JP2000147246A - Optical element and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reducion of contrast due to black floating and to make it possible to display a high-quality display image by applying the optical element to a projector device for projecting image light spatially modulated by a reflection type liquid crystal panel e.g. to a screen, a polarized beam splitter to be used for the projector device and a dichromic mirror. SOLUTION: A polarized beam splitter 28R (28G, 28B) to be an optical element is constituted so as to selectively transmit or reflect incident light transmitted through transparent optical blocks 31, 32 by a dielectric multi-layer film 34 formed between the blocks 31, 32. A transparent plate material 33 consisting of a parallel plate forming the multi-layer film 34 is arranged between the blocks 31, 32 and a space between the blocks 31, 32 holding the film 34 between them is filled with a translucent liquid 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and a projection type display device, for example, a projector device for projecting image light spatially modulated by a reflection type liquid crystal panel onto a screen, a polarizing beam splitter used in the projector device, It can be applied to a dichroic prism. The present invention, by arranging a transparent plate material of a parallel plate formed with a dielectric multilayer film between transparent optical blocks,
Further, by filling a transparent liquid between the transparent optical blocks sandwiching the dielectric film multilayer film, a projection type display device prevents a decrease in contrast due to floating black and displays a high-quality display image. Be able to do it.

[0002]

2. Description of the Related Art Conventionally, in a projection type display device, spatially modulated image light is generated using a reflection type liquid crystal panel, and the image light is projected on a screen so that a desired color image can be formed. What was done is proposed.

FIG. 4 is a schematic diagram showing this type of projection display device. In the projection display device 1,
The light source 2 includes, for example, a discharge lamp 3 and a reflector 4, and emits illumination light of white light. Convex lens 5
Converts the illumination light emitted from the light source 2 into a substantially parallel light flux and emits it. The mirror 6 reflects the illumination light emitted from the convex lens 5 and bends the optical path by 90 degrees, and the convex lens 7 makes the light emitted from the mirror 6 enter the polarization beam splitter 8.

Here, the polarizing beam splitter 8 is formed by bonding the inclined surfaces of a right-angle prism, which is a transparent optical member, and an analysis surface made of a dielectric multilayer film is formed on the bonded surface. The polarization beam splitter 8 selectively transmits and reflects the incident light according to the polarization component by using the analysis surface. That is, the polarizing beam splitter 8 is
Of the incident illumination light, the P-polarized light component is transmitted, while the S-polarized light component LS is reflected and emitted to the dichroic prism 9. The polarization beam splitter 8 reflects the S-polarized light component of the image light incident from the dichroic prism 9 side and emits it, while transmitting the P-polarized light component LP and emits it to the projection lens 11.

The subsequent dichroic prism 9 is formed using three prisms, which are transparent optical members processed into a predetermined shape, so that the bonding surface sequentially crosses the optical path of incident light. In the dichroic prism 9, a dielectric multilayer film is formed on these bonding surfaces, and the dielectric multilayer film selectively transmits and reflects incident light according to the wavelength.

That is, the dichroic prism 9 selectively reflects the illumination light in the blue wavelength band from the illumination light incident from the polarization beam splitter 8 on the dielectric multilayer film formed on the bonding surface on the polarization beam splitter 8 side. , Transmitting the illumination light of the remaining wavelength band. The dichroic prism 9 guides the illumination light of the blue wavelength band reflected in this way to the reflective liquid crystal panel 10B for the blue wavelength band, and as a result, converts the image light of the blue wavelength band obtained from the reflective liquid crystal panel 10B to the dielectric liquid crystal panel 10B. Lead to body multi-layer film. The dichroic prism 9 reflects the image light in the blue wavelength band on the dielectric multilayer film and emits the image light to the polarization beam splitter 8.

Further, the dichroic prism 9 selectively reflects the illumination light in the red wavelength band from the remaining illumination light in the subsequent dielectric multilayer film, transmits the illumination light in the green wavelength band, and transmits the red and green wavelength bands, respectively. The illumination light of the wavelength band is emitted to the reflective liquid crystal panels 10R and 10G for the red wavelength band and the green wavelength band. In addition, the illumination light is emitted in this manner, and the image light in the red wavelength band and the green wavelength band obtained from the reflective liquid crystal panels 10R and 10G for the red wavelength band and the green wavelength band is reflected by the subsequent dielectric multilayer film. Then, the light is transmitted and enters the dielectric multilayer film on the polarization beam splitter 8 side, and the polarization beam splitter 8
The light passes through the dielectric multilayer film on the side and exits to the polarization beam splitter 8.

[0008] Reflective liquid crystal panels 10R, 10B, 10G
By spatially modulating incident illumination light with image light for each wavelength band by driving a drive circuit (not shown), the polarization plane is rotated with respect to the illumination light, and the image light is emitted to the dichroic prism 9. Thereby, the reflective liquid crystal panel 10R,
10B and 10G emit image light by combined light of P-polarized light and S-polarized light with respect to the illumination light incident by S-polarized light,
In the projection display device 1, the P-polarized light component of the image light thus emitted is changed to the polarization beam splitter 8.
Is transmitted.

The projection lens 11 projects the image light emitted from the polarization beam splitter 8 on a screen 12. As a result, in the projection display device 1, the images formed by the reflective liquid crystal panels 10R, 10G, and 10B are enlarged and projected on the screen 12, so that a desired color image can be displayed.

[0010]

By the way, in this type of projection type display device 1, black is displayed with white floating (so-called black floating), and the contrast is sufficiently ensured in the displayed image on the screen. There was a problem that could not be done.

That is, in the polarization beam splitter 8, the transmitted light and the reflected light should emit linearly polarized light due to the P-polarized light and the S-polarized light due to the analysis surface of the dielectric multilayer film.

However, the right-angle prism constituting the polarizing beam splitter has a birefringent property, whereby reflected light and transmitted light which are originally emitted as linearly polarized light are emitted as elliptically polarized light. That is, in the reflected light and the transmitted light, light having a polarization plane orthogonal to the intended polarization plane is included. In addition, light incident by linearly polarized light is analyzed by elliptically polarized light, and a portion of light that is originally transmitted or reflected is reflected or transmitted by the opposite way and emitted. .

Also in the dichroic prism 9, since each prism has birefringence, the illuminating light emitted from the polarizing beam splitter 8 as elliptically polarized light is further birefringent, and each reflection type liquid crystal panel 10R,
10G and 10B, and each reflective liquid crystal panel 10
The image light obtained from R, 10G, and 10B is birefringent and emitted to the polarization beam splitter 8.

Looking at this with respect to the image light, the light is emitted from the reflection type liquid crystal panels 10R, 10G, and 10B as a combined light of P-polarized light and S-polarized light, and only the P-polarized light component should originally enter the projection lens 11. Of the S-polarized light component that has not been spatially modulated at all,
2 will be projected.

As for the illumination light, the component of the P polarization plane orthogonal to the S polarization plane which is spatially modulated by the reflection type liquid crystal panels 10R, 10G, and 10B leaks, The leaked illumination light is projected on the screen 12 as it is.

As a result, in the projection display device 1, black floating occurs. If such black floating occurs unevenly, the uniformity (uniformity) of the displayed image in the projection display device 1 is deteriorated.

The present invention has been made in view of the above points, and is directed to a projection-type display device capable of displaying a high-quality display image by improving contrast, and an optical element applied to such a device. It is something to propose.

[0018]

According to the present invention, there is provided an optical device for selectively transmitting and reflecting incident light transmitted through a transparent optical block by a dielectric multilayer film formed between the transparent optical blocks. Applying to the element, a transparent plate of a parallel flat plate is disposed between the transparent optical blocks, and a dielectric multilayer film is formed on the transparent plate.

In a similar optical element, a transparent liquid is filled between transparent optical blocks sandwiching a dielectric multilayer film.

Further, in a projection display device, these configurations are applied to a polarizing beam splitter and a dichroic prism.

By disposing a parallel flat transparent plate between the transparent optical blocks and forming a dielectric multilayer film on the transparent plate,
The initial stress generated when the dielectric multilayer film is formed can be reduced as compared with the case where the dielectric multilayer film is formed directly on the transparent optical block. So overall,
Birefringence due to the optical member on the optical path can be reduced.

In a similar optical element, when a transparent liquid is filled between transparent optical blocks sandwiching a dielectric multilayer film, a transparent optical block is bonded as compared with a case where the transparent optical block is bonded with an optical adhesive. The initial stress can be reduced. Therefore, the birefringence due to the optical member on the optical path can be reduced accordingly.

With these arrangements, in the projection type display device, these structures can be applied to the polarizing beam splitter and the dichroic prism to reduce the floating of black, thereby improving the contrast and displaying a high quality display image. be able to.

[0024]

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

(1) First Embodiment (1-1) Overall Configuration of First Embodiment FIG. 2 is a schematic diagram showing a projection display apparatus according to a first embodiment of the present invention. It is. In the projection display device 21, the same components as those described above with reference to FIG. 4 are denoted by the corresponding reference numerals, and redundant description will be omitted.

In the projection display device 21, the color separation mirror 22 reflects the illumination light LB in the blue wavelength band and transmits the remaining illumination light on the optical path of the illumination light emitted from the convex lens 5. . The color separation mirror 23 reflects the illumination light LR in the red wavelength band and transmits the remaining illumination light LG in the green wavelength band on the optical path of the illumination light reflected by the color separation mirror 22. Thus, the projection display device 21 separates the illumination light emitted from the light source 2 into blue, red, and green illumination lights LB, LR, and LG.

Lens 24, mirror 25, lenses 26, 2
7B bends the optical path of the illumination light LB reflected by the color separation mirror 22, and guides it to the polarization beam splitter 28B. The polarization beam splitter 28B emits the S-polarized component of the illumination light LB incident from the lens 27B toward the reflective liquid crystal panel 10B, and transmits the P-polarized component. The polarizing beam splitter 28B is a reflection type liquid crystal panel 10B.
The illumination light is spatially modulated to transmit the P-polarized light component of the emitted image light and output to the color combining prism 30.

The polarizing beam splitter 28R is connected to the lens 2
The illumination light LR in the red wavelength band reflected by the color separation mirror 23 enters through the 7R, emits the S-polarized component toward the reflective liquid crystal panel 10R, and transmits the P-polarized component. Further, the polarizing beam splitter 28R is connected to the reflective liquid crystal panel 10R.
The illumination light LR is spatially modulated by R, and the P-polarized light component of the image light emitted is transmitted and emitted to the color combining prism 30.

Similarly, the polarizing beam splitter 28G
The illumination light LG in the green wavelength band transmitted through the color separation mirror 23 enters through the lens 27G, emits the P-polarized component toward the reflective liquid crystal panel 10G, and transmits the P-polarized component. Further, the polarization beam splitter 28G transmits the P-polarized light component of the image light emitted after spatially modulating the illumination light LG by the reflection type liquid crystal panel 10G and emits it to the color combining prism 30.

The color synthesizing prism 30 synthesizes the video light incident from the polarization beam splitters 28R, 28G, and 28B and emits it to the projection lens 11, whereby the projection display device 21 displays a desired color image. It has been made possible.

(1-2) Configuration of Polarizing Beam Splitter FIG. 1 shows these polarizing beam splitters 28R, 28G,
It is a top view showing the composition of 28B. Here, the polarization beam splitters 28R, 28G, and 28B have the same configuration except that the wavelength bands to be processed are different and the arrangement locations are different, so that the polarization beam splitter 28R will be described here. However, duplicate description will be omitted.

In the polarization beam splitter 28R, two right-angle prisms 31 and 32, which are transparent optical blocks, are arranged so that the slopes face each other, and a thin parallel plate transparent plate material 33 is arranged between the slopes. . This transparent plate 3
3, a dielectric multilayer film 34 is formed in advance. Note that this dielectric multilayer film 34 constitutes an analysis surface.

Thus, the polarization beam splitter 28R
Is to form a dielectric multilayer film directly on the right-angle prisms 31 and 32 to reduce the increasing initial stress of the right-angle prisms 31 and 32, and when viewed as a whole, the birefringence due to the formation of the dielectric multilayer film 34 The increase in volume is reduced.

The right-angle prisms 31 and 32 and the transparent plate 33 are made of a highly versatile glass material having a refractive index N of about 1.40 <N <1.85 and substantially the same refractive index. It is made by processing, and like a normal optical component, each surface is made by mirror polishing.

Right angle prisms 31 and 32, transparent plate 33
The mirror-polished surfaces are arranged so as to be in close contact with each other, and a gap between the closely-contacted surfaces due to the capillarity by dropping a light-transmissive liquid 35 is filled with the liquid 35, and the filled liquid 35 It cannot be easily separated due to the surface tension of the material. Thereby, the polarization beam splitter 2
8R is such that the right-angle prisms 31 and 32 and the transparent plate 33 are integrated by the liquid 35.

The polarizing beam splitter 28R includes, as such a liquid, for example, ethylene glycol, glycerin,
A right-angle prism 3 is formed from benzyl alcohol, silicon-based oil, or a mixed liquid having compatibility among these liquids.
Liquids having a refractive index substantially equal to 1 and 32 and the transparent plate 33 are selected. Thereby, the polarization beam splitter 28R
Is designed to effectively avoid the initial stress generated by the adhesion of the right-angle prism.

Further, the polarizing beam splitter 28R is thus provided with the right-angle prisms 31 and 32 and the transparent plate 33.
Is filled with a liquid 35, a resin such as a silicone resin or a wax, or a coating material is applied around the liquid 35 so that the liquid 35 does not evaporate. Here, the resin or the paint has a small adhesive force to simply prevent the liquid 35 from directly contacting the air, and furthermore, the resin or the paint has such a degree that the right-angle prisms 31 and 32 can sufficiently absorb deformation due to temperature and the like. In addition, a material having flexibility even when cured is applied.

(1-3) Operation of First Embodiment In the above configuration, the projection type display device 21 (FIG. 2)
The reflective liquid crystal panels 10B, 10R, and 10G are driven by blue, red, and green color signals, respectively, and images corresponding to the blue, red, and green color signals are formed on the reflective liquid crystal panels 10B, 10R, and 10G, respectively. You. The projection display device 21 separates the illumination light emitted from the light source 2 into blue, red, and green wavelengths, and supplies the blue, red, and green wavelengths to the corresponding reflective liquid crystal panels 10B, 10R, and 10G. The polarization planes of the blue, red, and green illumination light are rotated by the image corresponding to the green color signal to generate image light, and the projection lens 11 selectively screens the P-polarized component of the image light. And a color display image is projected.

That is, the illumination light emitted from the light source 2 is
Through the color separation mirrors 22 and 23, the illumination light LB, LR, and LG are decomposed into blue, red, and green wavelength bands, and the blue, red, and green illumination light LB, LR and LG are incident on the polarization beam splitters 28B, 28R and 28G, respectively. Illumination light L of these blue wavelength band, red wavelength band, and green wavelength band
Here, B, LR, and LG respectively reflect the S-polarized component and selectively reflect the liquid crystal panels 10B, 10R, and 10G.
, The polarization plane is rotated and reflected according to the corresponding color signal, and image light of each wavelength band is generated by the combined light of the P-polarized light and the S-polarized light.

The image light in each of these wavelength bands traces the optical path of the illumination light in reverse, and the polarization beam splitter 28
B, 28R, and 28G, where the P-polarized light component is transmitted, enters the color combining prism 30, and is emitted from the color combining prism 30 to the projection lens 11. Thereby, each image light is projected on the screen via the projection lens 11, and a color image is projected on this screen.

In the projection display device 21 in which the optical paths of the illumination light and the image light are formed as described above, originally,
The polarization beam splitters 28B, 28R, and 28G illuminate linearly polarized illumination light by the S-polarized light components on
0B, 10R, and 10G, and among the image light emitted from the reflective liquid crystal panels 10B, 10R, and 10G as the combined light of the S-polarized light and the P-polarized light, only the P-polarized light component is polarized beam splitters 28B, 28R, and 28G. And projected on the screen. Accordingly, in the polarization beam splitters 28B, 28R, and 28G, the black portion that reflects the illumination light without rotating the polarization plane of the illumination light should not be projected on the screen.

However, the polarization beam splitter 28
S detected by the dielectric multilayer films of B, 28R and 28G
As for the polarized light component, when passing through the right-angle prism, the birefringence of the right-angle prism generates a P-polarized component.
0B, 10R, and 10G are reflected. Thereby, even in the black portion, the polarization beam splitters 28B, 28R, 2
Light is slightly projected on the screen by the birefringence of 8G.

Each of the reflective liquid crystal panels 10B, 10B
Even in the image light by the combined light of the S-polarized light and the P-polarized light emitted from R and 10G, the S-polarized light is generated by the birefringence of the right-angle prism until the light is incident on the right-angle prism of the polarization beam splitter and then on the analysis surface. The component is mixed with the P-polarized component, and the mixed component is projected on the screen. Accordingly, in the projection display device 21,
In the black portion, light is slightly projected on the screen, which causes floating of black and lowers the contrast.

In this embodiment, however, in each of the polarizing beam splitters 28B, 28R and 28G (FIG. 1), a dielectric multilayer film 34 is formed on a parallel flat transparent plate 33 disposed between the inclined surfaces of the right angle prisms 31 and 32. Is formed, the liquid 3 is formed without using an adhesive.
Since the right-angle prisms 31 and 32 and the transparent plate 33 are integrated by filling with 5, the amount of birefringence is reduced as compared with the related art, and the decrease in contrast due to floating black is prevented by that amount.

That is, from the cause of the occurrence of black floating described above,
If the degree of birefringence in the polarizing beam splitter can be reduced, the floating of black can be reduced accordingly. This birefringence occurs due to the stress inside the glass material, and can be determined by using the value of optical path length × photoelastic constant × stress indicating the distortion amount of the glass material as a guide.

Since the photoelastic constant is a constant value depending on the glass material, it is considered that this type of black floating can be reduced by managing the photoelastic constant. However, glass materials having a small photoelastic constant are not easily available and lack versatility.

Considering the stress, in this type of glass material, the stress is represented by thermal stress + initial stress + mounting stress. Here, the thermal stress is a stress that is displaced by a rise in the temperature of the glass material, and is generated in the projection display device 21 by a rise in temperature due to heat convection, heat conduction, loss of illumination light, and the like inside the set.

The initial stress F is a residual stress when the polarizing beam splitter 28R is formed, and is represented by the sum of the stresses f21, f22, f23, and f24 as shown by the following equation. The mounting stress is a stress applied to the polarization beam splitter by disposing the polarization beam splitter.

[0049]

(Equation 1)

Here, f21 is a residual stress when the glass material is hardened, and a stress f22 is a residual stress when the glass material is cut out and polished. These stresses f2
In the cases of 1 and f22, when the glass material is prepared, the time can be sufficiently reduced by controlling the annealing time and processing.

On the other hand, the stress f23 is a residual stress due to heat when the dielectric multilayer film is formed. In this embodiment, the stress f23 is
Instead of 1 and 32, it is generated by a parallel plate transparent plate material 33, which is significantly reduced as compared with the case where a dielectric multilayer film is formed directly on the slope of a right-angle prism.

That is, in the rectangular prism, the volume is larger than that of the transparent plate material 33 of the parallel flat plate, and the thickness is particularly large when viewed with reference to the slope, and further, because the thickness is not uniform, When a dielectric multilayer film is formed directly on a slope having a conventional configuration, heat causes a large residual stress.

On the other hand, the parallel plate transparent plate 33 is
The volume can be sufficiently reduced, and the thickness viewed with reference to the surface on which the dielectric multilayer film is formed can be reduced and made uniform. The stress f23 can be remarkably reduced.

The polarization beam splitters 28R, 28G, 2
In 8B, the amount of birefringence when viewed as a whole is reduced, and in the projection display device 21, the floating black is reduced accordingly.

In the case where the dielectric multilayer film is formed on a parallel flat plate instead of the inclined surface of the right-angle prism as described above,
It is also possible to improve the mass productivity at the time of forming the dielectric multilayer film.
Further, in the polarization beam splitter, the design characteristics of the dielectric multilayer film can be sufficiently exhibited.

On the other hand, the stress f24 is generated by the contraction of the adhesive at the time of bonding. In this embodiment, the right angle prisms 31 and 3 are used instead of the adhesive.
2. Since the right-angle prisms 31 and 32 and the transparent plate 33 are integrated by the liquid 35 filled in the gap between the transparent plates 33, they can be ignored.

This also allows the polarization beam splitter 28
In R, 28G and 28B, the amount of birefringence is reduced,
In the projection type display device 21, the floating of black is reduced accordingly.

In such a configuration, in the polarization beam splitters 28R, 28G, and 28B, the right-angle prisms 31 and 32, the transparent plate 33, and the liquid 35 are set to have substantially the same refractive index. Loss of illumination light and image light at the interface between them is effectively avoided, and thereby a bright image can be displayed.

At this time, by selecting the refractive index of the liquid 35 so as to substantially match the refractive index of the right-angle prisms 31, 32, etc., a highly versatile glass material can be applied to the right-angle prisms 31, 32, etc. It becomes possible.

Further, by applying a resin or paint having flexibility even when cured, stress is not applied to the right-angle prisms 31 and 32 and the like, so that the liquid 35 does not directly come into contact with air and evaporates. It is possible to display a high-contrast image stably over a long period of time.

(1-3) Effects of the First Embodiment According to the above configuration, each of the polarization beam splitters 28R,
In 28G and 28B, a transparent plate 33 of a parallel flat plate is disposed between the inclined surfaces of the right-angle prisms 31 and 32, and a dielectric multilayer film 34 is formed on the transparent plate 33, so that the liquid 35 can be formed without using an adhesive. By integrating the right-angle prisms 31 and 32 and the transparent plate material 33 by filling, the amount of birefringence in the polarizing beam splitter can be reduced as compared with the conventional case, and a decrease in contrast due to floating black can be prevented. Can be.

(2) Second Embodiment In the projection type display device according to this embodiment, FIG.
In the projection display device 1 described above, the polarization beam splitter having the configuration according to the first embodiment described above is applied instead of the polarization beam splitter 8. Thus, in this embodiment, the amount of birefringence in the polarizing beam splitter is reduced, and a decrease in contrast due to floating black is prevented.

Further, in this projection display device, a dichroic prism 49 shown in FIG. 3 is applied in place of the dichroic prism 9 in the projection display device 1 described above with reference to FIG.

Here, the dichroic prism 49
Is the distance between the opposing surfaces of the prisms 51 and 52, the prism 52
, And 53, transparent plate members 54 and 55 of a thin parallel plate are arranged between the opposing surfaces. Each transparent plate 54 and 55
Are formed beforehand with dielectric multilayer films 56 and 57, and the dielectric multilayer films 56 and 57 form a reflecting surface having wavelength selectivity.

Thus, the dichroic prism 49
Is designed such that the initial stress is reduced and the amount of birefringence is reduced as compared with the case where a dielectric multilayer film is formed directly on the prisms 51, 52 and 53.

The prisms 51, 52, 53, and the transparent plates 54, 55 are made by processing a highly versatile glass material having substantially the same refractive index, and each surface is mirror-polished similarly to ordinary optical components. It is made to be created.

Prisms 51, 52, 53, transparent plate 54
And 55 are arranged such that the mirror-polished surfaces are in close contact with each other, and are integrated by the translucent liquid 35 having substantially the same refractive index as the prism 51 and the like filled in these gaps.
Further, the liquid 35 is prevented from evaporating by a resin or a paint (not shown).

The prism 52 and the transparent plate member 54 are spaced apart from each other with a predetermined gap member 59 interposed therebetween to form an air layer 58 so that desired wavelength selection characteristics can be secured. It has been done.

According to the configuration shown in FIG. 3, in the dichroic prism, the prisms 51 and 52, the prism 5
By disposing parallel flat transparent plates 54 and 55 between 2 and 53 and forming dielectric multilayer films 56 and 57 on the transparent plates 54 and 55, the liquid 35 can be filled without using an adhesive. By integrating these prisms and the like, the amount of birefringence in the dichroic prism can be reduced as compared with the related art, and a decrease in contrast due to floating black can be prevented.

In addition to the dichroic prism,
By adopting the same configuration for the polarization beam splitter, it is possible to further prevent a decrease in contrast due to floating black.

(3) Other Embodiments In the above-described embodiment, a parallel plate transparent plate having a dielectric multilayer film formed thereon is disposed between transparent optical blocks, and the dielectric multilayer film is formed between the transparent optical blocks. A case has been described where a translucent liquid is filled between the transparent optical blocks sandwiched between to form a polarizing beam splitter and a dichroic prism. However, the present invention is not limited to this, and any configuration may be selected as necessary. It can also be applied in a specific way.

That is, even when a dielectric multilayer film is formed on a parallel plate transparent member, and this transparent plate member is disposed between transparent optical blocks and bonded by an optical adhesive, the amount of birefringence is reduced as compared with the conventional case. Accordingly, a decrease in contrast due to floating black can be prevented.

Even when a dielectric multilayer film is formed directly on a transparent optical block, and a transparent liquid is filled and integrated, the amount of birefringence can be reduced as compared with the case of integrating with an adhesive. It is possible to prevent a decrease in contrast due to floating black.

Further, in the above embodiment, the case where the polarizing beam splitter and the dichroic prism according to the present invention are applied to the projection type display device has been described.
The present invention is not limited to this, and can be widely applied to various optical devices.

[0075]

As described above, according to the present invention, a transparent plate made of a parallel flat plate having a dielectric multilayer film formed thereon is disposed between the transparent optical blocks, and the transparent optical block sandwiching the dielectric multilayer film therebetween. By filling the space with a translucent liquid, high-quality display images can be displayed in the projection display device while preventing a decrease in contrast due to floating black.

[Brief description of the drawings]

FIG. 1 is a plan view showing a polarization beam splitter applied to a projection display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a projection display device to which the polarization beam splitter of FIG. 1 is applied.

FIG. 3 is a plan view showing a dichroic prism applied to a projection display device according to a second embodiment.

FIG. 4 is a schematic diagram showing a conventional projection display device.

[Explanation of symbols]

1, 21 ... Projection display device, 8, 28B, 28G, 2
8R ... polarizing beam splitter, 9, 49 ... dichroic prism, 31, 32, 51, 52, 53 ... prism, 33, 54, 55 ... transparent plate material, 34, 56,
57: multilayer dielectric film, 35: liquid, 59: air layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshio Suzuki 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 2H048 FA01 FA11 FA23 FA24

Claims (12)

[Claims] 1. An optical element for selectively transmitting and reflecting incident light transmitted through said transparent optical block by means of a dielectric multilayer film formed between said transparent optical blocks, said transparent plate being a parallel flat plate between said transparent optical blocks. Wherein the dielectric multilayer film is formed on the transparent plate. 2. The transparent optical block according to claim 1, wherein a refractive index of said transparent optical block is substantially equal to a refractive index of said transparent plate material.
An optical element according to item 1. 3. An optical element for selectively transmitting and reflecting incident light passing through said transparent optical block by means of a dielectric multilayer formed between a plurality of transparent optical blocks, wherein said dielectric multilayer is interposed therebetween. An optical element, wherein a transparent liquid is filled between the transparent optical blocks. 4. The optical element according to claim 3, wherein a parallel flat transparent plate is disposed between the transparent optical blocks, and the dielectric multilayer film is formed on the transparent plate. 5. A reflection-type image forming means for spatially modulating illumination light having a predetermined polarization plane and emitting image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light, and projecting the image light. With the projection optical system and the dielectric multilayer film formed between the transparent optical blocks,
Of the illumination light emitted from the predetermined light source, the illumination light of a predetermined polarization component is emitted toward the reflection-type image forming means, and of the image light incident from the reflection-type image formation means, A polarizing beam splitter that emits a polarization component orthogonal to the polarization plane to the projection optical system, wherein the polarizing beam splitter has a parallel plate transparent plate disposed between the transparent optical blocks; A projection type display device, wherein a dielectric multilayer film is formed. 6. The transparent optical block according to claim 5, wherein a refractive index of said transparent optical block is substantially equal to a refractive index of said transparent plate material.
3. The projection display device according to 1. 7. A reflection-type image forming means for spatially modulating illumination light having a predetermined polarization plane and emitting image light obtained by rotating the polarization plane with respect to the polarization plane of the illumination light, and projecting the image light. With the projection optical system and the dielectric multilayer film formed between the transparent optical blocks,
Of the illumination light emitted from the predetermined light source, the illumination light of a predetermined polarization component is emitted toward the reflection-type image forming means, and of the image light incident from the reflection-type image formation means, A polarizing beam splitter that emits a polarization component orthogonal to the polarization plane to the projection optical system, wherein the polarizing beam splitter is a translucent liquid between the transparent optical blocks that sandwich the dielectric multilayer film. A projection type display device characterized by being filled with. 8. The projection type display device according to claim 7, wherein a parallel flat transparent plate is disposed between the transparent optical blocks, and the dielectric multilayer film is formed on the transparent plate. 9. A plurality of reflection-type image forming means for spatially modulating incident light with a video signal for a predetermined wavelength band and emitting video light obtained by rotating a polarization plane with respect to a polarization plane of the incident light. With the dielectric multilayer film arranged between the transparent optical blocks,
An illumination light emitted from a predetermined light source is selectively emitted to the plurality of reflection-type image forming means in accordance with a wavelength, and the image light incident from the plurality of reflection-type image formation means is transmitted along an optical path of the illumination light. A dichroic prism that emits light so as to trace back, a projection optical system that projects the image light, and a dielectric multilayer film disposed between transparent optical blocks,
A polarizing beam splitter that emits the illumination light emitted from the light source toward the dichroic prism and emits a predetermined polarization component of the image light incident from the dichroic prism to the projection optical system. The polarizing beam splitter and / or the dichroic prism, wherein a transparent plate material of a parallel flat plate is disposed between the transparent optical blocks, and the dielectric multilayer film is formed on the transparent plate material. . 10. The projection display device according to claim 9, wherein a refractive index of said transparent optical block is substantially equal to a refractive index of said transparent plate. 11. A plurality of reflection-type image forming means for spatially modulating incident light with a video signal for a predetermined wavelength band and emitting video light obtained by rotating a polarization plane with respect to a polarization plane of the incident light. With the dielectric multilayer film arranged between the transparent optical blocks,
An illumination light emitted from a predetermined light source is selectively emitted to the plurality of reflection-type image forming means in accordance with a wavelength, and the image light incident from the plurality of reflection-type image formation means is transmitted along an optical path of the illumination light. A dichroic prism that emits light so as to trace back, a projection optical system that projects the image light, and a dielectric multilayer film disposed between transparent optical blocks,
A polarizing beam splitter that emits the illumination light emitted from the light source toward the dichroic prism and emits a predetermined polarization component of the image light incident from the dichroic prism to the projection optical system. The polarizing beam splitter and / or the dichroic prism are filled with a translucent liquid between the transparent optical blocks sandwiching the dielectric multilayer film. 12. The projection type display device according to claim 11, wherein a parallel plate transparent plate is disposed between the transparent optical blocks, and the dielectric multilayer film is formed on the transparent plate.