TW563079B - Driving method and driving circuit of liquid crystal display panel - Google Patents

Abstract

A kind of liquid crystal display (LCD) panel driving method suitable for use in an LCD panel is disclosed in the present invention. The LCD panel contains plural display units and the corresponding N-type or P-type thin film transistors, which are individually coupled to a common electrode and the corresponding data electrode and the gate electrode. At first, the pre-charging pulse and the image signal are provided to the data electrode, in which the level of the pre-charging pulse is higher than the common level to vary the gray tone of display unit to the maximum voltage value when the display unit is in the positive polarity; while the level of the pre-charging pulse is lower than the common level and higher than the maximum voltage value of gray tone variation of the display unit when the display unit is in the negative polarity. Finally, the scan signal is provided to the gate electrode.

Description

563079 Description of the invention (1) The present invention relates to a driving circuit and a driving method for a liquid crystal display panel, and more particularly to a liquid crystal display panel driving using a pre-charging method to drive a liquid crystal display (LCD). Circuit and driving method. The currently known liquid crystal displays include a plurality of pixels arranged in an array. The liquid crystal in each day element is controlled by the cross-voltage on it, and the transmittance of the liquid crystal can be changed to show The desired gray level on the screen. FIG. 1 is a schematic diagram showing an equivalent circuit of a conventional liquid crystal display panel (hereinafter referred to as an LCD panel) and a peripheral driving circuit thereof. As shown in the figure, the LCD panel 1 is composed of interlaced data electrodes (represented by Dl, D2,. &Quot; Dm) and gate electrodes (represented by G1, G2, ..., Gn). Each group is interlaced. The data electrode and the gate electrode can be used to control a display unit. For example, the data electrode D1 and the gate electrode G1 can be used to control the display unit 2000. As shown in the figure, the equivalent circuit of each display unit mainly includes a thin-film transistor (QU ~ Qlm, Q2, Q2m, ..., Qn, Qnm) for controlling data entry, and a storage capacitor (C11 ~ Chem, C2, C2m, ..., Cnl ~ Cnm). The gate and drain of the thin film transistor are respectively connected to the gate electrode (G1 ~ Gn) and the data electrode (IH ~ Dm). The scanning signal on the gate electrode (Gb and Gn) can turn on or off the same column (also That is, all the thin film transistors on the same scanning line) are used to control whether the video signal on the data electrodes (D and Dm) can be written into the corresponding display unit. It must be noted that each display

563079 5. Description of the invention (2) In terms of 'each display unit corresponds to a single pixel (pixel); for a color LCD', 'each display unit corresponds to a single pixel (subpixel)

Do n’t use red (represented by R), blue (represented by B), or green (represented by G). In other words, a set of rGB sub-pixels (three display units) can form a single pixel. In addition, the driving circuit portion of the LCI panel 1 is also shown in the first figure. The gate driver i0 sends the scanning signals on each of the gate electrodes G1, G2, ..., Gn according to a predetermined scanning sequence '. When the scan signal is loaded on the =: interrogation electrode, the thin film transistors in all display units on the same line or in the same scan will be turned on. When a certain scanning line is selected, the data driver 20 sends corresponding video signals to the m display units in the column through the data electrodes D1, D2,. &Quot; Dm according to the image data to be displayed. When the gate driver completes the scanning operation on all ^ columns of scanning lines at a time, it means that the display operation of a single frame is completed. Therefore, by repeatedly scanning each scanning line and sending out video signals, the purpose of continuously displaying images can be achieved. Among them, the signal CTR represents the scanning control message received by the gate driver 10; the signal LD represents the data latch signal of the data driver 20, and the signal DATA represents the input image message. Generally, the video signal transmitted on the data electrodes D1, D2, ..., Dm can be divided into a positive polarity video signal (p 〇sitivevide 〇signa 1) and a negative electrode according to the relationship between the video signal and the common electrode voltage vc0M. Two kinds of sex video signal (negative video signal). A positive video signal means that its potential is higher than the common electrode voltage VCOM, and according to the gray level value it represents

0773-8585OVf (N); P91025; robert.ptd page 5 563079 V. Description of the invention (3) Different, the actual potential is between the voltage Vpl and the voltage Vp2 (generally closer to the common electrode voltage VCOM corresponds to the lower Grayscale value). In contrast, the negative roar signal is that its potential is lower than the common electrode voltage Μ⑽, and according to the grayscale value it represents, the actual potential is between the voltage Vnl and the voltage Vn2 (again, the closer it is to the common electrode voltage) MVCOM corresponds to lower grayscale values). When the same grayscale value is respectively expressed by a positive polarity video signal and a negative polarity video signal, the display effect is the same in principle, but in reality there are still some differences. In addition, in order to prevent the liquid crystal molecules from being continuously biased by a single-polar electric field, which shortens the life of the liquid crystal molecules, a single display unit will receive video signals with opposite polarities when it is in an odd frame and an even frame. Next, please refer to Fig. 2. Fig. 2 is a timing relationship diagram of the LCD cross-voltage corresponding to each screen. Figure 2 shows the timing of the original video signal. Here, the frame rate is 60Hz as an example, so the time on each side is 16.6ms. At this time, the voltage (pixel voltage) stored by the storage capacitor (liquid crystal) will slowly reach its applied cross voltage, as shown by the dashed line. As shown in the figure, in order to accelerate the speed of the pixel voltage to reach the video level, the level on the material line can be raised. The method is to set the voltage level of the data electrode = positive / negative polarity to maximize the grayscale change of the liquid crystal molecules. . With the above pre-charging technology, the voltage can be paraphrased in advance, and the target pixel voltage can be reached earlier, so that the LCD can be more realistic with the proper gray scale. Clothing appears, however, the traditional pre-charge technology is pre-charged / discharged in both positive and negative polarity.

111 II Page 6 0773-8585TWf (N); P91〇25; robert.ptd 563079

V. Explanation of the invention (4) The method of the electric data electrode has its disadvantages, because the result of pre-charging / discharging may cause over-charging / discharging and the final pixel voltage must be corrected to the target voltage, but the time to reach the target voltage is prolonged. Therefore, the timing of pre-charging must be carefully considered. The timing of pre-charging can be determined based on the amount of drain current I d flowing through the source / inverter of the thin-film transistor. The reason is the drain current! The amount of d directly affects the speed of charging and discharging liquid crystal molecules. Drain current is very large, which is affected by the voltage of the thin-film transistor gate, non-pole, and source. The formula is as follows: "

Id = // (W / L) Cins (Vgs-Vth) Vds (1) where 'is the mobility of the electrons, W and L are the width and length of the thin-film transistor, and Cins is the capacitance of the thin-film transistor gate , Vgs is the voltage difference between the thin film, the crystal gate and the source, vth is the ° boundary voltage of the thin film transistor on, and V ds is the voltage difference between the thin film transistor source and the source. It can be known from the formula (1) that when the source voltage is closer to the gate voltage, Vgs is smaller, and thus d is smaller. Taking an N-type thin film transistor as an example, when the level of the image signal provided by the data driver 20 is higher than the voltage of the liquid crystal pixel, these 3 perform a charging operation on the liquid crystal pixel, so the source voltage of the thin film transistor is the pixel Voltage. When the level of the image signal provided by the data driver 20 is lower than the voltage of the liquid crystal pixel, the discharge operation is performed on the liquid crystal pixel at this time, so the source voltage of the thin film transistor is the level of the image signal. Therefore, the voltage difference between the gate voltage and the image level #V i d e 〇 and the pixel voltage v p χ χ e 1 is smaller. Division

Vgs = vg (〇n)-(Min [Vvideo, Vpixel])

563079 V. Description of the invention (5) Here, it is assumed that Vg (on) is 12 and the range of Vvideo and Vpixei is 1.5V ~ 8.9V. 5V。 When the negative polarity, Vvideo is 1.5V, at this time Vpixei is greater than Vvideo, so Vgs is 10. 5V. This voltage gap enables the thin film transistor to provide sufficient current I d. When it is positive, Vgs will decrease as the gate voltage approaches Vvideo or Vpixel at this time. At this time, the pixel voltage changes in the following situations ... 1 · When charging the liquid crystal pixel, yvide0 is 8 at this time. Vpixel is 7.4V ', then Vgs is 4.6V (Vgs = Vg (〇n)-Vpixei = 4.6V). And because the pixel voltage Vpixel will gradually increase due to charging, Vgs will gradually decrease, which will make the id smaller, which will cause the time to charge the pixel voltage Vpixel to the target level increase. 2. When the liquid crystal pixel is discharged, at this time, Vvide is 7.4V, Vpixei is 8.9V, and then Vgs is 4.6ν (VgS = Vg (〇n "Vvide0 = 46V). And

Vgs will gradually increase as the pixel voltage Vpixel is discharged to Vvide0, so 1 d $ gradually increases, so when the pixel voltage vp 丨 X㊀1 is discharged to the target level 2 t ί * Because 2 has a positive polarity on the liquid crystal Only when the pixel is charged, # 之 # 作 is required. In addition, the situation discussed above is a thin-film transistor. When the main B / right-type transistor is a P-type, only when the negative polarity discharges the liquid crystal pixel, the pre-charge action needs to be performed. In order to solve the above-mentioned problem, the main purpose of the present invention is to display the panel driving circuit and driving method. • The timing of A f should be selected properly to accelerate the speed of the pixels to reach the positioning accuracy. Motion # i == For the purpose described, the present invention provides a method for driving a liquid crystal display panel, which is used for a liquid crystal display panel. LCD panel contains plural

563079 V. Description of the invention (6) — One display unit and corresponding or p-type common level and corresponding data electrode and gate = "Coupling a charge pulse and image signal to the data electrode First, a pre-display unit is provided in For positive polarity, it is higher than :: bit; and the median level: the voltage value with the largest change, and the display unit is at the white level of I5, and higher than the gray level of the display unit. Signal to the above gate electrode. Unjust value. Finally 'In addition, the present invention proposes a liquid crystal display panel driven on the liquid crystal display panel. The liquid crystal display panel includes complex power ^ applicable corresponding thin film transistors (can be N-type or p-type) ^ not ^ and the corresponding data electrode and closed electrode. A common level includes a closed-pole driver. The gate driver in the pre-charge pulse generator is used to send a scanning signal to Beco Drive. The generator is used to provide the pre-charge pulse to the capital. The display unit is higher than the common level when the polarity is positive; when the gray level of the display unit is lower than the common level, the material driver is used to provide an image signal to the data electrode. M value. Example: The figure shows a liquid crystal according to an embodiment of the present invention. Not early: and its driving circuit. Here only a single-displayed early circuit structure is shown. No. I will not repeat them here. The data electrode Dm and the gate electrode G are a display unit (dlspiay unit). As shown in the figure, each display ^ page 9 〇773-8585m (N); P91025; robert.ptd 563079 5. The equivalent circuit of the invention description (7) mainly includes controlling the display capacitance ". The gate of the thin film transistor And: The pole is connected: The electricity: The two conductors close off the "membrane electricity" on the same column (that is, the same-scan line): the body, precisely to control the video on the data electrode Dm "

Slgnal) can be written into the corresponding display unit. In addition, 偻 ,,, and gates 61 and 62 are used to control the LCD panel panel to communicate to the switching signals HSW and PSW. It must be said that "a single bright spot on the 2 panel. That is, for = two one mother = 显 不 単 疋 corresponds to a single pixel (pixei); for = ', each display unit corresponds to a single pixel — ί) Changing the 疋 Λ color (represented by R), blue (represented by 6), or green (corrected two pixels of the table, a set of RGB sub-pixels (three display units) can be formed. In addition, in Figure 3 At the same time, it shows the driving circuit part. The gate driver 30 sends the scanning signal (or scanning pulse wave) on each gate electrode according to the predetermined scanning sequence. ^ When a gate voltage = f scanning signal Will make the thin-film transistor on the same row or on the same scan line earlier in the on state. When a certain scan line is selected, the data driver 40 sends the corresponding data via the data electrode Dm according to the image data to be displayed. The video signal (gray level value) is (11 elements) in the column. ^ In addition, according to the embodiment of the present invention, the precharge pulse generator 50 provides a precharge pulse to the data electrode Dm. According to the previous description, the precharge Pulse bit

563079

ί = ϊ When the unit is positive, the voltage is higher than the common position ㈣⑽ and the voltage value (extremely positive value) that makes the display strict polarity, and the display unit is the voltage value that has the largest change in the negative: ... step, that is, it is not the display; = The voltage value with the greatest change (extremely negative value), & the pre-charge pulse in the negative polarity can be the middle gray scale value of the negative polarity or the common level vcom, not provided. In the case of Wang Shi +, in this embodiment, the thin-film transistor is an N-type as an example. When the crystal is P-type, the level of the precharge pulse is lower than the common value of the display unit when the polarity is $. When the voltage level (maximum negative value) of X, gs-s--X-^ ^ is doubled to be flushed # Mi on the level of the display unit, and the display is not positive, The pre-charge pulse f bit rate is south of the common level vc0M and lower than the voltage value that makes the gray scale of the display unit become lightning-noisy, that is, it is not an extremely positive value that maximizes the gray scale change of the display unit. The level of the charging pulse at the positive polarity may be the middle gray scale value of the positive polarity or the common level VCOM, or it may not even be provided. > Fig. 4 is a timing chart of No. L of the liquid crystal display according to the embodiment of the present invention. Here, a precharge pulse of 8 · 9 V is applied as an example when the target pixel voltage is 8 · 9 v and the polarity is positive. First, the pre-charge pulse generator 50 provides a pre-charge pulse to the transmission gate 62. When the switching signal PSW turns on the transmission gate 62, the level of the data electrode Dm is thereby increased to reach the same level as the pre-charge pulse of 8 · 9V ° Next 'when the gate electrode Gn receives a high-level gate scan signal', due to the cooperation of the capacitor, the level of the data electrode drops slightly, and the pixel voltage rises', and the transmission signal HSW is turned on to transmit the gate 6 1 After that, the signal (8.9V) provided by the data driver 40 makes the data electrodes and pixels electrically

0773-8585TWf (N); P9l025; robert.ptd page 11 ^ 03079, invention description (9) = continue to rise until the target level uv is reached. Here, because the-level is the same as the video signal, only the video signal is displayed. First, the Γ action can make the level of the data electrode and the pixel in advance. In addition, the pixel voltage Vpixel can reach the target level earlier. In the case of performing the pre-charged film transistor, the negative value of the VC0M is not required when the polarity is negative: if it is to be performed, it is also necessary to avoid the pre-charge to a rapid production below the common level. In order to avoid over-precharging and affecting the pixel voltage to reach the target, the embodiment is disclosed as above, but it is not intended to limit the spirit and scope. Those skilled in the art will not depart from the guarantee of the present invention. There are a few changes and retouches, so the scope of this invention ... as defined by the scope of the patent application attached hereafter shall prevail. Of

The drawings are briefly explained in order to make the present invention μ μ the following special-preferred objectives, features and advantages can be more clearly understood, the following examples are also given in conjunction with the accompanying explanations for detailed explanations as shown in Figure 1. Xi. The equivalent electric circuit of the moving circuit. The liquid crystal display panel of the transistor and its peripheral driver f 2 is a diagram showing the liquid crystal cross-voltage corresponding to each written timing diagram. The display-ϊ Λ display according to the present invention; the embodiment; the schematic diagram of the "moving circuit" of the liquid crystal display described. The signal timing diagram of the liquid crystal display of the production girl B # is not based on the embodiment of the present invention. Explanation of symbols: 1 ~ LCD panel 1 0, 3 0 ~ gate driver 20, 40 ~ data driver 2 0 0 ~ display unit 50 0 ~ precharge pulse generator 61, 6 2 ~ transmission gate ..., Cnl ~ Cnm ~ Storage capacitor data electrodes C11 ~ Chem, C21 ~ C2m D1, D2, D3, "· Ι) ι G1, G2, ... Gn ~ Gate electrode HSW, PSW ~ Switching signals Q1, Qlm, Q2, Q2m ... .QrU ~ Qnm ~ Thin Film Transistor

0773-8585TWf (N); P91025; robert.ptd Page 13

Claims (1)

Steps for applying patents to the board and the upper film material step: The above mentioned common value is mentioned, and the Nan Yushi 2. method, which is about the big electricity 3. The method, which is the above 4. The board, the upper film material Electrode steps: Note: J ί crystal display panel driving method, applicable to-LCD display panel, the daily display panel contains a plurality of display units and corresponding N body, respectively coupled to a common level and a corresponding plurality of resources For the f electrode, the method for driving the liquid crystal display panel includes the following steps and an image signal to the data electrode: the pulse charge level is at the above display level and the upper position + the remaining position-the position C is generated. Yin Ma is the same as in the above mentioned Gu Qian, "The voltage with the largest gray scale change. The above-mentioned dry-single order is as early as ^^. When negative, it is lower than the loading parity level and the above-mentioned insignificant gray-scale change is the largest for the scanning signal to the above. Gate electrode. The value of 阶 and the gray level change of the above-mentioned precharge pulse level in i. The level of the above-mentioned precharge pulse in the item 丨 is at the common level of the above-mentioned display panel driver. A driving method of a liquid crystal display panel when the unit is not in the negative polarity. The liquid crystal display panel includes a plurality of members: a crystal display surface transistor, which is respectively coupled to a common electrode and corresponding P and gate electrodes. The above-mentioned liquid a level and a plurality of corresponding materials are described below. The driving method of the panel includes the following and ~ image signals to the above-mentioned data electrodes, which Provide a pre-charge pulse and once you're out, patent application range ___ The above display unit is higher than the voltage value when the polarity is positive, and the maximum display power and the above display are left in the display-: a few In the past, a voltage value with the largest gray scale change below the above common level is provided; and & a scanning signal is provided to the above gate electrode. law,? The driver of the liquid crystal display panel described in item 4 in the middle range is approximately at a level higher than the voltage value of the display unit when it is in positive polarity and the above common level ... The driver of the display panel is the same as described above. The above display unit is on the positive time plate. On 7: == display panel drive circuit is applicable to- LCD display film. The panel contains a plurality of display units and corresponding ones. Thin electrode and gate electrode, the number of the above liquid crystal data is two: = device? The scanning signal is sent to the above-mentioned gate electrode; the electrode, 1 in the second device, is used to provide a pre-charge pulse to the above-mentioned data, the level of the ancient II Ι ί strikes the above-mentioned display unit at a positive polarity: a large voltage value, And the electric value at the gate level of the display unit and the maximum gray scale change of the display unit; a -data driver for providing an image signal to the above-mentioned data unit; page 150773-8585TWf (N); P91025; robe r tp td 563079 VI. Patent application scope pole 0 8. The liquid crystal display panel drive circuit according to item 7 of the patent application scope, wherein the thin film transistor is an N-type thin film transistor. 0773-8585TWf (N); P91025; robert.ptd Page 16