The present invention generally relates to a driving circuit of an AC driving type capacitive flat/matrix display panel, i.e., thin film EL (electro/luminescence) display.
Conventionally, for example, a double insulating type (or three-layer construction) thin film EL element is, for instance, constructed as shown in FIG. 4. Referring to FIG. 4, band-shaped transparent electrodes 2 made of In.sub.2 O.sub.3 are provided in parallel on a glass base plate 1.A dielectric material 3 such as Y.sub.2 O.sub.3, Si.sub.3 N.sub.4, Al.sub.2 O.sub.3 or the like, an EL layer 4 made of ZnS with activator such as Mn or the like doped therein, and dielectric material layer 3' of Y.sub.2 O.sub.3, Si.sub.3 N.sub.4, TiO.sub.2, Al.sub.2 O.sub.3 or the like are sequentially laminated in a film membrane thickness of 500 through 10000 .ANG. into the three-layer construction by the use of a thin film art such as an evaporation method, or a sputtering method. Band-shaped rear-face electrodes 5 made of Al.sub.2 O.sub.3 are then disposed thereon in parallel in the direction normal to the transparent electrodes 2.
As the thin film EL display has the EL material 4 grasped between the dielectric materials 3, 3', and in turn between the electrodes, it may be considered the capacitive element in terms of an equivalent circuit. Also, the thin film EL element is driven through the application of the comparatively high voltage of about 200 V as clear from the voltage-brightness characteristics shown in FIG. 5. The thin film EL element emits light with high brightness due to application of an AC electric field and exhibits a longer service life.
Conventionally, the switching circuit which discharges the modulation voltage 1/2 V.sub.M of 1/2 into the charging diode and the 0V is connected with each electrode on the data side for such film EL display panel. The Nch MOS driver and the Pch MOS driver are provided as the driving circuit for the scanning-side electrode to perform the field inversion driving operation. Furthermore, the driving circuit for reversing the polarity of the storing waveform to be supplied to the picture element for each of scanning lines, the Pch high-withstand voltage MOS driver for charging the modulation voltage V.sub.M with respect to the EL layer, and the Nch high withstand voltage MOS driver for discharging it into the 0V are connected with each of the data-side electrodes in accordance with the increase in the number of the scanning-side electrodes, so that the driving circuit for performing the charging, discharging operations of the modulation voltage at the same time in accordance with the display data in the data-side electrode during the storing driving operation are proposed.
However, in these propositions, two driver ICs (Nch high withstand-voltage MOS driver IC, Pch high withstand-voltage MOS driver IC and so on) or more were required for one line of the scanning electrode. Also, in order to apply the positive, negative high-voltage pulse into the scanning side electrode, the respective control signals of the Nch high withstand-voltage MOS driver and the Pch high withstand-voltage MOS driver were floated, thus requiring the isolator for each control signal use and the respective floating power supplies (interface circuit for driver control signal use), so that the EL driving apparatus was prevented from becoming thinner, more compact, and lower in price.
USPTO Backgrounds
USPTO Backgrounds