In one of the previous articles in Uni’s ABC series, we have discussed the crucial parameters of LCDs, pointing out, e.g., resolution, brightness, contrast ratio, or viewing angles, which impact the readability of the presented content. In some applications, there is also another worth noticing factor, that is, the LED’s durability. In datasheets, this parameter is usually called as “LED life time”.
LED – a light-emitting diode, is a basic element of LED backlights used in LCDs. The manufacturers define the backlight’s LED life time, so the average time of LEDs’ failure-free operation. It is specified as the number of hours followed by degradation of LEDs; then their luminance is 50% compared to its original value.
Is there any standard LED life time?
Well, there is no one-size-fits-all answer for such a question, besides “it depends”; mainly, it depends on the type of application that requires LCD. In the case of, e.g., consumer electronics, let’s say – TVs, we can choose a 30 000 h LED life time model. If we suppose that we will use it for 8 hours in each of 365/366 days in a year, it can function properly for about 10 years. Then, we can assume that the “standard” LED life time for this type of device is 30 000 h. It seems like a long time, especially for a TV’s users – nowadays, at galloping technological progress, the 10-years old devices may be perceived as “bygone”. (Just think about the dynamic extending of the resolutions applied in TVs – in 2014/2015, the 4K technology has popularized, today, in 2020, the 8K technology is on the tapis.)
In many applications, the LED life time will not be a crucial parameter that will preordain a particular LCD’s choice. Let’s conceive of assembling a 3.9-inch WF39BSQASDNN0# by Winstar, which LED life time has been estimated at 50 000 h, in a coffeemaker. If we suppose that this device will be intended to use in the office, e.g., for 10 hours each day, this screen will function properly even for 14 years. (All in all, such intensively used coffeemaker probably will be able to operate only for a few years due to the wear of other machine components.)
However, a few applications require LCD of “standard” LED life time at the level of even… 100 000 h (what kind of applications are they? – just read on ;-).
Which factors impact LED life time?
In datasheets, the manufacturers indicate the factors that should be maintained on a steady level to provide the longest LED life time at the optimal intensity of emitted light. Among them, e.g., temperature. Example: for AUO’s displays – 54.6-inch P55HVN12.0 and 85.0-inch P850QVN03.1, the LED life time has been estimated at 70 000 h, so about 8 years of continual functioning, as long as the environment temperature is 25 +/-2°C. Any fluctuations may influence the LED life time, which is related to the structure of LEDs – they are made of silicon, which properties contingent on temperature.
What devices need 100 000 h LED life time?
The extended LED life time is crucial for devices intended to work in continuous mode, 24/7. These are solutions used in, e.g., digital signage systems. Litemax is a pacemaker among the producers of extended LED life time LCDs. Its offer is full of solutions, which LED life time is estimated at 100 000 h. These are, e.g., LCDs of Spanpixel and Durapixel, as well as Squarepixel series. They can be used, e.g., in transportation to provide up-to-date information about, e.g., timetables or route courses (in this case, you should learn more about SSF2845-E, SSH2845-E, and SSD2845-E, which meet the requirements of EN 50155 standard). These solutions can also be applied in other public spaces as various information carriers in, e.g., shops, hotels, restaurants, and coffeehouses, as well as offices. What is more, the LED life time of SCD2365-Y, so the circular LCD, has also been estimated at 100 000 h; it can be an attractive element of the windows of, e.g., customer service points.
PS. In recent years, LCDs with LEDs getting more and more advanced. One of the developed functionalities is local dimming, also implemented in some of Litemax’s solutions. Learn more about selective backlighting – here.
Are you looking for an LCD adapted to operation in continuous mode, 24/7? Contact us – we will do our best to find a proper solution.
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