Patent ID: 6091446
Filing Date: 2000-07-18
Classification: H04N

Abstract:
A method for detecting an error condition of a web of material passing over a capstan connected by way of said web of material to a sprocket, comprising:(a) measuring a velocity and a rotational phase of said captain at a given time, wherein the velocity and rotational phase of said capstan is measured by an associated biphase tachometer producing at least two pulse streams approximately 90.degree. out of phase; and has(1) a first multibit counter, said counter being driven by a clock having a substantially constant predetermined frequency; and(2) a first multibit register connected to a microprocessor, said first register reading the instantaneous count of said first multibit counter upon receipt of a signal from said tachometer and transmitting said count back to said microprocessor, wherein said microprocessor compares said count with a next previously stored count to determine the velocity of the capstan;(b) measuring a velocity and a rotational phase of said sprocket engaged in said web or material having holes engageable by said sprocket; and(c) comparing velocity and rotational phase of said capstan to the velocity and rotational phase of said sprocket for detecting the existence or lack of existence of an error condition.