Look what I've found while browsing the net. That guy has designed an electronic ruler using an Arduino board. It looks quite cool. http://www.shayshafranek.com/index.php?/products/electronic-ruler/
What a great idea! I wonder how accurate it is?
it's just a concept right? as in, it's never actually been created in real life? good idea, but how would one make the ruler sensitive to touches and be able to determine at what distance from the edge (0) was it's side touched? some sort of linear touch potentiometer?
Well there is no details of the design that I could see. I assumed it was using optical emitter and sensor pairs that count up the passing of the pencil point as the line is being drawn. If so the accuracy would be that of the number of sensor elements embedded in the ruler's edge.
That would also require someone to draw a line down the side of the ruler... but what if you simply wanted to measure out a distance? then you need to just press one point, rather than draw a line.
Sorry for double post... but this is what I found... infact, something like this might be the ticket for creating what we've been discussing:
I assumed it was using optical emitter and sensor pairs
Maybe one of those linear pot strips, like this?
clearly, you didnt read the post(s) above.
It's just a concept right? as in, it's never actually been created in real life?
Well no, there is a picture of a PCB with an Arduino mini and if you search a little there is a picture of the guy testing a board.
I assumed it was using optical emitter and sensor pairs that count up the passing of the pencil point
On the picture it seems that he is using a 2 row right angle header. The pencil makes contact between the two rows.
is apencil that conductive? or is it a special pencil (to be honest, looks like some sort of pen to me)
Pencil lead is a clay and graphite mixture. Graphite is conductive.
That looks like a biro in that pic and the end is obviously conductive... Cool project though. I might have to try that at some point. Obviously it is limited in accuracy of 0.1 inch (0.254mm) because that is the normal spacing between the pins. I presume he is using inches...
the "screen" looks great, it's a neat idea, but with only a 0.05inch of precision it is useless... wonder what kind of sensor could be used to improve this...
edit: seems there's two row of interleaved pins, resulting in 0.05inch and not 0.1... still not enough in my opinion...
I think that's really nice. The precision would only need to be about twice as much to be as good as reasonably practical for pencil drawing (at least for me). Perhaps a custom PCB could do the trick.
looks verry nice
the “screen” looks great, it’s a neat idea, but with only a 0.05inch of precision it is useless… wonder what kind of sensor could be used to improve this…
edit: seems there’s two row of interleaved pins, resulting in 0.05inch and not 0.1… still not enough in my opinion…
With only 3 numerical characters on the ‘display’ the best precision can only be 0.1 unless it rounds which would be pointless, or it is a higher precision at lower values.
You can also get obscure pin headers at 1mm spacing which he may be using because I doubt that you would ever be counting 22.1 inches on a ruler that size…