The Mura effect, or "clouding", is a term generally used to describe uneven displays, caused by the imperfect illumination of the screen. These effects can manifest themselves in areas or individual pixels that are darker or brighter, show poorer contrast, or simply deviate from the general image. As a rule, these effects are particularly noticeable in the reproduction of dark images and under darker environmental conditions.
Generally speaking, the Mura Effect is a fundamental design feature of current LCD screens. Mura Effects can also manifest themselves in displays based on OLED technology (especially on smartphones). Virtually no display that works with back-lit – or, even more severely so, with corner/side-lit – LCD technology is free of Mura Effects.
Because of the continuous miniaturisation of displays – particularly ever-decreasing panel width and the remarkably advent of smartphones in recent years – this effect occurs more and more often, and is therefore known to a wider range of users.
The Mura Effect is an industry-wide phenomenon that usually cannot be repaired!
There are two main causes of the Mura Effect:
- An LCD screen consists of several layers. Unfortunately, due to production reasons during assembly, it is not (yet) possible to constantly, perfectly, seamlessly, and smoothly connect these layers.
- In addition, contamination can still occur during the manufacturing process, or the backlight may not illuminate the crystals in a completely even manner.
- Certain stresses that arise within the panel itself may cause the backlight to no longer illuminate the display as evenly as before. Stresses are usually caused by
- Mechanical influences such as vibration, shock, as well as incorrect mounting (stress exerted by the housing)High temperatures (expansion of the material).
Mechanical stresses can often be fixed if the cause of the stress can be eliminated (e.g., allowing the panel to cool down). However, there is no guarantee that the effects will indeed disappear. For this, the panel must be able to return to its original (physical) position. Depending on the panel, making certain image settings through the OSD can either reduce the Mura Effects, or even make them virtually invisible.
In the 1st case, the Mura effect is already noticed by roda quality assurance professionals during installation, and the panel replaced accordingly. Mura effects that are caused by stresses usually only become noticeable after a period of operating. In these cases, there are practically no possibilities to effectively predict and avoid Mura Effects.
The Mura Effect occurs with devices of all manufacturers. Switching to another panel manufacturer does not promise any type of reliable protection against the possible occurrence of Mura Effects.
All panel manufacturers point out that the Mura Effect is a construction-related physical property of modern LCD panels, that they can generally always occur, and that they are not a valid reason to lodge a complaint. Very large panels in particular always show a more or less pronounced Mura or Clouding Effect. However, this is usually only clearly visible under specific conditions.
Mura Effects are not seen as a defect or deficiency, but rather as an undesirable side effect of the product type. No claims can be asserted against the manufacturer for this reason. After replacing a display, the new display might – sooner or later – show a visible Mura or Clouding Effect as well. At present, it is technically impossible to guarantee that Mura Effects will not occur when operating an LCD device.