When you travel by public transport, when you walk along busy streets, when you are at shopping malls, or when you are at work these days, it is not rare to see people with smartphones; in fact it is not an exaggeration if we say “many people carry smartphones these days.ÓSome youngsters try to be smarter by using a smartphone.Many people refer smartphones to the mobile phones that have touchscreens. All the phones that have touchscreens are smartphones but all the smartphones must not necessarily have touchscreens.
Actually, what are smartphones?
Smartphones are mobile phones that are using a mobile operating system. Like the PC or laptop computer you use, these smartphones also use an operating system to do its work. In the contemporary world, the most famous mobile operating system is Android (by Google). There are many others too: iOS (by Apple), Symbian (by Nokia), Blackberry (by RIM), Windows Phone (by Microsoft) and Bada (by Samsung) are some of the popular ones.
Many modern smartphones have high-resolution touchscreens and web browsers that display standard web pages as well as mobile-optimized sites (sites that are specially designed for mobile phones where the URL starts with the prefix m.). Their high-speed data access is provided by Wi-Fi and mobile broadband. (Source: Wikipedia) Normal mobile phones that are being used by us are called feature phones. There is no clear information to distinct the two types (smart and feature). But the visible and clear significance is that smartphones contain advanced APIs (Application Programming Interfaces) to help them run third party applications (you call them as mobile apps). If I elaborate more on APIs, they can be considered as mediators who act as interfaces between different software components.- Referred: Wikipedia
Brief History of Smartphones
Smartphone concept is a brainchild of Ericsson where they described their product GS 88 “Penelope” as a smartphone. But some of you may have known Apple Inc. is the pioneer to introduce the smartphones. It is not incorrect, I would say but it is not correct too.
Means, Apple Inc. introduced one of the first phones to have multi- interface touch (recognises the presence of two or more points of contact with the surface simultaneously) in iPhone. And it became very popular among the public and people get the idea that Apple Inc. is the pioneer to introduce smartphones.
Since most of the modern smartphones have touchscreens I think it is good to have some background knowledge in touchscreen technologies:
How touchscreens work?
(Reference/Source: http://computer.howstuffworks.com/question716.htm)
There are 3 main categories of touchscreens. These three categories imply the way the system identify a person’s touch.
1. Resistive
2. Capacitive
3. Surface acoustic wave
Resistive touchscreen system:
The resistive touchscreen system consists of a normal glass panel covered with a conductive and a resistive metallic layer.
The two layers are kept apart by spacers. A scratch-resistant layer is placed on top of the whole setup.
An electrical current runs through the two layers while the screen is switched ON (i.e. when the mobile phone is operational). When a user touches the screen, the two layers make contact in that exact spot.
The change in the electrical field is noted and the coordinates of the point of contact are calculated by the computer (here we refer the computer as hardware and malware implementation of the mobile phone).
Once the coordinates are identified by the computer, a special driver translates the touch into something that the mobile operating system (Android, Symbian, Windows Mobile, etc.) can understand.
Capacitive touchscreen system:
In the capacitive touchscreen system, a layer that stores electrical charge is placed on the glass panel of the screen. When a user touches the screen with a finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the screen.
The mobile phone’s inbuilt computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch-screen driver software. In other words, the touchscreen driver software is prepared to catch that information and send it to the mobile operating system.
One advantage that the capacitive system has over the resistive system is that it transmits almost 90% of the light from the monitor, whereas the resistive system only transmits about 75%. This enables the capacitive system to provide a much clearer picture than the resistive system.
Surface Acoustic Wave touchscreen system:
In these systems, two transducers (one for receiving and one for sending) are placed along the x and y axes of the screen’s glass plate.
Now you might wonder what transducers are? Transducers are devices that convert a signal in one form (of energy) to another form.
This energy can be electrical, mechanical, chemical, acoustic and so on. In practice, the transducers are sensors and actuators. Sensors detect an energy parameter in one form and report it to another form. (E.g. Heat Sensors, Pressure Sensors, Light Sensors, etc.) Actuators, they accept energy and produce movement. (E.g. Electrical Motors, Loudspeakers and so on)
You might think of the term, acoustic wave. Acoustic waves are all the waves in liquids solids and glasses including vibration, sounds and etc. So coming back to the third type of touchscreen system, there are reflectors on the glass; they reflect an electrical signal sent from one transducer to the other.
The receiving transducer tells if the wave has been disturbed by a touch event at any instant, and can locate it accordingly. So, now you might understand that there are continuous waves (electrical signals) from the sending transducers to another.
That wave setup has no metallic layers on the screen, allowing for 100% light throughput and perfect image clarity. This makes the surface acoustic wave system best for displaying detailed graphics (both other systems have significant degradation in clarity).
Now you have an idea of the touchscreens, now let us get some background knowledge for the most widely used smartphone operating system - Android
Operating system - Android
By the time you read this article, you might have used your Android smartphone many times utilising its applications and facilities. But if you are not a computer or IT fan, you might not have spent time to explore Android. My intention is to get a brief overview of Android.
Android is a Linux based operating system (it uses the Linux kernel) which was initially built by Android Inc. which was backed by Google financially and then owned by Google. Android came to market in 2007. Android is open source and Google has released its native code under the Apache License so that anybody can edit it and distribute without any commercial benefit. Apache License is distributed by Apache foundation. If you want to read it more please surf the internet.
Later versions of Android has a Linux kernel version 3.x with middleware, libraries and APIs written in C language and have application software running on an application framework which includes Java-compatible libraries based on Apache Harmony (Apache Harmony is an open source Java implementation that acts as an application framework).
Android uses the Dalvik virtual machine with just-in-time compilation (JIT) to run Dalvik ‘dex-code’ (Dalvik Executable), which is usually translated from Java bytecode.
The main hardware platform for Android is the ARM architecture. (Source: Wikipedia) If you look at the Applications diagram carefully, you will get a clear picture of the Android’s System Architecture.
Daily News by Tharindu Weerasinghe
(The writer is a software engineer at a leading software company in Sri Lanka.)
