Reply by DaveC October 22, 20112011-10-22
> I really have no help for the question asked, but I think people > interested in the subject may have an answer to one of my questions.
And I have one word for you: HIJACK. If you don't have an answer to the OP's question, fine. If you have a question, START YOUR OWN THREAD.
Reply by DaveC October 22, 20112011-10-22
> Most white LEDs are phosphor-based but hardy as bi-chromatic as you make > them sound. The little Cree in my pocket flashlight has the typical > broad peak around 450 nm and valley around 485 but it's quite continuous > down to 650, tailing off at about 670. Very different from the narrow, > discrete lines from a CCFL.
[Rich Webb] Thanks, Rich. I think the "striping" issue and potential variance between samples will make for a less-than-satisfying result. Thanks, Dave
Reply by DaveC October 22, 20112011-10-22
> "White" LEDs are actually blue LEDs with a phosphor that glows yellow under > blue light. The eyes sees blue + yellow = white. > > Their spectrum is anything but continuous -- or even peaked at the right > points -- so it's highly unlikely to work.
I appreciate your simple and obviously knowledgable answer. It will help me in my search for the right decision. Dave
Reply by Loonie October 20, 20112011-10-20
spamtrap1888 wrote:
> On Oct 14, 2:49 pm, Paul Conners <pconner...@gUSmail.com> wrote: >> Would like to find white SMD LEDs suitable for use as backlight for LCD >> monitors where the CCFL lamps have burned out. So need is for consistency >> between units and... well, "whiteness". ;-) >> >> Or other parameters I should be considering? >> >> Any recommendations (ie, LEDs you think would be good for this)? >> >> (And yes, I can Google and have.) >> > > While we're at it I'd like a digital "film back" for my Nikon 35 mm > camera.
Three cheers for that. I am looking for one for my Canon A1 and for my Zeiss Ikon. Is there any movement towards these backs? TIA
Reply by Rich Webb October 15, 20112011-10-15
On Sat, 15 Oct 2011 09:58:38 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

>"White" LEDs are actually blue LEDs with a phosphor that glows yellow under >blue light. The eyes sees blue + yellow = white. > >Their spectrum is anything but continuous -- or even peaked at the right >points -- so it's highly unlikely to work.
Most white LEDs are phosphor-based but hardy as bi-chromatic as you make them sound. The little Cree in my pocket flashlight has the typical broad peak around 450 nm and valley around 485 but it's quite continuous down to 650, tailing off at about 670. Very different from the narrow, discrete lines from a CCFL. -- Rich Webb Norfolk, VA
Reply by William Sommerwerck October 15, 20112011-10-15
"White" LEDs are actually blue LEDs with a phosphor that glows yellow under
blue light. The eyes sees blue + yellow = white.

Their spectrum is anything but continuous -- or even peaked at the right
points -- so it's highly unlikely to work.


Reply by Salmon Egg October 15, 20112011-10-15
In article 
<0001HW.CABDFC87000B6522B02069DF@news.eternal-september.org>,
 Paul Conners <pconners98@gUSmail.com> wrote:

> Would like to find white SMD LEDs suitable for use as backlight for LCD > monitors where the CCFL lamps have burned out. So need is for consistency > between units and... well, "whiteness". ;-) >
I really have no help for the question asked, but I think people interested in the subject may have an answer to one of my questions. I have a relatively new Samsung LCD monitor using LED back lighting. When the computer is not providing a signal, such as waking from sleep, I see a speckling or snow rather than steady background light. I have two competing explanations. 1. The LED light is sufficiently spatially coherent to generate "laser speckle." For example, you can see colored speckle in your fingernail when illuminated by the sun. At one time I saw laser speckle from a noble gas laser providing a mixture of lines that gave white looking light. 2. With no signal, the noise in the video line was amplified in the monitor circuitry. The display was presenting this as a fine churning snow. When the computer finally was sending a signal, the pixels were either fully on or fully off. Does anyone have bette insight on this matter than I do? -- Sam Conservatives are against Darwinism but for natural selection. Liberals are for Darwinism but totally against any selection.
Reply by N_Cook October 15, 20112011-10-15
Paul Conners <pconners98@gUSmail.com> wrote in message
news:0001HW.CABDFC87000B6522B02069DF@news.eternal-september.org...
> Would like to find white SMD LEDs suitable for use as backlight for LCD > monitors where the CCFL lamps have burned out. So need is for consistency > between units and... well, "whiteness". ;-) > > Or other parameters I should be considering? > > Any recommendations (ie, LEDs you think would be good for this)? > > (And yes, I can Google and have.) > > Thanks, > Dave >
I take it you will replace the 2mm or so diameter CCFL with a line of LEDs . The tube is uniform illumination along its length, how will you avoid stripiness of illumination? It is very sophisticated dispersion sheets backing the display to make sure no graduation of illumination across the width of those sheets.
Reply by Jeff Liebermann October 15, 20112011-10-15
On Fri, 14 Oct 2011 14:49:43 -0700, Paul Conners
<pconners98@gUSmail.com> wrote:

>Would like to find white SMD LEDs suitable for use as backlight for LCD >monitors where the CCFL lamps have burned out. So need is for consistency >between units and... well, "whiteness". ;-)
I'm going to be doing this in about a week when the parts arrive. <http://www.lcdparts.net/howto/LEDBACKLIGHT_MOUNT.aspx> <http://www.lcdparts.net/panelledkit.aspx> <http://www.lcdparts.net/LB.aspx> <http://www.lcdparts.net/UB.aspx> <http://www.lcdparts.net/XB.aspx> <http://www.lcdparts.net/panelledkit.aspx> <http://www.instructables.com/id/LED-Backlight-for-Your-LCD-Monitor-or-Television/> Plenty more found with Google.
>Or other parameters I should be considering?
You should consider disclosing the maker and model of LCD monitor you're modifying. You're going to have problems with getting consistent white. The color will NOT be the same as CCFL, but close enough to be useful. The better LCD backlit TV's use individual colored LED's, with a optical filter/phototransistor combination to adjust the intensity of each until it looks white. What happens is that different color LED's fade at different rates. Without feedback, the backlighting would slowly turn red/orange.
>Any recommendations (ie, LEDs you think would be good for this)?
Nope. No maker and model number, no specifics.
>(And yes, I can Google and have.)
The key words are "led strip light" and "CCFL replacement". -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com jeffl@cruzio.com # http://www.LearnByDestroying.com AE6KS
Reply by Dennis October 15, 20112011-10-15
"spamtrap1888" <spamtrap1888@gmail.com> wrote in message 
news:9bb7dae8-b77f-449f-9306-a50e984b97fd@v8g2000pro.googlegroups.com...
On Oct 14, 2:49 pm, Paul Conners <pconner...@gUSmail.com> wrote:
> Would like to find white SMD LEDs suitable for use as backlight for LCD > monitors where the CCFL lamps have burned out. So need is for consistency > between units and... well, "whiteness". ;-) > > Or other parameters I should be considering? > > Any recommendations (ie, LEDs you think would be good for this)? > > (And yes, I can Google and have.) >
While we're at it I'd like a digital "film back" for my Nikon 35 mm camera. =============================== Can you get them?