The Pursuit of High Power LED UV
The
Pursuit
of
High
Power
LED
UV
Stephen
J.
Metcalf
Air
Mo?on
Systems,
Inc.
How does an LED emit light?
P
+
+
N
‐ ‐ ‐ +
An LED is a semiconductor engineered with a crystal structure whose layers are doped with impuri?es to create a P‐N junc?on. © 2009 – Air Mo?on Systems, Inc.
How does an LED emit light?
P
+
‐ +
+
N
‐ ‐ ‐
+
With voltage, electrons from N material join with posi?ve holes from P material, releasing “visible” light energy © 2009 – Air Mo?on Systems, Inc.
How does an LED emit light?
P‐InGaN
+
+
‐ +
N‐InGaN
‐ ‐ ‐ Band Gap
+
The wavelength of the light emijed is determined by the “band gap” energy of the P‐N materials used. © 2009 – Air Mo?on Systems, Inc.
Emergence of High Powered LEDs for UV
P‐AlGaN
+
+
‐ +
N‐AlGaN
‐ ‐ ‐ Band Gap
+
UV light is emijed when Aluminum Gallium Nitride (AlGaN) is used to create the crystal structure © 2009 – Air Mo?on Systems, Inc.
Wavelength, Power and Price
GaN based LEDs can be made to radiate from 240 nm to 600 nm
(AlGaN) based LEDs are most efficient at about 430 nm
Alloy with Indium (InGaN) to make visible LEDs from blue to red Allow with Aluminum (AlGaN) to make UVC to blue
Blue LED power has improved >10X in the past 10 years UV LED efficiencies will con?nue to improve at all wavelengths, including UVC
Cost pressures on LEDs for Solid State Ligh?ng will drive down the cost of all GaN based LEDs – including UV
Blue LED chip prices have dropped 10X in the past 10 years UV LEDs are s?ll expensive, price reduc?ons will depend on compe??on, market demand
© 2009 – Air Mo?on Systems, Inc.
19
UV Spectral Output of Normal (Arc) UV Lamp
Peaks occur across the the UVA, B and C spectral range, with cri?cal peaks at 365 and 400 nm; as much as 58% IR radia?on generated © 2009 – Air Mo?on Systems, Inc.
20
UV Spectral Output of LED versus Arc Lamp
Narrow spectral output of LED concentrates UV output at 380 to 400 nm (UVA) most efficiently for high power © 2009 – Air Mo?on Systems, Inc.
21
LED UV Benefits
Pure UV Spectral Output equals zero emmission of unwanted IR heat or ozone for cooler, cleaner, safer opera?on
Instant On/Off means no more down?me from shujer faults or wai?ng for warm‐up/cool‐down
Up to 30% Radiant Efficiency is far more energy efficient than the best mercury arc lamps
Extremely Long Life up to 20,000 hours of opera?on does away with lamp changes and ajendant costs
Solid‐state Design allows for fewer failure points and easier, more compact press integra?on
© 2009 – Air Mo?on Systems, Inc.
22
LED UV Benefits (cont’d)
Digital Control Op.ons allow for linear output control, performance feedback and precision dosage
Environmentally Improved meaning no more ozone genera?on or mercury content
© 2009 – Air Mo?on Systems, Inc.
23
No IR Heat Output Instant On‐Off Up to 30% Radiant Efficiency Long Lamp Life Solid State Design 24
Emerging Approach: Large Chips, Micro Op.cs
50 Wajs/cm2 at 400 nm Large chips are emerging with micro op?cs to collect more light for great intensity. Thermal package is improving for lower cost. © 2009 – Air Mo?on Systems, Inc.
27
Next Gen Approach: XL Chips, Macro Op.cs
Greater than 80 Wajs/cm2 Projected
A newer genera?on of even larger chips is expected to allow packaging op?ons using macro op?cs. Costs will con?nue to drop. © 2009 – Air Mo?on Systems, Inc.
28
The Pursuit of High‐Power LED UV (Comparison at 395 ‐ 400 nm)
Small LEDs Micro Op.cs
Large LEDs Micro Op.cs
XL LEDs Macro Op.cs
Irradiance at the chip surface
25 W/cm2
50 W/cm2
> 80 W/cm2
Working Distance**
3mm
5cm
>5cm
Irradiance at Substrate**
10 W/cm2
Cost rela?ve to Arc Lamp
Very expensive
Expensive
Comparable
Compare Point
Irradiance over area at the substrate majers most for offset * Radiant efficiency of the chip is strongly dependent on opera?ng current prin?ng, as it dictates speed and dosage ** Working distance and irradiance es?mate based on package and op?cs design © 2009 – Air Mo?on Systems, Inc.
29
The Pursuit of High‐Power LED UV (Comparison at 395 ‐ 400 nm)
Small LEDs Micro Op.cs
Large LEDs Micro Op.cs
XL LEDs Macro Op.cs
Irradiance at the chip surface
25 W/cm2
50 W/cm2
> 80 W/cm2
Working Distance**
3mm
5cm
>5cm
Irradiance at Substrate**
10 W/cm2
Cost rela?ve to Arc Lamp
Very expensive
Expensive
Comparable
Compare Point
Current systems are very expensive (est. $3,000 / linear inch) due * Radiant efficiency of the chip is strongly dependent on opera?ng current to costly chips and complex packaging and cooling ** Working distance and irradiance es?mate based on package and op?cs design © 2009 – Air Mo?on Systems, Inc.
30
Power Levels needed for Speed Chip and Package Costs Limita?on of Formula?ons IR May be Needed Changing Rapidly 31
Moving Forward with LED UV Ink Chemistry Advances Op?cal Power Increases
Beginning to Take off in Ink Jet Press‐maker and Early Offset Adopters?
How does an LED emit light?
P
+
+
N
‐ ‐ ‐ +
An LED is a semiconductor engineered with a crystal structure whose layers are doped with impuri?es to create a P‐N junc?on. © 2009 – Air Mo?on Systems, Inc.
How does an LED emit light?
P
+
‐ +
+
N
‐ ‐ ‐
+
With voltage, electrons from N material join with posi?ve holes from P material, releasing “visible” light energy © 2009 – Air Mo?on Systems, Inc.
How does an LED emit light?
P‐InGaN
+
+
‐ +
N‐InGaN
‐ ‐ ‐ Band Gap
+
The wavelength of the light emijed is determined by the “band gap” energy of the P‐N materials used. © 2009 – Air Mo?on Systems, Inc.
Emergence of High Powered LEDs for UV
P‐AlGaN
+
+
‐ +
N‐AlGaN
‐ ‐ ‐ Band Gap
+
UV light is emijed when Aluminum Gallium Nitride (AlGaN) is used to create the crystal structure © 2009 – Air Mo?on Systems, Inc.
Wavelength, Power and Price
GaN based LEDs can be made to radiate from 240 nm to 600 nm
(AlGaN) based LEDs are most efficient at about 430 nm
Alloy with Indium (InGaN) to make visible LEDs from blue to red Allow with Aluminum (AlGaN) to make UVC to blue
Blue LED power has improved >10X in the past 10 years UV LED efficiencies will con?nue to improve at all wavelengths, including UVC
Cost pressures on LEDs for Solid State Ligh?ng will drive down the cost of all GaN based LEDs – including UV
Blue LED chip prices have dropped 10X in the past 10 years UV LEDs are s?ll expensive, price reduc?ons will depend on compe??on, market demand
© 2009 – Air Mo?on Systems, Inc.
19
UV Spectral Output of Normal (Arc) UV Lamp
Peaks occur across the the UVA, B and C spectral range, with cri?cal peaks at 365 and 400 nm; as much as 58% IR radia?on generated © 2009 – Air Mo?on Systems, Inc.
20
UV Spectral Output of LED versus Arc Lamp
Narrow spectral output of LED concentrates UV output at 380 to 400 nm (UVA) most efficiently for high power © 2009 – Air Mo?on Systems, Inc.
21
LED UV Benefits
Pure UV Spectral Output equals zero emmission of unwanted IR heat or ozone for cooler, cleaner, safer opera?on
Instant On/Off means no more down?me from shujer faults or wai?ng for warm‐up/cool‐down
Up to 30% Radiant Efficiency is far more energy efficient than the best mercury arc lamps
Extremely Long Life up to 20,000 hours of opera?on does away with lamp changes and ajendant costs
Solid‐state Design allows for fewer failure points and easier, more compact press integra?on
© 2009 – Air Mo?on Systems, Inc.
22
LED UV Benefits (cont’d)
Digital Control Op.ons allow for linear output control, performance feedback and precision dosage
Environmentally Improved meaning no more ozone genera?on or mercury content
© 2009 – Air Mo?on Systems, Inc.
23
No IR Heat Output Instant On‐Off Up to 30% Radiant Efficiency Long Lamp Life Solid State Design 24
Emerging Approach: Large Chips, Micro Op.cs
50 Wajs/cm2 at 400 nm Large chips are emerging with micro op?cs to collect more light for great intensity. Thermal package is improving for lower cost. © 2009 – Air Mo?on Systems, Inc.
27
Next Gen Approach: XL Chips, Macro Op.cs
Greater than 80 Wajs/cm2 Projected
A newer genera?on of even larger chips is expected to allow packaging op?ons using macro op?cs. Costs will con?nue to drop. © 2009 – Air Mo?on Systems, Inc.
28
The Pursuit of High‐Power LED UV (Comparison at 395 ‐ 400 nm)
Small LEDs Micro Op.cs
Large LEDs Micro Op.cs
XL LEDs Macro Op.cs
Irradiance at the chip surface
25 W/cm2
50 W/cm2
> 80 W/cm2
Working Distance**
3mm
5cm
>5cm
Irradiance at Substrate**
10 W/cm2
Cost rela?ve to Arc Lamp
Very expensive
Expensive
Comparable
Compare Point
Irradiance over area at the substrate majers most for offset * Radiant efficiency of the chip is strongly dependent on opera?ng current prin?ng, as it dictates speed and dosage ** Working distance and irradiance es?mate based on package and op?cs design © 2009 – Air Mo?on Systems, Inc.
29
The Pursuit of High‐Power LED UV (Comparison at 395 ‐ 400 nm)
Small LEDs Micro Op.cs
Large LEDs Micro Op.cs
XL LEDs Macro Op.cs
Irradiance at the chip surface
25 W/cm2
50 W/cm2
> 80 W/cm2
Working Distance**
3mm
5cm
>5cm
Irradiance at Substrate**
10 W/cm2
Cost rela?ve to Arc Lamp
Very expensive
Expensive
Comparable
Compare Point
Current systems are very expensive (est. $3,000 / linear inch) due * Radiant efficiency of the chip is strongly dependent on opera?ng current to costly chips and complex packaging and cooling ** Working distance and irradiance es?mate based on package and op?cs design © 2009 – Air Mo?on Systems, Inc.
30
Power Levels needed for Speed Chip and Package Costs Limita?on of Formula?ons IR May be Needed Changing Rapidly 31
Moving Forward with LED UV Ink Chemistry Advances Op?cal Power Increases
Beginning to Take off in Ink Jet Press‐maker and Early Offset Adopters?
