High Brightness LED, HBLED Tutorial
- details or tutorial about high brightness LEDs, HBLED, the technology and how they work.
High brightness LEDs, also known as HBLEDs, are now entering the marketplace.
As the name suggests these high brightness LEDs offer much higher levels of luminosity than the standard LEDs.
In view of their performance high brightness LEDs are now entering many areas where other technologies had reigned supreme before.
High brightness LEDs have a number of advantages over the standard LEDs that were previously used in applications including indicators, and displays.
- Longer life
- Low cost
- RoHS manufacturing compatibility (lead free)
What is an HBLED?
With many LEDs being introduced onto the market, and available light levels increasing, it is useful to be able to define an HBLED and understand what differentiates it from a standard LED.
Obviously it is dependent upon the brightness of the LED itself.
One overview of what a high brightness LED is that it is a LED that produces over 50 lumens (1 candela = 12.75 lumens).
High brightness LEDs should not be confused with high power LEDs. Although they may be one and the same, high power refers to the power consumption and not the light output. Generally it is assumed that a high power LED consumes more than 1 watt in power.
One of the chief reasons for using high brightness LEDs is their improved efficiency over other types of lamp. It is worth comparing HBLEDs with other lamps in terms of lumens per watt.
|Lamp type||Typical efficiency
(Lumens per watt)
|High brightness LED||
>100 and improving
|Tungsten filament lamp||
|Sodium street lamps||
~100 - 200
There are several enhancements that have been made to basic LED technology to enable the high brightness LEDs to be manufactured.
The initial indicator LEDs used a traditional through hole style wired package. A standard 5mm LED would produce a light output of around two or three lumens for an input of 100 mW - equivalent to 20 or 30 lumens per watt.
Surface mount technology allowed development of LEDs in such a way that the printed circuit board could act as a heat sink - with LEDs mounted onto the board, any heat could be removed reasonably effectively, and this allowed light levels to be increased.
The next development was to add a thermal heat slug directly into the bottom of the surface mount package. Being located directly under the LED junction, this allowed heat to be removed far more effectively.
High brightness LEDs utilise this effective heat removal to enable the HBLED junction to remain within its safe limits while still producing he light output required. In addition to this, more effective manufacturing processes have enabled the efficiency to be improved.
By Ian Poole
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