P. 2 SID Display Week 2012 June 2012
SOLOMONSYSTECH
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Display Interface Controller 2012 SID
Booth 111
P. 3 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Different Sizes of Touch Panels
Solomon Systech Limited
Small Size (up to 5”)Smart phones and portable game consoles
Medium Size (6” ~ 10”)Tablet PCs, Netbooks, GPS systems, Ebook, etc.
P. 4 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Different Sizes of Touch Panels (Cont’d)
Solomon Systech Limited
Medium Large Size (11” ~ 17”)Notebook, Ultrabook etc.
Large Size (18” onwards)All-in-one desktop PC, industrial applications, electronic billboards, etc.
CHALLENGES: in particular with medium-large and large size touch panels
P. 5 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Challenge ONE: Mechanical Bending
Solomon Systech Limited
Touch panel not solidly glued to the TFT Module Capacitance formed between touch panel ITO and the TFT module can vary with touch pressure.
TFT Module
Large and thin touch panel
Capacitive effect formedbetween touch panel ITOand the TFT module.
Heavily coupledregion
Lightly coupledregion
Lightly coupledregion
Mechanical bendingformed by touch pressure
P. 6 SID Display Week 2012 June 2012
SOLOMONSYSTECHChallenge ONE: Mechanical Bending (Cont’d)
Solomon Systech Limited
Even the variation in coupling capacitance due to touch pressure is only a few percents of the total capacitance of an ITO electrode can be an issue because:
The capacitance change due to a finger touch is also a few percents.
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Signal Amplitude
Panel X direction
Y directi
on
A frame scan image of a single finger touch with high touch pressure
P. 7 SID Display Week 2012 June 2012
SOLOMONSYSTECH
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Solution for Mechanical Bending
Solomon Systech Limited
SOLUTION:
Apply appropriate filtering by digital signal processing (DSP)
Bowl-shaped profile removed while keeping the general shape of the finger image
Signal Amplitude
Panel X direction
Y directi
on
After applying appropriate filtering by DSP
P. 8 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solution for Mechanical Bending (Cont’d)
Solomon Systech Limited
2-finger touch with extreme high touch pressure
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digital filtering
Signal Amplitude
Panel X direction
Y directi
on
Original sensed signal Signal after digital filtering
DSP engine inside the touch controller reclaims the finger image
P. 9 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Challenge TWO: Many Sensing Nodes
Solomon Systech Limited
312 sensing nodes (or cross points): 5” smart phone
1856 sensing nodes: 11.6” Ultrabook
4400+ sensing nodes: 18” all-in-one desktop PC
58 sense electrodes
11.6" panel size, 1856 crossover points(Landscape orientation)
5" panel size,312 crossover points(Portrait orientation)
13 sense electrodes
32 d
rive
elec
trode
s
24 d
rive
elec
trode
s
P. 10 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solution for Many Sensing Nodes
Solomon Systech Limited
SOLUTIONS:
Option 1: Increase scanning speed and data conversion speed of the touch controller.
Option 2: Use of partial or multiple-line scanning technique (Diagram)
non-scan region
scan region
scan region
fingerlocation
fingerlocation
Touch Panel
PartialScan
FullScan
P. 11 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Challenge THREE: Higher Resistance & Heavier Capacitance
Solomon Systech Limited
As panel size becomes bigger, the capacitance per ITO electrode becomes heavier.
The mutual capacitor and the capacitance of a finger keeps constant.
DriveLine
SenseLine
DriveLine
SenseLine
ITO
ITO
Finger Model
MutualCapacitor
P. 12 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Challenge THREE: Higher Resistance & Heavier Capacitance (cont’d)
Solomon Systech Limited
Resistance per ITO electrode is also higher
Higher resistance + heavier capacitance on larger touch panel transmission line effect more noticeable
Large panels have lower frequency response than small panels
Adverse effect: with more sensing nodes on a larger touch panel,we want to scan faster rather than slower
P. 13 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solution for Higher Resistance & Heavier Capacitance
Solomon Systech Limited
SOLUTIONS:Option 1: Drive the touch panel at both endsOption 2: Increase the driving voltage so that over-drive pulses can be deployedOption 3: Silver Nano Printing Technology
Over-drive driving signal
Large Touch Panel
Drive at both endsTouchController IC
P. 14 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Challenge FOUR: Noise Coupling
Solomon Systech Limited
As the panel becomes bigger, it becomes easier to pick up coherence noise from the environment
A typical example is the coupling between TFT VCOM and the touch panel when no ground shield is added.
Another example: switch mode power supply (SMPS) noise
P. 15 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solution for Noise Coupling
Solomon Systech Limited
SOLUTION:
Counteract these noise sources by adding noise cancellation circuitry to the analog front-end.
Sense Lines of Touch Panel
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Sensefrontend
Coherencenoise
detection
ADC
P. 16 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solution for Noise Coupling (Cont’d)
Solomon Systech Limited
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Constructive interference by applying a sinusoidal coherence noise source.
Destructive interference by applying a sinusoidal
coherence noise source.
After noise cancellation the finger signal is more stable.
Signal Amplitude
Sensing direction
Driving
directi
on
P. 17 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solomon Systech Solution
Solomon Systech Limited
Watchdog & Timers
uC
IIC slave Controller
ROM
Program and Data
Working Memory
to Host MCU
RAM
1.8V Reg, band gap &16MHz Osc.
GPIO
4 Ch Osc Self Cap
RAM
MUX
IIC Master ControllerEEPROM
0 1 2 3
32KHz OscPrescaler
23
1
0
Sleep Control
3rd Generation Front End
System Calibration
Scan Logic + M. Filter
Scan RAM +Delta RAM +
Reference RAM
Image Segmentation
4X sense channels3X drive channels
Cal Delta + 2D filter
MUX
2X/3Xcharge pumps
Cal finger C.G.
* DSP removes bowl-shaped profile due tomechanical bending.* DSP engine divided intovarious functions that canbe programmed by the uC.
* Develop partial scanningscheme to increasescanning speed for largepanels.
USB Controller FrontEnd to PC
DSP
2-st
ep A
DC
* This over-samplingADC provide anequivalent resolutionof more than 12-bit.
* Built-in noisecancellation circuitry
* For high voltagedriving.
SOLOMONSYSTECH
Thank Youhttp://www.solomon-systech.com
Email : [email protected] : 852-2207 1111 Fax : 852-2267 0800
P. 19 SID Display Week 2012 June 2012
SOLOMONSYSTECH
Solomon Systech Solution
Solomon Systech Limited
All-in-one touch controllerSupport up to 13” panelCan be interface through IIC or USB10 fingers + 2 palms detection4 independent GPIO pins and 4 independent self-cap sensing pinsAutomatic Power Down Mode to save powerDSP function to remove the bowl-shaped profile due to mechanical bending.Include smart partial scanning optionsInclude coherence noise cancellation for better S/N ratioBuilt-in booster for programmable high voltage driving