patents tft lcd globally manufacturer

[1] The present invention relates to a cutting method of a large size TFT-LCD panel and a liquid crystal display unit to enhance a simplicity of process facility and a speediness through solving a problem of an increase of facilities due to manufacturing TFT-LCD panels of respective sizes and reducing a subsequently increased cost by enabling a mass production of a various size of TFT-LCD panels in one manufacturing line through using a TFT-LCD panel cut in a desired size that is manufactured in large size. Background Art

[5] Most of all as an outline, one pixel (composed of R. G. B. three sub-pixels) in the thin film transistor (TFT) - LCD is approximately as fine as 0.3 mm wide.

[6] Of course, the TFT included in the pixel is smaller than the pixel. Moreover, in order to meet a resolution of 1600x1200, 1,920,000 pixels are required and 5,760,000 TFTs are necessary if the sub-pixels are considered. Therefore, an overall process is very precise and demands a level of semiconductor process.

TFT process, a color filter (CF) process, a cell process and a module process. The cell process makes one panel with two glasses undergone the TFT process and the CF process. Then, the module process completes the manufacturing process by mounting the one TFT-LCD panel undergone the cell process in a real monitor or TV.

[8] First, the TFT process is the most basic core process for forming the most basic electrodes that provides an electrode for each cell. The process includes five process steps in order of forming a gate electrode, an insulating film, a semiconductor film, a data electrode, a protective film, and a pixel electrode that requires one or more pattern processes for each process step. Not only this pattern process that may be called a core

process in the processes of manufacturing the TFT-LCD panel is necessary in the TFT process but also a similar pattern process is necessary in the CF process.

TFT-LCD panel formed as hereinabove, the TFT-LCD panel is completed by providing a polarized plate on a surface of the TFT substrate and the CF substrate.

[11] The TFT-LCD panel of size demanded by a user may be produced in a large amount but the other TFT-LCD panel of less demand may be produced in only a limited amount since various sizes of the TFT-LCD panels completed as hereinabove require a difference in production line and in each process of the production line dependent on the sizes of the TFT-LCD panels. Disclosure of Invention Technical Problem

[13] The cutting method of a large size TFT-LCD panel of the present invention, provided to solve the hereinabove problems, has an object of enhancing a simplicity of process facility and speediness through solving a problem of an increase of facilities due to manufacturing TFT-LCD panels of different sizes and reducing a subsequently increased cost by enabling a mass production of a various size of TFT-LCD panels in one manufacturing line through using a TFT-LCD panel cut in a desired size that is manufactured in large size.

[14] The cutting method of a large size TFT-LCD panel formed as hereinabove can devise a simplicity in process and a profitability through solving a spatial enlargement and other costs increase due to an increase of facilities by equipping a facility"s process dependent on a size according to a production of TFT-LCD panels in various sizes, having an advantage of possibly producing a various size of the TFT-LCD panel asked by a user purpose or a user taste in a simple and convenient way, and solving an abandonment and reduction of the facilities due to a change in consumption dependent

[18] FIG. 4 illustrates a state of a scribe line set into a mid-depth of a color filter substrate and a thin film transistor substrate by diamond wheel in the cutting method of a large size TFT-LCD panel of the present invention.

[20] FIG. 6 illustrates a state completed after processing sealing a cut portion in the cutting method of a large size TFT-LCD panel of the present invention.

[27] In a completed large size TFT-LCD panel formed in a sequentially coupled configuration of a polarized plate, a color filter (CF) substrate, a liquid crystal layer, a thin film transistor (TFT) substrate and a polarized plate below the TFT substrate, a polarized plate stripping step that removes a portion of a predetermined width to be cut from the each polarized plate provided on a surface and an opposite surface of the large size TFT-LCD panel, a cutting location setting step that sets a portion not damaging a gate line and a data line of the TFT substrate through investigating a portion stripped in the polarized plate stripping step by microscope, a scribe line setting step that sets a first scribe line cutting the CF substrate into its mid-depth along the portion set in the cutting location setting step using a diamond wheel, a turning

over step that turns over the large size TFT-LCD panel to a side opposite from a side where a portion of the first scribe line is set after chucking one end of the large size TFT-LCD panel, a scribe line setting step that sets a second scribe line cutting the TFT substrate into its mid-depth in the stripped polarized plate portion along the portion set in the cutting location setting step which precisely corresponds with the set first scribe line using a diamond wheel after turning over the large size TFT-LCD panel, a tempering step that tempers for 30 minutes to form a natural crack in the scribe lines formed on the CF substrate and the TFT substrate of the large size TFT-LCD panel, a cutting step that cuts the CF substrate and the TFT substrate naturally cracked after the 30 minutes tempering step, and a sealing process step that sealing a cut portion formed in the cutting step, and

[28] In a completed large size TFT-LCD panel formed in a sequentially coupled configuration of a polarized plate, a color filter (CF) substrate, a liquid crystal layer, a thin film transistor (TFT) substrate and a polarized plate, a cutting location setting step that sets a portion to be cut, a scribe line setting step that sets a first scribe line cutting the CF substrate into its mid-depth along the portion set in the cutting location setting step using a diamond wheel, a turning over step that turns over the large size TFT-LCD panel to a side opposite from a side where a portion of the first scribe line is set after chucking one end of the large size TFT-LCD panel, a scribe line setting step that sets a second scribe line cutting the TFT substrate into its mid-depth along the portion set in the cutting line setting step which precisely corresponds with the set first scribe line, using a diamond wheel after turning over the large size TFT-LCD panel, a tempering step that tempers for 30 minutes to form a natural crack in the scribe lines formed on the CF substrate and the TFT substrate of the large size TFT-LCD panel, a cutting step that cuts the CF substrate and the TFT substrate naturally cracked after the 30 minutes tempering step, and a sealing process step that sealing a cut portion formed in the cutting step may accomplish the present invention object.

[29] Further, the present invention comprises a scribe line setting step that sets scribe lines simultaneously cutting the CF substrate and the TFT substrate into their mid-depths along the portions set in the cutting location setting step using a diamond wheel.

[30] The cutting method of a large size TFT-LCD panel further comprises a blocking off a light illuminated from a backlight through attaching a light blocking tape along a cut portion selected between the CF substrate and the TFT substrate or the both substrates or between the polarized plates located above the CF substrate and below the TFT substrate or the both polarized plates.

LCD panel 100 is formed in structure sequentially coupled of, a polarized plate 10, a color filter (CF) substrate 11, a liquid crystal layer 12, a thin film transistor (TFT) substrate 13 and a polarized plate 14.

[36] In order to cut the large size TFT-LCD panel 100 completed as hereinabove, a polarized plate stripping step is initially performed that removes a portion of a predetermined width to be cut from the each polarized plate 10 provided on a surface above the CF substrate 11 and an opposite surface below the TFT substrate 13.

[38] The TFT substrate 13 is exposed if the polarized plates 10 and 14 around the cutting portion are removed by its lengthwise direction. Since gate lines transferring a scanning signal and data line transferring a screen image signal are configured by innumerably crossing with each other and difficult to perceive by naked eyes, a cutting location setting step sets a portion not damaging the gate line and the data line of the TFT substrate through investigating a portion stripped on the polarized plate stripping step by microscope.

[43] To process a side opposite from a side where a portion of the first scribe line is set, the present step turns over the large size TFT-LCD panel 100 after chucking one end of the large size TFT-LCD panel 100.

[45] The present step sets a 2nd scribe line setting step cutting the TFT substrate 13 into its mid-depth in the portion of the stripped polarized plate 14 bonded with the TFT substrate 13 below along the portion set in the cutting location setting step which

precisely corresponds with the set first scribe line, using a diamond wheel after turning over the large size TFT-LCD panel 100. This step is also difficult and requires a skill of high precision to correspond with the set first scribe line.

[48] A natural crack is made if tempered for 30 minutes to form a natural crack in the scribe lines formed on the CF substrate 11 and the TFT substrate 13 of the large size TFT-LCD panel 100. Then, the air flows into a liquid crystal layer 12. If there is the air flow into the liquid crystal layer 12, the liquid crystal layer 12 is temporarily restricted from flowing out by the flowed in air.

[50] After the 30 minutes tempering step, the CF substrate 11 and the TFT substrate 13 are naturally cracked along the first scribe line and the second scribe line and the present step externally applies a certain amount of force in order to cut the large size TFT-LCD panel 100 along the scribe lines.

[52] The present step is the last step that applies a sealant 30 on a cut portion in the large size TFT-LCD panel 100 and the present invention is completed by applying the sealant 30.

[53] Through undergoing the process hereinabove, the large size TFT-LCD panel 100 is possible to be cut into a plural or multiple numbers without a many numbers of equipment and to meet a desired size of a demander or an operator.

[56] That is, in a large size TFT-LCD panel 100 completed of forming sequentially coupled, a polarized plate 10, a color filter (CF) substrate 11, a liquid crystal layer 12, a thin film transistor (TFT) substrate 13 and a polarized plate 14 below the TFT substrate 13, a cutting location setting step that sets a portion to be cut, a scribe line setting step that sets a first scribe line cutting the CF substrate 11 into its mid-depth along the portion set in the cutting location setting step using a diamond wheel, a turning over step that turns over the large size TFT-LCD panel 100 to a side opposite from a side where a portion of the first scribe line is set after chucking one end of the large size TFT-LCD panel 100, a scribe line setting step that sets a second scribe line cutting the TFT substrate 13 into its mid-depth along the portion set in the cutting location setting step corresponds with the set first scribe line, using a diamond wheel after turning over the large size TFT-LCD panel 100, a tempering step that tempers for

30 minutes to form a natural crack in the scribe lines formed on the CF substrate 11 and the TFT substrate 13 of the large size TFT-LCD panel 100, a cutting step that cuts the CF substrate 11 and the TFT 13 substrate naturally cracked after the 30 minutes tempering step, and a sealing process step that sealing a cut portion formed in the cutting step may configure the present invention.

[59] For example, after undergoing the sequentially processed cutting location setting steps of the first or the second exemplary embodiments through the polarized plate stripping step that removes a corresponding portion of a predetermined width to be cut from the polarized plates 10 and 14 provided on a surface of the CF substrate 11 and an opposite surface of the TFT substrate 13 like the first exemplary embodiment or without the polarized plate stripping step like the second exemplary embodiment, a scribe line setting step sets scribe lines simultaneously cutting the CF substrate 11 and the TFT substrate 13 into their mid-depths along the portion set in the cutting location setting step using a diamond wheel.

TFT substrate 13 by applying the same scribe line depth and the like enables not only an abridgement of the operation process but also a precise setting job.

[61] The present exemplary embodiment may or may not include the polarized plate stripping step like the first or second exemplary embodiment, and the subsequent steps may proceed in the same sequence as tempering step for the natural crack, cutting step cutting the CF substrate 11 and the TFT substrate 13 and sealing process step .

[62] Meanwhile, when a light from the backlight unit through the TFT-LCD panel 100 processed by the respective exemplary embodiments is illuminated to display a corresponding image, the image may be displayed with an image quality relatively unclear at a portion corresponding to the cutting portion.

[64] Here, the light blocking tape 20 may be attached in a range covering any cut portions of the CF substrate 11 and the TFT substrate 13 or the both substrates 11 and 13 as shown in FIG. 7.

10 bonded above with the CF substrate 11 or at a periphery of the polarized plate 14 bonded below with the TFT substrate 14 which are removed with the set cutting portion, may maximize a clearness of the screen quality when the light from the back light unit is illuminated on the cut portion of the TFT-LCD panel 100 completed by cutting into a desirable size.

[67] Meanwhile, as shown in FIG. 9 of other exemplary embodiment, a transparent tape is used to cover an outer peripheral edge of the CF substrate 11 and the TFT substrate 13 after sealing the outer peripheral edge with an ultraviolet sealant 31 while the CF substrate 11 and the TFT substrate 13 are in bonded state.

[68] Further, though not shown in the drawings, the peripheries of the CF substrate 11 and the TFT substrate 13 may be covered by tape-processing or may be fixed by clipping and the like.

[70] Further, FIG. 10 and FIG. 11 illustrate an application of the TFT-LCD panel according to the cutting method provided by the present invention. FIG. 10 is a brief exploded perspective view of a liquid crystal display unit. FIG. 11 is a brief cross sectional view of FIG. 10.

[71] As shown in FIG. 10 and FIG. 11, the cut processed TFT-LCD panel 100 equipped with the backlight unit (not shown in drawing) below undergoes a series of course coupling a top sash 2 corresponding to an upper frame with an accommodating frame 3 accommodating the TFT-LCD panel 100 and the backlight unit to be used for the liquid crystal display unit.

[72] Here, when the TFT-LCD panel 100 cut processed in a desired size according to the present invention is received in the top sash 2 and the accommodating frame 3, a realization of a clear screen may be difficult since a slight difference may be produced, not accurately fixing the TFT-LCD panel 100, and producing a flowing phenomena because of the internal difference.

[74] Accordingly, in order to prevent the flowing phenomena, that is the flowing phenomena of the received TFT-LCD panel 100, attaching a plurality of both-faces tape 4 at the outer peripheral edge on the top sash 2 surface and attaching a plurality of both-faces tape 4 at the outer peripheral edge on the accommodating frame 3 surface as well is preferable to completely prevent the flowing phenomena.

[76] Therefore, since a large size TFT-LCD panel may be miniaturized for an application to various video games, monitors or cell phone liquid crystal displays through cut processing the large size TFT-LCD panel without a separate manufacturing line for manufacturing process according to present invention, an industrial applicability expecting an effective reduction of manufacturing facility and its value may be recognized.

Realize that goal of the invention technical scheme of the present invention is: this production line of the present invention is after glass substrate forming annealing, come out through cutting from annealing furnace, grind, check, packing, to the processing whole process of producing finished product, according to process characteristics and zone, be divided into three work areas according to the operation setting, be followed successively by the annealing furnace end region, the post-treatment district, the test package district, three work areas are connected formation whole piece TFT-LCD glass substrate production line successively, be made as to be interrupted and be connected by manually transporting equipment between annealing furnace end region and the post-treatment district, be made as directly by automatic conveying equipment between post-treatment district and the test package district and be connected; Wherein the annealing furnace end region comprise be disposed with transverse cutting unit, load units, supply unit, weighting unit, rip cutting unit, verification unit, go up the paper unit, packaging unit constitutes, the terminal workspace of annealing furnace constitutes a whole set of sealing working cycle system, each working cell is connected successively, its supply unit connects each working cell thereafter and is loop structure, and each equipment of annealing furnace end region is realized the united and coordinating running by the electrical apparatus control system of supporting setting; The post-treatment district comprises the load units that sets gradually, gets paper unit, supply unit, transposable element, scribing unit, breaks disconnected unit off with the fingers and thumb, grinding unit, cleaning unit constitute, each working cell is connected successively, its supply unit connects each working cell thereafter, and each equipment of post-treatment district is realized the united and coordinating running by the electrical apparatus control system of supporting setting; The test package district comprises that supply unit, temporary storage location, verification unit, the unloading unit that sets gradually, the finished product packing unit of finishing the finished product packing constitute, each working cell is connected successively, its supply unit connects each working cell thereafter, and each equipment of test package district is realized the united and coordinating running by the electrical apparatus control system of supporting setting.

AUO Corporation ("AUO" or the "the Company") (TAIEX: 2409; NYSE: AUO), one of the world"s top manufacturers of TFT-LCD panels, announced the signing of a patent assignment agreement with International Business Machines Corp ("IBM") today. This transaction will allow AUO to own hundreds of TFT-LCD related patents developed by IBM, some technologies of which are widely adopted in the industry.

With this agreement, approximately 170 United States patents relating to TFT-LCD technology, together with the counterpart patents in Japan, Korea, Taiwan, and other countries, will be transferred to AUO. The patents cover almost all aspects of key TFT-LCD-related technology, including TFT Array process (TFT structure production), Cell process, such as One Drop Fill Technology, RBG Color Filter, Backlight and TFT driving circuit, among others.

Dr. Fan Luo, AUO "s Chief Technology Officer, stated that IBM, as a pioneer in the TFT-LCD industry, commenced research and development in the TFT-LCD technology since the 1980s, of which originated some fundamental key technologies. After IBM exited from TFT-LCD manufacturing in 2001, it still maintained the TFT-LCD related patents. Some of the patents transferred under this transaction were developed by IBM"s research lab in Japan as well as the Yasu manufacturing site, some of which are believed to be widely used in the industry. With the patents assigned, AUO will further strengthen its intellectual property position on both the defensive and offensive aspects.

During the era of Acer Display Technology, AUO has already entered into a technology transfer and license agreement with IBM since 1999, and built Taiwan"s first Generation 3.5 TFT-LCD fabrication facility. The successful partnership paved the way for AUO "s growth in the following years and strengthened the company’s TFT-LCD manufacturing process and development. In a few years thereafter, AUO went on to establish Generation 4, Generation 5, and Generation 6 fabrication production facility – all first in Taiwan.

As Taiwan"s largest and world"s third largest TFT-LCD manufacturer, AU Optronics also leads in Taiwan in the area of intellectual property. As of May 2005, the company owns over 1,100 patents worldwide with over 2,800 patent applications pending. The company is one of the top patent applicants in Taiwan"s optoelectronics industry. Moreover, IFI Claims Patents Services placed AUO as the fifth fastest growing patent applicant in the United States in 2004 with a 98% annual increase. With the patents assigned, the number of AUO "s United States patents will increase from about 200 to about 370.

In recognition of the efforts of the company"s patent engineers and legal staff, the President of AUO, Mr. HB Chen stated, "the efforts made by the AUO Technology Center in developing technologies in flat panel displays are evident, and we have seen the accomplishment of our patent filings in recent years. The transfer of these important fundamental patents from IBM is the largest number of TFT-LCD related patents acquired in Taiwan. It not only elevates the company"s intellectual property position, but also helps us to preserve the interest of our customers."

AU Optronics and IBM also entered into a patent cross license agreement on the same day for a license of the relevant products under other patents owned by both companies.

STONE Technologies is a proud manufacturer of superior quality TFT LCD modules and LCD screens. The company also provides intelligent HMI solutions that perfectly fit in with its excellent hardware offerings.

STONE TFT LCD modules come with a microcontroller unit that has a 1GHz Cortex-A8 CPU. Such a module can easily be transformed into an HMI screen. Simple hexadecimal instructions can be used to control the module through the UART port. Furthermore, you can seamlessly develop STONE TFT LCD color user interface modules and add touch control, features to them.

Becoming a reputable TFT LCD manufacturer is no piece of cake. It requires a company to pay attention to detail, have excellent manufacturing processes, the right TFT display technology, and have a consumer mindset.

Now, we list down 10 of the best famous LCD manufacturers globally. We’ll also explore why they became among the top 10 LCD display Manufacturers in the world.

In 2019, BOE’s yearly new-patent applications amounted to 9657, of which over 90% are invention patents, amounting to over 70,000 usable patents in total. Data from IFI Claims also shows that BOE has ranked 13th among the Top 50 USPTO (The United States Patent and Trademark Office), Patent Assignees, in 2019. According to the 2019 International PCT Applications of WIPO, BOE ranked No.6 with 1,864 applications.

LG Display is a leading manufacturer of thin-film transistor liquid crystal displays (TFT-LCD) panels, OLED, and flexible displays.LG Display began developing TFT-LCD in 1987 and currently offers Display panels in a variety of sizes and specifications using different cutting-edge technologies (IPS, OLED, and flexible technology).

With innovative and differentiated technologies, QINNOOptoelectronics provides advanced display integration solutions, including 4K2K ultra-high resolution, 3D naked eye, IGZO, LTPS, AMOLED, OLED, and touch solutions. Qinnooptoelectronics sets specifications and leads the market. A wide range of product line is across all kinds of TFT LCD panel modules, touch modules, for example, TV panel, desktop and laptop computer monitor with panels, small and medium scale “panels, medical, automotive, etc., the supply of cutting-edge information and consumer electronics customers around the world, for the world TFT – LCD (thin-film transistor liquid crystal display) leading manufacturers.

AU Optronics Co., LTD., formerly AU Optronics Corporation, was founded in August 1996. It changed its name to AU Optronics after its merger with UNIOPtronics in 2001. Through two mergers, AU has been able to have a full range of generations of production lines for panels of all sizes.Au Optronics is a TFT-LCD design, manufacturing, and r&d company. Since 2008, au Optronics has entered the green energy industry, providing customers with high-efficiency solar energy solutions.

Sharp has been called the “father of LCD panels”.Since its founding in 1912, Sharp developed the world’s first calculator and LIQUID crystal display, represented by the living pencil, which was invented as the company name. At the same time, Sharp is actively expanding into new areas to improve people’s living standards and social progress. Made a contribution.

BYD IT products and businesses mainly include rechargeable batteries, plastic mechanism parts, metal parts, hardware electronic products, cell phone keys, microelectronics products, LCD modules, optoelectronics products, flexible circuit boards, chargers, connectors, uninterruptible power supplies, DC power supplies, solar products, cell phone decoration, cell phone ODM, cell phone testing, cell phone assembly business, notebook computer ODM, testing and manufacturing and assembly business, etc.

Tianma microelectronics co., LTD., founded in 1983, the company focus on smartphones, tablets, represented by high order laptop display market of consumer goods and automotive, medical, POS, HMI, etc., represented by professional display market, and actively layout smart home, intelligent wear, AR/VR, unmanned aerial vehicles (UAVs) and other emerging markets, to provide customers with the best product experience.IN terms of technology, the company has independently mastered leading technologies such as LTPS-TFT, AMOLED, flexible display, Oxide-TFT, 3D display, transparent display, and in-cell/on-cell integrated touch control. TFT-LCD key Materials and Technologies National Engineering Laboratory, national enterprise Technology Center, post-doctoral mobile workstation, and undertake national Development and Reform Commission, The Ministry of Science and Technology, the Ministry of Industry and Information Technology, and other major national thematic projects. The company’s long-term accumulation and continuous investment in advanced technology lay the foundation for innovation and development in the field of application.

Reference is made to commonly assigned U.S. Serial No. 08/355,786 entitled "An Electroluminescent Device Having an Organic Electroluminescent Layer" by Tang et al and U.S. Serial No. 08/355,940 entitled "A Method of Fabricating a TFT-EL Pixel" by Tang et al, both filed concurrently herewith, the disclosures of which are incorporated herein. Field of the Invention

The present invention relates to an electroluminescent display panel employing thin-film-transistors (TFT) as active-matrix addressing elements, and organic electroluminescent thin films as the emissive medium. Introduction

Rapid advances in flat-panel display (FPD) technologies have made high quality large-area, full-color, high-resolution displays possible. These displays have enabled novel applications in electronic products such as lap top computers and pocket-TVs. Among these FPD technologies, liquid crystal display (LCD) has emerged as the display of choice in the marketplace. It also sets the technological standard against which other FPD technologies are compared. Examples of LCD panels include: (1) 14", 16-color LCD panel for work stations (IBM and Toshiba, 1989) (see K. Ichikawa, S. Suzuki, H. Matino, T. Aoki, T. Higuchi and Y. Oano, SID Digest, 226 (1989)), (2) 6", full-color LCD-TV (Phillips, 1987) (see M.J. Powell, J.A. Chapman, A.G. Knapp, I.D. French, J.R. Hughes, A.D. Pearson, M. Allinson, M.J. Edwards, R.A. Ford, M.C. Hemmings, O.F. Hill, D.H. Nicholls and N.K. Wright, Proceeding, International Display Conference, 63, 1987), (3) 4" full-color LCD TV (model LQ424A01, Sharp, 1989) (see Sharp Corporation Technical Literature for model LQ424A01), and (4) 1 megapixel colored TFT-LCD (General Electric) (see D.E. Castleberry and G.E. Possin, SID Digest, 232 (1988)). All references, including patents and publications, are incorporated herein as if reproduced in full below.

A common feature in these LCD panels is the use of thin-film-transistors (TFT) in an active-addressing scheme, which relaxes the limitations in direct-addressing (see S. Morozumi, Advances in Electronics and Electron Physics, edited by P.W. Hawkes, Vol. 77, Academic Press 1990). The success of LCD technology is in large part due to the rapid progress in the fabrication of large-area TFT (primarily amorphous silicon TFT). The almost ideal match between TFT switching characteristics and electrooptic LCD display elements also plays a key role.

A major drawback of TFT-LCD panels is they require bright backlighting. This is because the transmission factor of the TFT-LCD is poor, particularly for colored panels. Typically the transmission factor is about 2-3 percent (see S. Morozumi, Advances in Electronics and, Electron Physics, edited by P.W. Hawkes, Vol. 77, Academic Press, 1990). Power consumption for backlighted TFT-LCD panels is considerable and adversely affects portable display applications requiring battery operation.

An ideal solution to the foregoing limitation would be a low power emissive display that eliminates the need for backlighting. A particularly attractive candidate is thin-film-transistor-electroluminescent (TFT-EL) displays. In TFT-EL displays, the individual pixels can be addressed to emit light and auxiliary backlighting is not required. A TFT-EL scheme was proposed by Fischer in 1971 (see A.G. Fischer, IEEE Trans. Electron Devices, 802 (1971)). In Fischer"s scheme powdered ZnS is used as the EL medium.

In 1975, a successful prototype TFT-EL panel (6") was reportedly made by Brody et al. using ZnS as the EL element and CdSe as the TFT material (see T.P. Brody, F.C. Luo, A.P. Szepesi and D.H. Davies, IEEE Trans. Electron Devices, 22, 739 (1975)). Because ZnS-EL required a high drive voltage of more than a hundred volts, the switching CdSe TFT element had to be designed to handle such a high voltage swing. The reliability of the high-voltage TFT then became suspect. Ultimately, ZnS-based TFT-EL failed to successfully compete with TFT-LCD. U.S. Patents describing TFT-EL technology include: US-A-3,807,037;US-A-3,885,196; US-A-3,913,090; US-A-4,006,383; US-A-4,042,854; US-A-4,523,189; and US-A-4,602,192.

Recently, organic EL materials have been devised. These materials suggest themselves as candidates for display media in TFT-EL devices (see C.W. Tang and S.A. VanSlyke, Appl. Phys. Lett., 51, 913 (1987), C.W. Tang, S.A. VanSlyke and C.H. Chen, J. Appl. Phys., 65, 3610 (1989)). Organic EL media have two important advantages: they are highly efficient; and they have low voltage requirements. The latter characteristic distinguishes over other thin-film emissive devices. Disclosures of TFT-EL devices in which EL is an organic material include: US-A-5,073,446; US-A-5,047,687, US-A-5,059,861; US-A-5,294,870; US-A-5,151,629; US-A-5,276,380; US-A-5,061,569; US-A-4,720,432; US-A-4,539,507; US-A-5,150,006; US-A-4,950,950; and US-A-4,356,429.

The particular properties of organic EL material that make it ideal for TFT are summarized as follows: 1) Low-voltage drive. Typically, the organic EL cell requires a voltage in the range of 4 to 10 volts depending on the light output level and the cell impedance. The voltage required to produce a brightness of about 20 fL is about 5V. This low voltage is highly attractive for a TFT-EL panel, as the need for the high-voltage TFT is eliminated. Furthermore, the organic EL cell can be driven by DC or AC. As a result the driver circuity is less complicated and less expensive.

3) Low temperature fabrication. Organic EL devices can be fabricated at about room temperature. This is a significant advantage compared with inorganic emissive devices, which require high-temperature (>300°C) processing. The high-temperature processes required to make inorganic EL devices can be incompatible with the TFT.

The present invention provides an active matrix 4-terminal TFT-EL device in which organic material is used as the EL medium. The device comprises two TFTs, a storage capacitor and a light emitting organic EL pad arranged on a substrate. The EL pad is electrically connected to the drain of the second TFT. The first TFT is electrically connected to the gate electrode of the second TFT which in turn is electrically connected to the capacitor so that following an excitation signal the second TFT is able to supply a nearly constant current to the EL pad between signals. The TFT-EL devices of the present invention are typically pixels that are formed into a flat panel display, preferably a display in which the EL cathode is a continuous layer across all of the pixels.

A first thin-film-transistor (TFT1) is disposed over the top surface of the substrate. TFT1 comprises a source electrode, a drain electrode, a gate dielectric, and a gate electrode; and the gate electrode comprises a portion of a gate bus. The source electrode of TFT1 is electrically connected to a source bus.

A second thin-film-transistor (TFT2) is also disposed over the top surface of the substrate, and TFT2 also comprises a source electrode, a drain electrode, a gate dielectric, and a gate electrode. The gate electrode of TFT2 is electrically connected to the drain electrode of the first thin-film-transistor.

A storage capacitor is also disposed over the top surface of the substrate. During operation, this capacitor is charged from an excitation signal source through TFT1, and discharges during the dwell time to provide nearly constant potential to the gate electrode of TFT2.

An anode layer is electrically connected to the drain electrode of TFT2. In typical applications where light is emitted through the substrate, the display is a transparent material such as indium tin oxide.

A dielectric passivation layer is deposited over at least the source of TFT1, and preferably over the entire surface of the device. The dielectric passivation layer is etched to provide an opening over the display anode.

In preferred embodiments, the TFT-EL device of the present invention is made by a method using low pressure and plasma enhanced chemical vapor deposition combined with low temperature (i.e. less than 600°C) crystallization and annealing steps, hydrogen passivation and conventional patterning techniques.

The construction of pixels having thin-film-transistors composed of polycrystalline silicon and silicon dioxide provides improvements in device performance, stability, reproducibility, and process efficiency over other TFTs. In comparison, TFTs composed of CdSe and amorphous silicon suffer from low mobility and threshold drift effect.

There are several important advantages in the actual panel construction and drive arrangement of a TFT-organic EL device of the present invention: 1) Since both the organic EL pad and the cathode are continuous layers, the pixel resolution is defined only by the feature size of the TFT and the associated display ITO pad and is independent of the organic component or the cathode of the EL cell.

Fig. 1 is a schematic diagram of an active matrix 4-terminal TFT-EL device. T1 and T2 are thin-film-transistors, Cs is a capacitor and EL is an electroluminescent layer.

Figure 1 shows the schematic of an active matrix 4-terminal TFT-EL display device. Each pixel element includes two TFTs, a storage capacitor and an EL element. The major feature of the 4-terminal scheme is the ability to decouple the addressing signal from the EL excitation signal. The EL element is selected via the logic TFT (T1) and the excitation power to the EL element is controlled by the power TFT (T2). The storage capacitor enables the excitation power to an addressed EL element to stay on once it is selected. Thus, the circuit provides a memory that allows the EL element to operate at a duty cycle close to 100%, regardless of the time allotted for addressing.

In the TFT-EL device illustrated in Figure 2, TFT1 is the logic transistor with the source bus (column electrode) as the data line and the gate bus (row electrode) as the gate line. TFT2 is the EL power transistor in series with the EL element. The gate line of TFT2 is connected to the drain of TFT1. The storage capacitor is in series with TFT1. The anode of the EL element is connected to the drain of TFT2.

The construction of the TFT-EL of Figure 2 is shown in cross-sectional view in Figures 3-9. The cross-sectional views shown in Figures 3-8 are taken along section line A-A" in Figure 2. The cross-sectional view in Figure 9 is taken along line B-B" in Figure 2.

In the first processing step, a polysilicon layer is deposited over a transparent, insulating substrate and the polysilicon layer is patterned into an island (see Fig. 4) by photolithography. The substrate may be crystalline material such as quartz, but preferably is a less expensive material such as low temperature glass. When a glass substrate is utilized, it is preferable that the entire fabrication of the TFT-EL be carried out at low processing temperatures to prevent melting or warping of the glass and to prevent out-diffusion of dopants into the active region. Thus, for glass substrates, all fabrication steps should be conducted below 1000°C and preferably below 600°C.

Contact holes 54 and 56 are cut in the second insulating layer (see Fig. 5) and electrode materials are applied to form contacts with the thin-film-transistors (see Figs. 6 and 7). The electrode material 62 attached to the source region of TFT2 also forms the top electrode of the capacitor (see Fig. 9). A source bus and ground bus are also formed over the second insulating layer (see Fig. 2). In contact with the drain region of TFT2 is a transparent electrode material 72, preferably ITO, which serves as the anode for the organic electroluminescent material.

The foregoing examples merely represent some preferred organic materials used in the electroluminescent layer. They are not intended to limit the scope of the invention, which is directed to organic electroluminescent layers generally. As can be seen from the foregoing examples, the organic EL material includes coordination compounds having organic ligands. The TFT-EL device of the present invention does not include purely inorganic materials such as ZnS.

The on-current requirement for TFT1 is such that it is large enough to charge up the storage capacitor during the row dwell time (17 µs) to an adequate voltage (10V) in order to turn on the TFT2. The off-current requirement for TFT1 is such that it is small enough that the voltage drop on the capacitor (and TFT2 gate) during the frame period (17 ms) is less than 2%.

The on-current requirement for TFT2 is (designed to be) about 2 times the EL pixel current, 1.6µA. This factor of two allows for adequate drive current to compensate for the gradual degradation of the organic EL element with operation. The off-current of TFT2 affects the contrast of the panel. An off-current of 1 nA should provide an on/off contrast ratio greater than 500 between a lit and an unlit EL element. The actual contrast ratio of the panel may be lower, depending on the ambient lighting factor.

This power consumption excludes the power consumed by the TFTs. Since TFT2 is in series with the EL element, any source-drain voltage drop across TFT2 will result in substantial power loss in the TFT2. Assuming a source-drain voltage of 5 volts, the total power loss on TFT2 is 2 watts. The power consumption for TFT1 is estimated to be no greater than 1 watt for the 1000 x 1000 panel. The power needed for the row (gate) drivers is negligible, on the order of a few tens of milliwatts, and the power for the column (source) drivers is on the order of 0.5 watt (see S. Morozumi, Advances in Electronics and Electron Physics, edited by P.W. Hawkes, Vol. 77, Academic Press, 1990). Thus, the total power consumption for a full page TFT-EL panel is about 7 watts. Realistically, the average power consumption would be much less since the EL screen is not 100% on in average usage.

The TFT-EL panel of the present invention has two important advantages in terms of power requirements over TFT-LCD panels. First, the TFT-EL power need is relatively independent of whether the panel is monochrome or multicolor, provided that the color materials have a similar luminescent efficiency. In contrast, the TFT-LCD colored panel requires a much higher power than the monochrome panel because the transmission factor is greatly reduced in the colored panel by the color filter arrays. Second, the LCD backlight has to stay on regardless of the screen usage factor. In contrast, the TFT-EL power consumption is highly dependent on this usage factor. The average power consumption is much less since less than 100% of the EL screen is emitting at any given time in typical applications.

The patents cover driving circuits, backlights, RGB filters, and TFT array processes amongst other technologies, according to the Electronic Engineering Times.

AU Optronics and IBM also entered into a cross licence agreement about their relative LCD patents, allowing them to share those patents TFT LCD globally.

“LCD is one opportunity for Taiwan in a hundred years. It is a sunrise industry, and it’s really important we make the best of it at the end of the day.” as commented Wen-long Shi, the former Chairman of Chi Mei Corporation. He went on to say, “For the 3C industry (computers, communication and consumer electronics), the LCD can be widely used on any electronic product, from refrigerators, air-conditioners, washing machines, to computers, notebooks or mobile phones, and even cars, traffic signs or wrist watches in the future. It’s not difficult to imagine why the industry is so competitive, as LCD is applied so widely.” In this gigantic industrial chain connected by LCD technology, tons of billion dollars change hands from upstream to downstream, and LCD global production value in 2011 alone exceeded one hundred billion dollars. In this completely open market, the frequent patent infringement disputes and licensing problems have become a patent game which every LCD player has to face.

This author has collected and compiled publicly available LCD patent cases published before July 2012, of which the patent infringement cases were from Westlaw database, while licensing information, due to confidentiality reasons, was obtained mainly from news media. LCD patent disputes came into public view in 2000 when the Japanese company Sharp sued Chunghwa Picture Tubes for LCD-related infringement in Taiwan. In 2002 it again sued Chunghwa in Japan for infringing three of its patented techniques in LCD driver programs and LSI setup, for an injunction against latter from importing, and against any sale, offer for sale, display, advertisement or promotion of LCDs using such technologies. Again in 2000, Plasma Physics and Solar Physics, an American NPE (non-practicing entity), sued 9 parties including Sharp and NEC in various courts for patent infringement.

First, there is a criss-cross multilayer game in the production chain. Generally speaking, direct competing relationship exists among business competitors, and players on the same level are more likely to be competitors, among whom patent suits take place. That is not the case in the LCD industry, however, where patent disputes among players on different levels are very constant. The LCD industry can be roughly divided into three levels, namely, the upstream suppliers, including suppliers of equipment, materials, glass strata, driver ICs, optical membranes, and backlight sources, such as Corning and Anvik; the midstream panel manufacturers, representative companies including Samsung, LG, Innolux, AUO and BOE; and the downstream OEM manufacturers, mostly those that mount LCD panels to display equipment, such as Sony, Vizio, as well as Samsung, LG and Sharp. On September 17th 2003, Sharp filed a lawsuit in Californian district court, alleging patent infringement of its LCD technology against BenQ and Viewsonic, which were downstream compani e s t h a t used pane l s from AUO. In 2005, the U.S. glass manufacturer, Guardian, sued AUO, Chi Mei Corporation, Chunghwa Picture Tubes, Dell, Acer and AOC in the U.S., which were all downstream LCD manufacturers. On January 24th 2011, Sharp took simultaneous actions both in the ITC and in federal district court in Delaware against BenQ, Haier, LG, Sanyo, TCL, TTE and Vizio, for using allegedly infringing panels from AUO. On June 6th 2011, a German backlight source manufacturer, OSRAM, filed complaints both at ITC and district court in Delaware against Samsung and LG for infringement of its LED patents. On April 7th 2011, Seiko Epson sued toymakers Leapfrog and Mattel for using LCD modules from Taiwanese Giantplus Technology.

Second, new aspects are added to the game. Generally the patent game can be either patent lawsuits or patent licensing. The LCD industry has fully expounded in these two aspects. In recent years, more is added to the game, including filing patent litigation, responding and counter claiming, as well as a Section 337 investigations and customs recording. For example, during a three-year patent duel, Samsung first requested a Section 337 investigation with ITC against Sharp on December 21st 2007. After a year and a half, Samsung prevailed at ITC which found Sharp infringing two of Samsung’s patents (US6937311 and US6771344). Patent licensing comes in a variety of forms. There are primarily three cooperative modes in the panel industry: 1. Technical licensing, which is the most commonly applied form of technical cooperation. Examples include AUO’s announcement of 170 IBM TFT-LCD licenses in the US on June 30th 2005, and Samsung’s cross-licensing with Sharp after the extended patent war. 2. Joint ventures. Examples are AUO and AOC that entered into a joint venture agreement to establish companies in Poland and Brazil for manufacturing and selling LCD modules; and Samsung and Sony that joint established the panel joint venture S-LCD (however, Sony announced its total withdrawal in December 2001 for the failure of the joint venture). 3. Strategic cooperation. Examples are Hon Hai Precision Industry and Vizio that formed a strategic alliance to jointly enter the TV market in the North America; and Sharp formed a strategic alliance with Hon Hai Corporation by selling to the latter 46.5% of the shares of its Sakai Display Products (SDP).

Third, friends or foes, it depends. In the business world, there are no permanent friends, nor permanent enemies. Participants in the LCD industry may be partners today, but start to sue each other tomorrow. In January 2006, Samsung entered into an extensive cross-licensing agreement with AUO with respects to TFT-LCD and OLED-related patents. But, just before the end of the agreement, it sued AUO, together with AUO’s downstream clients, for patents infringement, at the ITC and district courts in Delaware and North California. Through the actions, as it can be said, Samsung intended to urge AUO to enter into a new crosslicensing as soon as possible. Finally on January 6th 2012, AUO announced its settlement with Samsung, whereby the parties agreed to continue to grant licenses to each other and withdraw their actions against each other, to end their LCD patent controversy.

Settlement is the preferred option. This author notices upon study that there are 300,000 LCD patent applications globally, some of which carry multiple national applications. Any given LCD panel may incorporate up to 1,000 patents, which means no one manufacturer can keep walking within the territory of its own patents, without stepping on the domain of the competitors. The best way for the LCD players to navigate through these patent entanglements as fast as possible, is to get your own patents first, then bargain the litigation through negotiation for a balancing point so as to settle for a solution. From the Samsung and Sharp controversy, to the numerous lawsuits between Sharp and AUO, and to the dispute between Innolux and Sony, statistics show that nearly 55% of such cases were settled either in or out of court, regardless of the duration and the process involved.

Concentration is in U.S. forums. Because the U.S. market is most attractive to manufacturers for its revenue-generating ability on the global scale, its judicial system being well established, and its robust protection of intellectual property, all LCD manufacturers would like to get their cases in US courts. Sharp, LG, 02Micro, Anvik, Semiconductor Energy Lab of Japan and Atomic Energy Lab of France favor filing lawsuits in US district courts, while Samsung, Sharp, Innolux, AUO and BenQ are the mostly sued, 10 times on average, in the country.

NPEs are the more troublesome. The party that raises an action for patent infringement is mostly a midstream panel maker, an upstream supplier, an R&D institution or an NPE. NPEs (or patent trolls) are often deemed as patent licensing companies. They never produce or sell any product, but obtain patents independently or through acquisition. They aim to profit by collecting royalties or compensations from manufacturers, mostly by means of licensing negotiation or patent litigation. They are the most dangerous to manufacturers for two reasons. First, it is generally easy for a company to know the patent portfolio of its competitors, so that it can formulate a strategy to avoid those patents in advance. But, it is almost impossible to know how many cards an NPE has in hand, as it often registers a number of subsidiaries. Second, if sued by a competitor, a company may settle it through cross-licensing. But, an NPE, having no actual products but patents, is not interested in cross-licensing. It goes after monetary damages only.

The recent NPE stories include a few cases of Modis Technology Ltd. from Britain against Innolux in the US from 2007 to 2012, Thomson Licensing in France against Innolux or AUO under Section 337 in 2010, Advanced Display Technologies of Texas in the US against 13 top global manufacturers of panels, computers and mobile phones, including AUO, Sharp, Vizio, Viewsonic, Haier, ASUS and Apple in 2011, where ADT alleged that the 13 manufacturers infringed its display patents; Technology Licensing Corporation in the US vs. ASUS and Westinghouse Electric on account of 3 of its patents being infringed; Yield Boost Tech, a Californian technical consultation and solution provider, vs. Applied Materials, the world’s largest semiconductor equipment supplier, on account of one of its patents being infringed, at the Eastern Californian court.

In 2011, the top five LCD panel makers in the world, according to their market shares, were LG, Samsung, Innolux (the new Chi Mei), AUO and Sharp. As shown, they attack and are attacked the most often with respect to the patent game of the LCD industry. As this patent game cannot be avoided even by the industrial leaders, then how about the situation of enterprises in the Mainland China? It is a surprise to find that among representative Chinese LCD manufacturers, such as BOE, CSOT, Tianma, Panda and IVO, only BOE’s subsidiary in South Korea, BOEHYDIS, was ever sued by the glassmaker Guardian in the U.S. in 2005. No other Chinese enterprises are found in the patent game. Do they own all the intellectual property rights? Is their technical leadership so powerful as to keep themselves out of the patent wrestle? Both answers are absolutely “no.” This author considers a few possible reasons. Some of them purchase whole production lines, new or used, directly from foreign manufacturers, so that they pay the royalty up front. The others reach a technical licensing agreement with foreign manufacturers in private, so that they pay the royalty but do not publish the information due to confidentiality reasons. Moreover, as most Chinese enterprises have limited market shares and their products are at the lower end, they do not create a real threat to foreign competitors in overseas markets.

The market status determines whether a company is worth being sued by other companies for patent infringement. In other words, if a company has never encountered any patent lawsuit, it does not mean it’s litigation proof, but that its status is not high enough. After all, with respect to the 300,000 patent applications globally in the LCD industry every year, no one manufacturer could work within its own sphere of patents without stepping on the area of domain of the other competitors.

With the support in policy and finance from the government, Chinese LCD manufacturers have been growing up. As international panel makers, particularly Samsung and LG, begin to shift their attention to OLED panels, this will very likely leave an opportunity for Chinese enterprises to acquire the global LCD market. For their greater market shares and better profiting situation, Chinese LCD manufacturers will face more criticism in intellectual property from international competitors. They must get themselves ready for coming challenges.

The LCD industry is intensive in both finance and technology and its growth cannot be without government support. When arranging the industry from upstream to downstream or causing the industry to integrate, the government should focus on promoting technical consolidation among enterprises. For technical consolidation, the government should act early to collect relevant information and intelligence with respect to patenting strategies in the LCD area, and study and analyze patent-related litigations. It can be said that a core step of consolidation is to consolidate patent assets. To understand the industrial patent game in an overall way helps enhance Chinese enterprises’ ability to use and protect their patents.

While the level of a patent war among Korea, Japan, and Taiwan over TFT LCD is escalating day by day, LG Phillips LCD has acquired the sub-license of Vertical Alignment (VA), a core technology for implementing Wide View Angle (WVA) of TFT LCD for monitor and TV, which is likely to bring about a considerable ripple effect.

The company`s aggressive action to use intellectual property rights (IPR) attracts attention. In particular, LG Phillips LCD recently sued Taiwan`s leading display maker CPT and related companies for the infringement of patent on `side mounting`, its technology of maximizing LCD screen, on a U.S. court. (See Page 28 of this paper’s Sep. 4th issue.)

LG Phillips LCD announced on Sep. 26 that it secured the sub-license of a WVA technology-related core patent held by Commissariat a l’Energie Atomique (CEA) of France.

With a sub-license, the party concerned can utilize IPR to maximize the influence of any patent rights, being allowed to exert patent rights by a company or an individual who holds source patents. Therefore, the company could grant a license of using VA patent technology to other TFT LCD makers.

The technology of implementing VA-mode WVA is one of core ones for securing wide view angles of LCD for monitor and TV. It is reportedly being used by a number of TFT LCD makers within and without, including Samsung Electronics and some major companies of Taiwan.

Concerning this issue, the company said, "As we have acquired rights to grant a patent license, we are going to take official steps related with the use of patent technology sooner or later toward global LCD manufacturers that are applying VA technology."

As the largest government-invested research center in France that holds a number of FPD-related source patents, including TFT LCD, CEA reportedly acknowledged the aggressive IPR strategy of LG Phillips and offered the sub-license of VA patent technology to the company.

Following Sharp, Hitachi, and Toshiba, LG Phillips acquired 102 cases of TFT LCD-related U.S. patents last year. Furthermore, the joint venture company signed a contract of a patent license with Lockwell Collinas, a No. 3 maker of display for aircrafts, strengthening its offensive through IPR.

"As global TFT LCD manufacturers are entering the era of limitless competition to survive, those companies holding source technologies would step up their offensive of IPR more and more," said experts."Among other things, we cannot exclude the possibility that some early starters would take advantage of IPR in an effort to prevent late comers from chasing them."

Adding to its portfolio of flat-panel patents, Taiwan?s AU Optronics has signed an agreement with IBM Corp. to acquire hundreds of Big Blue?s TFT-LCD related patents.

Under the deal, approximately 170 U.S. patents -- as well as counterpart patents in Japan, Korea and Taiwan, among other countries -- will be transferred to AU Optronics. The patents cover various key TFT-LCD-related technology, including TFT array process (TFT structure production); cell process, such as one-drop fill technology; RBG color filter; and backlight and TFT driving circuits.

IBM ceased manufacturing TFT-LCDs in 2001, but it maintained its TFT-LCD patents. Armed with those patents, AUO is now poised to boost its intellectual property position.

?The transfer of these important fundamental patents from IBM is the largest number of TFT-LCD related patents acquired in Taiwan,? AU Optronics President HB Chen said in a statement. ?It not only elevates the company"s intellectual property position, but also helps us to preserve the interest of our customers."

A 1999 technology transfer and license agreement with IBM resulted in AU Optronics building Taiwan"s first Generation 3.5 TFT-LCD fabrication facility. Since then, the company went on to pioneer Generation 4, 5 and 6 fabs in Taiwan.

In 2006, it merged with Quanta Display Inc. to create a larger TFT-LCD manufacturer with a leading position in the world"s TFT-LCD market. AUO is the first TFT-LCD manufacturer to be successfully listed on the New York Stock Exchange (NYSE). AUO extended its market to the green energy industry in late 2008. The display and solar businesses were established as the company"s two core businesses in 2010.