JP2503265B2 - Driving method of liquid crystal display device - Google Patents

Description

[Detailed description of the invention] [Table of contents] Outline ...... page 4 Industrial field of use ...... page 5 Conventional technology ...... page 6 Problems to be solved by the invention ...... pages 7 to 10 To solve the problems Means ...... Page 10 to 12 Action ...... Page 12 to 14 Example 1st Example ...... Page 14 to 20 Second Example ...... Page 20 to 22 Third Example ...... Page 22 to 24 ...... Page 25 [Summary] Regarding the driving method of a simple matrix type liquid crystal display device, the distortion of the cell applied voltage waveform depending on the display pattern is suppressed to suppress the occurrence of uneven brightness (crosstalk), In a liquid crystal display device that drives a liquid crystal cell by applying a voltage from a data electrode and a scan electrode, the number of on-displays or the number of off-displays of the liquid crystal cell on the scan electrode is counted for each scan electrode drive, and the counted value is calculated. Differentiate the proportional DC voltage and deselect the differentiated pulse output. When the voltage is applied to the data electrode on the opposite side, it is induced in the scan electrode by applying the opposite polarity to the voltage applied to the selected scan electrode or the voltage applied to the data electrode. The differential pulse to be generated is canceled, and as a result, the distortion of the cell applied voltage waveform due to the display pattern is suppressed.

[Industrial applications]

The present invention relates to a driving method of a simple matrix type liquid crystal display device.

2. Description of the Related Art With the recent widespread use of personal computers, word processors, and the like, as a display device therefor, a lightweight and thin liquid crystal display device that can be driven by a battery has been remarkably adopted in place of a large-sized and power-consuming CRT.

The drive system of this liquid crystal display device is roughly classified into a simple matrix type and an active matrix type, but the latter active matrix type is difficult to manufacture because each pixel arranged in a matrix requires a non-linear element. At present, a simple matrix type is generally adopted for a liquid crystal display device having a large display capacity.

However, in a liquid crystal display device with a simple matrix structure,
As the display capacity is increased, display unevenness (crosstalk) depending on the display pattern due to its characteristics occurs, and the display quality deteriorates. Therefore, it is strongly desired to eliminate this display unevenness.

[Conventional technology]

Figure 6, in the liquid crystal display panel of a simple matrix structure shown in FIG. 5, the "bright" on one line all the liquid crystal cells as X ₁ row and X ₂ rows when the write (of the liquid crystal display ○ ), And when writing "dark" (LCD display ●)
The drive waveform of is shown. More specifically, (a) is the data voltage, the thick line shows the applied waveform in the X ₁ column, the dotted line shows the applied waveform in the X ₂ column, and (b) and (c) are the applied waveforms in the Y ₁ row of the scan voltage. and Y is a _second line of the applied waveform, showing the (d) of the cell applied voltage, thick line voltage waveform applied liquid crystal cell alpha, the applied voltage waveform of the dotted line liquid crystal cell beta.

In the conventional driving method, the voltage averaging method shown in FIG. 7 is adopted, and the first cycle is selected during one frame, and the second cycle is selected in the next frame. The one in which the first cycle and the second cycle are switched every few lines has been put into practical use, and a high-reliability drive that does not deteriorate the panel characteristics is realized by preventing the direct current component from being applied to the liquid crystal cell.

[Problems to be Solved by the Invention]

By the way, in the above-mentioned conventional example, the display of the five liquid crystal cells A to E in the row (for example, Y ₄ row) selected at a certain time T ₁ is “○ ●●●●”, and the selection is made at the next time T ₂ . Consider the case where the line (for example, Y ₅ line) is displayed as "● ○○○○". At this time, since the liquid crystal panel has the electrode resistance R and the liquid crystal cell capacitance C, the equivalent circuit of the Y ₁ row is as shown in FIG. Considering the case of changing from a certain time T ₁ to a time T ₂ , the voltage applied to each of the data electrodes X _{1 to} X ₅ and the scan electrode Y ₁ is as shown in FIG. 9 (the data electrode is X ₁ , X ₂ only).

That is, when changing from a certain time T ₁ to a time T ₂ ,
Since there is a difference in the number of liquid crystal cells from "bright" display to "dark" display and from "dark" display to "bright" display, a current that neutralizes this display difference flows, but when viewed from the scan electrode side, for the number of liquid crystal cell polarity change is unbalanced, not completely be subtracted in the neutralization current only between cells, it will be current and out in accordance with the voltage polarity at the output of the scan driver, the time from time T ₁ voltage of the scan electrodes Y ₁ as shown in FIG. 9 during the change to T ₂ is changed.

As a result of such differential pulse appearing in the scan voltage, the voltage waveform (X ₁ -Y ₁ ) applied to the liquid crystal cell A and the voltage waveform (X ₂ -Y ₁ ) applied to the liquid crystal cell B are There is a problem that it becomes dull or rises.

This problem will be described with a specific example. For example, if there is a liquid crystal display panel of 5 × 8 dots and it has a display pattern as shown in FIG. 10, cell A in the first row,
Focusing on the drive waveforms of the cell B, the voltage waveforms of the data electrodes X ₁ and X ₂ and the scan electrode Y ₁ , and the cells A and B constituting the cells are as shown in FIG. As can be seen from this figure, cell A and cell B are both written in the "bright" state.
And, there is a difference in the effective value of the cell voltage, which causes a luminance difference (cell A is brighter), that is, so-called crosstalk.

To prevent this, a differential pulse detection circuit is provided on the power supply line to a certain scan electrode, and this circuit generates a distorted waveform (differential pulse) corresponding to that detection pulse and feeds back negatively to the power supply circuit. A driving method for suppressing the distortion of the cell applied voltage waveform due to the differential pulse which is the main cause of the uneven brightness has already been proposed. The detection example of the differential pulse will be described in a little more detail. This is detected as a potential difference between one output of the scan driver and the output of a circuit (not connected to the liquid crystal panel) that generates the same waveform as this.

According to this driving method, uneven brightness can be solved in principle, but in actual driving, the scan electrode itself is driven by a pulse with a large amplitude at the time of selection or switching of the polarity of the driving voltage. There is a problem that erroneous waveform distortion due to the influence is detected, and this becomes an error, which makes it difficult to completely prevent uneven brightness.

In view of the above conventional circumstances, the present invention provides a driving method capable of completely suppressing the occurrence of luminance unevenness (crosstalk) due to a differential pulse induced in a scan electrode in a simple matrix type liquid crystal display device. The purpose is to provide.

[Means for solving the problem]

In order to achieve the above object, the present invention counts the number of on-displays or the number of off-displays of liquid crystal cells on each scan electrode in driving a simple matrix liquid crystal display panel, and counts the count value as the count value. It is characterized by differentiating a proportional DC voltage and synthesizing the differentiated pulse output with the opposite polarity to the voltage applied to the non-selected scan electrodes or with the same polarity as the voltage applied to the data electrodes.

FIG. 1 is a block diagram for realizing such driving. In the figure, 3 is a simple matrix type liquid crystal panel, in which a driver 1 is provided for the data electrode and a scan electrode,
2 is connected. A power supply circuit 4 supplies positive and negative on-display voltages and off-display voltages to the data driver 1 and the scan driver 2. Reference numeral 5 is a control means, which outputs a polarity inversion signal DF for each frame, for example, to invert the polarity of the voltage applied to the electrodes of the drivers 1 and 2.

Reference numeral 6 denotes a logic conversion circuit, which relates to an ON display signal and an OFF display signal in the display data XD sent from the control means 5 in a line unit. For example, in the positive voltage application mode, the ON display signal is a logic 1 and an OFF display signal. On the contrary, in the negative voltage application mode, the ON display signal is logically converted to the logic 0, and the OFF display signal is logically converted to the logic 1.

Reference numeral 7 is a distortion amount detection circuit, which counts the number of signals of logic 1 from the logic conversion circuit 6.

Reference numeral 8 is a distorted waveform generation circuit, which generates a DC voltage proportional to the count value and further differentiates it to generate a differential pulse.

9 and 10 are feedback circuits provided with only one of them in practical use. The feedback circuit 9 reverses the polarity of the differential pulse from the distorted waveform generating circuit 8 and turns off the power supply circuit 4 to the scan driver 2. Combined with the display voltage, the feedback circuit 10 uses the same differentiated pulse as the power supply circuit 4 with the same polarity.
Are combined with each voltage for ON display and OFF display to the data driver 1.

[Action]

With the above configuration, the number of ON display cells (logic 1 signal) on the selected scan electrode during the positive voltage application mode period and the OFF display cell (logic 1 signal) during the negative voltage application mode period for each line selection The number is counted by the distortion amount detecting circuit 8, and the distortion waveform generating circuit 8 outputs a DC voltage proportional to the count value and a differential pulse thereof.

Specifically, for example, assuming that a certain line of a liquid crystal panel having one line of 640 liquid crystal cells is driven in the positive voltage application mode period, the immediately preceding line has n number of ON display cells (640-n). In the current selection line, n1 of n cells are changed from off display to off display, and n2 of (640-n) cells are changed from off display to on display in the currently selected line. It is assumed that the number is (n−n1 + n2). In this case, the output DC voltage of the distorted waveform generation circuit 8 is
The voltage changes from nV to (n-n1 + n2) V, and the differential pulse appears as a distorted waveform with a peak value corresponding to the DC voltage of the change. For example, when the number of display-on cells increases, it becomes a positive voltage, and conversely, when it decreases, it becomes a negative voltage.

In this differential pulse, the peak value of the differential pulse induced in the scan electrode, which is the main cause of distortion of the waveform applied to the liquid crystal cell, is displayed from on (logic 1) to off (logic 0) during, for example, the positive voltage application mode period. ) Is determined by the difference between the number of data changed to) and the number of data changed from off display to on display. Therefore, this is made equivalent to the scan driver 2 of the power supply circuit 4, for example. By synthesizing the off display voltage of with the relationship of the reverse polarity,
The differential pulse induced on the scan electrode side is canceled. As a result, in addition to the distortion, incorrect waveform disturbances are introduced as in the previously proposed drive method that detects differential pulses directly from the potential difference between the pulse-driven scan electrode and the data electrode to prevent uneven brightness. Since it is not included, the distortion of the cell applied waveform is completely suppressed, a more complete countermeasure effect is obtained, and high quality display can be realized.

〔Example〕

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

FIG. 2 is a diagram showing the configuration of the first embodiment of the present invention. A data driver 1 is connected to the data electrodes X _{1 to} X _n of the liquid crystal panel 3, and a scan driver 2 is connected to the scan electrodes Y _{1 to} Y _m .

The data driver 1 is provided with a serial-in / parallel-out type shift register (not shown) that latches the display signal XD for one line, and the power supply circuit 4 supplies voltages V [V ₁ ] and (1-2 / a) V [V ₃ ], (2 / a) V [V ₄ ],
And 0 [V ₆ ] are applied. In addition, the scan driver 2 includes V [V ₁ ] and (1-1 / a) V from the power supply circuit 4.
Each potential of [V ₂ ], (1 / a) V [V ₅ ] and 0 [V ₆ ] is applied.

A liquid crystal controller 15 is connected to the data driver 1 and the scan driver 2.
Reference numeral 15 denotes X data (display signal) XD which is liquid crystal panel display data for the data driver 1 and the scan driver 2 in response to a command from a control device such as a personal computer 19.
And Y data (scanning signal) YD. Then, the data driver 1 and the scan driver 2 respond to the X data and the Y data from the liquid crystal controller 15 according to the liquid crystal panel 3
One of the above-mentioned voltages from the power supply circuit 4 is selected and applied to each of the data electrodes X _{1 to} X _n and each of the scan electrodes Y _{1 to} Y _m .

For example, in the positive voltage application mode in which the liquid crystal panel 3 is driven by a positive voltage, the data driver 1 selects the voltage V on the data electrode selected on the basis of the X data XD (on display) and does not select (off display). A voltage (1-2 / a) V is applied to the data electrode, while the scan driver 2 sets 0 to the scan electrode selected based on the Y data YD and (1-1 / a) to the non-selected scan electrode. a) Apply V voltage. Further, in the negative voltage application mode in which the liquid crystal panel 3 is driven by the negative voltage, the data driver 1 sets the selected data electrode to 0 and the non-selected data electrode to the voltage (2 /
a) The voltage of V is applied, and the scan driver 2 applies the voltage V to the selected scan electrode and the voltage (1 / a) V to the non-selected scan electrode. In this embodiment, the ON display voltage from the data driver 1 causes the "bright" write state, and the OFF display voltage causes the "dark" write state.

The liquid crystal controller 15 has an output terminal 151 of a frame signal (polarity inversion signal) DF whose polarity is inverted each time data of one frame (one screen) of the liquid crystal panel 3 is sent.
This polarity inversion signal DF is used as a data driver 1, a scan driver 2, and an inverter 61 that constitutes a logic conversion circuit 6 described later.
Respectively. The data driver 1 and the scan driver 2 alternately switch the voltage application mode in the order of the positive voltage application mode and the negative voltage application mode by the signal DF.

Here, consider a case where the liquid crystal controller 15 has sent out the data of the first line. The X data XD among them is simultaneously input to the data driver 1 and the logic conversion circuit 6, the data driver 1 latches it for a predetermined time, and the logic conversion circuit 6 uses the ON display signal and the OFF display signal therein as a predetermined reference. Logically convert with. That is, the logic conversion circuit 6 includes an inverter 61 and an exclusive OR gate 62, and
The polarity inversion signal DF is input to 61, and the inverter output and the X data XD are input to the exclusive OR gate 62. Since the polarity inversion signal DF is inverted by the inverter 61, the X data XD of the first line input to the exclusive OR gate 62 is
The logic as it is, for example, the ON display signal is output as a logic 1 and the OFF display signal is output as a logic 0. In the negative voltage application mode period, on the contrary, the ON display signal is output as a logic 0 and the OFF display signal is output as a logic 1.

The distortion amount detection circuit 7 is composed of a counter, and inputs the data synchronization signal DCLK from the liquid crystal controller 15 as a clock signal, while inputting the logic signal XD 'from the logic conversion circuit 6 to the enable terminal EN. When the output of the conversion circuit 6 is logic 1, the data synchronization signal is counted. The counter is further provided with an initialization terminal RST, to which a scan synchronization signal (a signal for synchronizing the scan electrode drive) SSYNC sent from the liquid crystal controller 15 is input, and every scan drive period The count value is set to the initial 0 state. In short, the counter
Reference numeral 62 counts the number of ON display signals (logic 1) in the positive voltage application mode period and the number of OFF display signals (logic 1) in the negative voltage application mode period.

The distorted waveform generating circuit 8 includes a D / A converter 81 and a differentiating circuit 82. The D / A converter 81 generates a DC voltage Vd corresponding to the digital count value of the counter 7. Differentiator circuit 82
Is composed of a capacitor and a resistor and differentiates the DC voltage Vd to generate a differential pulse DP. This differential pulse DP is, as described in the above [Action] section, the differential pulse induced on the scan electrode, which is the main cause of the distortion of the liquid crystal cell applied waveform,
The waveforms have the same polarity and almost the same crest value.

The feedback circuit 9 combines the inverter 91 for inverting the polarity of the differentiated pulse DP and its inverter output DP ′ with the _two voltages V ₂ and V ₅ of the power circuit 4 via the feedback path 92, respectively. It is composed of adder circuits 93 and 94. The voltages of the power supply V ₂ and the power supply V ₅ are supplied to the scan driver 2 as an off display voltage and further applied to the non-selected scan electrodes other than the currently selected first scan electrode via this driver. It

Therefore, at this time, the data voltage corresponding to the first line is simultaneously applied to all the data electrodes through the data driver 1, and the differential pulse is induced in the scan electrodes accordingly, and the differential pulse is applied to the non-selected scan. It is canceled by the differential pulse DP 'superimposed on the electrodes for OFF display. As a result, distortion of the cell applied waveform is suppressed.

The effect of suppressing the waveform distortion will be described in more detail with reference to the drive waveform of FIG. The waveform of each part of the circuit is shown in FIG. This figure is the frame A of the drive waveform of FIG. 11 described above.
Corresponding to the frame B, the broken line shows itself, and the solid line shows the waveform after the present embodiment is adopted.

That is, this drive waveform shows the drive periods of the liquid crystal cells A and B in the positive voltage application mode and the negative voltage application mode in the display pattern of FIG. 10, and as can be seen from the solid line waveform, the first frame A (positive voltage application mode). In the application mode period),
The number of ON indicators for each line Y _{1 to} Y ₈ is 5 for each line selection.
Counted in the order of one, one, four, one, four, one, four, one, and a DC voltage Vd corresponding to that number is generated, and further corresponding to this change in DC voltage The differential pulse is output. Then, the polarity inversion output DP ′ of this differential output DP
However, for example, as a result of being combined with the OFF display voltage at the time of non-selection for the scan electrode corresponding to the line Y ₁ and canceling the differential pulse induced in the same electrode, the applied waveform of the scan electrode Y ₁ is distorted. It does not appear. Therefore, the waveform distortion does not occur even in the combined waveform of the voltage applied to the scan electrode and the data electrodes X ₁ and X ₂ , that is, the drive waveforms of the liquid crystal cells A and B, and the uneven brightness caused by the waveform distortion is suppressed. Therefore, high quality display can be realized.

In the next frame B (negative voltage application mode period), the only difference is that the number of OFF display cells is counted. After that, the processing is performed in the same manner and the waveform distortion of the cell applied voltage is suppressed.

FIG. 4 is a diagram showing the configuration of the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the feedback circuit 10 omits the inverter and the four adder circuits 102 to 105 are turned on for the data driver 1 not on the scan electrode side but on the data electrode side. This is a point provided on the power supply lines of the voltage sources V ₁ and V ₆ for display and the voltage sources V ₃ and V ₄ for off display. Therefore, the power supply circuit 4 via the return path 101
The differential pulse that is fed back to the scan electrode and the differential pulse that is induced in the scan electrode have the same waveform in both polarity and peak value. Note that other circuit configurations are denoted by the same reference numerals as those in FIG. 2, and the description thereof is omitted.

The differential pulse affects the liquid crystal cell applied voltage at the time of non-selection, and the cell applied voltage at this time is the OFF display voltage V ₂ of the scan driver 2 and the ON display and OFF display voltages of the data driver 1. It is determined by the potential difference between V ₁ and V _3, and the potential difference between the OFF display voltage V _{5 of the} scan driver 2 and the ON display and OFF display voltages V ₆ and V ₄ of the data driver 1. Therefore, in the first embodiment shown in FIG. 2, the differential pulse DP 'having a polarity opposite to that of the differential pulse and the same crest value is added to the OFF display voltages V ₂ and V ₅ of the scan driver 2. In the example, since it is equivalent to adding the differential pulse DP of the distorted waveform generating circuit 8 to the on-display and off-display voltages V ₁ , V ₃ , V ₆ , V ₄ of the data driver 1 as it is, in the first embodiment. By the same operation as described above, uneven brightness can be eliminated, and high quality display can be realized.

FIG. 5 is a diagram showing the configuration of the third embodiment of the present invention. This embodiment is an application example to a liquid crystal display device in which a liquid crystal panel is divided into upper and lower two screens and both screens are simultaneously driven. In this case, as is well known, the data electrode of each screen is a separate data driver 1U. , And the scan electrodes are connected in common to the same scan driver 2 with electrodes of the same rank. Therefore, the differential pulse induced on the scan driver side is a total value of the applied voltages to the data electrodes of the upper and lower screens.

Therefore, in this third embodiment, as shown in FIG. 5, logic conversion circuits 6 and 6'are provided for the upper and lower screens of the liquid crystal panel 3 '.
And distortion amount detection circuits 7 and 7 ′ are individually provided, and an addition circuit 11 having a decoder configuration, a distortion waveform generation circuit 8 and a feedback circuit 9 are commonly provided. However, in operation, the number of on-display cells (the number of off-display cells in the negative voltage application mode period) on the same-order scan electrodes that are simultaneously driven in each screen is counted, and these count values are added and added. A differential pulse corresponding to the value is generated, the polarity is inverted, and this is combined with the off display voltage to the scan driver 2 common to the screens.
As a result, the differential pulse induced on the scan driver side is canceled and the distortion of the cell applied voltage waveform is suppressed.

Also in the application to this screen division type liquid crystal display device, the following modifications can be made in addition to the third embodiment described above.

That is, one is an embodiment in which the third embodiment and the second embodiment are combined, and the differential output of the distorted waveform generating circuit 8 is turned on and off to the respective data drivers 1U and 1D on the upper and lower screens. It is configured to be synthesized with the same polarity.

The other is an example of application to a device in which the scan driver is provided for each screen similarly to the data driver, and in this case, two embodiments can be considered. That is, the configurations of the first and second embodiments are adopted for each drive circuit of the upper and lower screens, and the waveform distortion in each screen is independently suppressed.

Further, as another embodiment, a configuration in which the inverter 91 is omitted in the feedback circuit 9 and the D / A converter 81 of the distorted waveform generation circuit 8 outputs a DC voltage whose polarity is inverted in advance is also applicable.

〔The invention's effect〕

As described above, according to the present invention, it is possible to suppress the occurrence of luminance unevenness (crosstalk) depending on the display pattern in the liquid crystal display device of the simple matrix drive and improve the display quality. There is.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the principle of the present invention, FIG. 2 is a block diagram showing a first embodiment of a driving device according to the present invention, and FIG. 3 is a diagram showing waveforms of respective parts of the first embodiment, FIG. 4 is a block diagram showing a second embodiment of the driving device according to the present invention, FIG. 5 is a block diagram showing a third embodiment of the driving device according to the present invention, and FIG. 6 is a simple matrix type liquid crystal display panel. FIG. 7 is a diagram showing an example of a display pattern, FIG. 7 is a drive waveform diagram of the liquid crystal cells α and β of FIG. 6, FIG. 8 is a diagram showing a voltage averaging method used when driving the liquid crystal panel, and FIG. Is an explanatory view showing the relationship between the display change of the liquid crystal cell and the applied voltage at that time, FIG. 10 is a waveform diagram explaining the change of the cell applied voltage when the applied voltage is changed as shown in FIG. 9, and FIG. 11 is The figure which shows the example of the display pattern of the liquid crystal panel of 5x8 dot, Figure 12 the liquid crystal cell A and B of Figure 11 formerly. It is a drive waveform diagram when driving by a driving method. 1 to 5, 1,1U and 1D are data drivers, 2 is a scan driver, 3 and 3'are liquid crystal panels, 4 is a power supply circuit, 5 is control means, 6 and 6'are logic conversion circuits, 7 and 7'is a distortion amount detection circuit (counter), 8 is a distortion waveform generation circuit, 9 and 10 are feedback circuits, 11 is an addition circuit, 15 is a liquid crystal controller, 19 is a personal computer, 61 and 91 are inverters, and 62 is exclusive oR gate, 81 is D / A converter, the differentiating circuit 82, 92 and 101 the feedback path, the adder circuit 93,94,102~105, X ₁ ~X _n data electrodes, Y ₁ to Y _m scan electrode Are shown respectively.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Kobayashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Kazuhiro Takahara 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Yoshiya Kaneko 1015 Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Hisa Yamaguchi 1015, Kamikodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

(57) [Claims] 1. A liquid crystal is provided between a plurality of intersecting data electrodes and scan electrodes to arrange a plurality of liquid crystal cells in a matrix.
In a liquid crystal display device that drives this liquid crystal cell by applying a voltage from a data electrode and a scan electrode, the number of on-displays or the number of off-displays of the liquid crystal cell on the scan electrode is counted for each scan electrode drive, and the total is counted. The DC voltage proportional to the numerical value is differentiated to generate a differential pulse, and this differential pulse is combined with the reverse polarity of the voltage applied to the non-selected scan electrode, so that the cell capacitance is applied when a voltage is applied to the opposite data electrode. A drive device for a liquid crystal display device, characterized in that distortion of a cell applied voltage waveform caused by a differential pulse induced in a scan electrode via a capacitor is suppressed. 2. A liquid crystal is provided between a plurality of intersecting data electrodes and scan electrodes to arrange a plurality of liquid crystal cells in a matrix.
In a liquid crystal display device that drives this liquid crystal cell by applying a voltage from a data electrode and a scan electrode, the number of on-displays or the number of off-displays of the liquid crystal cell on the scan electrode is counted for each scan electrode drive, and the total is counted. A DC pulse proportional to a numerical value is differentiated to generate a differential pulse, and this differential pulse is combined with the same polarity as the voltage applied to the data electrode, so that when the voltage is applied to the data electrode on the opposite side, the differential voltage is applied via the cell capacitance. A drive device for a liquid crystal display device, characterized in that distortion of a cell applied voltage waveform caused by a differential pulse induced on a scan electrode is suppressed. 3. An array of liquid crystal cells is divided into at least two parts in the array direction of scan electrodes to form two display screens, and a voltage is applied to the data electrodes of each screen from separate data drivers to scan both screens. A voltage is applied to the electrodes at the same time from the scan driver, and the differential pulse is converted into a DC voltage after the sum of the number of on-displays or the number of off-displays of the liquid crystal cells on the scan electrodes simultaneously selected on each display screen is converted. The driving method of the liquid crystal display device according to claim 1 or 2, wherein the driving method comprises a differentiated output.