The Big Touch screen Debate
The Mobile phone revolution today has resulted in the market
being flooded by android and other touch screen smart phones. Starting from as
low as 1200 rupees to worth more than a fortune, touch screen phones vary in
size, shape and sensitivity and end up confusing the buyers. With most
companies only advertising those features that are best for them, or those
technological aspects that they think they are offering cheaper, there are
chances that the unwary customer might end up being fooled by the flashy adverts
and end up buying less than what they bargained for. Not everyone can
understand what exactly each technical term means. And not everyone can clearly
say one type over the other. But there could be certain pointers and
categorizations based on the requirement of each and every individual user.
The basic definition of touch screen is given as "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". Some
touch screens can also detect objects such as a stylus or ordinary or specially
coated gloves. The touch screen enables the user to interact directly with what
is displayed, rather than using a mouse, touchpad, or any other intermediate
device (other than a stylus, which is optional for most modern touch screens). So
here are a few basic pointers to distinguish between the major technical terms
of touch screens
Debate 1: Resistive Vs Capacitive
In electrical engineering, resistive touch screens are
touch-sensitive computer displays composed of two flexible sheets coated with a
resistive material and separated by an air gap or microdots. When contact is
made to the surface of the touch screen, the two sheets are pressed together.
On these two sheets there are horizontal and vertical lines that, when pushed
together, register the precise location of the touch. Because the touch screen
senses input from contact with nearly any object (finger, stylus/pen, palm)
resistive touch screens are a type of "passive" technology.
In electrical engineering, capacitive sensing is a
technology, based on capacitive coupling that takes human body capacitance as
input. Capacitive sensors detect anything that is conductive or has a dielectric
different from that of air. A standard stylus cannot be used for capacitive
sensing, but special capacitive styli, which are conductive, exist for the
purpose. For this reason, it is called as “active” technology, since it needs
active finger charge input.
But all this is technical jargon, what the techs call as ‘explanation’.
But in short
Resistive touch screen technology works well with almost any
stylus-like object, and can also be operated with gloved fingers and bare
fingers alike. In some circumstances, this is more desirable than a capacitive
touch screen, which needs a capacitive pointer, such as a bare finger (though
some capacitive sensors can detect gloves and some gloves can work with all capacitive
screens); resistive touch screens, due to requiring harder pressure, are also
more accurate than capacitive touch screens. Costs are relatively low when
compared with active touch screen technologies, but are also more prone to damage.
Resistive touch screen technology can be made to support multi-touch input. Where
conditions allow bare finger operation, the resistive screen's poorer
responsiveness to light touches has caused it to lose market share to
capacitive screens.
Resistive screens are cheaper, require more pressure, can be
operated with any object or gloved hands. On the other hand capacitive screens
are most comfortable when operated with a bare finger and can be smooth and
require minimal pressure. The cost issue is actually addressed nowadays with
mass production.
So the winner of this round is…. CAPACTIVE TOUCH SCREENS
Debate 2: IPL or AMOLED?
IPS (In-Plane Switching) was developed by Hitachi Ltd. in
1996 to improve on the poor viewing angle and the poor colour reproduction of
TN panels at that time. Its name comes from the main difference from TN panels,
that the crystal molecules move parallel to the panel plane instead of
perpendicular to it. This change reduces the amount of light scattering in the
matrix, which gives IPS its characteristic wide viewing angles and good colour
reproduction. Initial iterations of IPS technology were characterised by slow
response time and a low contrast ratio but later revisions have made marked
improvements to these shortcomings. Because of its wide viewing angle and
accurate colour reproduction (with almost no off-angle colour shift), IPS is
widely employed in high-end monitors aimed at professional graphic artists,
although with the recent fall in price it has been seen in the mainstream
market as well.
AMOLED (Active-Matrix Organic Light-Emitting Diode) is a
display technology for use in mobile devices and televisions. OLED describes a
specific type of thin-film display technology in which organic compounds form
the electroluminescent material, and active matrix refers to the technology
behind the addressing of pixels. An AMOLED display consists of an active matrix
of OLED pixels that generate light (luminescence) upon electrical activation
that have been deposited or integrated onto a thin film transistor (TFT) array,
which functions as a series of switches to control the current flowing to each
individual pixel. Typically, this continuous current flow is controlled by at
least two TFTs at each pixel (to trigger the luminescence), with one TFT to
start and stop the charging of a storage capacitor and the second to provide a
voltage source at the level needed to create a constant current to the pixel,
thereby eliminating the need for the very high currents required for passive
matrix OLED operation. TFT backplane technology is crucial in the fabrication
of AMOLED displays.
Away from the “official” explanation, the layman comparison
is as follows.
AMOLED displays provide higher refresh rates improving response
time often to under a millisecond, and they consume significantly less power.
This advantage makes these screens well suited for portable electronics, where
power consumption is critical to battery life. On the other hand, IPS panels
have slower response times and are therefore more prone to the ghosting effect.
They also require up to 15% more power consumption.
To their credit, IPS panels display consistent and accurate
colour from all viewing angles. They do not lighten or show tailing when
touched. This is important for touch screen devices, such as smart phones and
tablets. IPS Panels offer clear images and stable response time. Whereas, AMOLED
displays may be difficult to view in direct sunlight compared with LCDs because
of their reduced maximum brightness and increased gap between the layers of
TFT. The organic materials used in AMOLED displays are prone to degradation
over a period of time, resulting in colour shifts as one colour fades faster
than another, and image persistence or burn-in occurs.
In short, if you are a fan of colours and clarity, and do
not worry about certain lags or battery drains, go for IPS, but if you are a
stickler for every bit of battery juice, and need quick response from screens
and do not mind covering your phone with your hand in case of bright outdoor
lights, go for AMOLED. They are equally placed, for what is life, if not
compromise?
Debate 3: Is a higher PPI really that impressive?
With the Apple iPad offering a 326 ppi retina display, the
question has now arisen. What exactly is this ppi? Why is this Retina Display
so special? Pixels per inch (PPI) or pixel density is a measurement of the
resolution of devices in various contexts. The PPI of a computer display is
related to the size of the display in inches and the total number of pixels in
the horizontal and vertical directions. Often heard of terms like pixel density
is 1024 X 800, or 800 X 600? These are actually the number of pixels used to
display the image in the screen. This is where the ppi comes in. To be really
clear, the 800 X 600 resolution might be well nigh impossible to bring into a
3.5 inch smart phone. This is simply because the total size of the screen is
too less to hold that many pixels. These small smart phone screens would do
well with a 480 X 320 resolution.
On the other hand, the 800 X 600 seems a big daddy in smart
phones but would look too distorted, blurred and vague on modern day computer
screens that claim sizes of 17 and 19 inches. But giving higher ppi is not easy.
The technology is both expensive and power consuming. The famous tagline of the
Retina Display is, “you can’t really see the individual pixels”. They are so
densely packed together in the available screen size.
Therefore, the higher the ppi, the clearer and accurate and
lifelike the picture is. But it comes at a price. If you are ready to pay, the ppi
intensive devices are for you!
Debate 4: How big is big?
Many people are often easily impressed by bigger screens and
are often confused and end up buying tablets when all they need are phones.
What must be realised here is, unless you work with documents with lots of
pictures and texts and browse a lot, a bigger screen device is uncomfortable to
carry around. The smaller smart phones are convenient if all you do is call and
text. But an avid reader must notice that the screen size and pixilation matter
when clarity of text comes to question. To conclude, bigger does not always
translate to impressive. Bigger screens with lower resolution and ppi are not
worth the buck. Bigger, denser, and possibly clearer is the requirement.
