US Patent 7236450 Recording medium having resin substrate

A recording medium including a resin substrate having a first thermal expansion coefficient, a center hole, a first surface, and a second surface opposite to the first surface, a recording layer formed on the first surface of the resin substrate and having a recording region, an inner nonrecording region formed inside the inner periphery of the recording region, and an outer nonrecording region formed outside the outer periphery of the recording region, and a protective layer formed on the second surface of the resin substrate except an inner peripheral region having a predetermined range from the center hole, the recording region, and the outer nonrecording region. The thermal deformation suppressing layer has a second thermal expansion coefficient smaller than the first thermal expansion coefficient.