Touch Sensor Controller

Touch Sensor Controller

Fujitsu and @lab Korea 2

Touch Sensing a revolution Touch Sensing a revolution in Human Input Device Can replace virtually all mechanical buttons, sliders and turning knobs Create a simple, robust, clean und esthetic design Insolator (Set cover) Touch Pad (copper) PCB TSC C touch : the capacitance induced between finger and touch pad : the constant value of permittivity (Air=1, Glass=10, Acryl=5~10, Rubber=2~3) D: the thickness of the set cover A: the size of the touch pad 3

System Overview Parameters are loaded to from MCU to TSC MCU I²C bus 2508-40N Touch Pads Touch information as interrupt, wake up etc. Typical Applications Single Keys Output information: Which key has been touched MCU no need to process the touch data Advanced sensing (slide, wheel, approximation etc.) Output information Touch strength MCU needs to process the touch data 4

How does it work? Main Idea Digital Sensing Impedance includes capacitance, resistance, and inductance Impedance causes delay of capacitor charging time Time delay is measured Digital domain, no AD conversion Differential Signal Internal reference RC circuit Reference time delay can be calibrated Comparison between Input time delay and reference time delay If input time delay is larger than reference time delay by a certain amount touch event occurred No Ground Electrode needed for Touchpad 5

How does it work? - Touch Sensing [1] Not Touched [1] Z IN < Z REF α Z IN Z REF [2] Touched [2] Z IN > Z REF Touch pad Z IN Z REF Output Waveform Consistent sensitivity of the touch pad is maintained by setting proper value of α. 6

Advantages Extremely Fast Extremely Low Power Extremely Robust Extremely EASY to implement 7

Fast and Low Power Extremely FAST Response Time No complex signal processing needed Register programmable, 10 times/sec (100msec) ~ 5,000 times/sec (0.2msec) Allows data management, filtering, etc. Extremely LOW Power Consumption Supply current typical 120 A Active mode, 60 A Idle mode, 0.1 A Sleep mode Perfectly fit to portable products 8

Robust and Easy Implementation Extremely Robust Consistent sensitivity through AIC Resistant to outer signal disturbances through differential signal format Water resistant designs possible ESD protected up to 8KV (HBM) / 15KV (set / air) Extremely EASY to Implement One single electrode is sufficient for touch channel Advanced hardware functionality AIC impedance calibration APIS touch filtering High design flexibility Host interface via I²C up to 12 general-purpose IOs Individual channel sensitivity Touch strength output TSC can be either located close to touch pads or on the main PCB Touch pad can be as small as 1mm x 1mm Tuning Board with Tuning Viewer Program available 9

Automatic Impedance Calibration AIC (Automatic Impedance Calibration) Maintain consistent sensitivity despite environmental changes temperature, humidity, production tolerance, etc. Initial setup sensitivity Z IN Sensitivity = a Z REF Temperature PCB Humidity Lot External Changes Z IN Z REF Sensitivity = b Z IN Z REF Sensitivity changes with environment changes Sensitivity = c Sensitivity = a Sensitivity = a Sensitivity stays consistent Z IN Z REF Z IN Z REF AIC adapts reference delay line for each sensor individually to keep constant. 10

APIS APIS (Adjacent Pattern Interference Suppression) Filter out unintentional touches Reduce Software efforts APIS Mode 1 Reports the strongest output only APIS Mode 2 Reports all outputs that exceeds predefined thresholds APIS Mode 3 Reports two strongest outputs 11

Water Resistant Split pad Water Drop C touch Sensor Input Split pad Coupling Capacity between two electrodes is measured Finger increases capacity coupling Water drop has the same effect false touch detection GND Input GND Single pad 2508-40N Sensor Input Sensing Cap Ref Input Single pad 2508-40N No ground or reference electrode next to pad Capacity of pad is measured directly Water drop has nearly no effect no false trigger Water Drop 12

Tuning/Development Board DPI7 Tuning Kit Main Board Communication Line On /Off Switch 4CH I 2 C Communication Port ROM Select Switch BUZZ Power On /Off Switch USB Cable I 2 C Communication Cable DPI7 Touch Board LCD Bright Control Resistor Test Pin DPI7 Demo Board 16 X2 Display LCD 14

G Development Tools 15

Tuning Kit Tuning / Development Software 16

Applications of Touch Sensors Unlimited Applications ~ limited only by imagination Touch Sensor may REPLACE virtually all MECHANICAL buttons and scrolling knobs with ELECTRONICS. Buttons Slider Circular Scroll Or Navigation Invisible Buttons on LCD (ITO) Aesthetic Design and Higher Product Reliability 17

Why TSC? Key Technology Features Lowest Power Consumption Active (120~350uA), Idle (20uA), Sleep (< 0.1uA) Resistant to Water and Noise ~ Differential signal, No GND Fastest Response Time ~ 0.2 msec (5KHz) Wider Dynamic Range for touch No hardware tuning required Higher Sensitivity More sensitive to smaller changes in capacitance (time delay) Commitments to Customers Customer requirements: FPGA proof Close technical/commercial support On-site technical support, prototyping, proof of concept Meet quality and delivery schedule 18

Technical Position Architecture Analog Digital Touch Response Time Slow Fast Digisensor S, C, Q, A Single - End Differential Signal Format Small Large As small as 1mm x 1mm Sensing Pad Area 19

Strong Point 1. Consumption Current : 1/10 times comparing to competitors - Because of not using analog technology, circuit architecture is very simple. - Active mode : 130, Idle mode : 70, Sleep mode : 0.1 2. Response Time : 25 times comparing to competitors - Because it dose not need complex signal processing, can raise the data sampling rate. 10 Current [ma] 1 Q C S x 25 Faster Speed x 10 Less Power ATLab 0.1 0 1 2 3 4 5 6 Conversion Frequency [KHz] 20

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Strong Point Other s Solution Dielectric material C2 C3 Vs GND Equivalent Circuits C1 Sensing pad C1 C1 C2 C3 Vs Not Touched Touched Sensor Input Sensor Input C touch Sensing Cap Ref Input Water Drop Water Drop GND Input GND 22

Strong Point Inherently Differential Architecture Immune for External Noises Non-interrupt Touch Operation at active RF Multi-level Capacitance Values Change of Output RF Signal: 3Vp-p swept from 100MHz to 2.4 GHz, Korea MIC Condition Frequency [GHz] 23

Strong Point Low Input Impedance Higher ESD Voltage 8KV 6KV HBM: 8KV (Input Sensor) Set: more than 15KV 4KV 2KV Analog Touch Sensor DigiSensor 24

Strong Point High Sensitivity 30 ff/step now (x 5 than others), break 1 ff barrier soon. Small sensing area Better resolution Extend to another applications (e.g. proximity sensing, display embedded touch screen) Digital Advantages Following Moore s Law / Insensitive to Foundry/ Technology Low Power & Best for Portable Electronics Longer Battery Lifetime / Touch Wake-up Fast Sampling Less Noise Aliasing / Capable for Signal Conditionings 25

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Available TSC Products Product No. of Ch. Matrix of Ch. No. of DIO or LED Interface Operating Voltage LED Control LED Dimming Package Size [mm] 28

TSC Product example Available Packages 29

Target Applications Home Large Appliance Wash machine, dryer, hob, stove etc. Small Appliance Cooker, microwave oven etc. Consumer devices Remote control, DVD player etc. 30

Target Applications Industrial Application examples ---- wherever robust human input device is needed Control panels Medical instruments Test & Measurement Equipments Special vehicle 31

Target Applications - Portable devices 32

Target applications - office devices And Many More 33

Application implementation Function Spec. Hardware Solution Firmware Solution Touch Pad Design (PCB/ITO) MCU Coding Tuning H/W, S/W Finalize register set values and firmware Production Tuning can be done on site during production. 34

Typical Implementation example Portable Multimedia Player Exhibited in CES 2006 Currently in mass production For Buttons For Scrolling DCC on touch B/D 35

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