JP3131875B2 - Dichroic prism and projection type color display device using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dichroic pump.
The present invention relates to a rhythm and a projection type color display device using the same . 2. Description of the Related Art A conventional dichroic prism is shown in FIG.
A right-angle prism having a first wavelength-selective reflective layer and a second wavelength-selective reflective layer on two surfaces sandwiching a right angle as shown in FIG.
5, two right angle prisms 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 in the same manner. In some cases, two right angle prisms were stuck so as to be alternated. [0003] However, in the above-mentioned technique, the former has eight vapor-deposited surfaces on which the wavelength selective reflection layer is formed, so that the manufacturing cost is high. In the latter, there is light that directly enters the dichroic prism and is reflected by the wavelength-selective reflection layer, and light that is reflected by the wavelength-selection reflection layer after passing through the adhesive used for bonding, because the refractive index is different. In the case of a projection optical system, the color is changed, and a lens is used. Accordingly, the present invention is intended to solve such a problem. It is an object of the present invention to reduce the cost and to reduce the light incident on the dichroic prism by using four wavelength selective reflection layers. An object of the present invention is to provide a dichroic prism for color separation that is directly reflected by a reflective layer and does not cause discoloration or defocus. According to the present invention, the surfaces of the four right-angle prisms sandwiching the right angle are bonded to each other with an adhesive so that the wavelength-selective reflection layer has a substantially cross shape.
In the dichroic prism , a first wavelength selective reflection layer and a second wavelength selective reflection layer are respectively formed on two surfaces sandwiching the right angle of the first right angle prism, and sandwich the right angle of the second right angle prism. The two surfaces have a first wavelength-selective reflective layer formed on one surface and no wavelength-selective reflective layer formed on the other surface, and the two surfaces sandwiching the right angle of the third rectangular prism are: A second wavelength selective reflection layer is formed on one surface, a wavelength selective reflection layer is not formed on the other surface, and a wavelength selective reflection layer is formed on two surfaces sandwiching the right angle of the fourth rectangular prism. Are not formed, and the two right-angle prisms adjacent to each other across the right angles of the four right-angle prisms are arranged such that the first wavelength selective reflection layer and the second wavelength selective reflection layer are orthogonal to each other. The surface on which the selective reflection layer is formed, and the wavelength selective reflection layer is formed. If a have surfaces together by the adhesive
Adjacent to the right-angled prism
Between the two right-angle prisms facing each other
Between the wavelength selective reflection layer and one of the adhesive layers.
The first wavelength selective reflection layer reflects red light and green light.
And the second wavelength-selective reflection.
The layer has the property of reflecting blue light and transmitting green light.
It is characterized by that. Also, the present invention provides a plurality of colored light sources.
A plurality of liquid crystal light valves, each of which modulates,
Dike that synthesizes color light modulated by a crystal light valve
By Loic prism and the dichroic prism
A projection type lens having a projection lens for projecting the combined light.
In the color display device, the dichroic prism
Are four so that the wavelength selective reflection layers are arranged in a substantially cross shape.
The surfaces sandwiching the right angle of the right angle prism of
Ri Na is bonded, a right angle of the first of the right-angle prism
A first wavelength-selective reflection layer and a second
And a second wavelength-selective reflection layer is formed on the second rectangular prism.
One of the two surfaces sandwiching the right angle of the
A long selective reflection layer is formed, and a wavelength selective reflection layer is formed on the other surface.
Is not formed, and the right angle of the third right angle prism is
Of the two surfaces sandwiched, one surface has a second wavelength selective reflection
Layer is formed, and on the other side, a wavelength selective reflection layer is formed.
The right angle of the fourth right angle prism
No wavelength selective reflection layer is formed on the surface.
Of the first wavelength selective reflection layer and the right-angle prism
2 so that the two wavelength selective reflection layers are orthogonal to each other.
The surface on which the radiation layer is formed, and the wavelength selective reflection layer is formed.
And the surface that is not adhered by the adhesive,
Two right-angle prisms that face each other with the right angle between them
Between the right angle prisms, one of the wavelength selective reflection
A first wavelength selection layer interposed between the first wavelength selection layer and the adhesive layer.
The selective reflection layer has the property of reflecting red light and transmitting green light.
And the second wavelength selective reflection layer reflects blue light.
And has a characteristic of transmitting green light.
You. According to the above configuration of the present invention, it is possible to significantly reduce the manufacturing cost and sufficiently enhance the performance of the dichroic prism. 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 two surfaces sandwiching the right angle of the first right angle prism 1 by vapor deposition or sputtering. The wavelength selective reflection layer is formed of a dielectric multilayer film, and the characteristics of the wavelength selective reflection layer are obtained by alternately stacking several tens of TiO ₂ and SiO ₂ thin films. Other The same with MgF ₂ and _{Z R} O. FIG. 2 shows an example of the wavelength-selective reflection characteristic, in which the dotted line indicates the characteristic of the first wavelength-selective reflective layer 5 and the solid line indicates the characteristic of the second wavelength-selective reflective layer 6. The first wavelength-selective reflection layer 5 reflects red light at a position where the transmittance is 50%, approximately in the vicinity of 590 [nm]. Second
The wavelength selective reflection layer 6 has a transmittance of about 50% at a position of about 5%.
Blue light is reflected around 00 [nm]. The remaining green light (light between approximately 500 [nm] and 590 [nm]) is transmitted, and is used for color separation into three primary colors and color synthesis. It should be noted that various color separation and color synthesis can be performed for the wavelength selectivity by changing the setting at the time of deposition. [0009] Of the two surfaces sandwiching the right angle of the second right angle rhythm 2, the first wavelength selective reflection layer 5 is provided on one surface, and the two surfaces sandwiching the right angle of the third right angle prism 3 are provided. 1
A second wavelength selective reflection layer 6 is formed on one of the surfaces similarly to the first rectangular prism 1 by vapor deposition or the like. 4th
The two surfaces sandwiching the right angle of the right angle prism 4 have no wavelength selective reflection property. 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. For bonding, use epoxy-based thermosetting or UV
It is optically bonded using a curable optical adhesive or the like.
As long as the refractive index of the optical adhesive is the same as that of the prism, it is not exactly the same, so that the dichroic prism configured as shown in FIG. 5 reflects without passing through the adhesive layer. There are light and light that is reflected after passing through the adhesive layer, where a color difference occurs. Also,
Since the optical path lengths are different, a focus shift or the like occurs in a projection optical system using a lens. However, with the configuration as shown in FIG. 1, any incident light is either reflected without passing through the adhesive layer or reflected after passing through the adhesive layer. However, the above-mentioned problem does not occur at all. In addition, by applying an AR coat on each of the slopes with respect to the right angle, a bright one with high transmittance can be created. FIG. 3 shows an example of a configuration in which the dichroic prism of the present invention is used for color synthesis, and is a configuration diagram of a projection type color display device. A light beam emitted from a projection light source 7 of white light such as a halogen lamp is condensed by a reflector 8 and a condensing lens 9, a heat ray in an infrared region is cut by a heat ray cut filter 11, and only visible light is colored. Inject into the separation system. The light condensing system may use an elliptical reflector or a parapolar reflector to condense light. In the color separation system, blue light (generally 500 [nm]) is reflected by the blue reflecting dichroic mirror 11.
The following wavelength components are reflected, and then the green reflecting dichroic mirror 12 emits green light (generally 500 [nm] to 5
90 [nm] wavelength component is reflected, and color separation is performed as red light (wavelength component of approximately 590 [nm] or more) from transmitted light. Thereafter, the direction is changed by the reflection mirror 13 and the light enters the liquid crystal light valves for modulating the image of each color. Each color modulation liquid crystal light valve 14R, 14
Signal voltages for each color are applied to G and 14B, and an image is formed for each color according to the magnitude of the voltage. Since this liquid crystal light valve functions as a shutter for controlling the transmittance of incident light, it can be used not only for an active matrix liquid crystal panel or a time-division driving liquid crystal panel, but also for a liquid crystal panel whose transmittance varies according to a signal voltage. I just need. Furthermore, 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
Each color light modulated by G and 14B is incident on a dichroic prism having the spectral characteristics of FIG. The red light does not reach the adhesive layer 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.
Is reflected by the wavelength-selective reflection layer 5. Similarly, blue light is reflected by the second wavelength selective reflection layer 6 without reaching the adhesive layer. The green light is transmitted, the light forms a color image of three primary colors, and is enlarged and projected on the screen by the projection lens 15. On the screen, no difference in color is recognized between the left and right or top and bottom of the three-color image, and the image becomes sharp without any out-of-focus, and high-quality image display is performed. FIGS. 4 and 5 show the configuration of a conventional dichroic prism. FIG. 4 shows a structure in which four first right-angle prisms are bonded to each other, so that the vapor deposition is performed on a total of eight surfaces, so that the manufacturing cost is high. FIG. 5 shows a structure in which the second right-angle prism 2 and the third right-angle prism 3 are bonded alternately two by two, and the above-described color difference, out-of-focus, and the like occur. The dichroic prism of the present invention is effective in other than the above-described embodiment as long as it is a color image display apparatus that performs color separation and color synthesis. As described above, according to the present invention, since only four surfaces for forming the wavelength selective reflection layer are required, the manufacturing cost is very low , and the difference in color and out-of-focus can be obtained. This has the effect of solving the problem and enabling high-quality image display especially in the projection optical system . The present invention is particularly effective in that excellent color separation and color synthesis characteristics can be obtained in the field of color display devices.

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 a configuration example using a dichroic prism of the present invention. FIG. 4 is an exploded view of the conventional dike-aperture prism viewed from above. FIG. 5 is an exploded view of a conventional dike-aperture prism viewed from above. [Description of Signs] 1 ... First right-angle prism 2 ... Second right-angle prism 3 ... 3rd right-angle prism 4 ... Fourth right-angle prism 5 ... First wavelength selection Reflective layer 6 Second wavelength selective reflective layer 7 Projection light source 11 Blue reflective dichroic mirror 12 Green reflective dichroic mirrors 14R, 14G, 14B Each color modulation liquid crystal light valve 15 Projection lens

Claims (1)

(57) [Claims] 1. A dichroic prism configured such that the surfaces of the four right-angle prisms sandwiching the right angle are bonded to each other with an adhesive so that the wavelength-selective reflection layer has a substantially cross shape. A first wavelength-selective reflective layer and a second wavelength-selective reflective layer are respectively formed on two surfaces sandwiching the right angle of the right-angle prism, and the two surfaces sandwiching the right angle of the second right-angle prism are one of The first wavelength-selective reflective layer is formed on the surface of No. 1, and the wavelength-selective reflective layer is not formed on the other surface. The two surfaces sandwiching the right angle of the third right-angle prism are formed on one surface. No wavelength selective reflection layer is formed on the other surface, the wavelength selective reflection layer is not formed on the other surface, and no wavelength selective reflection layer is formed on the two surfaces sandwiching the right angle of the fourth rectangular prism. Two right angle prisms adjacent to each other across the right angle of four right angle prisms Prism, the first so that the wavelength selective reflection layer and the second wavelength-selective reflective layer are orthogonal to a plane formed of the wavelength selective reflection layer, and wherein not formed of the wavelength selective reflection layer surface wherein The right-angled prisms are bonded together by an adhesive, and face each other with the right-angled prisms interposed therebetween.
One wavelength selection between two right angle prisms
The first wavelength selective reflection layer reflects a red light and emits a green light by interposing a reflection layer and one of the adhesive layers.
The second wavelength selective reflection layer reflects blue light and transmits green light.
A dichroic characterized by having the property of transmitting light
Hook prism . 2. Multiple liquid crystal light bars that modulate multiple color lights
And the colors modulated by the plurality of liquid crystal light valves.
A dichroic prism for synthesizing light, and the dichroic prism
Projection lens that projects the light synthesized by the back prism
In the projection type color display device comprising: the dichroic prism, the wavelength selective reflection layer is substantially
Sandwich the right angles of the four right angle prisms so that they are
Are bonded to each other by an adhesive, and the two surfaces sandwiching the right angle of the first right-angle prism are
The first wavelength selective reflection layer and the second wavelength selective reflection layer respectively
Is formed, of the two surfaces sandwiching the right angle of the second of the right-angle prism,
A first wavelength selective reflection layer is formed on one surface, and the other
No wavelength selective reflection layer is formed on the surface, and of the two surfaces sandwiching the right angle of the third rectangular prism,
A second wavelength selective reflection layer is formed on one surface, and the other
No wavelength selective reflection layer is formed on the surfaces, and the two surfaces sandwiching the right angle of the fourth rectangular prism
No long selective reflection layer is formed, and the four right-angle prisms are connected to the first wavelength selective reflection layer.
And the second wavelength selective reflection layer is orthogonal to the
The surface on which the long selective reflection layer is formed, and the wavelength selective reflection layer
The surface that is not formed should not be bonded with the adhesive.
The right-angle prisms are opposed to each other with the surfaces sandwiching the right angle adjacent to each other.
One wavelength selection between two right angle prisms
A first wave having a reflective layer and one adhesive layer interposed therebetween;
Long selective reflection layer reflects red light and transmits green light
And the second wavelength selective reflection layer reflects blue light and emits green light.
Projection-type color having transmission characteristics
-Display device.