Image forming apparatus and image forming system

A secondary image forming apparatus, comprising:

• a sheet feeding unit at which a sheet having a first image formed thereon can be received and placed on a sheet transfer path;
• a reading unit configured to detect a position of the first image on the sheet;
• an image forming unit including:
• an exposure unit configured to form a latent electrostatic image on a photoconductor according to image data supplied to the image forming unit;
• a developing unit configured to forma toner image on the photoconductor by developing the latent electrostatic image on the photoconductor;
• a transfer unit configured to transfer the toner image on the photoconductor to the sheet;
• and
• a fixing unit configured to fix the toner image transferred to the sheet to the sheet as a second image positioned relative to the first image on the sheet;
• and
• a control unit configured to receive the position of the first image on the sheet as detected by the reading unit and calculate a timing for transfer of the toner image on the photoconductor to the sheet by the transfer unit, and control the image forming unit according to the calculated timing.

An image forming system, comprising:

• a primary image forming apparatus configured to form a first image on a sheet and discharged the sheet with the first image formed thereon;
• and
• a secondary image forming apparatus including:
• a sheet feeding unit at which the sheet having the first image formed thereon can be received and placed on a sheet transfer path;
• a reading unit configured to detect a position of the first image on the sheet;
• an image forming unit including:
• an exposure unit configured to forma latent electrostatic image on a photoconductor according to image data supplied to the image forming unit;
• a developing unit configured to forma toner image on the photoconductor by developing the latent electrostatic image on the photoconductor;
• a transfer unit configured to transfer the toner image on the photoconductor to the sheet;
• and
• a fixing unit configured to fix the toner image transferred to the sheet to the sheet as a second image positioned relative to the first image on the sheet;
• a control unit configured to receive the position of the first image on the sheet as detected by the reading unit and calculate a timing for transfer of the toner image on the photoconductor to the sheet by the transfer unit, and control image forming unit according to the calculated timing.