A hydrodynamic bearing apparatus comprises at least a pair of hydrodynamic bearing surfaces that face each other in the radial direction which are formed with an outer circumferential surface of a shaft unit and an inner circumferential surface of a shaft fitting unit relatively and rotatably attached to the shaft unit. The plural Orthogonal Variable Spreading Factor codes are defined by a binary code tree structure having a root and plural code levels, each node of the tree corresponding to one code and having a spreading factor defined by its level in the tree structure. For a given set of operational input values, a first set of end use device control signals is generated when a configuration input has a first value, and a second set of end use device control signals is generated when a configuration input has a second value. As a result the moving frequency of the crank in the air chamber can be altered to adjust the air supply amount being delivered.