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Dual Cathode Ray Tube
so that you can have two resolutions at the same time, in different portions of the screen. | |
Its basically a cathode ray tube that has two (or possibly more) cathode rays inside of it. This would allow for multiple resolutions at different locations on the screen.
I don't know if this in would work exactly the way I would like it to.
Someone could have thought if this before, but maybe
it wouldn't work for some reason.
I haven't thought of how to control it. I think it would need a special video card or something. And probably some special software.
Cathode ray tube
http://en.wikipedia...ki/Cathode_ray_tube
[BJS, Jul 19 2007]
How CRT Monitors Work
http://computer.how...ks.com/monitor7.htm
[BJS, Jul 19 2007]
Sony Trinitron CRT
http://www.sony.net/Fun/SH/1-25/h2.html
Sony History [BJS, Jul 19 2007]
Trinitron
http://en.wikipedia.org/wiki/Trinitron
"...was a three cathode single electron gun arrangement," [BJS, Jul 19 2007]
Dual beam oscilloscope
http://en.wikipedia...l_beam_oscilloscope
Tektronix 556 (for example) [csea, Jul 19 2007]
Electrostatic Deflection
http://en.wikipedia...rostatic_deflection
Charged particles in an electric field [csea, Jul 20 2007]
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I don't think it would work. A CRT''s electron beam is governed by an electro-magnetic field. You know the coil at the base of the gun? That's an electromagnet. If you had two guns you would need two electromagnets also. The electromagnetic fields would probably interfer with each other, distorting the electron beam. |
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<vague no doubt inaccurate memory of marketing hype> |
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Didn't the Sony Trinitron CRT monitors have 3 sources - one red, one green, and one blue? |
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I think most CRT computer monitors have that technology now. |
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Dual beam CRTs were used extensively in the '60s, when I was a young lad. [link] The deflection was electrostatic, rather than electromagnetic. |
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I think that the Dual beam oscilloscope, is split into two separate sections (top half and bottom half?), which don't cross each other or change sizes and stuff (which is what I want). |
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//The beam is deflected by large electromagnets located on the four sides of the CRT. It would be impossible to have independent beams because you would need two sets of magnets and they would simply interfere with the magnetic fields of each other. // |
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[BrauBeaton],
The beams can also be deflected by electrostatic plates. See [link] on dual-beam oscilliscopes. IIRC, the two (or exotically, up to 4) guns exist in the base of the CRT, and are deflected independently (though two beams may share common horizontal plates, depending on the application / cost. |
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[BJS]The beams can quite easily cross each other without interference, just as beams of light do. |
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I think the picture-in-picture feature already does this. Also the magnify feature in Windows. |
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I'm gonna go hit the Picture-in-Picture button on my TV remote and vote this "What's the point?" |
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//I'm gonna go hit the Picture-in-Picture button on my TV remote and vote this "What's the point?"// Because the resolution of the PiP will be the same as the rest of the screen.
If you had a second beam, it could be a higher resolution than the rest of the screen, though I suspect this wouldn't work on a normal colour tube, but may well work on a mono one with a continuous phosphor coating. |
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I was thinking of using CRTs mostly because of their high resolution capabilities. |
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CRT monitors have a native resolution just like LCD or plasma. The resolution of a CRT is determined by its shadow mask, which determines when the beams hit the phosphor. Because of this you will need to scan convert to achieve your resolution changes whatever display you are using. The only way you can really do what you want properly is to use a display with stupidly high resolution to the point where you can fit in two images at their native resolution anyway, and even then any scaling will involve scan convertion (which entails loss of resolution). |
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//The resolution of a CRT is determined by its shadow mask//
[wags] But mono screens don't have a shadow mask. If you were to use an LCD RGB shutter in front of a mono CRT and successively displayed RGB frames, you could get a much higher resolution than a colour CRT.
Such displays were quite common in specialist applications like scopes and logic analysers from Tektronix in the early 1990s.
There was even a Mitsubishi camcorder that used a simple mechanical colour wheel and a mono tube viewfinder to give a very satisfactory high res display. |
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That's clever, but you still need alternating lines of coloured phosphor which will determine resolution, no? |
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//but you still need alternating lines of coloured phosphor which will determine resolution, no?//
No, the LCD shutters/filters worked across the whole screen. Don't ask me how, but it worked - we used some of them as persiscope displays in simulators. The only downside was that you had to triple the frame rate. |
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Can you find a link to that? |
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Google "Tektronix NuColor".
Quite often used with 1 inch CRTs to provide colour head-mounted displays, but also on test gear up to around 7inch displays.
I can't find a reference to the Mitsubishi camcorder, but it used a tiny motor-driven lampshade-shaped (conic frustum) colour-wheel mounted at a slight angle to the viewfinder assembly, and you looked down the wide end at the monochrome CRT.
At the time (early to mid 90s), it was streets ahead of small LCD viewfinders in terms of both colour fidelity and resolution. |
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Well I still don't understand how they've done it, but it means that [BJS]'s idea will at least work in theory. |
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I suspect the dual beam devices probably had the two sets of vertical deflection plates mounted above/below each other. I'll look for a better reference. |
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[BrauBeaton], see [link]. |
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Yes, the electon beam is deflected towards / away from a pair of plates having opposite charge. This generally takes a fairly high voltage difference (+/-). |
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In a dual beam, single timebase setup, the deflection plates might look like: |
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.__ __.
|__ __ |
where the vertical pair of plates (left/right) cause horizontal scan, and the horizontal pairs of plates (top/bottom) can independently deflect separate beams. |
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In a real implementation, the H / V plates would be at different distances from the cathode(s). [AWL] has it, except the pairs of V deflection plates are "beside" each other rather than above / below. |
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//However, this concept could work on modern LED/SED displays because they use digital information to define the action of the fully independent pixels//
No, it wouldn't - they would give exactly the same resolution as the rest of the screen, just like the PinP solution suggested above - the resolution is defined by the (fixed) pixel pitch.
With a monochrome CRT, the resolution is defined by the size of the electron beam spot. |
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CRT's are old
This is like over clocking a 386
You might be able to do it but what's the point |
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I don't know what you mean by that. |
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