The image reading device of the present invention reads images by using a visible
light and an invisible light that are generated by a single light source. The fluorescent
lamp is provided with a pair of internal electrodes and a pair of external electrodes.
It generates a visible light with a higher intensity than an infrared light when
switching a feeder circuit on to generate a discharge between the external electrodes.
On the other hand, it generates an infrared light with a higher intensity than
a visible light when switching another feeder circuit on to generate a discharge
between the internal electrodes. Therefore, the fluorescent lamp has a reading
mode using the visible light, and a reading mode using the infrared light. And,
a lamp controller selectively switches the emission mode of the fluorescent lamp.
