Mirrors, anti-dazzle

It s quite common when driving at night to be dazzled by the lights of the vehicle behind as they reflect from the driver s new-view or door mirror. We can prevent the dazzle by forming a layer of coloured material over the reflecting surface within an electrochromic mirror. Such mirrors are sometimes called smart mirrors or electronic anti-dazzle mirrors . 

We can now explain how an electrochromic car mirror operates. The mirror is constructed with II in its colourless form, so the mirror functions in a normal way. The driver activates the mirror when the anti-dazzle state of the mirror is required, and the coloured form of methylene blue (MB+) is generated oxidatively according to Equation (7.24). Coloured MB+ blocks out the dazzling reflection at the mirror by absorbing about 70 per cent of the light. After our vehicle has been overtaken and we require the mirror to function normally again, we reduce MB+ back to colourless MB0 via the reverse of Equation (7.24), and return the mirror to its colourless state. These two situations are depicted in Figure 7.6. 

The materials that change colour on passing a charge are called electrochromes, and these can be classified into three groups. In the first type the colouring species remain in solution in the second type the reactants are in solution but the coloured product is a solid the third type are those where all the materials are solids, e.g. in films. The first type is used in car, anti-dazzle, rear-view mirrors, the second type in larger mirrors for commercial vehicles and the third type in smart windows (see section 1.5.4.2). 

The main application areas for electrochromic systems are in electrically switchable rear-view car mirrors for anti-dazzle, in glazing units for temperature and light control and in visnal displays. The main advantage offered by electrochromic systems in the first two of these applications is the fact that the cells can be made very large, i.e. one cell can comprise a whole glazing unit. 

Rearview mirror External rearview mirror electric drive, electrical heating defrosting, anti dazzle type, the left and right side are all convex mirror, with a radius of curvature of 1400mm. The internal rearview mirror manual, anti dazzle type, plane endoscope. 

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