Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

From time to time I hear about companies experimenting with ways to make
thinner CRTs. Is anybody selling PC monitors that are CRT based and a good
bit thinner than your average CRT?

Thanks,
Tom

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"TC2" <neinspam.tomcantlon@vispath.com> wrote:

>From time to time I hear about companies experimenting with ways to make
>thinner CRTs. Is anybody selling PC monitors that are CRT based and a good
>bit thinner than your average CRT?

Don't think so. Making the CRT shorter means that the deflection
angle of the electron beam, as it sweeps across the face of the tube,
must increase. The larger this angle, the more difficult it is to
keep the spot circular and focused as it strikes the phosphor face of
the tube. Using dynamic beam-shape corrections helps, up to a point.

Most computer monitor CRT's have a horizontal deflection angle of 90
degrees (+/- 45 degrees off center). Note that some of the length of
the CRT is the actual electron gun part of the tube, which is going to
be X length no matter what, so, if one wanted to, say, cut the length
of the CRT in half, you may have to bring the "business end" of the
electron gun 3 times as close to the phosphor face, which jacks your
deflection angle from 90 degrees to 143 degrees. Not at all easy to
deal with, and you're still left with something many times thicker
than an LCD.

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

chrisv wrote:
> "TC2" <neinspam.tomcantlon@vispath.com> wrote:
>
>> From time to time I hear about companies experimenting with ways to
>> make thinner CRTs. Is anybody selling PC monitors that are CRT based
>> and a good bit thinner than your average CRT?
>
> Don't think so. Making the CRT shorter means that the deflection
> angle of the electron beam, as it sweeps across the face of the tube,
> must increase. The larger this angle, the more difficult it is to
> keep the spot circular and focused as it strikes the phosphor face of
> the tube. Using dynamic beam-shape corrections helps, up to a point.

Possibly a variation of the back-projection tv's might work in this case?
You could make the CRT guns occupy the the lower part of the case, while the
keeping a fairly slim upper part of the body?

Yousuf Khan

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"Yousuf Khan" <bbbl67@ezrs.com> wrote:

>chrisv wrote:
>> "TC2" <neinspam.tomcantlon@vispath.com> wrote:
>>
>>> From time to time I hear about companies experimenting with ways to
>>> make thinner CRTs. Is anybody selling PC monitors that are CRT based
>>> and a good bit thinner than your average CRT?
>>
>> Don't think so. Making the CRT shorter means that the deflection
>> angle of the electron beam, as it sweeps across the face of the tube,
>> must increase. The larger this angle, the more difficult it is to
>> keep the spot circular and focused as it strikes the phosphor face of
>> the tube. Using dynamic beam-shape corrections helps, up to a point.
>
>Possibly a variation of the back-projection tv's might work in this case?
>You could make the CRT guns occupy the the lower part of the case, while the
>keeping a fairly slim upper part of the body?

I know Sony made a Watchman that had a radically-bent CRT in it, but
that's obsolete technology now, with the LCD's available. That design
had a lot of drawbacks. It was much flatter than usual, but also much
"taller". And that radical tube made getting a precise image so
difficult as to be totally inappropriate for computer monitor
applications.

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"Yousuf Khan" <bbbl67@ezrs.com> wrote in message
news:k1hOc.1317265$Ar.299376@twister01.bloor.is.net.cable.rogers.com...
> Possibly a variation of the back-projection tv's might work in this case?
> You could make the CRT guns occupy the the lower part of the case, while
the
> keeping a fairly slim upper part of the body?

But that's not quite how rear-projection TVs work; in a CRT-based
RPTV, there are actually three complete CRTs (of a very specialized
design; one for red, green, and blue), each with their own
deflection yoke, etc., and the resulting images are simply projected
optically to the screen. Electron beams aren't that easy to
manipulate.

What MAY ultimately result in a more "CRT-like" display is
a technology known as the "field-emission display," or "FED,"
also sometimes called "cold-cathode CRTs." Imagine a
flat-panel display, something like an LCD, but where the
individual subpixels all have electron emitters behind them,
driving very CRT-like phosphors on the screen. So far, no
one has managed to produce a commercially-viable FED in
monitor or TV sizes, but some are still trying. Of course, such
a display will still be a fixed-format device (i.e., distinct physical
pixels on the screen), just as an LCD is.

Bob M.

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Bob Myers wrote:
> "Yousuf Khan" <bbbl67@ezrs.com> wrote in message
> news:k1hOc.1317265$Ar.299376@twister01.bloor.is.net.cable.rogers.com...
>> Possibly a variation of the back-projection tv's might work in this
>> case? You could make the CRT guns occupy the the lower part of the
>> case, while the keeping a fairly slim upper part of the body?
>
> But that's not quite how rear-projection TVs work; in a CRT-based
> RPTV, there are actually three complete CRTs (of a very specialized
> design; one for red, green, and blue), each with their own
> deflection yoke, etc., and the resulting images are simply projected
> optically to the screen. Electron beams aren't that easy to
> manipulate.

No, I realize that they aren't manipulating the electron beams themselves,
it's just the optical images being deflected. But it's also not the point,
the original poster was asking about some way of getting a thin screen using
CRT technology, but he never mentioned whether he wanted to watch the images
directly or indirectly through projection. Since that was never mentioned
specifically, therefore I suggested a back projection system.

> What MAY ultimately result in a more "CRT-like" display is
> a technology known as the "field-emission display," or "FED,"
> also sometimes called "cold-cathode CRTs." Imagine a
> flat-panel display, something like an LCD, but where the
> individual subpixels all have electron emitters behind them,
> driving very CRT-like phosphors on the screen. So far, no
> one has managed to produce a commercially-viable FED in
> monitor or TV sizes, but some are still trying. Of course, such
> a display will still be a fixed-format device (i.e., distinct physical
> pixels on the screen), just as an LCD is.

Which would be an interesting future for directly visible CRT systems, and
it would fulfill the original poster's requirement too -- whenever it
becomes practical.

Yousuf Khan

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

TC2 wrote:

> From time to time I hear about companies experimenting with ways to make
> thinner CRTs. Is anybody selling PC monitors that are CRT based and a good
> bit thinner than your average CRT?

Some years ago I saw attempts in that direction. The manufacturers
dubbes them 'short-neck' CRTs.
The concerns about the image quality are probably valid. And I doubt
that there is any more research since CRTs will never be as flat as TFTs.

André

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Actually both Sony and Matsushita (AKA Panasonic in USA) did have viewable
samples of "thin CRT's". I
believe NV Philips labs were also at least closely watching the technology
possibilities. But the commercial
value of the "thin CRT" never seemed to materialize. Development of Plasma
and LCD flat displays with
large enough format for TV applications has likely cause most of the thin
CRT research to wither away. One
major factor was that monochrome displays could be made (as Sony did) but
extending to color was entirely
another problem.

The one advantage of Plasma is that it uses phosphor, like a CRT, so may
have similar luminance and viewing
angle performance. At least colors and luminance don't change nearly as
drastically with Plasma as with direct
view LCD's. Plasma's disadvantage is still its luminous efficiency - just go
to a demo in a store, put your hand
near the face, and feel the radiated heat. These guys are power hungry.

Light valve technology (like TI's DMD) is the up & coming candidate for
projection types of systems, now that
the signal management electronics are more within economic reach. They are
quite common now in the desktop
presentation projectors market.

FED's seem to experience "peak & valley" kinds of acceptance. The theory
sounds great, but putting it into practice
has consumed a lot of venture capital, and there are few products to show
for all the expense.

Just my opinion - I don't speak for anybody!

NGA
--

"Yousuf Khan" <bbbl67@ezrs.com> wrote in message
news:VsvOc.74$Quq.56@news04.bloor.is.net.cable.rogers.com...
> Bob Myers wrote:
> > "Yousuf Khan" <bbbl67@ezrs.com> wrote in message
> > news:k1hOc.1317265$Ar.299376@twister01.bloor.is.net.cable.rogers.com...
> >> Possibly a variation of the back-projection tv's might work in this
> >> case? You could make the CRT guns occupy the the lower part of the
> >> case, while the keeping a fairly slim upper part of the body?
> >
> > But that's not quite how rear-projection TVs work; in a CRT-based
> > RPTV, there are actually three complete CRTs (of a very specialized
> > design; one for red, green, and blue), each with their own
> > deflection yoke, etc., and the resulting images are simply projected
> > optically to the screen. Electron beams aren't that easy to
> > manipulate.
>
> No, I realize that they aren't manipulating the electron beams themselves,
> it's just the optical images being deflected. But it's also not the point,
> the original poster was asking about some way of getting a thin screen
using
> CRT technology, but he never mentioned whether he wanted to watch the
images
> directly or indirectly through projection. Since that was never mentioned
> specifically, therefore I suggested a back projection system.
>
> > What MAY ultimately result in a more "CRT-like" display is
> > a technology known as the "field-emission display," or "FED,"
> > also sometimes called "cold-cathode CRTs." Imagine a
> > flat-panel display, something like an LCD, but where the
> > individual subpixels all have electron emitters behind them,
> > driving very CRT-like phosphors on the screen. So far, no
> > one has managed to produce a commercially-viable FED in
> > monitor or TV sizes, but some are still trying. Of course, such
> > a display will still be a fixed-format device (i.e., distinct physical
> > pixels on the screen), just as an LCD is.
>
> Which would be an interesting future for directly visible CRT systems, and
> it would fulfill the original poster's requirement too -- whenever it
> becomes practical.
>
> Yousuf Khan
>
>