Discharge lamp circuit protection and regulation apparatus

A circuit protection and adjustment device technology, applied in lighting devices, electric light sources, electrical components, etc., can solve the problems of unstable CCFL inverters and inability to adapt automatically, avoid unstable work and sudden changes in current, and achieve automatic adaptation. And the effect of adjusting and simplifying the circuit structure

Inactive Publication Date: 2014-03-19
HANGZHOU MPS SEMICON TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] Among them, the method of realizing frequency hopping through the controller is relatively simple, but this method cannot automatically adapt to the load.
Even under some load conditions, this approach may lead to CCFL inverter instability

Method used

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  • Discharge lamp circuit protection and regulation apparatus
  • Discharge lamp circuit protection and regulation apparatus
  • Discharge lamp circuit protection and regulation apparatus

Examples

Experimental program
Comparison scheme
Effect test

no. 1 Embodiment

[0049] figure 2 Shown is a lamp voltage LV signal detection circuit according to a first embodiment of the present invention. Taking the application of 4 lamps in phase as an example, the principle of the first specific embodiment will be described in detail. Step S1: Extracting electrical signals in one or more discharge lamp circuits, wherein the electrical signals are voltage sampling signals, LV1, LV2, LV3 and LV4 are sampled lamp voltages, and the four lamp voltages are in phase. Connect the detection branch at the point where the lamp voltage is sampled.

[0050] Step S2: Synthesize the electrical signals into a voltage detection signal representing the working state of the discharge lamp through a logic circuit, and each detection branch includes a voltage detection signal connected to the DC bias voltage V bias and the bias resistor R between the lamp voltage sampling point s , the lamp voltage sampling signals LV1 / LV2 / LV3 / LV4 are respectively connected to the lamp...

no. 2 Embodiment

[0064] The second specific embodiment is an extension of the first specific embodiment, and the step S2 is divided into steps S21 and S22. Steps S21 and S22 will be described in detail below.

[0065] Step S21: Divide the discharge lamps into at least one group of discharge lamp groups with the same voltage or current phase; divide the discharge lamps into two groups, wherein the voltage phases of the first group and the second group of discharge lamps are opposite, and one is coupled to A first detection circuit of the discharge lamps of the first group obtains a first electrical signal and a second electrical signal is obtained from a second detection circuit coupled to the discharge lamps of the second group, when said first or second electrical signal is short-circuited state, the short-circuit protection is activated. The electrical signal may be a current signal or a voltage signal. Figure 6 It is the out-of-phase application of 4 lamps according to the second embodim...

no. 3 Embodiment

[0072] Figure 7 It is a schematic diagram of a LI signal detection OR gate circuit for 4 lamps in phase according to the third embodiment of the present invention. Its working principle is the same as that of the first embodiment, but the lamp current is used instead of the lamp voltage. The point of sampling the lamp current is connected to one end of the lamp tube, and through the sampling resistor R s grounded. Connect the detection branch at the point where the lamp current is sampled. Each detection branch is connected with a diode, and the four diodes in the figure form an OR gate. Comparing the LI signal instead of the LV signal in Figure 5 with a threshold value can realize the open circuit protection of the lamp, and its principle is consistent with that of using the LV signal to realize protection.

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Abstract

A CCFL inverter circuit integrates a feedback circuit and protection circuit together. For both in-phase and out-of-phase applications, sensed lamp voltages can be used for open lamp and short lamp detection and sensed currents can be used for open lamp detection. The driving circuit adjusts the open lamp frequency by using a duty cycle control signal so that the driving circuit can always achieve the desired lamp voltage gain.

Description

technical field [0001] The invention relates to a protection regulating device and a frequency regulating device for a discharge lamp, in particular to a protection regulating device and a frequency regulating device for a cold cathode fluorescent lamp (CCFL). Background technique [0002] In the application of cold cathode fluorescent lamp CCFL (Cold Cathode Fluorescent Lamp) inverter, the regulation of lamp current in normal operation and the regulation of lamp voltage in open circuit state are essential. In addition, short-circuit protection and open-circuit voltage protection are equally important in practical applications. [0003] Typically, open circuit protection and lamp current feedback require sampling of the winding current (or lamp current). Likewise, short circuit protection and lamp voltage feedback require sampling of the lamp voltage (or winding voltage). [0004] Usually, feedback circuits and protection circuits cannot be directly linked because they hav...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B41/298H05B41/36
CPCH05B41/2855
Inventor 杨先庆姚凯卫陈伟张军明任远程
Owner HANGZHOU MPS SEMICON TECH
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