21 Sep
2014
21 Sep
'14
1:51 p.m.
On 09/20/2014 03:12 PM, Tony Duell wrote:
What do you think the purpose of the outer faceplace is? The CRT
manufactuers seem to think it's necessary for safety (as in 'Do not attemp
to remove it') and it's boned all over the screen area, not just at the
edges. To me that certainly suggests a 'laminated glass' type of thing.
It doesn't take much to keep the glass from flying. I rememebr my father
(who as I said worked on high vacuum systems) demostrating what happens
if you evacuate a too-tin-glass vessel (behind a safety screen). Boom,
and glass everywhere. Then he covered an indentical vessel in selotape
andpumped it doen. Whomp and the glass stayed together, albeit totally
shattered.
If so, than failing aadhesive (as in 'fungus') could be a safety risk itself
I am not so sure. I don't think that 2 sheets
of normal glass would be as
safe as laminated glass for a car windscreen, for example. I don't know
if the outer faceplate is enoguh to stop the fragments of CRT, and I do
not intend to find out by experiment. I do feel that the adhesive
between the 2 layers does help to keep the bits together if the CRT
implodes, though.
I'm sure that it's certainly not a shatter guard. However, if you looked at US televisions made before about 1956,
you'd see that the
plain faceplate CRT had a sheet of plate glass installed in front of it.
Some of these got as large as 21", but my family had a 7" 1950 Philco
that had that sheet of glass also.
Same in the UK. Older sets had laminaged glass protection screens (they
were not jsut plain galss), later ones had a moulded perspex cover aound
the front of the CRT.
Given that such sheilkds were fitted in times when people were less
safety-concious, and less likely to sue if there was an accidnet, I think
the manufacturers realised just hoiw dangerous an imloding CRT could be.
-tony