Rain Sensor; Automatic Dimming Feature - BMW SERIE 7 2000 Manual

Rearview mirror with automatic dimmer
192n
The interior rearview mirror with auto-
matic dimming feature reduces glare
from following traffic by adapting the in-
tensity of the reflected images to corre-
spond to levels of light registered by
the unit's sensors. The mirror reverts to
its undimmed setting as soon as the
light source disappears. One of these
sensors is mounted on the front of the
mirror housing and is designed to mon-
itor light levels in the area forward of
the vehicle. The second sensor is inte-
grated within the mirror's glass. The
electronic control system operates by
comparing the respective levels of lumi-
nous intensity in front of and behind the
car. The difference provides the basic
parameter used to modulate an electri-
cal current and induce chemical
changes in a semisolid layer incorpo-
rated in the lens.
The semisolid reacts chemically to this
electrical current, thus providing infi-
nitely-variable dimming of the mirror
(electrochromic technology).
As a result, it is no longer necessary to
dim the mirror manually, and the driver
can maintain full concentration on traf-
fic.

Rain sensor

*
The rain sensor controls windshield
wiper operation, depending on how wet
the windshield is.
Infrared light is carried along the sur-
face of the windshield in an optical con-
ductor in such a manner that it is re-
flected completely when the windshield
is dry. The quantity of reflected light is
measured.
If there is moisture on the glass, the
amount of light reflected is reduced
since the infrared light at the surface of
the windshield can escape. The quan-
tity of reflected light is thus a means of
gauging the degree of wetness on the
windshield.
Online Edition for Part No. 01 41 0 004 597 - © 08/99 BMW AG