touch screen technology
TRANSCRIPT
TOUCH SCREEN TECHNOLOGY
Contents1. Walkthrough2. Introduction3. Applications4. History, Evolution & Development5. Types of Touchscreen Technology
i. Resistiveii. Capacitiveiii. SAWiv. Infrared / Optical
6. Future Technology
Call it an effort of human
mind or a miracle from human heart but this is all happening with technology.
Just move the hand or walk your fingers over a thing and it works.
Yes, it is the interactive gesture based technology I am talking about.
Walkthrough
Introduction
A touch screen is an electronic visual display that detect the location and presence of touch in the display area
This works by locating the coordinates of users touch independent of what is being displayed on the screen
In today’s world, Touch Screen Technology is omnipresent
Starting from mobiles to home appliances almost all the electronic devices comprise TST
It allows users to interact directly with what is being displayed, rather than indirectly using an intermediate device like mouse or keyboard
Widely used in modern smartphones, video games, kiosks, navigation systems, etc.
Applications
History, Evolution & Development Invented by E.A. Johnson (Royal Radar Est.) around 1965 for air traffic control
HP-150 home computer using infrared technology in 1983
1993 Apple’s Newton and IBM’s Simon
2002 Microsoft’s Windows XP Tablet
2007 Apple’s iPhone (Multi-touch)
There are four main types of touchscreen technology namely:
1. Resistive2. Capacitive3. Surface Acoustic Wave (SAW)4. Infrared LED or Optical
Looking from an engineer’s perspective, this revolutionary touchscreen technology is a 2 dimensional sensing device made of 2 sheets of material separated by spacers
Types of Touchscreen Technology
Resistive Touchscreen Technology
A resistive touch screen panel is composed of several layers
The most important of which are two thin, metallic, electrically conductive layers separated by a narrow gap
When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point.
This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing. It is used in Grocery Stores, Hotels, Restaurants and Retail Stores.
Advantages & Disadvantages
Advantages
1. Cost-effective solution
2. Activated by any stylus
3. Very accurate
4. Low power requirements
5. Liquids won't affect touch screen performance
Disadvantages
6. Polyester surface can be damaged
7. Lower endurance (35 million touches)
8” resistive touch screen will cost about $60
4 and 5 wire touch screens don’t need controllers For those that do, they cost less than $5
Any object can be used to activate the screen
Not able to register multiple touches
~75% of light is transferred through (12.5% per layer)
Some of the popular devices that use Resistive Touchscreen are Nintendo DS, Nokia N97, HTC Touch Pro2, HTC Tattoo, Sony Ericsson Satio, etc.
Summary
Capacitive Touchscreen Technology
A capacitive touch screen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO)
Small amount of voltage applied to four corners of touch screen, draws minute amount of current creating voltage drop
Coordinates of point of contact calculated by controller
The capacitive systems transmit almost 90% of light from the monitor
Advantages & Disadvantages
Advantages
1. Scratch resistant, durable surface
2. High endurance (225 million touches)
3. Very accurate
4. Good optical clarity
5. Liquids won't affect touch screen performance
Disadvantages
1. Does not work with gloved fingers or stylus
Summary 8” capacitive touch screen costs about $100
Controllers can be bought for less than $5
Only conductive objects can be used to activate
Able to register multiple touches
~88% of light is transferred through Some of the devices using capacitive touchscreen are
Motorola Xoom, Samsung Galaxy Tab, Samsung Galaxy SII, Apple’s iPad
Surface Acoustic Wave Touchscreen Technology
The Surface Acoustic Wave Touchscreen technology contains two transducers (transmitting and receiving) placed along the X-axis and Y-axis of the monitor’s glass plate along with some reflectors.
When the screen is touched, the waves are absorbed and a touch is
detected at that point. These reflectors reflect all electrical signals sent from one transducer to another.
This technology provides excellent throughput and image clarity.
The waves propagate across the glass and are reflected back to the sensors.
Advantages & Disadvantages
Advantages
1. Durable glass construction
2. High optical clarity
3. Activated by a finger, gloved hand, or soft tip stylus
Disadvantages
4. Moving liquids or condensation can cause false touches
5. Solid contaminants create non-touch areas until removed
6. Doesn't support drag or draw effectively
7. Expensive
Summary
Prices for individual screens are unavailable
Any object can be used to activate the screen
Able to register multiple touches
~100% of light is transferred through SAW touch screen technology is suggested for use in ATMs, Amusement Parks, Gaming Environments, Industrial Control Rooms etc
Infrared Touchscreen Technology
An infrared touch screen uses an array of X-Y infrared LED and photo detector pairs around the edges of the screen to detect a disruption in the pattern of LED beams.
Touching screen interrupts LEDs
Cameras detect reflected LED caused by touch
Controller able to calculate coordinates from camera data
Advantages & DisadvantagesAdvantages
1. Highest quality of underlying image
2. Very high transmittance
3. Excellent anti-glare, with use of chemically etched glass
4. Can be activated with almost any device
5. Higher accuracy than other technologies
6. Very high durability and reliability
Disadvantages
7. Surface obstructions can cause a false touch
8. It is very sensitive and can be activated by stray touches.
9. Low resolution
10. Parallax problems
Summary
Infra-red bezels have proven to be a very reliable technology for use in ATMs, Medical Instrumentation and Transportation Tracking applications
8” infrared touch screen costs about $160
Any object can be used to activate the screen
Able to register multiple touches
~100% of light is transferred through
Touch Screen Technology Comparison Chart
Future of Touchscreen Technology Touchscreen Technology has made a tremendous progress in the past few years and the future beholds a lot of surprising innovations
As complex the technology gets as simpler the life becomes and there we would be.
Closing Thoughts
Though the touch screen technology contains some
limitations it’s very user friendly, fast, accurate, easy for
the novices & fun to operate.
It has been widely accepted.
And now by just modifying a little it can replace the
mouse and key board completely in near future.
*References
*Wikipedia *www.engineersgarage.com/articles/*www.computerworld.com/.../how-it-works--
the-technology-of-touch-scr...
Thank you :D