JP3904140B2 - Color separation / synthesis optical system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color separation / synthesis optical system including a polarizing beam splitter applied to a reflection type projection display device, and more particularly to improvement of image quality deterioration due to birefringence of the polarizing beam splitter.
[0002]
[Prior art]
The color projection display device decomposes R (red), G (green), and B (blue) color lights related to the three primary colors from white light and leads them to the corresponding spatial light modulation elements. Color light modulated according to the video signal is synthesized and projected to display a color video on the screen.
[0003]
Color projection display devices are roughly classified into three types depending on the type of spatial light modulation element applied thereto. For example, there are a device to which a transmissive spatial light modulator is applied, a device to which a reflective spatial light modulator is applied, and a device to which DMD (Digital Mirror Device) is applied.
[0004]
The transmissive spatial light modulator and the DMD can be reduced in size easily because of the relatively simple optical configuration, but are difficult to achieve high resolution. On the other hand, the reflective spatial light modulator is advantageous for high resolution, but it is difficult to reduce the size because the optical configuration is complicated.
[0005]
In particular, a projection display device to which a reflective spatial light modulation element is applied requires a polarization beam splitter to separate incident light that irradiates the spatial light modulation element and reflected light modulated by the spatial light modulation element. To do. In order to realize high contrast, two or more polarization beam splitters are usually applied to one spatial light modulation element, which complicates the optical configuration of the reflection type projection display device.
[0006]
A color separation / synthesis optical system that solves the problem of the optical configuration of such a reflective spatial light modulator has recently been provided by Colorlink Inc. of the United States. This is also introduced in the literature (Michael G. Robinson et. “High Contrast Color Splitting Architecture Using Color Polarization Filters”, SID 00 DIGEST, 92-95 (2000)).
[0007]
FIG. 28 is a schematic plan view showing an optical configuration of a projection display device to which a reflective spatial light modulation element provided by Color Link is applied.
The color separation / synthesis optical system 290 (the portion surrounded by a broken line in the figure) includes cubic or prismatic first to fourth polarization beam splitters 102, 103, 104, 105 and their polarization separation surfaces 121, 131, 141. , 151 are arranged so as to intersect substantially in an X shape, and further, on the light incident surface side of the first polarizing beam splitter 102 (the left side surface portion of the first polarizing beam splitter 102 in FIG. 28), In addition, the light exit surface side of the fourth polarization beam splitter 105 (the right side surface portion of the fourth polarization beam splitter 105 in FIG. 28) has a function of rotating the polarization plane of the linearly polarized G light by 90 °. First wavelength-selective polarization conversion means (G phase plate) 106, 107, and between the first and third polarization beam splitters 102, 104 and third and fourth polarizations. Between chromatography beam splitter 104, and a second wavelength-selective polarization conversion means (R phase plate for) 108 and 109 having both functions of rotating 90 ° the plane of polarization of the R light of the linearly polarized light.
[0008]
Here, the linearly polarized light includes S-polarized light and P-polarized light whose polarization planes are orthogonal to each other, and the S-polarized light and the P-polarized light are relative relationships between the polarization plane of each polarization and the polarization separation plane of the polarization beam splitter on which the polarization is incident. Determined by. That is, when the polarization plane of each polarization is perpendicular to the plane of incidence with respect to the polarization separation plane of the polarization beam splitter, it is called S polarization, and when it is parallel, it is called P polarization.
[0009]
A phase plate having the characteristics shown in FIG. 29 is applied to the first wavelength selective polarization conversion means (G phase plate) 106 and 107. In FIG. 29, crossed polarizers are spectral characteristics of output light when measured with a polarizer and an analyzer arranged in a cross via a wavelength-selective polarization converting means, and a parallel-polarizer ( Parallel Polaraizers) is a spectral characteristic of output light when a polarizer and an analyzer are arranged in parallel. From the figure, it can be seen that the polarization plane of the G light is rotated by 90 °.
[0010]
The second wavelength selective polarization conversion means (R phase plates) 108 and 109 have the characteristics shown in FIG. In FIG. 30, the cross-polarizer and the parallel-polarizer have the same meaning as described above. From the figure, it can be seen that the polarization plane of the R light is rotated by 90 °.
[0011]
It is also possible to produce wavelength selective polarization conversion means (B phase plate) having a function of rotating only the polarization plane of the B light by 90 °, and the spectral characteristics in this case are as shown in FIG.
These wavelength selective polarization conversion means are described in detail in US Pat. No. 5,751,384.
[0012]
In the color separation / synthesis optical system 290 described above, the first polarization beam splitter 102 serves as a light incident side polarization beam splitter, and the fourth polarization beam splitter 105 located on the opposite side of the first polarization beam splitter 102 serves as a light emission side polarization beam splitter. Become. The second and third polarization beam splitters 103 and 104 arranged at the intermediate position separate incident light that irradiates the reflective spatial light modulator and reflected light modulated by the reflective spatial light modulator. This is a so-called main polarization beam splitter.
[0013]
A reflective spatial light modulator 161 corresponding to G is provided on the light transmitting surface 103c side of the second polarization beam splitter (main polarization beam splitter) 103 of the color separation / synthesis optical system 290, and a third polarization beam splitter (main polarization). The beam splitter) 104 includes an R-compatible reflective spatial light modulator 162 on the translucent surface 104b side, and a B-compatible reflective spatial light modulator 163 on the translucent surface 104a side. A light splitting surface of a light source 171 that emits white light and a first polarizing beam splitter (light incident side polarizing beam splitter) 102 is disposed in front of the light incident side (translucent surface 102a) of the beam splitter (light incident side polarizing beam splitter) 102. 121 includes a first polarizing plate 181 having a transmission axis selected so as to transmit only linearly polarized light having a relationship of S polarization with respect to 121, and The polarization beam splitting surface 151 of the fourth polarization beam splitter (light exit side polarization beam splitter) 105 is located behind the light exit side (transmission surface 105 c) of the fourth polarization beam splitter (light exit side polarization beam splitter) 105. The projection display apparatus 300 includes a second polarizing plate 182 whose transmission axis is selected so as to transmit only linearly polarized light having a P-polarized light relationship, and a projection lens 191 that enlarges and projects color image light. Yes.
[0014]
Note that the polarization separation surfaces 121, 131, 141, 151 of the first to fourth polarization beam splitters 102, 103, 104, 105 are arranged so that their incident surfaces are common surfaces. Since the relative relationship between the polarization plane of the linearly polarized light that determines the P-polarized light and the polarization separation plane is the same for all the polarization beam splitters, the polarization separation plane of any polarization beam splitter is hereinafter referred to as S-polarization or P-polarization. A description of whether or not it is for will be omitted.
[0015]
The projection display device 300 operates as follows.
Indefinitely polarized white light emitted from the light source 171 enters the first polarizing plate 181. Then, only the S-polarized light (in FIG. 28, the center is a black double circle symbol, the same applies hereinafter) passes through the first polarizing plate 181 and enters the first wavelength-selective polarization conversion means 106.
Since the first wavelength-selective polarization conversion means 106 is a G phase plate (see FIG. 29) that rotates the plane of polarization of only G light by 90 °, the first wavelength-selective polarization conversion means 106 transmits the first wavelength-selective polarization conversion means 106. S-polarized light related to light (solid line in FIG. 28) is converted to P-polarized light (both arrows in FIG. 28; the same applies hereinafter). Further, since the first wavelength selective polarization conversion means 106 does not act on the R light (broken line in FIG. 28) and the B light (two-dot chain line in FIG. 28), they remain S polarized light.
Hereinafter, the transition of the optical path and the plane of polarization of each color light will be described individually.
[0016]
First, the P-polarized G light (solid line) that has passed through the first wavelength-selective polarization conversion means 106 passes straight through the polarization separation surfaces 121 and 131 of the first and second polarization beam splitters 102 and 103, and The light is emitted from the light transmitting surface 103 c of the second polarization beam splitter 103 and is incident on the reflective spatial light modulation element 161 corresponding to G. Then, the reflection type spatial light modulation element 161 receives light modulation according to the video signal corresponding to G and reflects the light.
[0017]
The S-polarized component of the G light generated by the light modulation is reflected by the polarization separation surface 131 of the second polarization beam splitter 103 and enters the fourth polarization beam splitter 105. Then, the light is reflected by the polarization separation surface 151 of the fourth polarization beam splitter 105, is emitted from the light transmission surface 105c of the fourth polarization beam splitter 105, and is incident on the second wavelength selective polarization conversion means 107 disposed in the subsequent stage. To do.
Since the second wavelength-selective polarization conversion means 107 has a function of rotating the polarization plane of the G light by 90 ° as described above, the S-polarized light of the G light is converted into P-polarized light and emitted.
[0018]
Next, R light (broken line) will be described. The S-polarized R light transmitted through the first wavelength-selective polarization converter 106 is reflected by the polarization separation surface 121 of the first polarization beam splitter 102 and enters the second wavelength-selective polarization converter 108. Here, since the second wavelength-selective polarization conversion means 108 is an R phase plate that rotates the polarization plane of the R light by 90 °, the R light is converted from S-polarized light to P-polarized light, and is emitted therefrom. The light enters the third polarization beam splitter 104. Further, the P-polarized R light travels straight through the polarization separation surface 141 of the third polarization beam splitter 104, exits from the light transmission surface 104 b, and enters the R-compatible reflective spatial light modulation element 162. Then, the reflection type spatial light modulation element 162 receives the light modulation corresponding to the video signal corresponding to R and is reflected.
[0019]
The S-polarized component of the R light generated by the light modulation is reflected by the polarization separation surface 141 of the third polarization beam splitter 104 and enters the second wavelength-selective polarization conversion means 109. Since the second wavelength-selective polarization conversion means 109 is an R phase plate as described above, the S-polarized component of the R light is converted into P-polarized light and enters the fourth polarizing beam splitter 105. Then, the light travels straight through the polarization separation surface 151 of the fourth polarization beam splitter 105, exits from the light transmission surface 105 c of the fourth polarization beam splitter 105, and is disposed at the subsequent stage. Is incident on.
As described above, since the first wavelength-selective polarization conversion means 107 is a G phase plate, it does not act on the R light at all, and the R light is emitted as P-polarized light.
[0020]
Next, the B light (two-dot chain line) will be described. The S-polarized B light transmitted through the first wavelength selective polarization conversion means 106 is reflected by the polarization separation surface 121 of the first polarization beam splitter 102 and enters the second wavelength selective polarization conversion means 108. Here, since the second wavelength-selective polarization conversion means 108 is an R phase plate as described above, it does not act on the B light at all, and the B light is emitted without being converted to S-polarized light. Then, the light enters the third polarizing beam splitter 104.
[0021]
The S-polarized B light is reflected by the polarization separation surface 141 of the third polarization beam splitter 104, exits from the light transmitting surface 104a, and enters the B-type reflective spatial light modulator 163. Then, the reflection type spatial light modulation element 163 receives light modulation according to the video signal corresponding to B and is reflected.
[0022]
The P-polarized component of the B light generated by the light modulation is transmitted through the polarization separation surface 141 of the third polarization beam splitter 104 and enters the second wavelength selective polarization conversion means 109. Since the second wavelength-selective polarization conversion means 109 is an R phase plate as described above, it does not act on B light. The light enters the beam splitter 105. Then, the light travels straight through the polarization separation surface 151 of the fourth polarization beam splitter 105, exits from the light transmission surface 105 c of the fourth polarization beam splitter 105, and is disposed at the subsequent stage. Is incident on.
As described above, the first wavelength-selective polarization conversion means 107 is a G phase plate, so it does not act on the B light, and the B light is emitted as P-polarized light.
In this way, the polarization planes of the R light, G light, and B light are aligned with P polarized light, and a color image is enlarged and displayed on a screen (not shown) via the projection lens 191.
[0023]
As described above, according to the projection display device 300, while three polarization beam splitters are applied to one reflective spatial light modulator, a relatively simple optical configuration can be achieved. A contrast projection display device can be realized.
[0024]
[Problems to be solved by the invention]
However, in the above-described projection display device, when a high-intensity discharge lamp of 100 W or more is applied as a light source, if the light-transmitting member of the polarizing beam splitter is selected incorrectly, it is affected by the birefringence of the light-transmitting member. There has been a problem that the contrast at the corners of the black display screen is lowered (black floating) and the display quality is deteriorated.
[0025]
For such a problem, the absolute value of the photoelastic constant is 1.5 × 10 5 as a translucent member of the polarizing beam splitter.^-8cm²Japanese Patent Application Laid-Open No. 9-54213 discloses that it is effective to apply a translucent material having a / N or less.
According to the disclosure of Japanese Patent Laid-Open No. 9-54213, a so-called main polarization beam splitter that separates at least incident light that irradiates a reflective spatial light modulation element and modulated reflected light from the spatial light modulation element. Is disclosed that it is effective to apply the translucent material having the low photoelastic constant as the translucent member.
[0026]
However, according to a study by the present inventors, in the projection display device 300 using the color separation / synthesis optical system 290 described above, the main polarization beam splitter (second and third polarization beam splitters 103 and 104). It has been found that the problem of birefringence cannot be solved even by applying a light-transmitting material having a low photoelastic constant as described above.
[0027]
Of course, it can be easily expected that all of the four polarizing beam splitters are effective if the above-described light-transmitting material having a low photoelastic constant is applied. In this case, however, the color separation / synthesis optical system is expensive. There is a problem.
That is, in general, a translucent material having a low photoelastic constant is an optical glass substrate containing a large amount of lead, and is fragile and soft and difficult to process. Therefore, it is less expensive than BK7, which is a general optical glass. Is several to several tens of times as expensive.
[0028]
Further, the color separation / synthesis optical system 290 provided by Color Link Co., Ltd. is formed by bonding all the constituent elements with an adhesive. Therefore, there was a problem in reliability because the joint part peeled off in the reliability test of the thermal cycle.
[0029]
This is because the four polarization beam splitters are arranged so that their polarization separation surfaces intersect in an X shape, which can cause the thermal expansion or contraction of each optical element during temperature rise or cooling in the reliability test. Accompanying stress is generated in the circumferential direction around the intersection, and as a result, outward shear stress during temperature rise and tensile stress during cooling act on the joint, resulting in the above-mentioned problem of delamination. Can be inferred.
[0030]
The present invention has been made in order to solve the problem, and provides an inexpensive and highly reliable color separation / synthesis optical system suitable for a reflective projection display device by suppressing the birefringence of the polarization beam splitter. For the purpose.
[0031]
[Means for Solving the Problems]
  According to a first aspect of the present invention, there is provided a cubic or prismatic first to fourth polarizing beam splitter arranged so that a polarization separation surface formed in a diagonal direction is X-shaped, and the first When the polarizing beam splitter and the fourth polarizing beam splitter are diagonally arranged, the first polarizing beam splitter is arranged on the light incident side, and the fourth polarizing beam splitter is arranged on the light emitting side, the first polarizing beam splitter is arranged on the light emitting side.ofOf the light incident side of the polarizing beam splitter, the light emitting side of the fourth polarizing beam splitter, and the inner facing surfaces orthogonal to each other of the first to fourth polarizing beam splitters, two or more of the inner facing surfaces Wavelength selective conversion means for rotating the plane of polarization of the predetermined color light disposed between them by 90 °, and the first to the fourthofAn optical member integrally formed by joining any three of the polarizing beam splitters and the wavelength selective conversion means, and the remaining one polarizing beam splitterWhenGap betweenButEstablishmentAnd the gap is filled with a transparent cushioning member.A color separation / synthesis optical system is provided.
  According to a second aspect of the present invention, there are provided a cubic or prismatic first to fourth polarizing beam splitters arranged so that a polarization separation surface formed in a diagonal direction has an X shape, and the first polarizing beam splitter. And the fourth polarizing beam splitter are diagonally arranged, the first polarizing beam splitter is disposed on the light incident side, and the fourth polarizing beam splitter is disposed on the light emitting side.ofOf the light incident side of the polarizing beam splitter, the light emitting side of the fourth polarizing beam splitter, and the inner facing surfaces orthogonal to each other of the first to fourth polarizing beam splitters, two or more of the inner facing surfaces Wavelength selective conversion means for rotating the plane of polarization of the predetermined color light disposed between them by 90 °, and the first to fourthofAmong the polarizing beam splitters, any two polarizing beam splitters adjacent to each other and the wavelength selective conversion means disposed between the two polarizing beam splitters are joined and integrated, and the remaining two polarized light beams Beam splitterWhenGap betweenButEstablishmentAnd the gap is filled with a transparent cushioning member.A color separation / synthesis optical system is provided.
  The third invention isWhen the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko,
Ki <Ko and Km
Have a relationshipA color separation / synthesis optical system according to claim 1 or 2 is provided.
  In a fourth aspect of the invention, the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko. When
Ki and Km <Ko
The relationship is as follows:Or 2The described color separation / synthesis optical system is provided.
  In a fifth aspect of the invention, the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko. When
Ki <Km <Ko
The relationship is as follows:Or 2The described color separation / synthesis optical system is provided.
  The sixth invention is:Cubic or prismatic first to fourth polarizing beam splitters arranged so that the polarization splitting surfaces formed in a diagonal direction are X-shaped, the first polarizing beam splitter, and the fourth polarized light When the beam splitter is diagonal and the first polarizing beam splitter is disposed on the light incident side, and the fourth polarizing beam splitter is disposed on the light emitting side, the light incident side of the first polarizing beam splitter, Of a predetermined color light disposed between two or more inner facing surfaces among the light emitting side of the fourth polarizing beam splitter and the inner facing surfaces orthogonal to each other of the first to fourth polarizing beam splitters. A wavelength selective conversion means for rotating the plane of polarization by 90 °, the photoelastic constant of the first polarization beam splitter being Ki, and the second to third polarization beam splitters. Of the photoelastic constant Km, the fourth a polarizing When the photoelastic constant of the beam splitter is Ko,
Ki <Ko and Km
Or Ki and Km <Ko
Or Ki <Km <Ko
A color separation / synthesis optical system characterized by having any one of the following relationships is provided.
  The seventh inventionThe first to fourth polarizing beam splitters and the wavelength selective conversion means are joined to each other.It is characterized byClaim 6A color separation / synthesis optical system is provided.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic plan view for explaining a first embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a color separation / synthesis optical system according to the first embodiment of the present invention, which has the following configuration.
That is, the cubic or prismatic first to fourth polarizing beam splitters 2, 3, 4, and 5 are arranged so that the polarization separation surfaces 21, 31, 41, and 51 of the polarizing beam splitters intersect in a substantially X shape. Is arranged. In this case, the first polarizing beam splitter 2 is a light incident side polarizing beam splitter, and the fourth polarizing beam splitter 5 arranged at a diagonal position thereof is a light emitting side polarizing beam splitter.
It is up to you to select the light incident side polarizing beam splitter, but in either case, the polarizing beam splitter located at the diagonal of the light incident side polarizing beam splitter must be the same as the light emitting side polarizing beam splitter. Is done.
[0033]
In front of one of the four light transmitting surfaces 2a, 2b, 2c, and 2d of the first polarizing beam splitter 2 (light incident side polarizing beam splitter), and the fourth The linearly polarized light G is located behind one light transmitting surface 5c (light emitting side surface) selected from the four light transmitting surfaces 5a, 5b, 5c and 5d of the polarizing beam splitter 5 (light emitting side polarizing beam splitter). First wavelength selective polarization conversion means (hereinafter referred to as G phase plates) 6 and 7 for rotating the polarization plane of light by 90 ° are arranged.
[0034]
Further, between the first polarizing beam splitter 2 and the third polarizing beam splitter 4 and between the third polarizing beam splitter 4 and the fourth polarizing beam splitter 5, both of the linearly polarized R light Second wavelength selective polarization conversion means (hereinafter referred to as R phase plates) 8 and 9 for rotating the polarization plane by 90 ° are provided.
[0035]
Further, the color separation / synthesis optical system 1 includes the second to fourth polarization beam splitters 3, 4 and 5, the G phase plate 7 and the R phase, excluding the G phase plate 6 and the first polarization beam splitter 2. The plates 8 and 9 are integrally joined by a joining member 10 such as a transparent adhesive to form a joined optical member 11. The G phase plate 6 and the first polarizing beam splitter 2 may be joined or separated to form a gap (separated in FIG. 1). Alternatively, the R phase plate 8 may be joined to the first polarizing beam splitter 2 and separated between the R phase plate 8 and the third polarizing beam splitter 4 to form a gap.
[0036]
In the color separation / synthesis optical system 1 according to the first embodiment of the present invention, the spatial light modulation element 61 corresponding to G light is disposed on the side surface of the light transmitting surface 3c of the second polarization beam splitter 3 and is compatible with R light. The spatial light modulation element 62 is disposed on the side of the light transmission surface 4 b of the third polarization beam splitter 4, and the spatial light modulation element 63 for B light is disposed on the side surface of the light transmission surface 4 a of the third polarization beam splitter 4. Will be.
[0037]
The color separation photosynthesis system 1 according to the first embodiment of the present invention functions to color-separate R, G, and B light from white light and further synthesize them as follows.
First, S-polarized light of white light is given to the G phase plate 6. In this case, since the G phase plate 6 has a function of rotating the plane of polarization of only the G light by 90 ° (see FIG. 29), the G light (see FIG. 1) among the white light transmitted through the G phase plate 6. Only the solid line) is polarized and changed from S-polarized light to P-polarized light. On the other hand, R light (broken line in FIG. 1) and B light (two-dot chain line in FIG. 1) remain S-polarized light.
Hereinafter, the transition of the optical path and the plane of polarization of each color light will be described individually.
[0038]
First, the G light transmitted through the G phase plate 6 will be described.
G light (solid line) is converted to P-polarized light as described above. The G light travels straight through the polarization separation surfaces 21 and 31 of the first and second polarization beam splitters 2 and 3, and is emitted from the light transmission surface 3 c of the second polarization beam splitter 3 to be reflected by G. The light enters the spatial light modulator 61. Then, the reflection type spatial light modulation element 61 receives light modulation according to the video signal corresponding to G and reflects the light.
[0039]
The S-polarized component of the G light generated by the light modulation here is reflected by the polarization separation surface 31 of the second polarization beam splitter 3 and enters the fourth polarization beam splitter 5. Then, the light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5, is emitted from the light transmission surface 5 c of the fourth polarization beam splitter 5, and is incident on the G phase plate 7 disposed in the subsequent stage.
Since the G phase plate 7 has a function of rotating the polarization plane of the G light by 90 ° as described above, the S polarized light of the G light is converted into P polarized light and emitted.
[0040]
Next, R light (broken line) will be described.
The S-polarized R light transmitted through the G phase plate 6 is reflected by the polarization separation surface 21 of the first polarization beam splitter 2 and enters the R phase plate 8. Here, since the R phase plate 8 has a function of rotating the polarization plane of the R light by 90 ° (see FIG. 30), the R light is polarized from S-polarized light to P-polarized light and emitted therefrom. The light enters the third polarizing beam splitter 4. Further, the P-polarized R light travels straight through the polarization separation surface 41 of the third polarization beam splitter 4, exits from the light transmission surface 4 b, and enters the R-compatible reflective spatial light modulator 62. Then, the reflection type spatial light modulator 62 receives light modulation corresponding to the R-compatible video signal and reflects the light.
[0041]
The S-polarized component of the R light generated by light modulation here is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and enters the R phase plate 9. Since the R phase plate 9 has a function of converting the polarization plane of the R light as described above, the S-polarized component of the R light is converted to P-polarized light and enters the fourth polarizing beam splitter 5. To do. Then, the light travels straight through the polarization separation surface 51 of the fourth polarization beam splitter 5, exits from the light transmission surface 5 c of the fourth polarization beam splitter 5, and enters the G phase plate 7 disposed in the subsequent stage.
As described above, the G phase plate 7 does not act on the R light, and the R light is emitted as P-polarized light.
[0042]
Next, the B light (two-dot chain line) will be described. The S-polarized B light transmitted through the G phase plate 6 is reflected by the polarization separation surface 21 of the first polarization beam splitter 2 and enters the R phase plate 8. Here, the R phase plate 8 does not act on the B light at all as described above, and the B light is output as S-polarized light without being subjected to polarization conversion, and enters the third polarizing beam splitter 4. .
[0043]
The S-polarized B light is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, exits from the light transmitting surface 4 a, and enters the B-type reflective spatial light modulator 63. Then, the reflection type spatial light modulation element 63 receives the light modulation corresponding to the video signal corresponding to B and is reflected.
[0044]
The P-polarized component of the B light generated by the light modulation travels straight through the polarization separation surface 41 of the third polarization beam splitter 4 and enters the R phase plate 9. The R phase plate 9 does not act on the B light as described above, and the B light exits from the P-polarized light and enters the fourth polarizing beam splitter 5. Then, the light travels straight through the polarization separation surface 51 of the fourth polarization beam splitter 5, exits from the light transmission surface 5 c of the fourth polarization beam splitter 5, and enters the G phase plate 9 disposed in the subsequent stage.
As described above, the G phase plate 9 does not act on the B light, and the B light is emitted as P-polarized light.
In this way, the white light is color-separated in the color separation / combination optical system 1 and then recombined, and the polarization planes of the R, G, and B lights are all aligned with the P-polarized light and emitted from the color separation / synthesis optical system 1. .
[0045]
However, as described above, when the color separation / combination optical system 1 is composed of a general light-transmitting member such as BK7, the black floating phenomenon due to the birefringence of the light-transmitting member (in the black display, the luminance is slightly higher than the peripheral portion). The phenomenon of generating a part that generates image) occurs, and there is a problem of degrading video quality.
Birefringence is generated by thermal stress generated by light transmitted through the light-transmitting member or external mechanical stress. For example, in a square-shaped translucent member, when the temperature difference between the central part and corner part through which the light beam passes becomes large, thermal stress concentrates on the corner part and birefringence occurs at that part. There is. When linearly polarized light is transmitted through a site where such birefringence occurs, the polarization plane is rotated, and the influence appears on the projected image.
[0046]
This phenomenon will be described in more detail with reference to FIG.
FIG. 2 simply shows a projection apparatus constituted by one polarization beam splitter 22, one reflection type spatial light modulation element 24, and a projection lens 25.
[0047]
By the way, the effect of birefringence is most problematic on a projected image is a black floating phenomenon in black display. Black display means a state in which light incident on the spatial light modulator 24 is not modulated at all and returns to the original optical path. That is, in FIG. 2, when S-polarized light (solid line in FIG. 2) enters the polarizing beam splitter 22, the S-polarized light is reflected by the polarization separation surface 23 of the polarizing beam splitter 22 and enters the reflective spatial light modulator 24. To do. As described above, in the case of black display, the incident light is not modulated at all in the reflective spatial light modulator 24, so that the reflected light remains S-polarized light. Therefore, the S-polarized light reflected by the reflective spatial light modulator 24 is reflected again by the polarization separation surface 23 and returns to the same optical path as that at the time of incidence. Therefore, the image projected and displayed by the projection lens 25 is black.
[0048]
However, when birefringence occurs in the translucent member of the polarizing beam splitter 22 (part shown by hatching in FIG. 2), when S-polarized light passes through this part, the plane of polarization is rotated, and the component of P-polarized light (Broken line in FIG. 2) is generated. Therefore, the P-polarized light component is transmitted through the polarization separation surface 23 and causes a bright portion on a screen (not shown) through the projection lens 25. For this reason, the corners of the display screen are slightly brightened while displaying black. This is the black floating phenomenon that is affected by birefringence.
[0049]
FIG. 3 is a diagram conceptually showing a black display screen. 3A shows a normal black screen, and FIG. 3B shows a black screen when birefringence occurs. Black floating occurs at the corners of the screen due to the effect of birefringence.
[0050]
One of the causes of birefringence is due to thermal stress as described above. Therefore, the inventors measured the surface temperatures of the first to fourth polarizing beam splitters 2, 3, 4, and 5 in the color separation / synthesis optical system 1 of the first embodiment. FIG. 4 is a diagram showing the measurement results. The light source used at this time was a 150 W ultrahigh pressure mercury lamp. The temperature was measured at room temperature by measuring the surface temperature of each polarizing beam splitter one hour after turning on the light source.
[0051]
As a result, the surface temperature of the first polarizing beam splitter (light incident side polarizing beam splitter) 2 was the highest, and in particular, the triangular prism 2A had the highest temperature of 39 ° C.
The second highest temperature was displayed at 37.3 ° C. of the triangular prism 4A of the third polarizing beam splitter 4. Conversely, the lowest temperature was displayed by the fourth polarizing beam splitter 5 at 29 ° C. to 30 ° C.
Note that the temperature difference in FIG. 4 tends to further increase if a light source with higher brightness is applied.
[0052]
The reason why the temperature of the prism 2A of the first polarizing beam splitter 2 becomes the highest is considered to be that the incident light and the return light of R, G, B light pass through the prism 2A. Also, the reason why the prism 4A of the third polarizing beam splitter 4 is the second highest is considered to be because two colors of incident light and return light of R and B light pass through. On the other hand, the reason why the surface temperature of the fourth polarizing beam splitter 5 is lowest is that substantially no light passes through the fourth polarizing beam splitter 5 during black display.
[0053]
Thus, the temperature of the first polarizing beam splitter 2 was higher than that of any other polarizing beam splitter. In such a situation, in the color separation / synthesis optical system in which all the optical elements as shown in the related art are integrally joined, the temperature difference of each optical element causes a difference in thermal expansion of each optical element, As a result, it is considered that stress is generated for each optical element to generate birefringence. In particular, it is considered that the above problem appears remarkably in the first polarizing beam splitter 2 having the largest temperature rise during use.
[0054]
However, the color separation / synthesis optical system 1 according to the first embodiment of the present invention has an effect of suppressing the occurrence of birefringence. This is because the first polarizing beam splitter 2 is separated from the second to fourth polarizing beam splitters 3, 4, and 5 of the joined optical member 11, the G phase plate 7, and the R phase plates 8 and 9. It can be inferred that it is not affected by stress due to a temperature difference from other optical elements.
[0055]
  In addition, according to the color separation / synthesis optical system 1 according to the first embodiment of the present invention, the problem that the joint portion of each optical member peels in the reliability test of the thermal cycle did not occur. This is separate and independent from the optical member 11 to which the first polarizing beam splitter 2 is joined. Therefore, the first to fourth polarizing beam splitters 2, 3, 4 at the time of temperature rise or cooling in the reliability test. The stress generated in the circumferential direction around the intersection of the five polarization separation surfaces 21, 31, 41, 51 is released at the position of the first polarization beam splitter 2.ThisTherefore, it can be inferred that the occurrence of outward shear stress or tensile stress is eliminated in the joint as in the prior art.
[0056]
(Second Embodiment)
Next, a second embodiment of the present invention will be described.
FIG. 5 is a schematic plan view of a color separation / synthesis optical system according to the second embodiment of the present invention. Here, only different parts from the first embodiment of the present invention will be described.
In FIG. 5, reference numeral 50 denotes a color separation / synthesis optical system according to the second embodiment of the present invention. The configuration is similar to that of the first embodiment of the present invention shown in FIG. 1 except that a G phase plate 6 and a first polarization beam splitter (light incidence side polarization beam splitter) 2 arranged on the light incident side are connected to other components. Separated from the joined optical member 11 (second to fourth polarizing beam splitters 3, 4, 5 and joined body of G phase plate 7 and R phase plates 8, 9 arranged on the light emitting side) 11, It is affixed to the joined optical member 11 with a buffer member 12 such as a transparent adhesive or coupling oil. Note that the first polarizing beam splitter 2 and the G phase plate 6, and the third polarizing beam splitter 4 and the R phase plate 8 may be joined by the joining member 10 or a buffer member 12 such as an adhesive material. May be attached or separated and provided with a gap.
Since the operation of the second embodiment of the present invention is the same as that of the first embodiment of the present invention, description thereof is omitted.
[0057]
According to the second embodiment of the present invention, as in the first embodiment of the present invention, the first polarization beam splitter (light incident side polarization beam splitter) 2 has a degree of freedom with respect to the joined optical member 11. Therefore, even when the temperature of the first polarizing beam splitter 2 becomes higher than the temperature of the bonded optical member 11 due to the passage of light, the first polarizing beam splitter 2 is not in contact with the bonded optical member 11. There is an effect that the thermal stress due to the temperature difference is hardly generated in the first polarizing beam splitter 2 and the problem of birefringence is difficult to be generated. In addition, since the stress due to thermal expansion or contraction of each optical element is released at the site of the first polarizing beam splitter 2 for the reliability test of the thermal cycle, the problem of peeling at the joint portion is solved. The
[0058]
(Third embodiment)
Next, a third embodiment of the present invention will be described.
FIG. 6 is a schematic plan view of a color separation / synthesis optical system according to the third embodiment of the present invention.
In FIG. 6, reference numeral 60 denotes a color separation / synthesis optical system according to the third embodiment of the present invention. The second and fourth polarization beam splitters 3 and 5, the G phase plate 7 and the R phase plate on the emission side 9 and 9 are joined together by a joining member 10, and the first and third polarizing beam splitters 2 and 4 are provided separately through a gap. The first polarizing beam splitter 2 and the G phase plate 6, and the third polarizing beam splitter 4 and the R phase plate 8 may be joined by the joining member 10 or a buffer member such as a transparent adhesive material. Even if it is affixed by etc., it does not matter even if it has isolate | separated and provided the space | gap.
Since the operation of the third embodiment of the present invention is the same as that of the first embodiment of the present invention, description thereof is omitted.
[0059]
According to the third embodiment of the present invention, since the first and third polarization beam splitters 2 and 4 that are likely to become high temperature due to the passage of light are provided separately through the air gap, the heat related to birefringence is provided. Since the stress is generated only by the internal temperature difference between the first and third polarizing beam splitters 2 and 4 itself, the occurrence of birefringence is suppressed. In addition, since both ends of the optical member bonded to the reliability test of the thermal cycle are opened, the stress due to thermal expansion is released and the problem of peeling is solved.
[0060]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.
FIG. 7 is a schematic plan view of a color separation / synthesis optical system according to the fourth embodiment of the present invention.
In FIG. 7, reference numeral 70 denotes a color separation / synthesis optical system according to the fourth embodiment of the present invention. The third and fourth polarizing beam splitters 4 and 5, the G phase plate 7 on the output side, and the R phase. The plates 8 and 9 are joined by the joining member 10, and the first and second polarizing beam splitters 2 and 3 are both provided separately through a gap. The first polarizing beam splitter 2 and the G phase plate 6 may be joined by the joining member 10 or pasted by a buffer member such as a transparent adhesive material, or may be separated and provided with a gap. It doesn't matter.
Since the operation of the fourth embodiment of the present invention is the same as that of the first embodiment of the present invention, the description thereof is omitted.
[0061]
According to the fourth embodiment of the present invention, since the first polarization beam splitter 2 that is likely to become a high temperature when passing light is separated and provided independently through the air gap, the thermal stress related to birefringence is the first stress. The generation of the birefringence is suppressed because it is generated only by the internal temperature difference of the polarization beam splitter 2 itself. In addition, since both ends of the optical member bonded to the reliability test of the thermal cycle are opened, the stress due to thermal expansion is released and the problem of peeling is solved.
[0062]
Next, a fifth embodiment of the present invention will be described.
FIG. 8 is a schematic plan view of a color separation / synthesis optical system according to the fifth embodiment of the present invention. In FIG. 8, reference numeral 80 denotes a color separation / synthesis optical system according to the fifth embodiment of the present invention, which includes first to fourth polarization beam splitters 2, 3, 4, 5, G phase plates 6, 7 and an R phase. Each of the plates 8 and 9 is joined by the joining member 10, and a slit (gap) 13 is provided between the first polarizing beam splitter 2 and the R phase plate 8. Note that the G phase plate 6 and the first polarizing beam splitter 2 may be separated or affixed using a transparent buffer member. The slit 13 may be filled with a transparent buffer member.
Since the operation of the fifth embodiment of the present invention is the same as that of the first embodiment of the present invention, description thereof is omitted.
[0063]
  According to the fifth embodiment of the present invention, the slit 13 is provided between the first and third polarizing beam splitters 2 and 4 that are likely to become high temperature due to the passage of light. Since the stress based on it is released in the slit 13, there is an effect of suppressing the occurrence of birefringence.
  In addition, stress generated in the circumferential direction centering on the intersection of the polarization separation surfaces 21, 31, 41, 51 of the first to fourth polarization beam splitters 2, 3, 4, 5 due to thermal expansion or contraction is generated. , Open at the slit 13 described aboveThisTherefore, the problem of peeling of the joint portion is also solved.
[0064]
Next, a sixth embodiment of the present invention will be described.
FIG. 9 is a schematic plan view of a color separation / synthesis optical system according to the sixth embodiment of the present invention. In FIG. 9, reference numeral 90 denotes a color separation / synthesis optical system according to the sixth embodiment of the present invention, which has a configuration similar to that of the fifth embodiment of FIG. 8, but the first polarization beam splitter 2 and the second polarization beam. The difference is that a slit (gap) 13 is provided between the splitter 3 and the splitter 3. The slit 13 may be filled with a transparent buffer member.
Since the operation of the sixth embodiment of the present invention is the same as that of the first embodiment of the present invention, description thereof will be omitted.
[0065]
  The sixth embodiment of the present invention is similar to the fifth embodiment of the present invention in that the first polarizing beam splitter 2 adjacent to the first polarizing beam splitter 2 that tends to become high temperature due to the passage of light.2Polarization beam splitter3Since the slit 13 is provided between and the stress due to the difference in thermal expansion of each optical element is released in the slit 13, there is an effect of suppressing the occurrence of birefringence.
  In addition, stress generated in the circumferential direction centering on the intersection of the polarization separation surfaces 21, 31, 41, 51 of the first to fourth polarization beam splitters 2, 3, 4, 5 due to thermal expansion or contraction is generated. , Open at the slit 13 described aboveThisTherefore, the problem of peeling of the joint portion is also solved.
[0066]
(Examination of photoelastic constant of translucent member constituting polarizing beam splitter)
As described above, it is known that the birefringence generated in the polarizing beam splitter is affected by the photoelastic constant of the translucent member constituting the birefringence. It is also known that a glass substrate which is an optical member having a small photoelastic constant is expensive. Therefore, in constructing the color separation / synthesis optical system 1, it is necessary to consider both the projection quality and the economical efficiency. Therefore, the birefringence problem of the color separation / synthesis optical system 1 was studied by examining the photoelastic constant of the glass substrate which is a light transmitting member of the polarizing beam splitter.
[0067]
FIG. 10 is a schematic plan view of the color separation / synthesis optical system used in the birefringence experiment. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.
In FIG. 10, reference numeral 100 denotes a color separation / synthesis optical system, and all optical elements of the first to fourth polarization beam splitters 2, 3, 4, 5, the G phase plates 6, 7 and the R phase plates 8, 9. Are joined together by a joining member 10 such as a transparent adhesive.
[0068]
FIG. 11 shows the experimental results of examining the influence of birefringence in black display. FIG. 11 shows the first to fourth polarizing beam splitters 2, 3, 4, and 5 manufactured using glass substrates having different photoelastic constants, and the influence of birefringence in each combination is evaluated.
In addition, the symbol of an evaluation result describes the determination result based on the evaluation criteria of FIG. In other words, x indicates the level of birefringence that clearly appears and cannot be practically used, Δ indicates a level applicable to an inexpensive projection display device, and ○ indicates the effect of birefringence if observed carefully. Levels and ◎ indicate levels at which the influence of birefringence is not confirmed. FIG. 12 illustrates a birefringence evaluation model. However, the evaluation model is not limited to this. In addition, the occurrence of birefringence varies depending on the evaluation environment.
[0069]
Evaluation of birefringence is based on a comparatively low brightness 100 W UHP lamp (trade name, ultra-high pressure mercury lamp manufactured by Philips), a medium brightness 150 W UHP lamp, and a high brightness 200 W UHL lamp ( (Trade name, ultra high pressure mercury lamp manufactured by Ushio Inc.).
[0070]
First, the influence of birefringence on a 100 W light source will be described.
In Experimental Example 1, the photoelastic constant of each of the first to fourth polarizing beam splitters 2, 3, 4, and 5 is 2.77 × 10.^-8cm²/ N BK7 (manufactured by SCHOTT) is used. In this case, although the influence of birefringence is clearly confirmed, it was a level (Δ) applicable to an inexpensive projection display device that does not place much importance on display quality.
[0071]
In Experimental Example 2, only the first polarizing beam splitter (light incident side polarizing beam splitter) 2 has a photoelastic constant of 1.8 × 10.^-8cm²/ N SF1 (manufactured by SCHOTT), others have a photoelastic constant of 2.77 × 10^-8cm²/ N BK7 is applied. In this case, it was a level (◯) at which the influence of birefringence was confirmed at the corner if observed carefully.
[0072]
In Experimental Example 3, the photoelastic constant of the first polarizing beam splitter (light incident side polarizing beam splitter) 2 is smaller than that in Experimental Example 2, 1.36 × 10^-8cm²/ N SF4 (manufactured by SCHOTT) glass substrate is applied. In this case, it was a level (（) that no influence of birefringence was confirmed on the display screen.
[0073]
Next, the influence of birefringence on a 150 W light source will be described.
Experimental Example 4 uses the same color separation / synthesis optical system as Experimental Example 1, and all the polarization beam splitters have a photoelastic constant of 2.77 × 10.^-8cm²/ N BK7. In this case, the influence of birefringence clearly appeared and it was a level (x) that could not be used.
[0074]
In Experimental Example 5, the first, second, and third polarizing beam splitters 2, 3, and 4 have a photoelastic constant of 1.8 × 10.^-8cm²/ N SF1 is applied, and the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5 has a photoelastic constant of 2.77 × 10 6.^-8cm²/ N BK7 is applied. In this case, although the influence of birefringence can be clearly confirmed, it was a level (Δ) applicable to an inexpensive projection apparatus.
[0075]
In Example 6, the first, second, and third polarizing beam splitters 2, 3, and 4 have a smaller photoelastic constant of 1.36 × 10 6.^-8cm²/ N SF4 is applied, and the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5 has a photoelastic constant of 2.77 × 10 6.^-8cm²/ N BK7 is applied. In this case, it was at a level (◯) where the influence of birefringence could be confirmed at the corner if observed carefully.
[0076]
Experimental Example 7 has a photoelastic constant of 1.36 × 10 for the first polarizing beam splitter (light incident side polarizing beam splitter).^-8cm²/ N SF4 has a photoelastic constant of 1.8 × 10 2 for the second and third polarizing beam splitters (main polarizing beam splitters) 3 and 4.^-8cm²/ N SF1 with respect to the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5 has a photoelastic constant of 2.77 × 10 6.^-8cm²/ N BK7 is applied. In this case, it was a level (◯) at which the influence of birefringence could be confirmed at the corners when observed carefully.
[0077]
In Experimental Example 8, only the first polarizing beam splitter (light incident side polarizing beam splitter) 2 is 0.65 × 10 6 having a smaller photoelastic constant.^-8cm²/ N PBH6W (manufactured by Ohara), others have a photoelastic constant of 2.62 × 10^-8cm²/ N SF2 is applied. In this case, it was a level (◯) at which the influence of birefringence could be confirmed at the corners when observed carefully.
[0078]
In Experimental Example 9, the photoelastic constant of the first polarizing beam splitter (light incident side polarizing beam splitter) 2 is 0.65 × 10 6.^-8cm²/ N PBH6W has a photoelastic constant of 1.8 × 10 2 for the second and third polarizing beam splitters (main polarizing beam splitters) 3 and 4^-8cm²/ N SF1 with a photoelastic constant of 2.62 × 10 4 for the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5^-8cm²/ N SF2 is applied. In this case, it was at a level (レ ベ ル) that no influence of birefringence was confirmed on the display screen.
[0079]
Next, the influence of birefringence on a 200 W light source will be described.
Experimental Example 10 has a photoelastic constant of 1.8 × 10 for all of the first, second, third, and fourth polarizing beam splitters 2, 3, 4, and 5.^-8cm²/ N SF1 is applied.
In this case, the influence of birefringence clearly appeared and it was a level (x) that could not be used.
[0080]
In Experimental Example 11, only the first polarizing beam splitter (light incident side polarizing beam splitter) 2 has a photoelastic constant of 0.65 × 10 6.^-8cm²/ N PBH6W, others have a photoelastic constant of 2.62 × 10^-8cm²/ N SF2 is applied. In this case, although the influence of birefringence can be clearly confirmed, it was a level (Δ) applicable to an inexpensive projection apparatus.
[0081]
In Experimental Example 12, the photoelastic constant of the first polarizing beam splitter (light incident side polarizing beam splitter) 2 is 0.65 × 10 6.^-8cm²/ N PBH6W has a photoelastic constant of 1.8 × 10 2 for the second and third polarizing beam splitters (main polarizing beam splitters) 3 and 4^-8cm²/ N SF1 with a photoelastic constant of 2.62 × 10 4 for the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5^-8cm²/ N SF2 is applied. In this case, it was a level (◯) at which the influence of birefringence could be confirmed at the corners when observed carefully.
[0082]
Experimental Example 13 has a photoelastic constant of 0.65 × 10 for the first, second, and third polarizing beam splitters 2, 3, and 4.^-8cm²/ N PBH6W is applied, and the fourth polarization beam splitter (outgoing side polarization beam splitter) 5 has a photoelastic constant of 2.62 × 10 6.^-8cm²/ N SF2 is applied. In this case, the level (◎) was such that no influence of birefringence was confirmed on the display screen.
[0083]
In Experimental Example 14, only the first polarizing beam splitter (incident side polarizing beam splitter) 2 is 0.03 × 10 6 having the smallest photoelastic constant.^-8cm²/ N PBH55 (Ohara), others have a photoelastic constant of 0.65 × 10^-8cm²/ N PBH6W is applied. In this case, the level (◎) was such that no influence of birefringence was confirmed on the display screen.
[0084]
Experimental Example 15 has a photoelastic constant of 0.03 × 10 for the first, second, and third polarizing beam splitters 2, 3, and 4.^-8cm²/ N PBH55 is applied, and the fourth polarizing beam splitter (light emitting side polarizing beam splitter) 5 has a photoelastic constant of 2.62 × 10 6.^-8cm²/ N SF2 is applied. In this case, the level (◎) was such that no influence of birefringence was confirmed on the display screen.
[0085]
How birefringence occurs depends on the photoelastic constant of the glass substrate, which is a translucent member applied to the polarizing beam splitter, and the brightness of the light source used. Become.
That is, the photoelastic constant of the first polarizing beam splitter (light incident side polarizing beam splitter) 2 is Ki, the photoelastic constant of the second and third polarizing beam splitters (main polarizing beam splitter) 3 and 4 is Km, If the photoelastic constant of the polarization beam splitter 4 (light exit side polarization beam splitter) 4 is Ko, it is necessary to select the glass substrate of each polarization beam splitter so as to satisfy the relationship of Ki <Km and Ko. In this case, Ki <1 × 10^-8cm²When the glass substrate of the first polarizing beam splitter 2 is selected so as to be / N, the problem of birefringence can be solved even when a 200 W class high-intensity light source is used.
[0086]
Preferably, it is necessary to select the glass substrate of each polarization beam splitter so as to satisfy the relationship of Ki <Km <Ko. In this case, Ki <1 × 10^-8cm²/ N, Km <2 × 10^-8cm²When the glass substrates of the first, second and third polarizing beam splitters 2, 3, and 4 are selected so as to be / N, the problem of birefringence can be solved even when a 200 W class high-intensity light source is used. it can.
[0087]
More preferably, it is necessary to select the glass substrate of each polarization beam splitter so as to satisfy the relationship of Ki and Km <Ko. In this case, Ki and Km <1 × 10^-8cm²When the glass substrates of the first, second and third polarizing beam splitters 2, 3, and 4 are selected so as to be / N, the problem of birefringence can be solved even when a 200 W class high-intensity light source is used. it can.
[0088]
Needless to say, the above result of the photoelastic constant of the translucent member constituting the polarizing beam splitter can be applied to the color separation / synthesis optical systems of the first to sixth embodiments. Furthermore, it is needless to say that the above-described result of the photoelastic constant can be applied to a color separation / synthesis optical system having a configuration in which at least the first to fourth polarizing beam splitters are separately separately provided. Absent. Thereby, birefringence can be suppressed more effectively.
[0089]
(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described.
FIG. 13 is a schematic plan view of a color separation / synthesis optical system according to the seventh embodiment of the present invention. The same optical elements as those in the first embodiment of the present invention shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. Here, only the arrangement configuration of each optical element is shown, and only different portions from the first embodiment of the present invention will be described.
[0090]
In FIG. 13, reference numeral 130 denotes a color separation / synthesis optical system according to the seventh embodiment of the present invention. The third wavelength-selective reflecting means 14 and 15 is a portion different from the first embodiment of the present invention in that it is a B phase plate (see FIG. 31) that rotates the polarization plane of B light by 90 °. For this reason, the arrangement positions of the reflective spatial light modulator 62 for R light and the reflective spatial light modulator 63 for B light in the first embodiment of the present invention are interchanged.
[0091]
In this case, since the third wavelength-selective reflecting means 14 and 15 are B phase plates as described above, the R light (broken line) is not affected at all by these. Accordingly, the S-polarized light of the incident R light is reflected as it is by the polarization separation surfaces 21 and 41 of the first and third polarization beam splitters 2 and 4 and enters the R-compatible reflective spatial light modulator 62, where The P-polarized light component modulated in (1) is transmitted through the polarization separation surfaces 41 and 51 of the third and fourth polarization beam splitters 4 and 5 as they are, and further transmitted through the G phase plate 7 as it is and emitted.
[0092]
On the other hand, after the S-polarized light of the B light (two-dot chain line) is reflected by the polarization separation surface 21 of the first polarization beam splitter 2, a third wavelength selective polarization conversion means (hereinafter referred to as a B phase plate). 14 is converted to P-polarized light. Then, the light passes through the polarization separation surface 41 of the third polarization beam splitter 4 and enters the B-type reflective spatial light modulation element 63.
The S-polarized component of the B light modulated here is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and further converted into P-polarized light by the B phase plate 15. Then, the P-polarized light of the B light is transmitted through the polarization separation surface 51 of the fourth polarization beam splitter 5 and the G phase plate 7 as they are, and is emitted.
The G light (solid line) is the same as that described in the first embodiment of the present invention (see FIG. 1), and the polarization planes of the three primary color lights are aligned with the P-polarized light and are emitted from the color separation / synthesis optical system 130.
[0093]
Also in the seventh embodiment of the present invention, white light is separated into RGB three primary color lights and guided to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are also provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the seventh embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0094]
(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described.
FIG. 14 is a schematic plan view of a color separation / synthesis optical system according to the eighth embodiment of the present invention. The same elements as those of the first embodiment of the present invention shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. Here, only the arrangement configuration of each optical element is shown, and only different portions from the first embodiment of the present invention will be described.
[0095]
In FIG. 14, reference numeral 140 denotes a color separation / synthesis optical system according to the eighth embodiment of the present invention. The difference from the first embodiment of the present invention is that G phase plates 16 and 17 are added between the first and second polarizing beam splitters 2 and 3 and between the second and fourth polarizing beam splitters 3 and 5. It is the point that is inserted. For this reason, the reflective spatial light modulation element 61 corresponding to G is disposed on the light transmitting surface 3 d side of the second polarization beam splitter 3.
[0096]
In this case, the S-polarized light of the G light (solid line) is converted into P-polarized light by the G phase plate 6, passes through the polarization separation surface 21 of the first polarization beam splitter 2, and is again transmitted by the G phase plate 16 to S The light is converted into polarized light, is reflected by the polarization separation surface 31 of the second polarization beam splitter 3, and enters the G-type reflective spatial light modulator 61.
Here, the P-polarized component of the G light generated by the light modulation is transmitted through the polarization separation surface 31 of the second polarization beam splitter 3 and converted into S-polarized light by the G phase plate 17. Then, the G light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5, further converted into P-polarized light by the G phase plate 7, and emitted from the color separation / synthesis optical system 140.
On the other hand, since the R light (dashed line) and B light (two-dot chain line) are the same as those in the first embodiment of the present invention, the polarization planes of the three primary color lights are aligned with the P polarized light, and the color separation / synthesis optical system 140 is changed. Eject.
[0097]
Also in the eighth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the eighth embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0098]
(Ninth embodiment)
Next, a ninth embodiment of the present invention will be described.
FIG. 15 is a schematic plan view of a color separation / synthesis optical system according to the ninth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 15, the color separation / synthesis optical system 150 according to the ninth embodiment of the present invention is between the first and second polarizing beam splitters 2 and 3 and between the second and fourth polarizing beam splitters 3 and 5. The G phase plates 16 and 17 are different from the seventh embodiment (see FIG. 13) of the present invention. Accordingly, the spatial light modulation element 61 corresponding to the G light is disposed on the light transmitting surface 3 d side of the second polarization beam splitter 3.
[0099]
In the color separation / synthesis optical system 150, the corresponding optical path of the eighth embodiment of the present invention (see FIG. 14) corresponds to the optical path of G light (solid line), and R light (dashed line) and B light ( The optical path corresponding to the seventh embodiment (see FIG. 13) of the present invention corresponds to the optical path of the two-dot chain line. Therefore, since the changes in the polarization planes of the R, G, and B light are as described in the seventh and eighth embodiments of the present invention, repeated description is omitted, but the polarization of the three primary color lights is not described. The wavefront is aligned with the P-polarized light and exits from the color separation / synthesis optical system 150.
[0100]
Also in the ninth embodiment of the present invention, white light is separated into RGB three primary color lights and guided to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are also provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to the light modulation based on the video signal.
In addition, regarding the ninth embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0101]
(10th Embodiment)
Next, a tenth embodiment of the present invention will be described. Here, only the arrangement of each optical element is shown.
FIG. 16 is a schematic plan view of a color separation / synthesis optical system according to the tenth embodiment of the present invention. As shown in FIG. 16, the color separation / synthesis optical system 160 includes a G phase plate 17 interposed between the second and fourth polarization beam splitters 3 and 5, and the third and fourth polarization beam splitters 4. 5 is replaced with the B phase plate 15, the G phase plate 7 is disposed on the light transmitting surface 5 b side of the fourth polarizing beam splitter 5, and the light emitting direction is changed to the light transmitting surface 5 b. This is different from the color separation / synthesis optical system 1 of the first embodiment of the present invention in that it is a side (see FIG. 1).
[0102]
In this case, for the G light (solid line), the S-polarized light generated by being modulated by the reflective spatial light modulation element 61 corresponding to G is reflected by the polarization separation surface 31 of the second polarization beam splitter 3, and the G phase plate 17 is incident. Here, the G light is polarized and converted to P-polarized light, passes through the polarization separation surface 51 of the fourth polarization beam splitter 5, exits from the light transmitting surface 5 b, and is again polarized and converted by the G phase plate 7 to S. Ejected as polarized light.
[0103]
As for the R light (broken line), the S-polarized component generated by being modulated by the reflective spatial light modulation element 62 corresponding to R is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, and the B phase. After passing through the plate 15 as it is, it is reflected by the polarization splitting surface 51 of the fourth polarization beam splitter 5 and exits the G phase plate 7 with S polarization.
[0104]
On the other hand, for the B light (two-dot chain line), the P-polarized component generated by being modulated by the reflective spatial light modulation element 63 corresponding to B passes through the polarization separation surface 41 of the third polarization beam splitter 4, and B After being converted to S-polarized light by the phase plate 15 for reflection, it is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the phase plate 7 for G with the S-polarized light remaining unchanged. In this way, the polarization planes of the three primary color lights are aligned with the S-polarized light and exit from the color separation / synthesis optical system 160.
[0105]
Also in the tenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, the configuration of the first to sixth embodiments of the present invention described above with respect to the tenth embodiment of the present invention and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0106]
(Eleventh embodiment)
Next, an eleventh embodiment of the present invention will be described. Here, only the arrangement of each optical element is shown.
FIG. 17 is a schematic plan view of a color separation / synthesis optical system according to the eleventh embodiment of the present invention. As shown in FIG. 17, the color separation / synthesis optical system 170 includes the R phase plate 8 as the B phase plate 14 and the B phase plate 15 in the tenth embodiment (see FIG. 16) of the present invention. Is equivalent to an R phase plate 9. Along with this, the spatial light modulation elements 62 and 63 corresponding to R and B are arranged to be exchanged.
[0107]
In this case, the operation of the G light (solid line) is the same as that of the tenth embodiment of the present invention described above, and thus the description thereof is omitted.
For the R light (broken line), the P-polarized component generated by being modulated by the reflective spatial light modulator 62 corresponding to R passes through the polarization separation surface 41 of the third polarization beam splitter 4, and the R phase plate 9. After being converted to S-polarized light, the light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the G phase plate 7 while remaining S-polarized.
[0108]
On the other hand, for the B light (two-dot chain line), the S-polarized component generated by being modulated by the reflective spatial light modulator 63 corresponding to B is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, and R After passing through the phase plate 9 as it is, it is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the phase plate 7 for G with the S polarization.
In this way, the polarization planes of the three primary color lights are aligned with the S-polarized light and exit from the color separation / synthesis optical system 170.
[0109]
Also in the eleventh embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the eleventh embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0110]
(Twelfth embodiment)
Next, a twelfth embodiment of the present invention will be described.
FIG. 18 is a schematic plan view of a color separation / synthesis optical system according to the twelfth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
In FIG. 18, reference numeral 180 denotes a color separation / synthesis optical system according to the twelfth embodiment of the present invention. The difference from the above-described tenth embodiment of the present invention (see FIG. 16) is that a G phase plate 16 is inserted between the first and second polarizing beam splitters 2 and 3 instead of the R phase plate 8. The G phase plate 17 between the second and fourth polarizing beam splitters 3 and 5 is excluded. For this reason, the spatial light modulation element 61 corresponding to G is disposed on the light transmission surface 3 d side of the second polarization beam splitter 3.
[0111]
In this case, the S-polarized light of the G light (solid line) is converted to P-polarized light by the G phase plate 6, passes through the polarization separation surface 21 of the first polarization beam splitter 2, and is again S-polarized light by the G phase plate 16. Is reflected by the polarization separation surface 31 of the second polarization beam splitter 3 and enters the G-type reflective spatial light modulator 61.
The P-polarized component of the G light generated by modulation here passes through the polarization separation surface 31 of the second polarization beam splitter 3 and the polarization separation surface 51 of the fourth polarization beam splitter 5. The G light is converted into S-polarized light by the G phase plate 7 and is emitted from the color separation / synthesis optical system 180.
[0112]
On the other hand, since R light (dashed line) and B light (two-dot chain line) are the same as those in the tenth embodiment of the present invention, when the color separation / synthesis optical system 180 according to the twelfth embodiment of the present invention is both emitted. The polarization planes of the three primary color lights are aligned with the S polarization, and the color separation / synthesis optical system 180 is emitted.
[0113]
Also in the twelfth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the twelfth embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0114]
(13th Embodiment)
Next, a thirteenth embodiment of the present invention is described.
FIG. 19 is a schematic plan view of a color separation / synthesis optical system according to the thirteenth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 19, the color separation / synthesis optical system 190 according to the thirteenth embodiment of the present invention is the same as the color separation / synthesis optical system 180 of the twelfth embodiment of the present invention described above. This is equivalent to the phase plate 14 in which the B phase plate 15 is replaced with the R phase plate 9. Along with this, the R-compatible and B-compatible spatial light modulation elements 62 and 63 are replaced and arranged.
[0115]
In this case, the operation of the G light (solid line) is the same as that of the twelfth embodiment of the present invention, and thus the description thereof is omitted.
For R light (dashed line), S-polarized light is transmitted through the G phase plate 6 as it is, reflected by the polarization separation surface 21 of the first polarizing beam splitter 2, and then transmitted through the B phase plate 14 as it is. The light is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and reaches the R-type reflective spatial light modulator 62.
The P-polarized component of the R light generated by being modulated by the reflective spatial light modulator 62 is transmitted through the polarization separation surface 41 of the third polarization beam splitter 4 and is incident on the R phase plate 9. Here, the R light is converted into S-polarized light, reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5, and exits the G phase plate 7 while remaining as S-polarized light.
[0116]
On the other hand, for B light (two-dot chain line), S-polarized light passes through the G phase plate 6 as it is, is reflected by the polarization separation surface 21 of the first polarization beam splitter 2, and then enters the B phase plate 14. .
In the B phase plate 14, the B light is converted into P-polarized light. Then, the light passes through the polarization separation surface 41 of the third polarization beam splitter 4 and reaches the B-type reflective spatial light modulation element 63.
The S-polarized light generated by being modulated by the reflective spatial light modulator 63 is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, passes through the R phase plate 9 as it is, and is converted into the fourth polarization beam splitter 5. Is incident on. Then, the B light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the G phase plate 7 while being S-polarized light.
Thus, the polarization planes of the three primary color lights are aligned with the S-polarized light, and exit from the color separation / synthesis optical system 190.
[0117]
Also in the thirteenth embodiment of the present invention, the white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, the configuration of the first to sixth embodiments of the present invention described above with respect to the thirteenth embodiment of the present invention and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0118]
(14th Embodiment)
Next, a fourteenth embodiment of the present invention is described.
FIG. 20 is a schematic plan view of a color separation / synthesis optical system according to the fourteenth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 20, in the color separation / synthesis optical system 200 according to the fourteenth embodiment of the present invention, the G phase plate 6 is arranged on the light transmission surface 2d side of the first polarization beam splitter 2, and the light transmission surface 2d is obtained. The light is incident from the side. Further, a G phase plate 16 is disposed between the first and second polarizing beam splitters 2 and 3, and a G phase plate 7 is disposed on the light transmitting surface 5 c side of the fourth polarizing beam splitter 5. Further, an R phase plate 8 is disposed between the first and third polarizing beam splitters 2 and 4, and a B phase plate 15 is disposed between the third and fourth polarizing beam splitters 4 and 5.
[0119]
In this case, the three primary color lights incident on the color separation / synthesis optical system 200 are P-polarized light. Further, a reflective spatial light modulator 61 corresponding to G is disposed on the light transmitting surface 3 c side of the second polarizing beam splitter 3, and an R corresponding reflective space is disposed on the light transmitting surface 4 a side of the third polarizing beam splitter 4. In the light modulation element 62, a reflective spatial light modulation element 63 corresponding to B is disposed on the light transmitting surface 4b side.
[0120]
The P-polarized G light (solid line) incident on the color separation / synthesis optical system 200 is converted to S-polarization by the G phase plate 6, enters the first polarization beam splitter 2, and is reflected by the polarization separation surface 21. . Then, the light is converted into P-polarized light by being subjected to polarization conversion in the G phase plate 16, passes through the polarization separation surface 31 of the second polarization beam splitter 3, and reaches the G-compatible reflective spatial light modulator 61.
The S-polarized component of the G light generated by being modulated by the reflective spatial light modulator 61 is reflected by the polarization separation surfaces 31 and 51 of the second and fourth polarization beam splitters 3 and 5, and the G phase plate 7. And converted to P-polarized light.
[0121]
The P-polarized R light (broken line) passes through the G phase plate 6 and the polarization separation surface 21 of the first polarization beam splitter 2 as it is and enters the R phase plate 8. Then, after being converted to S-polarized light by the R phase plate 8, it is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and reaches the R-compatible reflective spatial light modulator 62.
The P-polarized R light generated by being modulated by the reflective spatial light modulator 62 is converted into the polarization separation surface 41 of the third polarization beam splitter 4, the B phase plate 15, and the polarization separation surface of the fourth polarization beam splitter 5. 51 and G phase plate 7 are both transmitted as P-polarized light and emitted.
[0122]
The P-polarized B light (two-dot chain line) is used for the G phase plate 6, the polarization separation surface 21 of the first polarization beam splitter 2, the R phase plate 8, and the polarization separation surface of the third polarization beam splitter 4. 41 is transmitted as it is, and reaches the reflective spatial light modulation element 63 corresponding to B.
S-polarized B light generated by being modulated by the reflective spatial light modulator 63 is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and then converted to P-polarized light by the B phase plate 15. Both the polarization splitting surface 51 of the fourth polarization beam splitter 5 and the G phase plate 7 are transmitted through and emitted as P-polarized light.
In this way, the polarization planes of the three primary color lights are aligned with the P-polarized light, and the color separation / synthesis optical system 200 is emitted.
[0123]
Also in the fourteenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
Also for the fourteenth embodiment of the present invention, the first to sixth embodiments of the present invention described above, and the first to fourth polarizing beam splitters 2, 3, 4, and 5 translucent members. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0124]
(Fifteenth embodiment)
Next, a fifteenth embodiment of the present invention is described.
FIG. 21 is a schematic plan view of a color separation / synthesis optical system according to the fifteenth embodiment of the present invention.
As shown in FIG. 21, the color separation / combination optical system 210 according to the fifteenth embodiment of the present invention uses the R phase plate 8 as the B phase plate 14 and the B phase plate 14 in the fourteenth embodiment described above. The phase plate 15 is equivalent to the R phase plate 9 replaced. For this reason, the reflection-type spatial light modulation elements 62 and 63 corresponding to R and B are arranged to be exchanged.
[0125]
In this case, the operation of the G light (solid line) is the same as that of the above-described fourteenth embodiment of the present invention, and thus the description thereof is omitted.
P-polarized R light (broken line) passes through the G phase plate 6, the polarization separation surface 21 of the first polarization beam splitter 2, the B phase plate 14, and the polarization separation surface 41 of the third polarization beam splitter 4 as they are. Thus, the reflection type spatial light modulator 62 corresponding to R is reached.
The S-polarized R light generated by being modulated by the reflective spatial light modulator 62 is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and then converted to P-polarized light by the R phase plate 9. Then, the light is transmitted through the polarization separation surface 51 of the fourth polarization beam splitter 5 and the G phase plate 7 as P-polarized light and emitted.
[0126]
The P-polarized B light (two-dot chain line) passes through the G phase plate 6 and the polarization separation surface 21 of the first polarizing beam splitter 2 as it is, and then is converted into S-polarized light by the B phase plate 14. The light is reflected by the polarization separation surface 41 of the third polarization beam splitter 4 and reaches the B-type reflective spatial light modulation element 63.
The P-polarized B light generated by being modulated by the reflective spatial light modulator 63 is used for the polarization separation surface 41 of the third polarization beam splitter 4, the R phase plate 9, and the polarization separation of the fourth polarization beam splitter 5. The light is transmitted through the surface 51 and the G phase plate 7 as P-polarized light.
Thus, the polarization planes of the three primary color lights are aligned with the P-polarized light, and exit from the color separation / synthesis optical system 210.
[0127]
Also in the fifteenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are also provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
The first to sixth embodiments of the present invention and the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described with respect to the fifteenth embodiment of the present invention. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0128]
(Sixteenth embodiment)
Next, a sixteenth embodiment of the present invention will be described.
FIG. 22 is a schematic plan view of a color separation / synthesis optical system according to the sixteenth embodiment of the present invention.
As shown in FIG. 22, the color separation / synthesis optical system 220 according to the sixteenth embodiment of the present invention removes the G phase plate 16 in the fourteenth embodiment (see FIG. 20) of the present invention, and The G phase plate 17 is disposed between the four polarization beam splitters 3 and 5. Therefore, the reflective spatial light modulation element 61 corresponding to G is disposed on the light transmitting surface 3 d side of the second polarization beam splitter 3.
[0129]
In this case, the operations of the R light (broken line) and the B light (two-dot chain line) are the same as those in the above-described fourteenth embodiment of the present invention, and thus description thereof is omitted.
The P-polarized G light (solid line) is converted into S-polarized light by the G phase plate 6, reflected by the polarization separation surfaces 21 and 31 of the first and second polarization beam splitters 2 and 3, and reflected by G. The spatial light modulator 61 is reached.
The P-polarized component G light generated by being modulated by the reflective spatial light modulator 61 is transmitted through the polarization separation surface 31 of the second polarization beam splitter 3 and then converted to S-polarized light by the G phase plate 17. Then, the light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5, converted again to P-polarized light by the G phase plate 7, and emitted.
Thus, the polarization planes of the three primary color lights are aligned with the P-polarized light, and exit from the color separation / synthesis optical system 220.
[0130]
Also in the sixteenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
Further, the configuration of the first to sixth embodiments of the present invention described above with respect to the sixteenth embodiment of the present invention and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0131]
(17th Embodiment)
Next, a seventeenth embodiment of the present invention is described.
FIG. 23 is a schematic plan view of a color separation / synthesis optical system according to the seventeenth embodiment of the present invention.
As shown in FIG. 23, the color separation / combination optical system 230 according to the seventeenth embodiment of the present invention replaces the R phase plate 8 with the B phase plate 14 in the sixteenth embodiment of the present invention (see FIG. 22). , B phase plate 15 is replaced with R phase plate 9. For this reason, the reflection-type spatial light modulation elements 62 and 63 corresponding to R and B are arranged to be exchanged.
In this case, the G light (solid line) acts in the same manner as in the sixteenth embodiment of the present invention and is emitted as P-polarized light. Further, the R light (broken line) and the B light (two-dot chain line) act similarly to the fifteenth embodiment (see FIG. 21) of the present invention, and are emitted as P-polarized light.
In this way, the polarization planes of the three primary color lights are aligned with the P-polarized light and exit from the color separation / synthesis optical system 230.
[0132]
Also in the seventeenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the seventeenth embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the first to fourth polarizing beam splitters 2, 3, 4, and 5 translucent members. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0133]
(Eighteenth embodiment)
Next, an eighteenth embodiment of the present invention will be described.
FIG. 24 is a schematic plan view of a color separation / synthesis optical system according to the eighteenth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 24, in the color separation / synthesis optical system 240, a G phase plate 17 is interposed between the second and fourth polarization beam splitters 3 and 5 in the fourteenth embodiment (see FIG. 20) of the present invention. Further, the wavelength-selective polarization conversion means 15 between the third and fourth polarizing beam splitters 4 and 5 is replaced with an R phase plate 9, and the G phase is placed on the light transmitting surface 5b side of the fourth polarizing beam splitter 5. The plate 7 is disposed and the light emission direction is set to the translucent surface 5b side.
[0134]
In this case, with respect to the operation of the G light (solid line), the S-polarized light generated by being modulated by the reflective spatial light modulator 61 corresponding to G is reflected by the polarization separation surface 31 of the second polarization beam splitter 3 and is used for G. The light enters the phase plate 17. Here, the G light is polarized and converted to P-polarized light, passes through the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits from the light-transmitting surface 5b, and is again polarized and converted by the G phase plate 7 to S-polarized light. It becomes and it injects.
[0135]
For the R light (broken line), the P-polarized component generated by being modulated by the reflective spatial light modulation element 62 corresponding to R is transmitted through the polarization separation surface 41 of the third polarization beam splitter 4, and the R phase. After being converted to S-polarized light by the plate 9, it is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the G phase plate 7 while remaining S-polarized.
[0136]
For the B light (two-dot chain line), the S polarization component generated by being modulated by the reflective spatial light modulation element 63 corresponding to B is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, and R After passing through the phase plate 9 as it is, it is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the phase plate 7 for G with the S polarization.
In this way, the polarization planes of the three primary color lights are aligned with the S-polarized light and exit from the color separation / synthesis optical system 240.
[0137]
Also in the eighteenth embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, the configuration of the first to sixth embodiments of the present invention described above and the first to fourth polarizing beam splitters 2, 3, 4, 5 of the 18th embodiment of the present invention are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0138]
(Nineteenth embodiment)
Next, a nineteenth embodiment of the present invention is described.
FIG. 25 is a schematic plan view of a color separation / synthesis optical system according to the nineteenth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 25, the color separation / synthesis optical system 250 is the same as that obtained by replacing the R phase plates 8 and 9 with B phase plates 14 and 15 in the eighteenth embodiment (see FIG. 24) of the present invention.
[0139]
In this case, the operation of the G light (solid line) is omitted because it exhibits the same operation as that of the eighteenth embodiment of the present invention described above.
For the R light (broken line), the S-polarized component generated by being modulated by the reflective spatial light modulation element 62 corresponding to R is reflected by the polarization separation surface 41 of the third polarization beam splitter 4, and the B phase plate 15. Then, the light is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the G phase plate 7 with S polarization.
[0140]
For the B light (two-dot chain line), the P-polarized component generated by being modulated by the reflective spatial light modulation element 63 corresponding to B passes through the polarization separation surface 41 of the third polarization beam splitter 4, and B After being converted to S-polarized light by the phase plate 15 for reflection, it is reflected by the polarization separation surface 51 of the fourth polarization beam splitter 5 and exits the phase plate 7 for G with the S-polarized light remaining unchanged.
Thus, the polarization planes of the three primary color lights are aligned with the S-polarized light, and the color separation / synthesis optical system 250 is emitted.
[0141]
Also in the nineteenth embodiment of the present invention, white light is separated into three primary color lights of RGB and guided to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are also provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
Further, the configuration of the first to sixth embodiments of the present invention described above and the first to fourth polarizing beam splitters 2, 3, 4, and 5 of the light transmitting member of the nineteenth embodiment of the present invention are also described. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0142]
(20th embodiment)
Next, a twentieth embodiment of the present invention will be described.
FIG. 26 is a schematic plan view of a color separation / synthesis optical system according to the twentieth embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 26, the color separation / synthesis optical system 260 is the same as that obtained by removing the G phase plates 16 and 17 from the eighteenth embodiment (see FIG. 24) of the present invention.
In this case, the reflective spatial light modulation element 61 corresponding to G is disposed on the light transmitting surface 3 d side of the second polarization beam splitter 3.
In the color separation / synthesis optical system 260 according to the twentieth embodiment of the present invention, the operations of the R light (broken line) and the B light (two-dot chain line) are the same as those in the eighteenth embodiment of the present invention, and thus the description thereof is omitted. .
[0143]
P-polarized G light (solid line) is converted to S-polarized light by the G phase plate 6 and enters the first polarization beam splitter 2. Then, the light is reflected by the polarization separation surface 21 of the first polarization beam splitter 2 and the polarization separation surface 31 of the second polarization beam splitter 3 to reach the G-type reflective spatial light modulator 61.
The P-polarized component G light generated by being modulated by the reflective spatial light modulation element 61 is transmitted through the polarization separation surfaces 31 and 51 of the second and fourth polarization beam splitters 3 and 5 as they are, and is thus used for the G phase. The light is converted into S-polarized light by the plate 7 and emitted.
Thus, the polarization planes of the three primary color lights are aligned with the S-polarized light, and exit from the color separation / synthesis optical system 260.
[0144]
Also in the twentieth embodiment of the present invention, white light is separated into RGB three primary color lights and guided to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are also provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the twentieth embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the light transmitting members of the first to fourth polarizing beam splitters 2, 3, 4, 5 The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0145]
(21st Embodiment)
Next, a twenty-first embodiment of the present invention will be described.
FIG. 27 is a schematic plan view of a color separation / synthesis optical system according to the twenty-first embodiment of the present invention. Here, only the arrangement of each optical element is shown.
As shown in FIG. 27, the color separation / synthesis optical system 270 of the twenty-first embodiment of the present invention is equivalent to the nineteenth embodiment (see FIG. 25) of the present invention in which the G phase plates 16 and 17 are excluded.
[0146]
The operation of G light (solid line) is the same as that of the twentieth embodiment of the present invention (see FIG. 26), and the operation of R light (dashed line) and B light (two-dot chain line) is the same as that described above. Since it is the same as that of the nineteenth embodiment of the present invention, repeated description is omitted, but the polarization planes of the three primary colors are aligned with the S-polarized light and emitted from the color separation / synthesis optical system 270.
[0147]
Also in the twenty-first embodiment of the present invention, white light is separated into RGB three primary colors and led to the corresponding reflective spatial light modulators 61, 62, 63, and the reflective spatial light modulators 61, 62 are provided. 63, it is possible to synthesize and emit the three primary color lights of the reflected light subjected to light modulation based on the video signal.
In addition, regarding the twenty-first embodiment of the present invention, the configurations of the first to sixth embodiments of the present invention described above, and the first to fourth polarizing beam splitters 2, 3, 4, and 5 translucent members. The photoelastic constant selection conditions described above can be applied, and the problem of birefringence can be effectively solved.
[0148]
In the above-described embodiments, the G phase plate 6 is disposed on the light incident side of the first polarizing beam splitter 2 and the light emitting side of the fourth polarizing beam splitter 5, respectively. Of course, other wavelength-selective polarization conversion means may be arranged. However, in this case, the wavelength-selective polarization conversion means inserted in the facing portions of the four polarization beam splitters is appropriately selected according to the relative relationship with the position of the reflection type spatial light modulator to be arranged.
[0149]
【The invention's effect】
  As will be apparent from the detailed description above, the color separation / synthesis optical system of the present invention has the inner light-transmitting surface of the first polarization beam splitter on the light incident side where at least the three primary color lights concentrate and become high temperature. Separate at least one surface from other optical members through a gapThis gap is filled with a transparent cushioning memberTherefore, the thermal stress in the first polarizing beam splitter is released, and there is an effect that generation of birefringence can be suppressed.
  In addition, since the thermal stress due to the temperature change in the usage environment is released at the location where the first polarizing beam splitter is disposed, the bonded optical member does not peel off at the bonded portion and has excellent reliability. A system can be provided.
  In addition, since a glass substrate having a small photoelastic constant is selected and used as the translucent member constituting at least the first polarizing beam splitter, generation of birefringence due to thermal stress is more effectively suppressed. can do.
[Brief description of the drawings]
FIG. 1 is a schematic plan view for explaining a first embodiment of the present invention.
FIG. 2 is a schematic diagram for explaining the principle of the influence of birefringence on a projected image.
FIG. 3 is a conceptual diagram comparing normal display and black floating display on a black display screen.
FIG. 4 is a result of measuring the surface temperature of each polarization beam splitter in a black display state.
FIG. 5 is a schematic plan view of a color separation / synthesis optical system according to a second embodiment of the present invention.
FIG. 6 is a schematic plan view of a color separation / synthesis optical system according to a third embodiment of the present invention.
FIG. 7 is a schematic plan view of a color separation / synthesis optical system according to a fourth embodiment of the present invention.
FIG. 8 is a schematic plan view of a color separation / synthesis optical system according to a fifth embodiment of the present invention.
FIG. 9 is a schematic plan view of a color separation / synthesis optical system according to a sixth embodiment of the present invention.
FIG. 10 is a schematic plan view of a color separation / synthesis optical system used in a birefringence experiment.
FIG. 11 is an experimental result in which the influence of birefringence in black display is evaluated by changing the translucent member of each polarization beam splitter.
12 is a diagram showing evaluation criteria for birefringence in the experiment of FIG. 11. FIG.
FIG. 13 is a schematic plan view of a color separation / synthesis optical system according to a seventh embodiment of the present invention.
FIG. 14 is a schematic plan view of a color separation / synthesis optical system according to an eighth embodiment of the present invention.
FIG. 15 is a schematic plan view of a color separation / synthesis optical system according to a ninth embodiment of the present invention.
FIG. 16 is a schematic plan view of a color separation / synthesis optical system according to a tenth embodiment of the present invention.
FIG. 17 is a schematic plan view of a color separation / synthesis optical system according to an eleventh embodiment of the present invention.
FIG. 18 is a schematic plan view of a color separation / synthesis optical system according to a twelfth embodiment of the present invention.
FIG. 19 is a schematic plan view of a color separation / synthesis optical system according to a thirteenth embodiment of the present invention.
FIG. 20 is a schematic plan view of a color separation / synthesis optical system according to a fourteenth embodiment of the present invention.
FIG. 21 is a schematic plan view of a color separation / synthesis optical system according to a fifteenth embodiment of the present invention.
FIG. 22 is a schematic plan view of a color separation / synthesis optical system according to a sixteenth embodiment of the present invention.
FIG. 23 is a schematic plan view of a color separation / synthesis optical system according to a seventeenth embodiment of the present invention.
FIG. 24 is a schematic plan view of a color separation / synthesis optical system according to an eighteenth embodiment of the present invention.
FIG. 25 is a schematic plan view of a color separation / synthesis optical system according to a nineteenth embodiment of the present invention.
FIG. 26 is a schematic plan view of a color separation / synthesis optical system according to a twentieth embodiment of the present invention.
FIG. 27 is a schematic plan view of a color separation / synthesis optical system according to a twenty-first embodiment of the present invention.
FIG. 28 is a schematic diagram showing an optical configuration of a projection display device to which a reflective spatial light modulation element is applied.
FIG. 29 is a diagram showing characteristics of first wavelength selective polarization conversion means (G phase plate).
FIG. 30 is a diagram showing characteristics of second wavelength selective polarization conversion means (R phase plate).
FIG. 31 is a diagram showing characteristics of third wavelength-selective polarization conversion means (phase plate for B).
[Explanation of symbols]
1, 50, 60, 70, 80, 90, 100, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270... DESCRIPTION OF SYMBOLS 2 ... 1st polarizing beam splitter (incident side polarizing beam splitter), 3 ... 2nd polarizing polarizing beam splitter (main polarizing beam splitter), 4 ... 3rd polarizing beam splitter (main polarizing beam splitter), 5 ... 1st 4 polarization beam splitters (exit-side polarization beam splitters), 6, 7, 16, 17... First wavelength selective polarization conversion means (phase plate for G), 8, 9... Second wavelength selective polarization conversion means. (R phase plate), 14, 15 ... third wavelength selective polarization conversion means (B phase plate), 10 ... bonding member, 12 ... buffer member

Claims (7)

Cubic or prismatic first to fourth polarizing beam splitters arranged so that the polarization splitting surfaces formed diagonally are X-shaped;
When the first polarizing beam splitter and the fourth polarizing beam splitter are diagonal, the first polarizing beam splitter is disposed on the light incident side, and the fourth polarizing beam splitter is disposed on the light emitting side, the first PBS of the light incident side, of the inner facing surfaces which are orthogonal to each other of said fourth polarizing beam splitter the light emission side and the first through the fourth polarization beam splitter, two or more of the A wavelength selective conversion means for rotating the polarization plane of the predetermined color light disposed between the inner facing surfaces by 90 °,
Between the first or one of the fourth polarization beam splitter, any three polarization beam splitters and the optical member and the remaining one polarizing beam splitter which is integrated formed by joining a wavelength-selective conversion means A color separation / synthesis optical system characterized in that a gap is provided in the gap and a transparent buffer member is filled in the gap . Cubic or prismatic first to fourth polarizing beam splitters arranged so that the polarization splitting surfaces formed diagonally are X-shaped;
When the first polarizing beam splitter and the fourth polarizing beam splitter are diagonal, the first polarizing beam splitter is disposed on the light incident side, and the fourth polarizing beam splitter is disposed on the light emitting side, the first PBS of the light incident side, of the inner facing surfaces which are orthogonal to each other of said fourth polarizing beam splitter the light emission side and the first through the fourth polarization beam splitter, two or more of the A wavelength selective conversion means for rotating the polarization plane of the predetermined color light disposed between the inner facing surfaces by 90 °,
The first through of the fourth polarization beam splitter, optics and integrated by bonding the wavelength-selective conversion means disposed between any two of the polarizing beam splitter and the two polarizing beam splitters which are adjacent to each other A color separation / synthesis optical system , wherein a gap is provided between the member and the remaining two polarizing beam splitters, and the gap is filled with a transparent buffer member . When the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko,
Ki <Ko and Km
3. The color separation / synthesis optical system according to claim 1, wherein the color separation / synthesis optical system has the following relationship . When the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko,
Ki and Km <Ko
3. The color separation / synthesis optical system according to claim 1, wherein the color separation / synthesis optical system has the following relationship. When the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko,
Ki <Km <Ko
3. The color separation / synthesis optical system according to claim 1, wherein the color separation / synthesis optical system has the following relationship. Cubic or prismatic first to fourth polarizing beam splitters arranged so that the polarization splitting surfaces formed diagonally are X-shaped;
When the said first polarizing beam splitter fourth polarization beam splitters and diagonal, or One of the first polarizing beam splitter the light incident side, the fourth polarizing beam splitter is disposed on the light emitting side Two or more of the light incident side of the first polarizing beam splitter, the light emitting side of the fourth polarizing beam splitter, and the inner facing surfaces orthogonal to each other of the first to fourth polarizing beam splitters. The wavelength selective conversion means for rotating the plane of polarization of the predetermined color light disposed between the inner facing surfaces by 90 °;
When the photoelastic constant of the first polarizing beam splitter is Ki, the photoelastic constant of the second to third polarizing beam splitters is Km, and the photoelastic constant of the fourth polarizing beam splitter is Ko,
Ki <Ko and Km
Or Ki and Km <Ko
Or Ki <Km <Ko
A color separation / synthesis optical system characterized by having any of the following relationships: 7. The color separation / synthesis optical system according to claim 6, wherein the first to fourth polarization beam splitters and the wavelength selectivity conversion unit are joined to each other .

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