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are crt response times 0?
- Thread starter I3eyond
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santaliqueur
Gawd
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well everything has a response time, but CRT response times are measured in nanoseconds instead of milliseconds for an LCD.
VendettaUF
n00b
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Yep what the above poster said. CRTs use an electron beam to excite phosphors to change different colors. LCDs have individual liquid crystals that make each pixels. They change color a lot slower then the electron beam moves.
PCMusicGuy
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Actually, a typical CRT's response time is usually on the order of 0.8 or 0.9 milliseconds (800~900 microseconds). Certainly not in nanoseconds.
UrielDagda
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The crt "response" time is usually called persistence, as in how long after the phosphor is hit and stays lit before it requires refresh. Expressed as long, medium-long, medium, short, etc.
I think when that was a "big" thing was back when long persistence phosphor would lead to burn-in without the use of screen savers. I never really heard it referred to as a limitation on actual refresh or framerates.
I think when that was a "big" thing was back when long persistence phosphor would lead to burn-in without the use of screen savers. I never really heard it referred to as a limitation on actual refresh or framerates.
Actually, its not the electrons determining the response time, but rather the relaxation time for the phosphor atoms to return to the ground state.iJeff said:
Furthermore, CRT phosphors are tuneable for varying response times. Some go into the nanosecond range (some of the yttrium and zinc oxide phosphors), while others can have decay times lasting several minutes.
No, any particular phosphor compound emits a certain wavelength, period. They don't change color.
The display of different colors are achieved by varying the luminance level of nearby phosphor dots, and the resultant optical illusion of your eye mixing them into a single color.
masher said:
Isn't the movement of electrons from one energy level to another in the phosphors the actual mechanism that emits light/energy? I remember learning something like that in high school chemistry. So, if you wanted to be uber pedantic, it really is the electrons.
...unless I'm wrong, which I could be.Very true...but at this level, it is also the electrons in liquid crystal molecules that gives them their dipole moment, and thus causes them to align with an externally-applied electric field. So if you want to be pedantic, it's still not that "electrons are faster than liquid crystals"...but rather that electrons can change state faster than they can force realignment.iJeff said:
When I thought about this a while ago I never considered factoring the phosphor's part in the picture but thought it would be the time it took for the electron beam to travel from the gun to the front of the tube which would be the time it takes light to travel 1-1.5 feet...but now I know and knowing is half the battle.
Actually, electron beams in a CRT don't travel at the speed of light; their velocity is a function of the accelerating voltage. I think most CRTs run about 20 kV, meaning each electron is charged to 20 keV, giving them a velocity of about 0.27c. (if I did the math correctly...)
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Either way its WAY faster than any human eye can see.