BRIEF DESCRIPTION OF THE APPENDED DRAWINGS
FIG. 1A and FIG. 1B show the structure of a conventional plasma display panel; FIG. 1C shows an example of voltage provided to the scan electrode in the sustain period.
FIG. 2 is a schematic diagram of opposite discharge in a certain lighting cell in the prior art.
FIG. 3 is a schematic diagram of a plasma display panel according to a preferred embodiment of the invention.
FIG. 4 shows an example of voltage provided to the scan electrode in the sustain period.
FIG. 5 is a schematic diagram of opposite discharge in certain lighting cell in the invention
FIG. 6 shows the scan voltages corresponding to two adjacent rows of lighting cells.
FIG. 7 shows the respective current directions of two adjacent rows of lighting cells when the electrodes discharge after providing the above scan voltages.
FIG. 8 shows the scan electrode and auxiliary electrode after their shapes are changed.
FIG. 9A shows the shadow mask of another preferred embodiment according to the invention; FIG. 9B and FIG. 9C show the configure mode of the scan electrode and the auxiliary electrode.
FIG. 10 is a schematic diagram of the plasma display panel including 2*N scan electrodes in the preferred embodiment.
FIG. 11 shows the scan voltages corresponding to two adjacent rows of lighting cells.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a plasma display panel with high lightness, long lifetime, and high yield of manufacturing process.
According to the invention, a preferred embodiment is a plasma display panel including a front plate, a back plate, and N rows and M columns of lighting cells. N and M are both positive integers. In practical applications, as shown in FIG. 1A and FIG. 1B, the lighting cells are a plurality of spaces separated by a shadow mask located between the front plate and the back plate; the shadow mask can include a plurality of barrier ribs and a plurality of color phosphors.
In the embodiment according to the invention, the front plate includes N scan electrodes and N auxiliary electrodes. The back plate includes M address electrodes. The ith row of lighting cells among the N rows of lighting cells corresponds to the ith scan electrode among the N scan electrodes and the ith auxiliary electrode among the N auxiliary electrodes, wherein i is an integer index ranging from 1 to N. Moreover, the jth lighting cell in the ith row of lighting cells corresponds to the jth address electrode among the M address electrodes, wherein j is an integer index ranging from 1 to M. In other words, each row of lighting cells corresponds to a scan electrode and an auxiliary electrode; each column of lighting cells corresponds to an address electrode.
Referring to FIG. 3, FIG. 3 is a schematic diagram of the preferred embodiment. In order to make the schematic diagram clearer, the front plate and the back plate are not shown in the diagram. Mark 30 represents the shadow mask located between the front plate and the back plate. Mark 32 represents the lighting cells. Marks 34, 36, and 38 represent a scan electrode, an auxiliary electrode, and an address electrode respectively.
According to the invention, when certain lighting cell 32 is assigned to be lightened, the scan electrode 34, auxiliary electrode 36, and address electrode 38 corresponding to the lighting cell 32 are operated to generate discharge effects in the lighting cell 32.
In practical applications, during a first sustain period for lightening the jth lighting cell in the ith row of lighting cells 32, an ith scan voltage is applied to the ith scan electrode 34; an ith auxiliary voltage is applied to the ith auxiliary electrode 36, and a jth address voltage is applied to the jth address electrode 38. As shown in FIG. 4, the ith scan voltage includes a first AC voltage. The ith auxiliary voltage and the jth address voltage are substantially DC voltages. In practical applications, if each of the auxiliary voltages is designed to have the same value, the N auxiliary electrodes 36 can be connected with each other.
Referring to FIG. 5, FIG. 5 shows the discharge condition according to the lighting cell 32 in the invention. The discharge phenomenon is generated not only between the scan electrode 34 and the address electrode 38, but also between the scan electrode 34 and the auxiliary electrode 36. Due to the effect of the address electrode 38, the discharge between the scan electrode 34 and the auxiliary electrode 36 can be far away from the front plate and can move toward the direction of the address electrode 38. This increases the discharge area within the lighting cell 32. Compared to those in the prior art in which each of the lighting cells has only one discharge area concentrated in the central part, the discharge distance in this invention is longer, and the lighting efficiency is higher in the lighting cell 32. The color phosphors spread on the upside and the downside of the lighting cell 32 can also be fully utilized. By enlarging the discharge area within the lighting cell 32, this invention can even prevent the problem of wearing out the central parts of the lighting cell 32 too fast in prior art.
Besides, according to the invention, the discharge gap that dominates the driving characteristics of the lighting cell 32 is related to the distance between the scan electrode 34 and the auxiliary electrode 36 instead of the thickness of the shadow mask 30. Because the distance between the scan electrode 34 and the auxiliary electrode 36 can be easily controlled in the manufacturing process, the plasma display panel, according to the invention, can prevent the problem of varying driving characteristics in the prior art.
Another advantage of the invention is that the effect of the thickness of the shadow mask 30 to the firing voltage is substantially reduced. This is because the discharge gap that dominates the driving characteristics is related to the distance between the scan electrode 34 and the auxiliary electrode 36. Thus, increasing the thickness of the shadow mask to improve the lightness is not harmful to the surrounding driving circuits.
In practical applications, the plasma display panel, according to the invention, can further control the scan voltage provided to the scan electrode 34 to reduce electromagnetic interference. Referring to FIG. 6, FIG. 6 shows the scan voltages corresponding to two adjacent rows of lighting cells 32. During a second sustain period for lightening the jth lighting cell in the (i+1)th row of lighting cells 32, an (i+1)th scan voltage is applied to the (i+1)th scan electrode among the N scan electrodes 34. The (i+1)th scan voltage includes a second AC voltage. The amplitudes of the first AC voltage and the second AC voltage are substantially the same, and the first AC voltage and the second AC voltage are substantially out of phase. That is to say, during the sustain period, the amplitudes of the scan voltages corresponding to two adjacent rows of lighting cells 32 are the same, and the phase difference is about 180°.
FIG. 7 shows the respective current directions of two adjacent rows of lighting cells 32 when the electrodes discharge after providing the above scan voltages. As shown in FIG. 7, because the scan voltages of two adjacent rows of lighting cells 32 are out of phase, the current directions of two adjacent rows of lighting cells 32 are also opposite. In this way, the electromagnetic interference generated by two adjacent rows of lighting cells 32 will be cancelled out. Besides, the opposite current directions can reduce 50% of peak current for the entire circuit. This not only reduces the cost but also increases the lifetime of the plasma display panel. Moreover, this embodiment can also effectively suppress noise problems due to the opposite vibrating direction generated during the discharge of the noble gases.
In practical applications, the plasma display panel, according to the invention, can also change the shape of the scan electrode 34 and the auxiliary electrode 36 to further improve the lighting efficiency. FIG. 8 shows the scan electrode 34 and auxiliary electrode 36 after their shapes are changed. As shown in FIG. 8, each of the lighting cells 32 includes a first lighting region and a second lighting region respectively. The distances between the scan electrode 34 and the auxiliary electrode 36 corresponding to the first lighting regions are larger than those corresponding to the second lighting regions. That is to say, the discharge gap of the first lighting region is larger than that of the second lighting region in each of the lighting cells 32.
The advantage of this embodiment is that the parts with smaller discharge gap can provide lower firing voltage while the parts with larger discharge gap can generate higher lightness. The lower firing voltage area will generate discharge phenomenon earlier; on the contrary, in the higher firing voltage area, the generation time of discharge phenomenon will be later. By doing so, this embodiment can lower the discharge peak current to reduce the load of the circuit system. Besides, the electrode shape shown in FIG. 8 can disperse the current to enlarge the discharge area. This not only can increase the lifetime of the panel but also improve the lighting efficiency.
In practical applications, the front plate of the above mentioned plasma display panel can further include a first glass substrate, a transparent dielectric layer, and a first protective layer. The back plate of the plasma display panel can further include a second glass substrate, a dielectric layer, and a second protective layer.
Referring to FIG. 9A, FIG. 9A shows the shadow mask of another preferred embodiment according to the invention. In this embodiment, each of the lighting cells of the plasma display panel is divided into a first sub-cell 32A and a second sub-cell 32B. When a target lighting cell among the lighting cells is assigned to be lightened, both the first sub-cell 32A and the second sub-cell 32B of the target lighting cell are operated to be lightened. Dividing a lighting cell into two sub-cells can increase the spread area of the color phosphors and can improve the utilization efficiency of ultraviolet rays.
As shown in FIG. 9B, all the first sub-cells 32A and the second sub-cells 32B in the same row of the lighting cells can share a scan electrode 64 and an auxiliary electrode 66, and the scan electrode 64 is located between the first sub-cell 32A and the second sub-cell 32B, FIG. 9C shows another configuration of the scan electrode 64 and the auxiliary electrode 66 making the auxiliary electrode 66 be located between the first sub-cell 32A and the second sub-cell 32B.
According to the invention, the first sub-cells 32A and the second sub-cells 32B can also have their own scan electrodes respectively. That is to say, if a plasma display panel includes N rows and M columns of lighting cells 32, the front plate must include 2*N scan electrodes 34 and N auxiliary electrodes 36, and the back plate includes M address electrodes 38.
Referring to FIG. 10, FIG. 10 is a schematic diagram of the plasma display panel including 2*N scan electrodes 34. The first sub-cells 32A in the ith row of lighting cells 32 among the N rows of lighting cells 32 correspond to the (2i−1)th scan electrode 34 among the 2*N scan electrodes 34 and the ith auxiliary electrode 36 among the N auxiliary electrodes 36. The second sub-cells 32B in the ith row of lighting cells 32 among the N rows of lighting cells 32 correspond to the (2i)th scan electrode 34 among the 2*N scan electrodes 34 and the ith auxiliary electrode 36 among the N auxiliary electrodes 36. It is the same as the former embodiment that the jth lighting cell 32 in the ith row of lighting cells 32 corresponds to the jth address electrode 38 in the M address electrodes 38.
When the jth lighting cell 32 in the ith row of lighting cells 32 is assigned to be lightened, the (2i−1)th scan electrode 34, the (2i)th scan electrode 34, the ith auxiliary electrode 36, and the jth address electrode 38 are operated to generate discharge effects in the first sub-cell 32A and second sub-cell 32B of the jth lighting cell in the ith row of lighting cells 32.
The advantage of making the first sub-cells 32A and the second sub-cells 32B have their own scan electrodes 34 respectively is that the designer can adjust the scan voltages with more flexibility. FIG. 11 shows an example of the scan voltage corresponding to two adjacent rows of lighting cells during a sustain period.
In the example of FIG. 11, during a first sustain period for lightening the jth lighting cell in the ith row of lighting cells, a (2i−1)th scan voltage is applied to the (2i−1)th scan electrode, and a (2i)th scan voltage is applied to the (2i)th scan electrode. The (2i−1)th scan voltage includes a first AC voltage; the (2i)th scan voltage includes a second AC voltage. As shown in FIG. 11, the second AC voltage is lag in phase compared with the first AC voltage. The phase lag is smaller than π and is represented by ψ.
During a second sustain period for lightening the jth lighting cell in the (i+1)th row of lighting cells, a (2i+1)th scan voltage is applied to the (2i+1)th scan electrode among the 2*N scan electrodes, and a (2i+2)th scan voltage is applied to the (2i+2)th scan electrode among the 2*N scan electrodes. The (2i+1)th scan voltage includes a third AC voltage; the (2i+2)th scan voltage includes a fourth AC voltage. As shown in FIG. 11, the first AC voltage and the third AC voltage are substantially out of phase, and the second AC voltage and the fourth AC voltage are substantially out of phase.
The current peak of the entire circuit can be lowered by dispersing the times at which each of the scan voltages reaches the voltage peak; thus, the load of the circuit system can be reduced.
On the other hand, the ith auxiliary voltage and the jth address voltage are DC voltages. In practical applications, if each of the auxiliary voltages is designed to have the same value, the N auxiliary electrodes can be connected with each other.
With the above example and explanation, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Patent Application
20080042931
