Sheet laminator and image forming system incorporating the sheet laminator

1. A sheet laminator comprising:

a thermal fixing roller pair including:

a first thermal fixing roller; and

a second thermal fixing roller facing the first thermal fixing roller, and

the thermal fixing roller pair configured to thermally fix and convey a two-ply sheet and a sheet medium nipped between two sheets of the two-ply sheet;

a first heater configured to heat the first thermal fixing roller;

a second heater configured to heat the second thermal fixing roller;

multiple temperature detectors at different positions along an axial direction of the thermal fixing roller pair, the multiple temperature detectors configured to detect a surface temperature of each of the thermal fixing roller pair; and

a driver configured to drive the thermal fixing roller pair.

2. The sheet laminator according to claim 1 ,

wherein each of the thermal fixing roller pair includes:

a core metal portion at a center portion of each of the thermal fixing roller pair;

an elastic layer around the core metal portion; and

a fluororesin layer on a surface of the elastic layer.

3. The sheet laminator according to claim 1 , wherein:

the multiple temperature detectors include:

a first temperature detector at a center portion of the first thermal fixing roller in the axial direction; and

a second temperature detector at a center portion of the second thermal fixing roller in the axial direction, and

the first temperature detector and the second temperature detector are at different positions from each other in the axial direction.

4. The sheet laminator according to claim 3 ,

wherein the multiple temperature detectors further include a third temperature detector at:

an end portion of the first thermal fixing roller in the axial direction; and

outside a conveyance area of the two-ply sheet of the thermal fixing roller pair.

5. The sheet laminator according to claim 4 , wherein:

the multiple temperature detectors further include a fourth temperature detector at:

an end portion of the second thermal fixing roller in the axial direction; and

outside a conveyance area of the two-ply sheet of the thermal fixing roller pair, and

the third temperature detector and the fourth temperature detector are at different positions from each other in the axial direction across the conveyance area of the two-ply sheet of the thermal fixing roller pair.

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

a first thermostat facing the first thermal fixing roller; and

a second thermostat facing the second thermal fixing roller,

wherein the first thermostat is configured to:

detect a first ambient temperature of the first thermal fixing roller; and

disconnect the first heater from the first thermal fixing roller in response to a detection of the first ambient temperature equal to or higher than a first given value, and

the second thermostat is configured to:

detect a second ambient temperature of the second thermal fixing roller; and

disconnect the second heater from the second thermal fixing roller in response to a detection of the second ambient temperature equal to or higher than a second given value.

7. An image forming system comprising:

the sheet laminator according to claim 1 ; and

an image forming apparatus configured to form an image on a sheet medium to be supplied to the sheet laminator.