In reference to the patent: US5222141
Maintaining a patent costs money. Those fees have to be paid regularly or the patent "dies".
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So this is what is occurring? Sep 11, 1996 FPAY Fee payment Year of fee payment: 4 Sep 29, 2000 FPAY Fee payment Year of fee payment: 8 Sep 29, 2004 FPAY Fee payment Year of fee payment: 12 – M Killian Dec 14 '16 at 20:06
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