TWI303401B - Driving method for liquid crystal display - Google Patents

Description

.1303401

Sanda number: TW2121PA, IX. Description of the invention: [Technical field of the invention] The present invention relates to a liquid crystal display and particularly relates to a voltage waveform of a scanning signal. [Prior Art] As the size of the liquid crystal display panel continues to increase, the resistance-capacitance effect of the scanning signal transmitted on the scanning line also increases. This means that the waveform that is farther away from the input of the _ signal will be more distorted by the waveform that receives the scanned signal. The distortion of the waveform of the scanning signal causes a thin film transistor to be used as a switch in the pixel, and the conduction time is shortened. In addition, as the resolution increases, the charging time on average for each pixel will also decrease. Therefore, the on-time of the thin film transistor is shortened, so that the liquid crystal capacitor CL and the storage capacitor cs in the pixel do not have sufficient charging time to store a predetermined amount of charge, so that the liquid crystal molecules cannot generate a predetermined rotation angle, thereby making The displayed side cannot achieve the desired brightness and reduces the overall image quality. SUMMARY OF THE INVENTION In view of the above, the object of the present invention is to provide a driving method for a liquid crystal display 'improving a pixel that is far away from the input of the female signal due to waveform distortion of the scanning signal, and the charging time is insufficient. Let the LCD display display the brightness of the left and right sides more evenly. According to an object of the present invention, a driving method of a liquid crystal display is proposed. The liquid sputum includes MxN elements (μ is the number of scanning lines, N is the number of data lines), scanning lines and data driving circuits. Each of the MxN pixel systems includes a thin film transistor. The closed poles of each of the thin film transistors are electrically connected to the scanning lines. The driving method is described as .1303401

Sanda number: TW2121PA '= two output scan signal to - scan line' This scan signal has a continuous first = firm level, second voltage level and third voltage level. N thin film transistors • Although they receive the money, they are turned on. During the N film transistor turn-on period, the N pixels receive the pixel voltage output by the data driving circuit. Wherein, the first voltage level is determined by the leakage current of the N thin film transistors and is used to turn off the N thin film transistors. The second voltage level is used to turn on the n thin film transistors. The voltage difference between the third voltage level and the second voltage level is greater than the voltage difference between the first voltage level and the second voltage level. The above-mentioned objects, features, and advantages of the present invention will become more apparent and obvious. The following detailed description of the preferred embodiments, together with the accompanying drawings, will be described in detail as follows: It is a schematic diagram of an example of a halogen circuit. The pixel, 包括 includes a thin film transistor (Tinger Transm Transistor) Tsw, a liquid crystal capacitor CL and a storage capacitor cs. The thin film transistor Tsw is, for example, NM〇S, the gate G is coupled to the scan line SL, the drain electrode is coupled to the resource line DL, and the source s is coupled via the liquid crystal capacitor CL and the storage capacitor cS. Connect to the common electrode power Vcom. Please refer to FIG. 2, which is a schematic diagram of an example of a liquid crystal display. The liquid crystal display display 200 includes a pixel array 202, a scan driving circuit 2〇4, and a data driving private path 206. The halogen array 202 is composed of N pieces of the above-mentioned cells, 100(1) to 100(N), and N is a positive integer. When the screen is displayed, the scan driver % channel 204 outputs the sense signal SS to the scan line SL to turn on the thin film transistors TSW in the n books 100. The waveform of the scan signal ss outputted by the scan driving circuit 2〇4 is a pulse square wave having a high voltage level Vgh and a low voltage level Vgl. The high voltage level vgh is used to turn on the thin film transistor Tsw, 6 1303401,

Sanda number: TW2121PA and the low % pressure level Vgl is determined by the leakage current of the thin film transistor Tsw, which is used to turn off the thin film transistor Tsw. The thin film transistor Tsw turn-on time can be controlled by controlling the enable time of the high voltage level Vgh. During the on-time of the thin film transistor Tsw, the data driving circuit 206 outputs a plurality of pixel voltages VP(1) to VP(N) to the corresponding data lines dl(1) to DL(N). The multi-pixel voltages VP(1) to VP(N) are input to the corresponding liquid crystal capacitors CL and storage capacitors cs through the correspondingly-transferred thin film transistors Tsw to drive the liquid crystal molecules to rotate. Therefore, the on-time of the thin film transistor Tsw affects the charging time (chargjng time) of the pixel voltage vp Lu to the liquid day and valley CL and the storage capacitor CS. The on-time of the thin film transistor Tsw is affected by the enable time of the high voltage level Vgh and the waveform of the scan signal SS. In the waveform of the scanning signal ss, the waveform is a pulse square wave. The rise and fall times of the pulsed square wave affect the conduction and cut-off time points of the thin film transistor Tsw. When different rises. Time and fall time, it will affect the length of time that the thin film transistor Tsw is turned on. The rise and fall times of the pulsed square wave are delayed by the resistance-capacitance (RC) effect on the scan line. Further, the pixel 100 has a liquid crystal cell CL and a storage capacitor CS, and the scanning line SL and each of the plates or between the wires also have various conditions for generating parasitic capacitance, such as between the scanning line SL and the common electrode plate, so scanning The line SL has an RC effect or a load effect. Because of the RC effect of the scan line SL, the pulse square wave of the scan signal SS increases as the distance transmitted to the scan line SL increases, and the waveform distortion phenomenon also increases. Eventually, the pixels on the left and right sides of the same column, such as pixels 1〇〇(1) and 1〇〇(N), are different in waveform distortion due to the received scanning signal SS, so that the corresponding thin film transistor is made. Tsw has different conduction and deadlines.凊 Refer to Figure 3, which is the waveform of the scanning signal transmitted on the scanning line. 7 1303401 麝

For the example of the architecture of the LCD display 2 (10) of the TW2121PA, the waveform of the scanning signal on the SL scan line SL is similar to the ideal square wave, but with the distance of the transmission i In the case of a pixel farther away from the input of the scanning signal, for example, the waveform of the scanned signal received by the picture =100(N) _ is severely lost. The problem of waveform distortion will cause the pixel to be 〇_〇 Thin film transistor b conduction time becomes shorter, so that its corresponding liquid crystal capacitor and storage (10)

Sufficient charging time to store a predetermined amount of charge, so that the predetermined degree of singularity ", s: 100 (1) is not obtained, because the waveform of the received scanning signal % approximates the ideal square wave, so there is enough charging time The predetermined amount of charge is stored. Therefore, the illuminance brightness of the enamel pixels 100(1) and the pixels 1〇〇(N) on the left and right sides of the same column is not uniform. Therefore, the present invention is not uniform. Providing a driving method for a liquid crystal display for solving the problem of insufficient charging time due to a large load effect, so that the screen displayed by the liquid crystal display can correctly display the required brightness. The scanning signal proposed by the present invention is borrowed. The voltage difference between the voltage level at which the thin film transistor is turned on and the voltage level at which the thin film transistor is turned off, for example, the voltage difference between the high voltage level Vgh and the low voltage level Vg| In order to make the voltage waveform of the scanning signal appear, the falling time or the rising time of the voltage (ns丨' is called faster, to increase the scanning signal to maintain the time of enabling. For the first embodiment, please refer to FIG. 4, which is a waveform diagram of the scanning signal according to the first embodiment of the present invention. The scanning signal SS' is applied to, for example, the liquid crystal display 2 and output by the scanning driving circuit 204 described above. The signal ss has a continuous first voltage level VgM, a second voltage level Vgh and a third voltage level. 2: The first power 8 1303401

Sanda number · TW2121PA, quasi-Vgl1 is determined by the leakage current of the thin film transistor Tsw in the pixel 100, such as 6 volts. The second voltage level Vgh is used to make the thin film transistor 'on', for example, +23 volts. The voltage difference between the third voltage level Vg|2 and the second voltage level Vgh is greater than the voltage difference between the first voltage level Vg|1 and the second voltage level (10), for example, the third voltage level Vg 丨 2 It is lower than the first voltage level '-1 to 17 volts. The first voltage level Vgl1 is determined by lowering the amount of leakage current defined by the third voltage level Vgl2, so that the scanning signal ss is switched from the high voltage level Vgh to the low voltage level Vgl2, and the voltage falling time is A faster, ie faster, voltage drop slope, which represents the point in time at which the threshold voltage of the thin film transistor Tsw is reached, can be advanced. Please refer to FIG. 5A, which is a waveform diagram of a scan signal and a conventional scan signal according to a comparative embodiment of the present invention. Compare the waveform of the conventional scanning signal ss with the scanning signal ss. When the control signal 〇E is enabled (time TS1), it means that the scan signal SS and the known signal SS' are turned into non-enabling. As shown in FIG. 5A, when the waveform signal SS and the scanning signal ss are distorted, since the scanning signal ss, the low voltage level Vgl2 is lower than the low voltage level VgM of the scanning signal SS, the scanning signal ss The falling reaches a certain voltage level, for example, the threshold voltage Vt, • the time point T1 is earlier than the time point T2 at which the scanning signal ss reaches the threshold voltage ντ. This means that the cut-off time point of the scan signal SS can be postponed, that is, the control signal is delayed by the time point to increase the charging time of the above-mentioned pixel 1 〇, please refer to FIG. 5 A waveform diagram of a scan signal and a conventional scan signal of the embodiment. Since the scanning signal SS' has a relatively fast voltage drop slope, the new control signal 〇Ε' can be later than the above-mentioned control signal 〇Ε enabling time point, that is, the time point TS2, so that the scanning signal SS is maintained at the second voltage. The time of Vgh is longer, that is, the time for turning on the thin film transistor Tsw is more 9 1303401

Sanda number: TW2121PA long. Thus, when the scanning signal SS is generated as the % effect on the scanning line SL increases, and the wave distortion occurs, 'by increasing the second voltage (4) (4): so that the scanning signal SS is farther away from the input. A pixel, such as a stencil, will take longer to charge than the traditional scan signal ss. - This will greatly improve the charging time caused by the load effect being too large. SECOND EMBODIMENT B. FIG. 6A is a waveform inconsistency of a scanning signal according to a second embodiment of the present invention. Similarly, the scanning signal ss is applied to the liquid crystal display 2 and outputted by the above-described scanning drive circuit 2G4. The scanning signal ss has a continuous first-voltage level Vg 丨1, a second voltage level (four) and a third voltage level vgh2. As described above, the first voltage level Vgl1 is determined by the leakage current of the thin germanium transistor Tsw in the halogen (10), for example, _6 volts, and the second voltage level is used to turn on the thin film transistor Tsw. It is +23 volts. The present embodiment differs from the first embodiment in that the third voltage level Vgh2 is higher than the second voltage level Vgh1, for example, +4 volts. Further, during the turn-on of the thin film transistor Tsw, the scan signal is increased by increasing the second voltage level Vgh1 to the third voltage level Vgh2: s"- varies between the high voltage level and the low voltage level Voltage difference, that is, the third voltage level

The voltage difference between Vgh2 and the first voltage level VgM makes the voltage drop faster. Similarly, the voltage drop time is faster, in addition to increasing the charging time ^, so that the thin film transistor Tsw cuts off faster and avoids receiving the next check, .... In addition, in this embodiment, it is not limited to reducing the time for voltage drop, and the time during which the voltage rises is less, so as to increase the charging time of the pixels. Please refer to the waveform diagram of another scanning signal according to the second embodiment of the present invention. Scanning 1.303401

Erda number: TW2121PA ** - 唬SS change has a continuous _voltage level VgM, a third voltage level Vgh2 and a second voltage level Vgh1. The third voltage level vgh2 is advanced in advance of the second voltage level Vgh1 to increase the voltage difference between the low voltage level and the return voltage level. In this way, the film transistor Tsw can be turned on at a later time to improve the problem of insufficient charging time due to a large load effect. In the scanning signal of the third embodiment, the voltage difference between the on and off of the thin film transistor is increased, and the voltage difference between the on-voltage level and the low-voltage level is changed to the high-f voltage level. At the same time, increase the voltage difference between voltage rise and fall. Please refer to FIG. 7, which is a waveform diagram of a scan signal according to a third embodiment of the present invention. Similarly, the scanning signal SS, is also applied to the liquid crystal display 2 and output by the above-described scanning driving circuit 204. The scan signal ss,, includes a continuous first-voltage level Vgii, a fourth voltage level Vgh2, a second voltage level ν_, and a third voltage level 刈丨2. Similarly, in the same manner as in the first and second embodiments, the first voltage level Vgl1 is used to turn off the thin film transistor, for example, _6 volts, and the second voltage level is used to turn on the thin film transistor, for example, +23 volts. The third voltage level is the second voltage level, which is lower than the first voltage level _, for example, the voltage difference between the low voltage level and the second voltage level is increased by the low voltage level. The voltage difference between the quasi-conversion and voltage levels. As with the principle described above, the third embodiment makes the scan simple s = faster than the fall time, so that the charging time of the pixels can be increased. Therefore, the scanning signal proposed by Sheng 1 is not limited to the conversion of low power by high-voltage leveling. 1303401

达达号·· TW2121PA The voltage difference between the voltage level and the low level of the electric level can be changed as long as the rising time and the falling time of the scanning signal can be changed. Check the charging time. D. In addition to this one, the scanning signal shown in Fig. 4, 6 or 7 does not limit the pixel structure shown in Fig. 1, and can also be used in other paintings having a binding transistor as a switch. Prime structure. The driving method of the liquid crystal display disclosed in the above embodiments of the present invention is as follows: increasing the high voltage level and the low voltage level of the scanning signal

The power difference is 'so that the rise and fall times of the scan signal are faster than the conventional scan signal'. After the waveform of the scan signal is distorted, it still has more charging time than the conventional method. In the above, although the present invention has been disclosed in a preferred embodiment as above, it is not intended to limit the present invention, and anyone skilled in the art can make various kinds without departing from the scope of the invention: The scope of the reading of the present invention is determined by the scope of the patent application.

12 1303401

Sanda number: TW2〗 21PA, [Simple description of the diagram] Figure 1 is a schematic diagram of an example of a pixel circuit. Figure 2 is a schematic diagram showing the structure of an example of a liquid crystal display. Figure 3 is a waveform diagram of the scanning signal transmitted on the scanning line. Fig. 4 is a waveform diagram showing the scanning signal of the first embodiment of the present invention. Fig. 5A is a waveform diagram showing the scanning signal and the conventional scanning signal of the embodiment of the present invention. FIG. 5B is a schematic diagram showing the waveforms of the scan signal and the conventional scan signal according to the embodiment of the present invention. FIG. 6A is a schematic diagram showing the waveform of the scanning signal according to the second embodiment of the present invention. FIG. 6B is a schematic diagram showing the waveform of the scanning signal according to the second embodiment of the present invention. Figure 7 is a waveform diagram of a scanning signal according to a third embodiment of the present invention. [Main component symbol description] 1〇〇: Alizarin 200: Liquid crystal display> 2〇2: pixel array 204: scan drive circuit 2〇6: data drive circuit SL: scan line DL: data line Tsw: thin film transistor Cs : liquid crystal capacitor CL : storage capacitor 13

Claims (1)

Ϊ303401 三达号: TW2121PA X. Patent application scope 1. A driving method of a liquid crystal display TF device, the liquid crystal display includes at least N halogen elements, a scan line and a data driving circuit, and the N system is a positive integer, the ~ Each of the pixel systems includes a thin film transistor, and the gates of the N thin film transistors are electrically connected to the scan line. The driving method includes: outputting a scan signal to the scan line, the scan signal has continuous— a first voltage level, a second voltage level, and a third voltage level; and a gate of 4 N thin film transistors receives the scan signal, and then turns on 'near 4 N thin film days During the conduction of the body, the N pixels receive the pixel voltage rotated by the data driving circuit; " wherein the first voltage level is used to turn off the N thin film transistors, the second voltage bit a quasi-system for turning on the N thin film transistors; wherein, when the third voltage level is greater than the second voltage level, the voltage difference between the third voltage level and the first voltage level is greater than the third f-pressure level a voltage difference from the third voltage level; , The third voltage level when the voltage level less than the second time, the third voltage level and the second - the voltage level is less than the voltage difference between the voltage difference between the third voltage level and second voltage level of φ. The driving method of the liquid crystal display according to claim 1, wherein the scanning signal further has a fourth voltage level, the first voltage level is green, the fourth voltage level, the second The voltage level and the third voltage level are continuous, and the voltage difference between the fourth voltage level and the first voltage level is greater than a voltage difference between the first electric j level and the first voltage level And a voltage difference between the third voltage level and the second voltage level is greater than a voltage difference between the second voltage level and the first voltage level. 3. A scanning method for a display, the display having a plurality of ^03401, ___ = number: fan dans, each of the elements has a transistor, the electric day and day control θ its conduction 舆By the end, the scanning method comprises: the book calendar system provides a scanning signal with continuous n voltage (four) and n two voltage levels by a known scan; wherein the first level is used to make the electricity=standard The transistors are turned on, and the third voltage level is so large: the electric level is lower or lower than the first voltage level. 4. In the scanning method described in claim 3, in i, the voltage difference between the second voltage and the second voltage level is greater than the second voltage level and the first voltage level Voltage difference. 5. The scanning method according to claim 3, wherein the voltage difference between the % three voltage level and the first voltage level is greater than the second voltage level and the first voltage level. The voltage difference. The scanning method of claim 3, wherein the scanning signal further comprises: a fourth voltage level, the first voltage level, the fourth voltage level, and the second voltage level And the third voltage level is continuous, the voltage difference between the fourth voltage level and the first voltage level is greater than a voltage difference between the second voltage level and the first voltage level, and the The voltage difference between the third voltage level and the third voltage level is greater than the voltage difference between the second voltage level and the first voltage level. 15