TWI275065B - Method for resolving feed through effect - Google Patents

Abstract

A method for resolving feed through effect is disclosed, including the steps of obtaining a sampled Gamma voltage value from a corresponding relationship of effective voltage versus permeability of a display and a Gamma curve of the display; using the sampled voltage value and transistor parameters to obtain feedback values of positive and negative frames; and obtaining new Gamma curve values of the positive and negative frames using the feedback values, where the new Gamma curve will fall back to the ideal Gamma curve after feed through effect so as to prevent the display screen from flickering without the need to adjust the Vcom DC bias of common electrodes.

Description

1275065 IX. Description of the Invention: [Technical Field] The present invention relates to a method for solving the feedthrough effect, in particular to input a display driving 1C with a feedback value of a positive and negative frame (frame) to solve the feed through effect. The method. [Prior Art] The ked through effect of a typical TFT (Thin Film Transistor) liquid crystal display is mainly caused by the parasitic capacitance on the panel, and the feed through effect indirectly affects the correctness of the gray scale display, and causes 昼The surface flashing 'takes the Cs on c(10)mon type tft subpixel element shown in Figure 6, where the gate of the transistor q is connected to the scanning signal line G (G ate 1 ine ), and the drain is connected to the data signal. The data line D (Data 1 ine), and the parasitic capacitance Cgd are respectively connected to the source of the scanning signal line G and the transistor Q, and connected to the liquid crystal capacitor Clc and the storage capacitor Cs, and the liquid crystal capacitor Clc and the storage capacitor Cs are connected to vcom ( Common electrode). For example, the VG signal shown in Figures 7A and 7B is the scanning signal of the TFT. When the VG signal is from Vgh (scanning signal high level) to Vgl (scanning signal low level), the voltage will pass through the capacitance of the parasitic capacitance Cgd. The coupling 9 affects the voltage of the video signal Vs, and generates a feed through effect (such as AVp and AVn shown in FIG. 7B), which causes a phenomenon such as flickering of the display screen, which is viewed from the perspective of the gamma curve. 3 and 4, the ideal gamma value is input, and after the feed through effect, 5 is obtained - the gamma value with the feed through effect, which will cause the phenomenon of the flickering 1275065 flickering 'because of positive and negative gamma Ma is worth the feed through voltage is not the same. In order to improve the feed through effect, there are many ways and circuits to reduce the AVp and Δνη to solve the feed through effect, such as US Patent No. 6256010B1 and Taiwan Patent Publication No. 564645, 573284, 527497, etc., but none of them are considered by the Gamma curve. Adjustments can address the effects of the feed through effect. The following are the existing methods to solve the feed through effect; First, by the drive method to solve: (1) Adjust the Vcom DC bias (that is, adjust the bias voltage of the common electrode): only compensate for the positive and negative frame feed through voltage divided by the value of 2 Can't really compensate for the feed through effect. (2) 3 Level drive mode: The feed through effect and drive complexity caused by the liquid crystal capacitor Clc cannot be compensated. (3) 4 level drive mode: the drive is complicated. Second, by the process method: Only reduce the value of the parasitic capacitance Cgd or increase the value of Cst to achieve a reduction in the feed through effect. Such as the US patent 610764, 6019796, 60202232 and so on. Third, by the layout (1 ayout) solution: Reduce the parasitic capacitance Cgd value through the layout method to reduce the pressure drop caused by the feed through effect, such as US patent 6028650. 1275065 4. Add circuit solution on Pane 1: No sampling circuit is fed back; the pressure drop caused by feed through, such as Taiwan patent 591594. In addition, there is a design compensation capacitor in each pixel to compensate for the feed through effect, such as Taiwan Patent 594347, but this method will increase the complexity of the device. Accordingly, the aforementioned techniques are necessary to be improved. SUMMARY OF THE INVENTION The main object of the present invention is to solve the above problems and provide a method for solving the feed through effect. By taking the corresponding relationship between the effective voltage and the transmittance, the gamma voltage value is obtained and the feedback value is calculated, and the gamma curve is adjusted. (Gamma curve), by the way, the feedthrough effect (feedthrough effect) of the parasitic capacitance of the display is compensated, and there is no need to increase the trouble of the device or the process, and the adjustment mode is simple, so that the display surface does not have a feedthrough effect. Flashing situation. For the purpose of the present invention, the 'method of solving the feed thr〇Ugh effect of the present invention' includes the following steps: (1) sampling is performed by the correspondence between the effective voltage and the transmittance of the display and the gamma curve of the display. Gamma voltage value; (2) Use the sampled gamma voltage value and the transistor parameter to obtain the feedback value of the positive and negative frame (frame); (3) Add the feedback value of the positive and negative frame (frame) to get a The gamma curve value of the new positive and negative frame (frame); (4) Enter the new gamma curve value into the driving ic inside of the display; (5) This new gamma curve passes the feed through effect 1275065 ( After the feedthrough effect, it will fall back to the ideal gamma curve, without adjusting the bias voltage of the common electrode (Vc(10)DC bias) 5 to make the surface of the display not flicker. The above and other objects and advantages of the present invention will be readily understood from Of course, the invention may be varied on certain components, or in the arrangement of the components, but the selected embodiments are described in detail in the specification and their construction is shown in the drawings. [Embodiment] Please refer to Fig. 1, which shows the method flow of the embodiment selected for the present invention, which is for illustrative purposes only and is not limited by such a process in patent application. The method 5 for solving the feed through effect of the embodiment includes the following steps: (1) a VT curve (corresponding relationship between effective voltage and transmittance) of a known display, and setting a desired gamma curve (Gamma curve, Gray scale-transmission rate graph), obtain the desired sampled gamma (Ga leg a) voltage value; (2) Use sampled gamma (Gamma) voltage value and transistor parameter: Clc (liquid crystal capacitance value), Cgdon (capacitance value when parasitic capacitance is turned on), Cgdof f (capacitance value when parasitic capacitance is off), and input video signal Vs (Video signal), VGH (scanning signal high level), VGL (scanning signal low level) VcomH (common electrode signal high level) and VcomL (common electrode signal low level) calculate the feedback value of positive and negative 1275065 frame (frame) by means of feed-through voltage drop formula; (3) add feedback value to get a new positive and negative The gamma curve value of the frame; (4) input the new gamma curve value into the drive IC (integrated circuit) of the display; (5) The new gamma curve is fed through After the (Beltong effect), it will return to the ideal gamma curve (as shown in Figures 3 and 4) without adjusting the bias voltage of the common electrode (Vcoin DC bias). The face of the display can be made not to flicker. The example of the present invention is exemplified by the Cs on ccDmmon type TFT subpixel (sub-cell) element applied to the prior art 2A, and the structure thereof is not described. The feed through effect of the technology, the present invention is based on the steps of the foregoing method, and uses the feedthrough pressure drop formula derived from the feedthr〇ugh effect to obtain parameters for subsequent application, and the feedthrough pressure drop formula is as follows: (Where the VC0in signal is AC, 0 volts to 5 volts)

Positive frame pressure drop: two '--(L-VA +G +G/C ’

Negative f mme pressure drop: = H

Cgdoff Seven Cst + Clc

Cgdon represents the capacitance value when the parasitic capacitance Cgd capacitor is turned on;

Cgdoff represents the capacitance value of the parasitic capacitance Cgd capacitor when it is closed; V gh represents the high voltage level value of the clock signal Vg1 represents the low voltage level value of the clock signal 1275065 V sp represents the video signal of the positive frame input Vs value Vsn represents negative The VSD value of the video signal input by the frame, and the VT curve of the known liquid crystal display (corresponding curve of effective voltage to transmittance, as shown in FIG. 2A) and Gamma=2· 2 curve (gray scale) A penetration curve, as shown in Figure 2B. Assuming that you want to find Vp32 on page 2B (representing the input voltage of grayscale 32), you must first select the pre-designed gamma curve value to select Garnma1^ 2, for example, as shown in Fig. 2A, the G32 point is known by the gray level 32, and then used as a map to the right to the VT curve of the 2A picture to obtain Vp32, which is Ga匪a=2, The voltage of the gray level 32 of 2, the same can correspond to the gray level voltage of the eight points of the positive frame is as follows:

VpO 2·78 Vpl=4·76 Vp8=3·7 Vp20=2.65 Vp43=L 98 Vp55 2 L 69 Vp62-le 28 Vp63=0.86 Then use the eight positive frames to calculate eight negative frame points as follows : Since the Vcom signal is AC type, the negative frame point is the difference from the positive frame point of 5 volts; νηΟ = (5-4·78) = 〇β22 Vnl = (5-4.76) 〇β24 1275065

Vn8 two (5-3·7) two 1. 3 Vn20-(5-2. 65)=2. 35 Vn43=(5-1. 98)=3. 02 Vn55=(5-1·69) two 3 ·31 Vn62=(5-1·28) two 3.72 Vn63=(5-〇.86)=4.14

Calculate the feed through voltage for these points for the positive and negative frames, and get back to the Gamma curve to get a new gamma curve value.

Cgdon is not equal to Cgdoff, Clc is not a fixed value (constant) Α-=〇·〇1 corpse, ‘=0.005/7

If (four) me 丄=0·07Ρ

If 1< |AV/C| < 2,Clc2 = Clcl^- = 0AP

// (4) m full C / / + Lu C 丄 = 0.12P

If 3< |AVZc| < 4,Clc4 = Clc3+2Clc5 =0ΛΊΡ

If |AV/C| > 4,C/c5=C7/=0.22P

Cst = 0MP, Vgh = l5V, Vgl = -10V, VcomH = 5V, VcomL = 0V. The above parameters are obtained for an embodiment of the present invention as follows: 5 is the gamma curve of the positive frame because = 4.787, so Clc 2 · 22, the value of Clc will change due to the value of Vp. 5 0.01(15 -y;0)+ 0O05(y;. +10) _ -0O05V;. +0.2 —"""0.005 +0Ό8+ 0.22 0305 11 1275065 -0.005 y;0 + 0.2 0 . 305 0.305 + 0.2 0.305 * 4.78 + 0.2 p〇 Similarly, 0.31 0.31 — 5.33V, Vfo = y pS = 4AV , K20 = 3.547 , V; 55 ^ 2.7 V y yr - V p62 - 2.3V, V; 63 = = 1A1V V f V fvrvfvft / , P〇^V pl^VpS^Vp 20 ^Vp 43 p 55 ^ is the new positive Frame Gamma curve V f V Fyp 62 ^ v p63 M3 The operation of the Gamma curve of the negative Frame is as follows; Δ7

• 35 V ==

2.98V η 0 0.01(15 ^y;Q) +0.0Q5 (y;g +ι〇) — 0:005 + 0.08 + 0.22 " ρ -0.005 V,;〇+0·2 Ρ〇0.305 — 7l0 , 0.305 y/l0 + 0.2 0.305 *0.22 + 0.2 n〇0.31 0.31 Similarly, Κι =0.887, y; 8 = :2·,,Κ2〇= 3.25V v;55 =4.287, y,;62 =4.67 [, H5.26V ~, 〇, dK2〇 hk62, k63 τ43

OMV

3.99V is a positive positive frame Gamma curve The correction value obtained by the above calculation method is as follows (Original Gamma level)

TpO~ Vpl Vp8 ν^20~

TW 4. 76TT~ Γ65" Gamma with feed through Ό~~ 4: 18 2.99 1. 74

Gamma level

Evel)S OFOF T4~ΌΤ 12 Ϊ275065 0.95 2· 98 0.65 2.7 0.23 2.3 -0.4 L41 -0.43 0.86 -0.41 0.88 0.54 2· 04 1.43 3.25 2.02 3.99 2.31 4. 28 2.72 4. 67 2· 98 5.26

And by the front and the bottom of the calculation of the positive and negative eight frame points grayscale telecommunications, you ^ / 曰, 4: gamma curve correction (Gamma curve, as shown in Figure 3 and the value of the wheel into the display After driving 1C, through the feed through effect w & pass effect, you can make the corrected gamma curve (Ga leg a curve) back to the ideal gamma curve (such as Figure 3 and the Φ shows) 'Vcom DC bias 5 17 does not need to adjust the common electrode to make the screen of the awarder not flash. The invention can compensate for the feed through effect ('Beton effect') of the parasitic capacitance of the display when adjusting the gamma curve (Ga wakes up a curve), so there is no need to increase the device or process. The trouble, and the adjustment method only inputs the obtained feedback value into the display 1C. Therefore, the adjustment mode is simple, and the bias voltage (Vc_DC bias) of the adjustment common electrode is not required, as shown in FIG. 5, it is not necessary. Vc (10) voltage for any adjustment,

Vc(10)H=4·78V, Vc(10)L=0V 〇 The above description of the embodiments is intended to be illustrative of the present invention and is not intended to limit the scope of the invention. 13 1275065 The righteousness of the month has made it possible for the person skilled in the art to understand the invention to achieve the aforementioned objectives, and to swear by the people. 7 Bay has paid the provisions of the Patent Law, and has filed a patent. [Simple Description of the Drawing] The f 1 diagram is a flow chart of the method for solving the problem of the feed. The second embodiment of the present invention utilizes the gray level _ penetration rate to select the gamma value. , Brother 2 B = The present invention utilizes the effective voltage versus transmittance map to correct the gamma value in Figure 2A to obtain the voltage value to be selected. Figure 3 is a diagram showing the video signal-gray scale of the embodiment of the present invention and the conventional technique. The ideal gamma curve and the ideal gamma value of the sampled gamma value 2·2 under the frame (Frame) are shown. The gamma curve of the feedthrough effect and the gamma curve of the correction. Figure 4 is a video signal-gray scale graph of the embodiment of the present invention and a conventional technique. The ideal gamma curve and ideal gamma value of the sampled gamma value 2·2 in the negative frame (Frame) are shown in the figure. The gamma curve of the feedthrough effect and the gamma curve of the correction. Fig. 5 is a graph showing the voltage-time relationship of the common electrode measurement in the embodiment of the present invention. The brother 6 shows a circuit diagram of a Cs on common type TFT (thin film transistor) subpixel. Figure 7A is a VG time-voltage diagram of the thin film transistor scan signal of Figure 6. Figure 7B is a thin film transistor video signal of Figure 6 Vs time ~ voltage off 14 1275065. [Description] (Practical part) Transistor Q Scanning signal line G Data signal line D Parasitic capacitance Cgd Liquid crystal capacitor C L C Storage capacitor Cs Common electrode Vcom

Claims (1)

1275065 X. Patent Application Range·· 1 · A method for solving the feed through effect, which includes the following steps: (1) Corresponding to the penetration rate of the effective voltage of the pain device, and the gamma curve shown as ' The sampling gamma voltage value is paid; (2) the positive and negative frame (frame) feedback values are obtained by using the sampled gamma voltage value and the transistor parameter; (3) adding the positive and negative frame (frame) feedback The value gets a new positive and negative frame (frame) gamma curve value; (4) the new gamma curve value is input into the display drive I c inside; (5) this new gamma curve (Gannna curve) through the feed After the through effect (the know-how effect), the gamma curve of the common electrode can be turned back to the ideal gamma curve without changing the bias voltage of the common electrode (vc〇m DC bias). 2 · According to the scope of claim 1 of the patent application, the method of solving the feec [through effect] where 'sampling gamma (Ga leg a) voltage value and transistor parameters include · · C1 c (liquid crystal capacitance value), Cgdon ( Capacitance value when parasitic capacitance is on), Cgdoff (capacitance value when parasitic capacitance is off) and input video signal Vs (Video signal), VGH (scanning signal high level), VGL (scanning signal low level), VcomH ( Common electrode signal high level), VcomL (common electrode signal low level). 3. The solution described in item 1 of the patent application scope; the method of the feed through effect' wherein the feedback values of the positive and negative frames are obtained in the calculation of the feedthrough voltage. 16