The present invention discloses a photo mask employing in a TFT-LCD fabrication using 4-mask process. One power contact embodiment includes a first plate that defines a first non-deflecting beam and a first deflectable beam, and a second plate that defines a second non-deflecting beam and a second deflectable beam. In the absence of the recessed angled surface in the front face of the data cartridge, the flat surface of the flap blocks insertion of the data cartridge. The control circuit serves for actuating the electromotive motor and charging the battery and the over current protection device serves to monitor the charging current so as to protect the battery.