A method for detecting the crystal leakage of liquid crystal display screen by low temperature freezing includes the following steps:
- 1) evenly place the liquid crystal display screen in the tray;
- 2) put the tray code into the industrial freezer;
- 3) set the temperature of the industrial freezer to – 35 ℃, freeze for 4 hours, and start freezing;
- 4) take out the tray and place it horizontally after freezing On the test bench;
- 5) evenly select 9 positions on the screen surface, use a rubber hammer to gently drop at a height of 10cm from the LCD screen, and knock each LCD screen;
- 6) observe whether there is crystal leakage on the LCD screen. The phenomenon of crystal leakage can be divided into two kinds, one is the appearance of black spots or patterns, the other is the appearance of white spots or patterns.
The tools needed for the low temperature freezing method to detect the crystal leakage of LCD include LCD freezer, fluorescent lamp, rubber hammer, finger sleeve, PVC glove, dust-free cloth, alcohol, bracket and label paper. The operators shall wear finger cots and PVC gloves in turn, clean finger cots and PVC gloves with dust-free cloth dipped in alcohol, and then evenly place the LCD screen used for the experiment in the tray, put the tray into the LCD freezer, set the temperature of the freezer to – 35 ℃, set the freezing time to 4 hours, start to freeze, and take out the tray as a whole after freezing, and place it at room temperature Unfreeze: there will be a layer of white frost on the surface of LCD screen at this time. The unfreezing time is 20 minutes. After 20 minutes, put the LCD screen in the same tray into the freezer. Set the temperature of the freezer to – 35 ℃, and the freezing time to 16 hours. After taking it out, place it in the room temperature environment for 20 minutes. Then carry out the test, lift the rubber hammer, and evenly select 9 positions on the screen surface , drop down slightly at a height of 10cm from the LCD screen, and after knocking, it can be observed whether there is crystal leakage on the test screen under the condition of sunlight reflection. The phenomenon of crystal leakage can be divided into two types. If the LCD is positive, there will be black spots or patterns; if the LCD is negative, there will be white spots or patterns.
As a kind of optimization, the temperature required for low-temperature freezing is between – 35 ± 10 ℃, so as to achieve the purpose of detecting whether there is crystal leakage on the LCD screen.
Matters needing attention:
1. The freezing time is between 4 hours and 16 hours, which can make all the liquid crystal displays used for the test achieve the purpose of thorough freezing.
2. The location of percussion points are: one at each corner of the screen surface, one at the center of the screen surface, two at both ends of the horizontal center line and two at both ends of the vertical center line. The key percussion part is the percussion point closest to the crystal pouring opening.
3. This method can simplify the testing equipment of LCD, and simplify the testing process of LCD. More importantly, it can save the production cost of the enterprise.
This method needs a short time, simplifies the detection method and improves the efficiency.
As a kind of optimization, the operation is simple and easy to learn, and the LCD screen will not be damaged, suffer from low temperature, and the performance will not decline after humid environment.