JPH11161235A - Liquid crystal display device and driving method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device displaying a high quality image. SOLUTION: A liquid crystal panel 1 is provided with switching elements arranged in the form of matrix in intersections between gate buses and drain buses, and in the switching element, a gate electrode is connected to the gate bus while a source electrode is connected to the drain bus respectively. In the liquid panel 1, two source driver IC units 3a, 3b supplying source signals, which are inverted around a predetermined voltage in every fixed period, to the source electrodes in the switching elements respectively are arranged on the both sides. Each of the two source driver IC units 3a, 3b is connected to two signal lines alternately, and an inverted source signal is supplied to the adjacent signal line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display and a method for driving the same.

[0002]

2. Description of the Related Art One pixel in a liquid crystal display device is RG.
Each unit of B (R: red, G: green, B: blue) is configured, and one dot (one pixel) represents each of R, G, and B as one unit. That is, one pixel has three dots (3
Pixel). With the active matrix drive system, switching elements and capacitor elements are added and integrated as necessary for each dot at the intersection of the matrix of scanning lines and signal lines to improve display performance such as contrast and response. It is a driving method.

FIG. 3 is a configuration diagram showing a liquid crystal display device based on an active matrix driving method. In the figure,
1 is a liquid crystal panel constituting a display unit, 2 is a gate driver IC unit for supplying a gate signal to a scanning line of the liquid crystal panel 1,
3 is a source driver IC unit for supplying a data signal to a signal line of the liquid crystal panel 1, 4 is a control circuit for supplying a control signal to the gate driver IC unit 2 and the source driver IC unit 3,
5 is a power supply unit. 6 is a gate bus which is a scanning line, 7 is a drain bus which is a signal line arranged so as to cross the gate bus 6, 8 is arranged at an intersection of the gate bus 6 and the drain bus 7, and the gate electrode is a gate bus 6. A switching element having a source electrode connected to the drain bus 7; a liquid crystal 9 connected to the drain electrode of the switching element 8; a capacitor element 10 connected to the drain electrode of the switching element 8; , The liquid crystal 9 and the capacitor element 10 are arranged in a matrix to form the liquid crystal panel 1 as a display unit.

FIG. 4 is an overall view showing a conventional one-sided liquid crystal display device. In the figure, 1 to 3 are the same as those in FIG. In this figure, the control circuit 4 and the power supply unit 5 are omitted. In the active matrix driving method, various driving methods are applied to improve functions and performance of the liquid crystal display device. One of the dot inversion methods is a liquid crystal driving method in which the polarity of the signal voltage applied to the drain electrode is inverted every dot period with respect to the center of the signal voltage.

FIG. 5 is a waveform diagram of a signal voltage in a dot inversion method in an arbitrary vertical direction (i-th line) of the liquid crystal display device. In the figure, the horizontal axis represents an arbitrary horizontal direction of the liquid crystal display device (the n-th column, the (n + 1) -th column, the (n + 2) -th column, and the (n +)-th column.
(3 columns, n + 4 columns), and the vertical axis represents voltage. 11 is the signal voltage, 12 is the signal voltage center, 1
3 is a common voltage.

FIG. 6 is an overall view showing a conventional double-sided liquid crystal display device, including a dot inversion method and other inversion methods. In the figure, 1 and 2 are the same as those in FIG. 4, and 3a and 3b are source driver IC sections for outputting data signals to the liquid crystal panel 1, which are divided into two and constitute two drive blocks. ing.

In the single-sided liquid crystal display device as shown in FIG. 4, the input clock frequency of the source driver IC unit 3 is equal to the clock frequency for one dot, but as shown in FIG. In the display device, since the output of one source driver IC is half the output of the former, the clock frequency of the input source driver IC is also two-dot clock frequency, which is half the clock frequency of one dot. Becomes The clock frequency is related to the EMI generated from the liquid crystal display device. The lower the frequency, the lower the EMI, and the lower the frequency, the lower the EMI.
In addition to the fact that mounting on both sides is more effective than mounting on one side, the driver IC becomes larger as the clock frequency increases with larger screens and higher definition.
Due to the fact that data sampling errors easily occur and the cost of a driver IC with a high clock frequency is high, mounting on both sides with a lower clock frequency is much more effective than mounting on one side. The rate of applying double-sided mounting to liquid crystal display devices is increasing.

FIG. 7 is a diagram showing a connection arrangement between a source driver IC unit and a liquid crystal panel in a conventional double-sided mounting. In the drawing, 1, 3a and 3b are the same as those in FIG. Data signal output terminals of the source driver IC section 3a and the source driver IC section 3b in the conventional double-sided liquid crystal display device (including the dot inversion method and other inversion methods) shown in FIG. The connection relationship of the terminals is such that adjacent output terminals of the source driver IC section are arranged at one dot intervals as shown in FIG. That is, the data signal input terminals (X ₁ , X ₂ , X ₃ ... X _2N ) of the liquid crystal panel 1 connected in the horizontal direction of the liquid crystal display device are connected to the data signal output terminals of one of the source driver IC units 3a. (D _t1 , D _t2 , D _t3 ... D _tN ) and the data signal output terminals (D _b1 , D _b1 ) of the other source driver IC section 3b.
_b2, D _b3 ··· D _bN) and when, X ₁ and D _t1, X ₂ and D _b1, X ₃ and D _t2, X ₄ and D _b2, X ₅ and D _t3, X6 and D _b3
... are respectively connected.

FIG. 8 is a diagram showing a signal voltage waveform in a conventional dot inversion method in double-sided mounting. In the case of a source driver IC used in a driving method other than the dot inversion method (for example, a line inversion method), the relationship of the change in polarity remains the same even in a double-sided mounting structure. In the conventional double-sided mounting configuration, the polarity is inverted every two dots as shown in FIG. 8, so that the polarity inversion for each dot cannot be realized by the conventional dot inversion method. Polarity inversion cannot be performed between matching pixels.

[0010]

In the liquid crystal display device of the active matrix driving system, the voltage applied to the liquid crystal partially decreases during one screen period because the storage capacity of the TFT is small. At the same time, even if the voltages applied to the liquid crystal have the same polarity due to the parasitic capacitance existing between the common electrode portion, the drain electrode portion, and the source electrode portion, there is a possibility that the voltages are different for each pixel. When adjacent pixels have the same polarity, the voltage applied to the liquid crystal at each pixel must also be kept constant. However, as described above, since it is difficult to keep the voltage constant, the voltage applied to the liquid crystal fluctuates, causing a problem that the contrast difference changes. These problems are prominent due to the miniaturization of TFTs and the reduction in signal voltage as the screen size of the liquid crystal display device increases. As described above, when a conventional liquid crystal display device mounted on both sides is configured by using the source driver IC for the dot inversion method, since the polarity is inverted every two dots, the adjacent pixels have a completely inverted polarity. Because of this, the magnitude of the voltage applied to the liquid crystal changes between adjacent pixels, which causes a change in the contrast of display (decrease in contrast), and in addition to this, flickering of the screen, etc. This causes a problem that the flicker phenomenon becomes noticeable. There is also a drawback that a display pattern for evaluation of a liquid crystal display device employing a conventional dot inversion method cannot be used.

The present invention has been made to solve the above-described problems, and has as its first object to provide a liquid crystal display device capable of displaying a high-quality image. It is a second object to obtain such a driving method of a liquid crystal display device.

[0012]

In a liquid crystal display device according to the present invention, a second electrode inverting a predetermined voltage at a predetermined period is applied to a second electrode of a switching element arranged in a matrix on a display unit. Two drive blocks each having a second drive circuit for supplying a signal are provided, and the two drive blocks are alternately connected for every two signal lines, and an inverted second signal is supplied to an adjacent signal line. Supply. Further, two drive blocks each having a second drive circuit for supplying a second signal that inverts a predetermined voltage as a center to a second electrode of a switching element arranged in a matrix on the display unit at predetermined intervals. The two drive blocks are alternately connected for every even number of signal lines, and supply an inverted second signal to an adjacent signal line.

Further, the two drive blocks are disposed at both ends of the signal line via the display unit. Further, the two drive blocks are arranged at one end of the signal line. Further, the two drive blocks are arranged to overlap.

In the method of driving a liquid crystal display device according to the present invention, two driving blocks for driving a display section having switching elements arranged in a matrix at intersections of a plurality of scanning lines and a plurality of signal lines. In this configuration, a drive signal that is alternately inverted around a predetermined voltage at predetermined intervals is supplied to every two signal lines, and an inverted drive signal is supplied to adjacent signal lines. In addition, the two drive blocks that drive the display unit having the switching elements arranged in a matrix at the intersections of the plurality of scanning lines and the plurality of signal lines are alternately arranged at regular intervals every even number of signal lines. A drive signal that is inverted around a predetermined voltage is supplied, and an inverted drive signal is supplied to an adjacent signal line.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing a connection arrangement between a source driver IC unit and a liquid crystal panel according to a first embodiment of the present invention. In the figure, 1, 3
_{a, 3b, X 1 ~X 6} ,, D t1 ~D t4, D b1, D b2 Figure 7
And 2 are the same as those in FIG. 3, and the description thereof will be omitted. FIG. 1 is a layout diagram of a source driver IC for a liquid crystal display device mounted on both sides having two source driver IC units for the dot inversion method, specifically, in a liquid crystal panel 1 connected in the horizontal direction of the liquid crystal display device. data signal input terminals _{(X 1, X 2, X} 3
_{.. For} one source driver IC unit 3
a at the data signal output terminals (D _t1 , D _t2 , D _t3.
D _tN ) and data signal output terminals (D _b1 , D _b2 , D _b3 ... D _bN ) in the other source driver IC section 3b, X ₁ and D _t1 , X ₂ and D _t2 , X ₃ And D _b1 , X ₄ and D
_b2, X ₅ and D _t3, X ₆ and D _t4, X ₇ and D _b3, X ₈ and D _b4 ··
・ Connect as shown.

According to the configuration of the first embodiment, the liquid crystal display device can realize the conventional dot inversion method having the signal voltage waveform of FIG. 5, inverting the polarity of the voltage applied to the liquid crystal in the frame cycle, and Since the polarity of the voltage applied to the liquid crystal between adjacent pixels can be temporally and spatially inverted, a high quality image can be obtained by improving the contrast and reducing the flicker phenomenon. Embodiment 1
Can realize the conventional dot inversion method having the signal voltage waveform of FIG. 5, and can use the evaluation display pattern of the liquid crystal display device employing the conventional dot inversion method. Further, in the setting made in Fig. 1, X ₁ and D _b1, X ₂ and D _b2, X ₃ and D _t1, X ₄ and D _t2, X ₅ and D _b3,
X ₆ and D _b4, X ₇ and D _t3, X ₈ and the same effect even when connected as the D _t4 · · · are obtained.

Embodiment 2 FIG. FIG. 2 is a diagram showing a single-sided mounted liquid crystal display device according to Embodiment 2 of the present invention.
2 (a) is an overall view, and FIG. 2 (b) is II-II in FIG. 2 (a).
It is sectional drawing. This is a single-sided liquid crystal display device having two dot inversion type source driver IC units 3c and 3d, and data signal output terminals of one source driver IC unit 3c are _Dt1 , _Dt2 , _Dt3. when the data signal output terminal is set to _{D b1, D b2, D b3} ··· D bN in _tN and the other of the source driver IC unit 3d, performs the same connection method as the first embodiment. In this case, the source driver IC unit 3a corresponds to the source driver IC unit 3c, and the source driver IC unit 3b corresponds to the source driver IC unit 3d.

The liquid crystal display device according to the second embodiment has the structure shown in FIG.
A conventional dot inversion method having a signal voltage waveform of the type described above can be realized. In addition to inverting the polarity of the voltage applied to the liquid crystal in a frame cycle, the polarity of the voltage applied to the liquid crystal between adjacent pixels can be temporally and spatially. , It is possible to obtain a high quality image by improving the contrast and reducing the flicker phenomenon. Further, the liquid crystal display device according to the second embodiment can realize the conventional dot inversion method having the signal voltage waveform of FIG. 5, and can use the evaluation display pattern of the liquid crystal display device employing the conventional dot inversion method. Become.

In the second embodiment, two source driver IC sections 3c, 3c,
By providing 3d, EMI can be reduced because the frequency of the clock is reduced by half. In the first and second embodiments, the two source driver IC sections are alternately connected to the data signal input terminal of the liquid crystal panel at two-dot intervals. However, the same effect can be obtained even with an arbitrary even-dot interval. can get.

[0020]

Since the present invention is configured as described above, it has the following effects. The display unit includes two drive blocks each having a second drive circuit that supplies a second signal that is inverted around a predetermined voltage to a second electrode of a switching element arranged in a matrix at predetermined intervals, and The two drive blocks are alternately connected to every two signal lines and supply an inverted second signal to adjacent signal lines, so that a high quality image can be obtained by improving the contrast and reducing the flicker phenomenon. And the noise can be reduced by halving the clock frequency. Further, two drive blocks each having a second drive circuit for supplying a second signal that inverts a predetermined voltage as a center to a second electrode of a switching element arranged in a matrix on the display unit at predetermined intervals. The two drive blocks are alternately connected to even signal lines, and supply an inverted second signal to adjacent signal lines, so that high-quality images can be obtained by improving contrast and reducing flicker phenomenon. Can be obtained, and the electromagnetic noise can be reduced by halving the clock frequency.

Further, since the two drive blocks are disposed at both ends of the signal line via the display unit, the two drive blocks can be mounted on both sides as in the conventional case. Further, since the two drive blocks are arranged at one end of the signal line, they can be mounted on one side. Further, since the two drive blocks are arranged so as to overlap with each other, the area required for the arrangement may be small.

The two drive blocks for driving the display section having the switching elements arranged in a matrix at the intersections of the plurality of scanning lines and the plurality of signal lines are alternately provided with a predetermined period every two signal lines. A drive signal that is inverted around a predetermined voltage is supplied every time, and an inverted drive signal is supplied to an adjacent signal line, so that a high-quality image can be obtained by improving the contrast and reducing the flicker phenomenon. In addition, the electromagnetic noise can be reduced by halving the clock frequency. In addition, the two drive blocks that drive the display unit having the switching elements arranged in a matrix at the intersections of the plurality of scanning lines and the plurality of signal lines are alternately arranged at regular intervals every even number of signal lines. A drive signal that is inverted around a predetermined voltage is supplied, and an inverted drive signal is supplied to an adjacent signal line, so that a high-quality image can be obtained by improving the contrast and reducing the flicker phenomenon, and the clock can be obtained. Electromagnetic noise can be reduced by halving the frequency.

[Brief description of the drawings]

FIG. 1 is a diagram showing a connection arrangement between a source driver IC unit and a liquid crystal panel of a liquid crystal display device mounted on both sides according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a single-sided liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a liquid crystal display device using an active matrix driving method.

FIG. 4 is an overall view showing a conventional one-sided mounted liquid crystal display device.

FIG. 5 is a diagram showing a signal voltage waveform in a dot inversion method.

FIG. 6 is an overall view showing a conventional liquid crystal display device mounted on both sides.

FIG. 7 is a diagram showing a connection arrangement between a conventional double-sided source driver IC unit and a liquid crystal panel.

FIG. 8 is a diagram showing a signal voltage waveform in a conventional dot inversion method in both-side mounting.

[Explanation of symbols]

Reference Signs List 1 liquid crystal panel, 2 gate driver IC section, 3 source driver IC section, 4 control circuit, 6 gate bus, 7 drain bus, 8 switching element, 9
liquid crystal.

Claims (7)

[Claims] 1. A switching element arranged in a matrix at intersections of a plurality of scanning lines and a plurality of signal lines, wherein a first electrode has a switching element connected to the scanning line and a second electrode connected to the signal line, respectively. A display unit, a first drive circuit that supplies a first signal to a first electrode of the switching element, a second signal that inverts a second electrode of the switching element around a predetermined voltage every predetermined cycle. It comprises two drive blocks each having a second drive circuit for supplying, and the two drive blocks are connected alternately every two of the signal lines, and an inverted second signal is supplied to an adjacent signal line. A liquid crystal display device characterized by supplying. 2. A switching element which is arranged in a matrix at intersections of a plurality of scanning lines and a plurality of signal lines, wherein a first electrode is connected to the scanning line and a second electrode is connected to the signal line. A display unit, a first drive circuit that supplies a first signal to a first electrode of the switching element, a second signal that inverts a second electrode of the switching element around a predetermined voltage every predetermined cycle. It comprises two drive blocks each having a second drive circuit for supplying, and the two drive blocks are connected alternately for every even number of the signal lines, and an inverted second signal is supplied to an adjacent signal line. A liquid crystal display device characterized by supplying. 3. The liquid crystal display device according to claim 1, wherein the two drive blocks are disposed at both ends of the signal line via the display unit. 4. The liquid crystal display device according to claim 1, wherein the two drive blocks are arranged at one end of the signal line. 5. The liquid crystal display device according to claim 4, wherein the two drive blocks are arranged so as to overlap with each other. 6. A liquid crystal display for driving a display section having switching elements arranged in a matrix at intersections of a plurality of scanning lines and a plurality of signal lines by supplying driving signals to the signal lines by two driving blocks. In the driving method of the device,
The drive block alternately supplies a drive signal that inverts a predetermined voltage at a predetermined cycle to the two signal lines alternately every two lines, and supplies an inverted drive signal to an adjacent signal line. Characteristic driving method of a liquid crystal display device. 7. A liquid crystal display in which a display section having switching elements arranged in a matrix at intersections of a plurality of scanning lines and a plurality of signal lines is driven by supplying driving signals to the signal lines by two driving blocks. In the driving method of the device,
The drive block alternately supplies an even number of signal lines with a drive signal inverted around a predetermined voltage every predetermined period and supplies an inverted drive signal to an adjacent signal line. Driving method for a liquid crystal display device.