Apparatus for thermographic duplication of information

An apparatus for copying information from an original or master (M) provided with information comprising a rotatable drum, to which the master (M) with applied information is attached, and the master (M) during the rotation of the drum is exposed to directed heat radiation from one or more heat radiation sources outside said drum spaced from said master and is supplied with a dye carrier, the dye of which thereby adheres to the master (M) in accordance with the information applied thereon, whereafter unprepared copy receiving sheets are brought into contact with the master (M) and thereafter removed therefrom, characterized in that the drum comprised two portions separated and movable relative to each other, of which the first portion is a cooled cylinder, and the second portion is a segment of a cylindric shell concentric with said cylinder and closely abutting but movable about the surface of the cylinder, means for attachment of said master (M) to said segment and wherein said segment of a cylindric shell is only a part of a cylinder and does not extend about the entire circumference of the cylinder whereby said cylinder is directly subjected to said directed heat radiation during a portion of a complete revolution of the said segment.