Lighting control circuit, passenger detection device, lighting control method, and passenger detection method

A lighting control circuit comprising:

• at least one light emitting element connected between a first terminal and a second terminal;
• a first switch to connect or disconnect the first terminal with or from a ground potential;
• a second switch to connect or disconnect the second terminal with or from the ground potential;
• a converter to selectively perform:
• converting a direct current input voltage into a first direct current output voltage having a same polarity as a polarity of the direct current input voltage and having magnitude capable of driving the light emitting element, and outputting the first direct current output voltage to the first terminal;
• and converting the direct current input voltage into a second direct current output voltage having a reverse polarity to the polarity of the direct current input voltage and having the magnitude capable of driving the light emitting element, and outputting the second direct current output voltage to the second terminal;
• and
• a monitor to monitor magnitude of the direct current input voltage, wherein
• when the monitor determines that the direct current input voltage is higher than a predetermined threshold voltage, the first switch disconnects the first terminal from the ground potential, the second switch connects the second terminal with the ground potential, and the converter outputs the first direct current output voltage to the first terminal, and
• when the monitor does not determine that the direct current input voltage is higher than the predetermined threshold voltage, the first switch connects the first terminal with the ground potential, the second switch disconnects the second terminal from the ground potential, and the converter outputs the second direct current output voltage to the second terminal.