A system for providing a backlight module has a light guide plate and at least a light source set positioned adjacent to the incident surface. Transition speech frames are encoded with the high-rate, time-domain coding mode, which may be a CELP coding mode. If the ink remaining amount of at least one of the cartridges is smaller than a threshold value, a display control section determines that the cartridge requires replacement and operates a display to display an ink-end screen. The first switch and the second switch may be turned on or off based on the detected temperature of the head or ink in the head.