quality TFT LCD Display & TFT LCD Module factory

  Nowadays, the use of strip LCD screens is quite widespread, and there are also many types of strip screen products on the market. Some products from different manufacturers have significant price differences, which is very troublesome for consumers, who do not know how to distinguish and choose. Due to the different price positioning of strip LCD screens produced by various manufacturers, the quality requirements are also different. So, what are the factors that cause different prices of strip LCD screens? Let's give a brief introduction below. 1. Viewing angle of bar LCD screen For current LCD displays on the market, the viewing angle is symmetrical, but not necessarily vertical. The vertical viewing angle is usually smaller than the horizontal viewing angle. Due to the directionality of the light source of the backlight tube after refraction and reflection, color distortion occurs when viewed beyond this range. Generally, the horizontal viewing angle is the main parameter, and the larger the value, the larger the viewing angle.                        2. Brightness and contrast of bar LCD screen Brightness is one of the important indicators reflecting the performance of liquid crystal displays. The brightness of LCD screens is measured in square candles (cd/m2) or nits, and is generally between 100-130 nits. It should be noted that data is not the entirety of product performance, and brighter products may not necessarily be better products. The key is whether the brightness is uniform, which cannot be found in the product specification manual. The uniformity of brightness is closely related to the number and configuration of light sources and mirrors. Places far away from the light source will inevitably have darker brightness. 3. Response time and refresh rate (i.e. scanning frequency) of bar LCD screen Response time is a specific indicator of LCD displays, which refers to the speed at which each pixel of the LCD display responds to input signals, measured in milliseconds (ms). The smaller the response time, the faster the pixel response, while the longer the response time, the more severe the display tailing phenomenon when displaying dynamic images (even mouse cursor). Currently, the standard response time for LCD displays should be below 30ms.                         4. Pixel spacing of bar LCD screen The pixel pitch of a bar LCD screen is similar in meaning to the dot pitch of a CRT. However, the former is not as important to product performance as the latter. The number of pixels in LCD displays is relatively fixed, therefore, as long as the size and resolution are the same, the pixel spacing of all products should be the same. For example, a 15 inch LCD monitor with a resolution of 1024 × 768 has a pixel pitch of 0.297mm (some products are also labeled as 0.30mm).

  Performance and indicators of LCD polarizer The optical performance of polarizing film includes three main performance indicators: polarization degree, transmittance, and color tone. Other performance indicators include UV resistance, transmittance, total reflectance, and diffuse reflectance of semi transparent polarizing film semi permeable membranes. In the use of general LCD products, it is required that the higher the polarization and transmittance performance indicators, the better. The higher the polarization and transmittance, the higher the display efficiency of LCD display devices and the lower the relative energy consumption. But for conventional iodine dyed polarizing film products, polarization degree and transmittance are contradictory. The higher the polarization degree, the lower the transmittance, and it is also constrained by color tone. Therefore, the polarization degree of ordinary polarizing film products is generally between 90% and 99%, and the transmittance is between 41% and 44%. The "Fudi" brand polarizer universal PLN product produced by Guangdong Fudi Rihe Polarizing Device Co., Ltd. has a polarization degree of over 97% and a transmittance of 43%, while the medium durability and high contrast PMN product has a polarization degree of over 99.9% and a transmittance of over 42%. The color tone index is mainly to meet people's visual habits, while requiring the color tone deviation of polarizer products to be small to ensure the consistency of the appearance color tone of LCD final products. This is mainly identified by the chromaticity coordinate parameters L, a, b values of polarizer products and their control tolerance range. Generally, the smaller the control tolerance range, the better. The durability technical indicators of polarizing film include four technical indicators: high temperature resistance, moisture and heat resistance, low temperature resistance, and thermal shock resistance, among which the most important is the level of moisture and heat resistance performance indicators. High temperature resistance refers to the temperature resistant working conditions of polarizing film at a constant baking temperature. Currently, according to the technical level of polarizing film, it is usually divided into three levels: universal type: working temperature of 70 ℃× 500HR; medium durability type: working temperature of 80 ℃× 500HR; high durability type: working temperature above 90 ℃× 500H. The moisture and heat resistance technical indicators refer to the moisture and heat resistance performance of polarizing films under constant temperature and humidity conditions. It is usually divided into three technical levels: universal type: moisture and heat working conditions of 40 ℃ × 90% RH × 500HR; medium durability type: moisture and heat working conditions of 60 ℃ × 90% RH × 500HR; high durability type: moisture and heat working conditions of 70 ℃ × 95% RH × 500HR or above. Due to the fact that PVA film, iodine, and iodide, which are the basic materials that make up polarizing films, are easily hydrolyzed, and the pressure-sensitive adhesive used in polarizing films is also prone to degradation under high temperature and high humidity conditions, the most important durability technical indicators for polarizing films are high temperature resistance and moisture resistance. If the high temperature resistance and moisture resistance indicators are passed, other durability indicators usually do not have problems. The technical indicators of the adhesive properties of polarizing film mainly refer to the various characteristics of the pressure-sensitive adhesive of polarizing film, generally including the peeling force between the pressure-sensitive adhesive and the glass substrate, the peeling force between the pressure-sensitive adhesive and the peeling film, the peeling force between the polarizing film protective film and the polarizing film, and the adhesive durability of the pressure-sensitive adhesive. The peeling force between pressure-sensitive adhesive and glass substrate, also known as the adhesive strength of the adhesive, is the most important adhesive characteristic index of LCD polarizer products. This technical indicator is usually measured using the EIAJ-ED-2521A standard of the Japan Electronic Machinery Industry Association, expressed in units of g/25mm. Typically, the peeling force of LCD polarizer pressure-sensitive adhesive on glass substrates is specified at 500g/25mm or above, while in actual use, the upper limit is generally below 1000g/25mm. There are practical examples showing that when the peeling force of the adhesive on the glass substrate is below 500g/25mm, the phenomenon of automatic peeling and warping of the polarizer after bonding on the surface of the glass screen will occur. The appearance performance technical indicators of polarizing film mainly refer to the surface flatness and the number of appearance defects of polarizing film products. These technical indicators mainly affect the utilization rate of polarizing film products during surface mounting. These technical indicators usually have relatively consistent technical regulations in the polarizer industry, generally with less than 15 defects of no more than 150 μ m per polarizer product (500 × 1000mm). Due to the fact that the final appearance inspection of polarizing film products is carried out through manual visual inspection, there will be a certain degree of dispersion in the distribution of appearance defects during the mass production process of polarizing film products. Therefore, various polarizing film production enterprises adopt a certain difference between internal control specifications and delivery specifications to ensure delivery quality standards. However, it should be noted that due to the fact that 150 μ m is already close to the minimum limit of human visual resolution, especially in industrial mass production processes, inspectors may still experience visual fatigue during long-term operations. Therefore, the under point inspection standard of 150 μ m is relatively reasonable and reliable. The main factors affecting the performance indicators of LCD polarizing film The main factors affecting the performance of polarizers are related to their basic performance indicators. The main influencing factors on the optical performance technical indicators of polarizing films include: the selection of polarizing film materials, the selection of dyeing materials, the dyeing of polarizing films, the selection of stretching process conditions, and the limitations of equipment capabilities. These all involve the core technology of polarizer production, so polarizer manufacturers are very cautious in choosing these materials and process conditions, and generally do not easily change them. Once the products of polarizer manufacturers are recognized by customers, they will take strict production quality management measures to ensure the stability of the optical performance of polarizer products. The durability technical indicators of polarizing film products actually include two aspects of durability indicators: the durability of polarizing film and the durability of pressure-sensitive adhesive. The main influencing factors on the durability of polarizing film include: the selection of basic materials for polarizing film, the selection of dyeing materials, and the process conditions for polarizing film dyeing, stretching, and composite. Generally speaking, the higher the molecular weight and stretching ratio of PVA film used for polarizing film, the better the durability of the polarizing film, and vice versa. The better the coloring degree of the polarizing film during the production process, the stronger the resistance of the dye used to hydrolysis, and the better the durability of the polarizing film. Therefore, the durability of dye based polarizing films is much better than that of iodine based polarizing film products. The main factors affecting the durability of pressure-sensitive adhesives include the selection of adhesive formula, adhesive solvent, adhesive blending process conditions, adhesive drying process conditions, and adhesive storage conditions. It should be noted that the durability index of adhesives is a comprehensive index, and its impact is multifaceted. This is another core technology in the production of polarizing films. Generally, polarizing film production enterprises will not easily change the process conditions of adhesives after determining them, and have strict process quality management requirements. Otherwise, it is easy to cause batch product defects. The main factors affecting the appearance and performance of polarizing films are also multifaceted. Mainly includes: environmental purification conditions for polarizer production, material selection for polarizer production, equipment conditions for polarizer production, process flow and formula for polarizer production, packaging, storage, and transportation conditions for polarizer, as well as storage environment and processing methods for polarizer during customer use. In short, polarizing film is a very delicate product that must be carefully stored and used, otherwise it is easy to cause surface defects such as pits, black spots, and warping.

   Low Blue Light mode, a new feature that became popular around 2016, has now become a standard feature on monitors. According to media reports, blue light has already made people pale at the sound, as its harm to the eyes has been verified through medical examples. The low blue light mode usually uses a slider or a series of preset forms to gradually reduce the blue light in the image. After enabling this function, it has a certain impact on the overall color presentation of the screen, but it is indeed necessary for protecting the eyes.                           response time Response time, also known as standard response time, refers to the time required to turn off a pixel, then turn it on and off again (or from black to white and back to black). The response time of a monitor is divided into standard response time and grayscale response time. If the response time is too long, there may be "blurriness" and "ghosting" when playing games or watching movies. The general experience for consumers when making purchases is that the shorter the response time, the better. Additionally, it should be noted that the response time is divided into two parts: Tr (rise time) and Tf (fall time). The transition from black to white is called rise, and from white to black is called fall. The response time is the sum of these two values. However, some manufacturers only label one of these two values to mislead consumers, so it is important to understand them clearly when making a purchase.   Curved display Monitors are divided into regular flat displays and curved displays. In theory, curved screens provide a wider viewing angle and an immersive experience, with smaller curvature radii resulting in greater curvature. To reap the benefits of curved surfaces, you need a large 100 inch screen and sit very close, which may give you a more immersive "movie" experience. But you may not want such a big TV or computer monitor, and you may not want to sit so close. If your monitor is not that big, a curved monitor is actually not very useful.                         Brightness/contrast Liquid crystal is a substance between liquid and crystal, and cannot emit light on its own, so the brightness of the backlight determines its brightness. Generally speaking, the higher the brightness of a LCD display, the more vivid the displayed colors and the better the display effect; If the brightness is too low, the displayed color will be darker, and you will feel tired after watching for a long time. Contrast is the ratio of brightness, which refers to the brightness of a white image divided by the brightness of a black image in a dark room. Therefore, the brighter the white and the darker the black, the higher the contrast, the clearer and brighter the displayed image, and the stronger the sense of color hierarchy. For consumers who frequently use computers to play games or do graphic processing, they should choose LCD displays with higher contrast. For users who have a special preference for DVD blockbusters, high brightness/high contrast LCD displays are the most suitable choice. Of course, higher brightness and contrast are not necessarily better. Watching a high brightness LCD screen for a long time can also easily cause eye fatigue. Bad pixels "are irreparable physical pixels on a LCD panel, divided into bright and dark spots. Bright spots refer to pixels that still emit light when the screen displays black, while dark spots refer to pixels that do not display color. As their presence can affect the display effect of the image, the fewer bad pixels, the better. Consumers should not choose products with more than three bad pixels when selecting LCD displays. How to test for bad pixels on a monitor? Users can use the Nokia Monitor Test software for testing. In addition to "dark spots" and "bright spots", there are also "color dots" that always display a single color. The light of a LCD monitor is emitted forward through the liquid crystal at a nearly vertical angle, so when we observe the screen from other angles, we will not see it as clearly as we do with a CRT monitor, but will see obvious color distortion. This is caused by the size of the viewing angle. The viewing angle is divided into horizontal viewing angle and vertical viewing angle. When choosing a LCD display, it is advisable to choose products with larger viewing angles. At present, the viewing angle of LCD displays is generally above 140 degrees, which can meet the needs of ordinary users. Regardless of the visual angle value, whether it is convenient for one's own use is fundamental, and it is best to choose according to one's daily usage habits. The warranty period of the monitor is determined by the manufacturer themselves, usually with a full free warranty service of 1-3 years. Therefore, consumers need to understand the detailed warranty period to avoid any problems that may affect their use of the product. Therefore, consumers should try to choose products with longer warranty periods.

1. Outdoor advertising machine runs black screen Check if the air conditioning of the outdoor LCD advertising machine is working and if the internal temperature is too high. If the air conditioning is not cooling, it needs to be replaced. 2. The remote control cannot be operated Check if the remote control of the outdoor high brightness advertising machine is equipped with a dry battery, if the remote control head is aligned with the remote sensing sensor, and if the wire from the remote sensing sensor to the drive board is loose. If there are no issues mentioned above, it may be due to a damaged remote control or driver board. 3. The outdoor advertising machine displays a signal on the screen, but the screen is not full Use the remote control to press "menu" - "setting" - "adjust" to semi automatically adjust the portrait 4. Display screen with image but no sound Check if the video signal cable of the advertising machine is connected correctly, if there is image display during remote control operation, and if the signal source selection is correct. If none of the above issues are found, it may be due to a broken driver board.                            5. Outdoor LCD advertising machine is not powered on (black screen) It may be due to poor internal power supply or faulty internal driver board of the device. Troubleshooting method: Check if the power output is normal. If there is no output from the power supply, it can be confirmed that there is a fault with the power supply; If the power output is normal, it may be a defect in the driver board. 6. Flower screen The situation where a certain area on the surface of the display screen cannot be displayed or the display screen is abnormal is called a splash screen. Troubleshooting method: Check if the signal transmission line inserted into the LCD screen is loose, causing poor contact. If so, insert and secure the signal line, and check if the problem is resolved. If it is not caused by this situation, it may be due to a faulty LCD screen. 7. Dark screen (no display, flashing screen) When playing advertisements, if the LCD screen remains black, dark, or flashing, it is referred to as a dark screen. Troubleshooting method: Check if the power output is normal. If the power output voltage is unstable and does not reach 11V-12V, it can be confirmed that the power supply has a fault. If the power output is abnormal, it is necessary to replace the driver board and inverter one by one until the fault is resolved. 8. No signal When powered on, the words' no signal 'appearing on the screen are called' no signal '. Troubleshooting method: Check if the internal video cable and the 5V power cord input to the decoding board are loose. If they are not loose, replace the decoding board or driver board and check if the fault disappears.

一丶Composition of TFT-LCD panel Disassemble the LCD panel, which can be divided into three main parts: 1. LCD panel 2. TFT panel 3. Backlight module As for other driver ICs or iron frame structures used to fix these three parts, they will not be described separately; The specific decomposition diagram is as follows;                                                二丶The role of each part 1. Backlight source (or backlight module) The backlight layer is actually the structure of the backlight source and the light guide plate, which is a light tube or light-emitting diode that can emit white light. The backlight source is mostly LED light source now. So when TV vendors refer to LED, they actually mean LCD with LED backlight, not real LED. Due to the fact that liquid crystal molecules themselves cannot emit light, in order to display images, liquid crystal displays require specialized light sources to provide light, which is then deflected by the liquid crystal molecules to produce different colors. The backlight serves to provide light energy. After the light tube (or LED) emits light, it is distributed to various places through a light guide plate, and the direction of all the light is concentrated towards the liquid crystal molecules through a reflective plate on the back. Finally, the light is evenly distributed through the prism sheet and diffuser plate to avoid situations where the central brightness is too high and the surrounding brightness is too low.                              The above picture shows a light guide plate, which has a simple function of making the backlight uniform. Upon careful observation, it can be seen that the surface of the backlight panel is densely packed with dots that serve as light guides. Professional optical analysis and production are required to control the density of the dots at each position, thereby regulating the amount of light emitted by the light guide panel at that location. The precision designed light guide plate dots can evenly spread the incident light on both sides on the entire plane; If there are problems with the placement of the light tubes or the light guide plate in the backlight layer, it can easily lead to the appearance of a cathode ray screen; There is also a layer of shiny reflective paper underneath the light guide plate, which has a simple function of reflecting the light from above back. Previously, mobile phones were relatively thick, and the entire backlight module was surrounded and protected by an iron frame. Nowadays, many projects omit the iron frame in order to make it thinner, which can lead to a problem. Once the bottom reflective paper is deformed by force, the reflected light is locally concentrated, resulting in water ripples on the surface of the screen; 2. Diffusion sheet In the backlight structure, it mainly plays a role in correcting the diffusion angle, which increases the radiation area but reduces the light intensity per unit area, that is, lowers the brightness After being diffused by a diffusion material, the luminescent light source can become larger in area and have better uniformity; 3. Brightening film Also known as prism film, it usually has two layers, mainly used to enhance brightness. The prism film is placed between the diffuser of the backlight and the liquid crystal panel. It can converge the light emitted from the diffuser uniformly at various angles to the axial angle, that is, the positive viewing angle, and improve the axial brightness without increasing the total emitted light flux; If the diffusion sheet or prism film is locally damaged, the exported light will have problems, resulting in white spots and other issues appearing on the screen; 4. Two polarizing films on the upper and lower layers The function of polarizing film is to allow light to pass through in one direction. The polarizing layer is made by dyeing and stretching PVA film, which is the main part of polarizing film, also known as polarizing film. It determines the polarization performance and transmittance of the polarizer, while also affecting the color tone and optical durability of the polarizer. 5. Two glass substrates on the upper and lower layers A glass substrate is not just two pieces of glass, it has a groove structure on the inside and is attached with an alignment film, which allows liquid crystal molecules to be arranged neatly along the grooves. TFT thin film transistors and color filters will be affixed on both sides of the upper and lower glass layers. The liquid crystal layer is sandwiched between two layers of glass; 6. Thin film transistor (also known as TFT) We often refer to TFT-LCD, which actually refers to this thin film transistor. Its function is similar to a switch. TFT can control the signal voltage on the IC control circuit and deliver it to the liquid crystal molecules, determining the angle of liquid crystal molecule deflection. Therefore, it is a very important component. 7. Liquid crystal molecular layer The liquid crystal molecular layer is the most important element that changes the polarization state of light, and its arrangement and polarization state are determined by both electric and elastic forces. 8. Color filter The light deflected by liquid crystal molecules can only display different gray levels, but cannot provide the three primary colors of red, green, and blue (RGB). Color filters are composed of RGB filters, which are mixed to adjust the colors and brightness of each color. Each pixel in the LCD panel is composed of three dots: red, green, and blue, with each color dot having a different grayscale variation. A filter is made of plastic or glass with special dyes added. A red filter can only allow red light to pass through, and so on. The transmittance of glass sheets was originally similar to that of air, allowing all colored light to pass through, making them transparent. However, after dyeing, the molecular structure changes and the refractive index also changes, resulting in changes in the passage of certain colored light. For example, a beam of white light passing through a blue filter emits a beam of blue light, while green and red light are very rare and mostly absorbed by the filter