Patent ID: 6965455
Filing Date: 2005-11-15
Classification: H04N

Abstract:
1. An image scanning device for scanning an image on an original document placed on a document table, by using light irradiation means scanned along the document table, the image scanning device comprising: a stepping motor for moving the light irradiation means with use of either one of first and second phase exciters which are of different phase excitation modes and which provide different step angles; reception means for receiving a scanning magnification for the image of the original document, supplied from an external device; first movement means for controlling the stepping motor to move the light irradiation means by accelerating it to a first moving speed based on a minimum scanning magnification for the image of the original document, from an initial position located outside a document scanning region of the document table to a first predetermined position, said first movement means moving the light irradiation means by rotating the stepping motor by use of a first amount of current by a first step angle by excitation of the first phase exciter by supplying a driving clock of a first frequency to the first phase exciter; second movement means for controlling the stepping motor to move the light irradiation means at the first moving speed based on the minimum scanning magnification for the image of the original document, from the first predetermined position to a second predetermined position located outside the document scanning region of the document table, said second movement means moving the light irradiation means by rotating the stepping motor by use of the first amount of current by excitation of the first phase exciter by supplying a driving clock of the first frequency to the first phase exciter; third movement means for controlling the stepping motor to move the light irradiation means by decelerating from the first moving speed based on the scanning magnification, if the received scanning magnification is that other than the minimum scanning magnification for the image of the original document, or by maintaining the first moving speed based on the scanning magnification if the received scanning magnification is the minimum scanning magnification, from the second predetermined position to a third predetermined position located outside a document scanning region of the document table, which varies its position depending on the scanning magnification of the image of the original document, said third movement means moving the light irradiation means by rotating the stepping motor by use of the first amount of current by excitation of the first phase exciter by supplying a driving clock of the first frequency to the first phase exciter; fourth movement means for controlling the stepping motor to move the light irradiation means at a second moving speed based on the scanning magnification, from the third predetermined position to a light irradiation start position of the document table and from the light irradiation start position of the document table to an end portion of the original document on the document table, said fourth movement means moving the light irradiation means by rotating the stepping motor by use of a second amount of current, smaller than the first amount of current, by a second step angle greater than the first step angle by excitation of the second phase exciter by supplying a driving clock of a second frequency higher than the first frequency to the second phase exciter; and photoelectric conversion means for converting an amount of reflection light while irradiating the original document on the document table by the light irradiating means moved by the fourth moving means, into an electric signal.