There are two main display type families: LCD and OLED. LCD stands for Liquid Crystal Display and OLED stands for Organic Light Emitting Diode. These displays are built on different technologies and there are smartwatches, smartphones, and tablets using both types. Devices such as the original HTC One, Motorola Moto 360, and Sony Xperia Z Tablet all use LCD panels, whereas devices such as the Samsung Galaxy Nexus use an OLED panel. LCD technology is based upon shining a light through the display and controlling the content by blocking pixels. Because of this, modern active LCD panels use a backlight, which is always turned on in use. Older, less sophisticated LCDs use a passive matrix, which does not need a backlight. OLED technology is different in that each individual pixel is illuminated, and because of this, the more pixels in use, the higher the power consumption. Showing a white colour on an OLED panel means activating all subpixels, which increases the power consumption.
This difference in technology is why LCD panels cannot produce the same deep blacks as an OLED panel. For most LCD panels, black is in reality a dark grey colour, whereas for an OLED, black is the absence of illumination.
OLED panels have a reputation for producing starkly colourful images with LCDs being muted by comparison, but most manufacturers allow OLED panels to have their saturation toned down and LCDs can have their saturation enhanced.
Advantages and Disadvantages
OLED panels offer the advantages of a thinner design as there is no backlight layer to be incorporated. OLEDs are also more responsive than LCDs. They can also use less power if most of the display is dark, but use more power if the display is predominantly white. OLEDs are also subject to screen burn, whereby a frequently seen image can leave a ghost of itself on the panel. OLED technology also deteriorates quicker compared with LCD.
OLED panels produce their colour via subpixel rendering. Each pixel actually consists of a number of subpixels, which may or may not be more visible to the user depending on his or her eyes. This means that for a given resolution, the OLED panel may appear less sharp than a competitor LCD panel. This phenomena depends on the colours being shown as different subpixels can be a different size.
LCDs are less power efficient when used to illuminate a small part of the display or when showing a dark display. Inexpensive LCD panels often “ghost,” that is, the display does not respond quickly enough to movement and it can cause visual artifacts. LCDs are also less flexible and it is much harder to build a curved or flexible LCD panel.