Browse Prior Art Database

Belt Edge Detector

IP.com Disclosure Number: IPCOM000051348D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Helinski, EF: AUTHOR

Abstract

Belt 10 is a continuous moving character belt of the type used in line printers. Belt 10 is preferably metallic bearing etched characters and timing marks precisely located relative to the bottom edge 11. Edge 11 is detected and shifted vertically for precisely locating the vertical position of the characters as they move along a print line. Edge 11 is located in gap 12 of a stationery magnetic core of a detector which includes transmitting coil 14 on pole 15 and receiving coil 16 on pole 17. Coil 14 is energized with a high frequency signal (e.g., 1 megahertz). With high frequencies the presence of the belt edge in gap 12 results in a much larger percentage change in the output voltage from coil 16 than when operating at lower frequencies.

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Belt Edge Detector

Belt 10 is a continuous moving character belt of the type used in line printers. Belt 10 is preferably metallic bearing etched characters and timing marks precisely located relative to the bottom edge 11. Edge 11 is detected and shifted vertically for precisely locating the vertical position of the characters as they move along a print line. Edge 11 is located in gap 12 of a stationery magnetic core of a detector which includes transmitting coil 14 on pole 15 and receiving coil 16 on pole 17. Coil 14 is energized with a high frequency signal (e.g., 1 megahertz). With high frequencies the presence of the belt edge in gap 12 results in a much larger percentage change in the output voltage from coil 16 than when operating at lower frequencies.

Receiving coil 16 is a multiple-layer coil tapped at a precise location 18 with lead 19 connected to the lead 20. In a specific embodiment, receiving coil 16 was wound by starting with the lead 20 and winding multiple layers of insulated wire. Coil 16 was tapped at point 18 with lead 19 at the tenth layer (961 turns) and then wound to a total of 1,500 turns terminating in lead 21. Leads 20 and 19 were connected together, and the potential difference between this connection and lead 21 was viewed on an oscilloscope.

Transmitting coil 14 was connected to a sine-wave generator which applied 25 volts peak to peak at 1 megahertz. The voltage signal obtained from receiving coil 16 was approximately 6 times greater than any other way that any of the three leads could be combined. This connection represents a tuned condition.

When belt 10 is placed in gap 12, the output signal from receiving coil 16 drops to a lower value. The output voltage is dependent upon the vertical position of edge 11 within gap...