Patent ID: 7499066
Filing Date: 2009-03-03
Classification: G03G,H04N

Abstract:
1. An image forming apparatus, comprising: a plurality of latent image bearing members; a plurality of visible image forming units each including development means for developing latent images on said corresponding latent image bearing member to form visible images thereon; a light scanning means for forming said latent images on said latent image bearing members, said scanning means including a deflecting means for deflecting image information light to form said latent images on surfaces of said latent image bearing members; an endless intermediate transfer member; means for rotating said endless intermediate transfer member; a transfer means for transferring said visible images formed by said visible image forming units in a manner to be superposed on said endless intermediate transfer member; a mark detection means for detecting a base mark affixed onto a predetermined location on a surface of said endless intermediate transfer member and providing a mark detection signal corresponding thereto; a standard angle detection means for detecting the light deflected by said deflecting means arriving at a predetermined angle of deflection; and a deflection angle phase correction means included in said light scanning means for correcting a phase of change in angle of deflection caused by said deflecting means based on at least the mark detection signal from said mark detection means and a standard angle detection signal from said standard angle detection means, wherein said light scanning means is configured to carry out light scanning onto said plurality of latent image bearing members such that at least one pair of neighboring visible image forming units of said plurality of visible image forming units are both subjected to the light scanning by a same deflecting means, wherein said endless intermediate transfer member is adapted to be rotated for a plurality of rounds by said means for rotating such that the surface of the endless intermediate transfer member is superposed thereon with plural visible images each provided by a same of said visible image forming units for one of rounds of rotation of the endless intermediate transfer member; wherein said plurality of visible image forming units each further includes first and second visible image forming units to constitute said pair of neighboring visible image forming units, such that, after forming a double-color image by sequentially transferring to superpose said plural visible images each formed by said first and second visible image forming units onto the surface of said endless intermediate transfer member during a first round of rotation of said endless intermediate transfer member, a quadruple-color image is formed by sequentially transferring to superpose plural visible images each formed by said first and second visible image forming units onto said double-color image during a second round of rotation of said endless intermediate transfer member; wherein said light scanning means is further configured, after storing a time lag dt wherein said light scanning means is further configured to store in advance a predetermined base correction time; initiate optical image writing for the first round of rotation of said endless intermediate transfer member onto said latent image bearing member included in said first visible image forming unit based on said standard angle detection signal detected after a time Te determined as a time elapsed by a base correction time t