Image forming apparatus
AssigneeKyocera Mita Corporation
InventorsTomoyuki Kitao, Masanori Okada
Life of this patent
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Abstract
A CPU (91) of an image forming apparatus includes a beam detecting part (911) that detects each of laser beams scanning by a predetermined number (e.g., four) of polygon mirrors (332) at a preset position (where a beam sensor (335) is disposed), a reference phase setting part (912) that sets a reference phase that is a phase to be a reference of the predetermined number of rotation phases of the polygon mirrors (332) based on a result of detection by the beam detecting part (911), and a phase control part (913) that controls polygon motor (330) so that predetermined number of rotation phases of the polygon mirrors (332) match the reference phase.
Claims18
An image forming apparatus that forms a color image through the steps of forming latent images by applying laser beams to photosensitive drums via polygon mirrors for a predetermined number of colors that is two or more, forming toner images corresponding to the formed latent images, and superposing the toner images of the predetermined number of colors to be transferred to a paper sheet, the image forming apparatus comprising:
- a number of polygon driving portions, equal to the predetermined number, that drive a number of polygon mirrors, equal to the predetermined number, to rotate at preset steady-state rotation frequencies;
- a number of beam detecting portions, equal to the predetermined number, that detect laser beams scanning by the predetermined number of polygon mirrors at preset positions on scanning paths;
- a reference phase setting portion that sets a substantially intermediate phase between a most leading phase and a most lagging phase among rotation phases of the predetermined number of polygon mirrors as a reference phase that is a phase to be a reference of the rotation phases of the predetermined number of polygon mirrors based on a result of detection by the predetermined number of beam detecting portions;
- and
- a phase control portion that controls the polygon driving portions so that rotation phases of the predetermined number of polygon mirrors match the reference phase.
An image forming method for use in an image forming apparatus that forms a color image through the steps of forming latent images by applying laser beams to photosensitive drums via polygon mirrors for a predetermined number of colors, forming toner images corresponding to the formed latent images, and superposing the toner images of the predetermined number of colors to be transferred to a paper sheet, the image forming apparatus including:
- a number of polygon driving portions, equal to the predetermined number, that drive a number of polygon mirrors, equal to the predetermined number, to rotate at preset steady-state rotation frequencies;
- and a number of beam detecting portions, equal to the predetermined number, that detect laser beams scanning by the predetermined number of polygon mirrors at preset positions on scanning paths,
- wherein the image forming method involves performing:
- a reference phase setting step for setting a substantially intermediate phase between a most leading phase and a most lagging phase among rotation phases of the predetermined number of polygon mirrors as a reference phase that is a phase to be a reference of the rotation phases of the predetermined number of polygon mirrors based on a result of detection by the predetermined number of beam detecting portions;
- and
- a phase control step for controlling the polygon driving portions so that rotation phases of the predetermined number of polygon mirrors match the reference phase.
Dependencies are inferred from the claim text.