Building Detection in Ikonos Images from Disparity of Edges

In a data processing device using flexible magnetic disc media, apparatus is disclosed for improved positioning of a magnetic read/record head against the recording surface of a magnetic disc. A carriage, moveable radially on the disc, has two opposed swing arms pivotal between a load position and a retracted position. A gimbal spring is cantilevered to each swing arm and carries at its free end a transducer. A retainer is attached to the end of each swing arm. During movement of the swing arm toward the load position, each retainer is engaged with its associated gimbal spring and maintains its associated head in a controlled attitude as the head approaches the disc. In the load position, the heads are opposite one another against recording surfaces on opposite sides of the disc, and each is free of its associated retainer. As the swing arms are moved from the load position toward the retracted position, each retainer engages its associated gimbal spring to pull the associated head from the disc surface in a controlled attitude.