JP3454744B2 - Active matrix type liquid crystal display and driving method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device represented by a TFT (thin film transistor) type liquid crystal display device and a driving method thereof, and particularly, low power consumption is required. The present invention relates to an active matrix type liquid crystal display used as a display device of a portable device and a driving method thereof.

[0002]

2. Description of the Related Art FIG. 1 is a conceptual diagram of a liquid crystal display. The liquid crystal display includes an active matrix substrate, a counter substrate and a liquid crystal layer sandwiched therebetween. As shown in FIG. 1, a display unit 30 including a plurality of pixel electrodes P arranged in a matrix and a plurality of rows for applying a scanning signal (gate voltage) to the plurality of pixel electrodes P on an active matrix substrate. An electrode (scanning line or gate electrode) G, a plurality of column electrodes (source electrodes) S for giving a data signal (gray scale voltage) to a plurality of pixel electrodes P, a pixel electrode P, a row electrode G and a column electrode S. A switch element T for connecting to each other, a scan driver (gate driver) 32 for driving the row electrode G, and a data driver (data driver) 34 for driving the column electrode S are provided. A common electrode 36 is formed on the counter substrate.

The scan driver 32 is controlled by a controller 38 and receives a gate voltage from a gate voltage generating circuit 40. The data driver 34 is controlled by the controller 38 and receives the grayscale voltage from the grayscale voltage generation circuit 42. The common electrode 36 receives the common electrode voltage V from the common electrode drive circuit 44.
com is received and it drives.

When driving the above-mentioned active matrix type liquid crystal display, in general, a DC voltage is applied to the liquid crystal by alternately inverting the polarity of the voltage applied to the liquid crystal (this is called "AC driving of the liquid crystal"). It is designed so that it is not applied. This is because the liquid crystal has a property that its characteristics deteriorate when a DC voltage is applied. The most widely used method of AC driving of liquid crystal is the row inversion method (also referred to as “line inversion method”) shown in FIG.
According to this method, the polarity of the voltage applied to the liquid crystal is inverted for each row (scanning line) and for each frame. When the polarity inversion for each row is added to the polarity inversion for each row, the pixel inversion method (also referred to as “dot inversion”) shown in FIG. 3 is used.
The pixel inversion method is especially suitable for XGA because of its high display quality.
It is becoming the mainstream for driving large-sized and high-definition displays larger than the conventional models.

FIG. 4 shows the simplest one pixel P (i,
The equivalent circuit corresponding to j) is shown. The capacitance of a pixel is mainly composed of a pixel electrode and an auxiliary electrode (additional electrode), and in FIG. 4, the total capacitance is Cp.

FIG. 5 shows the drive timing of each part of the display shown in FIG. 1 and the waveform of the applied voltage. In FIG. 5, Vsy
n and Hsyn represent a vertical synchronizing signal and a horizontal synchronizing signal, respectively. When the output VG (j) of the scan driver corresponding to the j-th row becomes high potential, the switch element T (i, j) corresponding to the pixel P (i, j) in the j-th row is turned on, and the pixel P
(I, j) is the output S (i) of the data driver at that time
Is charged by. The switch element T (i, j) is turned off by the low potential of VG (j), and the pixel P (i, j) is turned off.
The electric charge charged in j) is then stored until T (i, j) is turned on, during which the liquid crystal filled between the pixel electrode and the common electrode continues to be driven. In addition, in FIG.
The number given to the horizontal synchronizing signal represents the horizontal period in which the image signal for the pixel of the row of the number is transmitted. Since the data driver samples and stores the data of the first row and outputs it in the next horizontal period, the scan driver of the corresponding row sets the output to a high potential in the horizontal period during which the data is transmitted. It is one horizontal period later.

FIG. 6 shows an equivalent circuit of one data line of the liquid crystal display. Cd and Rd respectively indicate the capacitance and resistance of the data line expressed by lumped constants, Cp indicates the pixel capacitance, and Ron indicates the on resistance of the switch element. The circuit of FIG. 6 serves as a load for one output of the data driver, but since the pixel capacitance Cp is a value smaller than the data line capacitance Cd by 2 to 3 digits, it can be ignored as the load of the driver. Therefore, the load of the driver is the data line resistance Rd and the data line capacitance C.
It is sufficient to consider d. By the way, the circuit of FIG. 6 exists in a one-to-one correspondence with the output of the data driver, and for the entire display, for example, even if it is a VGA type which has a relatively medium resolution at present, if it is a color type. 640 × 3 = 192
There are 0 of them, and the load of the data driver as a whole becomes considerably large. In the row inversion method or the pixel inversion method drive in which it is necessary to invert the output of the data driver for each scanning line, the capacity Cd is charged / discharged between positive and negative polarities for each output operation, so that power consumption increases. The problem arises.

As a method for preventing the above increase in power consumption, Japanese Patent Laid-Open No. 8-320674 proposes interlaced scanning. "Interlaced scanning" means that all odd-numbered (or even-numbered) pixel electrodes are first scanned,
Then, the remaining even-numbered (or odd-numbered) pixel electrodes are scanned. According to this method, since rows of pixels having the same polarity are sequentially scanned, it is possible to suppress the increase in power consumption. At the time when scanning of one frame (that is, scanning of both odd and even rows) is completed, a state similar to that of FIG. 2 or 3 is obtained.

[0009]

However, although the power consumption is reduced by the above-mentioned interlaced scanning, as a new problem, a slight horizontal stripe pattern appears every other row due to a slight difference in gradation between the odd-numbered row and the even-numbered row. May occur. In addition, flicker that cannot be ignored and image quality deterioration of moving images with large movements are sometimes seen.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce image quality such as flicker or to cause a gap between adjacent rows even when a driving method of interlaced scanning of pixel electrodes is used. It is an object of the present invention to provide an active matrix type liquid crystal display device capable of achieving high display quality and low power consumption without causing horizontal stripes due to a difference in gray scale, and a driving method thereof.

[0011]

A method of driving an active matrix type liquid crystal display according to the present invention applies a scanning signal to a plurality of pixel electrodes arranged in a matrix and pixel electrodes in the same row.
A display unit having a plurality of row electrodes to provide, respectively, said surface
Odd row for every frame for all row electrodes in the display
Or one of the even row electrodes was scanned with the same polarity potential.
Later, the other row electrode of the odd or even row is charged with the opposite polarity.
A method for driving an active matrix type liquid crystal display device, which performs interlaced scanning for scanning at a position, comprising:
Scan odd or even rows of interlaced scans first
Scan order for the first frame and the first frame following the first frame.
Odd rows of the interlaced scan in two frames and
The scan order as to which of the even rows is scanned first and
Differently, the jumping in the second frame
Check the respective polarities when scanning the odd and even rows,
Odd rows of the interlaced scan in the first frame
And the polarity opposite respective time of scanning the even rows, the above-mentioned object can be achieved by the it. Continue to the second frame
In the third frame, in the second frame,
Scan either odd or even rows of interlaced scanning first
In the same scan order as for
Scan and perform the interlace in the third frame
Polarity when scanning odd and even rows of scan
Is an odd number of the interlaced scan in the second frame
Reverse the polarities of the rows and even rows when scanning,
In the fourth frame following the third frame, the third frame
Of the odd and even rows of the interlaced scan
The scanning order differs from the scanning order as to which is scanned first.
The interlaced scanning is performed in the check order, and the fourth frame is
When scanning the odd and even rows of the interlaced scanning in
The respective polarities of the
Polarity and its polarity when scanning odd and even rows of interlaced scanning
Reverse each other .

Another active matrix type liquid crystal display driving method according to the present invention comprises a plurality of pixel electrodes arranged in a matrix ,
Multiple signals are applied to each pixel electrode in the same row.
A display unit having a number of row electrodes, less the display section
And for some consecutive row electrodes in some first areas
For each frame, one of the odd or even row
Odd or even rows after scanning the poles with potentials of the same polarity
The other row electrodes performing interlaced scanning scans in opposite polarity of the potential, a driving method of an active matrix type liquid crystal display device, the
The jump in the first area in one frame
Check whether odd or even rows are scanned first.
Current scan order and the second frame following the first frame.
Odd number of the interlaced scans of the first area
Run as to whether to scan row or even row first
The inspection order is different from that of the first frame in the second frame.
Running of odd and even rows of said interlaced scan in area 1
Check each polarity at the time of
Note Odd and even rows of the interlaced scan in the first area
Reverse the polarity when scanning . Adjacent to the first area
The interlace for a plurality of consecutive row electrodes in the second area
Scanning for each frame in succession in the first area.
The jump of the second area in the first frame
Scan across odd and even rows of interscan first
The scanning order for or and in the second frame
Odd rows and even lines of the interlaced scan of the second area
Different from the scan order as to which of the rows to scan first
The second area of the second frame
When scanning odd and even rows of interlaced scanning
The polarity of before the second area in the first frame
Polarity when scanning odd and even rows of interlaced scanning
Reverse each.

A third frame following the second frame
Then, odd-numbered rows of interlaced scanning in the second frame
And which even row to scan first
When the interlaced scanning is performed in the same scanning order as the order,
, The respective polarities when scanning the odd and even rows,
During scanning of odd and even rows in the second frame
The reverse of the polarities of the 3rd frame and the 4th subsequent to the 3rd frame.
Frame, the jump in the third frame
Check whether odd or even rows are scanned first.
The interlaced scanning is performed in a scanning order different from the conventional scanning order.
When scanning the odd and even rows,
Of the odd rows and even rows in the third frame
Reverse the polarity when scanning rows .

The active matrix type liquid crystal display according to the present invention has a plurality of pixel electrodes arranged in a matrix and pixel electrodes in the same row.
A plurality of row electrodes that respectively provide scanning signals to the poles
For each of the row electrodes of the display section having the display section ,
For each frame, apply the same row electrode on either the odd row or the even row.
The other of the odd or even rows after scanning with a potential of polarity
An active-matrix liquid crystal display device comprising: a scan driver that performs interlaced scanning by scanning the row electrodes of the same with an electric potential of opposite polarity , wherein the scan driver is interlaced in the first frame.
Whether to scan odd or even rows of the scan first
Scan order and the second frame following the first frame.
Odd and even rows of interlaced scanning in Laem
Different from the scanning order for scanning the shift first
And in the second frame, odd rows and even rows
The respective polarities at the time of scanning the row are set in the first frame.
Reverse the polarity when scanning odd and even rows.
To do .

Another active matrix type liquid crystal display according to the present invention has a plurality of pixel electrodes arranged in a matrix and a plurality of pixel electrodes in the same row.
A plurality of row electrodes that respectively provide scanning signals to the pixel electrodes
A display unit having a pole, and at least a part of the display unit
Each frame for multiple consecutive row electrodes in one area
Each time, one of the odd or even row electrodes is charged with the same polarity.
The other row electrode of the odd or even row after scanning
A scan driver for the interlace scanning for scanning in the opposite polarity of the potential, an active matrix type liquid crystal display device having a said scan
The driver is in front of the first section in the first frame
Run either odd line or even line of interlaced scanning first
Scan order as to whether to check and follow the first frame
And the jump over of the first area in the second frame.
Whether to scan odd or even rows of the first scan first
Different from the scan order for
An odd row of the interlaced scan of the first area and
And the even polarities of the even-numbered rows when scanning the first frame.
Odd rows of the interlaced scan of the first area
And the polarity when scanning even rows . Scan drive
In the third frame following the second frame,
Odd rows of the interlaced scan in the second frame
Order for which to scan first and even rows
The interlaced scanning is performed in the same scanning order as the introduction, and the third scanning is performed.
Odd lines and even lines of the interlaced scan in a frame
The respective polarities at the time of scanning the row are set in the second frame.
When the odd and even rows of the interlaced scan
Reverse the polarities respectively, and add the fourth frame following the third frame.
In the frame, the interlace in the third frame
Whether to scan odd or even rows of the scan first
The interlaced scanning in a scanning order different from that for
Of the interlaced scan in the fourth frame.
The respective polarities at the time of scanning the odd and even rows are
Odd rows of the interlaced scan in frame 3 and
Reverse the polarity when scanning even rows .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION <Regarding Occurrence of Alternate Horizontal Stripes> First, the cause of occurrence of alternate horizontal stripes due to interlaced scanning will be described. In the following description, the pixel in the same row has the same polarity in the row inversion mode. However, in the pixel inversion mode, the polarity is reversed in each column, and the content of the description can be directly applied. A description of the case of the inverted state is omitted. The "row inversion mode" here means that the polarity of the screen is in the state of FIG. 2 at the time when the driving of one frame is completed as described above. The "pixel inversion mode" is As described above, the polarity of the screen at the time when the driving of one frame is completed is in the state shown in FIG.

FIGS. 7A to 7D show the state transition of the voltage polarity when the pixel electrode is interlaced and scanned. Figure 7 (a)
Indicates the state immediately before the start of a new frame. At this time, the voltage polarity of each pixel is in the row inversion state. By scanning only the odd-numbered rows from here, the voltage polarities of the pixels in the odd-numbered rows are inverted, and the state shifts to the state of FIG. 7B. Next, by scanning the even-numbered rows, the voltage polarities of the pixels in the even-numbered rows are inverted, and the state shifts to the state of FIG. 7C. The state of FIG. 7C is a state in which the scanning of one frame is completed. In the next frame, similarly (however, the polarities are reversed), the state shifts to the state of FIG. 7A through the state of FIG. 7D.

FIG. 8 shows four columns adjacent to each other in the column direction (that is, four columns).
Pixel electrodes P (over the rows) are shown (TFT switch elements are omitted). A scanning line (gate line) G exists between each pixel electrode P, and sides in the scanning line direction are parallel to each other, so that a coupling capacitance Cpp exists between adjacent pixel electrodes. Electric charges are held in the coupling capacitance Cpp due to the voltage difference V between the two adjacent pixel electrodes, and the magnitude of the electric charges is
It is a function of the voltage difference V, is 0 when V = 0, and is a monotonically increasing function with respect to V (where V ≧ 0). In addition,
Since the dielectric constant of the liquid crystal changes depending on its alignment state, the coupling capacitance Cpp itself is also a function of the voltage difference V.

9 (a) and 9 (b) respectively show a case where charge is generated in the coupling capacitance Cpp and a case where no charge is generated in the coupling capacitance Cpp (that is, all four pixel electrodes shown in FIG. 8 are at the same potential). 4 shows an equivalent circuit of four pixel electrodes. When no electric charge is generated in the coupling capacitance Cpp,
In order to make the equivalent circuit easy to see, the relevant portion of the coupling capacitance Cpp is omitted from FIG. 9B (the same applies hereinafter). Assume that the same data is written on the entire screen. Note that "writing data" means charging the pixel electrode with a voltage corresponding to the data (the same applies hereinafter).

When the state of FIG. 7A transits to the state of FIG. 7B and when the state of FIG. 7C transits to the state of FIG. Transitions from the appearing state to the disappearing state. For simplification, the influence between pixels in two adjacent rows will be described with reference to FIGS. When pixels in odd rows are written with the switch elements A in even rows open, the charge transfer state changes from FIG. 10A to FIG.
The transition is from (c) to FIG. 10 (d). Since the switch elements A in the even-numbered rows are still open, the charge of −q or + q trapped in the capacitance Cpp moves to the pixel electrodes in the even-numbered rows due to the disappearance of the voltage difference across the capacitance Cpp, The charge of the pixel electrode increases to − (Q + q) or (Q + q). That is, the writing of data to the pixels in one row (odd row) works to deepen the voltage of the pixels in the adjacent row (even row). Strictly speaking, a slight electric charge between A and B remains in the capacitor Cpp due to the slight difference in potential generated here, but it is extremely small with respect to the original electric charge q and can be ignored. Note that "the voltage becomes deeper" means that the potential difference between the pixel electrode and the common electrode becomes large (the same applies hereinafter).

Further, in FIGS. 10A and 10C, the electric charges of the pixels in the odd-numbered rows are Qq and-(Qq), respectively, as will be apparent from the description of FIG. 11 below. 7D from the state of FIG. 7D to the state of FIG. 7A or the state of FIG.
This is the result of being affected by the transition to the state of (c). Since the adjacent row is an even row in the above case, the even row is applied with a voltage deeper than the original gradation.

With the same consideration, the state of FIG.
To the state of (c) or from the state of FIG. 7 (d) to FIG. 7 (a)
11C, the equivalent circuit changes from the state of FIG. 11B to the state of FIG. 11C or the state of FIG.
The state changes to (a). Since the voltage difference between the adjacent rows appears, the charge of the pixel electrode moves to the capacitance Cpp, and the voltage of the pixel in the adjacent row becomes shallow. “The voltage becomes shallow” means that the potential difference between the pixel electrode and the common electrode becomes small (the same applies hereinafter). In this case, the adjacent rows are odd rows, so that the odd rows have a shallower voltage than the original gradation.

As described above, when a potential having the same polarity as that of the voltage of the electrode is written to the adjacent electrode of the certain electrode, the voltage of the electrode becomes deep, whereas when writing a voltage of the opposite polarity. That is, the voltage of that electrode becomes shallow. For this reason, in a normally black display, the odd rows are lighter than the original gradation and the even rows are darker, which causes a slight gradation difference between the even rows and the odd rows. It will be observed as thin horizontal stripes every other row.

FIG. 12 shows a waveform of the above drive when the display device includes eight rows of pixel electrodes and scanning lines. In addition,
For simplification, it is assumed that the display has eight scanning lines unless otherwise specified. The actual number of scanning lines of the display is much larger, for example, 726, but the driving principle is exactly the same. In FIG. 12, VP (i, 3) and VP (i, 4) represent the potentials of the pixel electrodes in the third row and the fourth row, respectively, and the shaded portions represent the potential fluctuation portions. Show.

As described above, the electrode adjacent to an electrode is
When writing a potential having the same polarity as that of the voltage of the electrode, the voltage of the electrode becomes deep, whereas when writing a voltage of the opposite polarity, the voltage of the electrode becomes shallow. This is reflected in the waveform shown in FIG. That is, the odd-numbered rows VP (i, 3) fluctuate so that the voltages become shallower in consecutive frames, and the even-numbered rows PV (i, 4) change.
On the contrary, the voltage fluctuates so that it becomes deeper.

There are other factors such as a pull-in voltage when the gate is turned off as factors for changing the potential of the pixel, but these are not directly related to the present invention, and therefore are shown in order to avoid complication. No (same below).
In addition, the variation of the potential is exaggerated for visual recognition. The actual level of potential fluctuation depends on the characteristics of the display device and cannot be generally stated, but is, for example, about 1% of the pixel electrode potential with respect to the common electrode.

In the above description, the case where the data is written in the pixels in the odd-numbered rows first, and then the data is written in the pixels in the even-numbered rows is explained. However, even if the even-numbered rows are written first and the odd-numbered rows are written later. Since the causes of the problems that occur are the same, description will be omitted.

The present invention displays an image based on the coupling capacitance between adjacent pixels on the same column as described above even when performing interlaced scanning on all or part of the screen in order to reduce power consumption. This was done to prevent deterioration and to realize high-quality display without horizontal stripes.

<Basic Concept of the Present Invention> As discussed above, in the case where all or part of the screen is interlacedly scanned in a certain field, the voltage polarities of pixels in adjacent rows are changed to the same state. When it changes like
The voltage of the pixel written in the previous field changes so as to become deeper. When the voltage polarities of the pixels in the adjacent rows change from the same state to different states, the voltage of the pixels written in the previous field changes so as to become shallow.

In consideration of this situation, in order to erase the horizontal stripes in every other row, the present invention makes the pixels in a certain row have a shallow voltage in a certain frame, and the pixels in the following frame have a deep voltage. To do so. By this,
The change in the voltage of the pixel is canceled in successive frames, and a uniform voltage is applied to the pixel as an effective value. More specifically, in a portion where interlaced scanning is performed, in a certain frame, when scanning is performed in a first scanning order in which pixel electrodes in odd rows are scanned and then pixel electrodes in even rows are scanned, In the frame, scanning is performed in the second scanning order in which the pixel electrodes in the even-numbered rows are scanned and then the pixel electrodes in the odd-numbered rows are scanned, as opposed to the first scanning order. That is, by alternating the first scanning order and the second scanning order for each frame, every other horizontal stripe is erased.

(First Embodiment) The first embodiment of the driving method of the active matrix type liquid crystal display according to the present invention will be described in detail below. The active matrix type liquid crystal display according to the present invention has basically the same configuration as that shown in FIG. 1, and the description thereof will be omitted.

A method of driving the active matrix type liquid crystal display device of this embodiment will be described with reference to FIG. FIG. 13 shows 1
It is the schematic of the display part 30 (FIG. 1) which showed the pixel of a row as one line. This figure shows the order of scanning over two frames (frame (a) and frame (b)). The numbers on the left end are the numbers of pixel rows counted from the top of the screen, and the numbers in the circles indicate the scanning order.

First, in the frame (a), the first, third, fifth, and seventh odd rows are scanned (first frame, first field), and then the second, fourth, sixth, and eighth even rows are scanned. Scan (first frame, second field). In the next frame (b), on the contrary, the even-numbered rows of the second, fourth, sixth and eighth rows are scanned first (first field of the second frame), and then the first,
Scan odd rows 3, 5, and 7 (second frame second
field).

14A to 14D show state transitions of the polarities of the pixels in the above scanning. In the first field of the first frame, the first, third, fifth, and seventh lines change from positive to negative (transition from state (a) to state (b)). Therefore, the pixels in the adjacent rows (second, fourth, sixth and eighth rows) are
Since the pixels on the third, fifth, and seventh rows make a transition from the different polarities to the same potential having the same polarity, the pixel voltages on the second, fourth, sixth, and eighth rows written in the previous field become deeper. (Actually, the potential that had become shallow returns to the original).

In the second field of the first frame, the second,
The polarities of the pixels in rows 4, 6, and 8 change from negative to positive (transition from the state of (b) to the state of (c)). Therefore,
The pixels in the adjacent rows (first, third, fifth and seventh rows) are
Since the same electric potential of the same polarity is changed to the different polarities for the pixels of the 6th and 8th rows, the pixel voltage of the 1st, 3rd, 5th and 7th rows written in the previous field becomes shallow.

In the first field of the second frame, the second,
The polarities of the pixels in rows 4, 6, and 8 change from positive to negative (transition from state (c) to state (d)). Therefore,
The pixels in the adjacent rows (first, third, fifth and seventh rows) are
Since the pixels of rows 6 and 8 make a transition from different polarities to the same potential of the same polarity, the potential becomes deep (actually, the potential that has become shallow is restored).

In the second field of the second frame, the first,
The polarities of the pixels in the third, fifth, and seventh rows change from negative to positive (transition from the state (d) to the state (a)). Therefore,
The pixels in the second, fourth, sixth and eighth rows are the first, third, fifth and seventh.
The transition from the same polarity to different polarities with respect to the pixels in the row makes the potential shallow.

FIG. 15 shows drive waveforms for the above scanning. Both the odd-row pixel P (i, 3) and the even-row pixel P (i, 4) are both at the negative potentials (VP (i, 3) and V).
Since P (i, 4) changes so as to become shallow, the influence on the gradation in the odd / even rows is the same and horizontal stripes do not occur. However, in the present embodiment, since the driving time for the positive polarity is different from that for the negative polarity, a small amount of direct current is applied as an average value. However, it does not immediately become a practical problem. Even if a direct current as an average value is applied, irreversible destruction of the liquid crystal does not occur if the voltage is small. This is because, for example, afterimages are likely to occur, but it does not matter if there is no problem from a practical level. In that sense, the present embodiment has a practically sufficient level of practical use depending on the purpose of use of the display.

In the above description, in order to make it easy to understand, the case where all the screens display the same gradation is explained. When the gray scales of the pixels in the adjacent rows are different, the electric charges are always left in the coupling capacitance Cpp, but the same mechanism causes the movement of the electric charges, which is slightly different from the original gray scale. Is. Also in the following description, the case where all screens display the same gradation will be described.

(Second Embodiment) A second embodiment of the driving method of the active matrix type liquid crystal display according to the present invention will be described below. In the present embodiment, the scanning order of the first frame and the second frame is the same as that of the first embodiment, and the scanning order of the third frame and the fourth frame is the reverse of that of the first frame and the second frame. To That is, in the third frame, the even rows are scanned first, the odd rows are scanned later, and the fourth row is scanned.
In a frame, odd rows are scanned first and even rows are scanned later.

FIGS. 16A to 16D show the scanning order of four consecutive frames as described above. FIG. 17 shows the drive waveform. As shown in FIG. 17, T ₁ (+) and T ₂ of the voltage VP (i, 3) of the pixel P (i, 3) in the third row
The (+), T ₁ (−), and T ₂ (−) portions are T of the voltage VP (i, 4) of the pixel P (i, 4) in the fourth row, respectively.
_The waveforms are inverted with respect to the common electrode and the portions of ₁ (+), T ₂ (+), T ₁ (-), and T ₂ (-). Therefore, the effective values (of alternating current) are almost the same, there is no difference in gradation, and horizontal stripes do not occur.

The present embodiment is superior to the first embodiment in that four frames are used as one cycle and the odd-row pixels and the even-row pixels have a positive polarity time and a negative polarity time. Are the same. For each of the pixel P (i, 3) and the pixel P (i, 4), the time obtained by adding T ₁ (+) and T ₂ (+) is the time obtained by adding T ₁ (−) and T ₂ (−). Because they will be equal. Therefore, the occurrence of horizontal stripes can be prevented without sacrificing the AC driving of the liquid crystal for preventing the application of the DC voltage as the average value. Note that if the time for one frame is 1/60 seconds, the cycle for four frames is 1/15 seconds, but the voltage difference at issue here is extremely small, and this causes flicker. There is nothing to do.

(Third Embodiment) The third embodiment of the driving method of the active matrix type liquid crystal display according to the present invention will be described below.

FIG. 18 shows drive waveforms when the first embodiment is applied to a display device including 18 rows of pixels. In FIG. 18, the drive waveforms of the pixels on and after the ninth row are omitted. The numbers given to the waveform of Hsyn are numbers sequentially given from the horizontal period corresponding to the period in which scanning is started (the meaning is different from the number given to the waveform of Hsyn in FIG. 5). . The problem in the case of driving in FIG. 18 is that the imbalance between the time when the positive voltage is applied to the pixel and the time when the negative voltage is applied to the pixel are larger than in the case of the driving in FIG. This imbalance increases as the number of rows increases.

The third embodiment of the present invention is to solve this problem. 19 (a) and (b)
Shows the scanning order of pixels over two frames in the present embodiment. In the present embodiment, the number of pixels in the display unit is set to 2 for every 8 rows.
The area is divided into two areas (first area and second area), and the interlace scanning is completed for each area in the order of the numbers circled.

FIG. 20 shows drive waveforms for the above scanning.
Note that the drive waveforms of the pixels on the ninth and subsequent rows are omitted as in FIG. As is clear from the figure, since the interlace scanning is completed in each area, the time imbalance between the positive and negative voltages of each pixel is smaller than that in the case of FIG. Even when the number of rows of pixels is further increased, it is possible to suppress the increase in the positive / negative imbalance by increasing the number of areas. For example, when the number of rows of pixels is 480, it may be divided into 60 areas every 8 rows. Of course, the number of rows included in one area is not limited to eight and can be determined to be any number.

The method of dividing the display portion into a plurality of areas in the column direction and completing the interlaced scanning for each area as described above is disclosed in Japanese Patent Application No.
0-161199. With this method, it is possible to reliably reduce the power consumption, and it is possible to suppress flickering (flicker) and image quality deterioration of a moving image with large movement.

(Fourth Embodiment) FIGS. 21A to 21D.
FIG. 8 shows a pixel scanning order according to a fourth embodiment of the driving method of the active matrix type liquid crystal display of the present invention. In this embodiment,
The third embodiment (FIG. 19) and the second embodiment (FIG. 1)
This is the case when the concept of 6) is added.

According to the present embodiment, the imbalance in the time taken by the positive and negative voltages of each pixel is suppressed (effect of the third embodiment), and the time when the pixels in the odd rows and the pixels in the even rows are both positive. By applying the same negative polarity time, it is possible to prevent application of a DC voltage as an average value (effect of the second embodiment).
However, it is possible to prevent the occurrence of horizontal stripes.

(Fifth Embodiment) FIGS. 22A and 22B show the scanning order of pixels according to a fifth embodiment of the method of driving an active matrix type liquid crystal display device of the present invention.

This embodiment is a modification of the embodiment of FIG. 19 (third embodiment), and FIG.
And the order of scanning is interchanged as shown in (b). More specifically, when interlaced scanning is performed in the first scanning order of odd rows to even rows in the first area, interlaced scanning is performed in the second scanning order of even rows to odd rows in the second area. I do. Needless to say,
When interlaced scanning is performed in the second area in the first area, interlaced scanning is performed in the first area in the second area.

As described above, in the present embodiment, even if the scanning order of each area is set independently, it does not deviate from the essence of the present invention, and the above-mentioned effects can be obtained.

Needless to say, in all the above embodiments, the positive and negative polarities of the pixel potential may be reversed in each frame. Further, although not described in the above embodiments because it is not directly related to the essence of the present invention, the data driver outputs data to the pixel electrodes in response to scanning of the pixel electrodes in each row. It goes without saying that it is controlled.

[0054]

In the driving method for performing the interlaced scanning on the display portion, the pixel electrodes are scanned in the odd-numbered row (or even-numbered row) and then the even-numbered row (or odd-numbered row) in a certain frame. In that case, in the next frame, pixel electrodes in even rows (or odd rows) are scanned and then pixel electrodes in odd rows (or even rows) are scanned. As a result, power consumption can be reduced and at the same time horizontal stripes in every other row can be prevented from occurring.

When the display section is divided into a plurality of areas in the column direction, and the pixel electrodes in one area are interlaced in the first scanning order in the first frame, the first frame following the first frame is scanned. The second frame is interlaced in the second scanning order. As a result, it is possible to suppress image quality deterioration of a moving image with large flicker and large movement.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a liquid crystal display.

FIG. 2 is a diagram showing a polarity distribution and transition of a pixel voltage in a row inversion method.

FIG. 3 is a diagram showing a polarity distribution and transition of a pixel voltage in a pixel inversion method.

FIG. 4 is the simplest equivalent circuit diagram of a TFT and a pixel.

FIG. 5 is a diagram showing a drive timing of a TFT liquid crystal display and a waveform of a pixel voltage.

FIG. 6 is an equivalent circuit diagram of a data line.

7A to 7D are diagrams showing state transitions of polarities of pixel voltages during interlaced scanning.

FIG. 8 is a diagram showing continuous pixel electrodes on the same column.

9A and 9B are equivalent circuit diagrams of continuous pixel electrodes on the same column.

10A to 10D are diagrams showing a state change of an equivalent circuit when pixels in odd rows are charged.

11A to 11D are diagrams showing a state change of an equivalent circuit when pixels in even-numbered rows are charged.

FIG. 12 is a diagram showing a drive waveform of a display device when display quality is deteriorated.

FIGS. 13A and 13B are diagrams showing a scanning order of pixel electrodes in the first embodiment of the present invention.

14A to 14D are diagrams showing state transitions of polarities of pixel voltages in the scanning of FIG.

FIG. 15 is a diagram showing drive waveforms for scanning in FIG.

16A to 16D are diagrams showing the scanning order of pixel electrodes in the second embodiment of the present invention.

FIG. 17 is a diagram showing drive waveforms for scanning in FIG.

FIG. 18 is a diagram showing scan drive waveforms according to the first embodiment of the present invention when the number of rows of pixels is large.

19 (a) and 19 (b) are views showing the scanning order of pixel electrodes in the third embodiment of the present invention.

FIG. 20 is a diagram showing drive waveforms for scanning in FIG.

21A to 21D are diagrams showing the scanning order of pixel electrodes in the fourth embodiment of the present invention.

22A and 22B are diagrams showing a scanning order of pixel electrodes in the fifth embodiment of the present invention.

[Explanation of symbols]

30 Display 32 Scan driver (gate driver) 34 Data driver 36 common electrode 38 Control unit 40 Gate voltage generator 42 gradation voltage generation circuit 44 Common electrode drive circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G09G 3/20 G09G 3/20 621C 622 622N 642 642A (56) Reference JP-A-2-213894 (JP, A) JP-A 10-228263 (JP, A) JP 5-46123 (JP, A) JP 63-144671 (JP, A) JP 9-236787 (JP, A) JP 64-38729 (JP, A) A) JP-A-3-289618 (JP, A) JP-A-6-222330 (JP, A) JP-A-9-80466 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G09G 3/00-3/38 G02F 1/133 505-580 H04N 5/66-5/74

Claims (8)

(57) [Claims] 1. A scanning signal is applied to each of a plurality of pixel electrodes arranged in a matrix and a pixel electrode in the same row.
A display unit having a plurality of row electrodes, and an odd number for each frame for all the row electrodes of the display unit.
Scan one or several row electrodes with the same polarity potential
The other row electrode of the odd or even row after
A method of driving an active matrix type liquid crystal display device, which performs interlaced scanning, comprising: an odd-numbered row and interlaced scanning in the first frame.
Order of which line to scan first and even lines
And in the second frame following the first frame
Run either odd line or even line of interlaced scanning first
The scanning order regarding whether to perform scanning is different, and the odd-numbered rows of the interlaced scanning in the second frame are different .
And the respective polarities at the time of scanning even-numbered rows are set to the first frame.
Of the odd and even rows of the interlaced scan
A method for driving an active matrix type liquid crystal display device , which has a polarity opposite to that during scanning . 2. In a third frame following the second frame, the interlaced scanning of the second frame is performed .
Whether to scan odd rows or even rows first
Perform the interlaced scanning in the same scanning order as
Odd rows of the interlaced scan in the third frame
The respective polarities at the time of scanning the and even rows are set to the second frame.
Of the odd and even rows of the interlaced scan
In the fourth frame following the third frame, the polarities are opposite to those in the scanning and the third frame is used .
Odd lines and even lines of the interlaced scan in a frame
Different from the scan order as to which of the rows to scan first
The interlaced scanning is performed in the scanning order of
The odd and even rows of the interlaced scan
Check each polarity at the time of
Polarity when scanning odd and even rows of interlaced scanning
The method of driving an active matrix type liquid crystal display device according to claim 1, wherein the driving methods are reversed . 3. A scanning signal is applied to each of a plurality of pixel electrodes arranged in a matrix and a pixel electrode in the same row.
A display section having a plurality of row electrodes and a plurality of continuous first electrodes in at least a part of the display section.
Row electrodes for each frame, odd rows or even rows
After scanning one of the row electrodes with the same polarity potential,
Scan the other row electrode of the row or even row with a potential of opposite polarity
A method of driving an active matrix type liquid crystal display, which performs interlaced scanning , wherein the interlace of the first area in a first frame is performed.
Whether to scan odd or even rows of the scan first
Scan order and the second frame following the first frame.
Oddness of the interlaced scan of the first area in Laem
Whether to scan several lines or even lines first
The scan order is different, and the interlace of the first area in the second frame is different .
Polarity of odd-numbered and even-numbered scans
To the fly in the first area of the first frame.
Contrary to the polarity when scanning odd and even rows of interlaced scanning
A method for driving an active matrix type liquid crystal display. 4. A second area adjacent to the first area
The interlaced scanning is performed on a plurality of continuous row electrodes,
The first area is continuously performed for each frame, and the interlacing of the second area in the first frame is performed.
Whether to scan odd or even rows of the scan first
Scan order for the
Of the odd and even rows of the interlaced scan of the second area
If the scan order is different about which one to scan first
The jump of the second area in the second frame
Polarity of odd-numbered and even-numbered scans
The jump of the second area in the first frame
Polarity and each of the odd-numbered and even-numbered rows of overscan
The active matrix type liquid crystal display according to claim 3, which is reversed.
Driving method. 5. In a third frame following the second frame, an odd number of interlaced scans in the second frame.
Run as to whether to scan row or even row first
When the interlaced scanning is performed in the same scanning order as the scanning order,
, The respective polarities when scanning the odd and even rows,
During scanning of odd and even rows in the second frame
In the fourth frame following the third frame, the polarities of the
Of interlaced scan odd and even rows in a frame
The scanning order differs from the scanning order as to which is scanned first.
In addition to performing the interlaced scanning in the check order,
And the even-numbered row when scanning the respective polarities at the third frame
Polarity and each of the odd and even rows in scanning
The method for driving an active matrix type liquid crystal display device according to claim 3, which is reversed . 6. A scanning signal is applied to each of a plurality of pixel electrodes arranged in a matrix and a pixel electrode in the same row.
An odd number for each frame for a display unit having a plurality of row electrodes and
Scan one or several row electrodes with the same polarity potential
The other row electrode of the odd or even row after
A active matrix type liquid crystal display device which includes a scanning driver for the interlace scanning for scanning in the potential, the scanning driver is interlaced in the first frame scanning
Whether to scan the odd and even rows of
Scan order and the second frame following the first frame.
Both odd and even rows of interlaced scanning
Different from the scan order of whether to scan first
Together, in the second frame,
The respective polarities at the time of scanning are set in the first frame.
Reverse the polarity when scanning odd and even rows.
That, an active matrix type liquid crystal display device. 7. A scanning signal is applied to each of a plurality of pixel electrodes arranged in a matrix and a pixel electrode in the same row.
A plurality of row electrodes, and a plurality of continuous first areas of at least a part of the display section.
Row electrodes for each frame, odd rows or even rows
After scanning one of the row electrodes with the same polarity potential,
Scan the other row electrode of the row or even row with a potential of opposite polarity
A scan driver interlace for scanning that, be an active matrix type liquid crystal display device having a said scan driver, the in the first frame the first ward
The odd and even rows of the interlaced scan
The scanning order as to whether to scan first and the first frame
Of the first area in the second frame following the
Scan either odd or even rows of interlaced scanning first
The scan order of whether to perform the skipping of the first area in the second frame.
Polarity of odd-numbered and even-numbered scans
To the fly in the first area of the first frame.
Contrary to the polarity when scanning odd and even rows of interlaced scanning
To, active matrix type liquid crystal display device. 8. The scan driver is arranged in the second frame.
In the third frame following
Whichever of the odd and even rows of the interlaced scan
The scan order is the same as the scan order for scanning.
Interlaced scanning is performed, and the jump in the third frame is performed.
The poles of the odd and even rows of the cross scan
Of the interlaced scan in the second frame.
In the fourth frame following the third frame, the polarities are reversed when scanning several rows and even rows, and the third frame is used.
Odd lines and even lines of the interlaced scan in a frame
Different from the scan order as to which of the rows to scan first
The interlaced scanning is performed in the scanning order of
The odd and even rows of the interlaced scan
Check each polarity at the time of
Polarity when scanning odd and even rows of interlaced scanning
The active matrix according to claim 6 or 7, which are respectively reversed.
Type liquid crystal display .