At the present time, physicians often treat patients with atrial fibrillation using radiofrequency catheter systems to ablate conducting tissue in the wall of the Left Atrium of the heart around the ostium of the pulmonary veins. The method includes: setting a unit time which is the time of the driver chip to scan every pixel; calculating the multiple of the area of every picture; obtaining the multiple of the maximum area; and calculating the multiple of the area of every picture according to step. A housing has a cavity into which the terminal fitting and the resilient plug are inserted.