Stitching prevention in multibeam imaging for exposing printing plates

A carrier medium carrying computer readable code segments to instruct one or more processors of a processing system to execute a method of exposing imaging data onto a sensitized medium, the method comprising:

• exposing a first number denoted K of sets of a number denoted N of tracks on to a sensitized medium using an imaging system arranged to expose at least N tracks simultaneously on to the medium according to provided imaging data, the N tracks oriented adjacent to each other in a slow scan direction, each successive N-track set of the K-sets being a pixel distance apart in a fast scan direction, the imaging system arranged to provide relative motion between the set of tracks and the medium in the fast scan direction and to provide relative motion between the set of N tracks and the medium in the slow scan direction, the number N being at least 1, the exposing of the K sets according to the corresponding part of the imaging data;
• exposing a second number denoted L of sets of N tracks onto the medium with an offset of M pixels in the slow scan direction, each successive N-track set of the L-sets being a pixel distance apart in a fast scan direction, the exposing based on imaging data shifted such that the exposing of the L sets matches in continuity with the previous exposing of K sets;
• repeating alternately exposing K sets and L sets of N tracks until the complete length in the fast scan direction of the medium is exposed medium is exposed;
• and
• during or after the alternately exposing K sets and L sets, progressing in the slow scan direction such that after exposing the complete length of N tracks of exposed pixels, the next N tracks match along the medium at the start of the next N tracks,
• such that no pixel location is exposed more than once, and such that the visibility of exposure differences between adjacent N imaging tracks recorded by the imaging system on the medium is reduced compared to continually recording a number of tracks for a complete medium distance in the fast scan direction.

A method of exposing imaging data onto a sensitized medium, the method comprising:

• exposing a first number denoted K of sets of a number denoted N of tracks on to a sensitized medium using an imaging system arranged to expose at least N tracks simultaneously on to the medium according to provided imaging data, the N tracks oriented adjacent to each other in a slow scan direction, each successive N-track set of the K-sets being a pixel distance apart in a fast scan direction, the imaging system arranged to provide relative motion between the set of tracks and the medium in the fast scan direction and to provide relative motion between the set of N tracks and the medium in the slow scan direction, the number N being at least 1, the exposing of the K sets according to the corresponding part of the imaging data;
• exposing a second number denoted L of sets of N tracks onto the medium with an offset of M pixels in the slow scan direction, each successive N-track set of the K-sets being a pixel distance apart in a fast scan direction, the exposing based on imaging data shifted such that the exposing of the L sets matches in continuity with the previous exposing of K sets;
• repeating alternately exposing K sets and L sets of N tracks until the complete length in the fast scan direction of the medium is exposed;
• and
• during or after the alternately exposing K sets and L sets, progressing in the slow scan direction such that after exposing the complete length of the N tracks of exposed pixels, the next N tracks match along the medium at the start of the next N tracks,
• such that no pixel location is exposed more than once, and such that the visibility of exposure differences between adjacent N imaging tracks recorded by the imaging system on the medium is reduced compared to continually recording a number of tracks for a complete medium distance in the fast scan direction.

An imaging apparatus to expose an ablative or thermal sensitive medium according to imaging data, the apparatus comprising:

• a laser output imaging device to direct a number N of beams, onto the media, N being at least one, the N beams on the media modulated according to the imaging data, and in the case that there is a plurality of beams simultaneously exposing the media, the plurality of imaging beams being oriented on to the media in a slow scan direction;
• a first mechanism to provide relative motion between the N beam or beams on the media and the media in a fast scan direction substantially perpendicular to the slow scan direction, such that during relative motion in the fast scan direction, a packet of N modulated beam or beams is directed onto the media;
• a second mechanism to provide relative motion between the N modulated beam or beams on the media and the media in the slow scan direction;
• and
• a controller coupled to the first and second mechanisms,
• the controller arranged to accept the imaging data and to select appropriate imaging data to the laser output imaging device to modulate the appropriate beam at the appropriate time to expose the medium such that the apparatus writes a number K of sets of N pixels onto the medium based upon a first block of imaging data, K being at least one, the controller proceeding to accept imaging data to expose at a next position in fast scan direction after the K sets of N pixels are written,
• the controller further is arranged such that the apparatus then writes L sets of N pixels onto the medium based upon a second block of imaging data while the N pixels being written are together offset by M pixels in the slow scan direction compared to the writing of the K sets according to the first block of imaging data, the controller proceeding to accept imaging data to expose at a next position in fast scan direction after the L sets of N pixels are written,
• the controller further is arranged such that there is repeated alternately exposing K sets and L sets of N tracks until the complete medium is exposed along the fast scan direction,
• the controller being arranged to produce relative motion in the slow scan direction during or after the alternately exposing K sets and L sets such that after exposing the complete length the N tracks of exposed pixels, the next N tracks match along the medium at the start of the at next N tracks.

A method of exposing imaging data onto a sensitized medium including:

• exposing K sets of N of tracks on to the medium according to a corresponding part of imaging data, each successive set being a pixel distance apart in a fast scan direction;
• exposing L sets of N tracks onto the medium with an offset of M pixels in a slow scan direction substantially perpendicular to the fast scan direction, according to a second corresponding part of imaging data;
• repeating alternately exposing K sets and L sets of N tracks until the complete medium is exposed along the fast scan direction;
• and
• during or after the alternately exposing K sets and L sets, progressing in the slow scan direction such that after exposing the complete length of the N tracks of exposed pixels, the next N tracks match along the medium at the start of the next N tracks.

An apparatus of exposing imaging data onto a sensitized medium including:

• means for exposing K sets of N of tracks on to the medium according to a corresponding part of imaging data, each successive set being a pixel distance apart in a fast scan direction;
• means for exposing L sets of N tracks onto the medium with an offset of M pixels in a slow scan direction substantially perpendicular to the fast scan direction, according to a second corresponding part of imaging data;
• means for repeating alternately exposing K sets and L sets of N tracks until the complete medium is exposed along the fast scan direction;
• and
• means for progressing in the slow scan direction during or after the alternately exposing K sets and L sets, such that after exposing the complete length of N tracks of exposed pixels, the next N tracks match along the medium at the start of the next N tracks.