Until the 2000s vacuum tubes practically ruled the roost. Even if they had surrendered practically fully to semiconductor technology like integrated circuits, there was no escaping them in everything from displays to video cameras. Until CMOS sensor technology became practical, proper video cameras used video camera tubes and well into the 2000s you’d generally scoff at those newfangled LC displays as they couldn’t capture the image quality of a decent CRT TV or monitor.
For a while it seemed that LCDs might indeed be just a flash in the pan, as it saw itself competing not just with old-school CRTs, but also its purported successors in the form of SED and FED in particular, while plasma TVs made home cinema go nuts for a long while with sizes, fast response times and black levels worth their high sale prices.
We all know now that LCDs survived, along with the newcomer in OLED displays, but despite this CRTs do not feel like something we truly left behind. Along with a retro computing revival, there’s an increasing level of interest in old-school CRTs to the point where people are actively prowling for used CRTs and the discontent with LCDs and OLED is clear with people longing for futuristic technologies like MicroLED and QD displays to fix all that’s wrong with today’s displays.
Could the return of CRTs be nigh in some kind of format?
What We Have Lost
As anyone who was around during the change from CRT TVs to ‘flat screen’ LCD TVs can attest to, this newfangled display technology came with a lot of negatives. Sure, that 21″ LCD TV or monitor no longer required a small galaxy of space behind the display on the desk or stand, nor did it require at least two people to transport it safely, nor was the monitor on your desk the favorite crispy warm napping spot of your cat.
The negatives mostly came in the form of the terrible image quality. Although active matrix technology fixed the smearing and extreme ghosting of early LC displays at higher refresh rates, you still had multi-millisecond response times compared to the sub-millisecond response time of CRTs, absolutely no concept of blacks and often horrendous backlight bleeding and off-angle visual quality including image inverting with TN-based LCD panels. This is due to how the stack of filters that make up an LC display manipulate the light, with off-angle viewing disrupting the effect.
Meanwhile, CRTs are capable of OLED-like perfect blacks due to phosphor being self-luminous and thus requiring no backlight. This is a feat that OLED tries to replicate, but with its own range of issues and workarounds, not to mention the limited lifespan of the organic light-emitting diodes that make up its pixels, and their relatively low brightness that e.g. LG tries to compensate for with a bright white sub-pixel in their WOLED technology.
Even so, OLED displays will get dimmer much faster than the phosphor layer of CRTs, making OLED displays relatively fragile. The ongoing RTINGS longevity test is a good study case of a wide range of LCD and OLED TVs here, with the pixel and panel refresh features on OLEDs turning out to be extremely important to even out the wear.
CRTs are also capable of syncing to a range of resolutions without scaling, as CRTs do not have a native resolution, merely a maximum dot pitch for their phosphor layer beyond which details cannot be resolved any more. The change to a fixed native resolution with LCDs meant that subpixel rendering technologies like Microsoft’s ClearType became crucial.
To this day LCDs are still pretty bad at off-angle performance, meaning that you have to look at a larger LCD from pretty close to forty-five degrees from the center line to not notice color saturation and brightness shifts. While per-pixel response times have come down to more reasonable levels, much of this is due to LCD overdriving, which tries to compensate for ghosting by using higher voltages for the pixel transitions, but can lead to overshoot and a nasty corona effect, as well as reduce the panel’s lifespan.
Both OLEDs and LCDs suffer from persistence blurring even when their pixel-response times should be fast enough to keep up with a CRT’s phosphors. One current workaround is to insert a black frame (BFI) which can be done in a variety of ways, including strobing the backlight on LCDs, but this is just one of many motion blur reduction workarounds.
As noted by the Blur Busters article, some of these blur reduction approaches work better than others, with issues like strobe crosstalk generally still being present, yet hopefully not too noticeably.
In short, modern LCDs and OLED displays are still really quite bad by a number of objective metrics compared to CRTs, making it little wonder that there’s a strong hankering for something new, along with blatant nostalgia for plasma and CRT technology, flawed as they are. That said, we live in 2025 and thus do not have to be constrained by the technological limitations of 1950s pre-semiconductor vacuum tube technology.
The SED Future
One major issue with CRTs is hard to ignore, no matter how rose-tinted your nostalgia glasses are. Walking into an electronics store back in the olden days with a wall of CRT TVs on display you’re hit by both the high-pitched squeal from the high-voltage flyback converters and the depth of these absolute units. While these days you got flat panel TVs expanding into every larger display sizes, CRT TVs were always held back by the triple electron gun setup. These generate the electrons which are subsequently magnetically guided to the bit of phosphor that they’re supposed to accelerate into.
Making such CRTs flat can be done to some extent by getting creative with said guidance, but with major compromises like divergence and you’ll never get a real flat panel. This dilemma led to the concept of replacing the glass tube and small number of electron guns with semiconductor or carbon-nanotube electron emitters. Placed practically right on top of the phosphor layer, each sub-pixel could have its own miniscule electron gun this way, with the whole setup being reminiscent of plasma displays in many ways, just thinner, less power-hungry and presumably cheaper.
Canon began research on Surface-conduction Electron-Emitter Display (SED) technology in 1986 as a potential successor to CRT technology. This was joined in 1991 by a similar ‘ThinCRT’ effort that used field emission, which evolved into Sony’s FED take on the very similar SED technology. Although both display technologies are rather similar, they have a very different emitter structure, which affects the way they are integrated and operated.
Both of them have in common that they can be very thin, with the thickness determined by the thickness of the cathode plate – featuring the emitters – combined with that of the anode and the vacuum space in between. As mentioned in the review article by Fink et al. from 2007, the vacuum gap at the time was 1.7 mm for a 36″ SED-type display, with spacers inside this vacuum providing the structural support against the external atmosphere not wanting said vacuum to exist there any more.
This aspect is similar to CRTs and vacuum fluorescent displays (VFDs), though one requirement with both SED and FED is to have a much better vacuum than in CRTs due to the far smaller tolerances. While in CRTs it was accepted that the imperfect vacuum would create ions in addition to electrons, this molecule-sized issue did necessitate the integration of so-called ion traps in CRTs prior to aluminized CRT faces, but this is not an option with these new display types.
For SEDs and FEDs there is fortunately a solution to maintain a pure vacuum through the use of so-called getters, which is a reactive material that reacts with gas molecules to remove them from the vacuum gap. With all of this in place and the unit sealed, the required driving voltage for SED at the time was about 20V compared to 50-100V for FED, which is still far below the kilovolt-level driving voltage for CRTs.
A Tenuous Revival
Both the companies behind SED and Sony decided to spin down their R&D on this new take on the veritable CRT, as LCDs were surging into the market. As consumers discovered that they could now get 32+” TVs without having to check the load-bearing capacity of their floor or resorting to the debauchery of CRT (rear) projectors, the fact that LCD TVs weren’t such visual marvels was a mere trifle compared to the fact that TVs were now wall-mountable.
Even as image quality connoisseurs flocked first to plasma and then OLED displays, the exploding market for LCDs crowded out alternatives. During the 2010s you’d find CRTs discarded alongside once prized plasma TVs, either given away for practically free or scrapped by the thousands. Then came the retro gaming revival, which is currently sending the used CRT market skyrocketing, and which is leading us to ask major questions about where the display market is heading.
Although CRTs never really went away from a manufacturing point of view, it’s mostly through specialized manufacturers like Thomas Electronics who will fulfill your CRT fix, though on a strict ‘contact us for a quote’ basis. Restarting a mass-manufacturing production line for something like once super-common CRT TVs would require a major investment that so far nobody is willing to front.
Meanwhile LCD and OLED technology have hit some serious technological dead-ends, while potential non-organic LED alternatives such as microLED have trouble scaling down to practical pixel densities and yields.
There’s a chance that Sony and others can open some drawers with old ‘thin CRT’ plans, dust off some prototypes and work through the remaining R&D issues with SED and FED for potentially a pittance of what alternative, brand-new technologies like MicroLED or quantum dot displays would cost.
Will it happen? Maybe not. It’s quite possible that we’ll still be trying to fix OLED and LCDs for the next decade and beyond, while waxing nostalgically about how much more beautiful the past was, and the future could have been, if only we hadn’t bothered with those goshdarn twisting liquid crystals.
This articles is written by : Nermeen Nabil Khear Abdelmalak
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