Current-to-voltage converting circuit, optical pickup head apparatus, and apparatus and method for recording/reproducing data

A current-to-voltage converting circuit comprising:

• a current-to-voltage converter which receives a current signal output from a photodetector outputting a current signal according to amount of received light and converts the received current signal into a voltage signal, the current-to-voltage converter comprising an active element applied with a negative feedback;
• a dummy circuit which has the same structure as the current-to-voltage converter and receives no current signal from the photodetector;
• p1 a differential operator for performing a differential operation between a signal output from the dummy circuit and a reference signal;
• a operating section for performing a differential operation or an adding operation, using the voltage signal from the current-to-voltage converter and a signal output from the differential operator;
• and
• a current variable section for varying an idling current which is to be supplied to the active element in accordance with a level of the current signal received from the photodetector or a reproduction speed of the data.

A current-to-voltage converting circuit which receives a current signal output from a photodetector outputting a current signal according to amount of received light and converts the received current signal into a voltage signal, comprising:

• a current-to-voltage converter for converting the current signal into the voltage signal;
• and
• a variable current section for varying an idling current which is to be supplied to the current-to-voltage converter in accordance with a level of the current signal received from the photodetector or a reproduction speed of the data;
• wherein a gain to convert a current into a voltage is provided by a negative feedback in which a signal output from the current-to-voltage converter is negatively fed back into an input of the current-to-voltage converter.

A current-to-voltage converting circuit which receives a current signal output from a photodetector outputting a current signal according to amount of received light and converts the received current signal into a voltage signal, comprising:

• a current-to-voltage converter for converting the current signal into the voltage signal;
• an amplifier for receiving the voltage signal from the current-to-voltage converter and amplifying the received voltage signal;
• and
• a current variable section for varying an idling current which is to be supplied to the current-to-voltage converter in accordance with a level of the current signal received from the photodetector or a reproduction speed of the data,
• wherein a gain to convert a current into a voltage is provided by a negative feedback in which a signal output from the amplifier is negatively fed back to the current-to-voltage converter.

A method of reproducing data from a recording medium by using a current-to-voltage converting circuit for converting a current signal from a photodetector to a voltage signal, the photodetector providing the current signal corresponding to amount of the light reflected on the recording medium, the current-to-voltage converting circuit including an active element applied with a negative feedback and being operable to vary an idling current to be supplied to the active element,

• wherein the current signal provided from the photodetector has two different levels including a first level and a second level which is smaller than the first level, the idling current to be supplied to the active element has two different currents including a first current and a second current which is smaller than the first current,
• the method comprising:
• detecting the level of the current signal provided from the photodetector;
• and
• setting the detected idling current to the first current when the current signal from the photodetector is at the first level, or setting the detected idling current to the second current when the current signal from the photodetector is at the second level.

A method of reproducing data from a recording medium by using a current-to-voltage converting circuit for converting a current signal from a photodetector to a voltage signal, the photodetector providing the current signal corresponding to amount of the light reflected on the recording medium, the current-to-voltage converting circuit including an active element applied with a negative feedback and being operable to vary an idling current to be supplied to the active element,

• wherein the current signal provided from the photodetector is transferred at one of a first transfer rate and a second transfer rate which is slower than the first transfer rate, the idling current to be supplied to the active element has one of a first current and a second current which is smaller than the first current,
• the method comprising:
• detecting the transfer rate of the data;
• and
• setting the idling current to the first current when the current signal from the photodetector is transferred at the first transfer rate, or setting the idling current to the second current when the current signal from the photodetector is transferred at the second transfer rate.