Thursday, May 16, 2013

Types Of Mobile Phone Screens : Explained

Screen of a mobile phone or a smartphone is one of the key features, users concern when buying a new mobile device. It's the main hardware that ,user can interact with the embedded software and do various things. Generation to generation the mobile phone screen has been evolved and today humans reached the milestone of making flexible screens.


There are so many types of screens out there with different technologies and pixel arrangements. Earlier days we had dot matrix screens and later we managed to make them display colors and now time has taken us to the era of touchscreens where screens are capable of showing crisp images,colors and retina beating pixel densities. Lets see what are the most popular mobile phone screen types out there.


TFT-LCD

These screens are the most common screen types and used in entry level to high end smartphones. It's a variant of LCD screens. For example almost all Nokia color display phones use TFT LCD panels. TFT LCD stands for Thin Film Transistor Liquid Crystal Display. Unlike the normal LCD pannels, TFT LCD panels gives better image quality and also supports higher resolutions.


As you can see in the structure above, liquid crystals are placed between two Indium Tin Oxide Pixel electrodes. The light emitted from backlight panel goes through liquid crystals and bright up the pixels. However TFT screens consume lot energy. due to this, battery life of devices that use TFT screens are not good unless they have a higher capacity. Since TFT screens are cheaper to manufacture most smartphone manufacturers tend to use these panels. Viewing angles are not the best in TFT screens, It's the reason why most Sony Xperia Z users complain about viewing angles and less vivid colors of the device. 

TFT screens often face the dead pixel problem, usually this happens when a single pixel died in the screen and whole pixel line vertically or horizontally to that pixel gets the same fate.

Here you can see a dead pixel row in a Nokia smartphone.

Another disadvantage of TFT screens are poor visibility in direct sunlight. therefore an ambient light sensor is a must have feature for smartphones with TFT panels.








SUPER LCD 

Super LCD screens are another type of  TFT LCD screens. But it's specially improved for low power consumption without reducing image quality. The latest from SLCD lineup is Super LCD 3, HTC J butterfly and HTC Droid DNA uses these kind of screens. These screens doesn't have an air gap between display element and outer glass like in ordinary TFT LCD panels. This makes the colors more accurate and reduce glare. Technology reviwers say Super LCD panels give more color definition than AMOLED screens.


You can see the  performance of Super LCD 3 screen of HTC droid DNA with LG nexus 4 and Samsung Galaxy SIII, Note that Droid DNA has a 1080p screen while other two are 720p.

IPS-LCD

IPS LCD Stands for In Plane Switching liquid Crystal Display. This is another great improvement for LCD screens. The technology used here is arranging and switching Liquid Crystal molecules between the glass substrates in a plane, parallel to the glass layers. IPS panels does a great job when it comes to viewing angles. Unlike TFT screens, IPS screens are capable of wide viewing angles and less power consumption.
Apple corporation use IPS pannels with oleophobic coating (finger print resistant coating) for their recent products.
IPS panels also got evolved quite recently to True HD IPS+ screens. Here we are dealing with the same IPS technology but supporting HD resolution which is 1280x720 and better color accuracy.

OLED

OLED screens made another milestone in Screen technology. It stands for Organic Light Emitting Diode,a totally different and impressive screen technology when compared to normal LCD screens. Here uses layers of carbon based organic materiels between two conducting sheets,which means an Anode and a Cathode accompanied by two glass plates on top and at the bottom. When electric pulse applied to the anode and cathode, Electro-Luminescent light produce directly by organic materials. Due to this,OLED screens doesn't need a backlight pannel , the pixels light up by them selves. That's why OLED screens have deep black colors, if there were a backlight panel light makes black color look bit more grey.


OLED pannels are very thin and consume low power. Therefore it's really helps to long last the battery. Some of key benifites of OLED screens are it's stunning color reproduction, wider viewing angles and fast response time.

AMOLED

AMOLED stands for Active Matrix Organic Light Emitting Diode. Taking a step ahead from OLED screens,AMOLED screens can control each pixel individuality while maintaining the properties of a OLED panel. AMOLED screens uses a different subpixel arrangement which can reduce the image quality a bit. AMOLED screens often use by smartphone manufacturers nowadays although they are quite expensive to produce.


Super AMOLED

Samsung electronics have the honor of making Super AMOLED screens. It's their own term for the AMOLED panels that they develop. Super AMOLED  screens are built with capacitive touch sensors on the display itself. these sensors helps to improve more touch response than it's predecessor AMOLED. Samsung has already took it's SMOLED screen to next levels by developing Super AMOLED+, HD Super AMOLED+ and FHD Super AMOLED+ screens.



 RETINA DISPLAY



Retina display is not actually a screen type though some people think it is. It's the name patent by Apple corporation for the screens they used in their iPhone and iPad lineup. Apple use LED backlit IPS panel with a high pixel density which human eye unable to identify pixels individuality at a normal viewing distance. Nowadays most high-end smartphones have screens with high pixel densities human eye could not differentiate. LG and Japan Display Inc are the largest screen suppliers for Apple.

NOTE : human eye can only differentiate up to 320ppi (pixels per inch) above that ,all are same.

Mobile BRAVIA Engine

Mobile Bravia Engine is a software integration by Sony to improve natural colors and contrast of their screens. BRAVIA stands for Best Resolution Audio Visual Integrated Architecture. Sony has already introduced the 2nd generation Bravia engine with new improvements such as adding a sharpness filter and image/video noise reduction. Bravia Engine 2 can be seen on Xperia Z,ZL,SP and V. Since it's a software integration, user can turn it on/off as he like.


Pure Motion HD+

Finnish giant Nokia has developed this feature for their Lumia smartphones. This is also not a screen type but a small hardware intergration in LCD/OLED panel. Pure Motion HD+ screen can light up the pixels twice as fast than other screens. This offers the best viewing quality of moving content. The contrast and colours of PureMotion HD+ display adapt automatically based on the surrounding light. It makes photos and videos easier to see in bright sunlight and in pitch black. Crisp and readable every day.




Screen Types To Show Up in The Future

Youm by Samsung


Samsung showcased Flexible screens at CES 2013 but still haven't seen in a real life device yet. Youm is the name of Flexible screen patent by Samsung electronics. Samsung claims Youm screens are unbreakable and supports higher resolutions.It is a AMOLED panel ofcause, 


Green PHOLED
PHOLED is the next generation of Super AMOLED. These screens are capable of delivering crystal clear details and colors while consuming low amount of energy when compared to other OLED screens. Green PHOLED screens uses the green and yellow color to make 25% more energy efficient display. Galaxy S4 was expected to spot a PHOLED screen but Samsung sticked with a AMOLED panel. Galaxy Note 3 might come with a PHOLED screen


Triluminos by Sony


Sony has confirmed they will use their latest screen tech Triluminos for smartphones. Sony claims that Triluminos screen use the highest color spectrum on a screen. This makes the screen shows more colors ,natural colors of an image or a video. Sony Xperia i1 AKA Honami is expected to feature a Trilunimos screen in Q3 this year.



Mobile Screen Resolutions and Names

QVGA - 240 x 320
WQVGA - 240 x 432
HVGA - 240 x 480
nHD - 360 x 640
WVGA - 480 x 800
FWVGA - 480 x 854
qHD - 540 x 960
DVGA - 640 x 960
XGA -768 x 1024
HD -720 x 1280 (720p)
WXGA -800 x 1280
FHD -1080 x 1920 (1080p)

Selecting the best screen is up to users needs. for examples i personally don't care about the viewing angles because it protects privacy in outdoors and public. Hope you learned new something from this article and if have a burning question, feel free to ask in comments.

Cheers!

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