4. Incandescent and Halogen Lamps
Contents
44.1
1 History
4.2 Physical Fundamentals
4.33 Co
Construction
s uc o
4.4 Lifetime
4.5 Halogen Incandescent Lamp
4.6 Interference Filter
4.7 Types of Halogen Lamps
4 8 New Developments
4.8
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 1
4.1 History
1820
1840
1854
1868
1879
1881
1900
1902
1911
1912
1936
1958
1960
1971
1973
2010
Arthur
A
th d
de lla Ri
Rive observes
b
a glowing
l i Pt
Pt-wire
i in
i vacuum
Joseph Wilson Swan experiments with carbonised paper wires
Heinrich Goebel constructs the first incandescent lamp with a bamboo fiber, which
finallyy leads to the carbon filament lamp
p
Problem: still not sufficiently well evacuated  C + O2  CO2
First fabrication of incandescent lamps by Swan (low lifetime)
Patent of Thomas Alva Edison
Edison improves incandescent lamps by better evacuation of the lamp bulb
 higher lifetime
Demonstration (Presentation) of Edison Lamp at the World Exhibition in Paris
Coil still made from C
S
Searching
hi ffor high
hi h melting
lti metals
t l  Ta,
T W,
W Re,
R O
Os
Winner: Tungsten because of the lowest vapour pressure  lowest blackening
Max Planck: Theoretical basis (Planck's law)
Osmium wire ((Auer and Welsbach))
Ar/N2 filling
Tungsten wire
First lamp with a double coiled filament
First application of Xenon as a filling gas
Halogen cycle (Zubler and Mosby, GE)
First H4 automotive lamp (today also H7)
First halogen lamp with interference filter
I
Incandescent
d
t llamps marketed
k t d as h
heatt b
balls
ll
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 2
4.2 Physical Fundamentals
Energy balance of an incandescent lamp
Input Power
Electromagnetic radiation
Electric
current I
IR
Visible
1.2
Gas losses
Conductivity losses
UV
Tungsten filament with the electrical
1
resistance R
I(  )
V( z)
Electric loss for current I
0.5
 P = U*I = R*I2
V() = Spectral
S t l sensitivity
iti it curve
0.
0
500
1000
1500

200
380
Incoherent Light Sources
Prof. Dr. T. Jüstel
780

z
nm nm
Wavelength
[nm]
Wellenlänge in nm
Spectrum of a glowing filament at about
2000
2000.
T = 2700 K (incandescence)
Chapter Incandescent and Halogen Lamps
Slide 3
4.2 Physical Fundamentals
The black
Th
bl k body
b d radiation
di ti can be
b defined
d fi d as th
the li
light
ht emission
i i iin th
thermall
equilibrium (thermal radiation)
Spectrum of a black body radiator
c1
c2

Le
T
2hc2
3.741832.10-16
Wm2
=
=
= hc/k = 1.438786.10-2 Km
= Wavelength [m]
= Spectral irradiance (radiation density)
= Temperature [K]
4x10
3x10
3
3x10
3
2x10
3
2x10
3
1x10
3
5x10
2
3000K
-1
e
-2
L
c1
1
 5  c 2 / T
λ
e
1
L e [W m nm ]
Planck's radiation law (1900)
3
2500K
2000K
0
200
400
600
800
1000
1200
1400
1600
1800
2000
W avelength [nm]
Light source
Color temperature
S
Sun
5800 K
Studio halogen lamp
3400 K
Halogen lamp
3000 K
Incandescent lamp (bulb)
(b lb) 2700 K
Incoherent Light Sources
Prof. Dr. T. Jüstel
Wien's displacement law
λ max  T  2880 [μm  K]
Chapter Incandescent and Halogen Lamps
Slide 4
4.2 Physical Fundamentals
Incandescent and halogen lamps are spatially and temporally incoherent light
sources
Incoherence
A light bulb radiates incoherent:
the wavelengths of the individual
waves are different or between the
various points of the radiating
surface, there is no fixed phase
relationship
Incoherent Light Sources
Prof. Dr. T. Jüstel
Temporally coherence
A color filter allows only light
of a certain wavelength to
pass through: the radiation is
temporally coherent
(monochromatic)
Spatially and temporally
coherence
Through color filter and
pinhole a small-area,
t
temporally
ll and
d spatially
ti ll
coherent light source of very
low intensity is created
Chapter Incandescent and Halogen Lamps
Slide 5
4.3 Construction
Tungsten filament
Filament is double coiled
Fill gas =
noble gas (Ar,
(Ar Kr,
Kr Xe) + N2
(pressure = 1 bar)
Typical: 80% N2 + 20% Ar
(Mo)
It is coiled initially on Mo,
then Mo is removed
C t t
Contact
Incoherent Light Sources
Prof. Dr. T. Jüstel
Ar
39,9 g/mol
Kr
83,8 g/mol
X
Xe
131 3 g/mol
131,3
/ l
Screw thread = Edison-Type
Bajonett-Type
Diameter in mm
Europe E10 E14 E27 E40
USA
E12 E17 E26 E39
Chapter Incandescent and Halogen Lamps
Slide 6
4.3 Construction
From a glass bulb to an incandescent lamp
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 7
4.3 Construction
Production of tungsten filament
Tungsten production
Filament production
Ores:
W-staves
CaWO4 or (Fe,Mn)WO4
“Scheelite” “Wolframite”
Di ti with
Digestion
ith HCl
MeCl2 + WO3.H2O “Tungstite”
Leaching with NH3
(NH4)10[H2W12O42] “Paratungstate”
600 °C
WO3
Hammering, rolling
W-plates
Pullingg
W-wires
Winding/coiling
W-filament
Doping, H2, 450 °C
-W-metal powder  Pressing + sintering to W-staves
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 8
4.4 Lifetime
Blackening of incandescent lamps
Tungsten which evaporates from the filament condenses
i id off the
inside
th glas
l bulb
b lb
T
Wasser
Os
Re
Ta
W
Tungsten has the lowest vapour pressure of all metals and the highest melting point
of all metals (Tm = 3410 °C),
°C) Carbon (graphite) melts at 3550 °C
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 9
4.4 Lifetime
The hotter is the filament, the more efficient is an incandescent lamp, however
blackening is then also stronger
Operating conditions of an incandescent lamp
represent a compromise between the energy
efficiency  and lifetime t.
Typical values for operation at nominal voltage:
 = 13 lm/W and t = 1000 h
 in K
W
„Hot spot“- mechanism
W i becomes
W-wire
b
thinner
thi
 Resistance increases
 Local output and temperature increase
 Vapour pressure increases
 Burning-out at „hot spot“
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 10
4.5 Halogen Incandescent Lamp
Functional principle
In halogen incandescent lamp tungsten is transported
back to the filament from glass bulb via chemical
transport  Glass bulb remains clear
W
Filling gas = nobel gas + O2 + X2 (X = Br, I)
= Solubility curve
= pW+ pWO+ pWBr+ .....
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 11
4.5 Halogen Incandescent Lamp
Chemical transport in halogen incandescent lamps
The position of the chemical equilibrium
is temperature dependent: W + O2 + X2 ⇌ WO2X2
Halogen-cycle
ΔH 0 ΔS0
l K
lnK

R T
R
van‘t Hoff
W + O2 + X2 ⇌ WO2X2 Chemical transport
lnK
T2 = Wall
 WO2X2(g)
lnK2 > 0
W
Br
=OFilament
lnK = 0
T1
 W(s) + O2(g) + X2(g)
lnK1 < 0
Wendel
1/T1
Incoherent Light Sources
Prof. Dr. T. Jüstel
1/T2
1/T
Chapter Incandescent and Halogen Lamps
Slide 12
4.5 Halogen Incandescent Lamp
Limitation of the W-Recycling
• Although
g W back transport
p
is efficient, no curing
g of the W-filament occurs
• Gaseous W condenses at the cold spot (thickest section due to lowest resistance)
W + ½ O2 ⇌ WO
WO + ½ O2 ⇌ WO2
WO2 + ½ O2 ⇌ WO3
Tungsten crystals
2 W(s) + 3 O2(g) ⇌ 2 WO3(s) ΔH = -764
764 kJ/mol
kJ/ l
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 13
4.5 Halogen Incandescent Lamp
Set of problems with UV-radiation
Due to the higher filament
filament’ss temperature
temperature, halogen incandescent lamps emit also
some of UV-A and UV-B radiation, since the quartz bulb is transparent to UV
radiation.
Transmission spectrum of quartz glass
Transmission and emission spectrum
of Ce3+ doped silica glass
100
Transmission
T
i i spectrum
t
Emission spectrum
1,0
Em
mission intensitty [a.u.]
Transmissio
on (%)
80
60
40
20
0
120
0,8
0,6
0,4
0,2
0,0
140
160
W
Wavelength
l
th nm
Incoherent Light Sources
Prof. Dr. T. Jüstel
180
200
300
400
500
600
700
800
W
Wavelength
l
th [[nm]]
Chapter Incandescent and Halogen Lamps
Slide 14
4.5 Halogen Incandescent Lamp
Advantages over incandescent lamps
In halogen
g incandescent lamp
p remains the (bulb) wall, during
g the chemical
transport, clear
 Reduction of bulb size
 Increase the noble gas pressure
 Lower evaporation rate of tungsten gives a higher lifetime, what gives partly
higher efficiency (higher filament temperature)
T [K]
 [lm/W]
 [%]
2700
2800
3000
3200
3400
13
16
22
29
36
10
11
13
16
20
Incoherent Light Sources
Prof. Dr. T. Jüstel
Incandescent lamp
Typical halogen lamp
Special halogen lamp
((Projectors,
j
TV-studios)
Chapter Incandescent and Halogen Lamps
Slide 15
4.6 Interference Filter
Since incandescent lamps and halogen incandescent lamps emit substantially IRradiation, even higher efficiencies can be achieved by IR filter
Principle on the example of the halogen lamp
Visible light is transmitted
IR light is reflected back to the filament
= 20 lm/W  40 lm/W
Reflecctance
Selective mirror
Interference filter
UV 380
Incoherent Light Sources
Prof. Dr. T. Jüstel
Visible
780
IR
 [nm]
Chapter Incandescent and Halogen Lamps
Slide 16
4.6 Interference Filter
Interference filters consist of a sequence of low-and highly refractive inorganic layers
m.
Constructive interference
High reflectance
Path difference = 2nd - /2
(k+1/2) Destructive interference
Low reflectance
TiO2, ZnS, ... (n = 2.3 – 2.7)
Glass (n = 1.5)
d
......
Incoherent Light Sources
Prof. Dr. T. Jüstel
Visible
Reflection
n
Example: 2nd = 500 nm
Low reflectance
k=0 = 500 nm
k=1 = 500/2 = 250 nm
k=2 = 500/3 = 167 nm
......
High reflectance
m=0 = 500/0.5 = 1000 nm
m=1 = 500/1.5 = 333 nm
m=2 = 500/2.5 = 200 nm
IR
1 Layer
U tto 40 layers
Up
l
200
400
600
800
1000  [nm]
Chapter Incandescent and Halogen Lamps
Slide 17
4.6 Interference Filter
Energy saving filter
VIS
IR
Cold light mirror
Cold
C
ld li
light
ht mirror
i
is
i an inverse
i
energy saving
i filter:
filt
It reflects visible light and let IR radiation pass through.
IR
VIS
C ld li
Cold
light
ht reflector
fl t are nott perfect,
f t i.e.
i deep
d
red
d and
dd
deep bl
blue are visible
i ibl b
behind
hi d th
the llamp
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 18
4.6 Interference Filter
Interference filter as colour filter
Refflexion
Application in light sources and spectrometers
380
780
IR
 [nm]
Lack of blue in emission spectrum  yellow filter
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 19
4.7 Types of Halogen Lamps
Halogen lamps for general lighting
Low-voltage halogen lamps
U = 12, 24 V (Transformator is required)
P = 20 - 50 W
Incoherent Light Sources
Prof. Dr. T. Jüstel
P = 200 - 500 W
U = 230 V
P = U2/R,, i. e. U  R
 R = *l/A
 Longer and thinner filament
 Filament is less stable
 Tfilament is lowered
 decreases in comparison with
low voltage lamps
High-voltage halogen lamps
Outer envelope
(hot & fingerprints)
PAR = Parabolic
reflector lamp
Chapter Incandescent and Halogen Lamps
Slide 20
4.7 Types of Halogen Lamps
Low Voltage vs. High Voltage Halogen Lamps
Lamp type
Low voltage High voltage
Voltage U [V]
12
230
Power P [W]
20
20
Filament length l
[[cm]]
2,21
15,81
Diameter d [μm]
54,1
7,558
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 21
4.7 Types of Halogen Lamps
Car head lights
Drive light (high beam)
Di
Dimmed
dh
head
d li
lights
ht (l
(low b
beam))
Drive light (high beam)
Dimmed head lights (low beam)
High beam
H7-Lamps
(1 Filament)
Incoherent Light Sources
Prof. Dr. T. Jüstel
Low beam
H4-Lamps
(2 Filaments)
Chapter Incandescent and Halogen Lamps
Slide 22
4.7 Types of Halogen Lamps
Halogen lamps SSTV Market (Stage-Studio-TV)
Headlamp
Spherical
mirror
f
Fresnel lens
Original filament
Incoherent Light Sources
Prof. Dr. T. Jüstel
Picture of a filament
Chapter Incandescent and Halogen Lamps
Slide 23
4.8 New Developments
White LEDs are becoming strong competition for halogen incandescent lamp
Light source
Luminous flux
[lm]
Incandescent 60 W 900
Halogen 50 W
1000
LED 2002
125
LED 2013
1000
Efficiency Brightness CRI
[lm/W] [Mcd/m2]
15
10
100
20
20
100
25
3
75
250
10
90
Lifetime
[kh]
1
2
60
60
Costs
[$/Mlm.h]
7.2
63
6.3
6.0
< 1.0
Further development of incandescent and halogen bulbs
Tungsten filament with photonic band structure via
3D-structuring.
Aim: Reduction of the IR-emission and therefore increasingg
the light efficiency.
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 24
4.8 New Developments
Specialties
High performance lamps
(up to 20 kW)
Colored incandescent lamp
(coated with inorganic metal oxides )
with
i h CoAl
C Al2O4
Incoherent Light Sources
Prof. Dr. T. Jüstel
with
i h Fe
F 2O3
Chapter Incandescent and Halogen Lamps
Slide 25
4.8 New Developments
Specialties
op g oof thee lamp
p gglass,
ss, e.g. by Nd2O3 (G
(GE Lighting:
g
g: Reveal
eve ®)
Doping
Aim: Increase of the color temperature without loss of color rendering
Enhancement of the contrast between red and green
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 26
4.8 New Developments
Specialties
2010:
Marketing of incandescent lamps as heatballs,
heatballs as a reaction on the ban
of incandescent lamps driven by the EU
2016:
Ban of halogen lamps implemented
Incoherent Light Sources
Prof. Dr. T. Jüstel
Chapter Incandescent and Halogen Lamps
Slide 27