Patent ID: 6812945
Filing Date: 2004-11-02
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 slanted creases diagonally extending at least across respective regions adjacent the two edge areas; and a crease preventing roller having respective web spreading portions that are similarly coiled inwardly along said roller from opposite coaxial ends of said roller, to be coiled towards one another from said opposite ends, in order to diagonally spread at least the web regions in which slanted creases can form, in opposition to crease formation that can occur when the pulling force is exerted on the dye transfer area and two edge areas at said print head, whereby crease formation can at least be substantially prevented, wherein said web spreading portions are similarly coiled inwardly along said roller to support the two edge areas, but not the dye transfer area, to diagonally urge the two edge areas to diagonally spread at least the web regions close to the two edge areas, and said crease preventing roller has an elastic portion between said web spreading portions to support the dye transfer area.