Video signal recording/reproducing system for increasing recording density of a frequency modulated signal

A video signal recording/reproducing device comprising:

• a laser light source, for projecting a laser light on an optical disk memory, to record/reproduce video signals;
• frequency modulating means for generating frequency-modulated signals representative of said video signals for recording on said optical disk memory;
• laser driving pulse generating means, coupled to said frequency modulating means, for generating laser driving pulses derived from said frequency-modulated signals, a duty factor of said laser driving pulses being modified in accordance with a linear velocity signal indicative of a linear velocity of a part of said optical disk memory where recording is performed;
• recording means, coupled to said laser light source, for recording said frequency-modulated signals by converging said laser light, emitted from said laser light source in accordance with said laser driving pulses, on said optical disk memory;
• driving means for driving said optical disk memory during recording/reproducing;
• linear velocity detecting means, coupled to said recording means and said laser driving pulse generating means, for detecting said linear velocity to generate said linear velocity signal;
• reproduction means for reproducing said frequency-modulated signals recorded on said optical disk memory by said recording means to output a reproduction pulse signal;
• and
• FM demodulating means, coupled to said reproduction means, for demodulating said reproduction pulse signal,
• said recording means including
• laser light source driving means, coupled to said laser driving pulse generating means and said laser light source, for driving said laser light source in response to said laser driving pulses and for controlling output power of said laser light source to be an optimum value during recording according to said linear velocity signal and the duty factor of said laser driving pulses,
• recording head means equipped with converging means for converging said laser light emitted by said laser light source onto said optical disk memory and a magnetic field applying section for emitting an auxiliary magnetic field, and
• head control means, coupled to said recording head means, for controlling the converging position of said laser light,
• said laser driving pulse generating means and said laser light source driving means respectively controlling the duty factor of said laser driving pulses and the output power of said laser light source to be optimum values so that said reproduction pulse signal has a duty factor substantially equal to 50%,
• said laser driving pulse generating means including
• comparator means, coupled to said frequency modulating means, for comparing said frequency-modulated signals and a level corresponding to a mid-value of the peak-to-peak amplitude of said frequency-modulated signals to convert said frequency-modulated signals into binary signals of pulses having a duty factor equal to 50%,
• delay means, coupled to said comparator means, for delaying said pulses generated by said comparator means by a predetermined time to generate delayed pulses in accordance with said linear velocity of the part of said optical disk memory where recording is being performed,
• an AND circuit, coupled to said comparator means and said delay means, for performing a logical AND function of said pulses generated by said comparator means and said delayed pulses, to generate an AND output signal, and
• buffer amplifier means, coupled to said AND circuit, for amplifying and outputting said AND output signal as said laser driving pulses.