In consumer electronics LCDs with LED backlight are standard nowadays. But to use this backlight technology also in industrial applications requires some precautions.
If you look into a production plant you will see a lot of displays. Nearly every production line is full of displays to monitor the single manufacturing steps for the operator. Monitors you will find also on the desks of the supervisors and manufacturing managers to visualize statistical values and other information to ensure the traceability of product information. Due to cost reasons and the longevity of manufacturing equipment there are still many CRT screens installed in the manufacturing floor. But this situation is changing now.
In the PC industry and also in the consumer electronics there are no CRT screens used any longer - they are replaced by flat panel displays. In the consumer electronics there are nowadays only large and ultra-flat high definition LCD TVs, Laptops and monitors for desktop computers offered to the customer. These flat panels use backlight technologies to ensure the brightness needed watch the images on the high resolution screens featuring good contrast. Cold cathode fluorescent lamps (CCFL) have for a long time proven themselves as well suited luminant for backlighting with good reason. They supply great brightness at high light efficiency with large-format displays and featuring a long life cycle of 50,000 hours particularly at high temperatures.
But in consumer electronics more and more LEDs are used to backlight the flat panel displays. Driving force behind this development is the increasing implementation of LED backlight units in mid and larger size LCD screens such as for laptop computers and flat panel TVs. Currently only 1.5% of LEDs are used in backlight applications for large displays. This figure is expected to rise to 25% by 2012 due to IMS Research. The success of the LED backlighting comes because its advantages. LEDs are mechanically substantially more robust compared to CCFLs. They also do not contain any mercury and only require direct current low supply voltage. His means that the high-voltage inverter required for CCFL lamps is no longer necessary. The consequence is a reduced system complexity and LED backlit LCDs can be used where high voltage is not desired e.g. in areas where thee is a risk of explosion. LEDs attain their full luminosity almost immediately, as soon as the operating voltage is connected, whereby the brightness can be regulated continuously over the entire range from zero percent to the maximum brightness without this having a negative impact on the life cycle of the backlight. CCFLs provide the full light output only when they have reached heir normal operating temperature.
But there is a challenge in the design of LED backlit displays for industrial applications " LED backlights produce substantially greater quantities of heat than comparably bright CCFL backlights. Therefore heat accumulation can occur in the display interior affecting the LCDs and the backlight. This means industrial LCDs with LED backlighting require a carefully developed concept for heat dissipation. But this problem is solved with especially developed housings for the LEDs which couples the LEDs thermally directly to the mechanical parts of the display which enables to transport the waste heat to the outside environment. This makes the LED-backlit LCDs a well suited supplement to the existing portfolio of industrial LCDs with CCFL backlight. Such displays will remain successful in areas where cost is a main criterion and the displays are exposed to high temperatures for longer periods of time. But in cases where aspects like greater mechanical robustness, a broad brightness range, and the avoidance of mercury and explosion protection are important LED-backlit industrial LCDs will succeed like it already did in consumer electronics.