Patent Application
20080084161
1. Field of the Invention
The present invention relates to plasma display panels which are employed as an image display device for use with information terminal devices, personal computers, televisions or the like. More particularly, the present invention relates to a plasma display panel and its fabrication method which make it possible to provide a higher peak intensity and less maximum power consumption for a plasma display panel, having a large capacity and a high resolution, than prior-art panels and methods.
2. Description of the Related Art
Plasma display panels have such advantages that they have a simple construction, facilitates the provision of a large screen, and can employ inexpensive glass materials, which are widely used for glass windows or the like, as substrates for constituting the display panel.
A plasma display panel employs two transparent insulating substrates formed of such a glass material, each transparent insulating substrate having electrodes and ribs formed thereon to define pixel cells or display units. To complete the panel, these two transparent insulating substrates, having these structures formed thereon, are disposed in parallel spaced relation to define a gap therebetween in which a discharge gas is sealed. Typically, the rib is about 0.1 mm in height and the transparent insulating substrate is about 3 mm in thickness, thereby making it possible to provide extremely thin and lightweight display devices.
Accordingly, by making use of such features, the plasma display panel has been being used in a display device for personal computers or office work stations, which have found widespread use in recent years, or for large-screen wall-hung televisions which have strong potential for further development.
The plasma display panel is largely classified into DC and AC types depending on the difference in panel structures. The plasma display panel with the electrodes being directly exposed to a discharge gas is referred to as the DC type because a DC current continues to flow once a discharge has occurred. On the other hand, the AC type with an insulating layer being interposed in between the electrodes and the discharge gas allows a pulse current to flow for a short period of time about 1 μs after the application of a voltage and then converge. The flow of current is restricted by the electrostatic capacitance of the insulating layer. The insulating layer acts as a capacitor so that applied AC pulses cause repetitive pulses of light emission to occur for display purposes. This is why the AC type is called by that name.
Although the DC type has a simple structure, the electrodes are directly exposed to discharge environments and therefore wear out in a shorter period of time, thereby making it difficult to provide the DC type with long life. In contrast, the AC type requires additional time, effort, and cost to form the insulating layer, however, the electrodes are covered with the insulating layer, thereby providing the AC type with long life. In addition, the AC type can readily implement the function referred to as a memory function, which enables highly bright light emission, and accordingly has been developed in recent years.
The present invention relates to this AC memory-type plasma display panel. Now, the configuration and then the method of the AC memory-type plasma display panel will be explained below.
First, the configuration of the AC memory-type plasma display panel is described. FIGS. 1 to 3 are views illustrating an AC memory-type plasma display panel disclosed in Japanese Patent Laid-Open Publication No. Hei 6-12026 and having an electrode structure which is generally called a plane discharge type.
As shown in
On the surface of the first insulating substrate 11 opposite to the second insulating substrate 12, a plurality of sustain electrodes 13a formed of transparent NESA film and a plurality of scan electrodes 13b also formed of transparent NESA film are disposed alternately in parallel to each other. In addition, a bus electrode 13c formed of silver thick film is disposed on top of each sustain electrode 13a and each scan electrode 13b to be in contact therewith, thereby making it possible to supply sufficient current to the sustain electrode 13a and the scan electrode 13b. These sustain electrode 13a, the scan electrode 13b, and the bus electrode 13c are formed to extend in the direction of horizontal rows in
Incidentally, the sustain electrode 13a and the scan electrode 13b are generally referred to as a display electrode portion which plays a major role in emitting light for display purposes. In addition, the bus electrode 13c is to supply current to the display electrode portion. Likewise, the wiring portion for supplying current is often referred to as the bus electrode. In this context, the bus electrode 13c is sometimes referred to as the bus electrode portion.
The electrode portion composed of the display electrode portion and the bus electrode portion is formed on the same surface of the glass substrate to provide an electrode constituting portion for causing plane discharges, and thus the display electrode portion and the bus electrode portion are generally referred to as the plane discharge electrode. For example, the plane discharge electrode on the side of the sustain electrode has the sustain electrode 13a as the display electrode portion and the bus electrode 13c on the sustain electrode 13a as the bus electrode.
Now, on the second insulating substrate 12, there are formed a plurality of column electrodes 14 of thick silver film to extend in the direction of horizontal rows in
As described above, the two insulating substrates 11 and 12, each having respective structures formed thereon, are disposed in parallel spaced relation to each other to define a gap therebetween which acts as the discharge gas space 15. The discharge gas space 15 is filled, at a total pressure of 66.5 kPa, with a discharge gas of a gas mixture such as He and Ne mixed at a ratio of seven to three and added by 3% of Xe.
Referring to
Incidentally, the insulating substrate on the side for viewing the display (the first insulating substrate 11 in this case) may be called the front substrate, while the other insulating substrate (the second insulating substrate 12 in this case) may be called the rear substrate. In addition, in
Now, described below is a method for performing gray-scale display operation using the plasma display panel configured as described above. For the plasma display panel, unlike other types of display devices, it is difficult to change the level of applied voltages to thereby perform gray-scale display operation at a high intensity, and accordingly the number of times of light emission is controlled in general to perform gray-scale display operation. Particularly, to perform gray-scale display operation at a high intensity, employed is the sub-field method to be described below.
As shown in
The luminous intensity of each pixel cell is controlled in accordance with the following equation 1 by assigning a weight of 2n to the number of times of light emission for sustain discharge at each pixel cell in each sub-field.
where n is the sub-field number, being one (1) for the sub-field of the lowest intensity and k for the sub-field of the highest intensity; L1 is the intensity of the sub-field providing the lowest intensity; and an is a variable taking on a value of one or zero, being a value of one when the pixel cell emits light in the nth sub-field while zero when no light is emitted therefrom. Since different levels of luminous intensity are provided at each of the sub-fields, brightness can be controlled by selecting the “on” or “off” state of each sub-field.
Since
A sustain pulse 31 and a preliminary discharge pulse 36 are applied to the sustain electrodes 13a (C1, C2, . . . , Cm). On the other hand, a sustain pulse 32, an erase pulse 35, and the preliminary discharge erase pulse 37 are applied successively in common to the scan electrodes 13b (S1, S2, . . . , Sm) in addition to the scan pulse 33 which is applied to each of the scan electrodes 13b (S1, S2, . . . , Sm) with independent timing. When light emission data is available, the data pulse 34 is applied to each of the column electrodes Dj (j=1, 2, . . . , n) in phase with the scan pulse 33. In the plasma display panel configured as shown in FIGS. 1 to 4, the erase pulse 35 first erases the discharge in the pixel cell that has emitted light in the immediately previous sub-field. Then, the preliminary discharge pulse 36 causes a preliminary discharge to forcedly occur once in all pixel cells and then the preliminary discharge erase pulse 37 is allowed to erase the preliminary discharge. This allows the scan pulse 33 being subsequently applied to readily cause a write discharge.
After the preliminary discharge has been erased, application of the scan pulse 33 and the data pulse 34 to the scan electrode 13b and the column electrode 14 with the same timing to cause a write discharge will cause a discharge between the scan electrode and the column electrode at the same time for the write discharge. This is referred to as the write sustain discharge. Subsequently, the sustain discharge is maintained between the sustain electrode 13a and scan electrode 13b, adjacent to each other, by the sustain pulses 31 and 32. On the other hand, application of only the scan pulse 33 or only the data pulse 34 would cause neither a write discharge nor a subsequent sustain discharge to occur. Such a function is called the memory function. The luminous intensity is controlled at each of the sub-fields depending on the number of times of sustain discharge.
However, as can be seen from the cross-sectional view of
It is therefore an object of the present invention to provide a plasma display panel which can provide a high optical output efficiency and high peak intensity and which can be driven with less maximum power consumption, and a method for fabricating the panel.
As a first aspect, the present invention provides an AC plane discharge plasma display panel having a fundamental structure including a front substrate, a rear substrate, and a sealing portion for encapsulating the front substrate and the rear substrate at a peripheral edge portion thereof to seal a discharge gas therebetween. The plasma display panel also includes column ribs and row ribs for defining pixel cells in a column direction and in a row direction, respectively, to thereby define the pixel cells in a matrix, and plane discharge electrodes constituted by a display electrode portion and a bus electrode portion. The plasma display panel is characterized in that at least part of the display electrode portion of the plane discharge electrodes has a notched portion or a cut-away portion between pixel cells adjacent to each other in the row direction; a sustain electrode and a scan electrode, paired as plane discharge electrodes, are placed in one pixel cell; and for neighboring pixel cells arranged in the column direction, sustain electrodes and scan electrodes are disposed to allow respective sustain electrodes and scan electrodes to be adjacent to each other between neighboring pixel cells. Furthermore, as a second aspect, there is provided the plasma display panel having the aforementioned fundamental structure according to the first aspect, characterized in that neighboring sustain electrodes or sustain-side bus electrodes for neighboring pixel cells arranged in the column direction are electrically connected to each other in the panel.
Furthermore, as a third aspect, there is provided the plasma display panel having the aforementioned fundamental structure according to the first aspect, characterized in that neighboring scan electrodes or scan-side bus electrodes for neighboring pixel cells arranged in the column direction are electrically connected to each other in the panel.
Furthermore, as a fourth aspect, there is provided a method for fabricating the plasma display panel set forth in the aforementioned first to third aspect, characterized by including the steps of encapsulating the rear substrate and the front substrate in a vacuum, and sealing a discharge gas in the panel continually thereafter without exposing the interior of the panel to the atmosphere.
Furthermore, as a fifth aspect, there is provided the plasma display panel set forth in the aforementioned first to third aspect, characterized in that lattice-shaped ribs are formed on the rear substrate.
Furthermore, as a sixth aspect, there is provided the plasma display panel set forth in the aforementioned fifth aspect, characterized in that a gap for allowing a discharge gas to pass therethrough is provided between the top of the lattice-shaped rib and the front substrate.
Furthermore, as a seventh aspect, there is provided the plasma display panel set forth in the aforementioned sixth aspect, characterized in that projected portions are provided on intersections of lattice-shaped ribs of the front substrate or the rear substrate, the intersections corresponding to those of lattice-shaped ribs of the rear substrate.
Furthermore, as an eighth aspect, there is provided the plasma display panel set forth in the aforementioned seventh aspect, characterized in that the projected portions define scan-side bus electrodes and sustain-side bus electrodes or scan electrodes and sustain electrodes between pixel cells adjacent to each other in the row direction.
Furthermore, as a ninth aspect, there is provided the plasma display panel set forth in the aforementioned sixth aspect, characterized in that recessed portions are provided on intersections of lattice-shaped ribs of the front substrate or the rear substrate, the intersections corresponding to those of lattice-shaped ribs of the rear substrate.
Furthermore, as a tenth aspect, there is provided the plasma display panel set forth in the aforementioned ninth aspect, characterized in that rib portions other than the recessed portions define at least scan electrodes and sustain electrodes between pixel cells adjacent to each other in the column direction.
Furthermore, as an eleventh aspect, there is provided the plasma display panel set forth in the aforementioned sixth aspect, characterized in that horizontal barrier walls having a thickness of 2 to 50 μm between pixel cells are formed in parallel to bus electrodes.
Furthermore, as a twelfth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that the horizontal barrier wall is formed of a material having a dielectric constant lower than that of the insulating layer.
Furthermore, as a thirteenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that the horizontal barrier wall is placed only on one of the sustain electrodes or the scan electrodes between pixel cells extending in the longitudinal column direction.
Furthermore, as a fourteenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that the horizontal barrier walls on the sustain electrode and the scan electrode have different widths.
Furthermore, as a fifteenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh to fourteenth aspect, characterized in that an extended portion is formed orthogonal to the longitudinal direction of the horizontal barrier wall, and the extended portion is disposed between pixel cells adjacent to each other in the longitudinal row direction.
Furthermore, as a sixteenth aspect, there is provided the plasma display panel set forth in the aforementioned sixth aspect, characterized in that lattice-shaped ribs are formed on the rear substrate, and a rib portion extending in the longitudinal row direction for defining pixel cells is higher than a rib portion extending in the longitudinal column direction for defining pixel cells.
Furthermore, as a seventeenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that a bus electrode constituting the plane discharge electrode does not overlap the horizontal barrier wall but overlaps the rib.
Furthermore, as an eighteenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that a bus electrode constituting the plane discharge electrode does not overlap the rib but overlaps the horizontal barrier.
Furthermore, as a nineteenth aspect, there is provided the plasma display panel set forth in the aforementioned eleventh aspect, characterized in that a bus electrode constituting the plane discharge electrode is located so as to overlap the horizontal barrier wall and the rib.
Furthermore, as a twentieth aspect, there is provided the plasma display panel set forth in the aforementioned sixth aspect, characterized in that the bus electrode has a thickness of 10 to 50 μm, and the thickness of the bus electrode causes a raised portion of thickness 2 to 50 μm to be formed on the surface of the insulating layer.
Furthermore, as a twenty-first aspect, there is provided the plasma display panel set forth in the aforementioned first, second, and fifth to twentieth aspect, characterized in that a metal electrode connects between the sustain electrodes.
Furthermore, as a twenty-second aspect, there is provided the plasma display panel set forth in the aforementioned first, second, and fifth to twentieth aspect, characterized in that a transparent electrode connects between the sustain electrodes.
Furthermore, as a twenty-third aspect, there is provided the plasma display panel set forth in the aforementioned first, second, and fifth to twentieth aspect, characterized in that the sustain electrodes are connected to each other to act as an integrated common bus electrode.
Furthermore, as a twenty-fourth aspect, there is provided the plasma display panel set forth in the aforementioned twenty-third aspect, characterized in that resistance of the common bus electrode is ⅓ to 1/12 of that of the scan-side bus electrode.
Furthermore, as a twenty-fifth aspect, there is provided the plasma display panel set forth in the aforementioned twenty-third aspect, characterized in that the bus electrode has a thickness of 10 to 50 μm, and the thickness of the bus electrode causes a raised portion of thickness 2 to 50 μm to be formed on the surface of the insulating layer.
Furthermore, as a twenty-sixth aspect, there is provided the plasma display panel set forth in the aforementioned first, third, and fifth to twentieth aspect, characterized in that a metal electrode connects between the scan electrodes.
Furthermore, as a twenty-seventh aspect, there is provided the plasma display panel set forth in the aforementioned first, third, and fifth to twentieth aspect, characterized in that a transparent electrode connects between the scan electrodes.
Furthermore, as a twenty-eighth aspect, there is provided the plasma display panel set forth in the aforementioned first, third, and fifth to twentieth aspect, characterized in that the scan electrodes are connected to each other to act as an integrated common bus electrode.
Furthermore, as a twenty-ninth aspect, there is provided the plasma display panel set forth in the aforementioned twenty-eighth aspect, characterized in that resistance of the common bus electrode is ⅓ to 1/12 of that of the sustain-side bus electrode.
Furthermore, as a thirtieth aspect, there is provided the plasma display panel set forth in the aforementioned twenty-eighth aspect, characterized in that the bus electrode has a thickness of 10 to 50 μm, and the thickness of the bus electrode causes a raised portion of thickness 2 to 50 μm to be formed on the surface of the insulating layer.
Furthermore, as a thirty-first aspect, there is provided the plasma display panel set forth in the aforementioned first, second, and fifth to twenty-fifth aspect, characterized in that the distance between the neighboring scan electrodes or the neighboring scan-side bus electrodes on vertically neighboring pixel cells is 20 to 200 μm.
Furthermore, as a thirty-second aspect, there is provided the plasma display panel set forth in the aforementioned first, third, fifth to twentieth, and twenty-sixth to thirtieth aspect, characterized in that the distance between the neighboring sustain electrodes or the neighboring sustain-side bus electrodes on vertically neighboring pixel cells is 20 to 200 μm.
Furthermore, as a thirty-third aspect, there is provided the plasma display panel set forth in the aforementioned first and second aspect, characterized in that the scan electrodes of neighboring pixel cells overlap each other being electrically insulated.
Furthermore, as a thirty-fourth aspect, there is provided the plasma display panel set forth in the aforementioned first and third aspect, characterized in that the sustain electrodes of neighboring pixel cells overlap each other being electrically insulated.
Furthermore, as a thirty-fifth aspect, there is provided the plasma display panel set forth in the aforementioned first to third and fifth to thirty-fourth aspect, characterized in that a notched or cut-away end portion of a display electrode portion disposed in the row direction is spaced apart by 20 to 70 μm from a head portion of a rib disposed in the column direction.
Furthermore, as a thirty-sixth aspect, there is provided the plasma display panel set forth in the aforementioned first and second aspect, characterized in that the sustain electrode has a portion, reduced in width, for connecting to the sustain-side bus electrode.
Furthermore, as a thirty-seventh aspect, there is provided the plasma display panel set forth in the aforementioned first to third and fifth to thirty-sixth aspect, characterized in that the plane discharge electrode is constructed so as to allow pixel cells disposed in the longitudinal column direction to have centers of light emission at equal intervals.
Furthermore, as a thirty-eighth aspect, there is provided the plasma display panel set forth in the aforementioned first to third and fifth to thirty-seventh aspect, characterized in that a horizontal black stripe is disposed between plane discharge electrodes or in the row direction including the plane discharge electrode.
Furthermore, as a thirty-ninth aspect, there is provided the plasma display panel set forth in the aforementioned thirty-eighth aspect, characterized in that horizontal black stripes, all having the same width, are disposed at equal intervals in the column direction to be vertically symmetric with each other in each pixel cell.
Furthermore, as a fortieth aspect, there is provided the plasma display panel set forth in the aforementioned thirty-eighth aspect, characterized in that a horizontal black stripe, a horizontal stripe made up of a scan electrode having a black or gray display side, and a horizontal stripe made up of a black or gray common bus electrode have the same width and are disposed at equal intervals in the column direction.
Furthermore, as a forty-first aspect, there is provided the plasma display panel set forth in the aforementioned thirty-eighth aspect, characterized in that scan electrodes and sustain electrodes are formed on the substrate, and horizontal black stripes are formed on the scan electrode and the sustain electrode.
Furthermore, as a forty-second aspect, there is provided the plasma display panel set forth in the aforementioned forty-first aspect, characterized in that a hole or notch is formed on the horizontal black stripe to ensure electrical connection of the scan electrode or the sustain electrode to the bus electrode.
As described above, the plasma display panel according to the present invention can employ the prior-art driving method to improve the intensity, the luminous efficiency, and the voltage margin. In addition, the plasma display panel can reduce unnecessary power consumption on the bus electrode provided on the sustain electrode and the overall percentage of breaks in the sustain electrode to thereby provide improved fabrication yields. Accordingly, the plasma display panel provides great effects of reducing the power consumption of and improving the reliability of the display device employing the plasma display panel and greatly contributing to saving energy.
In addition, the present invention provides electrodes having a shape equivalent to comb-teeth, thereby making it possible to increase the luminous efficiency. Lattice-shaped ribs allow the electrodes between pixel cells to be closely spaced and thereby the effective opening portion of a pixel cell can be increased. This prevents the intensity from being reduced even when the comb-tooth-shaped electrodes are employed to increase the luminous efficiency. Furthermore, the sustain electrodes or the scan electrodes are connected to each other or shared between the pixel cells, thereby making it possible to provide further increased effective opening portion. This in turn makes it possible to provide further improved intensity and luminous efficiency. Furthermore, it is possible to reduce the resistance of electrodes, increase the voltage margin, improve the fabrication yields of the electrodes in the panel, and reduce the power consumption.
Now, a plasma display panel and its fabrication method according to the present invention will be explained below in more detail with reference to the accompanying drawings in accordance with the embodiments.
On the surface of the second insulating substrate 12 opposite to the first insulating substrate 11, a plurality of column electrodes 14 of thick silver film, having a thickness of 0.5 to 10 μm, are disposed in parallel to each other so as to extend in the row direction. In addition, an insulating layer 18b of thick film having a thickness of 5 to 40 μm is formed so as to cover the column electrode 14 and the inner surface of the second insulating substrate 12. Furthermore, formed on the insulating layer 18b are lattice-shaped ribs 16 of thick film having a thickness of 80 to 150 μm to provide discharge gas spaces 15 and define pixel cells 20, and a phosphor 17 is formed to cover the insulating layer 18b and the sides of the rib 16 inside the pixel cell 20. The phosphor 17 is formed of Zn2SiO4:Mn, for converting UV light produced by discharges in the discharge gas into visible light. The first and second insulating substrates 11 and 12, each having the aforementioned respective constituents formed thereon, are disposed in parallel spaced relation to each other to define the discharge gas space 15, which is filled, at a total pressure of 66.5 kPa, with a gas mixture of He and Ne containing 4% of Xe. The lattice-shaped ribs 16 define the pixel cells 20.
In this embodiment, still referring to
The sustain electrodes 13a and the scan electrodes 13b form a display electrode portion, while the sustain-side bus electrodes 13d and the scan-side bus electrodes 13e form a bus electrode portion. In addition, the sustain electrode 13a and the sustain-side bus electrode 13d are the sustain-side plane discharge electrodes, while the scan electrode 13b and the scan-side bus electrode 13e are scan-side plane discharge electrodes.
For explanatory purposes, this embodiment employs an exemplary panel which can display a so-called XGA-type window for use in personal computers or the like. A monitor of the XGA type has 768 display units in the vertical direction and 1,024 display units in the horizontal direction. Accordingly, the plasma display panel has 768/2=384 sustain electrodes 13a in each column, 768 scan electrodes 13b in each column, and 1024×3=3,072 column electrodes 14. The plasma display panel has color pixels arranged in vertical stripes, and color pixels acting as one display unit consist of three primary color pixel cells arranged in three columns. For example, the color pixel cells are arranged at the same 0.6 mm intervals in the vertical and horizontal directions. The ratio of the vertical to the horizontal dimension of the color pixel cell can take on 9:16, thereby making it possible to support a wide window that is frequently used by televisions or the like to display moving pictures. Alternatively, with the vertical and horizontal pitches remaining unchanged, the number of color pixel cells can be changed to support a wide window. For example, vertical color pixel cells may be 768 in number and horizontal color pixel cells may be 1365 in number.
Still referring to
For example, the bus electrodes 13d, 13e have a width of 70 μm. For example, the distance between the bus electrodes of vertically adjacent pixel cells 20 is 70 μm. The end portion of the transparent scan electrode 13b and the scan-side bus electrode 13e overlap each other, for example, by 40 μm. For example, the pitch of the column electrodes 14 is 0.2 mm.
In the plasma display panel configured as described above, the either side of the rectangular sustain electrode 13a and the rectangular scan electrode 13b is spaced apart from the rib 16 in the row direction, thereby making it possible to reduce discharges of low luminous efficiency from the plane discharge electrodes near the rib 16 and thus increase the luminous efficiency. That is, since the scan electrode 13b and the sustain electrode 13a are spaced apart from the ribs 16 adjacent thereto in the row direction, the discharge at portions of low luminous efficiency near the rib 16 is prevented to increase the ratio of light emission from portions of high luminous efficiency, thereby making it possible to increase luminous intensity with respect to the amount of input power.
Furthermore, this embodiment allows the lattice-shaped ribs 16 to block and thereby suppress spurious discharges which occur between the sustain electrodes or the scan electrodes of pixel cells adjacent to each other in the column direction. This makes it possible to place the sustain-side bus electrode 13d and the scan-side bus electrode 13e in close proximity to the ribs 16 to which the either electrode resides in parallel. A portion within one pixel cell which emits light with high intensity is an opening portion (hereinafter referred to as an effective opening portion) residing between the sustain-side bus electrode 13d and the scan-side bus electrode 13e. As described above, placing both the sustain-side bus electrode 13d formed of Ag and the scan-side bus electrode 13e in close proximity to the rib 16 would make it possible to provide an enlarged opening portion for emitting light with high intensity in the pixel cell, thereby allowing the intensity and the luminous efficiency to increase. Accordingly, this can sufficiently compensate for a decrease in intensity caused by the sustain electrode 13a and the scan electrode 13b formed in a rectangular shape.
In this embodiment, the sustain electrode 13a is disposed across pixel cells 20 adjacent to each other in the column direction in orthogonal relation to the rib 16 that is parallel to the sustain-side bus electrode 13d. The transparent electrodes cannot be visually recognized and apparently remain unchanged when compared with conventional ones, and make it possible to connect between the sustain electrodes 13a of neighboring pixel cells. Thus, two neighboring sustain-side bus electrodes 13d are electrically coupled to each other, thereby making it possible to reduce the overall electrode resistance of the two neighboring sustain-side bus electrodes 13d, for example, substantially by one-half. This provides a reduction in voltage drop across the sustain-side bus electrode 13d and a reduced rate of reduction in the voltage applied to the sustain electrode 13a of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing more stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages. This is hereinafter referred to as an “increase in operational voltage margin”.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the aforementioned maximum voltage and an increase in the aforementioned minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
Furthermore, two neighboring sustain-side bus electrodes 13d are electrically coupled to each other. Thus, even when one of the sustain-side bus electrodes 13d is on the verge of a break, the other neighboring sustain-side bus electrode 13d supplies current, thereby making it possible to provide increased yield of fabrication for a break in the electrodes.
Incidentally, the drive waveform according to the first embodiment of the method for driving the plasma display panel of the present invention is the same as that of
Fabrication Method
Now, described below is a method for fabricating the aforementioned plasma display panel according to the first embodiment of the present invention. Explained first is a method for encapsulating and evacuating the plasma display panel having the configuration according to the first embodiment shown in FIGS. 7 to 9. In the plasma display panel shown in FIGS. 7 to 9, there exist slight gaps due to projected and recessed portions on the upper surfaces of the ribs 16 and the protective layer 19; however, each of the pixel cells is generally sealed by means of the ribs 16. According to the prior-art method, the first insulating substrate 11 and the second insulating substrate 12 are affixed to each other at the seal portion 21 (see
In this regard, to overcome this drawback, this embodiment is adapted to carry out part of the encapsulating step in a vacuum and subsequently a gas is introduced into the plasma display panel. This makes it possible to reduce the considerably long time required by the prior-art method for evacuating the panel to a vacuum. This fabrication method is hereinafter referred to as the vacuum encapsulation.
Now, the vacuum encapsulation process in the fabrication method according to this embodiment is explained step by step.
Step 1: First, the processed first insulating substrate 51 and the processed second insulating substrate 52 are inserted into the encapsulation chamber 40. With this arrangement, the seal portion 21 formed of low-melting glass and having a height 1.5 times as high as that of the rib 16 provides a sufficient gap between the first insulating substrate 51 and the second insulating substrate 52. In addition, at this stage, the insulating substrates 51 and 52 are aligned with each other in advance for the subsequent encapsulation. All the valves 45 to 48 and 73 to 75 are closed. The vacuum pumps 41 and 42 are activated.
Step 2: Then, the valve 46 is once opened to evacuate the chamber 40 and then closed. In addition, the valve 75 is once opened to evacuate the chamber 40 and then closed. This provides a degree of vacuum less than the atmospheric pressure or 10 Pa or greater in the encapsulation chamber 40, preferably a degree of vacuum 1 kPa to 50 kPa. These degrees of vacuum are provided to allow the insulating substrates 51 and 52 to be readily heated in a short period of time by the heat conduction of the gas in the encapsulation chamber.
Step 3: The encapsulation chamber 40 is heated by a heater or the like installed outside or inside the encapsulation chamber 40 to remove moisture or oil present on the insulating substrate 51 or the inner wall of the encapsulation chamber. In this case, the inside of the encapsulation chamber 40 is heated up to about 250 to 360° C. or preferably up to about 300 to 360° C. The heating is to be carried out up to the maximum temperature at which the low-melting glass used for the seal portion 21 is not softened.
Step 4: After the insulating substrates 51 and 52 have been heated up to a desired temperature in step 3, the valve 46 is opened slowly to allow the inside of the encapsulation chamber 40 to be evacuated to a vacuum. The moisture and oil, which have evaporated inside the encapsulation chamber 40, are thereby eliminated. Under this condition, the low-melting glass of the seal portion 21 has not yet been softened, and the first insulating substrate 51 and the second insulating substrate 52 provide a sufficient gap therebetween, thereby making it possible to effectively remove the evaporated moisture and oil.
Step 5: The encapsulation chamber 40 is further heated up to a higher temperature from about 430 to 470° C. This causes the material of the seal portion 21 or the low-melting glass to be softened, thereby allowing the substrates 51 and 52 having been thoroughly evacuated to be bonded together.
Step 6: Now, the temperature of the encapsulation chamber 40 is lowered close to the room temperature. Alternatively, the temperature of the substrates 51 and 52, encapsulated by the heat conduction of a gas, may be lowered. In this case, the valve 46 is closed, the valve 48 is slightly opened once, and the discharge gas is introduced into a gas heating portion 49. Then, after the valve 48 has been closed, the valve 47 is slightly opened, the discharge gas is introduced into the encapsulation chamber 40, and then the valve 47 is closed again. At this time, the pressure of the gas in the encapsulation chamber is about 1 Pa to 1 kPa. Thus, the temperature of the encapsulated substrates 51 and 52 is lowered as the temperature of the encapsulation chamber 40 becomes lowered. Incidentally, just before starting to lower the temperature of the encapsulation chamber 40, the valve 75 is opened to further evacuate the inside of the encapsulated substrates 51 and 52 to a vacuum.
Step 7: The valve 75 is closed when the temperature of the encapsulated substrates 51 and 52 has been lowered close to the room temperature. Then, the valve 48 and the valve 73 are opened to introduce the discharge gas from the gas cylinder 43 into the encapsulated substrates 51 and 52. After the discharge gas has been introduced into the encapsulated substrates 51 and 52, the valve 48 and the valve 73 are closed.
Step 8: The exhaust pipe 71b is heated at the portion of line E-E shown in
Through the steps described above, the plasma display panel, having almost sealed pixel cells, shown in the first embodiment can be easily encapsulated and provided with a discharge gas therein in a short period of time. That is, the present invention allows the first insulating substrate 51 and the second insulating substrate 52 to be evacuated to a vacuum as a whole in the encapsulation chamber 40 and then heated, thereby bonding and affixing the substrates 51 and 52 to each other at the seal portion 21. Then, after the temperature of the substrates 51 and 52 has been lowered in the chamber 40, a discharge gas is introduced therein. Increasing the temperature upon encapsulation causes gases to come out of the surface of the glass substrates 51 and 52 and the material of the seal portion 21. However, since the inside of the encapsulation chamber 40 and the gap between the substrates 51 and 52 have been evacuated to a vacuum upon encapsulation, these emitted gases can be exhausted quickly out of the panel. As described above, gases are thoroughly emitted from the surface of the glass substrates 51 and 52 and the sealing material, and a discharge gas is introduced into between the substrates 51 and 52 via the hole 70 after the temperature of the substrates 51 and 52 has been lowered. For this reason, this prevents the discharge gas from being contaminated and allows the discharge gas to be introduced into between the substrates with high service efficiency.
Now, a plasma display panel according to a second embodiment of the present invention will be described with reference to FIGS. 10 to 12. In FIGS. 10 to 12, the same components as those of FIGS. 7 to 9 are provided with the same reference symbols and will not be explained in detail again. The first embodiment shown in FIGS. 7 to 9 employs transparent electrodes as the sustain electrode 13a and the scan electrode 13b. However, the present invention is not limited thereto and can employ not only transparent electrodes but also thin metal electrodes.
As shown in FIGS. 10 to 12, this embodiment employs gate-shaped sustain electrodes 13a and scan electrodes 13b formed of metal. These electrodes can be formed through the same process as that for the sustain-side bus electrode 13d and the scan-side bus electrode 13e. These electrodes have a narrow width and therefore do not considerably block light emission. This lessens the need to employ transparent materials and the step of forming transparent electrodes can be omitted by employing metal electrodes as in this embodiment. This in turn makes it possible to reduce costs.
Incidentally, the metal electrode is not limited to the gate-shaped type and can employ various shapes such as a lattice-shaped or T-shaped type. Furthermore, the metal electrode can be formed in a fine mesh shape.
Now, a fourth embodiment of the present invention is described below.
The plasma display panel according to the fourth embodiment of the present invention provides a flow path for a gas to be exhausted therethrough to a vacuum, thereby making it possible to perform exhaustion easily by the same encapsulating and exhausting method as the prior-art method. Incidentally, in
Now, a fifth embodiment of the present invention is described below.
Even with projections residing at the intersections of the lattice-shaped ribs, the rib projections 53 allow the scan-side bus electrode 13e and the sustain-side bus electrode 13d to be separated from each other between neighboring pixel cells, thereby making it possible to prevent spurious light emission caused by currents flowing through the scan-side bus electrode 13e and the sustain-side bus electrode 13d between the neighboring pixel cells.
Incidentally, the rib projections 53 can be formed not on top of the ribs 16 as shown in
Now, a sixth embodiment of the present invention is described below.
The sixth embodiment provides an effect of facilitating vacuuming upon encapsulation. Furthermore, the central portion of each side of the ribs for defining pixel cells is separated by the ribs 16, thereby making it possible to reduce vertical and horizontal spurious light emission through the gaps communicating between pixel cells.
Now, a seventh embodiment according to the present invention is described below.
Unlike the fifth embodiment, this embodiment allows the scan-side bus electrode 13e, the sustain-side bus electrode 13d, and the sustain electrode 13a to be separated between neighboring pixel cells by the rib portions other than the rib recesses 54 residing on the intersections of the lattice-shaped ribs.
This seventh embodiment provides an effect of facilitating vacuuming upon encapsulation. Furthermore, the central portion of each side of the ribs 16 for defining pixel cells separates the gap between pixel cells, also defining the scan electrode 13b, the sustain electrode 13a, and the bus electrode 13c between neighboring pixel cells. Thus, even with the rib recesses 54 residing on the intersections of the lattice-shaped ribs 16, it is possible to effectively prevent spurious light emission transmitting along the scan electrode 13b, the sustain electrode 13a, and the bus electrode 13c between the neighboring pixel cells.
Now, an eighth embodiment according to the present invention is described below.
This eighth embodiment is different from the first embodiment in having horizontal barrier walls 23. In this embodiment, the horizontal barrier wall 23 is formed on top of the insulating layer 18a of the first insulating substrate 11. The horizontal barrier wall 23 has a height of 2 to 50 μm and desirably 5 to 30 μm. In addition, the horizontal barrier wall 23 is located between the sustain-side bus electrodes 13d and between the scan-side bus electrodes 13e.
It is possible to form the horizontal barrier wall 23, using a patterned screen, by employing the thick-film printing method to perform pattern printing directly on the insulating layer 18a and then by baking the horizontal barrier wall 23. Alternatively, a photosensitive paste can be printed on a plane by contact printing and dried, which is in turn radiated with UV light through masks, exposed, developed, dried, and then baked to form a pattern.
The horizontal barrier wall 23 can be formed of a transparent glass material. Alternatively, to increase contrast, the material may be mixed with a black material (such as cobalt oxide, ruthenium oxide, or iron oxide). Alternatively, to provide efficient reflections of light emitted from pixel cells, titanium oxide, zirconium oxide, alumina, silicon oxide, or the like) may be mixed with the material to form a white material. Alternatively, the display side (on the side of the first insulating substrate 11) may be formed in black to provide increased contrast, whereas the pixel interior side may be formed in white to provide effective reflections of light generated inside pixel cells.
The horizontal barrier wall 23 provides an exhaustion path in the longitudinal direction of the scan-side bus electrode 13e. This makes it possible, without using the vacuum encapsulation described with reference to
To eliminate unnecessary power consumption required for charging or discharging electrostatic capacitance by pulse voltages applied upon driving the plasma display panel, it is desirable that the electrostatic capacitance should be small between the scan-side bus electrodes 13e in neighboring pixel cells and between the sustain-side bus electrode 13d, the scan-side bus electrode 13e, and the column electrode 14. In this context, the material of the horizontal barrier wall 23 has desirably a low dielectric constant. It is possible to employ a zinc-oxide-based glass material (having a dielectric constant of about 8) instead of a lead-glass-based insulating material (having a dielectric constant of about 13) to reduce the dielectric constant, thereby reducing the power consumption of the plasma display panel.
The horizontal barrier wall 23 provides an exhaustion path in the longitudinal direction of the scan-side bus electrode 13e. This makes it possible, without using the vacuum encapsulation described with reference to
Furthermore, the reduction in dielectric constant of the horizontal barrier wall 23 results in a reduction in electrostatic capacitance between electrodes, thereby making it possible to prevent an increase in ineffective power consumption.
Now, a ninth embodiment according to the present invention is described below.
Now, a tenth embodiment according to the present invention is explained below.
Now, an eleventh embodiment according to the present invention is described below.
Now, a twelfth embodiment according to the present invention is described below.
The horizontal barrier wall 23 has a height of 2 to 50 μm, desirably 5 to 30 μm. In addition, the horizontal barrier wall 23 is located between the pixel cells corresponding to the sustain-side bus electrodes 13d adjacent to each other or between the pixel cells corresponding to the scan-side bus electrodes 13e, on the second insulating substrate 12.
The horizontal barrier wall 23 can be formed integrally with the ribs 16. Alternatively, it is possible to form the horizontal barrier wall 23, using a patterned screen, by employing the thick-film printing method to directly perform pattern printing on the ribs 16 having a uniformly formed height and then by baking the horizontal barrier wall 23. Alternatively, the horizontal barrier wall 23 can also be formed using a photosensitive paste in the same manner as that of the fourth embodiment.
The horizontal barrier wall 23 can be formed of a transparent glass material. Alternatively, to increase contrast, the material may be mixed with a black material (such as cobalt oxide, ruthenium oxide, or iron oxide). Alternatively, to provide efficient reflections of light emitted from pixel cells, titanium oxide, zirconium oxide, alumina, silicon oxide, or the like) may be mixed with the material to form a white material.
Like the eighth embodiment, this embodiment allows the horizontal barrier wall 23 to provide an exhaustion path in the longitudinal direction of the scan-side bus electrode 13e. This makes it possible, without using the vacuum encapsulation described with reference to
Now, a thirteenth embodiment according to the present invention is described below.
That is, the ribs 16 located to overlap the bus electrodes 13d, 13e can prevent the light emission on the bus electrodes 13d, 13e, thereby making it possible to increase the luminous efficiency. This in turn makes it possible to increase intensity for the same light emission power. In other words, with the intensity remaining unchanged, the light emission power can be reduced.
Now, a fourteenth embodiment according to the present invention is described below.
This in turn makes it possible to increase intensity for the same light emission power. In other words, with the intensity remaining unchanged, the light emission power can be reduced. Furthermore, since the bus electrodes 13d, 13e do not overlap the ribs 16, the electrostatic capacitance between the scan electrode 13b or the sustain electrode 13a and the column electrode 14 is reduced.
Now, a fifteenth embodiment according to the present invention is described below.
The horizontal barrier wall 23 and the rib 16 located to overlap the bus electrodes 13d, 13e can prevent the light emission on the bus electrodes 13d, 13e, thereby making it possible to increase the luminous efficiency. White ribs 16 would reflect visible light from ribs, thereby making it possible to further increase the luminous efficiency. This increase in light emission in turn makes it possible to increase intensity for the same light emission power. In other words, with the intensity remaining unchanged, the light emission power can be reduced.
Incidentally, in the thirteenth to fifteenth embodiments, the sustain-side bus electrodes 13d and the scan-side bus electrodes 13e have the same thickness as that of the prior art ones (about 3 to 8 μm). However, in these embodiments, since the discharges on the sustain-side bus electrodes 13d and the scan-side bus electrodes 13e are substantially prevented, these bus electrodes 13d, 13e may be made greater in width than those of prior art. More specifically, with the bus electrodes 13d, 13e being increased in width up to about 10 to 25 μm, the insulating layer 18a (normally having a thickness of 20 to 40 μm) having a decreased thickness would cause an extremely large discharge, preventing the insulating layer 18a and the protective layer 19 from being subjected to an electrical breakdown.
This makes it possible to reduce the electrode resistance of the sustain-side bus electrode 13d and the scan-side bus electrode 13e to about ½ to ⅕ of the conventional value. This also causes the voltage drop across the sustain-side bus electrode 13d and the scan-side bus electrode 13e to be made smaller than conventional value. This provides a reduced rate of reduction in the voltage applied to the sustain electrode 13a or the scan electrode 13b of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing more stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the aforementioned maximum voltage and an increase in the aforementioned minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
Now, a sixteenth embodiment according to the present invention is described below.
As described above, to raise the sustain-side bus electrode 13d and the scan-side bus electrode 13e to cause the insulating layer 18a to be also raised, control may be exercised over the leveling property of the insulating layer paste upon being dried and the reflow property thereof upon being baked, by the material and adjustment of baking temperatures upon printing, drying, and baking the thick insulating layer 18a. For example, the amount of the thinner component of print paste is reduced to be less than usual and the maximum temperature of baking is also reduced by about 5 to 50° C., thereby making it possible to form the bump 64. Furthermore, it is also effective to reduce the maximum temperature of baking and the length of time periods of the maximum temperature and temperatures before and after the maximum temperature.
This embodiment with the configuration described above can provide an effect equivalent to the horizontal barrier wall 23 without forming the horizontal barrier wall 23. This makes it possible to facilitate the fabrication process and provide a significant reduction in cost.
For example, the sustain-side bus electrode 13d and the scan-side bus electrode 13e have a thickness of 10 to 50 μm. Correspondingly, the bump 64 can have a height of 2 to 50 μm at the portions having no underlying bus electrodes 13d, 13e. The bus electrodes 13d, 13e conventionally have a thickness of 1 to 9 μm and about 5 μm on average. In contrast, this embodiment provides the bus electrodes 13d, 13e with a thickness of 10 to 50 μm. Thus, this embodiment provides a second effect that the resistance of the sustain-side bus electrode 13d and the scan-side bus electrode 13e can be reduced to ½ to 1/10 of the conventional average electrode resistance.
Furthermore, the sustain electrode 13a connects electrically two neighboring sustain-side bus electrodes 13d to each other. It is therefore possible to substantially reduce the overall electrode resistance of the two neighboring sustain-side bus electrodes 13d to ¼ to 1/20 of the conventional value. This reduces the voltage drop across the sustain-side bus electrode 13d to be significantly less than that provided by the first embodiment. This makes it possible to reduce the rate of reduction, caused by the voltage drop across the sustain-side bus electrode 13d, in the voltage applied to the sustain electrode 13a of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing more stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the aforementioned maximum voltage and an increase in the aforementioned minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
Furthermore, two neighboring sustain-side bus electrodes 13d are electrically coupled to each other. Thus, even when one of the sustain-side bus electrodes 13d is on the verge of a break, the other neighboring sustain-side bus electrode 13d supplies current, thereby making it possible to provide increased yield of fabrication for a break in the electrodes. Incidentally, when thick bus electrodes 13d, 13e are employed as in this embodiment, it is possible to use a silver paste increased in volume by mixing the paste with a fine particle filler formed such as of alumina or silica to avoid an increase in cost caused by the expensive silver paste.
Now, a seventeenth embodiment according to the present invention is described below.
This allows the connecting portion 56 to electrically connect two neighboring sustain-side bus electrodes 13d to each other, thereby making it possible to substantially reduce the overall electrode resistance of the two neighboring sustain-side bus electrodes 13d by one-half. This provides a reduction in voltage drop across the sustain-side bus electrode 13d and a reduced rate of reduction in the voltage applied to the sustain electrode 13a of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing further stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the aforementioned maximum voltage and an increase in the aforementioned minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
Furthermore, two neighboring sustain-side bus electrodes 13d are electrically coupled to each other. Thus, even when one of the sustain-side bus electrodes 13d is on the verge of a break, the other neighboring sustain-side bus electrode 13d supplies current, thereby making it possible to provide increased yield of fabrication for a break in the electrodes. This effect is greater than that provided by the first embodiment in which transparent electrodes, greater in resistance than the bus electrode by several orders of magnitude, between the bus electrodes.
Incidentally, referring to
Now, an eighteenth embodiment according to the present invention is described below.
This allows the two neighboring sustain-side bus electrodes 13d to be electrically connected to each other to perfection. As described in the first embodiment, the non-shared sustain-side bus electrode 13d or scan-side bus electrode 13e has a width of 70 μm, while the sustain-side bus electrodes 13d or the scan-side bus electrodes 13e between vertically neighboring pixel cells are arranged at 70 μm intervals. Accordingly, the common bus electrode 57 can have a width of 210 μm.
This makes it possible to reduce the electrode resistance of the common bus electrode 57 to approximately ⅓ of that of the scan-side bus electrode 13e. In addition, the common bus electrode 57 may be increased in thickness from 1 through 9 μm, 5 μm on average as mentioned in the first embodiment, to 20 μm, thereby making it possible to reduce the resistance of the common bus electrode 57 to 1/12 of that of the scan-side bus electrode 13e.
This allows the voltage drop across the sustain-side bus electrode (the common bus electrode 57) to be further reduced from that of the sixteenth embodiment. This provides a reduced rate of reduction in the voltage applied to the sustain electrode 13a of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing more stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the aforementioned maximum voltage and an increase in the aforementioned minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
In addition, the two neighboring sustain-side bus electrodes 13d are completely integrated with each other. This allows the common bus electrode 57 to have a width three to six times greater than that of the conventional sustain-side bus electrode 13d. This makes it possible to increase the fabrication yield twice or more for a break in the electrodes. This effect is greater than that provided by the seventeenth embodiment in which the connecting portion 56 connects between the sustain-side bus electrodes 13d.
Incidentally, the display side of the bus electrode portion is formed in black. In this regard, with the scan-side bus electrode 13e being greatly different in shape from the common bus electrode 57 as in the eighteenth embodiment shown in FIGS. 34 to 36, the configuration having intervals twice as large as the pitch of pixel cells would provide bad impression to the viewer. However, blackening between the neighboring scan-side bus electrodes 13e by means of the black horizontal barrier wall 23 would make it possible to eliminate the feeling of being apparently interfered.
Now, a nineteenth embodiment according to the present invention is described below.
As described above, to raise the common bus electrode 57 and the scan-side bus electrode 13e to raise also the insulating layer 18a to form the bump 64 thereon, control may be exercised over the leveling property of the insulating layer paste upon being dried and the reflow property thereof upon being baked, by the material and adjustment of baking temperatures upon printing, drying, and baking the thick insulating layer 18a. For example, the amount of the thinner component of print paste is reduced to be less than usual and the maximum temperature of baking is also reduced by about 5 to 50° C., thereby making it possible to form such a bump 64. Furthermore, it is also effective to reduce the maximum temperature of baking and the length of time periods of the maximum temperature and temperatures before and after the maximum temperature.
This embodiment with the configuration described above can provide an effect equivalent to the horizontal barrier wall 23 without forming the horizontal barrier wall 23. This makes it possible to facilitate the fabrication process and provide a significant reduction in cost.
The common bus electrode 57 and the scan-side bus electrode 13e can have a thickness of 10 to 50 μm. Correspondingly, the bump 64 can have a height of 2 to 50 μm at the portions having no underlying bus electrodes 13d, 57. The bus electrodes 13d, 57 conventionally have a thickness of 1 to 9 μm and about 5 μm on average. In contrast, this embodiment provides the bus electrodes 13d, 57 with a thickness of 10 to 50 μm. Thus, this embodiment provides a second effect that the resistance of the scan-side bus electrode 13e can be reduced to ½ to 1/10 of the conventional average electrode resistance.
Furthermore, the two neighboring sustain-side bus electrodes 13d are completely connected to each other to form the common bus electrode 57. It is therefore possible to reduce the electrode resistance of the common bus electrode to ⅙ to 1/30 of that of the two neighboring sustain-side bus electrodes 13d. This reduces the voltage drop across the sustain-side bus electrode 13d to be much less than that provided by the seventeenth embodiment. This provides a reduced rate of reduction in the voltage applied to the sustain electrode 13a of each pixel cell. This provides a reduction in minimum voltage to be applied from outside during a light emission discharge and reduced spurious erases for discharging pixel cells, thereby providing more stabilized display operation. Incidentally, the maximum voltage remains unchanged which can be applied from outside without causing spurious discharges during a light emission discharge. This makes it possible to provide an increased operational voltage margin or the difference between the aforementioned maximum and minimum voltages.
Thus, it is made possible to set voltages with sufficient allowance with respect to a decrease in the maximum voltage and an increase in the minimum voltage caused by long-term operation. This allows the longevity of the plasma display panel to increase which is affected by spurious discharges or spurious erases, thereby making it possible to significantly improve the long-term reliability of the display device employing the plasma display panel.
Furthermore, the present invention allows the two sustain-side bus electrodes 13d, which are adjacent to each other in the prior-art configuration, to be completely integrated with each other, thereby making it possible to provide increased yield of fabrication for a break in the electrodes. This effect is greater than that provided by the seventeenth embodiment in which the connecting portion 56 connects between the sustain-side bus electrodes 13d.
Now, a twentieth embodiment according to the present invention is described below.
Now, a twenty-first embodiment according to the present invention is described below.
Now, a twenty-second embodiment according to the present invention is described below.
Experiments carried out by the present inventor show that this configuration provided by the prior-art design technique causes the discharge gap centerline 60, or the center of light emission, to be displaced from the pixel cell centerline 59 for defining the center of pixel cells to vary the centers of light emission at every two pixel cells in the vertical direction, thereby visualizing stripes having intensities that vary at pitch intervals twice as large as the vertical pixel cell pitch.
As shown in
In addition, by narrowing the root of the sustain electrode 13a as shown in
With such an electrode arrangement, it is possible to effectively prevent the horizontal stripes from being viewed which have a repetitive pattern at twice pitch intervals.
Now, a twenty-third embodiment according to the present invention is described below.
In addition, suppose that white silver or the like having a high electrical conductivity is employed as the scan-side bus electrode 13e or the common bus electrode 57. Even in this case, the horizontal BS 62 is disposed so as to cover the bus electrodes 13e, 57, thereby providing a reduced surface reflectivity. For this reason, it is possible to use white silver electrodes of low resistance as the scan-side bus electrode 13e and the common bus electrode 57.
In the prior art, to reduce the reflectivity of bus electrodes formed of white silver, electrodes of black silver or the like were formed on the display side of the scan-side bus electrode 13e and the common bus electrode 57. However, the black silver is as expensive as the white silver and thus its drawback is the high cost of making electrodes. However, it is possible to reduce the cost by employing the comparatively inexpensive black BS 62 as in this embodiment.
Now, a twenty-fourth embodiment according to the present invention is described below.
Now, a twenty-fifth embodiment according to the present invention is described below.
The horizontal BS 62, a horizontal stripe formed of two neighboring black or gray scan-side bus electrodes 13e, and a horizontal stripe formed of a black or gray sustain-side bus electrode 13d are adapted to have the same width and all the horizontal stripes are disposed at the same intervals. This makes it possible to prevent horizontal fringes occurring in the vertical direction at pitch intervals twice as great as the pixel cell pitch. With the entire display side being formed in black, the scan-side bus electrode 13e and the common bus electrode 57 provide an effect of further enhancing contrast.
Now, a twenty-sixth embodiment according to the present invention is described below.
Forming the scan electrode 13b and the sustain electrode 13a, which are thinner by ⅕ or more than the horizontal BS 62, on the horizontal BS 62 would cause a break in the scan electrode 13b and the sustain electrode 13a to be apt to occur due to the stepped portion at the edge of the horizontal BS 62. However, with the arrangement described above, this break can be effectively prevented. In this case, it is necessary to ensure the electrical connection between the scan electrode 13b and the scan-side bus electrode 13e or between the sustain electrode 13a and the common bus electrode 57. To this end, it is effective to increase the diameter of particles of the material for use with the horizontal BS 62 to make the structure of the horizontal BS 62 porous, thereby ensuring the electrical connection between the scan electrode 13b and the scan-side bus electrode 13e or between the sustain electrode 13a and the common bus electrode 57.
Alternatively, as shown in a modified example of this embodiment of
The aforementioned embodiments are adapted to be driven by the same method as that of the prior art, allowing each pixel cell to have an independent scan electrode and pixel cells adjacent to each other in the column direction (the vertical direction) to share a common electrode. However, the present invention is intended to specify the structure of pixel cells of a plasma display panel but not intended to specify how to use each electrode. Thus, as a matter of course, the scan electrode described above with reference to the foregoing embodiments may be used as the sustain electrode and the sustain electrode may also be used as the scan electrode. An example of a driving method for this case is explained briefly below.
Pixel cells 20 are defined at the intersections of a pair of scan electrodes 113b and a sustain electrode 113a, parallel to one another, and the column electrodes 14 orthogonal thereto. Vertically neighboring pixel cells 20 share the scan electrodes 113b, which are in turn coupled to the output pin of a scan driver IC (not shown). With this arrangement, the number of outputs of the scan driver IC is one-half of that of the display lines. The sustain electrodes 113a are divided into a first sustain electrode group 103a located above the scan electrodes 113b and a second sustain electrode group 103b located below the scan electrodes 113b. Electrical connection (not shown) is provided for each of the groups outside the panel or outside the display area within the panel.
The operation by the driving method is explained below with reference to
Then, during the first select operation cycle B, a scan pulse Vw is applied to the scan electrode 113b and a data pulse Vd is applied to the column electrode 14 in response to display data. This causes the wall charges to vanish only in the pixel cell 20 to which the data pulse Vd has been applied. Furthermore, a first sustain discharge pulse Vs11 is applied to the scan electrode 113b to cause a discharge to occur only at the pixel cell 20a having wall charges built up or in the “ON” state. At the same time, wall charges of reversed polarities are built up on the scan electrode 113b and the sustain electrode 113a, respectively.
Likewise, during the subsequent second preliminary discharge cycle C and second select operation cycle D, a selective operation is carried out only in the pixel cell 20b including the sustain electrode group 103b to cause wall charges to build up only in the pixel cell 20b that is in the “ON” state.
Then, during the sustain cycle E, a discharge sustain pulse Vs having a reversed polarity is applied to all the scan electrodes 113b and sustain electrodes 113a, thereby causing a discharge only in the pixel cells 20, where the wall charges have not been erased, to obtain light emission for display purposes during the select operation cycles B and D. Furthermore, during the sustain erase cycle F, a blunt-waveform sustain erase pulse Ve is applied to erase wall charges to thereby terminate the discharge, and then operation proceeds to the subsequent sub-field. By the foregoing operations, it is possible to perform the “ON” and “OFF” control on all the pixel cells 20 within one sub-field.
As described above, it is also possible to perform the light-emitting and non-light-emitting control on each pixel cell by allowing pixel cells adjacent to each other in the vertical direction to share a scan electrode and using an independent sustain electrode for each pixel cell.
Furthermore, in each of the aforementioned embodiments, the scan electrode and the sustain electrode are completely cut apart in the row direction and each pixel cell is provided with a separate scan electrode 13b and sustain electrode 13a. However, the effects of the present invention can be obtained even by the scan electrode 13b and the sustain electrode 13a which are provided with a notched portion between pixel cells 20 adjacent to each other in the row direction and thus not completely separated from each other.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2000-223185 | Jul 2004 | JP | national |
This is a divisional of application Ser. No. 11/249,399 filed Oct. 14, 2005, which is a divisional of application Ser. No. 09/909,910 filed Jul. 23, 2001; the entire disclosures of which are considered part of the disclosure of the accompanying divisional application and are incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11249399 | Oct 2005 | US |
| Child | 11930399 | Oct 2007 | US |
| Parent | 09909910 | Jul 2001 | US |
| Child | 11249399 | Oct 2005 | US |
