Publish Time: 2024-02-12 Origin: Site
With the continuous development of society, LCD display is widely used in industry. The human-computer interaction interface has changed from eight-segment digital tube to CRT in the past, and then to today's LCD display, which involves many industries. At present, from the industrial flat-panel liquid crystal displays we have come into contact with, the failure rate of liquid crystal displays begins to increase over time during the use process. Common failure phenomena include black screen, blurry screen, display jitter, etc. Video interface, graphic control, and inverter. Since there are many types of LCD monitors in the industry, the models and interfaces of the internal panels are also different. In addition to the cumbersome disassembly, it is often difficult to find the same panel to replace. To this end, it is necessary to make a portable, easy-to-operate, and test tool for various parts of the LCD, and can also be used for maintenance of other types of LCDs. The design idea is to start by breaking down the parts in the LCD display one by one, from simple to deep, and select the relevant parts for detection according to the fault phenomenon.
Backlight tube inspection
Inverter circuit board detection
LCD panel inspection
Power and inverter circuit board signal detection
Graphics control board detection
The backlight tube is attached to the inside of the LCD display panel. The quality of the lamp tube is difficult to measure because most of the inverter circuit boards (high-voltage boards) equipped with the equipment have the current balance protection function, that is, once a lamp tube burns out, several outputs of the inverter circuit board (high voltage board) will be fully protected, and the output will be turned off so that the fault cannot be determined. For the judgment of the lamp, a very simple method can be used, equipped with an inverter circuit board with independent output and no current balance, which can easily solve the problem of whether the lamp is good or bad, and the starting voltage and working voltage of most lamps. They are all very close, and almost all of them can meet their needs.
Under the condition that the LCD display backlight tube has been determined to be normal, step by step, it provides testing conditions for the high-voltage board. Even if the lamp tube is judged to be damaged before, the tooling is equipped with six small backlight tubes for cooperative testing. To improve the rigor of detection, it can also be combined with the original liquid crystal lamp to judge when the power problem needs to be considered. Considering the independence of detection, we use the tooling to drive the inverter circuit board (high voltage board) autonomously, that is, to provide DC+12V and enable voltage DC+5V independently.
The LVDS low-voltage differential video signal generated by the tool itself is used to directly point to the screen, and the LCD display panel displays different graphics generated inside the tool to detect whether the display panel has streaks, and jitters, glitches, and other faults. To improve compatibility, it is equipped with several commonly used LVDS interfaces, so that the LCD panels of commonly used models can be lit. In addition, a VGA interface video signal source is also provided, which is convenient for debugging and copying.
Considering the convenience of LCD display detection, the tooling can provide two small digital voltmeters in parallel to the related circuits of the display, to easily see the load condition of the power supply when the LCD is working and whether the graphic control board is normal or not, and provides an enable signal. For the inverter circuit board, it provides a reference for fault analysis, and it is also convenient for the copy machine to use.
The graphics control board involves graphics processing algorithms and level conversion. Whether it is the input R, G, B, H, and V signals or the output LVDS signal, there is currently no practical and feasible way to detect the quality of the LCD display alone. Put the graphics control module in the final inspection, and locate it by the replacement method. If the lamp tube and high-voltage board are normal during the inspection, the direct LVDS signal can light up the display panel normally, and after the tooling provides normal R, G, B, H, and V video signals, make sure the input signal is normal, you can judge its good or bad.
The above is the relevant content about the design ideas of LCD display inspection tooling. If you are interested in an LCD display, you can contact us. Our website is www.smartboardfactory.com.