Reflecting mirror for an automobile

• US 4,673,248 A
• Filed: 08/25/1986
• Issued: 06/16/1987
• Est. Priority Date: 04/11/1983
• Status: Expired due to Fees

• Current Assignee: Nippon Soken, Inc.
• Original Assignee: Nippon Soken, Inc.
• Inventors: Hattori, Tadashi, Ueno, Yoshiki, Taguchi, Takasi
• Primary Examiner(s): ARNOLD, BRUCE
• Application Number:
  US06/902,028
• Time in Patent Office: 295 Days
• Field of Search: 350/164, 350/166, 350/482, 350/278
• US Class Current: 359/584
• CPC Class Codes: B60R 1/083 Anti-glare mirrors, e.g. "day-night" mirrors
• CPC Class Codes: G02B 5/0858 the reflecting layers comprising a single metallic layer with one or more dielectric layers
• CPC Class Codes: G02B 5/0883 with a refractive index gradient rugate filters G02B5/289

Abstract

A reflecting mirror for use as a rearview mirror in an automobile, the mirror having a plurality of thin layers arranged on a glass plate. One of the layers is made of a transparent dielectric material having a refractive index which is not less than a refractive index of WO₂ and the other is made of a metal material having a reflecting factor ranging between 50-70%. The light introduced into the mirror is reflected at different borders formed in the mirror between the layers so as to provide lights of different phases. Therefore, there is an interference, and, consequently, the mirror provides a certain selected tone in accordance with the value of the optical thickness of the transparent dielectric layer, resulting in an anti-glare effect and a deep color.

Claims

1. A reflecting colored mirror for an automobile having anti-glare effects comprising:

an opaque thin metal layer having a reflecting factor ranging from 50% to 70%, said metal layer defining a first light reflecting surface; and

a thin layer made of a transparent dielectric material, said dielectric layer being formed on said surface of said thin metal layer, said dielectric layer forming a second light-reflecting surface on a surface of said dielectric layer opposite said first light-reflecting surface of said thin metal layer, the thickness of said dielectric layer being sufficiently thin to allow the surface of said dielectric layer to have negligible roughness resulting in good interference for selected frequencies of visible light, said thickness, taken into consideration with said metal layer reflecting factor and said dielectric layer refractive index, causing a required interference effect by light reflected from said first and second light-reflecting surface so that the reflecting factor of said mirror is from 38% to 65%.

2. A reflecting mirror according to claim 1, wherein said transparent dielectric material is one of WO₂, ZrO₂, CeO₂ and TiO₂.

3. A reflecting mirror according to claim 2, wherein said transparent dielectric material is TiO₂, and said metal layer is nickel-chrome alloy.

4. A reflecting mirror according to claim 1, further comprising a substratum layer having a surface, said thin metal layer and said dielectric layer being formed on said surface of said substratum layer by one of vacuum deposition and sputtering.

5. A reflecting mirror according to claim 1, further comprising a transparent substratum layer having a surface, and said dielectric layer being formed on said surface of said substratum layer.

6. A reflecting colored mirror for an automobile having an anti-glare characteristic comprising:

a glass layer having a surface;

a auxiliary dielectric layer having a reflective index lower than the reflective index of said glass layer and disposed on said surface of said glass layer;

a auxiliary dielectric layer having a refractive index lower than the refractive index of said glass layer and disposed on said surface of said glass layer;

a main dielectric layer having a refractive index which is greater than said glass layer and being disposed on said auxiliary dielectric layer, said main dielectric layer and said auxiliary dielectric layer defining a first light-reflecting boundary; and

an opaque thin metal layer having a reflecting factor of from 50% to 70%, being formed on said main dielectric layer, said metal layer and said main dielectric layer defining a second light-reflecting boundary, the thickness of said main dielectric layer being sufficiently thin to allow the surface of said main dielectric layer to have negligible roughness resulting in good interference for selected frequencies of visible light, said thickness, taken into consideration with said metal layer reflecting factor and said main dielectric layer refractive index, causing a required interference effect by light reflected from said first and second light-reflecting boundaries so that the reflecting factor is from 38% to 65%.

7. A reflecting mirror according to claim 6 wherein said transparent main dielectric material is one of WO₂, ZrO₂, CeO₂, and TiO₂, and said auxiliary dielectric material is one of LiF, MgF₂, and SiO₂.