Printer and method for controlling printer

A printer, comprising:

• a platen roller;
• a print head for performing printing on a recording paper;
• a first detection switch for detecting a position of one side of the platen roller;
• a second detection switch for detecting a position of another side of the platen roller;
• and
• a potential detector;
• wherein both of the first and second detection switches are switched off when the platen roller is mounted, and are switched on when the platen roller is not mounted,
• wherein one terminal of the first detection switch and one terminal of the second detection switch are connected to each other and grounded,
• wherein another terminal of the first detection switch and another terminal of the second detection switch are connected to each other and to be connected to a power supply via a resistor,
• wherein the potential detector is configured to detect a potential between the another terminals of the first and second detection switches and the resistor.

A method for controlling a printer including a platen roller, a first detection switch for detecting a position of one side of the platen roller which is switched off when the platen roller is mounted and is switched on when the platen roller is not mounted, a second detection switch for detecting a position of another side of the platen roller which is switched off when the platen roller is mounted and is switched on when the platen roller is not mounted, and a potential detector, the method comprising:

• detecting a potential at terminals of the first and second detection switches;
• determining that the platen roller is mounted when the potential is lower than a first threshold;
• and
• determining that the platen roller is not mounted when the potential is higher than a second threshold that is higher than the first threshold.