Protection circuit for backlight module of liquid crystal display
A backlight module and protection command technology, applied to static indicators, light sources, electric light sources, etc., can solve problems such as failure to start the protection mechanism of the backlight module 10, damage to the fluorescent lamp group 20, etc.
Active Publication Date: 2014-04-30
AU OPTRONICS CORP
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Problems solved by technology
Therefore, the protection circuit 18 outputs a high-level comparison result signal (Vp), so that the main control circuit 12 still works normally and causes damage to the fluorescent tube group 20
[0013] To sum up, since the protection circuit 18 of the existing backlight module 10 adopts a protection command voltage (V-command) with a fixed value, in order to achieve a higher image quality, analog dimming or digital dimming is required. When the root mean square value of the lamp current (I-lamp) is lowered by dimming, the lamp voltage (V-lamp) and the feedback signal (V-fb) will also be lowered accordingly. Once the fluorescent lamp group 20 occurs When abnormal, the feedback signal (V-fb) may not be higher than the protection command voltage (V-command), at this time, the protection circuit 18 will misjudge that the plurality of fluorescent lamps 202 in the fluorescent lamp group 20 can work normally and output The comparison result signal (Vp) of a high level, and thus the protection mechanism for the backlight module 10 cannot be activated
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[0065] According to an embodiment of the present invention, the backlight module adopts a dynamic protection circuit. In the dynamic protection circuit, the adopted protection command signal (V-command) can be dynamically adjusted following the change of the analog adjustment signal (A-dim) or the digital adjustment signal (V-dim).
[0066] Please refer to image 3 , which is a schematic block diagram of a backlight module of a liquid crystal display with a dynamic protection circuit of the present invention. The backlight module 30 of the present invention includes a main control circuit 12 , a driving circuit 14 , a lamp feedback circuit 16 , a dynamic protection circuit 38 , and a fluorescent lamp group 20 .
[0067] First, the main control circuit 12 outputs the driving signal (Vd) to the driving circuit 14 according to an analog adjustment signal (A-dim) or a digital adjustment signal (V-dim). The driving signal (Vd) is mainly used to provide a driving voltage for power...
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The invention discloses a protection circuit for a backlight module of a liquid crystal display. The backlight module comprises a main control circuit, a driving circuit, a fluorescent tube group, a lamp tube feedback circuit and a dynamic protection circuit, wherein the main control circuit outputs driving signals according to analog adjusting signals or digital adjusting signals; the driving circuit outputs lamp tube voltage according to the received driving signals; the fluorescent tube group comprises a plurality of fluorescent tubes for receiving the lamp tube voltage and generating lamp tube current; the lamp tube feedback circuit generates feedback signals according to the acquired lamp tube voltage; and the dynamic protection circuit dynamically adjusts protection command signals according to the analog adjusting signals or the digital adjusting signals, so that the dynamic protection circuit compares the protection command signals with the feedback signals, and generates comparative result signals to the main control circuit.
Description
technical field [0001] The invention relates to a backlight module control circuit of a liquid crystal display, in particular to a backlight module protection circuit of a liquid crystal display. Background technique [0002] In recent years, the backlight module design of TFT-LCD Display using cold cathode fluorescent lamp (Cold Cathode Fluorescent Lamp; CCFL) as the light source has become more and more common. In order to effectively improve the picture quality and display effect, most R&D personnel set the research goal of dynamically adjusting the brightness of the light source. [0003] Furthermore, in order to meet the requirements of energy saving, high dynamic contrast (DCR) and dynamic display, the light source of the backlight module needs to be adjusted in real time to achieve higher image quality. At this time, the current of the cold cathode fluorescent lamp is under the condition of dynamic change. Due to the real-time brightness adjustment, when the cold-ca...
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IPC IPC(8): G02F1/133H05B41/36
Inventor 魏仕雯李宗勋黄匀珮郭俊良
Owner AU OPTRONICS CORP