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MMD > Archives > February 1999 > 1999.02.03 > 06Prev  Next

Advantages of Optical Reader
By Spencer Chase

The list of complaints that Craig Brougher mentions with respect
to roll readers is interesting, as my roll reader has none of these

> But in any kind of roll reader, each system has its problems.  With
> scanners, a problem might be roll tracking and very dark words on
> the roll, tears in the edges, different kinds of tape repairs, and
> failure to keep track of the roll position in time, accurately, and
> optical resolution and distortion.

The edges can be torn to shreds and it doesn't matter.  Anything that
passes air will pass light and anything that blocks light other than
optical quality clear tape will look like paper to my scanner.  The
light is transmitted through the paper so the paper is "black."  Dirt
and printing don't matter.

The paper is advanced with a friction drive by a stepper motor and
moves a precise amount for each scan line.  The tracking is auto-
matic and the paper wanders less than .02" while reading.  This
wander is largely due to warped paper.  Good paper wanders much
less.  The contact image sensor has very consistent optics and does
not get out of alignment.  Any errors are fixed and can be corrected
in software.

The most important point is how the old failing rolls can be read
or transcribed without damage.  I have many rolls that will not read
pneumatically on my piano.  The paper is too warped or the bridging
split or the edges gone or the paper stretched to the point that not
all the holes line up.  How do you read these rolls pneumatically?
Just to take the warp out so that you can get good contact with the
tracker bar can tear the rolls.

I have always had to make excuses for these rolls -- "This is a
wonderful roll but you have to ignore the ten false notes caused
by warped paper in the subtle part near the end."

Now I can read the roll and play it perfectly.

Spencer Chase

(Message sent Tue 2 Feb 1999, 09:42:52 GMT, from time zone GMT-0800.)

Key Words in Subject:  Advantages, Optical, Reader

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