How to check whether the LCD has bad spots and bright spots! thank you!
Author:Ding Muxin Time:2021-10-12 15:44 Browse(439)
According to the data, the common "spot defects" of LCD can be divided into three types: bad spot, bright spot and dark spot.
According to the data, the common "point defects" of LCD can be divided into three types: bad point, bright point and dark point.

● bad point

How to check whether the LCD has bad spots and bright spots! thank you!


is a pure black point in the case of white screen or a pure white point in the case of black screen.
when switching to red, green and blue display mode, this point is always in the same position and is always a pure black or white point.
this situation indicates that the R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R, R G. B three sub-pixel points are damaged.
such points are called bad points.

● bright spots

in the case of black screen, R, G, B (red, green There are two kinds of bright spots:


① in the case of a black screen, the red dots on the black screen are simply R or g or B.


② in the case of switching to the red, green and blue display mode.
only in the case of R or g or B, there are white dots, At the same time, in the other two modes, there are other color dots, in which there are two bright spots in the same pixel.

● dark dots

in the case of white screen, the color dots that are not pure R, G, B are called dark dots.


the appearance of dark dots can be divided into two cases:

① when switching to red, green, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red, red In the blue three color display mode.
in the same position, there is only one dark spot in the same display mode R or g or B.


② in the red, green and blue three color display mode.
in the same position, there are black spots in both display modes R or g or B,This situation indicates that there are two dark spots in this pixel.


measurement standard

ISO (international standards organization.
International Organization for Standardization) formulated a standard on LCD panel bad spots in 2001, which defines four levels of quality.
class 1 does not allow bad spots.
is the highest level, and the worst level is class 4, 10N bad points are allowed.
in general,
class 2 is used, which allows three bad points. However, if only two bad points appear within the range of 5 * 5 pixels, it is also not allowed, so dealers can be asked to exchange goods.


in addition,
due to different standards of defining the level of bad points around the world, Due to the lack of LCD technology and manufacturing process and limited by the cost, many manufacturers in the LCD display industry default that a display with less than 3-6 bad points is a qualified product, and only some products that only use a + panel will make the promise of zero bright spot or zero bad point.
in addition,
with the continuous improvement of technology, Some brands of LCD panels have no bright spot rate of 90%.


in addition,
although LCD display has less than 3 bright / bad points is within the allowed range, more and more consumers are not willing to buy a display with n bright / bad points when buying LCD, so it is difficult for LCD manufacturers with bright / bad points to sell it at present, in order to obtain benefits, Some manufacturers will not scrap these LCD screens. In most cases, they use a professional device to deal with the bright / bad spots on these panels, so as to make them more acceptable dark spots,We should pay attention to this point when choosing LCD.


moreover, different countries or regions or brands have different definitions of the number of bad points for products with the same grade A.
this also needs to be understood when purchasing.
for example, Japanese standard takes less than 3 bad points as grade a qualification, Korean standard takes less than 5 bad points as grade a qualification However, the Taiwan standard takes 8 bad points or less as A-level qualification.
of course.
these standards change with the continuous improvement of production process.


III Common "point defect" detection methods and software

the number of "point defects" is one of the standards to measure the quality of LCD.
it is essential to see how many "point defects" there are before purchasing the LCD.
especially for some manufacturers who promise that the bright spots of products with no bad points are all turned into dark ones with instruments.
it is more important to prevent them.


1 Check

when businesses display LCD, they often show you all kinds of gorgeous pictures.
it not only looks good, but also makes you unable to see the missing spots on the LCD.


when selecting LCD, they should pay attention to the bad points, bright spots, bright spots, bright spots, bright spots, bright spots and so on The most common method is to right-click the mouse on the desktop.
select "properties", select "appearance" in the open window, then select "black" or "white" in the "color" column, and then click "application"


in the desktop all black or all white, or red, green, black, white, or black, or white, or red, green Under the blue background, carefully observe whether there are heterochromatic spots or bright spots on the LCD screen.
if there are, there are some defects in the LCD screen.
if there are any, there are some defects in the LCD screenIt's better to ask for another product that has no such defect or spot defect on the four sides of the screen before payment.


2. Common software detection

of course.
when detecting the spot defect of LCD, take a floppy disk or U disk or a CD-ROM with several common display detection software, The common software includes Nokia monitor test, displayx, monitors matter checkscreen, etc.
each one has this function.


● Nokia monitor test

among them, Nokia monitor test is a simple and practical display test software.
it can easily help you find out the problems existing in the LCD screen, After starting the software, the first row of options from left to right are geometric distortion test, brightness contrast test, breath phenomenon test and color test, and the second row of options from left to right are convergence test, focus test and color test Resolution test, water ripple test, text display test and Jitter Test, etc.


among the multiple options of the software,
the "colors" item is useful for detecting the bad points of the display screen. In this option, five colors of white, red, green, blue and black can be output in the full screen state, It is convenient to check whether there are bad points on the display screen.

● displayx

displayx is a 48KB display softwareNo need to install, unzip and run the main program.
click "general complete test" to complete all tests.
including interlacing, solid color, color, convergence, geometry, breathing effect, 256 gray, gray, contrast and other test items, right-click or press ESC key to exit.
to do the bad point test.
just select "solid color" mode under the "general single test" menu, Click the mouse to enter different solid colors, such as all black, all red, all green, all white and all blue. You can easily find the bad spots on the LCD screen Passmark monitor test is a performance test software specially used to test the performance of your computer screen.
it provides 25 different test items.
you can test your computer screen according to different screen resolution settings and adjustments, Of course, it also includes testable LCD flat panel screens. It includes a number of tests, which can well detect the color, response time, text display effect and bad points of LCD, In order to know whether your computer screen is normal and display effect.
you can try this software.

● monitors matter checkscreen

monitors matter checkscreen is a convenient LCD test software besides CRT monitor.
it includes many tests, It can well detect the color, response time and text display effect of LCD,


select "LCD display"
to detect color, response time, text display effect, bad points and other parameters. There are five test items. You can directly click to start the test, and press the right mouse button or ESC key to return to the main interface.
among them,
color option (color, color, color, etc.) can be selected, Three primary colors and 16.7 million kinds of color scale images are used to investigate the color expressiveness, color uniformity, color scale expressiveness, brightness and contrast, cross talk (sharpness detection, and the sharpness and crosstalk of LCD color edge are detected by the black-and-white interlaced image with strong contrast), smoothing (response time detection), pixel check (pixel detection, and so on), Pocket LCD can be used to detect PDA devices.
pocket LCD is a tool software used to detect whether there are bad spots on the LCD of Pocket PC. It can let users judge whether there are bad spots on their LCD by displaying different full screen colors.
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pocket LCD is a tool software used to detect whether there are bad spots on the LCD of Pocket PC
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