Method and apparatus of correction image read signals by removing the influence of dark current therefrom

Claim 1

An apparatus for correcting image read signals comprising: a linear sensor for reading an image line by line and outputting read pixel signals of said image and blind pixel signals; an A/D converter for converting an output signal of said linear sensor into a digital signal; a shift register, coupled to an output of said A/D converter for receiving said digital signal, for storing and outputting a plurality of blind pixel signals of a plurality of lines; line memories, coupled to said output of said A/D converter for storing said digital signal; a first subtracter for subtracting blind pixel signals from a plurality of preceding lines from blind pixel signals of a current line; an adder, having a first input coupled to an output of said first subtracter and a second input for outputting addition data; a first latch circuit for latching the addition data from the adder, and having an output coupled to said second input of the adder; a second latch circuit for storing the addition data; a divider for dividing an output of said second latch circuit so as to obtain an average value; a second subtracter for subtracting the average value from an output of at least one of said line memories, and for outputting a corrected signal; and a timing generating circuit for controlling said line memories, said shift register and said first and second latch circuits by timing signals.

Claim 2

An apparatus for correcting image read signals comprising: a linear sensor for reading an image line by line and outputting read pixel signals of said image and blind pixel signals; an A/D converter for converting an output signal of said linear sensor into a digital signal; a shift register, coupled to an output of said A/D converter for receiving said digital signal, for storing and outputting a plurality of blind pixel signals of a plurality of lines; line memories, coupled to said output of said A/D converter for storing said digital signal; a first subtracter for subtracting blind pixel signals from a plurality of preceding lines from blind pixel signals of a current line; an adder, having a first input coupled to an output of said first subtracter and a second input for outputting addition data; a first latch circuit for latching the addition data from the adder, and having an output coupled to said second input of the adder; a second latch circuit for storing the addition data; a divider for dividing an output of said second latch circuit so as to obtain an average value; a second subtracter for subtracting the average value from an output of at least one of said line memories, and for outputting a corrected signal; and a timing generating circuit for controlling said line memories, said shift register and said first and second latch circuits by timing signals.

Claim 4

An apparatus for correcting image read signals comprising: a linear sensor for reading an image line by line and outputting read pixel signals of said image and blind pixel signals; an A/D converter for converting an output signal of said linear sensor into a digital signal; a shift register, coupled to an output of said A/D converter for receiving said digital signal, for storing and outputting a plurality of blind pixel signals of a plurality of lines; line memories, coupled to said output of said A/D converter, for storing said digital signal; a first subtracter for subtracting blind pixel signals from a plurality of preceding lines from blind pixels from a current line; an adder having a first input coupled to an output of said first subtracter and a second input for outputting addition data; a first latch circuit for latching the addition data from the adder, and having an output coupled to said second input of the adder; a second latch circuit for storing the addition data and for obtaining an average value by outputting a portion of said stored addition data; a second subtracter for subtracting the average value from the output of at least one of said line memories, and for outputting a corrected signal; and a timing generating circuit for controlling said line memories, said shift register and said first and second latch circuits by timing signals.

Claim 5

An apparatus for correcting image read signals comprising: a linear sensor for reading an image line by line and outputting read pixel signals of said image and blind pixel signals; an A/D converter for converting an output signal of said linear sensor into a digital signal; a shift register, coupled to an output of said A/D converter for receiving said digital signal, for storing and outputting a plurality of blind pixel signals of a plurality of lines; line memories, coupled to said output of said A/D converter, for storing said digital signal; a first subtracter for subtracting blind pixel signals from a plurality of preceding lines from blind pixels from a current line; an adder having a first input coupled to an output of said first subtracter and a second input for outputting addition data; a first latch circuit for latching the addition data from the adder, and having an output coupled to said second input of the adder; a second latch circuit for storing the addition data and for obtaining an average value by outputting a portion of said stored addition data; a second subtracter for subtracting the average value from the output of at least one of said line memories, and for outputting a corrected signal; and a timing generating circuit for controlling said line memories, said shift register and said first and second latch circuits by timing signals.