JPH09127317A - Dichroic prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a wavelength selective reflection layer of four layers and to reduce cost by sticking a surface where the wavelength selective reflection layer is formed to a surface where the wavelength selective reflection layer is not formed with adhesive. SOLUTION: The 1st and the 2nd wavelength selective reflection layers 5 and 6 are formed on two surfaces interposing the right angle of a 1st rectangular prism 1 by vapor deposition or sputtering. The reflection layers 5 and 6 are formed of a dielectric multilayer film, and obtain wavelength selective reflection layer characteristic by alternately laminating several ten layers of TiO2 and SiO2 thin films. The 1st reflection layer 5 is formed on one of two surfaces interposing the right angle of a 2nd rectangular prism 2, and the 2nd reflection layer 6 is formed on one of two surfaces interposing the right angle of a 3rd rectangular prims 3 by vapor deposition, etc. Thus, four rectangular prisms are stuck and the reflection layers 5 and 6 are made orthogonal to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dichroic prism for color separation and color synthesis of visible light and a projection color display device using the dichroic prism.

[0002]

2. Description of the Related Art A conventional dichroic prism is shown in FIG.
As shown in Fig. 4, a right angle prism having a first wavelength selective reflection layer and a second wavelength selective reflection layer on each of two surfaces sandwiching a right angle
Two pieces of a right-angle prism having a first wavelength selective reflection layer on one of two surfaces sandwiching a right angle as shown in FIG. 5 and a second wavelength selective reflection layer similarly. There was one in which two right-angle prisms were laminated alternately.

[0003]

However, according to the above-mentioned technique, in the former, the number of vapor deposition surfaces for forming the wavelength selective reflection layer is eight, and the manufacturing cost is high. In the latter, there are light that is incident on the dichroic prism that is directly reflected by the wavelength-selective reflection layer and light that passes through the adhesive used for bonding and then is reflected by the wavelength-selection reflection layer. , The color is changed, and in the case of the projection optical system, the lens is used, so that the focus is shifted or overlapped. Therefore, the present invention solves such a problem, and an object of the present invention is to provide a wavelength-selective reflection layer with four surfaces, reduce the cost, and use the wavelength-selective reflection layer to guide light incident on a dichroic prism. An object of the present invention is to provide a dichroic prism for color separation and color synthesis, which is directly reflected and does not cause discoloration or defocusing.

[0004]

According to the present invention, firstly, the surfaces of the four right-angle prisms that sandwich the right angle are bonded together by an adhesive so that the wavelength selective reflection layer has a substantially cross shape. In the dichroic prism, the two surfaces that sandwich the right angle of the first right-angled prism have the first
Forming two wavelength selective reflection layers and a second wavelength selective reflection layer, and sandwiching the right angle of the second rectangular prism, the first wavelength selective reflection layer is formed on one surface and the other surface is formed on the other surface. No wavelength selective reflection layer is formed on one surface, and two surfaces sandwiching the right angle of the third rectangular prism are provided with a second wavelength selective reflection layer on one surface and a wavelength selective surface on the other surface. No reflective layer is formed,
A wavelength selective reflection layer is not formed on the two right-angled surfaces of the fourth right-angled prism, and the two right-angled prisms adjacent to the right-angled surfaces of the four right-angled prisms are the first right-angled prisms.
The surface on which the wavelength selective reflection layer is formed and the surface on which the wavelength selective reflection layer is not formed are bonded together by the adhesive so that the wavelength selective reflection layer and the second wavelength selective reflection layer are orthogonal to each other. It is characterized by

Secondly, a plurality of liquid crystal light valves for respectively modulating a plurality of color lights, a dichroic prism for combining the color lights modulated by the plurality of liquid crystal light valves, and the light combined by the dichroic prisms are projected. In the projection color display device, the dichroic prism having the first characteristic is used as the dichroic prism, and the dichroic prism having the second characteristic, the third right angle prism, and the fourth right angle prism are provided with the plurality of dichroic prisms. The colored light from the liquid crystal light valve is incident, and the combined light is emitted from the first rectangular prism to the projection lens.

[0006]

According to the above construction of the present invention, the manufacturing cost can be significantly reduced and the performance of the dichroic prism can be sufficiently enhanced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the structure of a dichroic prism according to the present invention. A first wavelength selective reflection layer 5 and a second wavelength selective reflection layer 6 are formed on each of the two surfaces of the first right angle prism 1 that sandwich the right angle, by vapor deposition or sputtering. The wavelength selective reflection layer is formed of a dielectric multilayer film, and the wavelength selective reflection layer characteristics are obtained by alternately laminating several tens of TiO ₂ and SiO ₂ thin films. The same applies to other MgF ₂ and Z _R O. FIG. 2 shows an example of the wavelength selective reflection characteristics. The dotted line shows the characteristics of the first wavelength selective reflection layer 5, and the solid line shows the characteristics of the second wavelength selective reflection layer 6. The first wavelength selective reflection layer 5 reflects red light at a position where the transmittance is 50% is approximately 590 [nm]. Second
The wavelength selective reflection layer 6 has a transmittance of 50% at about 5%.
It reflects blue light near 00 [nm]. The remaining green light (generally between 500 [nm] and 590 [nm]) is transmitted, and thus is used for color separation into the three primary colors and color combination. Incidentally, the wavelength selectivity can be variously separated and combined by changing the setting at the time of vapor deposition.

Of the two surfaces that sandwich the right angle of the second right angle prism 2, one of the two surfaces that sandwich the right angle of the third right angle prism 3 and one of the two surfaces that sandwich the right angle of the third rectangular prism 3 1
The second wavelength selective reflection layer 6 is formed on one surface by vapor deposition or the like similarly to the first rectangular prism 1. 4th
The two surfaces that sandwich the right angle of the right angle prism 4 have no wavelength selective reflectivity.

These four rectangular prisms are bonded together in the direction shown in FIG. 1 so that the wavelength selective reflection layers are orthogonal to each other. Epoxy-based thermosetting type and UV
Optically bonded using a curable optical adhesive or the like.
The refractive index of the optical adhesive may be the same as that of the prism, but since the refractive index is not the same, the dichroic prism configured as shown in FIG. 5 reflects without passing through the adhesive layer. There is light and light that passes through the layer of adhesive and is then reflected, resulting in color differences. Also,
Since the optical path lengths are different, a focus shift or the like occurs in the projection optical system using the lens. However, with the configuration shown in FIG. 1, any incident light is either reflected without passing through the adhesive layer or reflected after passing through the adhesive layer. The above-mentioned problems do not occur at all. In addition, a bright object having a high transmittance can be produced by applying AR coating to the slopes with respect to the right angle.

FIG. 3 is a block diagram of a projection type color display device, which is an embodiment using the dichroic prism of the present invention for color combination.

A light beam emitted from a white light projection light source 7 such as a halogen lamp is condensed by a reflector 8 and a condenser lens 9, and a heat ray blocking filter 11 blocks heat rays in the infrared region. Only visible light is colored. It is incident on the separation system. An elliptical reflector or a parapolar reflector may be used for the light condensing system.

In the color separation system, blue light (approximately 500 [nm] is emitted by the blue reflection dichroic mirror 11.
The following wavelength components are reflected, and then the green light (approximately 500 [nm] to 5 [nm] is reflected by the green reflection dichroic mirror 12.
The wavelength component of 90 [nm] is reflected and the transmitted light is subjected to color separation as red light (wavelength component of approximately 590 [nm] or more). After that, the direction is changed by the reflection mirror 13, and the light enters the liquid crystal light valve for image modulation of each color.

Each color modulation liquid crystal light valve 14R, 14
A signal voltage for each color is applied to G and 14B, and an image is formed for each color depending on the magnitude of the voltage. Since this liquid crystal light valve functions as a shutter that controls the transmittance of incident light, it can be used not only for an active matrix liquid crystal panel or a time-division drive liquid crystal panel, but also for a liquid crystal panel whose transmittance is variable according to a signal voltage. Good. Further, it is also possible to replace with a valve whose transmittance can be controlled by a mechanical type, an electromagnetic type, or the like.

Each color modulation liquid crystal light valve 14R, 14
The respective color lights modulated by G and 14B enter the dichroic prism having the spectral characteristic shown in FIG.

The red light is emitted between the fourth right-angle prism 4 of the second right-angle prism 2 and the third right-angle prism 3 of the first right-angle prism 1 without reaching the adhesive layer.
It is reflected by the wavelength selective reflection layer 5. Similarly, blue light is also reflected by the second wavelength selective reflection layer 6 without reaching the adhesive layer.

The green light is transmitted, and the light forms a color image of the three primary colors, which is enlarged and projected on the screen by the projection lens 15. On the screen, the three-color image has no difference in color between right and left or up and down, and becomes a sharp image with no focus shift, and high-quality image display is performed.

FIGS. 4 and 5 are block diagrams of a conventional dichroic prism. FIG. 4 shows a structure in which four first right-angled prisms are bonded together, and vapor deposition is performed on a total of eight surfaces, resulting in high manufacturing cost. In FIG. 5, two second right angle prisms 2 and three third right angle prisms 3 are laminated alternately so that the above-mentioned color difference and out-of-focus state occur.

The dichroic prism of the present invention is also effective in any color image display device that uses color separation and color combination, other than the above embodiments.

[0020]

As described above, according to the present invention, since only four vapor deposition surfaces are required, the manufacturing cost is extremely low and
The problems such as color difference and out of focus can be solved, high-performance color separation can be performed in the color separation system, and high quality image display can be performed in the projection optical system in the color combination system.

The present invention is particularly effective in the field of color display devices in that excellent color separation and color combining characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a dichroic prism of the present invention.

FIG. 2 is a spectral characteristic diagram of two wavelength selective reflection layers.

FIG. 3 is a configuration diagram showing an embodiment using a dichroic prism of the present invention.

FIG. 4 is an exploded view of a conventional Dyke mouth ic prism as viewed from above.

FIG. 5 is an exploded view of a conventional Dyke mouth wick prism as viewed from above.

[Explanation of symbols]

 1 ... 1st right angle prism 2 ... 2nd right angle prism 3 ... 3rd right angle prism 4 ... 4th right angle prism 5 ... 1st wavelength selection reflective layer 6 ...・ Second wavelength selective reflection layer 7 ... Projection light source 11 ... Blue reflection dichroic mirror 12 ... Green reflection dichroic mirror 14R, 14G, 14B ... Each color modulation liquid crystal light valve 15 ... Projection lens

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[Procedure amendment]

[Submission date] December 5, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

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[Title of the Invention] Dichroic prism

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

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[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0001

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[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dichroic prism that performs color separation and color synthesis of visible light.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

According to the present invention, in a dichroic prism for synthesizing a plurality of color lights, four right-angled prisms are bonded to each other so that the wavelength-selective reflection layers are arranged in a substantially cross shape. A first wavelength selective reflection layer and a second wavelength selective reflection layer are respectively formed on the two surfaces of the first rectangular prism which sandwich the right angle, and the first wavelength selective reflective layer and the second wavelength selective reflective layer are respectively formed on the two surfaces of the first rectangular prism. The first wavelength selective reflection layer is formed on one of the two surfaces sandwiching the right angle, and the wavelength selective reflection layer is not formed on the other surface. A second wavelength selective reflection layer is formed on one of the two sandwiched surfaces,
No wavelength selective reflection layer is formed on the other surface.
No wavelength selective reflection layer is formed on the two surfaces that sandwich the right angle of the right angle prism, and the two right angle prisms that are adjacent to the surfaces that sandwich the right angle of the four right angle prisms have the first wavelength A surface on which the wavelength selective reflection layer is formed so that the selective reflection layer and the second wavelength selective reflection layer are orthogonal to each other;
A surface on which the wavelength selective reflection layer is not formed is bonded by the adhesive, and the second rectangular prism,
The plurality of color lights are incident on the third right-angle prism and the fourth right-angle prism, and combined light is emitted from the first right-angle prism.

[Procedure Amendment 5]

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[Correction contents]

FIG. 1 is a perspective view showing the structure of a dichroic prism. The first wavelength-selective reflection layer 5 and the second wavelength-selective reflection layer 5 are respectively provided on the two surfaces that sandwich the right angle of the first right-angle prism 1.
The wavelength selective reflection layer 6 is formed by vapor deposition or sputtering. The wavelength selective reflection layer is formed of a dielectric multilayer film, and the wavelength selective reflection layer characteristic is obtained by alternately laminating several tens of TiO2 and SiO2 thin films. Other MgF
The same applies to 2 and ZRO. FIG. 2 shows an example of the wavelength selective reflection characteristics. The dotted line shows the characteristics of the first wavelength selective reflection layer 5, and the solid line shows the characteristics of the second wavelength selective reflection layer 6. First
The wavelength selective reflection layer 5 reflects the red light at a position where the transmittance is 50% is about 590 [nm]. The position of the second wavelength selective reflection layer 6 having a transmittance of 50% is generally 500 [n.
m] near and reflects blue light. Remaining green light (generally 5
Since the light between 00 [nm] and 590 [nm] is transmitted, it is used for color separation and color combination of light into three primary colors.
In addition, the wavelength selectivity can be changed by changing the setting during vapor deposition.
Various color separations and color combinations are possible.

Claims (2)

[Claims] 1. A dichroic prism configured such that the wavelength-selective reflection layers are formed in a substantially cross shape by bonding the surfaces sandwiching the right angles of four right-angle prisms to each other with an adhesive. A first wavelength selective reflection layer and a second wavelength selective reflection layer are respectively formed on the two surfaces sandwiching the first and second surfaces, and the two surfaces sandwiching the right angle of the second right-angled prism have a first surface on one surface. The wavelength selective reflection layer is formed on the other surface, and the wavelength selective reflection layer is not formed on the other surface. The two surfaces sandwiching the right angle of the third rectangular prism are the second wavelength selective reflection layer on one surface. And a wavelength selective reflection layer is not formed on the other surface, a wavelength selective reflection layer is not formed on the two surfaces sandwiching the right angle of the fourth rectangular prism, and The two right angle prisms adjacent to the surface sandwiching the right angle are The surface on which the wavelength selective reflection layer is formed and the surface on which the wavelength selective reflection layer is not formed are bonded by the adhesive so that the first wavelength selective reflection layer and the second wavelength selective reflection layer are orthogonal to each other. A dichroic prism that is characterized by 2. A plurality of liquid crystal light valves for respectively modulating a plurality of color lights, a dichroic prism for combining the color lights modulated by the plurality of liquid crystal light valves, and the light combined by the dichroic prisms is projected. In a projection type color display device including a projection lens, the dichroic prism is configured such that the surfaces sandwiching the right angles of four right-angle prisms are adhered to each other with an adhesive so that the wavelength selective reflection layer has a shape of approximately ten thousand. A first wavelength selective reflection layer and a second wavelength selective reflection layer are respectively formed on the two surfaces that sandwich the right angle of the first rectangular prism, and the two surfaces that sandwich the right angle of the second rectangular prism. Includes a first wavelength selective reflection layer formed on one surface and a wavelength selective reflection layer not formed on the other surface, and two surfaces sandwiching the third rectangular prism at right angles. Forms the second wavelength selective reflection layer on one surface and does not form the wavelength selective reflection layer on the other surface, and the wavelength selective reflection layers are formed on the two surfaces sandwiching the right angle of the fourth rectangular prism. No two reflective prisms are formed, and the two adjacent right-angle prisms on the surface sandwiching the right angle of the four right-angle prisms are arranged such that the first wavelength-selective reflective layer and the second wavelength-selective reflective layer are orthogonal to each other. A surface on which the wavelength selective reflection layer is formed and a surface on which the wavelength selective reflection layer is not formed are bonded together by the adhesive, and the second right-angle prism, the third right-angle prism, and the fourth right-angle prism A projection type color display device characterized in that color light from the plurality of liquid crystal light valves is incident on a right-angled prism and synthetic light is emitted from the first right-angled prism to the projection lens.