[clug] Monitors that swivel

[Alex Satrapa]

On 05/06/2009, at 09:48 , Lana Brindley wrote:

> 'Scuse my ignorance ... what exactly does the 40° viewing angle  
> mean? Why does this have that end result?

Here goes my "Dummies Guide to Viewing Angles". I have no idea what  
the target audience already knows, so pardon me if some of it is  
oversimplified or attempts to teach grandma how to suck eggs:

Look at your monitor from dead in front, you're now at 0° from the  
"normal" (the normal being a line perpendicular to a plane). If you  
imagine a bottle sitting on a table, the vertical axis of that bottle  
is parallel to the "normal". Now sit the bottom of a bottle against  
the monitor, again the long axis of the bottle is parallel to the  
"normal".

If you move your head (and thus your eyes) to the left or right,  
you're increasing your viewing angle from 0° to some other deviation  
from the normal, in the horizontal direction. A monitor with a 130°  
viewing angle will give you consistent quality image when you move to  
the left or right in such a way that your deviation from the normal is  
up to 65° (at this angle, you're basically looking at the monitor from  
the side, as if you were the second person to the left of the person  
driving the computer).

So too, you have vertical viewing angle, which means that if you move  
your head up or down you're increasing your deviation from the normal  
in the vertical direction. A viewing angle of 40° will usually mean  
that the monitor is designed to allow you to go "down" by 10° or "up"  
by 30° - the monitors are designed to have people looking at them from  
normal ergonomic positions with eyes 1/3 down from the top of the  
monitor and this viewing angle allows you to see even tones across the  
vast vertical expanse of a 24" landscape monitor for example.

A little detour, if I may, into the world of LCD technology. The  
simplest way to understand LCDs is that the "liquid crystal" part of  
the technology is (I'm oversimplifying here) tiny flat crystals that  
can be twisted around by the electric field passing through the pixel.  
So for "white" you'd have the red, green and blue shutters "wide  
open", for "black" you'd have the red, green and blue shutters  
"closed". For greys, you'd have the shutters twisted partially open.  
Imagine the shutters as being miniature venetian blinds. If they're  
partially closed, moving from side to side will not alter your view of  
the world outside the window. If you move up or down, the blades of  
the venetian blind will end up being rotated relative to your  
position, and you'll see more or less of the world outside the window.  
Now replace the world outside the window with the backlight of the LCD  
monitor, you have a decent analogy to the LCD technology.

When you twist that monitor on its side to give a "portrait" display,  
suddenly you have a 40° horizontal viewing angle, which means that  
even with two eyes in the same head from 50cm away, you can  
potentially see different shades of colour from one side of the  
monitor to the other when displaying a "black" image. That is, you've  
turned the venetian blinds into vertical blinds.

In such an instance, you either have to sit further away and off to  
the side, or close one eye (ie: reduce the difference in angle between  
each eye and the points on the screen, or reduce your point of view to  
one viewing angle). Neither situation is particularly comfortable.

Portrait orientation can still be useful if you're editing documents  
that consist largely of black text on a white background - the  
differences between "navy blue" representing black at one side of the  
monitor and "Cayenne" representing black at the other side of the  
monitor won't cause too many problems. White is pretty uniform, since  
white is achieved by having all the shutters open. You'll get some  
grey at the extremes, which looks like vignetting.

Hope this helps. And again, apologies for the oversimplification.

Alex

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