MadSci Network: Computer Science

Re: Does playing videogames effect the colors of a television ?

Date: Mon Feb 11 13:32:09 2002
Posted By: Dietmar Hildebrand, Post-doc/Fellow, Radiation Biophysics, Scientific Services
Area of science: Computer Science
ID: 1006623937.Cs

Assuming your TV is built using a CRT (Cathode Ray Tube): The image of a 
CRT is created by a scanning electron beam, which excites the substances 
on the inner wall of the front glass to emit visible light via 
phosphorescence. A fine raster of different substances will light up in the 
colors red, green and blue, which causes you to perceive a color image.
If the electron beam always hits the same dots (e.g. a purely blue area of 
a video game background), then these surface points age faster (i.e. their 
capability to phosporesce diminishes over time). Over several months of 
operation this can create a visible difference in areas of the screen, 
when a picture with little details and large monochrome parts is 
displayed. So indeed playing video games or leaving any static screens on 
the TV for long hours has a negative impact on color uniformity across the 
However, more likely the color hues, which you describe, are induced by 
strong magnetic fields in the environment of the TV. The magnetic field 
causes the electron beam to miss the targeted points and excite points 
around it. Just take any strong magnet and bring it near the screen to see 
this effect. [Admin Note:  if you bring it too near for more than a 
second or so, it can cause permanent damage to the monitor; you might 
want to try this with an old tv or monitor instead. -- RJS] The cause can be in 
the near surroundings (e.g. a power supply with a big improperly shielded 
transformer near the TV) or even outside the building (e.g. people living very 
close to electrical train tracks can have this problem every time a train 
passes by).  Certainly a defect in the TV itself can also affect the electron 
beam and cause color hues.
Temporary color hue changes can also happen, when the signal from the 
sender to the antenna is affected. A technique to prevent this is used in 
the European TV systems (PAL, phase alternated lines). The US is still not 
using this technique. So as a joke the acromym NTSC of the US TV system 
can be expanded to "Never The Same Color".

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