JPS5922003A - Manufacture of high reflecting mirror - Google Patents

Abstract

PURPOSE:To obtain a reflecting mirror which has reflecting surfaces protected and an improved reflection factor and is suitable to a rotating polygon mirror, etc., by forming an SiO2 film and a TiO2 film over a specularly finished base material in order. CONSTITUTION:The blank 1 of the rotating polygon mirror which has small polygonal planes 1a is specularly finished by, for example, corrosion resisting Al alloy and then an Al film 2 is formed on each plane 1a to about 1,000Angstrom . Then, the SiO2 film 3 and the TiO2 film 4 are formed in order to optical film thickness nd and lambda0/4 (where (n) is a refractive index, (d) is geometric thickness, and lambda0 is in-use wavelength). The Al film 2 may be omitted depending on the state and kind of the base material 1. Thus, a reflection factor higher than that of the cut mirror surface is obtained, the mirror surfaces are protected, and a decrease in reflection factor due to oxidation is prevented, obtaining the reflecting mirror suitable to obtain a galvanomirror, etc., for the optical deflector of, specially, a laser printer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a highly reflective mirror, particularly a reflective mirror such as a galvanomirror or rotating polygon mirror used as an optical deflector in a laser printer or the like.

Such a reflecting mirror is, for example, Nf (K Giken Monthly Report, 1932).
As shown in the article "Multi-plane polygon high-speed scanning and its manufacturing method" published in December 2007, metal surfaces were conventionally made by polishing them, but the desired mirror surface In order to obtain 〃), the cost was quite high. To avoid this, it is possible to create a reflective mirror by first cutting the aluminum alloy to create a smooth surface that will serve as the reflective surface, then forming an electroless Ni plating layer on this smooth surface, and polishing this to the desired mirror state. It is being done. However, in the Ni alloy film formed by electroless coating, the crystal molecules are arranged relatively regularly, and when viewed microscopically, hard parts and soft parts coexist. For this reason, when this Ni alloy coating is polished, the degree of polishing differs between the hard and soft parts, resulting in uneven polishing, which is one of the limitations of improving surface precision with soil. Therefore, recently, as published in Sharp Branch Axis, September 21, 1981, a technology to finish aluminum alloy into a mirror finish using only ultra-precision cutting has been studied. However, reflective surfaces finished using this method are easily oxidized, and the thickness of the oxide film varies widely depending on temperature and humidity.

Furthermore, the absolute value of this oxide film is small, and even if it is left as it is, it will be about 10 A0 at most, and it cannot be said that it fully fulfills its role as a protective film.

Therefore, a protective film of SiO or 5i02 is usually formed on the reflective surface using a method such as vacuum evaporation, but such a protective film cannot prevent or improve the reflectance. There are drawbacks.

0 shots" 740 Purpose 1 Bamboo, so-called En/Nearing Plasti, ultra-precision cutting of metal: Ensure the reflective layer due to τ (protecting τ further increases the reflectance of the reflective surface). Rotating multi-faceted steel O with the protection that can be achieved
It is an object of the present invention to provide a method for manufacturing a mirror O with high resistance.

The method for producing reflective steel according to this invention (2) involves ultra-precision cutting of a discolored aluminum alloy to form the reflection (1), and then the reflection (W + τ, first the aluminum laminate coating, then the bottom of the aluminum alloy, and the
Attached is the 14-year-old nursing care fee. Toad 1-゛bajS, this O invention j depends on: multifaceted v-
', =- indicates flat Σ's, 2nd. This is a diagram showing an outline of the manufacturing process. First, JIS A251 and American All' A5 (152) made of an edible aluminum alloy as a material, a rotary polygon mirror O/R1 having continuous polygonal facets around the periphery as shown in the figure, a rotation R1 O:, and a pitch milling cutter. It is formed by machining, etc. θ1ζ, each flat core a is cut to a flatness of λ15 by ultra-precision cutting using a diamond cutting tool, etc.
Finish the lower part with a mirror surface with a surface roughness of 0.02II m and a x scale of 1. Next 1 Each plane 1a like this
I, vacuum evaporation method (thanks to A7' rise 2 thickness) 00
Approximately 0'A, 5102 coating 3 and TiO2 fracture 1144
λo/4 (n: refractive index, d
: The product is completed by forming the product with a thickness of about 100 mm (DJ thickness, 2 wavelengths used).

The vacuum evaporation equipment for forming each plate film has an optical film thickness n
It is preferable to control the vacuum chamber at about 5 d.
〉, 0-3 Pa (I Torr-]33 Pa) After exhausting to a normal air pressure of about 3〉, 10'Pa"i
Perform ion bombardment for 5 minutes while supplying Immediately after that (stop the oxygen supply and restart 5〉,] 0-3P
After forming a, an Al film is deposited. At this time
The deposition time is desirably 2 minutes or less. The evaporation of 5i02 and TiO2 is then carried out, and the evaporation of the Aj evaporation source is performed using an electric jJD thermal system, and the subsequent evaporation of the evaporation source is performed using an electron beam heating method. Immediately return the vacuum chamber to atmospheric pressure and heat the product to 30 sho, 400mm.
C. and then cooled for 10 minutes to complete the MW process.

FIG. 4 shows an example of a vacuum evaporation apparatus for carrying out such evaporation. This device], OK is equipped with a photoelectric film thickness monitor. Inside the vacuum chamber 11, an electron beam heating device 12 and a resistance heating device 13 are arranged at the bottom, and a dome 1 holding a monitor glass 14 at the top.
5 and a sheathed heater 16 are provided. Also,
A diffusion pump (not shown) is connected in the direction of arrow J7. The photoelectric film thickness monitor consists of a lamp 18 for irradiating light onto the monitor glass 4, a lens 19, and a sector 2.
0, pinhole 2], a light emitting unit consisting of a lens 22, and a reflecting mirror 23, a reflecting mirror 24 for receiving reflected light from the monitor glass 14, an aperture 25, a lens 26, a 1900 filter 27, and a diffusion filter. 28, light 'K tube 29
, Selective increase TI @ device 30. Differential amplifier 31, meter 32
and a part of the monitor (with a similar configuration to the light receiving section for receiving transmitted light from the monitor glass 14).
Each car is marked with a dash/- on the same symbol. ). The thickness of the deposited thin film on the monitor glass 14 can be determined to be 1n11 by comparing the meter 32 of the light receiving part and the meter 32' of the monitor part.
can be determined.

The reflectance R of the entire coating formed as shown in C can be determined from the following equation.

Here, +1: Refractive index of Al coating (n = n - ik) nL:
5i02 film refractive index r1+B TiO2+M film refractive index l (: constant

On the other hand, the reflectance R6 when mirror-finishing an aluminum alloy blank plane can be found from the following equation.

In this way, the reflectance of the mirror surface of the aluminum blank that has been subjected to ultra-rust active cutting is about 90.7% [on the other hand, the reflectance of the vapor-deposited film provided on the surface is as high as about 973.6]. The purpose of this invention is to protect the cut mirror surface and improve the reflectance.
Together we will achieve 75 (understood).

In the actual prototype, the reflectance of the cut mirror surface was 89% and the reflectance of the vapor-deposited film was 95%, both of which are lower than the reduced value, but this does not reduce the effectiveness of this invention. It's not a big deal.

Although the above embodiment includes a step of vapor-depositing aluminum onto the metallurgy, this step may be omitted depending on the condition and type of the metallurgy used. In addition, the method for forming films such as silicon oxide is not limited to the vacuum evaporation method;
(A chemical vapor deposition method (CVD), a sputtering method, an ion blating method, etc. can be used. Furthermore,
The base material used is not limited to aluminum or aluminum alloy, but metals such as stainless steel and nickel alloy, and even plastic can be used.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a rotating polygon mirror manufactured by the method of the present invention, FIG. 2 is a partially enlarged sectional view of the rotating polygon mirror of FIG. FIG. 4 is a schematic configuration diagram showing an example of a vacuum evaporation apparatus for carrying out the method of the invention of C. DESCRIPTION OF SYMBOLS 1...Rotating polygon mirror, 1a...Reflecting surface, 2...A6 coating, 3...5i02 coating, 4...TiO2 coating, 1o
...Vacuum evaporation device, 12...Electron beam heating device, 1
3... Resistance heating device, 14... Monitor glass, 1
5...Dome. valuable figure

Claims (1)

[Claims] A method for manufacturing a high-reflection mirror, comprising forming a silicon oxide film on the surface of a base material, and forming a titanium oxide film on the silicon oxide film.