From: Humphreys, David (david.humphreys_at_honeywell.com)
Date: Mon Jan 31 2005 - 11:01:28 PST
>
> Johannes Wolf wrote:
> > Just to give you a technical hint:
> > In case the BL is really a genuine Newt part, it should come with a
> > connector attached to the wires.
> Victor Rehorst wrote:
> Also, it should come in a bag or box with an Apple Service
> part sticker on it with the appropriate 7 digit part number
> (most Newton parts start with 922-).
And it probably won't have kinks in the cable where it had been fitted
in a unit before - just like the one in the photo...
Of course, that picture is just for illustrative purposes isn't it Ferdi?!
Yawn!!!
Oh, and he incorrectly describes half life as:
"The backlight just like any EL Backlight has a half life. When the Newton
was originally manufactured EL technology was in its infancy. That being
said the life on any Factory Backlight is around 800 to 1000 hrs of use.
This does not mean that you will get 800 hours of useful backlight use
before its becomes to dim to be helpful however. The backlight has a
half-life decay rate. This means that after around 400 hrs of use the
backlight will be half as powerful as it was when you first started using
it. It will continue to degrade in that fashion until your backlight will
simply not turn on anymore."
OK. Now the facts:
EL was developed in 1936. Its use was confined primarily to laboratories
until the early 1960s, when commercial applications such as illuminated
aircraft dials were developed. It was hardly in its' infancy when the Newton
arrived on the scene.
The time to half brightness is more like 3000hrs.
Even using his very conservative 800hr number, it simply means that, all
things being equal, the brightness will be half after 800hrs NOT 400hrs as
he states.
It will be a looooong time before it won't turn on any more. Don't believe
me? Well do the math:
The brightness starts out at about 60 candela
After 800hrs 1/2 bright 30
1600hrs 1/4 bright 15
2400hrs 1/8 bright 7.5
3200hrs 1/16 bright 3.75
4000hrs 1/32 bright 1.875 ~167 days
Using my numbers:
After 3000hrs 1/2 bright 30
6000hrs 1/4 bright 15
9000hrs 1/8 bright 7.5
12000hrs 1/16 bright 3.75
15000hrs 1/32 bright 1.875 ~625 days
In any case, this is for a continuous usage. In practice, it will be much,
much longer.
And after 15000hrs the brightness is still almost 2 candles. Still visible
across a room.
The point is that the light output decays exponentially. It won't just shut
off one day like a light bulb.
PCBman
-- This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries Official Newton FAQ: http://www.chuma.org/newton/faq/ WikiWikiNewt for all kinds of articles: http://tools.unna.org/wikiwikinewt/
This archive was generated by hypermail 2.1.5 : Mon Jan 31 2005 - 11:30:00 PST