Apparatus for optically recording information signal onto a recording medium

Claim 1

An apparatus for optically recording an information signal onto a recording medium (18 ; 38) sensitive to light, comprising : a light source (13 ; 33) for projecting a light beam onto said recording medium ; means (19 ; 39) for moving said recording medium relative to said light beam ; means for generating a series of consecutive clock signals C of a predetermined frequency ; and light source drive means (12 ; 32) for modulating and driving said light source in response to a content of a digital input data signal D in synchronism with said recording clock signals in accordance to a two-level modulation for switching between a recording current which maintains an output power level of said light beam at a predetermined high power level so as to apply to the recording medium a localized heating sufficient to form a recording mark by a change in a physical characteristic of said recording medium due to said localized projection of said light beam and a non-recording current for maintaining the output power level of said light beam lower than a predetermined low power level so as to substantially prevent the formation of a recording mark on said recording medium, characterized in that said apparatus further comprises sub-modulating means (11 ; 31) for periodically switching the output output power level of said light beam between said high power level and said level lower than said low power level in synchronism with said recording clock signals by a series of consecutive modulating signals having a repetition period which is 1/n ( n is an integer of 2 or over) of a period corres­ponding to a minimum unit mark width U predetermined in correspondence to a minimum unit pulse width of said input data signal when forming on said recording medium said recording mark with a mark width of an integral multiple of said minimum unit mark width.

Claim 2

An apparatus for optically recording an information signal onto a recording medium (18 ; 38) sensitive to light, comprising : a light source (13 ; 33) for projecting a light beam onto said recording medium ; means (19 ; 39) for moving said recording medium relative to said light beam ; means for generating a series of consecutive clock signals C of a predetermined frequency ; and light source drive means (12 ; 32) for modulating and driving said light source in response to a content of a digital input data signal D in synchronism with said recording clock signals in accordance to a two-level modulation for switching between a recording current which maintains an output power level of said light beam at a predetermined high power level so as to apply to the recording medium a localized heating sufficient to form a recording mark by a change in a physical characteristic of said recording medium due to said localized projection of said light beam and a non-recording current for maintaining the output power level of said light beam lower than a predetermined low power level so as to substantially prevent the formation of a recording mark on said recording medium, characterized in that said apparatus further comprises sub-modulating means (11 ; 31) for periodically switching the output output power level of said light beam between said high power level and said level lower than said low power level in synchronism with said recording clock signals by a series of consecutive modulating signals having a repetition period which is 1/n ( n is an integer of 2 or over) of a period corres­ponding to a minimum unit mark width U predetermined in correspondence to a minimum unit pulse width of said input data signal when forming on said recording medium said recording mark with a mark width of an integral multiple of said minimum unit mark width.