JPH09113713A - Laminating prism and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a laminating prism which is produced from four pieces of rectangular prisms and is used in separating and synthesizing the colors of a liquid crystal projector in such a manner that the orthogonal color component reflection films thereof respectively constitute planes to prevent the occurrence of a color drift. SOLUTION: This prism is constituted by laminating the constituting prisms to each other in such a manner that a transparent flat plate 7, such as glass, provided with films having a dichroic function interposes at least at one point of the laminating surfaces 7A of these prisms. More particularly, the prism consists of four pieces of the rectangular prisms 6-1 to 6-4 and the transparent flat plate 7 provided with the films having the dichroic function and has the structure in which the surfaces perpendicular to the adhered surfaces of two pieces of the adhered prisms formed by adhering the surfaces 1B and 3B, 2B and 4B across the vertex angles of two pieces of the rectangular prisms 6-1, 6-3 and 6-2, 6-4 are respectively laminated to both surfaces of the transparent flat plate 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded prism having a film having a dichroic function on a bonded surface of the prism and a method for manufacturing the same, and particularly to color separation and color separation of a liquid crystal projector which is one of projection-type displays. The present invention relates to a laminated prism composed of four right-angle prisms for use in synthesizing and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there has been a flat plate type which uses a dichroic mirror having a coat having a dichroic function on a flat glass for color combination in a liquid crystal projector. However, in the flat plate type using the dichroic mirror, it is difficult to obtain a high-precision image due to the aberration of light due to the thickness of the dichroic mirror, so it is possible to develop an apparatus for obtaining a higher quality image. Was wanted. In order to meet such demands, a prism type has been developed which uses a prism in which four right-angle prisms having a dichroic function-coated coat are bonded to each other. In the prism type, since color combination is performed by a coat having a dichroic function applied to the bonding surfaces, a highly accurate image can be obtained without the aberration of light caused by the thickness.

FIG. 1 is a schematic view showing the principle of prism type color combination. An image projected from the liquid crystal element 1 having a red signal is reflected as a red component image by the surface 2 having a dichroic function that reflects red and transmits other colors. The image projected from the liquid crystal element 3 having a blue signal is reflected as a blue component image by the surface 4 having a dichroic function that reflects blue and transmits other colors. The image projected from the liquid crystal element 5 having a green signal passes through the surface 4 having a dichroic function for reflecting blue and the surface 2 having a dichroic function for reflecting red, and is projected on the front surface as an image of a green component. . The images having red, blue, and green components thus obtained are radiated in the same direction by this prism, are combined, and are projected as a color image on the front screen through a lens.

Here, in order to form a color composite image in which the images having the respective components of red, blue and green are sufficiently matched on the screen, the reflected light of the color elements of the three colors at the same position in the image is formed. And the transmitted light needs to be projected so as to share the optical axis. For this reason, it is preferable that the dichroic functional surface 2 that reflects red and the dichroic functional surface 4 that reflects blue are adjacent parallel surfaces, and that the two dichroic functional surfaces are orthogonal to each other. Therefore, by using a right-angle prism having an accurate right angle, the bonding surfaces should be exactly orthogonal, that is, 4
They must be attached so that the ridges of the right-angled portions of each right-angled prism are parallel. If the ridges of the four right-angle prisms are not parallel, the surfaces will be offset or inclined with respect to each other, so the images reflected and transmitted by the surfaces will be projected in different directions, and the images of the respective colors will be projected on the screen. It is not possible to obtain a clear image with matching images. In order to manufacture such a highly accurate bonded prism, a skilled person having a high degree of skill relies on visual observation to bond the four right-angled prisms so that the ridgelines having the right angles accurately overlap each other.

[0005]

As described above, in order to manufacture a laminated prism, since a film having a dichroic function is directly applied to the prism surface, a sophisticated processing technique which requires time-consuming cleaning and film formation is required. However, the yield of the prism was also bad. Moreover, since the prisms that form the bonded prism are bonded three-dimensionally, not only does it require a high level of skill and time to bond the prisms,
The yield as a product was not good either. Therefore, the problem to be solved by the present invention is to provide a bonded prism capable of improving the yield of the constituent prisms by omitting the high-level processing for the prisms constituting the bonded prism. Further, there is a need to provide a method capable of adhering four right-angle prisms so that the ridge lines formed by the apex angles are parallel to each other in a short period of time with high yield without requiring high skill, and in particular, An object of the present invention is to provide a bonding method for reliably manufacturing a bonded prism for resolving and synthesizing red, blue, and green images of a liquid crystal projector without color shift.

[0006]

In order to solve these problems, in the bonded prism of the present invention, a transparent flat plate having a film having a dichroic function is interposed at least at one position on the bonding surface between the prisms. Is characterized by. Further, the bonded prism of the present invention comprises a transparent flat plate having four right-angle prisms and a film having a dichroic function, and each of the two right-angle prisms has two bonded prisms bonded to each other at their right angles. It is characterized in that it has a structure in which a surface perpendicular to the bonding surface is bonded to both surfaces of the transparent flat plate. The transparent flat plate may be a glass plate. Further, the liquid crystal projector of the present invention is characterized by incorporating the above-mentioned pasted prism to perform color combination.

In order to solve the above-mentioned problems, the method for manufacturing a laminated prism of the present invention is such that the first surface of the two surfaces sandwiching the right angle of two right angle prisms is placed on a flat substrate, and the second surface is Face each other and interpose a transparent flat plate such as a glass plate having a film having a dichroic function between the facing second faces, and bond them with an adhesive to form the right angles of the remaining two right-angle prisms. It is characterized in that the first surface of the right-angled prism in which the first surface of the two sandwiched surfaces is bonded to a transparent flat plate, and the second surface is bonded to the transparent flat plate by an adhesive respectively. It is more preferable that the flat substrate is provided with a slit for inserting a transparent flat plate.

The bonded prism of the present invention is characterized in that a transparent flat plate having a film having a dichroic function is interposed at least at one position on the bonded surface between the prisms. Instead of forming a film having a dichroic function, a dichroic function film is formed on an intervening transparent flat plate.
Therefore, by omitting the advanced treatment of coating the prism with a thin film having a dichroic function, not only is the opportunity to waste the expensive prism reduced, but it is also possible to use transparent glass such as a glass plate that is easy to hold in a vacuum evaporation system. Since a coating on a flat plate is used as an alternative, the yield can be increased while using a technique that does not require much skill. Further, the bonded prism of the present invention having a structure in which two adhesive prisms in which surfaces that sandwich the right angle of a right-angled prism are bonded to each other are bonded to both surfaces of a transparent flat plate such as a glass plate having a dichroic functional film, The dichroic functional film on the transparent flat plate is completely flat on the flat plate surface, and the dichroic functional film formed on the adhesive surface of the adhesive prism is a dichroic functional film on the transparent flat plate if it is manufactured so as to adhere to the transparent flat plate. Since it is automatically arranged vertically, it can be adjusted by adjusting the adhesive surfaces of two adhesive prisms so that they are on the same plane. Becomes

Here, if the thickness of the transparent flat plate is 1 mm or less, it can be practically used without any problem, but if it exceeds this value, the color balance of red, blue and green is easily broken. Furthermore, the liquid crystal projector that incorporates the above-mentioned laminated prism of the present invention to perform color combination can obtain a clear image with a small color shift. The present invention is characterized in that the transparent plate is provided with a thin film having a dichroic function. Here, the thin film may be provided on any one surface of the transparent plate, and the dichroic function is red. It may be a film having a function of reflecting blue or a film having a function of reflecting blue. If the dichroic function provided on the glass plate is a film having a function of reflecting red,
If the prism is provided with a film that reflects blue, a laminated prism for color separation and color synthesis can be made.If the dichroic function provided on the transparent plate is a film that reflects blue, the film provided on the prism will be red. A reflective film may be provided.

Further, according to the method for manufacturing a laminated prism of the present invention, since two right-angle prisms are mounted on a flat substrate, the first faces of the two faces sandwiching the right angle are on the flat substrate surface. It is regulated and automatically placed on the same plane with the thickness of the transparent plate sandwiched. Further, since the two surfaces of the remaining two prisms are closely adhered to the surface of the transparent flat plate and the first surface of the right-angled prism bonded to the transparent flat plate, the vertexes having the right angles of the remaining prisms are The ridgeline to be formed is in close contact with the same ridgeline of the prism previously bonded to the transparent flat plate and overlaps with the same straight line, and is parallel with the transparent flat plate sandwiched therebetween. In this way, even an unskilled person can easily and reliably manufacture a bonded prism with high accuracy. If the flat substrate has a slit for inserting the transparent flat plate, insert the transparent flat plate into the slit and stand upright. By pressing from above, it is possible to easily construct a structure in which two right-angled prisms, which are intermediate structures in the manufacturing process, sandwich a thin transparent plate. According to the above method, if the shape accuracy of each prism is sufficiently good, the color component image reflected and projected by the thin film having the dichroic function has no deviation or distortion. It should be noted that the prism shape can be relatively easily provided with high precision as required.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail based on examples.

[0012]

EXAMPLE 1 FIG. 2 is a perspective view of a right angle prism used in Example 1. As a material, BK7 (refractive index nd1.5
1112, an optical glass having optical characteristics of Abbe number νd60.5) was used. The four right-angled prisms have the same shape, the thickness d is 70.7 mm, and the cross section is an isosceles right triangle with the length of the equilateral side a of 50.0 mm and the length of the opposite side b of 70.7 mm. It is a thing.

FIG. 3 is a plan view showing the arrangement of four prisms and a transparent glass plate. Two prisms 6-
1, 6-3 and two prisms 6-2, 6-4 are arranged at symmetrical positions with one transparent flat plate 7 sandwiched between them, and the surfaces formed by the equilateral sides of a right-angled triangle in cross section are bonded together to form a right-angled triangle as a whole. Forming a prismatic bonded prism having a substantially square cross section with the surface formed by the opposite side of the outer surface as the outer surface. When the laminated prism is made precisely, the cross section of the two right-angled prisms on both sides of the transparent plate is two parallel ridges formed by the two ridge lines formed by the vertices that sandwich the right angle of the right triangle. It has become.

One surface 7A of the transparent flat plate 7 is provided with an optical multilayer film having a dichroic function for reflecting red color. An optical multilayer film having a dichroic function for reflecting blue color is applied to a bonding surface 1B of the first prism 6-1 with the third prism 6-3, and a surface 1C facing the ridgeline and facing outward is provided. Antireflection film is applied. In addition, an optical multilayer film having a dichroic function for reflecting blue color is applied to the bonding surface 2B of the second prism 6-2 with the fourth prism 6-4, and the surface 2C facing the ridge line is provided. Has an antireflection film. An antireflection film is applied to the surface 3C facing the ridgeline of the third prism 6-3 and the surface 4C facing the ridgeline of the fourth prism 6-4.

FIG. 4 is a perspective view showing a bonded prism of the present invention in which the above-mentioned four prisms and one transparent flat plate are bonded and integrated. In the laminated prism of the present invention, the red component of the light vertically incident from the surface 3C facing the ridgeline of the third prism is reflected by the surface 7A of the transparent flat plate 7 on which the dichroic optical multilayer film is applied, and the first prism It radiates from the surface 1C of 6-1. In addition, the second prism 6-
The blue component of the light vertically incident from the surface 2C provided with the antireflection film 2 is reflected by the dichroic optical multilayer film of the adhesive surface 1B of the first prism 6-1 and the adhesive surface 2B of the second prism 6-2. Then, the light is emitted from the same surface 1C of the first prism 6-1. Further, the green component of the light vertically incident from the surface 4C of the fourth prism 6-4 on which the antireflection film is applied passes through these dichroic optical multilayer films, and the same first component.
It radiates from the surface 1C of the prism 6-1. In this way, light color combination can be performed.

Further, in this laminated prism, the red component of the light incident from the surface 1C of the first prism 6-1 is covered by the surface 7A of the transparent flat plate 7 having the dichroic optical multilayer film.
And is emitted from the surface 3C of the third prism. In addition, the blue component is applied to the adhesive surface 1B of the first prism 6-1 and the second surface.
The light is reflected by the dichroic optical multilayer film on the adhesive surface 2B of the prism 6-2 and is emitted from the surface 2C of the second prism 6-2. Further, the remaining green component passes through these dichroic optical multilayer films and is emitted from the surface 4C of the fourth prism 6-4. In this way, color separation of incident light can be performed. Since this laminated prism has a shape in which the transparent flat plate 7 is sandwiched between right-angled prisms, the dichroic optical multilayer film that reflects blue has a crevice corresponding to the thickness of the transparent flat plate. If it is as thin as 1 mm or less, there is no practical problem in performing color synthesis or color separation.
Further, if the blue image is subjected to a treatment for compensating for the thickness of the optical multilayer film, it can be practically used even if a considerably large crack is present.

FIG. 5 is a sectional view showing a first step of adhering the prism in the method of manufacturing the bonded prism of the present invention. A flat substrate 8 having a slit 8-1 slightly larger than the thickness of the transparent flat plate 7 in the central portion and having a flat upper surface is prepared. The flat substrate 8 is made of quartz glass and has a diameter of 30.
It is a 0 mmφ disc, and its flatness is not more than one Newton ring per 100 mm ² φ. Here, the transparent plate 7
A glass plate is used as. First, the slit 8 of the substrate 8-
Insert the glass plate 7 into 1 and stand upright. Next, the first prism 6-1 and the second prism 6-2 are firstly placed on the flat substrate 8.
The 1B surface of the prism 6-1 and the 2B surface of the second prism 6-2 are placed downward, and the 1A surface of the first prism 6-1 and the 2A surface of the prism 6-2 are opposed to each other with the glass plate 7 interposed therebetween. To do so. Surface 1A of the first prism 6-1 and the prism 6-2
An adhesive (for example, Photobond (trade name)) made of an ultraviolet curable resin and having the same refractive index as that of the optical glass is applied to the surface 2A. Next, the first applied adhesive
The 1A surface of the prism 6-1 and the 2A surface of the second prism 6-2 were brought into contact with each other with a glass plate interposed therebetween, and ultraviolet rays were irradiated to bond them.

FIG. 6 is a perspective view showing a second-stage bonding method. The 1B surface of the first prism 6-1 obtained by the bonding method of the first step, the second prism 6-2, and the remaining third prism 6-3 and the fourth prism 6-4 in the intermediate component including the glass plate 7. Stick together. At the time of bonding, an adhesive made of an ultraviolet curable resin is applied to the surface 3B of the third prism 6-3 to be attached to the first prism 6-1 and the surface 3A to be attached to the glass plate 7, and the surface 3B is attached to the prism 6 -1 of 1
The surface 4B to be adhered to the glass plate 7 on the surface B and the surface 3A to be adhered to the first prism 6-2 of the fourth prism 6-4.
Then, an adhesive made of an ultraviolet curable resin is applied to the surface 4A to be attached to the glass plate 7, the 4B surface is brought into close contact with the 2B surface of the prism 6-2, and the 4A surface is brought into close contact with the glass plate 7. And glue them together. The bonded prism thus obtained is inevitably formed by the functions of the transparent flat plate 7 and the flat substrate 8 to form a complete dichroic optical multilayer film that reflects the red component and a dichroic optical multilayer film that reflects the blue component. Therefore, even a person with a low degree of skill can easily manufacture the bonded prism with a high yield. Therefore, when the manufactured laminated prism is incorporated into a projection type liquid crystal projector as a color separation / combination prism and an image is projected using this prism, a projected image with almost no color misregistration can be obtained.

In the bonded prism of the present invention, since the right-angle prism is bonded through the glass plate provided with the film having the dichroic function, the man-hour for coating the two surfaces of the right-angle prism with the thin film having the dichroic function is eliminated. Further, by using a glass plate which can be easily held in the vacuum vapor deposition apparatus, it is possible to substitute the coating on the glass plate which can be processed much more easily than the prism. Although the prism has a cross-sectional shape of an isosceles right triangle in the above embodiment, it is not limited to this depending on the purpose of the optical instrument. It is obvious that the method of pasting the right-angle prisms through the glass plate of the present invention can be applied as long as the apex angles of the adjacent prisms satisfy the condition that they complement each other.

[0020]

The method of laminating four right-angle prisms according to the present invention with the ridge lines sandwiching a right angle aligned with each other allows even a person with a low level of skill to easily and reliably perform color registration in a short time. It is possible to manufacture a laminated prism capable of obtaining a projected image, particularly a prism for color separation and combination for a liquid crystal projector. According to the pasting prism obtained by the pasting method of the present invention, it is inevitable to obtain a projected image with almost no color shift when performing color separation or color synthesis. Further, when the above-mentioned laminated prism is incorporated into a liquid crystal projector to perform color combination, an extremely precise color combined image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a color combining principle of a bonded prism according to the present invention.

FIG. 2 is a perspective view of a right angle prism according to an embodiment of the present invention.

FIG. 3 is a plan view showing an arrangement of right-angle prisms according to an embodiment of the present invention.

FIG. 4 is a perspective view showing an embodiment of a bonded prism in the present invention.

FIG. 5 is a cross-sectional view showing a first-stage bonding method in an example of the present invention.

FIG. 6 is a perspective view showing a second-stage bonding method in the embodiment of the present invention.

[Explanation of symbols]

 1 Liquid crystal element having red signal 2 Surface having dichroic function for reflecting red color 3 Liquid crystal element having blue signal 4 Surface having dichroic function for reflecting blue color 5 Liquid crystal element having green signal 6-1, 6-2, 6 -3, 6-4 Right angle prism 7 Transparent flat plate 8 Planar substrate 8-1 Slit

Claims (6)

[Claims] 1. A bonded prism in which a transparent flat plate having a film having a dichroic function is provided at least at one position on a bonding surface between the prisms. 2. A transparent flat plate having four right-angle prisms and a film having a dichroic function, each of which has a surface to sandwich the right-angle of the two right-angle prisms. A bonded prism in which vertical surfaces are bonded to both surfaces of the transparent flat plate. 3. The bonded prism according to claim 1, wherein the transparent flat plate is a glass plate. 4. A liquid crystal projector that incorporates the bonded prism according to claim 1 to perform color synthesis. 5. A method of manufacturing a bonded prism by bonding surfaces of four right-angled prisms that sandwich a right-angled surface to each other, wherein a flat substrate is prepared, and first of two surfaces of the two right-angled prisms sandwiching a right-angled surface. Is placed on the flat substrate, the second surfaces of the two surfaces are opposed to each other, and a transparent flat plate having a film having a dichroic function is interposed between the opposed second surfaces, The first surface of the right-angle prism in which the first surface of the two surfaces sandwiching the right angle of the remaining two right-angle prisms is bonded to the transparent flat plate and the first surface of the right-angle prism A method of manufacturing a bonded prism, comprising bonding the second surface to the transparent flat plate with an adhesive. 6. The flat substrate is provided with a slit into which the transparent flat plate is inserted.
A method for manufacturing a bonded prism as described.