JPH07294915A - Liquid crystal projector - Google Patents

Abstract

PURPOSE:To unnecessitate a large-scale cooler even in a liquid crystal projector improved in the luminance of a light source part and to miniaturize the projector by arranging an optical filter having the ultraviolet ray intercepting function and a heat ray intercepting function in the optical path in the front of the light source. CONSTITUTION:Light emitted from a light source 1 has ultraviolet rays and heat rays intercepted by an optical filter 2 and passes a condenser lens 3, a liquid crystal display device 4, and a field lens 5 and is projected on an independently installed projection screen from a projection lens 6. The optical filter 2 is provided with an ultraviolet ray intercepting layer 10 to give the ultraviolet ray intercepting function and is provided with a heat ray intercepting layer 9 to give the heat ray intercepting function. In this case, it is preferable that the heat ray intercepting layer 9 is arranged on the side of the light source 1. No restrictions are put on the method to laminate the heat ray intercepting layer 9 and the ultraviolet ray intercepting layer 10, and they may be stuck to a transparent substrate like a glass plate with a transparent acrylic adhesive or four outer sides of each layer may be fixed to a molding flask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector using a liquid crystal display. More specifically, the present invention relates to a liquid crystal projector in which an optical filter having an ultraviolet ray blocking function and a heat ray blocking function is arranged in an optical path.

[0002]

2. Description of the Related Art With the development of liquid crystal display (LCD) related technology, it is used for information transmission in small televisions, liquid crystal projectors and the like. Regarding liquid crystal projectors, it is already known that as a system for improving visibility in a bright place, it is effective to combine a polarizing film on a projection screen so as to have the same polarization direction as that of a projector image.

For example, Japanese Patent Publication No. 4-21173 discloses an image projection system in which a screen is provided opposite to a light transmission type projection device, and the image projection is a polarized image, and the screen has a polarization maintaining function. In addition, an image projection system is disclosed in which a polarizing filter is stretched on the reflecting side in a non-parallel posture to the reflecting surface.

It is also possible to improve the visibility by increasing the light source brightness of the liquid crystal projector. It is an issue to remove heat generated from the light source by increasing the brightness of the light source. In particular, there is a problem in heat resistance of the optical filter and the liquid crystal substrate placed in front of the light source. A cooling fan is generally used to solve this problem, and a cooling device such as a cooling fan is being scaled up to improve the cooling effect. However, it is not preferable because not only the equipment cost increases but also the size of the equipment increases.

As a method of solving such a problem, there has been proposed a method of using a resin film having excellent heat resistance for a polarizing filter of a liquid crystal panel. For example, Japanese Patent Laid-Open No. 5-
Japanese Patent No. 158031 discloses a liquid crystal projector in which a polarizing film of a liquid crystal panel is composed of a polyester resin and a dichroic dye. However, although the polarizing film can withstand a long-term continuous use of 4000 hours or more at a temperature of about 100 ° C., it is not always sufficient.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to reduce the size of a device even if it is a liquid crystal projector in which the brightness of a light source section is improved without requiring a large-scale cooling device or the like. It is to provide a liquid crystal projector capable of achieving the following.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors, they have found that the above object can be achieved by arranging an optical filter having an ultraviolet ray blocking function and a heat ray blocking function in a passage in front of a light source, The present invention has been reached.

That is, the present invention provides a liquid crystal projector in which an optical filter having an ultraviolet ray blocking layer and a heat ray blocking layer is arranged in the optical path.

The liquid crystal projector of the present invention will be described in detail below. The liquid crystal projector of the present invention is a liquid crystal projector provided with a light source, an optical filter, a liquid crystal display, a lens, a cooling fan, and a mirror as necessary as main components. Of course, ancillary devices such as a liquid crystal display driver, audiovisual input terminals, and speakers will be installed.

A representative example of a system to which the liquid crystal projector of the present invention is applied will be shown. FIG. 1 is a schematic diagram showing a schematic system of a single liquid crystal substrate type projector.
In FIG. 1, the light generated from the light source 1 is shielded from ultraviolet rays and heat rays by the optical filter 2, and then passes through the condenser lens 3, the liquid crystal display 4 and the field lens 5, and is separately installed from the projection lens 6 to a projection screen. Projected on.

FIG. 2 is a schematic diagram showing a schematic system of a three liquid crystal substrate type projector. In FIG. 2, the light emitted from the light source 1 is shielded from ultraviolet rays and heat rays by the optical filter 2, and then separated into two directions by the dichroic mirror 8a. One light is
The light is reflected by the reflection mirror 7a and reaches the dichroic mirror 8b through the liquid crystal display 4a and the condenser lens 3a. The other light is the dichroic mirror 8c.
To separate in two directions again. One of the lights reaches the dichroic mirror 8b through the liquid crystal display 4b and the condenser lens 3b. The other light passes through the liquid crystal display 4c and the condenser lens 3c, is reflected by the reflection mirror 7b, and reaches the dichroic mirror 8d. The light transmitted through the condenser lenses 3a and 3b is collected by the dichroic mirror 8b and reaches the dichroic mirror 8d, where the reflection mirror 7b is provided.
The reflected light from the light is collected to form one image, which is projected from the projection lens 6 onto a separately installed projection screen.

The liquid crystal projector of the present invention is shown in FIG.
And the optical filter 2 illustrated in FIG. 2 is characterized. Conventionally, the optical filter of the liquid crystal projector is
Absorbs UV rays generated from light sources such as halogen lamps,
It was installed for the purpose of blocking. On the other hand, in the present invention, the optical filter is provided with the ultraviolet ray blocking layer 10 to have the ultraviolet ray blocking function, and the heat ray blocking layer 9 is also provided to have the heat ray blocking function. The heat ray blocking layer 9 of the optical filter 2 is preferably disposed on the light source 1 side. The method for laminating the heat ray blocking layer 9 and the ultraviolet ray blocking layer 10 is not particularly limited, and these are laminated through a transparent acrylic adhesive, urethane adhesive or the like onto a glass plate, a polymethylmethacrylate sheet, a polycarbonate sheet or the like. How to stick on the transparent substrate,
Examples include a method of fixing the four outer edges of each layer to a mold.

There is no particular limitation on the method of providing the optical filter with both the ultraviolet ray blocking function and the heat ray blocking function, and a known method can be applied. As a method for providing the optical filter with an ultraviolet blocking function, a method of using a thermoplastic resin film containing an ultraviolet absorber as an ultraviolet blocking layer is exemplified. Examples of the thermoplastic resin include polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyethylene, polypropylene, polysulfone, polyether sulfone, nylon, polyamide, polyacrylate, polyvinyl fluoride and the like, which are excellent in transparency. Preferred are polyethylene terephthalate, polymethylmethacrylate, polycarbonate and the like.

As a UV absorber, 2-hydroxy-4
-Methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxy Benzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2 ', 4
Benzophenones such as 4′-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone and bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, and

2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'- Hydroxy-3'-ter
t-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-ter
t-octylphenyl) benzotriazole, 2-
(2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- [2'-hydroxy-3'-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2′-methylenebis [4- (1,
1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like.

Considering the ultraviolet blocking effect of the optical filter and the visible light transmittance, the amount of the ultraviolet absorber added is preferably 0.001 to 5 parts by weight per 100 parts by weight of the thermoplastic resin. More preferably 0.01
~ 2 parts by weight. The light transmittance of the optical filter is preferably 1% or less in the wavelength range of less than 380 nm. Therefore, the addition amount of the ultraviolet absorber is appropriately selected within the above range so that the light transmittance of the optical filter becomes such a value.

As a method for producing a thermoplastic resin film containing an ultraviolet absorber, a thermoplastic resin film is prepared by adding the ultraviolet absorber to the thermoplastic resin, mixing, kneading with an extruder or the like, melting and extruding. A manufacturing method may be mentioned. The extrusion molding temperature is a temperature range that exceeds the glass transition point of the thermoplastic resin to a temperature below the decomposition temperature when the thermoplastic resin is amorphous, and the thermoplastic resin when the thermoplastic resin is crystalline. A temperature range from the melting point of the resin to the decomposition temperature is preferable. The thickness of the film is about 10 to 500 μm. A typical commercially available thermoplastic resin film containing an ultraviolet absorber is Lumirror (polyethylene terephthalate film containing ultraviolet absorber), trade name, manufactured by Toray Industries, Inc.

Further, as a method for providing an optical filter with a heat ray blocking function, (1) thermoplasticity as described in Japanese Patent Application Laid-Open No. 56-32352 or Japanese Patent Application No. 4-346338. A method of using a laminate having a metal layer and a metal oxide layer alternately formed on the surface of a resin film by sputtering as a heat ray blocking layer, (2)
(3) Japanese Patent Application No. 4-346338, which uses a thermoplastic resin film containing a near-infrared absorbing compound such as a phthalocyanine compound as a heat ray blocking layer, as described in the patent application relating to Japanese Patent Application No. 5-069663. A method of using a thermoplastic resin film coated with a dye having an infrared ray absorbing property as a heat ray blocking layer as described in the patent application relating to the above publication, and the like. Among these, the method (1) is preferable in consideration of the heat ray blocking function of the optical filter and the visible light transmittance.

A known method can be used as a method for producing a laminate in which a metal layer and a metal oxide layer are alternately formed on the surface of a thermoplastic resin film by sputtering. As the thermoplastic resin, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyethylene, polypropylene, polysulfone, polyether sulfone, nylon, polyamide, polyacrylate,
A thermoplastic resin having excellent transparency such as polyvinyl fluoride can be used. Preferably polyethylene terephthalate,
Examples include polymethylmethacrylate and polycarbonate.

As a method for producing a thermoplastic resin film,
The above method can be mentioned. The film thickness is 10-500
It is about μm.

As a method of alternately forming a metal layer and a metal oxide layer on the surface of the thermoplastic resin film by sputtering, a metal or metal oxide is added to the surface of the thermoplastic resin film at 10 ^-1 to 10 ^-7 torr. A method of laminating by sputtering, vacuum deposition, ion plating, or the like can be used. As the material of the metal layer, silver, gold,
Examples thereof include platinum, copper, aluminum, nickel, palladium, indium, tin, chromium, zinc and the like. Considering the heat ray blocking function of the optical filter, silver, gold, platinum and the like are preferable. As a material for the metal oxide layer, indium oxide,
Examples thereof include zinc oxide, titanium oxide, indium-tin oxide, tin oxide, silicon oxide, aluminum oxide and tungsten oxide. Considering the heat ray blocking function of the optical filter, indium oxide, zinc oxide, titanium oxide and the like are preferable.

The metal layers and the metal oxide layers are alternately formed on the surface of the thermoplastic resin film, and the outermost layers on the front and back sides are formed so as to be the metal oxide layers. That is, they are sequentially laminated on the surface of the thermoplastic resin film as metal oxide layer / metal layer / metal oxide layer / metal layer / metal oxide layer. The greater the number of layers, the sharper the separation between the heat ray portion and the visible ray, but considering that the visible ray transmittance tends to decrease, the total number of layers of the metal layer and the metal oxide layer is three. ,
It is preferably 5 layers or 7 layers.

As the performance of the optical filter, in addition to the ultraviolet ray blocking function, the heat ray blocking function has a wavelength range of 780 to 3.0.
The average transmittance of the light of 00 nm is 30% or less, and the average transmittance of the light of wavelength 380 to 780 nm is 6%.
It is preferably 0% or more. More preferably, the average transmittance in the former wavelength region is 20% or less, and the average transmittance in the latter wavelength region is 70% or more. From this viewpoint, it is preferable that the metal layer has a thickness of 50 to 500Å and the metal oxide layer has a thickness of 100 to 2000Å.

As a method of providing the optical filter with both the ultraviolet ray blocking function and the heat ray blocking function, the film having the ultraviolet ray blocking function and the film obtained as described above may be laminated. Alternatively, a metal oxide layer and a metal layer may be alternately formed on one surface of a film having an ultraviolet ray blocking function by sputtering or the like by the above method. The latter method is preferable because the optical filter can be made thin.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples. The characteristic values shown in the examples were measured by the following methods. (1) Light transmittance for each wavelength Using a spectrophotometer [manufactured by Hitachi, Ltd., model: 356 type], the light transmittance for each wavelength in a wavelength range of less than 380 nm, 380 to 780 nm, and 780 to 3,000 nm is measured. The measurement is performed, and the average light transmittance (%) in each wavelength region is calculated using Planck's formula.

(2) Heat ray shielding effect A sample having a side of 5 cm is vertically fixed, and a metal halide discharge lamp (150 W) and ultraviolet ray shielding of the sample are provided at a substantially central portion 10 mm away from the surface of the heat ray shielding layer of the sample. A thermocouple temperature detection unit (the surface of which is covered with a black film) is installed at a position approximately 5 mm away from the surface of the layer, at approximately the center. In addition, a heat insulating material is used to block light rays from leaking from the outer periphery of the sample to the thermocouple side. The surface of the ultraviolet blocking layer of the sample is irradiated with light from the discharge lamp, the temperature of the black film after 60 minutes is measured, and the temperature (° C) is displayed.

Example 1 A polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name: Lumirror, containing an ultraviolet absorber, thickness: 50 μm, hereinafter referred to as Lumirror) was used as an ultraviolet blocking layer.
On one surface of the lumirror, indium oxide (In ₂ O ₃ , thickness 500 Å), silver (thickness 100 Å), and then indium oxide (In ₂ O ₃ , thickness 500 Å) were sequentially applied to DC.
The layers were laminated by the magnetron sputtering method to produce a laminated body. The obtained laminated body was attached to the surface of a transparent glass plate having a thickness of 1 mm to obtain an optical filter for a liquid crystal projector. Here, the DC magnetron sputtering method refers to indium oxide (I) under a vacuum of 1 × 10 ⁻³ toor.
sputtered in an argon-oxygen mixed gas with a target of n ₂ O ₃ ) and then sputtered in an argon gas with a silver target under a vacuum of 1 × 10 ⁻³ toor. Hereinafter, the same operation is repeated to perform sputtering. The light transmittance for each wavelength and the heat ray blocking effect of the obtained optical filter were measured by the above methods. The obtained results are shown in [Table 1].

Examples 2 and 3, Comparative Example 1 Example 1 except that the heat ray blocking layer was changed as shown in [Table 1].
An optical filter for a liquid crystal projector was obtained in the same manner as. The light transmittance by wavelength and the heat ray blocking effect of the obtained optical filter were measured in the same manner as in Example 1, and the obtained results are shown in [Table 1].

[0029]

[Table 1]

[0030]

The liquid crystal projector provided with the optical filter of the present invention efficiently blocks light rays other than the visible light portion. Therefore, even a high-brightness liquid crystal projector does not require auxiliary equipment such as a cooling device, which is extremely useful for simplifying and downsizing the liquid crystal projector.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic system of one liquid crystal substrate type projector.

FIG. 2 is a schematic diagram showing a schematic system of a three liquid crystal substrate type projector.

[Explanation of symbols]

 1 Light source 2 Optical filter 3, 3a, 3b, 3c Condenser lens 4, 4a, 4b, 4c Liquid crystal display 5 Field lens 6 Projection lens 7a, 7b Reflective mirror 8a, 8b, 8c, 8d Dichroic mirror 9 Heat ray blocking layer 10 UV blocking layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G02F 1/13 505 (72) Inventor O ▲ ▼ Katsutoshi 2 Tango Dori, Minami-ku, Nagoya-shi, Aichi Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Yoichi Hosokawa 2-1, Tango Dori, Minami-ku, Aichi Prefecture Nagoya Mitsui Toatsu Chemical Co., Ltd.

Claims (7)

[Claims] 1. A liquid crystal projector in which an optical filter having an ultraviolet blocking layer and a heat ray blocking layer is disposed in an optical path. 2. The liquid crystal projector according to claim 1, wherein the ultraviolet blocking layer is a film containing 0.001 to 5 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the thermoplastic resin. 3. The liquid crystal projector according to claim 2, wherein the ultraviolet absorber is at least one compound selected from benzotriazoles and benzophenones. 4. The heat ray blocking layer is one kind of laminate selected from three layers, five layers and seven layers in which a metal oxide layer and a metal layer are alternately laminated, and the laminate is a metal. The liquid crystal projector according to claim 1, wherein an oxide layer is provided on the outermost layers on the front and back sides. 5. The liquid crystal projector according to claim 4, wherein the metal oxide layer is a metal oxide having a thickness of 100 to 2000Å of at least one selected from indium oxide, zinc oxide and titanium oxide. . 6. The liquid crystal projector according to claim 4, wherein the metal layer is at least one metal selected from silver, gold and platinum and having a thickness of 50 to 500 Å. 7. The average light transmittance by wavelength of the optical filter is 1% or less in a wavelength range of less than 380 nm, and a wavelength range of 3
60% or more at 80 to 780 nm, wavelength range 780
The liquid crystal projector according to claim 1, wherein the content is 30% or less at 3,000 nm.