DLP Projector
※ 본자료는 사내용으로 TI 사의 발표장표에서 일부 발췌하였습니다 .
1. What is DMD?
2. DLP projector
- Why should we choice DLP projector?
- Optical configurations
- Optical elements
3. How it works?
- FSC
- SCR
Agenda
DMD: Digital Micromirror Device
Beginning to be developed by sight change according to the movement of Rear View Mirror
Number of moving parts - 0.5 (SVGA) to >1.3 (TBA) million
Mechanical motion - - - - - Makes discrete contacts or landings
Lifetime - - - - - - - - - - - - - up to 100,000 hrs
Address voltage - - - - - - - 3.3-volt CMOS technology
Mechanical elements - - - - Aluminum
Process - - - - - - - - - - - - - Low temperature, sputter deposition,
plasma etch (standard SC processes)
Package (Type A) - - - - - - Optical, hermetic, welded lid Mirror
Address Electrode
Yoke Bias/Reset Bus
Metal Address
Pads
Tilting Angle: ±10˚ ±12˚
1. What is DMD ?
Expressing light and shade by changes of selected light by path Mirror Tilting
Expressing Gray level by times taken for path change
1. What is DMD ?
2. DLP Projector – Why should we choice DLP projector?Why should we choice DLP projector?
Image Quality - PixelizationPixelization (fill factor)
DLP= ‘Seamless’, Filmlike
LCD= Grainy, Pixellated
- Contrast RatioContrast Ratio
DLP= simple optics: easier light management
LCD= complex optics: more difficult light management
- SharpnessSharpness (color alignment)
DLP= no misalignment
LCD= misalignment likely over time
- Video QualityVideo Quality
DLP= fast switching: minimal ‘lag’ (few μs)
LCD= slow switching: significant ‘lag’ (tens of ms) smearing for fast moving video
DLP™ = large ‘active’ area LCD = smaller ‘active’ area
DLP™ LCD
2. DLP Projector – Why should we choice DLP projector?Why should we choice DLP projector?
- Color QualityColor Quality
DLP= can match any LCD color gamut
LCD= can’t match any DLP color gamut
R,G,B Bandwidth is depend on each color because of non-sequential system
- Smallest & Brightest DLP= simple optical system,
good reflectivity
LCD= complex optical system
wavelength
LCD
wavelength
DLPTM
DLPTM LCD
2. DLP Projector – Why should we choice DLP projector?Why should we choice DLP projector?
Repeatable Performance (digital accuracy) DLP= digital: precise control, constant performance over time
LCD= analog: variable (affected by temperature, vibration, heat, humidity),
deterioration over time
Reliable - Superior thermal characteristics
DLP= reflects heat
LCD= absorbs heat, performance degrades
- LCD panel degrades as a function of both time and use
- DMDs have shown consistent robust performance over time with up to 100,000
hours lifetime
Start LCD DLP
Number of DMD
2. DLP Projector – Optical configurationsOptical configurations
1 Chip DLP 3 Chip DLP
2. DLP Projector – Optical ConfigurationsOptical Configurations
TIR prism
Non TIR Prism DLP TIR Prism DLP
2. DLP Projector – Optical ConfigurationsOptical Configurations
TIR prism
Non TIR Prism DLP TIR Prism DLP
Reflector (Elliptical Surface)
Lamp
Front Glass (UV Cut Coating)
Mirror
Color Drum (R,G,B,W segment)
※Color Wheel
Condenser Lens C3 (Aspherical Surface)
DMD Panel
Projection Lens
TIR Prism (Total Internal Reflection)
Condenser Lens C2
Condenser Lens C1
Aperture
Integrating Rod
2. DLP Projector – Optical elementsOptical elements
(1) Lamp & Reflector
a. Output Voltage
- AC Type : PHILIPS, OSRAM, IWASAKI, THOSHIBA ….
- DC Type : USHIO …
b. Reflector
- Elliptical Type : Almost of all DLP Projector
Smallest size= Φ33mm, ‘Bami’ lamp made by Philips
- Parabolic Type : Used with condensor lens . Some of AV Projector
Elliptical Reflector Parabolic Reflector
2. DLP Projector – Optical elementsOptical elements
(2) UV Cut Filter
- UV causes heat for some parts . (Coating, Plastic, Bonding)
- On UV Cut Coating, Try not to make the reflected light be concentrated on one point of UV Lamp
UV Cut Filter
0
10
20
30
40
50
60
70
80
90
100
380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780
Wavelength(nm)
Tra
nsm
ittan
ce(%
)
AOI=0 deg
AOI=10 deg
Material: Borofloat + UV Coating
2. DLP Projector – Optical elementsOptical elements
Reflected UV light
(3) Rod Integrator
- through internal reflects, it makes uninformative incident light distribution “rectangular uninformative light”
Type: Solid Rod – Glass or Plastic
Light Tunnel – Mirror
Light Distribution Light Distribution from the inputfrom the input
Light Distribution Light Distribution from the outputfrom the output
Avd: good transmission. Strong against heat DisAvd: easy to broken, easy to get dust , long
Avd: easy to install, dust free, ShortDisAvd: less transmission, weak for heat
in out
2. DLP Projector – Optical elementsOptical elements
(3) Color Drum & Wheel
Optical instrument filtering color by Color Filter assembled with Motor \
< Color Drum >
< Color Wheel > < SCR Color Drum >
2. DLP Projector – Optical elementsOptical elements
(4) Illumination Lenses
It guides lights from Rod Integrator into valid dimensions of DMD
f1 f1
f2 f2
h
h’
θ θ’
t
L1
L2
L1
L2
R1 R4
R5 R6
R2 R3
(m)= h’ / h
= f2 / f1
(t)= 2*(f1+f2)
< JT30 >
f1 = 9.53, f2 = 22.79
※ m = 2.39 배
2. DLP Projector – Optical elementsOptical elements
(5) Mirror
It changes light path or controls light position on DMD
2. DLP Projector – Optical elementsOptical elements
(5) (TIR Prism)
Using air gaps between two prism, it makes selective reflect of transmission
<in : reflect, out : transmission>
in
outin
out
<in : transmission, out : Reflect >
air gapair gap
DMD Panel
TIR Prism
TIR Prism DMD Panel
2. DLP Projector – Optical elementsOptical elements
(5) Projection Lens
It transmit Active Area of DMD on Screen
Fixed Focus Lens – Cannot control the zoom in Fixed distance
Variable Focus Lens (Zoom Lens) – Can control the screen size with zoom in Fixed distance
< Telecentric Type Zoom Lens> < Converging Type Zoom Lens >
Used in DLP Engine with TRI Prism Used DLP Engine with Non-TIR Prism
DM
D
Scr
een
DM
D
Scr
een
2. DLP Projector – Optical elementsOptical elements
3. How it works? – FSCFSC
Color Filtering by Rotating of Color Wheel
Color Wheel 에 광이 입사하는 경우에는 일정한 형태의 크기를 가지고 있기 때문에 그 부분에 아래 그림과 같이 Color Filter 들의 경계부위가 위치하는 경우 혼합 색이 되어 사용할 수 없다 . ( 단 DLP 에서 White Peaking Mode=0 인 경우 ) 그러므로 순색을 표현할 수 있는 시간이 길면 길 수록 Gray Ramp 의 표현이 부드러워지고 순색의 밝기 또한 증가한다 .
time for one field
Pure G time Pure W time Pure R time Pure B time
Mixed Color time
Mixed Color time
Mixed Color time Mixed Color
time
3. How it works? – FSCFSC
Operation
In case of transmitting Red Filter, Green and Blue is reflected and is useless
Blue and Green light turned into
heat
Color Wheel
Red light transmitted
33% efficiency
※FSC=Field Sequential Color
Lighting on DMD in timely sequence
3. How it works? – FSCFSC
Brief Brightness Estimation
1) RGB Segment ( W=1, R:G:B Intensity= 1/3, R:G:B segment size= 1:1:1)
R = 1/3 G = B = 1/3
RGB size = 1/3 : Wo = R/3 + G/3 + B/3 = 0.333
2) RGB Segment ( W=1, R:G:B Intensity= 1/3, R:G:B:W segment size= 1:1:1:1)
R = 1/3 G = B = 1/3
W = 1
RGB size = 1/4 Wo = R/4 + G/4 + B/4 + W/4 = 0.500
3. How it works? – SCRSCR
Operation
Integrating Rod 의 출사측에 Color Filter 가 위치하며 , 출사면의 Size 안에 RGB Segment 를 모두 포함한다Integrating Rod 에 입사된 백색광은 RGB Segment Filter 에 의해 해당 RGB 색은 투과된다 .RGB 색이 투과하고 CMY 색은 반사되어 Integrating Rod 의 입사측으로 되돌아간다 .반사된 CMY 색은 Integrating Rod 의 입사측의 Mirror 면에 의해 다시 RGB Filter 에 입사하게 된다 .RGB Filter 에 의해 CMY 색은 해당 RGB 색을 투과되고 나머지 RGB 색은 다시 반사된다 .
※SCR= Sequential Color Recapture
Scroll Lighting Whole RGB on DMD in timely sequence
Reflected RGB is re-reflected by Integrating Rod IN and transmitted by RGB Filter
3. How it works? – SCRSCR
Brief Brightness Estimation
Integrating Rod : Total size vs Hole Size ratio = 0.5 Total size Input vs Hole Input Intensity Ratio = 0.85
1) RGB Segment ( Wi=1, R:G:B Intensity= 1/3, R:G:B segment size= 1:1:1)
R = first transmission R(0.85*1/3) + G,B reflected MY of re-reflected R(0.85*0.5*2/3*1/3*2) = 0.472 G,B is same as above G=B= 0.472
RGB size = 1/3 Wo = R/3 + G/3 + B/3 = 0.472
2) RGB Segment ( W=1, R:G:B Intensity= 1/3, R:G:B:W segment size= 1:1:1:1)
R = first transmission R(0.85*1/3) + G,B reflected MY of re-reflected R(0.85*0.5*2/4*1/3*2)
= 0.425 G,B is same as above G = B = 0.425 W = 1
RGB size = 1/4 Wo = R/4 + G/4 + B/4 + W/4 = 0.569