MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
1
Karlheinz Blankenbach
Pforzheim University, Germany
Master in Embedded Systems, Pforzheim, SS 2008
Prof. Dr. Karlheinz Blankenbach
Pforzheim University
Tiefenbronner Str. 65
D-75175 Pforzheim, Germany
Phone : +49 7231 - 28 - 6658
Fax : +49 7231 - 28 - 6060
Email : [email protected]
Web : www.displaylabor.de
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
2
Objective of Lecture
• Understanding of applications of electronic displays
• Know how of advanced display technologies
• Knowledge of relationships between electronics ���� interface ���� display
• Capability to design embedded (information) systems
with the ‘best’ display
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
3
Recommended Textbooks
- L.W. MacDonald, A.C. Lowe: Display Systems, WILEY SID
- P.A. Keller: Electronic Display Measurement, WILEY SID
- Green, MacDonald: Color Engineering, WILEY SID
- Ernst Lueder: LCDs : Addressing Schemes and e-o Effects, WILEY SID
- Willem de Boer: AM Liquid Crystal Displays, NEWNES
- R.L. Myers: Display Interfaces, WILEY SID
- G. Berbecel: Digital Image Display, WILEY SID
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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• Display Interfaces
• Introduction
• Selected Topics on Advanced LCDs, OLEDs and PDPs
Overview
• 3D & E-Paper (flexible) Display Technologies
• Touch Screen Technologies
- Market overview
- Some basics of metrology
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
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Worldwide Flat Panel MarketWorldwide Flat Panel Market
0
10
20
30
40
50
60
2002 2003 2004 2005 2006 2007
Bill. $
AM LCD
PM LCDPDP
Other FPDs
Source :
iSupply
- 50% of FPD in 2006- PC and TV only indeveloping countries
CRTs
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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0
5
10
15
20
25
30
35
Noteb
ooks
Mon
itor
s
Mob
ile
Autom
otiv
eTV
Indus
trial
Pho
to
2004
2007
2009
6
Top 7 FPD Applications
~ 100% AM LCD except for TVWorldwide Turnover / B$
MES Multimedia - Displays: Introduction
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Worldwide Flat Panel Market by Regions
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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Worldwide Flat Panel Market by Applications
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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Worldwide Units by Applications
2007:
Production
60,000 m²
MES Multimedia - Displays: Introduction
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Shift of FPD Production
From Japan to Korea & Taiwan to (?) China
MES Multimedia - Displays: Introduction
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AM LCD “Application Waves”
MES Multimedia - Displays: Introduction
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Worldwide Flat Panel Market : Small / Medium LCDs (< 10”)
Price per display shrinks !
MES Multimedia - Displays: Introduction
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Worldwide Flat Panel Market : AMLCD > 10“ Mio. / B$ p.a.
0
2
4
6
8
10
12
14
16
18
SAM
SUNG
LG:P
HIL
IPS
AUO
CM
O
SHARP
CPT
HANNSTA
R
INNOLU
X
BOE-O
T
Oth
ers
2006
2007
Ranked acc. turn-over: compare e.g. SHARP and CPT
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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Worldwide Flat Panel Market : AMLCD > 10“ Mio. / Units p.a.
0
10
20
30
40
50
60
70
80
90
SAM
SUNG
LG:P
HIL
IPS
AUO
CM
O
SHARP
CPT
HANNSTA
R
INNOLU
X
BOE-O
T
Oth
ers
2006
2007
Ranked acc. turn-over: compare e.g. SHARP and CPT
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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Worldwide Flat Panel Market : LED Backlight for LCDs
LCD < 5“: ~ 100% LED
MES Multimedia - Displays: Introduction
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Worldwide Flat Panel Market : OLEDs
• Left: Linear rise or S-curve – compare to mobile devices (right)
• Left: 10 M$ ticks reasonable ?
• OLEDS in total are about 1.5% of total LCD-market in 2006
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
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Worldwide Flat Panel Market : Car Navigation
MES Multimedia - Displays: Introduction
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Worldwide Market : Head - Up Displays
MES Multimedia - Displays: Introduction
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Worldwide Market : Touch Screens
MES Multimedia - Displays: Introduction
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Worldwide Market : Low Power and Zero Power Displays
MES Multimedia - Displays: Introduction
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Commodityup to 65” (2007)
LCD TV Race (Prototypes)
2004 : 57“
2005 : 82“
2006 : 108“
Gen 10
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The Race for Size is limited by Mother Glass Size
Commercially in MP available:
- LCD up to 70”
- PDP up to 70” (PANASONIC 103“: 100,000 $)
Forced by
trend to signage
(POI, small sized
indoor billboards, …
SHARP 108” LCD prototype
PANASONIC 150” PDP
CES 2008
MES Multimedia - Displays: Introduction
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The Race for Size (I)
Production issue
Micrometer
precision
required in
meter range !
MES Multimedia - Displays: Introduction
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The Race for Size (II)
• Gen 8 = 1 B$
• SHARP announced
Gen 10 for 2010
SAMSUNG
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Projection
system
Flat Panel Display World
1 10 20 40 60 Display Size /“
Resolution
QXGA
HDTV
SXGA
XGA
SDTVVGA
QVGA Low information content displays
Note-book
PC-monitor
LCDTV
Car
MP, PDA
150 ppi
p-Si a-Si
PDP
Projection
MES Multimedia - Displays: Introduction
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User quality → Technical specification
'Good readability‘ Optics, electronics, application, …
How to Select a Display
Magic Circle
Optics
Electronics
Electro-optics
Application
Pixel driving,
e-o characteristics,
rise & fall time,
ghosting, …
Luminance, contrast,
grey scale, colour,
response time, uniformity
viewing angle, reflections, ...
Size, weight, price, lifetime,
power supply, reliability,
mature technology,
temperature, vibration,
displayed data, ...
Driving, voltages,
signal processing,
power consumption,
EMI, data input, ...
MES Multimedia - Displays: Introduction
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• Summary
• Introduction
• Basic Parameters (Merits)
Overview
• Common Issues
• Display Technology Dependent Issues (Shortcomings)
- Motivation
- Some basics of vision
MES Multimedia - Displays: Introduction
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Why Measuring Electronic Displays ?
Merits of display metrology
• Human vision is only descriptive
• Standardized measurement setups and test patterns
• Specifications enable judging of displays
• Wide range of measurement procedures for many applications
Shortcomings of display metrology
• Ambient light (simulation) difficult, therefore most of
the specified values are measured under dark room conditions
• Vision sees things that measurement can’t capture and vice versa
MES Multimedia - Displays: Introduction
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Basic Characteristics of Vision
Resolution Spectral Sensitivity for
Day and Night
• Angular resolution : 1‘
at optical axis
Example: 0.3mm @ 1m
• Time resolution ~ 50 ms (20 Hz)
up to 100 Hz flicker sensitive
• ~ 500,000 colors can be
distinguished
… plus ‚signal processing‘ (brain)
MES Multimedia - Displays: Introduction
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Sea of Measurement Tasks
Test patterns
Full, box, checkerboard, grille,
grey level, color, dynamic, moving, …
Measurement
of luminance
and/or color
Dark room or (simulated)
ambient light
Viewingangle
Environment
Temperature,
% rH, EMI,
power supply,
…
Procedure,
data storage
• Spatial
• Temporal
- Jitter
- Warm up
- T-change
- Lifetime
DUT
Driving
system
Signal
processing
MES Multimedia - Displays: Introduction
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• Summary
• Introduction
• Basic Parameters (Merits)
Overview
• Common Issues
• Display Technology Dependent Issues (Shortcomings)
- B/W, GS, color
- L, CR, GS, color
- Parameters & vision
Color Calculator:
www.radiantimaging.com/
MES Multimedia - Displays: Introduction
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• Luminous flux (power) : F / lm
• Luminance : L / (emitter)
• Illuminance : E / (receiver)
Illuminance = power / area :
Photometric Units
2m
cd
2m
lmlx =
A
F
Ad
FdE ==
Examples - Luminous flux F = 1,000 ANSI lm for projector
- Luminance L = 300 cd/m² for AMLCD
- Illuminance for 1,000 lm projector at 2 x 3 m² → E = 167 lx
compare to 500 lx recommended at workplace!
Units: RI Color Calculator
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• [L] = cd/m²
• Typical values : Displays 50 … 1,000 cd/m², bulb 10,000 cd/m²,
sun at noon 108 cd/m², full moon 100 cd/m²
• Basic value for contrast, grey scale, uniformity, viewing angle, ...
• One of three parameters for color measurements (Tristimulus)
• Measurement conditions
- Dark room unless otherwise noted
- Centre of display, perpendicular incidence
- Usually F.O.V. of > 25 pixel for monitors
- V(λ) corrected devices
Luminance
Same for color
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Example of Optical Specification for AM LCD (II)
Recommendation: Use same device as in spec!
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Contrast Ratio
• Luminance ratio of bright / white / max / ON to dark / black / min / OFF
• Various definitions, mostly contrast ratio used, MTF s. b.
Remarks • High CR can be critical because of measurement error for Lblack
• Vision range : CR = 3 : 1 - 500 : 1
• CR ≈ 10 : 1 recommended for non-fatigue reading (paper !)
• High CR can bother (e.g. car headlights at night) !
• CR in specs measured without ambient light ! E� → CR�
• Various conditions like full screen, checkerboard, …
• Contrast ratio
...L
L
L
LC
black
white
dark
bright
R ==Example
Paper ≈ 10 : 1 Lwhite Lblack
… is not a measure for readability of text (full screen)!
MES Multimedia - Displays: Introduction
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Contrast Ratio Test Patterns
• Full screen
• Centered box
• Checkerboard
(Projection)
• Intra-Character
CR depends on test
pattern, especially for
- PM drive (ghosting)
- PDP
- Projection
Used for PDP � CR ≈ 1,000:1
LCD, OLED, PDP CR ≈ 100:1
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LED LCD - Backlight Improvements : Local Dimming
Power saving 50% average (image dependant)
Lmax = 630 cd/m2
Lmin = 0.03 cd/m2
� CR = 630 / 0.03
= 21,000 : 1
High Contrast
MES Multimedia - Displays: Introduction
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Modulation Transfer Function & Resolution
• Contrast modulation = MTF
darkbright
darkbrightGrilleM
LL
LLC
+
−=
• Threshold
- Text
- Images
5.0CGrilleM ≥
25.0CGrilleM ≥
I,Tn
linesofNumberR =
• Resolution
• (Analogue) bandwidth
• Ghosting, …
n
Measure for text
readability
MES Multimedia - Displays: Introduction
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Grey Scale Measurements
0
0.2
0.4
0.6
0.8
1.0
0 0.2 0.4 0.6 0.8 1.0
rel. Grey Level
LCD 18"
LCD 8.4"
L ~ D 2.3
CRT
rel. Luminance
Deviations
log (norm. Grey Level)
log (norm. Luminance)
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
-2.0 -1.5 -1.0 -0.5 0.0
log(Luminance)
gamma 2.5
log(Luminance - L(0))
• Greyscale for images, …
• Results: Gamma, GS resolution, …
• Gamma is seldom specified
Grey
bars or
full screen
Contrastratio onlymax / min !
MES Multimedia - Displays: Introduction
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Color Space CIE 1931
• Oldest CIE standard
• Still in use today but
CIE 1976 UCS recom-
mended in display
metrology specs !
• Problem: Co-ordinate
differences ≠ color
differences (Mac Adam)
• Linear transformation of
Tristimulus values, L = Y
3. co-ordinate : Luminance L = Y
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LCD CIE 1931 Specification
Plot these tolerances in CIE 1931 with �x and �y = 0.1 !
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Color Space CIE 1976 UCS 3. co-ordinate : Luminance L = Y
u‘
v‘ • CIE 1976 UCS recom-
mended in display
metrology specs !
• Co-ordinate differences
≈ colour differences
• Linear transformation
• Gamut (100% usually refers to NTSC)
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TV Color Spaces
• YIQ : NTSC
• YUV : PAL, SECAM
• YCbCr : ITU-R BT.601, 709 HDTV
−
−−=
B
G
R
31.052.021.0
32.028.060.0
11.059.030.0
Q
I
Y
−−
−−=
B
G
R
08.042.050.0
50.033.017.0
11.059.030.0
Cr
Cb
Y
)YR(877.0V
)YB(493.0U
B11.0G59.0R30.0Y
−=
−=
++=
• All parameters are normalized
• Y ≡ Luminance, same formula for all TV color spaces
• IQ, UV, CbCr ≡ Chrominance
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Color Space Summary
SW∆ESpecs (recomm.)
SpecsUsed for
Device specific
3D, L* ≠ LL not brightness
∆co-cord. ≠ ∆color
(Mac Adams)
Cons
SWJNDs∆co-cord. ≈∆color
historyPros
3D3D2D2DPlot
n. a.NoYesYesLuminance
n. a.Non-linearLinearLinearTristimulus transformation
RGBCIE LabCIE Luv
CIE 1976 UCS
CIE 1931
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• Summary
• Introduction
• Basic Parameters (Merits)
Overview
• Common Issues
• Display Technology Dependent Issues (Shortcomings)
- Spatial domain:
Uniformity, MTF, gamma,
color tracking, …
- Time domain:
- Short: Flicker, jitter, swim, blur, …
- Medium: Warm up, …
- Long: Lifetime, …
- Ambient light: CR, GS, color, …
- Signal processing
Here: Some examples
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Uniformity
• Deviation of a display parameter, e.g. luminance within display area
• 5, 9 or 13 spots method (ISO 9241)
%xL
L100
%xL
LL100
%xL
min
max
max
minmax
<•
<−
•
±∅•
Examples*
*:Lmax = 200 cd/m², Lmin = 180 cd/m²
190 cd/m² ± 5%
10%
111%
Definitions
• Area (linear or false color)Uniformity
versus
Campbell-Robson
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Examples of Uniformity Measurement in Spec
Spot size acc.
FOV and distance
Luminance variations outside this points are not specified
like degradations due to burn-in or image sticking !
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Color Tracking
Color Tracking 20" LCD, CIE 1976 UCS
0.450
0.455
0.460
0.465
0.470
0.475
0.480
0.202 0.204 0.206 0.208 0.210 0.212
u'
grey
white
v'
Color co-
ordinate of
white depends
here on grey
level !
γγγγ ≠ γγγγ ≠ γγγγ !
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49
Contrast Ratio with Ambient Light
Components of reflections
LCD (left) : specular & haze
OLED (right) : mainly specular
(diffuse with low intensity)
Er
)lx0(L
L
)lx0(L
L)lx0(L
L)lx0(LC
L
LC white
reflected
white
reflected
reflectedwhite
Rlightambient
black
white
R
black
π≈≈
+
+=→=
+
Lwhite >> Lreflected
Lreflected >> Lblack
Diffuse
π=
ErLdiffuse
reflected
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ISO 15008 Sunlight Simulation
30“LCD
1
10
100
1,000
0 20,000 40,000 60,000
Illuminance /lx
Contrast Ratio Diffuse Geometry
Measured CR
Fitted CR
Diffuse or specular geometry
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51
Examples for Contrast Ratio Degradation
Luminance of white has more influence on CR with ambient light
than luminance of black and CR under dark room conditions !
Factor 5 for white luminance, L(K) = const. � factor ~ 4.7 in CR for ambient light
110 / 15 = 7205100
510 / 15 = 341005500
110 / 11 = 101001100
510 / 11 = 465001500
CR with LReflected = 10 cd/m² *CR(0 lx)LBlackLWhite
* : LRefl. (W) = LRefl. (K)
Factor 5 for black luminance, L(W) = const. � factor ~1.4 in CR for ambient light
for LWhite = 100 cd/m² and LWhite = 500 cd/m²
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52
Ambient Light & Grey Scale
-1.00 -0.75 -0.50 -0.25 0
log (Grey level)
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
-1.25
log (Luminance)
Ambient Light
• Ambient light reduces the number of distinguishable grey shades (JND)
• Grey shades below 80 (of 255) can‘t be resolved for 2,000 lx
0 lx
50 lx
200 lx
1,000 lx
2,000 lx
γ = 2.3
12“ Transmissive LCD
33 %
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Ambient Light & Color
Reflections shift the
color coordinates
towards the locus
of the light source.
CIE 1931 & Ambient Light
0 0.2 0.4 0.6 0.8 x
y
0.8
0.6
0.4
0.2
0
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Display Technology vs. Ambient Light : Sunlight Outdoor
Transmissive color AM LCD
Transflective
Color AM LCD
Reflective E-Paper
Reflective MUX LCD
Reflective b/w PM LCD
E-Paperis closeto paper
Display is ON!
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Blur Effects
• Spatial Blur
by limited bandwidth, jitter, …
e.g. MTF, analogue path
see ‘Display Metrology’
Luminance
t
FrameT
Blur
• Motion Blur
by hold type
displays (e.g. AM)
Luminance
t
FrameT
Hold Type
55
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Motion Blur Basics
• Motion blur is caused by AM techniques due to lack of ‚auto-tracking‘
by human vision (PDP has similar issues on subframe coding)
• Impulsive displays like CRTs don’t suffer of motion blur
Adapt AM to impulsive drive
AM
CRT
Visualization Perceived
‚Flashing‘
‚Display & hold‘
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Display & Observer Motion Blur
Blurry edges !
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Motion Blur Reduction Techniques
Only with LED backlight !
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¾ TFrame
Displaying Moving Objects
Frame 2( T = Frame 1
+ 1/2 Frame 2)
Frame 1
Hold Type
(AM technologies)
Original
Leftover of frame 1not visible due to phosphor decay
(2 pictures ‘movie’)
(Picture 1 iscompletelywritten onthe display)
(Half ofpicture 2 iswritten onthe display)
Non - Hold
Type (CRT)
Smearing !
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Effect of Eye Movement on CRTs (Impulsive Drive)
60
White box is moved with 4 pixels per 60 Hz frame
Examined line
Display x
CRTOn Display, x
t
1 F
Eye movement Perceivedimage by eye
On eye, x
t
1 F
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Effect of Eye Movement on 60 Hz LCDs (Hold Type)
61
60 Hz LCD
On Display, x
t
1 F
Eye movement Perceivedimage by eye
On eye, x
t
1 F
Unsharp edge ≡ blurring of 3 pixels
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Effect of Eye Movement on 120 Hz LCDs (Hold Type)
62
120 Hz LCD
On Display, x
t
1 F
Eye movement Perceivedimage by eye
On eye, x
t
1 F
Unsharp edge ≡ reduced blurring of 1 pixel
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Effect of Eye Movement on Displays
63
White box is moved with 4 pixels per 60 Hz frame
Examined line
Display x
CRTPerceived image by eye
60 Hz LCD
120 Hz LCD
- CRT has best motion picture quality
- LCD with 120 Hz is better than 60 Hz
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CRT
Black Frame Insertion
LCD
• High LC switching speed required
• Black frame insertion or impulsive LED backlight
OLED : ‘Easy’
• Fast OLED response
• Only SW required
L
t
1 F
Hold
Lpeak BFI > LHold
BFI
(not to scale)
Black frameinsertion
0 10 20
ITU Grade (International Telecommunication Union)
Excellent
Good
Fair
Poor
Bad
Subjective Evaluation for Moving Picture
Scroll velocity /pixel per frame
CRT
OCBw. LED
TN
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Impulsive Backlight for LCD Hold - Type Technologies
Nosmearing
Frame 1 Frame 2
TDisplay
= ½ TFrame
TBlackframe
= ½ TFrame
8.3 ms instead of 16.7 ms
→ fast switching LC required
Writegreyleveldata
todisplay
Writegreyleveldata
todisplay
Backlight OFF OFFON ON
Similar: Scrolling backlight
with LEDs
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Impulsive Backlight for LCD Hold - Type Technologies
Could be also made by 120Hz drive with GL = 0 insertion.
Application: Rolling backlight / black frame
66
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Impulsive Backlight for LCD Hold - Type Technologies
No BFI With BFI
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Impulsive Backlight for LCD Hold - Type Technologies
ON
OFF
Scrolling of ‚black‘ backlight sections
68
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Motion Blur Reduction by Higher Frame Rate
Motion blur reduction using high frame rate driving: 120Hz/100Hz
Requires new panel design, also video sources low frame rates
(NTSC = 60Hz, PAL = 50Hz, Film = 24Hz)
� Motion interpolated frame technology or Black Frame Insertion needed
such as McFi (Motion Compensated Frame Interpolation)
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Comparison by SAMSUNG
BFI
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Comparison by SIEMENS
BFI BFI
M. Zachmann (Pforzheim U) et al.
Evaluate your display with PIXPERAN (freeware)
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CLEAR MOTION DRIVE by JVC
100 or 120 Hz & interpolated images
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Motion Blur Reduction Using 120 Hz & 72 Hz Driving with
Motion - Compensated Frame Interpolation
Movie
24 Hz����
72 Hz
calculated
(DVD)
Motion judder for 3:2 pull-down!
For LCD and PDP
120 Hz
‚cheaper‘
than backlight
methods
NTSC Video
60 Hz����
120 Hz
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Frame Rate Conversion Techniques (I)
PAL Video 50 Hz ���� Motion blur on Hold type displays (LCD, …)
t
PAL Video 100 Hz repeated ���� judder
calculated
PAL Video 100 Hz motion compensated ���� no judder (if algorithm OK)
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Frame Rate Conversion Techniques (II)
Movie 24 Hz (24p) Original
t
Movie 60 Hz 3:2 pull down repeated ���� judder, jerkiness
calculated
Movie 120 Hz motion compensated ���� no judder (if algorithm OK)
Movie 72 Hz 3:3 pull down repeated ���� judder
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PDPs : Motion Artefacts by Sub - Frame Driving
Many motion artifacts etc. of PDPs can be minimized by massive signal processing
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• Summary
• Introduction
• Basic Parameters (Merits)
Overview
• Common Issues
• Display Technology Dependent Issues (Shortcomings)
- Luminance domain: Loading, halation
- Time domain: Burn-in, differential
ageing, image sticking
- Observer domain:
Spatial & time invariant
- Response time
- Viewing angle: L, CR, GS, color
Here: Some examples
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LCDs : Response Time Effects
Rel. L
t /ms0 10 20 30
255 � 0
0 � 255
110 � 192
192 � 110
170 � 215
215 � 170
Grey Level
1923170 ���� 215
2432110 ���� 192
9200 ���� 255
TFall /msTRise /msGrey leveltransition
• T > frame time (16.7 ms)
• TRise > TFall
• T = T(grey 1 � grey 2)
Grey level & color shifts
Tambient = 25°C
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LCD Motion Blur caused by Slow Response Time
Moving Picture Response Time
(MPRT) by Brightness Edge Width
Measurement setup: Camera and
screen (one moving, one fixed)
• Rise time often
≠ fall time
• Response time
depends on
grey level
(start, final)Fall time Rise time
Luminance A - A'
90%
10%
BEWPixel coordinate
Capturedimage
A A'
Motion blur occurs for all AM techno-logies due to vision (Hold type)
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Motion Blur Measurement Procedures
t
HS
Capturing so that image ‘stands still’
on the camera (chip)
High speed
camera
High speed
sensor,
problem:
t � x
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MPRT & Perceived Motion Blur (I)
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MPRT & Perceived Motion BlurMPRT & Perceived Motion Blur (II)
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Motion Picture Response Time by Brightness Edge Width
Normalising : N-BEW = BEW / moving speed
MPRT = ∅ N-BEW (G2G)
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Motion Picture Response Time by Brightness Edge Width
MPRT = 16 ms
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Motion Picture Response Time by Brightness Edge Width
MPRT
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MPRT Measurements by Grey - to - Grey Response Time
CIE 1976 UCS
6 equidistant
brightness
e.g. L = 0 , 2.2 , 7.7 , 18.4 , 36.2 , 62.8 , 100 cd/m2
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MPRT Measurements by Grey - to - Grey Response TimeMPRT Measurements by Grey - to - Grey Response Time
Extended Blurred Edge Time
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Viewing Angle
L, CR , …
Angle
Lambertian (paper)
Emissive displays,diffuse LEDs,standard screen
LCDs, highgain-screenClear LEDs
-80° 0° +80°
‚Angle isn‘t everything‘ !
Measurements : 2D, 3D , value : ± or Σ
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PM LCD
6:00
Viewing Angle Basics6:00 AM LCD seen from 12:00
displaying
green
⊥⊥⊥⊥
Sensor
Display
2D 3D
Dis play x
y
z
ΦΦΦΦ
θθθθ
0°/ 3°°
9°/ 12°°
180°/ 9°°
270°/ 6°°
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Contrast Ratio Dependency from Viewing Angle for LCD
32" LCD
0lx, horizontal
0
40
80
120
160
-80 -60 -40 -20 0 20 40 60 80
Viewing Angle /°
CR
Specify viewing angle only with the minimum contrast ratio (or better color difference ∆∆∆∆E)
here : 40°@ CR > 100 : 1 ; 70°@ CR > 50 : 1 ; 125°@ CR > 20 : 1 ; ???°@ CR > 5 : 1
Often CR min > 5 : 1
Thresholddefinition !
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Example from LCD - Specification
Threshold definition
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Display A is better because of
• Larger area with nearly constant contrast ratio for perpendicular incidence
• Larger maximum contrast ratio
In both cases a 6:00 observer position with θ ≈ 15°is recommended
Iso - Contrast Plots of AMLCDs
A B
Scale for contrast ratio
AMLCD
17”
60 cm
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Grey Scale Inversion
Remarks
- If the sign doesn’t change and luminance levels only merge, the image quality
is horrible, but grey scale inversion doesn’t ‘occur’ in meaning of standard (norm)
- Contrast inversion is the extreme case of grey scale inversion, when maximum and
minimum luminance levels change
∆∆∆∆ L = Ldark grey - Lblack
θθθθθθθθGI
L
θθθθGI θθθθ
Grey scale inversion
Visual test pattern
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L /cd/m²
Grey level (8-bit)
0 31 63
10
0
CR = 200 : 1
ΦΦΦΦ = 90°/ θθθθ = 20°
ΦΦΦΦ = 0°/ θθθθ = 0°
CR = 400 : 1
Contrast Ratio values are misleading here because a reduction of
‘only’ 2 occurs but the grey level representation is completely
vanished (flat curve, blue) compared to perpendicular incidence
(OK, brown) � no grey shades visible for 20° off !
CR = 400 : 1
CR = 200 : 1
Contrast Ratio vs. Grey Scale Performance
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Color Dependency from Viewing Angle of LCDs
Measured color representation,
black was shown on the screen !
Visual test pattern
Inversion !
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Colour Wash Out
0° 45° 60°
Electro-optical curve changes
with viewing angle!
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Luminance Domain : Loading of Plasma Panels
Luminance of
centered white
box depends
on their size,
this is called
‘loading’.
Why? Power limitation
This can be also
observed for CRTs
(incl. image
size variations).
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Aging of Displays
• Lifetime (50%)
Full screen white measured
Static content like on airport
information displays can cause
burn-in and image sticking
• Differential Aging
Different lifetimes of
color subpixel → color shift
rel. L
t
1
t
L
L
100
50
TLTTLT
No inital drop
InitaldropNote: Life time measured at ~ 75°C,
and extrapolated to 25°C in specs!
Temperature ↑ → Life time ↓
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Burn - In of Emissive Displays and LCD Image Sticking
CRT
PDP
LCD
Several hours
display dark grey
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Burn - In and LCD Image Sticking Measurement
- T = 0 : Display 5 x 5 (black & white) checkerboard and mark 3 boxes (2 white, 1 black)
- Measure ‘initial’ luminance for the 3 boxes for black and white: LWL, LWC, … LBL, … LBR
- Burn-in display when showing the checkerboard, if applicable
with high temperature for speeding up the effect, e.g. for OLEDs
- Wait x hours
- Measure luminance of the same locations for full white (KWL, KWC, KWR)
- Measure luminance of the same locations for full black (KBL, KBC, KBR)
- Calculate residual image factors by
R’s are greater than 1 because of aged luminance ‘K’ is lower than initial luminance ‘L’
Simpler test:
+−=−
)x(L2
)x(L)x(L1100(%)inBurn
WC
WRWL
- Checkerboard as burn-in- White screen as test pattern after x hours
IS:Test at
grey(60/255)
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
101
• Summary
• Introduction
• Basic Parameters (Merits)
Overview
• Common Issues
• Display Technology Dependent Issues (Shortcomings)
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
102
Parameters Affecting Measurements & Visual Perception
- Temporal ~
- Directional variations
- Lateral ~
- Photometric
- Colorimetric
- Resolution
‘Signal
processing’
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
103
Example of Optical Specification for AM LCD
Inverter
MES Multimedia - Displays: Introduction
Blankenbach / Pforzheim Univ. / www.displaylabor.de / MES / March 2008
D I S P L A Y L A BPFORZHEIM UNIVERSITY
D I S P L A Y L A BPFORZHEIM UNIVERSITY
104
Overview of Standards
Parameter Standard Display
Luminance CIE 18,15.2
IEC 47(CO)16
IEC 61747*
All
LCD
Chromaticity
CECC 20000 A3
IEC 47(CO)16
ISO 9241/3
ISO 13406
IEC 61747*
LCD
LCD
CRT
FPD
Luminance and
chromaticity uniformity
ISO 9241/3
ISO 13406
CECC WG 20B
IEC 61747*
CRT
FPD
LCD
Response time
ISO 13406
CECC 20000 A3
IEC 47(CO)16
IEC 61747*
FPD
LCD
LCD
Reflections
ISO 13406
CECC 20000 A3
IEC 47(CO)16
ISO 9241/7
IEC 61747*
FPD
LCD
LCD
CRT
Electro-optical Transfer EBUTech 3273 CRT, LCD
Resolution CECC11000 all
Crosstalk CECC WG 20B
ISO 13406
IEC 61747*
LCD
FPD
Distortion ISO 9241/3 CRT
Viewing direction
CECC 20000 A3
IEC 47(CO)16
ISO 13406
LCD
LCD
FPD
Parameter Standard Display
* : for LCD matrix displays
Common: VESA FPDM, SPWG, TCO
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