JP3459752B2 - Cross dichroic prism and projection display device using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross dichroic prism and a projection display apparatus using the cross dichroic prism, and more particularly to a cross dichroic prism in which color separation or color synthesis of visible light is appropriately set or manufactured by an appropriate method. It is suitable for projecting an image displayed by a liquid crystal light valve or the like onto a predetermined surface.

[0002]

2. Description of the Related Art Conventionally, a cross dichroic prism formed by bonding four right-angled isosceles triangular prisms has been used as an optical member for performing color separation and color combination of visible light.

FIG. 4 shows that when four right-angled isosceles triangular prisms are attached to each other to form a cross dichroic prism, one of two surfaces sandwiching the right-angled isosceles triangular prism has a wavelength. When the four cross dichroic prisms 21 to 24 each having a selective reflection film are joined together, a method of bonding them with an adhesive so that the respective wavelength selective reflection films 21B, 23B and 22R, 24R are orthogonal to each other is manufactured. is there.

In FIG. 4, in all of the four right-angled isosceles triangular prisms 21, 22, 23, and 24, a wavelength-selective reflective film (hereinafter, referred to as "hereinafter, referred to as" a surface "only on one of two surfaces sandwiching a right angle). Also referred to as "reflection film") 21B, 22R, 23
B and 24R are provided. In the cross dichroic prism shown in FIG. 4, two types of reflecting films (21B, 23B, and 22B) are used.
The orthogonality of R, 24R) does not depend on the angle accuracy of the prism alone, but depends on the bonding accuracy of the four right angled isosceles triangular prisms at the time of joining. Also, the two types of reflective films do not wrap around at the ridge.

In the figure, it is assumed that, for example, blue light LB from the member 25 enters from the left side and red light LR from the member 26 enters from the right side into the cross dichroic prism CP.
At this time, the blue light LB is reflected by the first wavelength-selective reflection films 21B and 23B and is reflected by the exit surface 23a of the rectangular prism 23.
Are deflected in the same direction. Similarly, the red light LR is reflected by the second wavelength selective reflection films 24R and 22R and is emitted from the emission surface 23a of the rectangular prism 23.

If the green light LG from the member 27 is incident from the incident surface 21a of the right angle prism, the green light LG is generated.
Is the first and second wavelength selective reflection films 21B, 23B, 24
R, 22R, exit surface 23a of right-angle prism 23
Exit from.

If each of these members is a liquid crystal light valve that modulates color light, the image displayed there is on a predetermined surface (screen surface) by a projection lens (not shown) provided in the vicinity of the exit surface 23a of the rectangular prism 23. Projected on.

[0008]

FIG. 4 shows four right angle 2
Four cross dichroic prisms having a wavelength-selective reflective film on one of two surfaces sandwiching a right angle of a right angled isosceles triangular prism when the equilateral triangular prisms are bonded together to form a cross dichroic prism. There is a method of bonding 21 to 24 with an adhesive so that the wavelength selective reflection films 21B and 23B and 22R and 24R are orthogonal to each other at the time of bonding.

In FIG. 4, in all of the four right-angled isosceles triangular prisms 21, 22, 23, 24, only one of the two surfaces sandwiching the right angle has a wavelength-selective reflective film (hereinafter referred to as " Also referred to as "reflection film") 21B, 22R, 23
B and 24R are provided. In the cross dichroic prism shown in FIG. 4, two types of reflecting films (21B, 23B, and 22B) are used.
The orthogonality of R, 24R) does not depend on the angle accuracy of the prism alone, but depends on the bonding accuracy of the four right angled isosceles triangular prisms at the time of joining. Also, the two types of reflective films do not wrap around at the ridge.

However, in the cross dichroic prism shown in FIG. 4, since the adhesive for bonding the prisms has a predetermined thickness, the adhesive between the reflective films 21B and 23B and between the reflective films 22R and 24R is the same. There is a problem in that a step is formed by the total of the thickness of the agent and the film thickness of the reflective film, the same reflective film is not arranged on one plane, and as a result, a color shift of the projected image occurs.

In the present invention, the surface of the four right-angled isosceles triangular prisms forming the cross dichroic prism is provided with a wavelength-selective reflective film for color separation and color synthesis, and each right-angled isosceles triangular prism is bonded with an adhesive. The thickness of the adhesive layer when adhered and fixed,
Then, in consideration of the thickness of the wavelength selective reflection film and the like, the four right angled isosceles triangular prisms are bonded and fixed,
The color separation and color combination are performed with high accuracy, and when projecting an image based on each color light on a predetermined surface, a cross dichroic prism and a projection display device using the cross dichroic prism that can obtain an image with good image quality without color misregistration are provided. For the purpose of provision.

[0012]

A cross dichroic prism according to a first aspect of the present invention has a wavelength selectivity on the first surface of the first surface and the second surface forming a prism apex angle of a right angled isosceles triangular prism. Four dichroic prisms with a reflective film
A cross dichroic prism is adhesively bonded, two dichroic prisms are fixed by the adhesive of the four dichroic prisms, each said two dichroic prism of the first surface and the second surface Among them, a surface orthogonal to a bonding surface for bonding the two dichroic prisms is bonded so as to be displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selective reflection is performed. It is characterized in that the films are located on the same plane.

In a cross dichroic prism according to a second aspect of the present invention, a first wavelength-selective reflective film is formed on the first surface of the first surface and the second surface forming the prism apex angle of a right angled isosceles triangular prism. The two dichroic prisms and the third and fourth surfaces that form the prism apex angle of the right-angled isosceles triangular prism .
Two dichroic prisms having a second wavelength-selective reflective film on the third surface of the surfaces are arranged so that the first wavelength-selective reflective film and the second wavelength-selective reflective film are orthogonal to each other. A cross dichroic prism fixed to the
Of the four dichroic prisms, the two dichroic prisms fixed by the adhesive are the first surface, the second surface, the third surface, and the fourth surface of the two dichroic prisms.
Of the two dichroic prisms, a surface orthogonal to the bonding surface is bonded so as to be displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selectivity is achieved. It is characterized in that the reflective film is located on the same plane.

In the cross dichroic prism of the third aspect of the present invention , a wavelength selective reflection film is applied to the first surface of the first surface and the second surface forming the prism apex angle of the right angled isosceles triangular prism. Two dichroic prisms, the first surface on which the wavelength selective reflection film is applied and the second surface on which the wavelength selective reflection film is not applied are arranged to face each other,
A method for manufacturing a cross dichroic prism by fixing with an adhesive to manufacture a cross dichroic prism, wherein two dichroic prisms among the four dichroic prisms are fixed with the adhesive to form a first junction triangular prism. A step of forming the second cemented triangular prism by bonding the remaining two dichroic prisms of the four dichroic prisms with the adhesive, and the first cemented triangular prism and the second cemented triangular prism. And a step of fixing the prism with the adhesive, the two dichroic prisms forming the first cemented triangular prism are the two dichroic prisms of the first surface and the second surface of the two dichroic prisms.
Two dichroic prisms are bonded so that the surfaces orthogonal to the bonding surface are displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selective reflection film is on the same plane. It is characterized by being located.

In a cross dichroic prism according to a fourth aspect of the present invention, a first wavelength-selective reflective film is provided on the first surface of the first surface and the second surface forming the prism apex angle of a right angled isosceles triangular prism. The two dichroic prisms and the third and fourth surfaces that form the prism apex angle of the right-angled isosceles triangular prism .
Two dichroic prisms having a second wavelength-selective reflection film on the third surface of the surfaces , and the first wavelength-selective reflection film or the second wavelength-selective reflection film. Previous
The first surface or the third surface and the second surface or the fourth surface which is not provided with the wavelength selective reflection film are arranged to face each other, and the first wavelength selective reflection film and the first surface. A cross dichroic prism manufacturing method for manufacturing a cross dichroic prism by fixing the two wavelength selective reflection films at right angles with an adhesive, wherein two dichroic prisms among the four dichroic prisms are bonded together. Fixing with an agent to form a first cemented triangular prism, and a step of fixing the remaining two dichroic prisms of the four dichroic prisms with the adhesive to form a second cemented triangular prism. Fixing the first cemented triangular prism and the second cemented triangular prism with the adhesive, and forming two dichroic prisms constituting the first cemented prism. The prism, the first surface said two dichroic prism having said second surface, said third surface, said first
Of the four surfaces, the surfaces that are orthogonal to the bonding surface that joins the two dichroic prisms are bonded so that they are displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selectivity is achieved. It is characterized in that the reflective film is located on the same plane.

In the projection display device according to the invention of claim 5, the luminous flux from the light source means is color-separated into a plurality of color lights by the color separation means, and the color-separated color lights illuminate the image display section provided for each color light. In a projection display device in which light beams from an image display unit are color-synthesized by a color synthesizing unit and projected onto a predetermined surface by a projection optical system, at least one of the color separating unit and the color synthesizing unit is defined by claim 1 or 2. The cross dichroic prism according to any one of the items 1 to 5 is characterized.

According to a sixth aspect of the present invention, the projection display device color-separates the light flux from the light source means into a plurality of color lights by the color separation means, and illuminates the image display section provided for each color light with the color separation. In a projection display device in which light beams from an image display unit are color-synthesized by a color synthesizing unit and projected onto a predetermined surface by a projection optical system, at least one of the color separating unit and the color synthesizing unit is provided. It is characterized by being manufactured by the method for manufacturing a cross dichroic prism described in any one of 1.

[0018]

[0019]

[0020]

[0021]

[0022]

1 is a schematic view of the essential portions of Embodiment 1 of a cross dichroic prism CP of the present invention.

In the figure, reference numerals 11 to 14 respectively denote first to fourth dichroic prisms, and one of two surfaces forming a prism apex angle (prism apex angle 90 degrees) of a right angled isosceles triangular prism. The surface is provided with a wavelength selective reflection film. Here, the prism apex angle is, for example, isosceles 11a, 11a in the first dichroic prism 11.
The angle (90 degrees) formed by b. Hereinafter, the first, second, third, and fourth dichroic prisms 11, 12, 13,
14 are also referred to as prisms 11, 12, 13, and 14, respectively.

11B (13B) is the prism 11, (1
3) Blue light (B) provided on one surface 11a, (13a)
It is a first wavelength-selective reflective film (dichroic film) that reflects light) and transmits other color lights. 12R (14
R) is one surface 12a of the prism 12, (14), (1
The second wavelength-selective reflection film, which is provided in 4a), reflects red light (R light) and transmits other color lights.

The four prisms 11 to 14 are composed of wavelength selective reflection films 11B and 13B and wavelength selective reflection films 12R and 1R.
4R are orthogonal to each other in a cross shape, that is, the surface on which the wavelength selective reflection film is applied and the surface on which the wavelength selective reflection film is not applied are arranged to face each other, and the adhesive S1 is sealed and fixed between them.

Further, the four dichroic prisms 11 to 14 constituting the cross dichroic prism CP of the present embodiment have a total of the thickness D1 of the wavelength-selective reflective film and the thickness D2 of the adhesive layer 1 as the dichroic prisms of each other. The same wavelength-selective reflection films 11B and 13B (12R and 14R) are bonded to each other while being relatively shifted in the parallel direction with respect to the adhesive layer S1 so as to be located on one plane.

That is, four dichroic prisms 11 to 1
In two dichroic prisms of the four, for example, the dichroic prisms 11 and 12, a plane (11b or 12a) orthogonal to the joint surface (11a and 12b) has a thickness D1 of the wavelength selective reflection film and a thickness D2 of the adhesive layer 1. Of the same wavelength selective reflection films 12R and 14R (1
1B and 13B) are located on one plane.

As described above, in this embodiment, four prisms each having a wavelength-selective reflection film on only one of the two surfaces sandwiching the prism apex angle of each prism are bonded to each other at the time of bonding. Are orthogonal to each other and the same wavelength-selective reflection film is positioned on the same plane by an adhesive agent.

In this embodiment, four prisms 11 are used.
Nos. 14 to 14 are bonded by an adhesive, but the optical adhesive used in the present embodiment may have the same refractive index as the refractive index of the material of the prism, for example, an epoxy thermosetting type or an ultraviolet curing type. UV adhesive can be applied.

In particular, in this embodiment, in order to guarantee the perpendicularity and the flatness of the reflecting film at the time of joining, it is semi-cured by slightly irradiating it with ultraviolet rays like a UV adhesive, and the thickness of the adhesive and the post-adhesion After confirming the surface accuracy and the angle of the reflective film, the main curing method is used. The thermosetting type is used when there is little effect on the change in surface accuracy due to heating.

As a joining method, various methods can be applied. For example, first the first prism 11 and the fourth prism 14 are adjusted so that the reflection films are orthogonal to each other, and are joined together.
A second cemented triangular prism that is obtained by similarly joining the third prism 13 and the third prism 13 is obtained, and finally, the final shape is obtained while adjusting so that a part of the reflective films of both are orthogonal and on one plane. The method can be applied.

FIG. 2A shows a method of securing the accuracy of the reflection film at the time of joining when the first and fourth prisms 11 and 14 in this embodiment are joined to obtain the first joined triangular prism. Show.

In FIG. 2A, in order to ensure the perpendicularity between the reflection film 11B and the reflection film 14R, a parallel beam is made incident from the collimator CO and the deviation of the auto-collimated reflected light is observed to obtain two values. The reflective surfaces 11a and 14a are joined while measuring the angle deviation.

In this embodiment, the surfaces 11a and 14b which are not the bonding surfaces of the first prism 11 and the fourth prism 14 have the thickness D1 of the adhesive S1 and the thickness D2 of the wavelength selective reflection film 11B in advance. Bonding is performed with a step formed by the total thickness (D1 + D2).

FIG. 2B shows the thus prepared 2
It is explanatory drawing regarding the joining when each prism is further joined and it is in a completed state.

In this case, a further perpendicularity is guaranteed with respect to one of the perpendicularities of the reflective film guaranteed in FIG. 2 (A). That is, paying attention to a combination of reflecting surfaces different from that shown in FIG. 2A, the perpendicularity of the auto-collimated reflected light is measured, and the main joining curing is performed. The surfaces 11B and 13B are located on the same plane after joining due to the step difference secured in advance. In the present embodiment, the total thickness of the adhesive and the reflective film is about 10 to 50 μm.

FIG. 3 is a schematic view of a main part of a projection type display device of the present invention using the cross dichroic prism CP shown in FIG.

In the figure, 1 is a high-intensity lamp (light source) as a light source means, 2 is a lamp reflector (reflector) such as an elliptical mirror, which collects the light flux from the light source 1 and cuts off the ultraviolet / infrared rays 3 It is incident on the side.

4 is a dichroic mirror for selectively reflecting the red light LR, 5 is a dichroic mirror for selectively reflecting the green light LG, 5a1, 5a2 are for reflecting the blue light LB, and are reflections for deflecting the optical path. A mirror 5a3 reflects a red light LR, a red liquid crystal light valve 6 captures and modulates red light, a green light liquid crystal light valve 7 captures and modulates green light, and 8 blue light. A blue light liquid crystal light valve which is modulated by 1., 9 is a color synthesizing means, and is composed of a cross dichroic prism having the configuration of FIG. 1 according to the present invention. Reference numeral 10 denotes a projection lens for projecting the light (image displayed by the light valve) combined by the cross dichroic prism 9 onto a predetermined surface (screen). Reference numeral 1A is a housing that holds the above unit together. The dichroic mirrors 4, 5 and the reflection mirrors 5a1, 5a2, 5a3 constitute one element of color separation means.

Of the wavelength-selective reflection film of the dichroic prism 9, the first wavelength-selective reflection film 9B deflects the blue light LB from the blue-light liquid crystal light valve 8 by 90 degrees and emits it to the emission surface 9a. Have an effect.

On the other hand, the second wavelength-selective reflection film 9R deflects the red light LR from the red light liquid crystal light valve 6 in the opposite direction by 90 degrees and emits the red light LR to the emission surface 9a. The green light LG from the green light liquid crystal light valve 7 is divided into the first and second green light.
The light is incident on the wavelength selective reflection films 9B and 9R at an incident angle of 45 degrees and is transmitted.

The first and second wavelength selective reflection films 9B and 9R
The dichroic characteristic of is determined in consideration of the transmission characteristic of green light.

In the projection type display device having such a structure, by using the cross dichroic prism 9 having no angular deviation and vertical stripes, the images displayed by the liquid crystal light valves 6, 7 and 8 can be displayed in high quality on a predetermined surface. The image is projected as a high-quality image.

In the present embodiment, the example in which the cross dichroic prism is used as the color synthesizing means is shown, but the cross dichroic prism may be used as the color separating means, or both cross dichroic prisms may be used.

[0045]

As described above, according to the present invention, the surfaces of the four right-angled isosceles triangular prisms forming the cross dichroic prism are provided with a wavelength-selective reflective film for color separation and color combination, and each right-angled two. In consideration of the thickness of the adhesive layer when the equilateral triangle prism is adhered and fixed with an adhesive, and the thickness of the wavelength selective reflection film, etc., the four right angled isosceles prisms are adhered and fixed, A cross dichroic prism and a projection display device using the cross dichroic prism, which can perform color separation and color synthesis with high accuracy and obtain an image with good image quality without color deviation when an image based on each color light is projected on a predetermined surface. Can be achieved.

In particular, according to the present invention, it is possible to guarantee the perpendicularity of the two types of wavelength-selective reflective films arranged in a cross shape without relying on the accuracy of the right-angle prism as a single unit.
Furthermore, when combining and bonding four right-angled isosceles triangular prisms, two kinds of wavelength-selective reflective films are formed after completion by bonding with a step considering the thickness of the adhesive and the reflective film. It is possible to arrange them in a cross shape at right angles and to arrange the same reflection film on the same plane, and as a total effect of these, the accuracy of single-part components can be greatly relaxed.

Further, since the projection type display device incorporating this cross dichroic prism can prevent pixel shifts of each color, vertical streaks, etc., high quality and high quality images can be obtained. Even if the definition becomes higher in the future, the angle measurement accuracy at the time of bonding and the bonding technology can be used, so that it is possible to reach a level that cannot be achieved by obtaining the angle accuracy in the polishing process.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a first embodiment of a cross dichroic prism of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a crossed dichroic prism according to a first embodiment of the present invention in a joined state.

FIG. 3 is a schematic view of a main part of a projection display device using the cross dichroic prism of the present invention.

FIG. 4 is a schematic view of a main part of a conventional cross dichroic prism.

[Explanation of symbols]

CP, 9 cross dichroic prism 11-14 14 isosceles triangular prism 11B, 13B First wavelength-selective reflective film 12R, 14R Second wavelength-selective reflective film 1 light source means 2 reflector 3 filters 4,5 dichroic mirror 6, 7, 8 liquid crystal light valve 10 Projection lens

Claims (6)

(57) [Claims] 1. Four dichroic prisms having a wavelength-selective reflection film on the first surface of the first surface and the second surface forming the prism apex of a right-angled isosceles triangular prism are fixed with an adhesive. Of the four dichroic prisms, the two dichroic prisms fixed by the adhesive are the two of the first surface and the second surface of each of the two dichroic prisms.
Two dichroic prisms are joined so that the surfaces orthogonal to the joining surface are displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selective reflection film is on the same plane. A cross dichroic prism characterized by being positioned above. 2. A dichroic prism in which a first wavelength-selective reflective film is applied to the first surface of the first surface forming the prism apex angle of a right-angled isosceles triangular prism , and the second surface ,
The forming a prism apex angle of the isosceles right triangular prism prism
Two dichroic prisms in which the second wavelength-selective reflective film is applied to the third surface out of the three surfaces and the fourth surface , the first wavelength-selective reflective film and the second wavelength-selective reflective film. In the cross dichroic prism fixed by an adhesive so that and are orthogonal to each other, the two dichroic prisms fixed by the adhesive among the four dichroic prisms are the first dichroic prisms having the two dichroic prisms . Surface, second surface, third surface, fourth surface
Of the two dichroic prisms, a surface orthogonal to the bonding surface is bonded so as to be displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selectivity is achieved. A cross dichroic prism, characterized in that the reflecting films are located on the same plane. 3. The wavelength selectivity of four dichroic prisms in which a wavelength selective reflection film is applied to the first surface of the first surface and the second surface forming the prism apex angle of a right angled isosceles triangular prism. A cross dichroic prism for manufacturing a cross dichroic prism by arranging the first surface having a reflection film and the second surface not having the wavelength selective reflection film facing each other, and fixing them with an adhesive. And a step of forming two first dichroic prisms of the four dichroic prisms with the adhesive to form a first cemented triangular prism, and the remaining two dichroic prisms of the four dichroic prisms. Fixing the prism with the adhesive to form a second junction triangular prism;
Fixing the bonded triangular prisms and the second bonded triangular prisms with the adhesive, the two dichroic prisms constituting the first bonded triangular prisms, and the two dichroic prisms of each of the two dichroic prisms . 1st and 2nd side
Of the two dichroic prisms, the surfaces being orthogonal to the bonding surface are bonded to each other so as to be displaced from each other by the thickness of the wavelength selective reflection film and the thickness of the adhesive layer, and the same wavelength selective reflection film is formed. The cross dichroic prism is characterized by being positioned on the same plane. 4. A first surface forming a prism apex angle of a right angled isosceles triangular prism, and two dichroic prisms having a first wavelength-selective reflective film on the first surface of the second surfaces ,
The forming a prism apex angle of the isosceles right triangular prism prism
Two dichroic prisms having a second wavelength-selective reflective film on the third surface of the third surface and the fourth surface, and the first wavelength-selective reflective film or the second wavelength-selective reflective film. The first surface or the third surface, which is provided with the wavelength selective reflection film, and the second surface or the fourth surface , which is not provided with the wavelength selective reflection film, are arranged to face each other, and the first wavelength selectivity is provided. A cross dichroic prism manufacturing method for manufacturing a cross dichroic prism by fixing a reflective film and the second wavelength-selective reflective film at right angles with an adhesive so that two of the four dichroic prisms are manufactured. A step of forming a first cemented triangular prism by fixing the dichroic prism with the adhesive; and a step of fixing the remaining two dichroic prisms of the four dichroic prisms with the adhesive to form a second cemented triangular prism. Make up And the first step
Wherein the of having the bonding triangular prism and the step of fixing the second joint triangular prisms by the adhesive, the two dichroic prism constituting the first junction triangular prism, the two dichroic prisms having Front side, front
Of the second surface, the third surface, and the fourth surface, the surface orthogonal to the bonding surface for bonding the two dichroic prisms is only the thickness of the wavelength selective reflection film and the thickness of the adhesive layer. A cross dichroic prism, wherein the cross dichroic prisms are joined so as to be offset from each other, and the same wavelength selective reflection film is located on the same plane. 5. A light beam emitted from the light source means is color-separated into a plurality of color lights by the color separation means, and the image light-emitting section provided for each color light is illuminated by the color-separated color lights, and the light rays emitted from each image display section are colored. In a projection display device in which colors are combined by a combination means and projected onto a predetermined surface by a projection optical system, at least one of the color separation means or the color combination means is a cross according to any one of claims 1 and 2. A projection display device comprising a dichroic prism. 6. A light beam emitted from a light source means is color-separated into a plurality of color lights by a color separation means, and the color-separated color lights illuminate an image display section provided for each color light, and the light rays from each image display section are colored. In a projection display device in which colors are combined by a combination means and projected onto a predetermined surface by a projection optical system, at least one of the color separation means or the color combination means is a cross according to any one of claims 3 to 4. A projection display device manufactured by a method for manufacturing a dichroic prism.