A detection apparatus for detecting foreign substances or defective goods, with which it is easy to accomplish inspection even if the inspection objects have a shape that tends to allow rolling, comprises: transparent members 11 and 12, partitions 21 and 22, a supplying unit 30, cameras 41 and 42, a control unit 50. The flat mirrored surfaces fold the images from separate projectors into a common image that has single optical axis aligned with principal axis of the convex mirror so that the combined image is reflected from the convex mirror onto the three dimensional screen. There is also provided a body defining at least one ink channel. The Hall Effect detecting device provides a first triggering signal to a first output pin and a second triggering signal to a second output pin in accordance to a magnetic field through the Hall Effect detecting device. Embodiments of the present invention comprise depositing a NiAl seedlayer, a Cr or Cr alloy underlayer and a first CoCrTa magnetic layer at a thickness less than about 50 for inducing the preferred crystallographic orientation in the subsequently deposited second magnetic layer, e. If the data copy fails to be verified, a copy of the data copy is generated.