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Thorn F40T12-640 Half Coated

Thorn F40T12-640 Half Coated

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Linear Fluo tube half coated with calcium halophosphate material. Note how the interior brightness of the phosphor coated region is significantly greater than the exterior surface of the tube. This is partly due to internal reflection but also due to the absorption of visible light by the thickness of the phosphor coating.

There is a critical optimum to the phosphor coating weight for each type of tube. If too thin, there will not be sufficient material to convert the UV to visible light. However if the coating becomes too thick it will begin to absorb the visible light generated near to the inner surface of the tube, resulting in a drop in efficacy.

IMG_5718.JPG D FL Philips TL20W-08 end.jpg IMG_3646.JPG Thorn_F40T12-640_Half_Coated.jpg

Light Information

Light Information

Manufacturer:Thorn EMI
Model Reference:F40T12CW
Lamp
Lamp Type:LFL
Base:G13
Electrical
Wattage:40W
Current:0.41A
Physical/Production
Dimensions:4' T12
Factory Location:Enfield, North London
Fabrication Date:1979

File information

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Filename:Thorn_F40T12-640_Half_Coated.jpg
Album name:James / Fluorescent
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Keywords:Lamps
File Size:23 KB
Date added:May 25, 2008
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Date Time:2008:05:16 19:15:21
DateTime Original:2008:05:16 19:15:21
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Make:SONY
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Comments
monkeyface
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May 25, 2008 at 09:14 AM Author: monkeyface
It looks similar to my bended T8 36W LAZZURO lamp. Nice photo indeed.
FGS
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May 25, 2008 at 01:40 PM Author: FGS
You can see this effect on standard coated lamps too. Just look into the holes on the endcaps if the lampholder allows. Some of them have a thin clear band near the caps where you can see the inner coating of the phosphor.

Nice pic BTW.

Why I like LEDs on top of other lighting tech?
LEDs = Upgrade 95% of the applications. (That is if you avoid eBay's LEDs).


LED brainwash? No, people uses them cuz they work well for them.

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Apr 05, 2009 at 11:58 PM Author: Medved
And this is the reason, why spirals will always considerably lag behind linear tubes in their efficacy - due to so complex shape it's not possible to make evenly distributed phosphor layer, so somewhere it would be too thick, somewhere too thin... Or if the phosphor would be deposited before twisting, it would be damaged by the hot forming operation, so again low efficacy...

No more selfballasted c***

James
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Apr 06, 2009 at 03:22 PM Author: James
Traditionally yes that's right about the spirals. Although Megaman has solved the problem some six months ago As a consequence they are now re-tooling their production to make the shift from U-tube to spiral lamps of smaller dimensions - and impressively without any loss of luminous efficacy.
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Apr 07, 2009 at 11:19 AM Author: Medved
I would like to see the result. May be they shift the efficacy to level where U-tubes were, but even this is not impressive at all - linear T5HE in 20W range has >90lm/W, while multiple U-tube CFL has no more then 70lm/W. And (my guess) doing same improvements on linear tube (e.g. T5HE) manufacturing process might lower their phosphor deposition tolerance, so boost even their efficacy higher - and again, spirals loose after linear...
You might improve the technology for complex shapes, but using such improved technology on simple shapes will always give better results... And i'm convinced, this is the way to go.
Instead of wasting effort on crappy concept, where the nature is in every aspect in opposition, use such effort, where the nature is a bit more in favor, so much more effectively. I think, now is the time for fixture designers - they have to come with affordable fixtures for linear lamps (= today's most efficient technology in home-rated light quality and quantity), aesthetically suitable for e.g. traditional living room. Here is very huge gap...

No more selfballasted c***

rjluna2
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Robert


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Aug 24, 2011 at 06:02 PM Author: rjluna2
The idea of clear coated spiral bulb is not new. Here is a couple of flourescent lamps in my collection in use that was made in the late 1950's posted at K°oloratec and Nuleco.

Pretty, please no more Chinese failure.

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Oct 25, 2013 at 09:00 PM Author: LandryB
I used to think, the thicker the phosphor the better. Should you be able to see the arctube through the phosphor when lighted?
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Oct 26, 2013 at 01:22 AM Author: Medved
@LandryB: Thicer phosphor mean more of the UV is converted. But as any other matter, the phosphor layer block some of the light, so thinner layer mean less light get blocked, so more pass through. So from this aspect the thinner layer the better...
So there is an optimum, where enough light is generated by the conversion, yet not too much of it is blocked. And more efficient lamp you want, you have to be closer to that optimum across the whole lamp surface. So you should be able to deposit as accurate layer thickness as possible. And the first step for this is to achieve as even distribution over the surface as possible.

No more selfballasted c***

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Oct 26, 2013 at 02:29 AM Author: Kappa7
I've found some time ago an interesting research about the effect of the phosphor thickness on tri-band tubes:
http://www.epqu.agh.edu.pl/archives/journal/v11i1/558.pdf
F96T12 DD VHO
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Alex//I love both Iceland and CO


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Jul 27, 2018 at 05:26 PM Author: F96T12 DD VHO
I saw this on google many times when I searched "Half Coated Fluorescent"
I could probably make this

Fluorescent Lamp T12/T17 Fluorescent Lamp
Snapchat: EvanT12/Dj I.D. I can conduct 120VAC
High Pressure SodiumMercury Vapor LampHigh Pressure Sodium
Şetta er Mackenzie eğa F96 GF, ég elska lısingu og mun skjóta upp á LG sem Kenzie
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220V AC 50Hz


UCOUT2noI2R__jgPSJUjGRtA
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Jul 11, 2019 at 10:45 PM Author: Binarix128
What is the porpuse of this lamp?

-I dont speak English very well. Compact Fluorescent (PL)
-Say NO to incandescent bulbs ban! Incandescent Lamp
-lamp saver Mercury Vapor Lamp

dor123
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Jul 11, 2019 at 11:38 PM Author: dor123
For demonstration purpose.

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the European date format (dd.mm.yyyy).

I lives in Israel, which is a 230-240V, 50hz country.

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