JP2003216124A - Method for driving picture display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the driving method of a picture display device for reducing the occurrence of flicker by averaging the change of the light intensity of a liquid crystal display over the entire screen of the display in one-dot (or two-dot) checkered pattern display. <P>SOLUTION: In a dot inversion driving method having two dots or more in which the voltage polarity to be applied to the liquid crystal layer of a unit liquid crystal cell is inverted by making two dots or more adjacent with each other in up and down directions a unit, polarities of all dots adjacent to the right and the left of these two dots are not inverted for every one dot. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of an image display device represented by an active matrix type liquid crystal display device using a thin film transistor (TFT) as a switching element.

[0002]

2. Description of the Related Art A first example of conventional technology will be described.

In the conventional active matrix type liquid crystal display device, as one dot inversion drive, the liquid crystal is applied to each adjacent dot on each of the X direction scanning line (gate scanning line) and the Y direction signal line (source signal line). There is a method of reversing the polarity of the voltage applied to the layers. The voltage waveform of the source signal line at this time is shown in FIG.

In addition, as the 2-dot inversion drive, the polarity of the voltage applied to the liquid crystal layer is inverted for each adjacent dot (adjacent to the left and right) on the gate scanning line, but is adjacent on the source signal line (adjacent to the vertical). There is a method in which two dots are regarded as one unit and the voltage polarity is inverted every two dots. The voltage waveform of the source signal line at this time is shown in FIG.

FIG. 5 is a schematic diagram showing the structure of a liquid crystal display panel of a liquid crystal display device. In the liquid crystal display panel, a plurality of gate scanning lines 1 and a source signal which intersects the gate scanning lines 1 in a matrix form. A thin film transistor (TFT) and a pixel electrode electrically connected to the gate scanning line 1 and the source signal line 2 are formed at an intersection of the line 2 and the gate scanning line 1 and the source signal line 2, and the TFT and the pixel electrode are formed. The unit liquid crystal cell 3 is formed by a single color of red, green and blue.

Next, the details of the 1-dot inversion drive will be described with reference to FIGS.

As shown in FIG. 4A, the source signal waveform applied to each unit liquid crystal cell 3 is a source signal voltage + Vs (5A) and -V having a voltage waveform in the opposite direction to the center voltage.
s (6A) is a drive waveform whose timing is selected so that it is alternately applied for each field (1h) (for each vertically adjacent unit liquid crystal cell 3), and on the same gate scanning line 1 Even between unit liquid crystal cells adjacent to each other (adjacent to the left and right), each source signal voltage has a controlled drive waveform so that + Vs and −Vs are alternately applied.

As a result, the voltage applied to the unit liquid crystal cell 3 has its polarity inverted for each unit liquid crystal cell adjacent vertically and horizontally, and in FIG. 5, 3A denotes a unit liquid crystal cell to which a positive polarity is applied. 3B shows a unit liquid crystal cell to which a negative polarity is applied.

Next, FIG. 7 is a diagram showing a state of 2-dot inversion drive. As shown in the figure, the 2-dot inversion drive is
For every two dots (two dots as one unit) with respect to the unit liquid crystal cells 3 vertically adjacent to each other, the polarity of the voltage applied to the liquid crystal layer is inverted, and the unit liquid crystals adjacent to the left and right of the two-dot unit liquid crystal cell are inverted. The cell is a driving method in which the polarity is inverted every dot. Alternatively, it is a driving method in which the polarities of the unit liquid crystal cells adjacent to the left and right are inverted every two dots, and the polarities of the unit liquid crystal cells vertically adjacent to the unit liquid crystal cells of the two dots are inverted every one dot. Also in FIG. 5, 3A indicates a unit liquid crystal cell to which a positive polarity is applied, and 3B indicates a unit liquid crystal cell to which a negative polarity is applied.

In both the 1-dot inversion drive and the 2-dot inversion drive, the transmittance is controlled in proportion to the amount of voltage applied to the unit liquid crystal cell 3, regardless of the polarity of the source signal waveform. We recognize the transmitted light (light intensity) according to the transmittance in the display image state.

The driving method of the liquid crystal display device is such that the unit liquid crystal cell 3A to which the source signal voltage + Vs in the positive direction is applied and the source signal voltage -Vs in the negative direction are applied to the center voltage of the source signal waveform. The unit liquid crystal cell 3B is driven by alternating current for inverting the polarity. In addition, the source signal voltage polarity is inverted every arbitrary number of fields (generally every frame). That is, the voltage of the unit liquid crystal cell, which had a positive voltage polarity in one field, is
In the next field, the voltage polarity is negative. As a result, the application of the DC voltage component to the liquid crystal itself is reduced as much as possible.

[0012]

However, in general, due to capacitive coupling between the gate scanning line 1 and the pixel electrode (not shown), the voltage component applied to the unit liquid crystal cell 3 is in the negative direction. The voltage drops, and the positive and negative voltage component amounts of the unit liquid crystal cell 3 are in an unbalanced state in which the negative applied voltage component amount is large. Therefore, since the light intensity of each unit liquid crystal cell changes as described above, deterioration of display quality such as flicker (flicker) is likely to occur.

In a solid display state in which the entire liquid crystal display screen has the same display color such as white, red, and halftone, the unbalanced difference in voltage polarity of each unit liquid crystal cell varies spatially and temporally over the entire screen. Canceled by For example, FIG. 5 and FIG.
When the image display state shown in is viewed on the entire screen, the unit liquid crystal cells having the positive and negative voltage polarities applied to the respective liquid crystal layers cancel out the light intensity changes and are averaged. It That is, the unit liquid crystal cells 3A and 3B shown in FIG. 5 or the unit liquid crystal cells 3A and 3B shown in FIG. 7 change or fluctuate in the opposite directions (if the light intensity at 3A is low, the light intensity at 3B is high). 3A and 3
It is averaged over the entire screen where B is mixed).

Therefore, in the solid display state, flicker is not particularly noticeable and poses no problem.

However, when displaying a specific image pattern, flicker may become noticeable.

In a personal computer (PC) or the like, a display pattern used for displaying an OS or application software is a conventional one dot (or two dots).
No problem such as flicker occurred in the inversion driving method. However, in recent years, on a specific screen of application software such as Windows (registered trademark) 95, as shown in FIG. 6, a 1-dot checkered pattern for each single color of red, green, and blue (dots of a specific color are in the halftone display 8, Other dots are displayed in a checkered pattern as a state of black display 9).

At this time, in the above-mentioned dot inversion drive, the unit liquid crystal cells having the positive and negative voltage polarities applied to the liquid crystal layer do not cancel out the change in light intensity with each other (the black display portion is Since the light is not transmitted, the light intensity disappears, and in the unit liquid crystal cell for halftone display, the entire screen has the same polarity in one field, and the uneven light intensity is displayed.) It was a problem in the quality of.

The present invention has been made in view of such a problem, and in a 1-dot (or 2-dot) checkered pattern display, a change in light intensity of a liquid crystal display device is averaged over the entire screen, and a flicker is obtained. It is an object of the present invention to provide a method for driving an image display device that can reduce the occurrence of the phenomenon.

[0019]

In order to achieve the above object, a first invention (corresponding to claim 1) includes a substrate, a plurality of gate wirings provided on the substrate, and An image display panel having a plurality of source wirings intersecting the plurality of gate wirings provided in a matrix and a plurality of pixel electrodes connected to the gate wirings and the source wirings, and scanning the plurality of gate wirings A driving method of an image display device, comprising: a scanning signal drive circuit for outputting a signal; and an image signal drive circuit for outputting an image signal to the plurality of source wirings, wherein a voltage polarity of the image signal is set in a row direction or a column direction. This is a driving method of an image display device in which N (N is an integer of 2 or more) pixel electrodes adjacent in the direction have the same polarity.

The second invention (corresponding to claim 2)
Is the number of the pixel electrodes to which the positive polarity image signal is applied and the number of the pixel electrodes to which the negative polarity image signal is applied, in the image panel displaying one field. The same number is the driving method of the image display device according to the first aspect of the present invention.

The third invention (corresponding to claim 3)
Reverses the voltage polarity of the image signal for every N (N is an integer of 2 or more) pixel electrodes adjacent to each other in the row direction or the column direction, and the N pixel electrodes are arranged in the column direction or the row direction. Is the driving method of the image display device according to the first aspect of the present invention, in which the voltage polarity of the image signal applied to at least one pixel electrode adjacent to the pixel electrode has the same polarity as the N pixel electrodes.

A fourth invention (corresponding to claim 4)
Is the driving method of the image display device according to the first aspect of the present invention, wherein the color of the image signal displayed by the N pixel electrodes is one of the three primary colors of red, green and blue.

The fifth invention (corresponding to claim 5)
Of the plurality of pixel electrodes of the first or second aspect of the present invention that performs black display by M pixel electrodes that are arranged every M (M is an integer of 1 or more) in the row direction and the column direction. It is a method of driving an image display device.

The sixth invention (corresponding to claim 6)
Is M (M is an integer of 1 or more) in the row direction and the column direction among the plurality of pixel electrodes in the image display panel.
The voltage polarity of the image signal is the same for N (N is an integer of 2 or more) pixel electrodes adjacent in the row direction or the column direction only when the M pixel electrodes arranged every other pixel display black. It is a method of driving the image display device according to the first aspect of the present invention so as to obtain the above polarity.

The present invention as described above, as an example thereof,
A method of driving an active matrix type liquid crystal display device includes a plurality of signal wirings and scanning wirings arranged in a matrix,
In an active matrix type liquid crystal display device having at least one switching element corresponding to each intersection and forming a unit liquid crystal cell, liquid crystal cells of vertically adjacent N dot units (N is an integer of 2 or more) An N dot inversion driving method in which the polarity of voltage applied to a layer is inverted, wherein at least one dot adjacent to the left and right of the N dot has the same voltage polarity.

In a liquid crystal display device in which a TFT section is formed for each unit liquid crystal cell, the voltage applied to the liquid crystal layer of the unit liquid crystal cell is two dots or more in which the polarity is inverted, with two dots or more vertically adjacent as one unit. In the dot inversion driving method, the dots adjacent to the right and left of the two dots are not all the polarity inverted for every dot.

In a liquid crystal display device using such a driving method, even if a 1-dot checkered pattern or a multi-dot checkered pattern for each single color of red, green and blue is displayed, it is applied to a unit liquid crystal cell of a halftone display section. The voltages applied are not all of the same polarity. Therefore, changes in spatial light intensity when viewed on the entire screen cancel each other out and are averaged, so that it is possible to provide a high-quality liquid crystal display device that can reduce flicker generation, and no problem occurs in the market. .

In the driving method of the active matrix type liquid crystal display device as an example of the present invention, the above-mentioned vertically adjoining two dots or more is defined as one unit, and the laterally adjoining two dots or more is defined as one unit. The dot inversion driving method of 2 dots or more in which the voltage applied to the liquid crystal layer of the unit liquid crystal cell is inverted in polarity may be used. In that case, the dots adjacent to the upper and lower sides of the two dots are not all reversed in polarity for each dot. Even in this case,
Similarly to the above, even if a 1-dot checkered pattern or a multi-dot checkered pattern is displayed for each single color of red, green and blue,
Since the voltages applied to the liquid crystal cells of the halftone display dots are not all of the same polarity, flicker can be reduced.

In the method of driving an active matrix type liquid crystal display device as an example of the present invention, when the polarity is inverted with two or more vertically adjacent dots as one unit, the upper and lower colors are red, green and blue. It is preferable that they have the same color. Further, when the polarity is inverted with two dots or more adjacent to the left and right as one unit, the colors on the left and right are
It is preferable that the same color is used among red, green and blue.

Further, in the driving method of the active matrix type liquid crystal display device as an example of the present invention, if it is the upper and lower 2-dot inversion driving method, only one dot of the 2-dot unit liquid crystal cell is adjacent to the left and right. The dots are not reversed in polarity (have the same polarity). Also, the upper and lower 3
In the dot inversion driving method, only one dot or two dots in the 3-dot unit liquid crystal cell are not polarity-inverted in the dots adjacent to the left and right.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION A method of driving an active matrix type liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

FIG. 1 is an explanatory diagram showing an example of a driving method of an active matrix type liquid crystal display device of the present invention. As shown in the drawing, the unit liquid crystal cells 3A and 3B vertically adjacent to each other for each single color of red, green and blue have the polarity of the voltage applied to the liquid crystal layer inverted every two dots. Here, the unit liquid crystal cells 3A and 3B that are collected in units of two dots are referred to as inversion unit liquid crystal cells 10A and 10B, respectively.

On the other hand, the arrangement of the inversion unit liquid crystal cells 10A 'and 10B' adjacent to the left and right of the inversion unit liquid crystal cells 10A and 10B is shifted by one dot from the inversion unit liquid crystal cells 10A and 10B. That is, the inversion unit liquid crystal cell 10
A unit liquid crystal cell adjacent to A and 10B has one of two dots
The voltage polarity of the dots is inverted, but the voltage polarity of the remaining one dot is not inverted and has the same polarity.

In the above-mentioned driving method that produces the voltage polarity state,
Even in a specific screen such as a dot checkered pattern for each single color of red, green, and blue such as Windows (registered trademark) 95 as shown in FIG. 2, the halftone display unit 8 has a unit of positive polarity in the entire screen in one field. Since the display is performed by both the liquid crystal cell 3A and the unit liquid crystal cell 3B having the negative polarity, the change in the light intensity of the halftone display portion is averaged and the flicker can be made inconspicuous.

Similarly, in a specific screen such as a 2-dot checkered pattern for each single color of red, green and blue as shown in FIG. 3, the applied voltage polarity of the unit liquid crystal cell displaying the halftone display portion 8 is 1 field. Flicker can be made almost inconspicuous because there are both positive and negative polarities on the entire screen at.

The above-mentioned unit liquid crystal cells that are vertically adjacent to each other are collected every two dots and the reversal unit liquid crystal cells 10A and 10B are combined.
In the above description, the polarity is inverted. However, two dots adjacent to each other on the left and right may be used as an inversion unit liquid crystal cell, and a driving method in which the voltage applied to the liquid crystal layer of the unit liquid crystal cell is inverted. In this case, the inversion unit liquid crystal cells vertically adjacent to each other are arranged such that the inversion unit liquid crystal cells are shifted from each other by one dot. That is, in each of the two-dot unit liquid crystal cells that form the inversion unit liquid crystal cell, the voltage polarities of the one-dot unit liquid crystal cells that are vertically adjacent to each other are reversed, but the remaining one-dot unit liquid crystal cell Make sure that the polarities do not reverse and that they have the same polarity.

In this case also, as described above, even if the 1-dot checkered pattern or the 2-dot checkered pattern for each of the red, green, and blue colors is displayed, the applied voltage polarities of the halftone display portions are all the same. Because it doesn't, flicker can be made almost unnoticeable.

In the above embodiment,
The inversion unit liquid crystal cells which are vertically (or left and right) adjacent to each other and whose polarities are inverted are composed of unit liquid crystal cells of 2 dots, but are not limited to this, and for example, 3 dots, 4 dots, ...
.., N dots (N is an integer of 2 or more) may be composed of a plurality of unit liquid crystal cells. In this case, the arrangement of the inversion liquid crystal cells vertically or horizontally adjacent to the inversion unit liquid crystal cell is shifted by at least one dot, and at most N-1 dots of the unit liquid crystal cell. That is, when the unit liquid crystal cell forming the reversal unit liquid crystal cell has 3 dots, only one dot or two dots of the unit liquid crystal cells vertically or horizontally adjacent to each other are not reversed in polarity. When the number of dots is N, among the unit liquid crystal cells that are vertically or horizontally adjacent to each other,
1 dot, or 2 dots, ..., or N
Only -1 dot is driven so that the polarity is not inverted. As a result, even when a 1-dot checkered pattern or a 2-dot checkered pattern is displayed, the applied voltage polarity of the display unit includes both plus and minus, and flicker can be made inconspicuous.

Further, the driving method according to the present embodiment does not need to be performed in units of inverted liquid crystal cells. As a first case, in the display panel, the voltage applied to the liquid crystal layer is inverted for every N (N is an integer of 2 or more) unit liquid crystal cells which are vertically or horizontally adjacent to each other, and the N unit liquid crystals are At least 1 adjacent to the cell in the column or row direction
Even if the polarities of the voltages applied to the unit liquid crystal cells are set to be the same as those of the N unit liquid crystal cells, the same effect as that of the above configuration can be obtained.

Further, in the second case, the N unit liquid crystal cells (N is an integer of 2 or more) that are vertically or horizontally adjacent to each other are driven so that the voltages applied to the liquid crystal layers have the same polarity. Even if it does, the same effect as the above-mentioned composition can be obtained.

In the first and second cases, the number of unit liquid crystal cells 3A to which a positive polarity image signal is applied during the display for one field, and
If the number of unit liquid crystal cells 3B to which a negative polarity image signal is applied is the same, flicker can be most efficiently reduced. However, when a sufficient effect can be obtained, the number of unit liquid crystal cells 3A to which a display positive polarity image signal for one field is applied and the number of unit liquid crystal cells 3B to which a negative polarity image signal is applied are different. It may be different.

Further, in the above description, the checkered pattern is such that one dot unit liquid crystal cell for black display is arranged every other dot, or two for black display.
The description has been made assuming that the unit liquid crystal cells for dots are arranged every two dots, but the checkered pattern is not limited to this, and M dots for black display (M is 1
The unit liquid crystal cells of the above integer) may be arranged every M dots.

Further, in the above description, the checkered pattern is displayed by the black display and the display of one of the primary colors of red, green and blue, but the black display and another color, for example, white. It may be realized by a display. A dark color close to black display may be used instead of black display.

Further, the driving method of each of the above embodiments is
It may be executed only when the checkered pattern is displayed, and may be switched to a driving method similar to the conventional one when another display pattern is to be displayed.

In each of the above embodiments, the pixel electrode corresponding to the unit liquid crystal cell corresponds to the pixel electrode of the present invention, and the liquid crystal display panel corresponds to the image display panel of the present invention. The image display panel of the present invention is not limited to liquid crystal, and may be a plasma display or the like.

As described above, according to the driving method of the active matrix type liquid crystal display device of the embodiment of the present invention, the voltage applied to the liquid crystal layer of the unit liquid crystal cell is defined by two dots or more vertically adjacent to each other as one unit. In the dot inversion driving method of two or more dots in which the polarity is inverted, the dots adjacent to the right and left of the two dots are not all inverted for every one dot. The liquid crystal display device using the driving method obtained in this way is
Even if a dot checkered pattern or a multiple dot checkered pattern is displayed, the voltages applied to the unit liquid crystal cells of the halftone display section are not all of the same polarity. for that reason,
Spatial light intensity changes when viewed on the entire screen cancel each other out and are averaged, so that the occurrence of flicker can be reduced.
Therefore, it is possible to provide a high-quality liquid crystal display device with no noticeable flicker even in the market, which is extremely effective in practice.

[0047]

As described above, according to the present invention, 1
Even if a checkered pattern of dots or a plurality of dots is displayed, the occurrence of flicker can be reduced, a high-quality liquid crystal display device can be provided on the market, and it is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of contents showing an embodiment of a driving method of the present invention.

FIG. 2 is a diagram showing a state in which a 1-dot checkered pattern is displayed in the basic conceptual diagram of the present invention in FIG.

FIG. 3 is a diagram showing a state in which a 2-dot checkered pattern is displayed in the basic conceptual diagram of the present invention in FIG.

FIG. 4A is a diagram showing a source signal waveform of a conventional one-dot inversion driving method. (B) It is a figure which shows the source signal waveform of the conventional 2-dot inversion drive method.

FIG. 5 is a diagram showing a basic concept of contents showing a conventional one-dot inversion driving method.

FIG. 6 is a diagram showing a state in which a 1-dot checkered pattern is displayed in the basic conceptual diagram of the conventional driving method in FIG.

FIG. 7 is a basic conceptual diagram showing the contents of a conventional 2-dot inversion driving method.

FIG. 8 is a diagram showing a state in which a 2-dot checkered pattern is displayed in the basic conceptual diagram of the conventional driving method in FIG. 7.

[Explanation of symbols]

1: gate scanning line 2: source signal line 3: unit liquid crystal cell 3A: unit liquid crystal cell with positive polarity voltage applied to liquid crystal layer 3B: unit liquid crystal cell with negative polarity voltage applied to liquid crystal layer 4A: 1 Center voltage of source signal waveform of dot inversion driving 4B: Center voltage of source signal waveform of 2 dot inversion driving 5A: Positive polarity of source signal waveform of 2 dot inversion driving Voltage 5B: Positive polarity of source signal waveform of 2 dot inversion driving Voltage 6A: 1-dot inversion drive source signal waveform minus polarity voltage 6B: 2-dot inversion drive source signal waveform negative polarity voltage 7A: 1-dot inversion drive source signal waveform 1-field period 7B: 2-dot inversion drive 1 field period of source signal waveform 8: unit liquid crystal cell 9 showing halftone display 9: unit liquid crystal cell 10A showing black display: liquid crystal Inversion unit liquid crystal cell 10B in which a positive polarity voltage is applied to the layer: Inversion unit liquid crystal cell in which a positive polarity voltage is applied to the liquid crystal layer

Claims (6)

[Claims] 1. A substrate, a plurality of gate wirings provided on the substrate, a plurality of source wirings intersecting the plurality of gate wirings provided on the substrate in a matrix, and the gate wirings and the source wirings. An image display panel having a plurality of pixel electrodes connected to, a scanning signal drive circuit that outputs a scanning signal to the plurality of gate lines, and an image signal drive circuit that outputs an image signal to the plurality of source lines. An image display device driving method comprising: an image in which voltage polarities of the image signals are set to be the same in N (N is an integer of 2 or more) pixel electrodes adjacent in a row direction or a column direction. Driving method of display device. 2. The number of the pixel electrodes to which a positive polarity image signal is applied and the number of the pixel electrodes to which a negative polarity image signal is applied in the image panel displaying one field. The method for driving an image display device according to claim 1, wherein the number is the same number. 3. The voltage polarity of the image signal is inverted for every N (N is an integer of 2 or more) pixel electrodes that are adjacent in the row direction or the column direction, and the N pixel electrodes are arranged in the column direction or The method for driving an image display device according to claim 1, wherein the voltage polarity of the image signal applied to at least one pixel electrode adjacent in the row direction is set to be the same as that of the N pixel electrodes. . 4. The method of driving an image display device according to claim 1, wherein the color of the image signal displayed by the N pixel electrodes is one of the three primary colors of red, green and blue. 5. The black display is performed by M pixel electrodes arranged in every M (M is an integer of 1 or more) in the row direction and the column direction among the plurality of pixel electrodes to display black. A method for driving the image display device according to claim 1. 6. In the image display panel, among the plurality of pixel electrodes, M pixel electrodes arranged at every M (M is an integer of 1 or more) rows and columns perform black display. The image display device according to claim 1, wherein the voltage polarities of the image signals are set to be the same in N (N is an integer of 2 or more) pixel electrodes adjacent in the row direction or the column direction only in the case. Driving method.