| 摘要 |
In the circuit for detecting a recording prevention signal recorded in an image signal, the record preventing circuit based on a detection of a recording prevention signal comprises a Y/C divider(1400) for dividing a Y(luminous) signal and a C(color) signal which are contained in an image signal outputted from an auto gain controller(100) of a record preventing signal detector(2100); a Y signal processor(1500) for processing only the Y signal separated from the Y/C divider(1400); a 0.5 FH carrier shifter(1800) for heightening a DC level of a signal so as to obtain a frequency difference of 0.5 FH only in a period of CH-1 of a switch pulse in order to remove a channel interference between the mutual Y signals in writing and reproducing data; an FM converter(1900) for receiving an output of the 0.5 FH carrier shifter(1800) and performing a frequency modulation; a second switch(1600) for receiving an outputted signal from a comparator(1000) of the record preventing signal detector(2100) and an EE(L) signal, turned on in the writing, and turned off in the reproduction; and a first switch(1700) turned-on only in the writing of the second switch(1600), changing a voltage distribution amount by resistances(R1, R2) if the record preventing signal is inputted as a high signal by a passage of the record prevention detecting signal, and generating 5V voltage, whereby preventing an illegal copy on a recording medium through an abnormal output that a recorded image by an illegal record can not be outputted on screen.
|
