What are the differences in smartphone display types and resolutions?
A lot of attention with smartphones is on the display. The large screen is in daily use and should meet the needs of the user. When choosing smartphones, however, you quickly come across many technical terms and can quickly lose track of which type and which resolution can offer what.
Resolution of a smartphone display
The resolution of a display indicates how many pixels the display is made up of. The pixels on the long side are listed times the pixels on the short side (e.g. 1920 x 1080). The different sizes are then given a name such as HD, Full HD, Quad HD or Ultra HD.
The abbreviation ppi stands for pixels per inch, i.e. how many pixels per inch are processed in a display. At a normal viewing distance of 300 pixels per inch or more, the human eye can no longer see individual pixels.
HD stands for high definition and is one of the most common abbreviations that you have to know about displays. A smartphone display has an HD resolution if the narrower side has 720 pixels. Such a display is often abbreviated to 720p display in the data sheet. A screen used to have an aspect ratio of 16: 9, but this is rare these days. However, the number of HD pixels still goes back to this aspect ratio and accordingly has 1280 pixels on the long side.
HD + is used when the aspect ratio is not 16: 9, but the side is a little longer, as is the case with most smartphones these days. Here you can often find displays with 18: 9, 19: 9 or even 21: 9 aspect ratios. If the shorter side still has 720 pixels, but the long side has more than the 1280 pixels that are available in a 16: 9 format, it is called HD +.
Full HD resolution is achieved when the shorter side of the display has 1080 pixels. So there are 1.5 times more pixels along the short side. The longer side is multiplied by the same factor and has 1920 pixels. So if a 16: 9 display has a resolution of 1920 x 1080 pixels, it is called a full HD screen.
Full HD +
Since full HD displays in smartphones usually do not have a 16: 9 format, but are a little longer, the longer side is equipped with more pixels. This leaves the narrower side at 1080 pixels, but the longer side can also have more than 2000 pixels.
Quad HD (2K)
Quad HD is a display that has a resolution four times higher than that of an HD display. The pixels on each side are doubled, so the shorter side is 1440 pixels and the longer side is 2560 pixels. Since the number of pixels here rises above 2,000 for the first time, this resolution is also referred to as 2K for smartphones. The abbreviations QHD and WQHD also correspond to this number of pixels. Many flagships currently have a Quad HD display.
There is also a plus version of the Quad HD resolution. As with the HD and Full HD versions, the plus relates to the additional pixels on the long side. The base page remains the same at 1440 pixels. However, the longer side is stretched to the appropriate size and thus receives an addition of pixels.
Ultra HD (4K)
Ultra HD has a resolution of 3840 x 2160 pixels. It is eight times the resolution of HD. So far, this resolution has been very rare for smartphones and is also associated with increased power consumption. The only smartphone displays that currently have Ultra HD resolution were manufactured by Sony. Among other things, the Sony Xperia 1 can convince with such a display.
It remains to be seen how useful it is to increase the pixel density of smartphones further, since the human eye can barely perceive a pixel density higher than 800 ppi even when viewed very closely.
Although none of the values of the Ultra HD resolution goes above 4000, this resolution is referred to as 4K in smartphones.
Display types of smartphones
An LC display consists of many liquid crystals, which give the display its name “Liquid Crystal Display”. The crystals of the panel are illuminated from the back to display all information correctly. This can lead to slight color distortions. These displays can deliver good results, especially with high light irradiation, and can be easily recognized from all angles.
The TFT display is an improvement on the LC display. With this “Thin Film Transistor” display, each pixel can be addressed individually by its own transistor. These displays can have higher contrasts, but do not have the same viewing angle stability that an LC display can offer. In addition, the power consumption of a TFT display is higher.
IPS stands for In-Plane Switching and is a type of display that is a further development of the TFT display. They work similarly to the previous displays, but they are brighter and use less power than a TFT display.
Retina displays can be found in most Apple products. The term retina is registered as a brand name. According to Apple, these displays have such a high point density that the human eye can no longer see pixels. But they are basically also IPS LC displays and work with liquid crystals in a matrix.
The big difference between OLED displays and LC displays is that OLED displays have pixels that light up themselves. You can do without the back lighting and thus have no color deviations. This makes them significantly more economical than LC displays, especially when playing back dark pictures or videos. Since they do not need a backlight, they can also be made significantly thinner. Their response time is also significantly faster than that of LC displays.
One of the few disadvantages that OLED displays have is their susceptibility and thus also their lifespan. In the case of smartphones, however, this is usually negligible. In early versions there was even a so-called burn-in of images, meaning that some pixels were no longer as bright as they were before an image was displayed for a long time.
Most of the aforementioned problems with OLED displays have been largely remedied through continuous improvements. Active transistor matrix technology has been added that allows each pixel to be controlled individually. These displays continue to have the same advantages as OLED displays.
So there are a wide variety of displays to choose from. Whether you opt for an LCD or an AMOLED display is up to you. If you want rich colors and a deep black, you should use a smartphone with an AMOLED display. If you prefer to pay attention to high viewing angle stability and colors that are true to the original, an LC display is well advised. Nowadays, however, all types of displays can produce excellent results.