JPH10214056A - Alternating current driving plasma display device and driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the reduction in the luminance caused by the variation of a display rate and the luminance irregularity between lines by connecting X and Y electrodes from the both surfaces of a panel and adding the maintaining and driving circuits of the X and Y electrodes from the both sides. SOLUTION: When a positive pulse is applied to the Y electrode, switching elements 9a and 19a are simultaneously turned ON in two maintaining pulse generators 5a and 5b. Then, a maintaining voltage Vsl goes through diode arrays 3a and 3b and simultaneously applied to all maintaining electrodes Y1 to Yn from the left and the right. In order for the maintaining pulses to fall, the elements 9a and 19a are similarly turned OFF and then, 9b and 19b are turned ON. Similarly, in order to apply maintaining pulses to maintaining electrodes X1 to Xn, switching elements 10a and 20a and 10b and 20b in two maintaining pulse generators 6a and 6b are simultaneously turned ON/OFF and the pulses are applied to both sides of the electrodes. Thus, the voltage drops by electrode resistances are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing unevenness of brightness and gradation of a plasma display which is a so-called memory type.

[0002]

2. Description of the Related Art FIG.
FIG. 9 is a schematic configuration diagram of a conventional plasma display panel disclosed in Japanese Unexamined Patent Application Publication No. H10-260, and FIG. 9 is a diagram of a main driving circuit thereof. In the figure, 1a is a surface discharge / AC drive type plasma display panel, 2 is an address driver, 22 is a sustain electrode driver (X driver), 23 is a scan electrode driver (Y driver), 109a, 341A to 34nA are push switches, 109b , 341B to 34nB are pull switches,
61A to 6nA, 61B to 61nB are diodes, 60
Is a semiconductor integrated circuit.

Next, the operation of the Y driver of the above-configured device during the writing period and the operation during the sustain period will be described. However, the operation of the reactive power recovery circuit is omitted here. In the writing period, only the pull switch 109b is turned on to set the voltage of the scan electrode Y1 to the GND level, and then the pull switch 341B is turned off. Next, the push switch 341A is turned on to return the voltage of Y1 to Vs, and then the push switch 341A is turned off. By these operations, a scanning pulse is applied to Y1. The second
A similar operation is performed for the display rows .about.n. In the maintenance period, the pull switch 109b and the push switch 1
09a to turn on alternately to supply charges from the sustain voltage Vs to the Y1 to Yn through the push switch 109a and the diodes 61A to 6nA, and discharge the charge from the Y1 to Yn to the GND through the diodes 61B to 6nB. Operation is alternately repeated. When the reactive power recovery circuit is used, the current path is slightly more complicated, but the description is omitted because it deviates from the purpose here.

Here, the description of the diodes 61AB to 6nAB will be supplemented. The diode is used to apply two types of pulses having different properties, that is, a scan pulse and a sustain pulse to the same electrode. The scanning pulse is Y1
It is necessary to individually apply to each of the n electrodes, and it is necessary to provide the same number of switch elements as the number of electrodes. However, since power consumption is relatively small, an integrated circuit is usually provided for each of a plurality of outputs. On the other hand, the sustain pulse consumes a large amount of power but may be applied to Y1 to n in common, and is usually generated by a discrete element such as an FET. However, since Y1 to n apply scanning pulses individually, they cannot be commonly connected. Therefore, the sustain pulse and the scan pulse are compatible by applying a sustain pulse in common through a diode without directly connecting Y1 to n.

In the above-mentioned conventional plasma display device, since the sustain discharge pulse is applied from one of the electrodes, the substantial voltage applied to the discharge cell is reduced due to the impedance of the electrode, and the display quality is reduced. . FIG.
This will be described with reference to FIG. FIG. 10 is an electrical equivalent circuit of the sustain electrode and the scan electrode, and can be represented as a distributed constant circuit of the electrode resistance 27 and the capacitance 28 between the electrodes. Usually, the electrode is made of a material having a low resistivity, such as aluminum, copper, or silver. Even when an electrode material having a high resistivity, such as a transparent electrode such as ITO, is used, an electrode made of a material having a low resistivity as described above is used. Are used as bus electrodes to reduce the resistance as much as possible. However, in a high-definition structure such as a PDP, the electrode width cannot be made too large, and a non-negligible resistance component remains. This value depends on the electrode material and width, as well as the electrode length, thickness, forming method, and the like.For example, when a 20-inch-size PDP is used to form an aluminum electrode having a width of about 100 μm by sputtering, It becomes about several hundred Ω per electrode. When a discharge current flows through this electrode, the voltage decreases as the distance from the voltage supply point increases due to the voltage drop due to the electrode resistance. For example, a voltage Vs is applied to the sustain electrode (X) from the left in the figure, and the scanning electrode (Y) is a panel of the potential of each electrode when the right end is kept at 0 V and all the cells on the electrode are turned on. FIG. 11A shows the change due to the upper position. At this time, the voltage actually applied between XY of the cell is lower than the voltage applied from the outside as shown in FIG.

Here, a particular problem is that the luminance reduction rate differs depending on the displayed pattern. FIG.
FIG. 7 shows a change in luminance when the display ratio is changed. FIG.
As shown in (a), when a rectangle having a width W is displayed on a screen having a width H, the display ratio of each display line, that is, the ratio of the lit cells to the total number of cells in this line is W / H.
FIG. 12B shows a change in luminance when the display ratio is changed. As the display ratio increases, the luminance gradually decreases. Such a decrease in luminance occurs for each display line.
Since the display ratio differs for each line, the luminance varies for each line, which leads to a decrease in display quality. Further, in the subfield gray scale method, since the display ratio is different for each subfield, the luminance ratio of the subfield is lost, and the grayscale is disturbed. This means that a discontinuous line of luminance appears as a so-called pseudo contour in a smoothly changing image.

[0007]

The conventional plasma display is constructed as described above, and since the electrodes have a non-negligible resistance, the substantial applied voltage of the push and pull differs depending on the electrode portion, resulting in uneven brightness. Also, there is a problem that display gradation is disturbed. This is because when the size of the display becomes large and the screen is displayed on a large screen, the electrode length becomes long and the display quality is particularly deteriorated. In order to reduce the influence of the electrode resistance, it is possible to adopt a configuration as shown in FIG. 13 in which the electrodes are drawn from both sides of the panel, and two electrode drive circuits are provided and driven simultaneously. However, in this case, there is a problem that a drive circuit is doubled, and in particular, a scan driver is required for each electrode, which leads to an increase in cost and an increase in circuit scale.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a plasma display device and a plasma display driving method which eliminate luminance unevenness and gradation disturbance by adding a relatively small circuit. And

[0009]

An AC-driven plasma display device according to the present invention has a structure in which n independent Y electrodes for sustaining and scanning and an X electrode for sustaining are provided. The electrode is a mechanism connected from both sides of the panel of the plasma display.
It has two sustain drive circuits for each of the electrodes and the Y electrode, and has one scan drive circuit for the Y electrode. These two sustain drive circuits for the X electrode and the Y electrode are respectively provided for the panel. Maintained driving from both sides simultaneously.

Still further, two independent driving circuits for n electrodes for n electrodes are connected to a high-voltage driving source on one side and connected to the respective high electrodes, and the other is connected to each of the Y electrodes. One of the (FET) groups is connected to a low-voltage drive source with one side common, and the other is driven through another FET group connected to the Y electrode.

Still further, instead of the connection from both sides of the panel, either the sustaining X electrode or the sustaining and scanning Y electrode is connected from one side of the panel. The driving circuit includes one sustain driving circuit that drives the one-side connected sustain electrode.

The AC driving type plasma display driving method according to the present invention is a method for driving an AC driving type plasma display having n independent Y electrodes for sustaining and scanning and an X electrode for sustaining. The Y electrodes are configured to be connected from both sides of the panel of the plasma display, a writing step of applying a scanning pulse corresponding to the designated address to the Y electrodes to emit light, and subsequently, simultaneously applying sustain pulses from both sides of the panel to all the Y electrodes. And a maintenance step of alternating application to the X electrode.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. A panel display according to the present invention, which has a relatively small scale and eliminates uneven brightness, will be described. FIG. 1 is a diagram showing a configuration of a main driving portion of a plasma display according to the present invention. In the figure, reference numeral 1 denotes a surface discharge AC type (AC driving type) plasma display panel, A1 to Am denote address electrodes, Y1 to Yn denote scanning electrodes, and X1 to Xn denote sustain electrodes. The scan electrode and the sustain electrode are paired with each other. The intersection of the electrode pair and the address electrode constitutes one discharge cell, and forms a matrix screen of m × n dots. The address electrodes A1 to Am are connected to the address driver 2. The scanning electrodes and the sustaining electrodes are drawn out from both sides of the panel to the outside. The sustaining electrodes are commonly connected on both sides of the electrodes, and the sustaining pulse generator 6a,
6b. The sustain pulse is generated by the switch element 1
0a, 10b and 20a, 20b are totem pole outputs, and a plus Vs1 or minus Vs2 of the sustain power is output.

One of the scanning electrodes is connected to the diode array 3a and the scan driver 4, and the other of the scanning electrodes is connected only to the diode array 3b. Each output of the scan driver is a switching element 7a
It is a totem pole output by 1, 7b1, etc.
A voltage of Vx1 or Vx2 can be individually applied to each of the electrodes Y1 to Yn. The diode arrays 3a and 3b have diode groups 8a and 18a in which the cathodes are connected to the electrodes Y1 to n and the anodes are commonly connected.
And diode groups 8b and 18b, each having an anode connected to Y1 to n and a cathode connected in common. The commonly connected anode DA is connected to the positive side Vs1 of the sustain pulse DC power supply through the switching element 9a in the sustain pulse generators 5a and 5b, and the commonly connected cathode DK is connected to the sustain pulse generators 5a and 5b.
It is connected to the negative side Vs2 of the sustain pulse DC power supply through the middle switching elements 9b and 19b.

Next, the operation of the apparatus having the above configuration will be described. FIG. 2 is a diagram showing an example of a driving waveform of the AC type plasma display. The figure shows one driving cycle, for example, a period corresponding to one subfield in the so-called subfield gradation method. First, a priming pulse Vp11 is applied to the sustain electrodes X1 to Xm at the beginning of the reset period to discharge the entire surface of the panel so that the subsequent discharge is likely to occur. Next, an erase pulse Ve12 is applied to the scan electrodes Y1 to Yn,
Eliminate wall charges. Subsequently, in the writing period, the scanning pulse 13 is applied in order from the first row Y1, and the address pulse 14 is applied to the address electrode according to the display data.
The cell to which the address pulse and the scanning pulse are applied at the same time is selected and becomes a display cell. Subsequently, sustain pulses 15, 1
6 are alternately applied to the scan electrodes Y1 to Yn and the sustain electrodes X1 to Xn, and the cell selected in the writing period repeats the sustain light emission.

Of the above operations, the operation of the drive circuit when a scan pulse and a sustain pulse are applied will be described with reference to FIG. The scan pulse is generated by the scan driver 4. In the initial state, the switch elements in the scan driver 7a1 to 7an are all ON for any electrode, and 7a1 to 7an.
All of b1 to 7bn are off, and the voltage VX1 is applied to all of Y1 to n. First of all,
The switch element connected to Y1 is inverted (7a1 is OFF, 7b1 is ON), and a scanning pulse of voltage Vx2 is applied to Y1. Subsequently, the switch element connected to Y1 returns to the initial state, and the switch element connected to Y2 is inverted. Similarly, the switching elements are sequentially inverted, and scanning pulses are sequentially applied. The light emission at the intersection of the scanning pulse and the address pulse is as described above. Note that the scanning pulse is applied only from one side of the electrode, but the light emission during scanning is extremely weak compared to the light emission amount in the entire sequence. The reduction does not matter, and it is sufficient that a voltage having a value sufficient to cause discharge can be applied.

The application of the sustain pulse is performed by switching the sustain pulse generator. When applying a positive pulse to the Y electrode, the switch elements 9a and 19a are simultaneously turned on in the two sustain pulse generators 5a and 5b. Then, the sustain voltage Vs1 becomes the diode array 3
a, 3b, to all the sustain electrodes (Y1 to Yn),
Applied simultaneously from left and right. When the sustain pulse falls, the switch elements 9a and 19a are similarly turned off, and
This is performed by turning on b and 19b. Similarly, when a sustain pulse is applied to the sustain electrodes (X1 to Xn), the switch element 10a in the two sustain pulse generators 6a and 6b
And 20a, 10b and 20b are simultaneously turned on / off, thereby applying a sustain pulse from both sides of the electrode.

As described above, the sustain pulse is applied from both sides of the electrode, so that the voltage drop due to the electrode resistance is smaller than that applied from one side. This effect is shown in FIGS. Assuming that the current flowing through one discharge cell is constant, in the case of A and B to which voltage is applied from both sides, compared to the case of application of C and D from one side, 1 / It is reduced to 3. As a result, a decrease in luminance due to a change in the display ratio is reduced, and a high-quality display with less luminance unevenness between lines and disturbance in gradation is provided.
On the other hand, in terms of cost, since the required number of scan drivers with a high cost ratio has not increased, the cost is not much higher than in the past. The diode array 3
The a, 3b, and scan driver 4 can be integrated into a plurality of outputs.

Embodiment 2 In the above-described embodiment, the case where the diode array is used to perform separation when the scan pulse and the sustain pulse are applied to the same electrode has been described. In this embodiment, a case where a field effect transistor (FET) is used instead of a diode will be described. FIG. 5 is a partial circuit diagram showing a connection between a scan driver for driving scan electrodes Y1 to Yn and related peripheral circuits. 7
a1, 7b1, 7a2, 7b2 etc. are FETs, 71, 8
1, 72, 82, etc. are what should be called virtual diodes, and are not actual diodes but parasitic diodes in the FET. Reference numerals 24a and 24b are switches for applying a scanning pulse.

Next, the operation of the apparatus having the configuration shown in FIG. 5 will be described. In the case of applying the scanning pulse during the writing period, the switches 9a, 9b, 19 of the sustain pulse generators 5a, 5b are used.
a and 19b are both turned off, and switches 24a and 24b
Is turned ON. In this state, the FETs are sequentially changed to Y1, Y2 to Y
Invert in the order of n. On the other hand, in the case of applying the sustain pulse during the sustain period, the switches 24a and 24b are both turned off.
Then, the switches 9a and 19a of the sustain pulse generators 5a and 5b are turned on / off simultaneously so that the switches 9a and 19b are operated in reverse. Note that the diode array 3b on the side without the scan driver has the same connection as that in FIG. Thus, the diode array on one side can be omitted, and the circuit scale can be further reduced.

In each of the above embodiments, the sustain pulse generators X and Y are provided at two locations 5a and 5b and 6a and 6b, respectively, and are driven from both sides. Of course, driving the sustain pulse from both sides of the X and Y electrodes is the most effective. However, there is a corresponding effect even if at least one of the X and Y electrodes is driven from both sides.

Although the sustain pulse generating circuit is a simple totem pole circuit for explanation here, a reactive power recovery circuit using a resonance coil as shown in FIG. 6 can also be used. The recovery capacitor 29 has Vs
One half of the voltage is stored. When raising the sustain pulse, first, the switch element 30 is turned on. Then, a current is supplied from the recovery capacitor 29 to the plasma display panel 1 through the switch element 30, the diode 32, the resonance coil 34, and further through the diode array 8a (or 18a) of FIG. At this time, the resonance voltage of the resonance coil 34 and the capacitance component between the electrodes of the plasma display panel 1 causes the electrode voltage of the plasma display to rise to near Vs1. After this,
Switch element 36 ON, switch element 30 OFF
Then, the electrode voltage is fixed at Vs1.

When the sustain pulse falls, the switch element 36 is turned off and then the switch element 31 is turned on. The electric charge stored in the capacitance component between the electrodes of the plasma display panel passes through the diode array 8b (or 18b) and passes through the resonance coil 35 and the diode 3
3. It is recovered by the recovery capacitor 29 through the switch element 31. Thereafter, the switch element 37 is turned on and the switch element 31 is turned off to fix the electrode voltage to 0V. With such an operation, about 80% of the reactive power due to charging and discharging of the capacitance component of the plasma display panel is recovered. The recovery efficiency when using this recovery circuit is:
It is limited by the inductance of the recovery coils 34 and 35, the value of the capacitance between the electrodes of the plasma display panel, and the resonance Q determined by the electrode resistance of the plasma display panel. The smaller the electrode resistance, the higher the recovery efficiency.
When a sustaining pulse is applied to both sides of the panel, the effect of the electrode resistance is reduced. Therefore, the recovery efficiency of the reactive power is improved by about 5% as compared with a case where the sustaining pulse is applied from only one side of the panel.

In FIG. 1, diodes 8a and 18
a, the common connection side of 8b and 18b, and the sustain electrode (X1
To n) are connected in common to the sustain pulse generator, but the electrodes are divided into a plurality of blocks each having a plurality of electrodes, and the electrodes are connected in common to each block and the sustain pulse is generated for each block. It is also possible to provide a generator. Alternatively, the diode array 3 on the side to which the scanning pulse is applied
a and the scan driver 4 are integrated on the same chip,
An integrated circuit having a configuration in which the groups 7a and 7b and the groups 8a and 8b are combined as shown in FIG. 7 may be used.

In this case, the driving pulse
Although only the scanning pulse has been described, it is necessary to apply a priming pulse, an erasing pulse, and the like in the actual driving sequence. These pulses can be applied from one or both sides of the PDP by providing a priming pulse generating circuit and an erasing pulse generating circuit in one or more of the sustain pulse generating circuits 5a, 5b, 6a, and 6b. it can. Further, as the drive sequence, various kinds of sequences that differ in detail other than those shown in FIG. 2 can be considered, and it goes without saying that the idea of the drive method described in each embodiment can be applied to them.

[0026]

As described above, according to the present invention, the X electrodes and the Y electrodes are connected from both sides of the panel, and the driving circuits for maintaining the X electrodes and the Y electrodes are added from both sides. This has the effect of reducing the decrease in luminance due to the change in the rate and the luminance unevenness between lines.

Further, since the FET is used, there is an effect that the circuit scale can be reduced in addition to the above effects.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main driving portion of a plasma display according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing an example of a drive waveform of an AC drive type plasma display.

FIG. 3 is a diagram showing a relationship between a position on an electrode and a voltage applied to a cell by a drive circuit according to the present invention.

FIG. 4 is a diagram showing a relationship between a display ratio in the horizontal direction and luminance by an electrode and a driving circuit according to the present invention.

FIG. 5 is a diagram showing a scan and sustain drive circuit of a plasma display according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a sustain pulse generator to which a reactive power recovery circuit is added.

FIG. 7 is an explanatory diagram of a configuration of an integrated integrated circuit of a scan drive circuit and a diode array.

FIG. 8 is a schematic configuration diagram of a conventional plasma display.

FIG. 9 is a main drive circuit diagram of a conventional plasma display panel.

FIG. 10 is a diagram showing an electric equivalent circuit of a sustain electrode and a scan electrode of a conventional PDP.

FIG. 11 is a diagram showing a relationship between a position on an electrode of a conventional PDP and a voltage applied to a cell.

FIG. 12 is a diagram showing a relationship between a display ratio in the horizontal direction and luminance of a conventional PDP.

FIG. 13 is a drive circuit diagram of a second conventional PDP.

[Explanation of symbols]

1 surface discharge AC type plasma display panel, 2 address driver, 3a, 3b diode array, 4
Scan driver, 5a, 5b sustain pulse generator (Y), 6a, 6b sustain pulse generator (X), 7a
1, 7b1, 7a2, 7b2, 7an, 7bn Switch element, 8a, 8b, 18a, 18b Diode, 9
a, 9b, 19a, 19b Switch element, 10a, 1
0b, 20a, 20b switch element, 11 priming pulse, 12 erase pulse, 13 scan pulse, 14
Address pulse, 15, 16 sustain pulse, 21 P
DP scan electrode driving integrated circuit, 22 sustain electrode driver (X driver), 23 scan electrode driver (Y driver), 24a, 24b scan pulse applying switch, 25
Level shifter and gate driver, 26 control logic circuit section, A1 to Am address electrodes, Y1 to Yn scan electrodes, X1 to Xn sustain electrodes.

Claims (4)

[Claims] 1. An independent n Y for maintenance and scanning
In an AC-driven plasma display having an electrode and a sustaining X electrode, the X electrode and the Y electrode are configured to be connected from both sides of the panel of the plasma display, and are respectively provided for the X electrode and the Y electrode. It has two sustain drive circuits, and one scan drive circuit for the Y electrode. The two sustain drive circuits for the X electrode and the Y electrode are simultaneously driven from both sides of the panel. AC driven plasma display device. 2. A scanning drive circuit for n independent Y electrodes, wherein one side is commonly connected to a high-voltage side driving source and the other is connected to each Y electrode, respectively. 2. An AC-driven plasma display according to claim 1, wherein one side of the group is connected to a low voltage side driving source, and the other side is driven through another group of FETs connected to the Y electrode. apparatus. 3. A structure in which either the sustaining X electrode or the sustaining and scanning Y electrode is connected from one side of the panel instead of the connection from both sides of the panel. 2. The circuit according to claim 1, wherein a single sustain drive circuit drives the one-side connected sustain electrode.
An AC-driven plasma display device as described in the above. 4. An independent n Y for maintenance and scanning
In an AC drive type plasma display having an electrode and a sustaining X electrode, the X electrode and the Y electrode are configured to be connected from both sides of the panel of the plasma display, and a scan pulse corresponding to an instruction address is applied to the Y electrode. An AC drive type plasma display driving method, further comprising: a writing step of emitting light; and a sustaining step of successively alternately applying a sustaining pulse from both sides of the panel to all the Y electrodes and the X electrodes.