Safety Protected Electrochromic Rearview Mirrors

Should a rearview mirror shatter under impact in an accident, it is important that occupants are not injured by glass fragments that scatter about the vehicle, and that occupants are not injured should they contact shattered glass retained in the mirror assembly. For decades, the safety of prismatic interior mirrors, and of flat and convex exterior mirrors, has been assured by use of antiscattering backings such as tapes or elastomeric layers which are firmly bonded to the rearmost surface of a single mirror glass element. Such backing materials are designed to prevent fragments detaching from the mirror should the glass shatter, and to securely retain shattered glass such that shards do not slide or otherwise displace so as to create a sharp edge or protrusion likely to lead to a lacerative injury. Recently, electro-optic mirrors have been introduced for use both on the interior and exterior of automobiles. Several constructions involve an electrochromic material sandwiched between two glass elements. This paper describes use of tear-resistant, transparent polymer layers to ensure that multiglass mirror constructions have a safety performance, under impact, at least equivalent to that currently delivered by single glass element rearview mirrors in widespread use. Regulatory and industry safety standards and specifications are discussed, safety statistics from national accident records are briefly reviewed, and the impact performance of safety protected electrochromic rearview mirror assemblies is described.