Magneto-optic information recording system

A combination of a magneto-optic information recording system for recording colorplexed composite video information on a magneto-optic information storage medium having a normal magnetization film and a magneto-optic information reproducing system for reproducing the information recorded on the information storage medium, the composite video information containing a luminance signal component with a predetermined frequency bandwidth and a color subcarrier carrying a chrominance signal component and having a predetermined frequency,

• said information recording system comprising:
• beam emitting means for emitting therefrom a beam of light to irradiate said normal magnetization film in the presence of a bias magnetic field;
• field induction means operative to induce said bias magnetic field;
• first signal extracting means for extracting said luminance signal component from said composite video information;
• modulating means for modulating a recording beam of light in accordance with the luminance signal component extracted by said first signal extracting means;
• second signal extracting means for extracting said chrominance signal component from said composite video information;
• frequency converting means for converting the chrominance signal component into a signal with a predetermined frequency lower than the frequency of said color subcarrier;
• and
• field control means which is responsive to the frequency-converted chrominance signal component produced by said frequency converting means and which is operative to vary said bias magnetic field in accordance with the frequency-converted chrominance signal component while the normal magnetization film is being irradiated with said modulated beam of light;
• said information reproducing system comprising:
• beam emitting means for emitting a readout laser beam to irradiate said normal magnetization film for thermomagnetically picking up the information recorded on the film;
• signal detecting means for producing an electric signal representative of the information picked up from the normal magnetization film;
• first signal extracting means for extracting a frequency-modulated luminance signal component from the signal produced by the signal detecting means;
• second signal extracting means for extracting a frequency-converted carrier chrominance signal component from the signal produced by the signal detecting means;
• frequency demodulating means for frequency demodulating said frequency-modulated luminance signal component into a luminance signal having a frequency bandwidth;
• frequency converting means for converting said frequency-converted carrier chrominance signal component into a signal having a predetermined frequency;
• and
• signal mixing means operative to combine together the respective output signals from said frequency demodulating means and said frequency converting means of the reproducing system and producing a readout composite composite video information corresponding to the original colorplexed composite video information.