Originally Posted by tom669
The pulse width directly determines brightness, though.
The pulses are 500us long at the greatest, far too fast for the human eye to perceive.
Sure. Doesn't change that they are pulse determined.
It's not really PAM or PWM or PCM. It's an additive and accumulative code, with dithering for low-APL detail. The closest it is sort of like a time-multiplexed version of PCM, or like the old "1-bit DAC" designs that were big about 10 years ago (Delta-Sigma type DACs) but with 14/28 levels instead of just 1.
Plasma displays would not work at all if they had 10 fixed levels... you would just be staring at noise all the time.
How you gang up the information is up to the implementation. The term for PWM comes from the fact that any individual cell
cannot achieve partial excitation at point in time. You can
however, tightly define its duration.
Digital to Analog circuitry and the like are an example I almost brought up yesterday. Each line is a power of 2 greater than the line next to it, and each line is 100% gated by their corresponding bit in the source field. They're all added together. But the simile falls short; it's not like the plasma excitation at the lowest level.
BTW, there's a question I have about plasma material, related, that you've jogged my memory on. A white paper I remember at one point: there was this idea that a plasma cell could have several plasma types in it, basically multiply doped to have different excitation rates, yet the plasma material remained all mixed together. Such a device would have allowed two or four output levels (again, at any specific point in the time domain).
That ever materialize?