This post was written by Keith Dawson for UBM Tech’s community Web site All LED Lighting, sponsored by Philips Lumileds. It is archived here for informational purposes only because the All LED Lighting site may go dark at any time. This material is Copyright 2013-2015 by UBM Americas.

2014-10-02

LED Filament Bulbs

Are we approaching peak filament? LED bulbs whose active elements resemble incandescent filaments are everywhere lately. But will the demand for this retro look endure?

We took a quick look at LED filament bulbs last June when Margery Conner did a piece on them at DesigningWithLEDs.com.

The Japanese company Ushio was the first to have introduced LED filaments, in 2010, according to LEDInside.com. Here is a video showing the company's filament-style clear bulb being shown at Lightfair in 2010. (The company is still selling the bulbs, or their descendants.)


AriusTek LED filament bulb

In March of this year Philips came out with its retro-look clear bulb, and it made a splash. But the LEDs weren't in the form of traditional incandescent filaments; rather, they were arranged as a ring of nearly point sources. (The overall look is similar to that of the Panasonic bulb that was introduced in 2011.) The LEDInside.com article linked above reports that rumors of Philips having ordered LED filament bulbs are false.

Conner provided a link to the spec sheet for a 38.5-mm LED filament from Z-Wave. Its light output is 105 lm. Conner's piece has a photo of a Z-Wave bulb with a clear envelope containing 8 such LED packages, probably giving around 800 lm. This leder-TEK bulb has four LED filaments that look about twice as long, again for 800 lm or thereabouts.

A Wisconsin company, AriusTek, just introduced LED filament bulbs to replace 40W, 60W, and 100W incandescents, for prices of $10, $15, and $20 respectively. Photos of the bulbs indicate they are also using LED filaments about 75 mm (3 in.) in length, each of which presumably generates 200 lumens or so.

Is it toast?
LEDInside.com's article, reported from the Chinese-language site hqlednews.com, is an account of a talk by Guoqing Tang, the head of the LED lighting business for Samsung China. Tang described how Chinese packagers jumped on the idea of LED filaments, and because of the "herd mentality" nature of the Chinese LED industry (Tang's words in translation), pretty soon the business was awash in LED filaments.

This page on Made-in-China.com bears out the form's ubiquity, as will a search on Amazon or any retailer of LED bulbs.

LEDInside goes on to quote Xu Zhengrong, described as the CTO of a Hong Kong packaging company and a veteran of the Chinese LED packaging business. He alluded to problems with heat handling and declared. "LED filament bulbs are not safe, they are unable to pass safety standards." He mentioned other problems with the form factor such as "super low yield rates" and "painful manufacturing techniques."

We always have to wonder, reading an article such as this, about the agenda behind it. Has Samsung decided not to play in the LED filament arena and so seeks to discredit the whole idea?

Conner mentioned not having seen LED filament bulbs in the retail channel. Months later, I still haven't. When they show up in the aisles of Home Depot, Lowes, and Walmart, then we will get a better idea of the staying power of this retro design.

— Keith Dawson Circle me on Google+ Follow me on Twitter Visit my LinkedIn page, Editor-in-Chief, All LED Lighting