display area of mobile phones – displays are becoming increasingly important when choosing a new device forms an important criterion. Nowadays, quickly evolving technology, there are a large number of types of displays, which is not hard to lose. In this part of the scientific section of our window we will introduce the most commonly used types, principles on which they work. Bring your equipment where you can meet with them.
Times monochrome monochrome screens have been for some time for us and rule the world, color display with thousands to millions of colors. Displays with different technologies, there are many, and when selecting a new phone, which can move up to whom sight. The following lines of the windows of our research should help you not only make sense, but also understand the basic principles on which they work most commonly used screens.
The first mobile phone with color display is considered that the Siemens S10 in 1998. He managed to see 4 colors – red, green, blue and white
fineness of the screen
basic parameter, applicable to all technologies equally, the softness display, often known as a raster display. The fineness of the grid is given in DPI (Dots Per Inch), or dots per inch. Practically therefore expresses the number of points that fits on the length of one inch (2.54 cm). The DPI value is greater, the finer the display. Most phones today at DPI value ranges from 140 to 300 +.
density of 300 dots per inch no human eye can no longer perceive the individual pixels. The first phone with such a fine display was the Sony Ericsson Xperia X1 with gentleness 311 DPI. To name of the current models such as Samsung Galaxy Nexus Nokia E6, or line of iPhones from 4 generation. Especially Apple, then your display with the density of pixels called the retina (retina).
LCDMost of the displays used today fall into the family of the LCD. LCD Abbreviation terminology expresses Liquid Crystal Display. The technology is based on the electromagnetic properties of liquid crystals. Basic LCD division is active (TFT) and passive (STN) technology. Nowadays practically only used TFT for its better display capabilities.
Activedisplays used for each of the separate transistor pixels, which ensures the activation of a pixel – a pixel. Every single pixel of the LCD consists of liquid crystal molecules suspended between two transparent electrodes and two polarizing filters. With the voltage on the electrode position is determined molecular crystals through which light passes through polarizing filters zpolarizované. The intensity of transmitted light is then regulated by the position of molecular crystals.
It follows that the LCD must be present at a constant source of light, even when displaying black. To obtain light using cathode-ray tube emitting white light. White light is used due to containment of all wavelengths of the color spectrum. The light is then decomposed into three primary colors – red, green, blue (Red, Green, Blue – RGB). The various states of molecular crystals can be controlled for each color of light transmission and therefore the intensity of color. The color of a pixel is divided into the so-called sub-pixels. Using the additive mixing these three colors then reaches hundreds or thousands of different colors. Each part is defined by thin glass panels.
Scheme of the active pixel LCD
For products
upper classes are increasingly encounter IPS display. He also falls into the family of the LCD, but offers a more realistic color reproduction and wider viewing angles. Contrast, however, is not just the highest and the administration of black is not as perfect as the OLED displays. Currently offered with IPS screen phones as the Nokia 603 and 701, iPhone 4 and higher generation, or the LG Optimus Black. He also carries the IPS panel with designation Nova . This is a special technology from LG, which brings brightness to 700 thread (thread – the basic unit of luminous brightness). This greatly improves readability in direct sunlight.
first Nova device with IPS panel – LG Optimus Black
newer generation LCD called Super LCD, or even S-LCD . It also offers the truer color rendition and a higher viewing angles up to 5 times less energy efficiency than previous generation LCD. This type of panel display offers above almost all HTC phones, its higher ranks and also the model Google Nexus P.
OLED
Like LCD, OLED pixels are also divided into different sub-pixels. Unlike the LCD does not need any internal source of light. The basic principle of OLED technology is the location of the organic material between two electrodes – an anode and cathode. Applying a DC voltage by means of electrodes into the organic material can be retrieved subpixel positive and negative charges. These charges are then connected in the radiating layer, and there is light radiation. The radiation intensity of each sub-pixel (red, green, blue) can comprise a variety of colors.
Thesesubpixelům voltage is conducted using a special conductive layer. A very layman’s terms – after the voltage to the subpixel subpixel will shine, just like an ordinary LED. It follows that when displaying black pixels will simply shut down. This is fundamentally different from TFT LCD technology. This results not only show a much truer blacks, but also a significant energy savings. Another interesting feature is the possibility of flexible production and flexible displays. With that in mind as far Samsung and Nokia, have already presented their concepts.
TIP: Look at the functional concept device from Nokia with a flexible display.
Nevýhodou these panels is a shorter life, visible grid displeje i hodnotě at high DPI and higher production costs. Even on this issue, but no longer works and is in the development of new types of nuts, which provide fine grid and the pixel density of around 300 DPI.
scheme OLED pixel
OLED active matrix display called AMOLED . Active matrix is the pair of transistors for each pixel separately. This increases the current flow and reduces the response time. Compared with a passive matrix display (PMOLED) has AMOLED display higher frequency, sharper image, and lower power consumption. The disadvantage is more complex structures and the associated higher price. One AMOLED pixel is composed of 8 sub-pixels. With this display, we find in phones such as the Dell Venue Pro, HTC Legend, Samsung Galaxy, Nokia C7-00, Nokia 700, or Nexus One. They are equipped with it also the first series of HTC Desire.
Improved versions of the so-called Super AMOLED . This version combines the display and the touch of a single layer. Compared with conventional AMOLED stands out brighter colors, better readability in sunlight, better viewing angles and energy savings. It can be found exclusively in the higher ranks of the Samsung model. Namely Galaxy, the Nexus S, Omnia 7 or such S8500 Wave.
OLED displays have been criticized for generally coarser grid and the high value of DPI. This malady largely removes Super AMOLED Plus . For it is used a new type of matrix called Real Stripe. This one uses just 12 pixel sub-pixels, thereby providing a really fine display. Devices with this display are now only two – Samsung Galaxy S II and Samsung Droid Charge.
TIP: Do not miss our review Samsung Galaxy II.
Direct comparison of pixel AMOLED AMOLED and Super Plus
LG in August 2011 launched its own bar built on the principle of OLED – Ultra called AMOLED. Unfortunately for him but not much specific information. The actual manufacturer claims that the display behaves better in direct sunlight than a typical AMOLED. This is apparently due to its double reflection of external light. It is not clear whether the polarizing filters, like ClearBlack displays from Nokia, or whether the contact area is located directly on the display, like the Super AMOLED from Samsung. So far the only phone with this display panel is LG Optimus Sol.
LG Optimus Sol – the first and only representative of Ultra AMOLED
interesting technology, developed in 2010, the Finnish company Nokia is called ClearBlack display (CBD), based on AMOLED panel. CBD is characterized by adding another layer between the screen and touch part. This layer reduces the release of external light, so that nedopadá the display part. This is achieved much better visibility, such as under direct sunlight. At the same time also significantly improves the contrast ratio. This kind of display can be found naturally only in models of the Finnish manufacturer – for example, Lumia 800, N9, N8, C6-01 and E7-00.
ConclusionAs in all directions in the field of display technology progresses by leaps and bounds forward and will be interesting to see what direction it will take further. To this list were included kinds of displays, which are nowadays in mobile devices often encounter. I firmly believe that today’s science window you brought a little light into the world of display panels.
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