BMW 325Ci Owner's Manual page 191

Interior rearview mirror with automatic dimming feature
T h e int erior re arvie w mirror w ith a uto -
m atic dim min g fe ature re d u c e s blin din g
fro m follo w in g traffic b y a d a p tin g th e
int e n sity of th e re fle ct e d im a g e s to
c orre s p o n d to le v els of lig ht re gist ere d
b y th e u nit's s e n s ors. T h e mirror re v erts
to its u n dim m e d s e ttin g a s s o o n a s th e
lig ht s o urc e dis a p p e ars. O n e la m p
s e n s or is m o u nt e d o n th e fro nt of th e
mirror h o u sin g. T his s e n s or, w hic h is
dire ct e d for w ard , m e a s ure s lig ht int e n -
sity in th e are a a h e a d of th e v e hicle .
T h e s e c o n d s e n s or is int e grat e d w ithin
th e mirror's gla ss. T h e ele ctro nic
c o ntrol syst e m c o m p are s th e lig ht
int e n sity fro m fro nt a n d re ar. T h e differ-
e n c e pro vid e s th e b a sic p ara m e t er
u s e d to m o d ulat e a n ele ctric al c urre nt
a n d in d u c e c h e mic al c h a n g e s in a
s e mis olid la y er in c orp orat e d in th e le n s.
T h e s e mis olid re a cts c h e mic ally to this
ele ctric al c urre nt, th u s pro vidin g
dim min g of th e mirror thro u g h a n infi-
nit ely -v aria ble ra n g e (ele ctro c hro mic
t e c h n olo g y).
A s a re s ult, it is n o lo n g er n e c e ss ary to
dim th e mirror m a n u ally, a n d th e driv er
c a n c o n c e ntrat e c o m ple t ely o n traffic
c o n ditio n s.
Rain sensor
* *
D e p e n din g o n th e d e gre e of w e tn e ss o n
th e w in d s hield , th e rain s e n s or c o ntrols
th e o p eratio n of th e w in d s hield w ip ers.
Infrare d lig ht is c arrie d alo n g th e s urfa c e
of th e w in d s hield in a n o p tic al c o n d u ctor
in s u c h a m a n n er th at it is re fle ct e d
c o m ple t ely w h e n th e w in d s hield is dry.
T h e q u a ntity of re fle ct e d lig ht is
m e a s ure d . If th ere is m oisture o n th e
gla ss, th e a m o u nt of lig ht re fle ct e d is
re d u c e d sin c e th e infrare d lig ht at th e
s urfa c e of th e w in d s hield c a n e s c a p e .
T h e q u a ntity of re fle ct e d lig ht is th u s a
m e a n s of g a u gin g th e d e gre e of w e tn e ss
o n th e w in d s hield . W h e n th e syst e m is
s e t to th e "Int er mitt e nt " w ip er s p e e d , th e
w ip ers re a ct im m e diat ely – if w at er is
s pla s h e d o nto th e w in d s hield b y v e hicle s
tra v elin g a h e a d of y o u, for e x a m ple . A s a
re s ult, th e rain s e n s or pro vid e s a c o ntri-
b utio n to drivin g s afe ty a n d c o mfort.
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