The study on the protection circuit of the inverter for LCD backlight using digital control method

The way of operating multiple CCFLs in parallel is adopted for ensuring the evenness of brightness while reducing the price of inverters for operating backlights according to the trend of producing larger LCD televisions. However, if any of the multiple CCFLs is turned on first, parallel (circuit) resistance is shown as further resistance of a lighted lamp. In this case, resting CCFLs, which are not turned on, do not have sufficient voltage for lighting; therefore, they rest unlit, and a problem arises because of the imbalance of brightness owing to the difference of excessive electric current between each CCFL. This thesis studied the imbalance of the output voltage of the electric current that is generated from an inverter for operating LCD backlights, designed the inverter protection function for OVP (overvoltage protection), LCC (limited current circuit), and OLP (open lamp protection) as a digital type circuit based on the study, and compared the function with the existing analogue type protection circuit.