In electronics, an inverter can be defined as a device for converting direct current (DC) power into alternating current (AC). An example of an inverter is the adapter used in cars for converting the low voltage cigarette lighter’s power (DC) into mains equivalent voltage (AC). This allows the use of many types of household electrical devices while on the road. In a laptop, an inverter is often used to light the computer's screen.
A laptop inverter is a small circuit board, usually about the size of a pen. Internally, a laptop runs on a low voltage, with the exception of the screen, which uses a backlit liquid crystal display (LCD). Without the inverter and the bulb it powers, the screen would be too faint to see properly. By controlling the output of the inverter, the laptop can adjust the brightness of its display. Some types of laptop inverter are able to do this automatically by using a small sensor to detect how bright the room is, and adjusting their output accordingly.
The LCDs in traditional laptops are lighted by one or two thin fluorescent bulbs that require a higher voltage than the rest of the computer. The inverter is typically housed close to the lamp, keeping its power wires as short as possible and to avoid running them through other parts of the machine unnecessarily. Less commonly, some laptops use white light emitting diodes (LEDs) to provide the backlight. These laptops do not require an inverter at all, since the LEDs can take their power directly from the laptop’s motherboard.
As with any electronic component, faults can occur in laptop inverters, especially after years of use. Common symptoms include the screen flickering on and off, the screen appearing too faint to read, and even sometimes a faint buzzing noise. It should be noted that there are other possible causes for all these symptoms, which are best diagnosed by a laptop technician or other qualified professional. If found to be faulty, the laptop inverter can usually be replaced.
Each model of laptop will have a specific inverter design, and they are generally not interchangeable. Replacing an inverter is a relatively quick and inexpensive fix, and is usually more cost effective than getting it repaired. The replacement process simply involves removing the screen bezel, unplugging the old inverter, and replacing it with the new one. A laptop inverter carries a high voltage warning, and should only be replaced by a qualified professional under static-controlled conditions.