Patent ID: 6724412
Filing Date: 2004-04-20
Classification: B41J

Abstract:
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 for 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; a web take-up that takes up the dye donor web, and that exerts a pulling force on the dye transfer area and two edge areas at said print head which is sufficient to stretch the dye transfer area relative to the two edge areas to possibly form some creases in at least respective regions adjacent the two edge areas; and a crease-preventing platen roller having a rotatable main portion and a coaxial pair of opposite end portions each rotatable independently of said roller main portion, with respective lengths to hold the dye transfer area and two edge areas against said print head, and with a diameter that is greater at said roller end portions than at said roller main portion, so that said roller end portions apply a pressure against the two edge areas that is greater than a pressure said roller main portion applies against the dye transfer area, whereby the pressure difference causes the two edge areas to be stretched substantially the same as the dye transfer area when the dye transfer area and two edge areas are subjected to the pulling force of said web take-up roller, so that crease formation which can cause line artifacts is at least substantially prevented.