Re: Optical Scanner for Music Box Discs
By Robbie Rhodes
Wayne Stahnke notes that ordinary 35mm lenses and film can resolve 100 lines/mm. The image of a music box disk within the standard 24 x 36 mm frame would have 2400 lines across the diameter, or 1200 lines across the radius. I will assume that the central 20% of the radius is blank, therefore 240 lines are blank, leaving 960 lines. If there are 200 channels playing, this results in not quite 5 lines per channel, which is inadequate resolution. High-resolution film and optics, and bigger film for larger images (e.g., 6 x 6 cm) seem to be needed. I doubt very much that the image from Kodak Photo-CD would be usable.
Terry Smythe's idea of microfilm (16mm) camera recording was tested on an Ampico roll, with promising results for making photographic archive records. I believe Richard Tonnesen reported this experiment at a recent AMICA convention.
I originally asked Jack Kane to put a small disc in a photocopying machine and "duplicate" it, but upon further reflection (!) I fear the reflections from the metal disk would be terrible! I like Wayne's idea of back-lighting the disk for photography.
I believe that large flat-bed scanners with a CCD array of 4096 pixels are now available at some service shops. Certainly an optical photocopy machine could reduce a photo print image to fit the flat-bed scanner.
Jim Heyworth correctly notes that the motion of the star-wheel in the music box adds a time delay in inverse porportion to the radius. Correcting for this delay should be an option available in the image conversion program: if the music is to be edited and played via Midi then the delay must be corrected, but if the data is to operate a punching machine there should be no further correction.
Terry Smythe: Your 28-inch Kalliope seems like a representative "big" instrument. What is the channel spacing at the star-wheels? What is the normal rotational speed (seconds per revolution)?
Larry Smith: could you kindly contact Porter Music Box Company and ask their thoughts on these topics? I wonder if Rouge is working on this problem...
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| Robbie Rhodes |
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(Message sent Tue 6 Aug 1996, 14:50:55 GMT, from time zone GMT-0700.) |
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