Rearview mirror for motor vehicles

DETAILED DESCRIPTION An object of the present invention is to provide a mirror that retains a predefined tint, even under different viewing angles, and especially of creating a rearview mirror for motor vehicles of the type described that is configured so as to be especially reliable for use in motor vehicles, also when it comes to the modern, demanding requirements made of its reflective properties.
The present invention provides a rearview mirror wherein the layer system comprising the intermediate layer arranged on the layer substrate and the reflective mirror coating arranged thereupon is configured in such a way that the magnitude of the parameter for the coloring C= {square root over (a.
sub.
0.
sup.
2+b.
sub.
0.
sup.
2)} is greater than 5 and in that the color change .
DELTA.
E resulting from a tilting of the rearview mirror by 45.
degree.
from the perpendicular viewing angle as a function of the magnitude of the color value a according to CIE is not greater than .
DELTA.
E.
ltoreq.
1/2(|a.
sub.
0|-8) wherein a.
sub.
0.
ltoreq.
-20, .
DELTA.
E.
ltoreq.
6 wherein -20.
ltoreq.
a.
sub.
0.
ltoreq.
0 and .
DELTA.
E.
ltoreq.
1/2(a.
sub.
0+12), especially .
ltoreq.
1/2(a.
sub.
0-3), preferably .
ltoreq.
1/3(a.
sub.
0-3), advantageously .
ltoreq.
1/6(a.
sub.
0-3), wherein a.
sub.
0.
gtoreq.
0.
The definition makes use of the color coordinates L, a and b in the so-called L a b color space as is commonly employed for the quantitative and/or qualitative characterization of color properties and stipulated by the International Commission on Illumination (Commission Internationale de l'Eclairage CIE).
The color coordinates that are characteristic for the rearview mirror are measured with perpendicular light incidence (L.
sub.
0, a.
sub.
0, b.
sub.
0) on the rearview mirror on the one hand and with light incidence at an angle of 45.
degree.
(L.
sub.
45, a.
sub.
45, b.
sub.
45) on the other hand.
The measured values thus obtained were used to determine the differential values on the basis of the relationships .
DELTA.
L=L.
sub.
45-L.
sub.
0, .
DELTA.
a=a.
sub.
45-a.
sub.
0 and