1. Field of the Invention
The present invention relates to the field of power supply, and more particularly, to a power supply apparatus for an LED lamp, which utilizes the principle of persistence of vision of human eyes to modulate the waveforms and frequencies of voltages for driving LEDs and can still maintain the normal operation.
2. Description of the Related Art
As compared with conventional light sources, light emitting diodes (LEDs) have the advantages of operating at a low voltage, low power consumption and a long service life, etc. Therefore, in modern life, LEDs have been widely used in various related fields, where a light source is required, for example, applied to display backlight modules, indicating light sources, general lighting equipment, and the like. LEDs have the especially significant advantage of energy saving, so their practicability is particularly important in the most general purpose of lighting.
The principle of a traditional power supply for driving an LED lamp is mainly that an inputted high voltage alternating current is rectified, filtered and then converted by a transformer into a low voltage alternating current then being processed by a rectifier and an electrolytic capacitor filter circuit into a stable voltage DC output for driving corresponding LED lamps. The prior art uses large capacitance characteristics of electrolytic capacitors to reduce the occurrence of ripples and thus to achieve a stable voltage DC output. However, most external environmental factors will deteriorate the performance of electrolytic capacitors such that electrolytic capacitors typically have a shorter life than other types of capacitors. Among environmental factors, temperature has the most tremendous impact on the life of electrolytic capacitors, and for example, the intense heat caused by ripple currents is one of the reasons. The intense heat will accelerate the performance deterioration of electrolytic capacitors to reduce the life and static capacity to only a fraction of the original, and thus the capacitors are tantamount to having no filter capacitor function. Therefore, even if an LED lamp has a longer life, there is no filter capacitor to effectively match the longer life for the normal operation of the LED lamp.
In view of the above-described circumstances, the invertors conducted elaborate research with accumulated years of experience in this field, so as to develop a power supply apparatus for an LED lamp, which mainly utilizes the principle of persistence of vision of human eyes to modulate the waveforms and frequencies of voltages for driving LEDs and can still maintain the normal operation. Also, with no need to convert an AC voltage into a stable DC output as in the prior art, the present invention uses a longer life non-electrolytic capacitor for wave filtering to control the waveforms and frequencies of any voltages outputted to an LED lamp to be greater than or equal to 60 Hertz and control peak-to-peak values of ripple signals to be greater than or equal to 1 volt. Furthermore, feedback control facilitates to maintain the output within the operating range so as to effectively drive the LED lamp, thus improving the overall service life of the LED lamp.