The present idea provides a high read and write performance fromto a solid state memory device. The backlight system includes a light source, a light homogenization mechanism, and a back frame. A plurality of exhaust ducts having inlets at different positions in each drying chamber are provided, and the exhaust duct having the inlet in the lowest gas concentration area is used as a duct for an exhaust gas circulated to a circulation blower. The location beacons may be rechargeable via ambient light and require no external power source. In one possible use, an image is reverse-printed on the ink-receptive layer. A pilot, including a circumferential spark gap, is provided to improve starting reliability.