seminar on lcd & flat panel displays
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BY CLOVER DISPLAY LTD.
(HONG KONG S.A.R, CHINA)AN LCD MANUFACTURER SINCE 1983
URL http://www.cloverdisplay.com &
DATE :Sept 29, 2005
SPEAKER
Mr. JOHNNY C. L. CHOU
<Topics>1. FLAT PANEL DISPLAY 2. INTRODUCTION TO LCD TECHNOLOGY.3. HOW LCDs ARE MADE.4. COLOR LCD5. TODAY’S LCD6. CUSTOM DESIGN LCD & LCM (MODULES).7. TOUCH PANEL, Bi-STABLE LCD & ORGANIC LED.8. QUESTION & ANSWER. Edition #7 (2005)
SEMINAR ON LCD & FLAT PANEL DISPLAYS
1.0. FLAT PANEL DISPLAYS
Display Types
( commonly used Display )
Emits
Light
Voltage Current Patterning
Flexibility
CRT ( Cathode Ray Tube ) Yes High DC Low ( scanning )
VFD ( Vacuum Florescent Displays )
Yes High DC Low Medium
LED ( Light Emitting Diode ) Yes Low DC Medium Low
Plasma Displays Yes High DC Low Low
EL ( Electro Luminescent Displays )
Yes High DC Low High
LCD ( Liquid Crystal Display ) NO Low AC Low High
OLED (Organic LED) Yes Low DC Low-medium
High
P.1.
2.1. Three major characteristics of Liquid Crystal
2.1.1. The Thermal Nature
High Temp
Clearing PointMelting Point
Liquid State
Liquid Crystaline State
Solid State (Crystal)
2.1.2. The Optical Nature of a LC molecule
LightNO light passing through
Light passing through
Low Temp
2.1.3. The Electrical Nature of the LC molecules
AC potentialNo potential field
Electrodes
P.2.
2.0. LIQUID CRYSTAL
XXX
Smectic Phase Nematic Phase Cholesteric phase
2.2. COMMON STRUCTURAL PHASES in the Liquid Crystal State
P.3.
2.3. Two other components to make a Liquid Crystal Display Panel 2.3.1. Transparent Electrodes ---- Glass with conductive ITO layer which is
etched to form a pattern. 2.3.2. The Polarizer Film
Light wave& its axis
Polarizer &its light axis
Outgoing light& its axis
2.4. A TYPICAL TN TYPE LCD CELL
With AC Voltsconnected
NO powersupply
Polarizer(Axis 0 degree)
Polarizer(Axis 90 degrees)
Glass with electrodes
Glass with electrodes
Light
Cell Gap =The separationbetween two glasses
Positive Mode = Black digit on the grey backgroundNegative Mode =Clear digits on the dark background
P.4.
2.5. THREE COMMON TYPES OF LCD
Light(Back Light)
2.5.1. TRANSMISSIVE TYPE
2.5.2. REFLECTIVE TYPE
POLARIZER ON THE FRONT SIDE REFLECTOR ON THE BACK SIDE
Incident Light
2.5.3. TRANSFLECTIVE TYPE
Day LightNight Light(Back Light)
TRANSFLECTOR ON THE BACK SIDE
POLARIZER ON BOTH SIDES
POLARIZER ON THE FRONT SIDE
LCD
LCD
LCD
Eyes
P.5.
2.6. CHARACTERISTIC CURVES
% LIGHT ABSORPTION(or TRANSMISSION)
VOLTS
Vs (Saturation Voltage)
Vth (Threshold Voltage)
10% change
90% changesAt higherTemp.
Time
% LightAbsorption
Ton 5ms to 100ms Toff 20ms to 300ms
Depending on how the LCD fluid is formulated.The smaller the cell gap, the faster response.
0 volt
Vth of LC
-40 deg C +80 deg C
5 v4 v
-40 deg C +80 deg C
LC FluidViscosity
10,000
100
mm2/sec
At a lowerTemp.
P.6.
2.7. TN & STN (Super Twisted Nematic)
mid-plane tilt angleVth Vs
The LC molecule
90 degTwisted
180 deg 240 deg
Volts
% Light Absorption
0
% Light Absorption
0
% Light Absorption
0
Twisted Twisted
V V
Narrow View Angle
TN LCD STN LCD
Wide View Angle
Grey Backgroundin the positive mode
Yellow Green background colorIn the positive mode P.7.
2.8. HTN (Highly Twisted Nematic) & FSTN (Film STN)
TN90 deg Twisted
STN180 deg or higher degTwisted
HTN110 degTwisted
Narrow View AngleWide View Angle BUT with Darker Color Background &Blue or dark blue patterns.
Wider View Angle than TNbut narrower than STN
FSTN240 deg or higher degTwisted
View angle same as 240 deg STN BUT in Grey Background Color& Black patterns.
LCD Cell
Retardation Films on Polarizersto correct the color phase
DSTN (Double STN Cells)
1st Cell with patterns Same as usual STN
2nd Cell without patternBut in reverse twisting
Old waywhen NORetardationfilm
1st Minimum TN
Little wider View Angle than TN(see later pages)
Polarizer
P.8.
2.9. COMPARISON AMONG TN, HTN, STN & FSTN 2.9.1. Positive Mode (Pattern on a Clear Background)
Either TN HTN STN STN FSTN
Deg Twisted 90 110 180 240 240
Background
Color
Grey Grey Yellow Green
or Grey
Grey or
Yellow Green
Grey
Pattern Color
Black Black Dark Blue
or Blue
Blue or
Dark Blue
Black
Temp Range
-40C to +85C -20C to +40C -20C to +70C -20C to +70C -20C to +70C
Multiplex Ratio
=< 1/8 duty =<1/16 duty =<1/32 duty =<1/240 duty =<1/240 duty
View Angle 60 deg 80 deg 120 deg 120 deg 110 deg
View Direction
At 6 or 12 O’clock ONLY
At 6 or
12 O’clock ONLY
May specify
6 or 12 O’clock
May specify
6 or 12 O’clock
All
Voltage 2.5v min
5v typical
3v min
5v typical
3v min
5v typical
5v typical, (higher duty, higher volts)
5v typical, (higher duty, higher volts)
P.9.
2.9.2. Negative Mode (Clear Pattern on a Color Background)
TN HTN STN STN FSTN
Degree Twisted 90 deg 110 deg 180 deg 240 deg 240 deg
Background
Color
Black Black (Seldom used) Dark Blue Black
Pattern Color Clear Clear (Seldom used) Clear Clear
Other natures same as the Positive Mode.
2.10. Gooch-Tarry Curve --- The 1st Minimum TN LCD% Transmission
12%
0%
4%
8%
d n(um)0.48 (1st Min* ) 1.05 (2nd Min) 1.64 (3rd Min)
n : Birefringence (reflective indices ofLight transmitted in parallel & perpendicularTo the director of LC molecules.
d : the cell gap
P.10.*The 1st Min process is patented by E. Merck.
2.11. THE STATIC & MULTIPLEX DESIGN OF ELECTRODES
4 pairs of electrodes8 connectors needed.
No time sharing for the input signals –The STATIC Design
5 electrodes5 connectors needed.
1/4 time sharing for the input signals to each of the top electrode.No time sharing for the bottom glass.We call the top electrodes the SEGMENT while the bottom electrodes the COMMON.
4 electrodes in matrix4 connectors needed.
1/2 time sharing for the input signals to both the top and bottom electrodes----The MULTIPLEX Design.
We call it 1/2 duty if the 1/2 time sharing is used on the Common.
The higher the duty ratio, the shorter time the power signal goes into each electrode pair. Finally the power rms value may NOT be enough to fully drive the LC twisting properly.
PROBLEM:
P.11.
2.12. THE PASSIVE AND ACTIVE LCD
Signal
Signal
Time
Time
X1
X2
Y1 Y2
An ACTIVE Component ;MIM (metal insulator metal) DiodeOrTFT (thin film transistor)
The LCD Pixel
The TFT method is commonly used today on the large DOT MATRIX LCD,we call it the ACTIVE MATRIX LCD, or AMLCD
The LCD built together with the Active Component is not only the TFT LCD. The LCOSis also an LCD built on a silicon wafer with active components to control the LCD.
In general, the duty ratio over 1/256 may not give a good contrast in the Passive design.But there are still some special design to work in the Passive way, such as;Dual Scan STN (DSTN), High Performance Addressing (HPA), …. etc
P.12.
2.13. THE HISTORY OF LC & LCD
Application Approx Year Major Development
1888 Liquid Crystalline initially described by an Austrian Scientist,Mr. Friedrich Reinitzer.
1904 E. Merck sold the first Liquid Crystal substrates to the research market.
1960 Westinghouse used the cholesteric LC as a temperature indicator.
1965 RCA demonstrated a dynamic scattering LCD to show numeric symbols.Kent State Univ. in Ohio USA presented an LCD operated at room temp.
1970 Rockwell (USA) and Sharp (Japan) made LCD Calculators.Hull Univ. in England synthesised new biphenyls with excellent physicalproperties for display use.
Higher Contrast Twisted Nematic Mode in use.OCLI (USA) coated ITO on glass as electrodes.BDH (UK) sold LC to LCD manufacturers.
1975Hamlin Inc (USA) in TN LCD mass production.E. Merck introduced Biphenylcyclohexanes LC for higher multiplex.
Motorola built LCD on 4 ½”x 4 ½” glass substratesMicroma (USA) further improved the mass production technique andFairchild Semiconductor Inc. moved LCD production to Hong Kong.Timex (USA) bought RCA LCD facility and merged with Fairchild.
The Japanese developed a Chemical Sealing process for cost reduction.
Thermometer
Calculator
Time pieces
Instruments
Data bank & PDA
P.13.
Application Approx Year Major Development
2.13. THE HISTORY (continued)
The first LCD scriber made by Villa Precision Inc. (USA)
1980 Roche, BDH, E.Merck improve LC mixtures for TN, STN
Fairchild scaled up to 14x14” substrates5x7 Character
Dot Matrix GraphicWord Processor
Clover Display Ltd established in May 1983
MIM & TFT AMLCD inventedFull Dot Matrix &TV Panels 1985
PDA, Laptop & Notebook PC
Brewer Science Inc. & OIS of Troy, USA developed colourAMLCD for space shuttle use.
Full color TFT panel for Notebook PC
1990
1995
2000
Bi-stable Cholesteric LCD
E Books
Mobile phones
New Display to replace LCD ?---- OLED, PLED
P.14.
3.0. HOW LCDs ARE MADE 3.1. THE FRONT END PROCESS
ITO Glass ITO = Indium Tin Oxide, a transparent conductive layer coated on the Sodium Lime Glass. Its resistance is from 10 Ohms to 120 Ohms/square.Glass area usually in 14x16”. Thickness in 1.1, 0.7, 0.5, 0.4, 0.3mm
Clean Glasswith DI water
Patterning theElectrodes on ITO
Artwork & Mask Design
Methods: Photo Masking, Resist Ink Printing, ITO Ink direct Printing, Laser Cutting.
Alignment Layer
Sealing Frame &Silver Dot Printing
Top/bottom GlassAlignment and Seal
To form the cell and the inter-connections between the top and bottom glasses
To form a rough surface to hold the LC molecule chains
The Laminated pairs
P.15.
3.2. THE BACK END PROCESS
Laminated PairCutting into cells
Liquid Crystal Filling
Liquid Crystal MixtureFormulation
End Sealing & Cleaning
Testing & Inspection
Polarizer Fixing
Polarizer Cutting
Cosmetic Check
ShipmentsOptional Process
Metal Pin or Heat Seal Connector fixing
LCD Module Assembly (COB, TAB, COG, COF)
P.16.
4.0. THE COLOR LCD
Black and White LCD Full Color LCD
Slice ITO into narrowsections
RGB ColorFilter
Segments
Common
Common
The color LCD can be built as a Passive LCD. But most large size Dot Matrix Color LCDs are built in the Active design.
P.17.
In order to give a better color mixing,the RGB line widths are usually lessthan 30 micron in width per color. Hence the same for the ITO electrodes.
4.1. THE FULL COLOR LCD
4.0. THE COLOR LCD (continued)
4.2. THE ECB (ELECTRICALLY CONTROLLED BIREFRINGENCE) COLOR LCD
Clear DarkGrey
Y O R P B GColor around2.4v to 3.7v
DarkV
% LightAbsorption
0
V
Various ECB Types;
1) Homogeneous TypeRed->Yellow->Green->Blue
2) Deformation of Vert Aligned Plane (DAP) TypeBlue->Green->Yellow->Red
3) Hybrid Aligned Nematic (HAN) TypeGreen->Red->Blue
4) Vertical Aligned Nematic(VAN) Type
P.18.
No pure color, 50% Green + 25% Red + 25% Blue at this point
4.3. DOUBLE CELL COLOR LCDThere are two kinds of double cell can generate colors;A) With Color Polarizer B) With usual Polarizers at certain angles (Only working in Transmissive Mode) (Reflective Mode is also possible)
4.4. GUEST HOST LCD (Single fixed color)Mixing color dye in the LC fluid and build LCD in Negative Mode.It will show clear pattern on a color background.Such method was used in the early date.
4.5. LCD WITH COLOR POLARIZER, COLOR FILM OR COLOR REFLECTOR IN CERTAIN AREA (fixed color)
4.6. COLOR INK PRINTING ON THE BOTTOM GLASS SURFACE (fixed color)
Pre-printed color polarizer is expensive.
This is the cheapest way to make LCD with fixed colors.The LC image & color area may not coincide well due to the glass thickness.
P.19.
5.0. TODAY’S LCD
Duty Ratio
Panel Size
1/1Static
1/2
1/3
1/4
1/8
1/16
1/32
1/64
1/256
10 mm2 100 1,000 10,000 100,000 mm2
Time piecesHand Held Games
Film Camera
Calculator
Data Bank
Mobile Phone Digital Instruments
PDA
Digital CameraOffice Equipment
Notebook PanelsProjector Portable TV
Active LCD
Passive LCD
STN
TN
1M+ Pixels
100K Pixels
10K Pixels
1K Pixels
100 Pixels
P.20.
LCD TV & Monitors
1/128
6.0. CUSTOM DESIGN LCD & LCM --- The factors to consider6.1. LCD PANEL DIMENSIONS
Outer Dimensions (Be economical size)
View Area (normally 2mm from the edges)
End Seal (0.5mm thick)
Active Area (Area with patterns)
Pinout or Connection Area (2 to 2.5mm)
Glass Thickness (1.1, 0.7, 0.5, 0.4 or 0.3mm/one side)
Economical Panel Size: The outer dimension may use up most the raw glass sheet area.
14x16 inches(355x406 mm)
7x8 inches(178x203mm)
For small order size or pilot run,7x8 inches sheets are used to boostup the yield and save the tool cost.
(The usable area is 7mm off the edge)
( Glass Material: Sodium Lime Glass with SiO2 barrier, surface polished for STN use )
P.21.
Raw Glass Sheetor
6.2. PANEL CONFIGURATIONS
Eyes
A B C D
Connectors suitable:Zebra (Silicone Rubber) – A, B,Heat Seal or TAB – A, B, C, D,Metal Pins – C, D,
All the above 4 models required Ag (silver) connections inside the LCD cell.If such Ag connection not to be used or unable to be used, the configurations will be as follows;
The thick lines representingthe pinout areas.
E F G
Models E, F & G are good for combination use of Zebra and Heat Seal connectors together.Most TAB connections are also applying on such models.
P.22.
For TN LCD, don’t forget to specify the View Direction
12 O’clock 6 O’clock
45+deg 15+deg40+deg 40+deg
15+deg 45+deg
6.3. PATTERN LAYOUT
C S1 S2 S3 S4 S5 S6 S6 S3 C S1 S2 S4 S5
GoodLayout
BadLayout
Too Long Trace Cross Over Narrow down trace
+
P.23.
6.4. ZEBRA CONNECTORS
Side Wall Insulators
Conductive Layers
Insulation Layers
Pitch: (Conductor/Insulator Layers)Low Cost Type --- 0.25+-0.05mmGeneral Type ----- 0.18+-0.04 mmDot Matrix Type – 0.10+-0.03 mmGraphic Type ------0.05+-0.025 mm
Contact Resistance: 1000 –1500 ohms at 10%-15% compression
Metal Mounting Bezel
PCB
LCD
Zebra
Assembly
Mis-aligned Good A safer way(wider contact on PCB)
LCD
Zebra
•Pre-clean Zebra•Three or more conductors in contact•PCB wraping <0.375mm / 50 mm•Bezel has opening gaps with PCB•0.3mm or 10%-15% compression•Dummy zebra use with single side contact LCD. •Insulation side wall quality.
Precautions in Assembly
P.24.
Three kinds of Rubber
1. Sponge Rubber
2. Silicon Rubber
3. Super Soft Rubber
6.5. HEAT SEAL CONNECTORSConductors (~20 um particles) printed on a Polyester (PET) Film of 20 -25um
Contact Resistance & PitchGraphite Type --- 35 to 100 ohms/sq 0.40, 0.60, 2.80 mmSilver Graphite Type ---- 0.5 ohm/sq 0.23, 0.35, 2.80 mmSilver Type ------ 0.05 ohm/sq 0.23 mm
Choose proper LCD configuration:
PET side
Conductor sideLCD
PCB
LCD
PCB
PET side
PET side
Hot Press
PCB
PET film
Welded
Precautions in Assembly
•The Hot Press head temperature 120-140 deg C at joint•32 Kg/sq cm pressure is recommended•Leveling the press for even pressure along the joint.•Properly select the sealing time to prevent uneven flow or wash away the conductor particles.•100pcs/mm2 particles at contact area is suggested.•Peeling off strength be >200gm (Vertical) & >500gm (Horizontal)
P.25.
6.6. METAL PIN CONNECTORS ( for 0.7 & 1.1mm glass )
LCD
Standard Pitch: 1.27mm, 1.8mm, 2.0mm, 2.54mmPin Length: 20mm, 30mm, & 45mm max
Contact Resistance: <0.05 ohm
Precautions in Assembly:• Prolong soldering may damage the Pin contact to glass ---- A good LCD will add carbon cushion between pin clip and glass contact area.• Care on bending the pins ---- LCD maker provides pin lead forming.• Pin length under 4.0mm is not recommended.• Wave solder is not recommended ---- Polarizer is weak• Mechanical stress on pin or temperature changes may cause LCD background color changed.
6.7. TAB (TCP IC BONDING)
IC on a flexible filmwith conductors.The Film is heat sealedonto the LCD pinout area
LCD
P.26.TAB = Tape Automation BondingTCP = Tape Carrier Package
All the above connections may have IC on PCB by SMT, Wire Bonding (COB) or Insert & Solder.
Epoxy enforcementWider seal area isrequired.
Clip Depth 2.0mm to 2.4mm max
6.8. CHIP ON FILM (COF)
Same as TAB, but with morecomponents on the film likea circuitry on PCB
LCD
6.9. CHIP ON GLASS (COG)
LCD
IC Chip
Glass withFine tracesFan-in &Fan-out
Same as anusual LCD
Most panels with Metal Pins
The IC Chipfor COG isdifferent fromthose for usualwire bondingon PCB.
P.27.
ACF* film is used to fix theCOG chip onto the glass.The ACF film is similar to Heat Seal but with much finer Pitch and conductive particles. * ACF=Anisotropic Conductive Film
6.10. TRICKS ON THE LCD PANEL DESIGN6.10.1. THE BIAS VOLTAGE
% LIGHT ABSORPTION
10%
90%
0 volt
Volts
VoltsVth
The Bias Voltage
Time
The drivingVoltage
Theoretical Driving Waveform
Applied toSegment
Applied toCommon
ResultingWaveformto LCD
Off On
Practical Design Waveform
(Example: Waveform to LCD at 1/3 Bias)
Off OffOnV
2/3V1/3V
0-1/3V-2/3V
-VP.28.
Recommended Driving Freq60 Hz to 120 Hz
6.10.1. THE BIAS VOLTAGE (continued)
P.29.
The formula and design facts;N: Multiplex Rate. Example: N=3 for 1/3 dutyS: Bias The ideal design S=1+ NVd: The supply voltage to the panel.
Von = ( Vd / S ) x ( N-1+S ) / N
Voff = ( Vd / S ) x [ N – 1 + ( S – 2 ) ] / N
2
2
N 2 3 4 8 16
S 2 2 3 4 5
Vd 3 volts 3 volts 3 volts 3 volts 5 volts
Voff 1.06 v 1.22 v 1.00 v 0.88 v 1.22 v
Von 2.37 v 2.12 v 1.73 v 1.27 v 1.58 v
Von – Voff 1.31 v 0.90 v 0.73 v 0.39 v 0.36 v
Less than 1 volt !Beware the drifting under temp changes
6.10.2. CROSS OVER LAYOUT
C2
S1 S2 S3 S4
C1
C1
2 cross over points
Hided under Frame
Epoxy Sealing Frame
Ag DotConnection
6.10.3. THE POLARIZER SELECTION•The Glue Type or Non-glue Type polarizer. •The Polarizer with the UV Barrier may extend the LCD Life under strong UV exposure.•The Anti Glare Polarizer may improve the contrast.•The high durability polarizer may stand for wider temperature environment.•The slightly orientation of Polarizer axis may change the background color.
P.30.
6.11. THE THERMAL COMPENSATIONIt is recommended to use the thermal compensation circuit when a LCD will be operated undera wide temperature range.
6.12. TEMPERATURE RANGE
TempDeg C
0 deg-20-30 +50 +60 +75 deg
General purpose
Low Temp Type
Wide Temp Type
OperatingTemp.
StorageTemp 10 deg C lower 10 deg C higher
Problemwhen exceedsrated temp.
Black SpotsSlow response
Background blackenedCross Talk
The STN temp is 10 deg narrower than TN
All the above defects are reversible at room temp
Temp
-40 deg +10 +30 deg +100
Possible design
Specific for Low TempSpecific for High Temp
P.31.
Clearing point
Melting point
6.13. BACK LIGHTS
Choice of
Back Light
Descriptions Common
Color
Side LED Type
( Fig. 1 )
Wedge diffuser (Light Guide) and reflector are needed.
Poor illumination for large panel
Yellow Green,
Blue, White
Array LED Type
( Fig. 2 )
Consuming more power and generating more heat.
Beware the difference in supply voltages of each model. Easy assembly
Yellow Green,
Red.
EL (Electro-
Luminescent)
The best in even brightness and light weight. But less brighter than LED Backlight. High voltage and EMC consideration.
Green, Blue,
White.
CCFL (Cold Cathode Fluorescent Lamp)
The strongest illumination.
High voltage and EMC consideration.
White.
Important: The Transmissive and the Transflective Type LCD absorb the different light intensity.
Diffuser Paper
Reflector PaperReflector domes
LEDs
Light Guide
Fig. 1. Fig. 2.
Light Light
P. 32.
LED wiring
+
-
7.0. BI-STABLE LCDBi-stable Cholesteric Display, orSSCT – Surface Stabilised Cholestric Texture Display, orMulti-stable Chiral Nematic Display, orE-Book Display
This is a new technology in LCD making use of the Cholesteric Liquid Crystal. Mr. John West and Mr. D. K. Yang of Kent State University, Ohio, USA filed the patent in 1995. The display image is retentive in the absence of an electric field. It has a excellent readability and wide view angle under the daylight or strong ambient light. No Polarizer is required on this kind of display panels.
The Liquid Crystal is switchable and stable in two kinds of texture.(a) The Twisted Planar Texture, which has the LC layers parallel to the display surface, reflects the incident light.(b) The Focal Conic Texture, whose LC is in fragmentary, scatters the incident light.
Switch-able
The above two textures are switch-able under 30V to 180V pulse of 10ms to 100ms, and stable in zero electric field. By properly adjust the pitch of the Twisted Planar Texture, it can reflect R, G, B lights.
P.33.
(a) (b)
8.0. ORGANIC LEDThe Organic Electro Luminescent Displays (OELD) , or The Organic Light Emitting Devices (OLED)
The EL ( Electro-luminescence ) Back Light for LCD has been used for many years. It operatesat high voltage (>100V). In 1987, Tang and Van Slyke in Kodak, USA reported a low voltage (<10V)Organic EL. It comes a new display ---- the OELD.
8.1. THE BASIC STRUCTURE Metal CathodeElectron Transport LayerRe-combination and Emission Layer
Hole Transport Layer
ITO Layer (Anode)Glass Substrate
Light emits
8.2. THE DIFFERENCE BETWEEN LCD & OLED LCD OLEDNo Light emission Emits light in colours (100cd/sqm)Narrow view angle Wide view angle (>150 degrees)Slow response Fast response (<10 microsec)
OLED has most the advantage of LCD such as; Easy patterningLow operating voltage but at high current ( 20ma/cm2)Low manufacturing costThin and light weight P.34.
DCvolt
8.0. ORGANIC LED (continued)8.3. THE OLED & PLED
There are two major ways to build the OLED;a. The small molecule process ---- by spluttering the organic materials onto the ITO patterns. Kodak uses such way.b. The large molecule process, or the polymer process ---- by spin coating, dip coating or screen
printing the organic pastes layer by layer. Cavendish Lab in Cambridge, UK and DowCorning, USA developed such process and materials in ’90s.
Some people now call the OLED made under polymer process the PLED.The small molecule process is also applying to making the ACTIVE OLED.Pioneer, Japan seems the first one in mass production for the OLED.It is expected the OLED will replace the LCD step by step from 2005.
CLOVER DISPLAY GROUP has started a joint venture with the University of Hong Kong to researchand develop the materials and process for OLED. The newly formed joint venture company is named COLED DISPLAY LTD., established Sept 2002.
P.35.
9.0. TOUCH PANELS9.1. ANALOG TYPE
PE FilmWith ITO
Glass withITO
SilverConductors
Pin outArea
Epoxy dots As Spacer
Ra Rb
Rc
Rd
A PE film with ITO layer is sealedonto an ITO Glass with epoxy dots asSpacer to maintain a gap. When the external pressure of touching makes contact of two ITOlayers, the sensing IC circuit with givean analog reading corresponding to thetouch position.
9.2. DIGITAL TYPE
PE FilmWith ITO
Glass withITO Pin out
Area
Epoxy dots As Spacer
The ITO on the PE Film and theITO Glass are etched out into sectors.When touched, the correspondingsectors are shorted circuit and reflectedto the pins concerned.
P.36.
10.0. CUSTOM LCD/LCM DEVELOPMENT GUIDE.Enquiry from Customer
Feasibility Study & NRE Charge / Unit Price Quoted
Free quote in 2-4 working days
NRE Order Confirmation NRE payment in advance
LCD Panel PCB & Circuit External Casing
Panel Drawingfor Approval
Circuit diagram& PCB Layout
Case Drawing
1 week 1 week 1-3 weeks
Mask Design& Samples**for Approval
PCB Tool Design& Samples** forApproval
Hand mould up sample
3-6 weeks
3-4 weeks 3-10 weeks
Primary Sample
Final CaseMould
Final Sample
3-9 weeks
Total development time;LCD Panels 4-7 weeks, LCM Modules 4-10 weeks; With External Case 7-18 weeks
** normally 10-20 LCDor 3-5 LCM sampleswill be free. For more qty,please notice us in advancewhen confirm the NRE order.
P.37.
11.0. ACKNOWLEDGEMENT & DECLAIMER
We have tried our best to present up-to-date and correct information here. Some of them to beexplained together with photographs and demonstration samples to form a complete part of theIntroduction. We wish that the information discussed in this seminar may help the design engineers to makea cost effective and quality custom design in an easier and logical way. However, this is not an academic seminar that we have used a simply way in the presentation.All information here is provided in good faith without any expressed or implied warranty. The readershould seek for more detail advice from the industry.
The information in above are partly referring to the following documents;1. Proceedings of the Liquid Crystal Seminar HK by E. Merck, Darmstadt, Germany.2. Various articles in the SID International Symposium and Information Display by the Society for
Information Display, Inc. USA3. LCD Displays, the leading edge in flat panel displays, by Sharp Technical Library, Vol. 1, of
Sharp Corporation, Osaka, Japan.
Prepared by;Johnny C. L. Chou, Clover Display Ltd. Room 1006, 26 Hung To Road, 10/F, Kwun Tong, Hong Kong Tel: 23428228, 23413238 Fax: 23418785, 23574237 email: cdl@cloverdisplay,com URL: http://www.cloverdisplay.com (in English) http://www.cloverdisplay.com.hk (in Japanese) http://www.cloverchina.com (in Chinese)
Editions: 7th edition Sept 29, 2005 6th edition Mar 13, 2003. 5th edition Sept 19, 2001. 4th edition Apr 16, 2000. 3rd edition Sept 6, 1999. 2nd edition Sept 1, 1998. 1st edition May 19,1997.All copy rights reservedClover Display Ltd. H.K.
P.38.
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