JP2693238B2 - Driving method of display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a display device such as a high-class drive type capacitive flat matrix display panel (hereinafter referred to as a thin film EL display device).

In the specification and drawings, V _M / 2 is represented as 1/2 V _M for convenience.

2. Description of the Related Art For example, a double-insulation (or three-layer structure) thin film EL device is constructed as follows.

As shown in FIG. ₃ , a strip-shaped transparent electrode 2 made of In ₂ O ₃ is provided in parallel on a glass substrate 1 and, for example,
Y ₂ O ₃ , Si ₃ N ₄ , Al ₂ O _{3 and} other dielectric materials 3, Mn and other activator-doped ZnS EL layer 4, and Y ₂ O ₃ and Si ₃ N as described above
Dielectric material layer 3a such as ₄ , TiO ₂ and Al ₂ O ₃ is sequentially laminated by a thin film technique such as vapor deposition method and sputtering method to a film thickness of 500 to 10000Å to form a three-layer structure, on which the above transparent layer is formed. A strip-shaped back electrode 5 made of Al is provided in parallel in a direction orthogonal to the electrode 2.

Since the thin film EL element has the EL material 4 sandwiched between the dielectric materials 3 and 3A between its electrodes, it can be regarded as a capacitive element in terms of an equivalent circuit. Also, this thin film
The EL element is driven by applying a relatively high voltage of about 200 V, as is apparent from the voltage-luminance characteristics shown in FIG.
This thin-film EL element has features that it emits light with high luminance by an AC electric field and has a long life.

Basic display driving of the above-mentioned thin film EL display device using the thin film EL element as a display panel is performed by using one of the transparent electrode 2 and the back electrode 5 of the thin film EL element as the scanning side electrode and the other as the data side electrode, and the data side electrode. A modulation voltage corresponding to display data for determining light emission / non-light emission is applied to the scanning side electrode, and a writing voltage is applied to the scanning side electrode line-sequentially.

FIG. 5 is a circuit diagram showing a schematic configuration of a conventional example of such a thin film EL display device.

In FIG. 5, the display panel 10 has a light emission threshold voltage V
The thin film EL element of _th (W _w <V _th <V _W −V _M ) is formed. In this figure, the X-direction electrode is the data side electrode, the Y-direction electrode is the scanning side electrode, and only the electrode is displayed.

The scanning-side drive circuits 20 and 30 are drive circuits composed of a high-voltage push-pull driver IC, and are associated with odd-numbered lines and even-numbered lines of the scanning-side electrodes, respectively. These scan side drive circuits 20 and 30 include pull-up switching elements PT _{1 to} PT _i and pull-down switching elements NT _{1 to} NT.
_i, and logic circuits 21 and 31 for controlling on / off of these switching elements are included.

The data side drive circuit 40 is also a high voltage push-pull driver IC
And is associated with the data-side electrode of the display panel 10. The data side drive circuit 40 also includes pull-up switching elements UT _{1 to} UT _j , pull-down switching elements DT _{1 to} DT _j, and a logic circuit 41 that controls on / off of these switching elements.

The switching circuit 50 switches the potential of the pull-down common line commonly connected to all the pull-down switching elements NT _{1 to} NT _i of the scanning side drive circuits 20 and 30 between the negative write voltage −V _W and 0 V. Circuit, which is composed of two switches SW3 and SW4.

The switching circuit 60 sets the potential of the pull-up common line commonly connected to all the pull-up switching elements PT _{1 to} PT _i of the scan side drive circuits 20 and 30 to the positive write voltage.
It is a circuit for switching between V _W + V _M and 0 V, and is composed of two switches SW1 and SW2.

The switching circuit 70 is a circuit for switching the potential of the pull-up common line, which is commonly connected to all the pull-up switching elements UT _{1 to} UT _j of the data side drive circuit 40, between 1/2 V _M and V _M. It is composed of two switches SW5 and SW6 and a capacitor C _M.

FIG. 6 shows a pixel A (scanning side electrode) of the thin film EL display device.
7 is a time chart showing driving of picture elements located at intersections of Y ₁ and data-side electrode X ₂ . The driving of the picture element A will be described below with reference to this time chart.

Here, the drive for applying the positive write voltage to the scan-side electrode is called P drive, and the drive for applying the negative write voltage is called N drive.

When the P drive scanning side electrode Y ₁ is selected, the data side driving circuit 40 pulls up the switching elements UT _{1 to} UT _j according to the display data corresponding to each picture element included in the scanning side electrode Y _1.
And the pull-down switching elements DT _{1 to} DT _j are on / off controlled. That is, the corresponding pull-down switching elements DT _{1 to} DT _j are turned on for the picture element to emit light, and the corresponding pull-up switching elements UT _{1 to} UT _j are turned on for the picture element when emitting light. . Before selecting the scanning side electrode Y ₁ , the switch SW5 is temporarily turned on as shown in FIG. 6 (5), which causes the capacitor C _M
Is charged to 1 / 2V _M. As a result, the potential of the data-side electrode including the pixel to emit light becomes 0V. On the other hand, the potential of the data side electrode including the non-light emitting pixel is first
1 / 2V _M, and the subsequent switch SW6, as shown in FIG. 6 (6) is V _M by being turned on. Therefore, at this time, the voltage of the waveform shown in FIG. 6 (7) is applied to the data side electrode X ₂ corresponding to the picture element A. The solid line in the figure shows the waveform when the picture element A is in the light emitting display, and the broken line shows the waveform when the picture element A is in the non-light emitting display.

On the other hand, when the scanning side electrode Y ₁ is selected, the switch SW 1 is turned on as shown in FIG. 6A, and all the pull-up switching elements PT _{1 to} PT of the scanning side drive circuits 20 and 30 are turned on.
Of _i , only the pull-up switching element PT ₁ corresponding to the scanning-side electrode Y ₁ is turned on, and the other pull-up switching elements are turned off. As a result, at this time, the positive electrode write voltage V _W + V _M is applied only to the scanning side electrode Y ₁ as shown in FIG. 6 (8). As a result, at this time, the voltage having the waveform shown in FIG. 6 (9) is applied to the picture element A with reference to the data side electrode X ₂ . That is, when the picture element A is a light emitting display picture element, the voltage (V _W + V _M ) −0 V = V _W + V _M (the waveform of the solid line in FIG. 6 (9)) is generated, and the picture element A is not In the case of picture elements for light emission display, a voltage of (V _W + V _M ) −V _M = V _W (waveform of broken line in FIG. 6 (9)) is applied.
Thereafter, the switch SW1 is turned off, by a pull-down switching element NT ₁ of the scanning drive circuit 20 corresponding to the scanning electrode Y ₁ is turned on, the write voltage V _W + V _M
Is discharged. Subsequently, as shown in FIG. 6 (2), the switch SW2 is turned on, whereby the pull-up common line potential of the scanning side drive circuits 20 and 30 is switched to 0V. At the same time, all the pull-down switching elements DT _{1 to} DT _{j of} the data side drive circuit 40 are turned on, thereby setting the potentials of all the data side electrodes to 0V. At this time, switch SW6
Is turned off, and then the switch SW5 is turned on temporarily to charge the capacitor C _M with a voltage of 1/2 V _M , and the next selection of the scanning side electrode Y ₂ is performed. In this way, P for the picture elements included in the scanning-side electrode Y ₁ is
The drive ends.

N driving When the scanning side electrode Y ₁ is selected, the data side driving circuit 40 pulls up the switching elements UT _{1 to} UT _j and pulls down switching according to the display data for each picture element included in the scanning side electrode Y _1. The elements DT _{1 to} DT _j are on / off controlled. That is, the corresponding pull-up switching elements UT _{1 to} UT _j are turned on for the picture elements to emit light, and the corresponding pull-down switching elements DT _{1 to} DT _j are turned on for the picture elements to be non-light emitting. To be done. Note that, as shown in FIG. 6 (5), the switch SW5 is temporarily turned on prior to the selection of the scanning-side electrode Y ₁ , so that the capacitor C _M is charged to 1 / 2V _M. As a result, the potential of the data-side electrode including the pixel to be emitted becomes 1/2 V _M first, and then becomes V _M by turning on the switch SW6 as shown in FIG. 6 (6). On the other hand, the potential of the data-side electrode including the non-luminous pixel is 0V. Therefore, at this time, the voltage of the waveform shown in FIG. 6 (7) is applied to the data side electrode X ₂ corresponding to the picture element A. That is, when the picture element A is a light emitting display, the waveform (V _M ) shown by a solid line in the figure is displayed, and when the picture element A is not light emitting display, a waveform (0
V).

On the other hand, when the scanning side electrode Y ₁ is selected, the switch SW 3 is turned on as shown in FIG. 6 (3) and the pull-down switching elements NT _{1 to} NT _{i of the} scanning side drive circuits 20 and 30 are selected.
Among them, only the pull-down switching element NT ₁ corresponding to the scanning-side electrode Y ₁ is turned on, and the other pull-down switching elements are turned off. As a result, at this time, as shown in FIG. 6 (8), the negative writing voltage -V _W is applied only to the scanning side electrode Y ₁ . By this, at this time picture element A
A voltage having the waveform shown in FIG. 6 (9) is applied to the data side electrode X ₂ . That is, when the picture element A is a picture element for light emission display, a voltage of −V _W −V _M = − (V _W + V _M ) (6th
The waveform of the solid line in FIG. 9), and when the pixel A is a non-emission display pixel, the voltage of −V _W −0V = −V _W (the waveform of the broken line in FIG. 6 (9)). Will be applied. After that, the switch SW3 is turned off, and the pull-up switching circuit of the scanning side drive circuit 20 corresponding to the scanning side electrode Y ₁
When PT ₁ is turned on, the writing voltage −V _W is discharged. Subsequently, as shown in FIG. 6 (4), the switch SW4 is turned on, whereby the scanning side drive circuit 20,
The pull-down common line potential of 30 is switched to 0V. At the same time, all the pull-down switching elements DT _{1 to} DT _{j of} the data side drive circuit 40 are turned on, thereby setting the potentials of all the data side electrodes to 0V. At this time, the switch SW6 is turned off, and then the switch SW5 is temporarily turned on to charge the capacitor C _M with the potential of 1/2 V _M , thereby preparing for the next selection of the scanning-side electrode Y _2. . In this way, the N drive is completed for the picture elements included in the scanning side electrode Y ₂ .

By repeating the above P drive and N drive,
For example, as shown in FIG. 6 (9), a voltage having an alternating waveform having symmetrical positive and negative waveforms is applied to the picture element A.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-described conventional thin film EL display device, since the positive voltage V _W + V _M and the negative voltage −V _W are required as the write voltage, these two types of high voltages are required. A multi-transformer TR as shown in FIG. 7 is used to generate the signal. That is, the number of turns from the intermediate dup 7 of the two-time winding of the multi-transformer TR to the one output terminal 8 side and the number of turns to the other output terminal 9 side are made different, and between the intermediate tap 7 and the output terminal 8. Connection point OU between diode D1 and capacitor C1 connected in series
While the positive write voltage V _W + V _M is obtained from T1, the negative write voltage − is generated from the connection point OUT2 between the diode D2 and the capacitor C2 connected in series between the intermediate tap 7 and the output terminal 9.
Got V _W.

By the way, since the characteristics of the display panel 10 of the thin film EL display device (such as the light emission threshold voltage of the picture element) vary slightly depending on the product, the output voltage of the high voltage generation circuit composed of the multi-transformer TR described above is the picture element. It is customary to make fine adjustments according to the light emission threshold genetic pressure of 1. As a result, there arises a problem that the AC drive by the above-mentioned symmetrical waveform is impaired.

That is, by changing the output voltage of the multi-transformer TR, when the positive polarity write voltage becomes n (V _W + V _M ) and the negative polarity write voltage becomes −nV _W , for example, a pixel to be displayed by light emission is displayed. The voltage applied to the
(V _W + V _M ) −0 V = n (V _W + V _M ), while N drive is −nV _W −V _M = − (nV _W + V _M ), and the voltage waveform applied to the pixel is P drive. And N drive are asymmetric. Therefore, a symmetrical waveform that is ideal for a thin film EL element cannot be applied to the display panel 10, and as a result, a burn-in phenomenon or the like occurs in the display panel 10.

Therefore, an object of the present invention is to provide a driving method of a display device capable of performing AC driving with an ideal symmetrical waveform even when two types of writing voltages are obtained by using a multi-transformer or the like.

Means for Solving the Problems According to the present invention, a dielectric layer is interposed between a plurality of scanning side electrodes and a plurality of data side electrodes arranged in a direction intersecting with each other, and a light emitting display / non-light emitting display is provided on the data side electrode. With the corresponding modulation voltage applied, N drive for applying a negative write voltage to the scan side electrode and P drive for applying a positive write voltage are alternately performed for each field to form the scan side electrode. In a method of driving a display device in which a pixel composed of an intersection of electrodes on the data side is AC-driven, voltages V _W and V _M are V _W <V _th <with respect to a light emission threshold voltage V _th of the pixel. When it has a relationship of V _W + V _M , it is -1 / when driving P as the modulation voltage corresponding to the emission display.
A voltage of 1 / 2V _M is applied when driving 2V _M and N, and is 1 / when driving P as a modulation voltage for non-emission display.
By applying a voltage of -1 / 2V _M during 2V _M and N driving, and by applying a voltage of V _W + 1 / 2V _M during P driving and-(V _W + 1 / 2V _M ) during N driving as a write voltage. , ± (V _W + V _M ) in the light emitting display, and ± V _W in the non-light emitting display are applied to the picture elements, and between the P driving period and the N driving period in each field,
For each data side electrode and each scanning side electrode, -1 / 2V _M and 1 / 2V _M
And each voltage are alternately applied with the same polarity with the lapse of time.

Operation According to the present invention, for example, by using a multi-transformer, the positive write voltage V _W + 1 / 2V _M and the negative write voltage − (V
_W + 1 / 2V _M ), the positive write voltage is n by finely adjusting the output voltage of the multi-transformer.
(V _W + 1 / 2V _M ), write voltage of negative polarity is -n (V _W +1/2
Even when the change V _M), the voltage applied to the picture element to be a light-emitting display in P driving _{n (V W + 1 / 2V} M) - (- 1/2
V _M ) = nV _W + (n + 1) 1 / 2V _M , while N drive
n (V _W + 1 / 2V _M ) −1 / 2V _M = − (nV _W + (n + 1) 1 / 2V _M )
And a symmetrical waveform is applied to the picture element.

The voltage applied to the picture element to be non-light emitting display in P driving _{n (V W + 1 / 2V} M) -1 / 2V M = nV W + (n-1) 1/2
On the other hand, it becomes V _M , but in N drive, -n (V _W + 1 / 2V _M )-(-1/2
_{V M) = - (nV M} + (n-1) 1 / 2V M) , and the symmetric waveform is applied to the picture element in this case.

Further according to the present invention, it is clear from the modulation voltage given to the data side electrode X2 shown in FIG. 2 (7) and the write voltage given to the scanning side electrode Y1 shown in FIG. 2 (8). As described above, the data-side electrode and the scanning-side electrode have the same voltage of −1 / 2V _M and 1 / 2V _M between the P drive period and the N drive period in each field. The polarity is given, and the polarity is alternately changed over time. This can prevent the dielectric layer from being left with a voltage of one polarity.

Embodiment FIG. 1 is a circuit diagram showing a schematic configuration of a display device to which a driving method according to an embodiment of the present invention is applied. This display device is a thin film EL display device which uses a thin film EL element having a light emission threshold voltage V _th (V _W <V _th <V _W + V _M ) as a display panel 110. Only the electrodes are shown with the direction electrodes as the data side electrodes and the Y direction electrodes as the scanning side electrodes.

The scanning side driving circuits 120 and 130 are driving circuits composed of high breakdown voltage push-pull driver ICs, and are respectively associated with odd lines and even lines of scanning side electrodes. These scan side drive circuits 120 and 130 include pull-up switching elements PT _{1 to} PT _i and pull-down switching elements NT _{1 to} NT.
_i, and logic circuits 121 and 131 for controlling on / off of these switching elements are included.

The data side drive circuit 140 is also a high voltage push-pull driver I
The drive circuit is composed of C and is associated with the data side electrode of the display panel 110. This data side drive circuit 140
Also in this case, the pull-up switching elements UT _{1 to} UT _j , the pull-down switching elements DT _{1 to} DT _j, and the logic circuit 141 for on / off controlling these switching elements are included. A pull-down common line is commonly connected to all the pull-down switching elements DT _{1 to} DT _j , and a voltage of −1 / 2V _M is always applied to the pull-down common line.

The switching circuit 150 includes the scanning side drive circuits 120 and 130.
The potential of the pull-down common lines connected in common to all the pull-down switching element NT ₁ ~NT _i of negative write voltage - a circuit for switching between (V _W + V _M) to the 0V, 2 two switches It is composed of SW30 and SW40.

The switching circuit 160 includes the scanning side drive circuits 120 and 130.
Is a circuit for switching the potential of the pull-up common line commonly connected to all the pull-up switching elements PT _{1 to} PT _i of the positive write voltage V _W + 1 / 2V _M and 0V,
It is composed of two switches SW10 and SW20.

The switching circuit 170 is a circuit for switching the potentials of the pull-up common lines commonly connected to all the pull-up switching elements UT _{1 to} UT _j of the data side drive circuit 140 between 1 / 2V _M and 0V. Two switches SW50, SW60
It is constituted by such as.

FIG. 2 shows a picture element B (scanning side electrode) of the thin film EL display device.
7 is a time chart showing driving of picture elements located at intersections of Y ₁ and data-side electrode X ₂ . Driving of the picture element B will be described below with reference to this time chart. The case of applying a positive write voltage to the scanning side electrode is called P drive, and the case of applying a negative write voltage is called N drive, which is the same as the case of driving the conventional thin film EL display device. Is.

P drive When the scanning side electrode Y ₁ is selected, the data side driving circuit 140 pulls up the switching elements UT _{1 to} UT in accordance with the display data corresponding to each picture element included in the scanning side electrode Y _1.
j and pull-down switching elements DT _{1 to} DT _j are on
Controlled off. That is, for the picture element to emit light,
The corresponding pull-down switching elements DT _{1 to} DT _j are turned on, and the corresponding pull-up switching elements UT _{1 to} UT _j are turned on for the picture elements which are not to emit light. In addition,
Prior to the selection of the scanning side electrode Y ₁ , the switch SW50 is turned off and the switch SW60 is turned on as shown in FIGS. 2 (5) and (6). At the same time as the selection of the scanning side electrode Y ₁ , the switch SW50 is turned on, It can be switched off with switch SW60. Therefore, the potential of the pull-up common line commonly connected to all the pull-up switching elements UT _{1 to} UT _j is switched from 0V to 1 / 2V _M according to the selection of the scanning-side electrode Y ₁ . As a result, the potential of the data-side electrode including the pixel to emit light is -1 / 2V.
_M, and the potential of the data-side electrode including a picture element and a non-emission becomes 1 / 2V _M. Therefore, at this time, the voltage of the waveform shown in FIG. 2 (7) is applied to the data side electrode X ₂ corresponding to the picture element B. In the figure, the solid line shows the waveform when the picture element B is in the light emitting display, and the broken line shows the waveform when the picture element B is in the non-light emitting display.

On the other hand, when Y ₁ is selected as the scanning side electrode, the switch SW10 is turned on as shown in FIG. 2 (1) and all the pull-up switching elements PT _{1 of the} scanning side drive circuits 120 and 130 are turned on.
Of the ˜PT _i , only the pull-up switching element PT ₁ corresponding to the scanning-side electrode Y ₁ is turned on, and the other pull-up switching elements are turned off. As a result, at this time, the positive writing voltage V _M + 1 / 2V _M is applied only to the scanning side electrode Y ₁ as shown in FIG. 2 (8). As a result, at this time, the voltage having the waveform shown in FIG. 2 (9) is applied to the picture element B with reference to the data side electrode X ₂ . That is, when the picture element B is a light emitting display picture element, (V _M + 1 / 2V _M ) − (− 1/2
V _M ) = V _W + V _M voltage (solid line waveform in Fig. 2 (9))
However, if the picture element B is a non-luminous display picture element, (V _W + 1 /
The voltage of 2V _M ) −1 / 2V _M = V _M (waveform of broken line in FIG. 2 (9)) is applied. After this, switch SW10
Is turned off and the scanning side drive circuit corresponding to the scanning side electrode Y ₁
When the pull-down switching element NT _{1 of} 120 is turned on, the write voltage V _W + 1 / 2V _M is discharged.
Subsequently, as shown in FIG. 2 (2), the switch SW20 is turned on, whereby the pull-up common line potential of the scanning side drive circuits 120 and 130 is switched to 0V. At the same time, all the pull-up switching elements UT _{1 to} UT _{j of} the data side driving circuit 140 are
Is turned on, and switch SW50 is turned off.
60 is switched on, which causes the potential of all data electrodes to be 0V. In this way, the P drive for the picture elements included in the scanning-side electrode Y ₁ is completed.

N drive When the scanning side electrode Y ₁ is selected, the data side driving circuit 140 pulls up the switching elements UT _{1 to} UT in accordance with the display data corresponding to each picture element included in the scanning side electrode Y _1.
j and pull-down switching elements DT _{1 to} DT _j are on
Controlled off. That is, the corresponding pull-up switching elements UT _{1 to} UT _j are turned on for the picture elements to emit light, and the corresponding pull-down switching elements DT _{1 to} DT _j are turned on for the picture elements to be non-luminous. It is said that At the same time, as shown in FIGS. 2 (5) and (6), the switch SW50 is switched from off to on and the switch SW60 is switched from on to off, respectively, and the pull-up common line potential of the data side drive circuit 140 is changed from 0V. Switchable to 1 / 2V _M. as a result,
The potential of the data side electrode including the pixel to be emitted is 1/2 V _M , and the potential of the data side electrode including the pixel to be non-emissive is -1 /
It becomes 2V _M. Therefore, at this time, the voltage of the waveform shown in FIG. 2 (7) is applied to the data side electrode X ₂ corresponding to the picture element B. That is, when the picture element B is a light emitting display, it has a waveform (1 / 2V _M ) shown by a solid line in the figure, and when it is not emitting light, it has a waveform (-1 / 2V _M ) shown by a broken line.

On the other hand, when the scanning side electrode Y ₁ is selected, the switch SW30 is turned on as shown in FIG. 2C, and all the pull-up switching elements PT ₁ to PT ₁ to
Of PT _i , only the pull-up switching element PT ₁ corresponding to the scanning-side electrode Y ₁ is turned on, and the other pull-up switching elements are turned off. As a result, at this time, the negative write voltage − (V _W + 1 / 2V _M ) is applied only to the scanning side electrode Y ₁ as shown in FIG. 2 (8). As a result, at this time, the voltage having the waveform shown in FIG. 2 (9) is applied to the picture element B with reference to the data-side electrode V ₂ . That is,
If the picture element B is a luminous picture element,-(V _W + 1 / 2V _M )
If the voltage of −1 / 2V _M = − (V _W + V _M ) (the waveform of the solid line in FIG. 2 (9)), and if the pixel B is a non-emission display pixel, − (V _W +1 / 2V _M ) − (− 1 / 2V _M ) = − V _W voltage (second
In the figure (9), the broken line waveform is applied. Thereafter, the switch SW30 is turned off, by the pull-up switching element PT ₁ of the scanning side drive circuit 120 corresponding to the scanning electrode Y ₁ is turned on, the writing voltage - (V _W
+ 1 / 2V _M ) is discharged. Then, as shown in FIG. 2 (4), the switch SW40 is turned on, whereby the pull-down common line potential of the scanning side drive circuits 120 and 130 is switched to 0V. At the same time, all the pull-up switching elements UT _{1 to} UT _{j of} the data side driving circuit 140 are turned on, the switch SW50 is turned off, and the switch SW60 is turned on, so that the potentials of all the data side electrodes are set to 0V. It
In this way, the N drive for the picture elements included in the scanning side electrode Y ₁ is completed.

By repeating the above P drive and N drive,
For example, as shown in FIG. 2 (9), a voltage having an alternating waveform having symmetrical positive and negative waveforms is applied to the picture element B.

As shown in FIGS. 2 (7) and 2 (8),
Between the P drive period and the N drive period in each field,
That is, during the period other than the period in which the applied voltage (Y1−X2) of the picture element B is ± (V _W + V _M ) for the light emitting display and ± V _W for the non-light emitting display, FIG. ) And FIG. 2 (8), the data-side electrode X2 and the scanning-side electrode Y1 are applied with voltages of −1 / 2V _M and 1 / 2V _M with the same polarity, and The polarity is alternately changed over time.

In this case, the negative polarity of the write voltage supplied from the switching circuit 150 - the _{(V W + 1 / 2V M} ), and a positive write voltage V _W + 1 / 2V _M supplied from the switching circuit 160, for example, multi When the voltage is generated using a transformer, the output voltage of the multi-transformer is variably set so that the negative write voltage is -n (V _W +1/2).
V _M ), and the positive write voltage changes to n (V _W + 1 / 2V _M ), respectively (n is an arbitrary coefficient close to 1).

At this time, the voltage applied to the picture element to be luminescently displayed is P
In _{driving, n (V W + 1 /} 2V M) - (- 1 / 2V M) = nV W + (n + 1) 1/2
V _M , and in N drive, −n (V _W + 1 / 2V _M ) −1 / 2V _M = − (nV _W + (n + 1) 1 / 2V _M ), and the pixel has positive and negative polarities. An AC waveform whose waveform is symmetric is applied.

Meanwhile, the voltage applied to the picture element to be non-light emitting display in P _{driving, n (V W + 1 /} 2V M) -1 / 2V M = nV W + (n-1) is 1 / 2V _M, also In N drive, -n (V _W + 1 / 2V _M )-(-1/2 V _M ) =-(nV _W + (n-1) 1 / 2V _M ), and in this case also, the pixel has positive polarity. An alternating current waveform having a symmetrical negative waveform is applied. That is, the display panel 110 is always AC-driven by a symmetrical pulse ideal for a thin film EL element, without being affected by changes in the output voltage of the multi-transformer.

In the above embodiments, the case of driving the thin film EL display device has been described, but the present invention is not limited to this and is similarly applicable to other display devices such as a liquid crystal display device in which AC driving is adopted.

As described above, according to the driving method of the display device of the present invention, the voltages V _W and V _M are set with respect to the light emission threshold voltage V _{th of the} picture element.
When V _W <V _th <V _W + V _M , the write voltage during P drive is V _M + 1 / 2V _M , and the write voltage during N drive is − (V _W +1/2
While the V _M), -1 / 2V _M modulation voltage during P drive corresponding to the light emission picture elements, a 1/2 _M when N drive, 1 / 2V modulation voltage corresponding to the non-luminescent pixels at P drive _Since it is set to −1 / 2V _M when driving _M and N, the above two types of write voltage V _M +
Even when 1 / 2V _M , − (V _W + 1 / 2V _M ) is obtained by using, for example, a multi-transformer, the pixel is always of positive polarity and negative polarity without being influenced by the change of the output voltage of the multi-transformer. It can be driven by a voltage having an alternating waveform having a symmetrical waveform.

Further, according to the present invention, between the P driving section and the N driving section in each field, the voltages of −1 / 2V _M and 1 / 2V _M are applied to the data side electrodes and the scanning side electrodes, respectively. Are applied alternately with the same polarity and with the passage of time, so that it is possible to prevent the voltage of one polarity from being continuously applied to the dielectric layer, and thus, such a P driving period and an N driving period are prevented. Even during the period, AC driving is performed, and the life of the dielectric layer can be extended.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of a thin film EL display device to which a driving method according to an embodiment of the present invention is applied, and FIG. 2 shows driving of arbitrary picture elements of the thin film EL display device. Timing chart, Fig. 3 is a partially cutaway perspective view of a thin film EL device, Fig. 4
FIG. 5 is a graph showing voltage-luminance characteristics of a thin film EL element, FIG. 5 is a circuit diagram showing a schematic structure of a conventional thin film EL display device,
FIG. 6 is a timing chart showing driving of arbitrary picture elements of the thin film EL display device, and FIG. 7 is a circuit diagram showing an example of a circuit for generating a write voltage used in the thin film EL display device. 110 …… Display panel, 120,130 …… Scanning side drive circuit, 140
...... Data side drive circuit, 150,160,170 …… Switching circuit

Continuation of the front page (72) Inventor Hisashi Kamide 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture (56) References: SHO 63-131097 (JP, U) SHO 52-136582 ( JP, U)

Claims (1)

(57) [Claims] 1. A dielectric layer is interposed between a plurality of scanning side electrodes and a plurality of data side electrodes arranged in directions intersecting with each other, and a modulation voltage corresponding to light emitting display / non-light emitting display is applied to the data side electrode. In this state, N drive for applying a negative write voltage to the scan side electrode and P drive for applying a positive write voltage are alternately performed for each field, and the intersection of the scan side electrode and the data side electrode is crossed. In a method for driving a display device in which a picture element consisting of 3 is driven by an alternating current, the voltages V _W and V _M are related to the light emission threshold voltage V _th of the picture element by V _W <V _th <V _W + V _M When it has, it is -1 / 2V when driving P as the modulation voltage corresponding to the light emission display.
A voltage of 1/2 V _M is applied when driving _M and N, and a voltage of 1/2 V is applied when driving P as a modulation voltage for non-emission display.
By applying a voltage of -1 / 2V _M when driving _M and N, and by applying a voltage of V _W + 1 / 2V _M when writing P as a write voltage and-(V _W + 1 / 2V _M ) when driving N, A voltage of ± (V _W + V _M ) is applied to the picture element in the light-emission display, and a voltage of ± V _W is applied to the picture element in the non-emission display, and each data-side electrode and each electrode are connected between the P drive period and the N drive period in each field. A driving method for a display device, wherein each voltage of −1 / 2V _M and 1 / 2V _M is alternately applied to the scanning side electrode with the same polarity and with the passage of time.