I. The Necessity of Saving Energy Technologies in Wireless Devices
The variety of wireless devices is truly great today due to needs and possibilities of modern society and its technology. Let’s take a look on the evolution of mobile phones, for example. Today, the mobile phone in its usual understanding is not so popular and is rather rarity than mobile phone walked trough the evolution way, from a simple (comparing to nowadays situation) device with a few functions to the modern smart phones that can suggest you an impressive number of possibilities. Smartphone is a logical sequel of a concept of mobile phone – the new functions had been added and today this is rather a small computer in your pocket than an instrument for communication. Smart phones usually have their operation system to provide all the functions, and often support GPRS internet and wireless networks. Whereas technologies are moving away from using wires in all spheres, it is very comfortable to have a device, which supports wireless networks.
Here comes another problem. Using wireless networks often requires a high stabile productivity of the device, and this, in turn, requires a very high capacity of the battery of such device. For example, HTC Corporation had admitted that the life of the batteries in their devices is poor.  The problem is that the battery will always be limited and its sizes, and, accordingly, in its capacity. And there are two ways to solve the problem: to change the technology of the batteries or the amount of power-usage by the devices. This essay will observe the second issue and will show you how the device can make a battery life longer. You will see on the concrete example how old technologies can help innovative smart phone to use less energy without losing “points” in design or productivity.
II. The Concept of Second Life Phone
The concept of Second Life Phone was created and developed by two designers Cho Sinhyung and Jeon Jungjae.  This concept had never been brought to life, but it worth your attention, because of much unexpected mix of innovative technologies and very old ones. The Second Life Phone is designed to work longer without any increasing size of the battery. The idea is to combine the very best achievements of the evolution of mobile phone and its technologies. Therefore, the Second Life Phone is a smart phone with all necessary functions and software. It is a usual smart phone that can also connect to the wireless networks. And the main aim can be achieved because of extraordinary design of the Second Life Phone.
The Second Life phone is a transparent rectangular smart phone, which is constructed from the two displays. The first one is AMOLED display. It is colorful and bright and all the icons and text can be well seen on it. The second display is E-Ink display, this technology is well-known, since we all have and electronic readers in our life. The displays are combined, one on another. Because of their thinness they both are transparent. The E-Ink display is turning on during calls, standby mode, and when the battery is low. During the work with apps, Internet or e-mail, the AMOLED display is on. When the battery is very low, the E-Ink display becomes lighter to save more energy.  This process of switching from one display to another due to needs of user and the current mode of phone can help to make battery life longer, while using all the functions and possibilities of smart phone. This is the touch phone, and it totally versa to the new series of Apple products, which are equipped with the Retina displays, which require a lot of battery power. Also there is a button on the front side of the smart phone, which is common for the devices like that.
III. Technologies Used in Second Life Phone
A. The AMOLED Display
AMOLED, or the Active Matrix Organic Light Emitting Diode is a technology for displays.  This technology is widely used in TV-sets, mobile phones and digital photo cameras. This display consists of a matrix of organic light-emitting diodes that are generating luminescent light.  This technology was developed later into touch panels, which made using AMOLED displays in touch phones possible. The most known AMOLED touch phones were produced by SAMSUNG and their AMOLED technology is called Super AMOLED and is used to provide very thick and large displays.  
The great advantage of AMOLED displays is that they use less energy comparing to other types of displays. AMOLED displays can provide very bright, crisp images using less power than the LCD displays, for example . In the process of creating color AMOLED displays, manufactures use organic films and apply to them different chemical compositions to get red, green and blue lights. The intensity or brightness of the light is proportional to the applied electrical current. AMOLED displays consume less power due to TFT (Thin-Film Transistor) array requiring a small amount of charge. AMOLED displays also have a very fast response time – near 50 sec and this makes them very comfortable to use in video player devices. Therefore, it is very comfortable to use an AMOLED display for big screens, due to their high power efficiency and video capability. 
The power-saving advantage of OLED technology is pretty impressive. They consume less power than LCD displays because of self-illuminating nature of OLED displays and absence of necessity of backlighting. OLED technology power consumption is depended on the displayed image. Comparing to the LCD displays, which has the same power consumption regardless the image, this is a huge advantage. Due to using the same image pattern and at the same brightness level, AMOLED displays have been shown to consume about 22 to 60 percent less power than LCD displays. The additional advantage in saving power technology is that the AMOLED displays can use darker images as a black background and save more charge of the battery in this way.  
Talking about advantages of AMOLED displays, we should mention some other details, which make using this type of display technology appropriate to use. There’s little problem with AMOLED displays – they can be difficult to view under the direct and bright sunlight, but also there’s a lot of innovations to solve this problem. For example, Samsung, who, as it was already told, provided their technology of AMOLED displays, reduced the size of gaps between the layers of the screen, and, therefore, solved this problem. 
Due to work that was developed by Samsung and HTC corporations under the technology of AMOLED displays, we can surely say that the whole technology was improved impressively, and today we have a great alternative to the LCD displays, and, furthermore, a very good variant to use in touch smart phones.  [10 ]
To make a sort of conclusion, we should say that the technology of AMOLED displays can not show the incredibly high resolution. For example, Retina displays do, but the quality of images displayed on AMOLED screens is still pretty high. AMOLED displays are very comfortable to touch-screen technologies. That is why it is widely used for such devices. For example, Samsung used their Super AMOLED technology in the number of devices: Galaxy S II, Nexus and so on. The main advantage of the AMOLED displays is their power-saving nature, which is a very good solution for the problem of life of the battery in wireless devices.
B. The E-Ink Display
E-Ink display is a specific type of electronic paper. It is available in grayscale and color. [8 ] Today E-Ink displays are widely used for portative devices as readers. It is useful for wireless devices. The E-Ink display was applied to the mobile phone for the first time by Motorola Corporation. The decision was based on the willing to take the advantage of the super low power consumption of the E-Ink display. Comparing to the LCD displays, E-Ink uses a very few amount of energy. A 12” LCD-equipped device uses, in 20 hours, the amount of energy that equals 36 AA batteries, and the E-Ink 12” display uses less than 1 such battery. Therefore, we can see that E Ink Displays save up to 60% energy versus LCD ones.  This numbers are pretty impressive. Unlike the LCD screen, E Ink display technology enables the electronic reader to replicate the look and feel of a printed book. This means that displays have the visual appeal of ink-on-paper and use no backlight so that screens can be viewed under almost any lighting condition, including direct sunlight, all the while using little power. One battery charge of four hours can power 7,500 continuous page turns. 
E-Ink displays can be used for touch smart phones as long as they support sensor technology. This makes them pretty interesting instrument for solving the problem of the long battery life, and the concept of the Second Life Phone proves this.
To sum everything up, we should say that the problem of long life of the battery is very important and hot, especially when we talk about wireless devices. The usage of wireless networks requires a constant stabile high-productive work of the device. The solution of the problem can be frequent charging of the battery, or there can be developed some innovations on the technical side. The example of Second Life Phone shows how the problem can be solved on the device technology side. The concept was never brought to life, but the technologies that it based on are widely used in the newest and the most innovative products of Samsung, HTC, Amazon and other corporations. The developing of power-saving technologies in the devices, such as AMOLED and E-Ink displays instead of LCD and, especially, Retina ones, combined with the great design and ergonomics can give the customer a real solution for the problem of the long life of battery. Instead of using tips for saving energy, or increasing the size of the battery, today we can use more comfortable technology that helps to preserve energy by its nature. The concept of Second Life Phone is a great example how progressive power-saving technologies can work together and bring a great result.