JP3960780B2 - Driving method of active matrix display device - Google Patents

Driving method of active matrix display device Download PDF

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Publication number
JP3960780B2
JP3960780B2 JP2001350509A JP2001350509A JP3960780B2 JP 3960780 B2 JP3960780 B2 JP 3960780B2 JP 2001350509 A JP2001350509 A JP 2001350509A JP 2001350509 A JP2001350509 A JP 2001350509A JP 3960780 B2 JP3960780 B2 JP 3960780B2
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auxiliary capacitance
auxiliary
voltage
video signal
electrode
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JP2003150127A (en
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康志 宮島
良一 横山
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三洋電機株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for driving an active matrix display device.
[0002]
[Prior art]
In an active matrix display device that supplies each image signal to a separate pixel electrode via a switching element such as a thin film transistor (TFT), AC driving for applying an AC potential to the counter electrode and the auxiliary capacitor is performed. Thus, the deterioration of the liquid crystal is prevented, and at the same time, the potential difference between the positive and negative polarity of the video signal input to the drain driver is reduced, and the current and voltage of the drain driver are reduced, thereby realizing low power consumption.
[0003]
However, in the horizontal inversion counter electrode AC driving that inverts the video signal polarity applied to each drain line every horizontal period, the polarity of the voltage of the counter electrode and all the auxiliary capacitance lines is inverted every horizontal period. Capacitive loads in all auxiliary capacity lines and the power consumption due to them were still large.
[0004]
Therefore, in order to realize further reduction in power consumption, by reversing the polarity of the voltage of the auxiliary capacitor, the power consumption can be remarkably reduced by making the counter electrode voltage constant, and at the same time, the video signal Japanese Patent Laid-Open No. 12-81606 discloses a driving method (hereinafter referred to as “SC driving”) in which the potential difference between the positive and negative electrodes is reduced and the current and voltage of the drain driver are reduced. Hereinafter, an active matrix liquid crystal display device using SC drive will be described.
[0005]
FIG. 10 is an equivalent circuit diagram of a display panel in an active matrix liquid crystal display device using SC drive. The drain line 105 and the gate line 107 are arranged so as to intersect with each other. At the intersection, a TFT 109 serving as a switching element and a liquid crystal capacitor 112, an auxiliary capacitor 110, and an auxiliary capacitor 110 each having one of the capacitor electrodes connected to the TFT 109 are provided. The storage capacitor line 108 is connected to the other of the capacitor electrodes. The auxiliary capacitance line 108 is arranged in parallel with the gate line 107 and is common to the auxiliary capacitance 110 connected to the same gate line 107. The other of the capacitor electrodes of the liquid crystal capacitor 112 is a counter electrode 111 provided integrally with a substrate on which the TFT 109 is provided and a substrate on the opposite side across the liquid crystal.
[0006]
FIG. 11 shows a signal waveform for driving a display panel focusing on one pixel. Here, the gate voltage V G , Pixel voltage V P , Source voltage V S , Video signal voltage V D , Auxiliary capacitance voltage V SC , Counter electrode voltage V COM It is shown. Gate voltage V G Has an ON period once in one frame. The gate voltage V applied to the gate line 107 during the ON period of the gate G Becomes a high level (hereinafter referred to as “High”). During this period, the TFT 109 is turned on and the drain-source is made conductive, and the source voltage V S Is the video signal voltage V applied to the drain line 105. D To the same level and applied to one of the liquid crystal capacitor 112 and the auxiliary capacitor 110. When the gate is off, the gate voltage V G Becomes low (hereinafter referred to as “Low”) level, the TFT 109 is turned off, and the source voltage V S And the gate voltage V G ΔV with the fall of S Only the level drops and V PL It becomes. Counter electrode voltage V COM Is a constant voltage and the source voltage V S Drop ΔV S Only, the video signal voltage V D The center level is lower than the center level Vc.
[0007]
Each auxiliary capacitance line 108 has a gate voltage V applied to the corresponding gate line 107. G Auxiliary capacitance voltage V that reverses after falling SC Is applied. Auxiliary capacitance voltage V SC Is V SCH And V SCL Inverted at two levels, for example, source voltage V S Is the counter electrode voltage V COM In the higher positive polarity period, the gate voltage V G After the fall of the low level V SCL To high level V SCH Stand up to. Therefore, the gate voltage V G Falls and source voltage V S The pixel voltage V once determined P Is the auxiliary capacitance voltage V through the auxiliary capacitance 110 SC ΔV affected by the rise of P Only rise. Pixel voltage V at this time P Is held during the gate OFF period, that is, for one frame.
[0008]
Auxiliary capacitance voltage V SC , The charge redistribution between the liquid crystal capacitor 112 and the auxiliary capacitor 110 occurs, and the pixel voltage V P Is ΔV P = V PH -V PL Only rise. Source voltage V S Is the counter electrode voltage V COM Conversely, in the lower negative electrode period, the auxiliary capacitance voltage V SC Falls from the positive side to the negative side, so the pixel voltage V P Is ΔV P Just descend. As a result, the pixel voltage V P And the voltage applied to the liquid crystal capacitor 112 can be increased. That is, the auxiliary capacitance voltage V SC Is inverted to two levels to counter electrode voltage V COM The video signal voltage V D Can be reduced in amplitude.
[0009]
Usually, the auxiliary capacitor 110 is sufficiently larger than the liquid crystal capacitor 112, and therefore, the change ΔV in the pixel voltage. P Is the fluctuation V (V SCH -V SCL ). Therefore, a larger voltage is applied to the liquid crystal capacitor 112 even if the current flowing through the auxiliary capacitor line is small. That is, by changing the auxiliary capacitance voltage, the video signal voltage V D The amplitude is reduced.
[0010]
Now, as the number of pixels increases, the plurality of drain lines 105 are simultaneously turned on, and the video signal voltage V V is simultaneously applied to the plurality of liquid crystal capacitors 112 and the auxiliary capacitors 110. D The drive method which applies is used. As a result, the drain line 105 is connected to the liquid crystal capacitor 112 and the auxiliary capacitor 110 by the video signal voltage V. D It is possible to ensure a sufficient time for applying.
[0011]
In particular, when a large or high-definition display panel is driven dot-sequentially, dozens of drain lines 105 are simultaneously turned on, and video signal voltage V is simultaneously applied to dozens of liquid crystal capacitors 112 and auxiliary capacitors 110. D Apply. As described above, when several tens of drain lines 105 are turned on at the same time, a large capacitive coupling occurs in a portion where the drain line 105 that is turned on and the auxiliary capacitance line 108 overlap. Due to this capacitive coupling, the voltage of the auxiliary capacitance line 108 and the gate line 107 fluctuates due to the influence of the voltage of the drain line 105. Due to this voltage change, image unevenness may occur in units of drain lines 105 that are simultaneously turned on.
[0012]
[Problems to be solved by the invention]
In order to prevent capacitive coupling and image unevenness due to this, voltages having different polarities are applied to pixel electrodes adjacent in the gate line direction, and voltages having the same polarity are applied to pixel electrodes adjacent in the drain line direction. The vertical inversion driving as shown in FIG. 12A or the dot inversion driving in which the reverse polarity is applied to all the pixels adjacent to the upper, lower, left, and right as shown in FIG. 12B can be considered. In either driving method, in order to prevent deterioration of the liquid crystal, a voltage having a polarity opposite to that of the previous frame is applied every frame. In order to prevent capacitive coupling more effectively, it is conceivable to reduce the number of adjacent pixel electrodes to which the same polarity voltage is applied. Therefore, an object of the present invention is to realize so-called dot inversion by applying voltages having different polarities to each adjacent pixel electrode or electrodes in SC driving.
[0013]
[Means for Solving the Problems]
The present invention has been made to achieve the above object, and includes a plurality of pixel electrodes arranged in a matrix on a first substrate, switching elements connected to the pixel electrodes, and the pixels. Auxiliary capacitance electrodes arranged for each pixel region where electrodes are arranged, first and second auxiliary capacitance lines arranged corresponding to the pixel electrodes in each row, and the first or second auxiliary capacitance A first video signal voltage having a first and a second auxiliary capacitor in which one of the lines and the auxiliary capacitor electrode are opposed to each other, the polarity of which is inverted every frame period, or the first video In the driving method of an active matrix display device for performing display by applying any one of the second video signal voltages having the opposite polarity to the signal to the pixel electrode and the auxiliary capacitance electrode, The first and second auxiliary capacitors are supplied to the first and second auxiliary capacitor lines by supplying first and second auxiliary capacitor voltages whose levels change during the period when the switching element is turned off. This is a method for driving an active matrix display device that amplifies the voltage held by.
[0014]
Alternatively, a plurality of pixel electrodes arranged in a matrix on the first substrate, a switching element connected to each of the pixel electrodes, and an auxiliary capacitance electrode arranged for each pixel region where the pixel electrode is arranged And first and second auxiliary capacitance lines arranged corresponding to the pixel electrodes in each row, and either the first or second auxiliary capacitance line and the auxiliary capacitance electrode are opposed to each other. And a second auxiliary capacitor, and a first video signal voltage whose polarity is inverted every frame period or a second video signal voltage having a polarity opposite to that of the first video signal. In the driving method of the active matrix display device that performs display by applying the voltage to the pixel electrode and the auxiliary capacitance electrode, the switching element is turned on during the period when the switching element is on. The pixel electrode in which the auxiliary capacitance is arranged and the pixel electrode in which the second auxiliary capacitance is arranged by supplying the first video signal voltage to the auxiliary capacitance electrode constituting the first auxiliary capacitance In addition, the second video signal voltage is supplied to the auxiliary capacitance electrode constituting the second auxiliary capacitance, and is supplied to the first auxiliary capacitance line during a period in which the switching element is turned off. The first auxiliary capacitance voltage changes in level to the same polarity as the first video signal voltage, and the second auxiliary capacitance voltage supplied to the second auxiliary capacitance line is the second video signal. This is a driving method of an active matrix display device that amplifies the voltage held by the first and second auxiliary capacitors by changing the level to the same polarity as the voltage.
[0015]
Alternatively, a plurality of pixel electrodes arranged in a matrix on the first substrate, a switching element connected to each of the pixel electrodes, and an auxiliary capacitance electrode arranged for each pixel region where the pixel electrode is formed And first and second auxiliary capacitance lines arranged corresponding to the pixel electrodes of each row, a first auxiliary capacitance formed by the first auxiliary capacitance line and the auxiliary capacitance electrode facing each other, A second auxiliary capacitance formed by the second auxiliary capacitance line and the auxiliary capacitance electrode facing each other; and a first video signal voltage whose polarity is inverted every frame period, or the first auxiliary capacitance line In the driving method of the active matrix display device for performing display by applying any one of the second video signal voltages having the opposite polarity to the video signal to the pixel electrode, the switching element During the on-period, the first video signal voltage is applied to the pixel electrode in which the first auxiliary capacitor is disposed and the auxiliary capacitor electrode constituting the first auxiliary capacitor. A first auxiliary capacitance voltage having a polarity opposite to that of the first video signal voltage is supplied to the auxiliary capacitance line, and a pixel electrode on which the second auxiliary capacitance is arranged and the second auxiliary capacitance The second auxiliary capacitance having the opposite polarity to the second video signal voltage for the auxiliary capacitance electrode and the second auxiliary capacitance line for the second auxiliary capacitance line. In the period when the voltage is supplied and the switching element is turned off, the level of the first auxiliary capacitance voltage changes to the same polarity as the first video signal voltage, and the second auxiliary capacitance voltage is Level to the same polarity as the video signal voltage of 2 By changing a driving method of an active matrix display device which amplifies the voltage of the first and second auxiliary capacitance is maintained.
[0016]
Further, in the active matrix display device, a common electrode is disposed on a second substrate, and a constant voltage is applied to the common electrode. It is.
[0017]
Further, in the driving method of the active matrix display device, the level of the first and second auxiliary capacitance voltages changes immediately after the switching element is turned off during the period when the switching element is turned off.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment will be described. FIG. 1 is a plan view of a display panel in an active matrix display device, FIG. 2 is a plan view of the display panel according to the first embodiment, and FIG. 3 is an equivalent circuit diagram thereof.
[0019]
First, in FIG. 1, the display panel 1 has a drain driver 2 arranged in the row direction and a gate driver 3 arranged in the column direction. A display area 4 for displaying an image is disposed so as to be surrounded by the drain driver 2 and the gate driver 3.
[0020]
As shown in FIGS. 2 and 3, in the display region 4, a plurality of drain lines 5 and a plurality of rectangular pixel electrodes 6 extending in the column direction are arranged in the column direction, and gate lines are arranged in the row direction. 7, a first auxiliary capacitance line 8a and a second auxiliary capacitance line 8b are arranged. In a region where each pixel electrode 6 is disposed (hereinafter referred to as “pixel region”), either the TFT 9 or the first auxiliary capacitor 10a or the second auxiliary capacitor 10b is disposed. The TFT 9 includes a gate electrode 9g formed extending from the gate line 7, a drain region 9d of a semiconductor layer electrically connected to the drain line 5 via a contact, and a pixel electrode 6 and a contact electrically. It is composed of a source region 9s of a connected semiconductor layer. The first auxiliary capacitance 10a is formed by an auxiliary capacitance electrode 10x made of a semiconductor layer connected to the TFT 9 and an auxiliary capacitance electrode 10y formed extending from the first auxiliary capacitance line 8a. The second auxiliary capacitance 10b is formed by the auxiliary capacitance electrode 10x and the auxiliary capacitance electrode 10z formed extending from the second auxiliary capacitance line 8b. In addition, a counter electrode 11 is provided on the opposite side of the substrate on which the TFT 9 is provided and the liquid crystal, thereby forming an auxiliary capacitance electrode corresponding to the pixel electrode 6 of the liquid crystal capacitance 12.
[0021]
As shown in FIG. 1, the drain driver 2 receives the first video signal voltage VDa and the second video signal voltage VDb having opposite polarities, and selects the drain line 5 in order to perform the first operation. The video signal voltage VDa or the second video signal voltage VDb is applied. The gate driver 3 sequentially selects the gate lines 7 and applies the gate signal GV. The display area 4 has a plurality of pixel electrodes 6 and displays video. The drain line 5 is a wiring for transmitting either the first video signal voltage VDa or the second video signal voltage VDb having opposite polarities to the TFT 9 through a contact. The pixel electrode 6 constitutes a pixel region which is a display unit, and is an electrode which drives the liquid crystal by the video signal voltage VD transmitted from the drain line 5 through the TFT 9 together with the counter electrode 11. The gate line 7 is selected by the gate driver 3, and when the gate signal GV is applied, the connected TFT 9 is turned on. The first auxiliary capacitance line 8a is formed integrally with the auxiliary capacitance electrode 10y arranged in the row direction in the same layer as the gate line 7, and connects the first auxiliary capacitances in each row to each other. The second auxiliary capacitance line 8b is integrated with the auxiliary capacitance electrode 10z arranged in the row direction in the same layer as the gate line 7, and connects the second auxiliary capacitances in each row to each other. The first auxiliary capacitance line 8a is supplied with a first auxiliary capacitance voltage, and the second auxiliary capacitance line 8b is supplied with a second auxiliary capacitance having a polarity opposite to that of the first auxiliary capacitance voltage. Voltage is supplied. The TFT 9 is a semiconductor directly below the gate electrode 9g in either the direction from the source region 9s to the drain region 9d or the direction from the drain region 9d to the source region 9s only when a voltage is applied to the gate electrode 9g. A switching element in which a current flows in the channel region of the layer. The first auxiliary capacitor 10 a and the second auxiliary capacitor 10 b hold the charge due to the video signal voltage VD supplied from the drain line 5 via the TFT 9 for one frame period, and compensate for the charge loss of the liquid crystal capacitor 12. A constant voltage is applied to the counter electrode 11, and the liquid crystal is driven together with the pixel electrode 6 in accordance with the video signal voltage VD applied to the pixel electrode 6. The liquid crystal capacitor 12 is a charge due to the video signal voltage VD supplied from the drain line 5 held by the liquid crystal via the TFT 9. However, the charge held by the liquid crystal capacitor 12 is very small compared to the charge held by the first auxiliary capacitor 10a and the second auxiliary capacitor 10b, and is caused by leakage due to an off operation of the TFT 9 or leakage from impurities in the liquid crystal. Since it tends to flow out, the charge is supplemented by the charge held by the first auxiliary capacitor 10a and the second auxiliary capacitor 10b.
[0022]
Next, a driving method will be described. FIG. 4 is a timing chart showing the relationship between signals in the display panel. This is the timing of voltage change in the vertical start signal STV and the gate signal GV, the horizontal start signal STH and the horizontal clock signal CKH, and the potential SCa of the first auxiliary capacitance line 8a and the potential SCb of the second auxiliary capacitance line 8b. Show.
[0023]
First, the pulse of the gate signal GV1 rises in response to the fall of the pulse of the vertical start signal STV, the gate signal GV1 is supplied to the gate line 7 in the first row, and the TFT 9 connected thereto is turned on. Then, the pulse of the horizontal start signal STH rises, and the pulse of the first horizontal clock signal CKH rises in the period when the gate line 7 of the first row is selected in synchronization with the fall of this pulse. During the period in which the gate signal GV1 is supplied to the gate line 7 in the first row, the pulses of the horizontal clock signal CKH sequentially rise, and the drain lines 5 are sequentially selected in synchronization with the rise of these pulses, and the video is sequentially turned on. The signal voltage VD is applied to the pixel electrode 6, the first auxiliary capacitor 10a, and the second auxiliary capacitor 10b through the TFT 9. The first video signal voltage VDa is applied to the pixel electrode 6 and the first auxiliary capacitor 10a, and the second video signal voltage VDb is applied to the pixel electrode 6 and the second auxiliary capacitor 10b. When the video signal voltage VD is applied to all the drain lines 5, the gate signal GV1 is not supplied to the gate line 7 in the first row, and the TFT 9 connected thereto is turned off. Then, the pulses of the gate signal GV2 and the gate signal GV3 sequentially rise, the gate signal GV2 is applied to the second gate line 7, the gate signal GV3 is applied to the third gate line 7, and the like. Repeat the operation. While the TFT 9 connected to the gate line 7 is in an OFF state, that is, during a period when the gate signal GV is not supplied to the gate line 7, the potential SCa of the first auxiliary capacitance line 8a and the second auxiliary capacitance line 8b The polarity of the potential SCb is inverted. Then, when the gate signal GV is supplied to all the gate lines 7, the pulse of the vertical start signal STV rises again, and the gate signal GV is supplied to the gate line 7 in the first row in synchronization therewith, and the same operation is performed. repeat.
[0024]
FIG. 5 is a signal waveform diagram showing a driving method of the display device according to the first embodiment, and shows a signal waveform between one frame in a pixel region adjacent in the gate line direction. 5A shows a signal waveform of the first auxiliary capacitor 10a, and FIG. 5B shows a signal waveform of the second auxiliary capacitor 10b. The signal waveform shown in FIG. 5 (a) is almost the same as that in FIG. 11, but the signal waveform shown in FIG. 5 (b) is just the polarity reversed from FIG.
[0025]
The active matrix display device according to the present embodiment includes an auxiliary capacitor arranged for each pixel region in which pixel electrodes are formed and an auxiliary capacitor electrode formed integrally with a plurality of pixel electrodes arranged in the row direction and arranged in the row direction. The first video signal voltage having first and second auxiliary capacitance lines connected to every other frame, the polarity of which is inverted every frame period, and the polarity opposite to the first video signal voltage By performing display by applying any one of the second video signal voltages having the above to the pixel electrode via the switching element, so-called dot inversion driving by the auxiliary capacitance line can be realized. In the active matrix display device, the first auxiliary signal having the first auxiliary capacitor line is supplied to the first auxiliary capacitor having the first auxiliary capacitor line and the second auxiliary capacitor at the same time as the switching element is turned on. A second video signal voltage is supplied to a second auxiliary capacitor having a line, but when the switching element is turned off, the voltage supplied to the first and second auxiliary capacitors flows out. End up. However, in this active matrix display device, the first auxiliary capacitance voltage whose level changes to the polarity of the voltage held by the first auxiliary capacitance is applied to the first auxiliary capacitance line during the period when the switching element is turned off. The second auxiliary capacitance line is supplied with a second auxiliary capacitance voltage having a polarity opposite to that of the first auxiliary capacitance voltage and whose level changes to the polarity of the voltage held by the first auxiliary capacitance. By supplying, it is possible to compensate for the voltages of the first and second auxiliary capacitors that have fluctuated due to the OFF operation of the switching element, and to amplify the voltage supplied to the first and second auxiliary capacitors. it can.
[0026]
In the present embodiment, by performing dot inversion driving, the influence of the adjacent video signal voltage is eliminated and image unevenness due to capacitive coupling is prevented. Further, the amplitude of the video signal voltage is narrowed by applying either the first or second auxiliary capacitance voltage to the first and second auxiliary capacitance lines during the period when the switching element is turned off. Therefore, power consumption can be reduced.
[0027]
In the present embodiment, the first and second auxiliary capacitance lines are configured to have auxiliary capacitance electrodes alternately in the row direction in units of one pixel electrode in order to reduce image unevenness and flicker as much as possible. However, the present invention is not limited to this, and a configuration may be adopted in which auxiliary capacitor electrodes are alternately provided in units of a plurality of columns of continuous pixel electrodes. For example, three pixel electrodes for displaying RGB primary colors may be used as one unit, and each unit may have an auxiliary capacitance electrode in either the first or second auxiliary capacitance line.
[0028]
By the way, in the present embodiment, as shown in FIG. 2, the first auxiliary capacitance line 8a and the second auxiliary capacitance line 8b are formed so as to overlap all the auxiliary capacitance electrodes 10x. Then, only in the pixel region where the auxiliary capacitance electrode 10z forming the second auxiliary capacitance line 8b and the second auxiliary capacitance 10b exists, the first auxiliary capacitance line 8a and the semiconductor layer continuous with the auxiliary capacitance electrode 10z are formed. Parasitic capacitance C in the overlapping portion 13 to be overlapped PAR Will occur.
[0029]
Therefore, a second embodiment will be described. In the second embodiment, the parasitic capacitance C PAR Is to solve the problem caused by being formed only in the second auxiliary capacitor 10b. FIG. 6 is a plan view of a display panel according to the second embodiment, and FIG. 7 is an equivalent circuit diagram thereof. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0030]
The present embodiment is different from the first embodiment in that a dummy wiring 14 is formed in the pixel region having the auxiliary capacitance electrode 10y so as to extend from the auxiliary capacitance electrode 10y and overlaps the second auxiliary capacitance line 8b. It is a point provided. The dummy wiring 14 forms a parasitic capacitance in the overlapping portion 13 between the auxiliary capacitance electrode 10z and the first auxiliary capacitance line 8a by forming an overlapping portion 13 'with the second auxiliary capacitance line 8b that does not form an auxiliary capacitance. C PAR Parasitic capacitance C equal to PAR ' Form.
[0031]
In the first embodiment, the parasitic capacitance C only in the overlapping portion 13 of the auxiliary capacitance electrode 10z and the first auxiliary capacitance line 8a. PAR As a result, only the potential of the second auxiliary capacitor 10b having the auxiliary capacitor electrode 10z is lowered. For this reason, a difference occurs in the magnitude of the counter electrode voltage optimum for the pixel electrode 6 in each pixel region between the pixel region where the auxiliary capacitance electrode 10y exists and the pixel region where the auxiliary capacitance electrode 10z exists. Variation and flicker occurred. However, in the present embodiment, by forming the dummy wiring 14 on the first auxiliary capacitance electrode 10x, the second auxiliary capacitance line 8b and the dummy wiring 14 that do not form an auxiliary capacitance with the first auxiliary capacitance electrode 10x are formed. Overlapping portion 13 'is formed where there is a parasitic capacitance C PAR ' Was generated. As a result, by balancing the polarity between the first auxiliary capacitor 10a and the second auxiliary capacitor 10b, it is possible to eliminate the difference in the magnitude of the counter electrode voltage optimum for each pixel electrode 6, and this difference. It is possible to eliminate contrast variation and flicker caused by the above.
[0032]
Next, a third embodiment will be described. FIG. 8 is a plan view of a display panel according to the third embodiment, and FIG. 9 is an equivalent circuit diagram thereof. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the arrangement of the drain line 5 and the pixel electrode 6 is the same as in the first and second embodiments.
[0033]
The present embodiment is different from the first and second embodiments in that the gate line 7 is sandwiched between the first auxiliary capacitance line 8a and the second auxiliary capacitance line 8b in the central portion of the pixel electrode. It is that it is arranged like this. In each pixel region, the gate electrode formed integrally with the gate line 7 and constituting the TFT 9 is formed in the region where the auxiliary capacitance electrode 10x is disposed with the gate line 7 as a boundary line. .
[0034]
In the second embodiment, since dummy wiring is provided in addition to the originally required auxiliary capacitance electrode, the pattern is complicated and the aperture ratio is reduced. However, in the present embodiment, since the gate line 7 is disposed between the first auxiliary capacitance line 8a and the second auxiliary capacitance line 8b, all the auxiliary capacitance electrodes 10x constitute the auxiliary capacitance. In order to overlap only one auxiliary capacitance line 8a or the second auxiliary capacitance line 8b, the overlapping portion 13 and the overlapping portion 13 ′ themselves are eliminated, and the parasitic capacitance C generated in the overlapping portion is eliminated. PAR Can also be eliminated. Furthermore, in this embodiment, the distance between the second auxiliary capacitance line 8b and the TFT 9 can be shortened to reduce the wiring resistance. Since the area of the semiconductor layer required for forming the auxiliary capacitance electrode 10z in the first embodiment and the dummy wiring 14 in the second embodiment can be reduced, the aperture ratio is improved.
[0035]
In each embodiment, a double gate type TFT is exemplified, but the present invention is not limited to this, and the number of gate electrodes may be one or more. Further, although the auxiliary capacitance line is formed in the same layer as the gate line, the present invention can be implemented even if the auxiliary capacitance line is formed in a layer different from the gate line.
[0036]
Furthermore, in each embodiment, the active matrix type liquid crystal display device has been exemplified, but the present invention is not limited to this, and can be applied to an active matrix type EL display device.
[0037]
【The invention's effect】
The present invention relates to an active matrix display device in which a pixel electrode formed on a first substrate, a switching element connected to the pixel electrode, and an auxiliary capacitance electrode arranged for each pixel region in which the pixel electrode is formed. A first auxiliary capacitance formed by facing a first auxiliary capacitance line arranged corresponding to the plurality of pixel electrodes, and a second auxiliary capacitance line arranged corresponding to the plurality of pixel electrodes, And a second auxiliary capacitor that is opposed to the auxiliary capacitor electrode, and has a first video signal voltage whose polarity is inverted every frame period or a polarity opposite to that of the first video signal. An active matrix type capable of realizing so-called dot inversion driving by an auxiliary capacitance line by performing display by applying one of the second video signal voltages to the pixel electrode A driving method shown apparatus. Then, during the period when the switching element is turned on, the first video signal voltage is supplied to the auxiliary capacitance electrode constituting the first auxiliary capacitance, and at the same time, the auxiliary capacitance electrode constituting the second auxiliary capacitance is applied to the auxiliary capacitance electrode. On the other hand, the second video signal voltage is supplied. However, when the switching element is turned off, the voltage supplied to the first and second auxiliary capacitors flows out. However, during the period in which the switching element is turned off, the first auxiliary capacitance voltage whose level changes to the polarity of the voltage held by the first auxiliary capacitance is supplied to the first auxiliary capacitance line at the same time. Second auxiliary capacitance line opposite to the first auxiliary capacitance voltage with respect to the second auxiliary capacitance line facing the capacitance electrode, and the level changes to the polarity of the voltage held by the first auxiliary capacitance By supplying the capacitance voltage, it is possible to compensate and amplify the voltage held by the first and second auxiliary capacitances that fluctuated due to the off operation of the switching element.
[0038]
Further, in the active matrix display device having the above structure, the first video signal voltage whose polarity is inverted every frame period or the second video signal voltage having the opposite polarity to the first video signal. In the driving method of an active matrix display device that performs display by applying any one to the pixel electrode and the auxiliary capacitance electrode, the pixel electrode in which the first auxiliary capacitance is arranged and the switching element are turned on during the period when the switching element is on A first video signal voltage is supplied to the auxiliary capacitance electrode constituting the first auxiliary capacitance, and the pixel electrode in which the second auxiliary capacitance is arranged and the auxiliary capacitance electrode constituting the second auxiliary capacitance. On the other hand, during the period when the second video signal voltage is supplied and the switching element is turned off, the first auxiliary capacitance voltage supplied to the first auxiliary capacitance line is the first video signal voltage. The level is changed to the same polarity as the signal voltage, and the second auxiliary capacitance voltage set to the second auxiliary capacitance line is changed to the same polarity as the second video signal voltage, so that the switching element is turned off. It is possible to compensate for and further amplify the voltage held by the first and second auxiliary capacitors that have been changed by the operation.
[0039]
In the active matrix display device having the above-described configuration, the first video signal voltage whose polarity is inverted every frame period or the second video signal voltage having the opposite polarity to the first video signal. In the driving method of the active matrix display device that performs display by applying any of the above to the pixel electrode, the pixel electrode in which the first auxiliary capacitor is arranged and the first electrode are provided during the period when the switching element is on. A first video signal voltage is applied to the auxiliary capacitance electrode constituting the auxiliary capacitance, and a first auxiliary capacitance voltage having a polarity opposite to that of the first video signal voltage is applied to the first auxiliary capacitance line. The second video signal voltage is supplied to the pixel electrode on which the second auxiliary capacitor is provided and the auxiliary capacitor electrode constituting the second auxiliary capacitor, and the second auxiliary capacitor line is supplied to the second auxiliary capacitor line. Supplies a second auxiliary capacitance voltage having a polarity opposite to that of the second video signal voltage, and the first auxiliary capacitance voltage has the same polarity as the first video signal voltage during a period when the switching element is turned off. The voltage held by the first and second auxiliary capacitors that have been changed due to the OFF operation of the switching element due to the change in level to the same polarity as the second video signal voltage. Can be further amplified.
[0040]
Further, in this active matrix display device, a common electrode is arranged on the second substrate, and by applying a constant voltage to the common electrode, fluctuations in the voltage of the common electrode having a large area are eliminated. Therefore, the active matrix display device can be driven with a lower voltage and power consumption.
[0041]
Further, in the OFF period of the switching element, immediately after the switching element is turned off, the first and second auxiliary capacitance voltages are leveled so that the switching element is less affected by the OFF operation. Since the charge of the auxiliary capacitor that has fluctuated while the fluctuation of the voltage held by the auxiliary capacitor is small can be compensated, more charge is used to amplify the voltage held by the first and second auxiliary capacitors. Can do.
[0042]
As a result, an active matrix display device with low power consumption and high display quality can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view of a display panel of an active matrix display device.
FIG. 2 is a plan view of the display panel according to the first embodiment of the present invention.
FIG. 3 is an equivalent circuit diagram of the display panel according to the first embodiment of the present invention.
FIG. 4 is a timing chart showing the relationship between signals in the display panel according to the first embodiment of the present invention.
FIG. 5 is a signal waveform diagram showing a driving method of the display device according to the first embodiment of the present invention.
FIG. 6 is a plan view of a display panel according to a second embodiment of the present invention.
FIG. 7 is an equivalent circuit diagram of a display panel according to the second embodiment of the present invention.
FIG. 8 is a plan view of a display panel according to a third embodiment of the present invention.
FIG. 9 is an equivalent circuit diagram of a display panel according to a third embodiment of the present invention.
FIG. 10 is an equivalent circuit diagram of a conventional display panel.
FIG. 11 is a signal waveform diagram illustrating a driving method of a conventional display device.
FIG. 12 is a conceptual diagram showing vertical inversion driving and dot inversion driving.
[Explanation of symbols]
1: Display panel
2: Drain driver
3: Gate driver
4: Display area
5: Drain line
6: Pixel electrode
7: Gate line
8a: first auxiliary capacity line
8b: Second auxiliary capacity line
9: TFT
10a: first auxiliary capacity
10b: second auxiliary capacity
11: Counter electrode
12: Liquid crystal capacity
13, 13 ': Overlapping part
14: Dummy wiring
105: Drain line
107: Gate line
108: Auxiliary capacity line
109: TFT
110: Auxiliary capacity
111: Counter electrode
112: Liquid crystal capacity

Claims (5)

  1. A plurality of pixel electrodes arranged in a matrix on the first substrate;
    A switching element connected to each of the pixel electrodes;
    First and second auxiliary capacitance lines extending in the row direction corresponding to each row of the pixel electrodes;
    An auxiliary capacitance electrode arranged for each pixel so as to overlap with one of the first or second auxiliary capacitance lines,
    Either the first video signal voltage whose polarity is inverted every frame period or the second video signal voltage having the opposite polarity to the first video signal is used as the pixel electrode and the auxiliary capacitance electrode. In a driving method of an active matrix display device that performs display by applying to
    The parasitic capacitance of the portion where the other of the first or second auxiliary capacitance line and the extended portion of the auxiliary capacitance electrode overlap is equal in each pixel,
    The first and second auxiliary capacitances are supplied to the first and second auxiliary capacitance lines by supplying first and second auxiliary capacitance voltages whose levels change during a period in which the switching element is turned off, respectively. A method for driving an active matrix display device, comprising amplifying a voltage held by the active matrix display device.
  2. A plurality of pixel electrodes arranged in a matrix on the first substrate;
    A switching element connected to each of the pixel electrodes;
    First and second auxiliary capacitance lines extending in the row direction corresponding to each row of the pixel electrodes;
    An auxiliary capacitance electrode arranged for each pixel so as to overlap with one of the first or second auxiliary capacitance lines,
    Either the first video signal voltage whose polarity is inverted every frame period or the second video signal voltage having the opposite polarity to the first video signal is used as the pixel electrode and the auxiliary capacitance electrode. In a driving method of an active matrix display device that performs display by applying to
    The parasitic capacitance of the portion where the other of the first or second auxiliary capacitance line and the extended portion of the auxiliary capacitance electrode overlap is equal in each pixel,
    During a period in which the switching element is turned on, the first video signal voltage is supplied to the pixel electrode in which the first auxiliary capacitor is disposed and the auxiliary capacitor electrode constituting the first auxiliary capacitor. The second video signal voltage is supplied to the pixel electrode in which the second auxiliary capacitor is disposed and the auxiliary capacitor electrode constituting the second auxiliary capacitor,
    During a period in which the switching element is turned off, the level of the first auxiliary capacitance voltage supplied to the first auxiliary capacitance line changes to the same polarity as the first video signal voltage, and the second auxiliary capacitance voltage When the level of the second auxiliary capacitance voltage supplied to the auxiliary capacitance line changes to the same polarity as the second video signal voltage,
    A driving method of an active matrix display device, wherein the voltage held by the first and second auxiliary capacitors is amplified.
  3. A plurality of pixel electrodes arranged in a matrix on the first substrate;
    A switching element connected to each of the pixel electrodes;
    First and second auxiliary capacitance lines extending in the row direction corresponding to each row of the pixel electrodes;
    An auxiliary capacitance electrode arranged for each pixel so as to overlap with one of the first or second auxiliary capacitance lines,
    By applying to the pixel electrode either the first video signal voltage whose polarity is inverted every frame period or the second video signal voltage having the opposite polarity to the first video signal In a driving method of an active matrix display device that performs display,
    The parasitic capacitance of the portion where the other of the first or second auxiliary capacitance line and the extended portion of the auxiliary capacitance electrode overlap is equal in each pixel,
    During a period in which the switching element is turned on, the first video signal voltage is applied to the pixel electrode in which the first auxiliary capacitor is disposed and the auxiliary capacitor electrode constituting the first auxiliary capacitor. A first auxiliary capacitance voltage having a polarity opposite to that of the first video signal voltage is supplied to the first auxiliary capacitance line, and a pixel electrode on which the second auxiliary capacitance is disposed and the first auxiliary capacitance line The second video signal voltage is applied to the auxiliary capacitor electrode constituting the second auxiliary capacitor, and the second video signal voltage is opposite to the second video signal voltage for the second auxiliary capacitor line. 2 auxiliary capacity voltage,
    During a period in which the switching element is turned off, the first auxiliary capacitance voltage changes in level to the same polarity as the first video signal voltage, and the second auxiliary capacitance voltage becomes the second video signal voltage. By changing the level to the same polarity as
    A driving method of an active matrix display device, wherein the voltage held by the first and second auxiliary capacitors is amplified.
  4.   4. The active matrix display device according to claim 1, wherein a common electrode is disposed on a second substrate, and a constant voltage is applied to the common electrode. 5. Driving method for an active matrix display device.
  5.   5. The level of the first and second auxiliary capacitance voltages changes immediately after the switching element is turned off in a period in which the switching element is turned off. 6. Driving method for an active matrix display device.
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