Sheet laminator, image forming apparatus, and image forming system

1. A sheet laminator comprising:

a sheet separation device configured to perform:

a sheet separating operation to separate a non-bonding portion of a two-ply sheet in which two sheets are overlapped and bonded together at one end as a bonding portion of the two-ply sheet; and

a sheet inserting operation to insert an inner sheet between the two sheets separated from each other by the sheet separating operation;

a sheet lamination device configured to perform a sheet laminating operation on the two-ply sheet after the sheet separating operation and the sheet inserting operation performed by the sheet separation device; and

circuitry configured to cause the sheet lamination device to perform the sheet laminating operation on the two-ply sheet while causing the sheet separation device to perform the sheet separating operation on another two-ply sheet subsequent to the two-ply sheet or the sheet separating operation and the sheet inserting operation on said another two-ply sheet.

2. The sheet laminator according to claim 1 , further comprising:

a sheet conveyance passage from the sheet separation device to the sheet lamination device;

a retract sheet conveyance passage from the sheet separation device to a retract portion; and

a switcher configured to switch a state of the sheet conveyance passage and the retract sheet conveyance passage, between a first state in which the sheet conveyance passage is open and the retract sheet conveyance passage is closed and a second state in which the sheet conveyance passage is closed and the retract sheet conveyance passage is open.

3. The sheet laminator according to claim 1 , further comprising:

a sheet conveyance passage from the sheet separation device to the sheet lamination device; and

a sheet sensor disposed on the sheet conveyance passage.

4. The sheet laminator according to claim 1 ,

wherein the circuitry is configured to cause a leading end of said another two-ply sheet in a sheet conveyance direction to enter an extreme upstream portion of the sheet lamination device in the sheet conveyance direction after a trailing end of the two-ply sheet in the sheet conveyance direction passes the extreme upstream portion of the sheet lamination device.

5. The sheet laminator according to claim 4 ,

wherein the sheet lamination device includes a plurality of heat-pressure roller pairs aligned along the sheet conveyance direction, the plurality of heat-pressure roller pairs being configured to apply heat and pressure to the two-ply sheet, and

wherein the extreme upstream portion of the sheet lamination device is a nip region of an extreme-upstream heat-pressure roller pair of the plurality of heat-pressure roller pairs in the sheet conveyance direction.

6. The sheet laminator according to claim 4 ,

wherein the sheet lamination device includes a heat-pressure roller pair configured to apply heat and pressure to the two-ply sheet, and

wherein the extreme upstream portion of the sheet lamination device is a nip region of the heat-pressure roller pair.

7. The sheet laminator according to claim 1 , further comprising:

a winding roller configured to rotate in a predetermined rotational direction to wind the two-ply sheet;

a conveyance roller pair configured to convey the two-ply sheet with an opposite end opposite the one end being, as a leading end, toward the winding roller in a sheet conveyance passage between the winding roller and the conveyance roller pair;

a separator configured to insert into a gap formed in the non-bonding portion between the two sheets of the two-ply sheet at a position between the winding roller and the conveyance roller pair, in a state in which the two-ply sheet is wound from the opposite end of the two-ply sheet by the winding roller and the one end of the two-ply sheet is nipped by the conveyance roller pair;

two branched sheet conveyance passages branching off in different directions from the sheet conveyance passage interposed between the two branched sheet conveyance passages; and

a switcher configured to guide the two sheets separated by the separator, to the two branched sheet conveyance passages, respectively.

8. An image forming apparatus comprising:

a housing including an image forming device configured to form an image on a sheet; and

the sheet laminator according to claim 1 .

9. An image forming system comprising:

an image forming apparatus configured to form an image on a sheet; and

the sheet laminator according to claim 1 , detachably attached to the image forming apparatus.