Touch screen technology is the direct manipulation type gesture based technology. Direct manipulation is the ability to manipulate digital world inside a screen. A Touch screen is an electronic visual display capable of detecting and locating a touch over its display area. This is generally referred to as touching the display of the device with a finger or hand. This technology is most widely used in computers, user interactive machines, smart phones, tablets etc to replace most functions of the mouse and keyboard.
Touch screen technology has been around for a number of years but advanced touch screen technology has come on in leaps and bounds recently. Companies are including this technology into more of their products. The three most common touch screen technologies include resistive, capacitive and SAW (surface acoustic wave). Most of low end touch screen devices contain on a standard printed circuit plug-in board and are used on SPI protocol. The system has two parts, namely; hardware and software. The hardware architecture consists of a stand-alone embedded system using an 8-bit microcontroller, several type of interface and driver circuits. The system software driver is developed using an interactive C programming language.
Types of Touch Screen Technology:
The Touch screen is a 2-dimensional sensing
device made of 2 sheets of material separated by spacers. There are four main
touch screen technologies: Resistive, Capacitive, Surface Acoustical wave (SAW)
and infrared (IR).
Resistive:
Resistive touch screen is composed of a flexible
top layer made of polythene and a rigid bottom layer made of glass separated by
insulating dots, attached to a touch screen controller. Resistive touch screen
panels are more affordable but offering only 75% of light monitor and the layer
can be damaged by sharp objects. Resistive touch screen is further divided into
4-, 5-, 6-, 7-, 8- wired resistive touch screen. The construction design of all
these modules is similar but there is a major distinction in each of its method
to determine the coordinates of touch.
Capacitive:
A capacitive touch screen panel is coated with a
material that stores electrical charges. The capacitive systems can transmit up
to 90% of light from the monitor. It is divided into two categories. In
Surface-capacitive technology only one side of the insulator is coated with a
conducting layer.
Whenever a human finger touches the screen,
conduction of electric charges occurs over the uncoated layer which results in
the formation of dynamic capacitor. The controller then detects the position of
touch by measuring the change in capacitance at the four corners of the screen.
In projected capacitive technology, the
conductive layer (Indium Tin Oxide) is etched to form a grid of multiple
horizontal and vertical electrodes. It involves sensing along both the X and Y
axis using clearly etched ITO pattern. For increasing the accuracy of the
system, the projective screen contains a sensor at every interaction of the row
and column.
Infrared:
In infrared touch screen technology, an array of
X and Y axis is fitted with pairs of IR Leds and photo detectors. Photo detectors
will detect any image in the pattern of light emitted by the Leds whenever the
user touches the screen.
Surface Acoustic wave:
The surface acoustic wave technology contains two
transducers placed along 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
through put and quality.
Components and working of touch screen:
A basic touch screen is having a touch sensor, a
controller, and a software driver as three main components. The touch screen is
needed to be combined with a display and a PC to make a touch screen system.
Touch sensor:
The sensor generally has an electrical current or
signal going through it and touching the screen causes a change in the signal.
This change is used to determine the location of the touch of the screen.
Controller:
A controller will be connected between touch sensor and PC. It takes
information from sensor and translates it for understanding of PC. The
controller determines what type of connection is needed.
Software driver:
It allows computer and touch screen to work
together. It tells OS how to interact the touch event information that is sent
from the controller.The touch screen is one of the simplest PC
interfaces to use, for larger number of applications. A touch screen is useful
for easily accessing the information by simply touching the display screen. The
touch screen device system is useful in ranging from industrial process control
to home
automation.
At the transmission end using a touch screen
control unit, some directions will send to the robot for moving into a specific
direction like forward, backward, rotating left and rotating right. At the
receiving end four motors are interfaced with the microcontroller. Two of them
will be used for Arm and grip movement of the robot and other two are used for
body movement.
Some remote operations can be done with touch
screen technology using wireless communication for answering calls, locating
and communicating with staff, and operating vehicles and robots. For this
purpose RF communication or infrared communication may be used.
0 Comments