Upload
utkarsh-mishra
View
225
Download
0
Embed Size (px)
Citation preview
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 1/32
WAZID AHSAN
REG NO-11000372
ROLL NO-203
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 2/32
A touch screen is an electronic visual display that
the user can control through simple or multi-touch
gestures by touching the screen with one or more
fingers.
The touchscreen enables the user to interactdirectly with what is displayed, rather than using
a mouse, touchpad, or any other intermediate
device .
Some touch screens can also detect objects suchas a stylus or ordinary or specially coated gloves.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 3/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 4/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 5/32
The first ever touch screen was developed by E.A Johnsonat the Royal Radar Establishment, Malvern, UK in the late1960s. Evidently, the first touch screen was a capacitivetype; the one widely used in smart phones nowadays.
In 1971, a milestone to touch screen technology wasdeveloped by Doctor Sam Hurst, an instructor at theUniversity of Kentucky Research Foundation. It was atouch sensor named ‘Elograph’. Later in 1974, Hurst inassociation with his company Elographics came up withthe first real touch screen featuring a transparent surface.In 1977, Elographics developed and patented a resistivetouch screen technology, one of the most popular touch
screen technologies in use today.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 6/32
Let us now give an engineer’s eye to this
revolutionary technology. A touchscreen is a 2
dimensional sensing device made of 2 sheets of
material separated by spacers. There are four
main touchscreen technologies:
1) Resistive 2) Capacitive 3) Surface Acoustic Wave 4) Infrared
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 7/32
The resistive touchscreen consists of a flexible toplayer made of Polyethylene (PET) and a rigid bottomlayer made of glass. Both the layers are coated with aconducting compound called Indium Tin Oxide (ITO)and then spaced with spacers. While the monitor is
operational, an electric current flows between the twolayers. When a touch is made, the flexible screenpresses down and touches the bottom layer. A changein electrical current is hence detected and thecoordinates of the point of touch is calculated by thecontroller and parsed into readable signals forthe operating system to react accordingly.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 8/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 9/32
Some of the popular devices that use Resistive Touchscreen areNintendo DS, Nokia N97, HTC Touch Pro2, HTC Tattoo, SonyEricsson Satio, etc.
These systems transmit only 75% of light from the monitor. The
resistive touchscreen is further divided into 4-, 5-, 6-, 7- and 8-wired resistive touchscreen. While the constructive design of allthese modules is similar there is a major distinction in each of itsmethod to determine the coordinates of touch.
The Four wire Resistive Touchscreen uses both the layers tocalculate the axes information of the touch. Touch measurement in
the 4-wire is a 2 step process. The x-coordinate of the touch pointis calculated by creating a voltage gradient on the flexible layer, andthe y-coordinate is determined by creating a voltage gradient alongthe bottom layer.
Pros and Cons: Consequently, the 4-wire resistive touchscreen isless durable, feebly accurate and can drift with environmentalchanges. However these negatives are divulged only with large-sized touchscreen. These are relatively cheap, easily available andconsume low power.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 10/32
the Eight wire Resistive Touchscreen is simply avariation of the 4-wire one with the addition of 4sense wires, two for each layer. The sensing pointsaid in reducing the environmental drift to increase
the stability of the system. The 8-wire systems areemployed in sizes of 10.4” or larger where the driftcan be significant.
The Five wire Resistive Touchscreen do not uses the
coversheet (flexible layer) in determining the touchcoordinate. All the position sensing is employed onthe stable glass layer. In this design, one wire goes tothe coversheet and four wires are deployed to thefour corners of the bottom sheet. The coversheet onlyacts as a voltage measuring probe. The functioning of
the touchscreen remains unscathed even withchanges in the uniformity of the conductive coatingover the coversheet.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 11/32
Pros and Cons: Highly durable, accurate and reliable.This technology involves complex electronics and isexpensive. However, it can be used in sizes upto 22”.
The Six and Seven wire resistive touchscreen is also avariant to the 5 and 4 wire technology respectively. Inthe 6-wire resistive touchscreen an extra ground layeris added behind the glass plate which is said to
improve system’s performance. While, the seven –wirevariant has two sense lines on the bottom plate.However, these technologies are as prevalent as theircounterparts.
The Resistive Touchscreen works well with almost anystylus-like object.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 12/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 13/32
The Capacitive Touchscreen Technology is the mostpopular and durable touchscreen technology used all
over the world at most. It consists of a glass panel
coated with a capacitive (conductive) material Indium
Tin Oxide (ITO). The capacitive systems transmitalmost 90% of light from the monitor. Some of the
devices using capacitive touchscreen are Motorola
Xoom, Samsung Galaxy Tab, Samsung Galaxy SII,
Apple’s iPad.There are two kinds of capacitive touch-surface and projected.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 14/32
Surface-Capacitive screens, in this technique only oneside of the insulator is coated with a conducting layer.While the monitor is operational, a uniformelectrostatic field is formed over the conductive layer.Whenever, a human finger touches the screen,conduction of electric charges occurs over theuncoated layer which results in the formation of adynamic capacitor. The computer or the controller thendetects the position of touch by measuring the change
in capacitance at the four corners of the screen. Pros and Cons: The surface capacitive touchscreen
is moderately durable and needs calibration duringmanufacture. Since a conductive material is requiredto operate this screen, passive stylus cannot be usedfor surface capacitive touchscreen.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 15/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 16/32
In the Projected-Capacitive Touchscreen
Technology, the conductive ITO layer is etched to
form a grid of multiple horizontal and vertical
electrodes. It involves sensing along both the Xand Y axis using clearly etched ITO pattern.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 17/32
The projective screen contains a sensor at every
intersection of the row and column, thereby
increasing the accuracy of the system.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 18/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 19/32
The Surface Acoustic Wave Touchscreen technologycontains two transducers (transmitting and receiving)placed along the X-axis and Y-axis of the monitor’s glassplate along with some reflectors. The waves propagateacross the glass and are reflected back to thesensors. When the screen is touched, the waves areabsorbed and a touch is detected at that point. Thesereflectors reflect all electrical signals sent from onetransducer to another. This technology provides excellentthroughput and image clarity.
Pros and Cons: 100% clarity is obtained as no metallic
layers are present on the screen, it can be operated usingpassive devices like stylus, glove or finger nail. Screen canget contaminated with much exposure to dirt, oil which mayhaunt its smooth functioning.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 20/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 21/32
In the Infrared Touchscreen Technology, an arrayof X- and Y- axes are fitted with pairs of IR
Leds and photo detectors. The photo detectors
detect any change in the pattern of light emitted by
the Leds whenever the user touches the
monitor/screen.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 22/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 23/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 24/32
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 25/32
PUBLIC INFORMATION DISPLAYS
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 26/32
Retail and restaurant systems.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 27/32
Customer self service
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 28/32
Computer based training.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 29/32
Used in industries.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 30/32
Used in hospitals.
8/13/2019 Wazid Ahsan Touch Screen Technology
http://slidepdf.com/reader/full/wazid-ahsan-touch-screen-technology 31/32