Smart Light Bulb

I guess we all are familiar with smart home automation with smart appliances where your refrigerator could

tell you supply shortages inside the fridge and smart enough to produce grocery list for you.  Who will think even a small light bulb is also smart?  Well, it is coming soon and most lighting manufacturers are making their lighting products smarter.  It will be much more easier to do so with the use of light-emitting-diode or LED technology.  Solid State Lighting (SSL) has come a long way and it has been a privilege for me to witness the evolution of its development till now. 

The traditional Edison bulb requires no additional circuitry to burn the tungsten.  In fact, the hotter its get the better its illumination.  Unlike the Edison bulb, LED requires DC current to operate and the cooler its get the better its illumination; the direct opposite of incandescent lamp. 

How do we operate the SSL on AC power line?  Simple!  We need an AC to DC power supply squeeze into a tiny housing.  The LED driver chipset has improved over time and now even the designer includes a single stage power factor correction internally that makes the power factor as close as possible to 1; most of the time measurement will shows around 0.95~0.99.  Not only that but overall bill-of-materials also been reduced in order to reduce the driver printed circuit board (PCB) size to reduce the overall system costs.  How about AC LED?  Are this LED really operate on AC?  No!  Diode is always a Diode. Thomas Edison discovered the principle of diode during its light bulb discovery but he is not aware of its application until later.  There are several ways to operate the LED on direct AC line.  One of the technique is to use high voltage VF (forward voltage) LED, as high as possible, in order to reduce the power loss from the additional voltages.  One can use a current source either at the front- or back-end; there is advantage and disadvantage by doing so.  This is a straight forward technique without any control and monitoring that may affect the power factor and system efficiency.  By putting intelligent into this technique, one could monitor the AC line and switch a string of LED accordingly to make sure the Current Phase and Voltage Phase are aligned; high power factor.  As the AC goes up and down, different array of LED will be switched on / off.  One drawback of this technique is more LEDs are required in order to achieve the same brightness compared to conventional AC-DC driver and linear AC LED.  Other techniques are existed......soon to be discovered.

Now, we have the power supply smart enough, what else can do to make the light bulb smarter?  Communication? YES! By adding communication to it one will be able to communicate with the light bulb and tell it what to do or how is it doing?  I stop here for now as the rest is trade secret :).  I leave it to the reader to imagine what else he/she could put into his/her light bulb.