JPH11258422A - Polarized beam splitter and projection type display apparatus using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the light transmittance or reflectance of a desired polarized light close to 0% or 100%. SOLUTION: This polarized beam splitter comprises prism member 1, 2 joined to each other while sandwiching a polarization separation film 3 by an adhesive 5. In the inclined face of the prism member 1 facing to that of the prism member 2, the polarization separation film 3 comprising multilayers of a dielectric is formed. In the inclined face of the prism member 2 facing to that of the prism member 1, a reflection preventive film 4 is formed. The adhesive layer 5 is set between the polarization separation film 3 and the reflection preventive film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing beam splitter and a projection type display device using the polarizing beam splitter.

[0002]

2. Description of the Related Art FIG. 30 is a schematic sectional view schematically showing a polarization beam splitter 100 conventionally known. The conventional polarization beam splitter 100 includes prism members 101 and 102 each having a right-angled isosceles triangular prism and a polarization separation film 103 formed of a dielectric multilayer film interposed therebetween. A polarization separation film 103 is previously formed on a slope facing the right-angled portion of the prism member 101 by a physical vapor deposition method such as a vacuum deposition method, and a slope of the prism member 101 on which the polarization separation film 103 is formed, and a prism member 102. The right-angled portion and the inclined surface facing each other are adhered to each other with an optical adhesive 104. This polarization beam splitter 1
As shown in FIG. 30, 00 has a function of splitting incident light of natural polarization into S-polarized light reflected by the polarization separation film 103 and P-polarized light transmitted through the polarization separation film 103.

As a conventional projection display device using such a conventional polarization beam splitter, there is, for example, the following projection display device. That is, the light source light is decomposed into R, G, and B lights by a color separation optical system, and the respective color lights are respectively incident on the respective color light polarization separation optical systems to be polarized and separated, and one of the polarization separated color lights is separated. The polarized light is incident on the light valve for each color light, modulated and emitted, and the modulated light of each color light is analyzed by the polarization separation optical system for each color light, respectively.
A color projection display device that combines the detected light of each color with a color combining optical system and projects the color combined light with a projection optical system is known, for example, Japanese Patent No. 259930.
No. 9 discloses this.

FIG. 31 shows a schematic configuration diagram of the projection type display device disclosed in the above publication, and this conventional projection type display device will be described with reference to FIG.

In this conventional projection type display device, the above-described polarizing beam splitter 100 is used as each of the polarizing beam splitters 74R, 74G and 74B.
The light source light emitted from the light source 71 is incident on a dichroic mirror 72 disposed on the optical axis, and the mirror 72
Are separated into B light transmitted through the mirror 72 and mixed light of R light and B light reflected by the mirror 72 in accordance with the characteristics of the mirror 72. The color-separated B light is incident on the polarization beam splitter 74B, and is reflected by the polarization separation film of the polarization beam splitter 74B by the polarization separation film of the polarization beam splitter 74B. And S-polarized light. The S-polarized light of the B light enters the reflective liquid crystal light valve 75B.

On the other hand, the mixed light of the R light and the G light is incident on a dichroic mirror 73 arranged on the optical axis in parallel with the dichroic mirror 72, and the mirror 73
Are separated into G light reflected by the mirror 73 and R light transmitted through the mirror 73. The color-separated G light is supplied to a polarizing beam splitter 74G.
And is transmitted through the polarization splitting film by the polarization splitting film of the polarization beam splitter 74G and discarded.
The light is polarized and separated into polarized light and S-polarized light reflected by the polarized light separating film. The S-polarized light of the G light is incident on the reflection type light valve 75G. The color-separated R
The light is incident on the polarization beam splitter 74R, and the polarization beam splitting film of the polarization beam splitter 74R causes the P-polarized light transmitted through the polarization beam splitting film to be discarded, and the S-polarized light reflected by the polarization beam splitting film 74R. The light is polarized and separated. The S-polarized light of the R light is incident on the reflection type light valve 75R.

The S-polarized light of each color light incident on each light valve 75R, 75G, 75B is
R, 75G, and 75B modulate and reflect and emit the light, and enter the polarization beam splitters 74R, 74G, and 74B, respectively.
The light is analyzed by 74G and 74B, respectively. That is,
Only the P-polarized light (signal light) of the modulated light of each color light passes through the polarization separation films of the polarization beam splitters 74R, 74G, and 74B (that is, is analyzed), and the P-polarized light (signal light) is modulated. The S-polarized light is polarized beam splitter 74R,
The light is reflected by the polarization separation films 74G and 74B, returns to the light source direction, and is discarded. Polarizing beam splitter 74R, 74
The detection light (P-polarized light) of each color light detected by G and 74B is subjected to color synthesis by a color synthesis optical system including two dichroic mirrors 76 and 77, and the color synthesized light is projected onto a projection lens 78. Is projected on a screen (not shown).

[0008]

The conventional projection display device has a problem that the brightness and contrast of the projected image projected on the screen are insufficient.

In order to achieve higher brightness in a conventional projection display device, a high-output light source may be used. However, in this case, not only does the use of power increase, but also the problem of a rise in temperature due to the increase in the amount of heat generated by the light source due to the increase in output, and one of the polarized lights that are polarized and separated by the polarization beam splitter and discarded. A problem associated with an increase in the amount of light is newly generated. Moreover, increasing the output of the light source does not provide any solution to the contrast problem.

The present invention has been made in view of such circumstances, and it is possible to achieve high brightness without increasing the output of a light source and to improve the contrast of a projected image. An object of the present invention is to provide a projection display device and a polarizing beam splitter that can be used for the projection display device.

[0011]

As a result of research, the present inventors have increased the output of the light source by making the configuration of the polarizing beam splitter used in the projection type display device different from that of the conventional polarizing beam splitter. Even without this, it is possible to increase the amount of light for forming a projected image and increase the brightness as compared with a projection type display device such as the conventional projection type display device, and to improve the contrast of the projected image. I found that I can do that.

The present invention has been made based on such new findings by the present inventors.

[0013] A polarizing beam splitter according to a first aspect of the present invention is the polarizing beam splitter having first and second prism members joined by an adhesive with a polarization separating film interposed therebetween. The polarization separation film is formed on a surface of the second prism member facing the second prism member, an anti-reflection film is formed on a surface of the second prism member facing the first prism member, and the adhesive is It is disposed between a polarization splitting film and the antireflection film.

As in the first embodiment, when an antireflection film is formed and an adhesive is arranged between the polarization splitting film and the antireflection film, an ideal polarization beam splitter is obtained as compared with the above-described conventional polarization beam splitter. Separation characteristics can be obtained, and the transmittance or reflectance of the desired polarized light can be closer to 0% or 100%.

According to a second aspect of the present invention, there is provided a polarizing beam splitter according to the first aspect, wherein the first and second prism members have a refractive index of 1.80 or more. It is made of material.

In the configuration of the first aspect, when the refractive index of the light-transmitting material constituting the first and second prism members is large, the structure is more ideal than the above-described conventional polarizing beam splitter. The degree of approaching the polarization separation characteristics increases. For this reason, as in the second aspect, the first and second
Is particularly preferable when the prism member is made of a translucent material having a refractive index of 1.80 or more.

According to a third aspect of the present invention, there is provided a polarization beam splitter according to the first or second aspect, wherein the first and second prism members are arranged so as to be incident on the polarization beam splitter. The absolute value of the photoelastic constant for light of a wavelength is 1.5 × 10 ⁻⁸ cm ²
/ N or less.

In the polarizing beam splitter, if the prism member is made of a material having a large photoelastic constant, the prism member is processed (cutting, joining with another material, film formation on the surface), and the prism member is formed. Due to external stress generated during the operation of incorporating the member into the optical system (holding with a jig, bonding, etc.), heat inside the prism member (absorption of light energy, etc.) or external heat (heat from peripheral devices, etc.) The birefringence induced by the prism member increases due to the generated thermal stress or the stress generated when a light-transmitting material and a material having a different coefficient of thermal expansion are brought into contact with each other at the time of heat generation, thereby increasing the polarization beam splitter. The polarization characteristics are greatly disturbed, and for example, when used in a projection display device, the image quality is greatly deteriorated. In this regard, as in the third aspect, the first and second prism members are provided with an absolute value of a photoelastic constant of 1.5 × 10 ⁻⁸ cm for light of a predetermined wavelength incident on the polarizing beam splitter. ^By using a light-transmitting material of ² / N or less, it is possible to secure optically stable performance against the influence of various thermal stresses and external stresses on the prism member. For example, when the prism member is used in a projection display device, Image quality degradation can be reduced. A light-transmitting material having an absolute value of photoelastic constant of 1.5 × 10 ⁻⁸ cm ² / N or less generally has a high refractive index and is often 1.80 or more. It is particularly preferable to adopt the configuration as described in the embodiment.

A projection display apparatus according to a fourth aspect of the present invention includes a polarizing beam splitter, a light valve, and a projection optical system, wherein the polarizing beam splitter separates light from a light source into two polarized lights. The light valve modulates one of the polarized lights separated by the polarization beam splitter, the polarization beam splitter detects the light modulated by the light valve, and the projection optical system outputs the polarized light beam. In a projection display device for projecting light detected by a splitter, the polarizing beam splitter according to any one of the first to third aspects is used as the polarizing beam splitter.

According to the fourth aspect, the polarization beam splitter according to any one of the first to third aspects is used as a polarization beam splitter for detecting light modulated by the light valve. As described above, since the polarization beam splitter has ideal polarization separation characteristics as compared with the conventional polarization beam splitter, high brightness can be achieved without increasing the output of the light source. At the same time, the contrast of the projected image can be improved.

A projection type display device according to a fifth aspect of the present invention comprises a color separation optical system for separating light from a light source into R light, G light and B light, and first, second and third lights. A valve,
A first, a second, and a third polarizing beam splitter provided corresponding to each of the color lights separated by the color separation optical system, a color combining optical system, and a projection optical system, The first, second and third polarization beam splitters respectively separate each color light separated by the color separation optical system into two polarized lights, and the first, second and third light valves. Modulates one polarized light of each of the color lights polarized and separated by the first, second and third polarization beam splitters, respectively, and the first, second and third polarization beam splitters The respective color lights modulated by the first, second and third light valves are respectively analyzed, and the color synthesizing optical system analyzes the respective color lights detected by the first, second and third polarization beam splitters. Color synthesis, the projection optical system,
The light beam that has been color-combined by the color-combining optical system is projected, and the first, second, and third polarization beam splitters each include the polarization beam splitter according to any one of the first to third aspects. It is a thing.

According to the fifth aspect, similarly to the fourth aspect, the polarization beam splitter for detecting the light modulated by the light valve is a polarization beam splitter according to any one of the first to third aspects. Since the beam splitter is used, as described above, the polarization beam splitter has ideal polarization separation characteristics as compared with the conventional polarization beam splitter, so that the output of the light source does not need to be increased. High brightness can be achieved, and the contrast of the projected image can be improved.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a polarizing beam splitter and a projection display device according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] First, a first embodiment of the present invention will be described.
A polarization beam splitter according to the embodiment will be described with reference to FIG. FIG. 1 is a schematic sectional view showing a polarization beam splitter according to the present embodiment.

The polarization beam splitter according to the present embodiment is composed of first and second light-transmitting materials having substantially the same right-angled isosceles triangular prism shape joined by an adhesive 5 with the polarization separation film 3 interposed therebetween. Are provided. On a surface of the first prism member 1 facing the second prism member 2 (in the present embodiment, a slope facing a right angle portion), a polarization separation film 3 made of a dielectric multilayer film is formed. An antireflection film 4 is formed on a surface of the second prism member 2 facing the first prism member 1 (in the present embodiment, a slope facing a right angle portion).
The adhesive layer 5 is disposed between the polarization splitting film 3 and the antireflection film 4.

First, in this embodiment, a light-transmitting material forming the prism members 1 and 2 will be described.

Generally, an isotropic light-transmitting material such as glass is used as the light-transmitting member used for the prism member of the polarization beam splitter. The light-transmitting material has optical anisotropy and has birefringence like a certain crystal. Such a phenomenon is called a photoelastic effect. The refractive index of the translucent material when stress is generated can be represented by a refractive index ellipsoid, and the main refractive index axis of the refractive index ellipsoid coincides with the main stress axis. Generally, the principal refractive indices are n ₁ , n ₂ ,
Assuming that n ₃ and main stresses are σ ₁ , σ ₂ , and σ ₃ (those having common indices are in the same direction), the following relationship is established between them.

[0028]

N ₁ = n ₀ + C ₁ σ ₁ + C ₂ (σ ₂ + σ ₃ ) (1)

[0029]

N ₂ = n ₀ + C ₁ σ ₂ + C ₂ (σ ₃ + σ ₁ ) (2)

[0030]

N ₃ = n ₀ + C ₁ σ ₃ + C ₂ (σ ₁ + σ ₂ ) (3)

Here, C ₁ and C ₂ are constants specific to the wavelength of light and the substance of the translucent material. Here, n ₀ is the refractive index when there is no stress.

When light is incident on such a translucent material, if the coordinates are set so that the direction is the same as σ ₃ , the incident light will be in the σ ₁ and σ ₂ directions, ie, mutually The vibration plane is divided into two orthogonal linearly polarized light components. When light is emitted from the translucent material, the refractive indices (n ₁ , n ₂ ) in the respective principal stress directions are different. Therefore, between these two linearly polarized light components, Optical path difference (phase difference)
Δφ occurs.

[0033]

Δ４ = (2π / λ) × (n ₁ −n ₂ ) × l = (2π / λ) × (C ₁ −C ₂ ) × (σ ₂ −σ ₁ ) × l = (2π / λ) ) × C × (σ ₂ −σ ₁ ) × 1 (4)

Here, λ is the light wavelength, and l is the light transmission thickness of the light transmitting material. C = (C ₁ −C ₂ ) is called a photoelastic constant, and is a coefficient (birefringence amount per unit stress) indicating the magnitude of birefringence caused by stress.

The present inventors prepared glasses of various compositions as translucent materials for a polarizing beam splitter, and applied σ ₂ = σ _{3 to the} sample by using linearly polarized monochromatic light of various wavelengths.
The birefringence of the sample was measured in a state where a known stress was applied in a direction where = 0, and the photoelastic constant C of the sample was calculated from Equations 1 to 4 above. The range of the composition of the produced glass is
It was as shown below in terms of weight% in terms of oxide.

SiO ₂ 17.0 to 29.0% LiO ₂ + Na ₂ O + K ₂ O 0.5 to 5.0% PbO 70.0 to 75.0% As ₂ O ₃ + Sb ₂ O ₃₀ to 3.0 %

The reason for setting the composition range of each component in this way is as follows.

PbO (lead oxide) of the above composition components
Is used to control the value of the photoelastic constant C by utilizing the fact that the value of the photoelastic constant C greatly depends on the content of PbO in the glass of the composition system containing PbO. It is considered that the value of the photoelastic constant C changes depending on the PbO content because the coordination state of the lead ion changes as the content increases.

SiO ₂ is an optical glass-forming oxide of this glass, and is desirably contained in an amount of 17% by weight or more. However, the upper limit of the content of SiO ₂ is 29% by weight when the content of PbO is set to the aforementioned weight%.

An alkali metal component such as LiO ₂ + Na ₂ O + K ₂ O has an effect of lowering the melting temperature and the glass transition temperature of the glass and increasing the stability against devitrification of the glass. It is desirable.
However, if the content exceeds 5% by weight, the chemical durability of the glass is impaired, which is not preferable.

As ₂ O ₃ , Sb ₂ to be used as a defoaming agent
O ₃ or (As ₂ O ₃ + Sb ₂ O ₃ ) is optionally
It is possible to mix it in the glass raw material, but if the content exceeds 3% by weight, the devitrification resistance and spectral transmittance of the glass are undesirably impaired.

Table 1 shows some of the results of the measurements performed as described above. Table 1 shows each glass sample No. 1 to N
o. 8 shows the composition, the wavelength at which the absolute value of the photoelastic constant C of the glass sample becomes minimum (that is, becomes substantially zero), and the refractive index.

[0043]

[Table 1]

In the glass manufactured here, oxides, fluorides, hydroxides, carbonates, nitrates and the like are prepared as raw materials corresponding to the respective components shown in Table 1, and they are weighed at a predetermined ratio. Mix to make a blended material, 900 ° C ~ 1300
It is manufactured by heating to ℃, homogenizing by melting, fining and stirring in an electric furnace, then casting into a preheated mold and gradually cooling. Then, a glass sample No. as a measurement sample of the photoelastic constant C was used. 1 to No. Numeral 8 is obtained by grinding and polishing the glass of each composition thus manufactured.

From the measurement results shown in Table 1, that is, the measurement results of the wavelength of light at which the absolute value of the photoelastic constant C is minimized, the Pb in the composition of the glass in the above composition range was obtained.
It has been found that there is a correlation shown in FIG. 2 between the O content and the wavelength at which the absolute value of the photoelastic constant C is minimum. However, the curve in FIG. 2 indicates that the content of PbO is 71% by weight to 7% by weight.
Between 5% by weight, a third-order polynomial was fitted. Thereby, in the composition in the range in FIG.
It has been found that by controlling the content, the wavelength of light at which the absolute value of the photoelastic constant C becomes a minimum can be controlled. From FIG. 2, for example, the B light wavelength range of 380 nm
In order to minimize the absolute value of the photoelastic constant C at 500 nm, the PbO content should be 71.0% by weight to 73.7%.
It can be seen that the weight% should be used.

On the other hand, the present inventors prepared three types of polarizing beam splitters, and based on the evaluation results of the polarizing beam splitters, it was found that the translucent material used in the polarizing beam splitter, the prism, and the like was different from the wavelength of the incident light. It was concluded that the absolute value of the photoelastic constant is preferably 1.5 × 10 ⁻⁸ cm ² / N or less. That is, the three types of polarizing beam splitters are (1) glass having a composition within the above-described composition range and manufactured by the above-described process, and the absolute value of the photoelastic constant C for green monochromatic light having a predetermined wavelength. (2) the absolute value of the photoelastic constant C with respect to the green monochromatic light is 1.33 × 10 ^−8, which is not more than 0.01 × 10 ⁻⁸ cm ² / N. c
m ² / N that is configured using a member made of glass, a member made (3) Glass of the absolute value of photoelastic constant C for the green monochromatic light 2.0 × 10 ^-8 cm ² / N What was constituted using was prepared. Then, the S-polarized green light is incident on each polarization beam splitter, the light reflected and emitted by the polarization beam splitter is reflected by a mirror, and is again incident on the polarization beam splitter.
Light reflected by the mirror and transmitted through the polarizing beam splitter was projected on a screen, and illuminance unevenness was measured and evaluated on the screen. As a result, in the case of the polarizing beam splitter of (1), illuminance non-uniformity hardly occurs, and in the case of the polarizing beam splitter of (2), illuminance non-uniformity can be observed, but is sufficient for practical use. In the case of the polarizing beam splitter (3), remarkable illuminance unevenness was observed. From this evaluation result, the absolute value of the photoelastic constant C for incident light is 1.5 × 10 ⁻⁸ cm ² / N or less (that is, the photoelastic constant) for a prism member such as a polarizing beam splitter employed in a projection display device. + 1.5 × when C is −1.5 × 10 ⁻⁸ cm ² / N or more
If a member made of a light-transmitting material of 10 ⁻⁸ cm ² / N or less is used, a conventional light-transmitting material (for example, BK7 is 2.78)
(10 × ^{8 −8} cm ² / N), it can be seen that a projection-type display device can be obtained in which optically stable performance can be sufficiently ensured and deterioration of the quality of a projected image is sufficiently suppressed.

FIG. 3 shows the results of the measurement described above.
Sample No. in Table 1 1 to No. The curve showing the wavelength dependence of the photoelastic constant C of No. 7 is shown. These curves are obtained by fitting measurement points obtained for each sample to a third-order polynomial. From FIG. 3, the following has been found. In other words, the photoelastic constant has the characteristic of a convex shape rising upward to the right as a function of the wavelength, and the rate at which the photoelastic constant C increases as the wavelength increases becomes smaller.

The sample No. in Table 1 1 to No. 8 has a refractive index of 1.80 or more.

The above sample No. 1 to No. 8 is an example of a light-transmitting material that can be used as a light-transmitting material constituting the prism members 1 and 2 in the present embodiment. As can be understood from the above description, the sample No. 8 is used.
1 to No. 7 is preferably used. Further, even though the absolute value of the photoelastic constant is 1.5 × 10 ⁻⁸ cm ² / N or less as described above, blue (B)
Since the absolute value is considerably large in the light region, the light absorption is particularly large in the wavelength region in consideration of the fact that the light absorption is larger than the green (G) light and red (R) light wavelength regions. It is desirable not to use it for B light.

As can be understood from FIG. 2, when the absolute value of the photoelastic constant is minimized in the B light wavelength region, the PbO content is set to 71% by weight to 73.7% by weight in the above-described composition range. %, And a light-transmitting material having such a composition range is an example of a light-transmitting material that can be used as a light-transmitting material constituting the prism members 1 and 2 in the present embodiment.

According to the present embodiment, the light-transmitting material constituting the prism members 1 and 2 is as described above.
The absolute value of the photoelastic constant for light of a predetermined wavelength incident on the polarizing beam splitter is 1.5 × 10 ⁻⁸ cm ² / N
Since the following translucent members are used, it is possible to secure the optically stable performance by reducing the occurrence of birefringence against the effects of various thermal stresses and external stresses, and to ensure the image quality such as color unevenness. Deterioration can be suppressed. However, in the present invention, the translucent materials forming the prism members 1 and 2 are not necessarily limited to such translucent materials.

In the present embodiment, the sample N in Table 1 is used as a light-transmitting material for forming the prism members 1 and 2.
o. 1 to No. Although a translucent material having a refractive index of 1.80 or more, such as 8, is used, the refractive index does not necessarily need to be 1.80 or more in the present invention.

Next, specific examples of the polarization beam splitter according to the first embodiment shown in FIG. 1 and its characteristics will be described.
explain.

In the polarization beam splitters according to various specific examples of the first embodiment described below and the polarization beam splitters according to the comparative examples to be compared with the polarization beam splitters, the light transmitting prisms constituting the prism members 1 and 2 are all provided. As a conductive material,
Sample No. in Table 1 6 (refractive index 1.849) is used.

(First Specific Example of First Embodiment and First Embodiment
Third Comparative Example) A first specific example of the first embodiment is shown in FIG. 4 as an antireflection film 4 formed on a slope of a prism member 2 in the polarization beam splitter shown in FIG. As shown in FIG. 8, a single-layer film of aluminum oxide (Al ₂ O ₃ ) (refractive index 1.62, film thickness 134 nm) is adopted as the polarization separating film 3 formed on the slope of the prism member 1.
As shown in the figure, silicon dioxide (SiO ₂ : refractive index n = 1.4)
7) and titanium dioxide (TiO ₂ : refractive index n =
And a layer composed of 2.2) and a total of 21 layers each having a film thickness shown in FIG. 8 alternately, which is disposed between the antireflection film 4 and the polarization separation film 3. As the adhesive 5, a commercially available optical adhesive (refractive index 1.52, film thickness 10 microns) is employed. The polarization splitting film 3 shown in FIG. 8 is configured for B light for 45-degree incidence. FIG. 4 is a schematic cross-sectional view schematically illustrating an example of the antireflection film 4, and FIG. 8 is a schematic cross-sectional view schematically illustrating an example of the polarization separation film 3.

A first comparative example to be compared with the first specific example is one in which only the polarization splitting film 3 is removed from the polarization beam splitter according to the first specific example. This is the same as the first specific example.

The second comparative example is different from the polarization beam splitter according to the first embodiment in that the polarization splitting film 3 is used.
And the antireflection film 4 is removed, and the other configuration is the same as that of the first specific example.

Further, a third comparative example is shown in FIG.
In the polarization beam splitter according to the first specific example, only the antireflection film 4 is removed so as to have the same configuration as the conventional polarization beam splitter shown in FIG. They are the same.

FIG. 6 shows the characteristics of the polarizing beam splitter according to the first comparative example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 7 is a diagram showing (curves in FIG. 6) and characteristics (curves in FIG. 6) of the polarizing beam splitter according to the second comparative example. 6, the vertical axis indicates the reflectance (%) and the horizontal axis indicates the wavelength (nm) (see FIGS. 6, 7,
9, 10, 12, 13, 15, 16, 1
8, FIG. 19, FIG. 22, FIG. 23, FIG. 25, and FIG. However, FIG. 6, FIG. 7, FIG. 9, FIG.
2, FIG. 13, FIG. 15, FIG. 16, FIG. 18, FIG. 22, FIG.
The vertical axis indicates that 1% is the full scale, whereas FIG.
9. Note that the vertical axes in FIGS. 23 and 26 show 10% as full scale. ).

As can be understood from FIG. 6, the polarization separation film 3
Is provided, when the antireflection film 4 is provided, the reflectance of the P-polarized light is reduced (that is, the transmittance is increased) over the entire wavelength range as compared with the case where the antireflection film 4 is not provided. The characteristics have been greatly improved.

FIG. 9 shows the polarized light for B light according to the first specific example when the P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 3 is a diagram illustrating characteristics of a beam splitter. On the other hand, FIG.
4 for the bonding surface (slope) of the prism members 1 and 2
When the P-polarized light is incident at an incident angle of 5 degrees, the third
FIG. 9 is a diagram illustrating characteristics of a polarizing beam splitter according to a comparative example.

As can be seen from a comparison between FIG. 9 and FIG.
In the B-light polarization beam splitter according to the first specific example, in the B-light wavelength region (400 nm to 500 nm), compared to the third comparative example in which the antireflection film 4 is not provided, the P-polarized light The reflectance is reduced (ie, the transmittance is increased) and the properties are greatly improved.

(The second concrete example of the first embodiment and the fourth concrete example)
Comparative Example) The second specific example of the first embodiment is a polarization beam splitter according to the first specific example,
As the polarization separation film 3 formed on the inclined surface of the prism member 1, a dielectric multilayer film for G light shown in FIG. 11 is employed instead of the dielectric multilayer film for B light shown in FIG.

That is, the second specific example of the first embodiment is a polarization beam splitter shown in FIG.
As shown in FIG. 4, a single-layer film of aluminum oxide (Al ₂ O ₃ ) (refractive index 1.62, film thickness 134 nm) was used as the anti-reflection film 4 formed on the slope of the prism member 2. As the polarization separation film 3 formed on the slope of
As shown in FIG. 11, silicon dioxide (SiO ₂ : refractive index n =
1. A dielectric multilayer film comprising a total of 21 layers of a layer of 1.47) and a layer of titanium dioxide (TiO ₂ : refractive index n = 2.2) each having a thickness shown in FIG. Then, as the adhesive 5 disposed between the antireflection film 4 and the polarization separation film 3, a commercially available optical adhesive (refractive index: 1.52,
(A film thickness of 10 microns). The polarization splitting film 3 shown in FIG. 11 is configured for G light for 45-degree incidence. FIG. 11 is a schematic sectional view schematically showing another example of the polarized light separating film 3.

A fourth comparative example, which is compared with the second specific example, has a configuration similar to that of the conventional polarization beam splitter shown in FIG. Only the antireflection film 4 is removed, and the other configuration is the same as that of the second specific example.

FIG. 12 shows polarized light for G light according to the second specific example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 3 is a diagram illustrating characteristics of a beam splitter. On the other hand, FIG.
FIG. 9 is a diagram illustrating characteristics of a polarization beam splitter according to the fourth comparative example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. .

As can be seen from the comparison between FIG. 12 and FIG. 13, in the polarization beam splitter for G light according to the second embodiment, the antireflection film 4 is provided in the G light wavelength region (500 nm to 600 nm). As compared with the above-mentioned fourth comparative example, the reflectance of P-polarized light is reduced (that is, the transmittance is increased), and the characteristics are greatly improved.

(The third specific example of the first embodiment and the fifth
Comparative Example 3) A third specific example of the first embodiment is a polarization beam splitter according to the first specific example.
As the polarized light separating film 3 formed on the inclined surface of the prism member 1, a dielectric multilayer film for R light shown in FIG. 14 is adopted instead of the dielectric multilayer film for B light shown in FIG.

That is, the third example of the first embodiment is a polarization beam splitter shown in FIG.
As shown in FIG. 4, a single-layer film of aluminum oxide (Al ₂ O ₃ ) (refractive index 1.62, film thickness 134 nm) was used as the anti-reflection film 4 formed on the slope of the prism member 2. As the polarization separation film 3 formed on the slope of
As shown in FIG. 14, silicon dioxide (SiO ₂ : refractive index n =
1. A dielectric multilayer film comprising a total of 21 layers of a layer made of 1.47) and a layer made of titanium dioxide (TiO ₂ : refractive index n = 2.2) each having a thickness shown in FIG. Then, as the adhesive 5 disposed between the antireflection film 4 and the polarization separation film 3, a commercially available optical adhesive (refractive index: 1.52,
(A film thickness of 10 microns). The polarization splitting film 3 shown in FIG. 14 is configured for R light for 45-degree incidence. FIG. 14 is a schematic sectional view schematically showing still another example of the polarized light separating film 3.

In the fifth comparative example, which is compared with the third specific example, the polarization beam splitter according to the third specific example has the same configuration as the conventional polarization beam splitter shown in FIG. Only the antireflection film 4 is removed, and the other configuration is the same as that of the third specific example.

FIG. 15 shows the polarized light for R light according to the third embodiment when the P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 3 is a diagram illustrating characteristics of a beam splitter. On the other hand, FIG.
FIG. 13 is a diagram illustrating characteristics of the polarization beam splitter according to the fifth comparative example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. .

As can be seen from a comparison between FIG. 15 and FIG. 16, in the polarization beam splitter for R light according to the third embodiment, the antireflection film 4 is provided in the R light wavelength region (600 nm to 700 nm). As compared with the above-mentioned fourth comparative example, the reflectance of P-polarized light is reduced (that is, the transmittance is increased), and the characteristics are greatly improved.

Although the polarizing beam splitters according to the first, second and third specific examples are each configured for each color light, the polarizing beam splitter for white light (from the B light region to the R light wavelength region). In the case of a polarizing beam splitter that covers all of the above, when the prism members 1 and 2 having a high refractive index of 1.80 or more as described above are used,
In view of the characteristics of the polarization splitting film in consideration of the refractive index, it has an effect similar to the polarization beam splitters according to the first, second, and third specific examples produced for each of the above-described color lights by disposing the antireflection film 4. Fabrication of things is difficult.

(The fourth concrete example of the first embodiment and the sixth concrete example)
-Eighth Comparative Example) In the fourth specific example of the first embodiment, the antireflection film 4 formed on the slope of the prism member 2 in the polarization beam splitter shown in FIG. Different from the third specific example, as shown in FIG. 5, a dielectric laminated film having a three-layer structure of SiO ₂ —Al ₂ O ₃ —SiO ₂ is employed, and polarization separation formed on the slope of the prism member 1 is performed. As the film 3, as shown in FIG. 17, a layer made of silicon dioxide (SiO ₂ : refractive index n = 1.47) and a layer made of titanium dioxide (TiO ₂ : refractive index n = 2.2) are shown in FIG. , A dielectric multilayer film composed of a total of 21 layers alternately laminated with the film thickness shown in FIG.
And a commercially available optical adhesive (refractive index: 1.42, film thickness: 10 microns) having a refractive index different from those of the first to third specific examples described above. It is. The polarization splitting film 3 shown in FIG. 17 is configured for B light for 45-degree incidence. FIG. 5 is a schematic sectional view schematically showing another example of the antireflection film 4, and FIG. 17 is a schematic sectional view schematically showing still another example of the polarization splitting film 3.

A sixth comparative example, which is compared with the fourth specific example, is a polarization beam splitter according to the fourth specific example, in which only the polarization separation film 3 is removed. This is the same as the specific example of FIG.

The seventh comparative example is a modification of the polarization beam splitter according to the fourth embodiment.
And the antireflection film 4 is removed, and the other configuration is the same as that of the fourth specific example.

Further, the eighth comparative example corresponds to FIG.
In the polarization beam splitter according to the fourth embodiment, only the antireflection film 4 is removed so as to have the same configuration as the conventional polarization beam splitter shown in FIG. They are the same.

FIG. 7 shows the characteristics of the polarizing beam splitter according to the sixth comparative example when P-polarized light is made incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 9 is a diagram showing a curve (curve in FIG. 7) and characteristics (curve in FIG. 7) of a polarizing beam splitter according to the seventh comparative example.

As can be understood from FIG. 7, the polarization separation film 3
Is provided, when the antireflection film 4 is provided, the reflectance of the P-polarized light is reduced (that is, the transmittance is increased) over the entire wavelength range as compared with the case where the antireflection film 4 is not provided. The characteristics have been greatly improved.

FIG. 18 shows the polarization for B light according to the fourth example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 1 and 2. FIG. 3 is a diagram illustrating characteristics of a beam splitter. On the other hand, FIG.
FIG. 19 is a diagram showing characteristics of the polarization beam splitter according to the eighth comparative example when P-polarized light is incident at an incident angle of 45 degrees with respect to the bonding surfaces (slope surfaces) of the prism members 1 and 2. .

As can be seen from a comparison between FIG. 18 and FIG. 19, in the polarization beam splitter for B light according to the fourth embodiment, the antireflection film 4 is provided in the B light wavelength region (400 nm to 500 nm). Compared with the above-described eighth comparative example, the reflectance of P-polarized light is reduced (that is, the transmittance is increased), and the characteristics are greatly improved. As described above, the full scale on the vertical axis in FIG. 18 is 1%, whereas the full scale on the vertical axis in FIG. 19 is 10%.

As in the case of the second and third embodiments, in the polarization beam splitter according to the fourth embodiment, the polarization beam splitting film 3 formed on the inclined surface of the prism member 1 in FIG. By adopting a dielectric multilayer film for G light or R light (not shown) in place of the dielectric multilayer film for B light shown in FIG. It goes without saying that a polarization beam splitter for R light can be obtained.

As can be seen from the above description of each specific example,
According to the polarization beam splitter according to the first embodiment, an antireflection film 4 is provided in addition to the polarization separation film 3, and the adhesive 5 is disposed between the polarization separation film 3 and the antireflection film 4. As a result, ideal polarization separation characteristics can be obtained as compared with the conventional polarization beam splitter, and the transmittance or reflectance of the desired polarized light can be made closer to 0% or 100%.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
The polarization beam splitter according to the embodiment will be described with reference to FIG. FIG. 20 is a schematic sectional view showing the polarization beam splitter according to the present embodiment.

The polarizing beam splitter according to the first embodiment shown in FIG. 1 has a square cross section,
The polarization beam splitter according to the present embodiment is an example of a polarization beam splitter for 52-degree incidence.

The polarization beam splitter according to the present embodiment is composed of first and second prisms made of a translucent material having substantially the same trapezoidal columnar shape and joined by an adhesive 15 with the polarization separation film 13 interposed therebetween. It has members 11 and 12.
As in the first embodiment described above, a polarization separation film 13 made of a dielectric multilayer film is formed on a surface of the first prism member 11 facing the second prism member 12. An anti-reflection film 14 is formed on a surface of the second prism member 12 facing the first prism member 11. The adhesive layer 15 is disposed between the polarization splitting film 13 and the antireflection film 14.

In the present embodiment, as shown in FIG.
The prism members 11 and 12 can be made of the same translucent material as the prism members 1 and 2 of the first embodiment. However, the shapes of the prism members 11 and 12 are determined according to the incidence of 52 degrees. I have. That is, as shown in FIG. 20, the incident surface is formed perpendicular to the incident optical axis, enters the antireflection film 14 at an incident angle of 52 degrees, and is incident on the antireflection film 14 according to the law of reflection. The exit surface of the reflected light and the light that passes through the antireflection film 14 as it is and is reflected and emitted by the polarization separation film 13 is also formed perpendicular to the emission optical axis. In addition, the exit surface of the light that has passed through the antireflection film 14 and the polarization separation film 13 as it is and is transmitted through the antireflection film 14 is also formed perpendicular to the emission optical axis. When the prism members 11 and 12 are made of the same translucent material as the prism members 1 and 2 according to the first embodiment, the film configurations of the antireflection film 14 and the polarization separation film 13 and the film thickness are 52 degrees. It is appropriately changed according to the incidence.

(The first specific example of the second embodiment and the ninth
Next, a first specific example of the polarizing beam splitter according to the second embodiment shown in FIG. 20 and its characteristics will be described.

In the polarization beam splitter according to the first specific example of the second embodiment, as in the first to third specific examples of the first embodiment described above, the prism members 11, 1 are provided.
Sample No. 2 in Table 1 was used as the light-transmitting material constituting Sample No. 2. 6
(Refractive index 1.849) is used. And the second
In the first specific example of the embodiment, in the polarization beam splitter shown in FIG. 20, as the antireflection film 14 formed on the slope of the prism member 12, as shown in FIG. 21, aluminum oxide (Al ₂ O ₃ : A dielectric material is formed by alternately laminating a total of six layers each having a thickness shown in FIG. 21 on a layer made of a refractive index n = 1.62 and a layer made of silicon dioxide (SiO ₂ : refractive index n = 1.47). Using a multilayer film, the prism member 11
24, titanium dioxide (TiO ₂ : refractive index n = 2.2) as the polarization separation film 13 formed on the slope of FIG.
Layer and silicon dioxide (SiO ₂ : refractive index n = 1.4)
24) and a dielectric multilayer film in which a total of 19 layers each having the film thickness shown in FIG. 24 are alternately laminated, and an adhesive disposed between the antireflection film 14 and the polarization separation film 13 is used. Fifteen
As a commercially available optical adhesive (refractive index 1.52, film thickness 1
0 micron). The polarization splitting film 13 shown in FIG. 24 is configured for B light for 52-degree incidence. FIG. 21 is a schematic cross-sectional view schematically illustrating an example of the antireflection film 14, and FIG. 24 is a schematic cross-sectional view schematically illustrating an example of the polarization separation film 13.

A ninth comparative example, which is compared with the first specific example of the second embodiment, is a polarization beam splitter according to the first specific example of the second embodiment. And the other configuration is the same as that of the first specific example of the second embodiment.

The tenth comparative example is obtained by removing the polarization separation film 13 and the antireflection film 14 from the polarization beam splitter according to the first example of the second embodiment. Are the same as those in the first specific example of the second embodiment.

Further, the eleventh comparative example corresponds to FIG.
In the polarization beam splitter according to the first specific example of the second embodiment, only the antireflection film 14 is removed to obtain the same configuration as the conventional polarization beam splitter shown in FIG. This is the same as the first specific example of the second embodiment.

FIG. 22 shows the characteristics of the polarizing beam splitter according to the ninth comparative example when the P-polarized light is made incident at an incident angle of 52 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 11 and 12. FIG. FIG. 23 is a diagram showing characteristics of the polarizing beam splitter according to the tenth comparative example when P-polarized light is incident at an incident angle of 52 degrees with respect to the bonding surfaces (inclined surfaces) of the prism members 11 and 12. It is.

As can be understood from the comparison between FIG. 22 and FIG. 23, when the anti-reflection film 14 is provided when the polarization separation film 13 is not provided, the anti-reflection film 1 is provided over the entire wavelength range.
4, the reflectance of P-polarized light is reduced (that is, the transmittance is increased), and the characteristics are greatly improved.

FIG. 25 shows the first concrete example of the second embodiment in the case where the P-polarized light is made incident at an incident angle of 52 degrees with respect to the bonding surface (slope) of the prism members 11 and 12. It is a figure showing the characteristic of the polarization beam splitter for B lights by an example. On the other hand, FIG. 26 shows the characteristics of the polarizing beam splitter according to the eleventh comparative example when the P-polarized light is made incident on the bonding surfaces (slope surfaces) of the prism members 11 and 12 at an incident angle of 52 degrees. FIG.

As can be seen from a comparison between FIG. 25 and FIG. 26, the polarization beam splitter for B light according to the first specific example of the second embodiment has a B light wavelength region (400 nm).
m to 500 nm), the reflectance of the P-polarized light is reduced (ie, the transmittance is increased) and the characteristics are greatly improved, as compared with the eleventh comparative example in which the antireflection film 14 is not provided. I have.

As in the case of the second and third specific examples of the first embodiment, in the polarization beam splitter according to the first specific example of the second embodiment,
As the polarization separating film 13 formed on the inclined surface of the prism member 11, a dielectric multilayer film for G light or R light (not shown) is used instead of the dielectric multilayer film for B light shown in FIG. Needless to say, a polarization beam splitter for G light or R light according to another specific example of the second embodiment can be obtained.

As can be seen from the above description of the specific example, the polarization beam splitter according to the second embodiment also includes the antireflection film 14 in addition to the polarization separation film 13 and the adhesive 15 And the anti-reflection film 4, it is possible to obtain an ideal polarization separation characteristic as compared with the conventional polarization beam splitter, and to obtain a desired polarization light transmittance or reflectance of 0% or It can be closer to 100%.

In the polarizing beam splitter according to the first specific example of the second embodiment, if an adhesive having a refractive index of 1.41 is used as the adhesive 15, FIG.
When P-polarized light is incident on the anti-reflection film 14 at an incident angle of 52 degrees into the polarization beam splitter from the direction of the arrow, the adhesive 15 is formed no matter how the anti-reflection film 14 is formed.
, Total reflection occurs due to the relationship between the refractive indices, and cannot function as a polarizing beam splitter.

In the description so far, the characteristics of the light incident on the polarizing beam splitter at the predetermined angle of incidence from the antireflection films 4 and 14 are discussed. In each specific example of the embodiment, the incident light may be incident from the polarization separation films 3 and 13 side. Also in this case, the reflection characteristics and the transmission characteristics are the same as those when the light enters from the antireflection films 4 and 14 of the polarization beam splitter.

[Third Embodiment] Next, a third embodiment of the present invention will be described.
The projection type display according to the embodiment will be described with reference to FIG. The projection display device according to the present embodiment is an example of the projection display device using the polarization beam splitter according to the first embodiment shown in FIG. 1 described above.

FIG. 27 is a schematic configuration diagram showing a projection type display device according to the present embodiment. For convenience of explanation, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined as shown in the drawing.

The projection type display according to the present embodiment is a projection type display configured to use a cross dichroic mirror 33 and a cross dichroic prism 37 as a color separation optical system and a color synthesis optical system, respectively. With this configuration, the above-described polarization beam splitters 35R, 35G, and 35B shown in FIG. 1 are arranged for each of the separated R, G, and B lights.

In the projection type display device according to the present embodiment,
As shown in FIG. 27, a white light source light emitted from a light source (not shown) traveling in the Y direction includes a B light reflecting dichroic mirror 33B and an R light reflecting dichroic mirror 33R.
Are incident on the color separation optical system composed of the cross dichroic mirror 33, which intersects at right angles to each other, so that the incident angle is 45 degrees with respect to each of the mirrors 33B and 33R. The white light source light incident on the cross dichroic mirror 33 is a red light (R
), Blue light (B light) traveling in the X direction, and green light (G light) traveling through the cross dichroic mirror 33 and traveling in the Y direction.

The R light, G light, and B light separated by the cross dichroic mirror 33 are
At R, 34G, and 34B, the optical axis is changed to the Z direction, respectively.
Polarizing beam splitters 35R, 35G, 35 for each color light
B.

In the present embodiment, the polarization beam splitters 35R, 35G, 35B are arranged such that the S-polarized light enters the reflection type light valves 36R, 36G, 36B.

As the polarization beam splitter 35R for R light, for example, the polarization beam splitter according to the third specific example of the first embodiment described above is used, and as the polarization beam splitter 35G for G light, for example, the first polarization beam splitter 35G described above is used. The polarization beam splitter according to the second specific example of the embodiment is used, and the polarization beam splitter according to the first specific example of the above-described first embodiment is used as the polarization beam splitter 35B for B light, for example.

Further, for example, as the polarizing beam splitter 35R for the R light, the light transmitting material constituting the prism members 1 and 2 in the first embodiment is replaced by the sample N shown in Table 1.
o. The polarizing beam splitter using the sample No. 7 in Table 1 was used as the polarizing beam splitter 35G for G light in the first embodiment in the light transmitting material forming the prism members 1 and 2 in the first embodiment. In the first embodiment, the polarizing beam splitter 35B for B light is used as the polarizing beam splitter using the sample No. 6 in Table 1 as the light transmitting material forming the prism members 1 and 2 in the first embodiment. 4 may be used. That is, as can be understood from the data in Table 1, a material having the smallest absolute value of the photoelastic constant may be arranged in the wavelength region of each color light.
By doing so, each polarization beam splitter 35R,
Since the photoelastic constant can be minimized for each color light incident on 35G and 35B, birefringence can be minimized, which is more preferable. In this case, the structures of the polarization beam splitters 35R, 35G, and 35B are as shown in FIG. 1. However, since the refractive index of each translucent material is different, the configuration of the antireflection film 4 and the polarization separation film 3 is different. The thickness and the film thickness are designed and manufactured according to the respective wavelengths.

The polarization beam splitters 35R, 35G, 3
Each of the color lights incident on the 5B in the Z direction is a random polarization light in terms of polarization, and each of the polarization beam splitters 35B.
The R, 35G, and 35B reflect the S-polarized light reflected by the polarization separation films of the polarization beam splitters 35R, 35G, and 35B and enter the reflection type light valves 36R, 36G, and 36B, and the polarization beam splitters 35R and 35B.
The light is polarized and separated into P-polarized light that passes through the G and 35B polarization separation films and is discarded.

The S-polarized R light, G light, and B light incident on the light valves 36R, 36G, and 36B, respectively, are modulated and reflected by the image signals for the respective colors, and are reflected as modulated lights, respectively, to form the respective light valves 36R, 36G. , 36B, and again, the polarization beam splitters 35R, 35G, 3
5B. In the modulated light of each color, P-polarized light at a position selected according to the image signal for each color and S-polarized light at a non-selected position are mixed. The modulated light that has entered the polarization beam splitters 35R, 35G, and 35B respectively receives the modulated light.
The light is analyzed by 35G and 35B, respectively. That is,
Only the P-polarized light of the modulated light of each color passes through the polarization splitting films of the polarization beam splitters 35R, 35G, and 35B, and the cross dichroic prism 37 as a color combining optical system.
(That is, analyzed), and the S-polarized light of the modulated light of each color is converted into the polarized beam splitters 35R and 35R.
The light is reflected by the polarization separation films of G and 35B and is discarded in the -Z direction.

The polarization beam splitters 35R, 35G,
The detection light of each color emitted from 35B is bent by a bending mirror 34R, 34G, 34B of each color light separated by the cross dichroic mirror 33 as the color separation optical system.
The light exits in the direction opposite to the direction of incidence on the color, and enters the color combining optical system composed of the cross dichroic prism 37.

The cross dichroic prism 37 is composed of R light reflecting dichroic films 37R formed on each side surface and B light
It has a structure in which four right-angled isosceles triangular prisms are bonded together with an adhesive so that the light reflecting dichroic film 37B is orthogonal to each other to form an X-shape.

The analysis light of the R light emitted from the polarization beam splitter 35R in the X direction and incident on the cross dichroic prism 37 is reflected by the R light reflecting dichroic film 37R, changes the optical axis to the −Y direction, and changes the optical axis to the -Y direction. It is emitted in the −Y direction from 37. The analysis light of B light emitted from the polarizing beam splitter 35B in the −X direction and incident on the cross dichroic prism 37 is reflected by the B light reflecting dichroic film 37B, changes the optical axis to the −Y direction, and It is emitted in the -Y direction.
The analysis light of G light emitted from the polarizing beam splitter 35G in the −Y direction and incident on the cross dichroic prism 37 passes through the dichroic films 37R and 37G,
The light is directly emitted from the prism 37 in the −Y direction.

As described above, the light valve 36 for each color light
The analysis light of each color light which has been modulated by the R, 36G, 36B and analyzed by the polarization beam splitters 35R, 35G, 35B is color-combined by a cross dichroic prism 37, and the combined light is cross-dichroic. Prism 3
7 is emitted in the −Y direction. Then, the synthesized light emitted from the cross dichroic prism 37 is incident on a projection lens (not shown) as a projection optical system, and is projected as a full-color projection image on a screen (not shown).

According to the present embodiment, the polarizing beam splitters 35R, 35G, and 35B according to the above-described first embodiment in which the transmittance of P-polarized light is greatly improved are used. This provides an effect of projecting a projected image having high luminance, high contrast, and excellent color reproduction.

The polarization beam splitter 3 for each color light is used.
5R, 35G, 35B, the light transmitting material of the prism member is 1
No. 2 to N in Table 1
It is preferable to use the material of o6. Because, as shown in FIG. 3, the characteristics of the wavelength and the photoelastic constant of each material pass through a substantially zero position at a wavelength that minimizes the photoelastic constant of each material, and the photoelastic constant increases as the wavelength increases. Is large and has upwardly convex characteristics.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described.
The projection type display device according to the embodiment will be described with reference to FIGS. 28 and 29. FIG. The projection display device according to the present embodiment is an example of the projection display device using the polarization beam splitter according to the second embodiment shown in FIG.

FIG. 28 is a schematic diagram showing a projection type display device according to the present embodiment. For convenience of explanation, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined as shown in the drawing. FIG. 29 is a diagram of the optical system for the B light in FIG. 28 as viewed in the −Y direction. 28 and 29,
Elements that are the same as or correspond to the elements in FIG. 27 are given the same reference numerals, and redundant description is omitted.

The projection type display device according to the present embodiment is shown in FIG.
7 is basically different from the projection type display device according to the third embodiment shown in FIG. 7 in this embodiment, in which the polarization beam splitters 35R, 35G, and 35B are the same as those in FIG.
0 is used in the polarization beam splitter according to the second embodiment.

As the polarization beam splitter 35B for B light, for example, the polarization beam splitter according to the first specific example of the above-described second embodiment is used, and as the polarization beam splitter 35G for G light, for example, the second polarization beam splitter 35G described above is used. In the polarization beam splitter according to the first specific example of the embodiment, a polarization beam splitter employing a dielectric multilayer film for G light is used as the polarization separation film 13, and the polarization beam splitter 35R for R light may be used, for example, as described above. In the polarization beam splitter according to the first specific example of the second embodiment, a polarization beam splitter using a dielectric multilayer film for R light as the polarization separation film 13 is used.

Therefore, in the present embodiment, in order to make each color light incident on the antireflection film and the polarization splitting film of the polarization beam splitters 35R, 35G, and 35B at an incident angle of 52 degrees, FIGS. As shown in the figure, the respective color lights from the cross dichroic mirror 33 are arranged to be incident on the bending mirrors 34R, 34G, and 34B at an incident angle of 52 degrees.

In the present embodiment, the B light that has been color-separated by the cross dichroic mirror 33 travels in the X direction, is incident on the bending mirror 34B at an incident angle of 52 degrees, is reflected, and is reflected by the polarization beam splitter 35B. The light is incident on the polarization splitting film of the polarization beam splitter 35B at an incident angle of 52 degrees. The S-polarized light of the B light polarized and separated by the polarized light separating film travels in the X direction, exits the polarized beam splitter 35B, and is reflected by the reflective light valve 3.
6B. The modulated light of the B light modulated by the light valve 36B is again transmitted to the polarization beam splitter 35B.
And enters the polarization beam splitter 35B at an incident angle of 52 degrees with respect to the polarization beam splitting film, and is subjected to light analysis by the polarization beam splitting film. The detection light (P-polarized light) of the B light travels in the −X direction and is incident on the cross dichroic prism 37 as a color combining optical system, and the R light obtained in the same manner as the B light described above. Light analysis and G
The color is combined with the light analysis light.

The same advantages as those of the projection type display device according to the third embodiment can be obtained by the projection type display device according to the present embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, the polarizing beam splitter according to the present invention can be used in various optical devices other than the projection display device.

[0126]

As described above, according to the present invention,
It is possible to provide a polarization beam splitter that can obtain ideal polarization separation characteristics as compared with a conventional polarization beam splitter.

Further, according to the present invention, there is provided a projection type display device which can achieve high luminance without increasing the output of a light source and can improve the contrast of a projected image. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a polarizing beam splitter according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the content of PbO in a light-transmitting material used for a polarization beam splitter and the wavelength of light at which the absolute value of the photoelastic constant of the material becomes a minimum.

FIG. 3 is a diagram showing the wavelength dependence of the photoelastic constant of various translucent materials used for the polarization beam splitter.

FIG. 4 is a schematic cross-sectional view schematically showing one example of an antireflection layer of the polarizing beam splitter according to the first embodiment of the present invention.

FIG. 5 is a schematic sectional view schematically showing another example of the antireflection layer of the polarization beam splitter according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating characteristics of a polarizing beam splitter according to first and second comparative examples.

FIG. 7 is a diagram illustrating characteristics of polarization beam splitters according to sixth and seventh comparative examples.

FIG. 8 is a schematic cross-sectional view schematically illustrating an example of a polarization splitting film of the polarization beam splitter according to the first embodiment of the present invention.

FIG. 9 is a diagram showing characteristics of the polarization beam splitter according to the first specific example of the first embodiment of the present invention.

FIG. 10 is a diagram illustrating characteristics of a polarization beam splitter according to a third comparative example.

FIG. 11 is a schematic cross-sectional view schematically showing another example of the polarization splitting film of the polarization beam splitter according to the first embodiment of the present invention.

FIG. 12 is a diagram illustrating characteristics of a polarization beam splitter according to a second specific example of the first embodiment of the present invention.

FIG. 13 is a diagram illustrating characteristics of a polarization beam splitter according to a fourth comparative example.

FIG. 14 is a schematic sectional view schematically showing still another example of the polarization beam splitting film of the polarization beam splitter according to the first embodiment of the present invention.

FIG. 15 is a diagram illustrating characteristics of a polarization beam splitter according to a third specific example of the first embodiment of the present invention.

FIG. 16 is a diagram illustrating characteristics of a polarization beam splitter according to a fifth comparative example.

FIG. 17 is a schematic sectional view schematically showing still another example of the polarization beam splitting film of the polarization beam splitter according to the first embodiment of the present invention.

FIG. 18 is a diagram illustrating characteristics of a polarization beam splitter according to a fourth example of the first embodiment of the present invention.

FIG. 19 is a diagram illustrating characteristics of a polarization beam splitter according to an eighth comparative example.

FIG. 20 is a schematic sectional view showing a polarization beam splitter according to a second embodiment of the present invention.

FIG. 21 is a schematic cross-sectional view schematically illustrating an example of a polarization beam splitting film of a polarization beam splitter according to a second embodiment of the present invention.

FIG. 22 is a diagram illustrating characteristics of a polarization beam splitter according to a ninth comparative example.

FIG. 23 is a diagram illustrating characteristics of a polarizing beam splitter according to a tenth comparative example.

FIG. 24 is a schematic sectional view schematically showing an example of a polarization beam splitting film of a polarization beam splitter according to a second embodiment of the present invention.

FIG. 25 is a diagram illustrating characteristics of the polarizing beam splitter according to the first specific example of the second embodiment of the present invention.

FIG. 26 is a diagram illustrating characteristics of a polarization beam splitter according to an eleventh comparative example.

FIG. 27 is a schematic configuration diagram showing a projection display device according to a third embodiment of the present invention.

FIG. 28 is a schematic configuration diagram showing a projection display device according to a fourth embodiment of the present invention.

FIG. 29 is a view of the optical system related to B light in FIG. 28 as viewed in the −Y direction.

FIG. 30 is a schematic sectional view schematically showing a conventional polarization beam splitter.

FIG. 31 is a schematic configuration diagram showing a conventional projection display device.

[Explanation of symbols]

 1,2,11,12 Prism member 3,13 Polarization separating film 4,14 Antireflection film 5,15 Adhesive layer

Claims (5)

[Claims] 1. A polarizing beam splitter having first and second prism members joined by an adhesive with a polarization separating film interposed therebetween, wherein a surface of the first prism member facing the second prism member is provided. The polarization splitting film is formed, an antireflection film is formed on a surface of the second prism member facing the first prism member, and the adhesive is between the polarization splitting film and the antireflection film. A polarizing beam splitter, wherein: 2. The polarization beam splitter according to claim 1, wherein the first and second prism members are made of a translucent material having a refractive index of 1.80 or more. 3. The first and second prism members have an absolute value of a photoelastic constant of 1.5 × 10 ⁻⁸ cm ² / N or less with respect to light of a predetermined wavelength incident on the polarization beam splitter. 2. A light-transmitting material.
Or the polarizing beam splitter according to 2. 4. A polarization beam splitter, a light valve, and a projection optical system, wherein the polarization beam splitter separates light from a light source into two polarized lights, and the light valve is a polarization beam splitter. The polarization beam splitter modulates one polarized light, the polarization beam splitter detects light modulated by the light valve, and the projection optical system projects light detected by the polarization beam splitter. 4. A projection display device, wherein the polarization beam splitter according to claim 1 is used as the polarization beam splitter. 5. A color separation optical system for separating light from a light source into R light, G light and B light, first, second and third light valves, and color separation by the color separation optical system. A first, a second, and a third polarization beam splitters provided corresponding to the respective color lights, a color combining optical system, a projection optical system,
The first, second, and third polarization beam splitters respectively separate each color light color-separated by the color separation optical system into two polarization lights, and the first, second, and third polarization beam splitters. The third light valve is the first light valve.
The first, second, and third polarization beam splitters respectively modulate one of the color lights separated by the second and third polarization beam splitters, and the first, second, and third polarization beam splitters respectively. 3, the color light modulated by the light valve of No. 3 is detected, and the color synthesizing optical system performs color synthesis on the color light detected by the first, second, and third polarization beam splitters, The polarization beam splitter according to any one of claims 1 to 3, wherein the projection optical system projects light that has been color-combined by the color composition optical system, and serves as the first, second, and third polarization beam splitters. A projection display device, wherein each of them is used.