Abstract: A recording medium that technically makes it not only impossible to infringe copyrights but possible for a buyer who properly bought contents to personally freely reproduce and enjoy the contents. A recording medium comprises a first recording region (3) where the contents encrypted by a contents key are recorded in advance, a second recording region (5) where a data providing a basis for the contents key is recorded in advance and a third recording region (4) that allows the encrypted contents key obtained by encrypting the contents key generated from the data providing a basis for the contents key by means of identification information on a user to be recorded therein.

Abstract: In a hydrodynamic bearing device in which a radial bearing face having a dynamic pressure generating groove on a shaft or an inner periphery of a sleeve is provided and a clearance between the shaft and the sleeve is filled with lubricant, an annular depression is provided on one end face of the sleeve adjacent to a rotor hub and a cover plate for covering the depression is attached to the sleeve so as to define a reservoir for the lubricant or air for the purpose of preventing such a risk that absence of an oil film occurs in clearances of a bearing of the hydrodynamic bearing device due to outflow of oil upon forcing of the oil by air received into the bearing. A step portion is provided on the other end face of the sleeve such that the step portion and the reservoir are communicated with each other by a communication hole. During operation of the hydrodynamic bearing device, air in the hydrodynamic bearing device reaches the reservoir via the communication hole so as to be discharged from the reservoir.