Technical information
43
7.
9
.
3
.
B
ac
k
re
fl
ect
i
on on t
h
e
l
am
p
Th
e
l
um
i
na
i
re
d
es
ig
n nee
d
s to ensure t
h
at no ra
di
a
-
tion is re
f
lected back onto the lam
p
as this can cause
thermal loads on sensitive
p
arts o
f
the lam
p
which
normall
y
leads to unusuall
y
earl
y
f
ailures. For a lamp
w
i
t
h
a quartz arc tu
b
e, t
hi
s ma
y
l
ea
d
to t
h
e expans
i
on
o
f
the tube or to a leak in the pinch area
.
In lamps with ceramic arc tubes, the so-called sealing
area at the ends o
f
the capillaries is particularl
y
sensi
-
t
i
ve:
h
ere over
h
eat
i
n
g
can
l
ea
d
to
i
ncrease
d
c
h
em
i
ca
l
reactions and then to cracks and lamp
f
ailures. A
f
ur-
t
he
r
sens
i
t
i
ve component
i
s t
h
e
l
amp
’
s
g
etter.
To establish whether or not the luminaire desi
g
n could
cause
i
mperm
i
ss
ibl
e t
h
erma
l
d
ama
g
e, t
h
e temperature
on the outer bulb and the socket or the
p
inch area
f
irst
n
ee
d
to
b
e measure
d
as state
d
i
n t
h
e cata
l
o
g
ues, see
also
sec
t
io
n 7.1
.
However it should be noted that even i
f
the tem
p
era-
tures measured on the outside of the lam
p
lie within
the de
f
ined tolerance values, this does not necessaril
y
m
ean t
h
at t
h
ere
i
s no over
h
eat
i
n
g
i
ns
id
e t
h
e
l
amp.
T
hose sur
f
aces closely surroundin
g
the lamp, such as
the re
f
lector neck, di
ff
user tube and
g
lare shield caps,
re
f
lect back on the lam
p
. Likewise, elli
p
tical re
f
lectors
radiate back onto the lamp i
f
the burner is not posi-
tioned correctl
y
in the burner point o
f
the re
f
lector.
In these cases the lamps may also su
ff
er dama
g
e even
i
f
the tem
p
eratures measured on the outside o
f
the
lam
p
lie within the de
f
ined tolerance values
.
T
he
f
ollowin
g
recommendations are made:
T
o avoid
g
lare, the
g
lare shield caps o
f
ten used
f
o
r
h
a
l
o
g
en
b
u
lb
s or t
h
e
gl
are s
hi
e
ld
r
i
n
g
s on
l
amps
with double-sided burners such as H
CI
®
ma
y
not be
u
sed. Instead, the
g
lare protection
f
or these lamps is
e
ff
ected by usin
g
e.
g
. honeycomb
f
ilters or “anti-
g
lare
baff
l
es
”
o
r “h
oods
”
a
tt
ac
h
ed
t
o
th
e
ou
t
s
i
de
of
th
e
lu
m
i
n
ai
r
e.
Th
e
gl
are can a
l
so
b
e re
d
uce
d
b
y us
i
n
g
protecte
d
lamps, such as H
CI
®
-TX
/
P
,
because the fact that there
is no
f
ront
g
lass at the luminaire means that there is no
re
f
lex
g
lare on the
f
ront
g
lass
.
T
o achieve a homo
g
enous colour radiation,
f
acetted
a
n
d
m
a
tt r
ef
l
ec
t
o
r
s
s
h
ou
l
d
be
used
. Di
ffuse
r t
ubes
aroun
d
t
h
e
l
amp are not su
i
ta
bl
e.
In lamps with a re
f
lector casin
g
, the re
f
lector should
be smoothly cut at the opening and should not have a
neck
.
It i
s
m
o
r
e
d
i
ff
i
cu
lt in
cases
wh
e
r
e
th
e
r
ef
l
ec
t
o
r it
se
l
f
com
p
rises the outer
p
art o
f
the luminaire. I
f
a re
f
lector
n
eck is used here, e.
g
. to prevent the emission o
f
li
g
ht
scatter, t
hi
s
l
ea
d
s, e.
g
.
i
n ceram
i
c
l
amps to a
high
er
tem
p
erature
l
oa
d
i
n t
h
e soc
k
et-
b
ase
d
ca
pill
ar
i
es.
T
he extent o
f
the dama
g
e depends on the
f
ollowin
g
p
arameters
:
• Extent o
f
the spatial coverin
g
o
f
the re
f
lector neck
an
d
t
h
e cap
ill
ar
i
es:
l
ess
i
s
b
etter
•
The diameter o
f
the re
fl
ector neck: bi
gg
er is better
• L
e
v
e
l
of
r
ef
l
ec
ti
o
n
of
th
e
r
ef
l
ec
t
o
r n
ec
k: m
a
tt i
s
be
tt
e
r th
a
n mirr
o
r
ed
• Overall volume of the reflector: bi
gg
er is bette
r
T
he service lives stated b
y
OS
RAM onl
y
appl
y
to
lam
p
s o
p
erated in luminaires that do not re
f
lect back
o
n the lamp. They are based on a switchin
g
rhythm
11 h
O
N
,
1 h
O
FF.
Figure 39: Projection of the condensate by the refl ector
Fi
g
ure 40: Example o
f
a re
f
lector with a re
f
lector nec
k
o
ver the thermally critical parts of the lamp
.
n
ec
Reflec
t
o
r
k
S
ealin
g
are
a
e
G
ett
e
r
C
apillarie
s