Reflector with a resistant surface

Details Reflector with a resistant surface Reflector with a resistant surface

2000-05-10

2001-10-30

Spyrou, Cassandra (Department: 2872)

Optical: systems and elements

Mirror

With support

C359S884000

Reexamination Certificate

active

06310737

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a reflector with high total reflection, resisting mechanical stress and comprising a reflector body on which the following components are superimposed,
a) a functional coating,
b) a reflection layer structure containing a reflecting layer and a transparent layer.
The invention relates also to the use of such reflectors.
2. Background Art
It is generally known to produce strips of highly reflective materials such as e.g. high purity aluminium or AlMg alloys based on aluminium with a purity level of 99.8% and higher, such as e.g. 99.9%, and to produce roll surfaces that create diffuse or directional reflection, depending on the application. It is also known, in order to increase the directional reflection (degree of reflection), to brighten the surfaces of such strips chemically or electrolytically and subsequently to provide them with a protective, e.g. 1.5 &mgr;m thick layer by anodic oxidation.
The known processes have the further disadvantage that high purity and expensive brightening alloys based on high purity aluminium have to be employed. The anodic oxide layer causes the degree of reflection to be lowered and, as a result, both the total reflection and the directional reflection, this due to absorption and diffuse light scattering in particular in the oxide layer. This represents a loss of energy.
Known from EP-A-0 495 755 are items with surfaces of aluminium which are suitable for depositing layer systems from the gas phase onto these surfaces. Anodising the surface is dispensed with and a layer system is described comprising e.g. an adhesive layer, such as a ceramic layer, a light reflecting layer, such as a metallic layer e.g. of aluminium and one or more transparent protective layers e.g. of the oxides, nitrides or fluorides of magnesium, titanium or praseodymium. Such layer systems exhibit a high degree of reflection. Such a layer system, however, has the disadvantage of being very sensitive to mechanical effects.
EP-A-0 586 943 describes the precipitation of a reflection layer which is based on aluminium and superimposed on this a gel film that has been deposited on the aluminium by a sol-gel process. The reflection is achieved by a layer system comprising layers of silicon oxide, metal, silicon dioxide and titanium dioxide. This is also a possibility for achieving reflecting aluminium-based materials. The layer structure described in EP-A 0 568 943 is not resistant to mechanical stress to the desired degree.
BROAD DESCRIPTION OF THE INVENTION
The object of the present invention is to avoid the above mentioned disadvantages and to propose reflectors with outer layers that are insensitive to external mechanical stress and are characterized by a high resistance to wiping.
That objective is achieved by way of the invention in that the reflection layer structure comprises a reflecting layer and a protective layer, in the form of a silicon oxide of general formula SiO
x
where x represents a number from 1.1 to 2.0, or in the form of an aluminium oxide of thickness 3 nm or greater, and the protective layer as the layer lying on the surface protects the underlying layers against mechanical damage, and the protective layer exhibits no surface damage in the wipe test according to DIN 58196 after 50 test cycles each of 100 wiping strokes.
The protective layer is, analogously, a transparent layer.
Usefully the minimum thickness of the protective layer amounts to 3 nm. The maximum thickness of the protective layer may e.g. be 1000 nm, advantageously 400 nm. The thickness of the protective layer is preferably 40 nm or less, in particular 20 nm and less. In the present description of the invention the letters nm stand for nanometer.
In a further version the thickness of the protective layer can also be defined by its optical thickness (or depth). The optical thickness is preferably described by the formula n·d=&lgr;/2±40 nm. The optical thickness may also be a multiple thereof expressed by the formula n·d=(k·&lgr;/2)±40 nm, where k is a natural number such as 2, 3, 4, 5, 6. 7, 8, 9 or 10. In this formula n stands for the index of refraction and d the geometric thickness. The symbol &lgr; stands for the intensity maximum of the wave lengths of the reflected electromagnetic radiation. In the case of visible light &lgr; lies in the region of approximately 550 nm. As mentioned above the optical thickness of the protective layer may vary according to the equation (k·&lgr;/2)±40 nm.


REFERENCES:
patent: 5216551 (1993-06-01), Fujii
patent: 5361172 (1994-11-01), Schissel et al.
patent: 5403657 (1995-04-01), Textor et al.
patent: 5424876 (1995-06-01), Fujii
patent: 5527562 (1996-06-01), Balaba et al.
patent: 5527572 (1996-06-01), Textor et al.
patent: 5582863 (1996-12-01), Textor et al.
patent: 5583704 (1996-12-01), Fujii
patent: 5663001 (1997-09-01), Textor et al.
patent: 5978133 (1999-11-01), Gillich
patent: 0358011 (1989-08-01), None
patent: 0456488 (1991-11-01), None
patent: 0495755 (1992-07-01), None
patent: 0568943 (1993-11-01), None
patent: 0610831 (1994-02-01), None
patent: 1507532 (1978-04-01), None
patent: 2267509 (1993-12-01), None
patent: 2292751 (1996-06-01), None
patent: WO 97/01775 (1997-01-01), None
Hass et al., Applied Optics, vol. 14, No. 11, (Nov. 1975), pp. 2639 to 2644.

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