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Nowadays, the pictures of liquid crystal display products on the market are getting clearer and more refined, but not all screens are so excellent. So how does the LCD screen distinguish between good and bad screens? This involves a concept, the classification of LCD screens. Different display application scenarios, choose different LCD screen grades, so as to match the screen that is most suitable for your product. Generally, the grades of LCD liquid crystal screens can be roughly divided into A grade, B grade, and C grade. LCD panel manufacturers also divide A-level panels into two levels, A+ and A, which are mainly aimed at products with higher display quality requirements.

Classification of LCD screens——A+ grade LCD screens So what is the basis for distinguishing LCD screen levels? Usually the LCD screen industry judges the level of LCD screens based on the number of dead pixels on the LCD screen. First of all, let's introduce a concept: LCD screen dead pixels. We all know that the LCD screen can be subdivided into each sub-pixel, and the sub-pixels can display black and white and the three primary colors of red, green and blue. The dead pixel of the LCD screen means that no matter what the image displayed on the LCD screen is, a certain sub-pixel on the screen will always display the same color. Dead pixels can be roughly divided into two categories, one is that the sub-pixels are always black no matter how the screen is, called dark spots, and the other is that as long as the screen is turned on, there will always be bright spots, called bright spots. Generally speaking, dead pixels on the screen cannot be repaired, and can only be repaired by replacing the entire screen.

Knowing the concept of LCD screen dead pixels, let's roughly introduce the division of LCD screen levels:

A+ grade LCD screen: LCD screen without any dead pixels is called A+ grade LCD screen. Through the professional test software test, there is no bright spot in the power-on state, and there is no dark spot behind the display screen, and the display screen is stable and smooth. A+ grade LCD screen is the highest quality LCD screen, suitable for display fields that require extremely high display quality, such as LCD monitors, vehicle displays, medical displays, etc.

A-level LCD screen: The total number of dead pixels does not exceed 3, and there is only one bright spot at most, and the bright spot is not in the central area of the screen. We call it an A-level LCD screen. The screen display is still high-quality and smooth, and generally there will be no obvious dead pixels during use. General application and LCD TV, home appliance display and other fields.

B-level LCD screen: The total number of dead pixels does not exceed 5, and there are only 2 bright spots at most, and the bright spots are not in the central area of the screen, which is called B-level LCD screen. The brightness of the screen is relatively uneven, and the color saturation is relatively insufficient. Most cheap LCD monitors use this kind of B-level panel, and the cost is relatively cheap.

What is the soft screen of an lcd display liquid? Which is a hard screen, first of all, let's introduce their concepts. The hard screen technology of LCD adopts a horizontal arrangement as the arrangement structure of liquid crystal molecules. When encountering external pressure, the molecular structure sinks slightly downwards, but the overall molecules are still horizontal. LCD hard screens are mainly IPS panels. The soft screen technology of LCD adopts vertical arrangement as the arrangement structure of liquid crystal molecules. When the finger crosses the LCD panel, "ripples" will appear at the same time, and the LCD soft screen is mainly a VA panel.

Let's analyze the difference between LCD hard screen and soft screen:

1. The arrangement of liquid crystal molecules is different: the IPS hard screen is a parallel arrangement of molecules, and the VA soft screen is a vertical arrangement of molecules. This will affect the response time of the screen. The inclination angle of the initial alignment direction of the soft screen liquid crystal molecules relative to the direction of the electric field is extremely small, and most of the liquid crystal molecules need to be rotated by nearly 90 degrees during the driving process; while the liquid crystal molecule alignment of the hard screen horizontal alignment technology generally has an inclination angle of 5 degrees compared to the direction of the electric field Above, only need to rotate 80 degrees during the driving process, and most of the liquid crystal molecules do not need to rotate to the limit angle during the driving process. Therefore, the response time of the LCD hard screen is better than that of the soft screen.

2. The surface of the LCD panel is different: VA soft screen is an LCD panel without a protective film. IPS hard screen is to add a layer of transparent resin material with a high hardness on the LCD screen to protect the outer film. In fact, the fundamental difference between an LCD hard screen and a soft screen is that the surface of the screen is coated or uncoated.

The difference between LCD hard screen and soft screen 3. Differences in viewing angle: viewing angle is an important indicator of LCD screens, especially for large-size screens, the differences in brightness, contrast, and color between front and side viewing angles will greatly affect the viewing experience. The VA soft screen vertical alignment technology uses 4-domain pixel electrodes to use liquid crystal molecules to flip in 4 directions to improve the performance of the viewing angle. There are still a lot of deficiencies in shifting, and the use of compensation films is still not optimistic. The IPS hard screen technology adopts an 8-domain design and applies different voltages to two 4-domain partitions in a pixel to increase the dispersion of the liquid crystal molecule arrangement and improve the color shift. The horizontal alignment technology of the IPS hard screen is determined by innate genes. In addition to its advantages in viewing angle, it can achieve a side viewing angle display effect far exceeding that of a VA soft screen without using a compensation film.

4. The pressing characteristics of the screen are different: when the LCD soft screen is lightly pressed with a finger or scratched with a fingernail, there will be obvious water ripples, but they will disappear after a while, and the image quality will not be affected. The hard-screen screen has a certain degree of stability, and there will be no obvious marks when you press it lightly with your fingers, which is good for screen protection, but the bonding process must be good enough.

5. The display effect is different: the soft screen has good color performance and a strong sense of layering, but the viewing angle is relatively poor, the touch will be distorted, and the high-speed motion picture is poor. The hard screen has a large viewing angle, fast response, and accurate color reproduction.

LCD (Liquid Crystal Display) displays through the movement of liquid crystal molecules and backlighting, while OLED (Organic Light Emitting Diode) emits light once it is powered on.

So the main difference between them is that LCD displays need a backlight to illuminate the screen, while OLED displays can generate light by themselves.

Basic composition of LCD and OLED Compared with LCD displays, OLED does not require external light, so it can reduce the number of CCFL backlight modules, as well as TFT glass, C/F glass and a set of substrates. Due to these characteristics, the structure of the OLED display is simpler, lighter, and power-saving.

In the era of full screens, OLED displays are more popular. And this is also related to fingerprint recognition technology. Because this technology needs to see through the display, the thinner the display, the better. That's why OLED displays are favored. All in all, OLED displays are better for smartphones.

The structural difference between LCD and OLED However, not all OLED displays are perfect. LCD display has 3 panel types: TN panel, VA panel, IPS panel. There are also 2 types of OLED displays: AM active and PM passive. Although AMOLED plays a leading role in the market, the display effect of AMOLED still varies from manufacturer to manufacturer.

Why AMOLED have different display effects?

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P-array of AMOLED: When it comes to the shortcomings of AMOLED, the first thing people think of is the P-array, that is, the Pentile array. Samsung is the first company to mass-produce OLED panels and use P-array. The Galaxy S4 first used a P-array called Diamond Pixel, which took a different path from the standard RGB arrangement.

RGB type and P array Simply put, the RGB type arranges the sub-pixels of the three primary colors of red, green, and blue evenly, and the RGB sub-pixels are not evenly arranged in the P array, but share pixels, so the actual pixel density of the P array is higher than that of the RGB Low. This has led to the fact that even at the same resolution, the P-array OLED display is not as clear as RGB, so it is often called "big fruit color-changing screen".

With the rapid development of automobile technology, people's experience of using a car is not only limited to the driving texture, but the onboard display system has attracted more and more attention. Most of the car LCD screens currently on the market are LCD screens. Due to the special use environment of the vehicle display, the screen is generally required to be moisture-proof, dust-proof, anti-glare, visible under high-brightness sunlight, and resistant to high and low temperatures. These can be said to be the most basic requirements for on-board display and combined with physical buttons, it is a qualified on-board display product.

However, with the intelligent development of in-vehicle display technology, the screen will not stay at the stage of physical buttons. The in-vehicle touch screen is currently developing rapidly. Representatives of a series of new energy models such as Tesla, Weilai, and Xiaopeng, even All the physical buttons have been abandoned, and a whole car touch LCD screen is used to integrate all functions. Car touch screens and car touch screens will be the development trend and future of car displays.

car touch screen Most car touch screens use capacitive touch technology, and the technical characteristics of capacitive touch screens have also been introduced in our previous articles. Capacitive touch screens are different from resistive touch screens. The biggest advantage is high touch accuracy, fast response, and support for multi-point touch. , to support larger screen sizes.

First of all, let's talk about the large size of the car's capacitive touch screen. Today's car touch screens are becoming larger and larger. Large-size car screens can not only integrate more functions on the screen, but also fully display the menu, and greatly improve the presentation of visual effects. Traditional car companies such as Toyota and Volkswagen have increased the size of the touch screen to more than 10 inches, and new energy vehicles such as Tesla and Weilai have even increased the size of the touch screen to more than 15 inches. Capacitive touch modules can be customized in various sizes, especially for large-sized car touch screens, which can fit perfectly. Therefore, the capacitive touch screen is the first choice for large-size vehicle displays at present.

Secondly, let's talk about the multi-touch of the capacitive touch screen. How is multi-touch implemented? Specifically, the screen is divided into blocks, and a group of mutual capacitance modules is set in each block to work independently so that the capacitive screen can independently detect the touch conditions in each area, and after processing, realize multi-touch. Multi-touch is very useful in the application of car touch screens, especially when zooming in and out of map navigation, it is very convenient.

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In the use of some outdoor equipment, due to environmental reasons, the brightness of the screen is usually required to be very high. Such as handheld infrared thermometers, outdoor commercial screens, etc. This requires us to use an outdoor bright LCD screen as the screen of the device. Next, let's focus on the concept and characteristics of outdoor bright LCD screens.

1. The concept of the outdoor bright LCD screen

The so-called outdoor high-brightness LCD screen, as the name suggests, first of all, it is brighter than ordinary LCD screens. The maximum brightness of an ordinary LCD screen is within 500 units, and the backlight source uses CCFL, which cannot be seen clearly outdoors. The reason why the outdoor high-brightness LCD screen can be used outdoors is to increase the brightness of its backlight. LED backlight is used, which is similar to or even higher than outdoor brightness. Generally, it needs to be higher than 500 units, and some can even reach the highest. 2000nits brightness, so that the outdoor LCD screen can be clearly displayed. Secondly, due to the variability of the outdoor environment, to ensure that the screen can operate normally without hindrance in various environmental conditions, the outdoor high-brightness screen must also have multiple functions such as wide temperature range, dustproof, and waterproof.

Outdoor bright LCD screen Second, the characteristics of the outdoor bright LCD screen

The outdoor high-brightness LCD screen has many advantages such as high brightness, high resolution, long life, wide temperature range, waterproof and dustproof. The most important feature is, of course, the high brightness, which is above 500nits. Using high-efficiency LED backlight modules, not only the brightness and contrast are greatly improved, but also the display effect and lifespan are also greatly improved. In this way, it is visible and readable in outdoor sunlight and has an ultra-wide brightness range.

Secondly, the resolution is also a very important indicator. It refers to the number of pixels that can be displayed in the horizontal and vertical directions on the screen. High resolution can make the picture more delicate and display more important information on the screen.

Wide temperature characteristics of the outdoor bright LCD screen. The outdoor environment is changeable, ranging from high-temperature exposure to ultra-low temperature. Therefore, the screen used outdoors must have the characteristics of a wide temperature range, and the working temperature and storage temperature of the screen must reach the range of -30°C to 85°C. Only by paying attention to high and low-temperature design can the failure of outdoor high-brightness LCD screens be reduced.

Dustproof and waterproof performance of outdoor high-brightness LCD screen. In addition to the cold winter and hot summer, there is also dust and water outdoors. The waterproof and dustproof outdoor screen is generally designed together with the whole machine, and special attention should be paid to the selection of materials to prevent the screen from entering water and dust.

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The English full name of the liquid crystal display is Liquid Crystal Display, referred to as LCD. It is a matrix display driven by thin-film transistors, which stimulate liquid crystal molecules with current to generate points, lines, and surfaces that cooperate with LED backlight to form a display screen. Let's talk about the classification of LCD MODULE from multiple dimensions.

LCD liquid crystal display Daquan Divided according to the display characteristics of LCD MODULE:

High-brightness display screen: The display brightness of MODULE is above 500cd/m2, which is suitable for display devices that need to be visible under outdoor sunlight.

Full viewing angle module: It has full viewing angle characteristics, and also has high contrast, color saturation, and dynamic clarity.

Wide temperature module: suitable for places with severe temperature conditions, the working temperature and storage temperature can reach -30 ℃ to +85 ℃, and the high-temperature limit of some models can reach 85 ℃.

Semi-reflective and semi-transparent screen: It has an outstanding display effect for display devices working under strong light, and excellent reading performance in low-light and low-light environments.

According to the panel type of LCD MODULE:

TN liquid crystal panel: the most basic and common display mode, simple to manufacture, high transmittance, and low cost.

IPS panel: excellent full viewing angle characteristics, dynamic definition, and color reproduction effect.

VA liquid crystal panel: With its advantages of wide viewing angle, high contrast, and no need for rubbing alignment, it has become the first choice for large-size TFT LCD liquid crystal panels.

LCD panel type According to the interface type of the LCD module: the most common interfaces include RGB interface, SPI interface, MCU interface, MIPI interface, LVDS interface, and others include HDMI interface, TTL interface, STN interface, etc.

According to the driving mode of LCD MODULE, there are three types: static drive (Static), simple matrix drive (Simple Matrix), an active matrix drive (Active Matrix).

OLED (Organic Light-Emitting Diode), also known as organic electric laser display, organic light-emitting semiconductor (Organic Electroluminescence Display, OLED). OLED belongs to a current-type organic light-emitting device, which is a phenomenon of luminescence caused by the injection and recombination of carriers, and the luminous intensity is proportional to the injected current. Under the action of the electric field, the holes generated by the anode and the electrons generated by the cathode will move, injected into the hole transport layer and the electron transport layer, respectively, and migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, thereby exciting the light-emitting molecules and finally producing visible light. Application field Because OLED has many advantages, OLED technology has a wider range of applications than LCD technology, and can be extended to the field of electronic products, business, transportation, industrial control, and medical fields. In recent years, major international enterprises They are constantly strengthening the research on OLED technology, and OLED technology will be further improved.

In the commercial field, small-sized OLED screens can be installed in POS machines, copiers, and ATM machines. Due to the characteristics of bendable, thin, and strong anti-aging properties, OLED screens are both beautiful and practical. The large screen can be used as a business publicity screen, and can also be used as an advertisement placement screen in stations and airports. This is because the OLED screen has a wide viewing angle, high brightness, and bright colors, and the visual effect is much better than the LCD screen.

In the field of electronic products, OLED is the most widely used in smartphones, followed by notebooks, displays, TVs, tablets, digital cameras and other fields. Because OLED displays are more colorful and can adjust colors (different display modes), Therefore, it is very widely used in practical applications, especially today's curved TVs, which are widely praised by the masses. It is necessary to mention a little VR technology here. The LCD screen has a very serious smear when watching VR equipment, but it will be alleviated a lot in the OLED screen. This is because the OLED screen is to light up light molecules, and the liquid crystal is the flow of light liquid.

Therefore, in 2016, the OLED screen officially surpassed the LCD screen and became the new darling of the mobile phone industry. In the field of transportation, OLEDs are mainly used for ships, aircraft instruments, GPS, video phones, car display screens, etc., and are mainly small in size. These fields mainly focus on the wide viewing angle performance of OLEDs, which can be clearly seen even if you do not look directly. When it comes to screen content, LCD is not. In the industrial field, my country's industry is developing in the direction of automation and intelligence, and more and more intelligent operating systems are introduced, which has more demands on the screen. OLED has a wider range of applications than LCD, both in touch-screen displays and viewing displays. In the medical field, the influence of medical diagnosis and the monitoring of surgical screens are inseparable from the screen. In order to meet the wide field of vision requirements of medical displays, OLED screens are the "best choice".

It can be seen that the development space of OLED display is very high, and the market potential is huge. However, compared with LCD screens, OLED manufacturing technology is not mature enough. Due to the low mass production rate and high cost, only some high-end devices in the market will use top-level OLED screens. However, judging from the data in the first half of 2017, various manufacturers have increased their research investment in OLED technology, and many mid-range electronic products in my country have applied OLED displays. From the perspective of the mobile phone industry, since 2015, the application ratio of OLED screens has increased year by year. Although there are still not as many LCD products, high-end smart phones have adopted the most advanced OLED screens. Therefore, the development of electronic products such as smart phones is bound to increase. Further promote the development of OLED. Development trend 1. It can really take advantage of OLED technology and still focus on AMOLED applications. PMOLED is simpler than AMOLED in terms of the structure and composition of its components. It has the manufacturing advantage of mass production and low cost. It is also the earliest mass production of OLED for display applications. product form.

PMOLED is suitable for display screen applications of mobile phones, especially for small panel applications where the amount of information displayed is not high, and the mass production cost is relatively low. However, when the main application products are increasingly turning to the application direction of high color, large size and fast display, PMOLED is obviously unable to meet the new demands in terms of technical conditions. But the real advantage of OLED technology is still dominated by AMOLED applications, especially in the field of display applications.

2. Flexible AMOLED can be applied AMOLED has flexible structure, so it also has the conditions to introduce e-ink electronic paper application.

3. The development of energy-saving light source OLED has become a global trend. The material characteristics of OLED not only amaze display manufacturers, but also interest lamp and light source manufacturers, such as Philips, Osram and other lamp manufacturers, because of the self-luminous characteristics of OLED. Try to invest in related research and development. In 2022, the first fully 3D printed flexible OLED display will come out. The following are several types of OLEDs: passive matrix OLEDs, active matrix OLEDs, transparent OLEDs, top emission OLEDs, foldable OLEDs, white light OLEDs, etc. Each OLED has its own unique use. Next, we will discuss these types of OLEDs one by one. The first is passive matrix and active matrix OLEDs. Passive Matrix OLEDs (PMOLEDs) PMOLEDs have a cathode strip, an organic layer, and an anode strip. The anode and cathode strips are perpendicular to each other. The intersection of the cathode and the anode forms the pixel, which is where the light is emitted. An external circuit applies current to selected cathode and anode strips to determine which pixels emit light and which do not. In addition, the brightness of each pixel is proportional to the magnitude of the applied current.

PMOLEDs are easy to manufacture, but they consume more power than other types of OLEDs, mainly because they require external circuitry. PMOLEDs are most efficient when used to display text and icons, and are suitable for making small screens (2-3 inches diagonal), such as those often found on mobile phones, PDAs, and MP3 players. Even with an external circuit, passive matrix OLEDs consume less power than the LCDs currently used in these devices. Active Matrix OLED (AMOLED) AMOLED has a complete cathode layer, organic molecular layer, and anode layer, but the anode layer is covered with an array of thin film transistors (TFT), forming a matrix. The TFT array itself is a circuit that determines which pixels emit light, which in turn determines the composition of the image.

AMOLED consumes less power than PMOLED because the TFT array requires less power than external circuits, so AMOLED is suitable for large displays. AMOLED also has a higher refresh rate and is suitable for displaying video. The best uses for AMOLED are computer monitors, large-screen TVs, and electronic signboards or signboards. Transparent OLEDs Transparent OLEDs have only transparent components (base layer, anode, cathode) and can be up to 85% of the transparency of the base layer when not emitting light. When the transparent OLED display is powered, light can pass in both directions. Transparent OLED displays can use either passive or active matrices. This technology can be used to make head-up displays that are often used in aircraft.

Top-emitting OLEDs have an opaque or reflective base layer. They are best suited for active matrix designs. Manufacturers can make smart cards using top-emitting OLED displays.

The full name of TFT: Thin Film Transistor, The application of TFT display products: intelligent wearing, children's education, smart home, industrial control medical treatment, mobile payment etc. All use relatively advanced TFT displays, which are made of liquid crystal pixels. It consists of dots and is driven by thin-film transistors integrated behind the pixel dots. Therefore, the TFT type display screen also belongs to a class of display devices with source matrix. TFT-type displays are the best among LCD color displays, and TFT-type displays have many advantages: high responsivity, high brightness, high contrast, and more. The display effect of a TFT-type display is closest to that of a CRT-type display. TFT-type screens also often appear on the screens of major mobile phones, with 65,536 colors, 160,000 colors, and 16 million colors, respectively. The display effect is also very good.

TFT means that each liquid crystal pixel on the liquid crystal display is driven by a thin film transistor integrated behind it. Thus, high-speed, high-brightness, and high-contrast display of screen information can be achieved. TFT-LCD (Thin Film Transistor Liquid Crystal Display) is a type of most liquid crystal displays.

LCD (short for Liquid Crystal Display). The structure of LCD is to place a liquid crystal cell in two parallel glass substrates, a TFT (thin film transistor) is arranged on the lower substrate glass, and a color filter is arranged on the upper substrate glass, and the signal and voltage on the TFT are changed to control the liquid crystal molecules. Rotate the direction, so as to control whether the polarized light of each pixel is emitted or not to achieve the display purpose. Now LCD has replaced CRT as the mainstream, the price has dropped a lot, and has been fully popularized.

1. Which is better, lcd screen or tft screen

TFT is a type of LCD screen.

TFT (Thin Film Transistor) is a thin film field effect transistor, which means that each liquid crystal pixel on a liquid crystal display is driven by a thin film transistor integrated behind it. Thereby, screen information can be displayed at high speed, high brightness and high contrast ratio.

One DOT point = three RGB pixels.

At present, most of the TN panels we see are improved TN+film, and film is a compensation film, which is used to make up for the lack of viewing angle of TN panels. At present, the viewing angles of improved TN panels have reached 160°. Of course, this is the manufacturer. The limit value measured when the contrast ratio is 10:1, in fact, when the contrast ratio drops to 100:1, the image has been distorted or even color cast.

The color screens of mobile phones vary according to the quality of LCD and research and development technology, and their types generally include STN (CSTN), TFT (LTPS), TFD, UFB and OLED.

Second, the difference between TFT and LCD liquid crystal screen

LCD (Liquid Crystal Display), the liquid crystal display. Generally, they are divided into two types: monochrome and color LCD screens. At present, monochrome LCDs have almost withdrawn from the notebook computer market, while color LCDs are still developing continuously. Color LCD is mainly divided into STN and TFT. Among them, TFT (Thin Film Transistor) LCD, also known as active transistor thin film transistor liquid crystal display, is also commonly known as true color liquid crystal display by many people; DSTN (Dual -Scn Twisted Nematic) LCD, that is, double-scanning liquid crystal display. It is a display method of STN LCD, which has now been withdrawn from the market.