16 April, 2010

A patent and Power Management in Small Gadgets

Can silly idea change the world? Certainly! There are many examples in the history. Here is a simple story. Don’t neglect basic mathematics and physics where ever you are…

It is a story of patent (Patent # 5280371, Directional Diffuser for a Liquid Crystal Display) made by an MNC. The same technology is now being used in smart systems. It was developed to minimize the scattered light from the source and to increase light rays directionality. However, the saving might be small percentage in case of large displays. On mobile displays the saving will be considerable.


An aircraft (civil/military) will be equipped with the state-of-the-art electronics ranging from Flight Controls, Displays, Flight Management Systems, Servos, etc. All these systems needs high power generators, usually the aircraft engines will generate large power compared to small systems.

These display systems will be having CRT, LED or LCD based monitors. Except CRT, the other two requires less power, order of few tens of watt. Then why do we need to save small quantity of power (due to scattered light rays) in LCD display? We are engineers, be smart! J

An LED is active display that emits light on power (just remember, it will replace entire lighting systems in near future. The CFL technology is an alternative). Where as, an LCD is passive display, which requires external light source (backlight) for illumination. Based on viewing angle the light will be scattered to sides and vertical direction.

The idea here is to minimize the scattered light to sides, since the display is required only to the pilot. It was achieved using basic physics principles. We use convex lens to direct light on single point. How can it be made directional? (Hint: An array of convex lenses).

The same principle is used in mobile displays, PDAs, iPod, etc. The MNC licenses the technology to the required companies.

Have you heard about CAN, I²C and SPI protocols? These protocols are used in plenty of chips made every year. Need is base for them, yet, the “Need” not to be mother of invention always.