JP2619083B2 - Driving method of display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method which can be suitably applied to a thin film EL display device called a capacitive flat matrix display pulse or a plasma display device.

FIG. 4 is a block diagram schematically showing a configuration of a conventional thin film EL display device. The display panel 1 is made of a thin film EL element. This thin film EL element is, for example, a double insulating thin film
In the case of an EL device, strip-shaped transparent electrodes are arranged in parallel on a glass substrate, a dielectric material is laminated thereon, and an EL layer is further laminated thereon to form a three-layer structure. And a strip-shaped back electrode extending in a direction orthogonal to the rear surface.

In the display panel 1, the transparent electrodes of the thin-film EL elements are data-side electrodes D1 to D8, and the back electrodes of the thin-film EL elements are scanning-side electrodes S1 to S4.

The data-side switching circuit 2 includes data-side electrodes D1 to D1.
A circuit for individually applying the modulation voltage V _M to D8,
The data-side output port group 3 individually connected to each of the data-side electrodes D1 to D8, and the display data corresponding to each of the data-side electrodes D1 to D8 are received, and the data-side output port group 3 is set in accordance with the display data. And a logic circuit 4 for turning on / off.

The scanning-side switching circuit 5 applies write voltages V _W1 , -V _W2 (V _W1 = V _W2 + V) to the respective scanning-side electrodes S1 to S4 in accordance with the line order.
_M ) is applied to each scanning side electrode S
A scanning-side output port group 6 individually connected to 1 to S4;
A logic circuit 7 for turning on / off the scanning-side output port group 6 in line sequence with the scanning-side electrodes S1 to S4.

Driving circuit 8 is a circuit for generating a high voltage for the display panel 1 driven from a constant reference voltage V _D, the modulation drive circuit for supplying a modulation voltage V _M to the data side output port group 3 9
And a write drive circuit 10 for supplying the write voltages V _W1 , −V _W2 to the scan-side output port group 6.

The drive logic circuit 11 generates various timing signals necessary for driving the display panel 1 based on input signals such as a display data signal D, a data transfer clock CK, a horizontal synchronization signal H, and a vertical synchronization signal V. Circuit.

The basic display driving of the thin film EL display device is such that a period spanning the first and second fields is one cycle, and a modulation voltage V corresponding to display data for determining light emission / non-emission is applied to the data side electrodes D1 to D8. _M , while the scanning electrodes S1 to S4
The is done by providing a write voltage V _W1 in Fig. 1 field, also a write voltage -V _W2 sequentially line in the second field.

This display driving, part write voltage V _W1 corresponding to the pixel A to the scanning electrode S1~S4 the data side electrodes D1~D8 intersect, is superimposed effect or effect of canceling -V _W2 and the modulation voltage V _M occurs, Pixel A has an emission threshold voltage V as an effective voltage.
_th (V _th ≒ V _W2) or more voltage V _W1 or emission threshold voltage V _th or less of the voltage V _W2 is applied, which each pixel by A
Is in a light emitting / non-light emitting state, and a predetermined display is obtained. Therefore, to one pixel A, an effective voltage whose polarity is inverted in each of the first field and the second field is alternately applied, and the thin film is formed with two fields as one cycle.
A symmetrical AC drive which is ideal for the EL element is performed.

In such a thin film EL display device, as a method for performing a driving method i.e. gray scale display to change the brightness of each pixel A in a plurality of stages by changing the pulse width of the modulation voltage V _M to be applied to the data side electrodes D1~D8 , and a pulse width modulation method for controlling the integrated intensity of the effective voltage applied to the pixel a, the amplitude modulation method to control the amplitude of the modulation voltage V _M is known.

FIG. 5 shows a waveform diagram of each voltage applied to an arbitrary pixel A of the display panel 1 in FIG. 4 in the case of the conventional example of gradation display by the pulse width modulation method. FIG. 1A shows the waveforms of the write voltages V _W1 and −V _W2 applied to the scanning electrode S2, and FIG. 5B shows the data electrode D1.
The waveform of the modulation voltage V _M applied to the side, FIG. 5 (3) shows a waveform of the effective voltage applied to the pixel A when based on the scanning electrode S2, respectively.

In the above pulse width modulation method of the conventional example, the voltage waveform obtained by superimposing the lamp voltage of the maximum amplitude V _M to the voltage of the rectangular wave in order to facilitate preparative gradient is used as a write voltage.

In this case, in the first field in which the positive write voltage _VW1 is applied to the scanning-side electrode S2, the modulation voltage applied during the application period of the write voltage _VW1 as the gradation luminance to be displayed increases. pulse width of V _M is set much shorter. That is, the modulation rise time is fifth diagram of the voltage V _M as shown in (2) B0 (non-emission) from B1, B2 ..., B7, ... , B1
As it shifts to 5 (maximum luminance), the area intensity of the effective voltage gradually increases as shown in FIG. 5 (3).
Note that the solid line in FIG. 5 (3), the rise time of the modulation voltage V _M corresponds to the case of the maximum luminance of B15.

On the other hand, the negative writing voltage -V is applied to the scanning side electrode S2.
In the second _{field W2} is applied, the pulse width of the modulation voltage V _M applied between the application period of the write voltage -V _W2 as gradation brightness to be displayed is increased is set correspondingly longer. That is, the fall time of the modulation voltage V _M is the fifth
As shown in FIG. 2B, from B0 (no light emission) to B1, B2,.
.., B15 (maximum luminance), the area intensity of the effective voltage gradually increases as shown in FIG. 5 (3). Note that the solid line in FIG. 5 (3), fall time of the modulation voltage V _M corresponds to the case of the maximum luminance of B15.

SUMMARY OF THE INVENTION However, in the driving method of the above-mentioned thin film EL display device, in any case of a high brightness display even in low-luminance display, the amplitude of the contributing modulation voltage to effective voltage always constant (V _M) Therefore, there is a problem that a large amount of power is required.

Also, since the modulation voltage applied to the data side electrodes is constant voltage V _M of the large amplitude, the data-side electrodes of ordinary ITO (indium tin oxide) a transparent electrode significantly larger line resistance such as, large so that a large current flows by the application of the amplitude of the modulation voltage V _M. As a result, the voltage drop due to the resistance of the data side electrodes increases, both ends of the data side electrodes (end portions of the data side output port group 3 is connected to output the modulation voltage V _M and the opposite side) As a result, there is a problem that a difference occurs in the amplitude of the voltage actually applied, thereby causing a phenomenon such as uneven brightness and deteriorating the display quality.

Therefore, an object of the present invention is to provide a driving method of a display device which can reduce power consumption at the time of low-luminance light emission in gradation display and reduce luminance unevenness caused by application of a modulation voltage.

Means for Solving the Problems The present invention has a dielectric layer interposed between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction crossing each other, and a modulation voltage according to display data is applied to the data electrodes. And a writing method for applying a write voltage to the scanning electrodes for each scanning period in a line-sequential manner to perform a gray scale display, wherein a pair of scanning electrodes forming each pixel is provided. and the data side electrodes, and the write voltage (V _W1), respectively provided to the modulation voltage of the same polarity as the write voltage (V _W1), the write voltage (V _W1) is each scanning period of each scanning electrode to, a rectangular wave having a threshold voltage Vth of the dielectric layer is a single waveform obtained by superimposing the ramp waveform of the maximum value V _M gradually increasing over time from the leading edge of the rectangular wave, the modulation voltage, the It gradually increases with time from the leading edge of the square wave And a method of driving a display device, characterized in that the maximum value is set shorter maximum sequentially delayed to pulse width start timing as the gradation equal staircase to V _M is increased in the ramp waveform.

In addition, the present invention provides a method in which a dielectric layer is interposed between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction intersecting with each other, and a modulation voltage according to display data is applied to the data electrodes, and scanning is performed. In a driving method of a display device in which a writing voltage is applied to each side electrode in each line-sequential scanning period to perform gradation display, a pair of a scanning side electrode and a data side electrode forming each pixel are connected to each other. , A write voltage (V _W1 ) and a modulation voltage having a polarity opposite to that of the write voltage (V _W1 ). The write voltage (-V _W2 ) is applied to the dielectric layer during one scanning period of each scanning side electrode. The modulation voltage is a single rectangular wave having a threshold voltage Vth, and the modulation voltage is gradually delayed as the gradation of the staircase wave that gradually increases with time from the leading edge of the rectangular wave becomes longer to increase the pulse width. Display device characterized by setting Is the driving method.

In addition, the present invention provides a method in which a dielectric layer is interposed between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction intersecting with each other, and a modulation voltage according to display data is applied to the data electrodes, and scanning is performed. In a display device driving method in which a write voltage is applied to each side electrode in each line-sequential scanning period to perform gradation display, a pair of a display side electrode and a data side electrode forming each pixel , A write voltage (V _W1 ) and a modulation voltage are provided for each of a pair of first and second frames. In the first frame, the modulation voltage and the write voltage V _W1 have the same polarity. voltage (V _W1) is the one scanning period of each scanning electrode, a rectangular wave having a threshold voltage Vth of the dielectric layer, the ramp waveform of the maximum value V _M gradually increasing over time from the leading edge of the rectangular wave Is a single waveform with the modulation voltage It is set to be shorter and the pulse width the incrementally over time from the leading edge of the square wave and sequentially delayed start timing as the gradation of the maximum value is equal staircase wave to the maximum value V _M of the ramp waveform increases In the second frame, the modulation voltage and the write voltage (−V _W2 ) have opposite polarities, and the write voltage (−V _W2 ) is set to the threshold voltage Vth of the dielectric layer during one scanning period of each scanning electrode. The modulation voltage is a pulse wave having a longer pulse width by gradually terminating the end timing as the gradation of the staircase wave that gradually increases with time from the leading edge of the rectangular wave becomes higher. This is a method for driving a display device, which is a feature.

According to the first aspect of the present invention, as shown in the first field of FIG. 3, the write voltage _VW1 and the modulation voltage have the same polarity, and this modulation voltage has a higher gradation. as the, since so as to set a short pulse width are sequentially delayed the start timing of the staircase, the voltage applied to the modulation voltage obtained by subtracting from the write voltage V _W1 applied to the dielectric layer is not be high at the time of low brightness Therefore, power consumption is reduced accordingly, and luminance unevenness is reduced. Moreover, the write voltage _VW1 is a single waveform for each scanning period of each scanning side electrode, and therefore, the present invention can be suitably implemented even in a display device having a large number of dots and therefore a short scanning period. .

According to the invention of claim 2, as shown in the second field of FIG. 3, the write voltage -V _W2 and the modulation voltage have opposite polarities to each other, and therefore the write voltage -V _W2.
The sum of _W2 and the modulation voltage is provided to the dielectric layer, and the modulation voltage is
As the gradation becomes higher, the end timing of the staircase wave is sequentially delayed to increase the pulse width. At a low luminance, a high voltage is not applied to the dielectric layer, and the power consumption is reduced. In addition, the present invention can be easily implemented in a display device having a large number of pixels and thus a short scanning period, while reducing luminance unevenness.

According to the third aspect of the present invention, the configuration of the first and second aspects is achieved in the first field and the second field, whereby so-called AC driving of the dielectric layer is performed, and the life of the dielectric layer is extended. can do.

Embodiment FIG. 1 shows a modulation driving circuit 19 in a thin film EL display device to which a driving method according to an embodiment of the present invention is applied (corresponding to the modulation driving circuit 9 in a general thin film EL display device in FIG. 3). FIG. 2 is a circuit diagram showing a specific configuration of FIG. Modulation drive circuit
Reference numeral 19 denotes four switching elements 20, 21, 22, and 23 composed of N-channel MOS transistors, and three capacitors 24, 25, and 2
6 and five diodes 27, 28, 29, 30, 31.

That is, the source of the switching element 20 is grounded,
The drain is connected to the cathode of one diode 30 of the two diodes 28 and 30 connected in series, and the anode of the other diode 28 is connected to the source of the switching element 21 and to the drain of the switching element 21. Connected to input terminal 32. This input terminal 32
Power supply voltage (1/4) of the maximum amplitude V _M of the voltage V _OUT to be output
V _M ) is provided externally.

A diode 2 is connected between the input terminal 32 and the output terminal 33.
7, 29, 31 are connected in series in this order, and diode 27
A capacitor 24 is connected between the cathode of the diode 28 and the anode of the diode 28. The source of the switching element 22 is connected to the cathode of the diode 28, and the drain thereof is connected to the anode of the diode 29.

The capacitor 25 is connected between the cathode of the diode 29 and the anode of the diode 30. The source of the switching element 23 is connected to the cathode of the diode 30, and the drain is connected to the anode of the diode 31.
A capacitor 26 is connected between the drain of the switching element 20 and the cathode of the diode 31.

Other configurations of the thin-film EL display device in this case are the same as those of the general thin-film EL display device shown in FIG. 4, and in the following description, the other circuit portions refer to the thin-film EL display device of FIG. I do.

FIG. 2 is a timing chart showing the operation of the modulation drive circuit 19, and FIG. 2 (1), (2),
(3) and (4) show the waveforms of the signals A, B, C, and D applied to the gates of the switching elements 20, 21, 22, and 23 in FIG. 1 from the driving logic circuit 11 in FIG. 4, respectively. FIG. 2 (5) shows the waveform of the output voltage _VOUT taken out from the output terminal 33.

FIG. 3 is a waveform diagram of each voltage applied to an arbitrary pixel A of the display panel 1 in FIG. 4 in the case of gradation display by the driving method (pulse width modulation method) of this embodiment,
3 (1) shows the waveforms of the write voltages V _W1 and -V _W2 applied to the scanning electrode S2, and FIG. 3 (2) shows the modulation voltage V _M applied to the data electrode D1. FIG. 3 (3) shows the waveform of the effective voltage applied to the pixel A with reference to the scanning side electrode S2.

Next, the gradation display operation of the thin-film EL display device according to the driving method of this embodiment will be described with reference to FIGS.

The modulation driving circuit 19 in FIG. 1 is connected to the data-side output port group 3 of the data-side switching circuit 2 in the thin-film EL display device in FIG. 4 for one scanning period (a period in which a writing voltage is applied to one scanning-side electrode). ), A voltage V _OUT having a step-like waveform as shown in FIG. 2 (5) is applied.

That is, the write voltage V _W1 , −
At the timing when the application of V _W2 starts, the modulation drive circuit 19
Signal A given to the gate of the switching element 20 is an ON signal (high-level signal for turning on the switching element), the switching element 20 is turned on, and the capacitors 24 to 26 are at the voltage V _D (= 1 / 4V _M ). Is charged. The signal A is returned to an off signal (a low-level signal for turning off the switching element).
When the signal B applied to the gate of 21 turns on and the switching element 21 turns on, the output voltage V _OUT becomes a capacitor.
Increases from a level corresponding to the charge voltage V _D of 24 to 26 to a voltage 2V _D obtained by superimposing an input voltage V _D thereto. Subsequently, when the signal C given to the gate of the switching element 22 becomes an ON signal and the switching element 22 is turned on, the output voltage V _OUT further increases by the charge voltage V _{D of the} capacitor 24 to 3 V
_D. Next, when a signal applied to the gate of the switching element 23 becomes an ON signal and the switching element 23 is turned on, the output voltage V _OUT further increases the charge voltage V _{D of the} capacitor 25.
It increases by 4 minutes to 4V _D. When the switching element 20 is turned on again in the next one scanning period, each of the capacitors 24 to
The output voltage V _OUT charged charge is discharged in 26 returns to the original voltage V _D. In this manner, the modulation driving circuit during one scanning period
The output voltage V _OUT output from 19 and applied to the data-side output port group 3 has a step-like waveform as shown in FIG. 2 (5).

In this embodiment, as shown in FIG. 3 (1), the writing voltage V applied to the scanning electrode S2 in the first field.
_W1 is a waveform maximum amplitude square wave emission threshold voltage equivalent is superimposed a ramp waveform V _M, the write voltage -V _W2 of the second field is a square wave of light emission threshold voltage equivalent.

In the data-side output port group 3, the modulation drive circuit 19
Rise timing and fall timing of the output voltage V _OUT that is applied, is set in accordance with the display data supplied from the logic circuit 4 (gradation data), the voltage is applied to the data side electrodes S2 as a modulation voltage.

That is, as shown in FIG. 3B, in the first field, the gradation luminance to be displayed is changed from B0 (non-light emission) to B1, B7, B15.
(Highest luminance), the rising timing, which is the start timing of the output voltage V _OUT , is gradually delayed, that is, the pulse width, which is the duration of the modulation voltage, is set to be gradually narrower. In the second field, as the grayscale luminance increases from B0 to B15, the rising timing, which is the end timing of the output voltage _VOUT , is gradually delayed, that is, the pulse width, which is the duration of the modulation voltage, is set to be gradually wider.

As is apparent from FIG. 3, the write voltage _VW1 in the first field and the modulation voltage have the same polarity. Single write voltage V _W1 is the one scanning period of each scanning electrode, the rectangular wave having a threshold voltage Vth, obtained by superimposing the ramp waveform of the maximum value V _M gradually increasing over time from the leading edge of the rectangular wave This is one waveform. Modulation voltage in the first field, the start timing sequentially delayed as titrated and the maximum value as time elapses from the leading edge of said square wave tone equal staircase to the maximum value V _M of the ramp waveform increases The duration is set short.

In the second field, the write voltage −V _W2 and the modulation voltage have mutually opposite polarities. The write voltage −V _W2 is a rectangular wave having a threshold voltage Vth during one scanning period of each scanning electrode. The modulation voltage is set to have a longer pulse width by gradually delaying the end timing as the gradation of the staircase wave gradually increasing with time from the leading edge of the rectangular wave becomes higher.

The effective voltage applied to the pixel A in the first field is a form obtained by subtracting the waveform of the modulation voltage from the waveform of the writing voltage, and the effective voltage is indicated by a broken line in FIG. The area intensity of the voltage is minimum, and the area intensity of the effective voltage increases as the gradation luminance increases. In the display of B15 (highest luminance), the area intensity of the effective voltage becomes maximum as indicated by the solid line.

The effective voltage applied to the pixel A in the second field has a form in which the waveform of the modulation voltage is superimposed on the waveform of the writing voltage, and is indicated by a broken line in FIG. The area intensity of the effective voltage is minimum, and the area intensity of the effective voltage increases stepwise as the gradation luminance increases, and the area intensity of the effective voltage becomes maximum as indicated by the solid line in the display of B15 (highest luminance). .

In this way, the luminance display according to the display data (grayscale data) is performed. However, since the waveform of the modulation voltage is stepwise, the amplitude of the modulation voltage contributing to the effective voltage is such that the grayscale to be displayed is low. As a result, the power consumption decreases as the luminance becomes lower.

Further, since the waveform of the modulation voltage has a step-like shape, the amplitude of the modulation voltage is reduced accordingly. As a result, the current amount at the data side electrode to which the modulation voltage is applied is reduced, and the resistance of the data side electrode is reduced. , The voltage drop due to the voltage drop is also reduced, and the uneven brightness occurring between both ends of the data side electrode is reduced.

In the above embodiment, the case where the number of steps of the waveform of the modulation voltage is four is described, but the number of steps may be larger or smaller than this.

Further, in the above embodiment, the case of driving the thin-film EL display device has been described. However, the present invention is not limited to this and can be similarly applied to other capacitive matrix displays such as a liquid crystal display device.

As described above, according to the driving method of the display device of the present invention,
Since the modulation voltage applied to the data-side electrode has a step-like shape, the amplitude of the voltage (effective voltage) applied to the pixel, which contributes as the modulation voltage, decreases as the grayscale luminance to be displayed decreases. As a result, power consumption is reduced. Further, since the amplitude of the modulation voltage is suppressed low, the amount of current flowing to the data side electrode is also reduced accordingly, and even when a transparent electrode having a relatively large resistance is used as the data side electrode, the voltage drop due to the resistance is small,
Therefore, uneven brightness between both ends of the data side electrode is reduced accordingly. In particular, according to the first aspect of the present invention, the write voltage _VW1 and the modulation voltage have the same polarity, and therefore, the voltage applied to the dielectric layer is a voltage obtained by subtracting the write voltage _VW1 and the modulation voltage. The modulation voltage is a staircase wave that gradually increases with the passage of time, and the start timing is sequentially delayed as the gradation becomes higher so that the pulse width is set shorter. Is not given a high voltage.

According to the second aspect of the present invention, the write voltage (-V _W2 )
And the modulation voltage are of opposite polarities, so that the sum of the absolute value of the write voltage (-V _W2 ) and the modulation voltage is given to the dielectric layer, and the modulation voltage is a staircase wave that gradually increases over time. Yes, as the gradation becomes higher, the end timing is gradually delayed so that the pulse width is set longer,
According to the present invention, as described above, a high voltage is not applied to the dielectric layer at the time of low luminance.

Further, according to the first and second aspects of the present invention, the write voltages V _W1 and −V _W2 are set to one scan period during each scan side electrode.
A single waveform provided, thus having a large number of pixels, and thus a short scanning period,
The present invention can be easily implemented.

According to the third aspect of the present invention, the first and second pairs forming a pair are provided.
In each of the fields (1) to (4), voltages whose polarities are inverted are applied to the dielectric layers, so that so-called AC driving is performed, and the life of the dielectric layers can be extended.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a specific configuration of a modulation driving circuit in a thin film EL display device to which a driving method according to an embodiment of the present invention is applied, FIG. 2 is a timing chart showing an operation of the modulation driving circuit, FIG. 3 is a waveform chart showing applied voltages at arbitrary pixels of the thin film EL display device according to the driving method.
FIG. 1 is a block diagram showing a schematic configuration of a general thin film EL display device, and FIG. 5 is a waveform diagram showing each voltage applied to an arbitrary pixel of the thin film EL display device by a conventional driving method. 1 ... display panel, 2 ... data side switching circuit,
5 ... Scanning side switching circuit, 8 ... Drive circuit, 11 ...
... Drive logic circuit, 19 ... Modulation drive circuit, D1-D8 ... Data side electrode, S1-S4 ... Scan side electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihiro Oba 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Hisahide 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp shares In-company (56) References JP-A-2-2033387 (JP, A) JP-A-2-15295 (JP, A) JP-A-2-149888 (JP, A) JP-A-63-298285 (JP, A) JP-A-49-79120 (JP, A) JP-A-2-201846 (JP, A) Japanese Utility Model Showa 58-54691 (JP, U)

Claims (3)

(57) [Claims] A dielectric layer is interposed between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction intersecting with each other, and a modulation voltage according to display data is applied to the data electrodes and scanning is performed. In a driving method of a display device in which a writing voltage is applied to each side electrode in each line-sequential scanning period to perform gradation display, a pair of a scanning side electrode and a data side electrode forming each pixel are connected to each other. , a write voltage (V _W1), respectively provided to the modulation voltage of the same polarity as the write voltage (V _W1), the write voltage (V _W1), for each one scanning period of each scanning electrode, the teeth of the dielectric layer A rectangular waveform having a threshold voltage Vth, a single waveform obtained by superimposing a ramp waveform having a maximum value V _{M that} gradually increases with time from the leading edge of the rectangular wave, and a modulation voltage from the leading edge of the rectangular wave. The lamp gradually increases with time and the maximum value The driving method of a display device is characterized in that set a short pulse width are sequentially delayed the start timing as equal staircase waveform grayscale of the maximum value V _M of the form increases. A dielectric layer interposed between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction intersecting with each other to apply a modulation voltage according to display data to the data electrodes and perform scanning. In a driving method of a display device in which a writing voltage is applied to each side electrode in each line-sequential scanning period to perform gradation display, a pair of a scanning side electrode and a data side electrode forming each pixel are connected to each other. , A write voltage (V _W1 ) and a modulation voltage having the opposite polarity to the write voltage (V _W1 ). The write voltage (-V _W2 )
The modulation voltage is a single rectangular wave having a threshold voltage Vth of the dielectric layer, and the modulation voltage is obtained by sequentially delaying the end tamping as the gradation of the staircase wave gradually increasing with time from the leading edge of the rectangular wave becomes higher. A method for driving a display device, wherein a pulse width is set long. 3. A method according to claim 1, further comprising: interposing a dielectric layer between a plurality of scanning electrodes and a plurality of data electrodes arranged in a direction intersecting with each other, applying a modulation voltage corresponding to display data to the data electrodes, and performing scanning. In a display device driving method in which a write voltage is applied to each side electrode in each line-sequential scanning period to perform gradation display, a pair of a display side electrode and a data side electrode forming each pixel , The write voltage (V _W1 ) and the modulation voltage,
In the first frame, the modulation voltage and the write voltage V _W1 have the same polarity, and the write voltage (V _W1 ) is set at every scan period of each scan-side electrode. a rectangular wave having a threshold voltage Vth of the dielectric layer is a single waveform obtained by superimposing the ramp waveform of the maximum value V _M gradually increasing over time from the leading edge of the rectangular wave, the modulation voltage, the rectangular wave The start timing is gradually delayed and the pulse width is set shorter as the gradation of the staircase wave that gradually increases with time and the maximum value of which is equal to the maximum value V _M of the ramp waveform becomes higher from the leading edge of the second frame. The modulation voltage and the write voltage (-V _W2 ) have opposite polarities, and the write voltage (-V _W2 )
The modulation voltage is a single rectangular wave having a threshold voltage Vth of the dielectric layer, and the modulation voltage is obtained by sequentially delaying the end timing as the gradation of the staircase wave gradually increasing with time from the leading edge of the rectangular wave becomes higher. A method for driving a display device, wherein a pulse width is set long.