TFT LCD驱动原理

‫ٯ‬:ှ ‫ ࡋ ݋‬1280x800; 60Hz refresh rate Frame Time = (1/60) s =16.7ms Line Time = 16.7ms/(800+23) = 20.1us
PDD1/PD2 © Chi Mei Optoelectronics
Page19
న ඲ ཱུ ‫ ܄‬ϸ ᙯ ០୏
dot (sub-pixel)
pixel
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Page13
TFT LCD Pixel Equivalent Circuit
ᡣ‫ঁ؂‬Ⴝન೿ૈ҅ዴᡉҢ
ӵՖкႝ‫҅ډ‬ዴ‫ޑ‬ႝᓸྗՏ@ ӵՖߥ࡭҅ዴ‫ޑ‬ႝᓸྗՏ@
ߚ౛གྷ‫ݩރ‬
០ ୏ চ ౛ Qbsu!JJ
PCB Light Guide
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Page6
Color Depth (1/2)
ᡂ ϯ Ο চ Յ Ӏ ‫ޑ‬ம ১ -ష ӝ ё ғ ԋ Ӛ ᅿ ᚑ Յ
Gray Scale 0 Red Green Blue White
8 16 24 32 40 48 56 63
Vlc، ‫ ۓ‬գ ࣮ ‫ࢂޑ ډ‬ϙ ሶ
Data line
Scan line Vs
Vg
G Vd
S
D Cst
Cgd +
Clc Vlc
Vst Vcom
PDD1/PD2 © Chi Mei Optoelectronics
Page14
TFT Switch
PDD1/PD2 © Chi Mei Optoelectronics
TFT-LCD០୏চ౛ Part I
ౢࠔ໒ว΋ೀ ໒วΒ ೽ ጰ຾ԋ
ε ᆜ (1/2)
კႽᡉҢচ౛ TFT-LCD០ ୏ চ ౛ ୷ ᘵ
న඲០୏চ౛
V-T curve
ߞ ဦ ቪ Ε চ౛(໻ Ե ቾ ౛གྷ ‫) ݩ ރ‬
pixel฻ਏႝၡ addressing, refresh rate, frame time, line time
PDD1/PD2 © Chi Mei Optoelectronics
Page20
Image Sticking
Switch to full
grayscale 128
after 12 hours
at room temp.
Ideal case
த ‫ ޑ ـ‬Jnbhf!Tujdljoh‫ ׎‬Ԅ
Surface type
న඲Ѹ໪аҬࢬߞဦ០୏ ߏ ਔ ໔ ᆢ ࡭ ࢌ ΋ཱུ ‫ ܄‬,న ඲ ϩ η ё ૈ ‫ ډ ڙ‬ઇ ᚯ ….
Vcom (CFೡሽᄕ)
----
0V
++
Vcom (CFೡሽᄕ)
----
0V
+4V
+3V
--
న඲‫ࡋف‬ᒱᇤ!
Vpixel +(T+F+T+ೡሽᄕ)4V
Vpixel +(T+F+T+ೡሽᄕ)3V
Row Inversion
+-+-
-+-+
+-++-+-
-+-+ -+-+
+-+-
-+-+
Column Inversion
+-+-
-+-+
-+-+
+-+-
+-+-
-+-+
-+-+
+-+-
Dot Inversion
PDD1/PD2 © Chi Mei Optoelectronics
Page17
Addressing
Gate Charge
Pixel Electrode
Storage Capacitor
PDD1/PD2 © Chi Mei Optoelectronics
Page18
Scan Driver Output
Vcom
16.67ms
҅ ॄ ཱུ ‫ ܄‬ႝᓸ ό ֡ᑽ ҅ॄཱུ‫ࡋߝ܄‬ό֡ᑽ Flicker (ଢ ᛉ )
ፓ ᏾ VcomԖ ਏ ݀ Ǵ ՠ ᏾ Т
˩ˀ˧ʳ˶̈̅̉˸ʳ̂˹ʳ˭˖ˠˈ˃ˈˊ
˄ ˃˃ʸ
ˋ˃ʸ
ˉ˃ʸ
ˇ˃ʸ
˅˃ʸ
time
˃ʸ
˃
˅
ˇ
ˉ
ˋ
̉̂˿ ̇ ˴ ˺ ˸ʳ̂́ ʳ̇ ˻ ˸ʳ˧˙ ˧ʳ̆ ˼ ˷ ˸
dot (sub-pixel)
pixel
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Page4
ற Յ ᡉ Ң চ౛ (1/2)
आ ɠ ᆘɨ ໳ आ ɠ ᙔɨ ๋ आ Q:आ ɠ ᆘɠ ᙔɨ ? Q:ค आ ɠ ค ᆘɠ ค ᙔɨ ?
PDD1/PD2 © Chi Mei Optoelectronics
PDD1/PD2 © Chi Mei Optoelectronics
Page11
V-T Curve (2/2)
PDD1/PD2 © Chi Mei Optoelectronics
Page12
LCDӵ Ֆ ᡉ Ң კ Ⴝ
MDEӵ Ֆ ᡉ Ң კ Ⴝ @
ӧ҅ ዴ ‫ޑ‬Տ ࿼ ቪ Ε ҅ ዴ ‫ޑ‬ႝᓸ
Vpixel < Vcom
PDD1/PD2 © Chi Mei Optoelectronics
1V
Page24
AC Vcom
λЁκय़݈தҔ
Vcom (CFೡሽᄕ)
----
0V
Vcom
++++
4V
+3V
-3V
Vpixel +(T+F+T+ೡሽᄕ)3V
---Vpixel
ཱུ҅‫܄‬០୏
ॄཱུ‫܄‬០୏
Vpixel > Vcom
TFT-LCD០ ୏ ႝ ၡ ࢎ ᄬ
‫س‬಍Б༧კ Ӛ೽фૈᙁϟ
TCON Data driver Scan driver DC/DC GAMMA
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Page3
კ Ⴝ ᡉ Ң চ౛
ႝတᡉҢϐკႽ֡ࢂҗ΋ঁঁ‫ޑ‬Ⴝન )q j y f m * ᄬ ԋ ΋૓ ٰ ᇥ -Ⴝન җΟ ᅿ ᚑ Յ आ )S * ! ᆘ)H * ! ᙔ)C * ! ‫ޑ‬λ Ӏ ᗺ )e p u * ᄬ ԋ ‫ ;ٯ‬2 6 / 5 ә2 3 9 1 + 9 1 1 ‫ޑ‬U G U .M D E ᑻ ჿ ൩ Ԗ 2 3 9 1 + 4 + 9 1 1 ঁt v c .q j y f m
-----------------------------------------------------------------
odd frame
even frame
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Page26
Flicker
Applied voltage shifts
Line shape
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Page21
Image Retention
Two types of the image retention cases. There might be other type image retention cases.
ֽ ؓ ೣ ٠ࣨ Page9
న ඲ ០୏চ౛
а ႝ൑ ‫ ׯ‬ᡂ న ඲ ‫ ރ‬ᄊ Ǵ ௓ ‫ ڋ‬Ӏ ऀ ೸ ‫ޑ‬ӭ ჲ Ƕ
а90ࡋ4V TNࣁ ‫ٯ‬
ऀຫໍສະໝຸດ Baidu౗
1&
3 1& 5 1&
7 1& 9 1& 2 11&
న඲‫ࡋفޑ‬
)ႝ ൑ ம ࡋ * ႝཱུ໔ϐႝᓸৡ
ε
λ )҂ у ႝ ൑ *
4V
2.3V
Page15
௟ ඔ Ԅ ቪ Ε (1/2)
ON OFF
OFF
OFF
Ӄ ໒ ௴ ಃ ΋ӈ ǹ ‫ ځ‬Ꭹ ᜢ ഈ Ǵ ᆢ ࡭ ϐ߻ ‫ޑ‬ႝᓸ Ƕ ‫ ׳‬ཥ ಃ ΋ӈ Կ ϐ߻ ೛ ‫ ۓ‬ϐ‫ ܌‬ሡ ႝᓸ Ƕ
PDD1/PD2 © Chi Mei Optoelectronics
Page16
௟ ඔ Ԅ ቪ Ε (2/2)
True color
2 5 6 color
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Page8
LCDӵ Ֆ ௓ ‫ࡋ ߝ ڋ‬
а90ࡋTNࣁ ‫ٯ‬
٠ᄭ ি ऴ ೣ ٠ࣨ
ੲᑿሽᄕ
෈དྷ
ੲᑿሽᄕ
ֽ ؓ ೣ ٠ࣨ
٠ᄭ ি ऴ ೣ ٠ࣨ
ੲᑿሽᄕ
෈དྷ
ੲᑿሽᄕ
PDD1/PD2 © Chi Mei Optoelectronics
Vpixel < Vcom
PDD1/PD2 © Chi Mei Optoelectronics
1V
Page25
Inversion Driving
Frame inversion
+++++++++ +++++++++ +++++++++ +++++++++ +++++++++ +++++++++ +++++++++ +++++++++
຾ ໘ ፐ ำ :Յ ࡋ Ꮲ
Page5
ற Յ ᡉ Ң চ౛ (2/2)
Q:LCDӵ Ֆ ౢ ғ Ο চ Յ Ӏ ? Color Filter Q:LCDӵ Ֆ ௓ ‫ ڋ‬Ӏ ‫ޑ‬ம ১ ?
Polarizer ೣ٠ࣨ
LC cell ෈ དྷ CF
Polarizer ೣ٠ࣨ
TFT ᗉ ጥ :‫ ׽‬ข ‫ ۥ ػ س‬٠
switch to full white
switch to
full white
PDD1/PD2
© Chi Mei Optoelectronics
Page22
DC ූ ੮
+ ++
+ External electric field
AC driving
~
ITO
++++
PI
Internal electric field
panel‫ޑ‬Vcom٠ ߚ ֹ ӄ ΋ኬ !!!!
PDD1/PD2 © Chi Mei Optoelectronics
Page27
Inversion Methods
++++ ++++ ++++ ++++
-------------
Frame Inversion
++++ ---++++ ----
---++++ ---++++
ˉ ˃ˁ˃˃ʸ ˇ ˃ˁ˃˃ʸ ˅ ˃ˁ˃˃ʸ
ᑇ٨˄
ႝᓸ ຫ ଯ Ǵ ऀ ೸ ‫ޑ‬Ӏ ຫ Ͽ
˃ˁ˃˃ʸ
ሽ ᚘ (V) ˃ˁ˃˃˃ ˃ˁˈ ˃˃ ˄ ˁ˃˃˃ ˄ ˁˈ ˃˃ ˅ ˁ˃˃˃ ˅ ˁˈ ˃˃ ˆ ˁ˃˃˃ ˆ ˁˈ ˃˃ ˇ ˁ˃˃˃ ˇ ˁˈ ˃˃
࿶ җу ӧన ඲ ΢ ႝᓸ ‫ޑ‬ଯ ե ё а ௓ ‫ ऀ ڋ‬೸ Ӏ ‫ޑ‬ӭ ჲ Ǵ ຾ Զ ௓ ‫ ڋ‬आ ᆘᙔΟ ᅿ Ӏ ‫ ߝޑ‬ས ำ ࡋ Ƕ
-
RDC
--
-
----
PI
ITO
The Residual DC drives the ions of the LC. The ions attach on the PI and do not release when the voltage is off . The previous image appears due to the internal electric field established by the ions.
PDD1/PD2 © Chi Mei Optoelectronics
Page23
DC Vcom
εЁκय़݈தҔ
Vcom (CFೡሽᄕ)
----
4V
++++
Vcom
++++
4V
----
+3V
-3V
----
++++
Vpixel +(T+F+T+ೡሽᄕ)7V
---Vpixel
ཱུ҅‫܄‬០୏
ॄཱུ‫܄‬០୏
Vpixel > Vcom
2.1V
1.9V 1.7V
0V
PDD1/PD2 © Chi Mei Optoelectronics
Page10
V-T Curve (1/2)
ઠຘ෷˄ ˅ (˃%ˁ˃˃)ʸ
˄ ˃˃ˁ˃˃ʸ ˋ ˃ˁ˃˃ʸ
˩ˀ˧ʳ˖̈̅̉˸
а90ࡋ4V TNࣁ ‫ٯ‬
ႝᓸ ຫ ե Ǵ ऀ ೸ ‫ޑ‬Ӏ ຫ ӭ
V-T curve!
ཱུ ‫ ܄‬ϸ ᙯ ០୏
DCූ ੮ , image sticking, image retention flicker (special test pattern) polarity inversion
PDD1/PD2 © Chi Mei Optoelectronics
Page2
ε ᆜ (2/2)
ჹ6 bitᡉ Ң Ꮤ Զ ‫ ق‬, Ӆ ё а ᡉ Ң 26 x 26 x 26 = 262,144 ჹ8 bitᡉ Ң Ꮤ Զ ‫ ق‬, Ӆ ё а ᡉ Ң 28 x 28 x 28 = 16,777,216
PDD1/PD2 © Chi Mei Optoelectronics
Page7
Color Depth (2/2)
OFF
16.7ms
ON
20 us
OFF
16.7ms
OFF
16.7ms
ௗ ๱ ᜢ ഈ ಃ ΋ӈ Ǵ ႝᓸ ς ࿶ ‫ ۓ ڰ‬Ǵ ‫ ܌‬а ᡉҢᚑ Յ Ψ ς ‫ ۓ ڰ‬Ƕ
໒ ௴ ಃ Β ӈ Ǵ ‫ ځ‬Ꭹ ϝ ߥ ࡭ ᜢ ഈ Ƕ ‫ ׳‬ཥ ಃ Β ӈ Կ Ⴃ ೛ ႝᓸ Ƕ
٩ Ԝ ᜪ ௢ Ǵ ё ֹ ԋ ᏾ ঁฝ य़ ϐᡉႽǶ