Apparatus and method for printhead to machine skew and margin adjustment for an electrophotographic machine

A method of aligning a laser printhead in an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with a pair of fixed sensors, said fixed sensors being spaced apart along a length of an axis of said first drum, each of said fixed sensors being fixed relative to a second of said drums;
• providing said first drum with a pair of floating sensors, said floating sensors being spaced apart along said length of said first drum axis, each of said floating sensors being fixed relative to said first drum;
• scanning a laser beam from the laser printhead across an outside surface of said first drum, said fixed sensors and said floating sensors, an intersection of said scanned laser beam and said outside surface of said first drum defining a scan path;
• measuring a first skew of said scan path relative to said axis of said first drum using said floating sensors;
• measuring a second skew of said scan path relative to an axis of said second drum using said fixed sensors;
• and
• adjusting said scan path of the laser beam dependent upon each of said first skew and said second skew.

An apparatus for positioning a laser beam in an electrophotographic machine, said apparatus comprising:

• a plurality of drums, each said drum having an axis;
• a laser printhead configured to scan the laser beam across a first of said drums;
• a pair of fixed sensors spaced apart along a length of said axis of said first drum, said fixed sensors being fixed relative to a second of said drums, said fixed sensors being configured to sense a skew of the laser beam relative to said second drum;
• a pair of floating sensors spaced apart along the length of said first drum, said floating sensors being fixed relative to said first drum, said floating sensors being configured to sense a skew of the laser beam relative to said first drum;
• and
• a processing/feedback unit in communication with said fixed sensors and with said floating sensors, said processing/feedback unit being configured to:
• calculate a desired skew of the laser beam;
• and
• provide an indication of a desired skew target.

A method of setting two side printing margins in an electrophotographic machine, said method comprising the steps of:

• providing the machine with a drum having a pair of sensors, each said sensor being disposed at a respective location along a length of said drum, each said location corresponding to a desired side printing margin;
• scanning a laser beam from a laser printhead across an outside surface of said drum and the sensors, an intersection of said scanned laser beam and said outside surface of said drum defining a scan path having two opposite ends;
• determining respective locations of said ends of the scan path relative to corresponding ones of said sensors, said determining step including determining whether the scan path is one of completely off of a corresponding said sensor, extending completely across a corresponding said sensor, and extending partially across a corresponding said sensor;
• and
• adjusting at least one of a starting location of the scan path and a length of the scan path dependent upon said determining step.

A method of setting two side printing margins in an electrophotographic machine, said method comprising the steps of:

• providing the machine with a drum having a pair of sensors, each said sensor being disposed at a respective location along a length of said drum, each said location corresponding to a desired side printing margin;
• scanning a laser beam from a laser printhead across an outside surface of said drum and the sensors, an intersection of said scanned laser beam and said outside surface of said drum defining a scan path having two opposite ends;
• determining respective locations of said ends of the scan path relative to corresponding ones of said sensors;
• and
• adjusting a length of the scan path by changing a number of picture element slices in the scan path dependent upon said determining step.

A method of calculating a drum-to-drum spacing in an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with at least one first sensor;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing a second of said drums with at least one second sensor;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• and
• calculating a drum-to-drum spacing based at least in part on said location of said first scan path and said location of said second scan path.

A method of calculating a drum-to-drum spacing in an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with at least one first sensor;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing a second of said drums with at least one second sensor;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• and
• calculating a drum-to-drum spacing based at least in part on said location of said first scan path and said location of said second scan path, said drum-to-drum spacing being calculated by an equation comprising:
• YDi=YNDi+Yvfi+YvfK
• wherein YDi is the drum-to-drum spacing, YNDi is a nominal drum-to-drum spacing, Yvfi is a measured distance between said at least one first sensor and a nominal target, and YvfK is a laser beam offset of said second drum.

A method of adjusting an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with at least one first sensor;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing a second of said drums with at least one second sensor;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• calculating a drum-to-drum spacing based at least in part on said location of said first scan path and said location of said second scan path;
• and
• adjusting an output delay of at least one of said first laser printhead and said second laser printhead dependent upon a result of said calculating step.

A method of adjusting an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with at least one first sensor;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing a second of said drums with at least one second sensor;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• calculating a drum-to-drum spacing based at least in part on said location of said first scan path and said location of said second scan path, said drum-to-drum spacing being calculated by an equation comprising:
• YDi=YNDi+Yvfi+YvfK
• wherein YDi is the drum-to-drum spacing, YNDi is a nominal drum-to-drum spacing, Yvfi is a measured distance between said at least one first sensor and a nominal target, and YvfK is a laser beam offset of said second drum;
• and
• adjusting at least one of a position and an output delay of at least one of said first laser printhead and said second laser printhead dependent upon a result of said calculating step.

A method of adjusting an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums;
• providing a first of said drums with at least one first sensor;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing a second of said drums with at least one second sensor;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• and
• adjusting at least one of a position and an output delay of at least one of said first laser printhead and said second laser printhead dependent upon said location of said first scan path and said location of said second scan path.

A method of adjusting an electrophotographic machine, said method comprising the steps of:

• providing the machine with a plurality of drums including a first drum and a second drum;
• providing said first drum with at least one first sensor, said at least one first sensor comprising at least one first fixed sensor and at least one floating sensor, said at least one first fixed sensor being fixed relative to said second drum, said at least one floating sensor being fixed relative to said first drum;
• scanning a first laser beam from a first laser printhead across an outside surface of said first drum and said at least one first sensor, an intersection of said scanned first laser beam and said outside surface of said first drum defining a first scan path;
• determining a location of the first scan path by using said at least one first sensor;
• providing said second drum with at least one second sensor, said at least one second sensor comprising at least one second fixed sensor, said at least one second fixed sensor being fixed relative to said second drum;
• scanning a second laser beam from a second laser printhead across an outside surface of said second drum and said at least one second sensor, an intersection of said scanned second laser beam and said outside surface of said second drum defining a second scan path;
• determining a location of the second scan path by using said at least one second sensor;
• and
• adjusting at least one of a position and an output delay of at least one of said first laser printhead and said second laser printhead dependent upon said location of said first scan path and said location of said second scan path.