Due to the rapid progress of the electrical and semiconductor technology, liquid crystal display (LCD) is widely utilized in electrical appliance displays. The LCD has many advantages over other conventional types of displays including high display quality, small volume occupation, a light weight, a low driving voltage and a low power consumption. Hence, LCDs are widely used in small portable televisions, mobile telephones, video recording units, notebook computers, desktop monitors, projector televisions and so on. Therefore, the LCD has gradually replaced the conventional cathode ray tube (CRT) as a mainstream display unit.
Backlights of LCD displays of notebook computers or portable electrical products normally are a cold cathode fluorescent lamp because the cold cathode fluorescent lamp possess higher backlight luminous efficacy. However, the cold cathode fluorescent lamp is triggered by alternating current signals, and therefore needs an inverter transformer for power.
Conventionally, each cold cathode fluorescent lamp uses an inverter transformer for a power supply. Due to the increased size of LCD panels, the backlight needs to provide more brightness to light up the LCD. Therefore, the backlight has to increase the quantity of the cold cathode fluorescent lamps to provide greater illumination for an LCD, and more inverter transformers are necessary to supply enough power to the cold cathode fluorescent lamps. Hence, the LCD volume is increased and the manufacturing cost is also increased due to the increase in number of components.