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Transducer Shielding for Impact Printer Platen

IP.com Disclosure Number: IPCOM000034696D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Jessen, RF: AUTHOR [+2]

Abstract

Improved shielding of signal lines or electrodes for ribbon-style piezoelectric impact transducers on printer platens can be achieved with non-conductive wear strips by providing commonly grounded shielding films over both signal lines on opposite surfaces of the transducers. In Fig. 1, impact transducer strip assembly 1 is supported in groove 2 of metal platen base 3 in a printer. Transducer assembly 1 is covered by non-conductive wear strip 4 and produces individual output voltage signals when struck by respective hammers 5. Hammer approaches and departures induce erroneous signal levels on the transducers due to carried charges. These charges can be nullified by shielding the transducer signal lines. Transducer assembly 1, shown in greater detail in Figs.

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Transducer Shielding for Impact Printer Platen

Improved shielding of signal lines or electrodes for ribbon-style piezoelectric impact transducers on printer platens can be achieved with non-conductive wear strips by providing commonly grounded shielding films over both signal lines on opposite surfaces of the transducers. In Fig. 1, impact transducer strip assembly 1 is supported in groove 2 of metal platen base 3 in a printer. Transducer assembly 1 is covered by non-conductive wear strip 4 and produces individual output voltage signals when struck by respective hammers 5. Hammer approaches and departures induce erroneous signal levels on the transducers due to carried charges. These charges can be nullified by shielding the transducer signal lines. Transducer assembly 1, shown in greater detail in Figs. 2 and 3, includes a strip of piezoelectric film 6, usually polyvinylidenedifluoride (PVDF). This film is coated on opposite surfaces with silver ink signal lines 7 and 8 and respective polyester insulator films 9 and 10. Shielding is accomplished by adding silver ink conductive layer 11 and its protective, insulative polyester layer 13 to film 9, and silver ink conductive layer 12 and its protective insulative polyester layer 14 to film 10. Shielding layers 11 and 12 are connected by conductive rivet 15 that passes through all layers as shown in section Fig. 3. Care is taken to avoid shorting the shielding to signal lines 7 and 8. Protective layers 13 and 14 may...