Correction information creation device, image formation device, correction information creation program storage medium and correction information creation method

A computer readable storage medium storing a program causing a computer to execute a process for correcting a period of a clock signal of an image formation apparatus, the image formation apparatus comprises:

• a recording head in which a plurality of image formation elements are two-dimensionally arranged such that the image formation elements are not aligned in a sub-scanning direction, the image formation elements respectively forming dots that constitute an image at a predetermined surface synchronously with the clock signal;
• and a rotating body that rotates with a peripheral surface thereof opposing the image formation elements, the rotating body functioning as one of a transfer body that transfers an image formed at the peripheral surface by the image formation elements to a surface of a recording medium or a conveyance body that conveys the recording medium, in a state in which the recording medium is retained at the peripheral surface, such that the surface of the recording medium opposes the image formation elements, the process comprising:
• detecting a period of a pulse signal generated in accordance with rotation of the rotating body;
• calculating a period of the clock signal on the basis of a reference rotation angle of the rotating body at which the pulse signal is generated, a distance between neighboring dots, an ideal distance between the peripheral surface of the rotating body and an axial center of the rotating body, and the detected period of the pulse signal;
• while the rotating body being rotated at a predetermined rotation speed, causing at least two sets of image formation elements of the plurality of image formation elements to sequentially form corrective images, which are used for correcting the period of the clock signal, at different positions of the peripheral surface, synchronously with a clock signal with the calculated period, wherein the at least two sets of image formation elements comprises a first set of image formation elements disposed at upstream side in a rotation direction of the rotating body, and a second set of image formation elements disposed at downstream side in the rotation direction, the at least two sets of image formation elements are separated from each other by a predetermined space in the rotation direction;
• detecting a space between the formed corrective images;
• calculating a distance between a measurement position of the peripheral surface of the rotating body and the axial center of the rotating body on the basis of the detected space between the corrective images, a value obtained by multiplying the distance between the dots by a predetermined integer, the predetermined space, and the ideal distance between the peripheral surface of the rotating body and the axial center of the rotating body;
• and
• storing distance information representing the calculated distance, to serve as information for correcting the period of the clock signal, in association with a measurement rotation angle from a reference position of the rotating body to the measurement position.

A method of correcting a period of a clock signal of an image formation apparatus, the image formation apparatus comprising:

• a recording head at which a plurality of image formation elements are two-dimensionally arranged such that the image formation elements are not aligned in a sub-scanning direction, the image formation elements respectively forming dots that constitute an image at a predetermined surface synchronously with the clock signal;
• and a rotating body that rotates with a peripheral surface thereof opposing the image formation elements, the rotating body functioning as one of a transfer body that transfers an image formed at the peripheral surface by the image formation elements to a surface of a recording medium or a conveyance body that conveys the recording medium, in a state in which the recording medium is retained at the peripheral surface, such that the surface of the recording medium opposes the image formation elements, the method comprising:
• detecting a period of a pulse signal generated in accordance with rotation of the rotating body;
• calculating a period of the clock signal on the basis of a reference rotation angle of the rotating body at which the pulse signal is generated, a distance between neighboring dots, a distance ideal between the peripheral surface of the rotating body and an axial center of the rotating body, and the detected period of the pulse signal;
• while the rotating body being rotated at a predetermined rotation speed, causing at least two sets of image formation elements of the plurality of image formation elements to sequentially form corrective images, which are used for correcting the period of the clock signal, at different positions of the peripheral surface, synchronously with a clock signal occurring at the calculated period, wherein the at least two sets of image formation elements comprises a first set of image formation elements disposed at upstream side in a rotation direction of the rotating body, and a second set of image formation elements disposed at downstream side in the rotation direction, the at least two sets of image formation elements are separated from each other by a predetermined space in the rotation direction;
• detecting a space between the formed corrective images;
• calculating a distance between a measurement position of the peripheral surface of the rotating body and the axial center of the rotating body on the basis of the detected space between the corrective images, a value obtained by multiplying the distance between the dots by a predetermined integer, the predetermined space, and the ideal distance between the peripheral surface of the rotating body and the axial center of the rotating body;
• and
• storing distance information representing the calculated distance, to serve as information for correcting the period of the clock signal, in association with a measurement rotation angle from a reference position of the rotating body to the measurement position.