back to article Boffins switch on pinchfist incandescent bulb

Scientists at MIT have been dabbling with some tech which could see the incandescent lightbulb make a comeback at energy efficiencies far exceeding current LED and compact fluorescent (CFL) alternatives. The venerable incandescent bulb simply uses electricity to heat a tungsten filament to around 2,700°C, at which temperature …

  1. Oh Homer

    Sounds expensive

    As Da Vinci noted: Simplicity is the ultimate sophistication. And usually a lot cheaper.

    1. Anonymous Coward
      Anonymous Coward

      Re: Sounds expensive

      What sounds complicated now may sound simple when we're doing it everyday....... or not :-)

      I wonder how Swan would feel seeing his original invention being advanced on all these years later.

      1. GlenP Silver badge

        Re: Sounds expensive

        Upvote for the reference to Joseph Swan.

      2. Anonymous Coward
        Pirate

        Re: Sounds expensive

        "...much as Thomas Edison did with the original tungsten filament technology."

        Um.. no. Edison's strategy for making money from other people's lightbulb invention was a cheaper process for producing CARBON filaments.

      3. PNGuinn
        Happy

        Re: I wonder how Swan would feel

        Pretty pi**ed off that it was being done by the opposition on the other side of the pond and not in Blighty I would say.

        Actually, this is not a new idea. It's already in production in some halogen lamps, albeit in a simplified form. Gives a tungsten filament lamp a B rating in efficiency.

        Basically a quartz envelope with an infrared reflective coating shaped to reflect back onto the filament.

        1. nijam

          Re: I wonder how Swan would feel

          > It's already in production in some halogen lamps, albeit in a simplified form.

          Yes, the generic term is dichroic.

    2. ZSn

      Re: Sounds expensive

      If you look at the technology required to produce a 'white' LED light, you'll find that that is far from simple either. This looks as if it can be automated so won't be much different. If it will scale from the lab to the home that is.

      1. Mage Silver badge

        Re: Sounds expensive

        And so called White LEDs are ghastly colour rendition. PSU life and interference as well as illumination angle are an issue. CFLs/Fluorescent tubes though are poor in the cold.

        1. scatter

          Re: Sounds expensive

          "And so called White LEDs are ghastly colour rendition"

          Not any more. Look for high CRI lamps (95+). The light they produce is barely indistinguishable from incandescent.

    3. Dave 126 Silver badge

      Re: Sounds expensive

      >As Da Vinci noted: Simplicity is the ultimate sophistication. And usually a lot cheaper.

      An LED light is more complicated and expensive than an incandescent bulb, but cheaper to run.

      A bicycle is more complicated and expensive than a sled, but more efficient in many circumstances.

      So, as others have noted: Horses (or bicycles, or sleds, or camels, depending) for courses.

      Or: Anyone who overgeneralises is always an idiot. : p

    4. martinusher Silver badge

      Re: Sounds expensive

      One of my little quirks is that I've sometimes work with valve equipment. The original valve types from the 1910s were known as 'bright emitters' because they were essentially a light bulb with some additional electrodes placed around the filament. These were quickly replaced by 'dull emitters' that used an oxide coating over the filament allowing it to work at much lower temperatures (which, in turn, was largely replaced by the 'indirectly heated kathode' or, in other words, 'a thin tube covered with an electron emitting surface heated by a thin wire or tape insulated by an oxide coating'. They're surprisingly complicated for a mass produced article.

      What I'm getting at with all this is that this light bulb sounds about as much hassle to produce as a typical valve from 60-70 years ago. Since valves were cheap expect these light emitters to also become cheap.

  2. Matthew 3

    TCO?

    A 60W incandescent bulb that's three times more efficient than before will still lose over 50W of that as heat. But if you're comparing it with a 6W LED, the inefficiencies surely don't change the fact that it is still cheaper to run for the same amount of usable light?

    1. DaLo

      Re: TCO?

      Efficiency is lumens per watt. Therefore a more efficient bulb either requires less power for the same light output or you get more light for the same output.

      A bulb that is three times more efficient therefore needs a 1/3 of the power for the same light output. You now only need a 20w bulb to replace your existing 60w bulb.

      The key is also "the same amount if light" - a regular 6w LED bulb will not produce the same amount of dispersed light as a 60w incandescent bulb at the moment.

      1. Anonymous Coward
        Anonymous Coward

        Re: TCO?

        "The key is also "the same amount if light" - a regular 6w LED bulb will not produce the same amount of dispersed light as a 60w incandescent bulb at the moment."

        The ones I bought seem to... OK not a scientific test and I may have got the Watts wrong but I bought a "75W equivalent " Philips bulb and my eyes tell me that it's about right.

        1. DaLo

          Re: TCO?

          Stronger LEDs (not 6w!) might have the "equivalent" in a narrow field underneath the bulb (they are very directional unless diffused), but the total amount of light given off will not be equivalent.

          They are good at replacing GU10s or under cupboard lighting, less so for a single bulb in a lamp to light up a room.

          1. DaddyHoggy

            Re: TCO?

            My kitchen is now lit entirely by 7.5W (50W equivalent) 480 lumen GU10 LEDs fitted with diffusers, replacing 50W 900 lumen halogens. The light from the LEDs is less directional, has a nicer quality to it (seems 'whiter') and the entire kitchen feels more brightly lit overall despite, apparently, having half the lumens I had before.

            I bought a pack of 4 when they were on special offer at B&Q and the £10 investment seemed worthwhile as a suck-it-and-see given I'd ran out of 'spare' halogens, it seemed like an ideal opportunity to make the switch.

            1. Kernel

              Re: TCO?

              "My kitchen is now lit entirely by 7.5W (50W equivalent) 480 lumen GU10 LEDs fitted with diffusers, replacing 50W 900 lumen halogens. "

              So is mine now - after one of the (originally) 12 halogen decided to fail by blowing a shard of hard and sharp plastic out of the front lens.

              Halogen GU10s are now banned from our house as being too dangerous to have around a food prep area.

          2. Anonymous Coward
            Anonymous Coward

            Re: TCO?

            "Stronger LEDs (not 6w!) might have the "equivalent" in a narrow field underneath the bulb (they are very directional unless diffused), but the total amount of light given off will not be equivalent."

            If that is allowed, it seems that you could get an big increase in apparent brightness of a regular incandescent bulb just by applying a mirror coating to part of the inside - and thus make say a 20W bulb which is "equivalent brightness" to a 60W bulb?

            1. Cynic_999 Silver badge

              Re: TCO?

              "

              If that is allowed, it seems that you could get an big increase in apparent brightness of a regular incandescent bulb just by applying a mirror coating to part of the inside - and thus make say a 20W bulb which is "equivalent brightness" to a 60W bulb?

              "

              When you require a directional light source that is most certainly the case, yes. There are quite a few incandescent bulbs that have such an arrangement, e.g. the conical "spots" and various photographic bulbs have mirrored sections behind the filament.

              Most rooms have white ceilings and light-coloured walls, which means that the light from a ceiling bulb that is not directed downwards is not wasted - it is reflected off ceiling and walls to create a more diffuse light without the harsh shadows associated with directional light sources.

          3. tony2heads

            @DaLo

            Single bulb??

            As the light from an incandescent bulb is omnidirectional it is really only good if if in the centre of the room; However I prefer lighting from above and fairly well distributed in a room for working in (so several sources) and if I am reading at home in the evening then a light near to hand which directs light towards the book.

            There is no room where I would prefer a single bulb, except for the smallest one.

            1. Anonymous Coward
              Anonymous Coward

              Re: @DaLo

              I fitted two led filament bulbs to two of my rooms. They create pretty much an omnidirectional light source and is so much better than the CFL they replaced.

              They even look like old squirrel cage bulbs and if you spend a little more money you can buy them in a dimmable option too.

              Plenty bright enough to act as the main light source for a bedroom.

              1. Anonymous Coward
                Anonymous Coward

                Re: @DaLo

                Since you mostly use light bulbs at night in your home you probably don't want them to have a daylight color temperature, but a warmer "hour before sunset" color which as luck would have it is about what a standard incandescent outputs (these new type may be different)

                For lighting in windowless areas occupied during the day or those with reduced daytime illumination (like say the lighting in a big office cube farm where conference rooms and VP offices hog most of the windows) then you'd want your bulbs to have a daytime color temperature.

            2. Cynic_999 Silver badge

              Re: @DaLo

              "As the light from an incandescent bulb is omnidirectional it is really only good if if in the centre of the room;"

              That is certainly true if you have a room with black walls and ceiling.

          4. Vic

            Re: TCO?

            Stronger LEDs (not 6w!) might have the "equivalent" in a narrow field underneath the bulb (they are very directional unless diffused), but the total amount of light given off will not be equivalent.

            I bought an 8W LED lamp. It's diffuse. It's so bright, I've had to change the lampshade...

            Vic.

          5. kiwimuso
            Happy

            Re: TCO?

            @ DaLo

            Sorry, I call bullshit. Or more politely, I fear you are incorrect in your assertion.

            We have had the whole house converted from a mixture of R80 and 50W halogen downlights with 9W sealed LED units. Yes they are diffused (why not) but more than adequate light.

            They provide more than sufficient light in the room. In fact, they provide so much light that we have had dimmers installed in order to adjust the light intensity in places like the dining room.

            If you are interested, you can find them, here http://www.energymad.com/Ecobulbs.

            I can't recommend them more highly.

        2. Mage Silver badge

          Re: TCO?

          The equivalents on lamp packages are a lie. This has now been exposed, though known by anyone expert for years. You need about 20W + of CFL or LED to light the same area to same brightness as a 100W lamp. Or about an 85W Halogen. 75W halogen is NOT same as 100W regular lamp, they are allowed too much latitude on measurements!

          1. Charles 9 Silver badge

            Re: TCO?

            " This has now been exposed, though known by anyone expert for years. You need about 20W + of CFL or LED to light the same area to same brightness as a 100W lamp."

            Funny. From what you say, the packages I read on a regular basis would then be accurate, because the 100W incandescent analogue in CFL is rated 26W (over 20 as you said). The watt ratio is roughly 4:1. A 9W CFL is roughly supposed to put out as much light as a 40W incandescent, a 15W a 60W, and I think an 18W a 75W.

      2. DaddyHoggy

        Re: TCO?

        Hmm...

        I've just replaced four 900 lumen 50W GU10 traditional halogen spotlights with four 480 lumen 7.5W LED GU10 spotlights.

        So while it seems I've approximately halved the amount of lumens I'm generating I've reduced the Watts consumed to approximately 1/6th of what it was before.

        Perhaps a more 'human' observation is that the light from the LEDs is 'nicer' in terms of overall illumination and 'colour' - at least for me (when cooking) and my wife (when doing her arts and crafts) and it actually feels if we have more light in the room, not less.

        1. Frank Bough

          Re: TCO?

          Ive never heard anyone who preferred the light quality of LED over tungsten halogen before.

          I swapped mine over about a year ago and was so appalled at the light quality that I promptly swapped back.

          Great news if we can avoid filament bulbs being banned by the bloody EU.

          1. scatter

            Re: TCO?

            Look for high CRI lamps. Their light output is virtually identical to incandescent.

      3. This post has been deleted by its author

      4. Anonymous Coward
        Anonymous Coward

        Re: TCO?

        "Efficiency is lumens per watt."

        Except that most people would prefer "efficiency" to be a dimensionless quantity expressed as a percentage. Also, to maximise lumens per watt you would emit green light, which wouldn't be pleasant for domestic use.

        I wish they'd agree on a sensible definition of efficiency for use in product descriptions. It could be something like: the brightness of the light after it has been filtered so as to have the same colour as standard daylight as perceived by a standard human eye divided by the maximum brightness possible with the given power consumption. (I think that there are already standard definitions of daylight and human colour perception. According to this definition, a monochromatic green LED would have 0% efficiency because the only way to filter it into a daylight colour would be to block it completely. An incandescent bulb would be slightly penalised by the need for a bluish filter to turn it into daylight colour.)

      5. PNGuinn

        Re: TCO?

        The real problem with fluorescent lamps - be they mercury vapour or blue led based - is their very peaky spectral response, and hence the problems of severe eye strain and even migraines that many people suffer from. A secondary problem is lousy colour rendering.

        This can be overcome somewhat by using a a more exotic mix of phosphors, but at a cost to luminous efficiency.

        In the 1970s Thorn had a fluorescent tube they called "Artificial Daylight". It was designed for the reprographics trades and the like. High nominal colour temperature at 6500 K. Excellent colour rendering for a fluorescent (even had a wodge of long wavelength uv so things that fluoresced under daylight would do so under these tubes.) Only about 40 lumens / watt though. An excellent general work light, with low eye strain. Sadly now discontinued.

      6. Alan Edwards

        Re: TCO?

        A 6w LED may not match a 60w incandescent (a bit less than 40w IME) but a 15w LED does. If the fancy new incandescent matches a 15w LED at 20w, it's still got a way to go to match LED in terms of light output efficiency.

        What does the coating do to the colour temperature of the light? I'm not too bothered, but some people are sensitive to that.

    2. Jonathan Richards 1

      Re: TCO?

      It always occurs to me when folk talk of lightbulb inefficiency: whenever the lightbulb is operated in an environment which is being heated and thermostatically controlled, then the heat energy output of the lightbulb isn't being wasted. It is contributing to heating the space it's in, and that means the thermostat will click off that much sooner. For much of Northern Europe, when it's dark, it's cold. My venerable Anglepoise is at this moment sitting in the corner, helping to keep the room warm.

      1. This post has been deleted by its author

      2. PNGuinn
        Mushroom

        Re: TCO? @ Jonathan Richards 1

        I fully agree. But "they" would argue that your condensing boiler gas fired heating system cooking the whole house is so much more efficient than .....

        On the other hand if "they" had ensured that there was enough clean nuclear power available ....

        You aren't one of those antisocial CO2 spouting individuals who are so uncaring as to live off the gas network are you?? Dare to use leccy for anything other than recharge a milk float in skirts and 50,000 essential battery powered toys??

        Upvoted. Especially for the Anglepoise reference. Lovely bit of kit. Is yours one of the originals with the square base, shade designed for a ginormous 60 W bulb and purple cotton covered twisted pair flex (hopefully rewired by now)?

        Icon just because...

        1. Charles 9 Silver badge

          Re: TCO? @ Jonathan Richards 1

          "On the other hand if "they" had ensured that there was enough clean nuclear power available ...."

          There are those who would argue that emboldened term is an oxymoron.

          1. DropBear

            Re: TCO? @ Jonathan Richards 1

            "There are those who would argue that emboldened term is an oxymoron."

            Indeed; then there are those others who actually have a clue of what they're talking about.

      3. scatter

        Re: TCO?

        Much of northern Europe uses gas for space heating which is generally a lot cheaper and lower carbon than electricity. Also having your heat sources up near or even in the ceiling is not really a great way to go about heating a room. Much better and cheaper to fit the most efficient lighting you can find and leave your heating system to do the space heating as it was designed to do.

      4. Vic

        Re: TCO?

        whenever the lightbulb is operated in an environment which is being heated and thermostatically controlled, then the heat energy output of the lightbulb isn't being wasted. It is contributing to heating the space it's in

        Whilst that is true, electricity is usually an inefficient way to heat your home. Generation from a thermal source - as is most often the case - is thermodynamically-limited in efficiency, and so converting that electricity back into heat means plenty of wasted energy in the cycle.

        Vic.

  3. Androgynous Cupboard Silver badge

    'ere we go

    Cue americans and Daily Mail readers complaining about the gummint unnecessarily prizing their incandescant bulbs from their fossil-fuel loving hands in three... two... one...

    1. tiggity Silver badge

      Re: 'ere we go

      For many months of the year in the damp, dank, cold UK the "waste" heat is nice and useful.

      In one of our rooms with quite a few lights (all now energy saving as all the old bulbs got replaced when they wore out) we quite often (especially in Winter) turn on an electric heater for added warmth, previously never needed as the old incandescent bulbs added extra heat.

      I would say that probably at least 4, maybe 5 months of the year the heat is "useful" rather than "waste".

      In the same way that (back when cars were not controlled by masses of electronics & allowed simple maintenance tasks) you used to switch carburettor from Summer to Winter setting, almost worth (for heating) throwing incandescent lighting in for WInter & reverting back to energy savers in (late) Spring ;-)

      .. not a Mail reader or Merkin

      1. Lester Haines (Written by Reg staff) Gold badge

        "at least 4, maybe 5 months of the year "

        It's an interesting point, but I personally don't want to be paying for heating the atmosphere in summer.

        1. Nigel 11

          Re: "at least 4, maybe 5 months of the year "

          A good fraction of the heat generated up near the ceiling goes up through that ceiling. If you live in a flat you are making a donation to upstairs' heating bill. If you aren't using the bedroom above your living room until several hours later, that's largely waste heat in winter and an even more uncomfortably hot bedroom in summer.

          Also per BTU or KWh or Joule of warmth in your house, Electric costs more than gas (and oil at today's price!) so it might not be a waste but it's still an extra drain on your wallet.

        2. Anonymous Coward
          Anonymous Coward

          Re: "at least 4, maybe 5 months of the year "

          "It's an interesting point, but I personally don't want to be paying for heating the atmosphere in summer."

          Plus, it is much cheaper to heat the air from the gas fueled central heating than from electric light bulbs.

          Currently our CH boiler is set to 55C. If it gets really cold outside I might turn it up to 58 or even 60, which takes a few seconds. I'm not wasting electricity when I don't need it.

          I've got a few CFLs still to replace but the rest of the house is on LEDs and I really cannot see the point of a more efficient incandescent bulb. To get the colour temperature it still has to run at filament temperatures which will cause eventual failure, it still needs a gastight envelope, and it still uses quite a lot of an expensive and not that common metal which doesn't get recycled.

      2. DaLo

        Re: 'ere we go

        But you could just use a low watt electric heater in the winter for the same effect but better efficiency. You then choose exactly when to have heat and when to have light and not have to compromise for the times you want one but not the other.

        The light bulb is more likely to be radiating heat to parts of the ceiling than a ground level heater which will have a more convective airflow.

      3. DropBear
        Trollface

        Re: 'ere we go

        "In one of our rooms with quite a few lights (all now energy saving as all the old bulbs got replaced when they wore out) we quite often (especially in Winter) turn on an electric heater for added warmth, previously never needed as the old incandescent bulbs added extra heat."

        Tsk, tsk, tsk... We should know better - that's not the right way to supplement your heating. What you do instead is you buy the latest video card for your PC - way more heat liberated than a standard incandescent and it even entertains you for free in the process!

    2. Matt 21

      Re: 'ere we go

      "Go"

      Well, I have some sympathy when you consider the CFL ones we were first given as alternatives. The light was poor and they didn't last well.

      They improved quite a lot bu I wasn't really happy until the latest LED ones came along. Now the light is of a better quality, they use less 'leccy and seem to last well. In fact they last so well that the last light I put up didn't have a bulb it was just an all-in-one LED.

      1. Nigel 11

        Re: 'ere we go

        Anyone who thinks LED bulbs are little better than CFL bulbs is buying the cheap ones with a CRI (Colour-rendering index) of 80. They range from no better than a CFL (except blue rather than green) to just about OK. If you have to buy in a shop in the UK, Philips ones seem to be the best of a bad bunch.

        You get what you pay for. (I.e. if it's cheap it will not be good, although if it costs a packet it won't necessarily be any good either).

        Search out LED bulbs with a CRI value of 90 or higher. They are remarkably hard to find in the UK where I guess they know that most folks look at the price not the specifications. The best LEDs I have found are made by Civilight and have a CRI of 95 or higher. They're dimmable. The 2700K warm white ones are sufficiently close to Halogen that I'm perfectly happy to spend £15 each. (I had to get an energy assessor to come back because he took one look and decided they were halogens! )

        There are a number of other less dear brands available in Germany boasting CRI of 90 or above. In Germany people seem to be more willing to pay more for a better product.

        How to get them here? I've found that the easiest way is to shop at elv.de using Chrome and its built-in Google translation option. ELV stocks a large range and all the specifications are there. The hardest bit is feeding a UK address into a German shipping form. The EU means there are no customs or other hassles, shipping is not particularly dear, and the biggest rip-off is the extra percentage your credit card will charge for Pounds to Euros conversion.

        Oh, and pay attention to the colour temperature as well! I assumed that because the 7W Civilight bulbs were 2700K that the 10W ones "warm" ones would be likewise. They were 2800K, rather whiter than I wanted. I can see why people hanker after the days when a light-bulb was just a light-bulb.

        1. stucs201

          Re: LED and CRI

          Has anyone found an LED G9 capsule with a good (90+) CRI with a 'normal' colour temperature? I maybe found one (on a site I was unsure about trusting) but it had a 'vintage white' colour temperature of 2200K - way too orange for my liking.

          1. Nigel 11

            Re: LED and CRI

            @ stucs201 No, and I suspect high CRI G9 led isn't do-able for lack of any place to sink the extra heat that filtering out the surplus blue components will generate.

            LED G9 is pretty marginal anyway. I experimented with "ordinary" G9 capsules and both failed within months. I took them back for a refund. Luckily I had kept the receipt, knowing that LEDs need a heatsink and that there is no space for a proper heatsink in a G9 capsule.

            It's sometimes more cost-effective to replace the light fitting than to retro-fit LEDs. Or at least it is if you are your own electrician.

            1. stucs201

              Re: LED and CRI

              Thanks Nigel, that's helpful. Looks like the halogen capsules are staying for the foreseeable future then - these fittings were chosen for looks and the styles I like tend to be G9.

            2. Doctor Syntax Silver badge

              Re: LED and CRI

              "t's sometimes more cost-effective to replace the light fitting than to retro-fit LEDs. Or at least it is if you are your own electrician."

              Going shopping with SWMBO for light fittings? Not worth it!

        2. Mage Silver badge

          Re: 'ere we go

          All LED lamps have a horrid gap in cyan part of spectrum, broad peak at yellow, narrow peak at blue end. They get bluer with age, the PSUs use too cheap electrolytics and fail. They often have inadequate filtering and only really beat CFL for efficiency in the cold or if a narrower illumination is required. You can make the Colour Temperature OK (though rises with age). Colour rendition is poor and they suppress melatonin at night, a lower power halogen better for late night reading (or if not dead trees, then Kindle/Kobo with LED front light off).

        3. scatter

          Re: 'ere we go

          Well-Lit is a UK company selling lamps with a CRI of 97. They're excellent.

  4. Phil O'Sophical Silver badge

    "waste" heat?

    Incandescent bulbs are certainly inefficient at producing lght, but who says the heat is waste? It was 2C outside last night, I'm fine with those bulbs adding to my home heating, the thermostat will adjust the central heating to compensate, nothing is "wasted".

    As for while reflecting infrared energy back for reabsorbtion by the emitter., once "reabsorbed" where does it go? It can't stay in the emitting filament, since that would melt. Converting it to light would be nice, but materials which can absorb heat and generate light don't, AFAIK, exist.

    Still at least you didn't copy the bit from the Daily Telegraph's "science editor" who described the incandescent filament as emitting black-body radiation...

    1. Bluewhelk

      Re: "waste" heat?

      If the heat can't escape then less electricity is needed to maintain the emitter temperature required to produce the light, that's what makes it more efficient.

      Edit:

      A normal filament bulb will actually be pretty close to a black body emitter. This new version would not be due to the filtering.

      1. stucs201

        Re: black body or not

        I wonder how good the transmission of visible light is. Is it letting through all of the visible light, or only most of it? Hopefully it isn't interfering too much, it would be nice if these had a 100CRI the same as normal incandescent bulbs, but it's not clear if they do or if they're more like CFLs and LEDs in their colour rendering.

    2. Gideon 1

      Re: "waste" heat?

      "Converting it to light would be nice, but materials which can absorb heat and generate light don't, AFAIK, exist."

      That would be an incandescent light bulb filament.

      1. Pierre Castille
        Headmaster

        Re: "waste" heat?

        Gas mantles convert heat to light - just to be accurate and pedantic

    3. captain veg

      Re: "waste" heat?

      > materials which can absorb heat and generate light don't, AFAIK, exist

      Never seen a blacksmith plying his craft?

      -A.

      1. Dave 126 Silver badge

        Re: black-body radiation...

        >Still at least you didn't copy the bit from the Daily Telegraph's "science editor" who described the incandescent filament as emitting

        The MIT news letter uses the same phrase.

        http://news.mit.edu/2016/nanophotonic-incandescent-light-bulbs-0111

    4. nijam

      Re: "waste" heat?

      > Still at least you didn't copy the bit from the Daily Telegraph's "science editor" who described the incandescent filament as emitting black-body radiation...

      In the visible and IR spectrum, the filament does indeed emit radiation that is very close to the black-body spectrum. So there's no need to be be snarky about the "science editor"!

  5. Whitter
    Boffin

    Previous "make old stuff better" from back in 2009 (from work started in 2006 or so):

    http://phys.org/news/2009-05-regular-bulbs-super-efficient-ultra-fast-laser.html

    Might even be related: can't tell it its colour or structure from the old report.

    1. Dave 126 Silver badge

      The above link kindly supplied by Whitter, above, is well worth two minutes of your time to read, IMHO.

      Thank you.

      It then lead me to start reading more generally about 'femtosecond lasers' and their current and future applications.

      Now I've lost a bit more time than just two minutes!

  6. This post has been deleted by its author

    1. Nigel 11

      That was the Telegraph's headline. Hardly worth groaning for the first time around.

  7. Duncan Macdonald Silver badge

    IR reflector on inside of bulb ?

    As the structure of a filament is complex (coiled coils), it might be better to put the IR reflector on the inside of the glass bulb where it would be easier to get a uniform coating.

    1. DropBear

      Re: IR reflector on inside of bulb ?

      I have a hunch the reflector is not all that ideally reflective, and then you'd now be heating up the glass bulb... again. Heating the filament instead would seem to be far less of a problem...

  8. Yugguy

    Resources to manufacture

    Given that this is more complex than a standard incandescent, it would only be useful if the total lifetime cost of it, including manufacture and , was less than that of the standard bulb.

    1. Nigel 11

      Re: Resources to manufacture

      People may be willing to pay a higher total lifetime cost to save the extra CO2 emissions from the Halogen filament bulb, or to get a CRI even better than the best LED (around 97 at present). Also they said it has potential to be 30% efficient in converting electricity into visible light whereas the best LEDs judged on light quality / CRI are around 8% (*). So that's the lifetime electricity cost down to a half or even a quarter of the LED.

      But this is research, nowhere near product development yet. First question is whether they can make them in production quantities at all!

      (*) The crappy bluish ones are around 13%, because one of the ways to make better quality LED light is to filter out the surplus blue component and turn it into waste heat.

  9. Ed 13

    Delta T

    I think there's going to be a fundamental problem here.

    From the article it seems that the idea is to keep more of the heat in, which is a path that halogen bulbs started down and why they are more efficient than ordinary super-coiled filaments (which are in turn more efficient than coiled filaments - a.k.a. Rough Service bulbs).

    The problem is that you have to keep the tungsten at 2700degC which being slightly warmer than I like my room temperate, you have a massive temperature difference to maintain and any thermal insulator is going to struggle with.

  10. Roger Kynaston Bronze badge

    How will this work with 12v DC?

    I replaced my navigation lights with LED a couple of years ago and love only burning 6W at the masthead rather than the original 25W. Also, will they burn out regularly as a trip up a 12 metre mast involves a lot of winch grinding for some poor sod (my wife can't do heights).

    Interesting thing though.

    1. Anonymous Coward
      Anonymous Coward

      Re: How will this work with 12v DC?

      Well...compared to the original 25W bulb the filament will be thinner because the resistivity of tungsten is fixed. So it will be more fragile. Probably not a problem under sail but when the auxiliary engine is going you might get masthead vibrations that destroy it pretty quick. Or you can have a much more robust multi-chip LED.

      Your masthead, your decision, but I know what I would go for.

  11. Kevin McMurtrie Silver badge

    Been there

    This was done before with double walled xenon halogen bulbs. The inner bulb used high pressure xenon and a bit of halogen that let the filament run very hot without evaporating. The outer bulb had a vacuum for insulation. When you see a 1990s car with a dimly glowing cracked headlamp, it's one of those with a crack in the outer bulb.

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