Abstract: A heating element having an electrically heatable layer comprises a support tube (16) provided with an electrically resistive heating layer (14), and electrodes for applying a voltage to the resistive heating layer (14). At least one electrode is provided as an elastic electrode, having a contacting side for engaging the resistive heating layer (14) and being adapted for arrangement on the support tube (16), with the contacting side of the electrode abutting the resistive heating layer (14). The contacting side has free ends comprising a plurality of projections having abutment faces, abutment lines or abutment points for contacting the resistive heating layer (14).

Abstract: An apparatus (14) for developing an exposed proof (16) provided with a visible light absorbing composition such as color particles or pigments includes a transport means (22-28, 36) for transporting the proof (16) along a treatment liquid dispenser unit (30, 32) and a take-off device (44, 38, 40) for removing detached composition from the proof (16). A tempering device (48) is provided for keeping the treatment liquid, which in the dispenser unit (30, 32) is applied onto the proof (16), at the optimum temperature for the developing process. The tempering device (48) comprises at least one Peltier element (52) which has at least one of its two tempering faces thermally connected with treatment liquid. The Peltier element (52) is adapted to receive a reversible supply voltage whose amount and polarity can be controlled. Depending on the polarity of the supply voltage, the Peltier element (52) operates either as a heating element or a cooling element.