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'column of dots LED?'
1999\09\08@120410 by Harold M Hallikainen

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       I'm helping a friend with a project where we're considering
writing info on Polaroid film as it is ejected from the camera.  I'm
thinking a single column of dots LED (maybe 7 to 9 dots) would do the
trick.  On detecting motor start, we could just flash the LEDs (with a
PIC, of course) to put the message on the film, just like an old dot
matrix printer.
       So... anyone have any "column of dots" LEDs as their favorite?

Harold



Harold Hallikainen
spam_OUTharoldTakeThisOuTspamhallikainen.com
Hallikainen & Friends, Inc.
See the FCC Rules at http://hallikainen.com/FccRules and comments filed
in LPFM proceeding at http://hallikainen.com/lpfm

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1999\09\08@141510 by Barry King

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Harold,
>         I'm helping a friend with a project where we're considering
> writing info on Polaroid film as it is ejected from the camera.
Uh... if you *could* expose the film as its being ejected, wouldn't that
let ambient light ruin the image every time?  SX-70 film has an
opacifier (makes the front layer opaque) which gives the
development  time to go to completion, then it clears to reveal the
image.

On standard Land chemistry, there's a peel-off sheet- also opaque.

So.. When are you expecting to expose it?  _Inside_ the camera?

And to answer the direct question, I would check on surface mount
LEDs and put a row of them on the board- the density could be
higher than the standard light bars, if that matters.  The classic DIP
bar-graph packages are 2.54 mm centers (thats 0.1" o' course).

I see surface mount LEDs (Panasonic LNJ208R8ARA in DigiKey)
that are 0.8 mm wide, and could end-stack on about 1 mm centers.
Good luck soldering them though :)

------------
Barry King, KA1NLH
Engineering Manager
NRG Systems "Measuring the Wind's Energy"
Hinesburg, Vermont, USA
http://www.nrgsystems.com

1999\09\08@155324 by Harold M Hallikainen

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On Wed, 8 Sep 1999 14:02:58 -0500 Barry King <.....barryKILLspamspam@spam@NRGSYSTEMS.COM>
writes:

>
>So.. When are you expecting to expose it?  _Inside_ the camera?

       Yes, inside the camera...  So far my friend has managed to stuff
an alphanumeric LCD  in the camera and has it working, sortof.  Really
complicated, and the image is backwards...  So, I thought the column of
dots on moving film might work...

{Quote hidden}

       We also thought of bar graphs and SMT LEDs.  Might end up with
one of those techniques.


Thanks!

Harold


Harold Hallikainen
haroldspamKILLspamhallikainen.com
Hallikainen & Friends, Inc.
See the FCC Rules at http://hallikainen.com/FccRules and comments filed
in LPFM proceeding at http://hallikainen.com/lpfm

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1999\09\08@163710 by paulb

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Harold M Hallikainen wrote:

>   Yes, inside the camera...  So far my friend has managed to stuff an
> alphanumeric LCD  in the camera and has it working, sortof.  Really
> complicated, and the image is backwards...  So, I thought the column
> of dots on moving film might work...

 Yes, obviously if the display is *inside* the rollers, it will act on
sensitive film.  I'd hazard a guess it needs to be well inside the
rollers to avoid the "bolus" of developer, perhaps a quarter to half
inch inside.

 For close resolution, I'd say you still need a matrix display LED, but
on the exit edge of the film rather than over the exposure area and
driven as you imply, one column only in the "air-writer" fashion.
Software determines which way the image appears.

 I presume this is for logging as some non-instant cameras already
provide, and having the image still visible through the display is
wanted.
--
 Cheers,
       Paul B.

1999\09\08@200403 by Peter van Hoof

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How about staggering the led's to increase resolution without complicating
mounting etc , you could mount in a diagonal , z or other pattern

0         0
0         0
0           0
0           0
0             0
0             0
0               0
and do timing with a flag or such on the motor


Peter van Hoof
-------------
.....pvhKILLspamspam.....vertonet.com
http://go.to/pvh

Harold wrote

>         I'm helping a friend with a project where we're considering
> writing info on Polaroid film as it is ejected from the camera.  I'm
> thinking a single column of dots LED (maybe 7 to 9 dots) would do the
> trick.  On detecting motor start, we could just flash the LEDs (with a
> PIC, of course) to put the message on the film, just like an old dot
> matrix printer.
>         So... anyone have any "column of dots" LEDs as their favorite?
>
> Harold

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