flyback efficiency

I'm wondering about the cost and power consumption of televisions and
CRTs. I don't have enough knowledge of electronics to answer this
question for myself.

Does the process of moving the beam rapidly across the screen to begin
a new scan line require a lot of power? Raster plotters draw in both
directions to save time and total plotter head motion. Would there be
any advantage to driving a CRT so half the scan lines were drawn right
to left and half were drawn left to right, alternating directions on
each scan line?

I'm guessing one advantage of drawing all the lines in the same
direction is synchronization, so what is the cost for doing it this
way? Are there alternative ways to synch the lines on an analog
display?

 

No.

 

Yes. The horizontal deflection system of a CRT uses far more power
than the vertical, even for a 1:1 aspect ratio system. The horizontal
deflection coil has to be low inductance, so needs lost od deflection
current, and has to have very high voltages applied to it to slew the
beam rapidly. All that takes a lot of power.

But an LCD uses a fraction of the power of a CRT.

Frame-sequential LED backlighting would be even better, if the LCDs
could be made fast enough.

John

 

But it's not "a lot of power".

 

"fraction" ???
My 19" CRT monitor use 75W
A normal 19" LCD monitor about 40-50W.

 

Tha ratio is typically 3:1 for small (15") screens, approaching 2:1
for larger screens. 1/3 and 1/2 are both fractions. Look it up.

John

 

The fraction is larger for smaller devices (common in HUDs and
MultiFunction displays in aircraft).

Cheers

PeteS

 

You must have a very good CRT, if this is correct. I have two 17" CRT
rated 1.5A and 2.5A (seems too high) @110V. I believe the actual
usages are more like 150W to 200W.

 

Oh!
Here the specification for my old CRT http://tekniken.se/misc/109b50.pdf

 

2/3 is a fraction.