Karlheinz Blankenbach

Transcription

1 Karlheinz Blankenbach Pforzheim University, Germany Prof. Dr. Karlheinz Blankenbach Pforzheim University Tiefenbronner Str. 65 D Pforzheim, Germany Phone : Fax : kb@displaylabor.de Web : 1

2 Overview Introduction Touch Screen Technologies Application Issues Summary Some slides are from Touch Screen tutorials given by 3M, Fujitsu, Walker Mobile & Elo TouchSystems 2

3 Touch Screens Why? Easies many HMI concepts by direct input (command buttons etc.) Mature technologies available Allows easy input incl. characters and graphics e.g. smartphone Space saving compared to keyboard and mouse Why not? Rise in some application system costs Reduced ambient light performance of display Inadequate performance of text input via stylus (is also an additional item!) Often more time consuming than keyboard and mouse 3

4 Touch Screens Why - because it is in! Touch is not only technology it is also user interface driven! 4

5 Touch Screen Basics Finger input: - simple, no device required - but low resolution Sylus input: - simple, high resolution (> 50 ppi) - stylus required - SW for text input 5

6 Touch Screen Applications Point of sale (POS) in restaurants, hospitality, post offices, ATMs Industrial/process control Medical equipment Office equipment like copiers Retail Automotive: navigation, diagnostic systems Personal mobile device Kiosks: Point of information (POI), merchandising, tourism & museums, digital photo printing stations, Ticketing & vending incl. transportation Gaming, amusement, Telecommunication Web phones Internet terminals Outdoor: Gas pumps, store window applications 6

7 Touch Screen System includes - Touch sensor - Touch controller - Software 8

8 Touch Screen System Route the touch screen cable away from the LCD backlight inverter System becomes more complex 9

9 Touch Screen Cost Share About the same price as for LCD! 10

10 Overview Introduction Touch Screen Technologies Application Issues Summary Analog resistive Surface capacitive Surface acoustic wave (SAW) Infrared (IR) Projected capacitive Optical Acoustic pulse recognition Dispersive signal technology 11

11 Touch Technologies 1/2 12

12 Touch Technologies 2/2 13

13 Analog Resistive (I)

14 Analog Resistive (II) Principle To TS controller Short 15

15 Analog Resistive (III) In-flight entertainment system Spacer visible 16

16 Analog Resistive (IV) Calculation of touch impact position x R R 1 2 x y Multi touch??? y R R

17 Analog Resistive (V) Size range: 2 to ~26 Major applications: - Mobile devices (replaced in smartphones by projected capacitive) - Point of sale (POS) terminals 2006 market share - 90% by volume - 75% by revenue Selected suppliers: - Elo TouchSystems, Fujitsu, Gunze, Touch International suppliers worldwide 18

18 Resistive Touch Screen Controller 19

19 Resistive Touch Screen Board 20

20 Resistive Touch Screen Protocol Touch electronics use a communications protocol - Embedded systems e.g. I2C, SPI, UART - PC-based systems USB, RS232 21

21 Capacitive Overview (no multi-touch) Only small changes of capacity are forced by finger etc. sophisticated touch controller and algorithms needed 23

22 Projected Capacitive (I) Principle: Electrical field changes due to influence of dielectric parameter Push (like whole touch awareness) by APPLE s IPHONE 24

23 Projected Capacitive (II) A specially structured multi-layer ITO-film is fully laminated to a glass substrate. By the specially structured electrodes an electric field will be projected through the glass substrate. Screen This electric field changes due to the influence of a touch element (finger). The dielectric parameter will change and the controller can calculate the position of this change. The touch finger does not need to be conductive! 25

24 Projected Capacitive (III) 26

25 Projected Capacitive (IV) Data acquisition path 27

26 Projected Capacitive (V) IPHONE Hardware 28

27 Projected Capacitive (VI) IPHONE integration 29

28 Projected Capacitive (VII) IPHONE HMI Examples 30

29 Projected Capacitive Touch Integration Source: Display Search 2012 one glass 31

30 P-Cap Touch Signal Processing - Control sensor electrodes to generate raw data Noise avoidance via multiple techniques: Frequency Shifting, CDM, etc - Process data to convert to image data - Derive and report data about finger touches (position, width, gestures) 32

31 P-Cap Touch Screen Method The basic construction of a projected capacitive sensor typically uses two dielectrically separated layers of glass patterned with ITO that are configured in rows and columns positioned perpendicularly to create a matrix. Projected capacitive functionality is achieved by scanning along each axis, identifying high capacitance lines, then determining a position by the intersection of those high capacitance lines. This scanning system and the sensor pattern allow potential decoding of multiple simultaneous touch points known as multi-touch capable. Two capacitance measurement methods: - Capacitive Sensing (CSM) - Charge Time Measure Units (CTMU). 33

32 P-Cap Touch Screen Board 34

33 P-Cap Touch Screen HW & SW 35

34 Surface Acoustic Wave (SAW) 42

35 Integrated Touch In-cell light sensors capture position like a flat camera Multi touch! 43

36 Integrated Touch Integration of an array of TFT optical sensors into the LCD s backplane Like a camera without a lens Works with finger, stylus, light-pen or laser pointer Works as a scanner (e.g., for business cards) TMD was in 2003, SHARP announced MP for 2008 Image on 2.6 VGA (300 ppi) 44

37 Camera Based 45

38 Radar Touch Excellent for large sized screens Gesture OK Lacks of multi touch by geometric blocking 46

39 Dual & Multi Touch 47

40 Mobile Infrared Touch Source: Walker, public and private 48

41 Comparison - All touch screens reduce clarity and enhance reflectivity of the display - All touch screens rise power consumption: LCD Backlight or emissive luminance must be enhanced Technology Multi- touch Resolution Form factor (bezel) Cost Resistive No 100+ dpi, any object Up to 5mm on all sides Low Surface Capacitive No 10 dpi, only finger; no pen input Minimal Medium Projected Capacitive Yes 10 dpi - only works with a human finger Minimal High 49

42 Overview Introduction Touch Screen Technologies Application Issues Summary 50

43 Touch Technology Comparison Source: M. Jones 51

44 Touch Technology Comparison for Applications Source: M. Jones 53

45 Touch Screens & Ambient Light 54

46 Touch Screens & System Total cost of ownership: Consider initial purchase price plus long-term costs including operation and maintenance Accepted input devices Is it important that the application work with a finger, a gloved finger, a metal stylus, a nonconductive stylus, a credit card, and/or a long fingernail? Durability: How harsh is the intended environment? Will the system be used in the public sector (vandal considerations)? Image quality of the underlying display: Are clarity, brightness and readability of the display important to the application? Sealability and chemical resistance: Is the screen/device likely to be subjected to spills and/or cleaning with harsh chemicals? Reliability: What is the impact of any downtime for repair? 55

47 Overview Introduction Touch Screen Technologies Application Issues Summary 57

48 Summary Touch screens have many advantages like HMI Mature technologies available Integration needs some expertise incl. ambient light Not every touch technology is suitable for dedicated applications Touch has many benefits but need some system considerations 58

49 Summary 59

50 Touch Screen Companies Name Internet Technology A D Metro C, R Bergquist R Chi Lin Technology/ NextWindow R, Opt DigiTech Systems C, R EGalax Cont Elo TouchSystems APR, C, IR, PC, R, SAW Fujitsu R Gunze R Hampshire Cont 60

51 Touch Screen Companies Name Internet Technology Horizon Technology SAW Immersion TF IRTouch Systems IR Northpoint Techn. C, R Smart Technologies Opt SMK Electronics IR, R, TF Touch International C, IR, PC, R Touch KO/ White Electronic Designs PC, R Wacom EMR Zytronic PC 61

52 What Touch Screen Technology Is It? (I) Brush the screen very lightly with Kleenex If it responds, it s either infrared or optical - Resistive needs pressure - Surface & projected capacitive need a finger - Surface acoustic wave needs a sound-absorbing contact - APR/DST (bending wave) needs a firmer touch Block the corners of the screen with something opaque - If it still responds to a touch away from the corners, it s infrared (IR transceivers are distributed all around the periphery) - If it stops responding, it s optical (imaging cameras are located in the corners) 62

53 What Touch Screen Technology Is It? (II) Brush the screen very lightly with Kleenex If it didn t respond, poke it with a toothpick - If it responds, it s resistive or APR/DST (bending wave) - Surface & projected capacitive need a finger - Surface acoustic wave needs a sound-absorbing contact - Check to see if the surface moves ever so slightly when you poke it with the toothpick (watch a reflection of a light source on the surface of the screen and try several locations) - If the surface moves, it s resistive (the surface is PET) - If the surface doesn t move, it s APR/DST (bending wave) the surface is glass 63

54 What Touch Screen Technology Is It? (III) Brush the screen very lightly with Kleenex If it didn t respond, touch it with a pencil eraser - If it responds, it s surface acoustic wave - Surface acoustic wave needs a sound-absorbing contact - If it doesn t respond, it s either surface or projected capacitive - Surface capacitive and projected-capacitive need a finger - Check for faintly visible straight or jagged lines in a repeating pattern in the darkest areas of the screen (the lines are most visible when the screen is powered off and you re looking at the surface using reflected light) - If you see lines, it s projected capacitive (you re seeing the transparent conductors on the sensor) - If you don t see any lines, it s surface capacitive 64