Touch screen Touch screen technologytechnology

Researcher: Eng. Tamer Sherif Mohamed Researcher: Eng. Tamer Sherif Mohamed ElMasry.ElMasry.Supervisor: Prof.D. Mohamed BesheerSupervisor: Prof.D. Mohamed Besheer

What are Touch Screens?What are Touch Screens?

• It is the most user friendly input It is the most user friendly input device used to interface with a PC.device used to interface with a PC.

• The user touches the screenThe user touches the screen to select options presented to select options presented on it, where associated hardware on it, where associated hardware

and software locate that touch. and software locate that touch.

History and DevelopmentHistory and Development• In 1971 Dr. Sam Hurst, founder of Elographics In 1971 Dr. Sam Hurst, founder of Elographics

developed the first touch opaque sensor developed the first touch opaque sensor “Elograph” at the University of Kentucky. “Elograph” at the University of Kentucky.

• In 1974 He developed the first real touch screen. In 1974 He developed the first real touch screen. • In 1977, Elographics developed the five-wire In 1977, Elographics developed the five-wire

resistive technology then with the backing of resistive technology then with the backing of Siemens Corporation, developed a curved glass Siemens Corporation, developed a curved glass sensor called the sensor called the touch screentouch screen. .

• The new transparent technology, AccuTouch, The new transparent technology, AccuTouch, was later developed by the founders of was later developed by the founders of Elographics, Dr. Hurst and Bill Colwell.Elographics, Dr. Hurst and Bill Colwell.

Why use Touch Screens?Why use Touch Screens? • Enable first-time users to interface with Enable first-time users to interface with

computers instantly, without any training. computers instantly, without any training. • Eliminate operator errors because users make Eliminate operator errors because users make

selections from clearly defined menus. selections from clearly defined menus. • Eliminate keyboards and mice, which many Eliminate keyboards and mice, which many

novice users find difficult to use. novice users find difficult to use. • Rugged enough to stand up to harsh conditions Rugged enough to stand up to harsh conditions

where keyboards and mice can be damaged. where keyboards and mice can be damaged. • Provide fast access to all types of digital content. Provide fast access to all types of digital content. • Ensure that no space is wasted since the input Ensure that no space is wasted since the input

device is completely integrated into the monitor.device is completely integrated into the monitor.

Elements of a touchscreen Elements of a touchscreen systemsystem• The touchscreen itself. The touchscreen itself. • A computer whose display is fitted with the A computer whose display is fitted with the

touchscreen interefacing with. touchscreen interefacing with. • A controller drives the touchscreen and converts A controller drives the touchscreen and converts

each touch into X/Y coordinates. each touch into X/Y coordinates. • A software driver, which communicates between A software driver, which communicates between

the controller card and the computer's operating the controller card and the computer's operating system. system.

• Application-development software, which Application-development software, which enables developers of touch programs to build enables developers of touch programs to build their own applications and/or customize existing their own applications and/or customize existing touch applications.touch applications.

How do Touchscreens How do Touchscreens Work?Work?

TOUCH TECHNOLOGIESTOUCH TECHNOLOGIES

Here are some technologies that are Here are some technologies that are used in making touch screens:used in making touch screens:

– ResistiveResistive– CapacitiveCapacitive– Surface Acoustic Wave (SAW)Surface Acoustic Wave (SAW)– Scanning InfraredScanning Infrared– Near Field ImagingNear Field Imaging

Resistive touch screenResistive touch screen

• Made of a glass panel with a coating of Made of a glass panel with a coating of uniform resistivity on which a voltage is uniform resistivity on which a voltage is applied. A polyester cover sheet is tightly applied. A polyester cover sheet is tightly suspended over the top of the glass, suspended over the top of the glass, separated from it by small, transparent separated from it by small, transparent insulating dots. insulating dots.

• The cover sheet has a hard, durable coating The cover sheet has a hard, durable coating on the outer side and a conductive coating on on the outer side and a conductive coating on the inner side. the inner side.

• With a light touch, the conductive coating makes With a light touch, the conductive coating makes electrical contact with the coating on the glass.electrical contact with the coating on the glass.

•   The voltages at the point ofcontact are the The voltages at the point ofcontact are the analog representation of the position touched. analog representation of the position touched. The controller digitizes these voltages and The controller digitizes these voltages and transmits them to thetransmits them to the computer for processing.computer for processing.

Advantages of ResistiveAdvantages of Resistive –High Resolution and Accuracy High Resolution and Accuracy –Fast Response Fast Response –Pressure-activated by finger or gloved hand with a Pressure-activated by finger or gloved hand with a

very light touch very light touch –Durable hard-coat front surface can be nonglare treated Durable hard-coat front surface can be nonglare treated

for     reflection control or polished for maximum clarity for     reflection control or polished for maximum clarity –Touchscreens and controllers are safety agency-Touchscreens and controllers are safety agency-

approved components,so certification of your system is approved components,so certification of your system is easiereasier

Disadvantages of ResistiveDisadvantages of Resistive –80 % Clarity 80 % Clarity –Resistive layers can be damaged by a sharp objectResistive layers can be damaged by a sharp object

Capacitive Touch screenCapacitive Touch screen•There are 2 types of capacitive touch screens:There are 2 types of capacitive touch screens:•Surface capacitiveSurface capacitive

-consists of a uniform conductive coating on a -consists of a uniform conductive coating on a glass glass panel on which a low voltage is evenly applied panel on which a low voltage is evenly applied fromthe corners. fromthe corners.

-The touch location is measured from the ratio of -The touch location is measured from the ratio of the the current flow from the cornerscurrent flow from the corners

•Projected CapacitiveProjected Capacitive -Made of a front and back protective glass -Made of a front and back protective glass

providing providing optical and strength enhancement optical and strength enhancement options. options.

-Its middle layer consists of a laminated -Its middle layer consists of a laminated sensor grid sensor grid of micro-fine wires and optical of micro-fine wires and optical enhancement options.enhancement options.

Advantages of CapacitiveAdvantages of Capacitive –High Touch Resolution High Touch Resolution –High Clarity High Clarity –Completely SealableCompletely Sealable

Disadvantages of CapacitiveDisadvantages of Capacitive   –Must be touched by finger- will not work with any Must be touched by finger- will not work with any

non- conductive input non- conductive input –Can be affected by electricity Can be affected by electricity –May need re-calibration often May need re-calibration often

Surface Acoustic Wave Touch Surface Acoustic Wave Touch screenscreen

• Made of a glass overlay with transmitting Made of a glass overlay with transmitting and receiving piezoelectric transducers for and receiving piezoelectric transducers for both the X and Y axes.both the X and Y axes.

• When a touch occurs, the wave is When a touch occurs, the wave is absorbed shortening the echo time it takes absorbed shortening the echo time it takes to reach the receivers.to reach the receivers.

Advantages of Surface Acoustic WaveAdvantages of Surface Acoustic Wave –Excellent Image Clarity -Very High Excellent Image Clarity -Very High

LightTransmission LightTransmission –Excellent Durability -Stable "No-Drift" Excellent Durability -Stable "No-Drift"

Operation Operation –High Resolution - Very Light Touch High Resolution - Very Light Touch –Fast Touch Response -X,Y and Z-axis Response Fast Touch Response -X,Y and Z-axis Response –Finger or Gloved-Hand Operation Finger or Gloved-Hand Operation

Disadvantages of Surface Acoustic WaveDisadvantages of Surface Acoustic Wave –Must be touched by finger, gloved hand, or soft-tip Must be touched by finger, gloved hand, or soft-tip

stylus.  Something hard like a pen won't work stylus.  Something hard like a pen won't work –Not completely sealable, can be affected by large  Not completely sealable, can be affected by large 

amounts of grease, water,  or dirt on the amounts of grease, water,  or dirt on the touchscreen touchscreen

Scanning Infrared touch Scanning Infrared touch screenscreen

• Made of a grid of LEDs and detectors framed Made of a grid of LEDs and detectors framed to the front of the display that projects to the front of the display that projects horizontal and vertical beams of infrared light.horizontal and vertical beams of infrared light.

• The press location is determined since it The press location is determined since it obstructs the IR beamobstructs the IR beam

AdvantagesAdvantages–Mostly used in manufacturing and medical applications Mostly used in manufacturing and medical applications

since it can be completely sealed. since it can be completely sealed. –operated using a stylus or a gloved finger.operated using a stylus or a gloved finger.–mechanically stronger mechanically stronger –ClearerClearer–more wear resistantmore wear resistant

DisadvantagesDisadvantages–it is very sensitive and can be activated by stray touches.it is very sensitive and can be activated by stray touches.–Low resolution Low resolution –Parallax problemsParallax problems

Near Field Imaging touch Near Field Imaging touch screenscreen• Made of two laminated glass sheets having a Made of two laminated glass sheets having a

transparent metal oxide coating in between.transparent metal oxide coating in between.• An AC signal is applied to the patterned An AC signal is applied to the patterned

conductive coating creating an electrostatic conductive coating creating an electrostatic field on the surface of the screen. field on the surface of the screen.

• It is used only in the toughest environments It is used only in the toughest environments and applicationsand applications due to its high cost. due to its high cost.

Applications of Touch ScreensApplications of Touch Screens   •Informational kiosks Informational kiosks •Trade show displays Trade show displays •Museum / tourism displays Museum / tourism displays •Point-of-sale terminals Point-of-sale terminals •Restaurant systems Restaurant systems •Employee time clocks Employee time clocks •Industrial process controls Industrial process controls •World Wide Web access kiosks World Wide Web access kiosks •Home automation systems Home automation systems •Casino and other gaming systems Casino and other gaming systems •Computer access for the physically disabled Computer access for the physically disabled

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