Preventing crease formation in donor web in dye transfer printer that can cause line artifact on print

A thermal printer capable of preventing crease formation in a dye transfer area of a dye donor web that can cause line artifacts to be printed on a dye receiver during a dye transfer from the dye transfer area to the dye receiver, said printer comprising:

• a thermal print head adapted to heat the dye transfer area of the dye donor web sufficiently to effect a dye transfer from the dye transfer area to the dye receiver, but not heating two opposite edge areas of the dye donor web alongside the dye transfer area sufficiently to effect a dye transfer from the two edge areas to the dye receiver, so that the dye transfer area is vulnerable to being stretched relative to the two edge areas to possibly form creases extending at least across respective regions of the dye transfer area adjacent the two edge areas;
• and
• a crease-preventing web roller having relatively weak roller portions that extend part-way inwardly from opposite coaxial ends of said web roller, to be bowed at least against the two edge areas of the dye donor web to urge the regions of the dye transfer area in which the creases can form to spread in opposition to the onset of creases in such regions, and having a relatively strong intermediate roller portion between said weak roller portions that remains straight when said weak roller portions are bowed.

A method in a thermal printer of preventing crease formation in a dye transfer area of a dye donor web that can cause line artifacts to be printed on a dye receiver during a dye transfer from the dye transfer area to the dye receiver, said method comprising:

• heating the dye transfer area of the dye donor web sufficiently to effect a dye transfer from the dye transfer area to the dye receiver, but not heating two opposite edge areas of the dye donor web alongside the dye transfer area sufficiently to effect a dye transfer from the two edge areas to the dye receiver, so that the dye transfer area is vulnerable to being stretched relative to the two edge areas to possibly form creases extending at least across respective regions of the dye transfer area adjacent the two edge areas;
• and
• bowing a crease-preventing web roller at least against two edge areas of the dye donor web to urge the regions of the dye transfer area in which the creases can form to spread in opposition to the onset of creases in such regions.

A method in a thermal printer of preventing crease formation in a dye transfer area of a dye donor web that can cause line artifacts to be printed on a dye receiver during a dye transfer from the dye transfer area to the dye receiver, said method comprising:

• heating the dye transfer area of the dye donor web sufficiently to effect a dye transfer from the dye transfer area to the dye receiver, but not heating two opposite edge areas of the dye donor web alongside the dye transfer area sufficiently to effect a dye transfer from the two edge areas to the dye receiver, so that the dye transfer area is vulnerable to being stretched relative to the two edge areas to possibly form creases extending at least across respective regions of the dye transfer area adjacent the two edge areas;
• and
• independently bowing relatively weak portions of a crease-preventing web roller that extend inward from opposite coaxial ends of the web roller, at least against the two edge areas of the dye donor web to urge the regions of the dye transfer area in which the creases can form to spread in opposition to the onset of creases in such regions, but not bowing a relatively strong intermediate portion of the web roller between the weak roller portions, to allow the weak roller portions to be independently bowed relative to the strong roller portion.