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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?

Reply to
dfarr --at-- comcast --dot-- n
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No.

Reply to
Ken

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

Reply to
John Larkin

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

Reply to
Ken

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

Reply to
Ken

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

Reply to
John Larkin

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

Cheers

PeteS

Reply to
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.

Reply to
linnix

Oh! Here the specification for my old CRT

formatting link

Reply to
Ken

2/3 is a fraction. 
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Bye.
   Jasen
Reply to
Jasen Betts

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