Patent ID: 8416486

Claim:
An electrochromic mirror stack comprising a reflective surface for reflecting light, a layered electrochromic device parallel therewith variable between a colored and a bleached state, said device comprising a functional stack of at least an ion conductor layer, two electrochromic layers in contact with said ion conductor layer and one or two transparent conductive layers in contact with either one or both of said electrochromic layers, and an optical layer parallel with said reflective surface, wherein at least one of the layers in the functional stack has a pattern made up of identifiable features and wherein the total local optical length of said layers in the functional stack along a normal to said reflective surface varies in a plane perpendicular to said normal in the pattern of which feature sizes along the principal axes of said pattern are larger than 1 micron and smaller than 950 micron so as to average out the interference of the light that occurs when the light striking the mirror stack is reflected such that a reflectogram scan taken over a spot with a diameter substantially larger than said feature sizes in a wavelength range starting from 450 up to 650 nm has differences between any local maximum and its subsequent local minimum of less than 15% of reflectance when said electrochromic device is in the bleached state.