Abstract: Beneath its line of heater points, the print head includes a film of thermoresistive material which is used for sensing temperature in the proximity of the heater points, thereby making it possible to obtain a signal which can be used quickly in regulating the quantity of energy delivered to each heater point, thereby making it possible to operate the points at a higher rate because they are subjected to excitation which is regulated.

Abstract: A thermal test pattern comprises motifs of a material having a high thermal emissivity which are provided on one side of a flat substrate. The substrate has a low thermal emissivity. The other side of the substrate is covered with a layer of a material having a high electrical resistivity which is provided between two conductive connection strips. The motifs and connection strips and resistive layer may be deposited by silk screening. Due to the differences in thermal emissivity, a temperature difference occurs between the substrate and the motifs, the motifs being colder, when the substrate is heated by passing an electric current through the resistive layer.