JP2002060230A - Method for manufacturing preform of glass reflection mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing the preform of a glass reflection mirror which has good profile irregularity (deviated little from an ideal curved surface) and has small relative roughness (small in roughness to be smooth) in the case of manufacturing the preform of the surface reflection mirror, and to provide a reflection mirror with reflection characteristic excellent optically. SOLUTION: In the method for manufacturing the preform of the parabolic ellipsoidal glass reflection mirror with a foal distance being <=10 mm and the maximum diameter of an effective reflection surface being <=70 mm, a press molding time >=2 sec is provided by using a trunk mold and an arrow mold in the case of preparing the preform of the glass, the flame is positioned nearly at a right angle with respect to the flange part of the reflection mirror toward a part of the inner surface of the reflection mirror by using the flame within the time of reaching the temperature of the cold removal point of the glass, the flame is arranged biased with respect to the axis of the reflection mirror and the flame is rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of manufacturing a glass reflector fabric used as a light source device belonging to a mobile system in a liquid crystal projector, which is a part of an optical component, and more particularly to a cold method having a dielectric multilayer film. The present invention relates to an improvement of a reflecting mirror having a mirror.

[0002]

2. Description of the Related Art Conventionally, such a reflecting mirror uses a mold in which a barrel type and an arrow shape are combined, a glass in which borosilicate glass is melted is placed on the body type, and the arrow shape is pressed from above. Manufactured by the method. This pressing time had a great effect on the inner surface accuracy of the resulting reflector.

For example, at about 1 second (glass temperature of about 800 ° C.), the transferability of an arrow shape is not sufficient, and in a mobile liquid crystal projector in which an optical device is manufactured with high accuracy, the brightness calculated by optical design is 20 times. ３０30% is a low value. This is because the deviation from the ideal curved surface is about 0.5 mm, and the effective reflection surface is small (for example, φ5).
(0 mm diameter) The reflection mirror has large variations, which is a major problem in characteristics.

[0004] The pressing time is extended so that the glass temperature becomes 700 ° C or less, a reflector mirror fabric is trial-produced, and a cold mirror having at least 21 layers is formed using titanium oxide and silicon oxide as a dielectric multilayer film. Was configured. As a result, there is a problem that the brightness is about 10 to 20% lower than the brightness calculated from the optical design, and the value becomes further lower when the number of continuous production is 300 or more.

[0005] The reason is that an arrow shape (ideal curved surface)
The transferability of the mirror is remarkably improved, but there is a fine deposit made of a glass material (silicon, potassium or sodium oxide) on the inner surface of the reflector (deviation within about 0.1 mm). This is because, even if coated, scattering on the attached matter occurs, thereby deteriorating the optical efficiency. When this deposit is mass-produced, the glass material adheres to the arrow-shaped curved surface and is transferred to the inner surface of the reflector fabric. If mechanical polishing is performed to remove this, the deposits are removed, but the inner surface accuracy itself is deformed by polishing the inner surface of the cloth, and not only the illuminance but also the reflection direction is changed. Further, there is a problem that the number of steps is significantly increased.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above, and has a high surface accuracy (less deviation from an ideal curved surface) and a high surface roughness in manufacturing a reflector fabric. An object of the present invention is to provide a method for producing a small (small roughness, smooth) glass reflector fabric, and to provide a reflector having optically excellent reflection characteristics.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a parabolic or elliptical glass reflector fabric having a focal length of 10 mm or less and a maximum diameter of an effective reflecting surface of 70 mm or less. In the manufacturing method of the above, using a body mold and an arrow shape, having a press molding time of 2 seconds or more at the time of glass material making, and using a flame within the time to reach the annealing point temperature of the glass, the reflection mirror Positioning the flame substantially at right angles to the flange portion of the reflector toward a part of the inner surface,
The flame is arranged eccentrically with respect to the reflecting mirror axis, and the flame is rotated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 6 are schematic explanatory diagrams of one embodiment, and use a mold composed of a body mold 1, an arrow mold 2 and a ring mold 3. FIG. The body mold 1 is configured such that after the glass press molding, an elliptical reflecting surface 5a of the reflecting mirror 5, a lower neck portion 5b, and an upper flange portion 5c are formed.
Glass 4 dissolved to a viscosity of 1 to 10 poise inside the barrel 1
It is better to keep (press) and hold the glass 4 with the arrow mold 2 for a long time so that the mold release is not difficult. For example, in the case of a reflecting mirror having an effective diameter of 50 mm and an average thickness of 4.0 mm, when the glass is pressed until the glass temperature becomes 700 ° C. or lower, the transferability of the arrow shape is good. Conventionally, the temperature was 700 ° C to 800 ° C.

In this case, although the surface accuracy is greatly improved, an adhering substance is formed on the inner surface of the reflector fabric, and the surface roughness is increased.
Unevenness having a particle size of about 0.1 μm was generated. Therefore,
In the method according to the present invention, after the glass blanking, at a time point equal to or higher than the strain temperature after the glass is substantially solidified, the crater diameter φ1.
A part of the inner surface of the cloth of the reflector 3 was concentrated with a flame of a single burner 5 of 3 mm (mixed gas burner of oxygen and propane) and heated for about 2 seconds. After that, when the inner surface of the heated reflector fabric was observed, the surface accuracy was good without any change,
The surface roughness was as low as 0.1 μm or less, and it was confirmed that an extremely good reflecting surface could be obtained.

Next, as a comparative test, an experiment was conducted using a single burner flame having a crater diameter of 2.5 mm (about 2 seconds).
Even if the oxygen propane amount and the mixing ratio are controlled, the φ50
The entire effective diameter of mm could not be covered, and a part having a large roughness remained. Furthermore, heating was carried out with a multi-hole flame burner having 12 or more craters, but a rough surface still remained, particularly in the center, which was problematic.

Further, the flame is positioned almost at right angles to the flange portion with respect to the cloth used as a reflector with one burner as a crater, the flame is arranged eccentrically about 5 mm from the axis of the reflector, and the burner is rotated with a rotary seal. After heating for about 8 to 10 seconds by rotating (20 to 120 times / minute),
The surface accuracy is limited to within 0.1 mm from the ideal curved surface, the roundness is no problem even if it is used for a small projector optical system, and the roughness is over the entire inner surface of the reflecting mirror. The thickness was 0.05 μm or less, and conditions suitable for mass production were found.

Therefore, as a mass production test, a pair of burners to be used are arranged at a right angle to the flange portion in the same manner as described above so as to be polished by the burner in a short time, and are arranged eccentrically from the center of the reflecting mirror axis. As a result, a good reflecting surface was obtained as a reflecting mirror. In addition, if the same arrangement is used,
It was confirmed that a double-hole burner was also good.

In the manufacturing method according to the present invention, the focal length is 10 mm or less, and the maximum diameter of the effective reflection surface is 70 mm.
It is most suitable as a light source device of a mobile liquid crystal projector using a parabolic or elliptical glass reflector as described below.

[0014]

As described above, even if the inner shape of the glass reflector is slightly fogged, deformed, or roughened in the prior art, it does not matter if the projector is a relatively large liquid crystal projector. However, in a mobile device suitable for a small liquid crystal panel of about 0.9 inch, for example, a diameter φ
In a reflecting mirror having an effective reflecting surface of 50 mm or the like, distortion and roughness of the inner surface shape greatly affect optical efficiency. In solving the effects on an industrial level, it is possible to obtain a method of manufacturing a glass reflector fabric having excellent optical characteristics by attaching a simple auxiliary jig (rotary burner) at a time within a tact. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a body mold of an embodiment according to the present invention.

FIG. 2 is an explanatory view showing a state in which glass is injected.

FIG. 3 is an explanatory view showing a state in which pressing is performed using an arrow shape and a ring shape.

FIG. 4 is an explanatory view showing a state after press molding.

FIG. 5 is an explanatory view showing a state in which heat treatment is performed by a burner.

FIG. 6 is an explanatory diagram showing a state after the processing is completed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Body type 2 Arrow type 3 Ring type 4 Glass 5 Reflecting mirror 5a Reflecting surface 5b Neck 5c Flange 6 Burner

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sumio Uehara 1-1 Iriyama-cho, Gyoda-shi, Saitama Iwasaki Electric Co., Ltd. Saitama Works (72) Inventor Susumu Tanaka 380 Juyoji, Kashiwa-shi, Chiba Okamoto Glass Co., Ltd. (72) Inventor Akihiro Hakusan 380 Juyoji, Kashiwa-shi, Chiba Prefecture F-term in Okamoto Glass Co., Ltd.

Claims (1)

[Claims] 1. A method of manufacturing a parabolic or elliptical glass reflector mirror fabric having a focal length of 10 mm or less and a maximum diameter of an effective reflecting surface of 70 mm or less, using a barrel shape and an arrow shape. A press forming time of 2 seconds or more at the time of preparing the glass cloth, and using a flame within a time to reach the annealing point of the glass, using a flame to face a part of the inner surface of the reflecting mirror, A flame positioned substantially at right angles to the portion, a flame disposed eccentrically with respect to the reflecting mirror axis, and rotating the flame.