CRT Computer Monitor to CRT TV Parts Swap

A CRT needs a neck for the electron beam gun. One manufacturer made a CRT with a bent neck but it worked poorly. Many manufacturers made a CRT with wide electron beam deflection then its neck was shorter.

audioguru said:

A CRT needs a neck for the electron beam gun. One manufacturer made a CRT with a bent neck but it worked poorly. Many manufacturers made a CRT with wide electron beam deflection then its neck was shorter.

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The best looking (picture) on a CRT monitor I designed had a curved screen and a very long CRT. The electron gun was at the center of the curve of the screen. So the distance from gun to screen is the same for any spot on the scree. This made a very simple focus circuit. The electron beam needed to be bent only slightly to reach the corner of the screen. This way it takes little energy to deflect the beam.

But no one wants a 3 foot deep monitor and many people do not want a curved screen.

With the electron gun very close to the screen, it takes much more energy to bend the beam that hard. Now the distance from gun to screen changes. To the center of the screen is a short trip while the corners is a long trip. The focus must be changed for each area of the screen. The focus voltage is a complex waveform. The electron beam is bent hard then hits the glass at a non right angle. All this makes the beam shape non round and hard to keep focused.

In the case of the bent neck Sony tube the top and bottom of the screen are a different distance from gun. It was very hard to deal with and the picture was only good for a "pocket TV".

I remember reading, around the time that HDTV was first available and before LCD and Plasma displays were well developed, about the development of a flat-panel CRT.
It had a very small needle-point cold cathode emitter for each pixel, the was very close to it associated colored phosphor on the front panel.
Sounded like an interesting idea, but obviously, it never went anywhere.
Not sure how they planned to modulate the current for each pixel -- perhaps a small grid between the cathode and screen.
I think they had small glass pillars between the front and back of the panel to prevent its collapse from the vacuum inside.

ciao303 said:

Did UltraSlim CRTs ever gain popularity??

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There never were any - although I suppose it depends on what you mean by 'ultra slim'?.

As it was, the move from 90 degree deflection to 110 degree introduced enough problems

ciao303 said:

Did UltraSlim CRTs ever gain popularity??

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Yes, but those were the last major CRT design projects. At that time many if not most CRT professionals were already retiring or looking for new jobs.

crutschow said:

I remember reading, around the time that HDTV was first available and before LCD and Plasma displays were well developed, about the development of a flat-panel CRT.
It had a very small needle-point cold cathode emitter for each pixel, the was very close to it associated colored phosphor on the front panel.
Sounded like an interesting idea, but obviously, it never went anywhere.
Not sure how they planned to modulate the current for each pixel -- perhaps a small grid between the cathode and screen.
I think they had small glass pillars between the front and back of the panel to prevent its collapse from the vacuum inside.

Click to expand...

Field Emission Displays were all the rage for three or four years. Candescent Technologies had a high profile in the United States but failed to attract the investment needed to build their factory. Come to think a few companies had demonstration units but nobody seems to have made it to production. One industry analyst and consultant, Fredrick Kahn, pointed out that color display LCDs had about a 10 year head start and huge investments in manufacturing technology by then and the new displays just could not catch up.

The inside of the display was made of precision shrink ceramic. There were little posts positioned under the faceplate to support it. They showed up in the image as tiny dark spots. Under each microtip was resistive material that acted like resistors put in series with LEDs connected in parallel so that the tips would tend to share current. Above the array of microtips was a plate that contained apertures where the pixels (or sub-pixels) were located and putting a small negative charge on the metal surrounding the apertures would cut off the beam current, just as on conventional CRTs.