And further, the other question, why don't they use electrostatic
> deflection? At least for the horizontal. I am pretty sure that
> today's transistors would have alot of trouble doing 1080i, if they
> ever can at all, because the yoke is inductive. Start kicking H up to
> 67.2 kHz, it is no fun. But with a non-inductive load, wouldn't the
> scan rate changes be easier to manage? They do it in spades in
> scopes.
Using electrostatic deflection requires a CRT with deflection plates. Such a tube would have (I believe) a thicker neck. Also, the output transistors would have to swing at least a couple hundred volts to deflect the beam.
My guess is that Sony, et al, stick with magnetically deflected tubes because they've been the standard for 60 years. That's the kind of tube they build, and the kind of deflection circuits they design.
However "correct" your theories might or might not be, they run up against industry practice. Electrostatic deflection is considered obsolete, at least with respect to video displays. And pretty soon CRTs will be obsolete with respect to video displays.
I have a Toshiba CZ-3299K HDTV that's about 12 years old. It has a 32" magnetically deflected CRT, and runs at four times the normal scanning rate (~ 63kHz) without problems.
Electrostatic deflection might be more affected by beam current
> changes.
I don't think so. Try changing the screen brightness of a 'scope's CRT. Does the deflection change?
I do not know enough CRT technology to know something of that
> nature. However, they have already found out that steady deflection
> along with precise HV regulation does not work. The raster will get
> smaller because beam density affects deflection sensitivity.
Again, I don't think so. If this were true, the image on any magnetically deflected CRT would show severe geometric distortion that varied with image brightness. It doesn't.
That's why there are seperate resistors going to each CRT anode in a
> high voltage splitter. That is also why they have abandoned extremely
> tight HV regulation in favor of more precise and modulated control of the
> deflection. They have integrated HV level with beam current, and also
> use it to control the vertical drive now.
Are you sure? How can you change beam current without changing brightness?