Hi,

Thanks for everyone's input on this and please one more thing before I =
let this drop just for my understanding.

Just looking at the ad for the waving pen that spells out something and =
reading everyone's input on the subject comparing it to a dot matrix =
printer it makes sense to me that the timing of the lights has to be =
synchronized with the position of the wand in space. =20

So would this mean that in the light pen wand thingy that there is some =
sort of tilt mechanism there that synchronizes the lights with the speed =
it is waving back and forth?

-----Original Message-----
From: pic microcontroller discussion list =
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Howard Winter
Sent: Sunday, May 23, 2004 12:30
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] Single Row of LED's Illusion - How they do that?

Lindy,

On Sun, 23 May 2004 12:11:15 +0200, Lindy Mayfield wrote:
>...<
> Sorry, perhaps I wasn't specific about my "idea".  (-:  I meant I =
thought I could maybe do one where you
have to look at it and shake your head NO! over and over to read it.

No, because although you move your head, your eyes will fix on the spot =
you are looking at - it's really
difficult to get your eyes to scan past something without stopping on =
the way, so all you'd see is a vertical
row of lights varying in intensity.  It's a physiology thing - our eyes =
don't work well when they're moving,
so you actually move them in stops & starts, however hard you try to do =
it smoothly.

Added to which you'd have to "scan" at the right rate, and syncronised =
with (say) the display of the start of
the characters, and you'd have no way of doing that.

It works exactly the same as a television scan (although with all the =
rows active at once, rather than
sequentially downwards on a television).  If the horizontal scan drive =
failed on a television so you had just
a vertical line, there's no way you could see the picture by waving your =
head about!  :-)

Cheers,

Howard Winter
St.Albans, England

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