News item: Slimline CRT TVs?

[redaction]

CRT TVs may not be as popular as plasma or LCD but development isn't dead yet, by the looks of things:

New York Times - Picture Tube TV's Try a Slimmer Strategy

[Nick_UK]

This is old news - Samsung's announcement was posted (by me) about a week ago in the HDTV section.

[Laurel&Hardy]

And you were two months behind with that news...

On the 11th november 2004 this was posted here in the TV section...

Samsung VixLim CRT the depth of Plasma'ish

So don't be so demeaning of others posting stuff that is news to them.

[redaction]

Hello. No offence taken by any post. I relised it wouldn't be news to many, but thought it was interesting as I'd not encountered anything on the CRT front that interested and wondered about the technical side to making CRTs more slimlined. For some it will be news for sure - anyone have any more info on how come it's taken them so long to reduce the size/weight of CRTs then?

[Laurel&Hardy]

Well Samsung have been a bit light on anything except how good they think it is. But the technical side of it is indeed very interesting. Like the size DY coil to effect good beam focus on a 125 degree tube. The physics of the tube are also interesting too, becuase the bulb glass (this is glued to the front glass during assembly) is almost parallel to the front of the tube - this requires huge mechanical strength once the tube is evacuated and sealed. Also, the focal length on a tube this shallow is a nightmare - the change from centre to corner is considerable and will require some very clever electronics to overcome. I think it is a very interesting development indeed but I won't be buying. After owning a 51" I can't watch a 32" in a large room now - it looks like a portable!

If CRT's were still curved front then it would be relatively light because the curve was for two reasons - first to ensure perfect focal length and second it aids the mechanical integrity of the tube when it's evacuated. Flat tubes have a very thick front glass in order to stop them imploding once the air is removed. This adds to the mass of the tube and the bigger the tube is the thicker the glass has to be in order to stop it imploding. Physically it is almost impossible to make them much lighter without compromising the mechanical integrity of the structure - spontaneous implosions in the cusomer's house would spell financial ruin for any company that tried. So they will always remain heavy and, in the case of the Vixlim (the name Samsung have given this tube), the physics dictate that even more glass is required to ensure it doesnt implode.

Here's the website for this tube...

http://www.vixlim.com/contents/promotion/index.html

[red16v]

May I add the following points to think about ? when I looked through the cabinet into the back of my Toshiba 32ZP48 I was surprised that in actual fact the crt isn't that deep - I couldn't help but wonder why Toshiba had chosen to make the cabinet so big when it seemed to me that they could make it considerably smaller (even taking issues like heat/air circulation etc into account). It then struck me that the audio 'woofer' is built into the rear of the cabinet (somewhere) and as any hi-fi 'buff' will tell you a deep bass speaker needs to be surrunded by a large volume of enclosed air with a controlled 'air leak' to the outside world. I wonder then if this is a limiting factor in the design of my particular model ? I suppose they could have supplied an external 'woofer' - like any after market home cinema system but that would have defeated their marketing idea?

As regards to large flat screen crts - if you look carefully at the crt when it's switched then you will see that the curved structure that 'Laurel&Hardy' refers to is actually on the inside of the glass not the exterior, so, there is still the conventional increase in mechanical strength of a conventional curved crt. But nonetheless as 'L&H' points out the glass still has to be thicker to really give the overall strength required. Regards, yt.

[Nick_UK]

Originally Posted by Laurel&Hardy

.....Physically it is almost impossible to make them much lighter without compromising the mechanical integrity of the structure - spontaneous implosions in the cusomer's house would spell financial ruin for any company that tried. So they will always remain heavy and, in the case of the Vixlim (the name Samsung have given this tube), the physics dictate that even more glass is required to ensure it doesnt implode......

I think you are being a little over-dramatic. If you have been around TV's as long as I have, you will know that back in the 1950's, tube implosions were a very common event. So much so that TV's had a thorough "soak test" before leaving the factory, and when they arrived at the dealers they had another soak test. Even then, the odd dud CRT would still get through, and my sister still has the scars on her knee to prove it, because our TV imploded. Nobody "went bust".

Fortunately the technologies have all moved on considerably in the last 50 years. Bonding the front glass has been routine for the last 40 years, and the adhesive is stronger than the glass itself. Also, problems caused by the CRT geometry which were very difficult to solve in the 1950's can be completely removed by a few electronics chips in the 21st century. Modern PC screens show just how good CRT's can be if designed and set up properly. A good CRT monitor can still knock spots off any plasma or LCD screen, especially at hi-definition.

[Laurel&Hardy]

The profile of compaines is much higher now than it was even 20 years ago and an event such as a tube implosion, especially if it hurt a child, would be taken very seriously I think, so I don't think it is being over dramatic. You have to remember that if it is a glass defect then many tubes could be suspect since they are all manufactured in large batches, and the company would now be compelled to investigate why this happened. The potential cost of this, especially if it is found to be a tube defect, could be huge.

This new slimline tube is not an easy shape to make mechanically sound when it is evacuated, so I would not mind betting that Samsung suffered a few implosions before getting the structural integrity right. But this is all part and parcel of R&D, so since they are marketing it I'd say that this problem has been solved.

[red16v]

Hi 'Nick UK'. Yes, PC crts are very good especially in terms of geometry but remember the screen sizes are usually limited (I don't think I've personally seen a PC CRT greater than 19" although I know they can be larger) Also, and this is very important, for a given screen size PC crts are actually much longer than the equivalent tv crt - precisely to limit beam deflection angles and therefore improve convergence and mimimise the need for dynamic focus. Regards, yt.

[Laurel&Hardy]

Largest I ever saw was a Sony GDM W900 24" wide. It was a colossal £1300!!! It was very nice though, but I simply couldn't afford to buy it. Now it is discontinued. Biggest size now is the 22" Diamondtron tube, I don't think anybody makes a bigger one now because I doubt they'd be able to make any money out of it.