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MMD > Archives > February 1999 > 1999.02.01 > 19Prev  Next


Sensing Reflectance With Fiber Optic Array
By Bill Chapman

I have been enjoying the abundance of ideas on roll reading.  When
looking at some of my favorite rolls crumbling (Ampico Yankee Rose,
The Clock on the Mantel), the variety and wealth of ideas is most
welcome.  Even if some of the pneumatic methods have need more software
correction they are valuable ideas that just may become useful in the
hobby.  And who knows, we may be some day playing old worn rolls in
real time, reading the lyrics while being sensed by a devise that
doesn't put wear and tear on the roll.  Then the proof will be in the
listening and the minor errors may never be noticeable.

My own variation was to insert optical fibers from behind the tracker
bar and terminate them in a lower corner of each tracker opening.
A light source and optical sensor would sense light reflected when a
paper was present, but not reflect when a note-hole passed by the tip
of the fiber.  The roll could be run at any speed needed.  The piano
would have the dynamics switched off to minimize the slowdown on loud
passages and near the end of the roll when it begins to slip.  The
output from the sensors could be sampled just as a synth keyboard or
typing keyboard is sensed.  Then the software editing would begin.

This method could also be modified by drilling tiny holes in the
tracker bar -- each hole corresponding to the existing air-hole.  The
position above or below wouldn't matter.  In that way the optical fiber
would not cut down on the flow of air in the tracker hole (if it was
significant).

I once gave thought to copying a roll by running it through the blue
print machines (Ozalid?) of yesteryear.  What mess that would have
been!  Cutting the holes would have taken a lot of patience.

Bill Chapman -- AMICA Memberships --

 -- reminding the 419 unpaid AMICA members to get those 1999 dues in
the mail if you haven't done so already.  Check with me first as 49
eager people are paid ahead through the year 2000!


(Message sent Mon 1 Feb 1999, 18:39:12 GMT, from time zone GMT-0800.)

Key Words in Subject:  Array, Fiber, Optic, Reflectance, Sensing

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