LCD or OLED - which one do you choose?

1. Display demands on the performance of the host processor and application development

• Classic character displays with some of the standard controllers are the least demanding because the required content is displayed only on the basis of the codes sent - we do not care about the content of individual pixels. This also implies that the development of character display applications is the least difficult.
• Monochrome graphical displays are considerably more demanding on the host processor, but thanks to the integrated controller the control is relatively easy and modern controllers (together with the firmware from the manufacturer) make it possible to simplify application development significantly.
• Full colour (RGB) graphical displays are naturally the most demanding to use, but they offer the most sophisticated ability to display any content.
  

2. Display Intelligence

Previous statements about the demands on the host (master) controller as well as on the development/complexity of the application apply only to standard displays without added intelligence.
However, there are already a variety of display module families on the market that incorporate a powerful graphics processor and firmware, which along with the development software (that is almost always available for free) can significantly simplify the development of graphics applications. The performance of the used processors is in many cases also sufficient to control the surrounding components, so that the entire application can be built on the basis of the display module, without the need for an additional microcontroller.

Intelligent displays of such kind are for example:

• UniTFT from Electronic Assembly
• all modules from 4D Systems,
• EVE family from Bridgetek
• - and partially also the eDIPTFT family from Electronic Assembly.
  

3. Touch panel

Almost every display can now be fitted with a touch panel - resistive or capacitive. Even OLED industrial displays are already becoming available with touch panels.

Although the ease of control and perhaps the habit from smartphones tempts us to use a capacitive display, it is not optimal everywhere. The ability to operate the resistive panel even with normal gloves is still a big advantage. Still, the touch panel slightly worsens the contrast and brightness of the display, so if the brightness of the display is a priority, it is better to use the display without the touch panel.

4. Light conditions (Ambient light)

The LCD display can be with or without backlight. The vast majority of available displays now have a backlight, allowing the display to be readable in darkness or dark environments.

However, under strong ambient light, and particularly in direct sunlight, the backlight is usually relatively dim, and the readability of the displays in the sun is significantly impaired. However, there are also exceptions where it is possible to maintain fair readability of the displays even in direct sunlight thanks to the technology used and the relatively powerful backlight.

OLED displays also suffer from significantly reduced contrast in direct sunlight, but some types provide acceptable readability even under such conditions.

5. Operating temperatures range

It can be stated that there are several display technologies on the market, but the absolute majority of display types use some analogue of LCD (STN, FSTN, TFT, IPS ..) or OLED. Some advanced technologies - such as VFDs (vacuum fluorescent display) are still available but are only beneficial for some specific cases, like operation in frosts with low power consumption at the same time.

So, knowing that even a modern IPS TFT panel is still a liquid-crystal display in its essence, it implies one fundamental fact - its reaction times and usually the contrast and viewing angles have a significant effect on temperature changes. However, even in LCD technology, we can find types capable of working in the range of -30 ... + 85°C, but it should be taken in mind that the characteristics of the display at the limit temperatures will no longer be optimal.

OLED displays, on the other hand, break down low-temperature barriers and work seamlessly at -40°C without compromising performance.

When selecting a display, it is therefore important to consider the temperatures at which the display will work, and in addition to allowing the extraordinary temperature conditions that may occur in the application environment. To learn more about the effect of temperature on display life, see our article Check the limits of your display.

LCD or OLED? Summary