Apparatus and method for recording and reproducing information from a plurality of recording medium having different thickness and recording densities

Claim 1

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; and a photodetector for detecting light returning from said information recording layer of the first or second recording mediums; wherein said photodetector has a size of at least 10 mm and at most 14 mm , which is normalized based on a magnification of said optical system; and wherein output from said photodetector is supplied to a focusing servo circuit which outputs in response thereto a focusing servo signal, said output from said photodetector also being supplied to a circuit which generates therefrom a signal representative of information recorded on said information recording layer of the first or second recording mediums.

Claim 2

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; and a photodetector for detecting light returning from said information recording layer of the first or second recording mediums; wherein said photodetector has a size of at least 10 mm and at most 14 mm , which is normalized based on a magnification of said optical system; and wherein output from said photodetector is supplied to a focusing servo circuit which outputs in response thereto a focusing servo signal, said output from said photodetector also being supplied to a circuit which generates therefrom a signal representative of information recorded on said information recording layer of the first or second recording mediums.

Claim 4

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; and a photodetector for detecting light returning from said information recording layer of the first or second recording mediums; said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; wherein output from said photodetector is supplied to a focusing servo circuit which outputs in response thereto a focusing servo signal, said output from said photodetector also being supplied to a circuit which generates therefrom a signal representative of information recorded on said information recording layer of the first or second recording mediums.

Claim 5

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; and a photodetector for detecting light returning from said information recording layer of the first or second recording mediums; said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; wherein output from said photodetector is supplied to a focusing servo circuit which outputs in response thereto a focusing servo signal, said output from said photodetector also being supplied to a circuit which generates therefrom a signal representative of information recorded on said information recording layer of the first or second recording mediums.

Claim 8

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; and an equalizer which receives an output signal from said comparator and equalizes an output signal from said photodetector in response to whether said first recording medium or said second recording medium is being read; wherein said comparator distinguishes between said first recording medium and said second recording medium by comparing a level of the output signal from said photodetector with a predetermined value.

Claim 9

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; and an equalizer which receives an output signal from said comparator and equalizes an output signal from said photodetector in response to whether said first recording medium or said second recording medium is being read; wherein said comparator distinguishes between said first recording medium and said second recording medium by comparing a level of the output signal from said photodetector with a predetermined value.

Claim 11

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; an equalizer which receives an output signal from said comparator and equalizes an output signal from said photodetector in response to whether said first recording medium or said second recording medium is being read; a binary signal generator which receives an output signal from said equalizer and which produces therefrom a binary signal representative of information recorded on said first or second recording medium; a demodulator which receives and demodulates an output signal from said binary signal generator; and a phase locked loop circuit which receives said output signal from said comparator and which provides a first clock signal to said demodulator when said first recording medium is being read and a second clock signal, different from said first clock signal, when said second recording medium is being read.

Claim 12

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; an equalizer which receives an output signal from said comparator and equalizes an output signal from said photodetector in response to whether said first recording medium or said second recording medium is being read; a binary signal generator which receives an output signal from said equalizer and which produces therefrom a binary signal representative of information recorded on said first or second recording medium; a demodulator which receives and demodulates an output signal from said binary signal generator; and a phase locked loop circuit which receives said output signal from said comparator and which provides a first clock signal to said demodulator when said first recording medium is being read and a second clock signal, different from said first clock signal, when said second recording medium is being read.

Claim 16

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; and a control circuit which receives an output signal of said comparator and which controls said optical system according to different tracking control processes when said first recording medium is read and when said second recording medium is read, as determined by said comparator; wherein: said first thickness is greater than said second thickness; said tracking control process is a three beam tracking process when said first recording medium is being used; and said tracking control process is a differential push-pull tracking process when said second recording medium is being used.

Claim 17

An apparatus for recording information selectively on and reproducing information selectively from a first recording medium having an information recording layer on a substrate having a first thickness or a second recording medium having an information recording layer on a substrate having a second thickness, comprising: a light source which generates light to be applied to the information recording layer of the first or second recording medium; an optical system which converges the light generated by said light source and applies the converged light to said information recording layer of the first or second recording medium; a photodetector for detecting light returning from said information recording layer of the first or second recording mediums, said photodetector having a normalized detector size of at least 3 mm and at most 16 mm; a comparator which receives an output signal of said photodetector and distinguishes between said first recording medium and said second recording medium using said output signal of said photodetector; and a control circuit which receives an output signal of said comparator and which controls said optical system according to different tracking control processes when said first recording medium is read and when said second recording medium is read, as determined by said comparator; wherein: said first thickness is greater than said second thickness; said tracking control process is a three beam tracking process when said first recording medium is being used; and said tracking control process is a differential push-pull tracking process when said second recording medium is being used.