Common defects and solutions in TFT-LCD production Time:2021-08-06 16:51 Browse(583)
The scope of your problem is too large. Each project can list hundreds of defects
The scope of your problem is too large. Each project can list hundreds of common defects, which can be divided into several categories according to the major categories. On the whole, there are too many, According to the defects of the finished product, it can be divided into dot defects, line defects, uniformity defects and glass defects.
TFT LCD is the abbreviation of thin film transistor liquid crystal display.

Common defects and solutions in TFT-LCD production

TFT LCD technology is a kind of technology that combines Microelectronics technology and liquid crystal display technology skillfully.
people use it to carry out microelectronics precision on Si Thin processing technology.
it is transplanted to the processing of TFT array on large area glass, and then the array substrate is combined with another substrate with color filter film to form a liquid crystal cell by using the mature LCD technology, and then through the post process such as polarizer coating, In TFT LCD,
the function of TFT is equivalent to a switch tube.
the commonly used TFT is a three terminal device.
generally, a semiconductor layer is made on a glass substrate.
there are source and drain connected with it at both ends.
and through the gate insulating film, it is opposite to the semiconductor, There is a grid.
the voltage applied to the grid is used to control the current between the source and leakage electrodes.
for the display screen,
each pixel can be regarded as a layer of liquid crystal sandwiched between the pixel electrode and the common electrode in terms of structure.
more importantly, it can be regarded as a capacitor in terms of electricity.
the structure of each pixel can be simplifiedTo charge the pixel P (I.
J) in row J and column I, the switch t (I, J) should be turned on and the target voltage should be applied to the signal line D (I).
when the pixel electrode is fully charged.
even if the switch is off, the charge in the capacitor will be preserved, The data (column) driver is used to apply the target voltage to the signal line.
while the gate (row) driver is used to turn on and off the switch.
because the display voltage applied to the liquid crystal layer can be stored in the storage capacitance of each pixel.
the liquid crystal layer can work stably.
this display voltage can also be transmitted through the TFT It can be rewritten in a short time.
therefore, even for high-definition LCDs,
the key to display image is the orientation of liquid crystal molecules under the action of electric field.
generally, different display modes can be realized through the orientation treatment on the inner side of the substrate.
a certain display mode can be selected.
under the action of electric field, the orientation of liquid crystal molecules changes, In a word, the simple matrix of TFT LCD is different from that of passive TN LCD and STN LCD. It has a thin film transistor (TFT) on each pixel of LCD, which can effectively overcome the crosstalk when it is not gated, The static characteristic of LCD is independent of the number of scan lines, so the image quality is greatly improved.
while the characteristic of switching unit (TFT).
the static characteristic of LCD is independent of the number of scan linesWhat about TFT LCD.
TFT (thin film transistor) LCD is thin film field effect transistor LCD.
liquid crystal flat panel display.
Special TFT LCD is the only display device that can catch up with and surpass CRT in brightness, contrast, power consumption, life, volume and weight, It has excellent performance, large-scale production characteristics, high degree of automation, low cost of raw materials, and broad development space. It will quickly become the mainstream product in the new century and a bright spot of global economic growth in the 21st century.
different from TN Technology, TFT displays adopt "back transparent" illumination mode - the imaginary light source path is not from top to bottom like TN liquid crystal, But from the bottom to the top.
in this way, a special light tube is set on the back of the liquid crystal.
when the light source is illuminated, it is transmitted upward through the lower polarizing plate.
because the electrodes of the upper and lower interlayer are changed into FET electrode and common electrode.
when the FET electrode is turned on, the performance of liquid crystal molecules will also be changed, and the display purpose can be achieved by shading and transmitting light, The response time is greatly improved to about 80ms.
because of its higher contrast and richer color than TN LCD.
the screen update frequency is also faster, so TFT is commonly known as "true color.
compared with DSTN.
the main feature of TFT LCD is that each pixel is equipped with a semiconducting switch device.
because each pixel can be directly controlled by a point pulse.
Therefore, each node is relatively independent.
and can be continuously controlled.
this design method not only improves the response speed of the display screen.
at the same time, it can accurately control the gray level of the display screen, This is the reason why TFT color is more realistic than DSTN.
the main advantages of TFT LCD.
with the maturity of TFT technology in the early 1990s.
color liquid crystal flat panel displays have developed rapidly. In less than 10 years, TFT LCD has rapidly grown into the mainstream display, This is inseparable from its advantages.
the main features are:
(1) good use characteristics: low voltage applications.
low driving voltage, solid use, improved safety and reliability; Flat, light and thin, saving a lot of raw materials and use space.
low power consumption.
its power consumption is about one tenth of CRT display, reflective TFT LCD is only about one percent of CRT, saving a lot of energy.
TFT LCD products also have a series of specifications, models and sizes.
various, convenient and flexible to use, easy to maintain, update and upgrade, Long service life and many other features.
the display range covers the application range of all displays from 1 inch to 40 inch and large projection plane.
it is a full-scale display terminal.
the display quality ranges from the simplest monochrome character graphics to high resolution.
high color fidelity, high brightness, high contrast, Various types of video displays with high response speed.
the display modes include direct view type.
projection type, perspective type, and reflection type.
(2) good environmental protection characteristics: no radiation and no flicker.
the display mode is direct view typeIt is not harmful to the health of users.
especially the appearance of TFT LCD electronic books and periodicals.
it will bring mankind into the era of paperless office and paperless printing, and lead to the revolution of human learning, communication and cultivation civilization.
(3) it has a wide range of applications.
it can be used normally from - 20 ℃ to + 50 ℃, The low temperature working temperature of TFT LCD after temperature hardening treatment can reach minus 80 ℃.
it can be used as mobile terminal display.
it can also be used as desktop terminal display and large screen projection TV, It is a full-scale video display terminal with excellent performance.
(4) high degree of automation of manufacturing technology.
good characteristics of large-scale industrial production.
the technology of TFT LCD industry is mature.
the yield of large-scale production reaches more than 90%.
(5) TFT LCD is easy to integrate and update.
it is a perfect combination of large-scale semiconductor integrated circuit technology and light source technology, At present, there are amorphous, polycrystalline and monocrystalline silicon TFT LCDs.
in the future, there will be TFTs made of other materials, including glass substrate and plastic substrate.
in the future, there will be TFTs made of glass substrate and plastic substrate
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