The TFT-LCD liquid crystal display is a thin film transistor type liquid crystal display, also known as "true color" (TFT). TFT liquid crystal has a semiconductor switch for each pixel, and each pixel can be directly controlled by dot pulses, so each node is relatively independent and can be continuously controlled, which not only improves the response speed of the display screen, but also can be accurately controlled Display color gradation, so the color of TFT liquid crystal is more real. TFT liquid crystal display screens are characterized by good brightness, high contrast, strong layering, and bright colors, but they also have the disadvantages of relatively power consumption and high cost.
TFT (Thin Film Transistor) is a thin film field effect transistor, which is a type of active matrix liquid crystal display. It can "actively" control each individual pixel on the screen, which can greatly improve the response time. Generally, the response time of TFT is relatively fast, about 80 milliseconds, and the viewing angle is large, generally reaching about 130 degrees.
Метод за преобразуване на полярността на TFT LCD екрана:
The driving voltage of the liquid crystal molecules cannot be fixed at a certain value, otherwise, over time, the liquid crystal molecules will undergo polarization and gradually lose their optical rotation characteristics. Therefore, in order to avoid the destruction of the characteristics of the liquid crystal molecules, the driving voltage of the liquid crystal molecules must be polarized. This requires the display voltage in the liquid crystal display to be divided into two polarities, one is positive polarity and the other is negative polarity. . When the voltage of the display electrode is higher than the voltage of the common electrode, it is called positive polarity; when the voltage of the display electrode is lower than the voltage of the common electrode, it is called negative polarity. Regardless of the positive polarity or the negative polarity, there will be a set of gray scales with the same brightness, so when the absolute value of the pressure difference between the upper and lower glass layers is fixed, the gray scales displayed are exactly the same. However, in these two cases, the turning of the liquid crystal molecules is completely opposite, which can avoid the above-mentioned characteristic damage caused when the turning of the liquid crystal molecules is always fixed in one direction. There are four common polarity conversion methods, namely frame-by-frame phase inversion, line-by-line phase inversion, column-by-column phase inversion, and point-by-point phase inversion.
For the frame-by-frame phase inversion mode, in the same frame, all adjacent points in the entire screen have the same polarity, while the adjacent frame polarities are different; for the line-by-line phase inversion mode, the same polarity is on the same line. Polarity, and the adjacent rows have different polarities; for the column-by-column phase inversion mode, the same polarity is on the same column, while the adjacent columns have different polarities; for the point-by-point phase inversion mode, each point The polarities of the four points up, down, left, and right adjacent to oneself are all different.
At present, the common LCD screens of personal computers, most of the panel polarity conversion methods used are point-by-point conversion methods. Why? The reason is that the display quality of point-by-point phase inversion is much better than other conversion methods. The table lists the performance comparison of the four polarity conversion modes: frame-by-frame phase inversion, line-by-line phase inversion, column-by-column phase inversion, and point-by-point phase inversion.
Така-нареченият феномен на трептене е, че екранът ще се усеща трептене, но това не е преднамерен визуален ефект, а защото сивата скала на показания екран ще се променя леко всеки път, когато екранът се актуализира, карайки хората да чувстват, че екранът мига. . Тази ситуация е най-вероятно да възникне при използване на метода за преобразуване на полярността на фазово обръщане на кадър-по{2}}кадър. Тъй като цялата картина на кадър-по-инверсия е с еднакъв полярност, когато картината е положителна този път, следващия път ще бъде отрицателна. Ако има малка грешка в общото напрежение, тогава положителната и отрицателната полярност ще бъдат една и съща сива скала. Ще има разлика в напрежението и, разбира се, сивата скала се усеща различно, както е показано на Фигура 2. В случай на постоянно превключване на екраните, феноменът на трептене ще се появи поради редуването на положителни и отрицателни екрани. Методът за преобразуване на полярността на други панели, въпреки че ще има този феномен на трептене, но тъй като за разлика от фазовата инверсия кадър{6}}по-кадър, полярността на целия екран се променя едновременно. Има само един ред или една колона и дори една точка променя полярността. Що се отнася до човешкото око, това няма да е очевидно.
The so-called Crosstalk phenomenon refers to that between adjacent points, the data to be displayed will affect the other party, so that the displayed screen will be incorrect. Although there are many causes of the Ctosstalk phenomenon, as long as the polarities of adjacent points are different, the occurrence of this phenomenon can be reduced.
Принципът на работа на TFT дисплея с течни кристали:
How TFT works TFT is the abbreviation of "Thin Film Transistor", generally refers to thin film liquid crystal displays, but actually refers to thin film transistors (matrix)-can "actively" on the screen of each independent pixel Control, this is the origin of the so-called active matrix TFT (active matrix TFT). So how exactly is the image produced? The basic principle is very simple: the display screen is composed of many pixels that can emit light of any color, and the goal can be achieved by controlling each pixel to display the corresponding color. In TFTLCD, backlight technology is generally used. In order to accurately control the color and brightness of each pixel, it is necessary to install a shutter-like switch after each pixel. When the "blinds" are opened, light can pass through, and the "blinds" "When it is closed, the light cannot pass through. Of course, technically, it is not as simple as the one just mentioned.
LCD (Liquid Crystal Display) uses the characteristics of liquid crystals (liquid when heated, and crystallized into solid when cooled). Generally, liquid crystals have three forms:
Smectic liquid crystal similar to clay
Nematic liquid crystal resembling a fine matchstick
Cholestic liquid crystal
The liquid crystal display uses filaments, and when the external environment changes, its molecular structure will also change, and thus have different physical properties-it can achieve the purpose of letting light through or blocking light-which is just like the blinds just now.
Everyone knows the three primary colors, so each pixel on the display screen needs three similar basic components described above to control the three colors of red, green, and blue respectively.
The most commonly used one is twisted nematic TFT LCD (Twisted Nematic TFT LCD). The following figure explains the working principle of this type of TFT LCD. The existing technologies vary greatly, and we will cover them in detail in the second part of this article.
На горния и долния слой има жлебове. Жлебовете на горния слой са разположени надлъжно, а жлебовете на долния слой са разположени хоризонтално. Долният слой е разположен хоризонтално. Когато не се прилага напрежение, течният кристал е в естествено състояние и светлината, излъчвана от диаграмата на принципа на работа на усукания нематичен TFT дисплей на фигура 2а след преминаване през междинния слой, ще бъде усукана на 90 градуса, така че да може да премине през долния слой плавно.
When a voltage is applied between the two layers, an electric field is generated. At this time, the liquid crystals are aligned vertically, so the light will not be twisted-the result is that the light cannot pass through the lower layer.
TF:
Color filters are divided into three types: red, green and blue according to their colors. They are arranged on the glass substrate to form a group (dot pitch) corresponding to a pixel. Each monochromatic filter is called a sub{{0}}pixel (sub-pixel). ). In other words, if a TFT display supports a maximum resolution of 12801024, then at least 128031024 sub-pixels and transistors are required. For a 15-inch TFT display (1024768), then a pixel is about 0.0188 inches (equivalent to 0.30mm), for an 18.1-inch TFT display (12801024), it is 0.011 inches (equivalent to 0.28mm) As we all know, pixels are decisive for the display, and the smaller each pixel is, the larger the maximum resolution that the display can achieve. However, due to the limitation of the physical characteristics of transistors, the current size of each pixel of TFT is basically 0.0117 inches (0.297mm), so for a 15-inch display, the maximum resolution is only 12801024.
Метод за преобразуване на полярността на TFT LCD екрана:
The driving voltage of the liquid crystal molecules cannot be fixed at a certain value, otherwise, over time, the liquid crystal molecules will undergo polarization and gradually lose their optical rotation characteristics. Therefore, in order to avoid the destruction of the characteristics of the liquid crystal molecules, the driving voltage of the liquid crystal molecules must be polarized. This requires the display voltage in the liquid crystal display to be divided into two polarities, one is positive polarity and the other is negative polarity. . When the voltage of the display electrode is higher than the voltage of the common electrode, it is called positive polarity; when the voltage of the display electrode is lower than the voltage of the common electrode, it is called negative polarity. Regardless of the positive polarity or the negative polarity, there will be a set of gray scales with the same brightness, so when the absolute value of the pressure difference between the upper and lower glass layers is fixed, the gray scales displayed are exactly the same. However, in these two cases, the turning of the liquid crystal molecules is completely opposite, which can avoid the above-mentioned characteristic damage caused when the turning of the liquid crystal molecules is always fixed in one direction. There are four common polarity conversion methods, namely frame-by-frame phase inversion, line-by-line phase inversion, column-by-column phase inversion, and point-by-point phase inversion.
For the frame-by-frame phase inversion mode, in the same frame, all adjacent points in the entire screen have the same polarity, while the adjacent frame polarities are different; for the line-by-line phase inversion mode, the same polarity is on the same line. Polarity, and the adjacent rows have different polarities; for the column-by-column phase inversion mode, the same polarity is on the same column, while the adjacent columns have different polarities; for the point-by-point phase inversion mode, each point The polarities of the four points up, down, left, and right adjacent to oneself are all different.
At present, the common LCD screens of personal computers, most of the panel polarity conversion methods used are point-by-point conversion methods. Why? The reason is that the display quality of point-by-point phase inversion is much better than other conversion methods. The table lists the performance comparison of the four polarity conversion modes: frame-by-frame phase inversion, line-by-line phase inversion, column-by-column phase inversion, and point-by-point phase inversion.
Така-нареченият феномен на трептене е, че екранът ще се усеща трептене, но това не е преднамерен визуален ефект, а защото сивата скала на показания екран ще се променя леко всеки път, когато екранът се актуализира, карайки хората да чувстват, че екранът мига. . Тази ситуация е най-вероятно да възникне при използване на метода за преобразуване на полярността на фазово обръщане на кадър-по{2}}кадър. Тъй като цялата картина на кадър-по-инверсия е с еднакъв полярност, когато картината е положителна този път, следващия път ще бъде отрицателна. Ако има малка грешка в общото напрежение, тогава положителната и отрицателната полярност ще бъдат една и съща сива скала. Ще има разлика в напрежението и, разбира се, сивата скала се усеща различно, както е показано на Фигура 2. В случай на постоянно превключване на екраните, феноменът на трептене ще се появи поради редуването на положителни и отрицателни екрани. Методът за преобразуване на полярността на други панели, въпреки че ще има този феномен на трептене, но тъй като за разлика от фазовата инверсия кадър{6}}по-кадър, полярността на целия екран се променя едновременно. Има само един ред или една колона и дори една точка променя полярността. Що се отнася до човешкото око, това няма да е очевидно.
The so-called Crosstalk phenomenon refers to that between adjacent points, the data to be displayed will affect the other party, so that the displayed screen will be incorrect. Although there are many causes of the Ctosstalk phenomenon, as long as the polarities of adjacent points are different, the occurrence of this phenomenon can be reduced.
Принципът на работа на TFT дисплея с течни кристали:
How TFT works TFT is the abbreviation of "Thin Film Transistor", generally refers to thin film liquid crystal displays, but actually refers to thin film transistors (matrix)-can "actively" on the screen of each independent pixel Control, this is the origin of the so-called active matrix TFT (active matrix TFT). So how exactly is the image produced? The basic principle is very simple: the display screen is composed of many pixels that can emit light of any color, and the goal can be achieved by controlling each pixel to display the corresponding color. In TFTLCD, backlight technology is generally used. In order to accurately control the color and brightness of each pixel, it is necessary to install a shutter-like switch after each pixel. When the "blinds" are opened, light can pass through, and the "blinds" "When it is closed, the light cannot pass through. Of course, technically, it is not as simple as the one just mentioned.
LCD (Liquid Crystal Display) uses the characteristics of liquid crystals (liquid when heated, and crystallized into solid when cooled). Generally, liquid crystals have three forms:
Cholestic liquid crystal
Nematic liquid crystal resembling a fine matchstick
Smectic liquid crystal similar to clay
The liquid crystal display uses filaments, and when the external environment changes, its molecular structure will also change, and thus have different physical properties-it can achieve the purpose of letting light through or blocking light-which is just like the blinds just now.
Everyone knows the three primary colors, so each pixel on the display screen needs three similar basic components described above to control the three colors of red, green, and blue respectively.
The most commonly used one is twisted nematic TFT LCD (Twisted Nematic TFT LCD). The following figure explains the working principle of this type of TFT LCD. The existing technologies vary greatly, and we will cover them in detail in the second part of this article.
На горния и долния слой има жлебове. Жлебовете на горния слой са разположени надлъжно, а жлебовете на долния слой са разположени хоризонтално. Долният слой е разположен хоризонтално. Когато не се прилага напрежение, течният кристал е в естествено състояние и светлината, излъчвана от диаграмата на принципа на работа на усукания нематичен TFT дисплей на фигура 2а след преминаване през междинния слой, ще бъде усукана на 90 градуса, така че да може да премине през долния слой плавно.
When a voltage is applied between the two layers, an electric field is generated. At this time, the liquid crystals are aligned vertically, so the light will not be twisted-the result is that the light cannot pass through the lower layer.
TF:
Color filters are divided into three types: red, green and blue according to their colors. They are arranged on the glass substrate to form a group (dot pitch) corresponding to a pixel. Each monochromatic filter is called a sub{{0}}pixel (sub-pixel). ). In other words, if a TFT display supports a maximum resolution of 12801024, then at least 128031024 sub-pixels and transistors are required. For a 15-inch TFT display (1024768), then a pixel is about 0.0188 inches (equivalent to 0.30mm), for an 18.1-inch TFT display (12801024), it is 0.011 inches (equivalent to 0.28mm) As we all know, pixels are decisive for the display. The smaller each pixel is, the maximum resolution that the display can achieve will be
По-голям. Въпреки това, поради ограничението на физическите характеристики на транзисторите, текущият размер на всеки пиксел от TFT е основно {{0}}.0117 инча (0,297 mm), така че за 15-инчов дисплей, максималният резолюцията е само 12801024.
1. GF LCD екран
GF is the abbreviation of "Glass Fine Color". Perhaps everyone is unfamiliar with GF LCD screens, because there are very few digital products using GF LCD screens on the market. In fact, GF is a kind of STN. The main feature of GF is that it guarantees power consumption. The brightness has been improved under the premise of smaller size, but the GF LCD screen has some color cast.
2. STN LCD екран
STN is the abbreviation of "Super Teisted Nematic", which belongs to passive passive matrix LCD. Almost all the LCD screens of black and white mobile phones are made of this material. The color STN LCD screen is to add a color filter on the basis of the monochrome STN LCD screen, and divide each pixel in the monochrome display matrix into three sub-pixels, and display red, green, and blue through the color filter. A variety of colors, so as to achieve a color picture. Due to technical limitations, the current STN LCD screen has a maximum of 65536 colors, and most of the STN products seen on the market are 4096-color STN products, so STN is also called "pseudo-color".
3. TFT LCD екран
TFT is the abbreviation of "Thin Film Transistor", also known as "true color". It belongs to the active matrix liquid crystal screen. It is a screen composed of thin film transistors. Each of its liquid crystal pixels is driven by thin film transistors. Behind each pixel, there are four independent thin film transistors to drive the pixel to emit colored light, which can display true color with 24bit color depth. In terms of resolution, the TFT LCD screen can reach up to UXGA (16001200).
The arrangement of TFT is memorable, so it will not return to its original state immediately after the current disappears, thereby improving the shortcomings of STN LCD screen flicker and blur, effectively improving the effect of LCD screen displaying dynamic pictures, and the ability to display static pictures More prominently, the dragon point of TFT LCD screen is that the response time is short and the color is bright, so it is widely used in notebook computers, DV and DC. The disadvantage of TFT LCD is that it consumes more power and costs more.
4. OLED LCD екран
OLED is the abbreviation of "Organic Light Emitting Display", also known as organic light-emitting display. It uses organic light-emitting technology, which is the latest display technology. OLED display technology is different from traditional liquid crystal display methods. It does not require a backlight. Instead, very thin organic material coatings and glass substrates are used. These organic materials will emit light when there is current passing through, so it has a large viewing angle, and the content on the screen can be seen clearly from all directions, and it can be done. It is very thin, and the OLED display can significantly save power, and is known as the "dream display."
But OLED is not without its shortcomings. Because it is still an immature technology, its service life is relatively short at this stage, and the screen area is relatively small.
Основните характеристики на TFT LCD екрана:
5. TFD LCD екран
TFD is the abbreviation of "Thin Film Diode". Due to the high power consumption and high cost of TFT LCD screens, which greatly increase the cost of the product, EPSON has developed TFD technology specifically for mobile phone screens, which is also active Matrix LCD screen, each pixel on the LCD is equipped with a separate diode, each pixel can be individually controlled, so that each pixel will not affect each other, which can significantly improve the resolution, and there is no smearing Display dynamic pictures and brilliant colors.
In terms of performance, TFD LCD screens take into account the advantages of TFT LCD screens and STN LCD screens. TFD LCD screens have higher brightness than STN LCD screens, and the colors are more vivid. At the same time, it is more power-efficient than TFT LCD screens. The brightness is still inferior to TFT LCD.
With the maturity of TFT technology in the early 1990s, color LCD flat-panel displays developed rapidly. In less than 10 years, TFT-LCD has rapidly grown into a mainstream display, which is inseparable from its advantages. The main features are:
(1) Характеристики на добра употреба: приложение с ниско напрежение, ниско напрежение на задвижване и подобрена безопасност и надеждност при стабилна употреба; плосък панел, лек и тънък, спестяващ много суровини и използване на пространство; ниска консумация на енергия, консумацията му е около CRT дисплей Една-десета от този, отразяващ TFT-LCD е дори само около една-стотна от тази на CRT, спестявайки много енергия ; TFT-LCD продуктите също имат спецификации, модели и размери в серии, с различни разновидности, удобна и гъвкава употреба, поддръжка и актуализиране, лесна за надграждане, дълъг експлоатационен живот и много други функции. Диапазонът на дисплея обхваща обхвата на приложение на всички дисплеи от 1 инч до 40 инча и голямата прожекционна равнина. Това е дисплей-терминал с пълен размер; качеството на дисплея варира от най-простата монохромна символна графика до висока разделителна способност и висока точност на цветовете. Видео дисплеи с различни спецификации и модели с висока яркост, висок контраст и висока скорост на реакция; методите на показване включват директен изглед, прожекция, виждане-през и отразяващ.
(2) Степента на автоматизация на производствената технология е висока, а характеристиките на широкомащабното-промишлено производство са добри. Технологията на TFT{2}}LCD индустрията е зряла и добивът на масово производство е достигнал повече от 90 процента.
(3) Обхватът на приложение е широк и може да се използва нормално в температурен диапазон от -20 градуса до плюс 50 градуса. Нискотемпературната работна температура на TFT-LCD след обработка за укрепване на температурата може да достигне минус 80 градуса. Може да се използва като дисплей на мобилен терминал, настолен терминален дисплей и голям-прожекционен телевизор. Това е терминал за видео дисплей в пълен размер с отлична производителност.
(4) Good environmental protection characteristics: no radiation, no flicker, no harm to the user's health. In particular, the emergence of TFT-LCD e-books will bring mankind into the era of paperless office and paperless printing, triggering a revolution in human learning, dissemination, and recording of civilization.
(5) TFT-LCD е лесен за интегриране и надграждане. Това е перфектна комбинация от широкомащабна-технология за полупроводникови интегрални схеми и технология за източник на светлина и има голям потенциал за продължаващо развитие. Понастоящем съществуват аморфни, поликристални и монокристални силициеви TFT-LCD. В бъдеще ще има TFT от други материали, включително стъклени и пластмасови субстрати.
The TFT liquid crystal display is characterized by good brightness, high contrast, strong sense of layering, and bright colors, but it also has the disadvantages of relatively power consumption and high cost. TFT LCD technology has accelerated the development of mobile phone color screens. Many of the new generation of color-screen mobile phones support 65536 color displays, and some even support 160,000 color displays. At this time, the advantages of TFT's high contrast and rich colors are very important.
