Plasma display panel driving apparatus

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a driving apparatus for a plasma display panel (hereinafter called “PDP”) of a matrix display type.

2. Description of the Related Background Art

Various studies have been made on PDPs which are thin flat display devices, and one of those PDPs is a matrix display type of PDP.

FIG. 1

is a diagram showing the constitution of a driving apparatus for the matrix display type of PDP.

In

FIG. 1

, row electrodes Y

1

to Y

n

and row electrodes X

1

to X

n

, each pair of which corresponds to a single one of rows of one screen (the first row to the n-th row), are formed on a PDP

1

. Column electrodes D

1

to D

m

which correspond to the respective columns of one screen (the first column to the n-th column) are formed perpendicular to those row electrodes each with an unillustrated dielectric layer and discharge space provided in between. Each discharge cell corresponding to a single pixel is formed at the intersection of one pair of row electrodes and a single column electrode.

An address driver

2

converts pixel data of individual pixels based on a video signal to pixel data pulses DP

1

to DP

n

whose voltage values correspond to the logic levels of the individual pieces of the pixel data, and applies the pixel data pulses to the column electrodes D

1

-D

m

row by row. A row-X electrode driver

3

generates a reset pulse for initializing the amount of the residual wall charges of each discharge cell and a discharge sustain pulse for maintaining the discharge state of each light-emitting discharge cell to be discussed later, and applies those pulses to the row electrodes X

1

-X

n

.

A row-Y electrode driver

4

, like the row-X electrode driver

3

, generates reset pulses each for initializing the amount of the residual wall charges of the associated discharge cell and discharge sustain pulses each for maintaining the discharge state of each light-emitting discharge cell, and applies those pulses to the row electrodes Y

1

-Y

n

. The row-Y electrode driver

4

also generates priming pulses for reforming the charge particles that are generated in individual discharge cells and scan pulses each for producing charges whose amount corresponds to the pixel data pulse in the associated discharge cell to thereby set a light-emitting discharge cell or a non-emitting discharge cell, and applies those pulses to the row electrodes Y

1

-Y

n

.

FIG. 2

shows the specific constitutions of the row-X electrode driver

3

and the row-Y electrode driver

4

with respect to an electrode X

j

and an electrode Y

j

. The electrode X

j

is the j-th one of the electrodes X

1

-X

n

and the electrode Y

j

the j-th one of the electrodes Y

1

-Y

n

. The part between the electrodes X

j

and Y

j

serves as a capacitor C

0

.

The row-X electrode driver

3

is equipped with two power supplies B

1

and B

2

. The power supply B

1

provides a voltage V

s1

(for example, 170 V), and the power supply B

2

provides a voltage V

r1

(for example, 190 V). The positive terminal of the power supply B

1

is connected via a switching element S

3

to a connection line

11

for the electrode X

j

, with the negative terminal grounded. A switching element S

4

is connected between the connection line

11

and the ground, and a series circuit of a switching element S

1

, a diode D

1

and a coil L

1

and a series circuit of a coil L

2

, a diode D

2

and a switching element S

2

are both connected via a capacitor C

1

to the ground. The end of the diode D

1

on that side of the capacitor C

1

serves as an anode, and the end of the diode D

2

on that side of the capacitor C

1

serves as a cathode. The positive terminal of the power supply B

2

is connected via a switching element S

8

and a resistor R

1

to the connection line

11

, with the negative terminal grounded.

The row-Y electrode driver

4

is equipped with four power supplies B

3

to B

6

. The power supply B

3

provides a voltage V

s1

(for example, 170 V), the power supply B

4

provides a voltage V

r1

(for example, 190 V), the power supply B

5

provides a voltage V

off

(for example, 140 V) and the power supply B

6

provides a voltage V

h

(for example, 160 V; V

h

>V

off

). The positive terminal of the power supply B

3

is connected via a switching element S

13

to a connection line

12

for a switching element S

15

, with the negative terminal grounded. A switching element S

14

is connected between the connection line

12

and the ground, and a series circuit of a switching element S

11

, a diode D

3

and a coil L

3

and a series circuit of a coil L

4

, a diode D

4

and a switching element S

12

are both connected via a capacitor C

2

to the ground. The end of the diode D

3

on that side of the capacitor C

2

serves as an anode, and the end of the diode D

4

on that side of the capacitor C

2

serves as a cathode.

The connection line

12

is connected via a switching element S

15

to a connection line

13

for the positive terminal of the power supply B

6

. The power supply B

4

has a positive terminal grounded and a negative terminal connected via a switching element S

16

and a resistor R

2

to the connection line

13

. The power supply B

5

has a positive terminal connected via a switching element S

17

to the connection line

13

and a negative terminal grounded.

The connection line

13

is connected via a switching element S

21

to a connection line

14

for the electrode Y

j

. The negative terminal of the power supply B

6

is connected via a switching element S

22

to the connection line

14

. A diode D

5

is connected between the connection lines

13

and

14

. A series circuit of a switching element S

23

and a diode D

6

is also connected between the connection lines

13

and

14

. The end of the diode D

5

on that side of the connection line

14

serves as an anode, and the end of the diode D

6

on that side of the connection line

14

serves as a cathode.

The on/off actions of the switching elements S

1

-S

4

, S

8

, S

11

-S

17

and S

21

-S

23

are controlled by a control circuit (not shown). The arrows at the individual switching elements in

FIG. 2

indicate terminals for control signals from the control circuit.

In the row-Y electrode driver

4

, the power supply B

3

, the switching elements S

11

-S

15

, the coils L

3

and L

4

, the diodes D

3

and D

4

and the capacitor C

2

constitute a sustain driver portion, the power supply B

4

, the resistor R

2

and the switching element S

16

constitute a reset driver portion, and the remaining power supplies B

5

and B

6

, switching elements S

13

, S

17

, S

21

and S

22

and diodes D

5

and D

6

constitute a scan driver portion.

The operation of the PDP driving apparatus with the above constitution will now be explained with reference to a timing chart in FIG.

3

. The operation of the PDP driving apparatus consists of a reset period, an address period and a sustain period.

First, in the reset period, the switching element S

23

in the row-Y electrode driver

4

is set on. The switching element S

23

becomes an on state both in the reset period and sustain period. At the same time, the switching element S

8

in the row-X electrode driver

3

is turned on and the switching element S

16

in the row-Y electrode driver

4

is turned on. The other switching elements are off. The on state of the switching element S

8

causes a current to flow from the positive terminal of the power supply B

2

to the electrode X

j

through the switching element S

8

and the resistor R

1

, and the on state of the switching element S

16

causes a current to flow from the electrode Y

j

to the negative terminal of the power supply B

4

through the diode D

5

, the resistor R

2

and the switching element S

16

. The potential of the electrode X

j

gradually increases at the rate specified by the time constant of the capacitor C

0

and the resistor R

1

and becomes a reset pulse RP

x

, and the potential of the electrode Y

j

gradually decreases at the rate specified by the time constant of the capacitor C

0

and the resistor R

2

and becomes a reset pulse RP

y

. The reset pulses RP

x

are simultaneously added to the respective electrodes X

1

-X

n

, and the reset pulses RP

y

are generated for the respective electrodes Y

1

-Y

n

and are simultaneously added to the respective electrodes Y

1

-Y

n

.

The simultaneous addition of those reset pulses RP

x

and RP

y

causes all the discharge cells of the PDP

1

to be excited and discharged, generating charge particles, and a predetermined amount of wall charges are evenly formed in the dielectric layers of the entire discharge cells after the discharging is finished.

After the levels of the reset pulses RP

x

and RP

y

are saturated, the switching elements S

8

and S

16

are turned off before the reset period ends. At the point of time, the switching elements S

4

, S

14

and S

15

are turned on, causing both the electrodes X

j

and Y

j

to be grounded. As a result, the reset pulses RP

x

and RP

y

disappear.

When the address period starts, the switching elements S

14

and S

15

are turned off, the switching element S

23

is turned off and the switching element S

17

is turned on at which time the switching element S

22

is turned on. The on action of the switching element S

17

renders the power supplies B

5

and B

6

in a series-connected state, so that a negative potential indicating the difference between the voltages V

h

and V

off

appears on the negative terminal of the power supply B

6

to be applied to the electrode Y

j

.

In the address period, the address driver

2

converts pixel data of individual pixels based on a video signal to pixel data pulses DP

1

to DP

n

whose voltage values correspond to the logic levels of the individual pieces of the pixel data, and sequentially applies the pixel data pulses to the column electrodes D

1

-D

m

row by row. As shown in

FIG. 3

, pixel data pulses DP

j

and DP

j+1

are respectively applied to the electrodes Y

j

and Y

j+1

.

The row-Y electrode driver

4

sequentially applies priming pulses PP of a positive voltage to the row electrodes Y

1

-Y

n

. The row-Y electrode driver

4

also sequentially applies scan pulses SP of a negative voltage to the row electrodes Y

1

-Y

n

immediately after the application of the respective priming pulses PP and in synchronism with the respective timings of the pixel data pulses DP

1

to DP

n

.

With regard to the electrode Y

j

, in generating the priming pulse PP, the switching element S

21

is turned on and the switching element S

22

is turned off. The switching element S

17

stays on. Consequently, the potential V

off

on the positive terminal of the power supply B

5

is applied as the priming pulse PP to the electrode Y

j

via the switching element S

17

and then the switching element S

21

. After the application of the priming pulse PP, the switching element S

21

is turned off and the switching element S

22

is turned on both in synchronism with application of the pixel data pulse DP

j

from the address driver

2

. As a result, the negative potential on the negative terminal of the power supply B

6

which indicates the difference between the voltages V

h

and V

off

is applied as the scan pulse SP to the electrode Y

j

. In synchronism with the timing at which the application of the pixel data pulse DP

j

from the address driver

2

is stopped, the switching element S

21

is turned on and the switching element S

22

is turned off, causing the potential V

off

on the positive terminal of the power supply B

5

to be applied to the electrode Y

j

via the switching element S

17

and then the switching element S

21

. Thereafter, as in the case of the electrode Y

j

, the priming pulse PP is likewise applied to the electrode Y

j+1

, and the scan pulse SP is applied to the electrode Y

j+1

in synchronism with application of the pixel data pulse DP

j+1

from the address driver

2

, as shown in FIG.

3

.

In the discharge cells related to the row electrode to which the scan pulses SP have been applied, those discharge cells to which the pixel data pulses of a positive voltage have also been applied at the same time discharge and most of the wall charges will be lost. Since no discharging occurs in those discharge cells which have been applied with the scan pulses SP but not the pixel data pulses of a positive voltage, the wall charges remain. At the time, the discharge cells in which the wall charges have remained become light-emitting discharge cells while those from which the wall charges have disappeared become non-emitting discharge cells.

At the transition from the address period to the sustain period, the switching elements S

17

and S

21

are turned off and the switching elements S

14

and S

15

are turned on instead. The switching element S

4

maintains its on state.

In the sustain period, the on state of the switching element S

4

in the row-X electrode driver

3

sets the potential of the electrode X

j

nearly to the ground potential of 0 V. When the switching element S

4

is turned off and the switching element S

1

is turned on, the charges stored in the capacitor C

1

cause the current to reach the electrode X

j

via the coil L

1

, the diode D

1

and the switching element S

1

and flow into the capacitor C

0

, charging the capacitor C

0

. At the time, the potential of the electrode X

j

gradually increases as shown in

FIG. 3

due to the time constant of the coil L

1

and the capacitor C

0

.

Then, the switching element S

1

is turned off and the switching element S

3

is turned on. Consequently, the potential V

s1

on the positive terminal of the power supply B

1

is applied to the electrode X

j

. Then, the switching element S

3

is turned off and the switching element S

2

is turned on, causing the current to flow into the capacitor C

1

from the electrode X

j

via the coil L

2

, the diode D

2

and the switching element S

2

because of the charges stored in the capacitor C

0

. At the time, the potential of the electrode X

j

gradually decreases as shown in

FIG. 3

due to the time constant of the coil L

2

and the capacitor C

1

. When the potential of the electrode X

j

reaches nearly 0 V, the switching element S

2

is turned off and the switching element S

4

is turned on.

Through the above operation, the row-X electrode driver

3

applies a discharge sustain pulse IP

x

of a positive voltage as shown in

FIG. 3

to the electrode X

j

.

At the same time the switching element S

4

is turned on at which the discharge sustain pulse IP

x

disappears, the switching element S

11

is turned on and the switching element S

14

is turned off in the row-Y electrode driver

4

. When the switching element S

14

is on, the potential of the electrode Y

j

is nearly the ground potential of 0 V; however, when the switching element S

14

is turned off and the switching element S

11

is turned on, the charges stored in the capacitor C

2

cause the current to reach the electrode Y

j

via the coil L

3

, the diode D

3

, the switching element S

11

, the switching element S

15

, the switching element S

13

and the diode D

6

and flow into the capacitor C

0

, charging the capacitor C

0

. At the time, the potential of the electrode Y

j

gradually increases as shown in

FIG. 3

due to the time constant of the coil L

3

and the capacitor C

0

.

Then, the switching element S

11

is turned off and the switching element S

13

is turned on. Consequently, the potential V

s1

on the positive terminal of the power supply B

3

is applied to the electrode Y

j

. Then, the switching element S

13

is turned off and the switching element S

12

is turned on, causing the current to flow into the capacitor C

2

from the electrode Y

j

via the diode D

5

, the switching element S

15

, the coil L

4

, the diode D

4

and the switching element S

12

because of the charges stored in the capacitor C

0

. At the time, the potential of the electrode Y

j

gradually decreases as shown in

FIG. 3

due to the time constant of the coil L

4

and the capacitor C

2

. When the potential of the electrode Y

j

reaches nearly 0 V, the switching element S

12

is turned off and the switching element S

14

is turned on.

Through the above operation, the row-Y electrode driver

4

applies a discharge sustain pulse IP

y

of a positive voltage as shown in

FIG. 3

to the electrode Y

j

.

Since the discharge sustain pulses IP

x

and IP

y

are alternately generated and are alternately applied to the respective electrodes X

1

-X

n

and the electrodes Y

1

-Y

n

in the sustain period, as apparent from the above, the light-emitting discharge cells where the wall charges remain repeat discharge emission and maintain the light-emitting state.

The conventional PDP driving apparatus is constructed in such a way that the scan driver portion uses a PMOS FET or NMOS FET as the switching element S

21

and uses an NMOS FET as the switching element S

22

, with the node of the series circuit of those switching elements serving as the output to the electrode Y

j

. In the case, as the on-state resistance of the FET that constitutes the switching element S

21

is high, the driving performance becomes considerably poorer than that of the FET that constitutes the switching element S

22

. Because it is impossible to supply the discharge sustain pulse current from the sustain driver to the electrode Y

j

via the switching element S

21

during the sustain period, the discharge sustain pulse current is supplied to the electrode Y

j

of the PDP through the bypass circuit that has the switching element S

13

. The scheme undesirably leads to a larger circuit scale and a cost increase.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a PDP driving apparatus which is capable of supplying a discharge sustain pulse current to a PDP during the sustain period without increasing the circuit scale.

A PDP driving apparatus according to the present invention, which drives a plasma display panel having plural pairs of row electrodes and a plurality of column electrodes laid perpendicular to the pairs of row electrodes, forming discharge cells at respective intersections of the pairs of row electrodes and the column electrodes, comprises a scan driver for supplying a scan pulse to one of each of the pairs of row electrodes to select a light-emitting discharge cell and a non-emitting discharge cell; and a discharge sustain driver for supplying a discharge sustain pulse to one of each of the pairs of row electrodes to maintain light emission of only the light-emitting discharge cell. The scan driver includes two switching elements having one ends commonly connected to one of each of the pairs of row electrodes in such a way that when the scan driver is activated, a first potential is applied to the other end of one of the two switching elements and a second potential lower than the first potential and equal to a potential of the scan pulse is applied to the other end of the other switching element. The output of the discharge sustain driver is electrically connected to the other end of the other switching element when the discharge sustain driver is activated.

According to the present invention, the discharge sustain pulse output from the discharge sustain driver is supplied to one of each pair of row electrodes via the other switching element.

A PDP driving apparatus according to the present invention, which drives a plasma display panel having plural pairs of row electrodes and a plurality of column electrodes laid perpendicular to the pairs of row electrodes, forming discharge cells at respective intersections of the pairs of row electrodes and the column electrodes, comprising a sustain driver for supplying a discharge sustain pulse to one of each of the plural pairs of row electrodes to permit only a light-emitting discharge to maintain light emission; and a scan driver for supplying a scan pulse to one of each of the pairs of row electrodes to select a light-emitting discharge cell and a non-emitting discharge cell. A drive current from the sustain driver flows in the same path in the scan driver at a charging time and a discharging time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a block diagram illustrating a PDP driving apparatus;

FIG. 2

is a circuit diagram showing the constitution of a conventional driving apparatus;

FIG. 3

is a timing chart for the individual sections of the apparatus in

FIG. 2

;

FIG. 4

is a circuit diagram illustrating one embodiment of the present invention; and

FIG. 5

is a timing chart for the individual sections of the apparatus in FIG.

4

.

FIG. 6

is a circuit diagram illustrating another embodiment of the present invention; and

FIG. 7

is a timing chart for the individual sections of the apparatus in FIG.

6

.

FIG. 8

is a circuit diagram illustrating another embodiment of the present invention; and

FIG. 9

is a timing chart for the individual sections of the apparatus in FIG.

8

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings.

FIG. 4

illustrates the constitution of a PDP driving apparatus according to the present invention, and uses same reference symbols for those components which are the same as the corresponding components of the conventional apparatus shown in

FIGS. 1 and 2

. In the PDP driving apparatus shown in

FIG. 4

, the negative terminal of a power supply B

6

is connected to a connection line

13

connected to a switching element S

15

. The positive terminal of the power supply B

6

is connected to a connection line

14

for an electrode Y

j

via a switching element S

21

, and the negative terminal of the power supply B

6

that is connected to the connection line

13

is also connected to the connection line

14

via a switching element S

22

. A diode D

5

is connected in parallel to the switching element S

21

and a diode D

6

is connected in parallel to the switching element S

22

. The end of the diode D

5

on that side of the connection line

14

serves as an anode, and the end of the diode D

6

on that side of the connection line

14

serves as a cathode.

A power supply B

5

has its positive and negative terminals connected in the opposite manner to that of the conventional apparatus in

FIG. 2

, and generates a voltage V

off

of, for example, 10 to 20 V.

Since the other constitution is the same as that of the conventional apparatus shown in

FIGS. 1 and 2

, its description will not be repeated.

The operation of the PDP driving apparatus of the invention with the above constitution will now be described with reference to a timing chart in FIG.

5

. The operation of the PDP driving apparatus, like that of the conventional apparatus in

FIG. 2

, consists of a reset period, an address period and a sustain period.

First, in the reset period, a switching element S

8

in a row-X electrode driver

3

is turned on and switching elements S

16

and S

22

in a row-Y electrode driver

4

are both turned on. The other switching elements are off. The on state of the switching element S

8

causes a current to flow from the positive terminal of a power supply B

2

to an electrode X

j

through the switching element S

8

and a resistor R

1

, and the on states of the switching elements S

16

and S

22

cause a current to flow from the electrode Y

j

to the negative terminal of a power supply B

4

through the switching element S

22

, a resistor R

2

and the switching element S

16

. The potential of the electrode X

j

gradually increases at the rate specified by the time constant of a capacitor C

0

and the resistor R

1

and becomes a reset pulse RP

x

, and the potential of the electrode Y

j

gradually decreases at the rate specified by the time constant of the capacitor C

0

and the resistor R

2

and becomes a reset pulse RP

y

. The reset pulse RP

x

finally becomes a voltage V

r1

and the reset pulse RP

y

finally becomes a voltage −V

r1

. The reset pulses RP

x

are simultaneously applied to the respective electrodes X

1

-X

n

, and the reset pulses RP

y

are generated for the respective electrodes Y

1

-Y

n

and are simultaneously applied to the respective electrodes Y

1

-Y

n

. The

The simultaneous application of those reset pulses RP

x

and RP

y

causes all the discharge cells of a PDP

1

to be excited and discharged, generating charge particles, and a predetermined amount of wall charges are evenly formed in the dielectric layers of the entire discharge cells after the discharging is finished.

After the levels of the reset pulses RP

x

and RP

y

are saturated, the switching elements S

8

, S

16

and S

22

are turned off before the reset period ends. At the point of time, the switching elements S

4

, S

14

and S

15

are turned on, causing both the electrodes X

j

and Y

j

to be grounded. As a result, the reset pulses RP

x

and RP

y

disappear.

When the address period starts, the switching elements S

14

and S

15

are turned off, and a switching element S

17

is turned on at which time the switching element S

22

is turned on. The on states of the switching elements S

17

and S

22

causes the negative potential −V

off

on the negative terminal of the power supply B

5

to be applied to the electrode Y

j

via the switching element S

17

and then the switching element S

22

.

In the address period, an address driver

2

converts pixel data of individual pixels based on a video signal to pixel data pulses DP

1

to DP

n

whose voltage values correspond to the logic levels of the individual pieces of the pixel data, and sequentially applies the pixel data pulses to column electrodes D

1

-D

m

row by row. As shown in

FIG. 5

, pixel data pulses DP

j

and DP

j+1

are respectively applied to the electrodes Y

j

and Y

j+1

.

The row-Y electrode driver

4

sequentially applies priming pulses PP of a positive voltage to the row electrodes Y

1

-Y

n

. The row-Y electrode driver

4

also sequentially applies scan pulses SP of a negative voltage to the row electrodes Y

1

-Y

n

immediately after the application of the respective priming pulses PP and in synchronism with the respective timings of the pixel data pulses DP

1

to DP

n

.

With regard to the electrode Y

j

, in generating the priming pulse PP, the switching element S

21

is turned on and the switching element S

22

is turned off. The switching element S

17

stays on. Consequently, the power supplies B

6

and B

5

are rendered in a series-connected state via the switching element S

17

, the potential on the positive terminal of the power supply B

6

becomes V

h

−V

off

(e.g., 140 V). The positive potential is applied as the priming pulse PP to the electrode Y

j

via the switching element S

21

.

After the application of the priming pulse PP, the switching element S

21

is turned off and the switching element S

22

is turned on both in synchronism with application of the pixel data pulse DP

j

from the address driver

2

. As a result, the negative potential −V

off

on the negative terminal of the power supply B

5

is applied as the scan pulse SP to the electrode Y

j

via the switching element S

17

and then the switching element S

22

. In synchronism with the timing at which the application of the pixel data pulse DP

j

from the address driver

2

is stopped, the switching element S

21

is turned on and the switching element S

22

is turned off, causing the potential V

h

−V

off

on the positive terminal of the power supply B

6

to be applied to the electrode Y

j

via the switching element S

21

. Thereafter, as in the case of the electrode Y

j

, the priming pulse PP is likewise applied to the electrode Y

j+1

, and the scan pulse SP is applied to the electrode Y

j+1

in synchronism with application of the pixel data pulse DP

j+1

from the address driver

2

as shown in FIG.

5

.

In the discharge cells related to the row electrode to which the scan pulses SP have been applied, those discharge cells to which the pixel data pulses of a positive voltage have also been applied at the same time discharge and most of the wall charges will be lost. Since no discharging occurs in those discharge cells which have been applied with the scan pulses SP but not the pixel data pulses of a positive voltage, the wall charges remain. At the time, the discharge cells in which the wall charges have remained become light-emitting discharge cells while those from which the wall charges have disappeared become non-emitting discharge cells.

When the address period is switched to the sustain period, the switching elements S

17

and S

21

are turned off and the switching elements S

14

and S

15

are turned on instead. The switching element S

4

maintains its on state.

Because the operation of the row-X electrode driver

3

in the sustain period is the same as that of the conventional apparatus shown in

FIG. 2

, the description for the operation will be omitted, except that the row-X electrode driver

3

applies the discharge sustain pulse IP

x

of a positive voltage as shown in

FIG. 5

to the electrode X

j

.

At the same time the switching element S

4

is turned on at which the discharge sustain pulse IP

x

disappears, the switching element S

11

is turned on and the switching element S

14

is turned off in the row-Y electrode driver

4

. When the switching element S

14

is on, the potential of the electrode Y

j

is nearly the ground potential of 0 V; however, when the switching element S

14

is turned off and the switching element S

11

is turned on, the charges stored in a capacitor C

2

cause the current to reach the electrode Y

j

via the coil L

3

, the diode D

3

, the switching element S

11

, the switching element S

15

and the diode D

6

and flow into the capacitor C

0

, charging the capacitor C

0

. At the time, the potential of the electrode Y

j

gradually increases as shown in

FIG. 5

due to the time constant of the coil L

3

and the capacitor C

0

.

Then, the switching element S

11

is turned off and the switching element S

13

is turned on. Consequently, the potential V

s1

on the positive terminal of the power supply B

3

is applied to the electrode Y

j

via the switching element S

13

, the switching element S

15

and the diode D

6

. Then, the switching element S

13

is turned off, the switching element S

12

is turned on and the switching element S

22

is also turned on, causing the current to flow into the capacitor C

2

from the electrode Y

j

via the switching element S

22

, the switching element S

15

, the coil L

4

, the diode D

4

and the switching element S

12

because of the charges stored in the capacitor C

0

. At the time, the potential of the electrode Y

j

gradually decreases as shown in

FIG. 5

due to the time constant of the coil L

4

and the capacitor C

2

. When the potential of the electrode Y

j

reaches nearly 0 V, the switching elements S

12

and S

22

are turned off and the switching element S

14

is turned on.

Through the above operation, the row-Y electrode driver

4

applies a discharge sustain pulse IP

y

of a positive voltage as shown in

FIG. 5

to the electrode Y

j

.

Since the discharge sustain pulses IP

x

and IP

y

are alternately generated and are alternately applied to the respective electrodes X

1

-X

n

and the electrodes Y

1

-Y

n

in the sustain period, as apparent from the above, the light-emitting discharge cells where the wall charges remain repeat discharge emission and maintain the light-emitting state.

FIG. 6

illustrates the structure of a PDP driving apparatus according to another embodiment of the present invention, and uses the same reference symbols as used for those components which are the same as the corresponding components of the conventional apparatus shown in

FIGS. 1 and 2

and the embodiment in FIG.

4

. In the PDP driving apparatus in

FIG. 6

, the positive terminal of the power supply B

6

is directly connected to the connection line

13

and is further connected to the connection line

14

for the electrode Y

j

via the switching element S

21

, and the negative terminal of the power supply B

6

is also connected to the connection line

14

via the switching element S

22

. The diode D

5

is connected in parallel to the switching element S

21

and the diode D

6

is connected in parallel to the switching element S

22

. The end of the diode D

5

on that side of the connection line

14

serves as an anode, and the end of the diode D

6

on that side of the connection line

14

serves as a cathode.

In the PDP driving apparatus in

FIG. 6

, the switching element S

17

and the power supply B

5

both illustrated in

FIG. 2

are not provided.

The power supply B

2

has a negative terminal connected to one end of the switching element S

8

and a positive terminal grounded. The power supply B

4

has a positive terminal connected to one end of the switching element S

16

and a negative terminal grounded. The power supply B

6

provides a voltage V

h

(for example, 10 to 20 V).

Since the other structure is the same as that of the conventional apparatus shown in

FIGS. 1 and 2

, its description will not be given below.

The operation of the thus constituted driving apparatus for the PDP

1

will now be described with reference to a timing chart in FIG.

7

. The drive sequence of this PDP

1

has one cycle consisting of a reset period, an address period and a sustain period.

First, when the sequence enters the reset period, the switching element S

21

in the row-Y electrode driver

4

is turned on, and, simultaneously, the switching element S

8

in the row-X electrode driver

3

and the switching element S

16

in the row-Y electrode driver

4

are turned on. The other switching elements are off during the reset period. The on state of the switching element S

8

causes a current to flow to the negative terminal of the power supply B

2

from the electrode X

j

through the resistor R

1

and the switching element S

8

. The on state of the switching element S

16

cause a current to flow to the electrode Y

j

from the positive terminal of the power supply B

4

through the switching element S

16

, the resistor R

2

and the switching element S

21

. The potential of the electrode X

j

gradually decreases at the rate specified by the time constant of the capacitor C

0

and the resistor R

1

and becomes the reset pulse RP

x

, and the potential of the electrode Y

j

gradually increases at the rate specified by the time constant of the capacitor C

0

and the resistor R

1

and becomes the reset pulse RP

y

. The reset pulses RP

x

are simultaneously applied to the respective row electrodes X

1

to X

n

and the reset pulses RP

y

are likewise simultaneously applied to the respective row electrodes Y

1

to Y

n

.

The simultaneous application of those reset pulses RP

x

and RP

y

causes all the discharge cells of the PDP

1

to be excited for the discharge action, generating charge particles. After the discharging is completed, a predetermined amount of wall charges are evenly formed in the dielectric layers of the entire discharge cells, rendering those cells in a light-emitting discharge state.

After a predetermined time passes and the levels of the reset pulses RP

x

and RP

y

are saturated, the switching elements S

8

and S

16

are turned off. At this point of time, the switching elements S

4

, S

14

and S

15

are turned on, causing both the electrodes X

j

and Y

j

to be grounded. As a result, the reset pulses RP

x

and RP

y

disappear.

Next, the address period starts, in which the address driver

2

selectively forms wall charges with respect to the individual discharge cells based on a video signal, thus generating pixel data pulses DP

1

to DP

m

for setting light-emitting discharge cells or non-emitting discharge cells, and applies the pixel data pulses to column electrodes D

1

-D

m

row by row. As shown in

FIG. 7

, pixel data pulses DP

j

and DP

j+1

are respectively applied to the electrodes Y

j

and Y

j+1

. The row-Y electrode driver

4

sequentially applies scan pulses SP of a negative voltage to the row electrodes Y

1

-Y

n

in synchronism with the respective timings of the pixel data pulses DP

1

to DP

m

.

With regard to the electrode Y

j

, in synchronism with the application of the pixel data pulse DP

j

from the address driver

2

, the switching element S

21

is turned off and the switching element S

22

is turned on. As a result, a negative potential indicating the voltage −V

h

on the negative terminal of the power supply B

6

is applied to the electrode Y

j

as the scan pulse SP. In synchronism with the end of the pixel data pulse DP

j

from the address driver

2

, the switching element S

21

is turned on and the switching element S

22

is turned off, causing the electrode Y

j

to be grounded. Thereafter, as in the case of the electrode Y

j

, the scan pulse SP is likewise applied to the electrode Y

j+1

in synchronism with application of the pixel data pulse DP

j+1

from the address driver

2

, as shown in FIG.

7

.

Of the discharge cells relating to the row electrode to which the scan pulses have been applied, only those discharge cells to which the respective pixel data pulses of a positive voltage have also been applied have a discharge action and the wall charges will be lost. Since no discharging occurs in those discharge cells which have been applied with the scan pulses but not with the respective pixel data pulses of a positive voltage, the wall charges remain. At the time, the discharge cells in which the wall charges have remained become light-emitting discharge cells while those from which the wall charges have disappeared become non-emitting discharge cells.

Then, the sustain period starts in which as the switching element S

4

is turned off and the switching element S

1

is turned on, the current flows to the electrode X

j

via the coil L

1

, the diode D

1

and the switching element S

1

based on the charges stored in the capacitor C

1

, charging the capacitor C

0

. At the time, the potential of the electrode X

j

gradually increases as shown in

FIG. 7

due to the time constant of the coil L

1

and the capacitor C

0

. When a half of the resonance period determined by the coil L

1

and the capacitor C

0

passes, the switching element S

1

is turned off and the switching element S

3

is turned on. Consequently, the potential of the electrode X

j

is clamped to the potential V

s1

on the positive terminal of the power supply B

1

.

After a predetermined time elapses, the switching element S

3

is turned off and the switching element S

2

is turned on, causing the current to flow into the capacitor C

1

via the coil L

2

, the diode D

2

and the switching element S

2

because of the charges stored in the capacitor C

0

, thus charging the capacitor C

1

. At the time, the potential of the electrode X

j

gradually decreases as shown in

FIG. 7

due to the time constant of the coil L

2

and the capacitor C

0

. When a half of the resonance period determined by the coil L

2

and the capacitor C

0

passes (when the potential of the electrode X

j

reaches 0 V), the switching element S

2

is turned off and the switching element S

4

is turned on.

Through the above operation, the row-X electrode driver

3

applies the discharge sustain pulse IP

x

of a positive voltage as shown in

FIG. 7

to the electrode X

j

.

At the same time the switching element S

4

is turned on at which the discharge sustain pulse IP

x

disappears, the switching element S

11

is turned on and the switching element S

14

is turned off in the row-Y electrode driver

4

. When the switching element S

14

is on, the electrode Y

j

is at the ground potential of 0 V; however, when the switching element S

11

is turned on and the switching element S

14

is turned off, the current flows to the electrode Y

j

via the coil L

3

, the diode D

3

, the switching element S

11

, the switching element S

15

and the switching element S

21

based on the charges stored in the capacitor C

2

, charging the capacitor C

0

. At this time, the potential of the electrode Y

j

gradually increases as shown in

FIG. 7

due to the time constant of the coil L

3

and the capacitor C

0

.

When a half of the resonance period determined by the coil L

3

and the capacitor C

0

passes, the switching element S

11

is turned off and the switching element S

13

is turned on. Consequently, the potential of the electrode Y

j

is clamped to the potential V

s1

on the positive terminal of the power supply B

3

. After a predetermined time elapses, the switching element S

13

is turned off and the switching element S

12

is turned on, causing the current to flow into the capacitor C

2

via the diode D

5

, the switching element S

15

, the coil L

4

, the diode D

4

and the switching element S

12

because of the charges stored in the capacitor C

0

, thus charging the capacitor C

2

. At the time, the potential of the electrode Y

j

gradually decreases as shown in

FIG. 7

due to the time constant of the coil L

4

and the capacitor C

0

. When a half of the resonance period determined by the coil L

4

and the capacitor C

0

passes (when the potential of the electrode Y

j

reaches 0 V), the switching element S

12

is turned off and the switching element S

14

is turned on.

Through the above operation, the row-Y electrode driver

4

applies the discharge sustain pulse IP

y

of a positive voltage as shown in

FIG. 7

to the electrode Y

j

.

As apparent from the above, the discharge sustain pulses IP

x

and IP

y

are alternately generated and are alternately applied to the respective row electrodes X

1

-X

n

and row electrodes Y

j

-Y

n

in the sustain period. As a result, the light-emitting discharge cells where the wall charges remain repeat discharge emission and maintain the light-emitting state.

The above-described scan driver uses a PMOS-FET or an NMOS-FET as the switching element S

21

and uses an NMOS-FET as the switching element S

22

, with the node of the series circuit of those switching elements serving as the output to the row electrode Y

j

. The drive current from the second sustain driver is so designed as to flow in the path formed by the parallel-connected switching element S

21

and diode D

5

in the scan driver at the charging time and the discharging time.

When the switching element

21

is constituted of an MOS-FET, the diode D

5

may be constructed by a parasitic diode in the MOS-FET.

Although the above-described embodiment is illustrated to take such a structure that the output of the second sustain driver is connected to the positive terminal of the power supply B

6

of the scan driver (the other end of the switching element S

21

), it may have such a structure that the output of the second sustain driver is connected to the negative terminal of the power supply of the scan driver (the other end of the switching element S

22

).

FIG. 8

illustrates the structure of a PDP driving apparatus according to a further embodiment of the present invention, and uses the same reference symbols as used for those components which are the same as the corresponding components of the conventional apparatus shown in

FIGS. 1 and 2

and the embodiment in FIG.

4

. In the PDP driving apparatus in

FIG. 8

, a resistor R

3

is inserted between the connection line

13

and the switching element S

17

of the PDP driving apparatus in FIG.

4

. Further, the power supply B

4

has a positive terminal connected to one end of the switching element S

16

and a negative terminal grounded.

The power supply B

2

has a negative terminal connected to one end of the switching element S

8

and a positive terminal grounded. The power supply B

4

has a positive terminal connected to one end of the switching element S

16

and a negative terminal grounded.

The power supply B

5

provides a voltage V

off

(for example, 10 to 20 V) and the power supply B

6

provides a voltage V

h

(for example, 140 V).

Since the other structure is the same as that of the PDP driving apparatus shown in

FIG. 4

, its description will not be repeated below.

The operation of the thus constituted driving apparatus for the PDP

1

will now be described with reference to a timing chart in FIG.

9

. The drive sequence of this PDP

1

has one cycle consisting of a reset period, an address period and a sustain period as in the case of the driving apparatus in FIG.

3

.

First, when the sequence enters the reset period, the switching element S

8

in the row-X electrode driver

3

is turned on, and, simultaneously, the switching elements S

16

and S

22

in the row-Y electrode driver

4

are turned on. The other switching elements are off. The on action of the switching element S

8

causes a current to flow to the negative terminal of the power supply B

2

from the electrode X

j

through the resistor R

1

and the switching element S

8

. The on action of the switching element S

16

cause a current to flow to the electrode Y

j

from the positive terminal of the power supply B

4

through the switching element S

16

, the resistor R

2

and the switching element S

22

. The potential of the electrode X

j

gradually decreases at the rate specified by the time constant of the capacitor C

0

and the resistor R

1

and becomes the reset pulse RP

x

, and the potential of the electrode Y

j

gradually increases at the rate specified by the time constant of the capacitor C

0

and the resistor R

1

and becomes the reset pulse RP

y

. The potential of the reset pulse RP

x

is saturated to be −V

r1

and the potential of the reset pulse RP

y

is saturated to be V

r1

. The reset pulses RP

x

are simultaneously applied to the respective row electrodes X

1

to X

n

and the reset pulses RP

y

are likewise simultaneously applied to the respective row electrodes Y

1

to Y

n

. The

The simultaneous application of those reset pulses RP

x

and RP

y

causes all the discharge cells of the PDP

1

to be excited for the discharge action, generating charge particles. After the discharging is completed, a predetermined amount of wall charges are evenly formed in the dielectric layers of the entire discharge cells, rendering those cells in a light-emitting discharge state.

After a predetermined time passes and the levels of the reset pulses RP

x

and RP

y

are saturated, the switching elements S

8

and S

16

are turned off before the end of the reset period. At this point of time, the switching elements S

4

, S

14

and S

15

are turned on, causing both the electrodes X

j

and Y

j

to be grounded. As a result, the reset pulses RP

x

and RP

y

disappear.

When the address period starts, the switching elements S

14

and S

15

are turned off, the switching elements S

17

and S

21

are turned on and at the same time the switching element S

22

is turned off. The on actions of the switching elements S

17

and S

21

cause a positive potential (V

h

−V

off

) to be applied to the electrode Y

j

.

In the address period, the address driver

2

selectively forms wall charges with respect to the individual discharge cells based on a video signal, thus generating pixel data pulses DP

1

to DP

m

for setting light-emitting discharge cells or non-emitting discharge cells, and applies the pixel data pulses to column electrodes D

1

-D

m

display line by display line. As shown in

FIG. 9

, pixel data pulses DP

j

and DP

j+1

are respectively applied to the electrodes Y

j

and Y

j+1

.

In synchronism with the application of the pixel data pulse DP

j

from the address driver

2

, the switching element S

21

is turned off and the switching element S

22

is turned on. Consequently, a negative potential indicating the voltage −V

off

on the negative terminal of the power supply B

5

is applied to the electrode Y

j

as the scan pulse SP via the switching element S

22

. In synchronism with the end of the pixel data pulse DP

j

from the address driver

2

, the switching element S

21

is turned on and the switching element S

22

is turned off, causing the predetermined positive potential (V

h

−V

off

) to be applied to the electrode Y

j

. Thereafter, as in the case of the electrode Y

j

, the scan pulse SP is likewise applied to the electrode Y

j+1

in synchronism with application of the pixel data pulse DP

j+1

from the address driver

2

, as shown in FIG.

9

.

Of the discharge cells relating to the row electrode to which the scan pulses have been applied, only those discharge cells to which the respective pixel data pulses of a positive voltage have also been applied have a discharge action and the wall charges will be lost. Since no discharging occurs in those discharge cells which have been applied with the scan pulses but not with the respective pixel data pulses of a positive voltage, the wall charges remain. At the time, the discharge cells in which the wall charges have remained become light-emitting discharge cells while those from which the wall charges have disappeared become non-emitting discharge cells.

At the transition to the sustain period from the address period, the switching elements S

17

and S

21

are turned off and at the same time, the switching elements S

14

, S

15

and S

22

are turned on. It is to be noted that the switching element S

1

maintains the on state.

Since the operation of the row-X electrode driver

3

in the sustain period is the same as that of the apparatus shown in

FIGS. 1 and 2

, the operational description will not be repeated except that the row-X electrode driver

3

applies the discharge sustain pulse IP

x

of a positive voltage as shown in

FIG. 9

to the electrode X

j

.

At the same time the switching element S

4

is turned on at which the discharge sustain pulse IP

x

disappears, the switching element S

11

is turned on and the switching element S

14

is turned off in the row-Y electrode driver

4

. When the switching element S

14

is on, the electrode Y

j

is at the ground potential of 0 V; however, when the switching element S

11

is turned on and the switching element S

14

is turned off, the current flows to the electrode Y

j

via the coil L

3

, the diode D

3

, the switching element S

11

, the switching element S

15

and the diode D

6

based on the charges stored in the capacitor C

2

, charging the capacitor C

0

. At the time, the potential of the electrode Y

j

gradually increases as shown in

FIG. 9

due to the time constant of the coil L

3

and the capacitor C

0

.

When a half of the resonance period determined by the coil L

3

and the capacitor C

0

passes, the switching element S

11

is turned off and the switching element S

13

is turned on. Consequently, the potential of the electrode Y

j

is clamped to the potential V

s1

on the positive terminal of the power supply B

3

. After a predetermined time elapses, the switching element S

13

is turned off and the switching element S

12

is turned on, causing the current to flow into the capacitor C

2

via the switching element S

22

, the switching element S

15

, the coil L

4

, the diode D

4

and the switching element S

12

because of the charges stored in the capacitor C

0

, thus charging the capacitor C

2

.

At the time, the potential of the electrode Y

j

gradually decreases as shown in

FIG. 9

due to the time constant of the coil L

4

and the capacitor C

0

. When a half of the resonance period determined by the coil L

4

and the capacitor C

0

passes (when the potential of the electrode Y

j

reaches 0 V), the switching element S

12

is turned off and the switching element S

14

is turned on.

Through the above operation, the row-Y electrode driver

4

applies the discharge sustain pulse IP

y

of a positive voltage as shown in

FIG. 9

to the electrode Y

j

.

As apparent from the above, the discharge sustain pulses IP

x

and IP

y

are alternately generated and are alternately applied to the respective row electrodes X

1

-X

n

and row electrodes Y

1

-Y

n

in the sustain period. As a result, the light-emitting discharge cells where the wall charges remain repeat discharge emission and maintain the light-emitting state.

The above-described scan driver uses a PMOS-FET or an NMOS-FET as the switching element S

21

and uses an NMOS-FET as the switching element S

22

, with the node of the series circuit of those switching elements serving as the output to the row electrode Y

j

. The drive current from the second sustain driver is so designed as to flow in the path formed by the parallel-connected switching element S

22

and diode D

6

in the scan driver at the charging time and the discharging time.

When the switching element

22

is constituted of an MOS-FET, the diode D

6

may be constructed by a parasitic diode in the MOS-FET.

As apparent from the above, the present invention can supply the discharge sustain pulse current to the PDP during the sustain period without going through a bypass circuit comprising a switching element, and can thus prevent the circuit scale from increasing.

Number	Date	Country	Kind
10-330638	Nov 1998	JP
11-095231	Apr 1999	JP

Number	Name	Date	Kind
5283556	Ise	Feb 1994	A
5317334	Sano	May 1994	A
5446344	Kanazawa	Aug 1995	A
5448024	Kawaguchi et al.	Sep 1995	A
5541479	Nagakubo	Jul 1996	A
6091380	Hashimoto et al.	Jul 2000	A
6140984	Kanazawa et al.	Oct 2000	A
6144349	Awata et al.	Nov 2000	A
6188374	Moon	Feb 2001	B1

Plasma display panel driving apparatus

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (2)

US Referenced Citations (9)