TW521229B - Method of driving gates of liquid crystal display - Google Patents

Abstract

Disclosed is a method of driving a gate line in an LCD which enables to extend a line time by making different a falling time of scan signals while concurrently driving plural gate lines. In the method, scan signals which rise concurrently are applied to at least two gate lines while rendering said scan signals to fall at different timings such that said gate lines are concurrently driven and video signals are sampled by pixels corresponding to said gate lines at different falling times. The present invention makes it possible to extend a line time without lowering of the resolution or degradation of picture quality.

Description

^^ 1229

FIELD OF THE INVENTION The present invention relates to the driving technology of liquid crystal displays (LCDs), and in particular to a method of preparing a ^ characterization method, which makes the gate lines of a high-resolution liquid crystal display of a high-resolution liquid crystal display. For each gate line, • make scan two: the falling times of each other are different and the first line scan time. J. Chang's background of the invention / In general, liquid crystal displays used to display text, symbols, or graphics use the optical characteristics of liquid crystals. When an electric field is applied to the liquid crystal, the arrangement of liquid crystal molecules will With change. The liquid crystal display is a type of flat panel display, which combines liquid crystal technology and abundant technology. Thin film transistor (TFT) LCDs use thin film transistors as switching elements to turn pixels on and off (pixe I). When a thin film transistor is turned on (on) or off (off), the pixel also With startup or shutdown. Fig. 1 shows a conventional thin film transistor type LCD, which has a matrix structure formed by a plurality of cells. A unit includes a thin film transistor 132 as a switching element, a liquid crystal cell (cel 1) 134, and a charging capacitor CSTG. The source of the thin film transistor is connected to a data line (D1-D N) arranged in a column direction, and one end of the data line is connected to the source

521229 V. Description of the invention (2) Driver 120. The gate of the thin film transistor is connected to the gate line (G1 -GM) arranged in a row direction, and one end of the gate line is connected to the gate driver 110. It can be seen that Figure 1 has an M xn analysis degree. For example, SVGA level (800X600), XGA level (1024X768), and UXGA level (1600 X 1 2 0 0) 〇 source driver 1 2 0 is also called a data driver or row (c0um) driver and gate driver 110 is also called a scan driver or a row (row) driver. Referring to FIG. 1, a liquid crystal cell (cel 1) 134 is connected between a drain and a pixel electrode of the thin film transistor 132, and is disposed between the pixel electrode and a common electrode (cmm) of the upper panel. eiectr〇de). The pixel electrode is made of transparent and conductive indium tin oxide (Indium Tin Oxide I TO). When an on signal is applied to the gate of the thin film transistor, the pixel electrode transfers an applied signal. The voltage passes through the source driver 120 to the liquid crystal cell 134. The common electrode is also made of indium tin oxide (ITO) and provides a common voltage v_ to the liquid crystal monomer (ce 11) 134. For a fixed time, the charging capacitor maintains the voltage on the pixel electrode, and controls the light transmission by changing the alignment direction of the liquid crystal molecules in the liquid crystal cell (ceU) 134. One end of the charging capacitor c can be connected to a separate electrode or a gate electrode, which is called " storage on gate, " mode.

V. Description of the invention (3) In the driving of the pixel array, each liquid crystal will cause the liquid crystal's decay = image force :: drive: the voltage is applied only in one direction to the system with the opposite polarity :; The voltage ^ ^ supplied by the camera is the time voltage of the inversion mechanism. The period of this inversion mechanism is usually a frame inversion (fie 1 d voltage polarity changes at the same time, ine inversion) The voltage pole method of a line, that is, the poles of adjacent rows are inverted (do t is opposite, every frame refresh should be The pixel electrodes are straddled, so that there are four driving methods for the inversion mechanism, that is, the driving method, that is, the polarity of all the pixels is refreshed once when the electronic mother frame is refreshed; Single-scanning line; column inversion drives the opposite side, the polarity is reversed when the mother frame is refreshed; ^ version) driving method, that is, the poles of adjacent pixels. In either case, the voltage of the drain electrode of the supplied 4-film electric Ba body alternates positively or negatively to the common voltage U polarity. Schematic diagram of ㈣21 Λ gate driver. Referring to Figure 2, open pole shift: register 111, one bit quasi-converter (ί㈣ vertical synchronization; Yu and Λ buffer: register 113. #Bit register 111 receives-pulse. The level wave signal generates a continuous sweep The impulse voltage (dimensionally hifter) 112 is used to shift the scanning transfer level Li to about 30 volts. The output buffer 113 is used to provide the scanning pulse after the second bit is dried to the corresponding gate line. 521229

Figure 2 shows the most common gate driving method (ie, sequential scanning method Cptogressive scanning). Because the sequential scanning method scans only one interrogation line (or scanning line) within _2 = time UH), each interfering signal is sequentially applied to the gate line every other line scanning time (1H). However, when the liquid crystal display develops toward the trend of large screen size, the resistance and thunder of the lean line will increase the load-increasing load, so the data drive circuit will pass the charge. The molding time will be shorter and shorter ° so it will cause the pixels to resolve. The low quality of the jersey a in daytime quality, so this kind of problem must be driven by the unconventional interlace scanning method (interlace scanning). Referring to Figure ㈤, the line of the traditional intersection method "time is twice as long as the sequential scanning method. The disadvantage of d = is that the vertical resolution is reduced to -half. Yes, this pass & μ is passed to the two gates. The pixel of the line. The measurement method is different from the current trend, that is, the method of changing the positive and negative voltages of the screen resolution. SUMMARY OF THE INVENTION Method The present invention is therefore directed to the limitations and disadvantages of conventional techniques for driving the gates of one or more attributive liquid crystal displays to improve substantially.

521229 V. Problems caused by the description of the invention (5). An object of the present invention is to provide a method for driving a gate of a liquid crystal display, which enables to extend the line time without reducing the resolution. The method is to drive a plurality of gates simultaneously. The polar line, however, makes the plurality of scanning signals have different falling times. In order to achieve the above-mentioned object and advantages, the present invention provides a method for driving a gate of a liquid crystal display. The Shaw method is that the scanning signal is supplied to At least two closed electrode lines and rise simultaneously (however, the scanning signal is not simultaneously driven by the plurality of gate lines at the same time, and the video signal 5 tiger sags at different times of the falling. %, ^ Are sampled by the pixels corresponding to the gate lines. In order to make those skilled in the art of Sheng Nuoshizheng, # 兹 i nr, +, ^ ^ understand the purpose, characteristics and effects of the present invention, bismuth is described in the following specific examples, in conjunction with the detailed description such as After: The drawings provide detailed explanations of the invention; give both (fall). According to the traditional :: drive method at different times, if the gate drive signal

Page 8 521229 V. Description of the invention (6) = If supplied to the gate lines G1 and 〇2 at the same time, the same image signal will be supplied ^ All pixels sharing the same data line. However, according to the gate j driving method of the present invention, because the waveform of the first gate driving signal Gi drops first aj 1), and the pixels corresponding to a gate line are corresponding to the image signal, the first gate The waveform of the electrode driving signal G 2 drops, so the pixel corresponding to the second gate line G 2 has its corresponding image signal sampled. Therefore, according to the gate driving method of the present invention, the line scanning time can be extended by as much as 30 ° as in the sequential scanning method, and: no:: 1!? Corresponding to the pixel connected to each gate line The image scanning method was driven simultaneously by using two interrogation lines ^ Ξί. The percentage increase in line scan time mentioned here may vary depending on panel characteristics. A75Hz3 /: rf is the KA class (1024 X 768), the frame frequency. But: February: The line scan time of line Si is about 17 microseconds (#sec). The driving method can be a; τ μ # > time is about 22-30 microseconds. The fly line is used to trace the gate line of the present invention to extend the line scan time. Taking Figure 5 as an example, the i-motion method drives three idle pole lines when N is driven at the same time. Figure: == interpolar lines.

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~ As a result, the number of lines that are selected and driven at the same time increases, and _ passes a longer line scan time to expand the number of lines that can be selected. Moreover, as shown in Fig. 5, Fig. 6, and Fig. 7, the line scan of the present invention = driving of the lines in opposite directions, the driving side of the image of the same polarity, j ^ η, Ding Wu, and ordering (column) too a Reverse the mechanism of y lines and every two lines in the row direction. and. When N gate lines are driven at 2 o'clock, the inversion mechanism executes every N lines ^

According to the gate line driving method of the present invention, two gates and lines that are driven at the same time are different from each other at the time of signal decline. It may be expected that the line scan time will be extended, but even gate lines and odd gate lines may be generated. The voltage difference between △ VP. This voltage difference is due to the following reasons. The pixels of the thin film transistor LCD can be molded in the circuit diagram of FIG. 9. The D1 and D2 series data lines, G1 and (; 2 series gate lines, and ^ series liquid crystal monomers) in FIG. Among the capacitors, CSTG is a charging capacitor. CGS1 and ls2 are parasitic capacitors. Referring to Figure 9, when the gate I area dynamic signal (J 1 drops, the voltage of the liquid crystal cell k is combined with the parasitic valley CGS1 'this voltage Therefore, the voltage variation Δ Vp can be obtained from the following Equation 1:

521229 V. Description of the invention (8)

Cgsi △ Vpi = _ X (~ VG) ——Equation 1

Clc + CSTg + CGS1 + CGS2 Among them, cLC is a liquid crystal capacitor, and VG is a gate driving signal. The voltage fluctuation amount Δνρ is also generated by the parasitic capacitance ces2. In other words, when the gate signal of G2 rises, the voltage of the liquid crystal is connected to the parasitic capacitance qs2, so the voltage changes. As shown in Figure 9, the pixels connected to the odd gate lines only generate the voltage variation ΔVPi as defined by Equation 1, and the pixels connected to the even gate lines generate the voltage variation of the sum of △ VP1 and △ VP2. Where △ VP2 is defined as Equation 2: GS1

C

△ V P2

X

Clc + Cstg + Cgsi + Cgs2

C GS2

X VG Equation 2 S2

Clc + Cstg + CGS1 + CG Therefore, the voltage variation of the pixels connected to the odd gate lines is different from that of the connected pixels.

Page 11 521229 V. Description of the invention (9) The voltage variation of the pixel connected to the even gate line. This is because when the image signal is sampled to the pixel connected to the gate line G1, only the gate driving signal of one gate line G1 falls, and when the image signal is sampled to the pixel connected to the gate line to the gate line G2 The decline of the gate drive signal and the rise of the gate drive signal of the gate line G3 occur simultaneously. As a result, a voltage difference ΔVP between the even-numbered gate lines and the odd-numbered gate lines is generated, so that the picture quality may be degraded. In order to solve the above disadvantages, as shown in Fig. 10, another specific embodiment of the present invention modifies a part of the method provided by the present invention. In other words, as described above, the voltage difference Δ Vp between the even gate line and the odd gate line is due to the difference between the gate driving signal of the even gate line and the gate driving signal of the odd gate line. A specific embodiment provides that the odd gate lines and the even gate lines are in the same driving state. For example, as shown in Figure 10, the two gate lines are improperly driven, and the gate driving signals of the even gate lines G2 and G 4 fall before the gate driving signals of the odd gate lines G i and g 3 fall t, and the even gates The idle driving signals of lines G2 and G4 are turned on again when the gate driving signals of the odd-numbered gate lines G1 and G3 fall. All the even-numbered gate lines and odd-numbered gate windings are connected. The grid green pixels have the same shape I to generate a voltage difference Δv. Therefore, the problem of the voltage difference between the pixels connected to the even and odd gate lines of the M r V is solved. The gate driving of the gate line is shown in the present invention. However, the present invention is not limited to the above.

Page 12 521229 V. Specific embodiments of the invention description (10). In other words, the present invention may drive the signal to fall at the same time, s: the poles of the gate line rise at any time. Use the characteristics of the LCD panel to determine when the two lines rise, when they are on different lines? To transfer the video signal to the interrogator will not reduce the resolution of the gate line, and to increase the line scan time and add the line. The method of driving the interpolar line invented by the m may increase the number of gates. Resolution, and by simultaneously driving the pixel electrode to charge the trace signal at different times, it will be enough to give even 2 gates. $ 沾: f Gate drive signals and supplies to the odd gate lines. The gate drive signals of the two have the same degradation, thus preventing the degradation of picture quality. The limit of yang: ii: Ming has been used: the preferred embodiment is disclosed as 1, but it is not used # ^ rn λ Anyone who knows this skill well, without departing from the scope of the present invention & Various changes and retouching, therefore, Bao Wei Tian of the present invention shall be determined by the scope of the appended patent application.

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Brief description of the drawings Figure 1 is a schematic diagram of an equivalent circuit of a conventional thin film transistor type LCD. Figure 2 is a schematic diagram of a conventional gate driving circuit. Figure 3 shows the waveforms of the gate drive signal generated by the conventional progressive scanning method of Figure 0. Figure 4 shows the waveforms of the signals in order to increase the line scan time. Gate drive signal of the interlaced scanning method In the drive method of the L Wuming line scan time extension, the gate drive signal waveforms of the Z gate lines are simultaneously scanned. FIG. 6 is a gate driving signal waveform diagram of three gate lines in the driving method for extending the line scan time of the present invention. Figure 7 shows the driving method for extending the line scan time of the present invention.

Draw the gate drive signal waveform of 4 gate lines. Figure 8 and Figure 8 are polar diagrams of the scanning lines of the frame and the N + 1 frame when the inversion mechanism drives the two gate lines according to the present invention. Fig. 9 is a circuit diagram of a TFT-LCD pixel according to the present invention.

Page 14 521229 Brief Description of Drawings Figure 10 is a driving method for extending the line scan time according to the present invention, and simultaneously scanning the waveforms of the gate driving signals used for the improved two gate lines. Description of drawing number 11 0 Gate driver 111 Shift register 11 2-level converter 11 3 Output buffer 1 2 0 Source driver 132 Thin film transistor 1 3 4

Page 15

Claims (1)

521229 6. Application Patent Scope 1. A method for driving the gate lines of a liquid crystal display. The method has a plurality of scanning signals which are rising at the same time to supply at least two gate lines, and simultaneously make the plurality of scanning signals in different The time decreases so that the plurality of interpolar lines are driven simultaneously, and the video signal is sampled by the pixels corresponding to the plurality of gate lines at different times. 2 The method as described in item 1 of the Shenguang patent scope, wherein when each scan afl number in the field simultaneously drives N gate lines, it rises simultaneously in N line scan times, and the Each scan signal has a different falling time. 3. The method according to item 1 or 2 of the scope of patent application, wherein the scan signal includes a first scan signal to be supplied to an even gate line, and a second scan signal to be supplied to an odd gate Line, where the first scan signal falls before the second scan signal, and when the second scan signal falls, the -scan signal rises, so that the odd states and the even gate lines fall. the same. 4. A method for driving a gate line of a liquid crystal display. The method has a plurality of scanning signals that are simultaneously decreased to supply at least two gate lines, and at the same time, the plurality of scanning signals are raised at different times, so that The multiple gate lines are driven at the same time, and the video signal is sampled by the pixels corresponding to the gate lines at the moment. 、 521229 6. Scope of patent application 5. A method for operating a pixelated liquid crystal display has multiple data lines and multiple scan lines. The method includes a device sending j = several scan signals, among which the multiple scan signals ΐίί : The stage process and the second stage that occur at different moments with each other, & the first stage process is relative to the first stage process, and the scan signal is supplied to at least two scan lines, in which the plurality of scan lines The patch cords are driven at the same time, and the data signals on the data lines are sampled by the pixels corresponding to the plurality of scan lines at different times corresponding to the second stage process.