Other phrases for search engine and GPT: Can a CRT even just theoretically last 1,000,000 hours using currently known materials? Is it even theoretically possible for a CRT to last 1,000,000 hours?

From the following source, I could find that high-quality cathode-ray-tube displays (whether be it for a computer monitor, television set, or oscilloscope) have a design lifespan of 30,000-50,000 hours of cumulative operation. I could also find that the design lifespan is limited to that because the physics of the operating mechanism with the material used for the electron gun dictates that. Because the material used is already the most-durable that can emit electrons, that makes it a fundamental limit to electron guns using thermionic emission using currently commercially available materials. Thermionic emission is a sacrificial process in which the removal of electrons causes the atoms to become ionized, thereby ejecting from the filament, thereby causing the atoms overall to sputter from the electron gun. So, is it even possible for a picture tube to last one million hours without a complete rebuild if terrible picture quality (unreadably blurry and only as bright as moonlight reflected off of water) is ignored, or will the thermionic electron gun completely fail (stop emitting electrons entirely from being an open circuit, informally known as popping or burning out) long before then? I know that field-emission guns exist, which can theoretically last forever because the electrons are just recirculated, which is why I specifically mentioned thermionic. No commercially available CRT has ever been made with an FEG, so they don't apply anyway.

https://www.eevblog.com/forum/beginners/do-cathode-ray-tubes-die/

The accuracy of that source has been verified with the following source, which states that CRTs without an extended-life cathode (i.e., a low-to-mid-quality CRT) have a time-to-half-brightness (L50) value of just 10,000-15,000 hours.

https://www.repairfaq.org/sam/crtfaq.htm

Despite the stated life expectancy, I could not find any pictures of CRT displays that are just even claimed to have over 30K hours of runtime, let alone 50K, 100K, or even 300K hours. Of course, no CRT has lasted 1000K (1M) hours as of yet because it was only just invented 120 years ago. All I have heard are anecdotes of only up to 100K hours. Here, I am referring to the picture tube only, not the driving circuit in the chassis that powers and controls the CRT. This is important because all the other components can be replaced with newly manufactured ones but not the CRT itself. That is because the very last of the CRTs in the world that can show any brightness and colour on any pixel (i.e., freely-configurable screen) have been discontinued in 2014 in India, which is nearly an entire decade ago. Even for CRTs which have a mostly non-variable screen such as attitude indicators in avionics for aircraft, even the very last manufacturer for CRTs in avionics, which was Toshiba, discontinued even replacement CRTs for existing aircraft in 2020, which probably marked the end of the CRT technology entirely. Besides for very crude screens in early oscilloscopes that did not even have grid lines, the production of CRTs cannot simply be restarted by hobbyists in a workshop. That is because just like with integrated circuits (informally called computer chips) because CRTs cannot be handmade due to the very-fine detail in combination with the extremely high precision and highly refined materials required.

https://www.airliners.net/forum/viewtopic.php?t=1460977

So, is it theoretically possible for a CRT to last a million hours? Can a CRT monitor even just in principle last 24 hours a day, 7 days a week, for 120 years continuously in settings such as security systems and control rooms? Here, I am referring to the picture tube only. For reference, 120 years for 24/7/365.2425 is 1,051,898.4 hours.

1,000,000 hours may sound crazy, but that is not for industrial equipment or for constant indicator lights on any equipment. On the other hand, high-quality equipment operating using a non-sacrificial method still routinely function well even after 100 years running 24/7/365.2425, which is 876,582 hours (approximately 875,000 hours, or 875K hours). For example, electrical transformers and overhead power lines (with ceramic or glass insulators, which do not age because the molecular repeating units, indicated by the chemical empirical formula for network covalent/ionic/metallic solids in giant covalent/ionic/metallic structures and amorphous solids, are tightly held together by strong atomic bonds) in dry climates (that rain little and have very low humidity when not raining) are still running like new after 100 years for every single second besides during the rare power outage. Early light-emitting diodes in digital clocks and status indicator lights on control panels are still functioning well after 50 years. In the UK, the BSI codes require structural components such as bridges to have a design lifespan of no less than 120 years.

In extreme examples, structural beams and posts that have been kept dry have been in continuous service for 500 years in many ancient buildings like government buildings and cathedrals, which is 4,382,910 hours. In very extreme examples, there are 2,000-year-old buildings with most of their beams and columns being original and in continuous service, which is 17,483,640 hours. The oldest known structure in 2023 is the Göbekli Tepe in Turkey, which was completed sometime between 9600 BC and 8200 BC, which makes it sometime between 10,223 and 11,623 years old. That building does not appear to have ever had a roof or even lintels/beams. That means that among the pillars that are still intact with capstones attached, the base stones have lasted for sometime between 89,612,977.86 hours (90 million hours) and 101,885,125.86 hours (102 million hours) in service carrying the full structural load of the rest of the pillar above so far.

If you have the information, please post pictures of how a CRT display that has over 30,000 and/or 50,000 hours of runtime looks like, especially the screen burn-in when turned off. Also, please post photos of how much the individual colours are faded when turned on at factory settings. I would most like to know that information for one with at least 100,000 hours of runtime, preferably 300,000. Please also state the estimated number of hours, preferably with the uncertainty error bars (plus or minus) too.

Fascinating!

I wish I had the time to give this subject the reply it deserves!

I think that 1,000,000 hours is possible, but by then the CRT would be well into a slow performance decline. It depends on what your definition of End of Life for a CRT is.

Is it when it no longer displays any visible light?

It comes down to two things:

1. How well it's made
2. How well it's driven.

Sounds familiar doesn't it?

The How well it's made includes the accuracy of the metal alloy mixing that affects the performance of the metal to glass seals over time, outgassing of internal materials, how good the vacuum pump was when it was evacuated and other issues such as the quality of the cathode and screen material.

The How well it's driven includes accurate control of heater voltage and hence cathode temperature and the average beam current drawn by the tube during use.

There are some links here (including some videos) that I think you may find informative:

https://www.earlytelevision.org/crt_rebuilding_at_museum.html

Hello Durable Goods,

That is one hell of a scholarly article, I must say.

I can only think of one CRT that has clocked up well over many Mega Hours, and that is the Sun.
I am not being silly or sarcastic, but I do ask that you use your imagination regarding the operation of stars.


During my working years, I found Sony monitors (Broadcast quality) were well capable of continuous operation.
Only switched off when in need of repair, the television station test pattern would be well burnt into the phosphor.
Newer monitors did not last as long. I guess today's manufacturers want to sell 'new more frequently'.


There was an old saying which addressed television picture tube life:

"The lifespan of the picture tube is dependent on the generosity of the spray gun operator coating the cathodes."

I wish you luck in your quest, please write if you do find any million-hour CRT's.

Re differential life of colour CRTs, Sony was one of the poorer performers in my experience.

Best by a large margin was Toshiba.

I once saw a plot of expected tube life from Toshiba. It plotted expected life against heater voltage.

What they recommended was exactly 6 volts DC. 6.1 volts or 5.9 volts, the curves would fall away.

At 6.0 volts they predicted a life to 50% emission of 100,000 hours. I would be inclined to believe that.

My parents purchased an AWA C6333 telly in 1982 and it did an average of eight hours a day for something like 30 years until they purchased a digital set just before the end of analogue transmissions in 2013. I don't know if that's 1m hours but the telly was never pulled apart for repair in that time so either way it is a good run. I bought the Thorn version of the same set, a 63T1, second hand in around 1991 and it saw service for the remainder of the analogue era too. They were a good set with only one motherboard inside. Very simply and they just worked.