JPH06208076A - Metallic rotary polyhedral mirror - Google Patents

Abstract

PURPOSE:To provide the metallic rotary polyhedral mirror having excellent surface mechanical strength and environmental resistance and high reflectivity. CONSTITUTION:The metallic rotary polyhedral mirror 1 made of aluminum or aluminum alloy is an octahedron and mirror finished surfaces are formed on its peripheral surfaces by machining, etc. Intermediate layers 2, metallic reflection layers 3 and protective layers 4 are successively formed by a vacuum vapor deposition method on the mirror finished surfaces of the metallic rotary polyhedral mirror 1. These intermediate layers 2 are Cr layers of <=50 and <=100nm film thickness, the metallic reflection layers 3 are Cu layers of >=100nm and <=150nm film thickness and the protective layers 4 are Al2O3 layers of >=150nm and <=200nm film thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary polygon mirror used as a reflecting mirror for copying machines, facsimiles, laser beam printers, etc., which has excellent mechanical strength and durability.
The present invention relates to a high-reflectance metal rotating polygon mirror in which variations in reflectance are suppressed.

[0002]

2. Description of the Related Art Conventionally, there are metal rotary polygon mirrors such as (a) and (b) described below.

(A) A mirror-protecting film formed by anodizing the cutting mirror surface of a rotating polygon mirror substrate made of aluminum or aluminum alloy to form a transparent film (JP-A-58-58).
184903).

(B) At least two metal thin films having a high reflectance are sequentially formed on the mirror surface of the rotating polygon mirror substrate made of metal.
A thin film of a dielectric layer is formed (JP-A-60-195).
502).

[0005]

Among the above-mentioned conventional techniques, (a) has an average reflectance of about 85%, which is a sufficient reflection for speeding up a copying machine or a laser beam printer. In addition, when forming an anodic oxide film on a substrate made of aluminum or aluminum alloy,
If impurities such as Si are present in the rotating polygon mirror substrate or the like, pit-like defects may occur in the anodic oxide film. Therefore, the aluminum or aluminum alloy needs to be of high purity. The price of the material becomes expensive, resulting in high cost.

In addition, (B) has a high reflectance, but the mechanical strength of the surface of the metal rotating polygon mirror is low, and the surface is easily scratched when dirt is wiped off.
After being left in a high temperature and high humidity environment at a temperature of 70 ° C. and a relative humidity of 85% for 100 hours, the product was taken out and the surface condition was observed. As a result, a pit-like discoloration point was generated on the surface, and the environment resistance was poor.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and realizes a metal rotary polygon mirror having a high reflectance with excellent surface mechanical strength and environment resistance. The purpose is to do.

[0008]

In order to achieve the above-mentioned object, the rotating polygon mirror of the present invention comprises a rotating polygon mirror substrate made of aluminum or an aluminum alloy, and a rotating polygon mirror substrate having a rotating polygon mirror substrate,
A metal rotating polygon mirror having an intermediate layer, a metal reflective layer and a protective layer, wherein the intermediate layer has a film thickness of 50 nm or more 100
nm or less chrome layer, the metal reflection layer has a thickness of 100 nm
A copper layer having a thickness of 150 nm or less and the protective layer having a thickness of 150 n
consisting of an aluminum oxide layer of m or more and 200 nm or less,
The wavelength used is 640 nm or more.

[0009]

An intermediate layer having a thickness of 5 is formed between the mirror surface of the rotating polygon mirror substrate made of aluminum or aluminum alloy and the copper layer having a thickness of 100 nm or more and 150 nm or less, which is a metal reflection layer.
Since the chromium layer having a thickness of 0 nm or more and 100 nm or less is provided, the adhesion between the mirror surface and the metal reflection layer becomes strong. Further, since the copper layer has a reflectance of 90% or more with respect to a light beam having a wavelength of 640 nm or more, it is not necessary to form an increased reflection layer.

Further, since an aluminum oxide layer having a film thickness of 150 nm or more and 200 nm or less is provided as a protective layer, the surface has a high mechanical strength and is excellent in environmental resistance. Therefore, the copper layer having a relatively low surface hardness. It also has the effect of protecting the surface of, and suppressing variations in reflectance with respect to the incident angle of light rays. In addition, even when the film is formed by a normal vacuum evaporation method, the filling factor is 0.95, which is higher than that of other dielectrics, and the gas has reactivity with the copper surface, such as water vapor and oxygen in the air. In addition to improving the barrier property, the change in the refractive index over time is small, so that the decrease in the refractive index over time of the reflective layer is suppressed.

[0011]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing about half of a rotary metal polygon mirror according to an embodiment of the present invention.

As shown in FIG. 1, the rotating polygon mirror base body 1 made of aluminum or aluminum alloy is an octahedron, and a mirror surface is formed on its peripheral surface by cutting or the like. On the mirror surface of the rotating polygon mirror substrate 1, an intermediate layer 2, a metal reflection layer 3 and a protective layer 4 are sequentially formed by a vacuum vapor deposition method.

The thickness of the intermediate layer 2 is 50 nm or more and 100 nm.
It is the following Cr layer. If the thickness of the Cr layer is less than 50 nm, the durability is insufficient, and if it is greater than 100 nm, the film is cracked and the vapor deposition property is poor.

The metal reflective layer 3 has a thickness of 100 nm or more.
It is a Cu layer of 50 nm or less. Cu layer thickness is 100n
When it is less than m, the reflectance is lowered, and when it is more than 150 nm, it takes a long time for vapor deposition, resulting in poor productivity.

The protective layer 4 has a thickness of 150 nm or more and 200
Al ₂ O ₃ layer having a thickness of nm or less. If the thickness of the Al ₂ O ₃ layer is less than 150 nm, the durability is insufficient, and
When it is larger than nm, the optical characteristics such as the reflection characteristics including the incident angle dependency become insufficient.

In the above-mentioned embodiment, the rotating polygon mirror base body is an octahedron, but it is not limited to this and may be a polyhedron other than the octahedron. (Example 1) A film having a thickness of 50 nm was sequentially formed as an intermediate layer on a mirror-cut octahedral aluminum rotating polygon mirror substrate.
Cr layer, a Cu layer having a thickness of 100 nm as a metal reflection layer,
As a protective layer, an Al ₂ O ₃ layer having a film thickness of 150 nm was formed to obtain a metal rotating polygon mirror. The film forming conditions for the intermediate layer, the metal reflective layer and the protective layer are as shown in Table 1.

[0018]

[Table 1] (Example 2) On a mirror-cut hexahedral aluminum polygonal rotary polygon mirror substrate, a Cr layer having a thickness of 100 nm as an intermediate layer and a Cu layer having a thickness of 150 nm as a metal reflection layer were sequentially formed by a vacuum deposition method. 200nm thickness as protective layer
Al ₂ O ₃ was formed to obtain a metal rotating polygon mirror. The film forming conditions for the intermediate layer, the metal reflection layer and the protective layer are as shown in Table 2.

[0019]

[Table 2] (Comparative Example 1) Explaining Comparative Example 1, as shown in FIG. 2, the mirror-cut Al rotating polygon mirror base 11 is an octahedron, and the peripheral surface thereof has a mirror surface. On the mirror surface of the rotating polygon mirror substrate 11, a Cr layer having a film thickness of 50 nm as the intermediate layer 12, a Cu layer having a film thickness of 100 nm as the metal reflection layer 13, and a reflection increasing layer 14 are sequentially formed by a vacuum evaporation method.
As an Al ₂ O ₃ layer having a film thickness of 105 nm and a TiO ₂ layer having a film thickness of 125 nm as the uppermost layer 15, a metal rotating polygon mirror was obtained. Table 3 shows film forming conditions for the intermediate layer 12, the metal reflection layer 13, the increased reflection layer 14, and the uppermost layer 15.

[0020]

[Table 3] (Comparative Example 2) Explaining Comparative Example 2, as shown in FIG. 3, a mirror-cut Al rotating polygon mirror base 21 is a hexahedron, and its peripheral surface has a mirror surface. An Al ₂ O ₃ layer having a film thickness of 90 nm was formed as the anodic oxide film 22 on the mirror surface of the rotary polygon mirror substrate 21 to obtain a metal rotary polygon mirror. The anodic oxide film 22 is formed under the following conditions: a direct current of 20 V is applied between the rotating polygon mirror substrate 21 and the cathode immersed in a solution having a sulfuric acid concentration of 15% and a liquid temperature of 18 ° C. An electric current was applied until an Al ₂ O ₃ layer having the above film thickness was obtained, and a metal rotating polygon mirror was obtained. Performance comparisons were made for the metal rotating polygon mirrors of the above-described examples and comparative examples.

For the performance evaluation of reflectance, the measurement wavelength 67
FIG. 4 shows the relationship between the incident angle at 5 nm and the reflectance of S-polarized light.
And the spectral reflectance of the S-polarized component at an incident angle of 12 ° is shown in FIG.

As is clear from FIG. 4, the reflectances of Examples 1 and 2 are 95% or more, and there is little variation in the reflectance even if the incident angle changes. Further, as is clear from FIG. 5, the reflectance for light with a wavelength of 640 nm or more is 9
It has a high reflectance of 5% or more. Next, regarding the quality performance evaluation, the environment resistance, the surface strength, and the peeling test were respectively performed by the test methods described below.

Regarding the environmental resistance, each rotary polygon mirror was left for 100 hours in a high temperature and high humidity environment at a temperature of 70 ° C. and a relative humidity of 85%, and then taken out to visually check the appearance change and measure the reflectance. It was

Regarding the surface strength, a lens cleaning paper (using "Zasper (R)" manufactured by OZU) is used.
Solvent (70 vol% ether: 30 vol methanol
%), The lens cleaning paper was pressed against the surface of the metal rotary polygon mirror at a pressure of ² kg / cm ² , and after 10 reciprocations, the presence or absence of scratches on the surface was visually confirmed.

In the peel test, an adhesive tape (using "Cellotape (C)" manufactured by Nichiban Co., Ltd.) was brought into close contact with the surface of the metal rotary polygon mirror and quickly peeled off, and the presence or absence of peeling on the surface was visually confirmed. . The results of the above tests are shown in Table 4.

In Table 4, the fluctuation amount of reflectance depending on the incident angle is from 0 ° to 7 ° at the incident angle at a wavelength of 675 nm.
It is the difference between the maximum value and the minimum value of the S-polarized reflectance when changing to 0 °.

[0027]

[Table 4] As is clear from Table 4, the metal rotary polygon mirrors of the respective examples are excellent in surface mechanical strength and environment resistance, and have high reflectance and small variation in reflectance.

[0028]

Since the present invention is configured as described above, it has the following effects.

The reflectance of the surface is as high as 90% or more, and the dispersion of the S-polarized reflectance is 2.3% or less when the incident angle of light rays is in the range of 0 ° to 70 °, which is excellent optical characteristics.

Further, since the protective layer is an aluminum oxide layer having a high filling rate and a high hardness, the mechanical strength of the surface is excellent, and the surface may be wiped to remove dirt, or scratches may be generated during assembly. In addition, it is excellent in environment resistance and its change in refractive index with time is small.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing about half of a metal rotating polygon mirror of an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing about half of a metal rotating polygon mirror of Comparative Example 1.

FIG. 3 is a schematic cross-sectional view showing about half of a metal rotating polygon mirror of Comparative Example 2.

FIG. 4 is a graph showing the relationship between the light incident angle and the S-polarized reflectance of the metal rotary polygon mirrors of Examples and Comparative Examples.

FIG. 5 is a graph showing the spectral reflectance of the S-polarized component at an incident angle of 12 °.

[Explanation of symbols]

 1 rotating polygon mirror substrate 2 intermediate layer 3 metal reflection layer 4 protective layer

Claims (1)

[Claims] 1. A metal rotary polygon mirror in which an intermediate layer, a metal reflection layer and a protective layer are sequentially formed on a mirror surface of a rotary polygon mirror substrate made of aluminum or an aluminum alloy, wherein the intermediate layer has a film thickness of 50 nm. A chromium layer having a thickness of 100 nm or less and 100 nm or less, a copper layer having a film thickness of 100 nm or more and 150 nm or less, and a protective layer having a film thickness of 150 nm or more and 200 nm or more
It consists of the following aluminum oxide layers, and its usable wavelength is 6
A metal rotating polygon mirror having a thickness of 40 nm or more.