construction of tft display factory

Display screen is everywhere nowadays. Do you still remember the TVs or computer monitors 20 years ago? They were quadrate, huge and heavy. Now let’s look at the flat, thin and light screen in front of you, have you ever wondered why is there such a big difference?

Actually, the monitors 20 year ago were CRT (Cathode Ray Tube) displays, which requires a large space to run the inner component. And now the screen here in your presence is the LCD (Liquid Crystal Display) screen.

As mentioned above, LCD is the abbreviation of Liquid Crystal Display. It’s a new display technology making use of the optical-electrical characteristic of liquid crystal.

Liquid crystal is a state of substance that has both the characteristics of liquid and solid crystal. It don’t emit light itself, but it can let the light pass perfectly in specific direction. Meanwhile, liquid crystal molecule will rotate under the influence of a electric field, and then the light goes through it will rotate too. That said, liquid crystal can be a switch of light, which is the key in display technology.

STN LCD: STN is for Super-twisted Nematic. The liquid crystal in STN LCD rotate more angles than that in TN LCD, and have a different electrical feature, allowing STN LCD to display more information. There are many improved version of STN LCD like DSTN LCD (double layer) and CSTN LCD (color). This LCD is used in many early phones, computers and outdoor devices.

TFT LCD: TFT is for Thin Film Transistor. It’s the latest generation of LCD technology and has been applied in all the displaying scenario including electronic devices, motor cars, industrial machines, etc. When you see the word ‘transistor’, you may realize there’s integrated circuits in TFT LCD. That’s correct and the secret that TFT LCD has the advantage of high resolution and full color display.

In a simple way, we can divide TFT LCD into three parts, from bottom to top they are: light system, circuit system and light and color control system.In manufacturing process, we’ll start from inner light and color control system and then stretch out to whole module.

It’s accustomed to divide TFT LCD manufacturing process into three main part: array, cell and module. The former two steps are about the production of light and color control system, which contains TFT, CF (color filter) and LC (liquid crystal), named a cell. And the last step is the assembly of cell, circuit and light system.

In order to enhance productivity, in this step we’ll do a series of procedure on a large glass, which will be cut into smaller pieces in the following step.

First, let me introduce a crucial material, ITO, to you. ITO, abbreviation of Indium tin oxide, has the characteristic of electrical conductivity and optical transparency, as well as can be easily deposited as a thin film. Thus it’s widely used to create circuit on glass.

Now let’s turn to the production of TFT and CF. Here is a common method called PR (photoresist) method. The whole process of PR method will be demonstrated in TFT production.

◇   Use glue to build a boundary for LC on both glass. And on CF glass, apply one more layer of conductive adhesive. This enable LC molecule link to the control circuit.

Important technical improvements of LCD, such as LED backlighting and wide viewing Angle, are directly related to LCD. And account for an LCD display 80% of the cost of the LCD panel, enough to show that the LCD panel is the core part of the entire display, the quality of the LCD panel, can be said to directly determine the quality of an LCD display.

The production of civil LCD displays is just an assembly process. The LCD panel, the main control circuit, shell, and other parts of the main assembly, basically will not have too complex technical problems.

Does this mean that LCDS are low-tech products? In fact, it is not. The production and manufacturing process of the LCD panels is very complicated, requiring at least 300 process processes. The whole process needs to be carried out in a dust-free environment and with precise technology.

The general structure of the LCD panel is not very complex, now the structure of the LCD panel is divided into two parts: the LCD panel and the backlight system.

Due to the LCD does not shine, so you need to use another light source to illuminate, the function of the backlight system is to this, but currently used CCFL lamp or LED backlight, don’t have the characteristics of the surface light source, so you need to guide plate, spreadsheet components, such as linear or point sources of light evenly across the surface, in order to make the entire LCD panel on the differences of luminous intensity is the same, but it is very difficult, to achieve the ideal state can be to try to reduce brightness non-uniformity, the backlight system has a lot to the test of design and workmanship.

In addition, there is a driving IC and printed circuit board beside the LCD panel, which is mainly used to control the rotation of LCD molecules in the LCD panel and the transmission of display signals. The LCD plate is thin and translucent without electricity. It is roughly shaped like a sandwich, with an LCD sandwiched between a layer of TFT glass and a layer of colored filters.

LCD with light refraction properties of solid crystals, with fluid flow characteristics at the same time, under the drive of the electrode, can be arranged in a way that, in accordance with the master want to control the strength of the light through, and then on the color filter, through the red, green, blue three colors of each pixel toning, eventually get the full-screen image.

According to the functional division, the LCD panel can be divided into the LCD panel and the backlight system. However, to produce an LCD panel, it needs to go through three complicated processes, namely, the manufacturing process of the front segment Array,the manufacturing process of the middle segment Cell, and the assembly of the rear segment module. Today we will be here, for you in detail to introduce the production of the LCD panel manufacturing process.

The manufacturing process of the LCD panel Array is mainly composed of four parts: film, yellow light, etch and peel film. If we just look at it in this way, many netizens do not understand the specific meaning of these four steps and why they do so.

First of all, the motion and arrangement of LCD molecules need electrons to drive them. Therefore, on the TFT glass, the carrier of LCD, there must be conductive parts to control the motion of LCD. In this case, we use ITO (Indium Tin Oxide) to do this.ITO is transparent and also acts as a thin-film conductive crystal so that it doesn’t block the backlight.

The different arrangement of LCD molecules and the rapid motion change can ensure that each pixel displays the corresponding color accurately and the image changes accurately and quickly, which requires the precision of LCD molecule control.ITO film needs special treatment, just like printing the circuit on the PCB board, drawing the conductive circuit on the whole LCD board.

First, the ITO film layer needs to be deposited on the TFT glass, so that there is a smooth and uniform ITO film on the whole TFT glass. Then, using ionized water, the ITO glass is cleaned and ready for the next step.

Next, a photoresist is applied to the glass on which ITO film is deposited, and a uniform photoresist layer is formed on the ITO glass. After baking for a period of time, the solvent of the photoresist was partially volatilized to increase the adhesion of the photoresist material to the ITO glass.

Ultraviolet light (UV) is used to illuminate the surface of the photoresist through a pre-made electrode pattern mask, which causes the photoresist layer to react. The photoresist is selectively exposed under ultraviolet light by covering the photoresist on the glass coated with the photoresist.

The exposed part of the photoresist is then washed away with the developer, leaving only the unexposed part, and the dissolved photoresist is then washed away with deionized water.

Then etch off the ITO film without photoresist covering with appropriate acid etching solution, and only retain the ITO film under the photoresist. ITO glass is conductive glass (In2O3 and SnO2). The ITO film not covered by photoresist is easy to react with acid, while the ITO film covered by photoresist can be retained to obtain the corresponding wire electrode.

Stripping: High concentration of alkali solution (NaOH solution) is used as a stripping solution to peel off the remaining photoresist on the glass so that ITO glass can form ITO graphics exactly consistent with the photolithography mask.

Rinse the basic label of glass with an organic solution and remove the photolithographic tape after reaction to keep the glass clean. This completes the first thin-film conductive crystal process, which generally requires at least five identical processes to form a complex and sophisticated pattern of electrodes on the glass.

This completes the previous Array process. It is not difficult to see from the whole process that ITO film is deposited, photoresist coated, exposed, developed, and etched on TFT glass, and finally, ITO electrode pattern designed in the early stage is formed on TFT glass to control the movement of LCD molecules on the glass. The general steps of the whole production process are not complicated, but the technical details and precautions are very complicated, so we will not introduce them here. Interested friends can consult relevant materials by themselves.

The glass that the LCD board uses makes a craft also very exquisite. (The manufacturing process flow of the LCD display screen)At present, the world’s largest LCD panel glass, mainly by the United States Corning, Japan Asahi glass manufacturers, located in the upstream of the production of LCD panel, these manufacturers have mastered the glass production technology patents. A few months ago, the earthquake caused a corning glass furnace shutdown incident, which has caused a certain impact on the LCD panel industry, you can see its position in the industry.

As mentioned earlier, the LCD panel is structured like a sandwich, with an LCD sandwiched between the lower TFT glass and the upper color filter. The terminal Cell process in LCD panel manufacturing involves the TFT glass being glued to the top and bottom of a colored filter, but this is not a simple bonding process that requires a lot of technical detail.

As you can see from the figure above, the glass is divided into 6 pieces of the same size. In other words, the LCD made from this glass is finally cut into 6 pieces, and the size of each piece is the final size. When the glass is cast, the specifications and sizes of each glass have been designed in advance.

Then, the organic polymer directional material is coated on the surface of the glass, that is, a uniform directional layer is applied to the appropriate position of ITO glass by the method of selective coating. Meanwhile, the directional layer is cured.

Directional friction:Flannelette material is used to rub the surface of the layer in a specific direction so that the LCD molecules can be arranged along the friction direction of the aligned layer in the future to ensure the consistency of the arrangement of LCD molecules. After the alignment friction, there will be some contaminants such as flannelette thread, which need to be washed away through a special cleaning process.

After the TFT glass substrate is cleaned, a sealant coating is applied to allow the TFT glass substrate to be bonded to the color filter and to prevent LCD outflow.

Finally, the conductive adhesive is applied to the frame in the bonding direction of the glass of the color filter to ensure that external electrons can flow into the LCD layer. Then, according to the bonding mark on the TFT glass substrate and the color filter, two pieces of glass are bonded together, and the bonding material is solidified at high temperatures to make the upper and lower glasses fit statically.

Color filters are very important components of LCD panels. Manufacturers of color filters, like glass substrate manufacturers, are upstream of LCD panel manufacturers. Their oversupply or undersupply can directly affect the production schedule of LCD panels and indirectly affect the end market.

Finally, a polarizer is placed on both sides of each LCD substrate, with the horizontal polarizer facing outwards and the vertical polarizer facing inwards.

A polarizer is an optical plate that allows only light from a certain direction to pass through. It is an optical element that converts natural light into straight polarized light. The mechanism of action is to make the vertical direction light pass through the straight incident light after passing through the vertical polarizer, and the other horizontal direction light is absorbed, or use reflection and scattering and other effects to make its shade.

When making LCD panel, must up and down each use one, and presents the alternating direction, when has the electric field and does not have the electric field, causes the light to produce the phase difference and to present the light and dark state, uses in the display subtitle or the pattern.

The rear Module manufacturing process is mainly the integration of the drive IC pressing of the LCD substrate and the printed circuit board. This part can transmit the display signal received from the main control circuit to the drive IC to drive the LCD molecules to rotate and display the image. In addition, the backlight part will be integrated with the LCD substrate at this stage, and the complete LCD panel is completed.

Next is the drive IC press. The main function of the drive IC is to output the required voltage to each pixel and control the degree of torsion of the LCD molecules. The drive IC is divided into two types. The source drive IC located in the X-axis is responsible for the input of data. It is characterized by high frequency and has an image function. The gate drive IC located in the Y-axis is responsible for the degree and speed of torsion of LCD molecules, which directly affects the response time of the LCD display. However, there are already many LCD panels that only have driving IC in the X-axis direction, perhaps because the Y-axis drive IC function has been integrated and simplified.

The press of the flexible circuit board can transmit data signals and act as the bridge between the external printed circuit and LCD. It can be bent and thus becomes a flexible or flexible circuit board

The manufacturing process of the LCD substrate still has a lot of details and matters needing attention, for example, rinse with clean, dry, dry, dry, ultrasonic cleaning, exposure, development and so on and so on, all have very strict technical details and requirements, so as to produce qualified eyes panel, interested friends can consult relevant technical information by a search engine.

LCD (LC) is a kind of LCD, which has the properties of light transmission and refraction of solid Crystal, as well as the flow property of Liquid. It is because of this property that it will be applied to the display field.

However, LCD does not emit light autonomously, so the display equipment using LCD as the display medium needs to be equipped with another backlight system.

First, a backplate is needed as the carrier of the light source. The common light source for LCD display equipment is CCFL cold cathode backlight, but it has started to switch to an LED backlight, but either one needs a backplate as the carrier.

CCFL backlight has been with LCD for a long time. Compared with LED backlight, CCFL backlight has many defects. However, it has gradually evolved to save 50% of the lamp and enhance the transmittance of the LCD panel, so as to achieve the purpose of energy-saving.

With the rapid development of LED in the field of lighting, the cost has been greatly reduced.LCD panels have also started to use LED as the backlight on a large scale. Currently, in order to control costs, an LED backlight is placed on the side rather than on the backplate, which can reduce the number of LED grains.

However, no matter CCFL backlight or LED backlight is placed in various ways, the nature of the backlight source cannot be a surface light source, but a linear light source or point light source. Therefore, other components are needed to evenly distribute the light to the whole surface. This task is accomplished by the diffuser plate and diffuser plate.

On the transparent diffuser plate, point-like printing can block part of the light. The LED backlight on the side drives the light from the side of the diffuser plate, and the light reflects and refracts back and forth in the diffuser plate, distributing the light evenly to the whole surface. Point-like printing blocks part of the light, screening the light evenly like a sieve.

At the top of the diffusion plate, there will be 3~4 diffuser pieces, constantly uniform light to the whole surface, improve the uniformity of light, which is directly related to the LCD panel display effect. Professional LCD in order to better control the brightness uniformity of the screen, panel procurement, the later backlight control circuit, will make great efforts to ensure the quality of the panel.

The backlight system also includes a backlight module laminator, located behind the backplane. In the CCFL backlight era, you can often see the long strip laminator like the one above, with each coil responsible for a set of tubes.

However, it is much simpler to use a side white LED as a backlight. The small circuit board on the far left of the figure above is the backlight of the LED.

This is the general structure of the backlight system. Since I have never seen the backlight mode of R.G.B LED, I cannot tell you what the backlight mode is like. I will share it with you when I see it in the future.

After the period of the Module, the process is completed in LCM (LCDModule) factory, the core of this part of the basic does not involve the use of LCD manufacturing technology, mainly is some assembly work, so some machine panel factories such as chi mei, Korea department such as Samsung panel factory, all set with LCM factories in mainland China, Duan Mo group after the LCD panel assembly, so that we can convenient mainland area each big monitor procurement contract with LCD TV manufacturers, can reduce the human in the whole manufacturing and transportation costs.

A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technologyactive matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.

In February 1957, John Wallmark of RCA filed a patent for a thin film MOSFET. Paul K. Weimer, also of RCA implemented Wallmark"s ideas and developed the thin-film transistor (TFT) in 1962, a type of MOSFET distinct from the standard bulk MOSFET. It was made with thin films of cadmium selenide and cadmium sulfide. The idea of a TFT-based liquid-crystal display (LCD) was conceived by Bernard Lechner of RCA Laboratories in 1968. In 1971, Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated a 2-by-18 matrix display driven by a hybrid circuit using the dynamic scattering mode of LCDs.T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories developed a CdSe (cadmium selenide) TFT, which they used to demonstrate the first CdSe thin-film-transistor liquid-crystal display (TFT LCD).active-matrix liquid-crystal display (AM LCD) using CdSe TFTs in 1974, and then Brody coined the term "active matrix" in 1975.high-resolution and high-quality electronic visual display devices use TFT-based active matrix displays.

The liquid crystal displays used in calculators and other devices with similarly simple displays have direct-driven image elements, and therefore a voltage can be easily applied across just one segment of these types of displays without interfering with the other segments. This would be impractical for a large display, because it would have a large number of (color) picture elements (pixels), and thus it would require millions of connections, both top and bottom for each one of the three colors (red, green and blue) of every pixel. To avoid this issue, the pixels are addressed in rows and columns, reducing the connection count from millions down to thousands. The column and row wires attach to transistor switches, one for each pixel. The one-way current passing characteristic of the transistor prevents the charge that is being applied to each pixel from being drained between refreshes to a display"s image. Each pixel is a small capacitor with a layer of insulating liquid crystal sandwiched between transparent conductive ITO layers.

The circuit layout process of a TFT-LCD is very similar to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Modern, high end consumer products have developed methods to overcome the technology"s shortcomings, such as RTC (Response Time Compensation / Overdrive) technologies. Modern TN displays can look significantly better than older TN displays from decades earlier, but overall TN has inferior viewing angles and poor color in comparison to other technology.

Most TN panels can represent colors using only six bits per RGB channel, or 18 bit in total, and are unable to display the 16.7 million color shades (24-bit truecolor) that are available using 24-bit color. Instead, these panels display interpolated 24-bit color using a dithering method that combines adjacent pixels to simulate the desired shade. They can also use a form of temporal dithering called Frame Rate Control (FRC), which cycles between different shades with each new frame to simulate an intermediate shade. Such 18 bit panels with dithering are sometimes advertised as having "16.2 million colors". These color simulation methods are noticeable to many people and highly bothersome to some.gamut (often referred to as a percentage of the NTSC 1953 color gamut) are also due to backlighting technology. It is not uncommon for older displays to range from 10% to 26% of the NTSC color gamut, whereas other kind of displays, utilizing more complicated CCFL or LED phosphor formulations or RGB LED backlights, may extend past 100% of the NTSC color gamut, a difference quite perceivable by the human eye.

The transmittance of a pixel of an LCD panel typically does not change linearly with the applied voltage,sRGB standard for computer monitors requires a specific nonlinear dependence of the amount of emitted light as a function of the RGB value.

In-plane switching was developed by Hitachi Ltd. in 1996 to improve on the poor viewing angle and the poor color reproduction of TN panels at that time.

Initial iterations of IPS technology were characterised by slow response time and a low contrast ratio but later revisions have made marked improvements to these shortcomings. Because of its wide viewing angle and accurate color reproduction (with almost no off-angle color shift), IPS is widely employed in high-end monitors aimed at professional graphic artists, although with the recent fall in price it has been seen in the mainstream market as well. IPS technology was sold to Panasonic by Hitachi.

Most panels also support true 8-bit per channel color. These improvements came at the cost of a higher response time, initially about 50 ms. IPS panels were also extremely expensive.

IPS has since been superseded by S-IPS (Super-IPS, Hitachi Ltd. in 1998), which has all the benefits of IPS technology with the addition of improved pixel refresh timing.

In 2004, Hydis Technologies Co., Ltd licensed its AFFS patent to Japan"s Hitachi Displays. Hitachi is using AFFS to manufacture high end panels in their product line. In 2006, Hydis also licensed its AFFS to Sanyo Epson Imaging Devices Corporation.

It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction.Response Time Compensation) technologies.

Less expensive PVA panels often use dithering and FRC, whereas super-PVA (S-PVA) panels all use at least 8 bits per color component and do not use color simulation methods.BRAVIA LCD TVs offer 10-bit and xvYCC color support, for example, the Bravia X4500 series. S-PVA also offers fast response times using modern RTC technologies.

When the field is on, the liquid crystal molecules start to tilt towards the center of the sub-pixels because of the electric field; as a result, a continuous pinwheel alignment (CPA) is formed; the azimuthal angle rotates 360 degrees continuously resulting in an excellent viewing angle. The ASV mode is also called CPA mode.

A technology developed by Samsung is Super PLS, which bears similarities to IPS panels, has wider viewing angles, better image quality, increased brightness, and lower production costs. PLS technology debuted in the PC display market with the release of the Samsung S27A850 and S24A850 monitors in September 2011.

TFT dual-transistor pixel or cell technology is a reflective-display technology for use in very-low-power-consumption applications such as electronic shelf labels (ESL), digital watches, or metering. DTP involves adding a secondary transistor gate in the single TFT cell to maintain the display of a pixel during a period of 1s without loss of image or without degrading the TFT transistors over time. By slowing the refresh rate of the standard frequency from 60 Hz to 1 Hz, DTP claims to increase the power efficiency by multiple orders of magnitude.

Due to the very high cost of building TFT factories, there are few major OEM panel vendors for large display panels. The glass panel suppliers are as follows:

External consumer display devices like a TFT LCD feature one or more analog VGA, DVI, HDMI, or DisplayPort interface, with many featuring a selection of these interfaces. Inside external display devices there is a controller board that will convert the video signal using color mapping and image scaling usually employing the discrete cosine transform (DCT) in order to convert any video source like CVBS, VGA, DVI, HDMI, etc. into digital RGB at the native resolution of the display panel. In a laptop the graphics chip will directly produce a signal suitable for connection to the built-in TFT display. A control mechanism for the backlight is usually included on the same controller board.

The low level interface of STN, DSTN, or TFT display panels use either single ended TTL 5 V signal for older displays or TTL 3.3 V for slightly newer displays that transmits the pixel clock, horizontal sync, vertical sync, digital red, digital green, digital blue in parallel. Some models (for example the AT070TN92) also feature input/display enable, horizontal scan direction and vertical scan direction signals.

New and large (>15") TFT displays often use LVDS signaling that transmits the same contents as the parallel interface (Hsync, Vsync, RGB) but will put control and RGB bits into a number of serial transmission lines synchronized to a clock whose rate is equal to the pixel rate. LVDS transmits seven bits per clock per data line, with six bits being data and one bit used to signal if the other six bits need to be inverted in order to maintain DC balance. Low-cost TFT displays often have three data lines and therefore only directly support 18 bits per pixel. Upscale displays have four or five data lines to support 24 bits per pixel (truecolor) or 30 bits per pixel respectively. Panel manufacturers are slowly replacing LVDS with Internal DisplayPort and Embedded DisplayPort, which allow sixfold reduction of the number of differential pairs.

Backlight intensity is usually controlled by varying a few volts DC, or generating a PWM signal, or adjusting a potentiometer or simply fixed. This in turn controls a high-voltage (1.3 kV) DC-AC inverter or a matrix of LEDs. The method to control the intensity of LED is to pulse them with PWM which can be source of harmonic flicker.

The bare display panel will only accept a digital video signal at the resolution determined by the panel pixel matrix designed at manufacture. Some screen panels will ignore the LSB bits of the color information to present a consistent interface (8 bit -> 6 bit/color x3).

With analogue signals like VGA, the display controller also needs to perform a high speed analog to digital conversion. With digital input signals like DVI or HDMI some simple reordering of the bits is needed before feeding it to the rescaler if the input resolution doesn"t match the display panel resolution.

The statements are applicable to Merck KGaA as well as its competitors JNC Corporation (formerly Chisso Corporation) and DIC (formerly Dainippon Ink & Chemicals). All three manufacturers have agreed not to introduce any acutely toxic or mutagenic liquid crystals to the market. They cover more than 90 percent of the global liquid crystal market. The remaining market share of liquid crystals, produced primarily in China, consists of older, patent-free substances from the three leading world producers and have already been tested for toxicity by them. As a result, they can also be considered non-toxic.

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K. H. Lee; H. Y. Kim; K. H. Park; S. J. Jang; I. C. Park & J. Y. Lee (June 2006). "A Novel Outdoor Readability of Portable TFT-LCD with AFFS Technology". SID Symposium Digest of Technical Papers. AIP. 37 (1): 1079–82. doi:10.1889/1.2433159. S2CID 129569963.

Kim, Sae-Bom; Kim, Woong-Ki; Chounlamany, Vanseng; Seo, Jaehwan; Yoo, Jisu; Jo, Hun-Je; Jung, Jinho (15 August 2012). "Identification of multi-level toxicity of liquid crystal display wastewater toward Daphnia magna and Moina macrocopa". Journal of Hazardous Materials. Seoul, Korea; Laos, Lao. 227–228: 327–333. doi:10.1016/j.jhazmat.2012.05.059. PMID 22677053.

When compared to the ordinary LCD, TFT LCD gives very sharp and crisp picture/text with shorter response time. TFT LCD displays are used in more and more applications, giving products better visual presentation.

TFT is an abbreviation for "Thin Film Transistor". The colorTFT LCD display has transistors made up of thin films of Amorphous silicon deposited on a glass. It serves as a control valve to provide an appropriate voltage onto liquid crystals for individual sub-pixels. That is why TFT LCD display is also called Active Matrix display.

A TFT LCD has a liquid crystal layer between a glass substrate formed with TFTs and transparent pixel electrodes and another glass substrate with a color filter (RGB) and transparent counter electrodes. Each pixel in an active matrix is paired with a transistor that includes capacitor which gives each sub-pixel the ability to retain its charge, instead of requiring an electrical charge sent each time it needed to be changed. This means that TFT LCD displays are more responsive.

To understand how TFT LCD works, we first need to grasp the concept of field-effect transistor (FET). FET is a type of transistor which uses electric field to control the flow of electrical current. It is a component with three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.

Using FET, we can build a circuit as below. Data Bus sends signal to FET Source, when SEL SIGNAL applies voltage to the Gate, driving voltage is then created on TFT LCD panel. A sub-pixel will be lit up. A TFT LCD display contains thousand or million of such driving circuits.

Topway started TFT LCD manufacturing more than15 years ago. We produce color TFT LCD display from 1.8 to 15+ inches with different resolutions and interfaces. Here is some more readings about how to choose the right TFT LCD.

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Improve your product design by adding the DT010ATFT: a small, simple 1” TFT LCD with IPS technology. This mini TFT display is perfect as a status indicator presenting graphic icons or simplified information. The IPS technology included in this display allows your content to be crisp and clear no matter what angle your user is viewing it from. The ST7735S driver IC provides on-chip storage and power system. This IC allows for fewer components and a simple design to easily integrate the DT010ATFT into your next product.

TFT-LCD technology is based on semiconductor IC manufacturing processes, and is unique in that it uses glass substrates rather than traditional silicon wafers. For the TFT manufacturing process, thin film formation, such as CVD and PVD processes, is a very important part. The ODF process has been developed for the assembly of color filters and TFT substrates, and is used in large size LCDs.

First of all, the movement and arrangement of liquid crystal molecules need electrons to drive, so in the carrier of liquid crystal – TFT glass, there must be able to conduct the part to control the movement of liquid crystal, here will use ITO (Indium TIn Oxide, transparent conductive metal) to do this thing. ITO is transparent, also known as thin film conductive crystal so that it will not block the backlight.

The different arrangement of liquid crystal molecules and the rapid movement changes to ensure that each pixel accurately display the corresponding color, and the image changes precisely and quickly, which requires precision control of the liquid crystal molecules. ITO film requires special processing, as if printed circuitry on a PCB board, drawing conductive lines throughout the LCD board.

For array panels with back-channel etched TFT structure.The main process can be divided into 5 steps (5 lightings) according to the sequence of the layers to be made and the interrelationship between the layers.

The process includes: Gate layer metal sputtering, Gate lithography, Gate wet lithography, and other processes. After these processes, scan lines and gate electrodes are formed on the glass substrate, i.e. gate electrodes. The graphical representation of the completed process is shown in the following figure.

Photolithography is the process of copying Mask graphic structures onto the glass substrate to be etched. There are three main processes: photoresist coating, exposure, and development

Dry lithography: The chemical reaction between the process gas and the film, as well as the bombardment of the film by the plasma, is used to remove the film layer.

The process includes: PECVD triple layer continuous film formation, island lithography, island dry lithography and other processes. After these processes, the final amorphous silicon island for TFT is formed on the glass substrate. The graphics obtained after the process is completed are shown in the following figure.

Specific processes include: S/D metal layer sputtering into a film, S/D lithography, S/D wet lithography, channel dry lithography and other processes. After these processes, the source, drain, channel and data lines of the TFT are finally formed on the glass substrate. At this point, the TFT has been produced. The graphics obtained after the process is completed are shown in the following figure.

The process includes PECVD, photolithography, and dry lithography of vias. After these processes, the final TFT channel protective insulation layer and guide through the hole are formed on the glass substrate. The graphics obtained after the process is completed are shown in the following figure.

Specifically, the process includes: sputtering of ITO transparent electrode layer, ITO photolithography, ITO wet lithography and other processes. After these processes, the transparent pixel electrode is finally formed on the glass substrate. The graphics obtained after the process is completed are shown in the following figure.

At this point, the whole array process is completed. In short, the array process of 5 times of light is: 5 times of film formation + 5 times of etching

Color filters can be produced by various methods; photolithography is a typical method. In photolithography, color filters are produced by exposing a glass substrate coated with a photographic color resist through a photomask. The resist is hardened to form the RGB pattern of the LCD.

The middle section of the cell is a combination of the front Array glass as the substrate and the color filter glass substrate, and the liquid crystal (LC) is injected between the two glass substrates.

Rubbing the PI film on top of the glass substrate by using the alignment cloth hairs to create grooves for liquid crystal orientation, so that the liquid crystal is neatly aligned between the upper and lower alignment films in the direction specified.

Pre-Tilt Angle (Pre-TIlt Angle or TBA: Tilt Bias Angle) characteristic refers to the arrangement of liquid crystal molecules on the mating film is not parallel to the film surface, but one end of the molecule in the friction direction relative to the film surface has a certain warp, the stilt angle is called pre-tilt angle. If there is no pre-tilt angle, under the external electric field, the liquid crystal molecules can stand up randomly from two directions, which will cause poor display.

After that is bonding IC and FPC; assembling backlight module, the whole machine shell and other processes, relative to the front of the high-precision process to be simpler.

COG (Chip on Glass) and FPC (Flexible Printed Circuit) is a circuit connection method. Due to the many electrodes, one-to-one lining connection is very difficult. Nowadays, the common practice is to make an array of leads on the glass and a corresponding array of leads on the IC/FPC, and to connect the electrodes on the IC/FPC to the electrodes on the glass one-to-one through an anisotropic conductive film (ACF). The schematic diagram of the lead electrode array on the glass is as follows.

Assembly is the combination of backlight, screen, control circuit board, and touch screen and other components together to form a complete display module. Assembly is generally done by hand, and skilled workers are very important here.

Although we are not process processing personnel, but we still need to understand the relevant things, because in the interface with other departments or personnel in order to be more comfortable. Problems can be considered in many aspects, if you do not know the process related knowledge, encounter problems simply will not think of here, so the process of understanding or necessary.

Taiwan-based makers shipped a total of 61.37 million large-size (9-inch and above) TFT-LCD panels during the fourth quarter of 2016, decreasing 1.5% on quarter but increasing 2% on...

China Star Optoelectronics Technology (CSOT) in late November 2016 started construction of an 11G LCD factory with monthly production capacity of 140,000 glass substrates in Shenzhen,...

Sakai Display Product"s (Sharp"s subsidiary) 10G using 2,880mm by 3,130mm glass substrates) TFT-LCD factory in Japan is currently one of the highest generation plants but four 10.5G...

AU Optronics (AUO) on November 16 kicked off volume production at a 6G LTPS (low-temperature poly-Si) TFT-LCD factory in Kunshan, eastern China, according to the company.

Taiwan-based makers shipped 62.29 million large-size (9-inch and above) TFT-LCD panels in the third quarter of 2016, increasing 6.7% on quarter and 6.2% on year, and accounting for...

Global shipments of small- to medium-size panels will decrease from 2.647 billion units in 2017 to 2.189 billion units in 2021 or a CAGR of negative 4.6%, according to Digitimes Re...

Taiwan-based TFT-LCD panel makers shipped 309.749 million small- to medium-size panels in the third quarter of 2016, increasing 15.0% on quarter and 0.8% on year, according to Digitimes...

AU Optronics (AUO) will inaugurate a 6G LTPS TFT-LCD factory in Kunshan, eastern China, on November 16 and start production later in the fourth quarter. AUO expects production capacity...

Global production capacity for large-size TFT-LCD panels in 2016 is estimated at 208 million square meters, increasing 6.6% on year, and the capacity will increase 3.9% to 216 million...

Global shipments of large-size (9-inch and above) TFT-LCD panels will slightly increase from 673.37 million units in 2016 to 684.60 million units in 2021, equivalent to an annual...

As Samsung Display, LG Display and Japan Display have shut down mostly 5G to 6G TFT-LCD lines to gradually expand AMOLED production capacity since the beginning of 2015, global shipments...

Taiwan-based TFT-LCD panel makers generated total production value of NT$164.135 billion (US$5.13 billion) in the second quarter of 2016, increasing 1.90% on quarter but decreasing...

Taiwan-based TFT-LCD panel makers AU Optronics (AUO), Innolux and Chunghwa Picture Tubes (CPT), at the Touch Taiwan 2016 taking place in Taipei during August 24-26, showed that they...

LG.Philips LCD began production of seventh-generation TFT LCDs (thin-film transistor liquid crystal displays) at its facility in Paju (Korea) at the beginning of 2006. The ramp up was over six months earlier than previously planned, prompted by increasing demand for LCD TVs and PCs. The expansion made it the world’s largest LCD production facility. Philips made a pilot production run at the end of November 2005, and has started production of 42in panels from its 1,950mm x 2,250mm glass substrates.

The company is investing $10 billion and expects annual sales close to $3 billion, more than 90% of which will be from exports. The 1,650,000m² complex takes the LG.Philips LCD industrial cluster to 3,300,000m², housing next-generation LCD production and R&D facilities. Preparatory work was completed by March 2004.

The fab is located in Paju, Kyonggi Province, north of Seoul. LG.Philips LCD and the Kyonggi provincial government has provided infrastructure including industrial water systems, electricity utilities and roads. The investment has created around 5,000 new jobs.

TFT LCDs have three layers. A glass plate substrate with TFT transistors is at the bottom, a glass plate colour filter on top and the liquid crystal is injected between the two. Although LCDs are fluid, they show long-range order like solids. The molecules are roughly bar shaped but with anisotropic values of reflective index, dielectric constant, conductivity and viscosity: all have different values along different axes.

The transistors apply voltages to the liquid crystals to control the vibration direction of polarized light passing through them. This affects the light permeability of the individual LCD pixels to form images.

TFT-LCD screens are flatter and lighter than CRTs, consume less power and generate lower electromagnetic emissions. Besides going into TV sets for the home, TFT LCDs will be used in monitors for mini notebook PCs and hand-held computers, medical equipment, car navigation and entertainment systems and avionics instrumentation.

Philips has been improving the technical limitations of TFT-LCDs, particularly angle, brightness response time. The company now has 20.1in UXGA, 23in WUXGA and 30in WQXGA+ TFT-LCD panels for large-scale, wide monitor-specific TFT-LCDs for desktop monitors.

The first phase of the factory should reach a production capacity of 45,000 glass sheets/month by Q3 2006. The factory should reach its initial design capacity of 90,000 input sheets/month by Q1 2007.

After first manufacturing 42in TV panels, Philips will gradually increase production of 47in TV screens. It can produce eight 42in panels or six 47in panels from a single glass substrate.

During sputtering, the high-energy gas ions inside the plasma collide with the surface of a (negative) target, knocking out the target materials which are deposited onto the (positive) plate.

Photolithography first coats the substrate with a very thin liquid film of photosensitive ‘resist’. Exposing the photoresist to light through a mask transfers the pattern onto the substrate. This is followed by cleaning. Another layer of the photoresist is then deposited to the substrate, exposed, cleaned, and so on, until all the layers have been printed or imaged onto the surface.

LG.Philips LCD is a 50:50 joint venture between LG Electronics and Philips Electronics. The company produces TFT-LCDs for notebook PCs, desktop monitors, LCD TVs and special applications including car navigation systems, avionics, miniature notebook PCs, hand-held PCs and medical diagnostic machines. Higher value 18in-and-above screens make up more than 20% of LG.Philips LCD’s total TV LCD production.

The company has also invested a total of 3.3 trillion won (just under $2 billion) to build a new sixth-generation TFT-LCD plant in Gumi, south of Seoul. In addition to its Korean facilities, where the core panels are made, LG.Philips LCD has expanded its Nanjing, China, fifth-generation module plant, where it has produced more than one million TFT-LCDs for desktop monitors (module yield is more than 99%). In Nanjing, panels are equipped with other components before being sold to monitor and TV set manufacturers.

The steel bars account for a high percentage of material costs for the current construction projects. At the present time, most of the construction projects for the factories of thin‐film transistor liquid crystal display (TFT‐LCD) complete the transactions of steel bars when the suppliers ship the steel bars to the temporary storage/processing sites. This paper applies the buy‐in concept in the Theory of Constraint (TOC) on the supply chain of steel bars. In this study, suppliers are required to establish warehouses at the construction sites and complete the transactions when the formed and processed steel bars are shipped into the factory sites. The aim is to find a win‐win solution to meet with the expectations from constructors as they hope that there is no need to build up inventories but supply is ready at any time. Also, this paper compares and analyzes the traditional supply/inventory model of steel bars and the Demand‐Pull (D‐P) model under the TOC framework. It is proved that Vendor Management Inventory (VMI) in the D‐P model is able to more effectively manage steel bars as a material.

This graphic display module is a 2.4" diagonal, full color TFT. Suitable for embedded applications, it is low-power, uses a white LED backlight, and has an integrated touch panel which has its connection brought out to the main TAB connector for the display.

It has an on-board controller and 3v single voltage for supply and logic (backlight not included), so you can easily use any modern microcontroller to interface with this display. It uses an 8 or 16 bit parallel interface, specified via connections to the display.

The connector on the CFAF240320K-024T-TS is a flex tail mated with a "COG" (chip on glass) display construction. This style of connector is designed to be soldered directly to corresponding pads on your PCB by using a hot-bar soldering machine. High volume contract manufacturers will be familiar with this type of construction and its assembly methods. There are hot-bar soldering machines made that are designed for prototype, rework or repair work of TAB connections.

In Taiwan.  It was formed in 2001 by the merger of Acer Display Technology Inc and Unipac Optoelectronics Corporation. It has G3.5 to G8.5 production lines.

In Taiwan. One of the daughter company of Foxconn/Hon Hai.  In 2010, it bought the then famous LCD manufacturer, ChiMei, then changed its name to Innolux. It has G7.5 production lines.

In Korea and China. It is used to be the 2nd biggest TFT LCD manufacturers. LG also planned to stop the production but delayed the plan after the price increased. LG has G7.5 and G8.5 (Guangzhou) production lines.

In China. Original Matix is the partner of CPT (Chunghwa Picture Tubes 中华映管). After CPT filed bankruptcy in 2019, Mantix took over CPT G6 production line.

In Korea. It used to be the biggest TFT LCD manufacturers before it was dethroned by BOE in 2019. Because of tough competition, Samsung planned to stop the production in 2021 but delayed because the price increase during the pandemic.  Samsung has G7 and G8.5 production lines.

In Japan and China. The pioneer and queen of LCD industry. Because of high cost and tough competitor, Sharp was acquired by Foxconn/Hon Hai in 2016. Sharp has G8, G8.5(Suzhou), G10, G10.5 (Guangzhou) production lines.

S-LCD Corporation celebrated completed construction of the world"s largest generation 7 amorphous TFT LCD panel production building in Tangjung, South Korea. The "S-LCD Grand Opening Ceremony" was held with approximately 1,000 guests, including government personnel from both Korea and Japan and personnel from related enterprises. A manufacturing equipment move-in event also took place and was broadcasted for the audience in the ceremony. Mass production is expected to start in the first half of 2005 after production testing.

S-LCD Corporation is a joint venture company that was established on April 26th 2004. It is an equal joint investment* by Samsung Electronics Co. Ltd. (hereafter Samsung) and Sony Corporation (hereafter Sony) dedicated to the manufacturing of amorphous TFT LCD panels for LCD TVs. The facility boasts the most advanced manufacturing equipment for 7th generation LCD panels, with a production capacity of 60,000 panels/ month. The facility will operate as a major source for LCD panels to both Samsung and Sony.

The LCD panel production building is composed of 4 floors, with a total floor area of 32,000 m2. The module assembly building with a total floor area of 15,000 m2 is also completed. LCD module production from S-LCD will be customized uniquely for Samsung and Sony, with integration of peripheral devices such as back-light and driving circuitry.

S-LCD Corporation will create a stable supply base for amorphous TFT LCD panels for both Samsung and Sony. Its efficient production output will support the development of LCD TV businesses at both Samsung and Sony.

"The cooperation between Samsung and Sony offers an opportunity to lead the rapidly growing LCD TV market and standardization of glass substrate and LCD TV sizes. It is a win-win situation for both companies. We are committed to developing Tangjung Crystal Valley as the center of the world"s display industry and making the joint venture into a success." said S.W. Lee, President and CEO of Samsung Electronics" LCD Business.

"It is a great pleasure to know that the preparations by S-LCD Corporation are progressing smoothly and both Sony and Samsung have great expectations for the beginning of mass-production next year." said Ken Kutaragi, Executive Deputy President and COO of Sony Corporation. "Television is a key product category for Sony. S-LCD panels will be at the core of our flat panel TV strategy, further strengthening our overall vision for television. There is tremendous potential for expansion in the market for digital TVs, and Sony will apply its unique signal processing technology, device technology and design skills to deliver products that allow customers around the world to enjoy varied contents."

Logic Technologies LCD/TFT Display division controls the design, development, manufacturing, assembly and testing of it’s displays within it’s China-based in-house LCD and touch glass fabrication facilities.

We also use our own products in the DLOGIC Touch Display Computers, providing a minimum 5-10 year supply guarantee, depending on display type and technology.