Cold CRT Guns for Thinner CRTs

Fly writes: "According to EETimes, an Austin startup company is close to producing CRTs with cold-emission electron guns. They claim this will reduce the parts needed for electron guns as well as allow for greater control and deflection of the electron beams leading to thinner CRTs. Their technology uses older chip-manufacturing techniquest to deposit diamond tips for the guns on silicon wafers. They hope to enter the CRT market next year."

Comments

CRT are on thier way out

[pennsol]

CRT monitors no matter how small are still big, clunky, and waist energy. They also contain lead, which is banned from landfills. LCD and TFT monitors will take over the market simply because they are better for the sellers as for the buyers, Smaller size cheaper to store, cheaper to ship. IMHO this company has a few merits but is beating a dead horse.

Re:CRT are on thier way out

[ewieling]

LCDs will replace CRTs when they are *cheaper to buy*.

--Eric

Re:CRT are on thier way out

[shepd]

>They also contain lead, which is banned from landfills

Not everywhere. I threw out some old TVs at the local landfill just a short while ago.

I guess the environmentalists gave up when a scientist explained to them how difficult it is for lead to leach out of glass...

If this were actually dangerous you'd see "Tell your kids: don't lick the TV screen" warnings near the tube of the monitor.

>CRT monitors no matter how small are still big, clunky, and waist energy.

Agreed.

> LCD and TFT monitors will take over the market simply because they are better for the sellers as for the buyers, Smaller size cheaper to store, cheaper to ship. IMHO this company has a few merits but is beating a dead horse.

You forget the merits of a CRT:

- Better saturation
- Closer colour tolerance
- Adjustable colour temperature
- Clearer picture
- Better resolution flexibility
- Better contrast
- Better brightness
- Faster response time
- Simple manufacturing
- Consistent quality - No "dead pixels"
- Very high refresh rates making them perfect for 3d shutter glasses
- Cheaper to fix
- No backlight to wear out (no, don't point out the irony)
- No ghosting
- Free antialiasing

All at a much, much lower price than LCDs.

I don't agree they are better for all buyers, just those forced to buy a 2' x 3' desk for their computer. ;)

As far as better for the sellers, other than the weight difference, I don't see how. Normally customers want cheaper and better. Weight and size are often only a concern when the buyer has made a poor choice in purchasing a desk.

These screens are really cool.

[tempmpi]

I have reed an article an year ago about these screens, if they get them to work they should be really cool.
They have almost all advantages of TFTs but have also almost all advantages of CRTs. They are very flat like a TFT, but have no problems with the viewing angle, smearing or bad color display. They need more power than a TFT so they shouldn't be suitable as a replacement of a laptop tft. They also shouldn't have any pixel faults because for every pixel there are many nano electron guns, so if one of these breaks down it doesn't matter. They should be cheaper to produce than a TFT because the process is more fault tolerant.
One of the biggest problems in the development of these things is that there isn't that much room between the electron emiter and the phosphorus, because of that they couldn't speedup the electron to the same speeds they get in a normal CRT and need to find new low-energy phosphoruses.

Lower Cost...Higher Quality

[peterdaly]

While it may be lower cost (for the gun) and higher quality, I bet the first ones we see will be more expensive. I've got a Sony Trinitron 21" in front of my face right now. I also have a Dell Laptop whos LCD can do 1600x1200. The SOny monitor pales in comparison. The monitor (and the one I previously used at work) have not done great things for my eyes, due to their slight bluring at super high resolutions. My eyesight has improved since I started using primarily my LCD/Laptop. It would be nice to see what kind of quality gain is possible with this. I would be willing to upgrade my hot 21" to a cold 21" if the sharpness is much better.

This sounds like a cool technology.

-Pete

yupeee yahoo hoorray

[atari2600]

You guys mean that i will be actually able to carry that 21in monitor all by myself - hoorray no more asking the school bully :)

Uh Oh, Staffed with Zenith employees

[Average_Joe_Sixpack]

Extreme Devices received what Kalar called "a godsend" when LG Electronics decided to close the former Zenith CRT manufacturing facility in Melrose Park, Ill., in October 1998, the same time that Extreme Devices was staffing up.

We can expect displays that will be encased in a big wood console.

almost makes flat screen technology easier

[dkemist]

A cold electron gun has some other benefits as well. Historically, the biggest problem with making monitor screens truly flat (no warping at the corners) was that the front material needs to be incredibly strong. Screens were rounded slightly to keep them from breaking due to the forces of the vacuum behind them. As screens grew larger and the depth of the monitor increased (in order to let the electron gun get the necessary width) screens had to be stronger. The premium for flat screens is still a couple hundred dollars more than their conventional counterparts.

By having a cold electron gun that allows wider dispersion angles, you can reduce the depth of the monitor, and thereby reduce the strength required from the front screen material.

Re:almost makes flat screen technology easier

[sjames]

This won't have much effect on the face of the tube. It still has to have the same surface area acted on by the external air pressure.

However, since the cold emission guns can work at greater deflection, the tube can be shorter, so the sides of the tube benefit from a reduced surface area and a shorter span..

The gun itself should be smaller since it won't need a bulky heater.

A big benefit comes from not having to power the heaters. While still requiring more energy than LCD displays, it's an improvement.

Given the less complex assembly (15 rather than 35 parts), reduced materials cost, and simplified and smaller power supply, it may be possable to produce monitors based on this technology for about the price of a conventional CRT (once retooling costs are covered).

Since this CRT will have some of the advantages of LCD (only to a lesser degree) over conventional CRT, it will apply more competitive pressure to LCD and the not yet here LED display developers.

Even if vastly improved and cheap LCD and LED screens come out tomorrow (hah!), the company will be OK. The cold emission technology still has applications for devices in high radiation environments AND military hardware than must withstand EMP. It might even shift the balance back to tubes (from power transistors) in some high power applications.

Multiple Guns in CRT's

[PoiBoy]

From the article I gathered that these electron guns are really a type of semiconductor, meaning that they can be controlled rather precisely.

That got me thinking. Currently, all CRT's have one set of electron guns at the center of the screen. Would it be possible to partition the screen into, say, four areas, each of which is painted by it's own set of guns.

This would have many advantages. Displays could be thinner, larger screens with higher resolution could be made, and (possibly) less energy would be required since the electrons from the guns would not have to fly nearly as far.

It seems the only tricky part would be getting the borders of adjacent areas to line up properly.

Re:Multiple Guns in CRT's

[Yarn]

Interesting idea.

However, the electronics to drive it would not be simple. Currently we have 3 fairly high frequency signals, one for each gun (red, green and blue). For this idea you'd need a set of three signals for each separate gun. Assuming you split into 4 subdisplays, you'd need 12 signals (plus the various sync and other control channels). I don't think a common-or-garden graphics card is going to do that very well. Better to do it within the monitor, I'd guess it'd increase the price by about $100.

Now, the alignment. Not as hard as you imagine; at least all the parts are within one enclosure. The display could auto-calibrate by aligning signals off the edge of the viewable area.

Cross-talk between the different steering coils would be a far larger problem. You could either compensate for this automatically (increased electronics complexity, expensive, reliability issues) or put in some mu-metal to absorb the field (expensive, heavy)

I suggest you do a patent search, see if anyone's had this idea before. Personally, I don't think it's feasable ;)

Oh, and as for energy saving, I don't think so! Electrons lose very little energy during flight.

This could be VERY popular

[MtViewGuy]

Folks,

While the new LCD flat-panel displays are dropping in price, you still have to deal with three issues: 1) screen blurring on very fast motion (though this has gotten way better in the last year or so), 2) LCD's are optimized for one display resolution and 3) they're still fairly expensive (especially now with 19" CRT monitors now under US$200 in price).

Given the CRT monitors maintain their sharpness from 640x680 all the way up to 1600x1200 and beyond (depending on the dot pitch of the monitor) and can run at 85 Hz vertical refresh rate for true flicker-free viewing, I think they're still preferred for serious imaging processing work. The new very-low profile CRT's using this new technology will allow 17" to 21" monitors have less physical depth than even the old 14" monitors from way back, which means more room saved on your desk.

I think this company may license the technology to Samsung or LG Electronics, both of which now make excellent monitors at reasonable prices. Samsung could have a huge winner right here with high-resolution CRT monitors that have half the depth of their predecessors.

CRT has its merits over LCD

[tepes]

CRT emits light, doesn't have to worry about latency and visual memory causing ghosting (a problem, I've heard, with TFT and OLED). CRTs also handle colors better. Some of the comparisons and an overview of LCD technology are at ZDNet and ErgoDynamix

Two articles confused.

[Ungrounded Lightning]

I have reed an article an year ago about these screens, if they get them to work they should be really cool. They have almost all advantages of TFTs but have also almost all advantages of CRTs. They are very flat like a TFT ...

I think you may have two articles conflated.

This one seems to be talking about using a diamond "forest" of cold emitters to replace the heated-cathode in a conventional electron gun, then deflecting the beam in the standard fashion, leading to an ordinary rectangular-cone CRT (but with no heater and instant-on).

You seem to be referring to another approach that was to use cold-emitters (which would also benefit from this breakthrough.):

The display consisted of a (glass) honeycomb of short individual "tubes".

Each "tube" had a single emitter "spike" (substitute "small forest") at the base.

A control electrode near the emitter (maybe substitute one per emitter in the "forest") switched it on/off and modulated the beam intensity. The voltage is near the cathode's and the voltage swing is just a couple volts, so you can use conventional transistor electronics.

(You can actually use two or more electrodes to do a matrix address and beam modulation, with the voltage gradient at the emitter tip or a space charge near it performing the computation so you don't need a separate switch per-pixel.)

The beam was accellerated along the narrow channel - the front portion of which contained an accelleration electrode with a constant high voltage - similar to a normal CRT. Difference: The beam could be bounced repeatedly between the channel walls, picking up additional electrodes by secondary emission.

The beam strikes a single phosphor dot at the end of the channel.

So you end up with something that can be fabricated (except for the cathode spike and maybe the modulation electrodes) by glass molding, vapor deposition of electrode metal, and micropipette phosphor-solution placement, and driven by essentially the same chips that run an LCD plus a single, unmodulated, high-voltage supply. The tubes are very short and the honeycomb of glass separating the individual tubes also supports the front screen, so you don't need thick heavy glass to fight 15 PSI of atmospheric pressure across more than a foot of unsupported span. Pixel placement is controlled by fabrication, so there's no sensitivity to local magnetic fields, no geometry adjustment. Of course in addition to no need to heat the cathodes there's no need to power and rapidly modulate an enormous magnetic deflection field.

And this new article tells you why we don't yet have either the cold-emission conventional CRT or the honeycomb flat-panel CRT: Positive ions from any impurities in the vacuum or kicked off the target or the sides of the channel are accellerated back toward the gun, slamming into the tip(s) and rapidly eroding it. RCA had a patent on field emission vacuum tubes but didn't feel like pursuing the technology with materials research. So the whole filed languished.

One of the biggest problems in the development of these things is that there isn't that much room between the electron emiter and the phosphorus, because of that they couldn't speedup the electron to the same speeds they get in a normal CRT and need to find new low-energy phosphoruses.

Huh? Space shouldn't be an issue. The final velocity of the electron only depends on the accelleration voltage, not the length of the path. The path only needs to be long enough to prevent arc-over along the surface of the glass (or in any residual gas in the "vacuum"), and that's a fraction of an inch.

With a conventional tube the voltage gradient also has to be low enough that the electrodes don't bend out of place. But that limit would be MUCH higher with the electrodes plated onto a glass surface or supported by the walls of a pixel-wide glass honeycomb cell, rather than by mica spacers and thin copper wire.

I expect the conventional-CRT style to come out first. It's only being held back by the RCA patent that just expired. The flat-panel might take longer, due to other patents, the need to build a "wafer" the size of the screen rather than the size of an electron-gun cathode, and possibly worse problems with tip erosion due to the limited number of tips per pixel.

scarcity of engineers

[Alien54]

"Most U.S. engineers with experience in the CRT industry are retired, and finding good people in this field was very hard," Kalar said. Extreme Devices received what Kalar called "a godsend" when LG Electronics decided to close the former Zenith CRT manufacturing facility in Melrose Park, Ill., in October 1998, the same time that Extreme Devices was staffing up.

Part of this was the close down of many manufacturing sectors in the USA. Most TV makers are now non-US, or are US in name only, for example

I know of several folks who will rant at the drop of a hat on this subject alone.

Interesting sentence about patents

[tlk nnr]

Blockquoting the article:

As the RCA patents expired, scientists at Systems and Processes Engineering Corp. (SPEC), a small technology think tank here, were developing emissive tips, based on synthetic diamond and silicon carbide, that could be used in the cathodes needed for radiation-hardened, high-bandwidth radio frequency amplifiers. The U.S. Air Force funded much of the SPEC-based research, which continues at Extreme Devices as a contract research effort.

Patent application in 1974, thus no reseach until the patent has expired.
Aren't patents supposed to promote research?

Heater isn't the big power waster.

[Ungrounded Lightning]

hot CRTs waste energy ... they don't require any actual heating for operation, and I doubt (though I don't know) that they'll even get warm in operation.

The CRT's heater wastes some energy. But most of the energy consumed in a monitor is the energy dumped when the magnetic deflection field "flys back" at the end of each horizontal scan line. Some of this is recycled - into the accelleration high-voltage supply or even powering the CRT's heater - but most is just dumped as waste heat.

This is just a replacement electron gun, so it won't do anything about the deflection power waste. But see my other posting and its parent here.

Ghosting was recently solved.

[Ungrounded Lightning]

The only flatpanel displays that look as good as a CRT to me are extreamly expensive. All the ones that are of lower cost have that wacky ghosting effect, not as bad as the old dual scan LCD displays, but it's there when playing higher framerate games..

That was recently solved - by remembering the previous frame and computing a voltage that would rapidly force the liquid crystal to the correct transparency rather than feeding it the voltage that would eventuall lead to it stabilizing at the desired transparency and letting it relax to that transparency in its own sweet time. There was an article about it maybe a month ago in slashdot.

Exepct TV-rate LCDs without ghosts as soon as this gets incorporated into the driver electronics - assuming the patent holders don't sit on it.

Is this field emission (tunneling)?

[pclminion]

The actual technology they are using isn't mentioned in the article, but I have a hunch it is some form of field emission. This is the same principle used in electron microscopy. A narrow emission tip is placed in a large potential gradient (electric field), and the electrons simply tunnel out of the tip. Their secret is probably the material the tip is made of: different materials have widely different tunneling rates.

The article brings up a good point. Using thermoionic emission (as is done now) is a little outdated and almost barbaric :)

Not just for computer monitors

[martyb]

I've not seen this mentioned here yet, but from my reading of the article they are intending to use this on televisions, too.

Yes, I can see the benefits of a shorter tube on a computer monitor (I'm using a 21" monitor right now that is nearly 20 inches deep and weighs nearly 65 pounds). The shorter tube would require less (heavy) glass and less plastic framing. So, smaller and lighter would be good. Also, instant on without requiring a warming circuit is a great plus, too.

BUT, these same benefits ALSO APPLY to conventional TVs, too! My current 27 inch TV sticks well out from my wall unit and weighs so much and is so bulky, I'm not ever going to try and move it again without help. It would be nice to be able to get a larger TV that would fit into the same space, weigh less, and would also not consume power just to keep the electron gun warm for "instant-on".

Other applications: shorter CRT tubes would be an advantage in any technical instruments that have a built-in display. Think: oscilliscope, medical instruments (pulse, BP, oxygen, etc. monitors), in-dash car displays, airplane cockpit displays, etc.

Now, to drool a bit for a more personal application... combine Cold CRT Gun with HDTV!

The technology formerly known as microtip displays

[SysKoll]

SET MODE=OLD FART

Reading this article made me jump way back in time. At that time, I worked in a Big Company located in the same campus as PixTech, a startup that had a deal with Japanese display specialist Futaba to produce microtip displays in a European lab in Montpellier, France. Pixtech produced a monochrome prototype, then the price of LCD collapsed and the funding dried up. That was in 1993 or 94 if I remember correctly.

PixTech wanted to create a technology and then licence it to mass producers. They entered an agreement with Texas Instrument, but after LCDs started to be dirt cheap, the agreement collapsed.

The principle in these screens seems to be the same as the technology explained in the article. Behind each phosphorus dot (1/3 pixel roughly), a few dozens to a few hundreds cold cathode cones emit electrons and replace electron guns. The European technology was using silicon tips instead of diamond, but the principle stays the same: In an electrical field, a tip tends to concentrate charges, hence a cone easily releases electrons when negatively charged.

The beauty of the scheme is that even if the yield of the microtip fabrication is not perfect, you don't care because there are many of them behind each phophorus dot. Compare and contrast with LCD screens, where a single defective transistor will leave a permanent dead pixel.

I am a strong supporter of this technology, because it allies the advantages of CRTs with the flatness of LCDs. But I have seen several startups fail while trying to market microtip screens, so I am wondering if it's not jinxed or something...

-- SysKoll