patents tft lcd globally quotation

2023-01-03 12:32:11

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.

[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.

patents tft lcd globally quotation

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.

patents tft lcd globally quotation

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.

patents tft lcd globally quotation

of a technology market is not synchronous to technology [10] Pénin, J., “Strategic uses of patents in markets for technology: A story

takes into account information on patents granted by the U.S. directly observed patent value - An empirical analysis of Ocean Tomo

obtained for patents granted by non-U.S. organizations, this for exploiting patented technological knowledge assets in the markets

related technologies and applications using the same analysis of global patents and trademarks,” Technological Forecasting

patents tft lcd globally quotation

Universal Display Corporation is a developer and manufacturer of organic light emitting diodes (OLED) technologies and materials as well as provider of services to the display and lighting industries. It is also an OLED research company. Founded in 1994, the company currently owns or has exclusive, co-exclusive or sole license rights with respect to more than 3,000 issued and pending patents worldwide for the commercialization of phosphorescent based OLEDs and also flexible, transparent and stacked OLEDs - for both display and lighting applications. Its phosphorescent OLED technologies and materials are licensed and supplied to companies such as Samsung, LG, AU Optronics CMEL, Pioneer, Panasonic Idemitsu OLED lighting and Konica Minolta.

OLEDs can be printed onto any suitable substrate by an inkjet printer or even by screen printing,plasma displays. However, fabrication of the OLED substrate is more costly than that of a TFT LCD, until mass production methods lower cost through scalability. Roll-to-roll vapour-deposition methods for organic devices do allow mass production of thousands of devices per minute for minimal cost, although this technique also induces problems in that devices with multiple layers can be challenging to make because of registration, lining up the different printed layers to the required degree of accuracy.

OLEDs can enable a greater artificial contrast ratio (both dynamic range and static, measured in purely dark conditions) and a wider viewing angle compared to LCDs because OLED pixels emit light directly. OLED pixel colors appear correct and unshifted, even as the viewing angle approaches 90° from normal.

LCDs filter the light emitted from a backlight, allowing a small fraction of light through. So, they cannot show true black. However, an inactive OLED element does not produce light or consume power, thus allowing true blacks.

OLEDs also can have a faster response time than standard LCD screens. Whereas LCD displays are capable of between 1 and 16 ms response time offering a refresh rate of 60 to 480 Hz, an OLED theoretically can have a response time less than 0.01 ms, enabling a refresh rate up to 100,000 Hz . OLEDs also can be run as a flicker display, similar to a CRT, in order to eliminate the sample-and-hold effect that creates motion blur on OLEDs.

While an OLED will consume around 40% of the power of an LCD displaying an image that is primarily black, for the majority of images it will consume 60–80% of the power of an LCD. However, an OLED can use more than three times as much power to display an image with a white background, such as a document or web site.

"Phablets" are defined as a device that has a screen between 5 and 7 inches and is part phone-part tablet. Examples include the Galaxy Note I, II and III. Samsung unveiled their Galaxy Note 3 at the IFA electronics show in September 2013. The Galaxy Note 3 has a 5.7 inch AMOLED screen.Galaxy Note 3 and say it is the best OLED screen they have tested and is superior to all LCD screens they have tested.

With the arrival of Quantum Dot LCD displays, LG released an article describing why they still see OLED as the future of Television displays: "In fact, OLED technology is the technology that is so much advanced that it should not be compared to an LCD based QD. Hence, even though LG already has the technology to create QD backlighting, it is focusing on developing OLED".

Consumer Reports, an American Magazine covering reviews of consumer products, published their review of OLED televisions saying that their TV project leader, Claudio Ciacci, would pick LG"s OLED TV over every other TV model tested in 2014. "It has all the advantages of both LCD and Plasma Televisions without any of the weakness."

The Flexible Display Center announced that it has successfully manufactured the world"s largest flexible color AMOLED prototype using advanced mixed oxide thin film transistors (TFTs). Measuring 7.4 diagonal inches, the device was developed at the FDC in conjunction with Army Research Labs scientists. It also meets a critical target set by the U.S. Department of Defense to advance the development of full-color, full-motion video flexible OLED displays for use in thin, lightweight, bendable and highly rugged devices.

In 2012, UDC reported two favorable patent decisions. The first one is from Japan, regarding two patents (JP781 and JP158) relating to UDC"s L2MX technology. The patents were upheld as valid by the Japanese patent office. The second decision related to one of the OVJP patents in Korea. The Korean patent office issued a favorable decision which upheld the patent as valid.

Thin film transistor-liquid crystal display (TFT-LCD) is known as the display required for the high pixel density and quality. In general, the TFT-LCD includes a bottom plate formed with thin film transistors and pixel electrodes and a top plate formed with color filters. The liquid crystal is filled between the top plate and the bottom plate. In each unit pixel, a capacitor and a further capacitor are provided which are formed by virtue of the TFT serving as the switching element of the unit pixel. In the operation, a gate signal voltage is applied to the TFT that is the switching element of each unit pixel. The TFT receives the gate signal voltage, it is turn on so that data voltage carrying image information can be applied to the corresponding pixel electrode and the liquid crystal via the TFT. When the data voltage is applied to the TFT, the arrangement of the liquid crystal moleculers is change, thereby changing the optical properties and displaying the image. Supplying of voltage to each pixel electrode is carried out via a single line by a corresponding thin film transistor which is switched by a gate voltage supplied via a gate bus line.

In U.S. Pat. No. 5,166,086 proposed by Takeda et al., he disclosed a method to form a TFT-LCD. In the patent, Takeda provides a TFT array with reduced parastic capacitances. Further, Possin et al. disclosed a method to form a TFT-LCD by using back-side photoresist exposure. Please refer to U.S. Pat. No. 5,010,027. Possin teaches a method for forming a self-aligned thin-film transistor which controls the overlap width of the gate electrode with each source and drain electrode to an optimum distance.

Typically, the channel region of the self-aligned TFT-LCD is defined by the gate structure as a mask. The lightly doped drain (LDD) region or the offset structure is formed by a further photomask. The object of the present invention is to provide a method to form the offset structure without a further photomask as aforesaid.

The present is to form a TFT-LCD having a offset structure. The present invention includes patterning a metal layer on a glass substrate for serving as the gate electrode. The metal layer can be chosen from the group of chromium (Cr), tungsten (W), titanium (Ti), tantalum (Ta) or molybdenum (Mo). Next, a dielectric layer is formed on the gate for isolation. An amorphous silicon layer having hydrogen ions (a-Si:H) is subsequently formed on the dielectric layer. A first positive photoresist is formed on the amorphous silicon layer. Then, a back-side exposure is used using the gate electrodes as a mask. A bake step is performed at a temperature 140 to 150 degrees centigrade for about 20 to 30 minutes to expand the lower portion of the photoresist. Next, a second positive photoresist layer is formed on the amorphous silicon layer and the residual first positive photoresist layer.

A method is disclosed to form a TFT-LCD. The present invention provides a method to form a TFT-LCD having a offset structure. Back-side exposure technique is used to eliminate the misalignment induced by the photolithography process. Further, at least two photoresist layers are used to construct the offset structure. As will be seen below, this technique can be used for the formation of a TFT device. Referring to FIG. 1, in the preferred embodiment, a glass substrate 2 or the like is used as an insulating transparent substrate. In a preferred embodiment, the substrate 2 is chosen from glass or quartz. Subsequently, still referring to FIG. 1, a metal layer 4 for the gate electrode is formed by using physical vapor deposition (PVD). The metal layer 4 can be chosen from the group of chromium (Cr), tungsten (W), titanium (Ti), tantalum (Ta) or molybdenum (Mo). A Cr/Al (chromium/aluminum) composition layer can also be used for serving as the gate electrode 4. The metal layer 4 is then patterned on the substrate 2. The thickness of the metal layer 4 is approximately 1500-3000 angstroms. Next, a gate isolation (dielectric) layer 6 is formed on the gate 4 for isolation. An amorphous silicon layer 8 (a-Si:H) is subsequently formed on the gate isolation layer 6. In a case, the amorphous silicon layer 8 is about 300 to 600 angstroms in thickness.

As shown in FIGS. 10, the amorphous silicon layer 8 is patterned. A further dielectric layer 16 for isolation is formed on the patterned amorphous silicon layer 8. Via holes are created by etching to expose a portion of the amorphous silicon layer 8. Next, a conductive layer 18 formed of metal, polysilicon or alloy are patterned on the dielectric layer 16 and in the via holes to contact with the amorphous silicon layer 8. The conductive layer 18 acts as the source and drain electrodes of the TFT. Referring to FIG. 10, subsequently, a passivation layer 20 formed of silicon nitride layer is deposited on the source and drain 18. Preferably, the thickness of the silicon nitride layer is about 3000 to 6000 angstroms. In a case, the silicon nitride layer can be amorphous silicon nitride having hydrogen dopant (a-SiNx :H).

Between 1976 and 1988, environmental munificence remained at the initial stage; commercial electronic products emerged from a specific market (Fig. 2a). Thus, resource munificence demonstrates a low status. However, FPD technology presents itself as a new opportunity to many industrial countries, explaining their aggressive efforts in this new frontier. In the mid-1970s, the previous technology (dynamic scattering mode, DSM-LCD) designs faded dominance, subsequently explaining the increase in the number of tie deletions. However, mainstream FPD technology is twisted nematic (TN) display technology However, in the early 1980s, TN technology began transitioning to super-twisted nematic (STN) display technology. Previous TN alliances transformed into STN technology, creating an increase in the number of links during this period.

Environment II remained in uncertainty (Fig. 2b), explaining why countries will not be eliminated entirely with a previous partnership. In the late 1980s, Japan dominated STN design technology and successfully transitioned from monochrome to color STN. During that period, Japan became the incumbent of the FPD industry. However, in the early 1990s, FPD technologies elevated to a higher stage; STN display technology transitioned to thin film transistor (TFT) display technology. Notably, TFT-LCD primary components, linkages, design concepts, and functions in products stemming from the technological developments of TFT technology differed from those during the earlier development of STN. Thus, in the mid-1990s, Japan licensed a previous technology and original equipment manufacturing from neighboring countries, e.g., Korea and Taiwan, to acquire any residual value from STN technology. Thus, network changes during this period not only demonstrated that Japan strategically transferred their technology to newcomers, but also exhibited dominant design translation. Accordingly, by the mid-1990s, FPD patents granted to newcomers South Korea and Taiwan were more likely to be cited from Japanese patents rather than US ones (Jang et al. 2009) (see Appendixes C-2 and C-3). This finding suggests that newcomers began developing a compatible technology to aggregate complementary assets in FPD technology. More specifically, the Industrial Technology Research Institute developed TFT-LCD capabilities under the auspices of the Ministry of Economic Affairs in Taiwan. Meanwhile, Korea acquired TFT technology without licensing it from Japanese incumbents (Mathews 2005). In the late 1990s, TFT-LCD became a critical component in information and communication technology (ICT) products. However, the Asian financial crisis of 1997 disrupted market domination by the Japanese.

In addition to succumbing to domestic financial pressure after the Asian financial crisis of 1997, Japan also encountered South Korean competition. Japan, thus, reinforced its Taiwan alliances to control costs and increase productivity. Restated, in the early 2000s, Korea heavily invested in fourth-generation TFT-LCD fabrication equipment and developed various applications; from ICT products to new applications in consumer electronic products such as portable media players, flat panel TVs, and digital still cameras, thus challenging Japan incumbents (Mathews 2005). Therefore, in the late 1990s, Japanese firms began licensing related technologies to Taiwan partners, with Taiwan joining in 4G TFT-LCD manufacturing in the early 2000s. Therefore, the simultaneous increase in tie creation and tie deletion demonstrated the ability of the FPD incumbents to enhance their productivity. This finding also indicates that the FPD industry culminates in quantitative competition. Furthermore, a new FPD entry barrier was posed, in which network heterogeneity (portfolio range) decreased. In the mid-2000s, Korea and Taiwan became incumbents, while emerging industrialized countries are now the challengers.

During the network churning period, FPD technology in industrialized countries provided innovation and led to a dominant design. This result implies industrialized countries hold an early technological advantage. First-mover advantages were founded upon their technological innovation and demonstrated their national innovative capacities. Therefore, Japan and the US demonstrated qualitative competition in terms of dominant FPD design. During the network expansion period, Japan became the incumbent, with abundant FPD assets during the early period and then strategically recruiting newcomers from newly industrialized countries to eliminate risks in mass production after the middle period. This result suggests environmental changes affect international technology diffusion; newly industrialized countries begin acquiring FPD-related technology and develop a local FPD industry. Therefore, the patents awarded to Korea and Taiwan showed a large citation percentage from Japan and the US. Appendix C-2 provides further details. During the network strengthening period, investment by Korea and Taiwan in 4G TFT-LCD fabrication equipment implies environmental change toward a decreasing technological uncertainty. Meanwhile, the number of patents awarded to Korea and Taiwan grew rapidly (see Appendix D). This result implies fast-followers not only demonstrate their technological progress in manufacturing advantages but also exhibit culmination in quantitative competition within the FPD industry. This evolutionary trajectory implies that different

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