the polarization separation film 102a.

  The red component light R and the blue component light B emitted from the first polarization beam splitter 102 are incident on the second stacked phase difference filter 103. The second laminated phase difference filter 103 transmits the red component light R and the blue component light B with the polarization plane of the red component light R orthogonal to the polarization plane of the blue component light B.

  The light beam that has passed through the second stacked phase difference filter 103 is incident on the second polarization beam splitter 104. In the second polarization beam splitter 104, the red component light R is P-polarized light and the blue component light B is S-polarized light with respect to the polarization separation film 104a. The red component light R is transmitted through the polarization separation film 104 a, is emitted from the second polarization beam splitter 104, and enters the red reflective spatial light modulator 105. Further, the blue component light B is reflected by the polarization separation film 104 a, is emitted from the second polarization beam splitter 104, and enters the blue reflective spatial light modulation element 106.

  The red reflective spatial light modulator 105 and the blue reflective spatial light modulator 106 are so-called reflective liquid crystal display devices, which respectively modulate the polarization of incident light according to the red and blue components of the display image. Reflect.

  The first modulated light modulated and reflected by the red reflective spatial light modulator 105 is incident on the second polarization beam splitter 104 again. Since the first modulated light is S-polarized with respect to the polarization separation film 104a, the first modulated light is reflected by the polarization separation film 104a and is transmitted from the second polarization beam splitter 104 to the first polarization beam splitter 102. The light is emitted in a direction different from the returning direction.

  The second modulated light modulated and reflected by the blue reflective spatial light modulator 106 is incident on the second polarization beam splitter 104 again. Since the second modulated light is P-polarized with respect to the polarization separation film 104a, the second modulated light is transmitted through the polarization separation film 104a and is transmitted from the second polarization beam splitter 104 to the first polarization beam splitter 102. The light is emitted in a direction different from the direction returning to.

  On the other hand, the green component light G emitted from the first polarization beam splitter 102 is incident on the third polarization beam splitter 107. In the third polarization beam splitter 107, the green component light G is P-polarized with respect to the polarization separation film 107a. The green component light G passes through the polarization separation film 107a, is emitted from the third polarization beam splitter 107, and is incident on the green reflective spatial light modulator 108. The green reflective spatial light modulator 108 is a so-called reflective liquid crystal display device, and reflects incident light by polarization-modulating it according to the green component of the display image.

  The third modulated light modulated and reflected by the green reflective spatial light modulator 108 is incident on the third polarizing beam splitter 107 again. Since the third modulated light is S-polarized light with respect to the polarization separation film 107 a, it is reflected by the polarization separation film 107 a and is transmitted from the third polarization beam splitter 107 to the first polarization beam splitter 102. The light is emitted in a direction different from the direction returning to.

  The first and second modulated lights emitted from the second polarization beam splitter 104 are incident on the third stacked phase difference filter 109. The third stacked phase difference filter 109 rotates the polarization plane of the first modulated light by 90 °, transmits the first and second modulated lights, and enters the fourth polarizing beam splitter 110. At this time, the polarization planes of the first and second modulated lights are in the same direction.

  Further, the third modulated light emitted from the third polarizing beam splitter 107 is incident on the fourth polarizing beam splitter 110.

  In the fourth polarization beam splitter 110, the first and second modulated lights are P-polarized and the third modulated light is S-polarized with respect to the polarization separation film 110a. The first and second modulated lights pass through the polarization separation film 110 a and are emitted from the fourth polarization beam splitter 110. The third modulated light is reflected by the polarization separation film 110 a and emitted from the fourth polarization beam splitter 110. In this way, the first and second modulated light and the third modulated light are combined.

  The first to third modulated lights emitted from the fourth polarization beam splitter 110 are incident on the fourth stacked phase difference filter 111. The fourth laminated phase difference filter 111 rotates the polarization plane of the third modulated light by 90 ° and transmits the first to third modulated lights. The first to third modulated lights that have passed through the fourth laminated phase difference filter 111 have the same polarization plane.

The first to third modulated light beams that have passed through the fourth stacked phase difference filter 111 are transmitted through the polarizing plate 112, thereby removing unnecessary light having different polarization plane directions and entering a projection optical system (not shown). . The projection optical system projects the first to third modulated light onto the screen and displays an image.
JP 2002-287094 A JP 2000-284228 A

A polarization beam splitter used in the color combining optical system as described above, as shown in FIG. 7, the first triangular prism 120 ₁ the polarization separation film 120a is formed by vapor deposition on one surface, the second 1 of the triangular prism 120 _first polarization separation film 120a the polarization separation film 120a and the second triangular prism 120 ₂ Metropolitan bonded via an adhesive layer 120b against was formed surface, configured cubical ing.

The light beam incident on the polarization beam splitter 120 and transmitted through the polarization separation film 120a passes through the adhesive layer 120b once. Further, the light beam is reflected by the polarization separation film 120a is incident from the second triangular prism 120 ₂ side to the polarizing beam splitter 120, so that the passing through the adhesive layer 120b 2 times.

For example, in a conventional color combining optical system as described above, incident light to the first polarization beam splitter 102 is incident from the second triangular prism 102 ₂ side, also, the incident light to the second polarizing beam splitter 104 also when the incident from the second triangular prism 104 ₂ side, the blue component light, when black display is an adhesive layer transmitted twice in the first polarization beam splitter 102, in the second polarizing beam splitter 104 Since the adhesive layer is transmitted twice, the adhesive layer is transmitted four times before reaching the blue reflective spatial light modulator 106. Since the blue component light reflected by the blue reflective spatial light modulator 106 follows the same path as when it is incident and returns to the light source side, the first and second polarization beam splitters 102, At 104, the adhesive layer is transmitted twice. That is, in each of the first and second polarizing beam splitters 102 and 104, the blue component light is transmitted through the adhesive layer four times.

  In this case, when the blue component light is displayed in white, the first polarizing beam splitter 102 transmits the adhesive layer twice, and the second polarizing beam splitter 104 also transmits the adhesive layer twice. Therefore, the adhesive layer is transmitted four times before reaching the blue reflective spatial light modulator 106. Then, the blue component light reflected by the blue reflective spatial light modulator 106 passes through the adhesive layer and the polarization separation film 104a of the second polarization beam splitter 104, and is transmitted from the second polarization beam splitter 104. Emitted. That is, the blue component light is transmitted through the adhesive layer twice in the first polarizing beam splitter 102 and three times in the second polarizing beam splitter 104.

  By the way, since the adhesive which bonds each triangular prism in a polarizing beam splitter has the property to absorb short wavelength light, it absorbs blue component light among visible light used for image display. As the adhesive layer absorbs light in this manner over a long period of time, the characteristics gradually deteriorate and the transmittance gradually decreases. Finally, the adhesive layer may be burned.

  Accordingly, the present invention provides a color separation / synthesis optical system for use in an image display device having a reflective spatial light modulation element, which prevents deterioration due to transmission of a light flux of an adhesive layer in a polarization separation element such as a polarization beam splitter. It is an object of the present invention to provide an illustrated color separation / synthesis optical system, and to provide an image display apparatus configured using such a color separation / synthesis optical system.

  In order to solve the above-described problems, in the color separation / synthesis optical system according to the present invention, a linearly polarized white light beam is incident, and the polarization planes of the red component light and the green component light of the incident beam are blue component light. A first wavelength-selective polarization conversion means that is orthogonal to the plane of polarization of the light, and a polarization separation film on which a light beam that has passed through the first wavelength-selective polarization conversion means is incident, and this polarization separation film From the first polarization separation element, the first polarization separation element that branches the optical path of the red component light, the green component light, and the blue component light by transmitting the P polarization component and reflecting the S polarization component A second component in which red component light and green component light are incident and the polarization plane of the first color component light and the polarization plane of the second color component light of the red component light and the green component light are orthogonal to each other. Wavelength selective polarization conversion means, and the second wave The first and second color component lights are incident from the selective polarization conversion means, the first color component light is incident on the first spatial light modulator, and the second color component light is incident on the second spatial light. A second polarization separation element that is incident on the modulation element; a third polarization separation element that receives blue component light from the first polarization separation element and causes the blue component light to be incident on the third spatial light modulation element; The modulated light of the red component light and the green component light that has passed through the first and second spatial light modulation elements and the modulated light of the blue component light that has passed through the third spatial light modulation element are incident, and each of these modulated lights And at least one of the first and third polarization separation elements includes a first prism on which a polarization separation film is formed, and the first prism of the first prism. The polarization separation film and the adhesive layer are interposed on the surface on which the polarization separation film is formed. A polarization beam splitter composed of a bonded second prism, wherein the blue component light directed to the third spatial light modulator is incident on the polarization beam splitter from the first prism and the polarization separation is performed. Reflected by the film and emitted from the first prism.

  Preferably, the first or third polarization separation element is a wire grid type polarization separation element.

  Preferably, the first polarization separation element is a dichroic wavelength separation film (dichroic filter).

  Preferably, in the color separation / combination optical system according to the present invention, a linearly polarized white light beam is incident, and the polarization planes of the red component light and the green component light of the incident beam are relative to the polarization plane of the blue component light. The first wavelength-selective polarization conversion means that is orthogonal to each other, and a polarization separation film on which the light beam that has passed through the first wavelength-selective polarization conversion means is incident. A first polarization separation element that splits the optical path of the red component light, the green component light, and the blue component light by transmitting and reflecting the S polarization component, and the red component light and the green light from the first polarization separation element Second wavelength selective polarization in which component light is incident and polarization plane of first color component light and polarization plane of second color component light are orthogonal to each other among red component light and green component light Conversion means and the second wavelength selective polarization change The first and second color component lights are incident from the means, the first color component light is incident on the first spatial light modulation element, and the second color component light is incident on the second spatial light modulation element A second polarization separation element that causes the blue component light to be incident from the first polarization separation element, and causes the blue component light to enter the third spatial light modulation element, and the first polarization separation element. And the modulated light of the red component light and the green component light having passed through the second spatial light modulation element and the modulated light of the blue component light having passed through the third spatial light modulation element are incident, and these modulated lights are combined. The first polarization separation element is a wire grid type polarization separation element or a dichroic wavelength separation film, and the third polarization separation element is a wire grid type polarization separation element.

  In the image display apparatus according to the present invention, the color separation / synthesis optical system and a light flux that is linearly polarized and includes at least red component light, green component light, and blue component light with respect to the color separation / synthesis optical system. A light source unit that makes the light incident; and an imaging optical system that forms an image of the light beam emitted from the polarization combining element of the color separation / synthesis optical system.

  In the color separation / synthesis optical system according to the present invention, the blue component light does not pass through the adhesive layer in the polarization separation element until it is incident on the spatial light modulation element. In addition, it is possible to prevent optical characteristics from deteriorating due to the light flux passing through the adhesive layer.

  In the image display device according to the present invention, in the color separation / synthesis optical system, the blue component light does not pass through the adhesive layer in the polarization separation element until it is incident on the spatial light modulation element. The durability can be improved by preventing the deterioration of the characteristics due to the transmission of the light beam.

  That is, the present invention relates to a color separation / synthesis optical system used for an image display device having a reflective spatial light modulation element, and the like, and the deterioration of the adhesive layer due to transmission of a light beam in a polarization separation element such as a polarization beam splitter. In addition, the present invention provides a color separation / synthesis optical system in which optical properties are prevented from being deteriorated due to the light beam passing through such an adhesive layer, and such a color separation / synthesis optical system is provided. It is possible to provide an image display device configured by using the above.

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

[First Embodiment]
FIG. 1 is a plan view showing a first embodiment of an image display apparatus according to the present invention using a color separation / synthesis optical system according to the present invention.

  In this color separation / synthesis optical system, as shown in FIG. 1, a light beam is incident on a first laminated phase difference filter 1 serving as a first wavelength-selective polarization conversion unit by an illumination optical system 13 serving as a light source unit. The

  The illumination optical system 13 includes a light source 14 and a concave mirror 15 that collects a light beam emitted from the light source 14. The light emitted from the light source 14 is reflected by the concave mirror 15, passes through the heat ray filter 16, passes through the condenser lens 17 and the polarization conversion element 18, and is emitted from the illumination optical system 13.

  The light beam emitted from the illumination optical system 13 is substantially a parallel light beam and linearly polarized light. The light beam emitted from the illumination optical system 13 includes red component light R, blue component light B, and green component light G. Each of these color component lights R, B, and G is linearly polarized, and the planes of polarization are in the same direction. In this embodiment, the polarization plane of each color component light of the incident light is in a direction parallel to the paper surface of FIG.

  The first laminated phase difference filter 1 to which the light beam from the illumination optical system 13 is incident is an optical element formed by laminating phase difference plates, and the direction of the polarization plane of only a specific wavelength band is 90 °. It is a filter to rotate. As such a laminated phase difference filter, for example, “Color Select” manufactured by Color Link can be used.

  In the light flux that has passed through the first laminated phase difference filter 1, the red component light R, the blue component light B, and the green component light G are each linearly polarized light, and the direction of the polarization plane of only the blue component light B is 90. Rotated, the polarization plane of the blue component light B is orthogonal to the polarization planes of the red component light R and the green component light G.

  The light beam that has passed through the first laminated phase difference filter 1 is incident on a first polarization beam splitter 2 that serves as a first polarization separation element. In the first polarization beam splitter 2, the red component light R and the green component light G are P-polarized and blue component light B with respect to the polarization separation film 2 a inclined at 45 ° with respect to the optical path of the incident light. Is S-polarized light. Therefore, in the first polarization beam splitter 2, the red component light R and the green component light G are transmitted through the polarization separation film 2a, and the blue component light B is reflected by the polarization separation film 2a. The optical path of the green component light G and the optical path of the blue component light B are branched according to the polarization plane direction.

The first polarizing beam splitter 2, a first triangular prism 2 ₁ polarization separation film 2a is formed on one surface by a deposition, the first triangular prism 2 _first polarization separation film 2a is formed and from this polarization separation film 2a and the second triangular prism 2 ₂ Metropolitan bonded through an adhesive layer 2b to the plane, and it is configured to cubic.

This for the first polarization beam splitter 2, a light beam transmitted through the first multilayer retardation filter 1 is incident from the first triangular prism 2 ₁ side. Thus, the blue component light B reflected at the polarization separation film 2a is reflected by the polarization splitting film 2a without passing through the adhesive layer 2b that is joined to the triangular prism, the first triangular prism 2 ₁ Emitted.

  The red component light R and the green component light G emitted from the first polarization beam splitter 2 are incident on the second laminated phase difference filter 3 serving as the second wavelength selective polarization conversion means. The second laminated phase difference filter 3 rotates the polarization plane of only the green component light G by 90 °, and the green component light G is in a state in which the polarization plane of the green component light G is orthogonal to the polarization plane of the red component light R. The component light G and the red component light R are transmitted.

  The light beam that has passed through the second laminated phase difference filter 3 is incident on a second polarization beam splitter 4 that serves as a second polarization separation element. In the second polarization beam splitter 4, the red component light R is P-polarized light and the green component light G is S-polarized light with respect to the polarization separation film 4 a inclined at 45 ° with respect to the optical path of the incident light. ing. The red component light R is transmitted through the polarization separation film 4a and the adhesive 4b layer, is emitted from the second polarization beam splitter 4, and is applied to the red reflective spatial light modulator 5 which is the first spatial light modulator. Incident. The green component light G is reflected by the polarization separation film 4a, is emitted from the second polarization beam splitter 4, and is incident on the green reflective spatial light modulation element 6 which is the second spatial light modulation element.

The second polarizing beam splitter 4, like the first polarization beam splitter 2, a first triangular prism 4 ₁ polarization splitting film 4a is formed on one surface by a deposition, the first triangle from the prism 4 ₁ of polarization splitting film 4a the polarization separation film with respect to formed surface 4a and the second triangular prism 4 ₂ Metropolitan bonded through an adhesive layer 4b, are configured in a cubic shape.

This second relative polarization beam splitter 2, light beam passing through the second stacked retardation filter 3 is incident from the first triangular prism 4 ₁ side. Thus, the green component light G is reflected at the polarization separation film 4a is reflected by the polarization splitting film 4a without passing through the adhesive layer 4b that is joined to the triangular prism, the first triangular prism 4 ₁ Emitted.

  The red reflective spatial light modulator 5 and the green reflective spatial light modulator 6 are so-called reflective liquid crystal display devices, which respectively modulate the polarization of incident light according to the red and green components of the display image. Reflect. Information on the display image is supplied from the outside to the red reflective spatial light modulator 5 and the green reflective spatial light modulator 6.

  The first modulated light modulated and reflected by the red reflective spatial light modulator 5 is incident on the second polarization beam splitter 4 again. The first modulated light is S-polarized with respect to the polarization separation film 4a when the red reflective spatial light modulation element 5 displays white, and is reflected by the polarization separation film 4a. The light is emitted from the second polarizing beam splitter 4 in a direction different from the direction returning to the first polarizing beam splitter 2.

  The second modulated light modulated and reflected by the green reflective spatial light modulator 6 is incident on the second polarization beam splitter 4 again. Since the second modulated light is P-polarized with respect to the polarization separation film 4a when the green reflective spatial light modulation element 6 is displaying white, the polarization separation film 4a and the adhesive layer 4b. And is emitted from the second polarization beam splitter 4 in a direction different from the direction returning to the first polarization beam splitter 2.

  On the other hand, the blue component light B emitted from the first polarization beam splitter 2 is incident on a third polarization beam splitter 7 serving as a third polarization separation element. A blue light transmission filter 7 c may be disposed between the first polarization beam splitter 2 and the third polarization beam splitter 7. In the third polarization beam splitter 7, the blue component light B is S-polarized with respect to the polarization separation film 7 a inclined at 45 ° with respect to the optical path of the incident light. The blue component light B is reflected by the polarization separation film 7a, is emitted from the third polarization beam splitter 7, and is incident on the blue reflective spatial light modulator 8 which is the third spatial light modulator. The blue reflective spatial light modulator 8 is a so-called reflective liquid crystal display device, and reflects incident light by polarization-modulating it according to the green component of the display image. Information of the display image is supplied to the blue reflective spatial light modulator 8 from the outside.

The third polarization beam splitter 7, like the first polarization beam splitter 2, a first triangular prism 7 ₁ polarization separation film 7a is formed on one surface by a deposition, the first triangle from the prism ₇₁ of the polarization splitting film 7a the polarization separation film with respect to formed surface 7a and the second triangular prism 7 ₂ Metropolitan bonded through an adhesive layer 7b, is configured to cubic. This for the third polarization beam splitter 7, the blue component light B emitted from the first polarization beam splitter 2 are incident from the first triangular prism 7 ₁ side. Therefore, the blue component light B is reflected by the polarization separation film 7a without passing through the adhesive layer 7b, and is emitted from the first triangular prism.

That is, the blue component light B is emitted from the first triangular prism 2 ₁ is reflected by the first incident from the triangular prism 2 ₁ polarization separation film 2a with respect to the first polarizing beam splitter 2, 3 to be the exit from the first triangular prism 7 ₁ is reflected by the first triangular prism 7 is incident from ₁ to polarization separation film 7a with respect to the polarization beam splitter 7 incident on the blue reflection type spatial light modulator 8 Therefore, the adhesive layer is never transmitted before reaching the blue reflective spatial light modulator 8.

  The third modulated light modulated and reflected by the blue reflective spatial light modulator 8 is incident on the third polarization beam splitter 7 again. Since the third modulated light is P-polarized with respect to the polarization separation film 7a when the blue reflective spatial light modulation element 8 displays white, the polarization separation film 7a and the adhesive layer 7b. And is emitted from the third polarizing beam splitter 7 in a direction different from the direction returning to the first polarizing beam splitter 2.

  The first and second modulated lights emitted from the second polarization beam splitter 4 are incident on the third stacked phase difference filter 9. The third stacked phase difference filter 9 rotates the polarization plane of the first modulated light by 90 ° to transmit the first and second modulated lights, and passes through the fourth polarizing beam splitter 10 serving as a polarization combining element. Make it incident. At this time, the polarization planes of the first and second modulated lights are in the same direction. Further, the third modulated light emitted from the third polarizing beam splitter 7 passes through the fourth stacked phase difference filter 11 and enters the fourth polarizing beam splitter 10. The fourth laminated phase difference filter 11 rotates the polarization plane of the third modulated light by 90 ° and transmits it, and makes it incident on the fourth polarization beam splitter 10.

The fourth polarizing beam splitter 10, like the first polarization beam splitter 2, a first triangular prism 10 ₁ polarization separation film 10a is formed on one surface by a deposition, the first triangle from the prism 10 _first polarization separation film 10a and the second triangular prism 10 ₂ Metropolitan bonded through the polarization separation film 10a and adhesive layer 10b with respect to formed surfaces, it is configured in a cubic shape.

  In the fourth polarization beam splitter 10, the first and second modulated lights are P-polarized and the third modulated light is compared with the polarization separation film 10 a inclined at 45 ° with respect to the optical path of the incident light. S-polarized light. The first and second modulated lights pass through the polarization separation film 10a and the adhesive layer 10b, and are emitted from the fourth polarization beam splitter 10. The third modulated light is reflected by the polarization separation film 10 a and is emitted from the fourth polarization beam splitter 10. In this way, the first and second modulated light and the third modulated light are combined.

This for the fourth polarizing beam splitter 10, a third modulated light emitted from the third polarization beam splitter 7 is incident from the first triangular prism 10 ₁ side. Therefore, the third modulated light is reflected by the polarization splitting film 10a without passing through the adhesive layer 10b, and is emitted from the first triangular prism 10 _1.

  FIG. 2 is a plan view showing the optical path of the blue component light B during black display in the color separation / synthesis optical system according to the present invention.

  As shown in FIG. 2, the blue component light B is never transmitted through the adhesive layer of the polarization beam splitter when black display is performed.

  FIG. 3 is a plan view showing the optical path of the blue component light B during white display in the color separation / synthesis optical system according to the present invention.

  The blue component light B is only transmitted through the adhesive layer 7b once in the third polarization beam splitter 7 as shown in FIG.

  The first to third modulated lights emitted from the fourth polarizing beam splitter 10 are incident on the fifth stacked phase difference filter 12 as shown in FIG. The fifth laminated phase difference filter 12 transmits the first to third linearly polarized modulated light as circularly polarized light.

  As the fifth laminated phase difference filter 12, the polarization plane of the third modulated light is rotated by 90 degrees so that the first to third modulated lights are aligned in the same direction and further transmitted through the polarizing plate. You may do it. This polarizing plate removes unnecessary light having a different polarization plane direction.

  Light emitted from the fifth laminated phase difference filter 12 enters a projection optical system 19 that is an imaging optical system. The projection optical system 19 projects the first to third modulated light onto the screen 20 and displays an image.

[Second Embodiment]
FIG. 4 is a plan view showing a second embodiment of the color separation / synthesis optical system according to the present invention.

  In this embodiment, the first to third polarization beam splitters 2, 4 and 7 in the first embodiment are replaced with flat wire grid polarization separation elements. In this embodiment, the blue component light B never passes through the adhesive layer of the polarization beam splitter.

  That is, in this color separation / synthesis optical system, a light beam emitted from a light source (not shown) is substantially a parallel light beam and is also linearly polarized, and as shown in FIG. 1 is incident. Each of the color component lights R, B, and G of the incident light is linearly polarized and has the same plane of polarization. In this embodiment, the polarization plane of each color component light of the incident light is in a direction parallel to the paper surface of FIG.

  In the light beam that has passed through the first laminated phase difference filter 1, the red component light R, the blue component light B, and the green component light G are each linearly polarized light, and the direction of the polarization plane of only the blue component light B is 90 °. It is rotated and the polarization plane of the blue component light B is orthogonal to the polarization planes of the red component light R and the green component light G.

  The light beam that has passed through the first laminated phase difference filter 1 is incident on a first wire grid type polarization separation element 21 that is a first polarization separation element. The first wire grid type polarization separation element 21 is disposed with an inclination of 45 ° with respect to the optical path of the incident light. The red component light R and the green component light G are P polarized light, and the blue component light B is Incident as S-polarized light. Therefore, in the first wire grid type polarization separation element 21, the red component light R and the green component light G are transmitted, the blue component light B is reflected, and the optical paths of the red component light R and the green component light G are The optical path of the blue component light B is branched according to the polarization plane direction.

  The red component light R and the green component light G emitted from the first wire grid type polarization separation element 21 are incident on the second stacked phase difference filter 3. The second laminated phase difference filter 3 rotates the polarization plane of only the red component light R by 90 °, and the red component light R is in a state in which the polarization plane of the red component light R is orthogonal to the polarization plane of the green component light G. The component light R and the green component light G are transmitted.

  The light beam that has passed through the second laminated phase difference filter 3 is incident on a second wire grid type polarization separation element 22 that is a second polarization separation element. The second wire grid type polarization separation element 22 is disposed with an inclination of 45 ° with respect to the optical path of the incident light. The green component light G is S-polarized light and the red component light R is P-polarized light. Incident. The green component light G is reflected by the second wire grid type polarization separation element 22 and is incident on the green reflective spatial light modulation element 6. Further, the red component light R is transmitted through the second wire grid type polarization separation element 22 and is incident on the red reflection type spatial light modulation element 5.

  The green reflective spatial light modulator 6 and the red reflective spatial light modulator 5 respectively reflect incident light with polarization modulation according to the green component and red component of the display image.

  The first modulated light modulated and reflected by the red reflective spatial light modulator 5 is incident again on the second wire grid polarization separation element 22. The second modulated light is S-polarized with respect to the second wire grid type polarization separation element 22 when the red reflective spatial light modulation element 5 displays white. The light is reflected by the wire grid polarization separation element 22 and is emitted from the second wire grid polarization separation element 22 in a direction different from the direction returning to the first wire grid polarization separation element 21.

  The second modulated light modulated and reflected by the green reflective spatial light modulation element 6 is incident on the second wire grid polarization separation element 22 again. Since the first modulated light is P-polarized with respect to the second wire grid type polarization separation element 22 when the green reflective spatial light modulation element 6 is displaying white, the second modulated light is The light is transmitted through the wire grid type polarization separation element 22, and is emitted from the second wire grid type polarization separation element 22 in a direction different from the direction returning to the first wire grid type polarization separation element 21.

  On the other hand, the blue component light B reflected by the first wire grid type polarization separation element 21 is incident on the third wire grid type polarization separation element 23 which becomes the third polarization separation element. The third wire grid type polarization separation element 23 is disposed with an inclination of 45 ° with respect to the optical path of incident light, and the blue component light B is incident as S-polarized light. A blue light transmission filter 7c may be disposed between the first wire grid type polarization separation element 21 and the third wire grid type polarization separation element 23. The blue component light B is reflected by the third wire grid type polarization separation element 23 and enters the blue reflective spatial light modulation element 8. The blue reflective spatial light modulator 8 reflects incident light with polarization modulation according to the blue component of the display image.

  The third modulated light that has been modulated and reflected by the blue reflective spatial light modulator 8 re-enters the third wire grid polarization separation element 23. The third modulated light is P-polarized with respect to the third wire grid type polarization separation element 23 when the blue reflective spatial light modulation element 8 is displaying white. The light is transmitted through the wire grid type polarization separation element 23, and is emitted from the third wire grid type polarization separation element 23 in a direction different from the direction returning to the first wire grid type polarization separation element 21.

  The first and second modulated lights emitted from the second wire grid type polarization separation element 22 are incident on the third laminated phase difference filter 9. The third laminated phase difference filter 9 rotates the polarization plane of the first modulated light by 90 °, transmits the first and second modulated lights, and enters the polarization beam splitter 10. At this time, the polarization planes of the first and second modulated lights are in the same direction. Further, the third modulated light emitted from the third wire grid type polarization separation element 23 passes through the fourth laminated phase difference filter 11 and enters the polarization beam splitter 10. The fourth laminated phase difference filter 11 rotates the polarization plane of the third modulated light by 90 ° and transmits it, and makes it incident on the polarization beam splitter 10.

  In the polarization beam splitter 10, the first and second modulated lights are P-polarized and the third modulated light is S-polarized with respect to the polarization separation film 10 a inclined at 45 ° with respect to the optical path of the incident light. It has become. The first and second modulated lights pass through the polarization separation film 10 a and are emitted from the polarization beam splitter 10. The third modulated light is reflected by the polarization separation film 10 a and emitted from the polarization beam splitter 10. In this way, the first and second modulated light and the third modulated light are combined.

For this polarization beam splitter 10, a third modulated light emitted from the third wire grid type polarization split element 23 is incident from the first triangular prism 10 ₁ side. Therefore, the third modulated light is reflected by the polarization splitting film 10a without passing through the adhesive layer 10b of the polarization beam splitter 10, it is emitted from the first triangular prism 10 _1.

  The first to third modulated lights emitted from the polarization beam splitter 10 are incident on a fifth laminated phase difference filter (not shown). The fifth laminated phase difference filter 12 transmits the first to third linearly polarized modulated light as circularly polarized light.

  As the fifth laminated phase difference filter 12, the polarization plane of the third modulated light is rotated by 90 degrees so that the first to third modulated lights are aligned in the same direction and further transmitted through the polarizing plate. You may do it. This polarizing plate removes unnecessary light whose polarization plane direction is different.

  The outgoing light from the fifth laminated phase difference filter enters a projection optical system (not shown). The projection optical system projects the first to third modulated light onto the screen and displays an image.

[Third Embodiment]
FIG. 5 is a plan view showing a third embodiment of the color separation / synthesis optical system according to the present invention.

  In this embodiment, the first polarizing beam splitter 2 in the first embodiment is replaced with a dichroic wavelength separation film (dichroic filter).

  That is, in this color separation / synthesis optical system, a light beam emitted from a light source (not shown) is substantially a parallel light beam and is also linearly polarized light, and as shown in FIG. 1 is incident. Each of the color component lights R, B, and G of the incident light is linearly polarized and has the same plane of polarization. In this embodiment, the polarization plane of each color component light of the incident light is in a direction parallel to the paper surface of FIG.

  In the light beam that has passed through the first laminated phase difference filter 1, the red component light R, the blue component light B, and the green component light G are each linearly polarized light, and the direction of the polarization plane of only the blue component light B is 90 °. It is rotated and the polarization plane of the blue component light B is orthogonal to the polarization planes of the red component light R and the green component light G.

  The light beam that has passed through the first laminated phase difference filter 1 is incident on the dichroic wavelength separation film 24. The dichroic wavelength separation film 24 is disposed with an inclination of 45 ° with respect to the optical path of the incident light, transmits the red component light R and the green component light G, and reflects the blue component light B. Therefore, in the dichroic wavelength separation film 24, the optical path of the red component light R and the green component light G and the optical path of the blue component light B are branched.

  The red component light R and the green component light G transmitted through the dichroic wavelength separation film 24 are incident on the second stacked phase difference filter 3. The second laminated phase difference filter 3 rotates the polarization plane of only the green component light G by 90 °, and the green component light G is in a state in which the polarization plane of the green component light G is orthogonal to the polarization plane of the red component light R. The component light G and the red component light R are transmitted.

  The light beam that has passed through the second laminated phase difference filter 3 is incident on the second polarization beam splitter 4. In the second polarization beam splitter 4, the red component light R is P-polarized light and the green component light G is S-polarized light with respect to the polarization separation film 4 a inclined at 45 ° with respect to the optical path of the incident light. ing. The red component light R is transmitted through the polarization separation film 4a and the adhesive layer 4b and is emitted from the second polarization beam splitter 4, and is applied to the red reflective spatial light modulator 5 which is the first spatial light modulator. Incident. Further, the green component light G is reflected by the polarization separation film 4a, is emitted from the second polarization beam splitter 4, and enters the green reflective spatial light modulation element 6 which is the second spatial light modulation element.

The second polarizing beam splitter 4, the first triangular prism 4 ₁ polarization splitting film 4a is formed on one surface by a deposition, the first triangular prism 4 _first polarization separation film 4a is formed from the second triangular prism 4 ₂ Metropolitan bonded through the polarization splitting film 4a and the adhesive layer 4b with respect to a plane, and is configured to cubic.

This second relative polarization beam splitter 2, light beam passing through the second stacked retardation filter 3 is incident from the first triangular prism 4 ₁ side. Thus, the green component light G is reflected at the polarization separation film 4a is reflected by the polarization splitting film 4a without passing through the adhesive layer 4b that is joined to the triangular prism, the first triangular prism 4 ₁ Emitted.

  The red reflective spatial light modulator 5 and the green reflective spatial light modulator 6 are so-called reflective liquid crystal display devices, which respectively modulate the polarization of incident light according to the red and green components of the display image. Reflect. Information on the display image is supplied from the outside to the red reflective spatial light modulator 5 and the green reflective spatial light modulator 6.

  The first modulated light modulated and reflected by the red reflective spatial light modulator 5 is incident on the second polarization beam splitter 4 again. The first modulated light is S-polarized with respect to the polarization separation film 4a when the red reflective spatial light modulation element 5 displays white, and is reflected by the polarization separation film 4a. The light is emitted from the second polarizing beam splitter 4 in a direction different from the direction returning to the dichroic wavelength separation film 24.

  The second modulated light modulated and reflected by the green reflective spatial light modulator 6 is incident on the second polarization beam splitter 4 again. Since the second modulated light is P-polarized with respect to the polarization separation film 4a when the green reflective spatial light modulation element 6 is displaying white, the polarization separation film 4a and the adhesive layer 4b. And is emitted from the second polarization beam splitter 4 in a direction different from the direction returning to the dichroic wavelength separation film 24.

  On the other hand, the blue component light B reflected by the dichroic wavelength separation film 24 is incident on the third polarization beam splitter 7. A blue light transmission filter 7 c may be further disposed between the dichroic wavelength separation film 24 and the third polarizing beam splitter 7. In the third polarization beam splitter 7, the blue component light B is S-polarized with respect to the polarization separation film 7 a inclined at 45 ° with respect to the optical path of the incident light. The blue component light B is reflected by the polarization separation film 7a, is emitted from the third polarization beam splitter 7, and is incident on the blue reflective spatial light modulator 8 which is the third spatial light modulator. The blue reflective spatial light modulator 8 is a so-called reflective liquid crystal display device, and reflects incident light by polarization-modulating the incident light according to the blue component of the display image. Information of the display image is supplied to the blue reflective spatial light modulator 8 from the outside.

The third polarization beam splitter 7, like the second polarization beam splitter 4, the first triangular prism 7 ₁ polarization separation film 7a is formed on one surface by a deposition, the first triangle from the prism ₇₁ of the polarization splitting film 7a the polarization separation film with respect to formed surface 7a and the second triangular prism 7 ₂ Metropolitan bonded through an adhesive layer 7b, is configured to cubic. This for the third polarization beam splitter 7, the blue component light B emitted from the dichroic wavelength separating film 24 is incident from the first triangular prism 7 ₁ side. Thus, the blue component light B is reflected by the polarization splitting film 7a without passing through an adhesive layer 7b, it is emitted from the first triangular prism 7 _1.

That is, the blue component light B, is reflected at the dichroic wavelength separating film 24, first being reflected by the third it is against the polarization beam splitter 7 entering from the first triangular prism 7 ₁ polarization splitting film 7a 1 since emitted from the triangular prism ₇₁ and is incident on the blue reflection type spatial light modulator 8, to reach the blue reflection type spatial light modulator 8, it is not transmitted through the even adhesive layer once .

  The third modulated light modulated and reflected by the blue reflective spatial light modulator 8 is incident on the third polarization beam splitter 7 again. Since the third modulated light is P-polarized with respect to the polarization separation film 7a when the blue reflective spatial light modulation element 8 displays white, the polarization separation film 7a and the adhesive layer 7b. And is emitted from the third polarizing beam splitter 7 in a direction different from the direction returning to the dichroic wavelength separation film 24.

  The first and second modulated lights emitted from the second polarization beam splitter 4 are incident on the third stacked phase difference filter 9. The third stacked phase difference filter 9 rotates the polarization plane of the first modulated light by 90 ° to transmit the first and second modulated lights, and passes through the fourth polarizing beam splitter 10 serving as a polarization combining element. Make it incident. At this time, the polarization planes of the first and second modulated lights are in the same direction. Further, the third modulated light emitted from the third polarizing beam splitter 7 passes through the fourth stacked phase difference filter 11 and enters the fourth polarizing beam splitter 10. The fourth laminated phase difference filter 11 rotates the polarization plane of the third modulated light by 90 ° and transmits it, and makes it incident on the fourth polarization beam splitter 10.

The fourth polarizing beam splitter 10, like the second polarization beam splitter 4, the first triangular prism 10 ₁ polarization separation film 10a is formed on one surface by a deposition, the first triangle from the prism 10 _first polarization separation film 10a and the second triangular prism 10 ₂ Metropolitan bonded through the polarization separation film 10a and adhesive layer 10b with respect to formed surfaces, it is configured in a cubic shape.

  In the fourth polarization beam splitter 10, the first and second modulated lights are P-polarized and the third modulated light is compared with the polarization separation film 10 a inclined at 45 ° with respect to the optical path of the incident light. S-polarized light. The first and second modulated lights pass through the polarization separation film 10a and the adhesive layer 10b, and are emitted from the fourth polarization beam splitter 10. The third modulated light is reflected by the polarization separation film 10 a and is emitted from the fourth polarization beam splitter 10. In this way, the first and second modulated light and the third modulated light are combined.

This for the fourth polarizing beam splitter 10, a third modulated light emitted from the third polarization beam splitter 7 is incident from the first triangular prism 10 ₁ side. Therefore, the third modulated light is reflected by the polarization splitting film 10a without passing through the adhesive layer 10b, and is emitted from the first triangular prism 10 _1.

The blue component light B never passes through the adhesive layer of the polarizing beam splitter when displaying black. The blue component light B, even when a white display, only transmits only the adhesive layer ₇₁ once in the third polarization beam splitter 7.

  The first to third modulated lights emitted from the fourth polarizing beam splitter 10 are incident on a fifth laminated phase difference filter (not shown). The fifth stacked phase difference filter rotates the polarization plane of the third modulated light by 90 ° and transmits the first to third modulated lights. The first to third modulated lights that have passed through the fifth laminated phase difference filter have the same plane of polarization. Note that the first to third modulated lights that have passed through the fifth stacked phase difference filter may be further transmitted through the polarizing plate. This polarizing plate removes unnecessary light having a different polarization plane direction.

  The outgoing light from the fifth laminated phase difference filter enters a projection optical system (not shown). The projection optical system projects the first to third modulated light onto the screen and displays an image.

1 is a plan view showing a first embodiment of an image display device according to the present invention using a color separation / synthesis optical system according to the present invention. It is a top view which shows the optical path of the blue component light at the time of the black display in the color separation synthetic | combination optical system which concerns on this invention. It is a top view which shows the optical path of the blue component light B at the time of white display in the color separation / synthesis optical system which concerns on this invention. It is a top view which shows 2nd Embodiment of the color separation / synthesis optical system which concerns on this invention. It is a top view which shows 3rd Embodiment of the color separation / synthesis optical system which concerns on this invention. It is a top view which shows the structure of the conventional color separation synthetic | combination optical system. It is a figure which shows a polarization beam splitter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lamination | stacking phase difference filter 2 1st polarization | polarized-light beam splitter 3 2nd lamination | stacking phase difference filter 4 2nd polarization | polarized-light beam splitter 5 Red reflection type spatial light modulation element 6 Green reflection type spatial light modulation element 7 1st 3 polarizing beam splitter 8 blue reflective spatial light modulator 9 third laminated phase difference filter 10 fourth polarizing beam splitter 11 fourth laminated phase difference filter 12 phase difference filter 13 illumination optical system 19 projection optical system

Claims (2)

First wavelength-selective polarization conversion means for entering a linearly polarized white light beam and setting the polarization planes of the red component light and green component light of the incident beam to be orthogonal to the polarization plane of the blue component light When,
A red light component and a green light component are obtained by transmitting a P-polarized light component and reflecting an S-polarized light component with respect to the polarized light-separating film, and having a polarized light separating film on which the light beam having passed through the first wavelength-selective polarization converting means is incident. A first polarization separation element for branching an optical path between the light and the blue component light;
Red component light and green component light are incident from the first polarization separation element, and the polarization plane of the first color component light and the polarization plane of the second color component light out of the red component light and the green component light. Second wavelength-selective polarization conversion means that are orthogonal to each other;
The first and second color component lights are incident from the second wavelength selective polarization conversion means, the first color component light is incident on the first spatial light modulator, and the second color component light is A second polarization separation element that is incident on the second spatial light modulation element;
A third polarization separation element that receives blue component light from the first polarization separation element and makes the blue component light incident on a third spatial light modulation element;
The modulated light of the red component light and the green component light that has passed through the first and second spatial light modulation elements and the modulated light of the blue component light that has passed through the third spatial light modulation element are incident, A polarization combining element that combines and emits; and
With
At least one of the first and third polarization separation elements includes a first prism on which a polarization separation film is formed, and the polarization separation for the surface of the first prism on which the polarization separation film is formed. A polarization beam splitter composed of a second prism bonded via a film and an adhesive layer, wherein the blue component light directed to the third spatial light modulation element is A color separation / synthesis optical system, wherein the color separation / synthesis optical system is incident from a prism, reflected by the polarization separation film, and emitted from the first prism. A color separation / synthesis optical system according to claim 1;
Light source means for making a light beam that includes at least red component light, green component light, and blue component light in a linearly polarized state incident on the color separation / synthesis optical system;
An imaging optical system that forms an image of a light beam emitted from the polarization combining element of the color separation / synthesis optical system;
An image display device comprising:

Images