Color Bleed

[Gideon]

Hi.  I read here that color bleed develops when mounting a television at an angle.  Would someone please explain what "color bleeding" is?  It sounds like a problem that could be solved by degaussing, but then again, I have no clue about these matters.  I'd like to find out more.  Thanks!

[JasonF]

Monitors (and televisions) rely on magnetic fields to direct the beam of electrons to the appropriate spot of phosphur on your screen to display a color.  If the beam is deflected even slightly off target, it will illuminate the phosphur next to it instead (so instead of a red "pixel" lighting up, you might get a blue).

There's a whole process performed at the factory of adjusting the monitor's magnetics in order to get good purity and convergence, which involves precise positioning the yoke and adjusting 4-pole magnets on the neck.  While making this adjustment, it's important that the monitor is in the same orientation that it will be during use, because the Earth's magnetic field also plays a role in how the electron beam is deflected.

If you change the orientation of the monitor after purity and convergence is set, you can expect the Earth's magnetic field to act differently, and will see some areas of the screen where the color appears off-tint.  This might resemble the need for degaussing, but it is not the same as part of the monitor becoming magnetized (which also causes deflection problems that illuminate wrong phosphur).

This effect becomes more noticable with smaller dot pitches, because each phosphur color is closer together, so small amounts of error produce more dramatic results.  To illustrate, take the computer monitor that you're looking at now, and turn it sideways.  

[Gideon]

Thanks!  You give a clear explanation.  Now, I am wondering how people using television sets in their cabs get by with color bleeding.  I wouldn't be able to stand it.

To illustrate, take the computer monitor that you're looking at now, and turn it sideways.

Heh.  You're assuming that I use a CRT display.  I could have been staring at my LCD for a good five minutes waiting for something to happen!

Edit:  Oh, I am also wondering if there are any permanent effects with color bleeding that could not be solved by turning the TV to the correct angle and degaussing.  I doubt that there are, but I want to know for sure.

[JasonF]

Now, I am wondering how people using television sets in their cabs get by with color bleeding.  I wouldn't be able to stand it.

That, I haven't quite figured out, because some models seem to be immuned.  Could be better yoke designs, or bigger dot pitches for the beam to fall on, etc.  

For instance, you can take a G07 arcade monitor, orient it just about any way, and not notice a difference.  But, I have a WG 4600 series that looks great vertically (it is meant for vertical display), but turn it horizontally, and you get all kinds of distorted colors in the corners.

Heh.  You're assuming that I use a CRT display.  I could have been staring at my LCD for a good five minutes waiting for something to happen!

I thought about that after I sent it...  I normally work on my laptop, but at the time, was sitting in front of a desktop with a CRT.

[Gideon]

That's kind of unsettling.