a method of driving microwave-driven lamps for … · radtech2018 (chicago, il), 9 may 2018, d....
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A METHOD OF DRIVING MICROWAVE-DRIVEN LAMPS FOR IMPROVED PERFORMANCERadTech 2018 (Chicago, IL), 9 May 2018, D. Leonhardt
DC-driven lamps have be adopted for UV curing lamps for many years› Improved equipment (higher efficiency, lighter weight, and more)› More stable UV output for high-speed processes› Slot arcing less of a problem› Doesn’t need multiple versions for 50Hz and 60Hz› More precise power controlContinuous “DC” power causes ‘color separation’ when metal halides are present with vertical bulb› Constant convection creates hot core and cooler surroundings (chimney effect) › Metal halides recombine/dissociate in localized portion of bulb – making two different discharges in bulb› Aka axial segregation, cataphoresis
Color separation leads to increased envelope temperatures and poor optical homogeneity
“DC-like” operation of the additive bulb that still maintains the benefits of the DC power supply and alleviates the inhomogeneity of the color separation
MOTIVATION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20182
Ferroresonant designs› Tried and true design; simple; moderately robust› Heavy step-up transformers for HV› HV is modulated at line frequency
FERRORESONANT AND DC POWER SUPPLIES
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20183
Mag
netro
n C
urre
nt
Time
Legacy System 2
A Mag B Mag
Mag
netro
n C
urre
nt
Time
Legacy System 1
A Mag B Mag
120° out-of phase, rectified by phase180° out-of phase, phase-split
DC designs› Power factor correction built in – extremely high efficiency› No heavy step-up transformers! Weight ~ 25% of ferroresonant design› Can distribute load evenly to bulb
DC POWER SUPPLIES
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20184
Constant current…
Magne
tron
Current
Time
DC
A Mag B Mag
Temperature distribution of additive bulbs in horizontal orientation
FERRORESONANT AND DC POWER BULB OPERATION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20185
DC (Tmax = 925 °C)Legacy 2 (Tmax = 920 °C)
Temperature distribution of additive bulbs in vertical orientation
FERRORESONANT AND DC POWER BULB OPERATION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20186
DC (Tmax = 1156 °C)
Legacy 2 (Tmax = 925 °C)
Temperature distribution and optical appearance of additive bulbs in vertical orientation
FERRORESONANT AND DC POWER BULB OPERATION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20187
DC Legacy 2
Data from iron halide bulb operated by DC power, horizontal compared to vertical orientation
DC OPERATION OF ADDITIVE BULB – BULB PERFORMANCE
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20188
75%
67%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Horizontal Vertical
Rel
ativ
e U
VA
Total UV (201-400nm) Key Band (351-400nm)
> 25% loss of optical output
Iron additive material position>1000 °C, and red in appearance
Mercury discharge primarily, no iron emissions
Briefly reduce power delivery to bulb to ‘mix’ additive but maintain DC operation character › Optimize duration, depth, waveform character and phase relationship
› ~ 80% of modulation required› Magnetron currents ~ 40° out-of-phase
› Keep peak power low, to maximize component life› Other critical parameters to optical output
› Rise and fall of driving current waveform› Duty cycle› Phase angle› Frequency› Peak Current › Magnetron delay (A delayed or B delayed)
› DC-like waveform is Patent Pending
DC-LIKE OPERATION OF ADDITIVE BULB – MAGNETRON WAVEFORM
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/20189
Mag
netro
n C
urre
nt
Time
DC-Like Modulated
A Mag B Mag
Temperature distribution of additive bulbs in vertical orientation
DC-LIKE OPERATION OF ADDITIVE BULB – BULB OPERATION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/201810
DC (as shown previously)0
1: bottom magnetron delayedTmax = 929 °C
2: top magnetron delayed
DC-like waveform 1 2
Orientation
DC-LIKE OPERATION OF ADDITIVE BULB – LAMP PERFORMANCE
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/201811
0
5
10
15
20
25
30
0%
20%
40%
60%
80%
100%
0 200 400 600 800 1000 1200
Irradiance (m
W/cm
2 )
UV Irradiance (%
of m
ax)
Time (s)
Surveying with Broadband Radiometer
UVA UVC uvasecondary
Horizontal60Hz
B Delay 40°
Vertical60HzB Delay 40°
Vertical60HzA Delay 40°
Vertical120HzA Delay 35°
Vertical120HzB Delay 35°
100% 94% 99% 97% 93% <80%
VerticalDC
Achieved improved performance for DC-like operation over legacy designs
DC-LIKE OPERATION OF ADDITIVE BULB – OPTICAL OUTPUT PERFORMANCE
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/201812
0
100
200
300
400
500
600
700
800
900
1000
201-260 261-300 301-350 351-400 401-450 451-500 501-550 551-600
Rad
iate
d Po
wer
(W/n
m)
Bandwidth (nm)
Horizontal Bulb Spectral Comparison
DC Legacy System 1 Legacy System 2 DC-Like Modulated
0
200
400
600
800
1000
1200
201-260 261-300 301-350 351-400 401-450 451-500 501-550 551-600
Rad
iate
d Po
wer
(W/n
m)
Band (nm)
Vertical Bulb Spectral Comparison
60Hz, A Up DC, A Up Legacy System 1 Legacy System 2
Achieved improved performance for DC-like operation over legacy designs› Magnetron-driving waveform mostly “DC”
› Minor fluctuations added to power delivered to bulb› Rise/Fall of waveform important for plasma stability› Also depends on additive composition (plasma reactions complex)
› Comparable or better bulb temperatures than when operated horizontally› No life time compromises
› Comparable or better bulb radiances› Horizontal: 4-6% higher than legacy power supplies, comparable to DC› Vertical: 6% higher than legacy power supplies, 15-25% higher than DC
› Comparable curing performance (still under study)
SUMMARY
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/201813
ACKNOWLEDGMENTS: BRETT SKINNER, MIKE GHARAGOZLOO, CHUCK WOOD, PK SWAIN
THANK YOU FOR YOUR ATTENTION
Method for Driving Microwave-Driven Additive Lamps for Improved Performance | D. Leonhardt PhD | HNA-Innovation5/9/201814
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