LED Lighting
We have seen a lot of spotlights. But many of us don't know that these spotlights are made by using LEDs. Many individual LEDs are combined together to form a spotlight.
There are many types of LEDs. SSL LED is one of them. SSL LED is Solid State Lighting (SSL) Light Emitting Diode (LED). SSL LEDs are one in which the LEDs are replaced for brightly shown bulbs i.e. incandescent bulbs and fluorescent lamps. In SSL LEDs the light source is formed by the grouping of a bunch of white LEDs. The LEDs are very efficient because the output of the LED is 32 lumens per watt (lm/ W). And due to the new technologies it is able to liberate up to 80 lumens per watt. These are vigorous than incandescent bulbs and fluorescent tubes. Now-a-days the cost of the LEDs are decreasing but these are not sold in many places because of the high expense due to the requirement of the power source conversion in the household applications.
When compared with LED the incandescent bulbs are very cheap. The efficiency of the incandescent bulbs are very less, but the Fluorescent tubes are very efficient. The incandescent bulbs provide an output from about 16 lm/W to 22 lm/W whereas the fluorescent tubes provide 50 to 100 lm/W for domestic tubes. The average output provide by fluorescent tubes is 60 lm/W. But the fluorescent tubes are very bulky and they need a starter. The mostly used incandescent bulbs are tungsten bulbs and halogen bulbs. The output of domestic tungsten bulb and halogen bulbs are 16 lm/W and 22lm/W respectively. Because of the high efficiency and vitality the fluorescent tubes are mostly used for household lighting.
The nature of the LED is monochromatic. The LED lights have so many advantages. By the use of LED we can get many colors. In the traditional white lights there is a coating or diffuser, which absorb much of the emitted light. By the use of variety inorganic semi-conductor materials we can produce different colors of LEDs. Red, infrared, green, high-brightness orange-red, orange, yellow, pure green (or emerald green), blue, near ultraviolet and bluish-green are the different LED colors. For traffic signals and navigation lights emerald green is used. It is most recently introduced.
The largest LED display in the world is the 1500 foot long LED on the Fremont Street Experience and it is located in Los Vegas.
The LED panels are divided into two.
- Conventional panels
- Surface Mounted Device (SMD) panel.
Now SMD technology is an extending trend. For the indoor screens SMD technology is used. Now it is widen to the outdoor market also. A SMD pixel is made by using a driver PC board and a chipset. In this chipset three diodes are mounted. Red, green and blue are the three diodes. First , the three diodes are mounted on a chipset and after that the chipset is mounted on the driver PC board. The individual diodes are smaller than a pinhead.
For indoor use SMD technology based screen is required. It can produce a minimum brightness of 600 nits. For retail applications this brightness is sufficient, but the conditions which needs high-brightness stage lighting such as fashion shows and auto shows require higher LED brightness for visibility.
Recently, only discrete diode screens are used for achieving the required brightness level for outdoor use. The minimum level is 2,000 nits and maximum is 5,000 nits.
Depending upon some factors, suitable locations are identified for large display panels.
The following are the required factors.
1. sight lines
2. local authority planning requirements
3. vehicular access
4. cable runs for power and video
5. power
6. suitability of the ground for the location of the screen
7. overhead obstructions.