JP3155671B2 - Liquid crystal display - Google Patents

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,
More specifically, the present invention relates to a duty driving type liquid crystal display device that can operate with low power consumption.

[0002]

2. Description of the Related Art With the downsizing of laptop computers and personal digital assistants, the demand for a liquid crystal display device having a small size, low power consumption and more pixels as a display device of the device has increased. Is being developed.

FIG. 6 is a block diagram showing a configuration of a typical conventional liquid crystal display device 1. As shown in FIG. Liquid crystal display device 1
Is configured to include a liquid crystal display unit 2, a control unit 3, and a power supply circuit 4. The liquid crystal display means 2 includes a liquid crystal display panel 5, a data driver 6, and a common driver 7.

The control means 3 controls the data driver 6 and the common driver 7 based on a control signal input from the outside. The liquid crystal display panel 5 is configured by interposing a liquid crystal layer between a pair of substrate members. One of the pair of substrate members has a plurality of signal electrodes X1, X2,..., X on one surface of a light-transmitting substrate made of glass, plastic, or the like.
L (referred to collectively as X) is arranged, and the alignment film covers the entire surface while the signal electrodes X are arranged. Further, the other substrate member includes a plurality of scanning electrodes Y on one surface of a light-transmitting substrate made of glass, plastic, or the like.
1, Y2,..., YM (the reference numeral Y is used when collectively referred to) are arranged, and the alignment film covers the entire surface while the scanning electrodes Y are arranged. Each substrate member is arranged so that the alignment film faces each other, and the signal electrode X and the scanning electrode Y intersect. The substrate members are attached to each other at a predetermined interval by a sealing member, and between the substrate members. A liquid crystal layer is formed with a liquid crystal interposed. Display is performed with the intersection of the signal electrode X and the scanning electrode Y as a pixel.

The data driver 6 is connected to each of the signal electrodes X, and selectively applies an ON potential and an OFF potential to the signal electrode X. The common driver 7 is connected to each of the scanning electrodes Y, applies a selection potential line-sequentially to the scanning electrodes Y every horizontal scanning period, and applies a non-selection potential to the remaining scanning electrodes to which no selection potential is applied. .

The power supply circuit 4 generates a selection potential and a non-selection potential of the scanning electrode Y and an on potential and an off potential of the signal electrode X and supplies them to each driver, and supplies a driving power source to the control means 3. I do.

In the liquid crystal display device 1 configured as described above, by using a driving method called a duty driving method in which the scanning electrode voltage is periodically changed, a driving method in which the scanning electrode voltage is kept constant is used. The drive voltage of the data driver 6 is reduced to reduce current consumption. On the other hand, since the voltage application time to one pixel is shortened by the increase in the duty ratio accompanying the increase in the number of pixels constituting one horizontal line, the applied voltage is increased. For this reason, the current consumption of the scan electrodes, particularly the charge / discharge current flowing to the pixel which is considered to be equivalent to a capacitor when switching between selection and non-selection of the scan electrode, increases. The charges applied in the display period by the data driver 6 and the common driver 7 and held in each pixel of the liquid crystal display panel 5 are returned to the respective drivers 6 and 7 via resistors after the display period, and furthermore, the power supply circuit It is returned to 4.

[0008] A first technique for suppressing waste of electric charges in a liquid crystal display device is disclosed in Japanese Patent Application Laid-Open No. 5-188888. In this first publication, a switching circuit that opens and closes at a predetermined timing is connected to a common electrode, and after the display period ends, the electric charge is returned to a power supply via a converter to thereby reduce the driving current during inversion driving. The increase in the driving power of the common electrode due to the increase is suppressed.
A second technique for suppressing waste of electric charge is disclosed in
It is disclosed in Japanese Patent Publication No. 3-48416. In this second publication, the drive power consumption is reduced by applying an intermediate potential to each electrode for a certain period of time at each cycle after the end of the display period.

[0009]

In the liquid crystal display device disclosed in the first publication, a switching circuit and a converter are required in order to suppress an increase in driving power, and the number of parts and the number of manufacturing steps are increased. Increase. Further, charge loss occurs in a circuit through which the charge returns to the power supply. In the liquid crystal display device disclosed in the second publication, the structure of the electrode driving means for applying electric charges is complicated, and the manufacturing cost increases due to the increase in the number of components and the number of manufacturing steps.

Also, in the duty driving type liquid crystal display device, since the period during which each pixel is selected is extremely short, the voltage difference between the selected state and the non-selected state of the scanning electrode becomes large, and the switching state between the selected state and the non-selected state is increased. The transition time tends to be short, and a steep voltage waveform cannot be obtained due to the internal resistance and protection resistance of the drive circuit, which causes a decrease in the reaction speed of the liquid crystal and a decrease in display quality. .

An object of the present invention is to provide a liquid crystal display device capable of suppressing the electric power supplied from the driving means and obtaining a good display with a high reaction speed of the liquid crystal.

[0012]

According to the present invention, a liquid crystal layer is interposed between a plurality of signal electrodes and a plurality of scanning electrodes which are arranged so as to intersect with each other. A liquid crystal display panel having a portion as a pixel, a power supply unit for supplying a plurality of potentials, and a horizontal scan electrode group which is sequentially scanned by selectively applying the potential of the power supply unit, are predetermined. A scanning electrode that applies a selection potential whose polarity is inverted with respect to a reference potential as a central value to the scanning electrodes in a line-sequential manner, and applies a non-selection potential having a polarity opposite to the selection potential to the remaining scanning electrodes to which no selection potential is applied. Driving means;
In a period determined based on data displayed on a pixel corresponding to the scanning electrode to which the selection potential is applied, by selectively applying a potential of the power supply unit, a polarity opposite to the selection potential is applied. A signal electrode driving means for applying an on potential to the signal electrode and applying an off potential to the signal electrode during periods other than the above, provided between the liquid crystal display panel and the scanning electrode driving means. And a switching unit including a switching element for conducting / cutting off between adjacent scanning electrodes, and the selection potential being applied for a predetermined period after scanning of the selected scanning electrode in the horizontal electrode group is completed. The scanning electrode driving means is instructed to disconnect the scanning electrode and the scanning electrode to which the selection potential is to be applied subsequently to the scanning electrode from the power supply means. Control means for conducting the switching element provided between the scanning electrode to which the selection potential is applied and the scanning electrode to which the selection potential is to be applied subsequently to the scanning electrode during a predetermined period. When,
A liquid crystal display device comprising: According to another aspect of the present invention, there is provided a liquid crystal display panel having a liquid crystal layer interposed between a plurality of signal electrodes and a plurality of scanning electrodes arranged so as to intersect each other, and having a pixel at an intersection between the signal electrode and the scanning electrode. Power supply means for supplying a plurality of potentials; and selectively applying the potentials of the power supply means. Scanning electrode driving means for applying a selection potential to be inverted to the scanning electrodes line-sequentially, and applying a non-selection potential having a polarity opposite to the selection potential to the remaining scanning electrodes to which no selection potential is applied; and In the period determined based on the data displayed on the pixel corresponding to the applied scanning electrode, by selectively applying the potential of the power supply means, an ON potential having a polarity opposite to the selection potential is signaled. On the electrode In addition, a signal electrode driving means for applying an off potential to the signal electrode in a period other than the above period, a signal provided between the liquid crystal display panel and the signal electrode driving means, and a signal adjacent to each other is provided. A switching unit having a switching element for conducting / cutting off between the electrodes, and disconnecting all signal electrodes from the power supply unit for a predetermined period after scanning of the selected scanning electrode in the horizontal electrode group is completed. Control means for instructing the signal electrode driving means to conduct all the switching elements in the switching means during the predetermined period.

[0013]

According to the present invention, a liquid crystal display device includes a switching means provided between a scanning electrode provided on a liquid crystal display panel and a scanning electrode driving means, for switching between adjacent scanning electrodes. After the scanning of the selected scanning electrode in the horizontal electrode group is completed by the control means, for a predetermined period, the scanning electrode to which the selection potential has been applied, and the selection potential subsequently to the scanning electrode. Disconnecting the scanning electrode to be applied from the power supply means,
A switching element provided between the scanning electrode to which the selection potential has been applied and the scanning electrode to which the selection potential is to be applied subsequently to the scanning electrode is made conductive. Therefore, after the scanning of the selected scanning electrode in the horizontal electrode group is completed, a part of the charge remaining on the scanning electrode to which the selection potential has been applied is next applied to the selection potential during a predetermined period. The scanning electrode is sent to the scanning electrode, and changes to an intermediate potential between the selection potential and the non-selection potential, so that waste of electric charges can be reduced and power supplied from the power supply means can be suppressed.

The liquid crystal display device further comprises a switching means provided between the signal electrode provided on the liquid crystal display panel and the signal electrode driving means, the switching means including a switching element for conducting / cutting off between adjacent signal electrodes. The control means disconnects all signal electrodes from the power supply means for the predetermined period, and makes all switching elements in the switching means conductive. Accordingly, during a predetermined period after the scanning of the selected horizontal scanning electrode group is completed, all the signal electrodes are turned on by the switching elements, and the charges are averaged in all the signal electrodes, thereby reducing waste of the charges. It is possible,
The power supplied from the power supply means can be suppressed.

[0015]

FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 21 according to a first embodiment of the present invention, and FIG. 2 is a circuit diagram around a liquid crystal display panel 25. The liquid crystal display device 21
It is configured to include a liquid crystal display unit 22, a control unit 23, and a power supply circuit 24. The liquid crystal display means 22 includes a liquid crystal display panel 25, a data driver 26, a common driver 27, and a switch circuit 28.

The control means 23 comprises a data driver 26 and a common driver 2 based on a control signal input from the outside.
7 is controlled. The power supply circuit 24 converts the power supplied from the outside into a plurality of predetermined potentials,
3. The data is supplied to the data driver 26 and the common driver 27. The power supply circuit 24 includes potentials V6 and V1, which are a selection potential of the scanning electrode Lc described later and an on potential of the signal electrode Ls described later, potentials V2 and V5 which are non-selection potentials of the scanning electrode Lc, and an off state of the signal electrode Ls. Potential V which is a potential
And V4 are generated and supplied to the drivers 26 and 27, and a power supply for driving the control means 23 is supplied. Each potential is supplied to each of the drivers 26 and 27 according to a combination shown in Table 1 below.

[0017]

[Table 1]

In the following description, only the combinations shown in (1) of Table 1 are used, but the same applies to the case where the combination shown in (2) is used. In this embodiment, the combination of potentials applied every vertical scanning period is changed. That is, if the selection potential applied line-sequentially in a certain vertical scanning period is the potential V6, the potential V2 is applied as a non-selection potential to the other scanning electrodes to which the selection potential is not applied, and the signal electrode is applied in the vertical scanning period. Is applied with a potential V1 as an ON potential and a potential V4 as an OFF potential. In the subsequent vertical scanning period, the potential V
1, a potential V5 is applied as a non-selection potential,
A potential V6 is applied to the signal electrode as an ON potential and a potential V3 is applied as an OFF potential.

The liquid crystal display panel 25 is configured by interposing a liquid crystal layer between a pair of substrate members. One of the pair of substrate members has a plurality of scanning electrodes Lc1 and Lc on one surface of a light-transmitting substrate made of glass, plastic, or the like.
2,..., Lcn (when collectively referred to, use reference numeral Lc)
Are arranged, and the alignment film covers the whole surface while the scanning electrodes Lc are arranged. The other substrate member has a plurality of signal electrodes Ls1, Ls2,..., Lsm (referred to collectively using a reference numeral Ls) arranged on one surface of a light-transmitting substrate made of glass, plastic, or the like. While the Ls is arranged, the entire surface is covered with an alignment film.
Each substrate member is arranged so that the alignment film faces each other, and the signal electrode Ls and the scanning electrode Lc intersect. The substrate members are bonded to each other at a predetermined interval by a sealing member, and between the substrate members. A liquid crystal layer is formed with a liquid crystal interposed. As shown in FIG. 2, the intersection of the scanning electrode Lc and the signal electrode Ls becomes a pixel in the liquid crystal display panel 25, and electrically equivalent capacitors C11, C12,.
33,... (The reference numeral C is used when collectively referred to).

As shown in FIG. 2, the common driver 27 is provided with a protection resistor and a plurality of driving transistors for each scanning electrode Lc in the liquid crystal display panel 25. In the common driver 27, each potential V1, V2, V5, V6 supplied from the power supply circuit 24
Are supplied to the corresponding driving transistors 29 to 40, respectively. In accordance with a signal supplied from the control means 23, a predetermined driving transistor is turned on, and a potential corresponding to the driving transistor is supplied to each scanning electrode Lc via a protection resistor. Driving transistors 29 to 32 and protection resistor 46 are provided for scan electrode Lc1, and drive transistors 33 to 32 are provided for scan electrode Lc2.
36 and a protection resistor 47 are provided, and drive transistors 37 to 40 and a protection resistor 48 are provided for the scan electrode Lc3. Four driving transistors and one protection resistor are provided so as to correspond to the other scanning electrodes Lc, respectively.

The switch circuit 28 is provided between the scan electrode Lc and the common driver 27, and includes switches S1 and S1.
., S3,... The switch circuit 28 includes the scan electrode Lc1
The switch S1 is provided between the scan electrode Lc2 and the scan electrode Lc2, and the switch S2 is provided between the scan electrode Lc2 and the scan electrode Lc3. That is, a switch S is provided between each adjacent scanning electrode Lc, and the switch circuit 28 is provided with n-1 switches S. The adjacent scanning electrodes Lc can be made electrically conductive by the switch S, so that charges can be exchanged between the scanning electrodes adjacent to each other. The switch S in the switch circuit 28 is controlled by the control unit 23 to operate at a predetermined timing.

FIG. 3 is a timing chart showing a potential waveform applied to the scanning electrodes Lc2 and Lc3. FIG.
In the timing chart shown in FIG. 1, description will be made using combinations shown in (1) of Table 1. FIG. 3A shows a potential waveform applied to the common electrode Lc2, and FIG.
Represents a potential waveform applied to the scanning electrode Lc3. FIG.
In the potential waveform shown in (1), a potential V2 which is a non-selection potential is applied until time t0, and the scan electrode Lc2 is in a non-selection period. In the common driver 27 shown in FIG. 2, the transistor 34 is conducting. At time t0, the transistor 34 is turned off, and during the period T0 from time t0 to time t1, no potential is applied to the scan electrode Lc2. At time t1, the transistor 36 is turned on and the potential V6, which is a selection potential, is applied to the scan electrode Lc2. The selection period is a period T1 from time t1 to time t2. The potentials V2 and V6 have opposite polarities across the reference potential.

At time t2, the transistor 36 is turned off, and no potential is applied to the scan electrode Lc2 during a period T2 from time t2 to time t3. In addition, in the potential waveform shown in FIG.
Is cut off, and the potential V, which is a non-selection potential, is applied to the scan electrode Lc3.
2 is not applied, and no potential is applied to the scan electrode Lc3 during the period T2. In a period T3, which is shorter than the period T2, the switch S2 in the switch circuit 28 is turned on, the scan electrodes Lc2 and Lc3 conduct with each other, and a part of the charge accumulated in the liquid crystal element of the scan electrode Lc2 is transferred to the scan electrode Lc3. And move. At time t3,
When the transistor 34 is turned on, the potential V2 is applied to the scan electrode Lc2, and a non-selection period is set. FIG.
The potential waveform applied to the scanning electrode Lc3 shown in (2) is
In the period T4 from the time t3 to the time t4, the transistor 40 is turned on to reach the potential V6 which is the selection potential, and the scanning electrode Lc3 is in the selection period during the period T4.

The same operation is performed for all the scanning electrodes Lc, thereby completing one vertical scanning period. Each scanning electrode is in the selection period only once in one vertical scanning period.
The same operation is repeated in the liquid crystal display device 21 to perform display.

As described above, according to the present embodiment, the switch circuit 28 is provided between the common driver 27 and the scanning electrode Lc, and when a selection potential is applied to each scanning electrode, the switching between the non-selection period and the selection period is performed. Since a period during which no potential is applied is set, and the scan electrode for which the selection period has ended and the scan electrode to be the next selection period are turned on by turning on the switch S in the period during which the potential is not applied, the switch S is turned on. Part of the charge remaining in the liquid crystal element after the end of the selection period can be sent to the scan electrode which is to be the next selection period, so that waste of the charge can be reduced. Further, the conducting scan electrode changes to the intermediate potential, and the transition to the intermediate potential is a transition which is not affected by the driver circuit and the protection resistance, so that the transition becomes steep, the reaction speed of the liquid crystal is improved, and the liquid crystal display panel is improved. 25
Can be improved in display quality.

FIG. 4 is a block diagram showing the structure of a liquid crystal display device 51 according to a second embodiment of the present invention, and FIG. 5 is a circuit diagram around the liquid crystal display panel 25. In the liquid crystal display device 51, the same components as those of the liquid crystal display device 21 in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted. A feature of the liquid crystal display device 51 in the present embodiment is that, instead of the switch circuit 28 provided between the common driver 27 and the liquid crystal display panel 25 in the liquid crystal display device 21, the data driver 26 and the liquid crystal display panel 25 That is, a switch circuit 58 is provided therebetween. In the data driver 26, m sets of four driving transistors and protection resistors controlled by the control unit 23 are provided so as to correspond to the respective signal electrodes Ls, and each potential supplied from the power supply circuit 24 is provided. V1, V3, V
4, V6 can be selectively applied to the signal electrode Ls. As shown in FIG. 5, driving transistors 69 to 72 and a protection resistor 66 are provided for the signal electrode Ls1,
Driving transistors 73 to 76 for signal electrode Ls2
And a protection resistor 67 are provided.

The switch circuit 58 is composed of m-1 switches. A switch Sw1 is provided between the signal electrodes Ls1 and Ls2, a switch Sw2 is provided between the signal electrodes Ls2 and Ls3, and the signal electrodes Ls3 and Ls3 are provided.
A switch SW3 is provided between s4.

In this embodiment, for example, the scanning electrode L
When switching from the state in which c2 is selected to the state in which scan electrode Lc3 is selected, all transistors 69 to 80 included in data driver 26 are shut off to disconnect signal electrode Ls from data driver 26, and switch SW are turned on so that the electric charge is averaged at the signal electrode Ls, and after the electric charge is moved, the switch SW
Turn off. After the selection period of the scanning electrode Lc3 is reached, a predetermined driving transistor 69 to 80 in the data driver 26 is turned on to apply a potential corresponding to the displayed data to the signal electrode Ls. Thereafter, similarly, when the scanning electrode Lc, which is the selection period, moves line-sequentially, the above operation is repeated so that the electric charge remaining in the liquid crystal element is averaged in each signal electrode Ls.

Referring to FIG. 3, the scanning electrode Lc2
In the period T2 between the period T1 which is the selection period of the above and the period T4 which is the selection period of the scanning electrode Lc3, the signal electrode L
s and the data driver 26 are disconnected, and the period T
In 3, all the signal electrodes Ls are made conductive to each other and the potentials are averaged. Thereafter, the same operation is repeated every horizontal scanning period.

As described above, according to the present embodiment, the switch circuit 58 is provided between the data driver 26 and the signal electrode Ls, and the signal electrode Ls is provided between a certain scanning electrode selection period and a subsequent scanning electrode selection period. A period during which no potential is applied is set, and during the period during which the potential is not applied, the switch S
w, all signal electrodes L
Since s is conducted, the charge remaining in the liquid crystal element after the selection period ends can be averaged in each signal electrode Ls, and waste of the charge can be reduced. Further, the potential of each signal electrode Ls is averaged in all the signal electrodes Ls, and the transition at the time of averaging is a transition that is not affected by the driver circuit and the protection resistance, so that the transition becomes steep, and the reaction speed of the liquid crystal is reduced. The display quality of the liquid crystal display panel 25 can be improved.

In each of the above embodiments, the liquid crystal display devices 21 and 51 provided with the switch circuit 28 and the switch circuit 58 independently have been described. However, a configuration in which both the switch circuit 28 and the switch circuit 58 are provided. It may be. In this case, power consumption can be further reduced as compared with the case where only one of the switch circuits is provided.

[0032]

As described above, according to the present invention, after the scanning of the selected scanning electrode in the horizontal electrode group is completed, the scanning electrode to which the selected potential is applied and the scanning electrode to which the selected potential is applied for a predetermined period. Subsequently, the switching element provided between the scanning electrode to which the selection potential is to be applied and the scanning element to which the selection potential is applied is made conductive by the control means. Part of the charge can be transmitted, and waste of the charge is reduced, so that power consumption of the liquid crystal display device can be reduced. In addition, since each of the scanning electrodes that are turned on by the switching element makes a sharp transition to the intermediate potential, the reaction speed of the liquid crystal is improved, and the display quality of the liquid crystal display panel can be improved.

Further, according to the present invention, the switching element provided between each signal electrode and the signal electrode driving means is turned on by the control means during a predetermined period after the scanning of the selected horizontal scanning electrode group is completed. The electric charges are averaged in all the signal electrodes, the waste of electric charges is reduced, and the power consumption of the liquid crystal display device can be reduced. Further, since each signal electrode makes a sharp transition to the average potential, the reaction speed of the liquid crystal is improved, and the display quality in the liquid crystal display panel can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a liquid crystal display device 21 according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram around a liquid crystal display panel 25.

FIG. 3 is a timing chart showing potential waveforms applied to scanning electrodes Lc2 and Lc3.

FIG. 4 is a block diagram illustrating a configuration of a liquid crystal display device 51 according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram around the liquid crystal display panel 25.

FIG. 6 is a block diagram showing a configuration of a liquid crystal display device 1 which is a typical conventional example.

[Explanation of symbols]

 21, 51 Liquid crystal display device 22 Liquid crystal display means 23 Control means 24 Power supply circuit 25 Liquid crystal display panel 26 Data driver 27 Common driver 28, 58 Switch circuit 29-40, 69-80 Driving transistor

Continuation of the front page (56) References JP-A-8-137436 (JP, A) JP-A-7-199866 (JP, A) JP-A-5-210358 (JP, A) JP-A-63-60195 (JP) , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G09G 3/00-3/38 G02F 1/133 505-580

Claims (2)

(57) [Claims] 1. A liquid crystal display panel comprising a liquid crystal layer interposed between a plurality of signal electrodes and a plurality of scanning electrodes arranged so as to intersect with each other, and having a pixel at an intersection between the signal electrode and the scanning electrode. A power supply means for supplying a plurality of potentials; and selectively applying a potential of the power supply means to a horizontal scanning electrode group which is sequentially scanned. Scanning electrode driving means for applying a selection potential to be inverted to the scanning electrodes line-sequentially and applying a non-selection potential having a polarity opposite to the selection potential to the remaining scanning electrodes to which no selection potential is applied; In the period determined based on the data displayed on the pixel corresponding to the applied scanning electrode, by selectively applying the potential of the power supply means, an ON potential having a polarity opposite to the selection potential is signaled. On the electrode And a signal electrode driving means for applying an off-potential to the signal electrode during periods other than the above-mentioned period, wherein the scanning is provided between the liquid crystal display panel and the scanning electrode driving means and adjacent to each other. A switching unit including a switching element that conducts / cuts off between the electrodes, and after the scanning of the selected scanning electrode in the horizontal electrode group is completed,
During a predetermined period, the scan electrode driving unit is instructed to disconnect the scan electrode to which the select potential has been applied and the scan electrode to which the select potential is to be subsequently applied from the power supply unit. Then, during the predetermined period, the switching element provided between the scanning electrode to which the selection potential is applied and the scanning electrode to which the selection potential is to be applied subsequently to the scanning electrode is turned on. A liquid crystal display device comprising: 2. A liquid crystal display panel having a liquid crystal layer interposed between a plurality of signal electrodes and a plurality of scanning electrodes arranged so as to intersect with each other, and having a pixel at an intersection between the signal electrode and the scanning electrode. A power supply means for supplying a plurality of potentials; and selectively applying a potential of the power supply means to a horizontal scanning electrode group which is sequentially scanned. Scanning electrode driving means for applying a selection potential to be inverted to the scanning electrodes line-sequentially and applying a non-selection potential having a polarity opposite to the selection potential to the remaining scanning electrodes to which no selection potential is applied; In the period determined based on the data displayed on the pixel corresponding to the applied scanning electrode, by selectively applying the potential of the power supply means, an ON potential having a polarity opposite to the selection potential is signaled. On the electrode And a signal electrode driving means for applying an off potential to the signal electrodes during periods other than the above. A signal provided between the liquid crystal display panel and the signal electrode driving means and adjacent to each other. A switching unit including a switching element that conducts / cuts off between the electrodes, and after the scanning of the selected scanning electrode in the horizontal electrode group is completed,
Control means for instructing the signal electrode driving means to disconnect all signal electrodes from the power supply means for a predetermined period, and conducting all switching elements in the switching means for the predetermined period. A liquid crystal display device comprising: