JPH0430102A - Reflecting plate - Google Patents

Abstract

PURPOSE:To obtain the reflecting plate which is highly resistant to heat and moisture and does not oxide and peel even under repetitively and drastically changing environmental conditions by providing a surface protective layer consisting of a mixture composed of silicon nitride and silicon dioxide on the specular surface part of a reflecting plate base body made of an aluminum alloy. CONSTITUTION:The reflecting plate base body 1 having a prescribed cross sectional shape is formed from, for example, the bright aluminum alloy (A 5650) by a press rolling method. After this base body 1 is sufficiently and precise ly washed and dried, the base body is mounted in a vacuum vapor deposition chamber and is kept heated to about 180 deg.C. The chamber is evacuated to 1X10<-5> Torr and the target consisting of the mixture composed of the silicon nitride and the silicon dioxide at 70:30 by weight is heated by an electron beam, by which the surface protective layer 3 having 0.18mum thickness is formed on the specular surface part 2 of the base body 1. The reflecting plate is thus completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reflector plate used for constructing a lighting system of OA equipment or the like.

[Conventional technology]

A reflector used in a lighting device equipped with a light source in office automation equipment such as a copying machine is a device that efficiently reflects the luminous flux emitted from the light source in a desired direction to illuminate the necessary target. The shape of the mirror surface varies depending on the purpose, from flat to spherical, ellipsoidal, paraboloidal, etc.

Although the reflective plate in such lighting systems does not need to have a particularly precise mirror surface, it does have a special shape, so it is usually formed into the desired shape by rolling or casting aluminum alloy, or by cutting, and then the reflective surface is It is manufactured by mirror-finishing the parts by lapping or electropolishing.

When such a reflector is used in, for example, a lighting device of a copying machine, it is exposed to repeated flashing irradiation from a halogen lamp used as a light source, so when used continuously, the temperature of the reflector may rise to around 250 to 300°C. There was a problem in that the reflective surface was oxidized and turned into alumite, which gradually caused cracks to occur and the mirror surface to become rough.

On the other hand, in order to prevent oxidation deterioration of the mirror surface,
A method of providing a silicon layer as a protective film has been proposed, but even with a reflector configured in this way, aging deterioration such as cracking and peeling in the usage environment cannot be sufficiently suppressed, and the heat resistance and moisture resistance are also poor. It wasn't satisfying.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a reflective plate that has excellent heat resistance and moisture resistance, and that does not oxidize or peel off even under repeated and significantly changing environmental conditions. Our goal is to provide the following.

[Means to solve the problem]

This object of the present invention can be achieved by a reflector, which is characterized in that a surface protective layer made of a mixture of silicon nitride and silicon dioxide is provided on a mirror surface portion of an aluminum alloy reflector base having a predetermined shape. can.

The base material constituting the reflector of the present invention is formed by rolling or casting an aluminum ram alloy into a desired shape by cutting, etc., and then mirror-finished by lapping, electrolytic polishing, etc. A substrate similar to that used as a reflector is used.

In the present invention, a surface protective layer made of a mixture of silicon nitride and silicon dioxide is provided on the mirror surface portion of the substrate.
The composition may consist of a predominant amount of silicon nitride and a minor amount of silicon dioxide, for example 90-50% silicon nitride and 50% silicon nitride.
A mixture with ~10% silicon dioxide is preferably used. Such a surface protective layer can be formed by, for example, a vacuum evaporation method or a sputtering method, and its thickness is 0.1
The thickness is preferably about 0.5 μm, preferably about 0.2 μm.

[For production]

The reflective plate of the present invention is provided with a protective layer having excellent thermal shock resistance and temperature and humidity resistance, and has significantly improved durability.

[Example 1] A reflector substrate 1 having the cross-sectional shape shown in FIG. 1 was formed from a bright aluminum alloy (A5650) by a rolling method. After thorough precision cleaning and drying, this substrate 1 was installed in a vacuum deposition tank, heated to about 180°C and evacuated to a vacuum degree of I x 10-' Torr, and the weight ratio of silicon nitride and silicon dioxide was determined. By electron beam heating a target of a 70:30 mixture, a surface protective layer 3 with a thickness of 0.18 μm was deposited on the mirrored portion 2 of the substrate 1.
Reflector A of the present invention was obtained.

[Example 2] In the same manner as in Example 1 except that the reflector substrate was formed of aluminum alloy (A6063), a surface protective layer with a thickness of 0.20 μm was deposited on the mirrored portion of the substrate, and the present invention was carried out. Reflector B was obtained.

[Comparative example]

The same process as in Example 1 was carried out except that the same reflector substrate as used in Example 1 was used and a silicon target was used.
A silicon layer with a thickness of 0.20 μm was deposited on the mirror surface portion of the substrate to obtain a control reflector C.

[Test example]

These reflectors were subjected to the following temperature/humidity resistance test and lighting test (thermal shock test) to examine their durability.

After being left in an atmosphere with a temperature of 80°C and a relative humidity of 90% for 1°0 hours, it was dried and the condition of the surface protective layer was observed.

In the control reflector C, peeling occurred in the protective layer, whereas in the reflectors A and B of the present invention, not only fogging but also no change was observed.

A test was conducted for 100 hours in which irradiation for 6 seconds and turning off for 5 seconds was repeated 20 times using a 1350 W halogen lamp, followed by a rest for 10 minutes, and the state of the surface protective layer was observed.

While the control reflective plate C had cracks and peeling in the protective layer, no changes were observed in the reflective plates A and B of the present invention.

〔Effect of the invention〕

The reflective plate of the present invention has excellent temperature and humidity resistance and thermal shock resistance, and has the advantage of being able to be used stably over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a reflector of the present invention. DESCRIPTION OF SYMBOLS 1...Reflector base body, 2... Mirror surface part, 3... Surface protective layer. Diagram

Claims (1)

[Claims] 1. A reflector plate comprising a surface protective layer made of a mixture of silicon nitride and silicon dioxide provided on a mirror surface portion of an aluminum alloy reflector substrate having a predetermined shape.