[Info] Display technology explained

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2016-01-10 03:02

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Edited by Abaggie at 2016-01-11 15:36

Display Technology
The display of a smartphone can be roughly divided into 4/5 parts. To keep it simple we will call them:
  • 1. classification,
  • 2. backplane material
  • 3. technology
  • 4. touch panel (glass)

1. Classifications
First of all, there are basically two types of classifications for mobile phone displays: TFT LCD and AMOLED.
TFT LCD = Thin Film Transistor Liquid Crystal Displays
includes TFT  backplane, and requires backlight.
AMOLED = Active Matrix Organic Light Emitting Diode
requires TFT  backplane, but no backlight.
1.classifications
OLED pixels emit light directly, or not, in which case the pixels are off and completely black. This allows very high contrast and zero power consumption if black is displayed. LCDs do require backlight, which mostly allows higher maximum brightness and this displayed in cd/m².
 
Nowadays, we have Super AMOLED too, which means that the layer for the touch system is integrated into the display. Reflecting less light and allowing for a slightly higher peak brightness. In a word: it's an improved version. For instance, the MX5 uses a Full HD Super AMOLED display.

2. Backplane material
Both of them require or use a certain backplane material (technology). They address the pixels and they more or less determine display resolution, refresh rate, and power consumption. Currently there’re 3 options: a-SI, IGZO and LTPS (or CGS a variant of LTPS). *currently AMOLED uses either Amorphoussilicon or Polycrystalline silicon
a-Si = Amorphous Silicon:
widely used, simple  to produce, slow electron movement, low cost.
IGZO = Indium Gallium Zinc Oxide:
low power consumption,  improved touch sensitivity, fast electron movement, low cost.
LTPS = Low Temperature Poly-silicon:
even faster electron movement, great stability, difficult to produce  therefore expensive.
2. backplane materials (technology)
Faster electron movement means higher (switching) speed and resolution, but also bigger size of flat-panel displays. View the chart below for a more in-depth comparison.
 
In one word: the IGZO advantage is cost. The LTPS advantage is performance. IGZO and LTPS are roughly comparable; both are better than the widely used a-Si. Note: NewMode 2 is used by (the) Meizu (MX4),which essentially is CGS, which is similar to LTPS.

3. Display technology
TFT LCDs also have display technology, also known as TN, IPS and VA. We will only discuss TN and IPS as they are used in mobile phones.
TN = Twisted Nematic:
low cost and widely used, but limited color  reproduction and viewing angle.
IPS = In-Plane Switching:
wide viewing angles, better color reproduction, but  more expensive.
3. display technologies
So for instance, you could have, an IPS LCD with LTPS backplane or an IPS LCD with IGZO backplane. There are variations of IPS, for example, (NEGA) Negative, which reduces power consumption or, for example, S-IPS which improves performance. Not every IPS (or TN) has the same level of quality; this varies due to different suppliers/manufacturers, productions and variants.

4. Touch panel
Of course, your phone needs a touch panel too. The following touch panel technologies are mostly used: GG, (GF) GFF, In-Cell, On-Cell and OGS. GFF provides enhanced sensitive touch experience and single-layer GF is mostly used for entry-level mobile phones. GG has high mechanical strength, while OGS enables thinness, flexibility(removes air gap) and improved sensitivity. On-Cell is used for AMOLED, which is similar to OGS. Details below:
 
4. touch panels
If there is no air gap between the display and front glass, we call it full laminated too, which has several benefits such as low reflection, high transmittance, high contrast and low noise.
 
Touch panels can adopt Corning's Gorilla /Concore Glass or AGC's Dragontrail Glass to add extra toughness, scratch resistance and so forth. Both companies produce similar performing glass, depending on the generation.

Wrap up
As you read there are several elements and various technologies. Meizu mostly uses IPS (TFT LCD)  IGZO/LTPS displays and since recently Super AMOLEDs too. Toughened glass is present on all models and GFF, OGS or On-Cell is used as touchscreen technology.

For instance, the Meizu M2 Note sports an IPS (in-plane switching) LCD + Indium Gallium Zinc Oxide (IGZO) + GFF full lamination + AGC Dragontrail - display. All combined, and together with the quality of the individual elements and the adjustments determine the display quality. Of course, sometimes it comes down to personal prefrence too.