patents tft lcd globally factory

The present invention generally relates to a capacity allocation method, and more particularly to a system and method of planning global logistics for a TFT-LCD manufacturing industry.

Being aware of multiple competitors investing in next generational capacities and the labor costs involved, TFT-LCD panel manufacturers usually perform front-end manufacturing at the technology-intensive place. On the other hand, LCD Module (LCM) assembly is performed at the place of demand. Practically, experience dominates the capacity allocation strategy for specifying the appropriate products to produce at a specific manufacturing location. Therefore, the aforementioned techniques affect the performance of the enterprises.

The present invention is directed to a method and a system for planning a global logistics system of a TFT-LCD manufacturing industry, thereby obtain a global logistical and capacity allocation plan.

The present invention provides a global logistics system for a TFT-LCD manufacturing industry suitable for globally allocating among multiple front-end TFT-LCD manufacturing factories and multiple back-end LCM factories. The front-end TFT-LCD manufacturing factories generate multiple semi-finished products. The back-end LCM factories receive these semi-finished products for module assembly. The global logistics system includes an input module and an industry characteristic planning module that has a front-end process transformation module and a back-end transportation allocation module. The input module is used for selecting a performance index and for entering the related parameters. The industry characteristic planning module is used for receiving the performance index and the related parameters. Herein, the front-end process transformation module calculates each semi-finished product quantity at each of the front-end TFT-LCD manufacturing factories. The calculation is performed according to the manufacturing parameters in order to estimate a glass substrate input quantity for each of the front-end TFT-LCD manufacturing factories. The back-end transportation allocation module calculates a shipping quantity. The shipping quantity of each semi-finished product is transported from each front-end TFT-LCD manufacturing factory to each back-end LCM factory. The back-end transportation allocation module calculates the total input quantity of semi-finished products received by each of the back-end LCM factories from each of the front-end TFT-LCD factories.

In one embodiment of the present invention, the aforementioned front-end process transformation module includes a capacity equivalent transformation module, an economical cutting rate transformation module, a cutting area loss transformation module, a manufacturing feasibility evaluation module, a demand limitation module, and a front-end resource limitation module. The capacity equivalent transformation module references a resource consumption quantity for manufacturing standard product in order to convert the resource consumption quantity into a capacity equivalent. The economical cutting rate transformation module calculates a glass substrate input quantity according to the semi-finished product cutting rate. The cutting area loss transformation module calculates a glass substrate loss area. The manufacturing feasibility evaluation module is used for determining whether the semi-finished products can be produced in each of the front-end TFT-LCD manufacturing factories. The demand limitation module limits the semi-finished product quantity. The front-end resource limitation module limits the semi-finished product quantity.

In one embodiment of the present invention, the aforementioned back-end transportation allocation module includes a shipping quantity distribution module, an input quantity calculation module, an inventory transformation module, an inventory limitation module, and a back-end resource limitation module. Herein, the shipping quantity distribution module calculates the shipping quantity of each semi-finished product from each of the front-end TFT-LCD manufacturing factories to each of the back-end LCM factories. The input quantity calculation module calculates a total input quantity of the semi-finished products for each of the back-end LCM factories. The semi-finished product inventory transformation module calculates the inventory quantity of each semi-finished product. The inventory limitation module limits the inventory quantity according to a storage space. The back-end resource limitation module limits a product quantity according to the available capacity.

In another perspective, the present invention provides a method for planning global logistics of a TFT-LCD manufacturing industry that is suitable for multiple front-end TFT-LCD manufacturing factories and multiple back-end LCM factories, where the front-end TFT-LCD manufacturing factories produce multiple semi-finished products, and where the back-end LCM factories receive the semi-finished products for module assembly. In the method of the present invention, a performance index and a plurality of related parameters are entered. The related parameters include manufacturing parameters and shipping parameters. Thereafter, each semi-finished product quantity at each of the front-end TFT-LCD manufacturing factories is calculated. Thereafter, respective calculations of a shipping quantity of each semi-finished product to transport from each of the front-end TFT-LCD manufacturing factories to each of the back-end LCM factories are performed. Thereafter, the total input quantity of the semi-finished products is calculated.

In one embodiment of the present invention, the aforementioned process of the semi-finished product quantity calculation includes calculating the capacity equivalent. Furthermore, whether each semi-finished product is producible at each front-end TFT-LCD manufacturing factory is determined. A cutting area loss transformation module calculates a glass substrate loss area for the semi-finished products.

After the aforementioned process of calculating the shipping quantity of each semi-finished product, an inventory quantity at each of the front-end TFT-LCD manufacturing factories is calculated.

In one embodiment of the invention, the aforementioned inventory calculation process can be limited according to a storage space at each of the front-end TFT-LCD manufacturing factories.

In summary, embodiments of the present invention may generate a production plan for the front-end TFT-LCD manufacturing factories, a resource allocation plan for the back-end LCM factories, and a shipping plan for transportation between the front-end and back-end factories. Accordingly, production costs are substantially lowered due to more efficient global logistics planning.

Practically, production planning for the TFT-LCD manufacturing industry is usually performed by spreadsheet software while capacity allocation is determined by experience. The aforementioned technique results in performance limitations in businesses. In light of the foregoing, in order to more effectively reduce production costs, the present invention provides a system and a method of planning global logistics of a TFT-LCD manufacturing industry. In order to facilitate the descriptions, the embodiments below use the TFT-LCD manufacturing industry as an example.

FIG. 1 is a schematic view of a global logistics environment in accordance with one embodiment of the present invention. Referring to FIG. 1, an enterprise has determined a production quantity from analyzing customer orders and historical data. Input data is represented by various sized product quantities of each period. A production need is allocated to each of front-end TFT-LCD manufacturing factories.

The work environment of the TFT-LCD manufacturing industry can be partitioned into two stages: a first stage involves setting a glass substrate input quantity and a resource allocation for each of the front-end TFT-LCD manufacturing factories 1˜n; a second stage involves capacity logistics planning, which requires determining an optimal logistics allocation plan and thereafter, using the allocation plan to transport semi-finished products to the back-end LCM factories 1˜m for module assembly.

The first stage includes the following industry characteristics. A capacity calculation is based on a capacity for producing a standard product, as well as a capacity equivalent for producing other products. When producing a panel, capacity utilization takes into account an economical cutting rate. Moreover, various degrees of glass substrate loss can occur since different front-end TFT-LCD manufacturing factories utilize different economical cutting rates.

In addition, the second stage includes the following characteristics. The semi-finished products are produced by the array and cell processes, and they are stored as panels at the front-end TFT-LCD manufacturing factories awaiting transport to the back-end LCM factories for module assembly. A shipping quantity between the TFT-LCD manufacturing factories and LCM factories is determined.

In addition to the manufacturing parameters and the shipping parameters, the related parameters further includes a front-end TFT-LCD manufacturing factory generation number, economical cutting rate, and glass substrate cutting loss rate. In addition, a planning period index is included for determining the long-term capacity allocation. A factory index is included for determining each front-end TFT-LCD manufacturing factories and the back-end LCM factories. A product type index is applied for determining the number of product types to allocate.

In addition, the industry characteristic planning module 220 is adapted for receiving the performance index and the related parameters. Herein, the front-end process transformation module 221 calculates the semi-finished product quantity for estimating the glass substrate input quantity. The calculation references the performance index and is performed according to the manufacturing parameters. The back-end transportation allocation module 223 respectively calculates a shipping quantity of each semi-finished product to transport from each of the front-end TFT-LCD manufacturing factories to each of the back-end LCM factories. The back-end transportation allocation module 223 calculates the semi-finished product quantity received by each of the back-end LCM factories from each of the front-end TFT-LCD manufacturing factories.

The economical cutting rate transformation module 303 calculates the glass substrate input quantity according to the semi-finished product quantity. Since different generation manufacturing factories use specific size of panel, producing products of different sizes results in a different economical cutting rate. Accordingly, during resource allocation for the TFT-LCD manufacturing industry, utilizing rates are considered for their economical benefit. During production, conversion between the glass substrate input quantity and the semi-finished product quantity is performed by considering the glass substrate area, the product size, and the product quantity at each generation factory. The conversion can be described as:

A manufacturing feasibility evaluation module 307 is used for determining whether the semi-finished products can be produced. The determination is made by using a manufacturing feasibility parameter. In general, not all front-end TFT-LCD manufacturing factories have the capability to produce products of all sizes under the consideration of production technology.

In each planning period, the capacity used by each front-end TFT-LCD manufacturing factory should be less than or equal to ep,i, a capacity limiting quantity.

Furthermore, in the back-end transportation allocation module 223, the shipping quantity distribution module 313 respectively calculates a shipping quantity from each of the front-end TFT-LCD manufacturing factories to each of the back-end LCM factories. The shipping quantity distribution module 313 particularly emphasizes on parameters such as shipping feasibility, shipping quantity limitation, and back-end assembly feasibility in order to generate a workable shipping plan. For instance:

In each planning period, the capacity used by each back-end TFT-LCD manufacturing factory should be less than or equal to a capacity limitation quantity.

After inputting the related parameters and the performance index into the industry characteristic planning module 220, primary results received by the front-end process transformation module 221 and the back-end transportation allocation module 223. The primary results include the glass substrate input quantity, the shipping quantity to transport from the front-end TFT-LCD manufacturing factories to the back-end LCM factories, and the total input quantity of semi-finished products received by the back-end LCM factories. In other words, the resource allocation plan for the front-end TFT-LCD manufacturing factories is determined. Furthermore, the resource allocation plan for the back-end LCM factories is determined. In addition, the global logistics plan is determined by the shipping quantity.

Besides the aforementioned primary results, some secondary results are gathered from calculations performed by the module 221 and module 223. These secondary results include a resource remaining quantity, a glass substrate cutting loss area, and an inventory quantity. More specifically, the resource remaining quantity is calculated by using the economical cutting rate transformation module 303, and thereafter using the capacity equivalent transformation module 301 to convert the semi-finished product quantity to the resource remaining quantity. Accordingly, the resource remaining quantity represents a capacity that is available to receive more orders or bypass other orders. The glass substrate loss area for the front-end TFT-LCD manufacturing factories is determined by the cutting loss area transformation module 305. Furthermore, the inventory quantity of semi-finished products at the front-end TFT-LCD manufacturing factories is determined by the economical cutting rate transformation module 303.

FIG. 4 is a flow chart of the method for planning global logistics. Referring to FIG. 4, as depicted in Step S405, the performance index is defined, and a plurality of related parameters is inputted. Thereafter, in Step S410, the semi-finished product quantity is calculated. While calculating the semi-finished product quantity, the capacity equivalent is calculated. The calculation, which references a resource consumption quantity of a standard product, converts the resource quantity into the capacity equivalent. Furthermore, whether each semi-finished product is producible is determined by the manufacturing feasibility parameter. In addition, the glass substrate cutting loss area of each of the front-end TFT-LCD manufacturing factories is calculated by taking into account the glass substrate cutting loss rate.

Thereafter in Step S415, calculation of the shipping quantity for transport from each of the front-end TFT-LCD manufacturing factories to each of the back-end LCM factories is performed respectively. In addition, calculation of the inventory quantity of the semi-finished product at each of the front-end TFT-LCD manufacturing factories is performed. The inventory quantity is limited by the storage quantity at each of the front-end TFT-LCD manufacturing factories.

Thereafter, as shown in Step S420, the total input quantity is calculated according to the semi-finished product quantity received by each of the back-end LCM factories from each of the front-end TFT-LCD manufacturing factories.

FIG. 5A to FIG. 5K are schematic views showing a plurality of input and output data. The basic settings for the present embodiment are as follows: a unit of the planning period is a month (12 planning periods); 4 front-end TFT-LCD manufacturing factories (Fab1-Fab4); 4 back-end LCM factories (LCM1-LCM4); there are 47 products each needing a glass substrate input quantity for each month. Herein, FIG. 5A to FIG. 5H represent input data, while FIG. 5I to FIG. 5K represent output data. When the related parameters shown in FIG. 5A to FIG. 5H are entered into the module 220, calculation by the module 221 and the module 223 arrive at the results shown in FIG. 5I to FIG. 5K.

FIG. 5A, FIG. 5C, FIG. 5D, and FIG. 5E respectively show the economical cutting rate, the glass substrate cutting loss rate, the capacity equivalent, and the manufacturing feasibility of the front-end TFT-LCD manufacturing factories Fab1-Fab4. FIG. 5B shows the market demand. FIG. 5F, FIG. 5G, and FIG. 5H show the shipping parameters. FIG. 5F and FIG. 5G respectively show the shipping feasibility and the shipping quantity limitation for transport between the back-end LCM factories LCM1-LCM4 and the front-end TFT-LCD manufacturing factories Fab1-Fab4. FIG. 5H shows the shipping cost of each product for the back-end factories LCM1-LCM4.

On the other hand, FIG. 5I and FIG. 5J use January as example, while FIG. 5K uses the front-end TFT-LCD manufacturing factory Fab3 as an example. FIG. 5I shows the allocation plan for each product"s glass substrate input quantity at each of the front-end TFT-LCD manufacturing factories Fab1-Fab4. FIG. 5J shows each product"s total input quantity of semi-finished products after January at the back-end LCM factories LCM-LCM4. FIG. 5K shows the shipping quantity of each product that is transported from the front-end TFT-LCD manufacturing factory Fab3 to the back-end LCM factories LCM1-LCM4.

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.

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.

H01L27/1214—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being other than a semiconductor body, e.g. an insulating body comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs

H01L27/1214—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being other than a semiconductor body, e.g. an insulating body comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs

A thin film transistor liquid crystal display (TFT-LCD) pixel structure comprising: a gate line and a gate electrode formed on a substrate; a first insulating layer, a semiconductor layer, and a doped semiconductor layer formed sequentially on the gate electrode and the gate line, wherein an isolating groove is formed above the gate line which disconnects the semiconductor layer on the gate line; a second insulating layer covering the isolating groove and a portion of the substrate where the gate line and the gate are not formed; a pixel electrode formed on the second insulating layer, wherein the pixel electrode is integral with a drain electrode and is connected with the doped semiconductor layer on the gate electrode at a place where the drain electrode is formed; a source electrode, which is a portion of a data line, formed on the doped semiconductor layer; and a channel formed between the source electrode and the drain electrode.

The present invention relates to a method of manufacturing a thin film transistor liquid crystal display (TFT-LCD) and the TFT-LCD thus manufactured. BACKGROUND OF THE INVENTION

At present, a liquid crystal displays (LCD) exemplified by a TFT-LCD has become one very important type of flat panel displays and has attracted extensive attention. During manufacture of a TFT-LCD, efforts have been made to adopt a more advanced manufacturing method, simplify producing process, and reduce production cost. Among the others, simplification of process and the reduction of production cost for each device of a TFT-LCD directly lead to the simplification of manufacturing process and the reduction of production cost of the whole TFT-LCD.

A LCD generally comprises an upper substrate and a lower substrate which are joined together by a seal agent. Electrodes are formed on the upper and lower substrates, and liquid crystal material is filled between the two substrates. Particles of a certain diameter are distributed between the two substrates to maintain a constant gap between the two substrates. A thin film transistor (TFT) is formed on the surface of the lower substrate as a switching element. The TFT can comprise a gate electrode connected with a gate line, a source electrode connected with a signal line, and a drain electrode connected with a pixel electrode. Specifically, the TFTs used for a TFT-LCD commonly comprise a gate electrode which may be a portion of the gate line, an active layer (comprising a semiconductor layer and a doped semiconductor layer) which forms a channel, a source electrode which may be a portion of the data line, and a drain electrode which opposes the source on the active layer and is electrically connected with the pixel electrode. The TFT, as a switching element, controls, under the electrical signal transmitted to the gate electrode through the gate line, the transmission of the data signal transmitted through the data line to the pixel electrode.

In recent years, in a conventional method of manufacturing a TFT-LCD, an array forming process is widely used, in which patterning processes by photolithography with a mask are performed for several times on a glass base substrate to form a TFT array. Since the mask for exposing is very expensive, it is an efficient method to decrease production cost by reducing the times of photolithography with a mask. However, decrease of the times of photolithography with a mask may render other processes in manufacturing a TFT-LCD complicated and may even make impossible to carry out such processes.

One currently popular method of manufacturing a TFT-LCD is a four-mask method, in which photolithography processes are carried out for four times, for which four masks are needed. In addition, processes such as deposition, etching, and/or stripping are necessary for forming a pattern. In the four-mask manufacturing method, a gray tone mask technology can be used for etching to form the source/drain metal electrodes and the channel portion of the active layer of the TFT. The fabrication of these portions is the key for manufacturing a TFT-LCD, which, in practice, imposes rigorous requirements on etching selectivity and the photolithography process and further brings complication to the manufacturing process.

Therefore, there is a need for a method of manufacturing a TFT-LCD which uses less masks and which is also simple in procedure and easy to carry out. SUMMARY OF THE INVENTION

An embodiment of the invention provides a thin film transistor liquid crystal display (TFT-LCD) pixel structure comprising: a gate line and a gate electrode formed on a substrate; a first insulating layer, a semiconductor layer, and a doped semiconductor layer formed sequentially on the gate electrode and the gate line, wherein an isolating groove is formed above the gate line which disconnects the semiconductor layer on the gate line; a second insulating layer covering the isolating groove and a portion of the substrate where the gate line and the gate are not formed; a pixel electrode formed on the second insulating layer, wherein the pixel electrode is integral with a drain electrode and is connected with the doped semiconductor layer on the gate electrode at a place where the drain electrode is formed; a source electrode, which is a portion of a data line, formed on the doped semiconductor layer; and a channel formed between the source electrode and the drain electrode.

Another embodiment of the invention provides a method for manufacturing a thin film transistor liquid crystal display (TFT-LCD) pixel structure comprising the following steps:

(II) depositing sequentially a pixel electrode layer and a source/drain electrode layer on the substrate after step I, forming a second photoresist pattern with a second gray tone mask to comprise a second non-photoresist region, a second partially retained photoresist region and a second fully retained photoresist region; etching the second non-photoresist region to form a channel of a TFT, a pixel electrode and a drain electrode which is integral with the pixel electrode, and a data line and a source electrode which is integral with the data line; ashing the second photoresist pattern to remove the photoresist in the second partially retained photoresist region to expose the source electrode and the data line and thin the photoresist in the second fully retained photoresist region; depositing a passivation layer, lifting off the remained second photoresist pattern along with the passivation layer deposited thereon on the pixel electrode, and etching the source/drain electrode layer in the region on the substrate corresponding to the pixel electrode and the drain electrode to expose the pixel electrode.

The TFT-LCD pixel structure and the manufacturing method thereof according to the embodiments of the present invention can reach the following advantages.

A second insulating layer is deposited during the first photolithography process so that the pixel structure can be planarized, which provides process tolerance for subsequent processes. In addition, a portion of the transparent pixel electrode is also used as the drain electrode of the TFT, which can avoid the problem about contact resistance.

As compared with the conventional method, two masks can be used to manufacture a TFT-LCD pixel structure, the number of masks can be decreased, the cost for the array process and the seizing time can be reduced, and the production volume and yield can be improved. In addition, since the number of the masks and also exposure processes is decreased, the complication of the process can be reduced, the process tolerance can be increased, and the production volume and yield can be improved.

Here, all the processes with the first gray tone mask have been described, and the plan view of the pixel structure after the processes are completed is shown in FIG. 1′. As can be seen from the above processes, in the present embodiment, a second insulating layer is deposited during the first photolithography process so that the pixel structure is planarized, which provides process tolerance for subsequent processes. In addition, the conventional gray tone mask and lift-off process for manufacturing a TFT-LCD can be used in the first photolithography process, which makes the first photolithography process easy to implement.

Then, a passivation layer 24 is deposited on the resultant structure, as shown in FIG. 2D. A lift-off process is carried out to remove the photoresist 23′ together with the passivation layer deposited thereon. The cross-sectional view along line A-A′ in FIG. 2 after the lift-off process is shown in FIG. 2E. Since the region corresponding to the source electrode 203 and the data line is protected by the passivation layer, an etching process is carried out on the pixel electrode region to etch away the source/drain electrode layer 22 in the region corresponding to the pixel electrode to be formed and expose the transparent pixel electrode layer 21 as the pixel electrode, as shown in FIG. 2F. In this way, the manufacturing process of the TFT-LCD pixel structure is completed here.

Furthermore, during the second gray tone photolithography process in the above embodiment, a portion of the transparent pixel electrode is also formed as the drain electrode of the TFT, which can avoid the problem about contact resistance.

Two masks can be used in the embodiment of the present invention to manufacture a TFT-LCD, thus the number of mask can be decreased, the cost for the array process and the occupation time can be reduced, and the production volume and yield can be improved compared with the conventional method. In addition, the conventional gray tone photolithography process and the lift-off process can be employed, which makes simple and convenient to implement the complete process.

The TFT manufactured by the method described above comprises a substrate 100, a gate line 101, a first insulating layer 12, a semiconductor layer 13, a doped semiconductor layer 14, a second insulating layer 16, a source electrode 203 which is a portion of a data line, a drain electrode 204 which is a portion of a pixel electrode, and a passivation layer 24. In the pixel structure of the embodiment of the present invention, the first insulating layer 12, the semiconductor layer 13, and the doped semiconductor layer 14 are disposed sequentially over the gate 102 and the gate line 101, the isolating groove 103 is formed on the gate line 101 and disconnects the semiconductor layer on the gate line, the second insulating layer 16 covers the isolating groove 103 as well as the portion of the substrate where the gate line 101 and the gate 102 are not formed, the transparent pixel electrode layer 21 is retained under the source electrode 203 which is integral with the data line, the drain electrode 204 which is integral with the pixel electrode is formed over the second insulating layer 16, that is, the pixel electrode is connected with the doped semiconductor layer 14 on the gate 102 at the place where the drain electrode 204 is formed, and the passivation layer 24 covers the portion of the substrate where the pixel electrode 204 is not formed, i.e., exposes the pixel electrode 204.

In the embodiment described above, description is made by reference to the structure with one TFT and the manufacturing process thereof. There can be formed a plurality of TFTs on the substrate, and the TFTs can be manufactured simultaneously by the photolithography processes, in which case the isolating groove on the gate line can prevent the short circuit among the data lines.

(II) depositing sequentially a pixel electrode layer and a source/drain electrode layer on the substrate after step I, forming a second photoresist pattern with a second gray tone mask to comprise a second non-photoresist region, a second partially retained photoresist region and a second fully retained photoresist region; etching the second non-photoresist region to form a channel of a TFT, a pixel electrode and a drain electrode which is integral with the pixel electrode, and a data line and a source electrode which is integral with the data line; ashing the second photoresist pattern to remove the photoresist in the second partially retained photoresist region to expose the source electrode and the data line and thin the photoresist in the second fully retained photoresist region; depositing a passivation layer, lifting off the remained second photoresist pattern along with the passivation layer deposited thereon on the pixel electrode, and etching the source/drain electrode layer in the region on the substrate corresponding to the pixel electrode and the drain electrode to expose the pixel electrode.

In recent years, the conventional cathode ray tube (CRT) products have been gradually replaced by thin film transistor (TFT) liquid crystal displays (LCDs). TFT-LCD manufacturers have to increase their production capacities to fulfil the increasing market demand.

The capacity planning in TFT-LCD panel manufacturing industry has to balance between multiple objectives. For example, the business sector expects to maximize the throughput, while the production sector focuses on the effective utilization of glass substrate.

Accordingly, how to obtain an appropriate multi-objective capacity planning is one of the major issues in today"s TFT-LCD panel manufacturing industry.

The present invention is directed to a multi-objective capacity planning system in the TFT-LCD panel manufacturing industry, wherein a graph illustrating the relationship between multiple conflictive objectives is provided such that an appropriate capacity planning plan can be selected.

The present invention is directed to a multi-objective capacity planning method in the TFT-LCD panel manufacturing industry, wherein a graph illustrating the relationship between multiple conflictive objectives is provided such that an appropriate capacity planning plan can be selected.

The present invention provides a multi-objective capacity planning system in the TFT-LCD panel manufacturing industry. The multi-objective capacity planning system includes an input module, a capacity planning module, a multi-objective planning module, and an output module. The input module inputs characteristic parameters of the TFT-LCD panel manufacturing industry. The capacity planning module provides a first objective and a second objective, wherein the first objective is to minimize a glass substrate loss area, and the second objective is to maximize the throughput. The multi-objective planning module provides a set of constraints of the first objective and a set of constraints for the second objective respectively, wherein the first set of constraints is a lower limit of the throughput, and the second set of constraints is an upper limit of the glass substrate loss area. The capacity planning optimization module respectively calculates outputs of the first objective and outputs of the second objective. The output module respectively draws a first curve and a second curve in a graph according to the outputs of the first objective and the outputs of the second objective and selects an output on the boundaries of the area enclosed by the first curve, the second curve, and the axes of the graph.

The present invention further provides a multi-objective capacity planning method in the TFT-LCD, panel manufacturing industry. First, multiple characteristic parameters of the TFT-LCD panel manufacturing industry are input. Then, a first objective and a second objective are provided, and a throughput and a raw material input of a panel manufacturing factory are respectively evaluated according to the characteristic parameters, wherein the first objective is to minimize a glass substrate loss ratio of the panel manufacturing factory, and the second objective is to maximize the throughput of the panel manufacturing factory. Next, a set of constraints of the first objective and a set of constraints of the second objective are established, wherein the first set of constraints is a lower limit of the throughput, and the second set of constraints is an upper limit of the glass substrate loss ratio. After that, the first objective and the second objective are respectively calculated according to the first set of constraints and the second set of constraints. Finally, a first curve and a second curve are respectively drawn in the graph according to the outputs of the first objective and the outputs of the second objective, and an output is selected on the boundaries of the area enclosed by the first curve, the second curve, and the axes of the graph.

FIG. 2 is a flowchart of a multi-objective capacity planning method in the TFT-LCD panel manufacturing industry according to an embodiment of the present invention.

In the TFT-LCD manufacturing industry, the objective to maximize throughput conflicts with the objective to minimize the cutting waste of glass substrate. The present invention provides a system and a method of capacity planning in the TFT-LCD manufacturing industry such that an appropriate capacity planning plan can be selected among multiple conflictive objectives.

The input module 110 inputs characteristic parameters of the TFT-LCD manufacturing industry into the capacity planning module 120. In the present embodiment, the input module 110 may be a user interface for the user to input various parameters.

Below, a multi-objective capacity planning method in the TFT-LCD panel manufacturing industry will be described by referring to the multi-objective capacity planning system 100 described above. FIG. 2 is a flowchart of a multi-objective capacity planning method according to an embodiment of the present invention. Referring to both FIG. 1 and FIG. 2, first, in step S205, the input module 110 inputs characteristic parameters of the panel manufacturing factory into the capacity planning module 120, wherein the characteristic parameters includes a theoretical capacity, a market demand, an allocation feasibility, a qualified product yield, a substrate cutting utilization ratio, a substrate economic cutting number, and a capacity weight.

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

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

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

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

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

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

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

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

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

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

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

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

Kawamoto, H. (2012). "The Inventors of TFT Active-Matrix LCD Receive the 2011 IEEE Nishizawa Medal". Journal of Display Technology. 8 (1): 3–4. Bibcode:2012JDisT...8....3K. doi:10.1109/JDT.2011.2177740. ISSN 1551-319X.

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

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 a