Lamp tube status judgement circuit and its controller

Abstract

The invention relates to a DC / AC conversion circuit for driving a load. The DC / AC conversion drive circuit comprises a switch device, a resonant groove, a voltage detection circuit and a controller. The switch device is coupled with a DC power. The resonant groove is coupled with the switch device and the load which converts the electric power of the DC power from the switch device into an AC signal in order to drive the load. The voltage detection circuit is coupled with the load and generates a voltage detection signal according the load voltage. The controller is coupled with the voltage detection circuit and the switch device and controls the electric power of the DC power that is transmitted to the resonant groove through the switch device. The controller decides the change of the operating frequency on the basis of the voltage detection signals.

Description

technical field [0001] The invention relates to a DC / AC conversion fluorescent lamp drive circuit, in particular to a DC / AC conversion control circuit capable of frequency conversion according to the state of the lamp tube. Background technique [0002] In the typical prior art DC / AC conversion fluorescent tube drive circuit, generally referred to as inverter (inverter), most of them adopt full-bridge DC / AC conversion circuit, and cooperate with the filtering and boosting of the resonant tank. Voltage device, which can convert the input DC voltage source into high-voltage AC power to drive fluorescent tubes. In order to stabilize the light source of the fluorescent tube and not change the brightness with the change of the input voltage, most of its designs are equipped with a negative feedback control circuit to stabilize the operating current of the fluorescent tube. [0003] Since the driving voltage required before and after the fluorescent tube is lit is different, and ...

AI Technical Summary

Problems solved by technology

Moreover, the capacitor Clk has a smaller impedance at the higher frequency of the lamp lighting frequency, and more lamp current flows out through the equivalent capacitor Clk, making it more difficult to detect the lamp state.

In addition, the longer the length of the fluorescent tube, the more possible leakage current paths, all of which increase the difficulty of judging whether the tube is turned on or not.

[0007] It can be seen that the above-mentioned existing DC / AC conversion fluorescent tube drive circuit obviously still has inconvenience and defects in structure and use, and needs to be further improved urgently.

In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and the general products do not have a suitable structure to solve the above-mentioned problems. This is obviously related. The problem that the industry is eager to solve

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