Method and circuit for correcting distance between sensors in image reading apparatus having a plurality of line sensors

In an image reading apparatus having a plurality of line sensors including an image sensing means for converting optical image information into an electrical signal, an analog-to-digital converting means for converting a signal from said image sensing means into a digital signal, and a sensor-to-sensor distance correcting means, a circuit for correcting a distance between sensors comprising:

• an extra-line corrector for correcting a registration error of an integer line unit among distances between sensors by housing sensor data for reading an image at a preceding position on a manuscript using red and green signal delay memories, delaying the housed sensor data until sensor data at a next position is read, and reading the delayed sensor data when sensor data at the last position is read;
• and
• an intra-line corrector for correcting a decimal point unit registration error among the distances between sensors using a look-up table for housing interpolation kernel data, wherein said sensor-to-sensor distance correcting means further comprises an address generator for generating an address for controlling a delay memory using a sensor pixel clock signal, wherein, in said address generator, an involution value of 2 is called a column-address when the difference between a signal scan line address coefficient value and the number of sensor pixels are the smallest among them of a multiple of an integer of the involution of 2 which is more than or equal to the number of sensor pixels, and, when the integral times of 2 is called the signal line address coefficient value, the multiplied value of the integer value by a value counted in a unit of integral times of a single line address according to a sub-scan control signal within a range below the capacitance of said delay memory is called a low-address.

In an image reading apparatus having a plurality of line sensors including an image sensing means for converting optical image information into an electrical signal, an analog-to-digital converting means for converting a signal from said image sensing means into a digital signal, and a sensor-to-sensor distance correcting means, a circuit for correcting a distance between sensors comprising:

• an extra-line corrector for correcting a registration error of an integer line unit among distances between sensors by housing sensor data for reading an image at a preceding position on a manuscript using red and green signal delay memories, delaying the housed sensor data until sensor data at a next position is read, and reading the delayed sensor data when sensor data at the last position is read;
• and
• an intra-line corrector for correcting a decimal point unit registration error among the distances between sensors using a look-up table for housing interpolation kernel data, wherein said intra-line corrector comprises:
• a line delay memory;
• a data register for arbitrarily storing data output from said line delay memory to perform an interpolation operation;
• an interpolation kernel look-up table having said interpolation kernel value;
• a kernel register for storing a coefficient value of an interpolation point to be referred according to an interpolation kernel offset;
• and
• an operator for performing multiplying and adding operations, wherein the number of said registers is set to be the same as that of interpolation points according to a selected interpolation algorithm, and each of said resistors performs a shift according to an interpolation operation.