Re: Glass Cockpit Video Rates

From:         edswafford@ins.infonet.net
Organization: INS Info Services, Des Moines, IA USA
Date:         07 Dec 94 01:15:45 
References:   1 2 3 4
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>
>1.  These displays are either raster scan, vector scan or a
>combination of the two. Raster scan is employed in your PC monitor;
>vector scan (or "stroke" displays)

I missed the start of this thread.  It appears there is some question
about the type of displays used on commercial aircraft.  For the past ten,
years I've worked as a software engineer on cockpit displays.

The displays used on the 737, 757 and 767 are all basically the same.
They are all stroke machines.  Any raster you think you may see is 
really just high speed stroke filling a predefined ares ising a pseudo         
raster pattern.  My understanding the reason stroke is used over
raster is for brightness reasons.  In high sunlight conditions, a raster
display will washout long before a stroke display will.  I've been told by
hardware types, this is due mainly to energy constraints.  i.e. there is
only so much energy that can be shot on the screen, and if you can concentrate
this energy to a few line instead of the entire screen those line will be
much brighter.  The refresh rate for these displays is typically 70Hz.  I
don't know much about the material used in the tubes, but I've been told
these tubes are MUCH better than any pc/workstation monitor.        

Ed Swafford