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Background: Our Bell & Howell printer control units originally used paper tape to store FCC & RGB information. There were many methods before this such as notching and electrostatic. Paper tape replaced these and originally worked by advancing the tape every cue because the control units lacked memory. With the PCM units, memory was added and a quadrature encoder was added to the main drive motor for position reference. With the later generations the holes in the paper tape were sensed by IR LED rather than mechanical fingers, that is when the paper tape switched to being black rather than yellow to block light transmission.
2D Barcode Paper Tape Replacement
Problem: As stated before, the printers we have used IR sensors and 8 bit paper tape. Paper tape has its good points, the biggest being it can easily be placed in the can with the film and stored so reprints can be easily done. However, there are many problems. The tape punches would dull and leave paper fibers or hanging chads. Also the transmission and receiving holes for the IR LED were very small and would get clogged. The PCM units do not have any error correction or complex validation. A paper tape could appear to load fine, however the values were wrong or in some cases it would take many tries to load the tape into the printer memories.
Solution: 2D barcodes. A micro controller was added to the PCM modules to emulate a paper tape. 2D barcodes can be printed on any paper and could be stored like a paper tape with the film in the can. The barcode reader also has error correction so the proper values are assured to be loaded. The connecter from the micro controller was created to use all the original harnesses so restoring the tape reader is plug and play. A separate tape to barcode reader had to be created for older jobs still with paper timing tapes. A PC application was developed allowing for paper tape to barcode conversion as well as editing and other features. The film analyzer developed was also able to be updated to print these barcodes.
Bell & Howell printer paper tape specifications.
(Click picture to enlarge)
Left: Bell & Howell printer control module. Upper Right: Paper tape reader. Lower Right: Paper tape. (Click pictures to enlarge)
Left: 2D barcode reader. Right: Our current timing sheets with 2D barcodes. (Click pictures to enlarge)