(EN) DISCLOSED HEREIN ARE A HIGH-DENSITY RECORDING MEDIUM (10), SUCH AS A HIGH-DENSITY OPTICAL DISC (10) AND A RECORDING AND/OR REPRODUCING DEVICE THEREFOR. AT A TRANSITION AREA OF THE HIGH-DENSITY OPTICAL DISC (10) ALLOCATED BETWEEN A CLAMPING AREA AND AN INFORMATION AREA OF THE HIGH-DENSITY OPTICAL DISC (10) IS FORMED A STEP HAVING A PRESCRIBED SLOPE SO THAT THE HIGH-DENSITY OPTCIAL DISC (10) DOES NOT COLLIDE WITH AN OBJECTIVE LENS (OL) OF AN OPTICAL PICKUP (14) PROVIDED IN AN OPTICAL DISC DEVICE ALTHOUGH THE OBJECTIVE LENS (OL) OF THE OPTICAL PICKUP (14) IS UPWARDLY MOVED TOWARD A RECORDING LAYER OF THE HIGH-DENSITY OPTICAL DISC (10) UNTIL IT MOVES TO THE MAXIMUM WORKING DISTANCE WHEN THE HIGH-DENSITY OPTICAL DISC (10), SUCH AS A BLU-RAY DISC, IS IMPROPERLY PLACED ON A TURNTABLE (11) PROVIDED IN THE OPTICAL DISC DEVICE, E.G., WHEN THE HIGH-DENSITY OPTICAL DISC (10) IS PLACED UPSIDE DOWN ON THE TURNTABLE (11). THE THICKNESS OF THE INFORMATION AREA IS SMALLER THAN THAT OF THE CLAMPING AREA BY THE PROVISION OF THE STEP AT THE TRANSITION AREA. CONSEQUENTLY, DAMAGE TO THE HIGH-DENSITY OPTICAL DISC (10) OR THE OBJECTIVE LENS (OL) DUE TO A COLLISION OF THE OBJECTIVE LENS (OL) WITH THE HIGH-DENSITY OPTICAL DISC (10) IS PREVENTED, AND FATAL ERRORS OF A SERVO OPERATION ARE EFFECTIVELY PREVENTED. FURTHERMORE, THE COST OF MATERIALS REQUIRED TO MANUFACTURE THE HIGH-DENSITY OPTICAL DISC (10) IS REDUCED WHILE STABLE CLAMPING FORCE IS MAINTAINED, AND SAFE INSERTION OF THE HIGH-DENSITY OPTICAL DISC (10) INTO A SLOT-TYPE OPTICAL DISC DRIVE IS POSSIBLE. FIGURE 6
