Image reading device, method of adjusting distance between document and light receiving sensor in the device, and distance adjustment program

A method of adjusting a distance between a document and light receiving sensors executed in an image reading device comprising:

• a plurality of light receiving sensors, which use an optical shrink system, configured to read an image of a document conveyed in a sub-scanning direction and be arranged at intervals in a main scanning direction, the plurality of light receiving sensors arranged so that border parts of reading areas of adjacent two of the light receiving sensors in the main scanning direction correspond to each other on or under a reference conveyance plane of the document;
• and
• at least one pair of document conveying rollers configured to be provided in front and back of the plurality of light receiving sensors in the sub-scanning direction,
• the method comprising:
• an overlap amount/missing amount detection step of detecting an image overlap amount in an image overlap area which occurs when a part of the document in the main scanning direction is redundantly read by adjacent two of the light receiving sensors in a case where the document is conveyed at a position apart from the reference conveyance plane as being away from the light receiving sensors and/or an image missing amount in an image missing area which occurs when a part of the document in the main scanning direction is not read by any of the adjacent two light receiving sensors in a case where the document is conveyed at a position apart from the reference conveyance plane as being closer to the light receiving sensors, from a plurality of parts in the main scanning direction of the image data of the document read by the light receiving sensors;
• an adjustment amount determination step of determining an adjustment amount used to adjust a distance between the document and the light receiving sensors in at least one part of the document in the main scanning direction based on the image overlap amount and/or image missing amount detected in the overlap amount/missing amount detection step;
• and
• a driving step of adjusting the distance between the document and the light receiving sensors by displacing at least one of the document conveying rollers and the light receiving sensors according to the adjustment amount determined in the adjustment amount determination step.

A non-transitory recording medium storing a computer readable program for adjusting a distance between a document and light receiving sensors, the program causing a computer of an image reading device comprising:

• a plurality of light receiving sensors, which use an optical shrink system, configured to read an image of a document conveyed in a sub-scanning direction and be arranged at intervals in a main scanning direction, the plurality of light receiving sensors arranged so that border parts of reading areas of adjacent two of the light receiving sensors in the main scanning direction correspond to each other on or under a reference conveyance plane of the document;
• and
• at least one pair of document conveying rollers configured to be provided in front and back of the plurality of light receiving sensors in the sub-scanning direction
• to execute:
• a detection step of detecting an image overlap amount in an image overlap area which occurs when a part of the document in the main scanning direction is redundantly read by adjacent two of the light receiving sensors in a case where the document is conveyed at a position apart from the reference conveyance plane as being away from the light receiving sensors and/or an image missing amount in an image missing area which occurs when a part of the document in the main scanning direction is not read by any of the adjacent two light receiving sensors in a case where the document is conveyed at a position apart from the reference conveyance plane as being closer to the light receiving sensors, from a plurality of parts in the main scanning direction of the image data of the document read by the light receiving sensors;
• a determination step of determining an adjustment amount for adjusting a distance between the document and the light receiving sensors in at least one part of the document in the main scanning direction based on the image overlap amount and/or image missing amount detected in the overlap amount/missing amount detection step;
• and
• an adjusting step of adjusting the distance between the document and the light receiving sensors by displacing at least one of the document conveying rollers and the light receiving sensors according to the adjustment amount determined in the adjustment amount determination step.