HF power device for driving discharge lamp and frequency setting method thereof

Abstract

The invention is concerned with the high-frequency power equipment and the frequency setting method of the driving discharge light, especially the high-frequency power equipment to drive the CCFL,EEFL,FFL and other discharge light. For achieve the aims that adjusts light and improves the power transform efficiency, the invention use a discriminator to control a phase-locked loop and a break lightprotection circuit simultaneously, achieves the closed loop regulation of the work frequency and the monitor protection after the fault of the break light during the normal work processing.

Description

technical field [0001] The invention relates to a high-frequency power supply device for driving discharge lamps and a frequency setting method thereof, in particular to a high-frequency power supply device for driving CCFL, EEFL, FFL and other discharge lamps. Background technique [0002] Liquid crystal display technology has been widely used in various electronic devices, such as mobile phones with small screens, laptops with medium screens, and electronic billboards with large screens. Discharge lamps, especially cold cathode fluorescent lamps (Coldcathode fluorescent lamps, CCFL), are often used as backlight systems for liquid crystal displays due to their high luminous efficiency and long lamp life. At this time, the discharge lamp is driven by a power converter (Inverter). Power converters convert DC or low frequency power to high frequency power. [0003] The discharge lamp power converter is usually composed of a control circuit, a switching network and a filter c...

AI Technical Summary

Problems solved by technology

However, it is impossible to change the system operating frequency and control the natural resonant frequency of the filter circuit by using PWM technology to adjust the pulse duty cycle dimming scheme, which undoubtedly cannot take into account both dimming and improving power consumption efficiency during the normal operation of the system dual purpose

[0009] Second, in order to ensure the safety of the system, the light-off protection system must respond quickly

However, in the existing lamp-off protection circuit, since the voltage and current in the reactance element in the filter circuit cannot change suddenly, a transition process is required for the lamp voltage to rise and the lamp current to drop, which is not good for system safety.

[0010] Third, the filter circuit in the high-frequency power supply device of the discharge lamp is generally composed of ordinary reactive components in order to reduce the cost of the power supply. Its frequency stability is low, and it is necessary to implement frequency tracking and frequency locking

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