GB1139232A - Improvements relating to thermomagnetic recording - Google Patents

Abstract

1,139,232. Magnetic printing. E. I. DU PONT DE NEMOURS & CO. 27 April, 1966 [27 April, 1965; 17 June, 1965], No. 18497/66. Heading B6C. [Also in Divisions G5 and H1] A master record is placed in contact with a magnetizable blank which is then heated and cooled through; a temperature at least in the vicinity of its Curie. temperature, thereby recording on the blank an amplified copy of the signal on the master record. In the embodiments described, the copying blank is in the form of a tape carrying a magnetizable layer (containing chromium dioxide particles); or a succession of such layersof different Curie temperatures so that a signal may be repeatedly copied and amplified on a single tape. The master record may take the form of a tape (Figs. I and II), a rotating drum carrying, an array of magnetizable zones (Figs. IIIA, IIIB and IV), or an endless belt running on two rollers and in contact at one roller with a copying tape wrapped round a third roller which in turn makes contact with a second copying tape wrapped round a fourth roller. Heating of the copying blank is effected by radiant energy, such as a flash from a xenon arc lamp, or a beam from an infra-red heater directed at a moving copying tape at a point just before it engages the master record. The radiant energy falling on the copying blank may be modulated by an interposed grating or transparency. The recorded magnetic signal may be indicated visually by means of ferromagnetic powder.