Touch Technology• Display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touch screens as a highly desirable user interface component and have begun to integrate touch screen functionality into the fundamental design of their products. Touch Screen Panel Resistive Capacitive Infrared Surface Acoustic Wave Mounted touch In cell touch
Resistive TouchA resistive touch screen panel is composed of several layers, the most important of which are two thin, electricallyconductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on thepanels outer surface the two metallic layers become connected at that point: the panel then behaves as a pair ofvoltage dividers with connected outputs. This causes a change in the electrical current, which is registered as atouch event and sent to the controller for processing. The cover sheet consists of a hard outer surface with acoated inner side. When the outer layer is touched it causes the conductive layers to touch creating a signal thatthe analog controller can interpret and determine what the user wants to be done. Resistive touch is used inrestaurants, factories and hospitals due to its high resistance to liquids and contaminants. A major benefit ofresistive touch technology is it is extremely cost-effective. One disadvantage of resistive technology is itsvulnerability of being damaged by sharp objects.
Resistive Panel Production Flow Source from Display Bank
Capacitive TouchA capacitive touch screen panel consists of an insulator such as glass, coated with a transparent conductor such asindium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the screen resultsin a distortion of the screens electrostatic field, measurable as a change in capacitance. Different technologies maybe used to determine the location of the touch. The location is then sent to the controller for processing. Unlike aresistive touch screen, one cannot use a capacitive touch screen through most types of electrically insulatingmaterial, such as gloves;
Pro. Cap. Touch Technology• Film and Glass Type• Glass Type – Apple iPhone: X and Y electrode on glass – Samsung Galaxy S : Multi coating on glass• DPW : Direct Patterned Window. Direct Coating on Glass Projected Film Type Capacitive Touch Glass Type Dual Coating Type Single Coating Type Direct Patterned Window
Capacitive Touch ControllerPro Cap Touch Control IC consists of Signal source, Multiplexer, A/Dconverter.
Projected Capacitive TouchProjected Capacitive Touch (PCT) technology is a capacitive technology which permits more accurate and flexible operation, byetching the conductive layer. An X-Y grid is formed either by etching a single layer to form a grid pattern of electrodes, or byetching two separate, perpendicular layers of conductive material with parallel lines or tracks to form the grid (comparable to thepixel grid found in many LCD displays).The greater resolution of PCT allows operation without direct contact, such that the conducting layers can be coated with furtherprotective insulating layers, and operate even under screen protectors, or behind weather and vandal-proof glass. Due to the toplayer of a PCT being glass, PCT is a more robust solution versus resistive touch technology. Depending on the implementation,an active or passive stylus can be used instead of or in addition to a finger.
Pro. Cap. Touch Comparison Single layer Direct Dual Coating ITO Film type Multi Coating Patterned Type Type WindowPrice Good Bad Bad Very BadVessel Width Bad Very good Very good Very goodThickness Bad Very bad Very good Very goodOperation Good Good Good GoodPerformanceLarge Display Very bad Good Good Very bad
Infrared TouchAn infrared touchscreen uses an array of X-Y infrared LED and photodetector pairs around theedges of the screen to detect a disruption in the pattern of LED beams. These LED beamscross each other in vertical and horizontal patterns. This helps the sensors pick up the exactlocation of the touch.A major benefit of such a system is that it can detect essentially any input including a finger,gloved finger, stylus or pen.It is generally used in outdoor applications and point of sale systems which cant rely on aconductor (such as a bare finger) to activate the touchscreen. Unlike capacitivetouchscreens, infrared touch screens do not require any patterning on the glass whichincreases durability and optical clarity of the overall system
Acoustic Touch Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touchscreen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreenThe key to the invention is that a touch at each position on the glass generates a unique sound.Four tiny transducers attached to the edges of the touch screen glass pick up the sound of thetouch. The sound is then digitized by the controller and compared to a list of prerecorded soundsfor every position on the glass. The cursor position is instantly updated to the touch location.
Gestural Interface• Wired gloves. These can provide input to the computer about the position and rotation of the hands using magnetic or inertial tracking devices. Furthermore, some gloves can detect finger bending with a high degree of accuracy (5-10 degrees), or even provide haptic feedback to the user, which is a simulation of the sense of touch. The first commercially available hand-tracking glove-type device was the DataGlove, a glove-type device which could detect hand position, movement and finger bending. This uses fiber optic cables running down the back of the hand. Light pulses are created and when the fingers are bent, light leaks through small cracks and the loss is registered, giving an approximation of the hand pose.• Depth-aware cameras. Using specialized cameras such as time-of-flight cameras, one can generate a depth map of what is being seen through the camera at a short range, and use this data to approximate a 3d representation of what is being seen. These can be effective for detection of hand gestures due to their short range capabilities. • Stereo cameras. Using two cameras whose relations to one another are known, a 3d representation can be approximated by the output of the cameras. To get the cameras relations, one can use a positioning reference such as a lexian-stripe or infrared emitters. In combination with direct motion measurement (6D-Vision) gestures can directly be detected.• Controller-based gestures. These controllers act as an extension of the body so that when gestures are performed, some of their motion can be conveniently captured by software. Mouse gestures are one such example, where the motion of the mouse is correlated to a symbol being drawn by a persons hand, as is the Wii Remote, which can study changes in acceleration over time to represent gestures.  Devices such as the LG Electronics Magic Wand, the Loop and the Scoop use Hillcrest Labs Freespace technology, which uses MEMS accelerometers, gyroscopes and other sensors to translate gestures into cursor movement. The software also compensates for human tremor and inadvertent movement.   • Single camera. A normal camera can be used for gesture recognition where the resources/environment would not be convenient for other forms of image-based recognition. Although not necessarily as effective as stereo or depth aware cameras, using a single camera allows a greater possibility of accessibility to a wider audience. 
Common Multi-Touch Gesture Tap Double Tap Long Press Scroll Pan Flick Two Finger Tap Two Finger Scroll Pinch Two hand PinchUnpinch Two hand Unpinch Rotate Two hand rotate
Gorilla Arm• "Gorilla arm" was a side-effect of vertically-oriented touch-screen or light-pen use. In periods of prolonged use, users arms began to feel fatigue and/or discomfort. This effect contributed to the decline of touch-screen input despite initial popularity in the 1980s.• Gorilla arm is not a problem for short-term use, since they only involve brief interactions which do not last long enough to cause gorilla arm
Technology Comparison(1)Technology Strong Weak Easy mounting Low light transmittanceResistive Fast response Very fragile High resolution High Durability Only ElectrodeCapacitive Fast Response Difficult in mounting Multi touch support Difficult in mounting High Durable Large vessel sizeInfrared High light transmittance Low response time Multi touch support Error in outside use Limited in design High durability Weak in liquidAcoustic High light transmittance Weak in contamination of sensor
Production Flow of MelfasIC ICTSM TSM Source from MELFAS IR, Nov. 2011
Major Touch Sensor Controller Supplier MELFAS ATMEL Cypress Synaptics Korea US US US Touch IC Touch IC Touch Screen Module Touch IC Touch IC Touch Screen Panel Touch Key Module Touch Key Module Turnkey Solution IC IC IC & ModuleDPW(Direct Patterned Window) 2-layer solution 1-layer solution 2-layer solution 2-layer solution Touch pad 2-layer solution
Touch Market Forecast(1)Touch Screen market projected US$10B in 2013Capacitive touch screen share 80% of Market in 2013Tablet PC shipment 50M in 2011 to 130M in 2013 Worldwide Touch Screen Market Worldwide Touch Mobile Phone Market (Shipment (Sales revenue in $100M) Unit : Million) Source from Melfas IR, Nov. 2011
Touch Phone Market Forecast(3)Global Mobile Phone-Touch Phone Market Forecast (unit: Million) Mobile Phone Touch Phone Touch adaptation rate Source from : Displaybank