| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the selling of an illegal copy of information recording medium by providing in advance a nearly planar LC resonance circuit on the normal recording medium. SOLUTION: When a video cassette tape 10 is inserted into a video deck 1 from the cassette inlet/outlet port 2 of the deck 1, an LC resonance circuit 20 provided on the case 11 of the tape 10 is resonated by a radio wave transmitted from a transmitting-receiving section 3 and a resonant wave is generated. When the resonant wave is not received by means of the section 3, a control section 4 discriminates the tape 10 as a copy and ejects the tape 10 as it is from the port 2. When the resonant wave from the surface of the case 11 is received by means of the section 3, the frequency of the resonant wave is analyzed. When it is confirmed that the frequency coincides with one reference frequency as a result of comparison, the control section 4 discriminates the tape 10 as a proper product and instructs an information reproducing section 5 to make normal reproducing operations.</p> |
