Image forming apparatus, image forming method, and computer program product

An image forming method performed by an image forming apparatus that includes a sensor and detects an image on an intermediate transfer medium using the sensor, the image forming method comprising:

• transferring, by both a direct-transfer medium and a first image forming unit that forms a single-color image, the single-color image onto either the direct-transfer medium or a transfer sheet, wherein both the direct-transfer medium and the first image forming unit are under the control of a direct-transfer control unit and both the direct-transfer medium and the transfer sheet move due to the rotation of the direct-transfer medium;
• transferring, by both an intermediate transfer medium and a second image forming that forms a multi-color image, the multi-color image onto the intermediate transfer medium, wherein both the indirect-transfer medium and the second image forming unit are under the control of an indirect-transfer control unit;
• transferring, as a secondary transfer by a secondary-transfer control unit, after the single-color image has been transferred by the direct-transfer control unit onto the direct-transfer medium, the single-color image onto the intermediate transfer medium;
• and
• calculating, by a positional-alignment control unit using the sensor, an amount of misalignment of the image and correcting, using a position of an image formed by the first image forming unit as a reference position, positions of images to be formed by the second image forming unit in accordance with the calculated amount of misalignment.

A computer program product comprising a computer-usable medium having computer-readable program codes embodied in the medium for forming an image in an image forming apparatus that includes a sensor and detects an image on an intermediate transfer medium using the sensor, the program codes when executed causing a computer to execute:

• transferring, by both a direct-transfer medium and a first image forming unit that forms a single-color image, the single-color image onto either the direct-transfer medium or a transfer sheet, wherein both the direct-transfer medium and the first image forming unit are under the control of a direct-transfer control unit and both the direct-transfer medium and the transfer sheet move due to the rotation of the direct-transfer medium;
• transferring, by both an intermediate transfer medium and a second image forming that forms a multi-color image, the multi-color image onto the intermediate transfer medium, wherein both the indirect-transfer medium and the second image forming unit are under the control of an indirect-transfer control unit;
• transferring, as a secondary transfer by a secondary-transfer control unit, after the single-color image has been transferred by the direct-transfer control unit onto the direct-transfer medium, the single-color image onto the intermediate transfer medium;
• and
• calculating, by a positional-alignment control unit using the sensor, an amount of misalignment of the image and correcting, using a position of an image formed by the first image forming unit as a reference position, positions of images to be formed by the second image forming unit in accordance with the calculated amount of misalignment.