Optical disc and method for judging whether optical disc is placed reversely

A method for judging whether a double-sided optical disc is placed reversely into an optical disc drive, the optical disc drive comprising a first control module which is used to control a first optical pickup head and a second control module which is used to control a second optical pickup head, the first control module comprising the first optical pickup head, a first sled motor, a first radio frequency amplifier, a first driving circuit and a first digital signal processor, the second control module comprising the second optical pickup head, a second sled motor, a second radio frequency amplifier, a second driving circuit and a second digital signal processor, the method comprising steps of:

• loading the double-sided optical disc;
• allowing the first control module to control the first optical pickup head to emit a first laser beam to a first specified area of the double-sided optical disc and receive a first reflected laser beam from the first specified area;
• allowing the second control module to control the second optical pickup head to emit a second laser beam to a second specified area of the double-sided optical disc and receive a second reflected laser beam from the second specified area;
• if the first reflected laser beam generates an alternate brightness and darkness change and the intensity of the first reflected laser beam processed by the first radio frequency amplifier generates a sinusoidal wave signal and the second reflected laser beam does not generate the alternate brightness and darkness change and the intensity of the second reflected laser beam processed by the second radio frequency amplifier generates a stable direct current signal, confirming that the double-sided optical disc is not placed reversely;
• and
• if the first reflected laser beam does not generate the alternate brightness and darkness change and the intensity of the first reflected laser beam processed by the first radio frequency amplifier generates the stable direct current signal and the second reflected laser beam generates the alternate brightness and darkness change and the intensity of the second reflected laser beam processed by the second radio frequency amplifier generates the sinusoidal wave signal, confirming that the double-sided optical disc is placed reversely.