I. composition principle of LCD
The liquid crystal
The screen looks like only one screen, in fact, it is mainly composed of four large pieces (filter, polarizer, glass, cold cathode fluorescent lamp), here to give you a brief explanation.
Filter: the reason why TFT LCD panel can produce color change is mainly from color filter. The so-called liquid crystal panel can make liquid crystal molecules stand in line through the voltage change of driving IC, so as to display the picture. The picture itself is black and white, and can be changed into color pattern through the filter.
Polarizing plate: polarizing plate can convert natural light into linear polarizing elements, whose performance is to separate the incoming linear light with polarizing components, one part is to make it pass, the other part is absorption, reflection, scattering and other effects to make it hidden, reduce the generation of bright/bad points.
Cold cathode fluorescent lamp: it is characterized by small volume, high brightness and long life.Made of specially designed and processed glass, cold cathode fluorescent lamps can be used repeatedly after rapid lighting and can withstand up to 30,000 switching operations.Because cold cathode fluorescent lamp USES three-color phosphor powder, so its luminous intensity increases, the light decline decreases, the color temperature performance is good, thus produces the heat quantity is extremely low, effectively protects our liquid crystal display the life.
Causes and prevention of bright/bad spots of liquid crystal
1. Reasons of the manufacturer:
The bright/bad spot is also known as the bright spot of LCD, which is a kind of physical damage of LCD. It is mainly caused by external force compression or slight deformation of the internal reflection plate of the bright spot.
Each pixel on the LCD screen has three primary colors, red, green and blue, which combine to produce a variety of colors.Take 15-inch LCD as an example, its LCD screen area is 304.1mm*228.1mm, resolution is 1024*768, and each LCD pixel is composed of RGB primary color unit.Liquid crystal pixels are “liquid crystal boxes” formed by pouring liquid crystal into a fixed mold. The number of such “liquid crystal boxes” on a 15-inch LCD display is 1024*768*3 = 2.35 million!What is the size of an LCD box?We can easily calculate: height = 0.297mm, width = 0.297/3 = 0.099mm!In other words, 2.35 million “liquid crystal boxes” with an area of only 0.297mm*0.099mm are arranged densely under the area of 304.1mm*228.1mm, and a drive tube that drives the liquid crystal box is integrated behind the liquid crystal box.Clearly, the production process requirements of production line is very high, at the current technology and craft, also cannot guarantee that each batch produced LCD screen is not bright/bad points, manufacturers generally avoid bright/bad points to segment LCD panel, there is no bright/bad points or very few bright spots/bad LCD panel of the high supply powerful manufacturers, and the light/bad points more LCD screen is generally low supply small manufacturers in the production of cheap LCD.
Technically, a bright/bad spot is an irreparable pixel on an LCD panel that is produced during the manufacturing process.The LCD panel is composed of fixed liquid crystal pixels, each of which has three transistors corresponding to red, green and blue filters behind a 0.099mm liquid crystal pixel
A faulty transistor or short circuit makes this pixel a bright/bad point.In addition, each LCD pixel is also integrated behind a separate driver tube to drive it.If one or more of the red, green and blue primary colors fail, the pixel cannot normally change color and will become a fixed color point, which will be clearly visible in some background colors. This is the bright/bad point of LCD.Bright/bad spot is a kind of physical damage that cannot be avoided 100% in the production and use of LCD screen. In most cases, it is produced in the manufacturing of the screen.As long as one or more of the primary colors that make up a single pixel are damaged, bright/bad spots are generated, and production and use are likely to cause damage.
According to international convention, liquid crystal display has 3 below bright/bad point is in the range that is allowed, however consumer is unlikely to be willing to buy the monitor that has bright/bad point when buying liquid crystal, so the liquid crystal manufacturer that has bright/bad point commonly sells very hard.How do panel manufacturers deal with three or more bright/bad spots due to production process?In order to gain profits, some manufacturers will not destroy these LCD screens, and in most cases, they will use a professional equipment to treat the bad/bad spots, so as to achieve the effect of no bad/bad spots on the surface to the naked eye.A few manufacturers do not even do the processing, directly put these panels into production line for production, so as to achieve the purpose of reducing costs.This kind of product does have an advantage in price, but it will produce bright/bad spots soon after use.At present on market a lot of cheap liquid crystal display are so processed out, so you do not want to buy liquid crystal display cheap, to buy some unknown brands.Glad to buy a low – cost non – bright display.Because after a while, things you don’t want to see may eventually happen.
2. Reasons for use
Some LCD bright/bad points may be caused by the use of the process, simply tell you about the usual use of some precautions:
(1) do not install multiple systems at the same time;Installation of multiple systems in the switching process will cause a certain degree of damage to the LCD.
(2) keep the voltage and power normal;
(3) do not touch the LCD button at any time.
All these three factors directly or indirectly affect the normal operation of the “liquid crystal box” molecules, which may lead to the production of bright/bad points.In fact, the bright/bad spots of consumers in the process of use can be understood through the inspection of engineers. Even the bright/bad spots of consumers can be understood if the manufacturers do not harm consumers without conscience.
The national standard is 335, meaning three bright spots, or three dark spots, qualify as normal.
Post time: Jun-29-2019