US 4,958,105 AGranted

Row driver for EL panels and the like with inductance coupling

AssigneeUnited Technologies Corporation

InventorsEdward L. Young, Mohan L. Kapoor

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Abstract

A simplified row driver switching circuit for display panels and the like, including particularly electroluminescent (EL) panels, as well as plasma panels, using inductance coupling between the power supply and the row electrodes. The circuit limits energy transfer to each row electrode of the EL panel through the inductance coupling, minimizing the effects of destructive arcing caused by inter-electrode shorts. The circuit is energy conservative and eliminates the need for, for example, -160 V and +220 V power supplies. Two row driver circuits are disclosed (FIGS. 4 & 6), the latter allowing the row electrodes to be driven to negative, as well as positive, voltages. Inductor(s) (L of FIG. 4; L.sub.1 & L.sub.2 of FIG. 6) are used to store and transfer energy to the row electrode load (C.sub.panel) and then back to the power source (V.sub.in), as various switches are pulsed "on" and released. The same power supply can be used for both the row driver and the column driver (FIG. 7).

Claims15

Dependent claims

In an electrical display panel system, including--

a display panel having row and column electrodes, said panel being capable of displaying indicia thereon in response to appropriate electrical signals to said row and column electrodes from a row driver and column driver, respectively;
at least one electrical power source (V.sub.in);
a column driver connected to a power source capable of electrically driving said column electrodes;
and
an output load, including said row electrodes (C.sub.panel) of said panel, which load is essentially capacitive;
a row driver capable of electrically driving said row electrodes, said row driver being powered by said power source;
and
row switches causing the drive signals from said row driver to be sequentially pulsed to said row electrodes;
the improvement in said row driver comprising:
an inductor being provided between the row driver power source and the row electrode panel load;
a first switch (S.sub.1 of FIG. 4;
S.sub.1 or S.sub.5 of FIG. 6) with unidirectional current flow (D.sub.1 of FIGS. 4 & 6) being connected to one end of said inductor and to a common voltage reference level, with said power source (V.sub.in) being connected to the other end of said inductor;
said first switch when closed allowing said power source to provide a current flow through said inductor, storing electrical energy in it;
a second switch (S.sub.3 of FIG. 4;
S.sub.3 or S.sub.7 of FIG. 6) with unidirectional current flow (D.sub.3 ;
D.sub.3 or D.sub.7) being connected in series between the same end of said inductor as said first switch and the essentially capacitive row electrode load (C.sub.panel) of the panel, which in turn is connected to said common voltage reference level;
the opening of said first switch and closing of said second switch causing the electrical energy in said inductor to be provided to said capacitive row electrode load through said second switch, driving and charging said capacitive row electrode load;
a third switch (S.sub.2 of FIG. 4;
S.sub.2 or S.sub.6 of FIG. 6) with unidirectional current flow (D.sub.2 ;
D.sub.2 or D.sub.6) being connected in series between the same end of said inductor as said first switch and the essentially capacitive row electrode load (C.sub.panel) of the panel;
the opening of said second switch and the closing of said third switch allowing the charged electrical energy in said inductor to be provided back from said capacitive row electrode load to said inductor through said third switch, re-energizing said inductor;
the opening of said third switch allowing the energy in the re-energized inductor to be dumped back to said row driver power source.

19 more elements

A method of improving the row driver for a electrical display panel system, which system includes--

a display panel having row and column electrodes, said panel being capable of displaying indicia thereon in response to appropriate electrical signals to said row and column electrodes from a row driver and column driver, respectively;
at least one electrical power source (V.sub.in);
a column driver connected to a power source capable of electrically driving said column electrodes;
and
an output load, including said row electrodes (C.sub.panel) of said panel, which load is essentially capacitive;
a row driver capable of electrically driving said row electrodes, said row driver being powered by said power source;
and
row switches causing the drive signals from said row driver to be sequentially pulsed to said row electrodes;
comprising the following step(s):
providing an inductor between the row driver power source and the row electrode panel load;
and
providing a first switch (S.sub.1 of FIG. 4;
S.sub.1 or S.sub.5 of FIG. 6) with unidirectional current flow (D.sub.1 of FIGS. 4 & 6) connected to one end of said inductor and to a common voltage reference level, with said power source (V.sub.in) being connected to the other end of said inductor;
closing said first switch, allowing said power source to provide a current flow through said inductor, storing electrical energy in it;
providing a second switch (S.sub.3 of FIG. 4;
S.sub.3 or S.sub.7 of FIG. 6) with unidirectional current flow (D.sub.3 ;
D.sub.3 or D.sub.7) connected in series between the same end of said inductor as said first switch and the essentially capacitive row electrode load (C.sub.panel) of the panel, which in turn is connected to said common voltage reference level;
opening said first switch and closing said second switch, causing the electrical energy in said inductor to be provided to said capacitive row electrode load through said second switch, driving and charging said capacitive row electrode load;
providing a third switch (S.sub.2 of FIG. 4;
S.sub.2 or S.sub.6 of FIG. 6) with unidirectional current flow (D.sub.2 ;
D.sub.2 or D.sub.6) connected in series between the same end of said inductor as said first switch and the essentially capacitive row electrode load (C.sub.panel) of the panel;
opening said second switch and closing said third switch, allowing the charged electrical energy in said inductor to be provided back from said capacitive row electrode load to said inductor through said third switch, re-energizing said inductor;
and
opening said third switch allowing the energy in the re-energized inductor to be dumped back to said row driver power source.

21 more elements

A method of improving the row driver for a electrical display panel system, which system includes--

a display panel having row and column electrodes, said panel being capable of displaying indicia thereon in response to appropriate electrical signals to said row and column electrodes from a row driver and column driver, respectively;
at least one electrical power source;
a column driver connected to a power source capable of electrically driving said column electrodes;
and
an output load, including said row electrodes (C.sub.panel) of said panel, which load is essentially capacitive;
a row driver capable of electrically driving said row electrodes, said row driver being powered by said power source;
and
row switches causing the drive signals from said row driver to be sequentially pulsed to said row electrodes;
comprising the following step(s):
providing an inductor coupling between the row driver power source and the capacitive row electrode panel load, the charging, driving energy for said capacitive row electrode panel load being provided to it only through said inductor coupling;
flowing current through said inductor, storing electrical energy in said inductor;
using said energized inductor to charge up the capacitive row electrode load, driving in sequence the row electrodes;
and
after driving a row electrode, using the charge on the capacitive row electrode load to re-energize the inductor;
and
dumping the energy in the re-energized inductor into the power supply;
reducing the amount of energy consumption of said row driver and limiting the amount of driving energy supplied to the row electrode to that of the inductor.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/282,787Filed 9 Dec 1988
Granted: 18 Sep 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H03K 17/667
The output circuit comprising more than one controlled bipolar transistor: using complementary bipolar transistors
G09G 3/2965
Driving circuits for producing the waveforms applied to the driving electrodes: using inductors for energy recovery
G09G 3/30
Using controlled light sources: using electroluminescent panels
H03K 17/668
The output circuit comprising more than one controlled bipolar transistor: in a symmetrical configuration