| 摘要 |
PURPOSE: To make it possible to execute reproducing only when a reproducing machine to be exclusively used is used and to prevent execution of 1 to 1 copying on the optical recording medium of the same size by providing the optical recording medium with a mask layer of a material having desired optical characteristics on the side outer than a recording layer. CONSTITUTION: This optical recording layer is provided with the mask layer 3 on the other side of the recording layer by using the material having the optical characteristics to generate a reversible charge in the optical characteristics when the material is irradiated with a light beam of the intensity higher than the intensity of the light beam used at the time of reproducing information from general magnetic recording medium having no mask layers. The density of the information recorded on the recording layer 3 is set higher than the max. recording density which can be read out even if there is no mask layer 3. As a result, the irradiation of the recording layer with the light spot of a desired bore is prevented by the mask layer as the power of the light beam is low when the reproducing is executed with a general reproducing machine. In addition, the recording density is high when reproduction is attempted to be executed by using the light beam of a high power, therefor, the execution of 1 to 1 copying on the recording medium of the same size is not possible. |
