|Application:||General and/or decorative Lighting|
|Tube Length:||740mm (approx)|
|Bulb/Tube material:||Glass, warm white phosphor coating on inner wall|
|Peak output wavelength:||N/A|
|Total Light Output:||680Lm (Manufacturers claim).|
|Rated lifetime:||8,000 Hours|
|Operating voltage:||220-240V AC 50-60Hz|
|Warmup/restrike time:||1 minutes/none|
|Cost (original):||£19.95 (January 2012)|
|Place of manufacture:||China.|
|Date of manufacture:||Assumed September 2011. Code 08/0911 stamped on lamp.|
|Lamp Status:||Working, new.|
Compact fluorescent lamps have been commonplace for a good long while now, and they have come a long way since their introduction a little over a quarter of a century ago. In the last ten years though we've only really seen refinements to established designs. There haven't really been any products appearing on the market which have been truly original. This thing I think does qualify though!
A few years ago, I recall stumbling across a website for a design project to create an artistically inspired compact fluorescent lamp. Some of the designs there were really quite eye catching and elaborate. Given the manufacturing challenges in putting them together though I dismissed it as something that was interesting, but unlikely to ever see the light of day on a production line.
Suffice to say that I was rather surprised when only a couple of weeks ago I spotted one in a John Lewis window display. After stopping abruptly enough on the pavement that the person behind me nearly crashed into me, I immediately went and hunted one down in their lighting section. Sure enough, the name on the box was the one I remembered from the suspiciously similar looking project online, Plumen.
Given that there is one of them sitting on my desk as I write this it seems that my predictions that the Plumen would never be more than a design prototype curiosity were rather unfounded, and on this occasion given how fantastic looking a bit of lighting equipment it is, I am glad to be proven wrong. Fantastic looking it may be, it is however equally fantastically difficult to photograph!
From a technological perspective this is a very ordinary compact fluorescent lamp. It has an electronic ballast just like any other, and a perfectly ordinary colour 827 phosphor, and aside from being a rather odd shape, the tube is very ordinary. The greatest challenge in creating this lamp has been how to reliably form the intricate tube shape without causing excessive degradation of the phosphor, as the usual challenges which apply to spiral compact fluorescents are also present here.
The main problem is that the phosphor is applied as a powder suspended in a liquid which is flowed through the tube during production. In linear tubes this is simply done end to end, and due to the action of gravity it is easy enough to get an even covering. With a spiral tube however this action invariably results in a far thicker band at the bottom of each spiral where gravity causes the fluid to run to. This gravity caused phenomenon is highly undesirable as it results in the top of the tube being phosphor deprived, resulting in a loss of light output and the colour temperature wandering off from where it should be due to the increased transmission of the mercury blue lines. The thicker phosphor at the bottom of the tube results in a dark band and reduced light output there. The question may be asked "why don't you just coat the tube before you form it then?" however this does not come without a price either. The heat of the forming process invariably damages the phosphor to some extent, and the stretching of the tube on the outside of the curve results also in the coating there being far thinner than it otherwise should be. On conventional U shaped compact fluorescents this is permissible, as the U-bend section of the tube represents a relatively small percentage of the total tube length. When dealing with a spiral (or similarly curve-intensive design like the Plumen) it's rather more of a problem though, so the former option of coating after tube forming is generally taken. The spiral CFL is rather a compromise by its very design due to the aforementioned phosphor problems, hot running temperatures and relatively poor optical efficiency, however the compact size of the lamps they allow to be created are generally seen as a worthwhile trade off. The approach used for the phosphor deposition on the Plumen 001 appears to be the usual "pour it down the tube after forming it" approach as is generally used these days for spiral CFLs.
The tubing appears to have been formed by a vacuum forming process judging from the mould lines apparent on the tube curves, which is no doubt a far more reliable way of forming the precise curves needed here. Given that the two tubes on each Plumen are identical to each other and are interlocked when fitted into the base, they need to be pretty precise. They are actually two completely separate tubes, connected in series as is often done with the different tubes on neon signs. This arrangement offers greater flexibility in terms of positioning than the usual tube-to-tube connections you generally see with the tubes actually fused together. In this case, that arrangement would of course be impossible to use due to the distance between the tube ends.
Electronically it's very ordinary, just a garden variety HF electronic ballast in the little black cap. I have to confess to being somewhat disappointed to see that it's an instant start ballast. Given that this is a £20 lamp, I would honestly have hoped for a programmed start ballast here to prolong the life of the lamp - or at the very least a simple soft-start device to preheat the tube electrodes. Given that this is a lamp which really isn't designed to be hidden away behind a shade, taking measures like that to minimise blackening around the electrodes would have been commonsense I would have thought.
Light output is pretty good for a 11W lamp, and the usable light is probably a bit higher than in most cases for a very simple reason.
Look at it. Really...Look at it - the whole idea of this lamp is that it's not intended to be hidden away behind a shade. That means of the 680 lumens it produces, they should all be finding their way into the room, rather than several tens of percent behind lost passing through the shade. There's even a special fitting available from the manufacturer which is designed to show it off - basically it's a lamp holder with a cup on the end which encloses the base of the lamp.
As an idea, it is definitely interesting. I have to admit to being very curious to see whether we will see any of the other Plumen designs that I remember seeing on the website years ago on the shelves in the future. I would like to think so certainly.
I reckon that if this was about £5 cheaper and had a ballast designed to look after the tube better that this could be a real success story. It's never going to replace conventional CFLs outright, but I can see a lot of people, especially designers of hotels and expensive homes really having fun with lamps like these.
|Click thumbnails for full size images|
added to the Virtual Display Shelf on the 26th February 2012 at 22:50.
References: Lamp packaging only.
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