Although LCD panels have long ceased to be a dream, even when using the most modern technologies, defects are found that can greatly spoil the mood from a perfect purchase. In order to fully satisfy the purchased goods, you need to check the TV for broken pixels when buying.
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Pixel what it is
Today, liquid crystal displays are not something unusual and extraordinary. On the contrary, in addition to TVs, they are present in many devices: computer monitors, telephones, cameras, navigators and other similar equipment. The basis of LCD or LCD technology are liquid crystals. After passing through a layer of light crystals from lamps or LEDs, the corresponding picture appears on the screen.
The matrix of a color TV is a huge number of tiny indivisible rectangular or round cells, called pixels. In turn, each such object consists of red, green and blue subpixels. It is these colors, more precisely, their combinations, that are considered the basis of color television. The simultaneous glow of all the pixels forms a complete image on the screen. Moreover, the more pixels, the clearer the picture will be. If you look closely at the display, you can easily see the three colored areas of these objects.
The concept of dead pixels, the reasons for their appearance
The number of pixels on the display is so huge that it is almost impossible to guarantee their absolute serviceability. Often on the screen you can observe luminous in one color, completely fixed points, which even with a change in the image of the TV do not change the color and location. It is these objects that are commonly called broken pixels. They can be black, white and color. There are two reasons for these defects: the imperfection of technology and ordinary manufacturing defects.
After the failure of the transistor controlling the liquid crystals, black ("dead") dots appear, indicating non-functioning cells. Subsequent control of these crystals is simply not possible. Such defects are most visible on a light background. Some experts consider their “treatment” impossible, while others argue that using a laser it is actually possible to partially return the pixel to its working state.
The second reason is the subpixel frozen in one position. This problem appears in a layer of liquid crystals. Such a “stuck” object appears on the display in the form of a white (burning) or colored dot. To eliminate this defect, you can use special programs or conduct a series of physical manipulations. There are times when broken pixels, after some time, disappear on their own.
Thus, choosing a LCD TV, it is not enough to pay attention to its appearance, the presence of numerous functions, ports, connectors. An important place is also taken by checking the device for matrix defects. Let's try to figure out how to check the TV before buying, and protect yourself from the acquisition of low-quality equipment.
Permissible number of dead pixels
Often in stores you can observe a picture when a buyer tries to return a newly acquired TV by detecting defects on the screen, in particular, dead pixels. For the sake of truth, we note that usually the dispute between the store and the buyer does not end in favor of the latter. In order not to get into an unpleasant situation, we recommend that you approach the choice of a TV very responsibly.In particular, it is worth knowing how to check the LCD TV at a point of sale when buying for broken pixels, to get acquainted with certain standards according to which displays are divided into four classes.
| Class | Constantly burning (white) pixels | Permanently non-burning (black) dots | Defective subpixels (color) |
| per million pixels | |||
| I | |||
| II | 2 | 2 | 5 |
| III | 5 | 15 | 50 |
| IV | 50 | 150 | 500 |
How to check the TV in the distribution network
The information in the table indicates that the products of the first class are completely devoid of dead pixels. The cost of goods depends on their class.
A picture is formed on the screen by all the pixels of the display. For example, the resolution Full HD (1920 x 1080) involves the use of more than two million pixels. Knowing the permissible norms of dead pixels, methods of checking for the presence of such defects, it is not difficult to choose high-quality equipment.
Testing devices can also be carried out using special programs by connecting the TV to a computer or laptop. Often, the buyer does not have a computer at hand, so such manipulations in the store is extremely difficult. Now many stores offer a paid service for checking screens for defects. What to do in this case, is it worth it to agree or still try to cope with this work on your own?
The easiest way is to visually inspect the screen at close range for the presence of a dot that glows in a different color. Ordinary magnifying glass will become a reliable assistant in this test. Detection of black dots, possibly when applying a white field to the screen. To find the white dots, just make the screen dark. Finding defective color subpixels can be facilitated by alternately changing the screen color.
It is important to remember that some defects do not appear immediately, but only after heating the matrix. Pictures in the form of colored stripes, grids, and fill in the form of a checkerboard will also help to quickly find subpixels that work incorrectly and stand out against the general background.
If you plan to purchase new equipment, first of all, study the relevant information, in particular, how to check the TV when buying in a store. For testing, you need to select special images and videos. They contain special pictures of various colors, which appear alternately on the screen. Then write down this information on a USB flash drive, and then go behind the TV. Videos are usually accompanied by music, which will simultaneously check the quality of acoustics.
Many today prefer new-generation devices with Ultra HD resolution (3840 x 2160). They are characterized by excellent color saturation, the ideal transition from one shade to another, the ability to adapt any format in 4K, excellent sound, many additional functions. To check the 4K TV when buying, you need to use pictures with the appropriate resolution.
Is it possible to "cure" broken pixels
Often, defects on the display occur during operation. Black points, as indicated earlier, cannot be deleted on their own. As for color pixels, there are two ways to get rid of them: physical treatment and hardware massage.
The first method involves the use of a conventional cotton swab to massage the damaged area in which the "stuck" pixel is located. Such manipulations are carried out in circular motions with the device turned off. This method cannot be called completely safe, because inaccurate movement will not only not save, on the contrary, it can add trouble.
The second method is to use special programs that are easy to find on the Internet. BadCrystal - does not always cope with the task, however, it is worth a try. Practice shows that it removes hovering points within a few minutes or a couple of days. No less popular today is the program JScreenFix. She not only finds a defect, but also eliminates it. Operating time from 20 minutes to 10 hours.
Thus, armed with the necessary test kit, you can safely go to the store for a new TV. Haste when checking the device is unacceptable. Testing should be done slowly, examining step by step each section of the screen.
