Hacking the Fluorescent Light

DynaSoar writes "MSNBC reports on an elegant hack performed on the common fluorescent tube. By mixing phosphorescent material with the usual white fluorescent material, American Environmental Products has developed a tube that continues to glow when shut off. Originally intended for submarines, and then used in places where terrorists could disrupt services, they are also perfect for power outages, providing some light so you don't have to thrash around in the dark looking for your candles and flashlights. Since the 'hack' is inside the tube, they can also be removed from their fixtures and carried around, as well as provide light even if they're shattered."

Re:Bleh

[rustbear]

What is this "war on terror" that you speak of? Ahhh... I bet you mean the "struggle against violent extremism"...

http://www.iht.com/articles/2005/07/26/news/terror .php [iht.com]

http://www.cbsnews.com/stories/2005/07/27/opinion/ smith/main712317.shtml [cbsnews.com]

Found the patent

[GoNINzo]

There's more detail on what he's doing with Patent 6,917,154 [uspto.gov]. It's definately not a hack, it's just a new (and obviously expensive) process. Interesting quote:
The after-glow phosphor of the scotopic after-glow lamp of the present invention is selected with a hyperbolic decay rate dropping to approximately ten (10%) percent of its initial brightness in about six minutes and to one-tenth that in an hour.
Anyway, read up, interesting stuff.

Have had them in Japan for years...

[CaptainBogus]

I have one in my bedroom here in Japan for the last four years. It is a ring florescent tube that glows like a night light after the light goes out. The light is made by NEC and is called Hotarukku (a play on the word hotaru, which is Japanese for firefly). It seems they launched the product in March 2000. http://www.nelt.co.jp/navi/la_shg/fre_shg.htm [nelt.co.jp] (Japanese) gives specs and has some pics showing the room lit with the light on and off.

Re:Light Sabres !

[cdrudge]

According to the end of the article, they've already done it...well...maybe not lightsaber quality but at least enough to survive a hammer impact.

Gas is *not* harmless ...

[jonathanweaver]

The vapour in fluorescent tubes is mercury (Hg). Very bad to breathe, and perilous to touch too (unless you wash hard, and even potent cleansers aren't designed to remove heavy metal contamination).

That's why they need phosphorescent coating in the first place: the excited Hg vapour emits UV, and it's actually the phosphors that 'fluoresce' visible EM.

Competent safety procedures include vacating the area of a fluorescent bulb break for at least ten minutes, followed by thorough cleanup and HAZMAT disposal of the materials used.

Re:Extra UV

[NormalVisual]

So by effectively putting the UV strips inside the tube, you charge them up when the light is on. You'd have to cover the walls with UV strips to get the same effect outside the lamp.

You still won't get a comparable effect - the phosphor and glass envelope does a pretty good job of filtering the UV such that only a fraction is radiated out into the room. Having the phosphor inside the tube exposes it to a *much* higher UV level, and most phosphorescent compounds respond a whole lot better to UV than to visible light. Compare how much brighter a glow-in-the-dark item is after exposure to a UV-rich blacklight vs. a regular incandescent or fluorescent lamp.

Re:RTFA already

[Dun Malg]

After reading the tedious patent, apparently they are using strontium aluminate, not zinc sulfide. The toxicology on strontium aluminate is "This product is non-toxic". It's also reactive only with acids, and doesn't burn. Basically, about as hazardous as dirt.

Re:Light Sabres !

[Anonymous Coward]

That's just a rubber type coating. It prevents the glass from scattering all over the place, but the glass still breaks. This is nothing new, shatter-"proof" lights are used in many applications.

It does not prevent the glass from breaking, it just encases the glass so it can't go anywhere and cause injury.

Re:RTFA already

[Dun Malg]

Except that strontium IS radioactive

No, the isotope Strontium-90 is radioactive. "Regular" Strontium is not.

(and used in french toothpastes for sensitive teeth, for some reason. French sensodyne brand toothpaste works much better than English sensodyne brand toothpaste, but the English sensodyne brand toothpaste isn't slowly killing you...)

Strontium chloride is about as dangerous as table salt. You really ought to research things rather than drawing half-baked conclusions from inaccurate data.

Re:Found the patent

[dnamaners]

Heres a brief overview for those that hate to read patent apps.

The word "scotopic" you seen in the app. refers to reduced illumination or reduced completeness of the wave lengths of light used to make white light. If I have "scotopic vision" it means I can function in low light.

summary:
These guys mixed up a set of additional phosphors that that they blended to produce this afterglow effect and tuned ti to be a nice green(sense human eyes are most sensitive to green) so you won't notice the slow reduction of glow over time. The bulbs have about a "hyperbolic decay rate dropping to approximately ten (10%) percent of its initial brightness in about six minutes".


some of the phosphors used:
Sr4AL14O25: Eu Dy (powere on phosphor)
(Sr Mg)3 (PO4): Sn
Mg WO4: W
Ca WO4: Pb
SrO (P2 O5 B2 O3): Eu
Y2 O3: Eu
La PO4: Co, Tb
Sr2 P2 O7: Eu
Ba Mg2 Al16 O27: Eu


construction and function:
Phosphors (I assume many or all of the above but I may be mistaken) are layered up in the tube as a chalky composite material and coated with aluminum oxide to prevent flaking off the walls. The after glow phosphors are coated on the outside of the tube, "the spray-on after-glow phosphor coating is slightly noticeable and causes only a slight decrease in normal lumen output". As someone surmised these phosphors absorb light from the tube as it is powered up and the greater light intensity in the tube is that which makes such a high density of phosphors useful and possible to so highly charge. These may well be similar phosphors to those found in glow plastics but I can not say for sure, however, they do work similarly. These tubes work on the older standard of operation, ie they are the wide mercury containing tubes, not the thin ones that don't have Hg that you have to use in the USA in new installations these days.

enjoy

I've had something like this for a while

[Anonymous Coward]

I bought a blue compact fluorescent bulb a while ago for no particular reason. When switched off, the bulb continues to glow perceptably for a couple minutes. It's not bright enough to light up the room, but it looks really weird. I hope the bulbs mentioned in the article, which I haven't read, glow a little brighter.

Re:RTFA already

[deglr6328]

The SrxAlxOx is not the important part though. It is what is DOPED into the strontium aluminate that is important. Note that is says Sr4AL14O25: Eu Dy. That means dysprosium and europium are doped [theodoregray.com] into the matrix of strontium aluminate. THESE are the important dopants which are responsible for the extremely long phosphorescent glow times.

Re:wait a minute...

[Anonymous Coward]

... they should at least find you handy.

Parent should be "+5 Red Green Reference"!

Re:No more flickering!

[cswiger2005]

A good fluoresent bulb shouldn't flicker, but older ones sure did, and yeah, they give lotsa people headaches.

The thing is, the older bulbs tended to just have one phosphor (ie, would be either a reddish tint, or a pale blueish tint), and you were supposed to mix and match tubes to have some of both lighting the area to sort of blend into a neutral white.

Those sort of bulbs look like crap, IMO, but newer tubes combine both phosphors and produce something closer to a normal white light, which is easier on the eyes and a lot less annoying.

All of this being said, I'd rather use halogen, except for the heat. This being summer and all, a ~20W fluorescent bulb beats the heck out of a 100W incandescent, or a 300W halogen in terms of not heating the room up....