lcd panel layers made in china

In recent time, China domestic companies like BOE have overtaken LCD manufacturers from Korea and Japan. For the first three quarters of 2020, China LCD companies shipped 97.01 million square meters TFT LCD. And China"s LCD display manufacturers expect to grab 70% global LCD panel shipments very soon.

BOE started LCD manufacturing in 1994, and has grown into the largest LCD manufacturers in the world. Who has the 1st generation 10.5 TFT LCD production line. BOE"s LCD products are widely used in areas like TV, monitor, mobile phone, laptop computer etc.

TianMa Microelectronics is a professional LCD and LCM manufacturer. The company owns generation 4.5 TFT LCD production lines, mainly focuses on making medium to small size LCD product. TianMa works on consult, design and manufacturing of LCD display. Its LCDs are used in medical, instrument, telecommunication and auto industries.

TCL CSOT (TCL China Star Optoelectronics Technology Co., Ltd), established in November, 2009. TCL has six LCD panel production lines commissioned, providing panels and modules for TV and mobile products. The products range from large, small & medium display panel and touch modules.

Established in 1996, Topway is a high-tech enterprise specializing in the design and manufacturing of industrial LCD module. Topway"s TFT LCD displays are known worldwide for their flexible use, reliable quality and reliable support. More than 20 years expertise coupled with longevity of LCD modules make Topway a trustworthy partner for decades. CMRC (market research institution belonged to Statistics China before) named Topway one of the top 10 LCD manufactures in China.

The Company engages in the R&D, manufacturing, and sale of LCD panels. It offers LCD panels for notebook computers, desktop computer monitors, LCD TV sets, vehicle-mounted IPC, consumer electronics products, mobile devices, tablet PCs, desktop PCs, and industrial displays.

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.

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.

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.

As can be seen from the above figure, each LCD panel is left with two edges after cutting. What is it used for? You can find the answer in the later module process

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

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.

Firstly, the heteroconductive adhesive is pressed on the two edges, which allows external electrons to enter the LCD substrate layer and acts as a bridge for electronic transmission

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.

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.

Since the LCD substrate and the backlight system are not fixed by bonding, a metal or rubber frame is needed to be added to the outer layer to fix the LCD substrate and the backlight system.

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.

However, neither Taiwan nor Korea has any intention to set up factories in mainland China for the LCD panel front and middle manufacturing process involving core technologies. Therefore, there is still a long way to go for China to have its own LCD panel industry.

Samsung Display is ending direct production of LCD panels in South Korea and China by the end of this year, according to a report by the global news agency Reuters.

Samsung’s gorgeous QLED displays (got one) are LCDs with a quantum dots layer, and there is lots of R&D work going on to add quantum dots to OLED displays, which would boost their brightness and color volume as well.

The investment for the next five years will be focused on converting one of its South Korean LCD lines into a facility to mass produce more advanced “quantum dot” screens.

Samsung Display’s cross-town rival LG Display Co Ltd said earlier this year that it will halt domestic production of LCD TV panels by the end of 2020.

This is happening, maybe not entirely but heavily, because Chinese government-backed manufacturers like BOE have greatly upped production capacity for LCD TVs, driving prices  and margins down for consumer and professional display products.

Samsung Display reportedly plans to shut down ahead of schedule four of its LCD panel production lines as early as in the third quarter of 2020, as the vendor is looking to accelerate its exit from the LCD segment, according to industry sources.

The ongoing coronavirus pandemic is apparently an impetus pushing Samsung Display to phase out its LCD panel production, as the crisis has wrecked havoc on the global economy, slowing down business activities and halting sports events such as the Tokyo Olympics 2020, which is seriously undercutting demand for TVs and adding downward pressure on panel prices, said the sources.

Samsung Display also plans to keep production at its 8.5G LCD fab in Suzhou, China in the meantime, while overhauling its L7-2 fab for production of POLED panels and its L8 fab for QD-OLED panels, indicated the sources.

The Korean panel maker is also looking to halt the operations of the Suzhou 8.5G line by the third quarter of 2022 and is currently in talks to sell the LCD panel plant to Chinese panel makers, said the sources, adding that the completion of a deal will mark Samsung Display ‘s exit from the LCD TV panel market.

Meanwhile, TV panel prices, which have been trending upward recently along with reduced production caused by the pandemic, are expected to stay flat in April, as capacity resumption of most panel plants in China is expected to reach over 90% in the month, while TV brands are likely to slow down their panel purchases amid pandemic-induced uncertainty, commented the sources.

Presumably, while Samsung may not be directly manufacturing LCD, the industry will still be able to buy Samsung LCD displays – just manufactured, as some will be already, by other companies in China and Taiwan.

I really don’t see direct view LED taking the place of single LCD displays, but much of the future of signage is in LED that fills entire walls and other surfaces, inside and outside.

Samsung Display will stop producing LCD panels by the end of the year. The display maker currently runs two LCD production lines in South Korea and two in China, according to Reuters. Samsung tells The Verge that the decision will accelerate the company’s move towards quantum dot displays, while ZDNetreports that its future quantum dot TVs will use OLED rather than LCD panels.

The decision comes as LCD panel prices are said to be falling worldwide. Last year, Nikkei reported that Chinese competitors are ramping up production of LCD screens, even as demand for TVs weakens globally. Samsung Display isn’t the only manufacturer to have closed down LCD production lines. LG Display announced it would be ending LCD production in South Korea by the end of the 2020 as well.

Last October Samsung Display announced a five-year 13.1 trillion won (around $10.7 billion) investment in quantum dot technology for its upcoming TVs, as it shifts production away from LCDs. However, Samsung’s existing quantum dot or QLED TVs still use LCD panels behind their quantum dot layer. Samsung is also working on developing self-emissive quantum-dot diodes, which would remove the need for a separate layer.

Samsung’s investment in OLED TVs has also been reported by The Elec. The company is no stranger to OLED technology for handhelds, but it exited the large OLED panel market half a decade ago, allowing rival LG Display to dominate ever since.

Although Samsung Display says that it will be able to continue supplying its existing LCD orders through the end of the year, there are questions about what Samsung Electronics, the largest TV manufacturer in the world, will use in its LCD TVs going forward. Samsung told The Vergethat it does not expect the shutdown to affect its LCD-based QLED TV lineup. So for the near-term, nothing changes.

One alternative is that Samsung buys its LCD panels from suppliers like TCL-owned CSOT and AUO, which already supply panels for Samsung TVs. Last year The Elec reported that Samsung could close all its South Korean LCD production lines, and make up the difference with panels bought from Chinese manufacturers like CSOT, which Samsung Display has invested in.

Flat-panel displays are thin panels of glass or plastic used for electronically displaying text, images, or video. Liquid crystal displays (LCD), OLED (organic light emitting diode) and microLED displays are not quite the same; since LCD uses a liquid crystal that reacts to an electric current blocking light or allowing it to pass through the panel, whereas OLED/microLED displays consist of electroluminescent organic/inorganic materials that generate light when a current is passed through the material. LCD, OLED and microLED displays are driven using LTPS, IGZO, LTPO, and A-Si TFT transistor technologies as their backplane using ITO to supply current to the transistors and in turn to the liquid crystal or electroluminescent material. Segment and passive OLED and LCD displays do not use a backplane but use indium tin oxide (ITO), a transparent conductive material, to pass current to the electroluminescent material or liquid crystal. In LCDs, there is an even layer of liquid crystal throughout the panel whereas an OLED display has the electroluminescent material only where it is meant to light up. OLEDs, LCDs and microLEDs can be made flexible and transparent, but LCDs require a backlight because they cannot emit light on their own like OLEDs and microLEDs.

Liquid-crystal display (or LCD) is a thin, flat panel used for electronically displaying information such as text, images, and moving pictures. They are usually made of glass but they can also be made out of plastic. Some manufacturers make transparent LCD panels and special sequential color segment LCDs that have higher than usual refresh rates and an RGB backlight. The backlight is synchronized with the display so that the colors will show up as needed. The list of LCD manufacturers:

Organic light emitting diode (or OLED displays) is a thin, flat panel made of glass or plastic used for electronically displaying information such as text, images, and moving pictures. OLED panels can also take the shape of a light panel, where red, green and blue light emitting materials are stacked to create a white light panel. OLED displays can also be made transparent and/or flexible and these transparent panels are available on the market and are widely used in smartphones with under-display optical fingerprint sensors. LCD and OLED displays are available in different shapes, the most prominent of which is a circular display, which is used in smartwatches. The list of OLED display manufacturers:

MicroLED displays is an emerging flat-panel display technology consisting of arrays of microscopic LEDs forming the individual pixel elements. Like OLED, microLED offers infinite contrast ratio, but unlike OLED, microLED is immune to screen burn-in, and consumes less power while having higher light output, as it uses LEDs instead of organic electroluminescent materials, The list of MicroLED display manufacturers:

LCDs are made in a glass substrate. For OLED, the substrate can also be plastic. The size of the substrates are specified in generations, with each generation using a larger substrate. For example, a 4th generation substrate is larger in size than a 3rd generation substrate. A larger substrate allows for more panels to be cut from a single substrate, or for larger panels to be made, akin to increasing wafer sizes in the semiconductor industry.

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One of the industry’s leading oxide panel makers selected Astra Glass as its backplane glass substrate because it has the inherent fidelity to thrive in high-temperature oxide-TFT glass fabrication for immersive high-performance displays.

One of the industry’s leading oxide panel makers selected Astra Glass as its backplane glass substrate because it has the inherent fidelity to thrive in high-temperature oxide-TFT glass fabrication for immersive high-performance displays.

Caihong Display Devices plans to spend CNY2.3 billion (USD348 million) expanding its capacity to make liquid crystal display panels, an investment the Chinese manufacturer expects to generate an extra CNY2.1 billion in operating income each year.

The investment will complete Caihong’s aim of expanding capacity to 170,000 panels a month from 132,000 at the plant at its Xianyang base in China’s northwestern province of Shaanxi, the company said in a statement.

Caihong, whose customers include smartphone makers Samsung and Xiaomi, is experienced at enlarging output capacity, with its 8.6-generation production line forThin Film Transistor-Liquid Crystal Displaypanelshaving come onstream at the end of 2017, the firm added.

As the current mainstream technology for flat panel display devices, TFT-LCD is widely used in electronic products. The total area of TFT-LCD panels sold worldwide rose to 214 million square meters in 2019 from 162 million sqm in 2014, and is set to grow to 255 million sqm by 2024, Caihong said, citing a report by Chinese market researcher Cinno Research.

Founded in 1992, Caihong was the first maker of TV color picture tubes in China. With the continuous upgrading of display panel technology, Caihong has transformed into an LCD panel producer in recent years, offering TFT-LCD andActive Matrix Organic Light Emitting Diodes, orAMOLED, products.

Touch panel technologies are a key theme in current digital devices, including smartphones, slate devices like the iPad, the screens on the backs of digital cameras, the Nintendo DS, and Windows 7 devices. The term touch panel encompasses various technologies for sensing the touch of a finger or stylus. In this session, we"ll look at basic touch panel sensing methods and introduce the characteristics and optimal applications of each.

Note: Below is the translation from the Japanese of the ITmedia article "How Can a Screen Sense Touch? A Basic Understanding of Touch Panels"published September 27, 2010. Copyright 2011 ITmedia Inc. All Rights Reserved.

A touch panel is a piece of equipment that lets users interact with a computer by touching the screen directly. Incorporating features into the monitor like sensors that detect touch actions makes it possible to issue instructions to a computer by having it sense the position of a finger or stylus. Essentially, it becomes a device fusing the two functions of display and input.

It"s perhaps not something we think of often, but touch panels have integrated themselves into every aspect of our lives. People who enjoy using digital devices like smartphones interact with touch panels all the time in everyday life—but so do others, at devices like bank ATMs, ticket vending machines in railway stations, electronic kiosks inside convenience stores, digital photo printers at mass merchandisers, library information terminals, photocopiers, and car navigation systems.

A major factor driving the spread of touch panels is the benefits they offer in the way of intuitive operation. Since they can be used for input through direct contact with icons and buttons, they"re easy to understand and easily used, even by people unaccustomed to using computers. Touch panels also contribute to miniaturization and simplification of devices by combining display and input into a single piece of equipment. Since touch panel buttons are software, not hardware, their interfaces are easily changed through software.

While a touch panel requires a wide range of characteristics, including display visibility above all, along with precision in position sensing, rapid response to input, durability, and installation costs, their characteristics differ greatly depending on the methods used to sense touch input. Some typical touch-panel sensing methods are discussed below.

As of 2010, resistive film represented the most widely used sensing method in the touch panel market. Touch panels based on this method are called pressure-sensitive or analog-resistive film touch panels. In addition to standalone LCD monitors, this technology is used in a wide range of small to mid-sized devices, including smartphones, mobile phones, PDAs, car navigation systems, and the Nintendo DS.

Drawbacks include lower light transmittance (reduced display quality) due to the film and two electrode layers; relatively lower durability and shock resistance; and reduced precision of detection with larger screen sizes. (Precision can be maintained in other ways—for example, splitting the screen into multiple areas for detection.)

Capacitive touch panels represent the second most widely used sensing method after resistive film touch panels. Corresponding to the terms used for the above analog resistive touch panels, these also are called analog capacitive touch panels. Aside from standalone LCD monitors, these are often used in the same devices with resistive film touch panels, such as smartphones and mobile phones.

Two types of touch panels use this method: surface capacitive touch panels and projective capacitive touch panels. The internal structures differ between the two types.

Surface capacitive touch panels are often used in relatively large panels. Inside these panels, a transparent electrode film (electrode layer) is placed atop a glass substrate, covered by a protective cover. Electric voltage is applied to electrodes positioned in the four corners of the glass substrate, generating a uniform low-voltage electrical field across the entire panel. The coordinates of the position at which the finger touches the screen are identified by measuring the resulting changes in electrostatic capacity at the four corners of the panel.

While this type of capacitive touch panel has a simpler structure than a projected capacitive touch panel and for this reason offers lower cost, it is structurally difficult to detect contact at two or more points at the same time (multi-touch).

Projected capacitive touch panels are often used for smaller screen sizes than surface capacitive touch panels. They"ve attracted significant attention in mobile devices. The iPhone, iPod Touch, and iPad use this method to achieve high-precision multi-touch functionality and high response speed.

The internal structure of these touch panels consists of a substrate incorporating an IC chip for processing computations, over which is a layer of numerous transparent electrodes is positioned in specific patterns. The surface is covered with an insulating glass or plastic cover. When a finger approaches the surface, electrostatic capacity among multiple electrodes changes simultaneously, and the position were contact occurs can be identified precisely by measuring the ratios between these electrical currents.

A unique characteristic of a projected capacitive touch panel is the fact that the large number of electrodes enables accurate detection of contact at multiple points (multi-touch). However, the projected capacitive touch panels featuring indium-tin-oxide (ITO) found in smartphones and similar devices are poorly suited for use in large screens, since increased screen size results in increased resistance (i.e., slower transmission of electrical current), increasing the amount of error and noise in detecting the points touched.

Larger touch panels use center-wire projected capacitive touch panels in which very thin electrical wires are laid out in a grid as a transparent electrode layer. While lower resistance makes center-wire projected capacitive touch panels highly sensitive, they are less suited to mass production than ITO etching.

Above, we"ve summarized the differences between the two types of capacitive touch panels. The overall characteristics of such panels include the fact that unlike resistive film touch panels, they do not respond to touch by clothing or standard styli. They feature strong resistance to dust and water drops and high durability and scratch resistance. In addition, their light transmittance is higher, as compared to resistive film touch panels.

On the other hand, these touch panels require either a finger or a special stylus. They cannot be operated while wearing gloves, and they are susceptible to the effects of nearby metal structures.

Surface acoustic wave (SAW) touch panels were developed mainly to address the drawbacks of low light transmittance in resistive film touch panels—that is, to achieve bright touch panels with high levels of visibility. These are also called surface wave or acoustic wave touch panels. Aside from standalone LCD monitors, these are widely used in public spaces, in devices like point-of-sale terminals, ATMs, and electronic kiosks.

These panels detect the screen position where contact occurs with a finger or other object using the attenuation in ultrasound elastic waves on the surface. The internal structure of these panels is designed so that multiple piezoelectric transducers arranged in the corners of a glass substrate transmit ultrasound surface elastic waves as vibrations in the panel surface, which are received by transducers installed opposite the transmitting ones. When the screen is touched, ultrasound waves are absorbed and attenuated by the finger or other object. The location is identified by detecting these changes. Naturally, the user does not feel these vibrations when touching the screen. These panels offer high ease of use.

The strengths of this type of touch panel include high light transmittance and superior visibility, since the structure requires no film or transparent electrodes on the screen. Additionally, the surface glass provides better durability and scratch resistance than a capacitive touch panel. Another advantage is that even if the surface does somehow become scratched, the panel remains sensitive to touch. (On a capacitive touch panel, surface scratches can sometimes interrupt signals.) Structurally, this type of panel ensures high stability and long service life, free of changes over time or deviations in position.

Weak points include compatibility with only fingers and soft objects (such as gloves) that absorb ultrasound surface elastic waves. These panels require special-purpose styluses and may react to substances like water drops or small insects on the panel.

All in all, however, these touch panels offer relatively few drawbacks. Recent developments such as improvements in manufacturing technology are also improving their cost-performance.

The category of optical touch panels includes multiple sensing methods. The number of products employing infrared optical imaging touch panels based on infrared image sensors to sense position through triangulation has grown in recent years, chiefly among larger panels.

A touch panel in this category features one infrared LED each at the left and right ends of the top of the panel, along with an image sensor (camera). Retroreflective tape that reflects incident light along the axis of incidence is affixed along the remaining left, right, and bottom sides. When a finger or other object touches the screen, the image sensor captures the shadows formed when the infrared light is blocked. The coordinates of the location of contact are derived by triangulation.

While this type differs somewhat from the above touch panels, let"s touch on the subject of electromagnetic induction touch panels. This method is used in devices like LCD graphics tablets, tablet PCs, and purikura photo sticker booths.

This input method for graphics tablets, which originally did not feature monitors, achieves high-precision touch panels by combining a sensor with the LCD panel. When the user touches the screen with a special-purpose stylus that generates a magnetic field, sensors on the panel receive the electromagnetic energy and use it to sense the position of the pen.

The table below summarizes the characteristics of the touch panels we"ve looked at. Keep in mind that even in devices based on the same sensing method, performance and functions can vary widely in the actual products. Use this information only as an introduction to general product characteristics. Additionally, given daily advances in touch-panel technological innovations and cost reductions, the information below is only a snapshot of current trends as of September 2010.

Each touch-panel type offers its own strengths and weaknesses. No single sensing method currently offers overwhelming superiority in all aspects. Choose a product after considering the intended use and environmental factors.

As the mainstream display mode of LCD, IPS is overwhelmingly used in many fields of flat displays. However, due to the stress sensitivity of glass, the stressed light leakage is a bottleneck for achieving perfect dark state performance. The conventional scheme of using a compensation polarizer outside the cell has no effect on this light leakage. Although many studies have been conducted to overcome this limitation, the proposed methods have limited effects. Our research team has proposed a novel light leakage compensation mechanism by introducing a positive A plate that is sandwiched between the glass and the LC layer, therefore the light leakage which is caused by the combined effect of the phase retardations from the stressed glasses and the LC layer can be eliminated. In addition to theoretically analyzing the compensation principles of the novel light leakage compensation mechanism, we also use the developed positive A material to prepare light leakage compensation demos. And then the electric-optical characteristics and light leakage compensation effects of the demos are evaluated. While maintaining excellent optical and electrical characteristics, this technology effectively solves the problem of stressed light leakage of glass-based IPS, improves the dark-state image quality, and breaks the application of IPS in products such as curve products.

After decades of development, IPS (In-Plane Switching) LCD (Liquid Crystal Display) occupies a dominant position in the display field. Due to its excellent display performance, IPS is widely used in all sizes of display products, such as mobile phones, tablet computers, notebook computers, monitors, and TVs

The LL is proportional to the backlight luminance and the transmittance (Tr) of the panel. When evaluating the LL caused by stress, the backlight luminance and the φ are fixed, so the LL is proportional to Tr. At this time, the δ1 in the Tr formula becomes the retardation related to stressed glass and LC, it is proportional to the retardation of glass (δ). Therefore, LL can be derived as:

Due to the manufacturing process of CF/TFT glass and panel, and even the using process of IPS panel, it is difficult to completely avoid the stress birefringence of glass. Although some studies have proposed solutions, such as slimming of glass thickness

where σ is the stress from bending, E is Young’s modulus of glass (73,000 MPa for LCD display used glass), t is the thickness of the glass sheet and r is the radius to which the sheet is bent. In an ideal case, as the light passes through the bent glass, the in-plane retardation can be calculated by the stress-optic law shown in formula (

In this article, referring to the fundamental reason for light leakage, we have proposed a novel light leakage compensation mechanism, and a new LCD structure with an in-cell phase retarder as a solution. The basic idea of phase compensation is to introduce a positive A (+A) plate to compensate for the retardation of LC, make the stress birefringence of CF and TFT glass offset each other, and effectively eliminate light leakage. We have explained the compensation mechanisms, analyzed the electric-optical characteristics, and studied the effects of LL compensation. It is a very important point to note that, different from studies of compensation layers on improving the viewing angle

As mentioned above, our research focuses on stressed LL caused by mechanical deformation stress. When the panel is under force, due to the fixing effect of the sealant, the panel as a whole, it experiences tension on the TFT glass and compression on the CF glass as bending 1, under pure bending, these tensile and compressive stresses are equal in magnitude but opposite in direction. At the neutral axis where the transition between tensile and compressive zones occurs, the stress is zero.

As shown in Fig. 2b, the first new LCD structure called compensation mode 1, introduces the  +A plate, which is sandwiched between the glass and LC. More specifically, the optical axis of the  +A plate is perpendicular to the initial optical axis of LC, and the phase retardation of the  +A plate is 350 nm, which is equal to that of the LC.Fig. 2b" illustrates the compensation principle of compensation mode 1. When receives external stress, the light from the backlight unit traverses the TFT polarizer, the effective optical axis position on the Poincaré sphere is P1, when the light (P1) successively passes through the stressed TFT glass, its polarization state is rotated from P1 to P2. And when the light (P2) passes through LC, its polarization state is rotated from P2 to P3. Then, the light (P3) successively passes through the  +A plate and the stressed CF glass, whose effective optical axis positions on the Poincaré sphere are P4 and P5, respectively. The intermediate polarization state (P2) in general, is an elliptical polarization state. Due to the role of the  +A plate, the polarization state (P5) on the Poincaré sphere is very near to the polarization state (P1), so the light almost can be absorbed by the CF polarizer, and the elimination of LL is achieved.

The second new LCD structure called compensation mode 2, also introduces a  +A plate, but the optical axis of the  +A plate is parallel to the initial optical axis of LC, the sum of the phase retardation of  +A and LC is an integer multiple of a specific wavelength. Considering that the human eye has the strongest sensitivity to green light, the retardation value of  +A is designed to be 200 nm, and the sum of phase retardation of  +A and LC is 550 nm, that is the specific wavelength is 550 nm.

When the thickness of the glass is not equal, such as the thickness of the CF glass is 0.3t and the thickness of the TFT glass is 0.4t, the panel as a whole still has the same compressive and tensile stresses on the neutral axis, but the neutral axis is not in the middle of the CF and TFT glass. When the neutral layer is located in the TFT glass, the CF glass has compressive stress. But the TFT glass has tensile and compressive stress, as the stress birefringence δ generated by each has different directions, the δcompressive of TFT can be offset by the δtensile of TFT, and finally, the δtensile of TFT will be equal to the δcompressive of CF glass. At this time, the situation is the same as when the thickness of TFT and CF glass is equal. So when the stresses of the CF and TFT glass are not completely equal, the proposed compensation mode can still effectively reduce light leakage.

The electric-optical characteristics of the panel are measured by DMS-1250 (Autronic Melchers Company). Figure 7 shows the V-T curves of 3.54inches demos. Because the light dispersion effect of LC and other materials was not considered in the simulation, the simulated value and the actual value cannot be completely consistent, but the trends and conclusions of the two are consistent. As can be seen from Fig. 7a, the V-T curves of normal IPS, compensation mode 1, and mode 2 basically coincides. Furthermore, it can be seen from the enlarged picture Fig. 7a", the dark state brightness of the sample is basically the same when no external force is applied, and the dark state brightness of compensation mode 1 is somewhat higher. The transmittance of normal IPS, compensation mode 1, and mode 2 are 0.099%, 0.128%, and 0.106% respectively. The transmittance curves are obtained from the brightness of the gray scales. The L0 brightness of normal IPS, compensation mode 1, and mode 2 are 0.5769nit, 0.6774nit, and 0.5526nit, respectively. Because the brightness test accuracy of the equipment is ± 0.01, the device error can be eliminated. It can be seen that the difference in brightness and transmittance is mainly caused by sample differences. The L0 brightness of ordinary IPS and mode 2 is basically the same, while the L0 brightness of mode 1 is higher.

For compensation mode 1, the dark state brightness is higher than that of the other two demos as shown in Fig. 3, so it has a lower CR. General, the light scattering of LC is an important factor to increase dark-state brightness and reduce panel CR

Table ​Table22 are the CR of  +A and panels. The retardations of compensation mode 1 and mode 2 are 350 nm and 200 nm, respectively. Due to the effect of light scattering, the CR of mode 1 (4100) is lower than that of mode 2 (6900). For mode 1, the low CR of  +A is the bottleneck CR among the various optical layers of the panel and further reduces the CRpanel to 789. So it is necessary to increase the CR+A for mode 1. For mode 2,  +A has a higher CR of 6900 which is almost equivalent to the color filter CR in IPS, the CRpanel remains the same as normal IPS. Based on the existing compensation materials, compensation mode 2 is recommended.

In order to verify the LL elimination effect of compensation technology on curved samples, the samples of 13.3 inches with a curvature of 2800R/2500R/2000R/1500R/1000R are prepared. And the glass thickness of normal IPS and compensation samples are 0.5t/0.5t (TFT/CF glass). The L0 brightness at the center of the panel and at the four corners of the panel are tested respectively. And the LL compensation effect of different curvatures samples are compared and analyzed. The ratio of the brightness of the four corners to the center is used to represent the LL level. The larger the ratio, the greater the brightness of the four corners, and the worse the compensation effect of LL.

In this paper, a compensation structure with excellent dark state image quality is proposed and experimentally analyzed. This technology can fundamentally improve the dark state LL even under deformation. By introducing a  +A plate that is sandwiched between the glass and the homogeneous LC layer, the LL caused by the combined effect of the phase retardations from the stressed glasses and the LC layer can be eliminated. But the compensation layer for glass stressed LL must be placed between the upper and lower glass, inside the cell. The conventional scheme of using compensation polarizer outside the cell cannot achieve the compensation effect of the scheme proposed in this article. We have proposed two light leakage compensation mechanisms and structures, compensation mode 1 and mode 2. Considering the optical characteristics, especially the effect of CR of  +A on the panel, we recommend the mode 2 solution. For mode 1, after the CR of  +A material is improved, it is also a good light leakage improvement solution. This compensation technology is applicable for IPS modes. In addition to theoretical analysis of compensation principles, we have also developed  +A materials that can meet the preparation process of IPS and prepared effective compensation demos. It is proved that the solution proposed in this paper is not only effective for reducing the local stress LL of flat panels but also effective for weakening the curved stress LL.

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A new glasses-free 3D video system uses three layered LCD panels displaying bizarre patterns (two images on the left & top right image) that collectively produce a coherent, high-resolution, multiperspective 3D image. The bottom right image illustrates, roughly, the composite image that would reach one eye at one viewing angle.

Similar to the dual layered LCD screens used by Nintendo’s 3DS to create glasses-free 3D images, engineers at MIT developed a “Tensor Display,” which uses several layers of liquid-crystal displays to produce a convincing 3D illusion.

Instead of the complex hardware required to produce holograms, the Media Lab system, dubbed a Tensor Display, uses several layers of liquid-crystal displays (LCDs), the technology currently found in most flat-panel TVs. To produce a convincing 3D illusion, the LCDs would need to refresh at a rate of about 360 times a second, or 360 hertz. Such displays may not be far off: LCD TVs that boast 240-hertz refresh rates have already appeared on the market, just a few years after 120-hertz TVs made their debut.

“Holography works, it’s beautiful, nothing can touch its quality,” says Douglas Lanman, a postdoc at the Media Lab and one of the new paper’s co-authors. “The problem, of course, is that holograms don’t move. To make them move, you need to create a hologram in real time, and to do that, you need … little tiny pixels, smaller than anything we can build at large volume at low cost. So the question is, what do we have now? We have LCDs. They’re incredibly mature, and they’re cheap.”

The Nintendo 3DS — a portable, glasses-free 3D gaming device introduced last year — uses two layered LCD screens to produce the illusion of depth, with the bottom screen simply displaying alternating dark and light bands. Two slightly offset images, which represent the different perspectives of the viewer’s two eyes, are sliced up and interleaved on the top screen. The dark bands on the bottom screen block the light coming from the display’s backlight in such a way that each eye sees only the image intended for it.

To get the refresh rate down to 360 hertz, the Tensor Display adds another LCD screen, which displays yet another pattern. That makes the problem of calculating the patterns exponentially more complex, however. In solving that problem, Raskar, Lanman and Hirsch were joined by Gordon Wetzstein, a new postdoc in the Camera Culture group.

The researchers’ key insight was that, while some aspects of a scene change with the viewing angle, some do not. The pattern-calculating algorithms exploit this natural redundancy, reducing the amount of information that needs to be sent to the LCD screens and thus improving the resolution of the final image.

At Siggraph, the Media Lab researchers will demonstrate a prototype Tensor Display that uses three LCD panels. They’ve also developed another prototype that uses only two panels, but between the panels they introduce a sheet of lenses that refract light left and right. The lenses were actually developed for stereoscopic display systems; an LCD panel beneath the lenses alternately displays one image intended for the left eye, which is diffracted to the left, and another for the right eye, which is diffracted to the right. The MIT display also takes advantage of the ability to project different patterns in different directions, but the chief purpose of the lenses is to widen the viewing angle of the display. With the three-panel version, the 3D illusion is consistent within a viewing angle of 20 degrees, but with the refractive-lens version, the viewing angle expands to 50 degrees.