Lexmark International, Inc.

Darrel Lee Henry

Michael Anthony Marra, Iii

Randall David Mayo

Thomas Jon Eade

Duane Edward Norris

Samuel William Gardiner

Jimmy Daniel Moore, Jr

Frederick Charles Griesemer

John W Douglas

A method for generating a reference signal for use in an imaging apparatus having an encoder system that supplies an original encoder signal includes selecting one of a plurality of encoder signal conditioning algorithms corresponding to a plurality of desired functions, each encoder signal conditioning algorithm of the plurality of encoder signal conditioning algorithms being directed to facilitating a specific predefined function of the plurality of desired functions relating to a modification of the original encoder signal; reading values into the selected encoder signal conditioning algorithm to generate at least one programming parameter; and programming a hardware reference unit using the at least one programming parameter to generate a synthesized encoder signal representing the modification of the original encoder signal.

Method for generating a reference signal for use in an imaging apparatus

A method for operating a device (such as a printer) having a first interface (such as USB interface) connectable to a first computer and a second interface (such as an Ethernet interface) connectable to a second computer. A phase lock loop (PLL) circuit is obtained which is driven by a clock source, which is adapted for switching between operating at the first and second clock frequencies, and which is operatively connected to the first and second interfaces to provide a clock signal to the first and second interfaces. The PLL circuit is operated at the first clock frequency when the first interface is active and is operated at the second clock frequency when the second interface is active. A device includes the first and second interfaces, the PLL circuit, and the clock source.

Providing different clock frequencies for different interfaces of a device

An improved ink jet printer is provided in which its carrier position and velocity information is derived from a linear optical encoder mounted on the carrier, which produces the position information uses a quadrature output signal, and one of the channels of that output signal is used to determine &ldquo;critical edge&rdquo; transitions used to provide the actual print fire timing. Two adjacent encoder periods are needed to determine the acceleration of the carrier. By measuring the time intervals of these two encoder periods, and measuring the difference between these time intervals, the present invention provides correction logic that can determine if the second of the two measurements has been corrupted by motion not relative to carrier speed across the print media. If the difference between the previous two periods is greater than a preset maximum, the correction logic will limit the new encoder time (i.e., for purposes of fire pulse width calculation) to the old encoder time, plus or minus the preset limit. In this manner, any significantly large errors in the critical edges of the encoder signals can be temporarily ignored for the fire pulse calculations of the next encoder period, at least within the programmable preset limits. This is particularly useful during printing operations during which the carrier should be traveling at a relatively constant velocity, wherein the false edges that may occur otherwise would significantly degrade the placement of printed pels on the print media if not for the automatic self-correction provided by the present invention.

Method and apparatus for automatically correcting the fire timing of a printhead carrier due to linear encoder velocity errors

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Versailles, KY, United States of America

Darrel Lee Henry