Image forming system having plural sheet stackers and image forming method thereof

An image forming system comprising:

• (a) an image forming section for forming an image on a sheet;
• (b) a first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• (c) a second stacking section provided at a position different from the first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• (d) a common conveyance path for conveying the sheet with the image formed thereon by the image forming section;
• (e) a first conveyance path for conveying the sheet conveyed along the common conveyance path, to the first stacking section;
• (f) a second conveyance path longer than the first conveyance path for conveying the sheet conveyed along the common conveyance path, to the second stacking section,
• wherein an interval between adjoining sheets fed along the common conveyance path is smaller than a difference between the second and first conveyance paths;
• when images are formed on the sheets continuously one by one by the image forming section;
• (g) a switching section for switching a conveyance path of the sheet conveyed along the common conveyance path between the first conveyance path and the second conveyance path;
• and
• (h) a control device for controlling such that;
• when images are formed on continuous N-th sheet (N:
• natural number) and (N+1)th sheet, and the switching section is selected such that the N-th sheet is fed along the second conveyance path and the (N+1)th sheet is fed along the first conveyance path, and when the N-th sheet is jammed along the second conveyance path and the (N+1)th sheet is ejected to the first stacking section and image formation is restarted after the jammed N-th sheet has been cleared;
• the control device controls in such a way that the image forming section restarts the image formation from an image corresponding to the N-th and subsequent sheets, except for an image that has already been formed on the (N+1)th sheet and ejected to the first stacking section;
• and the sheet with an image corresponding to the N-th sheet formed thereon is fed along the second conveyance path by the switching section.

An image forming method used in an image forming system comprising:

• an image forming section for forming an image on a sheet;
• a first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• a second stacking section provided at a position different from the first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• a common conveyance path for conveying the sheet with the image formed thereon by the image forming section;
• a first conveyance path for conveying the sheet conveyed along the common conveyance path, to the first stacking section;
• a second conveyance path longer than the first conveyance path for conveying the sheet conveyed along the common conveyance path, to the second stacking section, wherein an interval between adjoining sheets fed along the common conveyance path is smaller than a difference between the second and first conveyance paths, when images are formed on the sheets continuously one by one by the image forming section;
• and a switching section for switching a conveyance path of the sheet conveyed along the common conveyance path between the first conveyance path and the second conveyance path, the image forming method comprising the steps of:
• stacking an N-th sheet on the second stacking section;
• and
• then stacking an (N+1)th sheet on the first stacking section so that an arrival timing of the (N+1)th sheet at the first stacking section is delayed without stopping the continuous image formation by the image forming section, when the switching section is selected in such a way that the N-th sheet with an image formed thereon is conveyed along the second conveyance path, and the (N+1)th sheet with an image formed thereon is conveyed along the first conveyance path during continuous image formation, where N represents a natural number.

An image forming method used in an image forming system comprising:

• an image forming section for forming an image on a sheet;
• a first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• a second stacking section provided at a position different from the first stacking section for stacking the sheet with the image formed thereon by the image forming section;
• a common conveyance path for conveying the sheet with the image formed thereon by the image forming section;
• a first conveyance path for conveying the sheet conveyed along the common conveyance path, to the first stacking section;
• a second conveyance path longer than the first conveyance path to guide the sheet conveyed along the common conveyance path, to the second stacking section, wherein an interval between adjoining sheets fed along the common conveyance path is smaller than a difference between the second and first conveyance paths, when images are formed on the sheets continuously one by one by the image forming section;
• and a switching section for switching a conveyance path of the sheet conveyed along the common conveyance path between the first conveyance path and the second conveyance path, and when images are formed on continuous N-th sheet and (N+1)th sheet, and the switching section is selected such that the N-th sheet is fed along the second conveyance path and the (N+1)th sheet is fed along the first conveyance path, where N represents a natural number,
• the image forming method comprising the steps of:
• restarting image formation from an image corresponding to the N-th and subsequent sheets, except for an image which has been formed on the (N+1)th sheet and ejected to the first stacking section, after the N-th sheet has been jammed along the second conveyance path and has been cleared;
• and
• conveying a sheet with an image corresponding to the N-th sheet formed thereon to the second conveyance path by the switching section.