Image reading method and apparatus determining synchronous position

An image reading apparatus comprising:

• an image reader including a platen on which an original rests, a reading scanner for irradiating reading light extending in a one-dimensional direction to the original on the platform, a drive means for translating the reading scanner at a predetermined scanning speed in a direction substantially perpendicular to said one-dimensional direction, and an photo-electric transducer means for receiving the reading light reflected by the original;
• an original transmission assembly removably disposed on the platen at a predetermined position, said assembly including a transmitting light source for emitting reading light extending in the one-dimensional direction toward a transparent original on the platen, and drive means for translating the transmitting light source in synchronization with the translation of said reading scanner;
• and
• synchronization means for providing synchronization in scanning speed between said transmitting light source and said reading scanner by
• disposing the original transmission assembly on the platen of said image reader,
• translating either one of said transmitting light source and said reading scanner to a selected position,
• scanning the other one of said transmitting light source and said reading scanner in the proximity of said selected position,
• obtaining the distribution of a quantity of light transmitted by the original during the scanning,
• determining a synchronous position for the other one corresponding to the selected position on the basis of said light quantity distribution,
• performing said synchronous position detection at two or more distinct positions,
• obtaining the number of pulses developed by the transferring to said synchronous position said transmitting light source and said reading scanner, and
• calculating from the number of pulses the pulse-to-distance conversion coefficient of at least one of said transmitting light source and said reading scanner.

A method for reading an image from a transparent original on a platen using a transmitting light source extending in a one-dimensional direction for emitting light toward the original and a reading scanner disposed below said platen and extending in said one-dimensional direction for receiving the light transmitted by the original, the method comprising the steps of:

• translating the transmitting light source in an auxiliary scanning direction substantially perpendicular to said one-dimensional direction for illuminating the original over a two dimensional extent;
• and
• translating the reading scanner in synchronization with said transmitting light source;
• thereby photoelectrically reading the image in the original, each of said transmitting light source and said reading scanner having a base point and a scan start position at which it is positioned at the start of scan reading of the original;
• wherein the step of providing matching between the scan start positions of said transmitting light source and said reading scanner prior to reading of the original comprising the steps of:
• positioning either one of said transmitting light source and said reading scanner at a selected position;
• scanning the other one of said transmitting light source and said reading scanner in the proximity of said selected position;
• obtaining the distribution of a quantity of light transmitted by the original during the scanning;
• determining a synchronous position for the other one corresponding to the selected position on the basis of said light quantity distribution;
• and
• determining the relative spacing between the base points of said transmitting light source and said reading scanner from the distances from the respective base points of said transmitting light source and said reading scanner to the synchronous position, the scan start positions being matched in accordance with the relative spacing.

An image reading apparatus comprising:

• an image reader including a platen on which an original rests, a reading scanner for irradiating reading light extending in a one-dimensional direction to the original on the platform, a drive means for translating the reading scanner at a predetermined scanning speed in a direction substantially perpendicular to said one-dimensional direction, and an photo-electric transducer means for receiving the reading light reflected by the original;
• an original transmission assembly removably disposed on the platen at a predetermined position, said assembly including a transmitting light source for emitting reading light extending in the one-dimensional direction toward a transparent original on the platen, and drive means for translating the transmitting light source in synchronization with the translation of said reading scanner,
• each of said transmitting light source and said reading scanner having a base point and a scan start position at which it is positioned at the start of scan reading of the original, and
• alignment means for providing matching between the scan start positions of said transmitting light source and said reading scanner prior to reading of the original by
• translating either one of said transmitting light source and said reading scanner at a selected position,
• scanning the other one of said transmitting light source and said reading scanner in the proximity of said selected position,
• obtaining the distribution of a quantity of light transmitted by the original during the scanning,
• determining a synchronous position for the other one corresponding to the selected position on the basis of said light quantity distribution;
• and
• determining the relative spacing between the base points of said transmitting light source and said reading scanner from the distances from the respective base points of said transmitting light source and said reading scanner to the synchronous position, the scan start positions being matched in accordance with the relative spacing.