Original reader capable of reading originals of various sizes and method of reading original

An original reader comprising:

• a conveying unit configured to conveying an original;
• an original detection unit disposed in a conveying path for conveying the original and configured to detect the conveyed original;
• a first reading unit configured to read a first side of the conveyed original;
• a second reading unit configured to read a second side of the conveyed original, which is different from the first side;
• a storage unit configured to store first image data output from said first reading unit and second image data output from said second reading unit;
• and
• a control unit configured to control writing of the first image data and the second image data in said storage unit, and reading of the first image data and the second image data stored in said storage unit,
• wherein said control unit sets a write start position at which the second image data starts to be written in said storage unit, after a storage area in which the first image data is written, and
• wherein said control unit writes part of the second image data in a storage area from which the first image data written in said storage unit has been read out from said storage unit.

A document reading method executed by a document reader comprising:

• a tray on which a document is mounted;
• a sensor configured to detect a width of the document mounted on the tray;
• a conveying unit configured to convey the document mounted on the tray along a conveying path;
• a detection unit configured to detect the conveyed document;
• a reading unit configured to read the conveyed document;
• a memory configured to store the image data output from the reading unit;
• and
• a communication line configured to communicate with a controller;
• wherein the document reading method comprises a determining step of determining a size of the conveyed document based on a result of detection by the sensor,
• the determining step including the steps of:
• (i) in a case where the size of the conveyed document is determined in the determining step,
• notifying, the determined size to the controller through the communication line,
• writing the image data output from the reading unit in the memory, and
• transmitting the image data stored in the memory to the controller through the communication line;
• and
• (ii) in a case where the size of the conveyed document is not determined in the determining step;
• transmitting the maximum one of a plurality of document sizes, which are candidates of the size of the document to be selected in said determining step, to the controller through the communication line;
• writing the image data output from the reading unit in the memory based on a request signal received from the controller through the communication line;
• finalizing the size of the conveyed document based on a result of detection of the detection unit;
• transmitting, in a case where the finalized size and the determined size are identical with each other, the image data stored in the memory to the controller through the communication line;
• notifying, in a case where the finalized size and the determined size are different from each other, the finalized size to the controller through the communication line;
• and
• transmitting the image data stored in the memory to the controller through the communication line according to the request signal received from the controller through the communication line.

A method of reading an original, comprising:

• conveying an original;
• detect the conveyed original;
• reading a first side of the conveyed original;
• reading a second side of the conveyed original, which is different from the first side;
• storing first image data output by said reading the first side and second image data output by said reading the second side, in a storage unit;
• controlling writing of the first image data and the second image data in the storage unit, and reading of the first image data and the second image data stored in the storage unit;
• setting a write start position at which the second image data starts to be written in the storage unit, after a storage area in which the first image data is written;
• and
• writing part of the second image data in a storage area from which the first image data written in the storage unit has been read out from the storage unit.