Patent Grant
7015879
1. Field of the Invention
The present invention relates to a plasma display panel device and more particularly to a plasma display panel device having a pair of row electrodes made up of a scanning electrode and a common electrode (sustaining electrode) which provide one display row formed in parallel with a plane of a front substrate (scanning substrate) facing a rear substrate.
The present application claims priority of Japanese Patent Application No. JP2001-230602 filed on Jul. 30, 2001, which is hereby incorporated by reference.
2. Description of the Related Art
A Plasma Display Panel device ((hereinafter, may be referred simply to as a PDP device) is classified into one of three types; one being an AC (Alternating Current)-type PDP device conventionally using an AC as a driving power source, another being a DC (Direct Current)-type PDP device using a DC as the driving power source, and a third being a hybrid-type PDP device using the AC and DC in combination. Of them, the AC-type PDP device is widely used since it is of a comparatively simple structure and its screen can be easily made large.
Of the AC-type PDP device, a PDP device of a three-electrode surface discharge type, in particular, has a configuration in which a pair of row electrodes made up of a scanning electrode and a common electrode which provides one display row (line) is formed in parallel with a plane of a front substrate facing a rear substrate and a column electrode (address electrode) is formed on a rear substrate so as to be orthogonal to a pair of row electrodes and, by driving the address electrode (data electrode) and the scanning electrode using a driving voltage, writing discharge is performed to select a unit cell (hereinafter being referred to as a display cell) to be turned ON (to be displayed) and then sustaining discharge is performed by surface discharge of a display cell selected by driving the scanning electrode and the common electrode using a driving voltage. In the above PDP device, since no ion bombardment causing deterioration occurs between an ion of high energy being produced on the front substrate at a time of surface discharge and a phosphor formed on the rear substrate, which enables a life to be made longer. As a result, the PDP device is widely employed.
On the other hand, address electrodes 54 making up column electrodes are formed, in parallel with a column direction V on a screen, on a face (being opposite to the front substrate) of a rear substrate (not shown) made up of a transparent substrate that faces the front substrate and each of the address electrodes 54 is arranged in such a manner as to be put between ribs (partition walls) 55 each being formed in parallel with the column direction V. A display cell is partitioned by each of ribs 55 to be a plurality of display cells 56. The Plasma display panel (hereinafter, may be referred to as a PDP panel) is so constructed that the front substrate and the rear substrate are integrally assembled with space for discharging gas being put between them and, by connecting a driving circuit to the PDP panel, the AC-type PDP device is fabricated. In following descriptions, to get an easy understanding, the PDP panel alone is described simply as the AC-type PDP device.
In the AC-type PDP device having configurations described above, an arbitrary image is displayed on a screen by performing writing discharge (during an addressing period) to select a display cell 56 to be turned ON (to be displayed) out of a plurality of display cells 56 through an application of a driving voltage (high-frequency pulse) to drive the address electrode 54 and scanning electrode 51 and by performing sustaining discharge using a surface discharge method of a display cell 56 selected through an application of a driving voltage to drive the scanning electrode 51 and the common electrode 52.
In the configuration of the conventional AC-type PDP device shown in
Here, as shown in
Since such the electromagnetic radiation has an adverse effect on electromagnetic environments in electronic devices, electric appliances, or a like in general homes, to reduce the electromagnetic radiation, it is necessary that an electromagnetic shield is provided on a PDP device. However, since a thin configuration of a PDP device is its prime selling point, such the electromagnetic shield not only hinders the thin configuration but also causes an increase in costs.
A PDP device configured so as to reduce electromagnetic radiation is disclosed in Japanese Patent Application Laid-open No. JP2000-89723 (hereinafter referred to as a first conventional technology). In the above PDP device, as shown in
Similarly, a PDP device is disclosed, for example, in Japanese Patent Application Laid-open No. JP2000-294152 (second conventional technology) in which magnetic flux occurring in every two display units is erased. In the disclosed conventional PDP, as shown in
Each of the conventional PDP devices described as the first and second technologies can reduce electromagnetic radiation, however, each of them has a problem.
First, in the first conventional technology, each of a plurality of display cells in which the scanning electrode 101 and the common electrode 102 are formed has a different impedance in every display cell due to a difference in the drawing-out position 109 on the left side of the panel caused by a positional variation in a row direction H. Therefore, since light-emitting luminance and/or controlled state are made different in every display cell, a uniform state of light emission for displaying cannot be achieved.
Next, in the second conventional technology, since magnetic flux occurring in alternating sequence of display rows is erased and potentials of the two scanning electrodes for the two display rows and of the two common electrodes for the two display rows become same, individual selection of the scanning electrode or common electrode is made impossible. Therefore, since same scanning electrodes or same electrodes can always display same contents only, high-definition display of an image becomes difficult. To solve this problem, a method may be available in which address electrodes are separated depending on either of an odd row or an even row, however, to achieve this, a very complicated driving circuit is required, which inescapably causes very high manufacturing costs.
In view of the above, it is an object of the present invention to provide a PDP device capable of obtaining a uniform state of light emission for displaying and of reducing electromagnetic radiation while easily achieving a high-definition image display.
According to a first aspect of the present invention, there is provided a PDP device including:
a front substrate and a rear substrate between which a discharging gas space is formed;
a pair of row electrodes made up of a scanning electrode and a common electrode (sustaining electrode) which provide one display row in parallel with a face of the front substrate facing the rear substrate;
a folding-back electrode on either of the scanning electrode or the common electrode for every one display row; and
wherein a direction of a current flowing through the folding-back electrode and a direction of a current flowing through either of the scanning electrode or the common electrode are opposite to each other.
In the foregoing, a preferable mode is one wherein magnetic flux produced by a current flowing through the folding-back electrode and magnetic flux produced by a current flowing through either of the scanning electrode or the common electrode cancel out each other.
Also, a preferable mode is one wherein a bus electrode is connected to the common electrode.
Also, a preferable mode is one wherein an auxiliary folding-back electrode is formed on the bus electrode.
According to a second aspect of the present invention, there is provided a PDP device including:
a front substrate and a rear substrate between which a discharging gas space is formed;
a pair of row electrodes made up of a scanning electrode and a common electrode which provide one display row in parallel with a face of the front substrate facing the rear substrate;
a folding-back electrode on either of the scanning electrode or the common electrode for alternating sequence of display row; and
wherein a direction of a current flowing through the folding-back electrode and a direction of a current flowing through either of the scanning electrode or the common electrode are opposite to each other.
In the foregoing, a preferable mode is one wherein magnetic flux produced by a current flowing through the folding-back electrode and magnetic flux produced by a current flowing through either of the scanning electrode or the common electrode cancel out each other.
Also, a preferable mode is one wherein a dummy electrode is formed between display rows in which the folding-back electrode is not formed.
Also, a preferable mode is one wherein each of driving terminals for the scanning electrode and common electrode is formed in every one display row.
Also, a preferable mode is one wherein each of driving terminals for the scanning electrode and common electrode is formed for alternating sequence of display rows.
With the above configurations, each of scanning electrodes and each of common electrodes making up a pair of row electrodes that provides one display row, are formed, in parallel with a row direction on a face of a front substrate facing a rear substrate and a folding-back electrode is formed on either of the common electrode or scanning electrode, and therefore the scanning electrode and the common electrode can be drawn out from a same direction of a PDP panel for at least every one display row, which can cancel magnetic flux occurring in a unit of a display row. Therefore, it is possible to obtain a uniform state of light emission for displaying and to reduce electromagnetic radiation while easily achieving a high-definition image display.
The above and other objects, advantages, and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
Best modes of carrying out the present invention will be described in further detail using various embodiments with reference to the accompanying drawings.
On the other hand, the rear substrate 2, as shown in
The PDP device 10 chiefly includes, as shown in
According to configurations of the PDP device 10 of the first embodiment, as described later, since driving terminals of the scanning electrode 5 and common electrode 6 for all display rows 9 can be drawn out from a right side direction in
Next, operations of the PDP device 10 of the first embodiment will be described by referring to
Since a current path from the driving terminals S1 to C1 is one independent root, a current flowing in from the driving terminal S1 is always equal to a current flowing out from the driving terminal C1. When it is considered that the scanning electrode 5 and common electrode 6 both being connected to each other with the display cell 9 being interposed between them make up one current path, an amount of a current flowing through the current path is always equal to that of a current flowing through the folding-back electrode 21 formed on the common electrode 6 and directions of the flow of the currents are opposite to each other. The magnetic fluxes induced by each of the currents cancel each other out. In the PDP device 10 shown in
Next, effects that can be achieved by the PDP device 10 of the first embodiment are explained. As described above, when the folding-back electrode 21 is formed, since magnetic fluxes induced by a driving current for every one unit of a display row cancel each other out, it is made possible to extremely reduce electromagnetic radiation providing a source of a magnetic flux. Since this is an effect that can be achieved by an electrode structure making up the PDP device 10, no change in a method employed in the driving circuit is required and the effect can be obtained not only during a sustaining discharge period but also in all operations in which a current flows through a PDP panel.
Therefore, a stringent electromagnetic shield which has been indispensable to the PDP device as a product is not required and it is possible to reduce costs of the PDP device and to make it lightweight and to prevent an electromagnetic environment in space provided in general homes from becoming worse. Moreover, even if a distance from each of the driving electrodes in the scanning electrode 5 or in the common electrode 6 is different, since a total sum of a length of each of the driving electrode for an arbitrary display cell is same and since a uniform impedance is given to any display cell 9, a state of control on light emission luminance or on a display cell in every display cell 9 becomes same when a distance from a driving terminal of the scanning electrode 5 or common electrode 6 of the PDP panel 26 is large or small, a uniform state of light emission for displaying can be obtained.
Moreover, since the scanning electrode 5 is so configured as to be one independent electrode for every display row, a display being different for every display row can be easily achieved. Therefore, it is possible to provide a PDP device having an electrode structure being capable of reducing electromagnetic radiation, of obtaining a uniform state of light emission for displaying in the PDP panel 26, and of easily scanning and selecting an independent display content for every display row.
Moreover, according to the PDP device 10 of the first embodiment, as shown in
Moreover, according to the PDP device 10 of the first embodiment, since a bus electrode 19 is formed on the common electrode 6 and all the common electrodes 6 are grounded in the PDP panel 26, a potential of the common electrode 6 in the PDP panel 26 can be once made uniform. Even if paths being grounded from a driving circuit are not uniform in impedance for a driving terminal of the folding-back electrodes 21 formed on all common electrodes 6, it is possible to prevent an unevenness in light-emitting luminance. Moreover, even if impedance of a path being connected from a driving circuit is not uniform for the driving terminal of the folding-back electrode 21 formed on all the common electrodes 6 or even if a number of the display cells 9 used to perform sustaining discharge for a display row is largely different, it is possible to prevent an unevenness in light-emitting luminance among display rows. Here, if no bus electrode 19 is provided, an increase in impedance for the display cell 9 caused by addition of the folding-back electrode 21 independently affects one display row and, in the display row having a larger number of the display cells 9 used to perform sustaining discharge, a drop in voltage becomes larger and, as a result, an unevenness in the light emission luminance occurs. Thus, an effect can be obtained in which the bus electrode 19 prevents deterioration in an image quality of a display.
When a variation in light emission luminance among display rows by forming the bus electrode 19 is to be prevented, a current required for light emission discharge has to be larger in the display row having the larger number of display cells 9 used to perform sustaining discharge and is supplied additionally through the bus electrode 19 from the folding-back electrode 21 formed on the common electrode 6 making up a display row having a small number of the display cell 9 being adjacent to each other and being used to perform sustaining discharge. Therefore, when only one display row is considered, in some cases, an amount of a current flowing through one current path formed on the scanning electrode 5 and the common electrode 6 both being connected with the display cell 9 being interposed between them is not equal to an amount of a current flowing through the folding-back electrode 21 formed on the common electrode 6 in a direction opposite to each other. However, when a plurality of display rows being adjacent to each other is considered, a total sum of currents flowing in a direction opposite to each other becomes equal to each other. Moreover, in the case of high-frequency components in which radiation of an electro-magnetic noise increases more, since an action by mutual inductance becomes stronger, a current for light emission discharge provides a characteristic that an equal amount of the current flows through the folding-back electrodes 21 being nearer to each other. Therefore, even if the bus electrode 19 is formed, an effect is not impaired which can cancel magnetic flux occurring due to a driving electrode and can reduce extremely electromagnetic radiation providing a source of a magnetic field.
Moreover, according to the first embodiment, as shown in
In a go-and-return path for a current being so configured that magnetic flux is cancelled out, it is known that its inductance becomes very small which can be same in configurations of the electrodes used in the PDP device 10 of the present invention. This makes small inductance of an electrode for various driving pulses fed from a driving circuit and, as a result, a voltage surge occurring at a transient of a pulse or at a time of switching of a current path in the driving circuit can be made smaller. Therefore, this enables lowering of a rating of a withstand voltage of a switching element in the driving circuit and can give an effect of reducing electromagnetic radiation occurring as emission providing a source of an electric field.
Moreover, it is desirable that a rib (not shown) is provided along the folding-back electrode 21 formed on the common electrode 6. This can prevent discharging that should occur only between the scanning electrode 5 and the common electrode 6 from occurring between the scanning electrode 5 and the folding-back electrode 21 formed on the common electrode 6. Moreover, in the first embodiment, as a means for preventing a variation of light emission luminance, though the bus electrode 19 and the auxiliary folding-back electrode 22 formed on the common electrode 6 are formed, in order to reduce much of the electromagnetic radiation, the auxiliary folding-back electrode 22 is not always necessary. If there is no bus electrode 19, the scanning electrode 5 may serve also as the folding-back electrode 21. Moreover, it is not always necessary that one folding-back electrode 21 is formed in every one display row. The folding-back electrode 21, as shown in
Thus, according to the PDP device 10 of the first embodiment, in the configuration in which each of scanning electrodes 5 and each of common electrodes 6, both of which make up a pair of row electrodes that provide one display row, are formed, in parallel with a row direction on a screen on a face of the front substrate 1 that faces the rear substrate 2, since the folding-back electrode 21 is formed on the common electrode 6, the scanning electrode 5 and common electrode 6 can be drawn out from a same direction of the PDP panel 26 and, therefore, magnetic flux occurring in a unit of a display row can be cancelled. Therefore, it is possible to obtain a uniform state of light emission for displaying and to reduce electromagnetic radiation while easily achieving high-definition image display.
Next, operations of the PDP device 20 of the second embodiment will be described.
First, let it be assumed that only five electrodes are now considered which include a scanning electrode 5 on a first line and a common electrode 6 with a display cell 9 being put between the scanning electrode 5 and common electrode 6 on which a folding-back electrode 21 is formed, a common electrode 6 on a second line and a scanning electrode 5 with a display cell 9 being put between the common electrode 6 and scanning electrode 5. Also, let it be assumed that, during a sustaining discharge period, the driving terminals S1 and S2 of the scanning electrode 5 are connected to a same terminal for a high voltage and the driving terminal C1 and C2 of the folding-back electrode 21 being connected to the common electrode 6 are grounded. A current used to charge an electrostatic capacitor (not shown) existing in the display cell 9 and a current produced by discharge of the display cell 9 flow in the PDP panel 26 from the driving terminals S1 and S2 and passes through each of the display cells 9 for the two display rows to each of the common electrodes 6. This current, after having passed through one folding-back electrode 21 of the common electrode 6, flows out from the PDP panel 26 through the driving terminals C1 and C2 of the folding-back electrode 21 of the common electrode 6.
Since a current path existing between the driving terminals S1 and S2 and driving terminals C1 and C2 is one independent route, a total sum of an amount of a current flowing from the driving terminals S1 and S2 and an amount of a current flowing out from the driving terminals C1 and C2 always become equal to each other. When the scanning electrode 5 and the common electrode 6 with the display cell 9 being put between the scanning electrode 5 and the common electrode 6 are considered to be a current path, a total sum of an amount of a current flowing through the current path for the two display rows and an amount of currents flowing through one folding-back electrode 21 formed on the common electrode 6 are always same and their flowing directions are opposite to each other. Then, the magnetic fluxes induced by each of the currents cancel each other out. Same occurs also when a voltage applied to the driving terminal is reversed. That is, the magnetic fluxes induced by each of the currents cancel each other out in alternating sequence of display rows.
In the second embodiment, when sustaining discharge or preliminary discharge, in which a voltage pulse is applied to a whole of the PDP panel 26, occurs, currents between the electrodes without the display cell 9 being put between the electrodes being adjacent to each other becomes equal. Since both the electrodes being adjacent to each other in an up- and-down direction of the folding-back electrode 21 formed on the common electrode 6 are the common electrodes 6, these three electrodes are at a same potential and since both the electrodes being adjacent to each other in an up-and-down direction with the dummy electrode 27 being put between the electrodes are the scanning electrodes 5, these three electrodes including the dummy electrode 27 being electrically floated are at a same potential. Therefore, since electrostatic capacitance other than that produced in the display cell 9 can be neglected, reduction of amounts in currents used to drive the PDP panel 26 is made possible. As a result, effects of reducing a driving capacity of a driving circuit or of reducing power consumption occurring by charging or discharging of electrostatic capacitors can be achieved.
Moreover, since currents between the electrodes without the display cell 9 being put between the electrodes, being adjacent to each other, becomes equal, a problem associated with a distance between electrodes which is required to satisfy requirements for a dielectric strength is solved which enables its distance to be reduced. As a result, since an interval between the scanning electrode 5 and common electrode 6 that overlay the display cell 9 can be made wide, an effect of taking out more light emitted by the display cell 9 can be achieved.
Furthermore, in the second embodiment, as shown in
Furthermore, it is preferable that a rib (not shown) is formed along the folding-back electrode 21 formed on the common electrode 6 and the dummy electrode 27. By configuring the PDP device 20 of the second embodiment in a manner as described above, it is possible to prevent a discharge that should occur only between the scanning electrode 5 and common electrode 6 from occurring between the scanning electrode 5 and the folding-back electrode 21 formed on the common electrode 6. By configuring the PDP device 20 so that both a surface on a display screen side of the rib and a surface on a display screen side of the folding-back electrode 21 formed on the common electrode 6 have colors being visually equal to each other, the dummy electrode 27 is not required.
Thus, in the PDP device 20 of the second embodiment, instead of the folding-back electrode 21 formed in every display row, the folding-back electrode 21 is formed in alternating sequence of display rows and therefore approximately the same effect as obtained in the first embodiment can be achieved.
By configuring as described above, even if space constraints exist, since a number of the driving terminal formed on one side of the PDP panel 26 becomes approximately a half of the number of the driving terminals formed in the first embodiment and therefore an interval between positions for forming the driving terminal can be made wide, it is possible to ensure reliability of connection. Moreover, a driving capability and a number of scanning outputs of the driving circuits 24A and 24B being placed on both the sides of the PDP panel 26 also become a half, a problem that it is difficult to put the driving circuit fully together on one side can be solved. Moreover, as shown in
Thus, in the configurations of the PDP device 30 of the third embodiment, the same effect as obtained in the first embodiment can be achieved.
By configuring as above, even if there are space restraints, since a number of driving terminals formed on one side of the PDP panel 26 becomes approximately a half of that in the first embodiment, an interval between positions for forming the driving terminal can be made wide and, as a result, it is possible to ensure reliability of connection. Moreover, a driving capability and a number of scanning outputs of the driving circuits 24A and 24B each being placed on one side of the PDP panel 26 also become a half, a problem that it is difficult to put the driving circuit fully together on one side can be solved. Moreover, since a current route 23 can be terminated at the two driving circuits 24A and 24B each being placed at one side of the PDP panel 26, a current loop is not formed through a GND plate 25. As a result, the GND plate 25 used to flow a large high-frequency current is not required, which makes it possible to reduce costs of the PDP device 40 or to make it lightweight.
Configurations other than those described above are approximately same as those in the first embodiment and, in
Thus, in the configurations of the fourth embodiment, the same effect as obtained in the second embodiment can be achieved.
It is apparent that the present invention is not limited to the above embodiments but may be changed and modified without departing from the scope and spirit of the invention. For example, in the above embodiments, a folding-back electrode is formed on a common electrode, however, the folding-back electrode may be formed on a scanning electrode. Moreover, each of driving terminals for a scanning electrode and common electrode shown in the above embodiment can be drawn from either of right end portions or left end portions. All that is needed in the present invention is that each of the driving terminals for the scanning electrode and common electrode is drawn from a same direction of a panel for, at least, one display row.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001-230602 | Jul 2001 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6166711 | Odake | Dec 2000 | A |
| 6320326 | Shino et al. | Nov 2001 | B1 |
| 6538389 | Onozawa et al. | Mar 2003 | B1 |
| Number | Date | Country |
|---|---|---|
| 2000-89723 | Mar 2000 | JP |
| 2000-294152 | Oct 2000 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20030020675 A1 | Jan 2003 | US |
