JP2003075614A - Prism, method of manufacturing prism, optical unit, and projection display device - Google Patents

Abstract

(57) [Problem] To prevent uneven brightness in a prism due to a central structure of the prism. Also, when the prism is made of a plastic material, the bonded portion is prevented from peeling off. A concave lens is formed on an entrance surface of a prism.
Also, a convex lens is formed on the exit surface. As a configuration of the bonded portion of the prism pieces, a dichroic multilayer film is formed on one surface side of the adhesive layer, and a single layer film is formed on the other surface side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism for a projection display device that separates color light from incident light or combines a plurality of color lights and outputs the separated light, or separates the incident light into polarized light of different types.

[0002]

2. Description of the Related Art The prior art will be described below with reference to FIGS. FIG. 14 shows a configuration example of a conventional projection display device. In FIG. 14, the white light flux 3 from the light source 1 is made into a uniform white light flux by the reflector 2 of the parabolic mirror, the first lens array 4, the cold mirror 5, and the second lens array 6, and then blue. The green reflection dichroic mirror 7 separates the red luminous flux 8 and the blue / green luminous flux 13. The red light beam 8 is reflected by the increasing reflection mirror 9, passes through the condenser lens 10, and the transmission type liquid crystal panel 12 for red light.
Is incident on. The blue / green light flux 13 is converted into a green light flux 15 and a blue light flux 1 by the green reflection dichroic mirror 14.
9 and 9 are separated. The green light flux 15 passes through the condenser lens 16 and is incident on the transmissive liquid crystal panel 18 for green light. The blue light flux 19 passes through the relay lens 20, the increasing reflection mirror 21, the relay lens 22, the increasing reflection mirror 23, and the condenser lens 24 and is incident on the transmission type liquid crystal panel 26 for blue light. The red light flux emitted from the transmissive liquid crystal panel 12 for red light includes image information, the red light flux emitted from the transmissive liquid crystal panel 18 for green light and the green light flux including image information, and the transmissive liquid crystal panel 26 for blue light. The blue light flux including the image information is incident on the prism 57. In the prism 57, the respective color light fluxes are combined, and the combined light is emitted from the light emitting surface toward the projection lens unit 58. The projection lens unit 58 magnifies the combined light as the image light and projects it on the screen to display an image. The light source 1 is driven by the light source power supply circuit 80. In addition, each liquid crystal panel 1
2, 18, and 26 are driven by the drive circuit 70 based on the image signal input from the input terminal 60, and transmit the corresponding color luminous fluxes (color light) in a modulated state.

FIG. 15 shows a top view of the prism 57. In FIG. 15, the red light flux containing the image information emitted from the transmissive liquid crystal panel 12 for red light is directed to the surface 57 of the prism 57.
The light enters from 1a, is reflected by the bonding surface 571b and the bonding surface 573b at an angle of approximately 90 degrees, and is emitted from the surface 574a. The blue light flux containing the image information emitted from the transmission type liquid crystal panel 26 for blue light is reflected by the prism 57 on the surface 5.
The light enters from 73a, is reflected by 90 degrees at the bonding surface 572b and the bonding surface 574b, and is emitted from the surface 574a. The green light flux containing image information emitted from the transmissive liquid crystal panel 18 for green light is incident on the prism 57 from the surface 572a, and the bonding surfaces 571b, 572b, 573.
b, 574b, and is emitted from the surface 574a. Reference numerals 571, 572, 573, and 574 are triangular prisms each having a cross section of a right-angled isosceles triangle made of glass having the same refractive index. The emitted light 59 that is color-synthesized and contains image information is projected by a projection lens unit 58 onto a screen (not shown) to display an image.

FIG. 12 is a perspective view of the prism, and FIG. 13 is an enlarged sectional view of the prism. In the prism 57, four triangular prisms 571, 572, 573, 574 made of glass having a cross section of an isosceles right triangle and having the same refractive index are attached to each other with an adhesive 57g. Bonding surface 5
A red reflection film 57r having a selective reflection characteristic for red light is formed on 71b and 573b. Bonding surface 57
A blue reflective film 57b having a blue selective reflection characteristic is formed on 2b and 574b. As is clear from FIG. 12, the triangular prisms 573 and 574 are longer in the vertical direction than the triangular prisms 571 and 572. The prism 57 is configured such that the bonding surfaces of the triangular prisms 572 and 573 and the bonding surfaces of the triangular prisms 571 and 574 are linearly bonded. Figure 1
7 is a diagram showing the line width δ of the ridge line for one of the four triangular prisms (here, the triangular prism 571),
FIG. 16 is a diagram showing the line width δ of the central portion 57d of the prism when the four triangular prisms are bonded together without any deviation. When the deviation occurs, the line width δ of the center line of the prism becomes thick as shown in FIG. Prism 5
A reference numeral 7 is held by a prism holder (not shown) of a holding member and forms a color synthesizing means of the projection type display device.

As a conventional technique of a projection type display device having a color synthesizing means, there are, for example, those disclosed in Japanese Patent Publication No. 10-109443 and Japanese Unexamined Patent Publication No. 8-184797.

[0006]

The above-mentioned conventional techniques have the following problems. That is, (1) Since the light is blocked by the central portion 57d of the prism, vertical stripe-shaped luminance unevenness occurs on the screen. FIG. 16 shows the relationship between the width δ of the central portion 57d of the prism and the illuminance ratio. For example, the ridge width δ of the triangular prism is 10 μm
With the above, the width δ of the central portion of the prism also becomes 10 μm or more, and at that time, the difference in the illuminance ratio between the central portion projected on the screen and the adjacent region becomes 3% or more, and the image quality deteriorates. Further, as shown in FIG. 13, the blue reflection film 57b on the surface of the triangular prism 574b and the triangular prism 57 are provided.
There is a gap formed by the adhesive between the blue reflection film 57b on the surface 2b and the width where light is not reflected is larger than the width δ. There is also a gap between the red reflection film 57r on the surface of the triangular prism 571b and the red reflection film 57r on the surface of the triangular prism 573b due to the adhesive, and in this case as well, the width where light is not reflected is larger than the width δ. As described above, the reflected light of the red light flux and the reflected light of the blue light flux is likely to cause vertical stripe-shaped luminance unevenness on the screen. (2) When the prism is made of plastic material, etc., the prism expands due to the heat of the lamp, etc., and at the time of expansion, it adheres to the plastic material surface due to the difference in the coefficient of thermal expansion between the plastic material, the reflective film, and the adhesive The interface of the agent peels off. For example, the same applies to the temperature cycle test conducted between minus 30 ° C and plus 70 ° C. This means that the peel strength between the plastic material and the adhesive is weaker than the peel strength at the interface between the plastic material and the thin film, and the peel strength between the plastic material and the adhesive is weaker than the peel strength at the interface between the thin film and the adhesive. Probably the cause. In view of the situation of the above-mentioned conventional technology, the problem to be solved by the present invention is: (1) suppressing vertical stripe-shaped luminance unevenness caused by the configuration of the central portion of the prism;
(2) The peeling of the adhesive does not occur even when the prism is made of a plastic material or the like. An object of the present invention is to provide a technique capable of solving such a problem.

[0007]

In order to solve the above-mentioned problems, in the present invention, in order to suppress vertical stripe-like luminance unevenness,
(A) A concave lens is formed on the light incident surface of the prism.
(B) A concave lens is formed on the light incident surface of the prism, and a convex lens is formed on the light emitting surface. (C) In the above (A) or (B), concave lenses are formed on the respective color light incident surfaces of the red light, the green light and the blue light. Further, in order to prevent the peeling of the adhesive portion between the prism pieces, (d) As a structure of the bonding portion between the prism pieces, a dichroic multilayer film is formed on one surface side of the adhesive layer and the other surface is formed. A single layer film is formed on the side. Specifically, (i) to (iv) above are (1) a prism in which a concave lens is formed on the light incident surface, as a prism that separates colored light from incident light or combines a plurality of colored lights and emits the combined light. . (2) As a prism that separates colored light from incident light or combines a plurality of colored lights and emits the light, a concave lens is formed on the light incident surface and a convex lens is formed on the light emitting surface. (3) In the above (1) or (2), the light incident surface has concave lenses formed on the respective color light incident surfaces of red light, green light, and blue light. (4) A plurality of triangular prisms are adhered to each other as a prism for separating colored light from incident light or combining a plurality of colored lights and emitting the combined light. The adhesive layer and the prism surface are formed in all or part of the adhered portion. A thin film is provided between and. (5) In the above (4), one of the thin films is a single-layer film and the other is a multi-layer film that reflects a specific color light. (6) In the above (4), the triangular prism is 4
A single-layer film is formed in four of the eight bonded portions, and a multi-layer film that reflects a specific color light is formed in four of the bonded portions. (7) In the above (4), the triangular prism is 4
A single-layer film is formed in four of the eight bonded parts, and a multi-layer film that reflects a specific color light is formed in the other bonded parts. (8) In the above (5), (6) or (7), the single layer film is composed of SiOx (x is a number including a decimal point of 1 to 2) or a mixed substance of SiO ₂ and aluminum oxide. To do so. (9) In the above (8), the mixed substance of SiO ₂ and aluminum oxide has a light refractive index of approximately 1.48 to 1.5.
It should be in the range of 4. (10) In any one of (5) to (9) above, the multilayer film is configured to include a layer of SiOx (x is a number including a decimal point of 1 to 2). (11) In any one of (4) to (10) above,
The triangular prism is made of a plastic material. (12) As an optical unit for a projection display device, a panel that modulates separated color light based on image information, and a concave light is formed on a light incident surface, and the modulated light from the panel that is incident through the concave lens portion. And a projection means for enlarging and projecting the color-combined light on the screen. (13) As an optical unit for a projection type display device, a panel that modulates separated color light based on image information, a concave lens is formed on a light incident surface, and a convex lens is formed on a light emitting surface, and the light is incident through the concave lens portion. And a prism for synthesizing color-modulated light from the panel and radiating it from the convex lens portion, and a projection means for magnifying and projecting the radiated color-synthesized light on a screen. (14) As an optical unit for a projection type display device, a panel that modulates separated color light based on image information and a plurality of triangular prisms are attached to each other, and an adhesive is used in all or part of the attaching portion. A dichroic thin film or a single-layer thin film is provided between the layer and the prism surface,
A configuration is provided that includes a prism that color-modulates and outputs the modulated light from the panel, and a projection unit that magnifies and projects the color-mixed light on a screen. (15) As a projection type display device, from (12) to (1
It is configured to include any one of the optical units 4), a drive circuit for driving the panel, and a power supply circuit for driving the light source. (16) As a method for manufacturing a prism, a step of injection-molding a prism having a triangular prism shape, a step of holding the molded piece in a temperature range of a predetermined range for a predetermined time, a step of cooling thereafter, a first reflective film The prism is manufactured through the steps of forming a single layer film, bonding the triangular prisms, and forming the second reflective film and bonding the triangular prisms. (17) As a prism for separating incident light into polarized light of different types, a plurality of triangular prisms are attached to each other, and a thin film is provided between the adhesive layer and both prism surfaces at the attaching portion. In the above, one is a single layer film and the other is a polarized light separation film having selectivity for polarized light. (18) As a projection type display device, the prism of the above (17), a panel that modulates the separated color light based on image information, a drive circuit that drives the panel, and the color-combined light is enlarged on a screen. A projection means for projecting is provided.

In the above, the concave lens on the light incident surface of the prism enlarges the luminous flux cross-sectional area of the incident light in the prism and reduces the proportion of the luminous flux blocked by the ridgeline at the center of the prism to reduce the uneven brightness on the screen. To do. The convex lens on the light emitting surface of the prism reduces the cross-sectional area of the light flux and causes the prism to emit the combined light in a focused state. When the projection lens unit is coupled, the focused synthetic light is made incident on the projection lens unit. The single-layer film of SiO ₂ or the like in the bonded portion functions to improve the adhesiveness of the adhesive layer on the surface of the triangular prism (prism piece), and the triangular prism (prism piece) is made of a plastic material or the like. Even when configured, the peeling of the adhesive layer should not occur. The multi-layered film of the bonding portion reflects a specific color light to separate the color light from the incident light or combine the plurality of color lights.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In each figure, common parts are denoted by the same reference numerals. FIG. 1 is a configuration diagram of a projection type display device as an embodiment of the present invention. In this embodiment, a prism having a concave lens on the light incident surface and a convex lens on the light emitting surface is used as the prism. In FIG. 1, 27 is a prism,
Reference numeral 28 is a projection lens unit that projects the light 29 emitted from the prism 27 onto a screen (not shown). As in the case of FIG. 14, the white light flux 3 from the light source 1 is made into a uniform white light flux by the reflector 2, the first lens array 4, the cold mirror 5, and the second lens array 6, and the blue and green colors are obtained. The reflection dichroic mirror 7 separates a red light beam 8 and a blue / green light beam 13. Red luminous flux 8
Is reflected by the increasing reflection mirror 9, passes through the condenser lens 10, and enters the transmissive liquid crystal panel 12 for red light. The blue / green light flux 13 is a green reflection dichroic mirror 1.
4 separates a green light beam 15 and a blue light beam 19. The green light flux 15 is incident on the transmissive liquid crystal panel 18 for green light. The blue light flux 19 passes through the relay lens 20, the increasing reflection mirror 21, the relay lens 22, the increasing reflection mirror 23, and the condenser lens 24 and is incident on the transmission type liquid crystal panel 26 for blue light. The red light flux emitted from the transmissive liquid crystal panel 12 for red light includes image information, the red light flux emitted from the transmissive liquid crystal panel 18 for green light and the green light flux including image information, and the transmissive liquid crystal panel 26 for blue light. The blue light fluxes containing the image information are respectively incident on the light incident surface 271a of the prism 27,
The light enters the concave lens portions 272a and 273a. In the prism 27, the color light fluxes are combined to form a light emitting surface 274a.
The light is emitted toward the projection lens unit 28 from the convex lens portion of. The projection lens unit 28 magnifies the combined light as the image light and projects it on the screen to display an image. The light source 1 is driven by the light source power supply circuit 80, and the liquid crystal panels 12, 18, and 26 are driven by the drive circuit 70 based on the image signal input from the input terminal 60, and the corresponding color luminous flux (color light) is modulated. Make it transparent. In the structure of this embodiment, the optical components arranged in the optical path from the light source 1 to the projection lens unit 28 form an optical unit.

FIG. 2 is a top view of the prism 27 as the first embodiment shown in FIG. In FIG. 2, the red light beam 8, the blue light beam 19 and the green light beam 15 are indicated by a prism 27.
Incident on. The red light beam 8 emitted from the red light transmissive liquid crystal panel 12 and including image information is transmitted to the prism 27 by 27
It is incident from the 1a plane. In the case of this embodiment, the 271a surface is
It is a concave lens with a radius of approximately 500 mm. The red light flux 8 that has passed through the surface 271a is separated from the surface 271b and the surface 271b.
The light is reflected by the surface 73b and emitted from the surface 274a to the outside of the prism. The blue light flux 19 containing image information emitted from the blue light transmissive liquid crystal panel 26 enters from the surface 273 a of the color combining cross prism 27. The surface 273a is a concave lens having a radius of about 499 mm in this embodiment. 273
The blue light flux 19 that has passed through the a-side is the bonding surface 272b.
The light is reflected by the surface and the surface 274b and is emitted from the surface 274a to outside the prism. Further, the green light flux 15 containing image information emitted from the green light transmissive liquid crystal panel 18 enters the prism 27 from the surface 272 a. In the present embodiment, the surface 272a is a concave lens having a radius of about 497 mm. 27
The green light flux 15 that has passed through the surface 2a is a bonding surface 271.
B, 272b, 273b and 274b are transmitted and the light is emitted from the surface 274a to the outside of the prism. In the case of the present embodiment, the surface 274a is a convex lens having a radius of approximately 500 mm. The red image modulated by the red light transmissive liquid crystal panel 12, the green image modulated by the green light transmissive liquid crystal panel 18, and the blue image modulated by the blue light transmissive liquid crystal panel 26 are respectively on the light incident surface portion. Since the light passes through the concave lens, the light beam spreads inside the prism. In the light flux thus spread, the proportion of the light flux that is kicked (blocked) at the central portion of the prism is reduced.

In FIG. 3, the light beam 1 is reflected by the concave lens 272a.
It is a figure which shows that the F value of 5 changes. In the case of the first embodiment shown in FIGS. 1 and 2, the light beam 15 passing through the prism
Has an F value of about 2.0, but the concave lens 272a spreads the light beam like the light beam 15a to give an F value of 1.7, and the illuminance ratio on the screen due to the kick at the central portion 57d of the prism is substantially It is reduced from 3% to approximately 1%, which is a level that cannot be visually recognized.

FIG. 4 is a diagram showing a second embodiment of the prism of the present invention. The emission surface 274a is different from the first embodiment shown in FIG. 2 in that the emission surface 274a is not a convex lens but a flat surface. In the second embodiment, the red light flux incident surface 271a, the green light flux incident surface 272a, and the blue light flux incident surface 273a.
Is constructed as a concave lens as in the first embodiment. The emission surface 274a for the color-combined light is a flat surface having irregularities of one wavelength or less. When a projection type display device is constructed by using the prism of the second embodiment, the convex lens action on the light emitting surface of the prism of the first embodiment shown in FIG. 2 is given to the projection lens unit side.

5 to 11, the third to ninth embodiments of the prism of the present invention will be described below. The third to ninth
Example 1 relates to a bonding technique of triangular prisms. FIG. 5 is a diagram showing a third embodiment of the prism of the present invention. In FIG. 5, the prism is composed of four triangular prisms 271, 272, 27 whose base material is a plastic material.
3 and 274. Triangular prism 27
No. 1 has a red reflection film 27r formed on the surface 271b.
SiO ₂ (silicon dioxide) with a thickness of approximately 10 nm is on the 1c surface.
The single layer film 27s is formed. Triangular prism 27
2 has a thickness of approximately 10 nm on both surfaces 272b and 272c.
The SiO ₂ single layer film 27s is formed. In the triangular prism 273, the blue reflection film 27b is formed on the surface 273c, and the SiO ₂ single layer film 2 having a thickness of about 10 nm is formed on the surface 273b.
7s are formed. The triangular prism 274 is 2
The blue reflection film 27b is formed on the surface 74b, and the red reflection film 27r is formed on the surface 274c. Blue reflective film 27b
The first layer and the final layer of the red reflective film 27r are SiO ₂ layers. The four triangular prisms 271, 272,
273 and 274 are adhered by an adhesive 27g. A thin film (SiO ₂ single layer film) 27s is formed between the adhesive 27g and the surface of the triangular prism.
The plastic material as the triangular prism base material is
_{The two} triangular layer prisms 271, 272, 273, and 274 are adhered (bonded) to each other by bringing the _two single-layer films into close contact with each other and the adhesive into close contact with the SiO ₂ single layer film. Combined). Regarding the prism of such a configuration,
A temperature cycle test in the range of approximately -30 ° C to + 70 ° C was carried out, and the adhesive strength (bonding strength) was measured to be approximately 2
A strength of 00 N or more was obtained.

FIG. 6 shows a fourth embodiment of the prism of the present invention. The fourth embodiment is a configuration example in which there is no single layer film on the 272c surface, that is, when a thin film is formed on 7 of the 8 adhesive surfaces. As a result of actual measurement, also in the fourth embodiment, the adhesive strength of approximately 200 N or more was obtained between the four triangular prisms.

7 to 10 show the fifth to fifth prisms of the present invention.
It is a figure which shows an 8th Example. In both cases, the red reflective film 27r and the blue reflective film 2 are different from the configuration of the third embodiment in FIG.
The combination of the positions of 7b and the SiO ₂ single layer film 27s is changed. FIG. 7 is a fifth embodiment of the prism of the present invention.
An SiO ₂ single layer film 27s is formed on the 271c surface of the triangular prism 271, and a red reflection film 27r is formed on the 271b surface.
Is formed, a SiO ₂ single layer film 27s is formed on the surface 272c of the triangular prism 272, and a blue reflection film 27b is formed on the surface 272b.
The SiO ₂ single layer film 27s is formed on the surface 73c.
A red reflection film 27r is formed on the surface b, a SiO ₂ single layer film 27s is formed on the surface 274c of the triangular prism 274, and a blue reflection film 27b is formed on the surface 274b.

FIG. 8 shows a sixth embodiment of the prism of the present invention. 271c surface and 271b of triangular prism 271
A SiO ₂ single layer film 27s is formed on the surface, a red reflection film 27r is formed on the surface 272c of the triangular prism 272, a blue reflection film 27b is formed on the surface 272b, and a surface 273c of the triangular prism 273 is formed. Si on surface 273b
The O ₂ single layer film 27s is formed, and the triangular prism 274 is formed.
A red reflective film 27r is formed on the surface 274c of
A blue reflective film 27b is formed on the b-side.

FIG. 9 shows a seventh embodiment of the prism of the present invention. SiO is formed on the 271c surface of the triangular prism 271.
₂ single-layer film 27s is formed, red reflecting film 27r is formed on 271b surface, and triangular prism 272c has 272c.
SiO ₂ single layer film 27s is formed on the surface and the 272b surface,
The blue reflective film 2 is formed on the surface 273c of the triangular prism 273.
7b is formed, and the SiO ₂ single layer film 27s is formed on the surface 273b.
Is formed, the red reflection film 27r is formed on the surface 274c of the triangular prism 274, and the blue reflection film 27b is formed on the surface 274b.

FIG. 10 shows an eighth embodiment of the prism of the present invention.
Is. Si is formed on the 271c surface of the triangular prism 271.
O₂A single layer film 27s is formed, and red reflection is on the 271b surface.
The film 27r is formed, and 272 of the triangular prism 272 is formed.
SiO on the c-plane and 272b-plane ₂The single layer film 27s is formed.
Blue reflection on the 273c surface of the triangular prism 273.
A film 27b is formed, and SiO2 is formed on the surface 273b.₂Single layer film 2
7s is formed, and the 274c surface of the triangular prism 274 is formed.
A red reflection film 27r is formed on the
The spray film 27b is formed.

7 to 10, the same as FIG. 5 and FIG.
The same parts are designated by the same reference numerals. In either case
In the red reflective film 27r, the first layer and the final layer are made of SiO.₂Shaped in
Dielectric multilayer film having a red reflection characteristic, blue reflection film 2
7b is SiO for the first layer and the final layer. ₂Formed with blue reflection characteristics
Dielectric multilayer film having SiO, SiO₂The thickness of the single-layer film 27s is approximately
It is a thin film of 10 nm. The single layer film 27s is made of SiO.₂Teenager
Instead, SiO (monoxide having a refractive index of approximately 1.55 to 1.65) is used.
It may be formed of silicon). Furthermore, SiO₂instead of
SiO having a refractive index of approximately 1.48 to 1.54₂And oxidation
In the case of a single layer film made of a mixed substance of luminium,
Interface reflectance between plastic material and monolayer film is approximately 0.005%
The range may be as follows.

FIG. 11 shows a ninth embodiment of the prism of the present invention. The present embodiment is an example of a prism in which a film having a selectivity for polarized light (a polarized light separation film) is formed as a light selection film and the incident light is separated into two types of polarized light. The triangular prism 301 has an S-polarized light reflection film 3 on the surface 301c.
0p is formed, and the triangular prism 302 has 302
A SiO ₂ single layer film 30s having a film thickness of about 10 nm is formed on the c-plane. 30 g is an adhesive. The light (light flux 8) incident from the incident surface 301a is reflected by the S-polarized light reflection film 30p and is emitted from the surface 301b. on the other hand,
The P-polarized light is transmitted through the S-polarized light reflection film 30p, and the surface 302a
Emit more. In this way, the incident light flux 8 is S
The polarized light 8s and the P-polarized light 8p are separated. As a projection type display device configuration using the present prism, for example, a light source 1
The white light from the side is aligned with the S-polarized light or the P-polarized light by this prism, the aligned polarized light is color-separated by the dichroic mirror into red light, green light, and blue light, and the separated color light is
A liquid crystal panel or the like is used for modulation based on image information, the modulated color lights are combined by a color combining prism, and the combined light is made incident on a projection means such as a projection lens unit. The liquid crystal panel or the like is driven by a drive circuit based on image information.
The projection means magnifies and projects the combined light on the screen.

Next, an example of the method of manufacturing the prism of the present invention will be described. For example, a cycloolefin resin is used for each triangular prism. The cycloolefin resin has a glass transition point at atmospheric pressure of 139 ° C. (DSC (D
ifferential Scanning Calorimetry method) (in the case of measurement by the differential scanning calorimetry method), the over deflection temperature is 122
° C (ASTM (American Society for Testing and Ma
terial) (when measured with D648). The triangular prism is manufactured by injection compression molding (injection molding and compression) using an injection compression mold equipped with a core compression mechanism. The compression is performed by, for example, triangular prisms 271a, 272a,
The movable portions provided on the surfaces 273a and 274a are compressed by applying pressure. Specifically, for example, the mold temperature is about 130 ° C.
Set to ~ 135 ° C, inject and fill molten resin at about 250 ° C to 300 ° C, apply pressure to the gate part, and then add about 0.8 × 10 ⁵ N / m ² to the core compression part. 1.0 x 10 ⁵ N /
After applying a pressure of m ² for compression and maintaining the state for 5 minutes or longer, the molded product is taken out and naturally cooled in air to room temperature. Next, the molded product is annealed by heating the molded product to a temperature 10 ° C. to 20 ° C. lower than the glass transition point and holding it for a certain period of time, and then cooling to room temperature. As an example, approximately 125 ° C
To about 125 ° C to 100 ° C, then about 0.2 ° C / min.
It is cooled at a rate of 0.4 ° C. and then cooled at a rate of about 1.0 ° C./min from about 100 ° C. to 60 ° C. Then, in air, it is naturally cooled to room temperature.

Next, a dichroic film is formed on the triangular prism formed as described above. As the dichroic film, a red reflective film having a red reflective characteristic and a blue reflective film having a blue reflective characteristic are formed. These dichroic films have, for example, a measurement wavelength of about 550 nm on the first layer.
With a refractive index in the range of approximately 1.43 to 1.47
_Two films, a TiO ₂ (titanium dioxide) film and a Si
O ₂ films are alternately formed, the layer before the final layer is a TiO ₂ film, the final layer is the same SiO ₂ film as the first layer, and a multilayer structure including an odd number of layers of 15 layers or more is formed. When forming the dichroic film of the prisms of FIGS. 5 and 6, the triangular prisms 271 and 274 are combined so that the 271b surface and the 274c surface are one flat surface, and the triangular prisms of the triangular prisms are positioned at the apex positions. The formed ridges are combined so that there is no gap between them. Then 271b and 27
A red reflective dichroic film is formed on the surface 4c. next,
Similarly to the above, the triangular prisms 273 and 274 are combined to form a blue reflection dichroic film on the surfaces 273c and 274b. Similarly, in the case of the configuration of FIG. 7, the triangular prisms 271 and 273 are combined to produce 271b.
A red reflective dichroic film is formed on the surface and the 273b surface. The triangular prisms 272 and 274 are similarly combined to form a blue reflection dichroic film on the surfaces 272b and 274b. Similarly, in the case of the configuration of FIG. 8, the triangular prisms 272 and 274 are combined to form the 272b surface and the 272b surface.
A blue reflective dichroic film is formed on the 4b surface and 272c
A red reflection dichroic film is formed on the surface and the 274c surface. After forming the red reflection dichroic film and the blue reflection dichroic film, a SiO ₂ film is formed with a thickness of about 10 nm. As a result of the experiment, in the configurations of FIGS.
When the film thickness of the SiO ₂ film is thicker than about 20 nm, the interface reflection of the transmitted light at the interface with the triangular prism material or the interface with the adhesive increases or the adhesion strength with the triangular prism material decreases. On the other hand, when the SiO ₂ film is thin and has a thickness of about 5 nm or less, when the film thickness unevenness occurs, there are cases where the film is not formed. Therefore, the thickness of the SiO ₂ film is about 10 nm.
± 5 nm is one suitable range.

Next, four triangular prisms are bonded. Specifically, a visible light curable adhesive is applied between the triangular prisms 273 and 274, held in a jig and irradiated with blue light having a wavelength of about 400 nm to 480 nm to cure the adhesive. Similarly, a visible light curable adhesive is applied between the triangular prisms 271 and 272, and blue light is irradiated to cure the adhesive. Visible light for curing is made incident on the adhesive from the monolayer side. Furthermore, triangular prisms 273 and 27
4 and the triangular prisms 271 and 272 are coated with a visible light curable adhesive and fixed to a jig. Four
After adjusting so that the top corners of each triangular prism are aligned at one point,
Irradiate blue light to cure the adhesive. The visible light for curing is uniformly irradiated from four directions. Through the above steps, one prism is completed.

According to the technique of the above embodiment, the concave lens on the light incident surface of the prism enlarges the light beam cross-sectional area of the incident light in the prism and reduces the ratio of the light beam blocked by the ridge line at the center of the prism. It is possible to reduce vertical stripe-shaped luminance unevenness that occurs on the screen due to the configuration of the central portion of the prism. In addition, the convex lens on the light output surface of the prism is
In order to reduce the cross-sectional area of the light flux and let it exit the prism as combined light in a focused state, and let it enter the projection lens unit,
The burden of light focusing on the projection lens unit can be reduced, and the size and cost of the lens unit can be reduced. Further, the single layer film of SiO ₂ or the like in the above-mentioned bonded portion is
In order to improve the adhesiveness of the adhesive layer on the surface of the triangular prism (prism piece), even when the triangular prism (prism piece) is made of a plastic material or the like, the peeling of the adhesive layer due to thermal expansion or the like is prevented. You can

In the above embodiment, the material of the triangular prism is cycloolefin resin, but the material is not limited to this.
A transparent thermoplastic resin such as an acrylic resin or a polycarbonate resin may be used. Further, in the above embodiment, an example of the case of using a transmissive liquid crystal panel has been described, but the present invention is not limited to this, and a reflective liquid crystal panel may be used, or a liquid crystal panel. Other display panels other than DMD (Digital Micromirror Device)
(Registered trademark of Texas Instruments Incorporated) or the like may be used. For example, in the case of a projection type display device using a reflection type panel, a cross dichroic prism (color combining prism) is used as a color light separation means for separating light into three color lights of red, green and blue, and at the same time, a reflection type It is also used as a color light combining unit that combines the three color lights of red, green, and blue, which are respectively modulated by the panel in accordance with image signals, and emits them.

The inventions related to the invention described in the claims are described as the inventions described in the above embodiments.
(1) The film thickness of the single layer film at the bonded portion of the prism is set to about 20.
(2) As the configuration of the bonded portion of the prism, the first layer of the dichroic multilayer film that reflects at least either red light or blue light, which is in contact with the triangular prism (prism piece), is made of SiOx ( x is a number including a decimal point from 1 to 2), and (3) as a structure of the bonded portion of the prism, one layer of a dichroic multilayer film that reflects at least either red light or blue light, which is in contact with a triangular prism SiOx the eyes and the final layer in contact with the adhesive.
(x is a number including the decimal point from 1 to 2),
(4) Four triangular prisms are bonded together to form one prism, and in seven of the eight bonded portions between the four triangular prisms, between the adhesive layer and the prism surface. (5) As a method for manufacturing a prism piece with a plastic material, a thin film is provided, and an injection-molded prism piece is heated to a temperature 10 ° C. to 20 ° C. lower than the glass transition point and held for a certain period of time. There is a step of performing an annealing process for cooling to room temperature.

[0027]

According to the present invention, image quality can be improved by reducing the stripes on the screen due to the prism. Further, even when a plastic material is used for the triangular prism, an adhesive strength capable of preventing peeling can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a projection type display device as an embodiment of the present invention.

FIG. 2 is a diagram showing a first embodiment of the prism of the present invention.

FIG. 3 is an explanatory view of the action on the light incident surface of the prism of the first embodiment.

FIG. 4 is a diagram showing a second embodiment of the prism of the present invention.

FIG. 5 is a diagram showing a third embodiment of the prism of the present invention.

FIG. 6 is a diagram showing a fourth embodiment of the prism of the present invention.

FIG. 7 is a diagram showing a fifth embodiment of the prism of the present invention.

FIG. 8 is a diagram showing a sixth embodiment of the prism of the present invention.

FIG. 9 is a diagram showing a seventh embodiment of the prism of the present invention.

FIG. 10 is a diagram showing an eighth embodiment of the prism of the present invention.

FIG. 11 is a view showing a ninth embodiment of the prism of the present invention.

FIG. 12 is a perspective view of a conventional prism.

FIG. 13 is an enlarged cross-sectional view of a conventional prism.

FIG. 14 is a diagram showing a configuration example of a conventional projection display device.

FIG. 15 is a top view of a conventional prism.

FIG. 16 is a diagram showing an example of illuminance ratio characteristics on a screen surface of a prism central portion and a portion adjacent to the central portion of the conventional prism.

FIG. 17 is a ridge width δ at the center of the triangular prism.
FIG.

FIG. 18 is a diagram showing a displacement when the triangular prisms are bonded together.

[Explanation of symbols]

1 ... Light source, 2 ... Reflector, 3 ... White light flux, 4 ...
First lens array, 5 ... Cold mirror, 6 ... Second lens array, 7 ... Blue / green reflection dichroic mirror, 8 ... Red light flux, 9 ... Increasing reflection mirror, 10, 1
6, 24 ... Condenser lens, 12 ... Transmissive liquid crystal panel for red light, 13 ... Green / blue light flux, 14 ... Green reflection dichroic mirror, 15 ... Green light flux, 17 ...
Deflection plate, 18 ... Transmissive liquid crystal panel for green light, 19 ...
Blue luminous flux, 20 ... Relay lens, 21 ... Increase reflection mirror, 22 ... Relay lens, 23 ... Increase reflection mirror, 2
6 ... Transmission type liquid crystal panel for blue light, 27 ... Prism,
27r ... red reflective film, 27b ... blue reflective film, 27s,
30s ... Single layer film, 274, 301, 302 ... Triangular prism, 271a ... Red light beam incident surface, 271b,
274c ... Red light flux reflecting dichroic mirror surface, 2
72a ... Green light flux incident surface, 273a ... Blue light flux incident surface, 273c, 274b ... Blue light flux reflection dichroic mirror surface, 274a ... Color composite light flux exit surface, 28 ...
Projection lens unit, 29 ... Emitted light, 30g ... Adhesive, 30p ... S-polarized reflection film, 60 ... Input terminal, 7
0 ... Drive circuit, 80 ... Power source circuit for light source.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 21/00 G03B 21/00 E 33/12 33/12 (72) Inventor Shinji Kadowaki Yoshida Totsuka-ku, Yokohama-shi, Kanagawa 292, Machi, Ltd. Digital media system division, Hitachi, Ltd. F-term (reference) 2H042 CA06 CA08 CA10 CA14 CA15 CA16 CA17 2H091 FA05X FA21X FB03 FC14 FD05 FD15 HA05 LA18

Claims (18)

[Claims] 1. A prism which separates color light from incident light or combines a plurality of color lights and emits the light, wherein a concave lens is formed on a light incident surface. 2. A prism which separates color light from incident light or combines a plurality of color lights and emits the light, wherein a concave lens is formed on the light incident surface and a convex lens is formed on the light emitting surface. prism. 3. The prism according to claim 1, wherein the light incident surface has concave lenses formed on the respective color light incident surfaces of red light, green light and blue light. 4. A prism which separates color light from incident light or combines a plurality of color lights and emits the light, wherein the prism is formed by laminating a plurality of triangular prisms, and an adhesive is used in all or a part of the laminating portion. A prism characterized in that a thin film is provided between a layer and a prism surface. 5. The prism according to claim 4, wherein one of the thin films is a single-layer film and the other is a multi-layer film that reflects a specific color light. 6. Four of said triangular prisms are used, and 8
The prism according to claim 4, wherein a multilayer film that reflects a specific color light is formed in four of the bonded portions, and a single-layer film is formed in the other four bonded portions. 7. Four triangular prisms are used, and eight prisms are used.
The prism according to claim 4, wherein a multilayer film that reflects a specific color light is formed in four of the bonded portions, and a single-layer film is formed in the other three bonded portions. 8. The prism according to claim 5, 6 or 7, wherein the single-layer film is composed of SiOx (x is a number including a decimal point of 1 to 2) or a mixed substance of SiO ₂ and aluminum oxide. . 9. The prism according to claim 8, wherein the mixed substance of SiO ₂ and aluminum oxide has a refractive index of light in the range of approximately 1.48 to 1.54. 10. The multilayer film is formed of SiOx (x is 1 to 2).
10. The prism according to any one of claims 5 to 9, further comprising a layer including a number after the decimal point. 11. The prism according to claim 4, wherein the triangular prism is made of a plastic material. 12. An optical unit for a projection type display device, comprising: a panel for modulating separated color light based on image information;
A concave lens is formed on the light incident surface, and a prism for color-synthesizing the modulated light from the panel, which is incident through the concave lens portion, and projection means for enlarging and projecting the color-synthesized light on a screen are provided. An optical unit characterized by. 13. An optical unit for a projection type display device, comprising: a panel for modulating separated color light based on image information;
A concave lens is formed on the light-incident surface and a convex lens is formed on the light-exiting surface, the modulated light from the panel incident through the concave lens portion is color-synthesized, and the prism is emitted from the convex lens portion, and the emitted color-combined light. An optical unit comprising: a projection unit that magnifies and projects the image on a screen. 14. An optical unit for a projection type display device, comprising a panel for modulating separated color light based on image information,
A plurality of triangular prisms are attached to each other, and a dichroic thin film or a single-layer thin film is provided between the adhesive layer and the prism surface in all or part of the attached portion, and the modulated light from the panel is color-synthesized. An optical unit comprising: a prism that emits the light and a projection unit that magnifies and projects the color-combined light on a screen. 15. A projection type display device comprising: the optical unit according to claim 12; a drive circuit for driving a panel; and a power supply circuit for driving a light source. 16. A method of manufacturing a prism, comprising the steps of injection-molding a prism having a triangular prism shape, maintaining the molded article in a temperature range of a predetermined range for a predetermined time, and then cooling the prism. A prism is manufactured through a step of forming a reflective film of No. 1; a step of forming a single-layer film and attaching a triangular prism; and a step of forming a second reflective film, attaching a triangular prism. A method for manufacturing a prism, comprising: 17. A prism for separating incident light into polarized light of different types, which is formed by laminating a plurality of triangular prisms, and a thin film is provided between the adhesive layer and both prism surfaces at the laminating portion. One of the thin films is a monolayer film, and the other is a polarized light separation film having selectivity for polarized light. 18. The prism according to claim 17, a panel for modulating the separated color light based on image information, a drive circuit for driving the panel, and a projection for enlarging and projecting the color-combined light on a screen. And a projection type display device.