Printer capable of preventing paper jam

1. A printer for conveying a sheet of a roll paper type to perform printing thereon, the printer comprising a transverse tension sensor for detecting that the sheet being discharged from a discharge port has deviated in a paper width direction orthogonal to a discharging direction,

wherein the transverse tension sensor comprises:

a pair of movable pieces, each of which is displaced when the sheet has been displaced to one side and another side in the paper width direction; and

a sensor portion for detecting displacement of the pair of movable pieces as a state where the sheet has deviated in the paper width direction,

wherein the pair of movable pieces are provided with guide portions, respectively, the guide portions being arranged in rear of the discharge port in the discharging direction so as to sandwich therebetween the sheet in the paper width direction;

wherein the guide portions are biased by bias means inward in the paper width direction so as to have an interval therebetween corresponding to a width dimension of the sheet;

wherein the bias means biases the guide portions with a biasing force larger than a force of discharging the sheet; and

wherein conveyance of the sheet is stopped based on a detection signal of the transverse tension sensor.

2. The printer according to claim 1 , further comprising a front cover mounted to a front surface of the printer in a removable manner so as to cover an inside of the printer, the front surface having a discharge port formed therein,

wherein the pair of movable pieces and the sensor portion are mounted on an inner side of the front cover.

3. The printer according to claim 1 , wherein:

the pair of movable pieces are coupled together so as to move in association with each other; and

the sensor portion is provided in common to the pair of movable pieces.

4. The printer according to claim 1 , wherein:

the pair of movable pieces are coupled together so as to move in association with each other; and

the bias means is provided in common to the pair of movable pieces.

5. The printer according to claim 1 , wherein the sensor portion comprises any one of an optical sensor, a magnetic sensor, and a mechanical switch.

6. The printer according to claim 1 , wherein the bias means comprises any one of a coil spring, a leaf spring, and a weight.

7. The printer according to claim 1 , further comprising:

a retreat region for the sheet, which is formed in a thickness direction of the sheet so as to communicate to a sheet conveyance path; and

a deflection sensor provided in the retreat region, for detecting the sheet that has entered the retreat region when discharge has been hindered,

wherein the conveyance of the sheet is stopped based on the detection signal of the transverse tension sensor or a detection signal of the deflection sensor.

8. The printer according to claim 1 , further comprising means for informing, when the conveyance of the sheet has been stopped, a user of the stop of the conveyance of the sheet.