Method and apparatus for lateral registration control in color printing

A method for transverse registration of an image area to be exposed on a longitudinally moving belt subject to lateral deviation from linear travel, said method comprising the steps of:

• providing belt edge profile data relating i) each of a plurality of longitudinal positions along said moving belt to ii) a lateral position of an edge of the belt with respect to a spatially fixed reference point;
• detecting a first lateral position of said belt during movement of the belt by measuring the lateral position of said belt edge at a first one of said plurality of longitudinal positions along said belt;
• adjusting the transverse location of the image area on the belt to compensate for a difference between the detected first lateral position of said belt edge and the belt edge profile data related to said first one of said plurality of longitudinal positions;
• and
• determining when said longitudinally moving belt reaches a quasi steady state in said lateral deviation from linear travel by,
• calculating moving average belt edge profile data relating i) each of said plurality of longitudinal positions along said belt passing adjacent said spatially fixed reference point for a predetermined number of belt cycles to ii) an average lateral position of said belt edge at each of said plurality of longitudinal positions along said belt with respect to said reference point for said predetermined number of belt cycles,
• detecting a first lateral position data set of said belt during movement of the belt by measuring the lateral position of said belt edge at said plurality of longitudinal positions along said belt,
• calculating a plurality of difference data values by comparing said moving average belt edge profile data with said first lateral position data set for each of said plurality of longitudinal positions along said belt, and
• realizing said quasi steady state when each of said plurality of difference data values are within a predetermined value range.

A method for controlling a lateral position of a longitudinally moving endless belt subject to lateral deviation from linear travel, said method comprising the steps of:

• providing belt edge profile data relating i) each of a plurality of longitudinal positions along said moving belt to ii) a lateral position of an edge of the belt with respect to a spatially fixed reference point;
• detecting a first lateral position of said belt during movement of the belt by measuring the lateral position of said belt edge at a first one of said plurality of longitudinal positions along said belt;
• generating a steering command signal by calculating a difference between the detected first lateral position of said belt edge and the belt edge profile data related to said first one of said plurality of longitudinal positions;
• and,
• adjusting the lateral positions of the belt in response to said steering command signal while simultaneously performing the detecting and generating steps, whereby continuous updating of the lateral position of the belt is achieved.

A method for controlling a lateral position of a longitudinally moving endless belt subject to lateral deviation from linear travel, said method comprising the steps of:

• providing belt edge profile data relating i) each of a plurality of longitudinal positions along said moving belt to ii) a lateral position of an edge of the belt with respect to a spatially fixed reference point;
• detecting a first lateral position of said belt during movement of the belt by measuring the lateral position of said belt edge at a first one of said plurality of longitudinal positions along said belt;
• adjusting the transverse location of the image area on the belt to compensate for a difference between the detected first lateral position of said belt edge and the belt edge profile data related to said first one of said plurality of longitudinal positions;
• and
• determining when said longitudinally moving belt reaches a quasi steady state in said lateral deviation from linear travel by,
• calculating moving average belt edge profile data relating i) each of said plurality of longitudinal positions along said belt passing adjacent said spatially fixed reference point for a predetermined number of cycles to ii) an average lateral position of said belt edge at each of said plurality of longitudinal positions along said belt with respect to said reference point for said predetermined number of belt cycles,
• detecting a first lateral position data set of said belt during movement of said belt by measuring the lateral position of said belt edge at said plurality of longitudinal positions along said belt,
• calculating a plurality of difference data values by comparing said moving average belt edge profile data with said first lateral position data set for each of said plurality of longitudinal positions along said belt, and
• realizing said quasi steady state when each of said plurality of difference data values are within a predetermined value range.