Rugged PDA LCD brightness – What’s in a NIT

The Rugged PDA market has seen a lot of new devices recently and its ever more important to have a USP for your device.  Motorola has been spending a lot of time during their recent products launches of the ES400 and the MC65 rugged PDA’s on the new super bright screens that they sport, especially regarding the NIT rating of them so we thought we’d dig a little bit deeper and tell you all about what this really means.  We did this in true RAM way and conducted a few experiments on the devices.

Whats in a NIT

Firstly a little bit about NITS.  The term NIT comes from the latin word nitere which means to shine.  All lovely and nice but what about the science!  A NIT is a unit of measure of emitted luminance.  It’s derived from the Candela which is the SI base unit of luminous intensity which measures this in a scientific manner via waveform strength (a whole other blog).  The reason this is not good for us and LCD screens is that we are looking at overall luminosity of the whole panel and thus we need a way of looking at luminosity over and area.  A NIT is precisely this, and is a calculation of Candela’s over a given area.  In fact 1 NIT = 1cd / m2.

Normally you see LCD panels in TVs and monitors expressed as cd/m2 so we can see here that a NIT is simply the name given to this calculation.

NIT benchmarks

Now lets put this into perspective by giving you some typical benchmarks for NIT ratings:

  • CRT TV/Monitor – 350 nits
  • Budget LCD TV – 350 nits
  • HDTV – 400-450 nits
  • Brand new premium HD TV – < 1000 nits
  • Old or budget Laptops – 200-300 nits
  • Macbook pro – 450 nits (unofficial figure)
  • Brand new Lenovo w700 – 400 nits

So we can start to see that claims of 750+ nits on the ES400 are indeed exceptional.

The NIT V’s The Lumen

Both of these measurements are often mixed up and both also based on the Candela.  The difference is the Lumen is a measure of reflected light intensity and this is the reason you see projectors measured in lumens and not the same NIT rating as an LCD.  The reason is you;re looking directly at emitted light on an LCD, whereas you;re looking at reflected light when looking at a projector screen.

This got us thinking though with our experiments.

Sunlight readability in Practise

So we had a look at the ES400 and MC65 against other LCD’s, in fact the best known topology and Casio screens we know of here and the results can be clearly seen below.  In our controlled lighting environment you can see clearly how bright the ES400 is, the Motorola MC65 not so bright to be honest, but still marginally brighter than rival devices.

However we wondered if the Lumens of the screen where in fact affecting the NITS.  What the heck does that mean…well it means that whilst in a controlled environment the MC65 looked brighter, it also reflected too much light in a real world environment which affected the screen readability more than the brightness.  The ES400 was so bright that it had enough oomph to look good everywhere but the result is with a good ant-reflective screen, we can;t see much difference in the readability of the MC65 screen.

Conclusion

At minimal viewing angles  reflected LCD light effects screen readability more than the NIT rating of the LCD to a point with the 750+ NIT rating of the ES400 screen starting to basically crack the nut with a sledge hammer.  At certain angles of view however, the NIT rating mattered less as the angle grew with reflections causing poor readability full stop.

Solution, get yourself a glare stopping LCD protector!

The Rugged and Mobile blog.

About The Author

Dave's one of the founders of Raptor, his rants are memorable, his thoughts are stimulating and his heart is set on helping, entertaining and making things like mobile, Android, ruggedness, 3D printing and IOT simple.

Related Posts