JPH1032772A - Liquid crystal display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a video so that a flicker does not occur by combining string inversion driving, line inversion driving and pair line driving and driving the polarities of video input signals and thinning one scan line at timing when the polarities are line-inverted so as to execute driving. SOLUTION: A timing generator 11 inverts the polarity of a selection signal in synchronizing with the respective driving timings of a gate electrode. Switches SW1 and SW2 are changed over by the inversion timing and the video signal 1 generated by a non-inversion amplifier Amp1 and the video signal 2 generated by an inversion amplifier Amp2 are outputted to source drivers A13 and B14. In such a case, the polarities of the video signals applied to a source electrode is driven by combining array reversion driving, line reversion driving and pair line driving. One scan line is thinned at timing when the polarities of the video signals are line-reversed by a gate driver 12.

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 device provided with a liquid crystal drive control circuit for suppressing the occurrence of flicker and the like and improving the image display quality.

[0002]

2. Description of the Related Art In order to faithfully reproduce an interlaced drive image corresponding to a conventional television system such as NTSC or PAL in a liquid crystal television system, it is suitable for non-interlace drive using a frame memory or a line memory. It is necessary to implement a liquid crystal drive control method such as conversion into a video signal or a pair line drive.

Further, the liquid crystal cell itself needs to be driven by an alternating current because of its physical property that when the direct current is driven, an electrochemical reaction is induced inside the liquid crystal cell and the life of the liquid crystal display panel is remarkably deteriorated. Therefore, various liquid crystal drive control circuits have been proposed in order to realize a liquid crystal drive control method for realizing the non-interlace drive and the pair line drive and the like and a liquid crystal AC drive control method.

[0004]

However, the conventional liquid crystal drive control method for realizing such non-interlace drive and pair line drive for a liquid crystal display panel and the liquid crystal drive control circuit for realizing an AC drive control method. If so, there were the following problems.

[0005] First, a problem in the case where the liquid crystal display panel is AC-driven controlled will be described.

FIG. 12 is a cross-sectional view of a black and white liquid crystal display panel 1.
The upper and lower surfaces of a liquid crystal cell 4 composed of a pair of polarizing plates 5,
6 is a transmission type in which a backlight (not shown) is disposed below one of the polarizing plates 5. A source electrode (signal electrode) 7 is formed on the lower glass substrate 2 constituting the liquid crystal cell 4, and a common electrode (common electrode) 8 is formed on the upper glass substrate 3. When a predetermined voltage is applied between the electrodes 8, the amount of transmitted light changes and characters and pictures are displayed.

The source signal applied to the source electrode 7 and the common signal applied to the common electrode 8 are, for example,
As shown by drive A or drive B in FIG. 13, it is necessary to perform AC drive control based on the physical characteristics of the liquid crystal by using an AC drive signal that inverts the polarity of the video signal for each of the odd field and the even field. Drive cycle fV ≤5
If the frequency is not set to 0 to 60 Hz, flicker occurs.
Here, the interlaced video signal of the current television system such as NTSC or PAL is directly driven by the interlaced driving system, as shown in FIG. 14, by the scanning lines H1 to H8. In this case, as shown in FIG. 15, the driving cycle of each of the scanning lines H1 and H2 for each field is 15
Hz, and flicker occurs.

Next, a problem in the case of displaying an interlaced video signal on a liquid crystal display panel will be described.

As described above, if the video signal of the interlaced drive of the current television system such as NTSC or PAL is interlaced driven as it is, flicker occurs. When non-interlaced driving is performed, flicker can be suppressed. Now, for example, as shown in FIG. 16, the polarity of the video signal input to the source electrode is inverted for each of the scanning lines H1 to H6, and the polarity of the video signal is changed for each of the odd and even fields. Invert and drive. As shown in FIG. 17, the driving waveform at this time is such that the polarity of the video signal is inverted for each of the scanning lines H1, H2 and for each field. When the entire screen is viewed, the polarity is mixed for each line or each field, so that the application of the DC voltage to the liquid crystal element is eliminated, and the flicker is not seen.

However, when converting the interlaced video signal into a non-interlaced video signal, the interlaced video signal is temporarily stored in a memory and the polarity of the video signal for complementing the scan line is taken into consideration. Although the generation method is reliable, it leads to an increase in the cost of the driving circuit.

To solve this problem, a pair line driving method can be considered. If this pair line driving is simply performed, FIG.
As shown in FIG. 8, since the polarity of the video signal input to the heath electrode corresponding to the scan line driven by the pair line is the same, FIG. And FIG. 20 shows a timing chart of the video signal at the time of the pair line driving, and when the polarity change of the video signal between the scanning lines driven by the pair line is macroscopically viewed on the time axis, each scanning line is 1
At a driving frequency of 5 Hz, a portion surrounded by an ellipse in FIG. 19 appears as if a 30 Hz flicker flows one by one as a whole screen.

An object of the present invention is to drive a liquid crystal signal by driving a video signal which is interlaced in a current television system such as NTSC or PAL by combining column inversion driving, line inversion driving, pair line driving and the like. An object of the present invention is to provide a liquid crystal display device and a driving method thereof that realize high image quality without adding an expensive and large-scale circuit such as a memory to a control circuit and without generating flicker or the like.

[0013]

According to the first aspect of the present invention,
Arranging a plurality of signal lines and a plurality of scanning lines in a matrix,
A liquid crystal panel having a display element connected to each intersection of these signal lines and scanning lines; scanning means for scanning the plurality of scanning lines at a scanning timing according to a video input signal; and a video input to each of the signal lines. Video drive means for alternatingly driving each of the display elements while alternately inverting the polarity of the input signal positively and negatively at predetermined intervals, wherein the scanning means scans the video input signal. A predetermined number of adjacent scanning lines among the plurality of scanning lines are simultaneously scanned based on timing, and the video input signal is thinned out at a rate of one scanning line for each of the simultaneously scanned scanning lines. Sets a polarity inversion pattern for inverting the polarity of the video input signal for each of the number of scanning lines that are simultaneously scanned by the scanning means, and decimates the polarity inversion pattern by the video input signal. Along with the change in that timing,
The display device is characterized in that the polarity inversion pattern is inverted at predetermined intervals to drive each of the display elements by AC.

According to the liquid crystal display device of the present invention, a plurality of signal lines and a plurality of scanning lines are arranged in a matrix, and a display element is connected to each intersection of the signal lines and the scanning lines. A liquid crystal panel, a scanning unit that scans the plurality of scanning lines at a scanning timing according to a video input signal, and a video input signal input to each of the signal lines, the polarity of which is alternately switched between positive and negative at predetermined intervals. A liquid crystal display device comprising: a video driving unit that drives each of the display elements in an alternating manner while inverting, wherein the scanning unit includes a predetermined number of adjacent ones of the plurality of scanning lines based on a scanning timing of the video input signal. Are simultaneously scanned, and the video input signal is thinned out at a rate of one scan line for each of the simultaneously scanned scanning lines, and the video driving unit scans the scanning lines simultaneously scanned by the scanning unit. A polarity inversion pattern for inverting the polarity of the video input signal is set for each number of lines, and the polarity inversion pattern is changed at a timing at which the video input signal is thinned out, and the polarity inversion pattern is inverted at predetermined intervals. Thus, the display elements are AC-driven.

According to a fourth aspect of the present invention, a plurality of signal lines and a plurality of scanning lines are arranged in a matrix, and a display element is connected to each intersection of the signal lines and the scanning lines. AC driving each of the display elements while scanning the plurality of scanning lines at a scanning timing according to the above, and alternately inverting the polarity of the video input signal input to each of the signal lines at predetermined intervals alternately. In the method for driving a liquid crystal display device, a predetermined number of adjacent scanning lines among the plurality of scanning lines are simultaneously scanned based on the scanning timing of the video input signal, and one scan is performed for each of the simultaneously scanned scanning lines. The video input signal is decimated at a line ratio, a polarity inversion pattern for inverting the polarity of the video input signal is set for each of the number of simultaneously scanned scanning lines, and the polarity inversion pattern is input to the video input signal. No. along with change in the timing to be thinned out, is characterized in that by inverting the polarity inversion pattern for each predetermined cycle AC driving the respective display elements.

According to the driving method of the liquid crystal display device of the present invention, a plurality of signal lines and a plurality of scanning lines are arranged in a matrix, and a display is provided at each intersection of the signal lines and the scanning lines. The devices are connected, and the plurality of scanning lines are scanned at a scanning timing according to a video input signal, and the polarity of the video input signal input to each of the signal lines is alternately switched between positive and negative at predetermined intervals. In the method of driving a liquid crystal display device, wherein each of the display elements is AC-driven, a predetermined number of adjacent scanning lines of the plurality of scanning lines are simultaneously scanned based on a scanning timing of the video input signal, and the simultaneous scanning is performed. The video input signal is thinned out at a rate of one scan line for each scanning line number to be scanned, and a polarity inversion pattern for inverting the polarity of the video input signal is set for each of the simultaneously scanned scanning lines, With polar reversal pattern is changed in the timing of the video input signal are thinned to,
The polarity inversion pattern is inverted at predetermined intervals, and the display elements are AC-driven.

Therefore, the polarity of the video input signal to be input to the signal line is driven by, for example, a combination of column inversion drive, line inversion drive, and pair line drive. When performing conventional non-interlaced drive control by thinning out scan lines and performing conventional non-interlaced drive control, it is possible to perform video display without flicker without adding an external circuit such as a memory that stores video input signals for interlaced drive. it can. As a result, the display image quality can be improved without increasing the system cost of the liquid crystal display device.

Further, in this case, as in the liquid crystal display device according to the second aspect of the present invention, the scanning means does not thin out the video input signal and based on the scanning timing of the video input signal. A predetermined number of adjacent scanning lines are simultaneously scanned among the scanning lines, and the video driving unit sets a polarity inversion pattern for inverting the polarity of the video input signal for each of the number of scanning lines simultaneously scanned by the scanning unit. Alternatively, the display elements may be AC-driven by sequentially moving the polarity inversion pattern by a predetermined number of scanning lines of the number of scanning lines simultaneously scanned in a predetermined period.

According to the liquid crystal display device of the second aspect of the present invention, the scanning means does not thin out the video input signal and selects one of the plurality of scanning lines based on the scanning timing of the video input signal. A predetermined number of adjacent scanning lines are simultaneously scanned, and in the video driving unit, a polarity reversal pattern for reversing the polarity of the video input signal is set for each of the number of scanning lines simultaneously scanned by the scanning unit. The display elements are AC-driven by sequentially moving the polarity inversion pattern by a predetermined number of scanning lines of the number of scanning lines simultaneously scanned at a predetermined period.

In this case, the plurality of scans are performed based on the scan timing of the video input signal without thinning out the video input signal as in the driving method of the liquid crystal display device according to the present invention. A predetermined number of adjacent scanning lines among the lines are simultaneously scanned, and a polarity inversion pattern for inverting the polarity of the video input signal is set for each of the simultaneously scanned scanning lines, and the polarity inversion pattern is formed at a predetermined period. The display elements may be AC-driven by sequentially moving by a predetermined number of scanning lines of the number of scanning lines simultaneously scanned.

According to the driving method of the liquid crystal display device according to the fifth aspect, the predetermined number of adjacent ones of the plurality of scanning lines are not thinned out based on the scanning timing of the video input signal. Are simultaneously scanned, a polarity inversion pattern for inverting the polarity of the video input signal is set for each of the simultaneously scanned lines, and the polarity inversion pattern is simultaneously scanned at a predetermined period. The display elements are sequentially driven by a predetermined number of scanning lines of the number of lines, and the display elements are AC-driven.

Therefore, without thinning out the video input signal,
For example, by performing a drive pattern in which the timing of inverting the polarity of the video input signal line by line is changed for each scanning line for each field, phenomena such as a decrease in the resolution (vertical scanning direction) of the displayed video and the collapse of a picture occur. Instead, the display quality can be improved.

In this case, as in the liquid crystal display device according to the third aspect of the present invention, the scanning means sets the number of the scanning lines to be simultaneously scanned to be constant without thinning out the video input signal. A scanning number constant pattern and a scanning number changing pattern for changing the number of scanning lines to be simultaneously scanned in accordance with a predetermined pattern are alternately set at a predetermined cycle, and the video driving unit sets the scanning number set by the scanning unit to one. A polarity inversion pattern for inverting the polarity of the video input signal is set according to the constant pattern and the scan number change pattern, and when inverting the polarity of the video input signal according to the scan number change pattern, the same polarity before inversion is used. The display elements may be AC-driven by additionally setting a polarity video input signal.

According to the liquid crystal display device of the third aspect of the present invention, the scanning means does not thin out the video input signal and sets the number of scanning lines to be simultaneously scanned at a constant scanning number pattern. And a scanning number changing pattern for changing the number of scanning lines to be simultaneously scanned in accordance with a predetermined pattern are alternately set in a predetermined cycle. In the video driving means, the scanning number constant pattern and the scanning number set by the scanning means are set. A polarity inversion pattern for inverting the polarity of the video input signal is set according to the change pattern, and when inverting the polarity of the video input signal according to the scan number change pattern, a video input signal of the same polarity before inversion is set. Are additionally set, and the display elements are AC driven.

In this case, as in the method of driving a liquid crystal display device according to the present invention, the number of scanning lines for simultaneously scanning is set constant without thinning out the video input signal. A constant pattern and a scanning number changing pattern for changing the number of scanning lines to be simultaneously scanned in accordance with a predetermined pattern are alternately set at a predetermined cycle, and according to the set scanning number constant pattern and the scanning number changing pattern, Setting a polarity inversion pattern for inverting the polarity of the video input signal, and when inverting the polarity of the video input signal according to the scan number change pattern, additionally set the video input signal of the same polarity before inversion and Each display element may be AC driven.

According to the driving method of the liquid crystal display device according to the sixth aspect, the scanning number constant pattern for setting the number of scanning lines for simultaneous scanning to be constant without thinning out the video input signal, and A scanning number changing pattern for changing the number of scanning lines to be scanned according to a predetermined pattern is alternately set at a predetermined period, and the polarity of the video input signal is inverted according to the set scanning number constant pattern and the set scanning number changing pattern. When the polarity inversion pattern to be inverted is set, and the polarity of the video input signal is inverted according to the scan number change pattern, the video input signal of the same polarity before the inversion is additionally set, and the display elements are driven by AC. Is done.

Therefore, without thinning out the video input signal,
A state in which the number of simultaneous scans is constant and a state in which the number of simultaneous scans is changed are alternately set for each field. Lower the resolution,
The display quality of an image can be reliably improved without causing a collapse of a picture or a phenomenon such as flicker.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIGS. 1 to 8 are views showing a first embodiment of a liquid crystal display device to which the present invention is applied.

First, the configuration will be described.

FIG. 1 is a diagram showing a circuit configuration of a main part of a liquid crystal display device 10 according to the first embodiment.

In FIG. 1, the liquid crystal display device 10
Non-inverting amplifier Amp1 and inverting amplifier Amp2 for amplifying a video signal, switches SW1 and SW2 switched and driven by a select signal, and switches SW1 and SW
2. Gate driver 12 and source drivers A13, B
A timing generator 11 for generating each control signal for controlling each operation timing and drive timing of 14;
A gate driver 12 for driving and controlling the scanning lines of the liquid crystal display panel 15, source drivers A13 and B14 for driving and controlling the signal lines of the liquid crystal display panel 15, and an image which is driven and controlled by the gate driver 12 and the source drivers A13 and B14. And a liquid crystal display panel 15 for displaying.

The non-inverting amplifier Amp1 non-inverts and amplifies the input video signal and outputs a video 1 signal, and the inverting amplifier Amp2 inverts and amplifies the input video signal and outputs a video 2 signal.

The switches SW1 and SW2 are controlled to be switched by a select signal input from the timing generator 11, and select either the video 1 signal input from the non-inverting amplifier Amp1 or the video 2 signal input from the inverting amplifier Amp2. Then, the selected video 1 signal or video 2 signal is output to the source driver A13 and the source driver B14.

The timing generator 11 generates a select signal for controlling switching of the switches SW1 and SW2, outputs the select signal to the switches SW1 and SW2, generates various clock signals for controlling the operation of the gate driver 12, and gates the gate control signal. It outputs to the driver 12 and various control signals for controlling the operation of the source drivers A13 and B14, and outputs the source A control signal and the source B control signal to the source drivers A13 and B14.

As shown in FIG. 2, the gate driver 12 includes flip-flops F1 to F4 and an output buffer B1.
To B4, and flip-flops F1 to F4
The output buffer B sequentially shifts the gate start signal GST by the gate clock signal GCK among the gate control signals input from the timing generator 11.
1 to B4, and the output buffers B1 to B4 output the flip-flops F1 to F4 at the respective output timings set by the output enable signals GOE1 and GOE2 among the gate control signals input from the timing generator 11.
The gate electrodes X1 to X4 (scan lines H1 to H4) of the liquid crystal display panel 15 are sequentially driven by the gate start signal GST input from F4, and the source electrodes S1 to S4
Are stored in the liquid crystal element.

Although the circuit configuration of the gate driver shown in FIG. 2 shows only four circuits corresponding to the gate electrodes X1 to X4 of the liquid crystal display panel 15, it is actually formed on the liquid crystal display panel 15. Needless to say, the circuit has the same number of circuits as the gate electrodes X1 to Xn.

The source driver A13 includes an odd-numbered row of source electrodes of the liquid crystal display panel 15 (S1, S3, S5, S7,
..), The source driver B14 has even-numbered columns (S2, S2).
, S6, S8,...), And video input from the switches SW1, SW2 at timing set by the source A control signal and the source B control signal input from the timing generator 11. One signal and two video signals are output to the source electrodes S1 to Sn of the liquid crystal display panel 15.

Next, the operation of the first embodiment will be described.

Before describing the liquid crystal drive control operation by the liquid crystal display device 10 of the first embodiment, a conventional liquid crystal drive control method according to the present liquid crystal drive control method will be described.

The liquid crystal driving method in which flicker does not occur as in the conventional polarity inversion driving shown in FIGS. 16 and 17 has been described. However, as shown in FIG. 3, flicker is generated by inverting the polarity for each column. There is also a column inversion driving method that does not perform this. However, in this column inversion driving method, a V sag easily occurs in a pulse waveform of a video signal, and when the V sag occurs, for example, a problem occurs in that luminance changes between upper and lower portions of a liquid crystal display screen.

Therefore, in the liquid crystal display device 10 of the first embodiment, a liquid crystal driving method as shown in FIG. 4 is obtained by combining the column inversion driving method and the line inversion driving method. In the driving example shown in FIG. 4, the polarity of the video signal is inverted every four scanning lines, and when the field changes from an odd field to an even field, the polarity is inverted in order to complement the interlaced scanning lines by pair line driving. The timing is shifted by one scanning line. The polarity is also inverted for each column of the source electrodes S1, S2, S3... S8.

Next, FIG. 5 is a diagram showing the change in the polarity of the video signal in the time axis direction for the column of the source electrode S1 in FIG. 4. Referring to FIG. 5, the scanning lines H2, H3, H4,.
Polarity changes at H6, H7, and H8 are driven by the pulse waveform of the video signal without flicker (FIG. 6) (same as the conventional FIG. 17). That is, the polarities of the scan lines H2, H3, H4, H6, H7, and H8 are inverted for each of the odd and even fields, but the polarities of the scan lines H1, H5, and H9 of FIG. Therefore, a DC voltage is applied to the liquid crystal elements corresponding to the scanning lines H1, H5, and H9.
Since the applied state of the DC voltage impairs the image quality,
The scanning lines H1, H5, and H9 to which the voltage is applied are driven so as to thin out images. That is, the transfer operation of the gate drive 12 is stopped for the scan lines H1, H5, and H9, and the charging operation of the video signal of the source driver A13 corresponding to the odd columns is also stopped.

Actually, if the scanning lines are thinned out by (1/4) H, the display image quality is affected. Therefore, the scanning lines by (1/32) H or (1/64) H at which the V sag does not occur. To thin out. That is, the state where the polarity of the video signal is inverted every scanning line 4H in FIG. 4 is inverted every scanning line 32H or 64H.

Next, a liquid crystal drive control operation performed by combining the column inversion drive method and the line inversion drive method performed in the liquid crystal display device 10 will be described with reference to a timing chart of signals of respective parts shown in FIG.

FIGS. 7 (a) to 7 (d) and (m) to (p)
An output enable signal G input as a gate control signal from the timing generator 11 to the gate driver 12
OE1, GOE2, a gate clock signal GCK and a gate start signal GST are shown in FIGS.
(Q) to (v) show gate drive signals output to the gate electrodes X1 to X6 of the liquid crystal display panel 15 by these gate control signals, and (k) and (l) show timing generators. 11 to switches SW1, SW2
Shows the select signal output. FIG. 7 is a timing chart showing the operation states of these signals separately for odd fields and even fields.

The timing generator 11 starts control of each part in the liquid crystal display device 10 in response to an instruction from a control unit (not shown), not shown, and switches SW1 and SW
2. Gate driver 12 and source drivers A13, B
Each control for 14 is started. Gate driver 12
When the gate clock signal GCK of FIG. 7C or FIG. 7O is input from the timing generator 11 to the flip-flops F1 to F4 of FIG. ) Or the gate start signal GST shown in FIG. 7 (p) is shifted and output to the output buffers B1 to B4.
Alternatively, the output enable signal GOE1 shown in FIG. 11 (m), and the output enable signal GOE shown in FIG. 10 (b) or (n).
When E2 is at the “Lo” level, the output buffers B1 to B
4 can be output, and gate drive signals X1 to X6 shown in FIGS. 9E to 9K or FIGS. 10Q to 10V are output to the gate electrodes X1 to X6 of the liquid crystal display panel 15. Is done.

At this time, in synchronization with the respective drive timings of the gate electrodes X1 to X6, the timing generator 11 inverts the polarity of the select signal shown in FIGS. ,
SW2 is switched so that the video 1 signal generated by the non-inverting amplifier Amp1 or the video 2 signal generated by the inverting amplifier Amp2 is output to the source driver A13,
Output to the source driver B14. Then, a video 1 signal or a video 2 signal is output to the source electrodes S1 to Sn of the liquid crystal display panel 15 by the source driver A13 and the source driver B14 to display an image.

The operation of each field shown in FIG. 7 will be described in detail. First, when the gate start signal GST is output from the timing generator 11 during the drive control period of the odd field ("Lo" → "H")
i "), the output enable signals GOE1 and GOE2 are changed from" Lo "to" Hi "as shown in FIGS. 7 (a) and 7 (b).
At the rising timing, two pulse signals of the gate clock signal GCK shown in FIG. 10C are continuously output, and the output enable signal GOE1 is changed from “Hi” to “Hi” by the second gate clock signal. “Lo” is set.

At this time, when the gate start signal GST is shifted in the scanning direction by the flip-flops F1 and F2 and transmitted to the output buffers B1 and B2, the output buffer B1 is in the "Lo" state when the output enable signal GOE1 is in the "Lo" state. When the output is enabled, the gate drive signal X1 in FIG. 9E is output to the gate electrode X1 of the liquid crystal display panel 15 (“Lo” → “Hi”), and the gate electrode X1 is driven. However, at this time, the output enable signal GOE2
Is in the "Hi" state, the output buffer B2 is set to the output disabled state, and the output buffer B2 does not output the gate drive signal X2 to the gate electrode X2 (see the broken line in FIG. 7F).

After the drive period for one scan line for the gate electrode X1 has elapsed, the output enable signal GOE1 is set again from "Lo" to "Hi", as shown in FIG. Gate drive signal X1
Is stopped (“Hi” → “Lo”), the gate clock signal GCK shown in FIG. 9C is output, and both the output enable signals GOE1 and GOE2 are changed from “Hi” to “Lo”.
And the output enable signals GOE1, GOE
The “Lo” state of No. 2 is continued for the driving period for one scanning line. At this time, when the gate start signal GST is shifted in the scanning direction by the flip-flops F2 and F3 and transmitted to the output buffers B2 and B3, the output buffers B2 and B3 are output.
3 is set in an output enabled state, and FIG.
As shown in (g), the gate drive signals X2 and X3 are simultaneously output to the gate electrodes X2 and X3 (“Lo” → “H”).
i ″), the gate electrodes X2 and X3 are simultaneously driven.

After the drive period for one scan line for the gate electrodes X2 and X3 has elapsed, the output enable signals GOE1 and GOE2 in FIGS. 7A and 7B are changed from "Lo" to "H".
i ”and the gate drive signals X2 and X3 are stopped at the rising timing (“ Hi ”→“ L ”).
o "), two successive gate clock signals GCK shown in FIG. 3C are output, and the output enable signal GOE2 is changed from" Hi "to" L "by the second gate clock signal.
o ”.

At this time, when the gate start signal GST is shifted in the scanning direction by the flip-flops F4 and F5 and transmitted to the output buffers B4 and B5, the output buffer B4 is in the "Lo" state because the output enable signal GOE2 is in the "Lo" state. When the output is enabled, the gate drive signal X4 shown in FIG. 9H is output to the gate electrode X4 of the liquid crystal display panel 15 (“Lo” → “Hi”), and the gate electrode X4 is driven. However, at this time, the output enable signal GOE1
Is in the "Hi" state, the output buffer B5 is set to the output disabled state, and the gate drive signal X5 is not output from the output buffer B5 to the gate electrode X5 (see the broken line in FIG. 7I).

After the drive period of one scan line for the gate electrode X4 has elapsed, the output enable signal GOE2 is set from "Lo" to "Hi" again, as shown in FIG. Gate drive signal X4
Is stopped (“Hi” → “Lo”), the gate clock signal GCK shown in FIG. 9C is output, and both the output enable signals GOE1 and GOE2 are changed from “Hi” to “Lo”.
And the output enable signals GOE1, GOE
The “Lo” state of No. 2 is continued for the driving period for one scanning line. At this time, when the gate start signal GST is shifted in the scanning direction by the flip-flops F5 and F6 and transmitted to the output buffers B5 and B6, the output buffers B5 and B6 are output.
6 is set in the output enabled state, and therefore, FIG.
As shown in (j), the gate drive signals X5 and X6 are simultaneously output to the gate electrodes X5 and X6 (“Lo” → “H”).
i ″), the gate electrodes X5 and X6 are simultaneously driven.

Further, during the driving period of the gate electrodes X1 to X6 in the odd field, the switches SW1 and SW2 are switched every two scanning periods by the select signal shown in FIG. The video signals 1 and 2 are alternately supplied to the drivers A13 and B14. That is, the polarities of the video signals supplied to the odd and even columns of the source electrodes S1 to Sn of the liquid crystal display panel 15 are inverted every two scanning lines.

The drive control patterns of the gate electrodes X1 to Xn in the above odd fields are the same in the even fields of FIG. 7, and the description of the operation is omitted.

By the above gate control operation, the gate electrode X
FIG. 8 shows a change in the scanning lines H1 to Hn assigned to 1 to Xn as viewed on the time axis.

As described above, in the liquid crystal display device 10 of the first embodiment, the polarity of the video signal applied to the source electrodes S1 to Sn is determined by combining column inversion driving, line inversion driving, and pair line driving. When the conventional non-interlace drive control is performed, one scan line is thinned out at the timing when the polarity of the video signal is line-inverted by the gate driver 12.
Video display without flicker can be performed without adding an external circuit such as a memory for accumulating interlaced video signals.

Therefore, the display quality can be improved without increasing the system cost of the liquid crystal display device 10.

In the liquid crystal display device 10 of the first embodiment, the line inversion is performed every four scanning lines, and the driving of the liquid crystal display panel 15 is controlled by thinning out the scanning lines at quarter intervals. However, 6, 8, 10 ...
Line inversion is performed every 60 and 62 scanning lines,
/ 8, 1/10... The scanning lines may be thinned out at intervals of 1/60, 1/62. For example, in consideration of the relationship with the V sag generated in the video signal, for example, the video signal of the NTSC system is used. In the case of (1), it is considered that it is better to invert the polarity every 62 scan lines and thin out the scan lines at 1/62 intervals.

That is, in the liquid crystal display device 10 according to the first embodiment, the timing for inverting the lines and the timing for thinning out the scanning lines can be appropriately set in accordance with the scanning frequency of the input video signal. .

(Second Embodiment) In the liquid crystal drive control of the liquid crystal display device 10 according to the first embodiment, as shown in FIG. 5, the scan lines H1 to H4 and H9 and H10 are applied to the odd fields as shown in FIG. The polarity of the corresponding video signal is "+",
The polarities of the video signals corresponding to the scan lines H5 to H8 become "-", and the scan lines H1 and H
The same drive pattern in which the polarity of the video signal corresponding to 6 to H9 is "+" and the polarity of the video signal corresponding to scan lines H2 to H5 and H10 is "-" has been repeated for each field. However, in the case of this driving pattern, as described in the first embodiment, the DC voltage is applied to the pixels corresponding to the scanning lines H1, H5, and H9, and the timing for inverting the polarity of the line is performed. It is necessary to perform drive control for thinning out the scanning lines.

In the liquid crystal display device according to the second embodiment,
Liquid crystal drive control is performed to shift the timing of line inversion of the polarity of the video signal for each field so that a DC voltage is not applied to pixels on a specific scan line. The configuration of the liquid crystal display device according to the second embodiment is the same as the liquid crystal display device 10 and the gate driver 12 shown in FIGS. 1 and 2 of the first embodiment. Description is omitted.

FIG. 9 shows an example of a drive pattern of the liquid crystal drive control executed by the liquid crystal display device of the second embodiment. FIG. 9 is a diagram showing the polarity change of the video signal in the column of the source electrode S1 as viewed in the time axis direction, similarly to FIG. In the example of the drive pattern shown in FIG. 9, the timing of line inversion of the polarity of the video signal is moved for each scan line for each field, and in the case of this drive pattern, the same pixel Although the polarity becomes the same (the part surrounded by the ellipse in the figure), since the polarity of the other pixels is inverted for each field,
No DC voltage is applied.

FIG. 9 is a diagram showing the change in the polarity of the video signal in the column of the source electrode S1 as viewed from the time axis direction. FIG. 9 shows the change in the polarity of the video signal in the column of the source electrode S2 as viewed in the time axis direction. Since the polarity inversion and line inversion between the scanning lines are completely opposite to the polarity change shown in FIG. 9, the polarity of the pixel is always inverted for each field.

The drive pattern shown in FIG. 9 is obtained by developing a drive pattern of the conventional pair line drive shown in FIG. 20 and adding a column inversion drive pattern.
Therefore, it is only necessary to add the column inversion drive to the pair line drive for every two scan lines in FIG. 20 (because the polarity is inverted for each field in the column direction to offset the DC voltage), but the pixel When attention is paid to the change in the polarity of the video signal in units, the same polarity continues for every two fields in all pixels as in the portion indicated by the ellipse in FIG.
Some flickers like lines occur.

Therefore, in order to suppress the occurrence of such flicker, it is effective to use a drive pattern shown in FIG. 9 for shifting the timing of inverting the polarity of the video signal line by line for each field. Further, the polarity inversion is not limited to every eight scanning lines as shown in FIG. 9, but as described in the first embodiment, the scanning line interval at which the polarity is inverted is set to every thirty scanning lines, every forty scanning lines, or to sixty scanning lines.
Reversing the polarity for each scanning line is more effective in suppressing the occurrence of flicker.

As described above, in the liquid crystal display device of the second embodiment, the drive for moving the timing of inverting the polarity of the video signal line by line for each field without skipping the scanning lines. Since the pattern is formed, the scanning lines are not thinned out, and the display image quality can be improved without causing a phenomenon such as a decrease in the resolution (vertical scanning direction) of the displayed image or the collapse of the picture.

(Third Embodiment) In the third embodiment, as shown in FIG. 5 of the first embodiment, the same drive pattern is repeated and the polarity is always the same. In order to prevent the DC voltage from being applied to the pixels of the scanning line, as shown in FIG. 10, the gate electrodes are simultaneously selected for three scanning lines at the scanning timing when the polarity changes due to the line inversion, and one scanning line is selected. By adding a drive pattern that selects only the gate electrode described above, the drive pattern is driven so that flicker does not occur, as in the first embodiment.

The configuration of the liquid crystal display device of the third embodiment is the same as that of the liquid crystal display device 10 and the gate driver 12 shown in FIGS. 1 and 2 of the first embodiment. Its illustration and description are omitted.

FIG. 10 is a diagram showing a change in the polarity of the video signal in the column of the source electrode S1 as viewed in the time axis direction, similarly to FIG. In the example of the driving pattern shown in FIG. 10, the odd field performs pair line driving in which the polarity of the video signal is inverted every eight scanning lines, and scans the scanning lines H1 and H3 in the even fields at the same scanning driving timing as the scanning line H2. Three scanning lines are simultaneously driven, and the scanning line H8 is driven independently. That is, in the even field, the driving pattern of the number of scanning lines to be driven simultaneously is
Three, two, two, one, three, two, two, one, ...
・ ・The driving pattern of the scanning line in the even-numbered field corresponds to the gate driving signal X shown in FIG.
1 to X13... Are controlled by driving timings in the timing charts.

The pixel positions circled in FIG. 10 are the polarities of the video signal input to the source electrode S1 at the scan line position that is originally driven. For example, the video position set by the scan line H2 of the even field is set. The polarity of the signal is also used in the scanning lines H1 and H3 that are simultaneously driven,
Further, the polarity of the video signal set on the scan line H8 which is scanned alone is not used in the next scan line H9. Such a driving pattern is a driving method in which a video signal having the same polarity for one scanning line is added to the case where one scanning line is thinned out in the first embodiment.

Therefore, in the driving pattern of FIG.
A video signal of the same polarity is partially applied for every two scanning lines, but there is no problem that the resolution is reduced or the picture is broken. As in the first and second embodiments, the column inversion of the video signal polarity between the scanning lines when the column of the source electrode S2 is viewed from the time axis direction is completely opposite to the polarity change in FIG. Because it changes polarity,
The polarity of a pixel is always inverted for each field. Therefore, the column inversion of the video signal polarity is performed not only every eight scan lines but also every sixteen scan lines, every thirty scan lines, or every sixty scan lines.
It is possible to invert the polarity every 0 scanning lines, and as in the above-described embodiments, only the scanning line in which the polarity of the video signal is inverted only lowers the resolution by 2 lines. It does not affect.

As described above, in the liquid crystal display device according to the present embodiment, the resolution is reduced or the picture is not displayed by driving with the driving pattern of applying the video signal of the same polarity for one scanning line without skipping the scanning lines. An image display free from crushing and flickering can be displayed on the liquid crystal display panel.

In the third embodiment, the case where the driving pattern of the odd field is set to the regular driving and the driving pattern of the even field is set to the irregular driving has been described. May be set in reverse.

[0076]

According to the liquid crystal display device of the first aspect and the driving method of the liquid crystal display device of the fourth aspect, the polarity of the video input signal input to the signal line is set, for example, by column inversion driving, line inversion, When performing a non-interlaced drive control according to the related art, a drive is performed in combination with the inversion drive and the pair line drive, and one scan line is thinned out at the timing when the polarity of the video input signal is inverted. Video display without flicker can be performed without adding an external circuit such as a memory for storing input signals. As a result, the display image quality can be improved without increasing the system cost of the liquid crystal display device.

According to the liquid crystal display device of the second aspect and the method of driving the liquid crystal display device of the fifth aspect, for example, the timing of line inversion of the polarity of the video input signal without thinning out the video input signal. Is performed for each scanning line for each field, thereby improving the display image quality without lowering the resolution of the display image (vertical scanning direction) or causing a phenomenon such as image collapse. .

According to the liquid crystal display device according to the third aspect of the present invention and the driving method of the liquid crystal display device according to the sixth aspect of the present invention, the state where the number of simultaneous scans is constant in each field and the state where the number of simultaneous scans is constant without thinning the video input signal When the number of scans is changed alternately, and when the number of simultaneous scans is changed, the resolution is reduced or the picture is broken by driving with a drive pattern that applies a video input signal of the same polarity for one scan line during polarity reversal. Without letting
In addition, the display quality of an image can be reliably improved without causing a phenomenon such as flicker.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a circuit of the gate driver of FIG. 1;

FIG. 3 is a diagram showing a polarity inversion state of a video signal in a liquid crystal display panel by a conventional column inversion drive.

FIG. 4 is a diagram showing a liquid crystal driving pattern obtained by combining the column inversion driving method and the line inversion driving method according to the first embodiment.

5 is a diagram showing a state of column inversion and line inversion of the polarity of a video signal in the column of the source electrode S1 in FIG. 4 as viewed from the time axis direction.

6 is a timing chart of a video signal for realizing the drive pattern of column inversion and line inversion of FIG. 5;

FIG. 7 is a timing chart of signals of respective units controlled in the liquid crystal drive control of the liquid crystal display device according to the first embodiment.

FIG. 8 is a diagram showing a change in a scanning line assigned to a gate electrode by the liquid crystal drive control of FIG. 7;

FIG. 9 is a diagram illustrating a relationship between a scanning line controlled for each field and a video signal polarity in liquid crystal drive control of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a relationship between scanning lines controlled for each field and video signal polarities in liquid crystal drive control of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 11 is a timing chart of a driving signal for realizing the driving pattern of FIG. 10;

FIG. 12 is a cross-sectional view of a conventional liquid crystal display panel.

13 is a diagram showing an example of a signal applied to each electrode of the liquid crystal display panel of FIG.

FIG. 14 is a diagram showing a conventional interlaced driven video signal.

FIG. 15 is a timing chart of a video signal for realizing the interlace driving in FIG. 14;

FIG. 16 is a diagram showing a polarity inversion state between scanning lines when a conventional video signal is driven for polarity inversion.

FIG. 17 is a timing chart of a video signal for realizing the polarity inversion drive of FIG. 16;

FIG. 18 is a diagram showing a polarity inversion state of a video signal during conventional pair line driving.

19 is a diagram of a change in polarity of a video signal applied to a source electrode during pair line driving in FIG. 18 viewed macroscopically on a time axis.

20 is a timing chart of a video signal for realizing the pair line driving of FIG. 18;

[Explanation of symbols]

 Reference Signs List 10 liquid crystal display device 11 timing generator 12 gate driver 13 source driver A 14 source driver B 15 liquid crystal display panel Amp1 non-inverting amplifier Amp2 inverting amplifier B1 to B4 output buffer SW1, SW2 switch

Claims (6)

[Claims] A liquid crystal panel having a plurality of signal lines and a plurality of scanning lines arranged in a matrix, and a display element connected to each intersection of the signal lines and the scanning lines; and a scanning timing according to a video input signal. A scanning unit that scans the plurality of scanning lines, and a video drive that AC-drives each of the display elements while alternately inverting the polarity of a video input signal input to each of the signal lines at predetermined intervals. Means, wherein the scanning means simultaneously scans a predetermined number of adjacent scanning lines among the plurality of scanning lines based on the scanning timing of the video input signal, and performs the simultaneous scanning. The video input signal is thinned out at a rate of one scanning line for each number of scanning lines, and the video driving means reverses the polarity of the video input signal for each number of scanning lines simultaneously scanned by the scanning means. A liquid crystal display, comprising: setting a pattern, changing the polarity inversion pattern at a timing at which the video input signal is thinned, and inverting the polarity inversion pattern at predetermined intervals to drive each of the display elements by AC. Display device. 2. The system according to claim 1, wherein the scanning unit simultaneously scans a predetermined number of adjacent scanning lines among the plurality of scanning lines based on a scanning timing of the video input signal without thinning the video input signal. The image driving means sets a polarity inversion pattern for inverting the polarity of the video input signal for each of the number of scanning lines simultaneously scanned by the scanning means, and sets the polarity inversion pattern to the scanning lines simultaneously scanned at a predetermined period. 2. The liquid crystal display device according to claim 1, wherein the display elements are AC-driven by sequentially moving the display elements by a predetermined number of scanning lines. 3. The scanning means according to claim 1, wherein said scanning means is configured to set the number of scanning lines to be simultaneously scanned to be constant without thinning out said video input signal, and to determine the number of scanning lines to be simultaneously scanned according to a predetermined pattern. The scanning number changing pattern to be changed is alternately set at a predetermined cycle, and the video driving unit inverts the polarity of the video input signal according to the scanning number constant pattern and the scanning number changing pattern set by the scanning unit. When the polarity inversion pattern to be set is set and the polarity of the video input signal is inverted according to the scan number change pattern, the video input signal having the same polarity before the inversion is additionally set and the display elements are AC driven. The liquid crystal display device according to claim 1, wherein: 4. A plurality of signal lines and a plurality of scanning lines are arranged in a matrix, a display element is connected to each intersection of the signal lines and the scanning lines, and the plurality of signal lines and the plurality of scanning lines are connected at a scanning timing according to a video input signal. The method of driving a liquid crystal display device in which each of the display elements is AC-driven while scanning the scanning lines and alternately inverting the video input signal input to each of the signal lines positively and negatively at predetermined intervals. A predetermined number of adjacent scanning lines among the plurality of scanning lines are simultaneously scanned based on the scanning timing of the video input signal, and the video input signal is scanned at a rate of one scanning line for each of the simultaneously scanned scanning lines. A polarity inversion pattern for inverting the polarity of the video input signal is set for each of the number of simultaneously scanned scanning lines, and a timing at which the video input signal is thinned out from the polarity inversion pattern With changing a driving method of a liquid crystal display device, characterized in that by inverting the polarity inversion pattern for each predetermined cycle AC driving the respective display elements. 5. A method according to claim 1, wherein a predetermined number of adjacent scanning lines of said plurality of scanning lines are simultaneously scanned based on a scanning timing of said video input signals without thinning out said video input signals. A polarity inversion pattern for inverting the polarity of the video input signal is set for each number of lines, and the polarity inversion pattern is sequentially moved by a predetermined number of scanning lines of the number of simultaneously scanned scanning lines in a predetermined period. 5. The method according to claim 4, wherein each of the display elements is driven by an alternating current. 6. A scanning number constant pattern for setting the number of scanning lines to be simultaneously scanned constant without thinning the video input signal, and a scanning number change for changing the number of scanning lines to be simultaneously scanned according to a predetermined pattern. The pattern and the pattern are alternately set at a predetermined cycle, and a polarity inversion pattern for inverting the polarity of the video input signal is set according to the set scan number constant pattern and the scan number change pattern. 5. The liquid crystal display device according to claim 4, wherein when inverting the polarity of the video input signal, a video input signal having the same polarity before the inversion is additionally set and the display elements are AC-driven. Drive method.