Rob Studdert wrote:
On 14 Oct 2005 at 3:40, keith_w wrote:
This is pertinent, as I'm looking at that very range myself.
On reflectin, it seems to me the problem might be coming from having the CRT
adhere to the display ratio... If the screen dieplay was square, I'll bet all
squiggles would go away. But, that might be just my illusion.
Issues relating to screen width modulation due to changes in video intensity
are generally PSU related as Anthony said. Aspect ratio isn't generally problem
as these days the beam focus, defection and astigmatism is dynamically
controlled across every sweep.
Dynamically controlled! Now that is going to require another snippet of
self-education. I'll put it to Google, see what I get.
The deflection angle which is a function of the
tube depth vs screen width poses far more of a technical nightmare for
designers than aspect ratio and shallower tubes are being produced every year
to increase box aesthetics and to allow more finished units to be packed into a
container.
Sets this size are already in a weight class that makes it very difficult for
the owner to haul around, move, and so on. 105 lb. plus. So, if they can pare
weight off the total package, I suspect they do it. Where better than a heavy
power supply transformer? That's one place you can't miniaturize things much, or
as you've seen, performance becomes iffy.
The weight of a modern TV is primarily in the tube. As the tube size increases
the glass has to be made thicker to eliminate the chance of implosion.
Yeah. Count the number of square inches of tube surface, multiply times 14.7
psi, and that's how much total force is trying to collapse the tube, which
already has a small head start with the vacuum they draw on the inside...
There
are no mains frequency power transformers in most modern TVs, they use very
light and compact high frequency switch mode PSUs. These don't need to be
weighty to have good performance but a high performance supply has a comparably
high cost so that's a place that quality is often compromised.
Cheers,
Rob Studdert
HURSTVILLE AUSTRALIA
Excellent info, Rob!
My knowledge is 20 years out of date!
What the hey, so am *I*...at least!
Seriously, tho', thanks for dispelling some of my erroneous beliefs.
keith whaley
