JP2001305320A - Reflecting mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a reflecting mirror to satisfy necessary heat resistance and mechanical strength while using a glass composition other than that of crystallized glass. SOLUTION: A thin multilayer reflecting film is vapor-deposited on the surface of a glass substrate having a glass composition containing, by weight, 53-64% SiO2, 0-5% Na2O+K2O, 0-8% B2O3, 10-23% Al2O3, 0-8% TiO2+ZrO2, 4-15% ZnO, 0-18% MgO+CaO+BaO+SrO and <=3% one or more components selected from P2O5, As2O3, Sb2O3, PbO and Ta2O5 to obtain the objective reflecting mirror.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector for a light source lamp used in a liquid crystal projector, a projector and the like.

[0002]

2. Description of the Related Art Conventionally, this type of reflecting mirror is formed by depositing a thin-film multilayer reflecting film that reflects visible light of a light source lamp and transmits infrared light and ultraviolet light on the surface of a glass substrate.

[0003] By the way, when the light source lamp has a high brightness,
Since heat generation is intense, the glass substrate constituting the reflecting mirror is required to have heat resistance as a matter of course. The general condition of heat resistance is that a crack or a deposited film is not peeled off by a heat test in which heating to 550 ° C. and cooling to room temperature by natural cooling are repeated eight times.

Further, recently, an ultra-high pressure mercury lamp has been used as a lamp for a liquid crystal projector, so that a mechanical strength is required in preparation for an explosion.

The condition of the mechanical strength is to assemble a lamp in a reflector, to apply an overcurrent during lighting to deliberately rupture the lamp, and to confirm whether the reflector is cracked at that time.

Conventionally, crystallized glass has been known as a glass base material of a reflector that satisfies such conditions of heat resistance and mechanical strength (Japanese Patent Publication No. 7-92527).

[0007]

However, since crystallized glass requires at least two stages of heat treatment for crystallization, there is a problem that the production cost is high.

[0008] In addition, the surface must be polished when depositing the reflecting mirror, which also raises the problem that the manufacturing cost is increased.

Further, the crystallized glass has the following problem in terms of illuminance after the lamp is fixed, in addition to the production cost.

That is, in the case of crystallized glass, since the glass after molding is heat-treated and crystallized, deformation such as slight shrinkage of the glass occurs. For this reason, when the light of the lamp is reflected, there is a problem that the light is irregularly reflected and variations are observed.

Accordingly, the present invention is to provide a reflecting mirror that does not use crystallized glass so that the inner surface can withstand a high temperature of 600 degrees.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention aims to solve the above-mentioned problems by using SiO ₂ 53 to 64% by weight, Na ₂ O + K ₂
O 0-5%, B ₂ O ₃ 0-8%, Al ₂ O ₃ 10-23%, TiO ₂ + ZrO ₂
0 to 8%, ZnO 4 to 15%, MgO + CaO + BaO + SrO 0 to
And 18%, 3% or less of _{P 2 O 5, As 2 O} 3, Sb 2 O 3, PbO, Ta 2 O 5
A reflective mirror was formed by depositing a thin multilayer reflective film on the surface of a glass substrate composed of a glass composition containing one or more components selected from the above.

The glass substrate having the above glass composition is
The average expansion coefficient is 30 to 36 and the strain point shows a value of 620 degrees,
A reflector in which a thin multilayer reflective film is deposited on this glass substrate,
It has good infrared and ultraviolet transmittance and a heat resistance of 600 degrees.

That is, even if a heat resistance test in which heating to 600 ° C. and natural cooling to room temperature are repeated eight times is performed, cracks and cracks do not occur, and peeling of the thin multilayer reflective film formed by vapor deposition does not occur. Does not occur.

[0015] The heat treatment of the above glass improves the mechanical strength.

In the above-mentioned glass composition, the content of SiO ₂ is 53 to
The reason for making the content 64% is that if the content is more than 64%, melting of the glass becomes difficult. When the content is 53% or less, devitrification tends to occur during molding. The reason for making Na ₂ O + K ₂ O 0 to 5% is as follows.
This is because if it is 5% or more, the expansion coefficient increases.

B ₂ O ₃ is a component effective for improving the melting property of the glass and for improving the workability, but when it exceeds 8%, the glass tends to be devitrified. The reason for making Al ₂ O ₃ 10 to 23% is that if it is 10% or less, the mechanical strength becomes weak, and if it is 23% or more, melting becomes difficult.

TiO ₂ + ZrO ₂ is a component necessary for improving the mechanical strength, but if it is less than 4%, the desired strength cannot be obtained. If it is more than 8%, the glass substrate itself becomes unstable. Preferably it is 4 to 6%.

The reason for setting ZnO to 4 to 15% is that if it is 4% or less, the expansion coefficient increases, and if it is 15% or more, the glass is devitrified. MgO + CaO + BaO + SrO is not an essential component, but has an effect similar to that of ZnO.

The As ₂ O ₃ and Sb ₂ O ₃ components can be added as fining agents for glass melting, but a total amount of 3% or less is sufficient.

PbO and P ₂ O ₅ are glass compositions for improving the meltability.

The raw materials prepared so as to have the glass composition shown in Table 1 below were melted at about 1500 to 1600 degrees, and the obtained glass substrate was formed into a reflector shape.
_A reflective mirror was formed by depositing an alternate multilayer film of ₂ O ₅ film and TiO ₂ —SiO ₂ . About the reflector obtained in this way, 600
The heat resistance test was repeated eight times after heating to room temperature and cooling to room temperature by natural cooling.As a result, no cracks or cracks occurred in any of the reflectors, and a thin multilayer reflective film formed by evaporation There was no peeling.

[0023]

[Table 1]

[0024]

According to the reflecting mirror of the present invention, the glass base material is not crystallized glass, but sufficiently satisfies the conditions of heat resistance and mechanical strength.

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Claims (2)

[Claims] (1) SiO ₂ 53 to 64% by weight, Na ₂ O + K ₂ O _g 0
_{~5%, B 2 O 3 0~8} %, Al 2 O 3 10~23%, TiO 2 + ZrO 2 0~
8%, ZnO 4-15%, MgO + CaO + BaO + SrO 0-18%
And 3% or less of P ₂ O ₅ , As ₂ O ₃ , Sb ₂ O ₃ , PbO, on the surface of a glass substrate comprising a glass composition containing one or more components selected from Ta ₂ O ₅ , A reflector on which a thin multilayer reflective film is deposited. 2. A reflecting mirror for a liquid crystal projector, wherein the glass substrate according to claim 1 has an average expansion coefficient of 30 to 36 and a strain point of 620 ° or more.