JPH0854600A - Driving method for liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a driving method which can depress the occurrence of luminance irregularity in liquid crystal display devices irrespective of the display pattern. CONSTITUTION:In the voltage impressed on the scanning electrodes, non-scanning voltage periods (quiescent period) are placed between the scanning pulses (a) and (b), and between the scanning pulses (b) and (c). And as seen in (d), (e), (f), the voltage impressed on the signal electrodes gives the drive waveforms which have quiescent periods where the potential is the same as the non- scanning voltage in the scanning electrode drive irrespective of displayed data. By this, the switching times (frequency component) of each signal voltage waveform are the same and luminance irregularity is mitigated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a matrix type liquid crystal display device.

[0002]

2. Description of the Related Art As a conventional driving method of a matrix type liquid crystal display device, a voltage averaging method is generally used in which an effective voltage applied during a non-selection period is constant (for example, Japanese Patent Laid-Open No. Sho 50-50).
No. 68419). For example, a case where the pattern of FIG. 15 is displayed will be described. In FIG. 15, 1, 2,
3 is a pixel, 100, 110, 120, 130, 140,
Reference numerals 150 and 160 denote scanning electrodes, and reference numerals 200, 210, and 220 denote signal electrodes. In the drawing, the shaded portions at the intersections (pixels) of the scan electrodes and the signal electrodes indicate black display, and the portions without hatching indicate white display. FIG. 16 shows an equivalent circuit of a portion related to the scan electrode 100 of FIG. FIG. 17 is a waveform diagram of applied voltage in the conventional voltage averaging method.
15B and 15C are scan electrodes 100 and 1 of FIG. 15, respectively.
Waveforms of voltage applied to the scanning electrodes applied to the electrodes 10 and 120, (d), (e), and (f) of FIG.
FIG. 6 is a waveform diagram of voltage applied to signal electrodes applied to 10, 220.

Each potential difference at the intersection of the scan electrode and the signal electrode is applied to each pixel. ON / OFF of the pixel is determined by the voltage applied to the signal electrode, and turned on by the difference between this and the voltage pulse applied to the scan electrode.
/ OFF Takes the effective value.

[0004]

In this conventional voltage averaging method, the signal electrode applied voltage waveform differs depending on the display pattern as shown in FIGS. 17 (d), (e) and (f). . Further, the voltage actually applied to each pixel is complicatedly distorted by these different signal electrode applied voltage waveforms due to the influence of the electrode resistance of the panel and the liquid crystal capacitance. Therefore, there is a problem that an effective voltage different from the effective voltage to be applied is applied, resulting in display unevenness and the image quality is significantly deteriorated.

Next, the contents will be described. As shown in the equivalent circuit of FIG. 16, the scan voltages at the nodes 101, 102, and 103 are distorted when the signal voltage changes due to the resistance R of the scan electrode 100 and the pixel capacitance C, as shown in FIG. Here, the resistance between the nodes 101 and 103 is smaller than the resistance between the nodes 99 and 101, and the potentials of 101, 102, and 103 are substantially equal. Further, the nodes 201, 211, 221 are shown in FIG.
As shown in (c) and (d), the waveform r is distorted by the resistance r of the signal electrode and the pixel capacitance C. For this reason,
The voltage applied to the pixels 1, 2, and 3 of FIG.
(E), (f), (g), which have to take the same ON effective value, actually have different effective values, which causes uneven brightness. This phenomenon becomes more remarkable as the drive frequency becomes higher and the voltage resistance increases as the display capacity increases.

In order to calculate these distortion amounts, assuming that the distortion amount of the scanning voltage and the distortion amount of the signal voltage due to the change of one signal voltage are each one unit, the distortion amount differs depending on each display data. Pixel voltage in two fields in the selection period ta (scanning side applied voltage-signal side applied voltage)
The distortion amounts are −28, −20, and −8 (distortion amount maximum 20), and the effective voltages applied to the pixels 1, 2, and 3 which should originally have the same brightness are different, and uneven brightness occurs.

In addition, there is a method of detecting the distortion voltage of the scanning electrode in order to remove the distortion amount of the scanning voltage and feeding back the correction voltage to the scanning voltage based on the detected distortion amount of the scanning voltage (for example, , Japanese Patent Application No. 62-74607, "New driving method for reducing crosstalk unevenness of simple matrix LCD", IEICE Technical Bulletin 199
2, 41). However, although this method can remove the brightness unevenness caused by the distortion of the scanning voltage, it cannot completely remove the brightness unevenness caused by the difference in the number of switching of each signal voltage waveform (frequency component difference). Next, in order to equalize the difference in the number of times the signal voltage waveforms are switched, there is a method of inverting the polarity of all driving in an integral multiple of one scanning period (a period in which one scanning line is selected) (for example, (Kaisho 60-19195). However, in this method, scanning line flicker occurs due to the polarity inversion cycle that has been set, and when the polarity inversion cycle is used to avoid these, the difference in the number of times the signal voltage waveform switches is not uniform depending on the display pattern, and brightness unevenness also occurs. It was a result.

Further, consider the case where the halftone display as shown in FIG. 19 is performed. In FIG. 19, portions corresponding to those in FIG. 15 are denoted by the same reference numerals, and in the drawing, solid line shaded portions at intersections (pixels) of scan electrodes and signal electrodes are black, dotted shaded portions are halftone display. Areas without diagonal lines show white display.
FIG. 20 is an applied voltage waveform diagram for displaying the pattern shown in FIG. 19, and (a), (b), and (c) are scan electrode applied voltage waveform diagrams applied to the scan electrodes 100, 110, and 120, respectively. (D), (e), (f) are signal electrode applied voltage waveform diagrams applied to the signal electrodes 200, 210, 220, respectively. In this case, the voltage waveforms on the scanning electrode side of the pixels 1, 2 and 3 are shown in FIG. 21A, and the voltage waveforms on the signal electrode side of the pixels 1, 2 and 3 are shown in FIGS. 21B, 21C and 21D. ), The voltage waveforms applied to the pixels 1, 2 and 3 are shown in FIG.
Shown in (f) and (g).

As shown in FIG. 20, in the pulse width modulation method in which halftone is displayed by switching ON / OFF data according to a gradation level within one scanning period, a signal waveform is generated by the gradation data during one scanning period. There are times when switching occurs and times when switching does not occur, and due to the difference in frequency component due to this, as in the above case, the amount of voltage distortion in each pixel differs depending on the gradation pattern, resulting in uneven brightness.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a driving method of a liquid crystal display device capable of suppressing the occurrence of uneven brightness regardless of the display pattern.

[0011]

According to a first aspect of the present invention, there is provided a method of driving a liquid crystal display device, wherein a first scan pulse and a second scan pulse in a scan pulse sequentially applied to a scan electrode group are not provided between the first scan pulse and the second scan pulse. A scanning voltage period is provided, and the same voltage as the non-scanning voltage is applied to the signal electrode group during this non-scanning voltage period.

According to a second aspect of the present invention, there is provided a driving method of a liquid crystal display device, wherein the first scanning pulse is sequentially applied to the scanning electrode group.
The non-scanning voltage is applied to the signal electrode for a predetermined period spanning a first period for applying the second scanning pulse and a second period for applying the second scanning pulse subsequent to the first scanning pulse. It is characterized by applying to a group. The liquid crystal display driving method according to claim 3, wherein a non-scanning voltage period is provided between a first scanning pulse and a next second scanning pulse in the scanning pulse sequentially applied to the scanning electrode group, and the non-scanning voltage period is set. It is characterized in that the same voltage as the non-scanning voltage is applied to the signal electrode group in a predetermined period spanning the voltage period.

According to a fourth aspect of the present invention, there is provided a driving method of the liquid crystal display device according to the first, second or third aspect, in which a distortion voltage equal to the distortion voltage of the scanning electrodes due to a change in signal voltage is generated. The detection electrodes are provided on the second substrate provided with the scanning electrode group, and the voltage is corrected for the scanning electrode group based on the strain voltage generated in the detection electrode. According to a fifth aspect of the present invention, there is provided a liquid crystal display device driving method according to the first, second or third aspect, wherein the resistance per pixel in the power supply / final direction on the scanning electrode is 5Ω or less. It drives a display device.

According to a sixth aspect of the present invention, there is provided a method of driving a liquid crystal display device according to the first, second or third aspect, in which halftones are displayed by a pulse width modulation method and each of the scanning periods is performed. The same voltage as the non-scanning voltage is applied to the signal electrode group during a predetermined period. A method for driving a liquid crystal display device according to claim 7 is the method according to claim 1 or 2.
Alternatively, in the method for driving the liquid crystal display device according to the item 3, a detection electrode that generates a distortion voltage equivalent to the distortion voltage of the scanning electrode due to a change in signal voltage is provided on the second substrate provided with the scanning electrode group, and is generated on the detection electrode. Voltage correction is performed on the scanning electrode group based on the distorted voltage, halftone is displayed by the pulse width modulation method, and the same voltage as the non-scanning voltage is applied to the signal electrode group during a predetermined period in the middle of each scanning period. It is characterized by applying.

The driving method of the liquid crystal display device according to an eighth aspect is the driving method of the liquid crystal display device according to the first, second or third aspect, wherein the resistance per pixel on the scanning electrode in the power supply / final direction is 5Ω or less. The liquid crystal display device is driven to display halftones by the pulse width modulation method, and the same voltage as the non-scanning voltage is applied to the signal electrode group during a predetermined period in the middle of each scanning period. .

[0016]

There are two causes for uneven brightness caused by voltage distortion when driving a liquid crystal display device. One is the voltage distortion difference due to the switching frequency difference (frequency component difference) depending on the display pattern of each signal voltage waveform, and the other is the scanning voltage distortion due to the signal voltage change.

According to the driving method of the present invention, the voltage is applied to the scan electrode group between the first scan pulse and the second scan pulse or in the period when the first scan pulse and the second scan pulse are straddled. By applying the same voltage as the non-scanning voltage to the signal electrode group, the voltage distortion difference due to the switching frequency difference (frequency component difference) due to the signal voltage is made constant regardless of the display pattern, and brightness is maintained even in a large display capacity panel. It is possible to achieve high-quality display with less unevenness. Particularly, in the method of applying the same voltage as the non-scanning voltage applied to the scanning electrode group to the signal electrode group between the first scanning pulse and the second scanning pulse, the ON / OFF effective value ratio is made equal to that of the conventional one. Therefore, it is possible to perform display without brightness unevenness while maintaining the conventional contrast.

Further, a detection electrode for generating a strain voltage equivalent to the strain voltage of the scanning electrode due to the change of the signal voltage is provided,
The voltage of the signal electrode is corrected by correcting the voltage of the scanning electrode group based on the distortion voltage generated in the detection electrode, or by setting the resistance per pixel in the feeding / finding direction on the scanning electrode to 5Ω or less. It is possible to significantly reduce the amount of distortion of the voltage of the scanning electrode due to the change of the above. By simultaneously improving the above two causes, two synergistic effects appear, and it is possible to achieve higher quality display without brightness unevenness regardless of the display pattern. can do.

Further, by displaying a halftone by the pulse width modulation method and applying the same voltage as the non-scanning voltage to the signal electrode group in a predetermined period in the middle of each scanning period,
The number of times the signal voltage is switched in one scanning period is the same for any halftone data, and high-quality display with no brightness unevenness can be achieved regardless of any display pattern including halftone display.

[0020]

【Example】

(First Embodiment) A method of driving a liquid crystal display device according to a first embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are voltage waveform diagrams in a method of driving a liquid crystal display device according to a first embodiment of the present invention. (A), (b), and (c) of FIG. 1 are scan electrode 100 in FIG. , 110, and 120 are waveform diagrams of scan electrode applied voltage, and FIGS. 1D, 1E, and 1F are signal electrode applied voltage waveform diagrams applied to the signal electrodes 200, 210, and 220, respectively. Are applied with respective potential differences. 2A is a scan voltage waveform at the nodes 101, 102, and 103 of FIG. 16, and FIGS. 2B, 2C, and 2D are signal voltage waveforms at the nodes 201, 211, and 221 of FIG.
(E), (f), (g) show the voltage waveforms applied to the pixels 1, 2, 3 in FIG.

In this embodiment, as in the conventional example shown in FIGS. 17 and 18 and FIGS. 20 and 21, the polarity of the applied voltage is inverted every scanning cycle. That is, in the first one scanning cycle,
1A, 1B, and 1C, V0 is a reference voltage, V5 is a scanning voltage, and V1 is a non-scanning voltage.
In (d), (e), and (f), V0 is the reference voltage and V2 is the selection voltage. In the next one scanning cycle, in FIGS. 1A, 1B, and 1C, V5 is a reference voltage, V0 is a scanning voltage, and V4 is a non-scanning voltage.
In FIGS. 1D, 1E, and 1F, V5 is the reference voltage and V3 is the selection voltage. Therefore, in the first one scanning cycle and the next one scanning cycle, the polarities of all the voltages with respect to the reference voltage are inverted, and
As shown in (g), the voltage applied to the pixels 1, 2, and 3 is a complete AC signal in two scanning cycles.

Further, in this embodiment, as shown in FIGS. 1A, 1B, and 1C, the scanning electrode applied voltage is (b) between the scanning pulse of (a) and the scanning pulse of (b). ) Scanning pulse and (c) scanning pulse, non-scanning voltage (V1, V
The period (4) (pause period) is provided. As shown in FIGS. 1D, 1E, and 1F, the voltage applied to the signal electrode is once in a period between scan pulses and is not scanned by the scan electrode drive regardless of display data. A drive waveform having an idle period so as to have the same potential as the voltage is applied. As a result, the number of times of switching of each signal voltage waveform (frequency component) becomes equal, and uneven brightness is alleviated.

In the driving method of this embodiment, the scanning voltages at the nodes 101, 102 and 103 in FIG. 16 are shown in FIG.
As described above, the signal voltages at the nodes 201, 211, and 221 are as shown in FIGS. 2B, 2C, and 2D. Therefore, the voltage applied to the pixels 1, 2 and 3 is as shown in FIG.
It is distorted as in (f) and (g). Here, as in the conventional example, 1
Assuming that the distortion amount of the scanning voltage and the distortion amount of the signal voltage due to the change of the signal voltage for one time are one unit, the voltage distortion amounts in the two fields in the non-selection period ta in which the distortion amount is different depending on each display data are −11 respectively. ., -9.6, -8, and the difference in distortion amount in each pixel is smaller than that in the conventional example (maximum difference 3.1), so that the uneven brightness is also greatly improved.

Further, the driving method of this embodiment is different from the conventional driving method in that the voltage applied to the pixels 1, 2 and 3 is as shown in FIG.
As shown in (e), (f), and (g), the zero potential is only applied during the rest period. Therefore, the ON / OFF voltage effective value ratio can almost keep the effective value ratio in the conventional driving method, and the uneven brightness can be reduced while maintaining the conventional contrast.

As described above, in the driving method of this embodiment, the voltage distortion difference caused by the switching frequency difference (frequency component difference) depending on the display pattern of each signal voltage waveform is made constant regardless of the display pattern, and a large display capacity panel is obtained. Even in the case of “1”, it is possible to realize high-quality display with little unevenness in brightness. Regarding the pause period, the number of times the signal waveform is switched is uniform in any signal pattern even if there are only a few pause periods. Therefore, the effects of the present invention begin to appear, and uneven brightness can be improved. Further, in the pause period, the effect differs depending on how the driving waveform is rounded by the time constant determined by the resistance and capacitance of each signal line of the liquid crystal display device. Now, assuming that the signal electrode side potential applied to the pixel at the time of switching the drive waveform is 0% and the signal electrode side potential applied to the pixel in a steady state in which a sufficient time has elapsed after the waveform switching is 100%, the waveform switching is performed. After that, the signal electrode side potential applied to the pixel is 50
When the period until the time when the percentage changed to% was set as the rest period and the evaluation was performed using an actual panel, the effect was sufficiently observed. After the waveform is switched, by setting the period until the signal electrode side potential applied to the pixel becomes 100% or more as a rest period, the influence on the signal electrode side pixel voltage is Even when the drive corresponding to was performed, the values were equal, and almost no brightness unevenness was observed. Therefore, in the setting of the rest period, the effect of the present invention begins to appear by setting the rest period as much as possible, but the effect is improved by setting the period of 50% or more, and the period of 100% or more is set. By doing so, the effect becomes particularly good.

Further, in this embodiment, the liquid crystal display mode has a steep threshold characteristic in STN (Super-Twist).
In the d-Nematic mode, the effect can be particularly exerted. However, according to the driving method of the present invention until the fifth embodiment up to the first embodiment, the scanning electrode group is formed on the facing surface regardless of the display mode of the liquid crystal. As long as the liquid crystal display panel has a liquid crystal sandwiched between a pair of substrates having a signal electrode group, by using the driving method of the present invention in a liquid crystal display device using other modes, pixel driving voltage The uneven brightness can be improved. In this regard, for example, TN (Twisted-Nematic)
Mode, field effect birefringence mode, and the like.

(Second Embodiment) A method of driving a liquid crystal display device according to a second embodiment of the present invention will be described below with reference to the drawings. The scan electrode applied voltage waveform diagram and the signal electrode applied voltage waveform diagram in this embodiment are the same as those in the first embodiment shown in FIG. However, in this embodiment, a circuit for removing the distortion of the scanning voltage due to the change of the signal voltage is added to the scanning electrode in the liquid crystal display device. The circuit configuration of the liquid crystal display device in this example is shown in FIG.
In FIG. 3, 10 is a liquid crystal panel, 11 is a scanning electrode, 1
Reference numeral 2 is a signal electrode, 13 is a scan driver, 14 is a signal driver, 15 is a detection electrode, 16 is a detection circuit, 17 is a correction voltage generation circuit, 18 is a control circuit, and 19 is a drive voltage generation circuit. FIG. 5 is a voltage waveform diagram in the second embodiment. Like FIG. 2, FIG. 5A shows the node 101 of FIG.
Scanning voltage waveforms at 102 and 103, FIG.
(C) and (d) are signal voltage waveforms at the nodes 201, 211, and 221, and FIGS. 5 (e), (f), and (g) are shown in FIG.
3 shows voltage waveforms applied to the pixels 1, 2, and 3.

In the matrix type liquid crystal display device, the voltage applied to the signal electrode supplied by the signal driver 14 is distorted on the scanning electrode 11 due to the coupling by the liquid crystal when the signal voltage is switched. In this embodiment, by adding the detection electrode 15 similar to the scan electrode 11 to the substrate on the scan electrode side, a strain voltage is generated in the detection electrode 15 as well as the scan electrode 11. The distortion voltage generated in the detection electrode 15 is detected by a detection circuit 16 including, for example, an input terminal of an operational amplifier, and the correction voltage generation circuit 17 that amplifies the detected voltage to make it have an opposite phase.
In addition to the original drive voltage line of the scan driver 13, the scan electrode 1
It is possible to suppress the voltage distortion generated on the upper part.

This method is an example of detecting the voltage distortion generated on the scan electrode 11 when the voltage applied to the signal electrode is switched and correcting the voltage on the scan electrode 11 based on the detected voltage distortion. Any method may be used as long as it can correct the voltage distortion generated above.
With this method, the amount of distortion of the scanning electrodes due to the change in the signal voltage is reduced as compared with the first embodiment of FIG. 2A as shown in FIG. 5A, and the scanning is performed by switching the signal voltage once. The amount of voltage distortion is reduced from 1 unit in the first embodiment to about 0.1 unit. When the same calculation as in the conventional example is performed, the voltages applied to the pixels 1, 2, and 3 are as shown in FIGS.
(G), and the voltage distortion amounts of the second embodiment in the two fields in each non-selection period ta are -4.7 and-, respectively.
It becomes 4.6 and -4.4, and the difference in the amount of strain is only 0.3, which is almost no difference.

On the other hand, when the conventional driving method is simply used to remove the distortion of the scanning voltage due to the change of the signal voltage, the voltage applied to the pixels 1, 2, 3 is not selected in the non-selection period ta. The amount of voltage distortion in the two fields is -11.8, -7.4, and -2.6, respectively, and the difference between the amounts of distortion is 9.2, which does not improve brightness unevenness very much. This is because the difference in the amount of distortion due to the difference in the number of times the signal electrode drive voltage waveform is switched (difference in frequency component) cannot be improved only by removing the distortion in the scanning voltage. However, as in the second embodiment, by using the driving method of the first embodiment and the method of removing the distorted voltage on the scan electrodes in combination, a synergistic effect of the two methods is produced, and the effect is obtained. Both of the causes of the uneven brightness described can be improved at the same time,
Brightness unevenness is greatly improved.

Although the detection electrode 15 is provided on the power supply side of the signal electrode 12 in FIG. 3, the same effect as described above can be obtained by providing the detection electrode 15 on the final power supply side. In addition, since the distorted voltage on the scanning electrodes differs between the power supply side and the final power supply side viewed from the signal electrode side, the detection electrodes 15 are provided on both the power supply side and the final power supply side of the signal electrode 12 as shown in FIG. If the correction voltage is obtained by detecting the two detection electrodes 15, the distorted voltage can be removed more accurately. Further, the correction method is not limited to that shown in the second embodiment, and if the distortion of the scanning voltage due to the change in the signal voltage is removed, the driving in the first embodiment is performed like the second embodiment. A synergistic effect with the method appears, both of the causes of the brightness unevenness described in the operation can be simultaneously improved, and the brightness unevenness can be greatly improved.

The detection electrode 15 shown in FIGS.
May use a part of the scanning electrode 11 instead of the detection electrode. (Third Embodiment) A method of driving a liquid crystal display device according to a third embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the sheet resistance of the scan electrode is 10Ω / □ in the first embodiment, and the resistance per pixel in the direction from the power supply side to the final power supply side on the scan electrode is 10Ω. Is lowered until the resistance per pixel becomes 1Ω by the auxiliary wiring made of metal such as Al arranged in parallel with the scanning electrodes. The scan electrode applied voltage waveform diagram and the signal electrode applied voltage waveform diagram are the same as those in the first embodiment shown in FIG.
FIG. 6 is a voltage waveform diagram in the third embodiment. Like FIG. 2, FIG. 6A shows nodes 101 and 10 of FIG.
Scanning voltage waveforms at 2 and 103, FIG.
(C) and (d) are signal voltage waveforms at the nodes 201, 211, and 221. FIGS. 6 (e), (f), and (g) are shown in FIG.
3 shows voltage waveforms applied to the pixels 1, 2, and 3.

As shown in FIG. 6A, the amount of distortion of the scanning voltage due to the change in the signal voltage is lower than that of the first embodiment shown in FIG. 2A due to the lower resistance of the scanning electrode of this embodiment. The amount of distortion of the scanning voltage due to one switching of the signal voltage is reduced from 1 unit of the conventional example to about 0.3 unit. When the same calculation is performed, the voltages applied to the pixels 1, 2, and 3 are as shown in FIGS. 6E, 6F, and 6G, and the voltage distortion amounts in the two fields in the non-selection period ta are −, respectively. 6.4, -5.9, -5.3, the amount of strain is smaller than that of the conventional one, and the difference is considerably small (maximum difference 1.
1).

On the other hand, if only the auxiliary electrode is used and the resistance per pixel is set to 1Ω in the conventional driving method, the non-selection period t of the voltage applied to the pixels 1, 2, and 3 is reduced.
The amount of voltage distortion in the two fields in a is -1
6, -10.6, -4, the difference in strain amount is 12,
This causes uneven brightness. This is also because the difference in the amount of distortion due to the difference in the number of times the signal electrode drive voltage waveform is switched (frequency component difference) is not improved, as in the second embodiment. Therefore, even if the resistance of the scanning electrode is simply reduced, the frequency component of the waveform on the signal electrode side does not change, and the uneven brightness is not improved so much. However, as in the third embodiment, by using the driving method of the first embodiment and the lowering of the scanning electrode resistance in combination, the synergistic effect of the two methods appears and the uneven brightness can be greatly improved. it can. In addition, this reduction in the resistance of the scan electrodes is particularly effective with respect to the first embodiment because the resistance per pixel in the power supply / final direction on the scan electrodes is 5Ω or less. As shown, the uneven brightness hardly occurs.

In this embodiment, the method of lowering the resistance of the scanning electrode using the metal auxiliary wiring is used. However, not only this method but also a method of lowering the resistance of the scanning electrode such as simply lowering the resistance of the ITO electrode is used. If so, the difference in the amount of distortion of the drive voltage waveform applied to each pixel can be reduced as in this embodiment, and the uneven brightness can be greatly improved. (Fourth Embodiment) A method of driving a liquid crystal display device according to a fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is a waveform diagram of applied voltage in the driving method of the liquid crystal display device according to the fourth embodiment of the present invention.
(A), (b) and (c) are scan electrode applied voltage waveforms to be applied to the scan electrodes 100, 110 and 120 in FIG. 15, respectively, and (d), (e) and (f) are signal electrodes, respectively. Two
The waveforms of the voltage applied to the signal electrodes applied to 00, 210 and 220 are shown. FIG. 8 is a voltage waveform diagram in the fourth embodiment. Similar to FIG. 2, FIG. 8A shows the node 10 of FIG.
Scanning voltage waveforms at 1, 102 and 103, FIG.
(B), (c), (d) are nodes 201, 211, 22
Signal voltage waveform in Fig. 1, Fig. 8 (e), (f), (g)
Shows a voltage waveform applied to the pixels 1, 2, and 3 of FIG.

In the first to third embodiments, the rest period of the drive voltage waveform is provided between the scan pulses for both the signal electrode drive and the scan electrode drive, but in the fourth embodiment, As shown in FIG. 7, a rest period is set only for driving the signal electrode, and this is in a form that spans two scanning periods. The principle of making the difference in the number of switching for driving the signal electrodes constant without depending on the pattern is exactly the same as in the first embodiment, but in this embodiment, compared with the driving method of the first embodiment, a liquid crystal panel is used. It has the feature that the withstand voltage of the driving IC can be lowered.

In the method of the first embodiment, the pixel voltage waveforms are the conventional pixel voltage waveforms (FIGS. 18 (e), (f), (G))
Since the pause period is included, the effective value of the voltage applied to the pixel is reduced. Therefore, in order to drive the liquid crystal, the pulse voltage has to be set higher than in the conventional case, and the withstand voltage of the driving IC must be high. However, in this embodiment, as shown in FIGS.
As shown in (g), since the intermediate voltage between the ON pulse and the OFF pulse is applied to both ends of the selection pulse, the effective value can be prevented from lowering, and the withstand voltage of the driving IC can also be kept low. .

According to this driving method, the ON / OFF effective value ratio of the voltage for driving the pixel is lower than that in the conventional example and the first embodiment. Therefore, as shown in FIG.
By setting the pause period of the scan voltage shorter than that shown in the first embodiment and setting the pause period of the signal voltage over two scan periods, an optimum driving method according to the withstand voltage of the drive IC is obtained. be able to. In addition, FIG.
(B) and (c) are the scanning electrodes 100 in FIG.
Scan electrode applied voltage waveforms applied to 110 and 120, FIG.
(D), (e) and (f) are signal electrodes 200 and 2 respectively.
The waveform of the voltage applied to the signal electrodes applied to 10, 220 is shown.

Also, in the driving method of this embodiment, as in the second and third embodiments, by combining with the method of removing the distortion of the scanning voltage due to the change in the signal voltage, the uneven brightness can be greatly improved. it can. (Fifth Embodiment) A driving method of a liquid crystal display device according to a fifth embodiment of the present invention will be described below with reference to the drawings.

FIG. 10 shows an electrode applied voltage waveform in this embodiment when the halftone display shown in FIG. 18 is performed by the pulse width modulation method. And FIG. 10 (a),
19B and 19C are scan electrodes 100 and 100 in FIG. 19, respectively.
Scan electrode applied voltage waveforms applied to 110 and 120, FIG.
0 (d), (e), (f) are signal electrodes 200,
The waveform of the voltage applied to the signal electrodes applied to 210 and 220 is shown. FIG. 11 is a voltage waveform diagram according to the fourth embodiment. Like FIG. 2, FIG. 11A shows the node 10 of FIG.
Scanning voltage waveforms at 1, 102 and 103, FIG.
(B), (c), (d) are nodes 201, 211, 22
Signal voltage waveform in FIG. 11, (e), (f),
(G) shows the voltage waveform applied to the pixels 1, 2, and 3 of FIG.

In the case of the halftone display pattern as in this embodiment, as shown in FIG. 10, a rest period in which the scan electrode applied voltage and the signal electrode applied voltage have the same potential as the non-scan voltage is included in each scan period. It is provided in. As a result, the pixel voltage becomes as shown in FIGS. 11 (e), 11 (f) and 11 (g). By using this method, the difference in distortion amount due to the difference in the number of times of inversion of the signal electrode drive voltage waveform (frequency component difference) becomes small for any halftone data, as in the above embodiment.

Further, similarly to the second and third embodiments, it is also possible to greatly improve the luminance unevenness by using a method of removing the distortion of the scanning voltage due to the change of the signal voltage. . In the halftone display in the conventional pulse width modulation, the signal waveform is 1 by the halftone data.
There are cases where switching occurs and cases where switching does not occur within the scanning period, and since the number of waveform distortions due to the number of signal switching differs due to this, uneven brightness occurs due to the same mechanism as when switching display patterns in binary display. . However, according to this embodiment, the number of times of switching is the same regardless of any halftone data, and a uniform liquid crystal display device without uneven brightness can be obtained.

Also in this method, the ON / OFF effective value ratio of the voltage for driving the pixel is maintained as in the first embodiment, but the effective value of the voltage applied to the pixel is smaller than the conventional one. The withstand voltage of the liquid crystal panel drive IC must be high. Therefore, FIG.
If the drive voltage waveforms shown in FIGS. 12 (a), 12 (b), and 12 (c) are eliminated by eliminating the scan voltage pulse pause period shown in FIGS. 12 (a), 12 (b), and 12 (c), Waveform is Figure 13
As shown in (e), (f), and (g), it is possible to suppress a decrease in effective value and suppress the withstand voltage of the drive IC. FIG.
2 (a) to (f) show the waveforms of the scan electrode applied voltage and the signal electrode applied voltage, as in (a) to (f) of FIG. 10, and FIGS. 13 (a) to (g) show (a) of FIG. ) To (g), the scanning voltage waveform, the signal voltage waveform and the pixels 1, 2,
3 shows a voltage waveform applied to No. 3.

Further, also in the methods shown in FIGS. 12 and 13, the effective ON / OFF voltage ratio of the pixel becomes smaller than that in the conventional case. Here, FIG. 10 and FIG. 1 as shown in FIG.
By using a driving method in the middle of 2, that is, a method of applying a scan electrode applied voltage in the rest period to an intermediate voltage between the scanning voltage and the non-scanning voltage, an optimum driving method according to the breakdown voltage of the liquid crystal driving IC can be obtained. Obtainable. In addition,
14A to 14F are similar to FIGS. 10A to 10F.
The waveforms of the scan electrode applied voltage and the signal electrode applied voltage are shown.

Further, the difference in the amount of voltage distortion due to the halftone data can be eliminated only by the driving method shown in this embodiment, but the voltage distortion due to the switching of the display pattern occurs as in the conventional case, and the uneven brightness occurs. Therefore, in order to improve this, by combining the driving method of the first to fourth embodiments and the driving method of the fifth embodiment, the uneven brightness can be suppressed regardless of any display pattern including halftone display. It is possible to enable high-quality display that does not exist.

The present invention makes the distortion amount of the signal voltage constant regardless of the display pattern, and the distortion amount of the signal electrode applied voltage differs depending on the display pattern, that is, the signal electrode applied voltage waveform varies depending on the display pattern. If the driving method includes one that switches and one that does not switch, the unevenness in luminance can be improved by applying the driving method of the present invention. Further, in the above-described embodiment, the polarity of the scan electrode applied voltage and the signal electrode applied voltage with respect to the reference voltage (V0, V5) is inverted every scan cycle, and the voltage applied to the pixel is a complete AC signal in two scan cycles. Although the driving method as described above is used, the luminance unevenness can be improved by using the driving method of the present invention regardless of the cycle of the polarity inversion.

[0049]

As described above, according to the driving method of the liquid crystal display device of the present invention, the period between the first scanning pulse and the second scanning pulse, or the period straddling the first scanning pulse and the second scanning pulse. In addition, by applying the same voltage as the non-scanning voltage applied to the scanning electrode group to the signal electrode group, the voltage distortion difference caused by the switching frequency difference (frequency component difference) due to the signal voltage is made constant regardless of the display pattern, Even in a large display capacity panel, high-quality display with less uneven brightness can be realized. Particularly, in the method of applying the same voltage as the non-scanning voltage applied to the scanning electrode group to the signal electrode group between the first scanning pulse and the second scanning pulse, the ON / OFF effective value ratio is made equal to that of the conventional one. Therefore, it is possible to perform display without brightness unevenness while maintaining the conventional contrast. Further, a detection electrode that generates a strain voltage equivalent to the strain voltage of the scan electrode due to a change in the signal voltage is provided, and voltage correction is performed on the scan electrode group based on the strain voltage generated in the detection electrode, or scanning is performed. By setting the resistance per pixel on the electrode in the direction of power feeding / terminal power to 5Ω or less,
The amount of distortion of the voltage of the scanning electrode due to the change of the voltage of the signal electrode can be significantly reduced, and higher-quality display can be achieved without uneven brightness regardless of the display pattern.

Further, by displaying a halftone by the pulse width modulation method and applying the same voltage as the non-scanning voltage to the signal electrode group in a predetermined period in the middle of each scanning period,
The number of times the signal voltage is switched in one scanning period is the same for any halftone data, and high-quality display with no brightness unevenness can be achieved regardless of any display pattern including halftone display.

[Brief description of drawings]

1A, 1B, and 1C are waveform diagrams of a voltage applied to a scanning electrode in a driving method of a liquid crystal display device according to a first embodiment of the present invention, and FIGS. 1D, 1E, and 1F. FIG. 4 is a waveform diagram of a voltage applied to a signal electrode in the example.

FIG. 2A is a schematic diagram of a voltage waveform on a scan electrode side of a pixel in the driving method of the liquid crystal display device according to the first embodiment of the present invention, and FIGS. 2B, 2C and 2D are the same. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

FIG. 3 is a block diagram of a liquid crystal display device in a method of driving a liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a liquid crystal display device in a method of driving a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device according to the second embodiment of the present invention, and FIGS. 5B, 5C and 5D are the same. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

FIG. 6A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device according to the third embodiment of the present invention, and FIGS. 6B, 6C and 6D are the same. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

7 (a), (b) and (c) are scan electrode applied voltage waveform diagrams in a driving method of a liquid crystal display device according to a fourth embodiment of the present invention, (d), (e) and (f). FIG. 4 is a waveform diagram of a voltage applied to a signal electrode in the example.

FIG. 8A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device of the fourth embodiment of the present invention, and FIGS. 8B, 8C and 8D are the same. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

FIG. 9A is a schematic diagram of a voltage waveform on a scan electrode side of a pixel in the driving method for the liquid crystal display device according to the fourth embodiment of the present invention, and FIGS. 9B, 9C and 9D show the same embodiment. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

10 (a), (b), (c) are scan electrode applied voltage waveform diagrams in the driving method of the liquid crystal display device of the fifth embodiment of the present invention, (d), (e), (f). FIG. 4 is a waveform diagram of a voltage applied to a signal electrode in the example.

FIG. 11A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device according to the fifth embodiment of the present invention, and FIGS. 11B, 11C and 11D show the same embodiment. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

12 (a), (b), (c) are scan electrode applied voltage waveform diagrams in the driving method of the liquid crystal display device of the fifth embodiment of the present invention, (d), (e), (f). FIG. 4 is a waveform diagram of a voltage applied to a signal electrode in the example.

FIG. 13A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device according to the fifth embodiment of the present invention, and FIGS. 13B, 13C and 13D show the same embodiment. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

FIG. 14A is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in the driving method of the liquid crystal display device of the fifth embodiment of the present invention, and FIGS. 14B, 14C and 14D are the same. Schematic of the voltage waveform on the signal electrode side of the pixel in the example, (e), (f),
(G) is a schematic diagram of a voltage waveform applied to the pixel in the embodiment.

FIG. 15 is a display pattern diagram of a matrix type liquid crystal display panel.

FIG. 16 is an equivalent circuit diagram relating to one scanning electrode of a matrix type liquid crystal display panel.

17 (a), (b) and (c) are waveform diagrams of applied voltage to scan electrodes in a conventional method for driving a liquid crystal display device,
(D), (e), (f) is a signal electrode applied voltage waveform diagram in the same driving method.

FIG. 18A is a schematic diagram of a voltage waveform on a scan electrode side of a pixel in a driving method of a conventional liquid crystal display device, FIG.
(C) and (d) are schematic diagrams of voltage waveforms on the signal electrode side of pixels in the same driving method, and (e), (f), and (g) are schematic diagrams of voltage waveforms applied to pixels in the same driving method. .

FIG. 19 is a halftone display pattern diagram of a matrix type liquid crystal display panel.

20 (a), (b) and (c) are waveform diagrams of scan electrode applied voltage in a conventional pulse width modulation driving method for a liquid crystal display device, and (d), (e) and (f) are the same driving method. 5 is a waveform diagram of voltage applied to the signal electrode in FIG.

FIG. 21 (a) is a schematic diagram of a voltage waveform on the scanning electrode side of a pixel in a conventional pulse width modulation driving method for a liquid crystal display device, and FIGS. Schematic diagram of voltage waveform on the signal electrode side, (e), (f),
(G) Schematic of the voltage waveform applied to the pixel in the same driving method.

[Explanation of symbols]

1, 2 and 3 pixels 10 liquid crystal panel 11 scanning electrode 12 signal electrode 13 scanning driver 14 signal driver 15 detection electrode 16 detection circuit 17 correction voltage generation circuit 18 control circuit 19 drive voltage generation circuit 100, 110, 130, 140, 150, 160 scanning electrodes 200, 210, 220 signal electrodes 99, 101, 102, 103, 201, 211, 22
1 node

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoneharu Takubo 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] 1. A matrix type liquid crystal display device in which a liquid crystal is sandwiched between a first substrate provided with a signal electrode group and a second substrate provided with a scanning electrode group intersecting the signal electrode group. A driving method of the first scanning pulse applied sequentially to the scanning electrode group.
Liquid crystal display, wherein a non-scanning voltage period is provided between the second scanning pulse and the second scanning pulse, and the same voltage as the non-scanning voltage is applied to the signal electrode group during this non-scanning voltage period. Device driving method. 2. A matrix type liquid crystal display device in which a liquid crystal is sandwiched between a first substrate provided with a signal electrode group and a second substrate provided with a scanning electrode group intersecting the signal electrode group. A driving method of the first scanning pulse applied sequentially to the scanning electrode group.
The non-scanning voltage is applied during a predetermined period spanning a first period for applying the scanning pulse and a second period for applying the second scanning pulse subsequent to the first scanning pulse. A method of driving a liquid crystal display device, which comprises applying the signal electrode group. 3. A matrix type liquid crystal display device in which a liquid crystal is sandwiched between a first substrate provided with a signal electrode group and a second substrate provided with a scanning electrode group intersecting the signal electrode group. A driving method of the first scanning pulse applied sequentially to the scanning electrode group.
A non-scanning voltage period is provided between the second scanning pulse and the second scanning pulse, and the same voltage as the non-scanning voltage is applied to the signal electrode group in a predetermined period spanning the non-scanning voltage period. A method of driving a characteristic liquid crystal display device. 4. A detection electrode, which generates a strain voltage equivalent to the strain voltage of the scan electrode due to a change in signal voltage, is provided on a second substrate having a scan electrode group, and the strain voltage generated on the detection electrode is used as a basis. The method for driving a liquid crystal display device according to claim 1, wherein voltage correction is performed on the scan electrode group. 5. The method of driving a liquid crystal display device according to claim 1, wherein the liquid crystal display device is driven so that the resistance per pixel on the scanning electrode in the power supply / final direction is 5Ω or less. 6. The halftone is displayed by a pulse width modulation method, and the same voltage as the non-scanning voltage is applied to the signal electrode group during a predetermined period in the middle of each scanning period. 4. The method for driving the liquid crystal display device according to 2 or 3. 7. A detection electrode that generates a strain voltage equivalent to the strain voltage of the scan electrode due to a change in signal voltage is provided on a second substrate having a scan electrode group, and the strain voltage generated on the detection electrode is used as a basis. The voltage correction is performed on the scanning electrode group to display the halftone by the pulse width modulation method, and the same voltage as the non-scanning voltage is applied to the signal electrode group during a predetermined period in the middle of each scanning period. The method for driving a liquid crystal display device according to claim 1, 2, or 3. 8. A liquid crystal display device having a resistance of 5 Ω or less per pixel on the scanning electrode in the power supply / final direction is driven to display a halftone by a pulse width modulation method, and at the middle of each scanning period. The non-scanning voltage and the same voltage are applied to the signal electrode group in a predetermined period.
A method for driving the described liquid crystal display device.