Why haven't filament LED bulbs taken over the market?

[TimNJ]

As far as I can tell, filament LED bulbs seem almost like the ideal general purpose lighting technology. They meet consumer wants and needs by looking good and performing well while significantly cutting BOM size for manufacturers.

The LED filaments are effectively a series string of chip-on-glass LEDs. Therefore, they can be driven at a high voltage and low current. This is basically the opposite of traditional LED bulb technology which is low voltage and high current. Because of this, BOM size is way smaller for filament LED bulbs. Usually just a bridge rectifier, driver chip, external MOSFET, a capacitor, and resistor or two. And no heatsink necessary.

Philips et. al. rates them at the same expected life as traditional LED bulbs. Electronupdate did a video testing the brightness after 10k hours and the results were very good:

Why then, are manufacturers still making boat loads of the "traditional" LED bulbs? Are yields for LED filaments still low? Mass manufacturing still not there yet? Find that hard to believe since I assume an incandescent production line could be retooled fairly easily for new style bulbs.

Any ideas?

[Ampera]

I haven't seen these on the market, and I agree, they do look like a home run. No clues over here, possibly something to do with capitalism?

[mikeselectricstuff]

They do seem to be getting more popular, but in the days of incandescents, visible filaments weren't that common compared to pearl/diffused, as filaments cast harder shadows, so not always ideal for interior lighting.
For a diffused source, conventional LEDs may be more efficient and/or cheaper.
Filaments do have quite a lot of die and phosphor compared to the SMD LEDs used in conventional bulbs.

[duak]

I bought a couple of no-name filament bulbs from the local LED lite store.  The first thing that struck me was that the glass has a rubberized coating; a Good Idea for anything made of glass.  The second thing is how little heat sinking there is on the LED strings.  I wonder how hot the LEDs actually get?  Probably not too hot if there isn't serious degradation in output luminosity.  I have some 60 W GE LED bulbs that get a lot hotter - I think I measured something north of 70 C.

Cheers,

[glarsson]

Readily available here in Sweden in many variants. Perhaps manufacturers haven't bothered redesigning the filaments for the lower tension (120V) used in some countries?

[TimNJ]

Maybe the cost savings in reduction of electronics BOM is made up for with more expensive(?) filaments. As mike says, they take more die space. Plus the entire string has to work or you throw it out. I assume cheap chip LEDs can be had fairly cheaply.

Good point about the light quality. Though, I'm sure they could put a diffused coating on these bulbs pretty easily. For now, it seems they want everyone to know about the cool technology inside.

Rubberized coating sounds tricky from a thermal perspective, but maybe not. I have a few Cree bulbs with that coating and while nice, I'm not sure why they bothered. All you have to do is safely remove the bulb from the packaging and not drop it in the 30 seconds it takes to screw it in.

[IanB]

I like the filament bulbs and prefer to use them over other types. Some advantages are that they run cool, they have a good illumination pattern, and the light tends to be an attractive golden color. A disadvantage is they tend to be available only up to 60 W equivalent. I have not seen higher light outputs up to 100 W equivalent.

I do not find the lack of a diffused globe to be a problem as the bare filaments are quite attractive and most lamps have an external shade or diffuser anyway.

[james_s]

The filament types have been readily available here for some time now, I have a few of them in service. They are not without flaws though, the filaments create shadows of each other and you get yellow/brown fringes around objects. Typically they are also a tad less efficient than other types and have more primitive drive electronics made to fit completely in the base. They are great for decorative fixtures where the bulb is visible but otherwise I generally prefer other types.

[phil from seattle]

I bet it's all about heat. In the standard LED line powered bulbs, the LED chips are mounted on a metal plug that connects to the base which acts as a heat sink. So, the filament bulbs need more LEDs to produce the same lumins.  Frankly, I much prefer diffusers between my eyes and the LEDs.  And, they are readily available in the US but are more expensive than the standard frosted edison base bulbs.

[Nusa]

They seem to be primarily available in the lower-wattage vanity and candelabra style bulbs. In the US, at least, the incandescent version of those bulbs are still sold, which easily beat any of the alternatives on purchase price. Plus, you're going to pay extra if you need a dimmable LED, while that's a free feature on an incandescent.

Also, there's simply the time factor, combined with resistance to change. I don't think any of the six 40w bulbs in my bathroom mirror fixture have burned out in the last 10 years, and I have several spares on hand if they do. Those lights only get used 10 minutes a day, and it's not worth my time or the expense of updating them. Maybe in another 10 years.

In the very long run, I expect the market for replacement bulbs will largely disappear, as lighting will be so long-lasting that they're intended to last the life of the product. A current example of that would be LED lighting in new model refrigerators.

[james_s]

I replaced every bulb in my house with LEDs years ago and I've almost forgotten what it's like to have to change bulbs. The only incandescents I have left are the oven and microwave bulbs, and a couple of lava lites which obviously need the heat of the incandescent to work. For a while I was replacing CFLs with LED as they failed but eventually I got tired of waiting for them to fail. The LEDs are so much nicer, better light, instant on, nice dimming, I was really pleased to see that tech mature and succeed.

[TheWelly888]

I have a 40W equivalent LED filament bulb in my bedside light that I bought in April 2015, it's a nice light and looks a lot nicer than the "glowing turd" shaped CFLs available! But it is not bright enough to replace my ceiling bulb which is still incandescent as I have hoarded some before the ban!

I can't wait for the 100W equivalent bulb to be developed so that I can use it in the ceiling!

[james_s]

Do you live under a rock? 100W equivalent LED bulbs have been widely available for several years. Just yesterday I was in Costco and they had 4-packs of Feit 17.5W 1600 lumen 90+ CRI LED bulbs for about $12.

[IanB]

I replaced every bulb in my house with LEDs years ago

Some bulbs are hard to replace though. I have bathroom vanities with large decorative globes, and chandeliers with small decorative candles and globes, and every light is on a dimmer. I rarely run lights at full brightness as I would get blinded--my general level of room illumination is candle brightness.

[mikeselectricstuff]

I can't wait for the 100W equivalent bulb to be developed so that I can use it in the ceiling!

How about This

[IanB]

Do you live under a rock? 100W equivalent LED bulbs have been widely available for several years.

...but not in the filament style, which is the subject of this thread.

[james_s]

Some bulbs are hard to replace though. I have bathroom vanities with large decorative globes, and chandeliers with small decorative candles and globes, and every light is on a dimmer. I rarely run lights at full brightness as I would get blinded--my general level of room illumination is candle brightness.

It can take some searching for special application bulbs and you might not find one that looks *exactly* like the incandescent but you can get close. There is a large variety of decorative LED bulbs available now, such as the filament type covered by this thread. I have many lights on dimmers and selected LED bulbs that behave well with them.

[james_s]

Do you live under a rock? 100W equivalent LED bulbs have been widely available for several years.

...but not in the filament style, which is the subject of this thread.

The subject of the thread yes, but he didn't say he needed a filament type for that particular application. 60W equiv is the biggest filament type I've seen so far but I'm sure higher power bulbs will come.

[IanB]

It can take some searching for special application bulbs and you might not find one that looks *exactly* like the incandescent but you can get close. There is a large variety of decorative LED bulbs available now, such as the filament type covered by this thread. I have many lights on dimmers and selected LED bulbs that behave well with them.

But as someone else said, the original incandescent bulbs work perfectly, they look nice, they have a good CRI, they are dimmable, and they last for decades when dimmed. There is no need to replace them.

[james_s]

But as someone else said, the original incandescent bulbs work perfectly, they look nice, they have a good CRI, they are dimmable, and they last for decades when dimmed. There is no need to replace them.

Depends on how much use they get. Even with relatively little use the power consumption adds up, especially when dimmers are involved. When you dim an incandescent the already pitiful efficiency drops dramatically, when you dim an LED the efficiency generally rises slightly.

My bedroom lamp for example used to have a 60W bulb, I would dim it down to about 1/4 apparent brightness at which point it was drawing around 40W. When I dim the 12.5W LED bulb to about the same brightness, which is older, significantly less efficient than current designs the power consumption drops to about 3W. It has made a significant reduction to my power bill. Over the life of any bulb, whether incandescent or LED, the bulk of the cost is the energy required to run it, not the cost of the bulb.

[IanMacdonald]

A major problem with filament LEDs is flicker. This is not because of the filaments, but because of the need to cram the regulator into the BC or ES base of the lamp. Thus, usually no filter cap.

A flickering light source can have physiological effects even if the flicker is not obvious. Try waving your hand in front, if you see a strobe effect of your fingers, it's flickering. This used to be a big problem in the days of CRT computer displays. If the display was running at the default 60Hz I would typically ask the user if they suffered headaches. The answer was often, yes. Setting to 75Hz or better usually eliminated the headaches.  I would point out to some sites using old 60Hz-only displays that they were risking a compensation claim if they didn't fix this.

Most LCD panels don't flicker, but there are a few that use an LED backlight which has PWM brightness control. These can be headache-causers, especially if the frequency is low enough that the eye can just detect it. 

Besides, as mentioned LEDs work best with a heatsink. Even if they could work without, they will last a lot longer if kept cool.

[jmelson]

As far as I can tell, filament LED bulbs seem almost like the ideal general purpose lighting technology. They meet consumer wants and needs by looking good and performing well while significantly cutting BOM size for manufacturers.

The LED filaments are effectively a series string of chip-on-glass LEDs. Therefore, they can be driven at a high voltage and low current.

So, there is no way to get the heat out of the LEDs.  Thus, you must run them at really low current, or they will burn out in minutes.

I have some LED retrofits for 48" fluorescent tubes that I made.  They run at 350 mA, and have 20 LEDs in series.  They provide almost as much light as TWO of the 48" tubes.  With hideous old magnetic ballasts, the 2 tubes consumed 101 W from the AC mains.  The string of LEDs, running on a commercial lighting power supply, draws 21 W from the mains.

But, even these relatively low-power LEDs need some heat sink to keep them from deteriorating.  I solder them to a strip of PC board material almost the size of one of the original tubes, and that gets the heat out.

So, that is one of the big problems I see in these filament bulbs.  They are great for mood or accent lighting, but NO WAY will they light up a room.

Jon

[Halcyon]

I have a 40W equivalent LED filament bulb in my bedside light that I bought in April 2015, it's a nice light and looks a lot nicer than the "glowing turd" shaped CFLs available!

 

[IanB]

They are great for mood or accent lighting, but NO WAY will they light up a room.

Oh, but they do. The output in lumens is just as good as with other designs, and the illumination pattern is better since the light is emitted in all directions rather than being focused predominantly upwards away from the base. If I use a traditional LED lamp it tends to light up the ceiling more than the room.

[james_s]

The light distribution was a problem early on, but a lot of engineering effort went into getting omnidirectional light and most of the decent LED bulbs on the market now have a distribution pattern pretty close to that of a standard incandescent regardless of the specific design they use.