In an image forming apparatus that forms a toner image on a continuous medium, the tension force applied to the continuous medium by the image forming drum is controlled within a proper range. Highly assisted driving vehicles may read or capture images of the VSS. For this purpose, both parts have latching surfaces and deflecting surfaces and the latching hook is resiliently displaceable. The multimedia contents are encrypted by a key generated by the control server or are filtered by a transformation matrix. The shaped weld face is then textured to a desired surface roughness, and resistance spot welding using the welding electrode is performed to the aluminum alloy workpieces.