Analog to digital converter assembly for normalizing servo error signals and multiplexing reference voltage inputs and digital outputs and improved optical drive system including same

A servo error and control assembly for use with a servomotor, said assembly comprising:

• an analog to digital converter having a reference voltage input, a clock input, an analog input, and a digital output;
• a switch including first and second switch inputs, a switch output, and a control input for alternately connecting said first and said second switch inputs to said switch output, said swftch output being applied to said reference voltage input;
• an information detection device having at least one detection output for controlling said servomotor based on detected information;
• a signal summing circuit having a sum signal output connected to said first switch input and a summing input connected to said at least one detection output of said detection device;
• a direct current voltage reference connected to said second switch input;
• a control clock connected to said control input of said switch for activating said switch at a predetermined rate thereby mulbplexing said sum signal output and said direct current voltage reference on said reference voltage input of said analog to digital converter;
• and
• a servo error signal circuit having a servo error signal output and a servo input connected to said detection output of said information detection device, said servo error signal output being a combination of said servo input and a portion of said sum signal output, and said servo signal output being connected to said analog input of said analog to digital converter for conversion thereof.

An analog to digital converter assembly for use in normalizing servo error signals and multiplexing reference voltage inputs and digital outputs, said analog to digital converter assembly comprising:

• an analog to digital converter having a reference voltage input, a clock input, an analog input, and a digital output;
• an information detection device having at least one detection output for controlling at least one servomotor based on detected information;
• a signal summing circuit having a sum signal output connected to said reference voltage input of said analog to digital converter and having at least one summing input connected to said at least one detection output of said information detection device;
• and
• a servo error signal circuit having a servo error signal output and a least one servo input connected to said at least one detection output of said detection device, said servo error signal output being a combination of said at least one servo input and a portion of said sum signal output, and said servo signal output being connected to said analog input of said analog to digital converter for conversion.

An analog to digital converter assembly for normalizing servo error signals and multiplexing reference voltage inputs and digital outputs, said analog to digital converter assembly comprising:

• an analog to digital converter having a reference voltage input, a clock input, an analog input, and a digital output;
• a switch including first and second switch inputs, a switch output, and a control input for alternately connecting said first and said second switch inputs to said switch output, said switch output being applied to said reference voltage input;
• an information detection device having at least one detection output for controlling at least one servomotor;
• a signal summing circuit having a sum signal output connected to said first switch input and having at least one summing input connected to said at least one detection output of said detection device;
• a direct current voltage reference connected to said second switch input;
• a control clock connected to said control input of said switch for activating said switch at a predetermined rate thereby multiplexing said sum signal output and said direct current voltage reference on said reference voltage input of said analog to digital converter;
• and
• a servo error signal circuit having a servo error signal output and at least one servo input connected to said at least one detection output of said information detection device, said servo error signal output being a combination of said at least one servo input and a portion of said sum signal output, and said servo signal output being connected to said analog input of said analog to digital converter for conversion thereof.

An analog to digital circuit assembly, comprising:

• a circuit for normalizing servo error signals in an apparatus for retrieving information on a record medium;
• an analog to digital converter having a reference voltage input, a clock input, an analog input, and a digital output;
• an information detection device having at least one output and at least one servo mechanism that controls operations on information being detected;
• a signal summing circuit having a sum signal output connected to said reference voltage input of said analog to digital converter and having at least one input connected to said at least one detection output;
• a servo error signal circuit having a servo error signal output and at least one servo input connected to said at least one detection output, said servo error signal output being a combination of said at least one servo input and a portion of said sum signal output, and said servo signal output being connected to said analog input of said analog to digital converter for conversion;
• a sampling clock connected to said clock input for controlling said converterto convert said servo error signal to a digital signal that is normalized to said sum signal output;
• and
• a processing circuit having an input connected to said digital output of said analog to digital converter and an output for controlling said at least one servo mechanism.

An analog to digital circuit assembly, comprising:

• a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of a plurality of analog signal inputs at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting said first and said second inputs to said output, said output being applied to said reference voltage input;
• an information detection device having at least one detection output and having at least one servo mechanism that controls operations on information being detected;
• a signal summing circuit having a sum signal output connected to said first input of said switch and having at least one input connected to said at least one detection output;
• a direct current voltage reference connected to said second input of said switch;
• a control clock connected to said control input of said switch for activating said switch at a predetermined rate, thereby multiplexing said sum signal and said direct current voltage reference on said reference voltage input;
• a servo error signal circuit having a servo error signal output and at least one input connected to said at least one detection output, said servo error signal output being a combination of said at least one input and a portion of said sum signal output, and said servo signal output being connected to said analog input of said analog to digital converter for conversion;
• a sampling clock connected to said clock input for controlling said converter to convert said servo error signal to a digital signal that is normalized to said sum signal output when said switch connects said first input to said output;
• and
• a processing circuit having an input connected to said digital output of said analog to digital converter and an output for controlling said at least one servo mechanism.

An optical drive system, comprising:

• an objective lens subassembly for directing light from a light source toward an information storage medium, an amount of said light being returned therefrom;
• an objective lens disposed in said objective lens subassembly;
• a first servomotor for moving said objective lens relative to said storage medium to effect focusing;
• an information detection device having at least one detection output for controlling said servomotor based on detected information, said information detection device including at least one quad detector for detecting light returned from the storage medium;
• processing circuitry connected to said at least one quad detector to produce a Quad Sum signal related to the light detected by the quad detector;
• an analog to digital converter having a reference voltage input, a clock input, an analog input, and a digital output;
• a signal summing circuit having a sum signal output connected to said reference voltage input of said analog to digital converter and having at least one summing input connected to said at least one detection output of said information detection device;
• and
• a servo error signal circuit having a servo error signal output and a servo input connected to said at least one detection output of said detection device, said servo error signal output being a combination of said servo input and a portion of said sum signal output, said servo signal output being connected to said analog input of said analog to digital converter for conversion.