Mura Effect - Clouding

In general Mura Effect or Clouding means an uneven display surface caused by an imperfect illumination of the panel. Those effects may appear to be brighter or darker, less saturated, poor in contrast or from the general display presentation deviating areas, spots or pixels. Generally those effects are more noticeably with dark displays and under poor lighting conditions.

The Mura Effect is a constructional characteristic of up-to-date LCDs. Displays based on OLED technology (especially smart phone displays) are also effected by Mura or Clouding. Basically no LCD panel with background lighting - or even worse corner or side lighting - is guaranteed to not to be effected by Mura. Continued miniaturisation, especially slimmer panels and the extreme spread of smart phones in the past years made this effect more frequent and known to the public. All panel manufacturers are affected by Mura. It might be possible to eliminate some Mura Effects but in general the Mura Effect can not be repaired.

Mura is caused by 2 main issues:

  1. A LCD consists of serval layers. Due to production factors it is not possible to combine those layers 100% perfectly all the time without any seams or transitions. Additionally there is still the possibility of pollutions during production or that the backlight does not illuminate the crystals equally.

  2. Tensioning of the panel itself which leads to uneven lighting. Tensions can be caused by:

    • Mechanical influences like vibration, shock or wrong assembly (pressure of the casing)

    • High temperatures (extending of materials)

    Techanical tensions are often reversible if the cause of the tension can be removed (for example panel cooling down). There is no guarantee though. Additionally the panel must have the space to return to its original state and position. Image settings via OSD can also reduce the Mura Effect or make it less visible.

Mura Effects based on the first issue will be recognized during assembly by the roda QA. Those panels will be exchanged. Mura Effects caused by tensioning will most likely occur much later during operation. There is no way to predict a future Mura Effect occurrence or to effectively avoid it.

Mura is not restricted to specific panel manufacturers. Right now switching panel supplier(s) will not guarantee Mura free panels.

According to the panel manufacturers the Mura Effect is a constructive characteristic of the current LCD generation. It is impossible to completely avoid the risk of any Mura or Clouding Effects. Mura is no reason for rejection. Especially very large displays almost always come with some kind of Mura Effect. But in most cases this effect is only visible under specific conditions.

Mura Effects are not considered a defect or deficit but an unwanted side effect of the LCD technology. There are no claims against the manufacturer(s). Exchanging the display does not guarantee that the new display won’t have any visible Mura or Clouding Effects in the future. Right now it is technically not possible to guarantee that there won’t be any Mura or Clouding Effects during the operation of LCDs.